Phosphorus ore beneficiation process full analysis

Phosphate ore as an important chemical raw material, its beneficiation technology is directly related to the resource utilisation rate and economic benefits. With the ore quality gradually tends to poor, fine, miscellaneous, beneficiation process optimisation and innovation has become the core direction of industry development. The following from the mainstream process, systematic analysis of phosphorus ore dressing key technologies and their application progress.

First, flotation process: the core technology of efficient separation

Flotation is the most widely used and adaptable technology in phosphorus ore beneficiation, especially for low-grade gum phosphorus ore. According to the characteristics of the ore, flotation process can be divided into various types:

Direct flotation: direct enrichment of phosphorus minerals, applicable to ores with a single composition, but with limited effect on the sorting of ores with high magnesium, aluminium and iron impurities.

Reverse flotation: through the inhibition of phosphorus minerals, flotation impurity minerals (such as silicates, carbonates) to achieve separation, the effect on high magnesium phosphate ore is significant. For example, a low-grade colloidal phosphorus ore using reverse flotation process, the original ore P₂O₅ grade 27.33% increased to 37.34%, the magnesium oxide content down to 0.73%, recovery rate of 92%.

Combined positive-reverse flotation process: combining two flotation methods to remove different impurities in stages. By this process, the P₂O₅ grade of a gum phosphate ore was increased from 19.41% to 32.07%, with a recovery rate of 89.63%.

Double reverse flotation: for complex ores, step-by-step removal of silicon and magnesium impurities. Tests show that after double reverse flotation, the concentrate grade of the ore with 18.21% P₂O₅ grade is increased to 30.13%, and the magnesium content is only 0.93%.

Technological breakthrough: the development of new flotation chemicals (such as low-temperature trapping agent OT-8 and cationic desilicone agent CE-609) significantly improves the flotation efficiency and reduces energy consumption and cost.

Second，Scrubbing desliming process: simple and environmentally friendly physical sorting

This process is suitable for weathered or high mud content phosphorus ore, through mechanical scrubbing, desliming and screening to achieve enrichment. Its advantages are:

Simple process: no chemicals required, environmentally friendly;

Low cost: can be operated in the open air, suitable for surface weathered ores;

High-efficiency sorting: after scrubbing and desliming of weathered phosphate ore in a certain area, it can be directly used as raw material for high-concentration phosphate fertiliser, with an annual processing capacity of millions of tons.

Third, heavy media beneficiation: accurate sorting of large particles of ore

Heavy media cyclone is the core equipment of gravity beneficiation, using the mineral density difference to achieve separation, applicable to the strip structure is obvious, large particle size of the phosphate ore.

Technical highlights: the use of pressureless feeding three products heavy media cyclone, can simultaneously produce a variety of specifications of concentrate, high sorting efficiency;

Application case: a beneficiation plant through a coarse and a concentrate process to deal with banded phosphate ore, providing technical support for the comprehensive development of complex ores.

Fourth, roasting - digestion process: the solution for high carbonate ores

For phosphate ores with high carbonate content, high-temperature roasting (about 900 ℃) makes carbonate decompose into oxide, and then add water to digest to remove calcium and magnesium impurities.

Advantage: Magnesium content can be significantly reduced (removal rate up to 72%), and concentrate P₂O₅ grade can be increased to more than 37%;

Limitations: high energy consumption, complex operation, and the difficulty of by-product treatment, restricting its large-scale application.

Fifth,Chemical leaching and electrowinning: exploration of emerging technologies

Chemical leaching: the use of sulfuric acid and other reagents to dissolve impurities, but there is a high rate of loss of phosphorus minerals (15% ~ 30%), higher costs and other issues, is currently used for specific ore pretreatment.

Electrowinning technology: based on the difference in electrical properties of minerals to achieve dry sorting, high sorting efficiency and no wastewater pollution. Tests show that the original P₂O₅ grade 24.9% of the ore by the electrowinning, concentrate grade increased to 29.4%, recovery rate of 83.4%.

Sixth, the joint process: a comprehensive breakthrough for complex ores

For poor, fine and miscellaneous difficult to select ores, a single process is difficult to meet the demand, and the joint process has become a trend:

Combined re-election - flotation: reduce the amount of flotation through re-election pre-enrichment, reduce costs;

Combined magnetic separation-heavy separation-flotation: a low-grade phosphate ore (original ore P₂O₅8.33%) was treated by the combined process, and the concentrate grade was upgraded to 31.39%.

Future Prospect

Currently, flotation process is still the mainstream of phosphate ore dressing, but the development of high-efficiency chemicals and the optimisation of the combined process are the key to break through the difficult ore dressing. In the future, we need to further explore the technical route of low temperature, low consumption and high recovery rate to promote the development of phosphorus ore resources in the green and sustainable direction.