What Are Tailings?

The part of the product of the sorting operation in the beneficiation that has a low content of useful target components and cannot be used for production is called tailings. Tailings are a treasure to be tapped. Experts believe that the current task of China's mining circular economy is to develop and utilize a large number of long-term tailings.

Chinese name: Tailings
Foreign name: Tailings

Explanation: Treasures to be tapped
Nature: mineral

1 Tailings 1 Introduction and Classification

One of the products of the sorting operation in beneficiation, the part with the lowest content of useful target components is called tailings. Under the current technical and economic conditions, it is no longer suitable for further sorting. However, with the development of production science and technology, useful target components may also have economic value for further recycling. Tailings are not completely useless waste, and often contain components that can be used for other purposes, which can be comprehensively utilized. Achieving no waste discharge is the need for mineral resources to be fully utilized and to protect the ecological environment.

Different types and different structures of ore require different beneficiation processes, and the tailings produced by different beneficiation processes often have certain differences in process properties, especially in particle morphology and particle gradation. The beneficiation process, the tailings can be divided into the following types: manual beneficiation tailings, heavy beneficiation tailings, magnetic beneficiation tailings, flotation beneficiation tailings, chemical beneficiation tailings, electrical beneficiation and photoelectric beneficiation tailings. It can also be classified according to the combination of the main constituent minerals in the tailings.

2 Problems caused by tailings 2

With the development of the economy, the demand for mineral products has greatly increased, and the scale of mining development has increased. The number of beneficiation tailings generated will continue to increase; coupled with the decline in the number of available metal ore grades, in order to meet the increasing demand for Demand, the scale of beneficiation is getting larger and larger, so the number of beneficiation tailings will also increase, and a large number of piled tailings will cause many problems to the mining, environment and economy.

(1) Mineral resources fees are serious. As tailings not only contain useful components such as reselectable metal ores and non-metallic ores, but also non-reselectable final tailings have many uses, the amount of useful components wasted in the tailings is considerable. .

(2) The storage of tailings occupies a large amount of land, and the storage investment is huge. Regarding the treatment of tailings at home and abroad, regardless of whether the useful minerals in the tailings have recycling value, they are mostly stored on the ground. The storage of tailings not only occupies a large amount of arable land, but also easily causes environmental pollution, water and soil loss, and vegetation damage in the mining area.

(3) Impact of tailings on natural ecological environment. The impact of tailings on the natural ecological environment is specifically manifested as follows: The tailings are easy to flow and leak when they are stored, causing vegetation damage and injury accidents, especially in the rainy season, which easily cause subsidence and landslides. The dam body of the tailings reservoir is high and there are hidden dangers of insecurity. Tailings components and residual ore dressing agents have severely damaged the ecological environment, especially heavy metal-containing tailings, in which sulfide produces acidic water to further leaching heavy metals, and its loss will cause harm to the entire ecological environment.

3 Recovery of tailings 3

1 Tailings (1) The value of tailings

For example, the tin polymetallic mine in Guangxi Nandan has 61 tailings ponds. The total amount of 25.22 million tons of tailings contains a large amount of non-ferrous metals tin, antimony, lead, zinc, silver, gold, indium, cadmium and non-metal The grades of arsenic, sulfur, etc. of the mine are above the national industrial grade indicators, and some have reached large or extra large scales, and the preliminary estimate of the scale has a resource of 3 billion yuan. With the help of new developments in beneficiation technology, recycling these metals is no less than building a new mine. The tailings of the Panzhihua Iron Mine in Sichuan contain dozens of beneficial components such as copper, nickel, titanium, and vanadium, which is equivalent to a large non-ferrous metal mine. Non-metal mines, such as coal gangue and other surrounding rocks, are also useful materials, and are wealth that has been excavated from the ground and gathered together.

2 Tailings (2) Tailings development and utilization measures

In order to further develop and utilize tailings resources, the following measures are recommended:

First, we must formulate and implement relevant policies to support enterprises in technological research and technological transformation; at the same time, implement preferential policies such as reduction and exemption of resources, taxes and fees, and guide and encourage social and corporate funds to invest in tailings and other resource utilization.

Second, we must strengthen technological innovation in comprehensive utilization of tailings, develop advanced technologies, advanced equipment, and advanced technologies, and accelerate the transformation of research results.

The third is to make good use of the central financial funds, focus on supporting the resource utilization of tailings and "waste" in large enterprises, large mining areas, and play a guiding and demonstration role.

The fourth is to strengthen the management of development access, formulate and improve the standards for access and supervision of mining development enterprises, promote the adjustment of corporate structure, and strengthen and expand mining enterprises.

The fifth is to strengthen the management of production safety in tailings development and utilization to prevent accidents in production safety.

3 Tailings (3) Mine tailings recovery development prospects

China is in the stage of accelerated industrialization and urbanization, with large consumption of mineral resources and a high degree of dependence on foreign countries. However, the global price of mineral products has continued to rise, increasing the production costs of enterprises that require mineral products, and at the same time increasing the pressure on resource security.

Under the situation of tight supply of global mineral resources, developed countries around the world have discovered that the residues and tailings left after processing and utilization of mineral resources contain business opportunities for secondary utilization. China is a big mining country, and the long-term accumulation of a large number of tailings can be developed and utilized, which can not only turn waste into treasure, but also effectively alleviate pressure on resources and the environment.

Tailings are "waste" discharged by mining enterprises under certain technical and economic conditions, but at the same time they are potential secondary resources. When technical and economic conditions permit, effective development can be carried out again.

After the ore is sorted and comprehensively processed, its main useful components are enriched into concentrates, and other residues are called tailings. The content of the main useful components in the tailings is called the tailings grade. It is an important parameter for selecting an economical and reasonable beneficiation scheme and evaluating the selectivity of the ore.

