Applied material: tin, tungsten, gold, silver, lead, zinc, tantalum, niobium, titanium, manganese, iron ore, coal, etc. Advantages: high concentration ratio of dressing, convenient adjustment and easy to get obvious separation.
The shaking table beneficiation can not only be used as an independent beneficiation method, but also is often combined with methods such as jigging, flotation, magnetic separation by centrifugal concentrator, spiral classifier, spiral chute and other beneficiation equipment.
The shaking table is mainly used for the separation of copper, tungsten, tin, tantalum, niobium, chromium, gold and other rare metal and precious metal ores. In addition, it is widely used in the separation of iron, manganese ore and coal. Before flotation, it was also used in the dressing of nonferrous ores.
It can be used for different operations such as roughing, concentration, sweeping, etc., to separate coarse sand (2-0.5 mm), fine sand (0.5-0.074 mm), sludge (-0.074 mm) and sand with other different particle sizes. It is very effective equipment for selecting fine-grained materials below 1 mm, especially below 0.1 mm.
The bed surface can be made of wood, FRP (glass fiber reinforced plastic), metals (such as aluminum, cast iron) and other materials. Common shapes of the bed surface are rectangle, trapezoid and diamond.
There is a feeding chute on the upper right of the bed surface, the length of which is about 1/3~1/4 of the total length. There are many small holes on one side of the feeding chute, so that the slurry can be evenly distributed on the bed surface.
Connected to the feeding chute is the flushing tank, which accounts for 2/3~3/4 of the total length of the bed surface. Many small holes are made on the side of the tank so that the flushing water can be evenly fed along the longitudinal direction of the bed.
The light mineral particles in the upper layer are subject to great impact force, and most of them move downwardly along the bed surface to become tailings. Accordingly, this side of the bed surface is called the tailings side.
The heavy mineral particles at the bottom of the bed move longitudinally by differential movement of the bed surface, and are discharged from the opposite of the transmission end to become concentrate. The corresponding position of the bed surface is called the concentrate end.
The horizontal and longitudinal effects of mineral particles of different densities and particle sizes on the bed surface are different. The materials finally spread out in a fan shape on the bed surface, and a variety of products of different quality can be obtained.
The amount of feeding ore is related to the granularity of the feed. If the ore grains are relatively coarse, the required amount of feeding ore is large. However, if it is too large, it will cause zoning problems. In this case, it is necessary to move the concentrate intercepting plate to increase the flushing water and the horizontal slope of shaking table surface.
The Cr2O3 content in a certain lean chromite ore in Zimbabwe is only 8.19%. Fote has conducted research on the beneficiation technology and equipment of the lean chromite ore, finally decided to adopt the beneficiation method: tail discharging by the strong magnetic separationfull-grain separation by shaking table. The indicators are relatively good.
Step 2 Then use Fote magnetic separator for strong magnetic separation to remove qualified tailings with a yield of 50.21%, and the tailing grade is only 2.19%. As a result, the amount of ore entering the shaking table is reduced by half, and the number of shaking tables is greatly reduced. At the same time, after throwing the tail, it creates favorable conditions for the sorting of the shaking table and further improves the sorting index.
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It is widely used in separating gold, tungsten, tin, tantalum, niobium and other rare metals and precious metal ore. Can be used for roughing, concentration, scavenging different operations, separating coarse sand (2-0.5mm), fine sand (0.5-0.074mm), slime (-0.074mm) of different grain grade. It can also be used to separate iron, manganese ore and coal. When processing tungsten, tin ore, the table effective recycles particle size range for the 2-0.22 mm.
The working principle of shaking table is to use the combined action of the specific gravity difference of sorted minerals, alternating movement of bed surface, and transverse oblique water flow and riffle, to allow loose layering of ores on the bed surface and fan-shaped zoning, then different minerals can be separated.
Shujin Li, Cai Wu, Fan Kong, "Shaking Table Model Test and Seismic Performance Analysis of a High-Rise RC Shear Wall Structure", Shock and Vibration, vol. 2019, Article ID 6189873, 17 pages, 2019. https://doi.org/10.1155/2019/6189873
A building developed by Wuhan Shimao Group in Wuhan, China, is a high-rise residence with 56 stories near the Yangtze River. The building is a reinforced concrete structure, featuring with a nonregular T-type plane and a height 179.6m, which is out of the restrictions specified by the China Technical Specification for Concrete Structures of Tall Building (JGJ3-2010). To investigate its seismic performance, a shaking table test with a 1/30 scale model is carried out in Structural Laboratory in Wuhan University of Technology. The dynamic characteristics and the responses of the model subject to different seismic intensities are investigated via the analyzing of shaking table test data and the observed cracking pattern of the scaled model. Finite element analysis of the shaking table model is also established, and the results are coincident well with the test. An autoregressive method is also presented to identify the damage of the structure after suffering from different waves, and the results coincide well with the test and numerical simulation. The shaking table model test, numerical analysis, and damage identification prove that this building is well designed and can be safely put into use. Suggestions and measures to improve the seismic performance of structures are also presented.
With the fast urbanization in China, the population growth in cities has led to ever-increasing demand for high-rise buildings to accommodate commercial and residential needs. High-rise buildings are very common in the densely populated cities all over the world, such as New York and London [1, 2]. Accordingly, pertinent regulations have been developed to ensure the safety and reliability requirements of high-rise buildings. High-rise buildings that are designed and constructed according to codes and standards are deemed as complied with all regulatory requirements for the buildings. With the innovation and advancement of technology and materials, some high-rise buildings are planned and designed beyond the specifications of codes and standards, particularly for fast-developing countries such as China. To ensure the safe and reliable function of these buildings, it is imperative to investigate the behaviors of these buildings, in particular, the behavior under horizontal loadings such as wind and earthquake. It is also essential to identify and quantify if possible the characteristics of these buildings with a view to provide guidance for the future design of similar buildings.
The shaking table test is one of the most widely used techniques to assess the seismic performance of structures made of various materials. Commonly, it is widely used for assessing linear/nonlinear and elastic/inelastic dynamic response of structures. Martinelli et al.  presented the nonlinear dynamic response of a shaking table test for a full-scale seven-story reinforced concrete shear wall building, where four simulated earthquake records with increasing intensity were used as excitation. Saranik et al.  conducted a shaking table test to investigate the inelastic behavior of a two-story steel portal frame with bolted connections. Furthermore, it is not only used for structural dynamic tests but also for geotechnical behavior. Chen et al.  conducted a series of shaking table tests on a plaster model of a three-story and three-span subway station to investigate the seismic failure characteristics of the structure on the liquefiable ground. Lin et al.  undertook shaking table tests on three embankment slope models to study the seismic response of the embankment slope with different reinforcing schemes. The effectiveness of shaking table tests has also been studied. For example, Srilatha et al.  investigated the effect of frequency of base shaking on the dynamic response of unreinforced and reinforced soil slopes through a series of shaking table tests.
In shaking table tests, most researchers used scaled models as specimens. For example, Liu et al.  carried out shaking table tests on a 1/30 scaled model with and without base isolation bearings to assess the seismic performance of an isolated museum structure in high earthquake intensity regions. Lu et al.  tested a 1/50 scale high-rise building model on a shaking table for Shanghai World Financial Center Tower. The dynamic characteristics, seismic responses, and failure mechanism of the structure were investigated, and weak positions under seldom-occurred earthquakes were identified. Some researchers use prototype structures. For example, Lignos et al.  conducted a shaking table test on a full-scale high-rise building to demonstrate the effectiveness of the numerical models used. Graziotti et al.  performed a shaking table test on a two-story full-scale unreinforced masonry building to study its response, characteristics, damage mechanism, and evolution during the experimental phases.
