A method for efficiently recovering silicon metal in silicon slag

Abstract

The invention discloses a method for efficiently recovering silicon metal in silicon slag, which specifically comprises: crushing and sieving raw silicon slag, and then adding a sodium hydroxide solution with a molar concentration of 18-20 mol / L of 5-10% by mass of the silicon slag, Stir evenly, and stand at a temperature of 30~50°C for 48~72h to obtain material a; add a slagging agent 0.5~1.5 times the mass of material a to material a, stir evenly to obtain material b; put material b at 15~30°C / The heating rate of min is evenly raised to 1550~1750℃, and the temperature is kept for 1~2h until the silicon slag is completely separated from the metal silicon. The metal silicon floats on the top due to its good fluidity and small specific gravity. After the silicon and the silicon slag are separated, the silicon melt is passed through Casting obtains silicon metal with a purity of more than 99.2%. The present invention fundamentally solves the problem of silicon slag recovery, increases the recycling rate of silicon metal in silicon slag to more than 85%, and the silicon content in recovered silicon metal reaches more than 99.2%, and the Fe content in silicon metal is lower than 0.7%, the Al content is less than 0.08%, and the Ca content is less than 0.01%. It has laid a solid foundation for the recovery of silicon slag and the purification of silicon metal.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for efficiently recovering silicon metal in silicon slag. Background technique [0002] Silicon slag generally refers to the remaining part after the ore is refined, and it also contains a certain amount of silicon. There are many kinds of silicon slag, industrial silicon slag, solar silicon slag, semiconductor silicon slag and so on. Silicon slag can be used to return to the furnace for recrystallization and purification. Now silicon materials are in short supply and expensive. After re-election, silicon slag contains more than 65% silicon, but because the slag and silicon metal have not been completely separated, the concentrate still contains some silicon slag after re-election, and Al, Ca, Ti, P and other impurity elements are relatively high. It is of great significance to recycle silicon slag under the premise of quality, reduce cost and increase e...

AI Technical Summary

Problems solved by technology

After re-election, silicon slag contains more than 65% silicon, but because the slag and silicon metal have not been completely separated, the concentrate still contains some silicon slag after re-election, and Al, Ca, Ti, P and other impurity elements are relatively high. It is of great significance to recycle silicon slag under the premise of quality, reduce cost and increase efficiency, and enter the sustainable development of the cycle