Treatment method for recycling hydrofluoric acid waste liquor

Abstract

The invention discloses a treatment method for recycling hydrofluoric acid waste liquor. The treatment method comprises the following steps of: analyzing the content of silicon in hydrofluoric acid waste liquor; adding a compound of sodium, potassium or barium, which is more than the content of silicon by once, into the hydrofluoric acid waste liquor in a treatment slot, so that the fluorine and silicon is combined with sodium, potassium or barium in the hydrofluoric acid waste liquor for a reaction to generate fluosilicate solids of sodium fluosilicate, potassium fluosilicate or barium fluosilicate; extracting the upper layer of liquor after settling the fluosilicate solids, and conveying back to the original process for use after adding high-concentration hydrofluoric acid to achieve a hydrofluoric acid concentration value satisfying the use of the original use. The hydrofluoric acid waste liquor is only added with a little sodium, potassium or barium ions to prepare the hydrofluoric acid which can be recycled, so that less chemical drug is consumed, the wastewater emission is greatly lowered, the hydrofluoric acid usage amount of the original process is saved and the extra purchase cost is saved, and therefore, the treatment steps are simplified, the treatment cost is lowered and environment-friendly benefits are achieved.

Description

technical field [0001] The invention relates to a treatment method for recycling and reusing hydrofluoric acid waste liquid, in particular to a method that can recycle hydrofluoric acid in hydrofluoric acid waste liquid and reuse it in the etching process, which has the advantages of saving the original etching process The purchase cost of hydrofluoric acid usage is low, and the processing volume is large, fast and easy, and it has multiple functions such as avoiding high heat to cause fire and producing thick smoke of hydrofluoric acid to harm the human body. Background technique [0002] With the vigorous development of industries such as semiconductors, liquid crystal panels, and solar cells, the use of hydrofluoric acid (Hydrofluoric Acid; HF (aq)) in the production process to etch silicon and silicon compounds will also increase. After hydrofluoric acid etches silicon or silicon compounds, the amount of silicon-containing hydrofluoric acid waste liquid also increases; d...

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Problems solved by technology

[0014] 3. The third method is as disclosed in the Republic of China Invention Publication No. 200930663. It is to add hydrofluoric acid to the hydrofluoric acid waste liquid to adjust the hydrofluoric acid waste liquid to a certain concentration, and then add silicon and sodium. In the hydrofluoric acid waste liquid after adjusting the concentration, the fluorine ion is converted into sodium fluorosilicate, by adding excessive silicon-containing compound and sodium-containing compound (generally adding sodium silicate; trade name is water Glass) in hydrofluoric acid waste liquid to generate insoluble sodium fluorosilicate crystals (Na 2 SiF 6 ), and finally the sodium fluorosilicate crystals are dried to achieve recovery of fluorine; therefore, the cost of the chemical agent is large, and the amount of waste water produced is also extremely high, resulting in high waste water treatment costs, and at the same time, gums will be generated during the treatment process. The disadvantages of the gelatinous substance delay the formation rate of sodium fluorosilicate, and the subsequent dehydration treatment is extremely difficult due to the influence of the gelatinous substance. Because water glass is an alkaline substance but hydrofluoric acid is an acidic substance, it will form harmful substances. The exothermic acid-base neutralization reaction requires the use of heat exchangers to increase the processing speed. However, because hydrofluoric acid is corrosive to metals, only plastic heat exchangers with poor thermal conductivity can be used, which also reduces the processing speed. slow, and not a good way to handle it

[0015] The above three existing hydrofluoric acid waste liquid treatment methods also have a common shortcoming, which is limited to taking out the fluorine in the waste liquid to make cheap fluorine chemicals, which wastes the recovery and reuse of hydrofluoric acid. People aim at above-mentioned weak point, through a large amount of theoretical analysis and experiment, finally design the method of the present invention

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