PRODUCTION OF FERROALLOYS, CALCIUM CARBIDE, AND PHOSPHORUS FROM HIGH-SILICON PHOSPHORITE

Abstract

The article provides information on the interaction of Chilisai phosphorite with carbon, coke, and iron with the production of ferroalloy and calcium carbide and the extraction of phosphorus into gas. Research is conducted using computer thermodynamic modeling, mathematical planning of experiments, and electric smelting of phosphorites in an arc electric furnace. It is found that under equilibrium conditions the interaction occurs with the formation of iron silicides, calcium, silicon carbides, calcium, elemental silicon, aluminum, calcium, silicon oxide (ІІ), gaseous phosphorus (P4, P2), and iron phosphides. An increase in the amount of iron at 1,500-2,000oC increases the degree of extraction of silicon in the alloy but decreases the extraction of calcium in the calcium carbide, the concentration of silicon in the alloy, and the amount of calcium carbide. In the temperature range of 1,900-2,000oC in the presence of 16.8-19.8% of iron, phosphorus completely converts to gas, and there forms an alloy with 45-47.8% of Si and 1.6- 1.9% of Al and calcium carbide in the amount of 150-215 dm3 /kg (with the extraction of 60-63.6% of Si into the alloy and 50-56.4% of Ca into calcium carbide). Electric smelting of phosphorite in an arc furnace produces ferrosilicon of grade FS45 (40-44.7% of Si) with the extraction of 73.8% of silicone into it, as well as calcium carbide up to the second grade in the amount of 200-252 dm3 /kg. Phosphorus is almost completely (99.0-99.4%) reduced during electric smelting and converted into the gas phase.