SU1678903A1 - Process for recovering spent cuproammonia etchant - Google Patents

Abstract

This invention relates to the disposal of spent pickling solutions, in particular copper-ammonia. The aim of the invention is to increase the purity of the copper oxide. The method of processing spent copper ammonium pickling solution includes the preliminary introduction of ammonia into the solution to dissolve the precipitate from copper compounds, removing the tin and lead compounds by filtration and treating the base with an alkali solution in an amount of 80-125 g / l. The ammonia recovery is carried out at boiling point until it is completely removed. All this increases the purity of the resulting copper oxide. 1 tab.

Description

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This invention relates to the disposal of spent pickling solutions, in particular copper-ammonia.

The aim of the invention is to increase the purity of the resulting copper oxide.

Usually, a copper-ammonium solution is used to etch printed circuit boards with a protective tin-lead layer and some of these components go into solution, the content of which in copper compounds is extremely undesirable.

The filtrate should not contain NH / iCI and copper salts. The filtrate after evaporation and the production of NaOH is used in electrolysis to produce NaOH and CI2, the presence of N2 derivatives in production is unacceptable.

Preliminary, the precipitate from the Pb and Sn compounds is separated from the spent solution by filtering.

copper salts are present, MLs are added to completely dissolve them.

After the separation of the Pb and Sn compounds, the spent solution is separated into its constituent components: CuO-NH4CI-NH3-H20 and the alkali is added. The alkali is consumed in the following reactions.

 + 2NaOH-CuO + H20 + 2NaCI (1); + NaOH + NaO + NaCl (2).

In this case, the alkali is added to the solution in an excess of about 80-125 g / l. This excess is necessary to accelerate the process of obtaining CuO and distilling ammonia. It has been experimentally established that an excess concentration of NaOH of less than 80 g / l increases the time for distilling off NHs and obtaining CuO to 5-6 hours. An excess of alkali (more than 125 g / l)

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leads to better results. An excess of alkali permits the complete removal of all nitrogen derivatives and is necessary for dissolving Pb (OH) a and producing plumbits in the liquor.

A side solution is obtained in the case of absorption with chilled water and MY4C1 in the case of absorption with a solution of HCl. These products return to the stage of the adjustment process of the pickling solution.

The copper oxide thus obtained is used in the production of copper oxychloride according to the existing technology. Copper oxide after drying is a marketable product.

PRI me R 1. To 100 ml of spent pickling solution (neg.) Containing Cu12-2HgO 100 g / l; 130 g / l; Oil flow rate (25%) 300 ml / l; Pb 0.1 g / l, poured 100 ml H20 + 150 ml of NaOH solution 160 g / l; boil the solution for 90 minutes. Boiling point 99 - 101 ° С. Control distilling indicator paper, absorb NHs with a solution of HCI. The copper oxide is separated from the liquor on a Buchner funnel, the precipitate is washed to a neutral environment with distilled water. The precipitate is dried at 120-150 ° C. The output of CuO 100%.

EXAMPLE 2 A method of processing can be accomplished by using an alkali solution with a higher concentration of the order of 200 g / l and without adding water. For example, 120 ml of a 200 g / l solution of NaOH is poured into 100 ml of spent pickling solution. The mixture is heated to a boil and ammonia is distilled off. In this case, the filtrate will be much less than in the case of example 1. The final volume of alkali in example 2 is 165 ml, in example 1 is 290 ml. The concentration of NaCl and NaOH in the filtrate is much higher than in Example 1. The precipitate of CuO is 99.0% pure, and in the case of Example 1 it is 99.8%.

A comparative analysis of the processing of OTP without preliminary separation of Pb (OH) s and Sn (OH) 2 and after their separation, obtained the results summarized in the table. OTP composition is used: CuCl2 2H20 100 g / d; 130 g / l; NH3 (25%) 300 ml / l; Pb2 + 2 g / l; Sn2 + 2 g / l.

In the case of processing the OTP without preliminary separation of the Pb and Sn salts in the precipitate of CuO, there is 0.77% Pb, and in the case of the preliminary separation in CuO, there is 0.075% of Pb.

The technical and economic advantage of the proposed method is that there is no waste during the processing; The PRP is divided completely into its constituent components; in the filtrate there are no Cu2 and NH4CI ions; the filtrate (solution of NaCl and NaOH) is used in the production of NaOH and CI2. The output of CuO 100%, purity 99.8%. Copper oxide is used in the production of copper oxide.

Claims (1)

Invention Formula A method of processing spent copper ammonium pickling solution, which includes the introduction of alkali to the solution to precipitate copper as its oxide, the recovery of ammonia and the separation of copper oxide sediment by filtering, in order to increase the purity of the copper oxide before adding the alkali to the solution ammonia is used to dissolve the precipitate from copper compounds and the precipitate of lead and tin compounds is removed from it by filtration, and the alkali is introduced in an amount of 80-125 g / l and ammonia is recovered until it is completely removed at the boiling point of the solution.