The copper or copper oxide-containing waste, leaching by ammonium carbonate solution under blast conditions, copper ammonium carbonate complex to form copper into solution, after addition of impurities leaching solution purification, to obtain a pressurized hydrogen reduction of copper; or purification The liquid is boiled to precipitate copper as an oxide from the ammonium carbonate copper solution. The precipitated copper oxide is solid-reduced with copper to form a copper powder or a copper block. The copper oxide can also be dissolved in sulfuric acid, and then the cathode pure copper can be obtained by electrolysis using an insoluble anode.
Regeneration hydrometallurgical copper extraction process mainly, lead and tin in addition to purification, recovery of copper and other metals from the process liquid composition of the tin.
(1) Leaching
The leaching is carried out in a stirrer or a tower leacher. The stirrer requires the material to be crushed to below 6.4 mm. The pulverizable material is cut into strips and then circulated into the tower leacher. Copper-containing materials need to be processed prior to leaching to remove organic contamination such as oil, wax and insulating plastics.
The leaching is usually carried out under normal pressure, and the temperature is controlled between 300 and 324 K. When leaching, air or oxygen is sprayed from the bottom of the leaching device.
When leaching, add a copper-containing material and an ammonium carbonate solution to the leacher in a specified amount, then heat it to the reaction temperature, and blast air or oxygen, metal copper or copper-containing oxide.
CuO+(NH 4 ) 2 CO 3 +2NH 3 =Cu(NH 3 ) 4 CO 3 +H 2 O
2Cu+(NH4) 2 CO 3 +2NH 3 +1/2O 2 =Cu 2 (NH 3 ) 4 CO 3 +H 2 O
Cu+Cu(NH 3 ) 4 CO 3 =Cu 2 (NH 3 ) 4 CO 3
Cu 2 (NH 3 ) 4 CO 3 +1/2O 2 +(NH 4 ) 2 CO 3 +2NH 3 =2Cu(NH 3 ) 4 CO 3 +H 2 O
The leaching process is carried out until the solution contains copper at 140-160 g/L. At this time, 2/3 of the solution is ammonium arsenide and 1/3 is copper copper.
The most common impurities in copper are Fe, Zn, Pb, Ni and Sn. When leaching, Zn and Ni form water-soluble complexes and dissolve together with copper. Fe, Pb and Sn have limited solubility in ammonium carbonate solution, most of them. Leave in the leaching residue.
(2) Purification of lead and tin
Before the leachate is further processed, the lead is removed first, and the nickel and zinc are removed in the next stage. Clarified leachate first batch, followed by addition of strontium sulfate i.e. SrSO 4 to remove lead, and tin. Barium sulfate is a ground natural lapis lazuli that adsorbs heavy metal ions such as lead and tin. Practice has proved that lapis lazuli is an effective lead removal and tin agent. The purification rate of lead can reach 96%, and the tin can reach 50%. Because it is a natural product and the price is cheap, it is used by industrial production.
The addition amount of celestite is added in a mass ratio of 1:9, that is, 1 part of the solution needs to be added with 9 parts of lapis lazuli. At this time, lead and tin are best. The temperature of the solution is generally between 300 and 333 K. Appropriate increase and thinning of the celestite grain size can increase the lead and tin speed.
When the lead and tin contents in the solution meet the requirements, the solution is subjected to two stages of filtration to remove solid matter.
(3) Recovery of metal copper from leachate
To recover metal copper from the leachate, the following methods are available.
1 Directly reducing the leaching solution with hydrogen in an autoclave Under pressure, when hydrogen is directly introduced into a solution of copper carbonate, the following reduction occurs.
Cu(NH 3 ) 4 CO 3 +H 2 =Cu+(NH 4 ) 2 CO 3 +2NH 3
Cu 2 (NH 3 ) 4 CO 3 +H 2 =2Cu+(NH 4 ) 2 CO 3 +2NH 3
The reaction product is fine powdered copper, ammonium carbonate and ammonia. The copper powder is washed and sintered in a hydrogen stream, and sieved to obtain various specifications of products, ammonium carbonate and ammonia are recovered and circulated in the leaching circuit.
The reduced solution contains zinc, nickel, ammonia, ammonium sulfate and residual copper, wherein nickel and zinc impurities are enriched by the cycle after reduction, and a simple method for recovering nickel and zinc from the reduced liquid is to remove ammonia by distillation. And ammonium carbonate, and recovered in the gaseous state, returning to the stage of leaching; and zinc and nickel are precipitated in the form of alkaline carbonate in preference to copper, recovered as valuable by-products, and the residue obtained after distillation is filtered. Return to the leaching stage.
2 Solid state reduction method for extracting copper metal This method firstly boils the solution to precipitate copper in the ammonia carbonate solution in the form of oxide and alkaline carbonate, and then reduces the precipitate with hydrogen to obtain metallic copper.
The sinking of copper is divided into two states, first Cu 2 O precipitation, followed by CuO. If zinc or nickel impurities are present in the solution, it also precipitates with copper, making it difficult to carry out the next solid reduction to obtain metallic copper. Therefore, the solid reduction method is only suitable for the treatment of copper materials containing no zinc and nickel.
3 Insoluble anode electrolysis to obtain metallic copper Whether it is alkaline copper carbonate or copper oxide, it can be quickly dissolved in sulfuric acid at room temperature. Therefore, the precipitate obtained by boiling the ammonium carbonate copper solution is dissolved in sulfuric acid, and then added to the electrolytic bath for electrolysis with insoluble cation, whereby copper having a purity of 99.9% can be obtained.
In the case of insoluble anodic electrolysis, the accountants of zinc, nickel and iron in the electrolyte are not limited, and therefore, the method is suitable for treating copper materials containing zinc and nickel.
In summary, when the copper material is treated by the ammonium carbonate complex method, the leaching reaction is an exothermic reaction, and the main leaching agent ammonium carbonate and ammonia are recycled, and the whole process requires only a small amount of power, air, ammonia and chemicals, so It has economic value and does not pollute the environment and water quality.
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