how china used cheap coal and allegedly forced labour to dominate the world's solar market | financial post

how china used cheap coal and allegedly forced labour to dominate the world's solar market | financial post

The arrival ofSolarWorld AGpromised to be a turning point for his hometown just west of Portland.Not just because of SolarWorld itself, Hughesrecalled,but because of the other companies it would drag along with it to create this silicon-based and solar-based manufacturing cluster in Hillsboro.

That was in 2008 and solar was on the cusp of becoming one of the fastest-growing sources of energy in a world rattled by warnings of climate change. From the White House to statehouses, U.S. leaders promised that green jobs could not only replace those threatened in the nations oilfields and coal mines, but guarantee safer and more stable employment.

Yet acrossthe Pacific, a rapidly growing competitor had also set its sights on dominating solar manufacturing. China, eager to prove the supremacy of its socialist-market model, was mustering government investments that dwarfed the U.S. effort and couplingthem with national mandates that forced utilities to use renewable power.

It established an end-to-end supply chain the country now makes most of the worlds polysilicon, a key material in solar panels and ignored pleas by environmentalists to close coal plants that supply the cheap electricity needed to make solar equipment. It also kept its labour costs lower than those in most industrial countries and has been willing to prop up unprofitable operations. The result? Chinese firms now supply three quarters of the worlds solar panels.

U.S. companies, which 20 years ago made 22 per cent of them, now produce just 1 per cent on American soil, according to Jenny Chase, head of solar analysis at BloombergNEF. At one point there were 75 major solar parts factories in the U.S., a number that was expected to grow as the industry flourished. Most have since been shuttered.

The industry failed to take root in the U.S. despite billions of dollars in government incentives and nearly two decades of pledges from presidents, starting withGeorge W. Bush,that the nation would be a clean-energy superpower. Even the crushing tariffs imposed by former presidents Barack Obama and Donald Trump succeeded mostly in pushing the work out of China and into other Asian countries.

Critics, such as Oregon Senator Ron Wyden, allege that China benefited from unfair trading practices and the use of forced labour in its supply chain charges the nation rejects and that analysts say is unlikely to have played a significant role in the success of its solar strategy. Rather, Chinas dominance is a result of Beijings commitment to corner the market.

They tried harder than us, said Sarah Ladislaw, a senior adviser at the Center for Strategic and International Studies. China had a plan and they executed to the plan. They had policies to create supply, they had policies to create demand, and they executed on it.

At the same time, the U.S. dabbledwith short-lived incentives and punishing trade barriers that spurred retaliation instead of a manufacturing renaissance. The inconsistent, piecemeal policy of the U.S. was no match for a China-styled industrial strategy to dominate solar manufacturing, Ladislaw said. You cant take the sum of a bunch of half-hearted measures and hope that it equals a durable outcome.

For President Joe Biden, whos made investment in renewable energy a centerpiece of his climate-change initiatives and multi-trillion-dollar infrastructure plan, the failed strategies of his predecessors serve as a stark warning: Fulfilling his promise to make climate policy a jobs engine wont be easy.

And while solar manufacturing never generated a hoped-for bonanza of jobs in the U.S., where employment peaked at about 30,000, the next clean energy contestwith China will be more painful to lose.Both nations believe the future will be driven by electric vehicles, and Biden has vowed the U.S. will win the race to build them.

Yet while Detroit is planning an EV makeover, Congress is still bickering over tax credits and whether to pay for charging stations. China, meanwhile, has installed some 800,000 public chargers about eight times the number in the U.S. and has parlayed a combination of tax incentives, land grants, low-interest loans and other subsidies into becoming the worlds biggest producers of the vehicles for six years running.

Hundreds of companies are building electric vehicles in dozens of specialty manufacturing hubs set up around the country to take advantage of inexpensive semiconductors and batteries two other industries Beijing has set out to dominate.

The comprehensive strategy,part of China President Xi Jinpings blueprint to become a manufacturing superpower, echoes the oneused to conquer global solar panel manufacturing.Chinas victory on solar panels was so thorough that even erstwhile supporters of the U.S. renewable strategy say its time to give up the fight and make do with the installation jobs created by the low-cost Chinese equipment.

Its a bitter pill for Hillsboro and its 106,000 residents. In the early days, Hughes, the former mayor, saw the solar factory as a chance to diversify an area that was so dominated by computer chip manufacturing it had been dubbed the Silicon Forest. Job losses at a local Intel Corp. campus underscored the risks of the citys reliance on the volatile high-tech sector.

SolarWorld, in turn, was wooed by the promise of trained silicon workers and a state tax credit that offset 35% of project costs. Local colleges launched programs to train workers in solar manufacturing. Flush with the potential, Hughes began recruiting other manufacturers, even traveling to trade shows in Germany and Spain to pitch solar suppliers on the promise of the Pacific Northwest.

At least a dozen companies drifted through town, some of whom looked pretty seriously at sites, Hughes said. But right about the time they would have been following through on funding, the whole thing fell apart.

SolarWorlds U.S.-made panels just couldnt compete with better and cheaper subsidized options from China. Even the Oregon Convention Center just 18 miles (28.968 kilometers) away opted for Chinese imports.

