Construction of comprehensive treatment of mine solid waste

In recent years, with the rapid development of China's economy, the environment has been greatly damaged, we should adhere to the principle of economic development can not be at the expense of the environment, pay attention to environmental issues. One of the more important issues is the treatment of solid waste, and the main source of solid waste is the waste rock and tailings discharged by the mining industry, that is, the solid waste of the mine. Mine solid waste belongs to industrial solid waste, mainly refers to all kinds of mines in the construction of shafts and alleys, mining process, open pit mining process produced by the stripping and waste rock, and washing and smelting process produced by the tailings or waste slag.

The amount of stripping waste produced by mining in China is amazing, and the mining stripping ratio of mining is large, such as the mining stripping ratio of metallurgical mines is (2~4); The ratio of mining and stripping in straight mines is mostly 1: (2~8), and the highest is 1: 14. The maximum mining and stripping ratio of gold mines can reach 1:(10~14). The annual discharge of waste rock from mines in China exceeds 600 million tons, and the annual stripping of waste rock from open-pit iron mines alone reaches 400 million tons. The total amount of waste stone in our country has reached tens of billions of tons, which is the first country in the name of waste stone discharge.

The harm caused by solid waste is also very huge, mainly in the following aspects:

One is to pollute the environment around the mine. The minerals in the mine contain a large number of unknown pollutants before being treated, and the waste naturally contains excessive pollutants (such as radioactive elements, heavy metal elements, etc.). In the process of mine solid waste stacking, on the one hand, these pollutants will penetrate into the ground and pollute the surrounding soil and water sources; On the other hand, it will also react with other substances on the surface, forming new pollution. It is understood that in the total area of the land destroyed by mines in China, about 59% are destroyed due to the gob formed by mining,20% are occupied by open pit waste piles,13% are occupied by tailings ponds,5% are occupied by underground waste rock piles, and 3% are in the collapse danger zone. Among them, tailings and waste rock piles accounted for 38% of the total.

The other is soil erosion. Serious soil pollution will make the surface of the mine can not continue to grow vegetation, resulting in the surrounding soil increasingly loose, when the rain washed will form soil erosion. The third is to bring security risks. Mine waste is piled up in a disorderly manner, and the soil has become loose due to damage, so there may be a collapse or landslide phenomenon at any time. In recent years, the resulting disasters have occurred from time to time, such as landslide, debris flow, tailings dam break, etc., which not only destroyed the ecological environment, but also posed a serious threat to people's lives and property safety. On December 20, 2015, a huge landslide occurred at the Hongao Yu mud collection site in Guangming New District of Shenzhen, Guangdong Province, killing 73 people. After investigation, it was found that the main cause of the accident was the serious over-storage and ultra-high overfill in the receiving field, which led to this tragedy. In addition, due to the environmental deterioration caused by the stacked mine solid waste, the later restoration cost will also be greatly increased.

The fourth is the serious waste of resources caused by the massive discharge of mine solid waste. Mine solid waste often contains a variety of metal elements, if long-term stacking and loss, not timely recovery and comprehensive utilization, not only pollute the environment, but also for the national mineral resources is a great waste. The utilization rate of mineral resources in China is very low, its total recovery rate is 20% lower than that of developed countries, the average recovery rate of ferrous metal mining such as iron and manganese is only 65%, and the comprehensive recovery rate of non-ferrous metal mining in China is only 60%~70%. Taking iron ore as an example, there are more than 30 kinds of associated components in Chinese resources, but only 20 kinds can be recovered at present. Therefore, a large amount of valuable metal elements and available non-metallic minerals are left in solid waste, resulting in annual mineral resource development losses of about 100 billion yuan. Especially the old tailings, due to the restriction of the conditions at that time, the loss to the valuable group of tailings is greater. In 1997, the amount of gold mined in China was 25.4 million tons, the total recovery rate of gold was 86.46%, and about 18-20 tons of gold was lost in the tailings.

These are the main hazards of mine solid waste, it is like a time bomb, once activated, will cause a devastating blow to the environment. And this "bomb" is far from as simple as it seems, and its ingredients are extremely complex, so the actual consequences are far more than those listed. There is therefore an urgent need for action.