Metallurgical silicon

The Rochow Process refers to the synthesis of liquid methylcWorosilanes from metallurgical silicon powder and gaseous methyl cWoride ... 

For the solar industry, impurity control and alternative raw materials are of great interest. In the normal metallurgical silicon production furnace, silica is charged into the form of quartz lumps. The carbonaceous materials have many forms like charcoal coke, coal, and wood chips. The charge is carefully composed and the raw materials are selected to give best possible yield with respect to Si and to avoid unwanted impurities. Also, the refractory materials and the consumable electrodes are source of impurities. The Si from the arc... 

G.M. Haarberg et al. Electrorefining of metallurgical silicon in molten chloride and fluoride electrolytes, in the 3rd International Workshop on Science and Technology of Crystalline Si Solar Cells, (Trondheim, Norway 2009)... 

Aside from experimental and developing processes, there are three competing commercial processes for further refining metallurgical silicon into semiconductor grade polycrystalline silicon (polysilicon) Siemens, Union Carbide Chemicals, and Ethyl Corporation methods. This industry exists primarily to support the electronics industry. 

The aluminum market is still the largest market for metallurgical silicon. In 2000, consumption reached 573 000 Mt, whereas the chemical market accounted for 401 000 Mt and the electronics market for 42 000 Mt (Fig.l). The largest geographical markets are the EU (355 000 Mt), Japan (187 000 Mt) and the USA (290 000 Mt). The supply side is characterized by a few big suppliers (Elkem, Invensil) and many small ones (China, US, Brazil etc.). Norway, China, Brazil, and the USA are the four countries with the highest silicon production. 

Most elements can easily be alloyed to liquid silicon, through silicothermic reduction of oxides or by adding pure metals. In this way a variety of special requirements can be fulfilled. Metallurgical silicon is now supplied in a wide range of qualities. Almost every MCS or TCS process operator has his own specification, whereas the aluminum market is supplied with a range of standard specifications. 

The process waste from metallurgical silicon has been discussed previously. In the following chemical processes also, additional byproducts and wastes are generated. This was more recently discussed by Freebume [15] and Rich [16]. Currently such materials are treated and recovered in... 

Raw materials for the metallurgical silicon production are abundantly available. 

Fig. 2 Silicon incorporation of foodstuffs for taste and mouthfeel trials chocolate and chewing gum. Milk chocolate impregnated with mieronized metallurgical silicon using an industrial process. The two darker brown slabs, with a hue similar to dark chocolate, contained 12 wt% silicon. Chewing gum pellets blended with 10 wt% siUca and 10 wt% silicon...

Dichlorosilane is most commonly produced by the disproportionation of trichlorosilane in a catalytic redistribution reactor. The trichlorosilane is initially produced from metallurgical silicon that is reacted with hydrogen and silicon tetrachloride. 

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