Obama won election to the White House in 2008 on a promise to create 5 million green jobs and a surge of solar projects in the sun-drenched Southwest promised to deliver many of them. When businesses and homes go solar, every panel is pounded into place by a worker whose job cant be outsourced, Obama boasted.

The work was spurred along by a 2005 tax credit that allowed developers to deduct 30 per cent of solar project costs. Although that tax break didnt require the use of American parts, the Obama administration tried to cultivate a domestic panel-making industry by paring tax bills for clean energy manufacturers, too.

The 2009 stimulus package created a separate 30 per cent tax credit to steer US$2.3 billion toward more than 180 advanced energy manufacturers, though only eight recipients made solar panels and the incentive program ran out of money after just one year. The Obama administration also funneled seed money to solar companies through a loan guarantee program created under Bush to nurture advanced energy technologies.

Before the Recovery Act, we could build just 5 per cent of the worlds solar panels, Obama said at that Solyndra LLC. facility. In the next few years, were going to double our share to more than 10 per cent.

But Solyndra defaulted on its US$535 million loan guarantee after almost all of it had been paid out, causing a scandal and casting an enduring pall over the program. The government largely stopped offering loan guarantees through the program by late 2011. And the U.S. didnt hit Obamas 10 per cent benchmark.

China was using every tool at its disposal to develop its own solar industry. Local governments offered cheap land andstate-backed banks provided friendly financing terms. Beijing also created demand for the products with generous subsidies that helped make the country the worlds largest purchaser of panels.

Chinese factories also worked to improve efficiency and reduce costs. For example, they used new tools to slice thinner polysilicon wafers with less waste, producing more solar cells from the same amount of raw material. That innovation has helped lower costs by 80%, making solar as cheap as coal now in many parts of the world.

The surge of cheap panels from China dealt a crushing blow to U.S. manufacturers and Solyndra wasnt the only casualty. After three other U.S. solar manufacturers sought bankruptcy protection, Obama in 2012 slapped duties as high as 249% on the imports. Manufacturers responded by moving operations out of China, but they didnt head to the U.S. Instead, large manufacturers skirted the U.S. tariffs by building facilities to assemble solar cells and modules across Southeast Asia.

Making matters worse, China retaliated by imposing its own duties of up to 57 per cent on imports of U.S.-made polysilicon tariffs that crippled U.S. producers of the conductive material used in solar panels.

Before the Chinese tariffs, U.S.-made polysilicon had been shipped to the country and used to produce ingots, the next stage of solar cell manufacturing. But the tariffs made American polysilicon too expensive, Wang said, and the U.S. went from making 50 per cent of the worlds polysilicon in 2007 to less than 5 per cent today.

Half the worlds supply of polysilicon now comes from Chinas Xinjiang region, where an estimated 1 million ethnic minorities, including Muslim Uyghurs, have been detained in counter-terrorism internment facilities in recent years, according to a panel of United Nations experts. The U.S., U.K., European Union and Canada have imposed sanctions against Chinese officials over alleged human rights abuses of Uyghurs, including accusations that forced labour is being used in Chinese factories. The Biden administration is weighing a ban on the import of some solar products containing polysilicon from the region too.

Beijing denies the human rights charges and has accused foreign governments of using forced labour claims as a way to help their own companies compete against Chinas. When the E.U. issued sanctions earlier this year, Chinas foreign ministry said they werebased on nothing but lies and disinformation.

Even the deployment of solar power in the U.S. which was aided by cheap imported parts suffered from uncertainty, as the investment tax credit was haltingly extended at least four times and came close to expiring twice.

Its been a stop-start policy one or two incentives, you build capacity, and then that was it, said John Smirnow, vice president of market strategy at the Solar Energy Industries Association. In a very competitive global environment, for U.S. manufacturers to succeed, especially new companies, you need the same broad-based federal investment that other governments are providing their industries.

Domestic solar panel manufacturing was already dwindling when Trump took office in 2017 with vows to crack down on China and put America first. Even though he was no champion of renewable energy, Trump extended his protectionist policies to the solar industry, too, imposing import limits and tariffs as high as 30 per cent on foreign solar cells and photovoltaic panels in 2018.

Trumps tariffs had the potential to help a handful of panel makersstay afloat, but at the expense of wide swaths of the domestic solar power industry. While manufacturers SolarWorld, Suniva Inc. and First Solar Inc. cheered on the tariffs, they were fiercely opposed by renewable power developers and installers who feared climbing panel prices would put them out of business.

The tariffs briefly boosted some U.S. manufacturers, as both SunPowerand First Solar increased production. ButAmericas hunger for solar power meant that imports from Asia climbed anyway, as domestic developers exploited a loophole to buy foreign-made double-sided panels not subject to the duties. And Trumps tariffs werent enough to save two of their biggest champions, the now-bankrupt Suniva and SolarWorld.

Though there are now some 231,474 solar jobs in the U.S., only 14 per cent of them are involved in manufacturing, with most of those workers building mounting systems, inverters and other components instead of the photovoltaic panels.

