While the mineral processing industry was in its early years of development, most mineral processing plants adopted low-level management mode due to the limited economic level and ore beneficiation technology, which not only increased the amount of tailings discharge, but also caused mine resources waste. At the same time, with the gradual exhaustion of mine resources, and the development of mineral processing technology, the issue of tailings reprocessing technology becomes more and more outstanding. People realized that "useless" tailings contained the huge reused value, such as non-ferrous metals, ferrous metals and non-metallic minerals, etc. If abandoned, that's like monumental treasures were abandoned.
Up to now, the tailings storage in China has reached 8 billion tons and it is growing at an annual rate of 300 million tons per year. Among them, 2.6 billion tons of iron ore tailings and 500 million tons of gold tailings. According to statistics, the average grade of iron tailings is 10%, that is, there are at least 260 million tons of iron ore among the 2.6 billion tons of iron ore tailings. The gold content of gold tailings is generally 0.2-0.6g/ton, that is, that's about 300 tons of gold in 500 million tons gold tailings. Therefore, the tailings reprocessing technology not only greatly reduces the tailings storage and utilization rate, but also brings considerable economic benefits.
Taking Xinhai a gold ore dressing plant in Inner Mongolia as an example, this gold ore dressing plant has been established for nearly 40 years. As early as 2002, the tailings were up to 900,000 tons, the gold grade was about 1g/t. In order to make full use of the tailings resources and respond to the calling of "green mine" construction, this gold plant entrusted Xinhai to carry on tailings reprocessing plant. On the basis of the original 250t/d gravity separation process, Xinhai conducted a series of ore dressing experiments, and finally decided to use all-slime cyanidation CIP process. Through Xinhai wear-resistant slag slurry pump, the tailings were fed into NO. 1 ball mill a closed-circuit grinding (including NO. 1 ball mill and spiral classifier). The overflow was fed into the hydrocyclone, and formed a two-stage closed-circuit grinding with NO. 2 ball mill. In leaching adsorption process, Xinhai specially adopted negative oxygen machine to further enlarge the processing capacity and improve the beneficiation indexes. Then, the gold- loaded carbon was sent to the desorption electrolysis. Finally, the gold concentrate was obtained. Its comprehensive benefits was beyond the expected result. The main indicators were as follows:
|Ore||Leaching grade||Leaching rate||Recovery rate|
According to the preliminary investigation, the tailings volume (gold grade was more than 2.5g/t) was about 380,000 tons, which can be produced for 4-5 years. As a reasonable guess, 760kg gold can be recovered from these tailings, with a profit of over 70 million yuan.
Generally, the useful components in tailings were featured with the small amount of content, fine particle size and complex components, especially in some refractory tailings. Therefore, it is difficult to recycle useful components efficiently with traditional mineral processing technology and equipment. In view of the characteristics of tailings, innovations and breakthroughs in ore dressing technology must be made. And the key point is to save equipment investment, save energy and improve efficiency. Depending on more than 20 years of mineral processing experience, Xinhai adheres to customize technology and equipment according to different types and structures of ores. At the same time, corresponding to the actual situation of each mine, Xinhai will adopt the corresponding improvement, such as increasing reprocessing equipment to combine with the original process, building reprocessing plant, etc.
Nowadays, "green mines" construction has become an important direction for the whole mining industry. For the decreasing of mine resources and huge tailings base, the implementation of tailings reprocessing undoubtedly becomes a major way for mine comprehensive utilization, which not only protects the mine resources, but also brings considerable economic benefits for mining enterprise.