Flotation of Galena: The Key Technology for Unlocking Silver-Lead Resources

In the field of mineral resources, galena is an important mineral for extracting lead and silver, and its flotation process has attracted much attention. Galena often coexists with various minerals. Moreover, 80% of China's silver mineral resources are associated with non-ferrous metal deposits such as lead. Ag-bearing galena has become one of the main sources of silver. In-depth research on galena flotation is of great significance for improving the utilization rate of silver-lead resources.

The flotation process is an effective method for treating sulfide ores such as lead-zinc ores. For the flotation of galena, there are multiple processes to choose from. The preferential flotation process takes advantage of the difference in floatability of different sulfide ores. It first collects galena and then processes the tailings, which is suitable for ores with simple composition and high grade. The bulk flotation process simultaneously collects lead, zinc, and associated silver ores to form a bulk concentrate for subsequent separation. It is often used in scenarios where the ore has fine dissemination and low grade. The equal-floatability flotation process classifies and floats minerals based on their natural floatability, showing good adaptability to mineral surface properties. The asynchronous flotation process and the branch flotation process also have their own characteristics, which can achieve better beneficiation indexes according to ore properties and smelting requirements.

Flotation reagents play a crucial role in the flotation of galena. Collectors are an important type among them. Commonly used collectors include black reagents, xanthate reagents, and dithiocarbamate reagents. Ammonium dibutyl dithiophosphate (ADD) has a good collection effect on Ag-bearing galena under weakly alkaline conditions. Diethyldithiocarbamate (DDTC) can also function under strongly alkaline conditions, but its overall effect is slightly inferior to that of ADD in a weakly alkaline system. Depressants are used to suppress minerals such as sphalerite. Common depressants include inorganic depressants, organic depressants, and combined depressants. Selecting the appropriate depressant can enhance the separation effect of lead and zinc. Copper sulfate is a commonly used zinc activator that can improve the recovery of zinc.

The flotation test of actual ores is an important link to verify the effectiveness of the flotation process and reagents. Taking a silver-rich lead-zinc sulfide ore as an example, through the study of process mineralogy, the contents, occurrence states, and mineral compositions of lead, zinc, silver, and other elements in the ore were determined. On this basis, tests such as grinding fineness tests, collector and regulator type and dosage tests were carried out. Finally, the optimal flotation conditions were determined: the grinding fineness was -0.074mm accounting for 80%, ADD was used as the collector, sodium carbonate was used as the regulator, and zinc sulfate was used as the depressant. The lead-preferential flotation process was adopted. After a full-process closed-circuit test, a lead-silver concentrate with a lead grade of 72.76%, a lead recovery rate of 83.75%, a silver grade of 3,978.16 g/t, and a silver recovery rate of 83.28% was obtained, as well as a zinc concentrate with a zinc grade of 48.98% and a zinc recovery rate of 82.32%, achieving efficient recovery of silver-lead resources.

With the development of science and technology, galena flotation technology is also constantly innovating. By means of Zeta potential measurement, adsorption capacity measurement, thermodynamic calculation, and calculations and simulations based on density functional theory, the interaction mechanism between collectors and the surface of Ag-bearing galena has been deeply studied, providing theoretical support for optimizing the flotation process and reagent selection. In the future, galena flotation technology will develop towards a more efficient and environmentally friendly direction, further improving the comprehensive utilization level of silver-lead resources.