阅读说明：本技术 一种利用硅铁合金制备工业硅的方法 (Method for preparing industrial silicon by using ferrosilicon ) 是由 马文会 邓小聪 魏奎先 雷云 于 2020-07-13 设计创作，主要内容包括：本发明涉及一种利用硅铁合金制备工业硅的方法,属于工业硅冶炼技术领域。本发明将硅铁合金熔体连续匀速加入到定向凝固连铸装置中,控制硅铁合金熔体的温度和流速、凝固速度以实现金属铁的偏析富集,得到铁含量梯级分布的硅锭产品,对硅锭产品进行取样检测,确定Fe含量梯级分布的节点,并对硅锭进行分级处理得到不同铁质量含量的各级工业硅产品,工业硅产品包括化学级工业硅、冶金级工业硅和硅铁合金。本发明方法将硅铁合金熔体直接进行高效除铁,可以将硅铁合金部分提纯至工业硅,具有生产成本低、技术适应性广、应用前景广阔等特点。(The invention relates to a method for preparing industrial silicon by using a ferrosilicon alloy, belonging to the technical field of industrial silicon smelting. The method comprises the steps of continuously adding a ferrosilicon melt into a directional solidification fixed casting device at a constant speed, controlling the temperature, flow rate and solidification speed of the ferrosilicon melt to realize segregation and enrichment of metallic iron, obtaining silicon ingot products with iron content in step distribution, sampling and detecting the silicon ingot products, determining nodes with Fe content in step distribution, and carrying out grading treatment on the silicon ingot to obtain various levels of industrial silicon products with different iron mass contents, wherein the industrial silicon products comprise chemical-level industrial silicon, metallurgical-level industrial silicon and ferrosilicon. The method directly removes iron from the ferrosilicon melt with high efficiency, can purify the ferrosilicon part to industrial silicon, and has the characteristics of low production cost, wide technical adaptability, wide application prospect and the like.)

1. A method for preparing industrial silicon by using ferrosilicon is characterized by comprising the following specific steps:

the method comprises the steps of continuously adding a ferrosilicon melt into a directional solidification fixed casting device at a constant speed, controlling the temperature, flow rate and solidification speed of the ferrosilicon melt to realize segregation and enrichment of metallic iron, obtaining silicon ingot products with iron content in step distribution, carrying out sampling detection on the silicon ingot products, determining nodes with the Fe content in step distribution, and carrying out grading treatment on the silicon ingots to obtain various levels of industrial silicon products with different iron mass contents, wherein the industrial silicon products comprise chemical-level industrial silicon, metallurgical-level industrial silicon and ferrosilicon.

2. The method for preparing industrial silicon using ferrosilicon according to claim 1, wherein: the ferrosilicon alloy melt is No. 90 ferrosilicon alloy and/or ferrosilicon alloy with a grade above No. 90.

3. The method for preparing industrial silicon using ferrosilicon according to claim 1, wherein: the temperature of the ferrosilicon melt is 1450-1750 ℃, the flow rate of the ferrosilicon melt is 0.1-10 kg/s, and the directional solidification speed is 0.1-5 cm/s.

4. The method for preparing industrial silicon using ferrosilicon according to claim 1, wherein: based on the total mass of the industrial silicon product as 100%, the chemical grade industrial silicon product is not less than 40%, the metallurgical grade industrial silicon product is not less than 50%, and the ferrosilicon alloy product is not more than 10%.

Technical Field

The invention relates to a method for preparing industrial silicon by using a ferrosilicon alloy, belonging to the technical field of industrial silicon smelting.

Background

In the existing silicon industry, ferrosilicon faces the situation of excess productivity. In addition, the price of the silicon iron is basically kept to 5500-6200 yuan/ton, while the price of the industrial silicon, the quality of the normal-grade product, such as the price of 441# industrial silicon, is basically stabilized to be more than 10000 yuan/ton. If the ferrosilicon is used as the raw material and the corresponding silicon separation technology is used as the auxiliary material, not only the ferrosilicon and industrial silicon products can be obtained simultaneously, but also the profit margin of the industrial silicon products can be stably promoted, and value-added service is provided for the ferrosilicon industry.