The U.S. is far from alone. Other early solar adopters, including Germany, have seen their panel making plummet. Germanys once-thriving PV wafer, cell, and module manufacturers are now largely gone, Ladislaw and other authors said in a February paper. All have been out-competed and driven into bankruptcy by the rapid cost reductions achieved by foreign firms.

Even some beneficiaries of Trumps tariffs arent pushing Biden to renew the levies when they expire next February. First Solar, for instance, has advocateda broader industrial strategyto spur domestic panel making.

Biden is trying to encourage renewable manufacturing with his multitrillion-dollar infrastructure package and a plan to revive thelapsed 2005 tax credit worth nearly a third of the cost of factories making solar panels. Buy-America mandates could also be imposed for federally funded solar projects, an idea advanced by several Republican senators.

But a few new U.S. panel plants would do little to loosen Chinas stranglehold on the rest of the solar supply chain, which extends beyond panels to the polysilicon that is used to make them. China now produces more than 80 per cent of the polysilicon and roughly 98 per cent of two other key components wafers and ingots that are used in panels worldwide, even those manufactured and assembled in other countries.

Theres no reason the blades for wind turbines cant be built in Pittsburgh instead of Beijing, no reason why American workers cant lead the world in the production of electric vehicles and batteries, Biden told a joint session of Congress earlier this year.

Were starting to plateau on existing solar technologies, and we need the next generation, Friedmann said. That is another opportunity for America to excel, because we have a great innovation system. We have an opportunity to leapfrog to the next generation.

There is a real opportunity to make lasting change to strengthen the industry here at home and create new jobs, said Wyden, the Democratic senator from Oregon who was at the Hillsboro plants opening. It will take coordinated effort across the government on everything from R&D, tougher enforcement of trade laws and reforms to the tax code to better incentivize domestic manufacturing, to level the playing field and get the U.S. back in the solar manufacturing game.

Still, its too late for solar workers in Hillsboro, a former farming community whose fortunes were once tied to the price of strawberries and by 2008 had become tethered to the volatile chipmaking industry instead.

The regions economy has managed to diversify despite the loss of the solar plant, though Intel remains one of Oregons biggest corporate employers and continues to give the city an occasional scare. Last year, for example, Intel spooked local residents when it reportedly mulledoutsourcing some advanced manufacturing to Asia.

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crushing and screening | mining equipment | pilot crushtec

crushing and screening | mining equipment | pilot crushtec

With a three-decade heritage of providing expert equipment solutions, technical support and expert advice, Pilot Crushtec International (Pty) Ltd is southern Africas leading supplier of quarrying and mining equipment. We are proud to offer a range of industry-leading OEM and in-house quarrying, mining, recycling and materials-handling solutions, including:

Mobile and semi-mobile crushing Screening Modular plants Recycling Stockpiling Materials-handling Spare and wear parts Mobile lighting Dust fighters Impactors Sand washing Technical support Repair services

Our team of experts and specialists is backed by 30 years of experience in the field, in the harshest environments and toughest applications. Thats why we only offer the best OEM product ranges which include jaw crushers, cone crushers, vertical shaft impactors (VSI), screens, skid frames, feeders, hoppers and conveyors.

With a three-decade heritage of providing expert equipment solutions, technical support and expert advice Pilot Crushtec International (Pty) Ltd is southern Africas leading supplier of quarrying and mining equipment. We are proud to offer a range of industry-leading OEM and in-house quarrying, mining, recycling and materials-handling solutions including:

Mobile and semi-mobile crushing Screening Modular plants Recycling Stockpiling Materials-handling Spare and Wear parts Mobile lighting Dust fighters Impactors Sand washing Technical support Repair services

Our team of experts and specialists is backed by 30 years of experience in the field, in the harshest environments and toughest applications. Thats why we only offer the best OEM product ranges which include jaw crushers, cone crushers, vertical shaft impactors (VSI), screens, skid frames, feeders, hoppers and conveyors.

Pilot Crushtec International (Pty) Ltd is South Africas leading supplier of mobile and semi-mobile crushing, screening, recycling, sand washing, stockpiling, compacting and material handling solutions. Our product range includes jaw crushers, cone crushers, vertical shaft impact (VSI) crushers, impact crushers, screens and conveyors.

new requirements for crushing operations in the coal industry

new requirements for crushing operations in the coal industry

In the entire coal industry, crushing is a very important step for coal preparation and primary processing. Because it affects sales and subsequent investment, it is also linked to the economic benefits of coal companies. The improvement of coal preparation technology and the further development of market economy have put forward new requirements for traditional crushing operations, which are mainly reflected in the following aspects:

Different washing equipment has different processing granularity ranges, and the requirements of washing equipment must be met through crushing operations. For example, the heavy-medium cyclone is widely used because of its high separation efficiency and strong adaptability, and its easy production and automation. However, if the particle size of the washing product exceeds the limit, it is easy to cause a plugging phenomenon, which makes it unable to play an efficient role. The crushing operation can strictly guarantee the particle size of the feed to solve this problem.

Coal users have very strict requirements on product particle size. Different users have different particle size requirements that vary with the market. If the requirements are not met, coal will be unsold or customers will refuse to pay due to excessive particle size, which will directly affect coal. Economic benefits of the enterprise. Also at different times, the prices of products with different granularity specifications are different, and enterprises must rely on effective crushing operations to obtain maximum profits.

