Phosphate rock

Phosphate rock is a general term for phosphate minerals that can be used economically, and is an important chemical mineral raw material. It can be used to produce phosphate fertilizers, and can also be used to produce yellow phosphorus, phosphoric acid, phosphide and other phosphates, which are used in medicine, food, matches, dyes, sugar, ceramics, national defense and other industrial sectors.

phosphate

Phosphate rock type

There are three types of phosphate rock in China: magmatic rock type apatite, sedimentary rock type phosphorite rock, and sedimentary metamorphic rock type apatite.

Magmatic rock type apatite:

The reserves only account for 7% of the total reserves, mainly distributed in the north. Its characteristic is that the phosphorus grade is low, generally less than 10%, and the low one is only 2~3%. Due to the coarser crystals and coarser embedded particle size, it is easy to beneficiate phosphate rock, the beneficiation process is simple, and the beneficiation index is high. There are also associated elements such as vanadium, titanium, iron, and cobalt, which can be comprehensively recovered, so this type of ore has better economic benefits.

Phosphate rock type

Sedimentary metamorphic apatite:

Its reserves account for 23% of the total reserves, mainly distributed in Jiangsu, Anhui, Hubei and other provinces. Under normal circumstances, due to weathering, the ore is loose and the mud content is high, and the qualified phosphorus concentrate can be obtained by scrubbing and desliming processes, and sometimes flotation process is also added. There are many mines in the Dianchi Lake area of ​​Yunnan using this process, and the production cost is low. Such mines are the phosphate mines with the greatest industrial value.

Sedimentary rock type phosphate rock:

It is the main type in all countries in the world. The reserves of this type of ore in my country account for 70% of the total reserves, mainly distributed in the central and southwestern regions. The five provinces of Yunnan, Guizhou, Sichuan, Hubei and Hunan account for 78% of this type of reserves, which can be said to be the hometown of phosphate rock.

The beneficiation method of phosphate rock

Commercial phosphorus is made from phosphate rock, which is enriched after mining. There are eight main ways for phosphate beneficiation, which are suitable for different types of rock phosphate, to improve the grade and quality of phosphorite.

beneficiation ways of phosphate rock

① Crushing and smashing

Reduce the particle size of the ore, so that the phosphorus minerals and the impurity minerals are dissociated. The phosphorus minerals and impurity minerals in the phosphate rock are often cemented together to varying degrees. Only when they are ground to a certain particle size, they can be dissociated. Depends on the particle size of phosphorus minerals and impurity minerals. This operation is often the basic step in phosphate rock enrichment.

Crushing

②Wash with water

It is used to separate fine ore particles, such as phosphate mud, clay ore and fine-grained quartz. Because the wet ore slime often adheres to the phosphate rock, sometimes a slime is formed, which must be dispersed by scrubbing before it can be separated. Water washing can also remove certain soluble substances, such as sodium chloride and free lime in calcined phosphate rock.

③Grading

Classification is often required after crushing and washing. Commonly used classification equipment is wet screen, hydrocyclone and spiral classifier.

Hydrocyclone

④Flotation

Using the different surface properties of phosphorus minerals and impurity minerals, using a flotation agent to float phosphorus minerals to achieve the purpose of separation, this operation is called positive flotation. The other is to float impurity minerals and sink phosphorus minerals, which is called reverse flotation. In order to make the separation more effective, it is often necessary to add inhibitors to inhibit the floating of certain minerals. The slurry containing phosphorus minerals obtained from the flotation machine can be thickened, filtered and dehydrated to obtain concentrate.

Flotation machine

⑤ Magnetic separation

The magnetic impurity minerals in the phosphate rock are separated and removed by a magnetic separator.

⑥Photoelectric separation

Using the different colors of phosphorus minerals and impurity minerals, photoelectric elements are used for identification, and the compressed air jet is controlled to separate the phosphorus minerals from the impurity minerals.

Thickener

⑦Calcination

It is used to remove organic matter, carbon dioxide and a part of fluorine in phosphate rock. The calcination temperature is 400-1400℃ according to different purposes.

⑧ Heavy medium separation

Using the different densities of phosphorus minerals and impurity minerals, select a medium whose density is between the two, so that one mineral floats in the medium and the other sinks to achieve the purpose of separation. The phosphate rock enrichment process depends on the specific situation. The enrichment process of Florida phosphate rock includes wet screen classification, desliming and flotation. The enrichment process of Moroccan phosphate ore includes crushing and classification, water washing, wet screening, desliming and dehydration.

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