The above literature review suggests that the shaking table test is an essential tool to assess and verify the dynamic behavior of structures. It is particularly imperative for those structures that exceed the limits of the specification of design codes and standards. It is with this regard that the present paper is in order. The Shimao Building (numbered 13 in the A2 block) is an iconic building in the central business district area of Wuhan, China, located on the bank of Yangtze River. It is a combined commercial and residential building with 56 stories. The lateral-force resisting system of the structure is the reinforced concrete (RC) shear wall with a height of 179.6m, exceeding the limit for high-rise buildings specified by Chinese Regulation Technical Specification for Concrete Structures of Tall Building (JGJ3-2010) . Therefore, it is required to verify the structural seismic performance after the regular structural designing according to the codes. Besides, the irregular building shape in both plane and elevation complicates the analysis and determination of seismic resistance of the structure. To ensure the safety of the building, it is necessary to examine the behavior of the building under seismic loading. For this purpose, a shaking table test and its numerical analysis as well as structural damage identification were also conducted.
This paper focuses on the investigation of the seismic behavior of Shimao Building. Firstly, the results of a shaking table test on the 1/30 scale building model will be presented. The structural dynamic characteristics and the responses under different levels of earthquake loading will be investigated, and the failure mechanism and cracking pattern of the tested model will also be obtained. Then, the corresponding finite element model will be established to analyze its seismic performance. At last, a damage identification method based on the autoregressive (AR) model will also be presented to identify the damage of the test building. According to the analysis of experiment, finite element model, and theoretical identification of the test building, seismic performance of the prototype building will be obtained, and this study can make sure that the prototype building is designed reasonably and can be put into use safely. Finally, suggestions and measures to improve the prototype building seismic performance will also be presented.
A 1/30 model of Shimao Building was designed and built for the shaking table test to represent the main characteristics of the prototype building. The experiment was undertaken in the laboratory of School of Civil Engineering and Architecture at Wuhan University of Technology, China. Figure 1 shows the representing plan and elevation of the prototype building. It can be seen from Figure 1(b) that the plan of the building is shaped as T (maximum 32.85m in length and maximum 19.5m in width), and this shape of building may be susceptible to earthquake excitation. The vertical configuration of the building consists of a core tube accommodating staircase, lift well, and pipe shaft and shear walls located at the outer walls and some inner walls. The floors and roof of the building are reinforced concrete beam-slab structures. In addition, the upper (vertical) structure is fixed on the reinforced concrete base.
According to the Technical Points (No. 65, 2015) of Special Inspection for Seismic Fortification of Out-of-Code High-rise Buildings , issued by the Chinese Construction Ministry, the total height of the building 188.6m (including the roof truss) with 56 stories exceeds the limit height of 170m specified by the Class B shear wall structures according the Chinese code (JGJ3-2010) . Furthermore, the building has a set back at the height of 128.35m (the 41st story), as shown in Figure 1, leading to a disagreement between the centroid and stiffness center. As a consequence, the eccentricity violates the requirements of seismic conceptual design that building structures should be symmetric in both plan and elevation. Overall, a shaking table test of this building can be quite necessary.
Dynamic characteristics of the prototype building were calculated through Chinese structural design software PKPM. Although the maximum seismic responses of the structure under Frequent 6 (defined at Section 3), shown in Table 1, satisfy the requirements of the code (specified by the Chinese Seismic Design Code of Building Structures), considering larger earthquakes happen and making extra certain, the shaking table test is still needed for further verification.
In this paper, the similitude law is determined by the dimensional analysis method . Firstly, similar conditions are obtained, and then other similarity constants are obtained based on . Inertia force, restoring force, and gravity are required to be simulated in the test, and thus, elastic modulus and density of the model material are strictly controlled. The essential requirement is , where the subscripts and represent the scaled model and the prototype building, respectively. That is,where , , , and denote the similitude ratio of elastic modulus, equivalent density, acceleration, and geometry, respectively. In the present case, three controllable similitude ratios should be determined in advance to obtain others. Specifically, , , and are chosen in this paper, and thus, can be calculated using Equation (1).
Considering the shaking table size and the height requirement of the laboratory, the dimension scaling parameter is chosen as 1/30. Based on the tested characteristics of materials in the test, the similitude law of elastic modulus is determined as 1/3.05. The total weight of the model (including self-weight and artificial mass) and prototype building are 3.06ton and 40400ton (including live load), respectively. Thus, the mass ratio is 1/13202.6, and the similitude ratio of equivalent density can be obtained as 2.0245; all the main model similitude relationships and calculation formulas are shown in Table 2.
Since the aim of the shaking table test is to investigate the seismic behavior of the original structure subjected to different intensity of earthquakes, including failure mode and mechanisms, it is necessary to use the same materials as the prototype building. The materials used for model construction (specimen) are microconcrete (mix proportion is shown in Table 3), galvanized steel wires, and meshes which are similar to the materials in the prototype building. Ordinary Portland Cement P.O. 32.5 is chosen to construct concrete. A batch of specimens in the form of cubic and prism type were cast to measure the strength and elastic modulus of microconcrete. The testing method of the specimens strictly followed the requirements of the Standard for Test Methods of Concrete Structures (GB50152-2012) . The microconcrete mix proportions are shown in Table 3. The elastic modulus of materials is shown in Table 4. The height of the model is 6.437m, with 6.287m for the model itself, and 0.15m for the base. The photo of the completed model is shown in Figure 2.
The test variables include two types: different fortification intensity and different types of earthquake waves. According to related researches on the statistics of the peak acceleration of ground motions in China, the seismic intensity of a specific site exhibits the extreme distribution of the III type (Weibull distribution). The fortification intensity is defined as the intensity with 10% exceedance probability, which is also called as the moderate or basic intensity for simplicity. Similarly, the rare and frequent intensity is defined as the intensity with 23% and 65% exceedance probability, respectively. Furthermore, for the moderate intensity of a specific site, the frequent and rare intensity is about 1.55 lower and 1 higher than the moderate intensity, respectively. In this paper, the scaled building under investigation is located in Wuhan with Degree 6 as the fortification/basic intensity . This intensity is associated with medium occurrence (10%). Therefore, Moderate 6 means ground motion with Intensity 6 (the peak ground acceleration (PGA) is 0.05g) and Frequency 6 means ground motion with Intensity 4.45 (PGA 0.018g), whereas Rare 6 means ground motion with Intensity 7 (PGA 0.1g). Ultralarge earthquakes are not specified in GB50011-2010 , and Rare 7 (actually Intensity 8) is introduced here for the purpose of studying the nonlinear or even collapse performance of the scaled building. For a chosen recorded seismic excitation, the similitude law (shown in Table 1) was used to scale the acceleration and time.
According to the dynamic characteristics and site condition of the prototype structure, three seismic runs are chosen for simulating the shaking table test input wave: (1) El Centro wave, with a peak acceleration of 3.41m/s2; (2) Taft wave, with a peak acceleration of 1.53m/s2; and (3) artificial seismic wave (USER1), supplied by the construction designers, with a peak acceleration of 0.18m/s2. The time-history curves are shown in Figure 3. The main specifications of the shaking table used in the present experiment are shown in Table 5.
The testing procedure is shown in Table 6. It can be seen that the EI Centro wave is the first wave in each test condition, followed by the Taft wave and artificial seismic wave. Before and after inputting different fortification intensity seismic waves, low peak white noise excitation is conducted to measure the dynamic characteristics parameters such as natural frequency, mode, and damping ratio.
The main measurement of structural response is acceleration, displacement, strain, etc. Several acceleration sensors, displacement sensors, and strain gauges are arranged at the different heights of the model to measure the responses of the model structure under different seismic fortification intensities. Accelerations and displacements were measured by the large dynamic signal acquisition and analysis system DASP2003, developed by Orient Institute of Noise and Vibration. 14 acceleration sensors were used for different purposes, namely, 2 for measuring vertical accelerations, 10 for horizontal accelerations, and 2 for torsion of the building. Dynamic strain was obtained by the dynamic and static testing instrument DH3817. Five displacement sensors were used to measure the deformation along the direction of shaking. The positions of acceleration sensors and displacement sensors are shown in Figure 4.
