Micro-silica fume at home and abroad, an overview of the application
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Abstract: micro-silica fume (silica fume) is a silicon metal or ferrosilicon alloy smelting and so on from the flue gas recovery in the dust. In this paper, the micro-silica fume at home and abroad and the recovery in the concrete, refractories, cement production in such areas as outlined in the application of micro-silica fume and market research conducted on this basis both at home and abroad for market forecasts and prospects Prospect.
Key words: micro-silica fume / refractory ultrafine silica fume concrete-industrial waste
Also known as micro-silica fume silica fume, silica fume (silica fume, micro-silica), silicon metal or ferrosilicon alloy smelting and so on from the flue gas recovery in the dust. At present, the market's micro-silica fume, is part of the smelting flue gas filter through the collection of direct sales after the silica fume, but also is part of the smelting flue gas filter through the collection after the re-processed sales of silica fume. The average size of micro-silica fume 0.15-0.20μm, specific surface area for 15000-20000m2/kg. The main ingredients of silicon dioxide, the general content of 80-92% aerobic component of impurities Sodium, calcium oxide, magnesium oxide, iron oxide, alumina and activated carbon, and so on. Mineral composition, smelting process, collecting system and so can cause fluctuations in the composition. As the micro-silica fume in an amorphous material, high activity, small particles, surface area, have excellent physical and chemical properties, in the past was considered a waste industry is now increasingly seen as a Valuable resources, without going through a crush processing, low-cost ultrafine body. Can be widely used in the special concrete used in the project, refractories, cement, and other important areas.
We have a variety of information resources, including paper, network, telephone surveys, discussions with business channels such as the application of micro-silica fume and market research conducted in this paper on the research results summarized in the hope of promoting China's micro-depth research and silica fume Application development and narrow the gap between the country's strengths and enhance its international competitiveness.
1 micro-silica fume in the application of foreign
As early as 1947, Norway's Aiken (Elkem ASA) on the start of the micro-production technology of silicon powder and dust processing, grading and applied research, the world's first conduct research and development of silicon powder micro-enterprises, and always in the silicon micro - Powder collecting and processing technology to maintain its leading position. Subsequently, the United States, Russia, Japan began to conduct applied research and development, and become a major producer of fine silicon powder. At present, the micro-silica fume-year production: 300,000 tons the United States, Russia 150,000 tons, 120,000 tons Norway, Japan 70,000 tons. Abroad to micro-silica fume-based applications that can be developed:
1.1 high-strength concrete admixture industry Agent
Micro-silica fume as a blending agent used in the concrete industry is the comprehensive utilization of foreign micro-silica fume in the first study, results of the largest, most widely used in the field of a. As the micro-particles of silicon powder with a small surface area large, SiO2 purity of high volcanic ash activity, such as strong physical and chemical characteristics of the micro-silica fume as a blending agent to join the concrete improvement in the performance of the various concrete. If the marked improvement in adhesion properties of plastic and concrete pool, a significant reduction in the rebound, increasing the thickness of forming a shotcrete, to shorten the construction period, the project cost savings.
In the special needs of high-strength concrete occasion, micro-silica fume as a high-strength concrete admixture preparation, the level of intensity can be 100 MPa. Foreign many important high-rise buildings, such as the United States and Frankfurt, Germany buildings Nan Wake BfG buildings are doing fine silicon powder used to strengthen concrete admixture agent. In developed countries, some of the major water conservancy and hydropower project in concrete, such as offshore oil drilling platform, long-span bridges, tunnels and so on micro-mixing silica fume can improve the anti-seepage, scour, such as anti-corrosion properties, such as the Norwegian North Sea oil drilling Platform, cross-sea bridge Stolma Norway (301m span lightweight aggregate concrete construction LC60), the Danish Great Belt Bridge, connecting Denmark and Sweden, Ele (ORESUND) Strait Bridge, the United States Kinzua dam seepage of concrete panels, into the Lock, the hole was the main structure of the lower part of the plant, and so on. Micro-silica fume concrete pavement for roads and runways, we can greatly improve the early strength of concrete and wear-resistance, the road maintenance and road repair, you can open to traffic ahead of time, increase the economic benefits, such as the European E-6 and E - Highway 18 (Sweden), London, as well as non-metallic treatment plant to deal with the high wear-resistant surface.
