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Click to add WeChatIn the modern industrial system, cobalt, as a key strategic metal, is widely used in many fields such as batteries, super alloys, and cemented carbide. The effective development and utilization of cobalt resources depends on suitable beneficiation methods. At present, common cobalt ore beneficiation methods include flotation, magnetic separation, gravity separation, electrostatic separation, and chemical beneficiation. The applicable conditions of each method are different. Let's learn about these methods together.
Cobalt ore flotation mainly relies on the difference in surface chemical properties between minerals to achieve the separation of cobalt ore and gangue minerals. During the flotation operation, a quantitative beneficiation agent is added to change the hydrophobicity and hydrophilicity between minerals. At the same time, corresponding foaming needs to be generated so that the hydrophobic minerals are adsorbed on the foaming and then float up to form a foaming layer, while the hydrophilic minerals remain in the slurry, thereby achieving effective separation between minerals.
Flotation is suitable for processing various types of cobalt ores, especially cobalt sulfide ores and cobalt oxide ores. For cobalt sulfide ores, flotation can obtain higher concentrate grade and recovery rate. In the beneficiation of some high-quality cobalt sulfide ores, the cobalt concentrate grade can reach 25%-35%, and the recovery rate can reach 80%-90%. For cobalt oxide ores, better separation effects can also be achieved by using special collectors and regulators.
When the flotation method is operated, it has strong selectivity for minerals and can effectively separate cobalt minerals with lower grade and finer embedded particle size. Its equipment is simple and flexible to operate, and the reagent system and flotation process parameters can be adjusted according to the properties of the ore. However, the flotation method also has certain limitations. It is more sensitive to changes in ore properties. When the mineral composition in the ore is complex and the symbiotic relationship is close, the selectivity of the flotation reagent will be affected, resulting in a decrease in concentrate grade and recovery rate. In addition, a large amount of chemical reagents are used in the flotation process, which may cause environmental pollution if not handled properly.
Magnetic separation uses the difference in the magnetic properties of minerals to separate cobalt minerals from gangue minerals in a magnetic field. Cobalt minerals can be divided into strong magnetic, weak magnetic and non-magnetic according to their magnetic properties. Strongly magnetic cobalt minerals will be quickly attracted to the vicinity of the magnetic pole in a strong magnetic field, while weakly magnetic cobalt minerals need to be effectively separated under a stronger magnetic field strength, while non-magnetic gangue minerals are almost unaffected by the magnetic field.
Magnetic separation is suitable for processing ores containing magnetic cobalt minerals, such as cobalt magnetite. For such ores, magnetic separation can quickly and effectively enrich cobalt minerals. In the selection of some ores with a high content of cobalt magnetite, the grade of cobalt concentrate can be increased from 3%-5% of the original ore to 15%-20% through a magnetic separation process of one roughing and multiple fines, and the recovery rate can reach 70%-80%.
The process flow of magnetic separation of cobalt ore is relatively simple, easy to operate, low cost, and environmentally friendly. Magnetic separation can quickly enrich magnetic cobalt minerals and improve the grade of subsequent beneficiation operations. However, the magnetic separation method still has limitations. It is only suitable for processing ores containing magnetic cobalt minerals, and cannot directly separate non-magnetic cobalt minerals. In addition, the magnetic separation effect is greatly affected by factors such as the particle size, magnetic strength and magnetic interference of the magnetic minerals in the ore. When the magnetic cobalt mineral particles are too fine or closely coexist with the gangue minerals, the grade and recovery rate of the magnetic separation concentrate will decrease.
Gravity separation of cobalt is based on the density difference between cobalt and other minerals, and uses gravity to achieve separation. In the gravity field, the cobalt minerals with higher density settle faster, while the gangue minerals with lower density settle slower. Common gravity separation equipment includes jigs, shaking tables, chutes, etc.
Gravity separation is suitable for processing cobalt ores with coarse grains, especially when the density difference between cobalt minerals and gangue minerals is large, the gravity separation method can achieve better results.
The gravity separation of cobalt has a simple process, low equipment investment, and low operating cost. It can quickly discard a large amount of gangue minerals in the early stage of the beneficiation process and improve the grade of subsequent operations. However, the gravity separation method has a poor effect on the separation of fine-grained cobalt ore. When the particle size of cobalt ore is less than 0.074mm, the movement of fine-grained minerals in the medium is affected by many complex factors, and it is difficult to stratify by density, resulting in a decrease in separation accuracy. In addition, the gravity separation method is relatively weak in adaptability to ore properties. When the density difference between cobalt minerals and gangue minerals is small, it is difficult to achieve efficient separation.
Electrostatic separation of cobalt is to use the difference in the electrical properties of minerals to separate cobalt minerals from gangue minerals in an electric field. The electrical properties of minerals mainly include conductivity, dielectric constant, etc. In the electrostatic separation process, dry cobalt ore particles are fed into the electrostatic separation equipment. Under the action of the electric field, cobalt mineral particles with good conductivity can quickly obtain electric charge and deviate from the original motion trajectory under the action of the electric field force, while gangue mineral particles with poor conductivity maintain the original motion direction, thereby achieving separation.
The electrostatic separation method is suitable for processing cobalt ores that have been pre-enriched and have obvious electrical differences between minerals. In some rare metal paragenetic ores, after the cobalt minerals and other minerals are initially separated by the preliminary beneficiation method, the electrostatic separation method can further improve the grade of the cobalt concentrate.
Electrostatic separation has high sorting accuracy and can effectively separate ores with small electrical differences between minerals. The equipment occupies a small area and has high production efficiency. However, the electrostatic separation method has high requirements for the pretreatment of the ore. The ore needs to be dried and the ore particle size must be uniform, otherwise it will affect the sorting effect.
Chemical cobalt selection is to extract cobalt minerals from the ore through chemical reactions. Common methods include roasting-leaching method and direct leaching method.
Roasting-leaching: first roast the cobalt ore to change the chemical composition and structure of the cobalt mineral, making it easier to be dissolved by the leaching agent.
Direct leaching: directly use a suitable leaching agent to react chemically with the cobalt ore, so that the cobalt enters the solution in the form of ions, and then obtains the cobalt product through subsequent separation and purification processes.
Chemical beneficiation is suitable for processing various types of cobalt ores, especially for some complex ores that are difficult to process with traditional physical beneficiation methods, such as low-grade cobalt oxide ores and cobalt-containing sulfide ores. When processing low-grade cobalt oxide ores, by optimizing the leaching process and conditions, the cobalt leaching rate can reach 80-90%, and the purity of the final cobalt product can meet the requirements of industrial applications.
Chemical beneficiation of cobalt can effectively process complex and difficult-to-select cobalt ores, has strong adaptability to ores, and can select appropriate chemical reactions and process parameters according to the properties of the ore. However, the chemical beneficiation method requires the use of a large amount of chemical reagents, which is costly, and the wastewater and waste residues generated have certain pollution to the environment, requiring supporting and complete environmental protection treatment facilities.
The above is an introduction to several common cobalt ore dressing methods. In the actual beneficiation process, it is often necessary to comprehensively select suitable methods to achieve effective cobalt beneficiation based on factors such as the properties, grade, embedded particle size and paragenetic mineral relationships of the cobalt ore. It is recommended to conduct beneficiation tests on cobalt minerals first, and design suitable cobalt ore beneficiation plans and complete sets of cobalt ore beneficiation equipment according to actual conditions to achieve efficient separation and enrichment of cobalt minerals and improve the development and utilization efficiency of cobalt resources.
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