4 Tailings (4) Tailings recovery equipment

Tailings recovery machine

An energy-saving and high-efficiency beneficiation equipment used for the recovery of tailings in the process of magnetite, without the loss of ore powder and the effective utilization of effective resources. With the development of production technology in the society's beneficiation equipment industry, the slogan of green, high efficiency and energy saving is coming out, and green environmental protection and energy saving are imperative. Therefore, the role of tailings recovery machine is particularly important. High-efficiency tailings recovery machine can not only effectively curb pollution behavior, but also can greatly reduce production costs and greatly improve production efficiency. It has the characteristics of low input and high output.

Tailings sludge dewatering machine

The best choice for tailings dewatering --- belt sludge dewatering machine, large processing capacity, low energy consumption, save labor, tailings sludge dehydration has become necessary work for the next step of tailings.

Tailings recovery equipment is the latest machinery used in tailings production and recycling in China's recent beneficiation (iron) ore industry. Its production method: It is mainly to re-clean and recycle the waste from the beneficiation of mining equipment. The recovery rate has reached a new level. It has a single machine production and a unique method. It has saved national mineral resources to the limit. The equipment is characterized by excellent materials, reasonable design structure, convenient operation and high economic return rate.

4 Tailings 4 Tailings Treatment

Tailings processing technology

The waste slag discharged by mining enterprises after the beneficiation is mostly discharged in the form of mud, which forms a tailings pond over time. How to deal with tailings?

At present, tailings are generally treated as filling material for underground mining mined-out areas, that is, water-sand filling materials or cement-filled aggregates; or some directly cover the tailings dump with soil for farming, planting crops, or planting trees. afforestation. In fact, the most economical treatment method for tailings is tailings sand and raw materials for building materials. For example, processed tailings can be used as cement, tile, aerated concrete, permeable bricks, refractory materials, fire insulation materials, glass, For raw materials such as ceramsite and concrete aggregates, tailings sand can replace a part of the machined sand for making concrete, building roads, and pavement materials ^[1] .

The comprehensive utilization of tailings resources at home and abroad can be summarized as the following ways:

(1) First of all, the comprehensive recovery and utilization of the useful components of tailings resources should be done as far as possible, and the tailings should be re-selected using advanced technology and reasonable processes to maximize the recovery of useful components in the tailings, which can further reduce the tailings. Quantity. Some beneficiation plants develop in the direction of non-tailings.

(2) The tailings are used as filling material in the underground mining goaf, that is, water sand filling material or cement-filled aggregate. The tailings are used as filling material in the goaf. The most ideal filling process is the full tailings filling process, but it is still in the experimental research stage. In production, the coarse-grained part of the tailings is used as the filling material in the goaf. The tailings from the beneficiation (belt conveyor) plant are discharged and sent to the tailings preparation section for classification. The coarse sands are sent to the underground goaf, and the fines are entered into the tailings storage. This tailings treatment method has been applied at home and abroad.

(3) Using tailings as raw materials for construction materials: making cement, silicate tailings bricks, tiles, aerated concrete, cast stones, refractory materials, glass, ceramsite, concrete aggregates, glass-ceramics, molten slag tiles , Foam glass and foam materials.

(4) Use tailings to build roads, pavement materials, non-slip materials, and coastal land.

(5) Cover the tailings dump with soil for farming, plant crops or afforestation.

(6) The tailings pile is stored in a specially built tailings storage. This is the most widely used tailings treatment method in most ore dressing plants.

Tailings pond water treatment technology

Water treatment technology: The tailings pond is a large-volume sedimentation-storage pond. It can be set up on the valley, sloping land, river beach, or flat land by the terrain and surrounded by dams. Drainage wells and drainage pipes are set up in the pond, or drainage ditches are set up along the edge. The tailings water is clarified and purified and overflows in the pond. The suspended matter in the tailings water is deposited at the bottom of the tank for storage. Wastewater stays in the pond for at least one day and night. This method can effectively remove suspended matter in wastewater, and the content of heavy metals and flotation reagents is also reduced. The longer the residence time, the better the treatment effect. The overflow water of the tailings pond can be recycled. Gravity separation, magnetic separation, and simple flotation of a single metal ore do not require high water quality, and the water cycle utilization rate can reach 80%, or it is not drained at all. When the tailings particles are extremely fine and partially colloidal, a coagulant can be added to the tailings water to speed up the clarification process and improve the treatment effect. If lime is added to tailings water, 60 to 70% of xanthate and black medicine can be removed.

If the supernatant of the tailings pond fails to meet the discharge standards, it should be further processed.

Frequently used treatment methods include: Lime neutralization and roasted dolomite adsorption can be used to remove heavy metals. To remove 1 mg of copper requires 0.81 mg of lime, 1 mg of nickel requires 0.88 mg of lime, and the pH is required to be controlled above 8.5. Adsorption with roasted dolomite with particle size less than 0.1 mm can remove copper and lead ions. The removal of 1 mg of copper requires 25 mg of dolomite, and 1 mg of lead requires 2.5 mg of dolomite. The ore adsorption method is used to remove the flotation agent. Lead-zinc ore can be used to adsorb organic flotation agent. To remove 1 mg of organic flotation agent, 200 mg of lead-zinc ore is required. Treatment with activated carbon adsorption is more effective, but expensive. The cyanide-containing wastewater mainly adopts chemical oxidation methods, such as bleaching powder oxidation method; cyanide can also be removed by ferrous sulfate lime method and lead-zinc ore method. Adding 200 grams of ore per gram cyanide can remove about 90% of simple cyanide, or compound cyanide Chemicals are about 70%. High-concentration cyanide-containing wastewater can recover sodium cyanide ^[2] .