Hg-ore Gravity selection+flotation process

At present, there are more than 20 known types of mercury minerals in nature, and the main ones with mining value as industrial raw materials are cinnabar and black cinnabar; Chensha rich ore can be directly smelted in the furnace, while lower grade ore needs to be enriched through beneficiation before entering the smelting process. At present, most ore dressing plants use single flotation and heavy flotation combined processes, and a few individual mines still use manual selection.

Gravity selection flotation process

The heavy flotation combined beneficiation process is widely used in mercury ore beneficiation plants. In China, the vast majority of cinnabar products come from mercury ore beneficiation plants using this process. In mercury ore heavy flotation combined beneficiation plants, tailings are generally not discarded during the heavy beneficiation stage. Instead, the tailings after heavy beneficiation are overflowed, dehydrated, graded, and re ground before finally using flotation technology. Otherwise, it will affect the total recovery rate of mineral processing. For a single sand type mercury ore, both experimental and production practices have shown that the recovery rate of single flotation is slightly higher than that of heavy flotation combined process. Moreover, a single flotation plant requires less infrastructure investment and lower production costs. Therefore, the selection plant that adopts the heavy flotation combined process is often due to the needs of ore properties (such as recovering natural mercury), or for the production of cinnabar. At present, there are two types of production processes in domestic beneficiation plants that use the heavy flotation combined process. One type is multi-stage grinding and multi-stage shaking table selection. Before shaking table selection, hydraulic classification is carried out, and the classification overflow and shaking table tailings are sent to flotation after dehydration, classification, and regrinding. This type of process is suitable for ores with fine particles embedded in Chensha, and the ore contains a large amount of high-density minerals such as pyrite. Its advantage is that it can recover as much cinnabar as possible during the re selection process. Based on the mercury content in the produced cinnabar, the re selection recovery rate can reach 40% to 60% [the original ore grade is around 0.3% to 0.5% (Hg)]. The disadvantages of this type of process are high water and electricity consumption, high production costs, and significant infrastructure investment. Moreover, the re selected tailings need to be dehydrated before entering the lower stage of re grinding and flotation operations, and some fine cinnabar particles are lost due to floating with overflow water, reducing the total recovery rate of mineral processing. Another type of process is to roughly grind the crushed ore through a rod mill, and the products are not classified (wide grade), but are sorted by a high concentration shaking table. This process is suitable for ores with coarse particle size and relatively simple composition embedded in cinnabar. Its advantages are simple process, low water and electricity consumption, and the dehydration process can be omitted between heavy and floating operations. Therefore, the production cost is low, the infrastructure investment is small, and the total recovery rate of mineral processing is high. The drawback of this type of process is that the recycling rate of reselected jobs is lower than that of the previous type of process. Calculated based on the mercury content of the finished cinnabar, the re selection recovery rate is 30% to 40%

Process characteristics 

high comprehensive recovery rate and high concentrate grade.

Typical beneficiation plant

Guizhou mercury ore dressing plant, the deposit is a low-temperature hydrothermal layered integrated type deposit, with the main metal mineral being cinnabar, accompanied by small amounts of pyrite, antimonite, sphalerite, and natural mercury; The main gangue minerals are dolomite, as well as a small amount of quartz, calcite, and sericite. The specific process is as follows: