Processing Method Of Silicon Cutting Waste Liquid

Abstract

The present invention relates to a processing method of a silicon cutting waste liquid. In a particle-dispersed suspension which comprises solid component, namely the silicon cutting waste liquid, separated components such as polar aprotic solvent, polar protic solvent, nonionic agglutinant, ethylenediamine polybasic acid, and salt thereof, so the solid phase in the waste liquid is agglutinated and deposited. Excellent solid-liquid separation in an earliest period of the waste liquid treatment is ensured, so as to facilitate recycling of the useful components in the waste liquid. The invention provides the processing method which causes excellent solid-liquid separation of the silicon cutting waste liquid that is discharged in the processing step in semiconductor component manufacturing wherein crystal silicon is used as the substrate and separates and recycles the useful components such as silicon chips through low load and low cost for regeneration and reuse.

Description

technical field [0001] The present invention relates to a treatment method for silicon cutting waste liquid, and more specifically, relates to a simple and cheap means to make the silicon cutting waste liquid discharged during the cutting process of crystalline silicon (crystalline silicon) such as semiconductor element manufacturing etc. solid-liquid A treatment method for silicon cutting waste liquid that separates and makes the actual recovery, regeneration, and reuse of silicon and other useful components contained in silicon cutting waste liquid possible or easy. Background technique [0002] In the manufacturing process of semiconductor elements, solar cells, etc., single crystal silicon or polycrystalline silicon as a substrate is subjected to cutting, grinding, cutting, and polishing (hereinafter, collectively referred to as "cutting" as necessary), and these cutting processes A large amount of silicon chips generated are often discarded in vain. [0003] For exampl...

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Problems solved by technology

[0008] That is, useful solid components such as silicon cutting chips or abrasive grains, solid components of impurities such as grinding tools or wire saw wear pieces, and crushed abrasive grains are contained in the silicon cutting waste liquid as fine particles, and these solid component particles are dispersed in a colloidal state , become a suspension that stabilizes the silicon cutting waste liquid. Therefore, it is extremely difficult to achieve good solid-liquid separation, separation and recovery of the solid phase by natural precipitation of the solid component, using a filter, or by separation membrane filtration, centrifugation and other common means. In addition, in silicon cutting waste liquid, hydrogen gas is actively generated due to the oxidation reaction of silicon cutting chip particles, so distillation separation is also accompanied by a very large risk.

[0009] This point has been pointed out in the prior art. For example, referring to Patent Document 4, the silicon cutting waste liquid is concentrated in the sedimentation tank for natural precipitation, and the pH value is adjusted, which can only achieve the level of solid-liquid separation for the purpose of discarding, that is, using When the centrifugal separation device implements solid-liquid separation, although the liquid phase can be supplied and reused through filtration, the treatment of the solid phase is extremely difficult, and the processing speed is slow and the processing efficiency is poor. Moreover, even if the separation membrane filter is used, in order to capture the solid component, it must not It does not make the distinction performance fine, so the filtering speed is slow and cannot keep up with the processing capacity

[0010] As mentioned above, for silicon cutting waste liquid, it is extremely difficult to have effective and good solid-liquid separation at a practical level, and insufficient solid-liquid separation itself causes a great burden, and it is recovered from The treatment process of separating and recovering desired useful solid components such as silicon or abrasive grains individually from the solid phase, and the treatment process of separating and recovering useful components such as cooling medium from the liquid phase that has not been sufficiently separated and recovered from the solid phase require complex and cumbersome procedures. Substantial burden on processing, equipment, and facilities, resulting in the need to prevent the cost of practical implementation

[0011] As an example thereof, for example, the "method for recovering silicon" of Patent Document 5, figure 2 The processing steps are shown as a flow chart. In order to recover silicon from the silicon cutting waste liquid, a very large number of processing steps are required, and the processing of each step is complicated and troublesome, and requires a huge burden on equipment and facilities. On the other hand, according to Patent Document 2, Even if organic solvents are used to wash the solids, it is still difficult to remove impurities such as dispersants, which remain in the solids and hinder the improvement of the purity of recovered silicon. Even if the solids are put into the air stream, silicon oxide and abrasive particles may not be sufficiently removed. , it is difficult to obtain high-purity silicon. Moreover, the "Manufacturing Method for Extracting Silicon from Waste Sludge" of this patent document 2 proposes to use centrifugation to separate the waste sludge of the separation magnet into silicon dispersion liquid and abrasive particles. Solid impurity sedimentation layer, but sufficient solid-liquid separation cannot be obtained in centrifugation. Therefore, the post-treatment process requires a lot of burden, and it is difficult to say that it is a simple and efficient method that can be actually implemented.

[0012] Conversely, if good solid-liquid separation can be achieved simply and cheaply in the initial stage of silicon cutting waste liquid treatment, not only can the processing burden of the solid-liquid separation process itself be greatly reduced, but also, thereafter, the solid phase recovered from the separation The treatment process of separating the useful components from the liquid phase for regeneration and reuse is also simple and easy, and becomes cheap, and it is easier to separate and recover all the useful components contained in the silicon cutting waste liquid than before. Therefore, it is a kind of recycling contained in A practical method for regenerating and reusing useful components such as silicon that are mostly discarded in silicon cutting waste liquid, but no meaningful proposal for such treatment has been proposed or suggested in the prior art

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