A copper oxide ore minerals Crystal Structure
Copper oxides mainly include cupro ore (Cu20) and beryllium copper (CuO). Copper sulfate, carbonate and silicate minerals are mainly malachite (Cu2 CO3(OH)2), azurite (Cu3(CO3)2(OH)3), and chrysocolla ((Cu, Al) 2H2Si2O5(OH)4·nNH2O), water cholesteric (Cu4SO4(OH)6), and chlorite (Cu2CI(OH)3). The crystal structure of minerals is diverse, and the difference in structure leads to the difference in mineral properties. The deeper research on the crystal structure of copper oxide minerals is beneficial to the selection of more efficient recovery methods.
Malachite is the most important copper oxide mineral with a monoclinic structure. The lattice constants of common crystal forms are a=95.02nm, b=119.74nm, c=32.40nm and β=98.75° (Z=4). The space group is P21/α, which is a combination of octahedral CuO6 through a carbonate group. There are two different structures of copper in the crystal, Cu1 and Cu2, respectively. The ratio is 1:1. According to the JahnTeller efect, the two copper atoms are surrounded by four oxygen atoms in the axial arrangement. Ring structure.
2 copper oxide ore flotation theory
The vulcanization flotation method has been the main method for treating copper oxide ore and mixed copper ore, mainly including direct vulcanization flotation method and hydrothermal vulcanization flotation method.
The direct flotation method is the earliest application of sodium sulfide activation, directly using collector flotation, including fatty acid flotation, amine flotation, neutral oil emulsion flotation and chelating agent flotation Etc., Jiang Dengbang studied the mechanism of action of xanthate and hydroxamic acid on the surface of copper oxide ore by density functional theory. The results show that the reason why copper oxide ore is difficult to be directly captured by xanthate is that the adsorption of xanthate and copper oxide ore is weak and the copper oxide ore has strong hydrophilicity. The hydroxamic acid is aerobic, the chelating structure of the O-5 element ring, and the adsorption of the surface of the copper oxide ore mineral is far greater than the action of the xanthate and copper oxide ore, and can be used as a highly efficient collector of copper oxide ore.
The copper oxide mineral is first vulcanized with a vulcanizing agent, and then floated with a collector is called direct vulcanization flotation. At present, the vulcanizing agents are sodium sulfide, sodium hydrosulfide, hydrogen sulfide, calcium sulfide and ammonium sulfide, and sodium sulfide is more commonly used. Guo et al. studied the activation center of the surface of oxidized minerals in sulfide flotation. It is believed that the MeS unit cell formed during the vulcanization process is a bridge for the adsorption of collectors on the surface of oxidized minerals.
Sun Heyun studied surface complex vulcanization of synthetic basic copper carbonate and copper oxide based on the surface matching theory with ethyl xanthate and butyl xanthate as sulfur sources. The results show that it is a feasible method to surface vulcanize solid copper oxide and basic copper carbonate with xanthate as sulfur source. The key factor affecting the vulcanization effect is the amount of xanthate and its carbon chain length. In addition, the calcination temperature and time also have an effect on this. The surface of the surface-vulcanized copper oxide and the basic copper carbonate form a variety of valence sulfides, which change the adsorption properties of the solid surface to the xanthate, the wettability of the surface and the charging properties. It has been deduced that the surface of the CuS is moderately oxidized to help improve its hydrophobicity.
Liu Cheng studied the vulcanization mechanism of typical copper oxide ore malachite. It was pointed out that when sodium sulfide was added to the solution, a hydrophobic film was formed on the surface of the malachite mineral, which significantly changed the potential of the mineral surface and allowed the mineral to float, but was scanned by electron microscopy. (SEM) It was found that the formed vulcanized film was unstable.
The hydrothermal vulcanization flotation process is actually a development of direct vulcanization flotation. It strengthens the pre-position of ore on the basis of direct flotation.
- Pre-vulcanization process and flotation in warm water. The mechanism of action is that the slurry is mixed with sulphur powder (adding a small amount of liquid ammonia as an additive), and at a temperature of 180 ° C and a pressure of 0.6 to 1.0 MPa, elemental sulfur undergoes disproportionation to form S2- and SO.
A vulcanization reaction occurs on the surface of the copper oxide particles or inside the entire particle to form a new and hydrophobic "artificial copper sulfide".
Study on enhanced sulfuration flotation of 3 copper oxide ore and amine salts
Zhang Wenbin and Xu Xiaojun et al. studied the pure copper minerals of malachite and chrysocolla, and studied the activation mechanism of copper oxide ore by using inorganic ammonium salts such as ammonium sulfate and organic ammonium salts such as ethylenediamine phosphate . In recent years, many researchers have conducted extensive research on ammonium and amine salts as intensified vulcanization activators for oxidized ore.
