Treatment method for waste water with high chloride ion content in polysilicon production

Abstract

The invention relates to a treatment method for waste water with high chloride ion content in polysilicon production. The treatment method comprises steps of: A. pretreating the waste water with high chloride ion content aggregated in the pool to obtain a sodium chloride solution with a clarification degree and a pH reaching standards and deposition; B. concentrating the sodium chloride solution to obtain 40-50% sodium chloride concentrate and 50-60% reuse water and filtering the deposition; C. carrying out evaporation crystallization on the sodium chloride solution to obtain a sodium chloride solid-liquid mixture; D. filtering and drying the sodium chloride solid-liquid mixture containing crystals to obtain high purity sodium chloride salt. The invention employs a technology containing aconcentration before an evaporation to change waste into valuables, reuse and save water resource as possible and produce high quality solid sodium chloride salt; besides a relative cost, steam amount and electric energy are reduced and saved.

Description

technical field [0001] The invention relates to a treatment process for tail gas and raffinate in polysilicon production, in particular to a treatment method for high-concentration chlorine-containing wastewater. Background technique [0002] Waste water containing chloride ions is produced in the polysilicon process. At present, in the polysilicon industry, there are mainly the following process routes for the treatment of chlorine ion-containing wastewater: [0003] 1. Use a certain concentration of lime emulsion as the spray liquid to wash the tail gas and residual liquid generated in the production of polysilicon, thereby producing a large amount of high-concentration calcium chloride-containing wastewater. The waste water is firstly filtered into the plate and frame filter press, and then the filtrate is adjusted to neutral by adding lime emulsion or hydrochloric acid, and then enters the plate and frame filter press for filtration again, and the clarified filtrate is ...

AI Technical Summary

Problems solved by technology

[0009] ① Greater damage to the filter press;

[0010] ② High power consumption;

[0011] ③ Has a greater environmental risk

[0014] ① Greater damage to the filter press;

[0015] ② High energy consumption and high cost

[0018] ① High energy consumption and high cost;

[0019] ② There is a relatively large environmental risk

[0022] ① High energy consumption and high cost

[0023] The main reason is: repeated evaporation until crystallization consumes a lot of energy