RU2042643C1 - Method of treatment of acid and alkaline sewage from copper - Google Patents

Abstract

FIELD: sewage treatment. SUBSTANCE: spent acid and alkaline etching solutions were poured off up to pH 3-5, and formed mixture is diluted with water by 1.3-2-fold. Then sulfuric acid is added up to pH 1-2 in the solution, and copper content in prepared solution is determined. Then aluminium chips were loaded at quantity 0.8-1.2 of copper content in solution, and cementation is carried out at temperature 90 C, not above. After acidification with sulfuric acid solution is diluted with water up to copper concentration 20-60 g/l. Proposed method ensures to refine spent etching solutions up to copper concentration ≅ 0,001 g/l. 0.001 g/l. EFFECT: improved method of sewage treatment. 1 tbl

Description

 The invention relates to the treatment of industrial wastewater and can be used in the treatment of spent acidic and alkaline etching solutions of printed circuit boards and galvanic production.

A known method of treating wastewater from copper ions, including pre-treating them with a water-soluble aluminum salt (chloride, nitrite or sulfate) at a rate of 2-2.3 aluminum ions per 1 copper (II) ion, followed by alkalization of the solution. As an alkaline reagent, a suspension of calcium oxide in a solution of sodium carbonate is used at the rate of 5-6 moles of calcium oxide per 1 mol of sodium carbonate, which is introduced until a pH of 12-13 is reached, followed by stirring to form an insoluble compound [1]
The disadvantage of this method is the incomplete purification of copper-containing wastewater due to the impossibility of extracting copper from its complex compounds, for example, copper-ammonia, which can be represented as [Cu (NH ₃ ) ₄ ] Cl.

 Closest to the proposed is a method according to which the copper recycling process is carried out from spent pickling copper chloride acid and alkaline solutions [2] To separate copper from an alkaline solution, the copper-ammonia complex is first destroyed by adding the spent acid pickling solution or waste hydrochloric acid after decapitation to the alkaline solution and The pH is adjusted to 2.5-3, then the mixture is diluted with water to a copper concentration of 60 g / L.

 After that, waste aluminum and its alloys are loaded into the solution. As a result of the substitution reaction, pure copper precipitates in the precipitate, and aluminum chloride is formed in the solution, which is a good coagulant. In the case of an acid pickling solution, it is diluted with water to a copper concentration of 60 g / l, the pH is adjusted to pH 2.3-3.0, aluminum wastes are added and copper is extracted from the solution.

 The disadvantage of this method is the incomplete neutralization of copper ions in spent solutions. It was experimentally established that the spent concentrated copper-containing effluents, purified by the indicated technology until the solution was completely bleached and the copper (II) concentration to 1 g / l, after 3 days change their color to green, and the concentration of copper in the solution increases to 7.5-8 g / l

 The aim of the invention is to increase the degree of purification of acidic and alkaline wastewater from copper.

The spent acidic and alkaline etching copper-containing solutions are poured to pH 3-5, the resulting mixture is diluted with water 1.3-2 times, and then sulfuric acid is added to the pH of the solution pH 1-2, the amount of copper contained in the resulting solution is determined, then load aluminum shavings in an amount equal to 0.8-1.2 of the amount of copper in the solution, and cementation is carried out at a temperature of t ≅ 90 ^about C.

Spent acidic and alkaline pickling copper-containing solutions are poured to a pH of 3-5, which is determined, for example, with Rifan indicator paper with pH limits of 1.8-3.6, 4-5.4. When solutions are drained, the copper-ammonia complex [Cu (NH ₃ ) ₄ ] Cl is destroyed with the formation of copper salts, including chlorine in the form of CuCl ₂ , and gaseous products of CO ₂ , NH ₃ , NO _{2 are released} .

 In this case, chlorine-containing compounds are formed in an amount sufficient to activate (catalyze) the cementation process.

 The resulting mixture is diluted with water 1.3-2 times before adding sulfuric acid to avoid excessive heating and discharge of the mixture. Sulfuric acid is added to pH 1-2 to completely dissolve the copper salts and create a reactive pH.

 Moreover, it was experimentally established that the number of aluminum chips for cementation should be taken with a coefficient K equal to 1.2-0.8 of the amount of copper in solution with a pH of 1-2, respectively.

 When loading aluminum shavings with K> 1.2 of the amount of copper in the solution, aluminum is not used for the reaction and accumulates in the precipitate. When loading aluminum shavings with K <0.8 of the amount of copper in the solution, cementation does not go through, which affects the degree of purification.

 In the proposed method, the concentration of copper is determined by the iodometric method.

Using sulfuric acid in place of hydrochloric acid and reacting the cementation of copper at a temperature not exceeding 90 ^{° C} avoids the formation of aluminum structures dimerized oxochlor- ides and circuit ring of copper ions in the dimer that can improve the degree of purification of the concentrated copper-containing solutions.

The optimal result from the point of view of the reaction rate and the degree of purification is obtained if the solution after acidification with sulfuric acid is additionally diluted with water to a copper concentration of 20-60 g / l, and the loading of aluminum chips is carried out gradually, maintaining the temperature of the solution 40-85 ^about C.

