CS203345B1 - Method for the separation of copper and zinc from common solutions - Google Patents

Description

The invention relates to a process for separating copper and zinc from common solutions.

Currently, several methods are used for the separation of copper and zinc, the most common being extraction, ion exchange separation, and cementation of copper from solution by iron. However, the application of these methods presents some technical and economic problems.

The separation of copper and zinc by the extraction method requires the use of costly equipment. The extraction agents required are expensive and technically difficult to manufacture. The desired extraction and reextraction process requires acidity 1 to be adjusted to the concentration of both the feed and circulation solutions, leading to the loss of some acid and necessitating the disposal of a certain volume of wastewater.

Separation at ion exchangers is also costly due to the high cost of changing ions and the relatively low selectivity with respect to individual ions. To date, ion exchangers have been used in hydrometallurgy to obtain more precious metals, where their cost is much higher than the reagents used, and / or are used in the removal of some substances from wastewater, where the concentration of the components is already so low that no other methods can be used. .

Cementation of copper from iron solution is still used for simplicity of technological equipment, low energy consumption and chemicals. Iron cement is used as a cementing agent and is irreversibly consumed. During cementation, copper ions are replaced by dissolved iron ions, and copper falls out of solution in metallic form.

The process is not suitable for separating copper from zinc, as after zincing the zinc remains in solution next to iron. Obtaining zinc from such a solution is difficult and requires prior iron removal from the solution.

In practice, zinc is no longer recovered from the solution after cemetation of copper with iron and the solution must generally be disposed of by neutralization with lime, which precipitates both iron and other cations, more electropositive than calcium.

The sludge separates from the solution and is difficult to deposit. Also, after separation of the sludge, the filtrate usually does not meet the conditions for waste water discharge.

The method of separating copper and zinc from the common solutions according to the invention essentially eliminates the drawbacks of the known processes. It is based on the fact that the solution containing copper and zinc is separated by metallic zinc in solid form and after separation the solution is treated with oxalic acid and the reaction product is separated. It is preferred that the solution is treated with oxalic acid in a solid state. Furthermore, it is desirable if the liquid fraction is returned to the process cycle after separation of the reaction product.

Thus, copper is precipitated from the solution containing copper and zinc first by cementing with zinc in metallic form. After separation of the cementation copper, a solution is formed which contains practically only. zinc cations. These are precipitated from the solution with oxalic acid to form a solution containing only zinc cations. These are precipitated from the solution by oxalic acid and an insoluble precipitate of zinc oxalate is formed in the acid, releasing the mineral acid to which the zinc was bound. Both reactions proceed almost quantitatively, irrespective of the initial copper / zinc ratio and solution acidity. Even in the presence of a relatively large amount of free mineral acid, there is no disturbance of the reactions, which is in some cases a considerable technical and economical advantage, since the acidic solution after copper and zinc deposition can be returned to the initial process practically without concentration change. A further advantage of the process is that no further cations are introduced into the starting solution and the zinc used for cementation is recovered in a well-usable form of zinc oxalate.

If other ions more electropositive than zinc are present in the starting solution, they precipitate together with copper, which is not the case in most operating cases. defect, since cementation copper is normally refined by known metallurgical processes. Valuable cations can be obtained in a useful form by refining. With this in mind, it can be advantageously used in some operating cases

cementation and zinc waste containing metals Al Si Cu Zn Mn CD Mg —3 —3 —3 1 —1 - 0 —3 Zinc oxalate: Fe Al Sl Cu Zn Mn CD Mg —3 - - —3 1 —2 -. —3 Numbers in the table ! are advice kon-

% by weight.

Example 2

Ž pickling bath containing: 40 g / l of copper; 13.6 g / l zinc; pH 2 was copper vycemento-

granulated zinc. Solution after Al Si Cu Zn Mn CD Mg -. —2 —2 1 0 - - —3 Zinc oxalate contained: Al Si Cu Zn Mn CD Mg v_3 _ _ _2 1 - - —3

Pb W Ni Ca What electropositive 'than zinc. Such waste is readily available and in this application the impurities contained therein will pass into the cementation copper, where they are not defective and the zinc is regenerated in pure form.

Copper cementation and zinc precipitation proceed according to the equations:

Cu + 2 + z 2 = CU + Zn + ²

Zn ⁺² -j- (COOHJ2 = Zn (COOjz j-2H +)

Zinc oxalate can be easily converted either to basic zinc carbonate or to zinc oxide.

The invention is illustrated in more detail in the following examples.

He did

Operationally solution Zinc - Copper _content:; ,

8.7 g / l copper;

g / l of zinc;

mg / l iron;

The pH of the copper was cemented with granulated zinc.

The cementaei solution contained:

0.1 g / l copper and.

114 g / l zinc.

After filtering out the copper, it was precipitated from the solution by acid, oxalic zinc. The zinc filtering solution contained:

0.1 g / l of copper g / l of zinc

200 g / l of free sulfuric acid.

The obtained copper contained according to spectral semi-quantitative analysis:

Pb W Ni Ca Co

The Pb W Ni Ca Co - - - 3 - 3 mentation contained 0.1 µg / l copper and 78 g / l zinc. After the copper was filtered off, zinc oxalic acid was precipitated from the solution. The zinc filtering solution contained: 0.12 g / l of copper, 2.38 g / l of zinc and about 120 g / l of free sulfuric acid.

The obtained copper contained according to spectral semiquantitative analysis:

Pb W .Ni Ca Co

The process of the invention is suitable for separating copper and zinc from any solution of their salts. Such salts are formed in particular in the hydrochemical treatment of ores, in the purification of waste waters by means of sorbents in the regeneration of sorbents, in pickling plants, from cation exchange eluates, in the disposal or regeneration of electrolytes and the like.

Claims (3)

A process for separating copper and zinc from common solutions, characterized in that the solution containing copper and zinc is separated by metallic zinc copper, the solution after separation is treated with oxalic acid and the reaction product is separated. 2. A method according to claim 1, characterized by OF THE INVENTION in that the solution is treated with oxalic acid in a solid state. 3. The process of claim 1 wherein the liquid fraction is returned to the working cycles after separation of the reaction product.