The general term gypsum refers to two minerals, raw gypsum and anhydrite. Raw gypsum is calcium dihydrate (Ca [SO4] 2H2O), also known as dihydrate gypsum or plaster. Anhydrite is anhydrous calcium sulfate.
It is a very important industrial raw material that is widely used in construction, building materials, industrial and artistic models, chemical industry (sulfuric acid production, paper filler, paint filler), agriculture, food processing, pharmaceutical, and many other industries and applications.
The plaster of Paris (also known as hemihydrate gypsum), divided into -type gypsum powder and -type gypsum powder, is formed from gypsum raw materials by heating at a high temperature of 105-200 .
The -type gypsum powder has good crystallinity and solidity, so it can be used in ceramic molds, sculptures, gypsum lines and high-end buildings. The -type gypsum powder is mainly used for mortar levelling, gypsum board production, painting, etc.
Gypsum powder can be used as Portland cement retarder in the concrete industry. In agriculture, because gypsum powder is alkaline, it is possible to sprinkle it into the acidic soil to integrate the ph value of the soil so as to make use of a lot of lands.
In the pharmaceutical industry, gypsum is the main medicine in the famous Chinese medicine " Baihu Tang ", which has a good effect in treating acute high fever and thirsty irritable. In addition, dentists use plaster to make models of gums, and surgeons also use plaster to repair the fractures.
Is gypsum harmful to humans? Is gypsum powder safe to eat? Will gypsum kill plants? Here is a video about how gypsum is used, including its uses in toiletries, food additive, fertilizer, chalks, etc. It also shows the process of gypsum.
In recent years, the gypsum industry has developed rapidly. Gypsum building materials are increasingly welcomed by the market and recognized by society with their applications becoming more and more widespread.
According to the US mining forecast, the world's gypsum demand will increase at a rate of 2.5% in the next few years. It is estimated that the world's gypsum demand will reach 300 million tons in 2030. The total annual consumption of the gypsum board will reach 2.04 billion square meters.
With the increase in the market demand for gypsum powder, the requirements for its production technology are getting higher and higher, so the price has risen accordingly. The price of gypsum powder is generally calculated in tons.
Its price varies with its accuracy and use. The price of gypsum powder is between $ 28.8-$ 403.6 per ton according to its whiteness and fineness. The cooked gypsum powder is about $ 28.8-$ 158.6 per ton, the cooking gypsum is about $ 72.1-$ 317.2 per ton, and the refined gypsum powder is about $ 201.8-$ 720.8 per ton.
1. The ex-factory price of Australian recycled gypsum is $ 35.00 per ton, plus $ 25 per ton freight, which is $ 60.00 per ton at the farm gate, and $ 10.00 per ton to spread. Its purity is measured at 17% S wet weight. Total cost of gypsum supply and application per ton of pure CaSO4.2H20 = (35+25+10) 18.6 17 = $ 76.59 per ton.
2. The ex-factory price of gypsum mined in New South Wales is $ 15 per ton, plus $ 40.00 per ton freight, which is $ 60.00 per ton at the farm gate, and $ 11.00 per ton to spread. Its purity is measured at 15% S wet weight. Total cost of gypsum supply and application per ton of pure CaSO4.2H20 = (15+40+11) 18.6 15 = $ 81.84 per ton.
The world's major gypsum producing countries are the United States, Iran, China, Brazil, Canada, Mexico, Spain, Thailand, etc. The United States, Brazil, China, and Canada are rich in gypsum resources.
The largest consumption area of gypsum is the building decoration material industry, which is mainly used to manufacture gypsum boards for construction and decoration. In many countries, the manufacture of slabs accounts for more than 80% of gypsum consumption.
The mining technology of gypsum ore is divided into two categories: the mining of fibrous gypsum ore and the mining of alabaster, ordinary gypsum and anhydrite mines. Due to the difference in physical and mechanical properties of the ore and surrounding rock, the mining technology of these two kinds of gypsum mines is very different.
