Since China began to produce sodium dichromate in 1958, nearly half a century ago, the chromium salt industry has made great progress, becoming the largest producer and consumer of sodium dichromate in the world, and the company’s scale, industrial technological progress and concentration. Other areas have made great progress. At the same time, the current problems in the chromium salt industry are also prominent. It is imperative to promote the development model of circular economy.
The structural contradictions highlight that the scale of foreign chromium salt companies is basically 50,000 tons/year or more, and the scale of a single production unit is generally more than 30,000 tons/year. Basically calcium-free roasting production technology is used, and the production capacity is quite concentrated; while domestic chromium There are more than 20 salt companies, and the scale is generally around 20,000 tons/year. The products of foreign large-scale chromium salt plants often exceed 10, for example, there are dozens of chromium salts in Germany's LANXESS, and there are also more than 10 varieties in the UK. However, there are only 20 or 30 types of chromium salts in China, most of which are reagents, and the industrial variety does not exceed 10, of which only 5 or 6 varieties are produced by chromium salt plants. The status quo of fewer varieties, small scale, and low output limits the deep processing of chromium salt companies.
Some domestic chromium salt companies still use coal as fuel, and the energy consumption of the industry is generally higher, which is mainly reflected in the production of sodium dichromate by calcium-free roasting method. Compared with the average power consumption of five key chromium companies in China, the average power consumption in foreign countries is 100 kWh/ton lower, and the average steam consumption is lower than 0.25 tons steam/ton. With regard to electricity consumption and steam consumption, the comprehensive energy consumption of domestic chromium salt companies is approximately 300 kg of standard coal per tonne of sodium dichromate. In terms of equipment automation, resource utilization, labor productivity, product quality, “three wastes†emissions, and corporate management, domestic companies have a large gap with foreign countries, affecting the competitiveness of the entire industry.
Chromium residue utilization did not find the ideal way
The main components of chromium slag are sodium chromate and chromium compounds containing various ions. Due to the presence of Cr6+, serious environmental pollution can easily occur if strict treatment measures are not taken. The composition of chromium slag mainly depends on the origin, grade, filler formula and production technology of chromite. Under normal circumstances, the total chromium content (calculated as Cr2O3) is 3% to 7%, and the water-soluble Cr6+ content (calculated as Cr) is 0.5. % ~ 1.5%, acid-soluble Cr6 + content (Cr) is 0.4% ~ 1.0%. Chromium slag Under the long-term effects of natural rainwater and CO2, the acid-soluble Cr6+ will gradually turn into water-soluble Cr6+. Cr6+ has strong oxidative properties and its toxicity lies in the oxidation of living cells. Exposure of human body to Cr6+ can cause skin irritation and allergy, mucosal ulcers, erosive rhinitis, and nasal perforation of the diaphragm. In particular, the small amount of calcium chromate contained in the chromium residue is listed by the International Agency for the Study of Cancer as a substance that has been sufficiently proven to be carcinogenic to animals. As long as the water contains a few parts per million Cr6 + can present a unique bright yellow, causing environmental panic. Therefore, chromium residue has been listed as one of the hazardous wastes by the State Environmental Protection Administration.
With current production capacity, China's chromium salt companies generate nearly 600,000 tons of chromium-containing waste residue each year. Although some new technologies have been adopted to partially deal with them, due to the large amount of existing stocks of many old companies, it is very difficult to handle them in the short term, and some companies' existing slag yards can hardly meet the long-term requirements. As for the storage requirements, many chromium salt companies have taken measures such as deep mountain discharge and storage of waste slag.
Calcium roasting technology is still widely used The world's sodium dichromate production process mainly includes calcium-free roasting, low-calcium roasting, and calcined calcining. At present, the major advanced countries in the production of chromium salts mainly use the low-calcium roasting method and the calcium-free roasting method. However, in the developing countries, the relatively backward calcined calcining method is still used. Calcium roasting process has large emission of chromium residue and serious environmental pollution. The calcium-free roasting process eliminates dolomite and limestone in the batching process, thereby reducing the discharge of chromium-containing waste residue and reducing the content of Cr6+ in the waste residue. Waste slag treatment is easier and processing costs are greatly reduced.
