Study On The Purification Of Industrial Silicon Powder

Microsilica is a by-product obtained in the manufacturing process of Silicon alloy and collected from the electric arc furnace flue dust collector through with a high content of amorphous fine spherical silica particles. Microsilica has a high specific surface area, can be used as an active material with a wide range of applications. Currently, the method for purification of microsilica is calcination in a fixed-bed to get rid of carbon and iron in hydrochloric acid. These methods are serious waste of energy, and the excessive acid can cause environmental pollution. This paper studied current microsilica purification problems, in addition to carbon innovation fluidized bed calcination and oxalic acid purification process in addition to iron, and obtain the best reaction conditions, so that the efficiency recycling of waste microsilica greatly enhanced.The chemical composition, the physical and chemical properties, the use of the current situation and prospects of microsilica were introduced in this paper. The development and current status of industrial silica impurity purification technology were described in detail. By studying the development of oxygen-rich atmosphere circulating fluidized bed calcination and oxalic acid in addition to iron-carbon technologies to explore the idea of effective and efficient method of silica impurity. Many conclusions were gotten as follows:1. Circulation fluidized bed calcination process with oxygen-rich atmosphere, which can be effectively oxidized carbon particles, by improving the whiteness of silica fume. The study found that the conditions of calcination temperature900℃, calcination time3h, the oxygen concentration of32%by volume is the most suitable calcination process.2. Pickling method for purifying silica has some viability, oxalic acid can effectively remove the iron oxide sample, the optimum conditions are:oxalic acid concentration of30g/L; liquid to solid ratio8g/ml; reaction temperature was80℃; reaction time was2h. In addition to iron is feasible.We have a deeper understanding of the calcination carbon removal, pickling addition reaction mechanism of iron by the experiment; comparing the impact of various physical and chemical parameters, optimized the structure of the oxygen-rich atmosphere and fluidized bed calcination and pickling conditions,and provided a reliable basis for the next industrial data in the test and provide a theoretical basis for industrial mall reactor design.