As silver ore resources are continuously mined, the reserves of singular silver ore and gold-silver ore are gradually diminishing. To meet the rising market demand, lead-zinc-copper-associated silver ore has become another focal point of development. In order to achieve ideal technical and economic indicators for comprehensive ore recovery, efforts have been made to strengthen the study of silver mineralogy, continuously improve ore processing procedures and chemical regimes.
This ensures that the ore selection indicators of lead, zinc, copper, and other sulfide minerals are maintained at the original level or enhanced. The recovery rate of associated silver has increased from 30%-50% to 60%-80%, and both the production yield and the technical level of comprehensive recovery have seen significant improvement.
Currently, flotation is a common method for selecting lead-zinc-copper-associated silver ore. It involves selecting based on the technological conditions and chemical regimes of the main metals, without producing a singular silver concentrate. Typically, silver is enriched in lead, zinc, and copper concentrates, which are then recovered through smelting.
Due to the complex mineral composition of lead-zinc-copper-associated silver ore, with varying associations, embedding characteristics, and oxidation levels, the effectiveness of ore selection varies significantly. Through continuous research, several feasible methods to increase the recovery rate of associated silver have been identified:
Various silver minerals in lead-zinc-copper polymetallic ores often exist as finely dispersed particles with close associations. The current grinding conditions are primarily designed to recover lead, zinc, and copper sulfide minerals, making it difficult to fully dissociate silver minerals. To improve the recovery indicators of associated silver, it is necessary to reform the original grinding process and enhance grinding fineness.
Of course, the selection of grinding processes and fineness should consider not only technical feasibility and scientific principles but also economic rationality.
In the flotation process, reducing or eliminating cyanides that inhibit silver minerals or carrier minerals is beneficial for the recovery of associated silver. This approach has been widely recognized and applied in over 60% of lead-zinc-copper mines, showing satisfactory results.
In the past, flotation of lead-zinc polymetallic sulfide ores in China often used collectors such as yellow medicine (ethyl, butyl) and black medicine (No. 25, No. 31). In recent years, butyl ammonium black medicine has gradually become one of the main collectors in the flotation of lead-zinc polymetallic sulfide ores. It not only exhibits good selectivity but also demonstrates strong collecting ability for silver minerals. Additionally, the combination of butyl ammonium black medicine with yellow medicine, ethyl xanthate, esters, and other collectors has shown good effects on improving the ore selection indicators of associated silver, lead, zinc, etc. This combination has been widely applied in flotation practice.
The selection of ore processing procedures should consider both the high selection indicators of the main metals lead, zinc, copper, and the comprehensive recovery of associated silver, ensuring the maximum recovery of useful minerals.
For silver-containing lead-zinc polymetallic sulfide ores, if the embedding characteristics of associated silver are considered, adopting a mixed flotation or partially mixed flotation process is advantageous for the comprehensive recovery of associated silver. However, the determination of the flotation process depends on various factors, guided by ore properties. Therefore, each processing plant should gradually improve existing procedures based on ore selection test results and repeated production practices.
For ores predominantly composed of silver, a heavy flotation combined process or a single flotation process is often employed to concentrate silver minerals, which are then further processed using chemical methods.
With the continuous depletion of silver ore resources and the gradual increase in silver demand, the trend of recovering silver from lead-zinc-copper-associated silver ore is becoming more evident. By employing the above-mentioned four methods, silver recovery rates can be increased to 60%-80%. It is believed that with the gradual development of ore selection technology, better results can be achieved in the future, further enhancing ore selection recovery rates.