When subjected to Frequent 6, there were no noticeable shaking and visible damages, it can be predicted that the test model can remain in a serviceable condition after Frequent 6, and there was no damage. In the case of Moderate 6, the model responded with little vibration, but no cracks and structural damages, which may indicate that the model is still in serviceable conditions, and there was no need to strengthen. No visible cracks and significant damages occurred after Rare 6. However, the model responded with more vibrations and little crack, which indicated that the model was minor damaged, even though the test building was still in the serviceable condition. Some part of it might need to be repaired. When subjected to Rare 7, it is observed that the model vibrates significantly, together with a large number of cracks in the upper part of the model and spalling of concrete. It can be concluded that the test building is not collapsed even when subject to Rare 7 but lost much of its lateral load resisting capacity. Since the prototype building is represented as the model, the damage pattern of the prototype building can be obtained. The damage of different floors after the test is shown in Figure 5.
Low peak white noise excitation was used before and after seismic excitation for capturing the dynamic characteristic of the model. Results are shown in Table 7. It can be seen that the natural frequencies of the test model maintain the same under Frequent 6, indicating linear behaviors of the structure in this stage. Furthermore, the second- and the third-order frequencies of the test model decreased slightly after Moderate 6, reflecting slight decrease of the structures stiffness. Next, after Rare 6, the natural fundamental frequency decreased by 3.9%, indicating that damages may occur at a certain lateral-force resisting component of the model structure. Finally, after Rare 7, the natural frequencies of the test model decreased significantly. It can be inferred that the 1st mode of the prototype structure is the Y direction, the 2nd mode is the X direction, and the 3rd mode is torsion. The ratio of the 1st mode periods between torsion to the Y and X direction is 0.33 and 0.49, respectively, which is far smaller than the limit value 0.85 given by the Chinese code (JGJ3-2010) . Furthermore, after analyzing the structure stiffness degradation curves in accordance with the 1st order natural frequencies of the model, it can be obtained that the stiffness of the structure declines with the increasing magnitude of earthquake excitation, with a minimum stiffness to 81.9%.
Acceleration amplification factor is the ratio of the maximum absolute value of acceleration response of each story to the maximum input acceleration at the bottom of the model. This factor is of great significance to analyze the seismic performance of structures, describing how many times the accelerations at each story are amplified compared to the base seismic excitation. Hence, the acceleration amplification factor can be obtained through dividing the peak accelerations of the testing stories by the peak accelerations of the shaking table in this test. Then, the envelope diagram of the building in different test conditions can be drawn. Figure 6 shows the envelope of acceleration amplification factors in the main vibration direction (Y direction) with different seismic intensities, and the peak acceleration of some floors in a specific condition and acceleration amplification factor are listed in Table 8.
As can be seen, the acceleration amplification factors along the floors of the structure are nearly invariable except for the top floor, reflecting the lateral stiffness at different floors (except for the top floor) is uniformly distributed. Furthermore, the acceleration amplification factor was almost unchanged after suffering from Frequent and Moderate 6, which indicated that the lateral-force resisting components of the model are seldom damaged. However, the acceleration amplification factor increases sharply on the top floor and roofing layer, indicating that the whiplash effect cannot be ignored in this case. Usually when damages are increasing, the stiffness of structures is reducing, leading to the elastic-plastic phrase, which can result in a smaller acceleration amplification. It can be seen in Figure 6 that the acceleration amplification factor of the same floor continued to decrease with an increasing excitation intensity, reflecting a decreasing structural lateral stiffness and an increasing degree of damage as the seismic intensity increases. However, the decline of the acceleration amplification factor was not obvious after suffering from Rare 6, which indicated that some lateral-force resisting components of the model have already be damaged. Thus, the experimental phenomenon coincided well with the theory.
The displacement response of the model was converted to the displacement response of the prototype by a similar law. The formula to translate the maximum displacement response from the test model to the prototype building should be as follows:Di is the maximum displacement of the prototype on the ith floor, Dmi is the maximum displacement of the model at ith floor, mg is the maximum acceleration of the shaking table determined by the similitude law, ig is the maximum acceleration of the shaking table measured during the test, and Sd is the displacement similarity coefficient.
The maximum displacement and corresponding displacement angle of the prototype structures roof under different seismic levels are listed in Table 9. It can be seen that as the seismic wave intensity increases, both the maximum displacement and displacement angle of the roof increase. Both the maximum displacement and displacement angle of the prototype structure can meet the requirements of the Chinese code (JGJ3-2010) . The prototype building will not collapse and even have a relatively good integrity after severe earthquake action.
Figure 7 shows the envelope diagrams of maximum displacement in the Y direction of the prototype structure along the floors. It can be seen that the displacements of the prototype structure increase as the stories increase. Furthermore, the effect of the El Centro wave was significantly larger than that of the other two waves. Owning to the whiplash effect, the displacement response of the top floor and roofing layer is much larger than that of other floors. The lateral displacement curves under Frequent and Moderate 6 were not flat, which was small and had obvious bending shear deformation characteristics. So the structure had not been damaged yet. The lateral displacement curves under Rare 6 and 7 were relatively flat and obvious, which means that some components have already been damaged, and the stiffness of the structure has declined.
The story drift of representative floors under different seismic waves is listed in Table 10. It can be seen that all the maximum story drift of the structure occurred in the top of the structure, especially on the 56th floor, which means that the upper part of the structure is relatively weaker than others. The stiffness is reduced as the structure becomes smaller above 41st floors, which leads to the increase of story drift. All story drifts of the structure under the testing earthquakes are smaller than the value specified in the Chinese code (JGJ3-2010) , which indicates that the structure can meet the seismic resistance requirements of the code.
There are symmetrical accelerometers arranged at the 41st and the top floor. The displacements under different seismic intensities of these two stories can be obtained by integrating the accelerations. Hence, the torsion can be obtained by the ratios of the displacements to the sensors distances. Torsion angle of the model under different seismic levels is shown in Figure 8. It can be seen that the torsion deformation is small before the inputting of Rare 6, reflecting a good torsional stiffness. However, the torsion deformation became larger under Rare 7, which indicates that some part of the structure has been damaged.
According to transformation formula, the hysteresis curve of the prototype structure under different earthquake levels can be obtained by the displacement historical response and shear historical responses. The shear responses can be calculated by quality distribution of floors and corresponding acceleration responses. Taking Rare 6 as an example, considering the limited pages of this paper, the hysteresis curve under different waves is shown in Figure 9. Actually, the hysteresis curve of the structure under Frequent, Moderate, and Rare 6 change with the external excitation while the change of stiffness is however not obvious, which indicates that the building is basically in the elastic working stage. However, it can be seen that the hysteresis curve becomes irregular under Rare 7, which indicates that some parts of the structure have already been damaged and the structure has gone into the elastic-plastic phase.
In order to verify the experimental results, a finite element model of the test model was established by ANSYS. Elastic-plastic analysis of the test model was conducted. Three-dimensional BEAM4 element was used to simulate the beams and embedded columns, and SHELL63 was used to simulate the floors and shear walls. The material properties were obtained from the measured tests, and the nonlinear performance of materials had been considered. The input seismic waves used in the finite element model were the same as the shaking table test. Real properties of the materials of the model had been taken into account. The finite element mode contained 78899 nodes, beam elements 4599, and shell elements 72414 totally. The height is 179.4m, which is the same as the prototype building.
The results of the finite element analysis indicate that first three order vibration modes of the model include the translation mode in Y direction, X direction, and torsion mode. The first three order vibration modes are shown in Figure 10. All the three vibration modes reflect the coupling between translation and torsion.
