During the process of fluorspar ore beneficiation and purification, if you encounter low concentrate grade and low ore recovery, it's essential to consider whether the grinding fineness is appropriate, as both overly coarse and overly fine fineness can impact the final concentrate grade. So, how can you adjust the grinding fineness of fluorspar ore? Here's a suggested approach.
The nature of this fluorspar ore is that it's quartz-type, with a single chemical composition, but fine crystallinity. The relationship between fluorspar and quartz is tight, showing a fine vein-intergrowth pattern. It falls into the category of challenging quartz-fluorspar ore.
In the grinding stage of this project, a two-stage grinding process was employed, with a grid-type ball mill in the first stage and an overflow-type ball mill in the second stage. The fineness of the ground ore at -200 mesh accounted for 60%, and it was unstable, resulting in unsatisfactory final concentrate grade and recovery rates. Therefore, improving the grinding fineness is necessary.
Considering the ore characteristics, the fluorspar ore beneficiation plant employed a two-stage grinding process, with regrinding of either the rougher concentrate or the middlings concentrate to achieve the separation of mineral monomers.
Research has shown that by reducing the processing volume and increasing the grinding in the existing first-stage grinding, the effects of a two-stage grinding process can be achieved. To improve grinding fineness, appropriate adjustments were made to the grinding classification system. This primarily involved changes in ball size ratios and an increase in the settling area of the spiral classifier.
Analysis of the instability in grinding fineness revealed factors such as insufficient depth in the discharge chute of the ball mill and low water input at the discharge point, leading to chute blockage.
Based on the ore characteristics of the fluorspar ore beneficiation plant, it was determined that the fineness of the ground ore at -200 mesh should be at least 75%. Thus, the discharge chute of the ball mill was lowered by 10-375px, and the water input at the discharge point was doubled. With the increased grinding fineness, the return sand volume of the spiral classifier also increased.
During the modification, strict control of the concentration of the ball mill was maintained, and additional water was introduced for sand return. To assess fineness more accurately, a 200-mesh analysis sieve replaced the original 100-mesh sieve, and a concentration bottle was added on-site to facilitate the relationship between fineness and concentration monitoring.
Through these improvements, the grinding fineness of the fluorspar ore reached -200 mesh at 75%, and the discharge fineness became stable. This resulted in a significant enhancement of the final concentrate grade and recovery rates. In fact, apart from grinding fineness, factors like pulp temperature, pH of the slurry, and the selection of flotation reagents can all affect the final beneficiation outcome of fluorspar ore. Identifying and addressing these issues one by one is key to resolving the challenges effectively.
