Detail Of Chromite Beneficiation Method
Chromite has the characteristics of high density and medium magnetism and coarse crystalline particles, and the dressing method of chromite generally adopts washing method, low intensity magnetic separation method, medium intensity magnetic separation method, gravity separation method, flotation method and other beneficiation methods. The design of chromite beneficiation method needs to be developed according to the nature of chromite ore and various factors, under normal circumstances, chromite beneficiation uses gravity separation, and individual areas also use high intensity magnetic separation and flotation methods for washing.
The dressing method of chromite mainly depends on the grade, purity, particle size of chromite, composition and quantity of gangue mineral. Chromite has high density and weak magnetism. The mineral processing method of chromite poor ore in China has used jig, shaker, spiral ore concentrator, centrifugal ore concentrator and belt chute to separate the chromium poor ore (Cr 23 < 20%), and also used hydraulic separation tube to separate the ore in the shaker. Dry high intensity magnetic separation, wet high intensity magnetic separation, flotation and various chemical separation methods were studied in the laboratory. But in the actual production, gravity separation is mainly used, and some mines use high intensity magnetic separation.
The commonly used dressing methods of chromite mainly include gravity separation, magnetic separation and flotation. Below, let's understand the dressing method of chromite one by one.
1, chromite beneficiation method - gravity separation method detailed explanation:
Chromite ores are mostly in the state of massive, strip and porphyric coarse-grained disseminated, and the density is large, so gravity separation is one of the effective ways to select. At present, gravity separation methods such as shaking table and jigging are used to recover chromite in production practice.
Shaker sorting chromite: Shaker is suitable for fine grained chromite ore sorting, processing particle size range is generally 3-0.019mm, sorting is the bed surface longitudinal and transverse flow action to achieve, higher sorting accuracy, can obtain a higher enrichment ratio, but its processing capacity is low, occupy a large area.
Jig separation chromite: Jig is suitable for processing coarse and medium size chromite ore, the general processing particle size range is 35-0.1mm, can get the final product in a single separation.
2, chromite beneficiation method - chromite magnetic separation method detailed explanation:
The hardness of chromite is 5.5, the specific gravity is 4.2~4.8, with low magnetic separation, so magnetic separation is also one of the effective separation methods, can use low magnetic separation, high magnetic separation and other methods to select chromite.
Low intensity magnetic separation chromite: low intensity magnetic separation can effectively remove magnetite, improve the chrome-iron ratio of concentrate, and further enrich and select qualified chromite concentrate products. In particular, it is of great significance for unqualified concentrates containing a small amount of magnetite in chromite concentrate products after gravity separation.
High intensity magnetic separation of chromite: high intensity magnetic separation of chromite is to remove magnetite with a medium magnetic separator, and then recover chromite with a high intensity magnetic separator and separate gangue minerals. It is mainly suitable for gravity separation of fine minerals that cannot be effectively recovered.
3, chromite beneficiation method - chromite flotation method detailed explanation:
Flotation is the main method for the separation of fine chromite. It is considered to be used when the effects of gravity separation and high intensity magnetic separation are not good. The flotation methods of anionic collector and cationic collector are mainly used.
Anion collector flotation chromite: it is necessary to fully disperse the pulp, selectively flocculate the mineral, and prioritize the flotation of chromium minerals. Therefore, the mineral should be fully dissociated during grinding, and the alkali should be added to ensure the pH value of the pulp (pH=11.0~11.5), and then the dispersant should be added to make the pulp form a stable dispersion system, and then the selective flocculant is added to the dispersed pulp to make the fine gangue flocculate. However, care should be taken to prevent the formation of anionic collector films on the gangue minerals that have been flocculated.
Cationic collector flotation chromite: fine grinding operation is required to achieve monomer dissociation of minerals, but a large amount of slime will be produced, so the pre-desliming operation should be carried out before flotation, otherwise a large amount of chromite will be lost.
In addition to negative and cationic collectors, there are some new collectors, such as n-oleate amine moline chlorol, saccharic acid diallyl methanol adduct, etc., can be used for the separation of chromium ores containing 26% Cr2O3.
Sometimes the gravity concentrate will be reconcentrated by low magnetic or high magnetic separation to further improve the grade of chromium concentrate and the ratio of chromium to iron. When magnetic separation is used to separate chromite ore, single magnetic separation method is rarely used, and it is mostly used in combination with gravity separation process.
The specific gravity of chromite is 4.1~4.7g/cm3, the associated gangue and silicate iron mineral specific gravity is generally 2.7~3.2g/cm3, using the difference in mineral density, can be used spiral chute, jig, shaking table, spiral separator, centrifuge and other gravity separation equipment for sorting. The beneficiation method of chromite is suitable for chromite with coarse crystal size, and fine grain is easy to be lost in tailings.
The distribution size of chromite is generally medium and fine, so the equipment used mostly includes crusher, rod mill, etc. The determination of chromite gravity separation equipment needs to be based on the specific distribution size of chromite, such as the distribution size is coarse, the use of rod mill can achieve most of the monomer separation after grinding, then the selection of rod mill - jigging process, such as the distribution size is fine, It is necessary to use a ball mill to grind, and the grinding product enters the high intensity magnetic separation process or flotation process after reaching monomer dissociation.
Chromite mineral processing method Crushing process: In the chromite mineral processing process, the crushing process adopts two stages of jaw crushing, crushing the raw ore to 30mm below, and then transported to the next silo by conveyor.
Grinding process: grinding process using a rod mill grinding, because the general chromite distribution particle size is slightly coarse, through a simple rod mill grinding can achieve monomer separation, while the rod mill output is high, the product particle size is uniform and adjustable, is the ideal chromite grinding equipment. A vibrating feeder is arranged under the silo to evenly feed the broken product to the rod mill for grinding operation.
