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First, the main applications of silicon powder
1, applies to the concrete industry
Silica fume admixture as the agent for the concrete industry is the comprehensive utilization of foreign silica fume in the first study, results of the largest, most widely used in the field of a. As the small particles of silica fume, area, Sio2 with high purity and strong volcanic ash activity, such as physical and chemical characteristics of the silica fume as a blending agent in the concrete were added to improve the performance of various concrete.
(1) to improve the early strength of concrete and the ultimate strength
Study abroad has proved that when the silica fume concrete for the replacement of 30%, the steam curing temperature of 80 ℃, a one-day compressive strength of mortar is not for the silica fume 2 times (100MPa), the use of a conservation autoclave, Almost 3 times (150MPa); standard conservation, and the compressive strength of mortar also improved. Canada H. H. Bache suggested that when the silica fume and high-performance alkaline compound used agent, make concrete and plastic water (W / C + Si) fell to 0.13-0.18, cement between the particles was filled with dense fume, concrete Not for the strength of silica fume 3-5 times. Currently, the United States, Denmark, Norway and other countries for their own use silica fume admixture preparation agent 1100kg/cm2 up to a strength of the concrete, and simple technology, good economic returns, it has been used a lot.
(2) increase in the density
The introduction of silica fume concrete response from the increase of silicon content, electron microscopy, silica fume concrete cement the gap in the growth of crystals. In addition, very small particles of silicon powder, evenly filled with porous concrete. Foreign cement injection were determined, no matter what kind of conservation, silica fume cement concrete pore volume were significantly reduced.
(3) to improve the isolation of concrete and sand properties of water
Concrete water, the water produced is often separated from the concrete phenomenon, that is, in the form of surface water, also known as the floating pulp, so that the uneven distribution of the upper concrete, the impact on the quality of construction. Study abroad shows that the amount of silicon powder that is blended with the replacement of Si / (Si + C) more concrete material, the more difficult to disintegrate and bleeding. When the replacement of 15%, concrete slump, even if up to 15-20cm almost no bleeding and segregation. When replace the rate of 20-30%, the concrete directly to the release of water is also not easy to produce isolation. As the silica fume concrete on the segregation of water and sand to improve the performance so that the silica fume concrete can be put to use ports, such as underwater tunnel project.
(4) to improve the impermeability of concrete, anti-corrosive and chemical resistance
The introduction of silica fume as a result of increased density of concrete, cement significantly reduces the gap, so to improve the impermeability of the silica fume concrete. Study abroad diagnosis, when the silica fume concrete for the replacement of 10-20%, a significant improvement in the impermeability of concrete, anti-corrosive chemicals, but also reinforced the corrosion resistance is also improved. This is because of the dense and improve the content of SiO2, effectively blocking the acid ion and the corrosive effect of the invasion. In addition, due to resistance than the high silica fume (up to 1.2X10 ¹ ¹ Ω. Cm ,90-150 ℃), so the concrete can increase resistance than the 1.9-1.6 times.
As the silica fume concrete with the above-mentioned advantages, so abroad silica fume, as a new material has been widely used and carried out extensive and in-depth research for the development of silicon powder used in national or international norms laid the foundation. The United States, Canada, Norway and other countries on the use of silica fume established norms (standards), see table.
2, for the return of charge
The United States has made to the form of pellets as a raw material smelting furnace, pellet feed the ratio of allocation of 22.7kg per 453.6kg silica fume, made of pellets. The ball size of the largest 19-25mm. Dry ball too hard, plus people in electric easy broken, the impact of smelting; the ball is too small, the expected level of bad ventilation, but also affect the status of the furnace. Pellets in water up to 20%, the density of 0.83-0.92, for the dry-bulb (0.72-0.75) X10 ³ kg/m3, in the air after a dry day and night, the pellets can be given adequate machinery Intensity. After smelting furnace has proved that adding a large number of pellets, the furnace is running three weeks, there is no silicon recovery rate was found to reduce power consumption and increase in the unit. Norway Aiken company will have 20,000 kw silicon metal furnace each day and night to produce the rate of 100m ³ of pellets made of silica fume and returned to smelting furnace for trial. Non-doped binder, the water made to reconcile the 1-5cm diameter of the pellet in the shaft furnace 800-1200 ℃ in temperature sintering, the sintering pellets have sufficient mechanical strength. Accession to the ball before the shaft furnace do not have to dry after sintering pellets burst does not exist and adapted. Moreover, due to the non-plus binder, very few impurities in the pellet, it can return as a smelting furnace materials.