Table 11 shows the free vibration characteristics of the model in experimental results and finite element simulation results. It can be seen that the finite element simulation result of the first periods and second periods is similar to those of experiment results, and divergences between the two are 0.07% and 2.41%, respectively. However, the divergences of the third periods became much more significant, which is still within an acceptable level. The ratio of the first mode periods between torsion and translation in the Y direction is 0.38 in the finite element simulation, while the test result is 0.33. Both the two results are far less than the limited value of the Chinese code (JGJ3-2010) . Moreover, the influence of higher vibration modes to the structure can be quite large because of the high aspect ratio for high-rise buildings. It is usually difficult to capture the higher vibration modes of the building by an experiment, and the computational analysis thus shows its advantage and is an important supplement. The first 30 vibration modes and periods were analyzed through the finite element method. It can be concluded that the vibration modes became localized after the 15th order, and the vibration of the top model is much more obvious than others, which indicates that the whiplash effect is quite remarkable. Based on mass participation ratio and vibration maps, it can be concluded that the vibration mode of the structure is coupled translation and torsion, and the torsion has great influence on the seismic response of the structure.
It can be seen in Table 12 that both the acceleration amplification factor of the finite element model and experimental model continued to decrease after suffering from Frequent 6, Moderate 6, and Rare 6, reflecting that the lateral stiffness of the structure has decreased and the damage of the structure increased. The acceleration response of finite element simulation is similar to the shaking table test.
In order to compare the experimental results with the calculated results, the maximum displacement of the test floors under different earthquake levels is listed in Table 13. The envelope of interstory drift under different earthquake waves is shown in Figure 11.
It can be calculated that both the story drift angle of the finite element model and test model under Frequent and Moderate 6 can meet the seismic resistance requirements in the code specification (1/800). The maximum story drift angle of the finite element model under Rare 6 is 1/350, which is larger than the limited elastic value; however, it still can meet the requirements of plastic story drift angle in the Chinese code (JGJ3-2010) . As can be seen in Figure 11, all the peak story drift occurs in the upper part of the structure, especially near the 50th floor, which is relatively weaker than the other parts of the structure. Furthermore, story drift has increased above 41st floors, reflecting a decline of the stiffness, which coincides well with the experimental analysis. Hence, we can reach the conclusion that all the results of finite element simulation coincides well with the results of the experiment, which indicates that both the finite element simulation, and the shaking table model test are reasonable.
In this section, an identification method based on the AR model is presented to identify the damage location and degree of the test model after suffering from simulated earthquakes. Firstly, the AR model is briefly introduced and established by the acceleration response of the test model. Secondly, the plain version of the least squares (LS) method is used to solve the unknown parameters of the established AR model. Then, a judging factor based on the residual variance of the AR model is proposed to estimate the degree of structural damage. Finally, the proposed damage factor of the model building after different earthquake intensities is calculated by MATLAB. The damage location and degree identified by this method are compared with the testing results as well as the numerical results.
The AR model is widely used in the field of structural damage identification , and it is attempt to account for the correlations of the current time parameter with its predecessors in time series, in which the output variable depends linearly on its own previous values and on a stochastic term. It can be implemented to represent the dynamic response of structures . The AR model does not need any specific structural characteristics but the output response data; hence, it is widespread for complex structures [20, 21]. In this research, the AR time-series model is used to describe the acceleration time histories of the shaking table. A noisy AR model of order is described by equation :where is the output of the AR model, it is the discrete-time signal, and in this paper, the acceleration responses are used. is the random noise. is the unknown order of this model at prior and varies from 0 to . denotes the AR coefficients, which need to be estimated. This model can be simplified as follows :where , , and .
However, finding out the optimal order of the AR model is not trivial. The order is not as larger as better. When the order of the AR model increases, the residual sum of squares theoretically decreases, while the calculating errors rise. Therefore, these two aspects should be both considered in the modeling. In literature, there are some criterions achieved this goal , such as Akaikes Information Criterion (AIC) or Bayesian information criterion (BIC), proposed by Akaike and Schwarz, respectively. The AIC will be used in this paper, and it is presented as follows:where is the estimated variance of residual errors when the order of the AR model is .
After the unknown parameter of the AR model is obtained, a factor needs to be proposed to judge the damage of the structure. The step of the method can be clarified as follows:(1)Dividing the obtained response acceleration data before damage into two parts, part and part , serves as benchmark data, from which of the undamaged situation will be estimated. While serves as the unknown inspection data to be estimated in the healthy state of structure.(2)Estimating by equation (5) and the residential of based on by equation (6).(3)Dividing all the observed data into part and . Estimating the residential of and of based on the obtained .(4)Calculating the average of and to obtain . represents the final residential of observed data to be estimated after damage.(5)The damage identification factor is calculated as the ratio between the residential variance of to , shown as
It is clear that if the data to be estimated is coming from the undamaged structure, IF will be close to one. Otherwise, will be larger than ; that is, the IF will increase as the damages of the structure rise.
In this part, the IF of different stories and seismic intensities will be presented. It can be seen in Table 6 that before and after all the testing waves, the white noise is used to test the model; hence, the identification of white noise will be conducted here. Figure 12 lists the IF after different earthquake intensities of some representing floors based on the white noise excitation. It can be concluded that the IF becomes larger as the intensity of earthquake increases, indicating that the damage of the test building rises while intensity increases. Furthermore, the IF of the top story is larger than that of other stories, reflecting the whiplash effect too.
When comparing the damages of all stories after the same seismic intensity, the damage variation along stories can be studied. For the sake of simplicity, Figure 13 shows the IF along some stories, taking the white noise response after suffering from Frequent 6 and Rare 7 as examples here.
It can be concluded that after Frequent 6, all the IF ranges from 1.0 to 1.25, indicating very little damages occurred in the model building. Even though the IF of the 1st floor and top floor is the smallest and largest respectively, there is only a little difference. However, after suffering from Rare 7, the damage increases obviously, the damage degree of 50th, 52nd, and top floors is larger than that of other floors, and the damage of 14th, 28th, and 8th stories is quite significant as well, while the damage of the first story is the smallest. This variation can also be found in Table 8 of the peak acceleration and acceleration amplification factors. The IF of 41st floor is not quite large but increased rapidly above 41st floor, indicating that the 41st floor is not in a serious damage condition as the floors above. This is not limited to the earthquake intensities in Figure 13, and the same conclusion can be drawn after analyzing all the white noise response data of the model building.
Moreover, after studying the IF of the three types of waves used in the test, the variation of IF is nearly the same with that of white noise, and the results will not be detailed here. However, the comparison of the effectiveness between different types of waves cannot be obtained, probably due to no relative data to be used to calculate the healthy residential of benchmark data ().
To summarize, we can reach the conclusion that the identification results are reasonable and coincide well with the results of the experiment and numerical simulation, which indicates that the identification method presented here is effective, and not only the location but also the degree of the damage can be identified by the new identification factor.
The prototype building is represented as the testing model in this paper. Based on all the analysis, it can be concluded that after Frequent 6, almost no changes occur in the structure which is still in the elastic stage. After Moderate 6, no visible damages occur, and natural frequency decreased slightly, which indicates that the stiffness of the prototype building was changed slightly in this condition. However, under Rare 6, the 1st natural frequency decreased by 3.9% and other parameters had little of changes, which suggests that some part of the prototype building will be damaged in this condition. Under Rare 7, visible cracks and spalling of concrete occur, and the natural frequency of the model decreased significantly, which means that the prototype building has been damaged significantly in this condition.
Acceleration response of the top part of the structure is relatively large, which indicates that the whiplash effect of the building is significant. The torsional deformation is not apparent when an earthquake is small, but it became more substantial when the level of input earthquake increased, which indicates that the effect of torsion on seismic response of the structure is increased. Furthermore, the effect of torsion is large above the 41st floors, especially on the 52nd floor, showing that these floors may be weaker than other parts relatively. However, as for the same level of earthquake intensity, the maximum displacement, displacement angle, story drift, and torsional angle of the model caused by the El Centro wave are the largest among the three types of input waves, followed by the Taft wave and artificial seismic wave. Thus the El Centro wave may be the most dangerous wave to the prototype building.