Chromite beneficiation method gravity separation process: The front has been reduced to, chromite distribution particle size is generally coarse, the use of rod mill grinding to achieve monomer separation after entering the gravity separation process, and the equipment suitable for chromite gravity separation is mainly jig and shaker, jig processing capacity is large, the coarse effect of chromite is significant, so the gravity roughing process uses a large capacity, high recovery of trapezoid jig. Because the recovery effect of the jig on fine powder ore is not obvious, the shaking table can be set up after the jig tail ore to sweep and recover the lost ferrochrome to improve the recovery rate of the whole process.
Jig is the main gravity separation equipment in the chromite concentration method, and the final concentrate can be separated at one time in normal operation. The shaker is generally used as a sorting equipment with small processing capacity but high enrichment. In this process, the tailings of the jig are swept and sorted to recover fine-grained chromite. This process is suitable for the washing and purification of coarse and medium grade chromite, and the fine grade or micro-fine grade chromite embedded needs to be discussed separately. In addition, for the mineral processing of sand chromite, it is also necessary to determine the mineral processing process and equipment configuration according to the actual situation.
The choice of chromite beneficiation method is closely related to the physical and chemical properties of chromite. Because the specific gravity of chromium ore is 4.3-4.6 and the Mohs hardness is 5.5-7.5, with the continuous progress of mineral processing technology, the process of purifying chromium ore by gravity separation has been very mature. Moreover, because the gravity separation process has no pollution to the environment, the gravity separation process of chromium ore has been popularized and applied in major mine concentrators. The specific process of gravity mineral processing is that the raw ore enters the coarse crushing from the raw ore bin through the ore feeder, the coarse crushing enters the fine crushing, and the fine crushing enters the powder ore bin. The powder ore is fed into the ball mill by the belt conveyor, and the ball mill is equipped with the grinding head screen, in which the material on the screen is transported back to the ball mill for grinding, and the material under the screen enters the spiral chute for roughing. A part of the concentrate is produced by rough sorting in the spiral chute. The middle ore is returned for re-sorting, and the tailings enter the spiral chute for sweeping and sorting. The concentrate swept by spiral chute enters the shaker and is selected, the middle ore is returned and the tailings are discarded. The coarse concentrate in the shaker is another part of the concentrate, the ore in the shaker is returned for re-sorting, the tailings of the shaker are thrown off, and all the concentrate enters the sedimentation tank for dehydration. The tailings swept by the spiral chute and the tailings of the shaking table are combined into the total tailings, which enter the tailings sedimentation tank to precipitate a part of the tailings, and then enter the tailings pond, and the clarified water in the tailings pond is recycled for reuse.
Beneficiation methods of chromite in Philippines: The chromium content of chromite in the Philippines is low, about 4.8%, the mud content of the ore is very high, most of them are chromite ore sand, containing coarse grained stones are very limited, due to the large viscosity of the mud in the ore, it is necessary to go through a reasonable washing operation before beneficiation to carry out the next sorting operation, after the customer's field production practice found that after a simple washing ore, The grade of chromite can be increased from 4.8% to 30-35%, it can be seen that the content of mud in ore is indeed high, but improper operation in the washing operation or the use of unreasonable washing equipment will result in a decrease in the recovery rate of beneficiation or low processing capacity, so the customer deliberately found Fery Machinery, It is hoped that our factory can provide them with more reasonable and ideal beneficiation process and equipment configuration suggestions. First of all, the washing operation using a simple water gun washing is very unreasonable method, water gun washing for chromite ore washing effect is very limited, although it can also improve the grade of raw ore to a certain extent, but the resulting loss of chromite is also immeasurable, in order to improve the washing recovery rate, it is necessary to change the water gun to the washing machine, completely change the way of washing ore. In order to effectively improve the efficiency and effect of ore washing. Such as fine chromite ore washing in the Philippines, need to use spiral washing machine for washing, spiral washing machine according to customer requirements can be made into a double spiral washing machine, large spiral washing machine and other different specifications, to meet different production volumes, and spiral washing machine for fine chromite washing effect is also very obvious, the recovery rate can also reach a satisfactory degree. After the spiral washing machine washing, the mud in the chromite has been very limited, and the viscosity has been washed, and only some fine waste stone remaining affects the grade of chromite in the chromite ore. Therefore, in addition to the washing operation, it is also necessary to carry out beneficiation and purification operation.
The most commonly used method of chromite beneficiation method is gravity separation method, the actual production is also the most widely used gravity separation method, according to the specific properties of minerals can also be used strong magnetic separation method. The most commonly used equipment for chromite separation by gravity separation method is Jig, which has high efficiency and high recovery rate, occupies an irreplaceable position in the field of chromite beneficiation and purification, and is also the most widely used chromite beneficiation equipment. The commonly used chromite ore dressing jig is mainly trapezoidal jig and down-moving jig. After the washing operation, the chromite does not contain mud, and the viscosity is greatly reduced, so there will be no chromite wrapped in soil and not effectively recovered, which also greatly improves the recovery rate of chromite dressing.
The above is the commonly used chromite beneficiation method. In addition, there are some chemical beneficiation methods can be selected chromite, such as selective leaching, reoxidation, melt separation, sulfuric acid and chromic acid leaching, reduction and sulfuric acid leaching methods, can effectively improve the physical method of the output of concentrate chromite iron ratio. In the end, as for the choice of the process, it is necessary to carry out beneficiation tests on chromite first, analyze the type of elements and the structure of the raw ore, and customize the targeted beneficiation process in order to obtain the ideal beneficiation index.
