Production technology for metallurgical silicon with low boron content and low phosphorus content

Abstract

The invention relates to a production technology for metallurgical silicon with low boron (B) content and low phosphorus (P) content. The technical scheme comprises the following steps of: selecting silica with silicon dioxide (SiO2) of over 99 percent, B of less than 10ppmw and P of less than 5ppmw and cracking the silica until the particle size of the silica ranges from 50 to 120 millimeters; cleaning the silica by using water and drying the cleaned silica in the air as raw silicon; selecting petroleum coke as a reducing agent; uniformly mixing the following compound additives in percentage by weight: 60 to 65 percent of CaF, 22 to 26 percent of CaO and 7 to 11 percent of Na2SiO3; weighing according to the weight ratio of the compound additives to the reducing agent to the silica of 1 to 4 to 10 respectively and mixing the compound additives, the reducing agent and the silica, feeding the mixture into an ore furnace and smelting at temperature of 2,000 to 2,400 DEG C for 4 to 5.5 hours, stopping heating for every 1.5 to 2 hours and ramming the furnace for three times; simultaneously discharging non-silicon substances and smelted metallurgical silicon liquid in the ore furnace, injecting the non-silicon substances and the smelted metallurgical silicon liquid into a silicon water bag and performing oxygen blowing to slowly increase air pressure until the liquid silicon mixtureis in a boiling state and keeping the boiling state for 35 to 50 minutes; and removing slag and directionally solidifying to obtain the high-quality metallurgical silicon.

Description

technical field [0001] The invention relates to the technical field of metallurgical silicon production, in particular to a production process of low-boron and low-phosphorus metallurgical silicon. Background technique [0002] Metallurgical silicon has a wide range of uses, mainly for the production of organic silicon, the preparation of high-purity semiconductor materials, solar cell materials, and the preparation of alloys for special purposes, etc. [0003] At present, metallurgical silicon products are all prepared by smelting production methods, that is, the natural mineral silica is crushed, mixed with carbonaceous reducing agents such as charcoal, bituminous coal, and petroleum coke, and sent to submerged arc furnaces for smelting according to a certain ratio: the smelting chemical equation for SiO 2 +C=Si+CO 2 ↑, the silica is reduced to silicon, which is regularly released from the furnace, and after refining outside the furnace, metallurgical silicon products ar...

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to address the deficiencies in the current production of high-quality metallurgical silicon

Provide a method of producing metallurgical silicon by using all-petroleum coke as a reducing agent and compound additives, which solves the technical problems of high impurity content in metallurgical silicon and rising furnace bottom, and can smelt high-quality metallurgical silicon