In Europe and the United States, 75 percent of sprayed concrete are blended with micro-silica fume, and in Norway and Sweden, micro-silica fume shotcrete is a must-have material.
1.2 for refractory additive
Japan each year through Aiken, imported from China for a large number of micro-silica fume refractories industry. Kobe Steel from Japan's Institute of fire-resistant materials research, high-quality fine silicon powder to be used as the main high-performance castable fire-resistant, prefabricated steel-included, air brick, gravity-cast materials and refractory construction materials wet and dry injection method. According to the Osaka Industrial Technology Research Institute study report, the high temperature in the field of ceramics, such as: oxide silicon carbide products, high-temperature calcium silicate-light insulating materials, electromagnetic kiln with corundum mullite push plate, wear-resistant high-temperature Materials and products, ceramic products and corundum, the game combines products, such as lung, the use of micro-silica fume with high liquidity, low storage capacity, high density and high strength and so on.
1.3 metallurgical pellets used as additives
The United States has the micro-silica fume 453.6kg per 22.7kg allocation ratio of fine silicon powder pellets made from raw materials as a smelting furnace, the largest size of the ball for 19-25mm. After smelting furnace has proved that adding a large number of pellets, the furnace is running three weeks, there is no silicon recovery was found to reduce power consumption and increase in the unit. Norway Aiken company will have 20,000 kilowatts of silicon metal furnace each day and night to produce the micro-silica fume 100m ³ of water made to reconcile the 1-5cm diameter of the pellets do not have to dry after the return of direct smelting furnace for testing, in the shaft furnace in the 800 -- 1200 ℃ sintering temperature, post-sintering pellets burst does not exist and adapted, with adequate mechanical strength, and not because of an additional binder, very few impurities in the pellet, it can return as a smelting furnace Materials. The Soviet Union used to make paper pulp waste liquid binder-ball, pellet strength can not break through Daoyun, according to the ratio of 30% of the accession to the use of electric furnace. Sweden, a ferroalloy plant for the use of micro-silica fume chromium ore pellet binder used.
Ferrosilicon smelting furnace closed generally wet flue gas purification, the use of treated water heaters gas recovery of silicon micro-smelting furnace dust mud as raw materials. Norway's Aiken had a test and study of its rotary kiln in China and Canada oxidants or reducing agent, heated to continue 800-1400 ℃ or so, such as dealing with micro-silica dust can get rid of harmful substances in soil, at the same time to form a Pellets. Pellets of hazardous substances and cyanide and asphalt-like carbon material have been removed, treated pellets can be returned to the silicon metal and silicon as a raw material in smelting.
At present, the United States, Russia, Norway and other countries have made fine silicon powder and ball-ball equipment patents.
1.4 admixture materials used in cement do
Raw materials for cement: Norway, Iceland, Canada and other countries of the ferroalloy plant to recover some of the micro-silica fume as a cement raw materials are reported. The Soviet Union pointed out that the patents in the production of Portland cement raw materials into the allocation of 18-25% silica fume, can increase the output of cement kiln cement and the quality of the kiln cement production capacity to increase 10-20% in the conservation of 28 days after the resistance By the strength of 47Pa to 54-56MPa.
To do the production of cement mixed cement: Cement Iceland will be made of micro-spherical silicon powder and clinker grinding together with the production of micro-silica fume about 6% of mixed cement, a very good effect. 1982 Lafarge France (Lafarge) cement mixed with silica fume at the micro-Portland clinker in cement production has been mixed to enter the market. Canada has also developed a mixture of cement standards, mixed cement requirements in the amount of fine silicon powder blended with less than 10%, SiO2 content of micro-silica fume in more than 85% loss on ignition <6%. Cement production of ultra-dense: The Japanese electric industry Danmaidixi off from the Corporation (DENSIT) introduced the company to "DENSIFIED" named after the ultra-dense cement. This mainly by the micro-silica fume cement, cement clinker and special additives, such as by preparing. Use it made of high density concrete, the concrete to enhance strength than 2-3 times, good corrosion resistance, insulation, wear resistance, impermeability, frost resistance and chloride ions on the block Performance, and so on. Denmark has such a cement for the anti-corrosion, wear-resistant food factories and heavy machinery plant in the ground and requirements of insulation and chloride to stop the anti-corrosion layer of hydraulic concrete projects, but also to replace some of the metal. Denmark corrosion Research Center of the Institute are in this for cement and steel anti-corrosion coating Atomic Energy Research Institute is studying the use of radioactive waste for the protection of the isolation material.