In the existing industrial silicon purification technology, the separation of metal impurities such as iron in silicon is realized by a controllable solidification mode based on a directional solidification technology of a segregation theory; the aim of enriching the impurity Fe into a post-solidification liquid phase is realized through a controllable solidification process, and then the silicon of a pre-solidification part obtains higher purity. However, in the aspect of the casting process of the melt in the industrial silicon industry, the natural air cooling type solidification technology is always adopted, the silicon-iron alloy melt refined by ladle oxygen blowing is directly poured into an ingot mould, and a silicon ingot product is formed through natural cooling. The solidification mode is greatly influenced by factors such as ingot mold structure, melt component fluctuation, manual operation in the casting process and the like, so that different degrees of component segregation are generated in the silicon-iron alloy melt die casting process, the uniformity of industrial silicon products is obviously influenced, and the product quality grade determined according to random sampling detection results and the real product quality are greatly different; therefore, the existing intermittent solidification forming technology cannot meet the continuous controllable requirement of the directional solidification Fe removing technology.

The existing polycrystalline silicon ingot casting technology cannot be directly applied to the industrial silicon production process because the equipment cost and the equipment operation cost of polycrystalline silicon ingot casting are high, the intermittent production period is long, and the polycrystalline silicon ingot casting technology cannot be effectively grafted with the industrial silicon industry with low-cost space and a continuous production mode.

Disclosure of Invention

The invention provides a method for preparing industrial silicon by using a silicon iron alloy, aiming at the problem of insufficient profit space of products obtained by the existing industrial silicon production process, the method fully utilizes the cost advantage of the production of silicon iron products, realizes the segregation and separation of iron elements with segregation coefficient far less than 1 in main silicon by introducing the silicon iron as a direct raw material for the production of the industrial silicon and controlling the casting and solidification processes of silicon iron melt, and can bring huge economic benefit by controlling the process cost when the product with the brand number of FeSi90Al3.0 of the silicon iron is converted into two products of Si441 and FeSi75Al0.5-A.

The invention can convert the low-price ferrosilicon into industrial silicon products, can reduce the cost of the existing industrial silicon production and smelting process, improve the ingot casting efficiency and the product quality, and greatly reduce the dependence of the industrial silicon product quality on raw materials.

A method for preparing industrial silicon by using ferrosilicon comprises the following specific steps:

the method comprises the steps of continuously adding a ferrosilicon alloy melt into a directional solidification fixed casting device at a constant speed, controlling the temperature, the flow rate and the solidification speed of the ferrosilicon alloy melt to realize segregation and enrichment of metallic iron, obtaining silicon ingot products with iron content in step distribution, carrying out sampling detection on the silicon ingot products, determining nodes with the Fe content in step distribution, carrying out grading treatment on the silicon ingots to obtain various levels of industrial silicon products with different iron mass contents, and removing unqualified intermediate products to obtain the silicon ingot products comprising chemical-level industrial silicon, metallurgical-level industrial silicon and ferrosilicon.

The ferrosilicon alloy melt is 90# ferrosilicon alloy and/or ferrosilicon alloy of more than 90# trade mark.

The temperature of the ferrosilicon melt is 1450-1750 ℃, the flow rate of the ferrosilicon melt is 0.1-10 kg/s, and the directional solidification speed is 0.1-5 cm/s.

Based on the total mass of the finally obtained silicon ingot product as 100%, the chemical-grade industrial silicon product is not less than 40%, the metallurgical-grade industrial silicon product is not less than 50%, and the silicon-iron alloy product is not more than 10%.

The invention has the beneficial effects that:

(1) the invention adopts the ferrosilicon melt obtained by electric furnace production as the raw material to replace the prior process of preparing the industrial silicon melt by the carbothermic reduction of a high-purity silica raw material and a carbonaceous reducing agent submerged arc electric furnace, and simultaneously controls the segregation deposition of impurity elements in the ferrosilicon melt aiming at the controllable continuous melt cooling rate and the controllable ingot casting rate of the ferrosilicon melt obtained by furnace discharge, so that the ferrosilicon melt is enriched into the uncrystallized tail melt by strengthening segregation, thereby reducing the impurity content in the high-silicon product which is solidified firstly;

(2) the method solves the problems that the high-quality industrial silicon product is controlled by the purity of the raw materials, the industrial silicon and the ferrosilicon have small profit margin in smelting, and the like, and simultaneously realizes the purpose of increasing the value of the high-quality industrial silicon product prepared from the cheap ferrosilicon raw material.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments, but the scope of the present invention is not limited to the description.