A method and device for treating waste water containing ultrafine silicon powder

Abstract

The invention discloses a treatment method and device of wastewater containing superfine silicon powder, and belongs to the field of treatment of wastewater containing silicon powder in polycrystalline silicon industry. The method comprises the following steps: with a 20%-32% NaOH solution as a precipitant, adding the wastewater containing the superfine silicon powder, flocculating the superfine silicon powder in the wastewater, and naturally participating for about an hour. By virtue of the high-concentration NaOH solution as the precipitant, the problems that silicon powder particles in the wastewater generated by the cutting process of a silicon core and the like are too small, and high in surface activity, are hydrogenated with water, suspend in water for a long period of time (over half a year) without participation, and are difficult to filter are solved; the burden of an existing filter-press process can be greatly relieved; the filtering efficiency is improved; resource utilization is realized by supernatant alkaline water and filtrate alkaline water for a chlorosilane waste gas leaching process as absorbents; meanwhile, the treatment pressure of a subsequent wastewater treatment system is relieved; and the method and the device are simple in technology in treatment of the wastewater containing the superfine silicon powder, short in flocculation and precipitation time, good in treatment effect and low in cost.

Description

technical field [0001] The invention relates to a treatment method and device for waste water containing ultrafine silicon powder, and belongs to the field of treatment of waste water containing silicon powder in the polysilicon industry. Background technique [0002] Source of waste water containing silicon powder: In the silicon core preparation process, the silicon powder produced by cutting silicon rods with silicon core saws is used, and ultrapure water is used as the direct cooling of the silicon rod cutting process and the washing place for the surface of silicon core saws and silicon rods The formed silicon powder-containing wastewater containing ultrafine silicon powder. [0003] The silica fume in the silica fume-containing wastewater is very fine, and most of the particle diameters are in the range of 0.1-1 μm. Most of the fine particles are suspended in the water. After standing for more than half a year, only some large particles are deposited at the bottom, and...

AI Technical Summary

Problems solved by technology

The advantage of this invention is that the treated water is neutral and can be directly discharged or reused. The disadvantage of this invention is that the filtrate in the early stage is unqualified, and the filter membrane needs to be replaced continuously, which is costly. In addition, due to the waste water containing silicon powder The particle size of silicon powder in the medium is small, the filter membrane is seriously clogged, and it is difficult to clean. Cleaning the filter cloth produces a large amount of wastewater, which increases the amount of wastewater and makes the treatment efficiency low.

The advantage of this method is that the resource utilization of silicon powder in silicon powder-containing wastewater has been realized, and the water has been treated. However, for the silicon powder-containing wastewater in the present invention, the silicon powder particle size is very fine, and the silicon powder-containing wastewater is directly centrifuged. Separation doesn't apply, it doesn't work well

[0011] Patent CN103028329A discloses a grinding wastewater recycling and silicon powder recovery device with a tubular microfiltration membrane module. The advantage is that the treatment effect is good and the treatment efficiency is high, but the cost of this method is relatively high

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