Silicon-carbon treatment out of inorganic impurities produced from the rice husk

Abstract

The process of silicon-carbon produced out of the rice husk treatment with HCl solution has been investigated and elaborated to purify from aluminum and phosphorous to their contents were less than 0.1 % each. Silicon-carbon with such contents of these impurities meets the requirements to as the multifunctional material for its application in various branches of industry and agriculture. It was demonstrated that the required content of aluminum and phosphorus in silicon-carbon can be achieved by two ways. Namely, by silicon-carbon production out of the pre-treated rice husk or by purification of silica-carbon obtained out of untreated rice husk. Considering the output of silicon-carbon out of rice husk equals to 33 %, it is more reasonable to submit the minor material mass to the acid treatment that is the silicon-carbon. The silicon-carbon treatment produced out of untreated rice husk (52.3 % С, 35.9 % SiO2, 0.2 % Al and 0.12 % P) was carried out with 0.5 – 3 % hydrochloric acid solutions at the temperature of 70-80 °С. As a result of laboratory studies and pilot testing, the processing method hydrochemical treatment of silicon-carbon was elaborated. The following optimal processing parameters were recommended: hydrochloric acid concentration in aqueous solution – 1 %, 75-80 °С, and treatment time is 60 minutes. The aluminum content was at the level of 0.085 %, and phosphorus was 0.04 % in the processed silicon-carbon. The obtained silicon-carbon with low level of inorganic elements can be applied as the charging material for smelting low-aluminum ferrosilicon and pure silicon, as the filler of carbon construction materials and elastomers.