Intermittent operation method and device for recovery and purification of hexachlorodisilane from chlorosilane residual liquid

Abstract

The invention aims to provide an intermittent technology and a device for treatment and recovery of chlorosilane residual liquid and residue thereof, especially a method and a device for recovering hexachlorodisilane with very high value. The invention puts forward an intermittent technical scheme for the circumstance of a small residual liquid treatment amount. The technology mainly involves a primary rectification tower and an intermittent rectification tower. The method and the device provided in the invention are particularly applicable to treatment of the cold hydrogenation slag slurry and rectification residual liquid in polysilicon production, the rectification residual liquid and other dirty residual liquids in a synthesis process, and are also applicable to the rectification residual liquid in a reduction process and the rectification residual liquid in a thermal hydrogenation process or mixed type residual liquids, etc. With the treatment technology disclosed in the invention, hexachlorodisilane with purity above 98% can be recovered.

Description

technical field [0001] The invention relates to a batch operation method and device for recovering and purifying hexachlorodisilane from chlorosilane raffinate, in particular to hexachlorodisilane (also known as hexachlorodisilane and perchlorodisilane), which is a high boiler in chlorosilane Recovery method and device thereof. Background technique [0002] Polysilicon is the main raw material required by the electronics industry and the photovoltaic industry, and is a strategic material necessary for the development of my country's electronic information industry and solar photovoltaic industry. [0003] In the production process of polysilicon, a certain amount of raffinate will inevitably be produced along with the tail gas of rectification and purification of chlorosilane synthesis reaction, reduction reaction and cold (hot) hydrogenation reaction. This part of raffinate is useless for the production of polysilicon. In addition, due to the high solid content in this par...

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Problems solved by technology

[0008] Obviously, compared with the reasonable recovery of various components in the raffinate, the hydrolysis of the raffinate will cause huge waste, especially with the continuous expansion of polysilicon production, the raffinate that has not been reasonably recovered will increase exponentially. If the raffinate can be effectively recovered The high value-added components in the liquid, especially hexachlorodisilane, will surely enable enterprises to remain invincible in today's fierce polysilicon market competition

However, due to the many impurities in the chlorosilane raffinate in the cold hydrogenation process and synthesis process, organochlorosilanes such as trichloromethylsilane (boiling point 70.2°C) and silicon tetrachloride (boiling point 56.8°C), titanium tetrachloride (boiling point 136°C) is close to hexachlorodisilane (boiling point 145°C), which requires high recovery, purification and separation process

[0009] U.S. Patent US0193958 proposes a method of using an intermittent paddle dryer to dry and recycle chlorosilane residual liquid. After evaporation and recovery, trona is used to neutralize the remaining residual liquid and solid residue. This method is an environmentally friendly method. And it can recover a certain amount of chlorosilane, but it does not involve the recovery of high boilers and high value-added hexachlorodisilane

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