CN107601511A - A kind of method of the separation and Extraction silicon from white residue - Google Patents

Abstract

The invention discloses a method for separating and extracting silicon from silicon slag. The crucible containing silicon slag is placed in an induction furnace, and the furnace is evacuated to 5-10Pa, then filled with argon, and then the induction furnace is started. Heat the silicon slag to 1450~1700°C, keep it warm for 0.5~2h, then lower the temperature to 20~25°C, and finally adopt mechanical separation method to completely separate the cooled silicon from the slag, so as to achieve the purpose of separating and extracting silicon from the silicon slag , the extraction rate of silicon in silicon slag reaches more than 95%, and the method also has a certain removal effect on Fe, Al and Ca in silicon; the process of the invention is simple to operate, low in cost, green and clean, and solves the problem of silicon in industrial silicon enterprises. The current situation that the slag is difficult to separate and reuse can be directly applied to the industrial silicon production process.

Description

A method for separating and extracting silicon from silicon slag

technical field

The invention relates to a method for separating and extracting silicon from silicon slag, belonging to the technical field of separation and purification.

Background technique

Industrial silicon is an industrial product smelted from silica and carbonaceous reducing agent in a submerged thermal electric furnace, and the main component silicon content is above 98%. As a basic material, industrial silicon is widely used in metallurgy, chemical industry, electronics, machinery and other industries. As a raw material for producing solar-grade silicon, industrial silicon is constantly developing. At present, the global industrial silicon production capacity has reached 5.9 million tons per year, with an output of 3.14 million tons, and China's production capacity has reached 4.6 million tons per year, accounting for 78% of the world's total production capacity, with an output of 2.1 million tons.

Silicon slag is a kind of metallurgical slag produced during the process of refining industrial silicon outside the metal silicon ladle furnace. During the ladle refining process, about 200 kg of industrial silicon slag will be produced for every 2 tons of silicon water refined. Silicon slag has long been They are all used to pave roads or be stored as waste slag, occupying a large amount of land space resources. Silicon slag usually contains more than 15% of metal silicon, which is lost in the silicon slag in the form of inclusions, which is difficult to separate and recycle. , resulting in a waste of resources. Therefore, it is of great significance to separate and extract metal silicon from silicon slag.

The easiest way to extract industrial silicon from silicon slag is: first separate the obvious light-colored slag and dark-colored slag in the silicon slag with a manual hammer, then use the principle of middle selection for further separation, and finally use smelting to separate. However, the method of manually separating silicon slag is not only difficult to obtain abundant and pure industrial silicon, but also wastes resources to a certain extent.

Yang Shi et al. (patent number 201611131058.5) disclosed a tribromoethane solution recovery system for the separation of silicon slag, including a residue module and a silicon module, which is characterized by multiple fractionation, good separation effect and high efficiency. Tan Yi et al. (Patent No. 201310244836.1) provided a slagging agent that facilitates the separation of silicon slag during polysilicon medium smelting and its application method, which can improve the separation effect of silicon slag, reduce the viscosity of slag during the separation of slag and silicon, improve the recovery rate, and reduce the cost. Qu Renjing and others published a paper entitled "Technology for Extracting Industrial Silicon from Silicon Slag" (2012, 41(3): 83-85) in "Yunnan Metallurgy", providing a method for processing industrial silicon slag , through manual selection, machine selection, batching, smelting and other processes, using a power frequency furnace, adding a flux, refining elemental silicon from industrial silicon waste slag, and the product reaches industrial silicon precision. Although some researchers have tried to separate silicon slag, it is difficult to achieve the desired effect.

Contents of the invention

The purpose of the present invention is to propose a method for separating and extracting silicon from silicon slag. The recovery effect of the method on industrial silicon is very obvious, and the extraction rate of industrial silicon reaches more than 95%, which solves the difficulty of separating silicon from silicon slag. and utilization status, the invention is low in cost, green and clean, and provides a new way for separating and extracting silicon from silicon slag.