Excessive crushing during the crushing process will not only cause waste of resources and affect the economic benefits of coal enterprises. The increase in moisture content of pulverized coal after selection will also increase the pressure on the slime water system and reduce the actual yield of refined coal. Minimizing the output of pulverized coal has become the key to the crushing operation in the context of increased environmental protection requirements and increased pulverized coal disposal costs.

During the coal washing process, coal must be effectively pulverized to maximize the dissociation of Yancoal monomer, increase the specific surface area of raw materials, and improve the quality of coal (reducing ash content) , Increase heat generation), remove harmful substances such as sulfur and phosphorus in coal, and reduce atmospheric pollution caused by coal combustion.

The production cost of crushing and grinding operation in the ore dressing plant will account for more than 40% of the total ore dressing cost, and the investment cost of these equipment will account for about 60% of the total investment in the ore dressing plant. Although the production cost of the crushing operation of the coal preparation plant and the proportion of infrastructure investment are lower than those of the ore dressing plant, the production costs and infrastructure investment of its preparation system have a relatively large impact on the technical and economic indicators of the coal preparation plant. So reducing crushing power consumption and increasing crushing productivity is of great significance.

1000-6000t/h coal or coal gangue crushing station large capacity double roller crusher for sale,mining crushing equipment mine crushing & screening

1000-6000t/h coal or coal gangue crushing station large capacity double roller crusher for sale,mining crushing equipment mine crushing & screening

GBZ series heavy-duty Apron Plate Feeder/ZSW vibrating feeder + 2DSKP series Double Roller Crusher + GS series Sizing Screen/Vibrating Screen + Complete electronic system + monitoring system + Supporting steel structure platform

The processing of coal gangue is divided into three stages: primary crushing of jaw crusher or double roller crusher, secondary or medium crushing of double roller crusher and sand shaping of sand making machine.

Large pieces of coal gangue are evenly fed by the vibrating feeder through the silo, and then transported to the jaw crusher for coarse or primary crushing. After primary crushing, the coal gangue is sifted through the vibrating screen, and then transported by the belt conveyor to double roller crusher for secondary and fine crushing.

Strong adaptability, aiming at coarse crushing and fine crushing screening system, both single unit can operate independently, and system can be flexibly combined to work together. Complete supporting electrical and monitoring systems can realize remote centralized control monitoring. The entire system is controlled by PLC with high intelligence. Advanced design, excellent performance, stable and reliable work, short construction cycle, high production efficiency, convenient use and maintenance, and low operating costs

how much does it cost to operate a crusher? | stedman machine company

how much does it cost to operate a crusher? | stedman machine company

Crushing equipment is the heart of an industrial material-processing system. The size reduction choice you make will have a profound impact on the profitability of your business. When the right choice is made, you should expect many years of profitable operation.

Crushers are not glamourous. They are brute force workhorses and what they do is simple, really. Size-reduction equipment in all forms is adding energy to a material to make big pieces smaller. Simple, right?

When the above costs are all accounted for, they are used to quantify the production costs related to size reduction and are expressed in cost per unit of measure production. For example, $0.50 per tph.

There are always opportunities to buy a machine at a lower upfront cost. This usually translates into paying higher operating costs over the life of the equipment. Higher service labor cost. Higher wear parts costs. Higher energy costs.

Often there is a justifiable case to spend additional capital dollars for the better machine. When evaluating crushing equipment suppliers, crusher manufacturers should quantify both costs: purchase price and operating costs. Before you purchase, ask for reference customers to visit.

Why are there so many types of equipment? Our team brainstormed this question, and we came up with more than 50 tools or machines that are used for size reduction. What we are addressing here is industrial size reduction of dry, solid materials, which are grown, mined or chemically synthesized, and need to have a physical dimension alteration to be put to use.

The variables above all affect your costs. Lets take the first question as an example. How long do you plan to operate? There are times when mines reserves, stockpiles, permits, project contract terms affect expected life.

If a project is limited by any factor, then good enough could be the best choice. As long as the equipment is safe and there are machine wear parts and service available, then going cheap may be the best choice. Another factor to consider with low-cost is limited post-sale assistance if there is some process change or major equipment problem. You dont want to be hung out to dry.

Aggregate producers typically expect to be running and profitable for many years. Always buy a crusher from an established company, develop a relationship, and expect ongoing service and personal contact. Ask before you buy about how they approach post-sale parts sales and service.

Ask the company quoting how they intend to offer service for their crusher. How many field service people do they have? Are they local, regional or too far away? Not having responsive suppliers will have a significant impact on your plant profitability.

coking coal - an overview | sciencedirect topics

coking coal - an overview | sciencedirect topics

Coking coal is an essential input for production of iron and steel. The largest single use of coal in the steel industry is as a fuel for the blast furnace and for the production of metallurgical coke for reduction of iron ore or for injection with the hot blast. Most of the export trade is a low-volatile hard coking coal with a high swelling index and good fluidity. Over 66% of steel production relies on inputs of coal. World crude steel production was 1.6 billion tons in 2013. Around 0.6 t (600 kg) of coke produces 1 t (1000 kg) of steel, which means that around 770 kg of coal are used to produce 1 t of steel through this production route [10].

