Overview of recycling gold and silver from waste materials

The work of recycling gold and silver from waste raw materials has received widespread attention from countries around the world in recent decades. Take the United States as an example. In the early 1980s, there were more than 1,200 companies engaged in the recovery of precious metals such as gold and silver. In 1974, 2,400 tons of regenerated silver was recovered from waste materials, which was 2.28 times that of minerals in that year. Recycled gold is 80.6t, accounting for 5% of the annual gold production. In 1978, 5,660 tons of silver was recovered from scrap and currency, ranking first in the world. There are more than 150 companies that recycle silver from photo-based waste in Japan, and 300-400 tons of silver is recycled every year. In order to reclaim precious metals from used raw materials, Johnson Matthey invested more than $14 million to convert the gold refinery in Brinsdown, England, into a precious metal recycling facility for waste materials in 1977. plant. The plant was commissioned in October 1979. It is the world's largest waste raw material processing plant and the processing center for waste precious metals in the Western world.

Recovering gold and silver from waste raw materials, due to the wide range of raw materials, complex types, and disparity in grades (from tens of percent to 90% or more), in order to reduce processing and reduce production costs, the primary problem Different raw materials are classified according to the shape, type and grade of the materials, so that different treatment methods can be selected according to different raw materials. The main types of gold, silver, and gold and silver-containing waste materials and important treatment methods are summarized in Tables 1 and 2.

Table 1 Types of major silver and silver-containing waste materials and important treatment methods