Method for purifying silicon through semi-continuous crystallization in silicon alloy melt

A silicon alloy, semi-continuous technology, applied in the field of silicon purification, can solve the problems of difficult operation, slow growth rate, slow growth rate of Si crystal, etc., to achieve the effect of simple equipment operation and process, increased growth rate and fast growth rate

Inactive Publication Date: 2014-06-04
INST OF PLASMA PHYSICS CHINESE ACAD OF SCI
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Problems solved by technology

[0005] In U.S. Patent US42567117A (R.K.Dawless, Silicon purification method), after Si and Al are alloyed, the temperature is lowered to grow Si sheets, and then a pressing plate is used to press the grown Si sheets to the bottom of the crucible, and then the excess alloy melt is poured Take out the crucible, collect the remaining Si flakes, and realize discontinuous Si flake crystal growth, but this method has slow growth rate, low production efficiency, complicated separation method of Si flakes and melt, and difficult operation
[0006] In the world patent WO2010098676A1 (H.Tathgar, Method for the production of solar grade silicon), two furnaces for melting Si alloys are used, one furnace with a higher temperature is used to add and melt Si raw materials, and then high-temperature Si alloy melt After filtering, it is pumped to a second furnace with a lower temperature, where Si grows into larger crystals and is periodically removed, and the remaining Al-Si melt is pumped back to the first furnace through a filter screen. In the furnace, the continuous purification of Si has been realized, but the growth rate of Si crystals in this method is slow, the equipment and operation process are very com

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  • Method for purifying silicon through semi-continuous crystallization in silicon alloy melt

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Example Embodiment

Specific embodiment 1:

[0042] Mix 358.7g of metallurgical silicon (grade 3303) as a raw material with 1076.1g of metallic aluminum (purity 96.5%). The typical impurity content of silicon and aluminum is shown in Table 1. Heat the mixture to 950°C to melt and keep it for half an hour, then use a quartz rod Stir the melt and insert it into the crystallization rod after it is completely mixed. Use a stainless steel tube with a diameter of 25.4mm as the crystallization rod with a rotation speed of 130r / min. m 3 / hr, at the same time, reduce the furnace temperature, the cooling rate is 1.7°C / min, cool to 616°C, lift the crystallization rod out of the melt, the surface of the crystallization rod is attached with growing silicon crystals, and use a hammer to separate the silicon crystals from the crystallization rod , Obtain 90.84g of silicon crystals. After the silicon crystal was soaked in dilute hydrochloric acid to remove the attached Al, the ICP-OES test was performed, and th...

Example Embodiment

Specific embodiment 2:

[0047] Mix 622.5g of metallurgical silicon (grade 3303) as a raw material with 1228g of metallic aluminum (purity 96.5%). The typical impurity content of silicon and aluminum is shown in Table 1. Heat the mixture to 1050°C to melt and hold it for half an hour, then stir it with a quartz rod Insert the crystallization rod after the melt is completely mixed, use a stainless steel tube with a diameter of 25.4mm as the crystallization rod, and use a stainless steel tube with a diameter of 8mm as a cooling air pipe to feed air at room temperature into the crystallization rod at a ventilation rate of 0.1m 3 / hr, at the same time, reduce the furnace temperature, the cooling rate is 0.12°C / min, cool to 602°C, lift the crystallization rod out of the melt, the surface of the crystallization rod is attached with growing silicon crystals, and use a hammer to separate the silicon crystals from the crystallization rod , to obtain 78.4g of silicon crystals. After the...

Example Embodiment

Specific embodiment 3:

[0050] Mix 642.8g of metallurgical silicon (grade 3303) as a raw material with 1499.8g of metallic aluminum (purity 96.5%). The typical impurity content of silicon and aluminum is shown in Table 1. Heat the mixture to 1050°C to melt and keep it for half an hour, then use a quartz rod Stir the melt and insert it into the crystallization rod after it is completely mixed. Use an alumina tube with a diameter of 25.4mm as the crystallization rod with a rotation speed of 25r / min. 0.1m 3 / hr, at the same time, reduce the furnace temperature, the cooling rate is 0.2°C / min, cool to 600°C, lift the crystallization rod out of the melt, the surface of the crystallization rod is attached with growing silicon crystals, and use a hammer to separate the silicon crystals from the crystallization rod , Obtain 186g of silicon crystals. After the silicon crystal was soaked in dilute hydrochloric acid to remove the attached Al, the ICP-OES test was performed, and the resu...

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Abstract

The invention discloses a method for purifying silicon through semi-continuous crystallization in silicon alloy melt. The method comprises the steps of heating and melting silicon and Al or Al alloy to form an Al-Si base alloy melt, inserting an air-cooled revolving crystallizing rod in the melt so that silicon crystal is separated out of the alloy melt while such major impurities as B and P are kept in the alloy melt, thus achieving an effect of removing impurities. The air-cooled continuous rotating crystallizing rod is inserted in the melt and relatively high cooling speed is adopted to improve crystal growth speed, so as to realize semi-continuous crystallizing growth in the silicon alloy melt. The method disclosed by the invention has the advantages of being low in energy consumption, free from pollution, high in production efficiency, capable of realizing semi-continuous production, small in investment scale, and simple in production process and equipment operation.

Description

technical field [0001] The invention relates to the field of silicon purification, in particular to a method for semi-continuous crystallization and purification of silicon from a silicon alloy melt. Background technique [0002] Traditional energy sources such as oil and coal are showing signs of depletion and serious pollution. For example, currently 50% of China's "haze" PM2.5 emissions come from fuel combustion. Photovoltaic power generation has many advantages such as cleanness, safety, and sustainable use, and has become one of the main new energy sources. In recent years, it has been vigorously supported by many governments around the world. The output and market of solar cells have shown rapid growth, with an average annual growth rate of Above 30%. Due to the mature technology of silicon materials, abundant raw materials, relatively low price, and no toxic and side effects to the environment, silicon materials occupy an important position in solar cells. The main ...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 陈健李彦磊张涛涛班伯源戴松元
Owner INST OF PLASMA PHYSICS CHINESE ACAD OF SCI
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