Finite element simulation results coincide well with the experimental results. Higher vibration modes of the building show that vibration modes have become localized after 15th order, and the vibration mode of the structure is translation-torsion coupled; the whiplash effect at the top of the structure is quite remarkable.
The damage degree and location identified by the proposed factor in this paper also show that the upper part of the building has more damage than the lower part, but the damage of 8th28th floor is also quite significant. With the increase of the earthquake acceleration, the damage of the building increases apparently. The identification results indicate that the identification method is effective and can be used in other similar cases.
The results of the test, the numerical analysis, and the identification prove that the building in the A2 block developed by Wuhan Shimao Group was designed reasonably, which can entirely meet the requirement in the Chinese Code and can be safely put into use. Even though the design of this building can meet the seismic design requirements, some measures should be taken to improve the seismic performances. Firstly, the connection between the shear wall of the bottom floor and the base can be strengthened to avoid horizontal joined-up cracks under big earthquakes. Then, the effect of torsion is large above the 41st floor of the building, but the damage of the 8th28th floor cannot be neglected either. More structural reinforcements may be necessary for these floors. The top of the structure also needs to be strengthened since the whiplash effect is obvious.
Copyright 2019 Shujin Li et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The RP-4 shaker table is the most widely used and most successful gold gravity shaking concentrating table worldwide, used by small and large mining operations and the hobbyist. The patented RP-4 is designed for separation of heavy mineral and gemstone concentrate. The RP-4 table can process up to 600 (typically 400) lbs. per hour of black sand magnetite or pulverised rock with little to no losses. The RP-4 uses a unique reverse polarity of rare earth magnets, which will cause the magnetite to rise and be washed off into the tails. This allows the micron gold to be released from the magnetite, letting the gold travelling to the catch. The RP-4 is compact and weighs 60 lbs. With a small generator and water tank, no location is too remote for its use. The RP-4 is a complete, ready to go gold recovery machine. THERE ARE NO SCREEN INCLUDED with the small shaking table. Use was reservoirsgreater than 250 gallon and recycle all your water. Only 400 Watt of power drawn by typical pump. The small RP4 gold shaking has a mini deck of 13wide x 36 long = 3.25 square feet of tabling area. The RP-4 is the best and longest selling small miner shaker table still on the market today. With many 1000s of units sold during the last 10 years! Review the RP-4 Operating Manual and Installation Guide lower on this page.
The RP-4 uses a unique reverse polarity of rare earth magnets which will cause the magnetite to rise and be washed off into the tails and allowing the micron gold to be released from the magnetite leaving the gold travelling to the catch.
When assembling the RP-4, it is very important to set it up correctly to get the best recovery. The unit needs to be bolted preferably to a concrete pad or bedrock when in the field. It can be weighted down with seven or eight large sandbags. Wooden stands will set up harmonics and vibrations in the unit. Vibrations will create a negative effect on the concentrating action of the deck and create a scattering effect on the gold. We would strongly advise getting the optional stand to mount it. See a detailed RP4 Shaker Table review.
Once you have the RP-4 mounted or weighted down, you will want to level it, place a level under the machine on the bar running attached to the two mounting legs. Use washers to get a precise level adjustment. Once mounted and leveled, use the adjustment screw to adjust the horizontal slope of the deck. It took me about 10 minutes of playing with the adjustment till you are satisfied the slope angle was where it needed to be. A general rule for good recovery is less grade for the table deck and as much water as possible without scouring off the fine gold particles.
When the table is set, wet down your black sand concentrates with water and a couple drops of Jet-Dry to help keep any fine gold from floating off the table. You are now ready to start feeding the RP-4.
DO NOT dump material into the feed tray. You want a nice steady feed without overloading the table. Use a scoop and feed it steadily. Watch the back where the small gold should concentrate. If you see fine gold towards the middle, adjust your table angle just a bit at a time till it is where it needs to be.
Run a few buckets of black sand tailings that already panned out just in case there might have been some gold left behind. Its a good thing, too, because I pulled almost three pennyweights of gold out of my waste materials. Thats a pennyweight per bucket!
You could run all of you concentrates over this awesome little RP-4 Gravity Shaker Table. Some ran bottles No. 1 and No. 2 over the table a second time and cleaned it up some more, getting out almost all of the sand in No. 1 and removing more than half the sand from No. 2. It was amazing to see a nice line of fine gold just dancin down the table into the bottle. And, to think you were was about to throw away all of that black sand that still had color in it! This machine is small enough for the prospector and small-scale miner who, like me, wants all of the gold for his or her hard work. The 911MPE-RP-4 Gravity Shaker Table is also big enough to clean up bucket after bucket of concentrates from a big operation! The RP4 people came up with the solution for getting all of the gold!
All RP4 shaker tables operate best when firmly secured to a dense solid mounting base. Wooden stands will set up harmonics and vibrations. Dense concrete or solid bedrock is preferred or a heavy braced steel table sitting on concrete. Mount shaker table to solid bed rock if possible when operating in the field. When that is not an option, six or seven sand bags may also be used if concrete or bedrock is not available for mounting.
Place a level on top of the steel bar that extends between the two bolts down mounting feet.Use flat washers installed under either end of the mounting feet for precise level adjustment in the long axis.
At no time should sand or slime be re-circulated back with mill water. Large, calm, surface areas are required to settle slimes. Buckets, barrels or any deep containers with turbulent water will not allow slimes to settle. Tailings should discharge into a tails pond or into a primary holding vessel before entering slime settling ponds. Surface area is more important than depth. A small 10 x 20 ft. settling pond can be installed in about 30 minutes. Shovel a 6 high retainer wall of earth and remove all gravel. Lay a soft bed of sand in the bottom. A small raised wall area (with the top approximately 2 blow water level) should be placed around the pump area. Roll out plastic liner and fill with water. Desert areas require a plastic cover to retard evaporation. Use a 24 wood across pond and lay plastic.
As with ponds, at no time should sand or slime be re-circulated back with mill water. A calm surface is needed in the final two barrels to settle slimes. (In lieu of the last two barrels, the discharge from barrel two may be directed to a settling pond as outlined above.)Turbulent water will not allow slimes to settle. Tailings are discharged into the first container.
A small compact tailings thickener introduces tailings feed at a controlled velocity in a horizontal feed design that eliminates the conventional free settling zone. The feed particles quickly contact previously formed agglomerates. This action promotes further agglomeration and compacting of the solids. Slowly rotating rakes aid in compacting the solids and moving them along to the discharge pipe, these solids are eventually discharged at the bottom of the unit. Under flow from the thickener 60-65% solids are processed through a vacuum filter and a90-95% solids is sent to the tailings area. Tailings thickeners are compact and will replace ponds. A 23 ft. diameter will process flow rates at 800 gpm or 50 tph.
Pine oils and vegetation oils regularly coat the surface of placer gold. Sometimes up to 50% of the smaller gold will float to the surface and into the tails. The pine oil flotation method for floating gold is still in use today. A good wetting agent will aid in the settling and recovery of oil coated gold.
Separation of concentrate from tails Minerals or substances that differ in specific gravity of2.5 or to an appreciable extent, can be separated on shaker tables with substantially complete recovery. A difference in the shape of particles will aid concentration in some instances and losses in others. Generally speaking, flat particles rise to the surface of the feed material while in the presence of rounded particles of the same specific gravity. Particles of the same specific gravity but varying in particle size, can be separated to a certain extent, varying in particle size, can be separated to a certain extent, removing the larger from the smaller, such as washing slime from granular products.
Mill practice has found it advantageous in having the concentrate particles smaller than the tailing product. Small heavy magnetite particles will crowd out larger particles of flat gold making a good concentrate almost impossible with standard gravity concentrating devices. The RP-4 table, using rare earth reverse polarity magnets, overcame this problem by lifting the magnetite out and above the concentrate material thus allowing the magnetite to be washed into the tails. This leaves the non-magnetics in place to separate normally.
