1. Characteristics of Cu, Zn isolated
When dealing with complex sulfide ore, copper-zinc flotation separation is still a very difficult problem because:
(1) Copper-zinc minerals are densely symbiotic. The symbiotic relationship between copper-zinc minerals is related to the genesis of the deposit. For example, high-temperature deposits, chalcopyrite is often present in fine-grained state in sphalerite. The disseminated chalcopyrite particles are often below 5 μm. Like this dense symbiotic ore. It is very difficult to grind the monomer to dissociate, and even if the monomer dissociation is reached, it is difficult to separate.
(2) Sphalerite is activated by copper ions. The sphalerite activated by copper ions is similar in floatability to copper minerals. When there is copper ions in the slurry, the sphalerite will adsorb copper ions. Other heavy metal ions such as Hg +, Ag +, Pb 2+, and the like, also can activate sphalerite.
2. Copper and zinc separation method
There are two major types of copper and zinc separation methods used in production practice: floating copper and zinc, floating zinc and copper. The main methods are listed in Table 1.
(1) Cyanide + zinc sulfate method. This is the most versatile method over the years and is characterized by the ability to remove copper activated membranes from the surface of sphalerite, which is more effective in suppressing sphalerite. It is also an important method for the separation of copper and zinc in complex sulfide ore. Since chalcopyrite is also inhibited by cyanide, the amount of cyanide should be carefully controlled when using this method.
(2) Sulfite method. There are many agents used in this method. Anyone who uses Na 2 SO 3 , Na 2 S 2 O 3 , NaHSO 3 , H 2 SO 3 and SO 2 gas, or they can be mixed with ZnSO 4 can be included. This method. The sulfite method is characterized by a small inhibitory effect on copper minerals. Its order of inhibition of sulfide ore is:
Unactivated sphalerite> pyrite> galena> chalcopyrite
In order to enhance the inhibitory effect, sulfite is often used in combination with other inhibitors, the most common being ZnSO 4 , the effect of Na 2 SO 3 in combination with ZnSO 4 is shown in Figure 1. The sphalerite activated by copper ions has a poor inhibitory effect with Na 2 SO 3 alone, and can be used in combination with ZnSO 4 to enhance the inhibitory effect.
Table 1 The main method of copper and zinc separation
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Floating copper and zinc | Floating zinc and copper |
(1) Chloride + zinc sulfate method (2) Carbonate method (3) Zinc sulfate + sodium sulfide method | (4) Warming flotation method (5) Red blood salt method (6) Hot water flotation method |
Fig.1 Effect of Na 2 SO 3 +ZnSO 4 on floatation of copper-ion activated artificial sphalerite
1-Na 2 SO 3 0.2mol/L
2-Na 2 SO 3 0.2mol/L
ZnSO 4 0.1mol/L[next]
In addition, sodium sulfite can also be used in combination with lime, sodium sulfide, zinc sulfate and the like, and can replace the cyanide to suppress sphalerite, and can obtain better effects.
For example, a copper-zinc-sulfur polymetallic sulfide ore in China contains 1.42% Cu, 2.66% Zn, and S20.32% in the original ore; the secondary copper deposit has a copper ore, copper, etc., accounting for 10% of the total copper minerals~ 37%. Due to oxidation of the mineral, of clay, a large amount of soluble salts into the mineral slurry was strongly acidic (PH = 3 ~ 5), crushing water samples containing Cu 2+ 1500mg / t, Zn 2+ 1100mg / t. The separation of sphalerite and pyrite due to the presence of a large amount of Cu 2+ makes separation difficult. The preferential flotation process is adopted to suppress zinc and sulfur with lime, sodium sulfide and zinc sulfate, and copper is preferentially selected. Lime and sodium sulfide are added to the grinding process to precipitate copper ions. Obtained indicators: copper concentrate contains 18% Cu, recovery rate is 82%; zinc concentrate contains 41% Zn, and the recovery rate is 51%.
In recent years, the combination of sulfite and other inhibitors has played a significant role in the separation of complex sulfide minerals. This not only avoids the environmental pollution caused by the conventional cyanide method and the problem of dissolving precious metals, but also greatly improves the sorting index. At present, this method has been widely adopted in Japan, Canada, the United States, South Africa and other countries. According to incomplete statistics, 38% of the polymetallic sulfide ore flotation plants in China have adopted the sulfite method.
When using the sulfite method, the following points should be noted:
1 Strictly control the PH. Sulfurous acid is a strong reducing agent whose main component is HSO 3 - . Calculated by the dissociation constant, [HSO 3 - ] is the largest in the range of PH=4~7. In production practice, the most common is PH=5~6.5.
2 strictly control the dosage. When the amount of SO 2 is the largest, the activated sphalerite is strongly inhibited, but for pure sphalerite, there is a suitable amount, and the excess may cause activation. When the amount is too large, the pyrite is also slightly activated. This may be a low pH and a cleaning effect on pyrite, which is beneficial to the flotation of pyrite.
3 When SO 2 and H 2 SO 3 are used, the general xanthate is easily decomposed and consumed, so it is preferable to use a collector which is not easily decomposed, such as (propyl) ethionamide.
(3) Zinc sulfate + sodium sulfide method. The fine-grained colloidal zinc sulfide formed by the reaction of ZnSO 4 +Na 2 S absorbs the copper ions in the slurry, and the colloid is also adsorbed on the surface of the zinc blende, which is inhibited. Colloidal zinc sulfide has a strong inhibitory effect on activated sphalerite. This method can be used when the ore contains more secondary copper sulfide ore.
(4) Heating flotation method. The essence is that in the PH slurry caused by lime, the chalcopyrite is oxidized by heating, and then the sphalerite is activated by adding copper sulfate, and the collector float zinc is added.
In recent years, in order to solve the problem of Cu-Zn separation, countries have focused their attention on organic inhibitors such as dextrin, starch, baking gum and carboxymethyl cellulose, and their applications have been widely used.
Improving copper and zinc separation can be summarized into the following ways.
1 Precipitate copper ions to prevent their activation of sphalerite. An important method of precipitating copper ions is to use sodium sulfide. In the presence of copper ions, when Na 2 S and sphalerite coexist, calculations by chemical reaction equilibrium have shown that copper ions are likely to precipitate with Na 2 S before the sphalerite activation. Experiments have also shown that Na 2 S can prevent the activation of sphalerite by copper ions.
In addition to Na 2 S, an ion exchange resin can also be used to adsorb copper ions in the solution. In actual production, the ion exchange resin is added to the ball mill to prevent the copper ions from activating the sphalerite.
2 Remove copper ions adsorbed on the surface of the sphalerite. It has been found that the more effective deactivating agents are NaCH, H 2 SO 4 , H 2 SO 4 + Fe 2 (SO 4 ) 3 . H 2 SO 4 is more effective in combination with Fe 2 (SO 4 ) 3 , and the amount of acid used is only one tenth of that of H 2 SO 4 alone.
3 mixed concentrate detoxification. This is a commonly used method before separation of various mixed concentrates, after removing the collector film to facilitate separation.
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