In order to reduce the environmental pollution caused by the production of chromium salts, the production of chromium salts in the United States, Japan, Russia and other countries has grown toward the direction of concentration and large-scale production. For example, in the United States, there are currently only two chromium salt producers, namely U.S. Chromium and Chromide Corporation and U.S. Western Petroleum Corporation, with a production capacity of over 200,000 tons/year; Russia has 3 chromium salt plants with a production capacity of 180,000 tons/year. Years or more; UK business capacity is 135,000 tons/year; Japan is 50,000 tons/year. The large-scale production of chromium salts and less concentrated pollution sources are conducive to environmental governance and will help improve the economic efficiency and market competitiveness of enterprises.
Insufficient self-sufficiency of chromite raw materials
Chromite has been one of the country's most deficient mineral products. China's chromite reserves are low, production is low, and the deposits are small and located in remote areas. At present, China's proven reserves of chromite are only over 10 million tons, which is less than 0.01% of the world's total reserves. In 1995, China established the largest chromite ore production base in Luobusha, Tibet. The total proven reserves are only 2.46 million tons. The designed annual production capacity is only 150,000 tons, and the annual output is about 100,000 tons. The annual chromium ore production in the country Also about 200,000 tons. Due to a serious lack of self-sufficiency, China has become a pure importer of chromite. In 2005, China consumed 3.24 million tons of chromite, of which imports accounted for about 93%.
Promote the development mode of circular economy
The development mode of the recycling economy in the chromium salt industry is the use of advanced and clean production processes, the development of chromium salt series products, the realization of deep processing, and eventually the formation of industrial chain and series of large-scale production bases. Manufacturers should follow the “3R†principle of “reduction, reuse, and resource recycling†to minimize the consumption of materials, energy, and water resources. The industrial structure pursues the horizontal coupling and vertical closure between the industrial chains, strengthens the symbiosis network construction among the production units, and maximizes the realization of “waste†resources and cascade utilization of energy and water. One of the development models of the recycling economy in the chromium salt industry is shown in the lower left diagram. All chromium salt companies, especially chromium salt companies that need to expand their technological transformation, can design according to a new process route to achieve the lowest energy consumption.
The structural contradictions highlight that the scale of foreign chromium salt companies is basically 50,000 tons/year or more, and the scale of a single production unit is generally more than 30,000 tons/year. Basically calcium-free roasting production technology is used, and the production capacity is quite concentrated; while domestic chromium There are more than 20 salt companies, and the scale is generally around 20,000 tons/year. The products of foreign large-scale chromium salt plants often exceed 10, for example, there are dozens of chromium salts in Germany's LANXESS, and there are also more than 10 varieties in the UK. However, there are only 20 or 30 types of chromium salts in China, most of which are reagents, and the industrial variety does not exceed 10, of which only 5 or 6 varieties are produced by chromium salt plants. The status quo of fewer varieties, small scale, and low output limits the deep processing of chromium salt companies.
Some domestic chromium salt companies still use coal as fuel, and the energy consumption of the industry is generally higher, which is mainly reflected in the production of sodium dichromate by calcium-free roasting method. Compared with the average power consumption of five key chromium companies in China, the average power consumption in foreign countries is 100 kWh/ton lower, and the average steam consumption is lower than 0.25 tons steam/ton. With regard to electricity consumption and steam consumption, the comprehensive energy consumption of domestic chromium salt companies is approximately 300 kg of standard coal per tonne of sodium dichromate. In terms of equipment automation, resource utilization, labor productivity, product quality, “three wastes†emissions, and corporate management, domestic companies have a large gap with foreign countries, affecting the competitiveness of the entire industry.
