SU1479421A1 - Method of purifying solutions from metal cyanides - Google Patents

Abstract

The invention relates to hydrometallurgy, in particular to methods for cleaning solutions and wastewater from electroplating plants. The aim of the invention is to reduce the cost of the process by reducing the consumption of reagents. Purification of solutions from cyanides and metals is carried out by treating with a precipitating reagent, for which the strong acid cation exchanger in the form of a metal is used, which is present in the solution in the form of a cyanide complex. A precipitator is introduced at a mass ratio of cyanide and cation exchanger (0.5-2.5): 100. The purification of the solutions is carried out on ion exchange filters. The method makes it possible to reduce the consumption of reagents and dispose of cyanides and metals in the form of a precipitate of simple metal cyanides.

Description

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The invention relates to hydrometallurgy, in particular to methods for cleaning solutions and wastewater from electroplating plants.

The purpose of the invention is to reduce the cost of the process by reducing the consumption of reagents.

This goal is achieved by introducing into the solution a precipitating agent in the form of a strongly acidic cation exchanger charged in the form of a metal present in the solution in the form of a cyanide complex, with a mass ratio of cyanide and cation exchanger (0.5-2.5): 100 .

The process technology is that when the electrolyte containing complex cyanides of metals and free cyanides is contacted with

a cation exchanger in the form of a metal present in the electrolyte in the form of complex cyanide, the cation exchanges in the cation exchanger for an alkali metal cation with the formation of a simple metal cyanide precipitate in the solution phase: R1Cu + Na2 (Cu (CN) 3-2RNa + Cu (CN) i + CuCN;

R7Cu + 2NaCN 2RNa + Cu (CN) g; R2Zn + Naa (Zn (CN).,) -2RNa + 2ZN (CN) 3;

2RAg + Nai (Ag (CN) 3) -J 2RNa + 3AgCN.

Since the exchange of cations between the cation exchanger and the solution occurs equivalently, the solution is not contaminated with excess cations and anions;

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The metal cations entering the solution form insoluble salts with c-cyanides, which are easily separated from

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Anion exchanger AN-221 is placed in a column with a capacity of 300 ml and 400 ml of 10% sodium hydroxide solution are passed through at a rate of 200 ml / h. Get solution containing 5 mg / l: Na 11090, Cu 1700, Zn 125, CN 2500.

Example 2 (with a cation exchanger in the form of zinc ions and a solution containing an ion exchanger due to the different dispersion of the ion exchanger and sediment.

The metal cyanide precipitate can be dissolved in an excess of cyanide and returned to the electroplating process.

The cation exchanger is treated with the metal salt — JQ Xim zinc cyanide and sodium cyanide). la (copper, zinc, silver, etc.) and the ratio of cyanide and cation exchanger 2.5: return to a form suitable for removing cyanides from solution. The consumption of a metal salt does not exceed the stoichiometric amount needed to transfer simple and complex cyanides from solution to precipitate.

The purified solution is separated from the precipitate by filtration and desalted by a known ion exchange method, for example, by sequential filtration through a cation exchanger in the hydrogen form and an anion exchanger in the hydroxyl form "

At the first stage of purification - precipitation of simple metal cyanides - containing, mg / l: Na 50, Zn 1.5; The removal of anions and cations of CN 20 and 2200 mg of Zn (CN) precipitate, which is HS 90-95%, is going on, and the load on ion-exchange filters of the electrolyte is reduced by the same amount.

A new stage of purification, therefore, Ionite is again loaded into ion-exchangers, the flow rate of a 200 ml capacity column is reduced by the same amount, the flow-generating substances are acid, and 0.5 L of a 10% aqueous solution of sulfalochate is bent.

Example t (by a known method). Into a column with a capacity of 200 ml, 100 g of granules of compressed copper icade are charged and 1 l of a solution is passed, containing, mg / l: Na 490, Cu 500; Zn 50; CN 1000, at a rate of 100 ml / h. Get 1 liter of solution containing mg / l: Na 490; C 680; Zn 40 IU and Av in hydroxyl form. Ra- 50; CN 1000, the target is passed in succession. 200 ml each are swollen up to the column with cation exchanger and the CB-4 decons in hydrogen form and with anion exchanger. Get 1 liter of solution

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Into a 200 ml ion-exchange column load 100 ml (40 g) of 15 К KU-2 ion-ion charged in the form of zinc ions. 1 l of a solution containing, mg / l: Na 490; Zn 560; CN 1000, with a speed of 1 l / h.