The most commonly applied process for steel making is the integrated steel-making process via the blast furnacebasic oxygen furnace which produces about 70% of the worlds steel. A further 29% of steel is produced in electric arc furnaces.

Coke is produced by baking coal in the absence of oxygen to remove the volatile hydrocarbons contained in coal. The resulting coke is mechanically strong, porous, and chemically reactive, which are all critical properties for stable blast furnace operation. In addition to supplying carbon for heat and the reduction of iron ore, coke must also physically support the burden in the blast furnace shaft and remain permeable to the hot air blast entering from the bottom. Coke making is extremely problematic from an environmental perspective, as many of the hydrocarbons driven off during the coking process are hazardous. Also, not all types of coal are suitable for the production of coke.

The impurities in coal affects the quality of coke produced. Such impurities are moisture, volatile matter, ash, sulfur, phosphorous, and alkali contents. Their levels are kept as low as possible as their presence in coke affect its performance in the blast furnace by decreasing its role as a fuel in terms of amounts of carbon available. Sulfur and ash are particular importance because when they increase, coke productivity in the blast furnace decreases. Ash content must not have more than about 8%. It was reported that a 1% increase of ash in the coke reduces metal production by 2%3% wt [11]. That is the reason why all coking coals in full range of particle sizes are washed in coal preparation plants.

The rank and the chemistry of the coal strongly influence of the textures of cokes. The carbonization characteristics of the individual entities in the coal determine the nature of the coke produced. Coal must fall within a particular range in rank for the coking process to occur. The stage of coalification (rank) affects the strength of the bond and its ability to assimilate inerts. The coal must have a comparatively high content of vitrinite to form a hard metallurgical coke. The stage of coalification together with the percentages of reactive and inert entities can be used to calculate the strength of the resultant coke [12,13].

Basically, coal consists of reactive and inert materials. The reactives includes macerals namely vitrinite, liptinite, and one-third of semifusinite, which soften on heating during carbonization, become plastic and solidfy into a porous, fused, solid carbon material and bind inerts which contain two-thirds of semifusinite, fusinite, macrinite, micrinite, inertodetrinite, sclerotinite, and mineral matter. Inerts remain unaltered on heating and then act as aggregate during carbonization. Polish and Australian metallurgical coal specification are given in Tables 3 and 4.

Prime coking coals are usually more expensive than other coals, e.g., steam coals, and are becoming less readily available. Research on coke making seeks to take advantage of insights that may help to reduce the proportion of prime coking coals utilised in coke blends and to expand the range of coals that could be used in these operations (Sasaki et al. 1998). Shifting the coke blend composition toward weakly coking coals is therefore commercially attractive. Useful summaries of the vast literature on conventional coking operations may be found in standard texts (e.g., Elliott, 1981; Kumar et al., 2009; Speight, 2012).

Meanwhile, some low-rank bituminous coals remain morphologically unchanged when heated slowly (~1C s1), but soften or melt under rapid heating conditions (e.g., 1000C s1) (Hamilton, et al., 1979; Hamilton, 1980; Gibbins-Matham and Kandiyoti, 1988). In searching for ways to improve coke-making, Aramaki et al. (1996) demonstrated at bench scale that when weakly coking coals were first preheated rapidly to temperatures up to 400C, and then heated slowly to temperatures of 900C or higher, a coke of increased strength could be obtained. Ohtsuka et al. (1996) also reported that the swelling ability and softening properties of coals could be improved by rapid pre-heating to their softening temperatures; the heating rates used in that work ranged between 5C and 500Cmin1.

At Nippon Steel Corporation, experimental observations showing links between heating rates and coal plasticity led to a pilot-scale application aimed at improving the coke production process. The concept involved rapidly pre-heating crushed coal in a riser to about 400C. The resulting mass of sticky particles collected in a retort was then slowly heated to 800900C. The overall effect was to form a stronger coke than would have otherwise been possible by heating the same coal (or blend) in the same retort slowly from ambient temperature (Aramaki et al., 1996). The procedure was found to be effective for improving the coking properties of weakly coking coals. For prime coking coals, however, the initial rapid-heating step provided no significant improvement in the amount or strength of the coke product.

When coking coal to gasification coal ratio is 7, there is sufficient hydrogen supplied by the COG tri-reforming. The WGS unit can be cancelled in the new COG-CTM process, as shown in Figure4. As the WGS unit is no longer needed in the COG-CTM process, the main operating parameters of the AGR unit and TRM unit will change accordingly. If scale of the coal gasification is 2 Mt/y, the coking scale is thus 14 Mt/y. At present, there is no thus scale of coal coking plant in China. However, this new COG-CTM process without the WGS unit can be used for planning new industrial parks.

To achieve an ash reduction of 3%4%, dry destoning of ROM coal by a rotary breaker can be used. However, there should be a difference in the crushability index between rock and coal for effective utilisation of a rotary breaker.

