To address the key challenges of efficiently separating and recovering precious metals from waste printed circuit boards (WPCBs) and achieving a win-win outcome of economic and environmental benefits in the resource utilization of electronic waste, the following process is developed:

First, WPCBs are pulverized into particles via mechanical processing technology. The obtained particles are then separated into metallic and non-metallic fractions under the action of a high-voltage electrostatic field. After that, two liquid phase separation systems are constructed successively for the recovered metallic fractions: the Fe-Cu high-temperature liquid phase separation system and the Cu-Pb relatively low-temperature liquid phase separation system.

Next, by leveraging the selective partitioning rule of components in the WPCB metallic fractions in the aforesaid liquid phase separation systems, base metals and other non-ferrous metals are separated with high efficiency, while nearly all precious metals are enriched in the Cu-rich phase.

Subsequently, hydrometallurgical technology is adopted to separate and recover precious metals from the small amount of Cu-rich materials loaded with highly concentrated precious metals. This process can significantly reduce the consumption of chemical reagents during the separation and recovery of multi-component metals, and mitigate the ecological and environmental hazards posed by electronic waste.

The method for extracting gold from gold tailings comprises the following steps:

1)Mix gold tailings sand with water to prepare ore pulp;

2)Subject the ore pulp to ultrafine treatment to reduce the particle size to below 2 μm. A chemical reagent containing functional groups capable of forming coordination compounds with gold ions can be added either before or during the ultrafine treatment, so that the chemical complexation reaction proceeds synchronously with the ultrafine treatment; alternatively, the chemical reagent can be added after the ultrafine treatment to allow sufficient complexation reaction to complete;

3)Carry out solid-liquid separation and retain the liquid phase, which contains gold complex ions.

This extraction method boasts mild operating conditions, low production cost, low reagent consumption, fast extraction speed, and an extraction rate as high as 98%. Furthermore, the solid residue left after extraction can be further used to produce ceramic tiles, mineral admixtures for concrete and lightweight hollow wall materials. After drying, it can also serve as a filler for rubber or plastics, thus realizing full reutilization of resources and turning waste into wealth.

The process for recovering rare and precious metals via hydrometallurgical treatment of spent petrochemical catalysts falls into the technical field of hazardous waste treatment.

This process comprises a series of hydrometallurgical recovery procedures for rare and precious metals: slurrying, coarse grinding and ultrafine grinding leaching at ambient temperature, followed by subsequent steps including heated leaching, filtration and washing, platinum precipitation by cementation, and nickel recovery.

While improving the leaching efficiency of spent petrochemical catalysts, this process can shorten leaching duration, reduce energy consumption and lift the recovery rate of rare and precious metals. Meanwhile, waste gas is effectively treated, water is recycled, and a sound production environment is guaranteed.