No established mathematical relationship exists for the determination of the smallest size of concentrate particle and the largest size of tailing particle that can be treated together. Other factors, such as character of feed material, shape of particles, difference in specific gravity, slope or grade of table dock and volume of cross flow wash water will alter the final concentrate.
Size of feed material will determine the table settings. Pulverized rod mill pulps for gravity recovery tables should not exceed 65-minus to 100-minus 95% except where specific gravity, size, and shape will allow good recovery. Recovery of precious metals can be made when processing slime size particles down to 500-minus, if the accompanying gangue is not so coarse as to require excessive wash water or excessive grade to remove the gangue, (pronounced gang), to the tails. Wetting agents must be used for settling small micron sized gold particles. Once settled, 400-minus to 500 minus gold particles are readily moved and saved by the RP-4shaker table head motion. Oversized feed material will require excess grade to remove the large sized gangue,thus forcing large pieces of gold further down slope and into the middling. Too much grade and the fine gold will lift off the deck and wash into the tailings. Close screening of the concentrate into several sizes requires less grade to remove the gangue and will produce a cleaner product. A more economical method is to screen the head ore to window screen size (16-minus) or smaller and re-run the middling and cons to recover the larger gold. This concept can be used on the RP-4 shaker tables and will recover all the gold with no extra screens. A general rule for good recovery is less grade for the table deck and as much was water as possible without scouring off the fine gold. Re-processing on two tables will yield a clean concentrate without excess screening. Oversized gold that will not pass through window screen size mounted on RP-4 shaker tables, will be saved in the nugget trap. Bending a small 1/4 screen lip at the discharge end of the screen will trap and save the large gold on the screen for hand removal.
On the first run, at least one inch or more of the black concentrate line should be split out and saved into the #2 concentrate bin. This concentrate will be re-run and the clean gold saved into the #1 concentrate pocket. Argentite silver will be gray to dull black in color and many times this product would be lost in the middling if too close of a split is made.
The riffled portion of the RP-4 shaker table separates coarse non-sized feed material better than the un-riffled cleaning portion. Upon entering the non-riffled cleaning plane, small gangue material will crowd out and force the larger pieces of gold further down slope into the middling. Screen or to classify.
The largest feed particles should not exceed 1/16 in size. It is recommended that a 16-minus or smaller screen be used before concentrating on the RP-4 shaker table, eliminating the need for separate screening devices. Perfect screen sizing of feed material is un-economical, almost impossible, and is not recommended below 65-minus.
A classified feed is recommended for maximum recovery, (dredge concentrates, jig concentrates, etc.) The weight of mill opinion is overwhelmingly in favor of classified feed material for close work. Dredge concentrates are rough classified and limiting the upper size of table feed by means of a submerged deck screen or amechanical classifier is all that is necessary. A separate screen for the sand underflow is used for improved recovery when using tables.
Head feed capacity on the RP-4 tables will differ depending on the feed size, pulp mixture and other conditions. Generally speaking, more head feed material may be processed when feeding unclassified, larger screened sized material and correspondingly, less material may be processed when feeding smaller sized classified rod or ball mill pulps. Smaller classified feed material will yield a cleaner concentrate. Ultimately, the shape of the feed material particles and a quick trial test will determine the maximum upper size.
The width between the riffles of the RP-4 table is small and any particle over 1/8 may cause clogging of the bedding material. A few placer operators will pass 1/8 or larger feed material across the RP-4 table, without a screen, with the intent of making a rough concentrate for final clean up at a later date. This method will work, but excess horizontal slope/grade of the table deck must not be used as some losses of the precious metals will occur. Magnetite black sands feed material, passing a 16-minus screen (window screen size if 16-minus + or -) will separate without losses and make a good concentrate at approximately 500 to 600lbs feed per hour for the RP-4. Head feed material must flow onto the RP-4 screen, at a constant even feed rate. An excess of head feed material placed onthe table and screen at a given time will cause some gold to discharge into the tailings nugget trap. Head feed material should be fed at the end of the water bar into the pre-treatment feed sluice. Do not allow dry head feed material to form thick solids. The wash water will not wash and dilate the head feed material properly, thus allowing fine gold to wash into the tails.
Feed material should disperse quickly and wash down slope at a steady rate, covering all the riffles at the head end,washing and spilling over into the tails trough. A mechanical or wet slurry pump feeder (75% water slurry) is recommended for providing a good steady flow of feed material. This will relieve the mill operator of a tedious chore of a constantly changing concentrate line when hand feeding.
Eight gallons of water per minute is considered minimum for black sands separation/concentration on the RP-4 shaker table. 15 gallons of water per minute is consideredoptimum and will change according to feed material size, feed volume and table grade. A 1 inch hose will pass up to 15 gpm, for good recovery, wash water must completely cover the feed material 1/4 or more on the screen.
The PVC water distribution bar is pre-drilled with individual water volume outlets, supplying a precision water flow. Water volume adjustment can be accomplished by installing a 1 mechanical PVC ball valve for restricting the flow of water to the water distributing holes. Said valve may be attached between the garden hose attachment and water distributing bar.
More water at the head end and less water at the concentrate end is the general rule for precise water flow. More feed material will occupy the head end of the RP-4 shaker table deck in deep troughs and less material will occupy the concentrate end on the cleaning plane. A normal water flow will completely cover the feed material over the entire table and flow with no water turbulence.
A rubber wave cloth is installed to create a water interface and to smooth out all water turbulence. This cloth is installed with holes. Holes allow water to run underneath and over the top of the cloth and upon exiting will create a water interface smoothing out all the water turbulence. Bottom of water cloth must contact the deck.
Avoid excessive slope and shallow turbulent water.For new installations, all horizontal grade/slope adjustments should be calculated measuring from the concentrate end of the steel frame to the mounting base. For fine gold, the deck should be adjusted almost flat.
All head feed must be fed as a 75% water pulp. Clean classified sand size magnetite will feed without too much problem when fed dry. Ground rod or ball mill feed material 65-minus or smaller must be fed wet, (75% water slurry by weight or more) and evenly at a constant rate, spilling over into the tails drain troughat the head end of the table. Feed material without sufficient water will not dilute quickly andwill carry concentrate too far down slope or into the tails. A good wet pulp with a deflocculant and a wetting agent will aid the precious metals to sink and trap within the first riffles, thus moving onto the cleaning plane for film sizing. Round particles of gold will sink instantly and trap within the first riffles. The smaller flat gold particles will be carried further down slope to be trapped in the mid riffles. Potential losses of gold can occur if the table deck is overloaded by force feeding at a faster rate than the smaller flat gold can settle out. Under-feeding will result in the magnetites inability to wash out of the riffles, thus leaving a small amount of magnetiteconcentrated with the gold. A small addition of clean quartz sand added to a black sand concentrate will force the magnetite to the surface and will aid in its removal. Slimes require a separate table operation.
In flotation, surface active substances which have the active constituent in the positive ion. Used to flocculate and to collect minerals that are not flocculated by the reagents, such as oleic acid or soaps, in which the surface active ingredient is the negative ion. Reagents used are chiefly the quaternary ammonium compounds, for example, cetyl trimethyl ammonium bromide.
A substance composed of extremely small particles, ranging from 0.2 micron to 0.005 micron, which when mixed with a liquid will not gravity separate or settle, but remain permanently suspended in solution.
A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials (as in rock ore), so that pieces of different composition can be differentiated. Crushing is the process of transferring a force amplified by mechanical advantage through a material made of molecules that bond together more strongly, and resist deformation more, than those in the material being crushed do. Crushing devices hold material between two parallel ortangent solid surfaces, and apply sufficient force to bring the surfaces together togenerate enough energy within the material being crushed so that its molecules separate from (fracturing), or change alignment in relation to (deformation), each other. The earliest crushers were hand-held stones, where the weight of the stone provided a boost to muscle power, used against a stone anvil. Querns and mortars are types of these crushing devices.
