The oxidation structure is loose and fragile, the combined copper content is high, the embedded particle size is uneven, the water content and mud content are more, and many components are associated. There are many kinds of copper bearing minerals, most of which contain more than 5 kinds of copper oxide minerals, such as malachite, azurite, hematite, alum minerals and chrysocolla. At present, the treatment methods of copper oxide ores mainly include five flotation methods and two chemical beneficiation methods.
Flotation is one of the main methods to treat oxidized copper ores at home and abroad, which is widely used in production sites. Copper oxide flotation can be divided into sulfide xanthate flotation method, fatty acid flotation method, amine flotation method, emulsion flotation method and chelating agent neutral oil flotation method according to different types of collectors.
Sulfidation xanthate flotation method is to use sulfurizer to generate a
certain amount of sulfide film on the ore surface, improve the adsorption
capacity of xanthate collectors on the ore surface, and thus enhance the
hydrophobicity of the ore. At present, sulfide flotation is still the dominant
flotation method of copper oxide ores.
In the process of sulfurization
flotation, the dosage of sulfurizer and the pH value of pulp should be well
controlled. In the flotation process, sulfur ions have dual functions: on the
one hand, they can vulcanize the surface of oxidized ore to generate a slightly
hydrophobic sulfide film on its surface for activation; on the other hand, when
there are excessive sulfur ions, they can inhibit the oxidized ore or sulfide
ore that has been vulcanized. In actual production, the curing agent should be
added in batches and points to make it fully play its role. In addition, the pH
value also has a great influence on the vulcanization effect. Generally, when
the pH value is within the range of 7~9, the vulcanization effect is good and
the recovery rate of copper oxide is high.
Fatty acid flotation methods include fatty acid direct flotation method and
sulfurized fatty acid flotation method, but the effect of both methods is not
ideal, and they are mostly used to treat malachite with simple ore properties,
uncomplicated gangue components, high copper grade raw ore and relatively good
floatability.
Fatty acid collectors are characterized by strong collecting
ability and poor selectivity. When the content of alkaline earth metal ions or
heavy metal ions in ore is high, quartz and silicate minerals will be activated.
Fatty acid collectors can not only interact with useful minerals, but also with
activated quartz, silicate and other minerals, losing their selectivity. And
when the content of slime in ore is high, the selectivity of fatty acid
collectors will become worse.
Amine flotation method, also known as ion blocking collector flotation
method, is a common flotation method for nonferrous metal oxide ores (copper,
lead, zinc oxide ores), which is mainly used in chalcopyrite and malachite. When
amine collectors are used for flotation of oxidized copper ores, presulfiding
and appropriate addition of non-ionic additives are helpful to improve the
separation effect of amine collectors. The role of presulfiding is to enhance
the electronegativity of ore surface, which is conducive to the electrostatic
adsorption of amine salt; The non-ionic additive is mainly the adsorption
between organic agents, which enhances the hydrophobicity and enhances the
contact between minerals and bubbles to float.
Amine collectors have the
advantages of fast flotation speed and high recovery. But there are also some
shortcomings such as difficulty in defoaming flotation foam, expensive reagents,
and sensitivity of reagents to slime. However, the slime content of copper oxide
ores is generally high, so there are limitations in flotation of copper oxide
ores with amine collectors.
Emulsion flotation method adds copper complexing agent to copper oxide to create a stable lipophilic mineral surface, and then covers the mineral surface with neutral oil emulsion to create a highly hydrophobic floatable state, increasing the adhesion with bubbles and floating up with bubbles. Phenylguanidine (gua), sulfobenzazole, benzoyl triazole and benzotriazole are common complexing agents, and the neutral oil can be kerosene, diesel oil and gasoline. The application of this method also requires the addition of gangue inhibitors such as sodium silicate and acrylic polymer. Copper oxide emulsion flotation has the advantages of high speed and high recovery.
The chelating agent neutral oil flotation is to selectively react with the metal ions on the mineral surface to generate an oleophilic and hydrophobic chelate, and then add neutral oil to float the chelate with the neutral oil. The chelating agent has strong selectivity and collection ability for copper ions. The chelating agent neutral oil flotation method not only has the advantages of fast flotation speed and high enrichment ratio, but also can greatly reduce the consumption of sodium sulfide.
According to the difference of chemical properties of copper mineral
components, chemical agents are used to change the composition, and then
corresponding methods are used to enrich the target components. Acid leaching
and alkali leaching are divided according to the different leachants.
Acid leaching is mainly used to treat high acid ores mainly composed of silicate gangue. According to different leaching methods, it can be divided into heap leaching, tank leaching and in-situ leaching. For oxidized copper ores: heap leaching is mainly used to treat loose surface, porous low-grade oxidized copper ores or stripped waste rocks with lower copper grade at the boundary. Trough leaching is widely used to treat slightly higher grade oxidized copper ores that are difficult to recover by physical methods. This method has the advantages of short leaching cycle and high recovery rate. In situ leaching is usually used to treat low-grade copper sulfide or copper oxide minerals underground. The leaching solution flows through the ore and dissolves copper bearing minerals, and finally recovers copper from the leaching solution.
Alkali leaching is mainly used to treat highly alkaline ores mainly composed
of calcium magnesium gangue. Leaching agents for alkaline leaching include
caustic soda, sodium cyanide, ammonium carbonate, ammonium bicarbonate, ammonium
chloride, etc. For the industrial production of alkaline leaching of copper
oxide ores, ammonia leaching agents are mostly used.
The above is copper
oxide ore dressing. There are many kinds of copper oxides and their properties
are complex. In order to separate ores more reasonably, the beneficiation method
is very important. First, the beneficiation test should be carried out, the ore
properties should be analyzed, and a scientific beneficiation test report should
be obtained to determine which method to use. The beneficiation scheme should be
determined after considering the actual situation of the concentrator,
investment and other factors, so as to achieve an ideal rate of return on
investment.
