Copper sulfide ore is not uncommon among copper ore types. How can copper metal be used to obtain copper concentrate through appropriate mineral processing equipment and processes? When processing copper sulfide ore, in addition to copper sulfide minerals and gangue, it usually also contains various iron sulfide minerals, such as pyrite, pyrrhotite, and arsenic pyrite. Since separating copper sulfide minerals from gangue is relatively easy, the main difficulty in copper sulfide ore flotation is the separation of copper and sulfur.
When the content of iron sulfide minerals in the ore is high, it is recommended to use the preferential flotation process for separation. On the contrary, it may be more appropriate if priority is given to copper-sulfur mixed flotation and then separation. However, this does not exclude the use of preferential flotation processes.
The basic strategy for copper-sulfur separation is to use lime to suppress iron sulfide minerals. A small amount of cyanide can be added to enhance the inhibitory effect when necessary. We can use sodium carbonate, carbon dioxide gas, or sulfuric acid to revive suppressed iron sulfide minerals. At the same time, a small amount of copper sulfate needs to be added to improve the resurrection effect.
If the ore contains magnetite, it can be recovered using magnetic separation. If the ore also contains cobalt, usually cobalt will be present in pyrite, so pyrite concentrate can also be used as cobalt concentrate.
If the ore contains only a small amount of molybdenum, the copper-molybdenum mixed concentrate can be selected first and then separated. In most cases, a mixed flotation process separates copper-nickel ores. The mixed concentrate can be smelted into nickel matte, divided by flotation, or directly separated by flotation.
This process’s leading mineral processing equipment includes crushers, ball mills, magnetic separators, flotation machines, ore washers, and concentrators.
How to Extract Copper From Copper Sulfide Ore?
Extracting copper from copper sulfide ore involves chemical and physical processes. The most common method used for this purpose is known as smelting. Here are the basic steps involved in extracting copper from copper sulfide ore:
Crushing and Grinding
The first step is to crush the mined copper ore into small pieces. It typically uses crushers and grinding the ore into a fine powder. It increases the surface area of the ore, which is essential for the subsequent steps.
Concentration
After crushing and grinding, the copper ore is typically mixed with water to form a slurry. Various methods, such as flotation or gravity separation, separate the copper sulfide minerals from other gangue materials (unwanted minerals). These methods exploit the differences in the physical and chemical properties of copper sulfide minerals and gangue materials.
Roasting
The concentrated copper sulfide ore is then roasted in a furnace to convert the copper sulfides (usually copper pyrites, CuFeS2) into copper oxide (Cu2O) and sulfur dioxide (SO2). The chemical reaction is as follows:
CuFeS2 + O2 → 2Cu2O + 2FeO + 2SO2
Smelting
The roasted ore, which now contains copper oxide, is subjected to smelting. In smelting, the copper oxide is reduced to metallic copper. It is typically done by heating the roasted ore with a reducing agent, such as carbon (coke or charcoal), in a furnace. The carbon reacts with the oxygen in the copper oxide to produce metallic copper. The chemical reaction is as follows:
2Cu2O + C → 4Cu + CO2
Refining
The obtained copper, known as blister copper, often contains impurities, including iron and sulfur. To produce high-purity copper, the blister copper is further refined through a process called electrolysis. In this process, the blister copper is dissolved in an electrolyte solution, and pure copper is deposited on the cathode while impurities settle at the bottom as anode slimes.
Casting and Forming
The refined copper can be cast into various forms, such as ingots, sheets, or rods, depending on the intended use.
It’s important to note that this is a simplified overview of the copper extraction process. The specific methods and conditions can vary depending on the type of copper sulfide ore, the desired final product, and technological advancements in the field. Additionally, environmental regulations play a significant role in ensuring that the extraction and processing of copper are conducted in an environmentally responsible manner.
Copper Sulfide Beneficiation Equipment
Copper sulfide beneficiation equipment includes machines and devices that process and upgrade copper sulfide ore into a copper concentrate. The choice of equipment can vary depending on the specific characteristics of the ore, but here are some standard equipment used in copper sulfide beneficiation.
Crushers: These are used to break down the mined ore into smaller pieces, making it easier to handle and process. Standard crushers include jaw crushers, cone crushers, and impact crushers.
Grinding Mills: After crushing, the ore is usually ground to a fine powder to increase the surface area for subsequent beneficiation processes. Common types of grinding mills include ball mills, rod mills, and SAG (Semi-Autogenous Grinding) mills.
Flotation Cells: Froth flotation is widely used to separate copper sulfide minerals from gangue minerals. Flotation cells, also known as flotation machines, generate the froth and separate the valuable copper minerals from the gangue.
Thickeners: Thickeners are used to dewater the flotation concentrate, reducing the amount of water in the final product. It increases the concentration of copper in the concentrate.
Filtration Equipment: Filters, such as vacuum filters or filter presses, remove water further and produce a dry copper concentrate.
Magnetic Separators: Magnetic separators are used to remove iron-bearing minerals from the copper concentrate, helping to improve its quality.
Jigging Machines: Gravity separation methods, like jigging, are employed in some cases to separate copper minerals from gangue based on differences in density.
Spiral Concentrators: These are used for gravity separation and can effectively separate copper sulfides from gangue.
Leaching Equipment: In cases where leaching is part of the beneficiation process, equipment such as leaching tanks or reactors may dissolve and selectively remove certain impurities or copper minerals.
Roasting Equipment: If roasting is required to remove sulfur and convert copper sulfides to copper oxides as a pretreatment step, then may use rotary kilns or fluidized bed roasters.
Electrowinning Cells: In the final stages of copper processing, electrowinning cells are used to produce high-purity copper metal from the copper concentrate.
Analytical Equipment: Laboratory equipment for analyzing the ore and concentrate, such as X-ray fluorescence (XRF) and atomic absorption spectrometers, is essential for quality control.