A basic alkali material, such as sodium carbonate or sodium silicate, used as an electrolyte to disperse and separate non-metallic or metallic particles. Added to Slip to increase fluidity. Used to aid in the beneficiation of ores, to convert into individual very fine particles, creating a state of colloidal suspension in which the individual particles of gold will separate from clay or other particles. This condition being maintained by the attraction of the particles for the dispersing medium, water, purchase at any chemical house.
Manner in which the intensity and direction of an electrical or magnetic field change as a function of time that results from the superposition of two alternating fields, (+/-) that differ in direction and in phase.
The smelting of metallic ores for the recovery of precious metals, requiring a furnace heat. Each milligram of recovered precious metal is gravimetric weighed and reported as one ounce pershort ton. Atomic Absorption (AA finish) is the preferred method for replacing the gravimetric weighing system.
A reagent added to a dispersion of solids in a liquid to bring together the fine particles to form flocs and which thereby promotes settling, especially in clays and soils. For example, lime alters the soil pH and acts as a flocculent in clay soils. Acid reagents and brine are also used as a flocculent.
The method of mineral separation in which a froth created in water with air and by a variety of reagents floats some finely crushed minerals, whereas other minerals sink. Separate concentrates are made possible by the use of suitable depressors and activators.
An igneous oxide of iron, with a specific gravity of 5.2 and having an iron content of 65-70% or more. Limonite crystals, sometimes mistaken for magnetite, occurs with the magnetite and sometimes may contain gold. Vinegar will remove gold locked in limonite coated magnetite.
In materials processing a grinder is a machine for producing fine particle size reduction through attrition and compressive forces at the grain size level. See also CRUSHER for mechanisms producing larger particles. Since the grinding process needs generally a lot of energy, an original experimental way to measure the energy used locally during milling with different machines was proposed recently.
A typical type of fine grinder is the ball mill. A slightly inclined or horizontal rotating cylinder is partially filled with balls, usually stone or metal, which grinds material to the necessary fineness by friction and impact with the tumbling balls. Ball mills normally operate with an approximate ball charge of 30%. Ball mills are characterized by their smaller (comparatively) diameter and longer length, and often have a length 1.5 to 2.5 times the diameter. The feed is at one end of the cylinder and the discharge is at the other. Ball mills are commonly used in the manufacture of Portland cement and finer grinding stages of mineral processing. Industrial ball mills can be as large as 8.5 m (28 ft) in diameter with a 22 MW motor, drawing approximately 0.0011% of the total worlds power. However, small versions of ball mills can be found in laboratories where they are used for grinding sample material for quality assurance.
A rotating drum causes friction and attrition between steel rods and ore particles. But note that the term rod mill is also used as a synonym for a slitting mill, which makes rods of iron or other metal. Rod mills are less common than ball mills for grinding minerals.
Screening is the separation of solid materials of different sizes by causing one component to remain on a surface provided with apertures through which the other component passes. Screen size is determined by the number of openings per running inch. Wire size will affect size of openings. -500=500 openings per inch is maximum for gravity operations due to having a solid disperse phase.
Long established in concentration of sands or finely crushed ores by gravity. Plane, rhombohedra deck is mounted horizontally and can be sloped about its axis by a tilting screw. Deck is molded of ABS plastic, and has longitudinal riffles dying a discharge end to a smooth cleaning area. An eccentric is used to create a gentle forward motion, compounded to full speed and a rapid return motion of table longitudinally. This instant reverse motion moves the sands along, while they are exposed to the sweeping and scouring action of a film of water flowingdown slope into a launder trough and concentrates are moved along to be discharged at the opposite end of the deck.
A material of extremely fine particle size encountered in ore treatment, containing valuable ore in particles so fine, as to be carried in suspension by water. De-slime in hydrocyclones before concentrating for maximum recovery of precious metals.
A mixture of finely divided, micron/colloidal particles in a liquid. The particles are so small that they do not settle, but are kept in suspension by the motion of molecules of the liquid. Not amenable to gravity separation. (Bureau of Mines)
Flotation process practiced on a shaking table. Pulverized ore is de-slimed, conditioned with flotation reagents and fed to table as a slurry. Air is introduced into the water system and floatable particles become glom rules, held together by minute air bubbles and positive charged edge adhesion. Generated froth can be discharged into the tailings launder trough or concentrates.
The parts, or a part of any incoherent or fluid material separated as refuse, or separately treated as inferior in quality or value. The gangue or valueless refuse material resulting from the washing, concentration or treatment of pulverized head ore. Tailings from metalliferous mines will appear as sandy soil and will contain no large rock, not to be confused with dumps.
A substance that lowers the surface tension of water and thus enables it to mix more readily with head ore. Foreign substances, such as natural occurring pine oils, vegetation oils and mill grease prevent surface wetting and cause gold to float. Addition agents, such as detergents, (dawn), wetting out is a preliminary step in deflocculating for retarding gold losses.
RP4 shaker table for sale mini gold shaker table RP4 shaker table instructions RP4 shaker table dimensions RP4 gold shaker table RP 4 gravity shaker table utech RP4 shaker table RP 4 gravity shaker table price used RP4 shaker table for sale
Global mining solutions warrants that all mining equipment manufactured will be as specified and will be free from defects in material and workmanship for a period of one year for the RP-4. Providing that the buyer heeds the cautions listed herein and does not alter, modify or disassemble the product, gms liability under this warranty shall be limited to the repair or replacement upon return to gms if found to be defective at any time during the warranty. In no event shall the warranty extend later than the date specified in the warranty from the date of shipment of product by GMS. Repair or replacement, less freight, shall be made by gms at the factory in Prineville, Oregon, USA.
All bearings are sealed and no grease maintenance is required. Do not use paint thinners, or ketones to clean your deck. A small amount of grease should be applied to the adjustable handle which is used for the changing the slope of the deck.
Do not allow the RP-4 to stand in direct sunlight without water. Always keep covered and out of the sun when not in use. Heat may cause the deck to warp. Do not lift or pull on the abs plastic top, always lift using the steel frame. Do not attach anything to the abs plastic top. Do not attach PVC pipe to concentrate discharge tubes, constant vibration from the excess weight will cause stress failure of the plastic.
We've always aspired to offer our customers more than just kitchens and so, over the last few years, we've started to design and make our own stools, chairs, tables. Please see our ever-expanding range of products below.
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BY ENTERING THE CONTEST OR MAKING A REFERRAL THAT ENTITLES YOU TO PARTICIPATE IN THE CONTEST, YOU REPRESENT AND WARRANT THAT YOU HAVE READ, AND AGREE YOU WILL ABIDE BY, THESE CONTEST RULES, WHICH SHALL BE POSTED ON THE WEBSITE.
The Contest is open to all residents of Canada who have reached the age of majority in their province or territory, and have a valid Shakepay account (including a Shakepay Username) and completed the registration on their Shakepay account. Notwithstanding the foregoing, residents of the Province of Quebec cannot enter and cannot participate in this Contest. Additional entry requirements may be found in the HOW TO ENTER section below.
Anyone who meets the eligibility criteria and has made a valid Entry (as defined in the next section) in the Contest shall be deemed a Participant in these Contest Rules. The entirety of this section as well as any additional entry requirements found in the Section 2 below may be referred to as the Participant Eligibility Criteria.
You must have a Shakepay account to enter. If you do not have a Shakepay account go to https://shakepay.com or download the Shakepay: Buy Bitcoin Canada application from either the Google Play Store or the Apple App Store to create one.
The friend (or more than one) you invite must sign up to Shakepay and must complete account registration (by providing their full legal name, date of birth, current residential address, occupation, and verifying their phone number and email address, and fulfilling any other requirements for registration).