1.5 The spread of chemical products used as a release agent
In order to prevent some of the chemical synthesis of powder agglomeration, has been used for coated mica processing, the higher the cost. Application of micro-silica fume can replace more expensive to deal with the material, but to accurately grasp proportional use. Norway, France and Italy are using this method, so that the dispersion agent of the application well. This dispersion agent widely used in fine chemicals, chemical fertilizer, fire-fighting applications, such as the United States Borax, Scotland METHIL DOCKS fertilizer.
Other 1.6
Some foreign manufacturers of silicon metal alloys have a large number of micro-silica fume ongoing research to find more uses. For example, Russia has developed the use of micro-silica fume silicate brick raw materials for the process method of trial and the allocation of 5% of micro-silica fume silicate brick by brick hardness, strength resistance, water absorption equal to brand M200 Blocks, such as micro-silica fume will be allocated to increase the amount increased to 7%, to brand the brick M250-300, The pilot of the bricks are in line with other indicators of the Russian standards require Russia to use micro-silica fume-filled polymer resins and other Polymer products, alternative white carbon black, talc, asbestos, aerosols, such as filling material can be reduced to improve extension, tear and the degree of anti-aging properties of micro-silica fume can also be used in agricultural fertilizer and soil types, such as micro-silica fume Potassium hydroxide and potassium carbonate, or mixed-heating can be made from agricultural relief Potassium fertilizer, it is not easy evaporation loss, to protect the soil and promote root development of crop, inhibited plant diseases and insect pests, as well as micro-and silica fume or wood cellulose plant factory Waste-processing wastes such as bark, after the formation of mixed material, can enhance soil fertility.
2 micro-silica fume in China
2.1 micro-silica fume in our production and application of the status quo
China's micro-silica fume applied research and recycling late start, most of ferrosilicon production of micro-enterprises not pay enough attention to the recovery of silica fume, a number of large-scale enterprises, despite the recovery of micro-silica fume, but did not find the value of the And to the recovery of these micro-silica fume content standards are not the majority, is the extensive industrial by-products. In recent years, due to the country has attached to environmental protection and gradually stepped up the pollution management, in particular, domestic demand for high-strength concrete, a number of ferroalloy production enterprises with collecting equipment, and development, the introduction of encryption technology. China's development of micro-silica fume products quickly and in the field of foreign and the gap is narrowing. High-strength concrete, sprayed concrete micro-silica fume, to enhance the density of composite agent, silica fume mortar and low cement castable, and other scientific research have been adopted by the ministerial or provincial, municipal identification technology and has many applications in engineering, technical and economic Results are obvious. Some applications have been close to reaching or abroad in the early 1980s.
At present, most industrial silicon production plants every three tons of recyclable industry a ton of high-quality silicon micro-silica fume. Every five tons of ferrosilicon production of one ton of recyclable micro-silica fume. According to incomplete statistics, China's 2004 output of micro-silica fume reach more than 120,000 tons, most of them with SiO2 90% below grade.
