Comprehensive recycling of copper tailings

As the amount of copper resources exploited continues to increase, the emissions from copper tailings are also increasing. Copper tailings are composed of fine powdery sand remaining after copper ore has been crushed and selected. It contains a large amount of re-selectable metallic ores and non-metallic useful components. Choosing a suitable re-selection process to recover them is of great significance to the comprehensive utilization of copper tailings resources.

A copper concentrator processes 185,000 tons of raw ore per year, with a copper recovery rate of 86.5%. There is still 13.5% copper remaining in the tailings, and a considerable part of the copper is lost in the coarse-grained tailings. Large-size, large-mass coarse particles are in It is easy to break away from the bubbles during the flotation process, so it is difficult for the plant to use the original flotation process and equipment to process copper ore.

In order to recover copper from the tailings generated by the original flotation circuit, laboratory tests were conducted, a tailings recovery system was established, and a two-step beneficiation process was determined. The first step of beneficiation only includes a roughing process, using two sets of CGF-40 flotation cells specially designed for coarse-grained minerals. The second step of beneficiation includes a roughing group, a removal group and two cleaning groups, which are designed to further process the foam products of the first step. Based on this circulation system, the effects of reagents and operating parameters on flotation results were also studied. Industrial test results show that the copper recovery rate of the entire recycling system is more than 20%, and the copper grade is 0.3% (equivalent to the copper grade of raw ore). It is estimated that 3,000 tonnes of copper can be recovered per year using this flotation technology.

Some tailings contain trace elements such as phosphorus, zinc, manganese, molybdenum, vanadium, boron and iron, which can not only improve soil quality and promote plant growth, but can also be used as soil conditioners or trace element fertilizers. At present, domestic products using tailings to prepare fertilizers mainly include phosphorus compound fertilizers, magnetically separated tailings compound fertilizers, molybdenum, manganese, zinc, ferrosilicon and other elemental micro-fertilizers, and mixed fertilizers. Certain alkaline gangue-based tailings containing calcium and magnesium components can be used to neutralize acidic soil, which not only provides mineral elements as nutrients, but also improves soil porosity and water retention properties to promote plant growth.

In addition, the silica in the tailings is calcined and turned into active silicon, which is absorbed by plants. Shenhong Group took advantage of the silica-rich characteristics of the Duobaoshan molybdenum mine tailings, obtained qualified silicon fertilizer through calcination, and added components such as calcium and magnesium, and carried out field trials on crops.