Method for removing impurity iron in industrial silicon

Abstract

The invention relates to a method for removing impurity iron in industrial silicon, and belongs to the technical field of industrial silicon smelting. The method comprises: continuously adding industrial silicon melt into a directional solidification continuous casting device at a constant speed, carrying out segregation and enrichment of impurity iron under control of the temperature, flow speedand solidification speed of the silicon melt, so that a silicon ingot product with the iron content distributed in a gradient mode is obtained, sampling and detecting the silicon ingot product, determining nodes of gradient distribution of Fe content, and grading the silicon ingot to obtain industrial silicon products of different levels with different iron mass contents, wherein the total mass ofthe industrial silicon product is 100%, the micro-iron industrial silicon product is not lower than 60%, the low-iron industrial silicon product is not lower than 22%, the medium-iron industrial silicon product is not higher than 10%, and the high-iron industrial silicon product is not higher than 8%. The method is combined with existing industrial silicon smelting and external refining processes, silicon melt is directly subjected to efficient iron removal, the grade of industrial silicon products can be increased by 2-3 grades, and the method has the advantages of being low in production cost, wide in technical adaptability, wide in application prospect and the like.

Description

technical field [0001] The invention relates to a method for removing impurity iron in industrial silicon, belonging to the technical field of industrial silicon smelting. Background technique [0002] The production capacity and output of industrial silicon (silicon metal) in my country are more than 2 / 3 of the world's. In order to improve the quality of industrial silicon products, domestic and foreign industrial silicon production enterprises mostly use the technology of oxidation and refining outside the furnace to remove impurities, especially crude silicon. Impurities such as Al and Ca in silicon products can be better removed. However, the limitation of this technology is that it cannot effectively separate Fe, the main metal impurity in industrial silicon products, which leads to Fe impurities becoming a key impurity element that directly affects industrial silicon grades. The general method adopted to solve this problem is mainly by controlling production raw materia...

AI Technical Summary

Problems solved by technology

The present invention aims at the removal of impurity Fe in the existing industrial silicon purification technology, and provides a method for removing impurity iron in industrial silicon. The present invention is based on the existing industrial silicon production process, and the advantages of controllable solidification segregation and impurity removal of comprehensive directional solidification technology With the characteristics of low cost and continuous production of continuous casting technology, through the continuous controllable melt cooling rate and controllable ingot casting rate, the segregation and enrichment position of impurity Fe in silicon melt is controlled, so that the segregation and enrichment of impurity Fe is strengthened into the uncrystallized tail melt, thereby reducing the Fe content in the industrial silicon products that solidify first, and achieving the production target of low-Fe high-quality industrial silicon products

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