The beneficiation of fine coal is not taken into consideration as the ash content may not be as high as that of coarser coal. Thus, the coarser fractions are beneficiated by a coarse coal jig. The beneficiated coal is mixed with untreated fine coal so as to achieve an ash content of 34% as required by power houses. To elaborate, coarse coal normally of size >13/30mm is washed in a jig and the finer fraction is sidestepped and mixed with washed product.

To meet the quality requirements of sponge iron and cement industry, deep cleaning is necessary. Both coarse and intermediate sizes are washed in combination with an HM bath, HM cyclone and modern jig. Although flotation is the conventional method, fine coal can be treated in a blend of spiral, reflux classifier and enhanced gravity separators. Thus far, the latest technology of fine coal beneficiation has not been properly adopted in India.

In 2010 the top coking coal exporters included Australia, the United States, Canada, Russia, Indonesia, South Africa, and Colombia. The largest importers of coking coal included Japan, China, India, South Korea, Germany, Turkey, and Taiwan. Table4.3 provides a summary of the estimated export and import tonnages for these nations.

DOE/EIA projects Australia will continue to dominate the world coking coal trade in the future, as it has in the past. This is illustrated in Fig.4.5, projections of coking coal exports by nation. Of the estimated 95 Mt increase in worldwide coking coal exports between 2011 and 2035, Australia is expected to account for nearly 70% of that additional tonnage. Coking coal exports from Southern Africa, the former Soviet Republics, and Canada are also expected to grow significantly, while exports from other nations will remain flat, or even decline somewhat.

Two-thirds of the increased exports in coking coal will be absorbed by Asian nations, primarily India and China; about 30% of the increased coking coal exports are projected to be consumed in the Americas, presumably in Brazil and Chile; and the remaining increase in export tonnage is expected to be consumed in Europe. Table4.4 provides summary values from DOE/ EIA. Clearly, Asia is expected to drive the expansion of export coking coal in the future, particularly the dynamic economies of India and China.

Cretaceous and Carboniferous coking coals differ petrographically in the relative amounts of vitrinite and semi-fusinite they contain and in the fluidities of the whole coals (1). A sufficient amount of work has been done to demonstrate that Cretaceous semi-fusinite is at least partially reactive in coking and that, industrially, good quality coke can be produced from these coals(2,3). This report focuses on a direct comparison of four carefully chosen pairs of Carboniferous and Cretaceous coals covering a range of rank in reflectance terms of RO, max = 0.88 to 1.66%. The purpose of this continuing work is to gain some insight into how the two types of coal behave relative to each other and to attempt to explain the origin of differences when these occur. One of the key issues in this regard is the response to air oxidation. The rheological properties of these coals have been used as a probe for the course of oxidation reactions. In this study, in order to mimic natural oxidation we have chosen to react the coals with air at a relatively low temperature, i.e. 50C, and have speeded up the reaction by increasing the pressure.

Strongly caking coals, with low ash, sulphur, and phosphorus preferred. N.C.B. types 301 to 401. GrayKing coke types G.4 to G.9. Ash <5%, sulphur < 1%, phosphorus <0.012%. Size grading < 5 mm, 80% < 3 mm, H2O 5% top charging, 10% stamper charging.

The processing of lower horizon combined V/VI/VII seam coal should also be considered. This combined seam has a high rank and low volatile matter and is known as low volatile coking (LVC) coal (Table8.9). LVC coal has difficult-to-wash characteristics due to typical geological formation, finely inter-grown mineralogy and high NGM at the desired cut point densities. The majority of the remaining Indian metallurgical coal reserves belong to the LVC category. LVC coals mostly outcrop near the fringe areas of coalfields, which present an easier option for fully mechanised opencast mining as they are characterised by low overburden, coal ratio and low slope. At present, a large proportion of this type of coal is used by the power industry and in general accepted as ROM coal, or after minimal cleaning at 34% ash, because of various market issues. These coals could also be used in coal blends for producing metallurgical coke after washing to below 18% ash level (Table8.9).

Recognising the importance of LVC coal as the main source of Indian metallurgical coal supply, the major Indian institutions (CIMFR, CMPDI, etc.), the former in particular, have developed design schemes for multilevel washing of these coals. Advantages of these schemes are relatively coarse crushing, low washing cost, multi-product washing, simple moisture removal operations, etc. The common features of all of these schemes are:

In another approach (by the Indian School of Mines), emphasis has been placed on recovering more metallurgical coal through DMC washing. This requires fine crushing, so that more liberation is achieved. The entire LVC coal is crushed to 13mm or even finer followed by a sized washability study (Table8.10). For this approach, the yield of clean coal at the same ash is ~1.5 times greater and nearly 3 times greater at the reduced ash content as compared to the CMPDI scheme. Disadvantages include high washing cost, complicated moisture removal schemes, significant generation of fines with difficult handling characteristics, etc.

Testing has shown that significantly improved clean coal yield is obtained but only in the size range of 3mm, with little change between the 3 + 0.5mm and 0.5 + 0.1mm fractions. The yield increases in the 0.1mm fraction. Significant liberation of carbonaceous matter from associated mineral matter appears to effectively occur when the coal is crushed down to 3mm with a quantum increase in liberation at the size of 1mm.