Fibrous gypsum has low hardness and its rock consolidating coefficient is 1.2 for parallel fibrous gypsum and 1.5 for vertical fibrous gypsum. Because it is brittle, it will easily become fine ore to be lost. Due to the high price of the ore, most fibrous gypsum mines adopt the longwall method, selective mining and filling method.
The mining techniques of alabaster mine, ordinary gypsum mine and anhydrite mine are similar. The room and pillar mining method (generally 8-12 m in width) and breasting method are adopted. The drilling of gypsum ore is easy, but the explosive consumption is large, generally 0.34 kg/t.
The roller drilling rig is modern new drilling equipment. It is suitable for drilling operations of various hardness of minerals and rocks with the characteristics of high perforation efficiency, low operating cost, high mechanization and automation. At present, it has become a widely used perforation equipment in open-pit mines all over the world.
The excavator is composed of the power plant, working device, swing mechanism, control mechanism, transmission system, moving mechanism, auxiliary equipment, etc. The excavator can also perform pouring, lifting, installation, piling, ramming, and pile pulling operations after changing its working device.
After sieving with the vibrating screen equipment, the finished material conforming to the size is sent to the finished product area, while the large material is returned to the crusher for being crushed again until it meets the required size.
The common gypsum crushing equipment is the jaw crusher with a crushing ratio of 4-6. The jaw crusher, which is often used as the primary gypsum crushing equipment, can crush large pieces of gypsum into 150 mm particle size.
If the gypsum crushed by the jaw crusher cannot meet the particle size requirements, secondary gypsum crushing equipment such as cone crushers, hammer crushers, and impact crushers can be equipped to carry out further medium and fine crushing of gypsum. Specific equipment should be configured depends on the actual needs of the customer.
The crushed gypsum is sent to a ball mill for grinding until 90% of it is less than 149 m (100 mesh). The ground gypsum powder leaves the mill in the form of airflow and is collected in the cyclone separator.
The ball mill is mainly a machine for dry or wet grinding of the crushed gypsum. The machine is mainly used for repeated grinding of the raw materials in the barrel through the steel ball medium in the ball mill to complete the ball grinding operation.
The cyclone separator is suitable for purifying non-viscous, non-fibrous dry dust larger than 1-3 microns. It is purification equipment with simple structure, convenient operation, high-temperature resistance and low equipment cost.
Under the design pressure and air volume conditions, solid particles 10 m can be removed. At the operating point, the separation efficiency is 99%, and within 15% of the operating point, the separation efficiency is 97%. Under normal working conditions, the pressure drop of a single cyclone separator at the operating point is not greater than 0.05 MPa.
The gypsum material is lifted by an elevator and transported into the top silo of the rotary kiln preheater. Then, the gypsum material is evenly distributed into rooms of the preheater through the feeding pipe.
In the preheater, gypsum is heated to about 900 C by the flue gas of the roasting kiln at 1150 C, and about 30% of it is decomposed. Then, it is pushed into the rotary kiln by a hydraulic push rod, and -type hemihydrate gypsum (180240 ), anhydrous gypsum (350 ) and overfired gypsum (450700 ) can be produced.
The gypsum produced after calcining and decomposing in the rotary kiln is sent to the cooler to be cooled to below 100 C by the cold air blown in the cooler and discharged. The gypsum from the cooler is sent to the product warehouse via a vibrating feeder, bucket elevator, and belt conveyor.
Gypsum rotary kiln is a kind of thermal equipment for calcining gypsum. Its appearance and shape are similar to lime rotary kiln and cement rotary kiln. Its main structure includes kiln head, kiln tail sealing device, rotary cylinder, supporting device, back-up roll device, etc.
The finished gypsum clinker calcined in the gypsum rotary kiln produced by Fote has the characteristics of high taste, high purity, easy to control during the production process, high mixing degree of raw materials, uniform raw meal composition, high strength grade of the clinker, with less dust in the grinding process, less fly ash in the calcining process and reasonable price.
The large demand and wide application of gypsum powder have stimulated the prosperity of many industries and fields, so the production of high-quality gypsum powder is the general trend of the gypsum powder industry in the future.