Liu Cheng used ammonium sulfate as an activator to study the vulcanization mechanism of malachite. It was pointed out that the addition of ammonium sulfate can stabilize the vulcanized film on the surface of malachite and it is not easy to fall off. Infrared spectroscopy showed that both ethyl xanthate and butyl xanthate could be chemisorbed on the surface of malachite minerals. According to the infrared spectrum of malachite minerals in CO
The disappearance and the change of sodium sulfide concentration before and after the reaction can confirm the adsorption of sodium sulfide on the surface of malachite. In addition, the theoretical calculations show that when the Cu-O bond in the malachite is changed to the Cu-S bond, the fraction of the covalent bond is increased, the activity of the mineral-water interaction is reduced, and the floatability of the mineral is changed, which is related to the flotation result. Consistent.
Xing Chunyan et al. studied the effect of ammonium sulfate on the sulfide flotation of copper oxide ore, and used dynamic tracking to measure the change of S2-concentration in the slurry. The results show that in the sulfide ore flotation of copper oxide ore, in addition to the activation of copper oxide ore and the formation of copper sulfide film, the complex oxidation reaction occurs at the same time. The oxidation process is closely related to the pH value of the system. Ammonium sulfate cleans the mineral surface during the copper oxide ore flotation flotation process, which improves the activity of the mineral surface, which not only promotes the vulcanization process, but also accelerates the oxidation of S2-, which is the promotion of copper oxide vulcanization by ammonium sulfate. The important reason for choosing.
Liu Dianwen et al. studied the effect of ammonium salts on the flotation index of copper oxide ore during the flotation flotation process. The results show that the inorganic ammonium salt has an activation effect on the sulfide flotation of copper oxide ore, mainly because of NH.
It is easy to form a copper-ammonium complex with copper ions and adsorb on the surface of the mineral, which is more likely to cause the adsorption of sulfur ions.
Hu Benfu et al. studied the strengthening mechanism of fine-grained malachite vulcanization flotation with ammonium and amine salts, and pointed out that ammonium sulfate, ammonium chloride, ethylenediamine and DMTD can significantly enhance the vulcanization of fine-grained malachite under appropriate conditions. Flotation effect. Ammonium sulfate and ammonium chloride can only strengthen the flotation flotation when coexisting with sodium sulfide, while ethylenediamine and DMTD improve the flotation behavior of fine-grained malachite by coordinating with copper ions in mineral surface and pulp. .
4 Basic research on chemical beneficiation of copper oxide ore
For copper oxide ore, chemical beneficiation is mainly wet leaching. Depending on the leaching agent, leaching mainly includes acid hydrazine and ammonia leaching. Acid leaching generally uses inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid, and organic acids such as citric acid and lactic acid as leaching agents. Among them, sulfuric acid is a commonly used leaching agent. After acid leaching, copper exists in the form of copper sulfate. After extraction, copper-rich liquid is obtained. Then, electrolysis is used to produce cathode copper, which forms a process of "acid leaching, extraction, and electrowinning", which has been widely used in actual production.
Ammonia is not commonly used as ammonia or ammonium salt such as ammonium carbonate, ammonium chloride or ammonium sulfate as leaching agent. The copper oxide ore is dissolved in ammonia solution to form copper ammonia complex, which can directly treat raw ore, medium ore, tailings and oxidation. The calcined copper mineral is reduced. Regarding ammonia leaching, in order to improve the leaching rate of copper oxide ore, many scholars have studied the method of recovering copper oxide ore and the dissolution kinetics of the leaching process in different ammonia system. As a weakly alkaline reagent, ammonia is often used as a leaching agent alone or in combination with ammonium salts during ammonia leaching of copper oxide ore.
Liu et al. studied the dissolution kinetics of malachite from ammonia, ammonium sulfate concentration, pH, reaction temperature and ore size. The results showed that the ammonia/ammonium sulfate concentration was 3.0moI/L NH4OH+1.5moI/L. (NH4) 2S04, the liquid-solid ratio is 25::1, the leaching time is 120 min, the stirring speed is 500 r/min, the reaction temperature is 25 ° C, and the leaching rate of copper is greater than 96.8% when the particle size is less than 0.045 mm. The malachite dissolution process is a mixed control model of interface transfer and product layer diffusion, and its dissolution activation energy is 26.75 kJ/mol. Ekmekyapar et al. studied the leaching kinetics of malachite in ammonium nitrate solution, and studied a number of factors affecting the copper leaching rate. The leaching rate increased with the increase of ammonium nitrate concentration, reaction temperature, stirring speed and moderately. The ore particle size increases; the leaching process is a hybrid control model, including a chemical control model and a product layer diffusion control model, and the reaction activation energies are 95.10 kJ/mol and 29.50 kJ/moI, respectively. Deng Jiushuai et al. conducted a series of studies on the kinetic mechanism and influence of organic acid treatment of copper oxide ore.
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