When the copper concentration in solution exceeds 60 g / l cementation process proceeds very rapidly and to maintain the temperature within 40-85 ^{° C} and removal of explosive situation requires either aluminum shavings enter very slowly, thereby increasing treatment time, or to provide additional measures for heat dissipation .

Dilution of the solution to a copper concentration of <20 g / L is impractical, since in this case the cementation process is slowed down, resulting in a cycle time increase in wastewater treatment or for maintaining the temperature within 40-85 ^{° C} requires additional heat input.

Aluminum chips are loaded in successive portions in order to avoid overheating of the solution and maintaining the temperature within 40-85 ^about C.

PRI me R 1. In a Converter with a volume of 1000 l pour 100 l of spent acid etching solution printed circuit boards (pH ≅ 1), which includes chlorinated copper (CuCl ₂ ) with a concentration of copper 180 g / l.

Then, it is added in portions in 2–3 doses, mixing, with a closed mirror of the neutralizer, 100 l of spent alkaline pickling solution of the same production (pH 9–10) containing a copper-ammonia complex [Cu (NH ₃ ) ₄ ] Cl with a copper concentration of 60 g / l Half an hour after the foaming of the resulting mixture with pH 3 ceased, 180 L of water was added to it and mixed. Then add in small portions (approximately 5 l) 20 l of concentrated sulfuric acid (H ₂ SO ₄ ) and mix until the salts are completely dissolved in the precipitate. In this case, in a solution of pH 2, the copper concentration determined by the iodometric method is 60 g / l, and the total amount of copper in 400 l of the solution is 24 kg. Determine the amount of aluminum needed to clean this solution from copper (at pH 2, K 0.8), which is 24 ˙ 0.8 19.2 kg. Next, in the neutralizer with the prepared solution, load the first portion of 10 kg of aluminum chips in a titanium basket with a lid and holes over the entire surface. After about 3 hours, when the temperature of the solution in the converter falls ^to 40 ° C, charged with the second cart with other chips, without removing the first. All withstand until the solution is completely clarified for about 8 hours, after which the baskets with the precipitate are removed, the precipitate is washed and dried.

 The residual copper content in the purified solution is ≅ 1 mg / L.

 PRI me R 2. The spent pickling solutions of the same composition as in example 1 are poured into the neutralizer in an amount of acidic 50 l, alkaline 150 l, in the sequence indicated in example 1.

 The resulting solution with a pH of 5 is diluted 1.35 times with water (i.e. add 70 L of water), mix.

Then add 22.5 l of concentrated sulfuric acid (H ₂ SO ₄ ) as described in example 1. In this case, in a solution of pH 1, the copper concentration is 70 g / l. An additional 608.5 L of water is added to the solution and the copper concentration in it becomes 20 g / L, and the total amount of copper is 18 kg. The required amount of aluminum for this solution is determined (at pH 1, K 1.2), which is equal to 21.6 kg. Further conduct copper cementation on aluminum shavings in the sequence shown in Example 1, except that the time during which the solution temperature after loading the first portion of aluminum chips falls ^to 40 ° C in this case is about 1 h and after loading the last portion to complete clarification of the solution takes about 10 hours

 Example 3. Waste etching solutions of the same composition as in Example 1 are poured into a catalyst in an amount of acidic 67 L, alkaline 133 L, in the sequence indicated in Example 1. 100 is added to the resulting mixture with pH 4. l of water, mix. Then, instead of concentrated sulfuric acid, add 30 l of the spent solution for etching non-ferrous metals of galvanic production, which also includes: sulfuric acid with a concentration of 250 g / l, nitric acid with a concentration of 320 g / l, copper (II) ions with a concentration of 20 g / l

Moreover, in a solution with a pH of 1.8, the copper concentration is 68.7 g / L. An additional 185 l of water is added to the solution and the copper concentration in it becomes 40 g / l, and the total amount of copper is 20.6 kg. The required amount of aluminum is determined (K 1 is taken at pH 1.8), which is equal to 20.6 kg. Further conduct copper cementation on aluminum shavings in the sequence shown in Example 1, except that the time during which the solution temperature after loading the first portion of aluminum chips falls ^to 40 ° C, in this case equal to about 2 hours, and after loading The last portion of chips until the solution is completely clarified takes about 9 hours.

 The main parameters of the method for cleaning spent pickling solutions from copper, carried out in the modes described in examples 1-3 are shown in the table.

Claims (1)

METHOD FOR CLEANING ACID AND ALKALINE WASTE WATER FROM COPPER, including mixing acidic and alkaline wastewater before an acid reaction, diluting it with water to a certain copper concentration, acidifying the resulting solution and cementing on aluminum waste, followed by separation of the precipitate, characterized in that, in order to increase the degree purification, dilute the mixture with water to a concentration of copper 20 60 g / l in it, acidify the resulting solution with sulfuric acid to a pH of 1-2, and cementation is carried out on aluminum chips, taken in an amount of 0.8-1.2 of the quantity va copper in solution, at a temperature of not more than 90 ^o C.

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