Fote Heavy Machinery, as one of the three major mining machinery manufacturers in China, has 38 years of experience. We are always ready to provide you with high-quality milling equipment and the best service.
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Raymond mill has a history of over 100 years. So, it's classic undoubtedly. Recent years, with the growth of non-metallic mineral grinding industry, ZENITH upgraded Raymond mill to make it have more application areas, and, meanwhile, own high degree of reliability and automation. ZENITH's Raymond mill is suitable for materials like limestone, gypsum, coal, calcite, barite etc.
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Rod mill is very similar to ball mill. The maximum input size of material ground by Rod Mill is about 50 mm, and size of finished product can be controlled within range of 3000 to 270m (4 to 35 mesh).
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Mercury is a potentially deadly neurotoxin. Mercury emissions from coal-fired power stations are a major environmental concern due to the toxicity and persistence of mercury that accumulates in our waterways.
ANDRITZ follows a holistic approach by taking not only the various oxidation reactions in the flue gas pathway into account, but also the processes within the wet FGD system and downward streams. We expect that this issue will become a major topic worldwide for coal-fired boilers within the next few years.
If the conventional oxidation in the gas phase, based on the gas condition and process set-up, is not sufficient to meet the emission limits, ANDRITZ offers a well-proven calcium bromide oxidation system. Dosing calcium bromide into the boiler is an adequate and easy way to oxidize the greater part of the mercury originating inside the boiler. Other process steps within the flue gas path are crucial for any further mercury oxidation downstream of the boiler as well. For instance, any enhanced oxidation within an existing SCR unit has to be considered for any process developments. Finally, the oxidized mercury will be captured at the FGD scrubber. ANDRITZ considers all the important process steps and the gas composition in order to optimize the mercury emission control system implemented.
ANDRITZ is also looking into the documented topic of potential corrosion effects in combination with the bromine-induced mercury oxidation. Corrosion effects have been documented in some plants, especially in the USA. It was found that corrosion will occur primarily at the cold part of the cold side of the air heater in cases where unusually high bromine concentrations were added to the coal mill and the process set-up was not favorable. Bromine is not unusual in flue gas. It is found in any coal containing halogens. In general, the bromine content in coal will be roughly 1 to 3 % of the chlorine content. With a chlorine content of between 1000 and 2000 ppm in the dry coal, this means that the bromine content in the same coal will be between 20 and 40ppm.
The wet FGD is not only a very efficient way of separating acidic components from the flue gas stream, it is also highly efficient when it comes to removal of the oxidized mercury species. However, inconsistencies in wet scrubber chemistry can be linked to re-emissions of mercury that has already been captured. In order to avoid any re-emissions from the FGD process, ANDRITZ focuses particularly on binding and stabilizing the dissolved mercury in the limestone slurry. If, for instance, PAC (powdered activated carbon) injection is applied to inhibit re-emission, the main mercury sink in the conventional process chain will be the FGD by-product the gypsum. This is unacceptable for two major reasons if the plant management is targeting beneficial use of the FGD product. Firstly, it greatly increases the mercury content in the gypsum, which could render the FGD product useless as a resource for the drywall industry. Secondly, the gypsum whiteness will deteriorate and hence be unattractive for commercial use.
With conventional hydrocyclone systems, the specifically bound mercury cannot be removed efficiently from the gypsum. Thus, ANDRITZ offers a patented hydrocyclone design that clearly separates the mercury-loaded particles (e.g. PAC) from the gypsum and thereby reduces the mercury content in the FGD product to a minimum. This patented wash water hydrocyclone technology is easy to implement and has a clear advantage for any upgrade of existing FGD installations for any upgrade of existing FGC installations in order to enhance mercury transfer to the waste water treatment plant and also to prevent an increase in the mercury concentration within the scrubber.
ANDRITZ offers an upgrade of any mercury reduction system with a clear mercury sink within the FGD system and can draw on long-term experience with any dewatering technology. Thus, a controlled mercury sink is created.
