It is inevitable that iron ore will be mixed with some surrounding rocks during mining, especially underground mining. The amount of mixed surrounding rocks is larger, which can reach about 20%. Such a large amount of surrounding rock will inevitably lead to an increase in the later crushing and grinding costs. How can the iron ore dressing plant reduce energy consumption and save costs? Here is the recommended iron ore preconcentration method.
The pre separation of iron ore refers to the separation operation of discarding part of the final tailings under coarse grain conditions by using corresponding equipment according to different ore properties after the raw iron ore is moderately crushed and before it is grinded.
We know that grinding is a process with large energy consumption and high capital ratio, which may account for about half of the energy consumption of the concentrator. Therefore, if the iron ore can be preconcentrated before grinding, energy consumption and capital investment can be reduced. Therefore, in recent years, many iron ore concentrators have adopted the pre concentration process in the crushing and screening process and achieved good results.
For different iron ores, different preconcentration methods can be selected according to the magnetism of iron ores. Common iron ore preconcentration methods include strong magnetic separation, weak magnetic separation and gravity separation. Let's get to know.
1. Preconcentration method of hematite, limonite and specularite
Hematite, pseudohematite, specularite and limonite are iron ores with weak magnetism, which are collectively referred to as weak magnetic iron ores. For weak magnetic iron ores, strong magnetic separation method and gravity separation method are usually used for preconcentration.
High intensity magnetic separation
For weakly magnetic iron minerals, high intensity magnetic separation is an effective method to separate them from other gangue minerals. Its sorting efficiency is high, adaptability is strong, equipment operation rate is high, operation cost is low and maintenance workload is small. Common preselection equipment includes high gradient high intensity magnetic separator, electromagnetic induction roller high intensity magnetic separator, permanent magnet high intensity magnetic separator, etc.
Re selection method
The gravity concentration preconcentration method is widely used, which can select jigging preconcentration or heavy medium preconcentration.
Jigging preconcentration: Jigging preconcentration is a process in which mineral particles are separated according to the density difference between ores by putting the mineral particle mixture into a vertically ascending and descending variable speed medium flow. The jig has the advantages of simple structure, low investment, high separation efficiency, high recovery rate and low operating cost. The weak magnetic separation of iron ore and mixed ore has good separation effect, and about 80% of the waste rock can be removed under suitable conditions. However, jigging pre separation consumes large amount of water and has poor separation effect on intergrowth minerals.
Heavy medium preselection: According to Archimedes' theorem, heavy medium preselection uses heavy liquid or heavy suspension as the medium under the action of gravity, so that useful minerals with density less than the medium can float to the surface of the medium, and waste ores with density greater than the medium can be immersed in the bottom of the separation tank to achieve separation.
The heavy medium is an effective pre concentration method. The pre concentration of magnetite concentrate with iron grade of more than 60% is characterized by large production capacity, low investment, high specific gravity separation accuracy, strong adaptability to the particle size of ore to be beneficiated, and is suitable for large-scale production. However, the heavy liquid used in gravity preselection is expensive, which increases the investment cost.
2.Preconcentration method of magnetite
Preconcentration method of weak magnetic separation: strong magnetic iron ore is mainly magnetite, and good iron ore can be obtained by using weak magnetic separation. Generally, magnetic separation equipment with magnetic induction intensity below 160kA/m (or 200mT) can be selected. The weak magnetic separation preconcentration method has the advantages of high separation efficiency, simple process, low investment and quick effect for strong magnetic iron ore.
After the above pre concentration of iron ore, a part of surrounding rock minerals can be screened out to improve the quality of the ore. The remaining iron ore will enter the normal beneficiation process again, which will avoid excessive impurities during grinding, reduce the grinding cost, reduce the investment cost of the iron ore concentrator, and create greater profits for the concentrator. how? After a brief introduction, do you also think the preselection method is a good way to reduce energy consumption and save costs?