The technical scheme of the present invention is as follows: first, place the crucible containing silicon slag in an induction furnace, and simultaneously evacuate the furnace to 5-10Pa, and fill it with argon; then start the induction furnace to heat the silicon slag to 1450-1700 ℃, and keep it warm for 0.5~2h; cool down the silicon slag after heat preservation to 20~25℃; finally adopt the method of mechanical separation to completely separate the cooled silicon from the slag, that is to achieve the purpose of separating and extracting silicon from the silicon slag.

The present invention separates and extracts the method for silicon from silicon slag, concrete operation is as follows:

(1) Put the crucible with silicon slag in the induction furnace, and at the same time, vacuum the furnace to 5~10Pa, and fill it with argon;

(2) Start the induction furnace to heat the silicon slag to 1450~1700℃, and keep it warm for 0.5~2h; the current frequency of the induction furnace is 2.5~3.0kHz, and the power is 4~6kW;

(3) Cool the silicon slag after heat preservation to 20~25°C; the cooling rate is 20~50°C/min;

(4) Adopt the method of mechanical separation to completely separate the cooled silicon from the slag, that is to achieve the purpose of separating and extracting silicon from the silicon slag; where the wire cutting machine is used to mechanically separate the cooled slag and silicon.

Beneficial effects of the present invention:

(1) The method of the present invention does not need to add any reagent to the silicon slag, and has strong practicability and low production cost.

(2) In the method of the present invention, the purpose of separating silicon slag can be achieved through heating-heating-cooling in an induction furnace, and the operation and equipment are very simple.

(3) The separation effect of silicon slag by the method of the present invention is very obvious, the extraction rate of silicon reaches more than 95%, and the impurity elements Al, Fe, and Ca in silicon also have a certain removal effect.

The method of the invention is simple and easy to operate, low in cost and environmentally friendly, provides a new effective way for separating and extracting silicon from silicon slag, has strong practicability and has broad application prospects.

detailed description

The present invention is further illustrated by the following examples, but it should be noted that the scope of the present invention is not limited by these examples.

Embodiment 1: the method for separating and extracting silicon from silicon slag, concrete operations are as follows:

(1) Using industrial silicon slag with Fe, Al, and Ca contents of 0.187%, 0.121%, and 0.083% respectively as raw materials, weigh 80g of silicon slag and put it into a graphite crucible, place the crucible in an intermediate frequency induction furnace, and simultaneously place the furnace Evacuate the inside to 10Pa, and then fill the vacuum chamber with argon until the pressure is 1 atmosphere;

(2) Adjust the current frequency of the intermediate frequency induction furnace to 2.5kHz and the power to 4.6kW, start the intermediate frequency induction furnace for heating, and measure the temperature with an infrared thermometer;

(3) After the temperature in the furnace reaches 1450°C, keep the molten silicon slag warm for 30 minutes, and then reduce the power to lower the temperature in the furnace to 20°C at a rate of 35°C/min;

(4) Use a wire cutting machine to mechanically separate the cooled silicon slag, and use the XRF method to measure the content of Fe, Al, and Ca metal impurities in the separated silicon to be 0.114%, 0.092% and 0.079% respectively; calculated according to the amount of silicon The extraction rate of silicon in silicon slag is 96.6%.

Embodiment 2: the method for separating and extracting silicon from silicon slag, concrete operations are as follows:

(1) Using industrial silicon slag with Fe, Al, and Ca contents of 0.187%, 0.121%, and 0.083% respectively as raw materials, weigh 100g of silicon slag and put it into a graphite crucible, place the crucible in an intermediate frequency induction furnace, and simultaneously place the furnace Evacuate the inside to 5Pa, and then fill the vacuum chamber with argon until the pressure is 1 atmosphere;

(2) Adjust the current frequency of the intermediate frequency induction furnace to 2.8kHz, power 5kW, start the intermediate frequency induction furnace for heating, and measure the temperature with an infrared thermometer;

(3) After the temperature in the furnace reaches 1500°C, keep the molten silicon slag warm for 2 hours, and then reduce the power to lower the temperature in the furnace to 25°C at a rate of 20°C/min;

(4) Use a wire cutting machine to mechanically cut and separate the cooled silicon slag, and use the XRF method to measure the content of Fe, Al, and Ca metal impurities in the separated silicon to be 0.102%, 0.104% and 0.064% respectively; calculated based on the amount of silicon The extraction rate of silicon in the silicon slag is 95.6%.