Ferrosilicon smelting furnace closed generally wet flue gas purification, the use of treated water heaters gas recovery of silica dust and mud as a smelting furnace of raw materials, Norway Aiken's test and research, will be in the kiln dust in the mud Canada oxidants or reducing agent, heated to continue 800-1400 ℃ or so, this can be dealt with to remove the sludge Silica dust in the level of harmful substances at the same time to form 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 are made of silicon powder and ball patent-ball equipment.
3, used in cement industry
This is similar to add concrete materials, is currently developing a number of countries in this area, the development of a variety of mixed cement, the quality is better than ordinary cement.
4, as anti-caking agent
In order to prevent the agglomeration of fertilizer, commonly used mica or diatomaceous earth for special treatment, the higher the cost. Application of silica fume can replace more expensive to deal with the material, but to accurately grasp the use of living ratio. Norway, France and Italy are using this method, anti-caking agent to make the application well.
5, the raw material for silicate brick
Russia has developed the use of silica fume silicate brick raw materials for the process method of trial and the allocation of 5% of the silica fume silicate brick. The pilot of the brick indicators are in line with national standards. According to the hardness of brick, cold intensity, the equivalent of water-absorbing tiles brand M200. Will be equipped with Canadian such as silica fume increased 7%, the brand of brick to No. M250-300. Using silica fume silicate brick manufacturing has reduced the consumption of lime and reduces the cost of bricks.
6, for other purposes
Some foreign manufacturers of silicon alloy smelting silica dust generated by a large number of ongoing research to find a reliable market, in addition to the above found that the use of valuable, also found that dust that can be used in the production of refractory materials for Insulation material, anti-sintering agent. For example, the Russian use of silica dust making resins and other polymer-based organic polymer products, and as a black, white carbon black, talc, asbestos, air-solvent such as a substitute for, as a material to add. In addition, silica fume can also be used to improve soil. For example, silica fume and wood cellulose plant or plant waste, such as bark waste after processing the formation of the mixed material, can enhance soil fertility.
Second, domestic market demand, micro-silica fume
At present, domestic market demand for micro-silica fume at 100,000 tons / year or so, but made only a few micro-silica fume production, micro-silica fume production for a total of 45,000 tons / year or so. At present, a number of key projects, such as the power station dam diversion tunnel, advanced ceramic refractory materials, highway construction and so on the durability of demand for a large number of micro-silica fume products, micro-silica fume was also applied to the industry and special refractory cement industry. With the further development of economic construction, across the water and electricity, water and road transport infrastructure, a large number of starts, combined with the micro-silica fume should be further in-depth study of micro-silica fume the market prospects are very impressive.
Third, foreign market demand for micro-silica fume
From that information, micro-silica fume is a huge market for foreign, high-quality micro-silica fume wide range of applications. The main foreign micro-silica fume-producing countries to the United States, Russia, Japan, Norway. The United States with an annual output of 300,000 tons micro-silica fume; Russia with an annual output of 150,000 tons micro-silica fume: Japan with an annual output of 70,000 tons micro-silica fume; Norway with an annual output of 120,000 tons micro-silica fume. Far from enough to meet the needs of the market.
Domestic micro-high-purity silicon powder of the main areas of application:
l, anti-corrosion marine structure construction special 30%
2, high-refractory industry 30%
3, roads, bridges and special cement 30%
4, chemicals, electronic 5%
5, the other 5% |