China's micro-silica fume is the main use in the field of refractories and concrete. Micro-silica fume concrete has been used in major projects such as the construction of high-rise buildings, anti-erosion wear, such as anti-seepage project, as early as 1986, China's silicon has been used in mortar to repair the gates and Gezhouba 2000-3000m3 reservoir of anti-seepage, the Three Gorges Power station, the Ertan power plant, power station Project, the Yellow River Xiaolangdi Hydropower Station in Fujian power outlet, Longyangxia power station in Qinghai, and other water conservancy and hydropower project and the Yangpu Bridge in Shanghai, Hong Kong's Tsing Ma bridge spanning the sea, Lianyungang in Jiangsu timber terminal projects, such as the anti - And scour the site, as well as for high-intensity projects, such as the impermeability of the Shanghai Huangpu River Tunnel Project river micro-silica fume concrete is also used anti-sulfate, perchlorate, rust-proof steel and improve the durability of the project, such as in China's coastal construction The underwater oil production platform, such as micro-silica fume concrete for highway and rail, such as national key project of the Qinghai-Tibet railway construction projects have used more micro-silica fume products.
Micro-silica fume in the refractory material used in the main part of the amorphous. China's Ministry of Metallurgical Research Institute of construction since the beginning of 1985 conduct a low cement castable, 1988, through ministerial-level identification. It has been Baosteel, Shougang thermal devices, and some material has been made to replace the materials imported from Japan. Low cement castable and the general casting material used calcium aluminate cement, silica fume and the detailed allocation of superplasticizer, a low cement castable can not only save high cement 50-70%, but performance also improved. Castable cement has been used for many projects, such as Baoshan Iron and Steel blast furnace for iron covered ditch in place of the original casting material imported from Japan, a large number of foreign exchange savings for reheating furnace Shougang 250 and 430 on the brick furnace burning Tsui for Shougang 500 Blooming furnace gas flow scouring the site for serious wear and tear of the Nanjing Chemical Industry Company Institute's gas furnace lining, the service life of 68 days, corundum than the original pipe to increase the service life of 10-20 times. In recent years, a number of research institutions, product development organizations to promote, micro-silica fume in the project has been gradually plate, wear-resistant floor, paint, mortar functional areas such as access to the application.
In addition, the micro-silica fume in other fields also, such as the Shanghai Chemical Spark has been fine silicon powder used in the production of sodium silicate, can simplify the process, produce a module of the water glass is greater than 4. Module 4 over for the neutral water glass can be widely used in high-temperature paint, steel, and so on. Shanghai Baosteel has been in use for this kind of water glass.
2.2 micro-silica fume the price of the status quo
Micro-current market price per ton of silica fume for the 1800 to 3800 yuan, according to the micro-silica fume in SiO2 content, use of different micro-silica fume on the market prices vary, but generally, if not size, such as loss on ignition Factor, SiO2 content of the higher content of impurities in the lower, the higher the price. With the market's increasing demand for micro-silica fume, and higher prices. Table 1 - 3 of the international and domestic market prices of micro-silica fume.
Table 1 port on the international market some of the CIF market price
The main port of export packaging specifications parameters reference price (dollars / tonne) Remarks
85% of 800 kg / bag Tokyo
Incheon
Melbourne
Dubai
Karachi
Seattle 250-260
242-252
316-326
395-405
270-280
301-310 encryption
Encryption
Encryption
Encryption
Encryption
Encryption
90% of 800 kg / bag Tokyo
Incheon
Melbourne
Dubai
Karachi
Seattle 270-280
292-302
336-346
320-330
290-300
321-331 encryption
Encryption
Encryption
Encryption
Encryption
Encryption
Table 2 micro-silica fume part of the Chinese port FOB prices
The main port of export packaging specifications parameters reference price (dollars / tonne) Remarks
85% of 800 kg / bag Dalian
Qingdao
Newport
Shanghai
Huang Po
Zhanjiang 220-230
210-220
220-230
225-235
230
220-230 encryption
Encryption
Encryption
Encryption
Encryption
Encryption
90% of 800 kg / bag Dalian
Qingdao
Newport
Shanghai
Huang Po
Zhanjiang 250-260
240-250
240-250
250-260
240-250
240 encryption
Encryption
Encryption
Encryption
Encryption
Encryption
Table 3 micro-silica fume market prices in some regions of China
The main parameters of packaging specifications origin reference price of RMB
(Yuan / ton) Remarks
85% of 800 kg / bag in Inner Mongolia
Gansu
Ningxia
Guizhou 1500-1650 yuan / ton
1600-1700 yuan / ton