Our complete product portfolio allows us to comply with the most difficult requirements through the intelligent combination of our processes and technologies especially for Waste-to-Energy plants or other industrial applications.
ANDRITZ dry flue gas cleaning systems meet the requirements for complying with the worlds strictest emissions legislation, the desire for low consumption of additives, the need for minimal residues, and the installation simplicity of a compact design.
In response to the municipal strategic deployment of controlling environment pollution and in order to demonstrate the social responsibility as a state-owned enterprise, the customer company contacted SBM to help customize an efficient clean coal powder production project with an annual output of 300,000 tons.
Fully sealed production, there is no dust in the production process, and the production is fully in line with national green mine construction standards. Explosion-proof system ensures the safety of operations.
As environmental regulations tightenboth in the U.S. and around the worldcoal-fired power plants continue to look for ways to operate economically. Though reuse and sale of coal combustion by-products has a long history, one new approach could benefit a somewhat unlikely partner industry.
The history of power plant emissions regulations and control technologies is largely one of preventing elements that are bad for the environment or human healthincluding sulfur dioxide, particulate matter, and nitrogen oxidesfrom being dispersed to the environment. But sometimes its possible to take advantage of the by-products of the control technologies and put them to good use in the environment. Thats the case with a new process that converts sulfur to fertilizer.
Charah Inc. has developed a technology that allows sulfur captured from power plant exhaust gases to be pelletized into a calcium sulfate fertilizer product that returns vital nutrients to farm fields. To understand why Charah and coal-fired power plants would find this worth doing, you need to understand the role of sulfur in the environment and the economics of the process.
When coal is burned in a boiler to generate electricity, the naturally occurring sulfur in the coal is released into boiler exhaust gases. Before it was regulated, coal sulfur was discharged into the atmosphere through plant stacks. The U.S. Environmental Protection Agency (EPA) first started regulating power plant air emissions in 1971. According to the EPA, these air quality controls covered SO2 because exposure to the gas can cause adverse respiratory effects, it can combine with other gases to produce harmful particulates, and it is a primary cause of acid rain.
Declines in SO2 emissions began soon after enactment of the 1990 Clean Air Act Amendments, which established a national cap-and-trade program for the gas. Because coal-fired units accounted for a large share of SO2 emissions, the program (which also covered NOx) provided an economic incentive for coal-fired power plants to reduce emissions by installing pollution control systems, burning lower-sulfur coal, or generating less electricity.
All plants built after 1978 are required to clean the sulfur from coal combustion gases before they go up the stack. They do so with flue gas desulfurization (FGD) units, commonly called scrubbers. The EPA reports that by the end of 2011, 60% of the U.S. coal fleet had FGD scrubbers installed.
As scrubbers began to remove sulfur from exhaust emissions, and some plants switched to low-sulfur coal, the amount of sulfur in the air decreased. EPA data shows that between 1980 and 2012 concentrations of atmospheric SO2 in the U.S. decreased approximately 78% (Figure 1).
But sulfur need not always be a net negative for coal-fired plants. Since the 1990s, captured sulfur from flue gas has resulted in the production of high-quality gypsum, hydrated calcium sulfate: CaSO4-2H2O. That synthetic gypsum can then be beneficially used in a number of common applications, from plaster and wallboard to cement and fertilizer. Though gypsum occurs naturally (and even lends its name to a town in Colorado with a history of gypsum mining and processing), synthetic gypsum has advantages in that it doesnt have to be mined, and it recycles what would otherwise be a waste product that power plants would have to pay to dispose of in landfills. Use of synthetic gypsum has also reduced costs for drywall manufacturers.
Charah Inc.a Louisville, Ky.based company that specializes in total ash management, including recycling by-products from coal-fired power plantshas developed a technology that allows sulfur captured from power plant exhaust gases to be pelletized into a calcium sulfate fertilizer product, providing an improvement, it says, over previous forms of fertilizer created from power plant emissions.
Charahs new facility housing this process is located at the 1,472-MW Louisville Gas and Electric Co. (LG&E) Mill Creek Generating Station, in Jefferson County, Ky. Coal provides the majority of power for Kentucky, and this plant went into commercial operation in 1972 and was LG&Es first to utilize cooling towers to protect the Ohio Rivers aquatic life.