Then the ion exchanger is discharged from the column and the precipitate is separated on a sieve using a purified solution to wash the ion exchanger. The precipitate is separated from the solution by filtration. Get 1 liter of solution

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This zinc at a rate of 1 l / h, then 400 ml of distilled water, and is used in the next solution cleaning cycle.

The purified solution is subjected to final delamination, for which two columns with a capacity of 200 ml are loaded with 4 ml of KU-2 ion exchangers in hydrogen forAN-221 in the form of a free base and 1 g of ground bentonite.

The mixture is loaded into a 600 ml ion exchange column and the solution to be purified is passed at a rate of 800 ml / h. The resulting solution contains, mg / l; Na 30; Si 1.5; Zn 0.2; CN traces. Pass through the column

l of water from bottom to top at a rate of l / h and separated smetanny layer of ion exchangers.

The cation exchanger KB-4 is placed in a 300 ml capacity column and 40 ml of a 5% hydrochloric acid solution are passed at a rate of 200 ml / h. The resulting solution contains, mg / l: Na 1120, C1 5000

Anion exchanger AN-221 is placed in a column with a capacity of 300 ml and 400 ml of 10% sodium hydroxide solution are passed through at a rate of 200 ml / h. Get a solution containing, mg / l: Na 11090, Cu 1700, Zn 125, CN 2500.

Example 2 (with a cation exchanger in the form of zinc ions and a solution containing zinc cyanide and sodium cyanide). The ratio of cyanide and cation exchanger 2,5:

containing, mg / l: Na 50, Zn 1,5; CN 20 and 2200 mg of Zn (CN) sludge, which is used to prepare the electrolyte.

J100.

100 ml (40 g) of KU-2 ion exchanger charged in the form of zinc ions are loaded into a 200 ml ion-exchange column. 1 l of a solution containing, mg / l: Na 490; Zn 560; CN 1000, with a speed of 1 l / h.

Then the ion exchanger is discharged from the column and the precipitate is separated on a sieve using a purified solution to wash the ion exchanger. The precipitate is separated from the solution by filtration. Get 1 liter of solution

The ion exchanger is again loaded onto a 200 ml ion-exchange column with a volume of 0.5 l of a 10% aqueous solution of sulpha-

IU and AB in hydroxyl form. The solution is passed in succession.

This zinc at a rate of 1 l / h, then 400 ml of distilled water and is used in the next solution cleaning cycle.

The purified solution is subjected to final delamination, for which two columns with a capacity of 200 ml are loaded with 4 ml of KU-2 ion exchangers in hydrogen form.

containing, mg / l: Na 5,0; Zn absence, CN absence.

15 ml of 5% sulfuric acid and then 20 ml of distilled water are passed through a column with KU-2 ion exchanger at a rate of 20 ml / h. Get 15 ml of the eluate content, mg / l: Na 2700; Zn 80; SO 44100 and 15 ml of wash water content, mg / l: Na 300; Zn 20; S04 4900.

Through a column with ion-exchanger AB-47, 20 ml of 10% sodium hydroxide solution are passed at a rate of 20 ml / h, then 20 ml of distilled water. Get 20 ml of the eluate content, Ng / l: Na 9000, CN 900, 20 ml washing

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Noah water content, mg / l: Na 1000, CN 100.

Ionites are used in the next solution cleaning cycle.

ExampleZ (with a cation exchanger in the form of copper ions and a solution containing cyanide and sodium cyanide). The ratio of cyanide and cation exchanger 2.5: 100.

