Device and method for separating and recovering silicon and silicon carbide in cutting waste mortar of silicon wafers

Abstract

The invention discloses a device for solid-solid separation and recovery of silicon and silicon carbide in cutting waste mortar of silicon wafers. In the device, an inlet pipe is connected to a cylinder of a vertical electrophoresis tank, anode electrode tubes are arranged above the vertical electrophoresis tank, cathode electrode tubes are arranged below the vertical electrophoresis tank, an outlet of a main electrode tube of the anode electrode tubes is connected with a silicon outlet pipe, and the other side of the silicon outlet pipe is connected with a silicon outlet pump which is connected to a silicon recovery tank; and a main electrode tube of the cathode electrode tubes is connected with a silicon carbide outlet pipe, and the other side of the silicon carbide outlet pipe is connected with a silicon carbide outlet pump which is connected to a silicon carbide recovery tank. The cutting waste mortar of the silicon wafers is subjected to solid-liquid separation; and heavy liquid and a dispersant are added into the obtained solid phase sediment for ultrasonic oscillation and dispersion, and the silicon and the silicon carbide are separated through a vertical electrophoretic separation device. The purity of the silicon carbide obtained by separation in the process is more than or equal to 98.5 percent, and the purity of the silicon is more than or equal to 99.9 percent. The heavy liquid is non-volatile, nontoxic and environment-friendly solution of sodium polytungstate or ionic liquid. The method solves the problem of gravity effect caused by horizontal electrophoresis and realizes environment friendliness.

Description

technical field [0001] The invention relates to the technical field of recycling waste mortar, a by-product of silicon chip cutting processing in the solar energy and electronics industries, in particular to a device and method for separating and recycling silicon and silicon carbide in the silicon chip cutting waste mortar. Background technique [0002] At present, a large amount of waste mortar is continuously discharged during the industrial cutting and production of solar silicon rods. These mortars usually contain polyethylene glycol, silicon carbide and valuable high-purity silicon powder. The production of silicon shavings not only reduces the performance of the cutting fluid, but also leads to a decrease in the utilization rate of silicon. At the same time, silicon wafers account for almost 50% of the cost in the photovoltaic power generation industry. Therefore, how to reduce the cost of silicon wafers and processing costs has become a key link in reducing the tota...

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Problems solved by technology

In the patent 200710018636.9, a method for recovering silicon and silicon carbide is disclosed, but the liquids used are mostly dibromomethane and tribromomethane solutions with strong toxicity, which will undoubtedly cause certain pollution to the environment

Patent 201010140008.X mentions the method of electrophoretic separation. The conventional electrophoretic device uses an electric field to separate silicon and silicon carbide. The main problem is that silicon and silicon carbide in the particle state are not real ions. When moving to the positive and negative plates in the horizontal direction, the steric hindrance is large, the effect of gravity is large, and the separation is not clear; it is difficult to classify and collect samples, and the purity of the obtained products is low, requiring many times of repeated separation work, and the degree of industrialization is low

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