Embodiment 3: the method for separating and extracting silicon from silicon slag, concrete operations are as follows:

(1) Using industrial silicon slag with Fe, Al, and Ca contents of 0.187%, 0.121%, and 0.083% respectively as raw materials, weigh 80g of silicon slag and put it into a graphite crucible, place the crucible in an intermediate frequency induction furnace, and simultaneously place the furnace Evacuate the inside to 5Pa, and then fill the vacuum chamber with argon until the pressure is 1 atmosphere;

(2) Adjust the current frequency of the intermediate frequency induction furnace to 3.0kHz, power 6kW, start the intermediate frequency induction furnace for heating, and measure the temperature with an infrared thermometer;

(3) After the temperature in the furnace reaches 1700°C, keep the molten silicon slag warm for 1 hour, and then reduce the power to lower the temperature in the furnace to 23°C at a rate of 50°C/min;

(4) Use a wire cutting machine to mechanically cut and separate the cooled silicon slag, and use the XRF method to measure the content of Fe, Al, and Ca metal impurities in the separated silicon to be 0.165%, 0.118% and 0.073% respectively; calculated based on the amount of silicon The extraction rate of silicon in the silicon slag is 95.0%.

Embodiment 4: the method for separating and extracting silicon from silicon slag, concrete operations are as follows:

(1) Using industrial silicon slag with Fe, Al, and Ca contents of 0.187%, 0.121%, and 0.083% respectively as raw materials, weigh 80g of silicon slag and put it into a graphite crucible, place the crucible in an intermediate frequency induction furnace, and simultaneously place the furnace Vacuumize the inside to 8Pa, and then fill the vacuum chamber with argon until the pressure is 1 atmosphere;

(2) Adjust the current frequency of the intermediate frequency induction furnace to 2.7kHz, power 5.5kW, start the intermediate frequency induction furnace for heating, and measure the temperature with an infrared thermometer;

(3) After the temperature in the furnace reaches 1650°C, keep the molten silicon slag warm for 1.5 hours, and then reduce the power to lower the temperature in the furnace to 25°C at a rate of 30°C/min;

(4) Use a wire cutting machine to mechanically cut and separate the cooled silicon slag, and use the XRF method to measure the content of Fe, Al, and Ca metal impurities in the separated silicon to be 0.152%, 0.0957% and 0.066% respectively; calculated based on the amount of silicon The extraction rate of silicon in the silicon slag is 96.2%.

Claims (4)

1. A kind of 1. method of the separation and Extraction silicon from white residue, it is characterised in that carry out as follows：

   （1）Crucible equipped with white residue is placed in induction furnace, and 5 ~ 10Pa will be evacuated in stove, is re-filled with argon gas；

   （2）Start induction furnace and white residue is heated to 1450 ~ 1700 DEG C, and be incubated 0.5 ~ 2h；

   （3）White residue after insulation is cooled to 20 DEG C ~ 25 DEG C；

   （4）Take mechanically decoupled method to be kept completely separate the silicon after cooling with slag, that is, reach the separation and Extraction silicon from white residue Purpose.
2. 2. the method for the separation and Extraction silicon according to claim 1 from white residue, it is characterised in that：Step（2）Middle induction furnace Power frequency is 2.5 ~ 3.0kHz, and power is 4 ~ 6kW.
3. 3. the method for the separation and Extraction silicon according to claim 1 from white residue, it is characterised in that：Step（3）Middle cooling speed Rate is 20 ~ 50 DEG C/min.
4. 4. the method for the separation and Extraction silicon according to claim 1 from white residue, it is characterised in that：Step（4）It is middle to use line Cutting machine carries out mechanically decoupled to the slag after cooling with silicon.