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Click to add WeChatLow-grade phosphate ore is an important mineral resource for obtaining phosphorus. There are several types of phosphate ore, including sedimentary phosphate ore, igneous rock phosphate ore and metamorphic rock phosphate ore. The properties of each type of phosphate ore are different, so the ore selection process is also different. This article will mainly introduce the low-grade phosphate ore re-selection process method and process.
Jigging gravity separation is to separate mineral particles of different densities according to density under the action of vertical alternating water flow. For low-grade phosphate ore, due to the density difference between apatite and gangue minerals (such as calcite, clay minerals, etc.), when the slurry enters the jig, in the periodic up and down alternating water flow, the apatite particles with high density tend to be enriched in the lower layer, and the gangue minerals with low density are in the upper layer. When the water flow rises, the bed is loosened and the particles begin to stratify according to density and particle size; when the water flow falls, the heavy particles sink faster and the light particles are blocked in the upper layer, thus achieving the separation of minerals.
This method is suitable for processing low-grade phosphate ore with coarse grains and a large density difference between apatite and gangue minerals. The separation accuracy of fine-grained minerals is limited. For particles smaller than 0.5mm, the effect of jig re-selection will gradually deteriorate. For some ores with coarse apatite particles and obvious density difference with gangue minerals, jig re-selection can quickly and effectively remove most of the gangue minerals and improve the grade of the selected ore.
Shaking table gravity separation is to make the mineral particles fan-shaped on the inclined bed surface according to density and particle size with the help of horizontal water flow and vertical shaking. After the slurry is fed to the shaking table, under the action of the horizontal water flow and the inertial force and friction generated by the vertical shaking, the apatite particles with high density move to the concentrate end of the bed surface, and the gangue minerals with low density move to the tailings end. At the same time, fine-grained minerals are more easily washed away by the water flow, while coarse-grained minerals are relatively lagging, thereby achieving the separation of minerals of different particle sizes and densities.
This method has high sorting accuracy and can effectively sort low-grade phosphate ore with fine particle size (generally 0.037-2mm). However, the processing capacity is relatively small, the floor space is large, and the equipment investment is high.
Chute gravity separation uses the flow of slurry in an inclined chute to separate mineral particles according to density and size differences. When the slurry flows in the chute, the apatite particles with high density and large particle size are more likely to settle to the bottom of the chute and move forward along the bottom of the chute due to gravity and inertia, while the gangue minerals with low density and small particle size are carried by the water flow to the upper part of the chute and flow out of the chute faster. The separation effect of the minerals can be controlled by adjusting the slope of the chute, the roughness of the chute surface, the slurry flow rate and other parameters.
This method is only used as a roughing method for low-grade phosphate beneficiation, and is generally suitable for processing coarse phosphate ore larger than 2mm.
Ore preparation: The ore is first crushed. Generally, jaw crushers, cone crushers, etc. are used to crush large pieces of ore to a suitable particle size, usually 10-25mm, to meet the requirements of the jig machine. The crushed ore is screened to remove fine-grained materials to prevent them from interfering with the jig process.
Jig separation: The prepared slurry is evenly fed into the jigging machine, and the water flow parameters of the jig machine, such as water flow intensity, frequency, etc., are adjusted. During the jigging process, heavy minerals (apatite) sink to form bottom concentrate, and light minerals (gangue) form tailings on the upper layer. The concentrate and tailings are collected separately through the discharge device.
Concentrate treatment: The concentrate obtained by jigging may also contain a certain amount of gangue minerals, which needs to be further ground to further separate apatite from gangue minerals. Then other beneficiation methods (such as flotation, shaking table gravity separation, etc.) can be used for concentration to improve the grade of phosphate concentrate.
Ore processing: Firstly, it is crushed and ground. Crushing generally makes the ore particle size less than 2mm. Grinding further grinds the ore to -0.074mm, accounting for about 60%-80%. The slurry after grinding is classified to obtain products of different particle sizes, which are respectively sent to the shaking table for sorting.
Shaking table sorting: The classified slurry is fed into the shaking table, and the parameters such as the stroke, stroke frequency, bed slope and lateral water flow velocity of the shaking table are adjusted according to the properties of the ore. Under the action of the shaking table, apatite particles move to the concentrate end, and gangue minerals move to the tailings end, and the concentrate and tailings are collected separately.
Tailing reselection: The shaking table tailings may still contain some unrecovered apatite. Other gravity separation methods (such as chute gravity separation) or flotation methods can be used for reselection according to the situation to improve the recovery rate of phosphorus.
Ore processing: The raw ore is coarsely crushed to make the ore particle size less than 50mm, and then screened to remove fine-grained materials. Transport the qualified ore to the silo above the chute.
Chute sorting: Feed the ore evenly into the chute, control the slope of the chute (generally between 3°-15°), slurry flow rate and concentration and other parameters. In the chute, the heavy apatite particles settle to the bottom of the trough and move forward, and the light gangue minerals flow out of the chute with the water flow. The concentrate is collected at the bottom of the chute, and the tailings flowing out of the chute can be further processed or discharged. The concentrate obtained by chute gravity separation has a low grade, and generally requires subsequent use of other mineral processing methods (such as jigging gravity separation, flotation, etc.) to improve the grade of the phosphate concentrate.
In summary, there are various gravity separation process methods for low-grade phosphate ore, and different gravity separation methods have their own principles, characteristics and processing ranges. In practical applications, it is necessary to select a suitable gravity separation method or combine multiple gravity separation methods according to factors such as the type, mineral composition, and embedded particle size of low-grade phosphate ore, and design a reasonable beneficiation process to achieve effective utilization of low-grade phosphate ore resources and improve the grade and recovery rate of phosphate concentrate.
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