A common pattern observed in the washability and beneficiation characteristics of LVC coal is that there are certain differences occurring within the same coalfield e.g., between the western and eastern flanks of the Jharia coalfield with yields sometimes as low as 1625% at 1819% ash. Efficient utilisation of LVC coals for metallurgical application would therefore require addressing the problems and related issues:

As the reserves of good-quality coking coals of upper seams are almost depleted, low volatile medium coking (LVMC) coals of lower seams have become the alternative choice. These coals, being of lower seams are likely to be more mature (Ro ~1.3) than the upper seams and consequently exhibit lower values of volatile matter (Kumar and Saxena, 2014). They constitute about 50% of the total coking coal reserves of India. These coals are characterised by high ash content and difficult cleaning potential. Proper utilisation of these LVMC coals for metallurgical purposes after suitable beneficiation will not only help in reducing the dependence on imported coal but also minimise the present improper utilisation for power generation.

These coals generally occur in the lower seams of Jharia Coalfield (combined seam V/VI/VII/VIII and individual seam II, III and IV) and Karo group of seams (seam VI to XI) in the eastern part of East Bokaro Coalfield of the Damodar Valley basin. These coals have at present not found entry into the steel industry. The laboratory and pilot plant investigations on these coals after washing at 10%, 15% and 17% ash levels have firmly demonstrated that the coals show good coking properties and can be blended in a proportion up to 20% to produce good-quality blast furnace coke (Mishra and Chopra, 2013). The yield percentage of the cleans is also encouraging, and hence, these coals can be considered for utilisation in the metallurgical industry for coke making.

Generally, washability of LVMC coal can be improved by crushing it to smaller size. The difficult washability characteristics of LVMC coals are due to fine dissemination of mineral particles with macerals. The ash % of marketable product can be further improved by blending with prime coking coal, so that this coal can be used in various steel plants.

Coal India Ltd. has taken the initiative to set up six washeries with a total capacity of about 19Mt/y for washing LVMC coal in BCCL and CCL (Table 7.9). The mode of setting up of five washeries in BCCL is under a BOM concept, i.e., buildoperationmaintenance basis, through a global bidding process. Coal India Ltd. will provide the funds and infrastructure facilities like land, power, water, railway sidings. Another washery of 2.5Mt/y capacity has been envisaged to wash LVMC coals at CCL and is to be set up on a turnkey basis. The real task is to wash these coals with suitable washing techniques and to obtain 25%30% yield at 17%18% ash levels. The middlings are to be used in the power sector.

It is not known how far the dilution effect has been considered. If the ash content of ROM coal increases by 3%5%, the whole washing circuit will be imbalanced. The dilution effect has been discussed in Section 1.4.2.

There is a basic difference between blending and mixing. In the case of mixing, individual components are supposed to be of uniform characteristic, and if their ratio is correctly maintained then a homogeneous product can be made. On the other hand, even if one or more of the components are variable in nature, it is possible to obtain a homogeneous mixed product by a proper blending system. It should be realised that coal is a heterogeneous material varying in physical and chemical properties. This divergence is found even in the same seam. These properties may be density, hardness, size, coking properties, cleaning characteristic, ash content, volatile matter, sulphur content, calorific value, etc. Every coal-based industry requires coal with proper consistency in any one or more of the above characteristics. The use of coal from different sources with divergent characteristics reduces the efficiency of the plant and the quality of products. The purpose of blending is to reduce this variability so that an average mean value of some property or character of the blended product is obtained.

In India, central coal washeries are finding it increasingly difficult to blend and stock raw coals supplied from different sources. Sometimes the inputs can be from more than 25 collieries for a single washery unit. For efficient operation of a washery, consistent quality of raw coal feed is needed. By proper blending of raw coal, the capacity utilisation of the plant is increased, its operational and maintenance problems are reduced, and at the same time better-quality products are obtained. Blending should be done for coals received from diverse sources for the entire shift or day.

To conserve high-grade prime coking coal, it is essential to blend the prime coking coal with inferior coking coal without affecting the quality of the product mix. Blending is also required for the metallurgical industry. Blending of a blast furnace charge can bring about many advantages to the steel plants in the following ways:

Indian iron ores are very aluminous, and this cannot be removed by a simple beneficiation process; the correction of the alumina silica ratio is possible by blending aluminous ores with siliceous ores. The consistency in chemical and physical quality of blast furnace charge is only possible through a proper blending system, e.g., bed blending. This may appear to be very costly, but the cost incurred will be recovered by consistent hot metal production (Kumar, 1982).

coal crushing: new-type toothed roll crusher vs traditional toothed roll crusher | hxjq

coal crushing: new-type toothed roll crusher vs traditional toothed roll crusher | hxjq

In the coal industry, the requirements for the particle size of the finished product are extremely strict. Generally, the particle sizes of the finished products are between 25 and 70 mm. If it is too large, the furnace will be blocked and further coal processing can't be performed.

Toothed roll crusher is the mature coal crushing equipment applied in the current coal industry, which satisfies all the demands of customers by its advantages of large capacity and low over-crushing rate.

Based on the original toothed roll crushers, HXJQ Mining Machinery has optimized the structure and materials of rollers according to the customers' requirements, so that to adapt the nature of hard gangue and special working conditions and ensure the normal production of coal enterprises.