There is a maximum of one Entry per person per day. You are eligible to participate in the Contest every day as long as you meet requirements and have a valid Shakepay user account that complies with your legal obligations as a user. Entries indicating the same user details will be considered, for purposes of the Contest, to belong to the same Participant and therefore is subject to this restriction. Any excess Entries will be invalid for purposes of the Contest draw. If you attempt or are suspected of attempting to invite a friend who already has a Shakepay account or any entry methods not authorized by these Contest Rules, it shall be deemed as tampering and shall void any and all of your Entries.
The Prize(s) are granted in Satoshis (Sats). One Sats is 0.00000001 bitcoins. Every day there will be a Prize of $1,000 CAD worth of Sats. The value in Sats of each Prize will be calculated at the time of awarding the Prize, using the then current Shakepay conversion rate. Thus, the value in Sats may vary accordingly.
Every day, starting July 10th, 2021, a random winner will be picked from a list of the Participants. The winner will then need to answer a skill-testing question in order to qualify for the awarding of the Prize, and you must answer the question correctly. You must and warrant that you will answer the question without the assistance of any other person.
If the winners agree, their shaketag (username) will be shared publicly on the official Shakepay Discord community and the official Shakepay Twitter page (and any other website or app used by Shakepay). Winners will be announced each day, starting July 10th, 2021. The Winner will also receive a message from the Shakepay team in the Shakepay app. If the Winner does not have the Shakepay app set up, they will receive an email from [emailprotected].
The Winner must confirm their current residential address prior to receiving the Prize. We expect every Winner will confirm their address but a Winner who does not complete this requirement (and the skill-testing question) within 30 days will be deemed not to be a Winner, and no Prize will be awarded for that day. Being announced as a Winner by Shakepay is not sufficient to be awarded a Prize as all of the Contest Rules must be complied with before any Prize shall be awarded.
If the Winners address is up to date and matches the address on the Winners Shakepay account, the Winner will receive a Prize based on their residency. If the Winners address is changed from either non-Quebec to Quebec residency, or Quebec to non-Quebec residency, the Winner must submit a Proof of Address prior to receiving the Prize. Notwithstanding the foregoing, determination of residency shall be in Shakepays sole discretion and its decision regarding residency shall be final.
If a winner does not respond within seven days following the first attempt of contact, refuses to provide their current residential address, or declines the Prize, the Prize shall be forfeited and Shakepay shall have the right, at its sole discretion, to select another Winner for that day or pick an additional Winner for another day (but it is not obligated to do so).
If an individual Winner has fulfilled all the obligations described in this section and fulfills the Contest Eligibility Criteria, their Prize will be transferred to their Shakepay account within 24 hours.
5.1. PROOF OF ADDRESS. Winners will be required to provide their current residential address and might be asked to provide a Proof of Address in case the provided address doesnt match the address on the Winners Shakepay account (or otherwise triggers our review process, which is a part of our anti-money laundering program as a registered Money Services Business).
A Proof of Address must show the Winners name (i.e.your name) and address clearly. The Proof of Address shall be conducted in such a way that it meets or exceeds the standards established by Canadian anti-money laundering law, but the process chosen shall be at Shakepays sole discretion and may vary according to the circumstances.
5.3. FREE TO ENTER, NOT RESPONSIBLE FOR LOSSES OR HARM. Shakepay is not responsible for any loss, harm, damages, cost or expense arising out of participation in the Contest, participation in any Contest-related activity or the acceptance, use, or misuse of any Prize, including but not limited to costs, injuries, losses related to personal injury, damage to, loss or destruction of property, rights of publicity or privacy, defamation, or portrayal in a false light, or from any and all claims of third parties arising therefrom.
5.4. INDEMNIFICATION. By entering the Contest, Participant releases and holds Releasees (directors, officers, employees, and contractors of Shakepay, and Shakepay itself) harmless from any and all liability for any injuries, loss or damage of any kind to the Participant or any other person, including personal injury, death, or property damage, resulting in whole or in part, directly or indirectly, from acceptance, possession, use or misuse of any Prize, participation in the Contest, any breach of the Contest Rules, or in any Prize-related activity. The Participant agrees to fully indemnify Releasees from any and all claims by third parties relating to the Contest, without limitation.
5.6. DISQUALIFICATION. Illegal or dishonest activity is grounds for disqualification. If a Participant makes a false statement or otherwise violates these Contest Rules (or any legal terms applicable to their Shakepay account), they shall be disqualified from the Contest. Any action that violates, infringes, or misappropriates any rights of any third party including, without limitation, patent, copyright, trademark, trade secret, or right of privacy or publicity shall also subject a Participant to disqualification from the Contest. Any disqualification under these Contest Rules shall be at Shakepays sole discretion.
5.7. LIMITATION OF LIABILITY. Since were giving away Sats and theres no purchase necessary, we wont accept any liability. The Releasees assume no liability for any loss, damage or injury, including without limitation: (i) lost, stolen, delayed, damaged, misdirected, late, destroyed, illegible or incomplete Entries; (ii) loss, theft, or damage to software or computer or telephone data, including any breach of privacy; (iii) fraudulent calls or emails; (iv) inability of any person to participate in the Contest for any reason including technical, computer or telephone malfunctions or other problems with computer systems, servers, access providers, computer equipment, or software; technical difficulties with Shakepay, or any combination of the foregoing; (v) damage to any persons computer or device, including as a result of playing or downloading any material relating to the Contest; (vi) any delay or inability to act resulting from an event or situation beyond their control, including a strike, lockout or other labour dispute at their location or the locations of the organizations and businesses whose services are used to administer this Contest (including but not limited to Shakepay); or (vii) use of a Prize or any losses or damages arising from any activity related thereto.
5.8. CANCELLATION OF CONTEST. Fairness is important to us. Shakepay reserves the right to cancel or suspend this Contest should a virus, bug, or other cause beyond its reasonable control corrupts the security or proper administration of the Contest. Any attempt to deliberately affect the Website or to undermine the operation of this Contest is also a violation of the rules of the Contest. Should such an attempt be made, Shakepay reserves the right to seek remedies and damages to the fullest extent permitted by law.
5.10. DISPUTES REGARDING THE WINNERS ACCOUNT. If a Winners account is subject to Shakepay's risk management and security protocols that include limiting access to, suspending, or closing a Winners account, they shall be automatically disqualified from the Contest. Any disqualification under these Contest Rules shall be at Shakepays sole discretion.
5.11. TIME. The Contest will be conducted every day starting July 9th, 2021. In order to participate in the Contest, you must refer a friend who signs up using your referral link and completes the registration of their Shakepay account. You become a participant of the day when the criteria are met (e.g. if you refer the friend on Monday but they actually sign up on Tuesday then it would be Tuesday thats the relevant day, not Monday). Shakepay may end the Contest at any time, without notice to you.
5.12. ODDS OF WINNING. All Participants have equal odds of winning. If you sign up more than one friend on the same day, that will be considered as one Entry and will not increase your odds of winning. You can win more than once.
5.13. AMENDING THE CONTEST RULES. Shakepay reserves the right to amend the Contest Rules or to terminate the Contest at any time without any liability to any Participant (or any other person). Any amendments to these Contest Rules will be updated in this document and posted on the official Shakepay Discord community (https://discord.gg/TjG5RgPM). Participants are responsible for checking the Contest Rules and agree to abide by the most recent Contest Rules posted as at the Contest Closing Date and Time.
5.14. THE RULES ARE BINDING. By entering the Contest, you represent and warrant that you have read, and agree you will abide by, the Contest Rules. You further agree you will abide by the decisions of Shakepay, which decisions are final and binding on all Participants.
5.15. NO WAIVER. Any failure by Shakepay to enforce any provision of these Contest Rules shall not constitute a waiver of that provision. The invalidity or unenforceability of any provision of these Contest Rules shall not affect the validity or enforceability of any other provision. If any provision of the Contest Rules is determined to be invalid or otherwise unenforceable, then the Contest Rules shall be construed in accordance with their terms as if the invalid or unenforceable provision was not contained therein.Get in Touch with Mechanic