Phosphorus is an important strategic mineral resources in China, it is an important material of phosphate fertilizer production, food security, but also the material basis of fine phosphate chemicals, irreplaceable, non-renewable. Facing the challenges of the scarcity of phosphate rock resources in the world, comprehensive analysis, judgment and grasp of the status quo and future of phosphate rock resources in China are of great significance to China's phosphate fertilizer industry and sustainable development of agriculture.
China's phosphate rock resources economic reserves of 6.6 billion tons, ranking first in the world. However, this reserve contains a large number of low-grade ores that cannot be directly used for industrial production. Except for a few rich ore, which can be directly used as raw materials for the production of high-efficiency phosphate fertilizer, most of the ore needs to be used for mineral processing .
I. Current status of phosphate ore sorting process
In recent years, the research and development of national phosphate ore dressing is relatively fast, and it is closer to foreign countries in terms of sorting technology, and its technology and experience are relatively mature. According to the optional properties of different phosphate ore, flotation process and heavy medium beneficiation process are currently used.
(1) Flotation process of phosphate rock
1. Positive flotation process
The positive flotation process is suitable for sorting siliceous phosphate rock, using Na 2 SiO 3 to suppress silicate minerals and using positive flotation process of anion collector positive float phosphate minerals, the sorting effect is better, such as Ningxia Helan Mountain Mine, the process flow is shown in Figure 1. Sedimentary metamorphic silicon-calcium phosphate is an easy-to-float apatite type phosphate rock. It uses Na 2 CO 3 and Na 2 SiO 3 to suppress silicon and calcium minerals. The anion collector is directly flotation of apatite. Flotation process, for raw ore containing P 2 O 5 8.O%, through this process can obtain good indicators of phosphorus concentrate P 2 O 5 grade greater than 35%, phosphorus recovery rate of 83%, such as Hubei Dawu County Huangmailing Concentrator .
Figure 1 Siliceous phosphate rock flotation process
2. Positive and negative flotation process
Reverse flotation process for sorting calcium phosphate deposition, add Na 2 CO 3, Na 2 SiO 3 and other inhibiting silicate, anionic collector flotation of phosphate and calcium magnesium carbonate minerals, and The pH is adjusted to 5.5-6.0 with H 2 SO 4 or H 3 PO 4 to inhibit the phosphate, and the anion collector reverse flotation of the carbonate mineral, so that the P 2 O 5 content of the phosphate concentrate can be increased to 35.17. %, MgO reduced to 0.78%, R 2 O 3 1.97%, phosphorus recovery rate of 91.98% of good mineral processing indicators, such as Guizhou Yanfu phosphate mine, the process flow is shown in Figure 2.
Figure 2 Process of sedimentary calcareous phosphate ore-reverse flotation
3. Double reverse flotation process
The double reverse flotation process is suitable for the most difficult colloidal phosphate rock in phosphate ore. The process first uses H 2 SO 4 or H 3 PO 4 to inhibit phosphorus minerals, and anionic collector reverse flotation dolomite and other carbonates. After the mineral is removed, the slurry is de-slurried and then the silicate mineral is reversely floated with a cationic collector. The process flow is shown in Figure 3. However, further research is needed on high-efficiency cation collectors and beneficiation processes, such as Yichang Phosphate Mine and Jingjing Phosphate Mine in Hubei.
(2) Heavy medium cyclone separation process for phosphate ore
The heavy medium cyclone sorting process is suitable for siliceous phosphate rock. Yichang Phosphate Mine is a marine chemical deposited phosphate rock deposit. The ore industry type is mainly siliceous calcium phosphate. The structure of the ore is mainly strip-shaped, the strip of phosphorus in the ore is wide, the hardness difference between the phosphorite and the gangue strip is large, the joint surface is not tight, and it is easy to dissociate. When the ore is broken to -15mm It can achieve more than 90% of the monomer dissociation of the phosphorite strip, which is suitable for heavy medium dressing. When the P 2 O 5 grade of the ore is 22.05% and the MgO content is 2.85%, the final phosphate concentrate P 2 O 5 grade is 28.06%, the MgO content is 1.67%, and the P 2 O 5 recovery rate is obtained by heavy medium. It is 87.64% and the yield is 68.82% of the ore dressing index. For example, the beating process of Huaguoshu Heavy Medium Plant is shown in Figure 4.
(III) Comparison of phosphorus ore flotation process and heavy medium beneficiation process
Advantages and disadvantages of phosphate ore flotation process and heavy medium beneficiation process:
1. The advantages of phosphate ore flotation process are high grade of concentrate, low recovery rate and high cost of mineral processing. The disadvantages are complicated process system, high cost of dewatering of crushed grinding and products, and pollution of industrial wastewater flotation agent to natural environment. .
2. The advantage of the heavy medium beneficiation process is that the process system is simple, the cost of crushing and product dewatering is low, and the industrial wastewater flotation agent has little pollution to the natural environment. The disadvantages are low concentrate grade, low recovery rate and low ore dressing cost.
Second, the prospect of phosphate ore sorting process
At present, the phosphate ore flotation process and the heavy medium beneficiation process which can be applied to actual industrial production have their own advantages and disadvantages. In order to make the scientific and economic rational and efficient separation of phosphate rock, the heavy medium beneficiation-flotation process is recommended. That is to say, the heavy medium beneficiation process is selected for the rough selection of the phosphate ore suitable for re-election, and the phosphorus ore is selected by flotation, and the process flow is shown in Fig. 5.
Third, the conclusion
The heavy medium beneficiation-flotation process is to use the heavy medium beneficiation to sort out part of the tailings in the coarse-grained coarse selection of phosphate rock, which can reduce the cost of tailings treatment in flotation operation and reduce the cost of ore dressing. For the current mineral processing equipment, the most rational sorting process for phosphate rock needs to be further studied and finally applied to industrial production.
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