Due to the lack of ML/ARD regulations and guidelines in China’s mining industry, mine waste geochemistry studies are limited to the academic society funded by the government bodies. SRK China has recently completed a comprehensive literature review of these studies.
In general, Southern China due to higher rainfalls and warmer temperatures, has experienced more noticeable events of metal mining impacts. As a result, more research grants are biased towards that region.
Sulfur-bearing minerals are quite common among the identified mineral deposits in China, and the mining industry is criticized for the adverse effects of pollution. According to the data disclosed in journal articles, the pH values from some leachate were reported between 3 and 5, with As, Cd, Pb, and Zn concentrations far above the Chinese wastewater discharge criteria. Even worse, most farmlands nearby are irrigated with the polluted water, apparently causing soil contamination and producing toxic agricultural crops.
Some researchers have argued that soil contamination observed is natural, reflecting background anomalous levels of metals associated with mineralised rocks. However, evidence collected to date indicates that the high levels of Hg, As and Cd observed in southwest China is due to anthropogenic dispersion of metals due to poor mine waste management practices. SRK suggests that environmental regulations should be followed regardless: all relevant wastewater discharge criteria must be met before being discharged. It’s possible that mining activity could increase the naturally occurring contamination by two or three orders of magnitude, if no environmental protection measures are taken. Many of the studies published do not report sample methodology and/or collect a low density of samples. Therefore, the representativeness of samples is problematic, and the results could not be a direct indicator of pollution under natural site conditions.
According to SRK, a standard sampling program conducted by the academic society is critical, and the mining industry must continue it in the future.
Researchers conduct both static and kinetic tests, but all are generally at a bench scale test. The duration of a kinetic test is too short in general (usually two weeks maximum) to mimic the natural weathering and oxidation conditions, since pollution ML/ARD may not necessarily occur at that early stage. For example, a wastewater treatment facility operation could fail if the wastewater parameters are incorrectly estimated and applied. These results could mislead the mine waste management.
