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Tailings are also useful, recycling, turning waste into treasure

16/07/2020

China is a large country of mineral resources, and the accompanying mine waste rock and tailings are also huge. A large number of tailings piled up not only seriously pollute the environment, but also pose a great hidden safety hazard. As everyone knows, tailings are also a resource and have great potential value. After being processed, tailings waste rock can become high-quality aggregates, "turning waste into treasure", bringing huge investment returns to the mine.

Tailings recycling and sand making are common and well-known, but they are only a small aspect of the comprehensive utilization of tailings. The comprehensive utilization of tailings mainly includes two aspects: one is the tailings as a secondary resource re-election to recover useful minerals; the second is the direct use of tailings for filling and mining, road construction, preparation of organic fertilizers and building materials. It is also possible to combine the two to jointly utilize tailings, that is, to first comprehensively recover valuable components in the tailings, and then directly use the tailings to achieve comprehensive utilization of the tailings.

1. Aggregate

Tailings sand making is one of the simple and feasible schemes for comprehensive recycling of tailings. Sand and gravel aggregates are mostly used in infrastructure projects such as construction, roads and bridges, and are indispensable and irreplaceable basic materials. In China's metal and non-metallic mining industry, during the long-term mining and production process, the mine produces a lot of waste rock and tailings. Using these tailings resources to make sand and replace natural sand and gravel can not only ease the tight supply and demand situation of sand and gravel, but also It can realize the comprehensive utilization of tailings resources.

2. Concrete fine aggregate

When using tailings as fine aggregate for concrete, the same requirements for coarse and medium-sized aggregates should also be considered. Generally speaking, tailings sands are better than sea sands, because sea sands often contain salt and chloride ions, which are easy to corrode steel bars, and the surface of tailings is rough and angular, which can increase the strength of concrete.

The tailings are to be used as fine aggregate and require a certain particle size. When the particle size does not meet the requirements, the tailings need to be screened. Coarse sand makes the concrete more dry, the viscosity decreases, and the workability is not good; the ultra-fine sand not only makes the concrete very easy to segregate, but also requires a large amount of water, thereby increasing the amount of cement.

3. Use waste rock as railway ballast

The requirement for railway ballast is that it is not fragile under vibration pressure. Rocks with developed stratification or bedding are certainly not suitable for ballast, while limestone, basalt, etc. are more suitable for railway ballast.

4. Basic raw materials of cement

The basic raw materials of cement are limestone and clay ore. Limestone and clay rock (shale, etc.) are common waste rocks in mines, or tailings containing corresponding components can also be used as basic raw materials. It should be noted that for the use of limestone and clay rock, do not mechanically copy the grade index requirements in the past specifications.

5. Mixed materials of cement

Adding an appropriate amount of mixed materials to cement can not only improve some properties of cement, but also save the consumption of basic materials. The mixed material is divided into two kinds of filling and active. At present, blast furnace slag and fly ash have become commonly used cement active mixed materials.

6. Calibration raw materials for cement

Mainly iron correction raw materials and silicon correction raw materials. These two raw materials can also use tailings. For example, the tailings of a polymetallic mine in Youxi, Fujian, which have a high iron content, have been sold to cement plants as raw materials for iron correction. The tailings of most Anshan-type iron ores, which contain a lot of silicon and iron, have the potential to become raw materials for correction.

7. Used to produce all kinds of bricks

At present, coal gangue bricks have become one of the main wall building materials to replace clay bricks. Not only gangue red bricks but also hollow bricks can be fired. In fact, many shale waste stones are also suitable for brick making, but only energy consumption Higher than gangue bricks.

Square brick is a kind of ceramic imitation stone product that has just been popular in China. It can have various shapes and colors, and can be combined into various patterns at will. Generally, 30~50% of tailings can be added, and then some ceramic raw materials and color materials are added, and it is fired at 1200~1300 ℃.

8. Using tailings to make fields

This technique is to turn the wasteland of the river beach into arable land, which is called "enclosure farming method". In arid regions such as North China and Northwest China, there are often many intermittent or semi-intermittent rivers. The beaches are very wide, even when it rains, the water channels are also very narrow; and the beaches on both sides of the river channels have a large number of river pebbles of different sizes that cannot be used. Cultivated land. The method of making a pond is to build a dam with a height of 3.5 to 5 meters on the river beach, each pond has an area of ​​about 40 acres; the tailings are directly discharged into the pond, and when the pond is full, it is then discharged Go to another new enclosure. After filling the tailings pond, river pebbles have been buried under the tailings and covered with about 25 cm of arable soil, making this pond arable. This method has been obtained in some mines in eastern Hebei success.

9. Use waste rock or/and tailings to fill open pits to restore fields

Discharge the waste rock or/and tailings to the existing open pit in the past, and then cover it with a certain thickness of arable soil to make it arable land. This is the approach being adopted by some mines.

10. Tailings re-election: recover valuable components from tailings

Tailings re-election is an important measure to improve the utilization rate of resources, and it is also conducive to reducing the emissions of tailings, which not only improves the recovery rate of resources, but also brings huge economic benefits to enterprises.

The value of tailings cannot be underestimated. Whether it is due to environmental protection policy requirements or the practical needs of sand and gravel resources shortage and soaring prices, comprehensive utilization of tailings is particularly urgent. With the development of science and technology and the interpenetration of disciplines, the ways of using tailings will become wider and wider.

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