How does the chrome ore beneficiation plant work?
What is Chrome Ore?
Commonly, chrome ores are classified based on their elemental compositions and industrial applications as high-chromium used for metallurgical processes, high-iron used for chemical and metallurgical purposes, and high-aluminum used widely as a refractory material. The only one of economic importance is Chromite(FeOCr2C3).
The nature of chromium is hard, so it is often mixed into steel to make a hard and corrosion-resistant alloy, mainly used for refining stainless steel, heat-resistant steel, and various electric heating element materials. When the stainless steel encounters corrosive substances, a fine and solid chromium oxide film will be formed on its surface to protect the inner metal from further corrosion. Some stainless steels can maintain their excellent properties even at high temperatures of 800℃. Therefore, chrome steel is a good material for building machinery, tanks, and armored vehicles.
Various chromium salts produced by processing chromite are the main raw material in the chemical industry. Chromium salt is one of the main varieties of inorganic salts, which has wide uses in daily life, such as electroplating, tanning, printing and dyeing, medicine, fuel, catalyst, oxidant, match, metal corrosion inhibitor, etc…
Refractories & Cast Iron
Since the melting point of chromite is as high as 1900℃~2050℃， chromite can keep the volume constant at high temperatures and doesn’t react with any slag. Therefore, it can be used as a refractory material, lining steel-making furnaces and non-ferrous metal smelting furnaces. In terms of refractory materials, chromite is used to make chrome bricks、chrome-magnesia bricks, and other special refractory materials. Besides, chromium is also used in cast iron, for example, chromium cast ductile iron has the characteristics of high strength, high elongation, high impact value, low hardness, etc…
In the automotive industry, Chromium is also involved in the production of car brake pads.
Chromite is a magma-tic mineral that often occurs in ultra-basic rocks and coexists with peridot. It looks like magnetite is appearance, generally in the form of lumpy or granular aggregates. The main components of chromite are iron, magnesium, and chromium oxides: (Fe, Mg)Cr2O4, which is a kind of spinel. It is the only ore of chromium with a complex mineral composition, variable magnesium, and sometimes aluminum. The hardness is 5.5-6, the specific gravity is 3.9-4.8g/cm3, and it has weak magnetism.
In order to get ferro chromite ore, usually the beneficiation process involves Chromite Ore Crushing, Chromite Grinding, and Gravity Separation Process.
Chromite Ore Crushing
For the low-grade chromite or chromite with coarse grain size, In the chromite ore beneficiation process, the crushing process adopts a two-stage jaw crusher for crushing, and the raw ore is crushed to less than 30mm, and then transported to the next silo by a conveyor.
The grinding process adopts rod mill grinding. Since the particle size of chromite ore embedding is slightly coarse, the monomer dissociation can be realized through simple rod mill grinding. At the same time, the rod mill has a high output and the product particle size is uniform and adjustable. It is an ideal chromite ore grinding equipment. A vibrating feeder is installed under the silo to evenly feed the crushed products into the rod mill for grinding.
Gravity Separation Process
The rod mill is used for grinding to achieve monomer dissociation and then enters the gravity separation process. The equipment suitable for chromite gravity separation is mainly jigs and shaking tables. The effect is remarkable, so the re-selection roughing process adopts a trapezoidal jig with a large processing capacity and a high recovery rate. Since the recovery effect of the jig on the fine-grained powdery ore is not obvious, a shaker can be installed behind the tailings of the jig for sweeping to recover the lost ferrochromium to improve the recovery rate of the entire process.
Magnetic separation Process
Weak magnetic separation for chromite: Weak magnetic separation can effectively remove magnetite, increase the chromite ratio of concentrate, and further enrich and select qualified chromite concentrate products. Especially for the unqualified concentrate containing a small amount of magnetite in the chromite concentrate product after gravity separation.
Intensive magnetic separation for chromite: In the treatment of chromite by strong magnetic separation, the magnetite is first removed by a medium magnetic separator, and then the chromite is recovered by a strong magnetic separator, and the gangue minerals are separated. It is mainly suitable for the re-selection of fine-grained minerals that cannot be effectively recovered.
Appropriate use of gravity separation and recovery of ferrochrome concentrate by stages
Early recovery of coarse grain ferrochrome concentrate and further recovery of fine grain concentrate can improve the recovery rate.
Combined use of separation gravity and magnetic separation
Appropriate use of gravity separation and magnetic separation process, chromite recovery rate can be greatly improved at the same time, effectively increase the proportion of chromium
Good application to low grade chromite
This solution can effectively process low-grade chromite, and recover ferrochrome concentrate by stages, and finally qualified concentrate can be obtained to meet the demanding of industrial application.