Mine tailings are substances left after separating the valuable part of ore from the uneconomic part. Tailings are the unmined treasures. How to retreat tailings, maximum benefit?
Tailings are different from overburden, waste rock or other substances that cover ore or ore body and are replaced without treatment during mining. The tailings processing methods are varied by minerals, beneficiation methods, particle size, etc.
Tailings can be divided into the following types: hand-picking tailings, gravity separation tailings, magnetic separation tailings, flotation tailings, chemical beneficiation tailings, electrification tailings.
Why should we carry out the tailings retreatment process?
Usually, the ore tailings are stored in the tailings dam. The remaining toxic chemicals, wastewater and heavy metal ions in the beneficiation process will not only cause pollution and ecological damage to the surrounding environment but also increase the potential safety hazard of the tailings dam, may induce landslides, mudslides, tailings dam breaks, and other accidents, so tailings treatment has been highly valued.
Tailings processing methods
At present, tailings treatment has main three directions: tailings re-concentration, tailings dewatering, and tailings filling the mined-out areas. Below we will explain these three parts separately.
1. Tailings re-concentration
Although the content of useful components in tailings is relatively low, the use of advanced technology and reasonable process for re-treating of tailings can also recover the useful components in tailings to a greater extent, so that resources can be fully recycled and reduced. The final production of tailings will alleviate the pressure on the environment of the tailings.
Using the flotation process to treat tailings containing minerals such as colemanite, zinc oxide and apatite. Due to the development of new chemicals and new processes, some tailings with relatively simple processes, especially some old tailings, can recycle concentrate product by flotation process.
New gravity separation process
New gravity separation equipment can recover fine-grain minerals from tailings. Many traditional gravity separation equipment can separate fine-grained and ultra-fine tailings after being invented and perfected, such as vertical centrifugal concentrators, composite gold shakers, compound centrifugal concentrators, and so on.
Microbial treatment and leaching technology
This technology mainly uses the biochemical action of microorganisms to improve the tailings properties, and extracts harmful metal ions in tailings by means of microbial leaching or microbial mineralization to avoid environmental pollution.
2. Tailings dewatering process
In the mineral beneficiation stage, the slurry often contains much water. The high water content of the tailings is likely to lead to the tailing dam accident. Therefore, in the concentrating plant, tailings concentration and dehydration is also one of the important parts.
As a kind of equipment for solid-liquid separation using centrifugal force, the hydrocyclone has the characteristics of small area and high underflow concentration. This kind of concentration process mainly uses a hydrocyclone and a thickener to form a series or closed circuit to obtain high concentrate product.
The filter press is also used in the tailings treatment of gold mines. The method has the characteristics of low water content of the filter cake and the return of the filtrate. However, due to the low processing capacity of the single machine, it is difficult to scale the tail of the large-scale beneficiation.
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Tailings dry discharge
It is a new process using dewatering type cyclone, high-frequency dewatering screen and high-efficiency deep cone thickener. It can reduce the water content in tailings to less than 15%, and save costs, which can effectively avoid environmental pollution.
3. Filling the mined-out areas
The tailings filling the goaf is to refill the tailings waste back into the mined area to protect the terrain and reduce the cost of the tailings dam.
Tailings sand cement filling technology
The full tailings cement filling is mixed with cement, ash, etc. to form a filling aggregate with a hardness of 1~2 MPa, and the filling slurry is fed into the filling zone by the pipeline self-flow to achieve the purpose of filling the goaf.
Water consolidation sand filling technology
High-water consolidation full tail sand filling is similar to full tail sand cementing, except that high water materials are used as cementitious materials rather than cement. This method uses alumina, sulphoaluminate-based material and agglomerate, quicklime, and coagulant-based material, which are separately pulped and mixed, mixed before filling, and have a fast setting speed. Features.
The above three aspects are the three directions of tailings treatment. In the actual application of the concentrator, it is also determined according to the scale and investment of the plant. It is recommended to consult the concentrating equipment provider with the design qualification of the concentrator, and choose the suitable concentrator.