What is the Best Beneficiation Process for Magnetite and Hematite?

( Iron ore processing plant in China - what is the best beneficiation process )

At present, iron ores processed in the beneficiation plant are mainly magnetite, hematite, limonite, mirror iron ore, vanadium and titanium magnetite and rhodochrosite. In this article, we will mainly introduce the beneficiation process of magnetite and hematite.

Iron ore beneficiation process is for the processing of iron ore materials, divided into crushing and screening, grinding and classification, sorting and dewatering.

Crushing and screening is the crushing and screening of iron ore to ensure that the size of the crushed ore can provide the next process to meet the block size requirements of the ore.

Through the processing of ball mill and classifier, the ore that meets the pre-sorting of minerals is obtained.

Mineral sorting generally includes gravity separation, flotation and magnetic separation, usually iron ore can use one of the sorting process according to the nature of iron.

Dewatering is to concentrate, filter and dry the ore after mineral sorting, and finally the iron ore will be selected.

So below we will first introduce magnetite beneficiation process. Let's start it!

Magnetite ore is a silica-type ore, in which the main iron minerals are magnetite, but also contains a small amount of sulfide minerals, and accompanied by cobalt-nickel-vanadium and other non-ferrous metals. The vein is silica. The magnetite ore is speckled, brecciated, banded and massive. The magnetization coefficient is similar to that of magnetite quartzite. According to the size embedding characteristics, magnetite ores can be classified as coarse-grained, fine-grained, micro-fine-grained and very micro-fine-grained embedding ores.

Based on the physical properties of magnetite ores, the most effective beneficiation method is to recover magnetic minerals by magnetic separation and associated sulfide minerals by flotation.

The sorting process of magnetite ore is mainly two to four stages of crushing, and in the crushing process with one to two stages of dry magnetic separation, selection of medium or fine crushed products. For further deep-selected products, after two to three stages of fine grinding, two to five times wet magnetic separation, to obtain the final iron ore concentrate products using magnetic separation - flotation or flotation - magnetic separation and other combined processes. While improving the grade of the iron concentrate, the associated minerals can be recovered to become the corresponding concentrate products, as well as the desulfurization of the concentrate.

Finally, the magnetite ore grinding size is coarse and the content of muded particles is low, and generally the magnetic separator can be used for desliming.

The development and utilization of fine-grained embedded hematite ore has promoted the development of beneficiation processes such as hematite flotation, gravity separation, strong magnetic separation and roasted magnetic separation. And hematite ore mainly has the following six beneficiation processes.

(1) Full flotation process

The process uses fatty acid anion trap, sodium carbonate as pulp adjuster (pulp pH 910), flotation of hematite in hematite quartzite type ore, solving the problem of large pulp viscosity, concentrate dewatering difficulties. In addition, a two-stage concentration operation is used to reduce metal loss;

(2) Strong magnetic - flotation process

The main feature is to discharge the monolithic quartz and mud-prone chlorite and other vein minerals from the ore under coarse grinding conditions to become a qualified concentrate, thus creating favorable conditions for further fine grinding and flotation;

(3) Roasting - magnetic separation process

A shaft furnace is used to heat and reduce 75-20 mm hematite ore with a mixture of coke oven and blast furnace gas to produce artificial magnetite ore, which is then magnetically sorted to obtain iron ore concentrate.

(4) Roasted magnetic separation - reverse flotation process

In order to improve the quality of roasted magnetic separation iron concentrate, dodecylamine cationic trapping agent is used and reverse flotation is carried out in neutral pulp.

(5) Strong magnetic separation process

(6) Stage grinding, heavy magnetic - anion reverse flotation process

(1) Gravity Separation - Magnetic Separation - Flotation Process

The process can obtain a high recovery rate of high-quality iron ore concentrate products more competitive.

Its main feature is that after the primary grinding cyclone classification, a spiral chute is used to recover part of the coarse-grained iron minerals. The fine particles are recovered by magnetic separation-flotation process and the intermediate products are combined for secondary grading and grinding, and then returned to the sorting circuit.

(2) Magnetic Separation - Gravity Separation Process

For fine-grained embedded magnetic-hematite ore, some magnetite minerals are recovered by magnetic separation, and weak magnetic minerals are recovered by spiral chute and centrifugal concentrator for its tailings.

(3) Continuous Grinding - Magnetic Separation (Weak Magnetic - Strong Magnetic) - Reverse Flotation Process

The main feature is that continuous grinding is used to grind the ore directly to monomer dissociation, and only the final grinding product size is controlled.

The use of weak magnetic strong magnetic separation can play a dual role of discharging tailings and desliming, reducing or eliminating the harmful effects of ore mud on flotation. The strong magnetic separation has the best effect on mud removal.

The use of reverse flotation (flotation of quartz and other veins) adapts to the different proportions of magnetite, hematite and pseudo-hematite in the ore.

Ore mainly hematite, mainly the selection of coarse-grained embedded ore with good physical properties, and the use of microfine embedded hematite is still a subject of exploration in the world.

For the beneficiation of hematite - magnetite ore, now mostly use the magnetic separation - gravity separation process, magnetic separation - flotation process or gravity separation - magnetic separation - - flotation process. Some processing plants first use the gravity separation method to recover hematite, and then use the magnetic separation method to recover magnetite from the gravity separation tailings; also use the flotation method and use the electric selection method for selection, or use the fine screen treatment before the last section of selection.

The magnetic separation - gravity separation process first uses weak magnetic field magnetic separation to recover magnetite, and then uses gravity separation to recover hematite from the magnetic separation tailings. The magnetic separation-flotation process uses flotation as the main process to sort the hematite concentrate, with coarse-grained hematite and magnetite recovered by gravity separation and fine-grained magnetite recovered by magnetic separation.

For densely crystallized hematite-magnetite quartzite, gravity separation is widely used to sort coarse-grained embedded ores, and strong magnetic separation or flotation is used to sort fine-grained ores.

For clayey hematite-magnetite quartzite, washing or dry magnetic separation is mainly used.

Above we have mainly introduced the relevant beneficiation process of magnetite and hematite.But in the actual beneficiation plant, we also need to design the relevant beneficiation process according to the characteristics of the ore and the actual conditions of the beneficiation plant to choose the most suitable beneficiation process.

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