1500-1650 yuan / ton
1550-1700 yuan / ton encryption
Encryption
Encryption
Encryption
90% of 800 kg / bag in Inner Mongolia
Gansu
Ningxia
Guizhou 1800-1900 yuan / ton
1700-1850 yuan / ton
1700-1850 yuan / ton
1700-1900 yuan / ton encryption
Encryption
Encryption
Encryption
3 micro-silica fume market demand forecast
3.1 foreign market demand for micro-silica fume
At present, the international market demand for micro-silica fume increases every year, the principal foreign micro-silica fume-producing countries such as the United States, Russia, Japan, Norway, and other micro-silica fume than the total output of 640,000 tons / year, it can not meet the needs of the market. As the Chinese ferrosilicon and silicon metal in the international community's prominent position in production (in 2006 world production of about 2 / 3), associated with the micro-silica fume by foreign customers of great importance to end, foreign businessmen in China have silicon micro-purchases Powder, such as Norway, Aiken, not only gradually monopolize the investment of resources, and research and development center has moved to China, Northwest China every year to iron alloy, and so most of the domestic ferroalloy manufacturers of micro-silica fume at a low price to buy a large number of domestic processing China and then sold at high prices on the international market for construction, cement, fertilizer and other areas, micro-silica fume-year sales amounted to 250,000 tons, the profits of money. Data from the understanding of micro-silica fume is a huge market for foreign, high-quality micro-silica fume wide range of applications, but high-quality production of micro-silica fume few. According to the company and the Aiken (China) director of the Center for Research on the understanding of the discussion, the company has been in Norway the use of low-cost hydropower in the high-temperature electric arc furnace with specialized direct the production of high purity silica micro-silica fume (gas is actually white carbon black), the micro - Silica fume as much as the price of 5000 U.S. dollars / ton.
3.2 Domestic market demand for micro-silica fume
At present, high-rise buildings, railways, bridges, water and construction of micro-silica fume rapid growth in the demand market has great potential. Concrete is the basic construction materials, micro-silica fume so that the addition of high-intensity, high-performance concrete possible, although not a single high-performance concrete mixing refers to the micro-silica fume, and other filling materials such as fly ash, blast furnace slag, and so be able to raise The performance of concrete, but the micro-mixing of the silica fume concrete improvement in comprehensive even better performance, add micro-silica fume after mixing cement capacity will be significantly reduced.
China is the world's largest consumer of refractory materials, micro-silica fume in the refractory of applied technology is relatively mature, and refractories from China's development trend, due to the "11th Five-Year Plan" period, metallurgy, building materials industry will maintain steady development, Refractory demand remains high and will continue to maintain a rapid growth trend. Can be used to the level of high-grade cement pouring fire-resistant materials and prefabricated parts, large-scale iron and steel groove-included, air brick, the material applied to repair, gravity-casting fire-resistant materials and construction of wet and dry application of law injection, combined with oxides of silicon carbide products (ceramics kiln kiln , Every other board flame, and so on), high-temperature calcium silicate-light insulating materials, electric kiln with corundum mullite push plate, wear-resistant high-temperature materials and products, ceramic products and corundum, the game combines products, such as lung, in the micro-silica fume Refractory Application have broad market space. In addition, the micro-silica fume can substitute for fumed silica in rubber, plastics, paint, pesticides, high-performance ceramics, composite in areas such as the use of chemical fertilizers.
At present, domestic market demand for micro-silica fume in the 28-35 million tons / year or so (Tiankai through the network of special materials, ferroalloy China Network, China Concrete Network, China Industrial Information Network powder and a telephone survey), but the domestic micro-silica fume Only a few enterprises, micro-silica fume initial projections for the total output of 18-20 million tons / year (based on 2004 output of iron alloy of silicon statistical data analysis) around, not far from meeting the needs of the market. With the further development of economic construction, across the water and electricity, water and road transport infrastructure, a large number of starts, combined with micro-silica fume applied research and investment further increase the strength of micro-silica fume the market prospects are very impressive.
