Process for treating residual liquid and tail gas in polysilicon production by improved Siemens method

Abstract

The invention relates to a process for treating a tail gas, in particular to a process for treating a residual liquid and a tail gas in polysilicon production by an improved Siemens method. The invention provides a process for treating the residual liquid and the tail gas in polysilicon production by the improved Siemens method, which is difficult to block a pipeline. The process comprises the following steps of: carrying out neutralization reaction on the high-boiling substance residual liquid, the chlorosilane tail gas and eluent; emptying the gas after the neutralization reaction; treating the liquid after the neutralization reaction to neutrality and then carrying out harmless treatment, wherein the eluent is lime milk with the volume percentage of 10-30 percent. When the lime milk eluent of the process is used, calcium chloride is slowly crystallized, and crystals are quite loose, are easy to clean and can not block the pipeline; compared with sodium hydroxide, 8-10 percent of eluent can be saved, and the production cost is saved.

Description

technical field [0001] The invention relates to a tail gas treatment process, in particular to an improved Siemens method polysilicon production raffinate and tail gas treatment process. Background technique [0002] Chlorosilane tail gas and high-boiler raffinate will be produced during the polysilicon production process of the improved Siemens process. If it is not handled carefully, it will cause very serious safety hazards and environmental pollution accidents. Therefore, how to deal with the above two substances is still a very difficult problem in the production process of polysilicon. At present, polysilicon manufacturers generally use double-tower series leaching, and the above-mentioned tail gas and residual liquid are processed through the rinsing device (such as figure 1 Shown): Tail gas and residual liquid enter from the eluting tower, and neutralize with the eluent in the eluting tower. There is a circulation tank at the bottom of the leaching tower to collect...

AI Technical Summary

Problems solved by technology

Sodium chloride crystals will gradually grow up and block pipes, nozzles, valves, etc., resulting in obstruction of exhaust gas and residual liquid discharge, causing overpressure in the production device system and causing safety hazards

[0005] (2) Pipes, nozzles and valves need to be disassembled and cleaned frequently, and because sodium chloride crystals are very strong after crystallization, it is very easy to cause damage to pipes, nozzles, valves, etc. during the cleaning process

[0006] (3) Sodium hydroxide is extremely alkaline and highly corrosive, which poses a certain safety hazard during operation

[0007] (4) Sodium hydroxide is a monobasic base, and its ability to neutralize chlorosilane tail gas and residual liquid is relatively weak, so it is necessary to frequently replace fresh sodium hydroxide solution

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