Traditional toothed roll crusher is usually driven by double-motors. Two sets of motors, couplers and reducers are adopted to drive the independent rollers so that the rollers have the power to crush large coal materials.

The coupler is applied between reducer and rolls to transfer torque. And the toothed rollers and drive system are connected with the machine frame respectively to eliminate the vibrating of toothed roll crusher.

Traditional toothed roll crusher with ring structure has the advantages of stable and reliable performance, and the disadvantages of low wear resistance and hard to replace. Once the traditional toothed roll crusher is damaged, it must be returned to the factory for overhaul.

The traditional rollers are connected by the bolts and tooth-holders, which offers small bearing capacity. Therefore, the traditional toothed roll crushers are mainly applied in the clean-coal crushing process, because the raw coal will cause damage to roll crusher teeth.

In terms of tooth position, the roll crusher teeth are set in the peripheral direction, adopting the setting form of large tooth alternating with a small one. Under the premise of normal discharging size, the crushing force of roller can be improved efficiently, so that to increase the capacity, wear-resistance and service life.

As the picture shows, the new-type tooth-holder adopts the form of regular octagon. The toothed rollers and toothed holders are connected by the flat kay and socket head cap screws (the traditional ones are connected by bolts).

The contacted areas between tooth and toothed holders are processed and improved completely, and torque is transferred by flat key so that can prevent the socket head cap screws from the shearing force of coal materials. And the screws can be firmer and more reliable.

Meanwhile, the fastening bolt and the toothed roller holder are connected by the screw fastening blocks, which makes that the joint strength is ensured, and the interchangeability and the replaceability are also reliable.

The teeth are the main wearing parts of the toothed roll crusher, so it is very necessary to choose a suitable material. Therefore, it is required that the material should have enough hardness, toughness, impact resistance and wear resistance. Also, the following machinability and weldability should be considered.

When parts of high manganese steel are impacted repeatedly, the surface of parts gets changed, and the hardness increases rapidly, which can reach up to HRC54. It will improve the wear resistance significantly, but the inside of parts keeps flexibly. These are the main features of high manganese steel.

However, the toothed roll crushers crush coal materials by shearing and stretching, along with less impacting and squeezing, which makes high manganese steel can't play its advantages to enhance the hardness and strength. Therefore, high manganese steel is not suitable for making teeth.

To better improve the wear-resisting performance of teeth, traditional toothed roll crusher always adopts the low-alloy quenched and tempered steel as the material to make tooth of roll crushers. In general, 40 Cr is used to process the tooth. After processing, the compressive strength and the service life of tooth are improved.

However, since there are only a few millimeters thick wear-resisting layer in the surface of the tooth, it is required to be overlaid frequently in the process of use, which brings a large workload to workers.

The teeth of the new toothed roll crusher adopt the integral casting molding process, optimizes the proportion of the main elements such as C, Cr, Mn, Mo, Si, Ni. The medium carbon bainitic steel is selected finally to be the material of toothed roll.

The medium carbon bainitic steel has good hardenability. After quenching and tempering heat treatment, bainite with high hardness and wear resistance is processed. It has an excellent comprehensive performance of HRC50 hardness and compressive strength of 1500 MPa.

In addition, the material of the entire toothed roller structure, including the toothed roller, the toothed roller holder and the threaded fastening block, is reasonably matched, so that the strength and hardness of each component are more balanced and reasonable.

The raw coal is first crushed to below 300mm by the jaw crusher, and then crushed to below 70mm by a toothed roller crusher, and then transported to the coal storage bin by the belt conveyor. After screening, the final product of 25~70mm is sold to the chemical company.

The customer said it requires technical improvement urgently in their worksite urgently to reduce the operating cost of the enterprise and the labor intensity of the workers and to ensure the normal operation of the production system.

Since the new toothed roller crusher was put into use, the equipment has been running stably, the discharge size of the products is significantly improved, the over-crushing rate reduces, and the block-forming rate is highly increased (see the following table).

It can be seen from the above table that the difference between the qualified products before and after the replacement is 18.2%, which greatly improves the output of qualified products and creates great economic benefits for the enterprise.

In addition, the new toothed roller crusher has high wear resistance, and the fastening bolt is not easy to loosen, which reduces a large amount of maintenance time, the labor intensity of workers, and the maintenance cost of the coal crushing process.

With the transformation and upgrading of the coal industry, it is an inevitable trend to vigorously develop coal chemical industry. The coal chemical industry has strict requirements on the particle size of coal, which puts higher requirements on the crushing equipment.

The new toothed roller crusher can optimize the crushing operation of the raw coal by a series of optimizations on the structure and material of the toothed roller. It has a high block rate and a small maintenance amount. With the obvious technical advantages, the promotion prospects of new-type toothed roll crusher are broad.

henan mining machinery and equipment manufacturer - cost of starting crushing business

henan mining machinery and equipment manufacturer - cost of starting crushing business

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Ore beneficiation equipment, sand making equipment, crushing equipment and powder grinding equipment, which are widely used in various industries such as metallurgy, mine, chemistry, building material, coal, refractory and ceramics.

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