Plant owners are committed to keeping this plant online. Starting in spring 2012, LG&E planned to spend approximately $1.3 billion to modernize the FGD systems and install fabric filter baghouses for increased particulate and mercury control on all units at the plant. This construction project is under way and will continue through 2015. And in November 2012, LG&E officials announced that, as part of the $1.3 billion, they would be spending approximately $940 million on clean coal technology at the station. Mike Kirkland, general manager of Mill Creek Station, told POWER that would include replacing existing scrubbers with new ones, installing new baghouses, and replacing exhaust stacks.
Mill Creek burns approximately 4 million tons of high-sulfur coal annually, primarily sourced from the Illinois Basin. Kenny Tapp, senior by-products coordinator for LG&E and KU Services Co., noted that over 60% of the plants fly ash is used in the manufacturing of cement and concrete; the economic value of the fly ash utilization in concrete is estimated to be in excess of $5,000,000 to the regional manufacturers of concrete- and cement-based products. In addition, the plant realizes significant savings on landfill capacity and associated costs, though neither the plant nor Charah would release detailed data on these savings.
The plant has had wet scrubbers and a FGD slurry processing plant on its property since 1978, and its processing plant can dewater up to 1,800 tons of gypsum per day for use in the manufacturing of cement, drywall, or other uses. Now that gypsum has expanded utilization opportunities as fertilizer. This additional use can consume 200,000 plus tons per year of the total gypsum annual production.
The sulfur-scrubbing process at a coal-fired power plant typically involves grinding high-calcium limestone to powder and then mixing it with water to form a lime slurry. The lime slurry is then sprayed into a contact chamber, where it combines with boiler exhaust gases and the sulfur reacts with the lime to become chemically bound.
Scrubbers come in two types: wet and dry. In wet scrubbers, the ratio of lime slurry is greater and a slurry by-product is produced. In dry scrubbers, the ratio of slurry to hot exhaust gases is controlled, to dry the lime slurry and result in a dry product. Charah has developed a process to beneficially use the wet scrubber slurry dewatered gypsum to manufacture a sulfur and calcium fertilizer.
Wet scrubbers capture sulfur from all four units at Mill Creek. The lime and sulfur slurry is aerated to create calcium sulfate, dewatered to produce high-quality gypsum, and then processed to make fertilizer at the adjacent Charah facility (Figure 2).
The Mill Creek gypsum typically has higher purity than natural gypsum because it has less inert impurities. Mill Creek gypsum is 90+% pure calcium sulfate. Charah utilizes this calcium sulfate gypsum to manufacture a patent-pending fertilizer named SUL4R-PLUS product that can be used to replenish the sulfur and calcium in farm soils, turf, and specialty crops (see sidebar). As Danny Gray, executive vice president of Charah, explained, this process essentially closes the cycle loop for the sulfur that once was returned to farm fields with rainfall, but now is removed by the power plant emissions control equipment before discharging the cleaned exhaust gases into the atmosphere.
The Charah plant accepts the gypsum when it discharges from the existing Mill Creek dewatering facility onto a new conveyor that moves it directly into the Charah plant. That gypsum serves as the feed stock for the processing steps that include pelletizing to create the granular SUL4R-PLUS product. Although synthetic gypsum has previously been used as a soil amendment, Charah says it is the first to pelletize the by-product, which makes application easier for the farmer.
That granular product is stored inside the Charah warehouse until it is transported to customers. Custom truck loading is done inside the warehouse facility. Charah also has barge-loading capability, as well as onsite railcar-loading capacity to meet customers logistics needs. Because the Kentucky plant is located near the Ohio River, Charah can reach distant markets by barge at economical rates.
The sulfur level of SUL4R-PLUS product is greater than 16%, its calcium level is greater than 20%, and the product looks like and handles like any other granular fertilizer (Figure 3). Farmers can replenish the sulfur depleted by crops from farm soils by applying SUL4R-PLUS product along with their other fertilizers. The product has a unit weight of approximately 50 pounds per cubic foot and spreads in common distribution equipment in a single pass across the field.