A 200 ml ion exchange column with a capacity of 200 ml is charged with 100 ml (40 g) of KU-2 ion exchanger charged in the form of copper ions. Through the column from the bottom up pass 1 l of a solution containing, mg / l: Na 490; Si 550; CN 1000, at a rate of 25 ml / min. Then the ion exchanger is discharged from the column, the precipitate is separated on a sieve using a purified solution for washing the ionite. The precipitate is separated from the solution by filtration. Receive 1 l of a solution containing, mg / l Na 15; C 1.0; CN 15 and 2200 mg of precipitate Cu (CN) 2, which is used to prepare the electrolyte.

The ion exchanger is again loaded onto a 200 ml ion exchange column, 0.5 l of a 1.0% zinc sulphate solution, 400 ml of distilled water is passed in and used in the next solution cleaning cycle „

Finishing desalting of the solution is carried out analogously to example 2.

PRI me R 4 (with cation exchanger in the form of silver ions and a solution containing silver cyanide). The ratio of cyanide.and cation exchanger 2,0: 100.

A 200 ml ion-exchange column is charged with 100 ml (50 g) of a KU-2 ion exchanger charged in the form of silver ions. One liter of a solution containing mg / l: -Na 660, Ag 1038, CN 1000 is passed through the column from bottom to top at a rate of 25 ml / min. Then the ion exchanger is discharged from the column, the precipitate is separated on a sieve, using a purified solution for washing the ion exchanger. The precipitate is separated from a solution containing, mg / l: Na 20, Ag 0.5; CN 10, and 5050 mg of AgCN precipitate, which is used to prepare the electrolyte. The ion exchanger is loaded again into a column with a capacity of 200 ml and 0.5 l of a 1.0% silver nitrate solution is passed through, then 400 ml of distilled water is passed through and used in the next solution cleaning cycle.

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Finishing desalting of the solution is carried out analogously to example 2.

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Examples 5-8. Confirmation of the substantiation of the mass ratio of cyanide and cation exchanger.

Example 5 (the ratio of cyanide and cation exchanger 0.3: 100). Similar to example 2, the amount of KU-2 ion exchanger charged in the form of zinc ions, {300 ml (320 g), column volume 1200 ml.

The content in the solution to be purified after treatment with KU-2 ion exchanger in zinc form, mg / l: Na 25, Zn 2.0, CN 10.

PRI me R 6 (ratio. Cyanide and cation exchanger 0.5: 100). Similar to example 2; the amount of KU-2 ion exchanger charged in the form of zinc ions, 500 ml (200 g), column volume 800 ml.

The content in the purified solution-g after treatment with an ion exchange resin KU-2 in zinc form, mg / l: Na 25, Zn 2.0, CN 10

Example (ratio of cyanide and cation exchanger 3.0: 100). As in example 2, the amount of KU-2 ion exchanger charged in the form of zinc ions, 83 ml (33 g), column volume 120 ml.

Content in the purified solution after treatment with KU-2 ion exchanger in zinc form, mg / l: Na 70, Zn 2.5, -f CN 60 „

Thus, the proposed method allows to reduce the consumption of reagents (acids and alkalis), reduce the cost of the purification process, and dispose of cyanides and metals in the form of a precipitate of simple metal cyanides.

The significance of the ratio of cyanide and cation exchanger in the form of a metal that is present in the solution being purified as a cyanide complex is confirmed by the fact that when the ratio decreases below 0.25: 100, i.e. by increasing the consumption of ion exchanger, there is no increase in the depth of the solution cleaning, and with an increase of more than 2.5: 100, the depth of cleaning of the solution decreases sharply.

The method makes it possible to simplify the process (exclude the electrolysis stage) by reducing the consumption of caustic soda for regeneration and electricity for the destruction of cyanides, to utilize cyanides and metals. In this case, the acid consumption is reduced by 25 times, the alkali consumption for solution cleaning is reduced by 20 times. Cyanides and metals are utilized as a precipitate of simple metal cyanides, which makes it possible to use them in electroplating.

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Claims (1)

The invention claims to make the process cheaper by the consumption of reagents, as The method of purification of solutions from cyanide precipitator uses strongly acidic ions and metals by introducing reagent-. cation exchanger in the form of a metal, the precipitator is present, followed by treatment in solution in the form of cyanide on ion exchange filters, about tl and -complex, with a mass ratio due to the fact that, with the aim of cyanide and cation exchanger (0.5-2.5): 100.