Production of metallurgical silicon plant Silicium Kazakhstan Bashny.Net

With fotopomoschyu blogger victorprofessor we will visit the plant Silicium Kazakhstan, which produces silicon metal carbothermic process using a special ore-thermal furnaces. This is one of the largest factories in the country and the only silicon plant in Kazakhstan. The plant was launched in autumn 2010.

Prevalence in the crust silicon is second only to oxygen, occurs mainly in the form of oxygen compounds (quartz, silicates, etc.). High-purity silicon used in semiconductor technology, and technical grade (96-99% Si) - in ferrous and nonferrous metallurgy for non-ferrous alloys on the basis of (silumina et al.), Doping (silicon steels and alloys used in electrical equipment) and deoxidation Steel and Alloys (removal of oxygen), the production of silicides etc.

In the production process at the plant two kinds of products:
 - Metal silicon (having a purity of not less than 98, 5% aluminum, and used in the chemical industry)
 - Silicon dust (ultrafine material obtained in the process of gas purification furnaces, it is used in the production of extra strong dry construction mixtures)




In the industry of technical purity silicon is obtained by restoring melt SiO2 coke at a temperature of about 1800 degrees Celsius in the ore-smelting shaft furnaces. The purity of the thus obtained silicon can reach 99% 9 (major impurity - carbon and metals).



The basic unit of silicon smelting ore-thermal arc is one-three-phase electric power from 8 to 25 MVA. The oven is a round steel case with a bottom, lined with refractory brickwork. Hearth (bottom) and the height of the walls are lined with graphite blocks, the next layer of magnesite bricks and an outer layer - chamotte (porous brick made of special refractory clay).



Power supply to the working space of the furnace is carried out using an electrode made of graphite. Self-baking electrodes in silicon technology are not applicable due to possible contamination of the product components of the casing electrode and electrode mass (iron, calcium, aluminum). Electrical parameters of the recovery process mediated by the furnace transformer connected to the electrode short high current network, in which the current is 40-80 kA. As the consumption of the electrode socket are periodically lengthens via bypass mechanisms. Adjusting predetermined current in the electrode is accomplished by perescheniya electrode on the vertical axis.



Release of silicon is carried out almost continuously through Ledkov (hole in the lining) in a steel-lined mold.



In the bypass arc furnace is a restoration of silicon from silica quartzite carbon reductant. Theoretical beginning of the process temperature 1670 degrees Celsius. The main types of reducing agents include charcoal (birch, pine), petcoke and coal.



Of the ore-thermal furnace, molten quartz falls into the bucket from which it is poured into molds.



The plant currently operates one furnace, in the near future will be put second, and then the production capacity of 30 thousand. Tons of silicon metal per year. In addition, the products will continue to be supplied to the polysilicon plant: its construction in Omsk starts this year. Now the finished products are exported to the EU.



By the way, the market price of silicon metal - 2500 euros per tonne.



Plant potrebyaet huge amount of energy to maintain the temperature in the furnace. Production runs around the clock. A first run of the furnace to its heating to the working temperature required about two weeks.



At the plant as a raw material for the production of silicon metal used vein quartz from Ulytautskogo area.



In the forms of silicon metal cools and solidifies.



Silicon metal is the basis for high-tech industry. Silicon - that solar cells, semiconductors and computers, and much, much more.



By the way, the production of silicon metal completely without waste. Above the furnace ducts are, and all the dust goes into the gas cleaning, where the trapped microparticles. This silicon dust is a useful product in another part of the production. For example, previously melted quartz in Europe only to it, and then add to grind the concrete, in solutions which have a very high restorative properties. The quartz crystal lattice is very strong. And the 900-th grade of concrete can be obtained only by means of silicon. And then there are waterproofing seal, shock-resistant floors, these products are used to strengthen the subway tunnels.



After ostavanie silicon crushed into small pieces hydraulic hammer.



Then the finished products are packed in big bags - plastic bags, which can accommodate 1,000 pounds of silicon metal and sent to customers.



What can be done with a commercial silicon? Process chain in the production of silicon continues: metallurgical silicon - polysilicon - monocrystalline silicon - silicon wafers. For further purification, metallurgical silicon is distilled, turning to environmentally harmful chlorine compounds: dichlorosilane or trichlorosilane. After cleaning, the latter in large distillation columns and polysilicon deposition processes is obtained, where the concentration of impurities does not exceed ten-thousandth of a percent. Thereafter, it is melted into the single crystal material, and single crystals are cut on the plate. The obtained 80% of monocrystalline silicon used in electronics.