Abstract: With the increase in world demand for gold production, gold production scale continues to expand, bring to humanity and worsening environmental pollution, causing the majority of scientists engaged in gold extraction attention, study and have taken measures to control And actively develop new technologies with no pollution or less pollution to promote the application of gold clean production processes. This paper introduces the status of gold extraction and environmental management in China, and summarizes the progress of research on non-cyanide gold extraction technology at home and abroad, aiming to promote the development of China's gold clean extraction technology.
Key words: gold; extraction; environmental protection CLC number: X383 Document code: A
Article ID: 1005-7854(2000)01-0092-07
GOLD EXTRACTION AND
ENVIRONMENTAL PROTECTION
LUO Jia-ke
(Beijing General Research Institute of Mining and Metallurgy, Beijing 100044, China)
With the increased demand to gold in the world, the gold production is increased steadily, bringing, however, a much more serious environmental pollution to the human beings. The researchers undertaking gold extraction showed a great concern to this situation, studying methods of Treatment and developing the new technologies with no or little pollution to promote the application of clean gold extraction technology. To promote the development of the clean gold extraction technology, this paper described the domestic situation of gold extraction and putting environment under control, and progresses in The research on gold extraction without cynide, both at home and abroad.
KEY WORDS: Gold; Extraction; Environmental protection
1 Introduction China is a country rich in gold resources. Since the reform and opening up, especially after the 1980s, the annual production of gold in China has increased at an average rate of 10%. In 1999, China's annual gold output reached 169.1 t [1], second only to South Africa, the United States, Australia, and Canada, ranking fifth in the world.
As early as 4000 BC, China began its gold production activities [2]. After the founding of New China, China's gold production technology has made great progress. In the 1950s, the re-election method was adopted. In the 1960s, the mercury- mixing and flotation methods were mainly used. In the 1970s, the whole mud cyanidation method was adopted. The cyanide carbon slurry (CIP) method and the carbon leaching (CIL) method are mainly adopted and promoted. According to incomplete statistics, the current production of gold by cyanidation accounts for more than 60% of the total gold production in the country; there are still a large number of small and medium-sized enterprises that still use the amalgamation method to recover coarse-grained monomer gold for environmental belts. Came to pollution.
Like many countries in the world, China faces two major challenges in resource and environmental protection in the process of developing gold production. First, with the gradual reduction of gold resources in the province, it is necessary to develop new technologies to deal with poor and difficult gold resources. Second, with the increasingly strict requirements of environmental protection, especially after the promulgation of the "China Environmental Protection Law" in 1989, forcing enterprises to accelerate the study of clean production processes while controlling the environmental pollution of gold production, in order to promote the gold production technology Development in the direction of no pollution or less pollution.
2 Recycling of coarse-grained monomer gold and environmental protection
2.1 Re-election method Gravity sorting using the difference between gold and gangue density is the oldest method for people to recover gold from gold mines. Due to the low production cost of the re-election method and the low environmental pollution, it has been used up to now.
The re-election method plays an important role in the gold ore dressing in China. For the riverbed gold suitable for gold mining, depending on the nature of the ore, a single fixed chute process, a chute-jigging-shaker process or a three-stage jig process is used. The residual gold, slope product and alluvial sand gold are washed, agitated and choked, washed, centrifuged, and shaken-washed. The gold concentrate obtained from the gold mining or ship mining needs to be further selected by re-election, magnetic separation, electric selection or a combination of these methods, and the quality of the smelting by fire method is 85% to 92%. Finished gold. Table 1 lists the technical and economic indicators for mineral processing of some gold mining and ship mining in China.
Table 1 Technical indicators for gold ore dressing production [3]
Table 1 Technological indices of concentrating operation of placer gold
Project Rough plant capacity / selected plant capacity Original ore grade / recovery Gold color (m 3 .d -1 ) (m 3 .d -1 ) (gm -3 ) /% /‰
Rough selection, selection, smelting
Open pit mine 1 560 0.42 0.4844 68 97 98 897
Mining mine 2 480 1.0 0.6841 65 97 99 850
field
Mining Hill 3 1717 0.53 0.1929 85 98 99 920
Gold Boat Mine 4 1462 0.56 0.5228 81 95 98 920
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