Common major oxidizing minerals are:
Malachite CuCO 3 ·Cu(OH) 2 , containing 57.5% of Cu, has good floatability, can be directly floated by fatty acid or sodium hydroxyphosphate, or can be floated with high-grade xanthate after vulcanization with sodium sulfide. When vulcanized, ammonium sulfate is added to promote its vulcanization.
Blue Copper Mine 2CuCO 3 · Cu (OH) 2 , containing Cu69.2%, which is similar to malachite and floatability, but flotation time of vulcanization, the curing time is longer.
Cu 2 O in the copper ore, containing 88.8% of Cu, is similar to the malachite.
The silicon malachite CuSiO 3 · 2H 2 O, containing Cu 3.62%, has a strong hydrophilic surface and is not easily vulcanized by a vulcanizing agent such as sodium sulfide. When PH=4, hydrogen sulfide, sodium sulfide and ammonium sulfate can be added, which can be partially vulcanized and then floated with advanced xanthate. Chrysocolla can be harvested with fatty acids, but the flotation properties are similar to those of gangue, which is difficult to sort. In recent years, some effects have been obtained with hydroxamic acid and some other special collectors .
The methods of application in production are:
1. Vulcanization flotation
This is one of the simplest and most common methods of treating copper oxide ore such as malachite and azurite. The vulcanization of the chrysocolla and the cuprite is difficult, so when the copper oxide minerals in the ore are mainly malachite and aramid, the flotation flotation method can be used.
The amount of sodium sulfide during vulcanization can reach 1~2kg/t. Since the film formed by vulcanization is not stable, it is easily detached by strong stirring, and sodium sulfide itself is easily oxidized, so it should be added in portions when using sodium sulfide. In addition, malachite and alumite are vulcanized at a faster rate. Therefore, in practice, vulcanization is often carried out without prior agitation, and the vulcanizing agent is directly added to the first flotation tank, and the amount of the vulcanizing agent is adjusted according to the state of the foam. Significant inhibition of the first tank and good mineralized foam in the second tank. When there is more mud in the slime, a dispersant must be added, usually water glass.
Usually collector with butyl xanthate, butyl xanthate or mixed with a black powder application, PH value of floating mineral slurry is typically maintained at about 9. If the amount of sodium sulfide is small enough to maintain the pH value, some lime may be added during the grinding operation. Adding an appropriate amount of ammonium sulfate, aluminum sulfate or sulfuric acid during vulcanization contributes to the vulcanization of minerals and improves the flotation index.
2. Fatty acid flotation
Fatty acids and their soap collectors can well float malachite and blue copper. This method can be considered when the gangue mineral non-carbonate copper oxide ore is considered. This flotation method loses selectivity when the ore contains carbonate minerals or contains iron and manganese oxidized minerals that can be floated.
There are mixed applications of vulcanization and fatty acid methods in foreign countries. Sodium sulfide and xanthate are used to float copper sulfide and a portion of copper oxide, and then the residual copper oxide is floated with fatty acid. For example, in the Enchangjia plant in Zambia, the treated ore contains 4.7% copper, 500g/t lime (pH 9-9.5), 10g/t cresol (foaming agent) and 60g/t xanthate. Elevant yellow medicine 35g / t, sodium sulfide 1kg / t, palmitic acid 40g / t, fuel oil 75g / t, flotation concentrate containing copper 50% ~ 55%.
3. Acid leaching - precipitation - flotation
When the above two methods are not used to obtain satisfactory results, a more complicated method should be considered. Sometimes copper compounds are tightly combined with loose earthy or powdered iron hydroxide, manganese hydroxide, aluminosilicate, etc. to form so-called "bonded copper" (most copper oxide minerals can be dissolved in 1 in sulfuric acid solution). Copper oxide insoluble in 5% sulfuric acid, excluding copper in insoluble copper sulfide minerals, referred to as "bonded copper" or "combined copper". This part of copper is basically unable to use ordinary flotation Method of recycling. When the ore contains chrysocolla, cuprite and copper, the water-smelting-flotation method is easy to obtain satisfactory results.
After the ore is ground, it is first leached with a dilute solution of 0.5% to 3% sulfuric acid. (For some ore that is difficult to leach, it needs to be heated to 45-70 ° C when leaching), and the oxidized mineral of copper dissolves to form copper sulfate, and then replaced with iron, the copper ions are reduced to copper metal precipitated
CuCO 3 ·Cu(OH) 2 +2H 2 SO 4 =2CuSO 4 +CO 2 +H 2 O
CuSiO 3 ·nH 2 O+H 2 SO 4 =CuSO 4 +H 2 SiO 3 +nH 2 O
CuSO 4 +Fe=FeSO 4 +Cu↓
Finally, the copper metal and the copper sulfide mineral not dissolved in sulfuric acid are floated together to obtain a copper concentrate. This method has been applied in practice. However, when the ore contains a large amount of alkaline gangue, the acid consumption is too large and the cost is too high, and this method is not applicable. In practice, ammonia leaching or flotation-water smelting can also be considered! [next]
4. Ammonia leaching
A solution of ammonia and ammonium carbonate was used as a solvent, and leached for 2.5 hours at a temperature of 150 ° C, a pressure of about 1925175 to 2026500 Pa, and a solution concentration of 12.5%. The effects of ammonia and ammonium carbonate solutions on copper carbonates and oxides are as follows:
CuCO 3 ·Cu(OH) 2 +6NH 4 OH+(NH 4 ) 2 CO 3 =2Cu(NH 3 ) 4 CO 3 +8H 2 O
CuO+2NH 4 OH+(NH 4 ) 2 CO 3 =Cu(NH 3 ) 4 CO 3 +3H 2 O
The leached mother liquor is steam distilled at 90 ° C to separate ammonia and carbon dioxide and collect in water for recycling. Copper is a black copper oxide powder that precipitates out of solution.
5. Segregation - flotation
The essence of this approach is that the appropriate particle size of the ore, coal powder (a reducing agent), brine (chlorinating agent) certain mixing ratio, heated to 700 ~ 800 ℃, chloride (CuCl 2) generating the copper from the ore It is volatilized and then reduced to metallic copper by carbon and enriched on the surface of carbon particles. It is then separated from the gangue by flotation. The process index obtained by this method is good, but the cost is very high, and it is still in the stage of industrial experiment.
6. Flotation - water smelting
Some oxidized or mixed ores contain a portion of the optional copper oxide. It can be recycled first by flotation. Then send the tailings or the middle mine to the water and metallurgy. The acid method of water smelting is still determined by the composition of gangue in the ore. The gangue is mainly an acid method when the silicate is used, and the alkali method is used when the gangue is mainly a carbonate.
At present, the beneficiation of foreign copper oxide ore is basically carried out by two processes, a vulcanization flotation method and an acid leaching-precipitation-flotation method.
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