A kind of treatment method of alkaline etching waste liquid

Abstract

The invention discloses a treatment method for alkaline etching waste liquid, (1) adding excess calcium oxide to the alkaline etching waste liquid, and introducing it into an ammonia distillation tower, and separating the solid and liquid to obtain a blue-white precipitation mixture; (2) ammonia gas Absorbed by the absorption tower to prepare a 20%-40% ammonia solution; (3) add sulfuric acid to the blue-white precipitate mixture until the blue precipitate is dissolved, and separate the solid and liquid to obtain the Bordeaux mixture stock solution; the present invention introduces calcium oxide as an alkali source to produce Bordeaux liquid, and no new pollutants are introduced, avoiding a large amount of salinization of fresh water, resulting in waste of fresh water resources, and high recovery value.

Description

technical field [0001] The invention relates to the technical field of etching liquid waste treatment, in particular to a treatment method for alkaline etching waste liquid. Background technique [0002] Etching waste liquid is an important pollutant produced by the printed circuit board industry. Etching waste liquid contains a large amount of copper. If it is not handled properly, it will not only pollute the environment, but also cause a serious waste of resources. Common etching liquids are mainly alkaline There are several kinds of etching solution, acid etching solution, and traditional ferric chloride etching solution. The corresponding etching waste liquid mainly includes acid etching waste liquid, alkaline etching waste liquid, ferric chloride etching waste liquid, alkaline etching The main component is a solution containing copper ammonium ions, and the main components include copper chloride, ammonia water, ammonium chloride, etc. When etching circuit boards, alk...

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Problems solved by technology

[0003] [Cu(NH 3 ) 4 ]Cl 2 It can react with the copper plating on the surface of the circuit board to form a cuprous complex, and it is Cu(NH 3 ) 4 + , the generated Cu(NH 3 ) 2 + Although it does not have etching ability, it can be quickly oxidized by air and regenerated in the case of excessive ammonia water and chloride ions. As the concentration of copper ions in the etching solution increases gradually, the etching rate of the etching solution also decreases. , until it finally loses its etching effect and becomes an etching waste liquid. Therefore, the main component in the alkaline etching waste liquid is the complex Cu(NH 3 ) 2 Cl 2 , ammonia, chloride, etc., the copper content is about 100-160g / L, the total ammonia (NH 3 , NH 4 + ) content is about 150-200g / L, if it is discharged directly without proper disposal, it will not only waste precious resources, but also cause great harm to the environment

[0004] In the prior art, one of the commonly used methods for treating alkaline etching solution is to add a sufficient amount of sodium hydroxide solution to the alkaline etching waste solution and heat it to generate copper oxide and ammonia gas to remove the copper ions in the waste solution. and ammonium ion extraction, the technology is mature and the processing capacity is large, so it is widely used. Many waste liquid treatment plants have built production lines with an annual processing capacity of tens of thousands of tons. However, this technology needs to consume high-cost hydrogen Sodium oxide is used to produce low-value sodium chloride, and although the country does not prohibit the discharge of sodium chloride for the time being, it does not advocate a large amount of salinization of limited and valuable fresh water, and the ammonia nitrogen content in the treated wastewater is not easy to meet the standard , in order to effectively utilize chloride ions and recycle ammonium chloride, the patent CN103602988A aims at the problem of reclaiming ammonium chloride, adding alkali source, absorbing ammonia water with concentrated hydrochloric acid to be ammonium chloride solution, and realizing the regeneration and reuse of etching solution, however, This is equivalent to introducing new acid pollutants, and it needs to consume hydrochloric acid fuel and equipment, the operation is complicated, the economic applicability is poor, and the alkali source is NaOH or Ca(OH) 2 Solution, if NaOH solution is used, high-concentration NaCl solution will be discharged, not only the limited and precious fresh water will be salinized in large quantities, but the price of using a large amount of NaOH is more expensive, and the cost of converting it into NaCl is high, and the effect of NaOH solution is not as good as NaOH solid reaction efficiency High, low reaction efficiency, and waste of heating energy, if using Ca(OH) 2 Solution, itself Ca(OH) 2 It is an alkaline compound that is slightly soluble in water, and the solute that actually participates in the reaction is low, and it is inevitable that excess Ca(OH) will appear after the reaction 2 Precipitation phenomenon, mixed with copper oxide precipitation, in this patent, there is no mention of further processing steps of the precipitation mixture, so the technology is still flawed

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