The pre-beneficiation of iron ore is the iron beneficiation between suitable crushing and grinding with responsible equipment according to different ore characteristics. It is to discard part of tailings in coarse conditions.
The common pre-beneficiation methods of iron ore include strong magnetic separation, weak magnetic separation, and gravity separation. Among them, the stong magnetic iron ores always apply for the weak magnetic separation. For weak magnetic iron ore, strong magnetic separation or gravity separation is suitable.
Use the table of contents below to navigate through the guide:
Weak magnetic ores are mainly hematite, false hematite, mirrorite, limonite and so on. To gain better iron minerals, the common pre-beneficiations of iron ore are strong magnetic separation and gravity separation.
(1)Strong magnetic pre-separation
According to weak magnetic iron minerals, strong magnetic pre-separation is an effective way. It separates weak magnetic iron minerals from other gangue minerals. The processing efficiency is high. Strong flexibility, high equipment operating rate, low cost of operation and small workload of maintenance.
The common pre-beneficiation equipment includes high gradient strong magnetic separator, electromagnetic induction roller type strong magnetic separator.
Gravity pre-separation is also a common method. Gravity separation mainly separates valuable minerals and gangue minerals according to the proportion of gravity differences. The gravity pre-separations are mainly jig pre-separation and gravity medium pre-separation.
The jig pre-separation puts the mixture of ore particles into a vertically-lifting variable-speed medium stream, and then separate them.
It has the specialty of simple structure, less investment, high efficiency of separation, high recovery rate, and low cost of management. It has a good separation effect for weak magnetic iron ores and mixed iron ores. Over 80% of waste stones can be wiped off under suitable conditions. However, it has the disadvantage of the large consumption of water and poor effort on conjoined mineral separation.
b.Heavy medium pre-separation
It is based on Archimedes' theorem. Under the action of the gravity of the earth, heavy liquid or resuspended liquid is used as a medium to float useful minerals with a density less than the medium to the surface of the medium and to immerse waste ore with a density greater than the medium.
The bottom of the separation tank is used to achieve separation.
It is an effective way of pre-beneficiation of iron ore, especially for the magnetite with iron content over 60%. The production capacity is large. Less investment, high sorting accuracy and strong flexibility of feeding minerals. This method is suitable for large scale production. However, gravity liquor is expensive, increasing the investment.
The common equipment for heavy medium pre-separation includes: heavy medium vibration tank, heavy medium hydrocyclone, heavy medium vortex cyclone, etc.
Strong magnetic iron ore is mainly magnetite ore. Weak magnetic pre-separation can obtain good iron minerals. The magnetic induction of magnetic equipment is usually under 160kA/m or 200mT.
It is high efficiency of separation, simple in technology, less investment and fast in results.
The common weak pre-separation equipment includes: permanent magnet block magnetic separator, electromagnetic block magnetic separator, dry magnetic separator, etc.
The above are the common pre-beneficiation methods and beneficiation equipment for iron ore. The pre-beneficiation operation can not only effectively improve the utilization rate of ore resources but also effectively improve the economic benefits of the processing plant. Due to the different types and properties of iron-containing minerals in iron ore, the pre-beneficiation process needs to be determined according to the properties of the ore and the requirements of crushing particle size. Therefore, it is recommended to customize suitable pre-beneficiation processes and equipment through the beneficiation test to improve the ore recovery rate.