Chromium residue utilization did not find the ideal way
The main components of chromium slag are sodium chromate and chromium compounds containing various ions. Due to the presence of Cr6+, serious environmental pollution can easily occur if strict treatment measures are not taken. The composition of chromium slag mainly depends on the origin, grade, filler formula and production technology of chromite. Under normal circumstances, the total chromium content (calculated as Cr2O3) is 3% to 7%, and the water-soluble Cr6+ content (calculated as Cr) is 0.5. % ~ 1.5%, acid-soluble Cr6 + content (Cr) is 0.4% ~ 1.0%. Chromium slag Under the long-term effects of natural rainwater and CO2, the acid-soluble Cr6+ will gradually turn into water-soluble Cr6+. Cr6+ has strong oxidative properties and its toxicity lies in the oxidation of living cells. Exposure of human body to Cr6+ can cause skin irritation and allergy, mucosal ulcers, erosive rhinitis, and nasal perforation of the diaphragm. In particular, the small amount of calcium chromate contained in the chromium residue is listed by the International Agency for the Study of Cancer as a substance that has been sufficiently proven to be carcinogenic to animals. As long as the water contains a few parts per million Cr6 + can present a unique bright yellow, causing environmental panic. Therefore, chromium residue has been listed as one of the hazardous wastes by the State Environmental Protection Administration.
With current production capacity, China's chromium salt companies generate nearly 600,000 tons of chromium-containing waste residue each year. Although some new technologies have been adopted to partially deal with them, due to the large amount of existing stocks of many old companies, it is very difficult to handle them in the short term, and some companies' existing slag yards can hardly meet the long-term requirements. As for the storage requirements, many chromium salt companies have taken measures such as deep mountain discharge and storage of waste slag.
Calcium roasting technology is still widely used The world's sodium dichromate production process mainly includes calcium-free roasting, low-calcium roasting, and calcined calcining. At present, the major advanced countries in the production of chromium salts mainly use the low-calcium roasting method and the calcium-free roasting method. However, in the developing countries, the relatively backward calcined calcining method is still used. Calcium roasting process has large emission of chromium residue and serious environmental pollution. The calcium-free roasting process eliminates dolomite and limestone in the batching process, thereby reducing the discharge of chromium-containing waste residue and reducing the content of Cr6+ in the waste residue. Waste slag treatment is easier and processing costs are greatly reduced.
In order to reduce the environmental pollution caused by the production of chromium salts, the production of chromium salts in the United States, Japan, Russia and other countries has grown toward the direction of concentration and large-scale production. For example, in the United States, there are currently only two chromium salt producers, namely U.S. Chromium and Chromide Corporation and U.S. Western Petroleum Corporation, with a production capacity of over 200,000 tons/year; Russia has 3 chromium salt plants with a production capacity of 180,000 tons/year. Years or more; UK business capacity is 135,000 tons/year; Japan is 50,000 tons/year. The large-scale production of chromium salts and less concentrated pollution sources are conducive to environmental governance and will help improve the economic efficiency and market competitiveness of enterprises.
Insufficient self-sufficiency of chromite raw materials
Chromite has been one of the country's most deficient mineral products. China's chromite reserves are low, production is low, and the deposits are small and located in remote areas. At present, China's proven reserves of chromite are only over 10 million tons, which is less than 0.01% of the world's total reserves. In 1995, China established the largest chromite ore production base in Luobusha, Tibet. The total proven reserves are only 2.46 million tons. The designed annual production capacity is only 150,000 tons, and the annual output is about 100,000 tons. The annual chromium ore production in the country Also about 200,000 tons. Due to a serious lack of self-sufficiency, China has become a pure importer of chromite. In 2005, China consumed 3.24 million tons of chromite, of which imports accounted for about 93%.
Promote the development mode of circular economy
The development mode of the recycling economy in the chromium salt industry is the use of advanced and clean production processes, the development of chromium salt series products, the realization of deep processing, and eventually the formation of industrial chain and series of large-scale production bases. Manufacturers should follow the “3R†principle of “reduction, reuse, and resource recycling†to minimize the consumption of materials, energy, and water resources. The industrial structure pursues the horizontal coupling and vertical closure between the industrial chains, strengthens the symbiosis network construction among the production units, and maximizes the realization of “waste†resources and cascade utilization of energy and water. One of the development models of the recycling economy in the chromium salt industry is shown in the lower left diagram. All chromium salt companies, especially chromium salt companies that need to expand their technological transformation, can design according to a new process route to achieve the lowest energy consumption.
Pillow Block Bearings,The Pillow Block Bearing Series,Ff12 Pillow Block Bearings,Pillow Block Bearing
UKL Bearing Manufacturing Co., Ltd., , https://www.bearingukl.com