In recent years, with the continuous deepening of fluorite mining, the proportion of high-quality fluorite is getting lower and lower. Currently, low-grade fluorite is mainly mined, and quartz-type low-grade fluorite is one of them. This type of mineral mainly includes fluorite and quartz, and also contains a small amount of calcite, barite and sulfide. So what is the beneficiation method and process flow of this quartz-type low-grade fluorite?
The key to the separation of this type of fluorite ore is to reduce the silicon content of the concentrate, because in order to separate quartz from fluorite, it is necessary to dissociate the quartz and fluorite monomers through grinding. This type of fluorite ore can be divided into two types according to the characteristics of the useful mineral embedding: coarse-grained embedding and fine-grained embedding.
Fluorite with coarse-grained embedding is easy to select. It uses fatty acid collectors, sodium carbonate as the slurry adjuster, and water glass as the quartz inhibitor. High-quality fluorite concentrate can be obtained through a one-coarse-multiple-fine flotation process.
Quartz-type fluorite with fine-grained embedding requires intensive grinding, and a process flow of stage grinding and stage separation is adopted.
(1)Adjuster
The main function of the pulp adjuster sodium carbonate is to adjust the pH value of the pulp and create a suitable chemical environment for the subsequent flotation process. At a suitable pH value, the difference in floatability between fluorite and quartz increases, which is conducive to flotation separation.
(2)Depressant
Quartz depressant water glass can selectively adsorb on the surface of quartz, reduce the floatability of quartz, thereby reducing the mixing of quartz in fluorite concentrate and improving the quality of concentrate.
(3)Collector
In terms of collectors, fatty acid collectors have good selectivity and collection ability for fluorite, which can make fluorite particles adhere to bubbles and float to the surface of the pulp. As a fluorite low-temperature flotation collector, ZN136 has low-temperature resistance and can achieve good flotation effect at a lower temperature, eliminating the huge boiler investment required for heating and the high energy consumption and environmental pollution caused by coal burning, greatly improving the economic benefits of the enterprise.
The beneficiation methods of quartz low-grade fluorite ore mainly include hand selection, gravity selection and flotation, among which flotation is widely used. For this type of fluorite ore, the beneficiation process usually includes the following steps:
Crushing: First, the raw ore is crushed to a certain particle size, usually below 25-30mm, for subsequent beneficiation.
Grinding: The crushed ore is ground to achieve the monomer dissociation of fluorite and gangue minerals. The grinding fineness has a great influence on the flotation index of fluorite, and the appropriate grinding fineness needs to be determined through experiments.
Classification: The slurry after grinding is screened and graded to separate ore particles of different particle sizes.
Floatation: Flotation is a key step in the beneficiation of quartz fluorite. Sodium carbonate is usually used as a pH adjuster, fatty acids as collectors for fluorite, and water glass as a depressant for quartz. The flotation process may include a roughing process, multiple cleaning and scavenging processes, and the return of the middlings. During the flotation process, the flotation effect is optimized by adjusting the pH value and temperature of the slurry, as well as the dosage of collectors and depressants. (If necessary, the stage grinding and flotation process can be used)
Cleaning: In order to improve the grade of fluorite concentrate, multiple cleaning processes may be required to remove residual gangue minerals and improve the purity of fluorite.
Dehydration: The fluorite concentrate after flotation needs to be dehydrated to reduce the moisture content for easy transportation and further industrial application.
Drying: The dehydrated fluorite concentrate usually needs to be dried to obtain the final dry product.
The design of the entire process needs to be determined according to the specific properties of the fluorite ore and the beneficiation goals to ensure that high-grade and high-recovery fluorite concentrates are obtained. For low-grade fluorite ores, flotation can effectively improve the grade of fluorite to meet the requirements of industrial applications.
A quartz-type low-grade fluorite mine in Hunan has a grade of 30%. The main gangue minerals are quartz, followed by calcite, feldspar, mica, etc. The roughing grinding fineness is -200 mesh, accounting for 42.52%. Water glass + ZN608 is used as an inhibitor, fluorite low-temperature collector ZN136 is used as a collector, 1 roughing, 1 sweeping, 7 fine, fine 1 concentrate regrinding, and the closed-circuit process of the middle ore is returned in sequence. Finally, a fluorite concentrate with a CaF2 grade of 97.45% and a recovery rate of 92.71% is obtained.
A fine-grained quartz-type fluorite mine with a fluorite content of 32.75%. The fluorite and quartz inlay relationship in the ore is complex, and the inlay particle size is fine. The process of one roughing, one sweeping and seven cleaning is adopted. The tailings of the selected intermediate ore are directly discarded, and the selected flotation concentrate is regrinded and floated again. ZN136 is used as the fluorite low-temperature flotation collector. Under the condition of slurry temperature of 5~10℃, the ore dressing index obtained in the laboratory is fluorite feed CaF2-32.52%, CaF2-97.55%, SiO2-1.36% in the concentrate, and the fluorite recovery rate is 76.67%; under the condition of slurry temperature of 5℃, the industrial production index is fluorite feed CaF2-30.14%, CaF2-97.37%, SiO2-0.81% in the concentrate, and the fluorite recovery rate is 89.67%.
In short, for quartz-type low-grade fluorite ore, flotation is a common and effective ore dressing method. The key to flotation is to reduce silicon in the concentrate. The specific flotation process needs to be selected according to the coarseness of the embedded particle size. Xinhai Mining can tailor beneficiation solutions according to the specific characteristics of the ore. If you have any needs in fluorite beneficiation, please contact us.