In nations where power plant emissions are tightly regulated, adding beneficial reuse of by-products is likely to become an increasingly valued option for the future business case. At full capacity, more than 50% of Mill Creeks gypsum will be beneficially used. By avoiding disposal of the recycled by-products, LG&E realizes lower operating costs, which help lower electricity costs for the utilitys customers.
Additionally, Gray says Charahs granular fertilizer provides good economic value to the American farmer, as typical prices of SUL4R-PLUS product are 20% to 30% lower than alternative sources of sulfur equivalents.
Charahs investment of $12 million to $14 million in 2013 has provided a first-of-its-kind manufacturing plant to convert high-grade calcium sulfate into a new agriculture product. The plant is designed to reclaim up to 300,000 tons per year of gypsum and produce up to 250,000 tons of SUL4R-PLUS product fertilizer. It also created up to 25 new jobs in the recycling industry.
At power plants that generate a high-quality gypsum product, Charah says a manufacturing plant can be custom designed and installed within 12 months. Charah provides the capital for SUL4R-PLUS plants and maintains owner and operator status. Agreements between Charah and the host power plant typically extend over five to 15 years. Charah plans to develop and install SUL4R-PLUS manufacturing plants throughout the U.S. at strategic locations to meet the growing demand for agricultural sulfur products.
Vertical Roller Mill is our newly-launched product which is applied as a solution to the technical issues such as low output and high energy consumption in the ordinary industry. This new type product is developed based on years of production and development on the pulverizer through analyzing and researching the strengths and weakness of both foreign and domestic products of its kind. Its performance has entered into the leading level among the international products of its kind. Vertical Roller Mill is a new type advanced pulverizing equipment featuring good performance and drying function. Integrated with drying, pulverizing and powder-selection, Vertical Roller Mill is widely applied in cement, chemical, coal and electric power industries. It has become the mainstream equipment in the pulverizing industry.
The equipment integrates the functions of crushing, drying, grinding, powder separating and transportation, featuring simple system and compact layout, with the floor space of about 50% of that of the ball-milling system. And it can be arranged outdoors so as to greatly reduce the investment costs. The system design is simple and reasonable, saving unnecessary equipment investment so as to reduce total investment of the equipment.
Less wear: The roller does not contact the grinding plate directly and the roller and grinding plate are made of high-quality materials. Therefore, they enjoy longer service life and less wear. High efficiency: The grinding rollers can directly grind materials on the grinding plate, featuring lower energy consumption (30% ~ 40% lower than that of ball-milling systems).
The equipment is provided with an expert automatic control system, realizing free switching between remote and local control to achieve easy operation and save labor costs.
The equipment can operate stably with little vibration, so its noise is fairly low. The system is wholly sealed and works under negative pressure, free of dust spillover and environmentally friendly, with the emission meeting the national standard.
The main motor drives the grinding plate by the reducer, simultaneously the hot air enters the vertical mill body from the air inlet and the materials drop on the grinding plate center from the feed opening and evenly move outwards due to centrifugal force. The materials are ground by grinding rollers when passing through the grinding area on the grinding plate, and large size materials will be directly crushed while the fine materials will form a material bed by extrusion for further inter granular crushing. The crushed materials will continue to move towards the mill edge until being taken away by the strong air flow at the vane and collected by the dust collector, while larger material particles will again fall onto the grinding plate for repeated grinding; the coarse particles in the air flow will drop back onto the grinding plate for further grinding when passing through the upper separator under the action of the rotor blade, with the qualified fine powder flowing out of the grinding plate with the air flow and then collected and discharged by the system powder collector as finished powder product. However, the iron blocks and other wastes mixed in the materials will move along with the materials towards the edge of the grinding plate due to their own weight and fall into the lower chamber and then be discharged out of the slag discharge opening by the scraping plate at the bottom of the mill tray (commonly known as scumming).Get in Touch with Mechanic