It's more than gravel aggregate! Mine waste and tailings are used more widely than expected

Date: 2019-06-27 Views:

1. Sand aggregate


Sand aggregate is the largest, indispensable and irreplaceable basic material for infrastructure construction, such as construction, road, bridge and so on. However, sand aggregate belongs to non-renewable resources, and thousands of years of mining have caused great damage to the earth's environment. In the process of long-term mining and production, a large number of waste stone and tailings are produced in the metal and non-metallic ore industry of our country, and the use of these tailings resources can completely replace or partially replace sand aggregate.

Many waste rocks in mines can be used as coarse and medium aggregate, and the physical properties and chemical composition of rocks should be taken into account in the evaluation of aggregates. Both depend on the type of rock, but also consider the degree of fracture development and weathering. In the physical properties, the strength is of course beneficial; in addition, the elastic modulus is considered, the closer the elastic modulus is to the cement mortar, the better. At the same time, waste stone used as aggregate is also required, in which the content of flake or fiberlike cuttings should not be too much. Generally speaking, limestone, fine sandstone, quartz rock, granite with relatively fine crystallization, diorite, gneiss and basalt are all suitable as aggregates. Some airport runways Basalt is also required as aggregate in concrete, which is related to the highest strength of basalt in natural rocks. The chemical composition of rocks can not be ignored, mainly to prevent the problem of "alkali-aggregate reaction", which is called concrete cancer in the world.

2. Concrete fine aggregate


When tailings is used as fine aggregate of concrete, the same requirements for coarse and medium aggregate should also be considered. Generally speaking, tailings is better than sea sand because it often contains salt and chloride ions, which can easily rust steel bars, and the tailings surface is rough and angular, which can increase the strength of concrete. However, when the tailings is used as fine aggregate, a certain particle size is required. When the particle size does not meet the requirements, it is necessary to screen the tailings. Because the coarse sand makes the concrete dry, the viscosity decreases, the workability is not good, the ultra-fine sand not only makes the concrete easy to separate, but also requires a large amount of water, thus increasing the amount of cement.

3. Use the waste stone as the railway ballast


The requirement of the railway track slag is that the rock which is not fragile under the vibration pressure, and the rock or bedding is developed is of course not suitable for being used as the ballast, and the limestone, the basalt and the like are more suitable for being used as the railway ballast.

4. Basic raw material of cement


The basic raw materials of the cement are limestone and clay minerals. The limestone, clay rock, shale and so on are the common waste stones of the mine, and the tailings containing the corresponding components can also be used as the basic raw materials. It should be noted that for the use of limestone and claystone, it is not simply to mechanically copy the grade indicator requirements in the past specification.

5. Mixed material of cement


Adding proper amount of mixed material to cement can not only improve some properties of cement, but also save the consumption of basic materials. The mixed materials are divided into filling property and activity. At present, blast furnace slag and fly ash have become commonly used cement active mixed materials. In fact, some tailings are also suitable for mixed materials, such as the tailings of vanadium-titanium iron deposits in hornblende. In addition, those with high content of amorphous materials in waste rocks (or tailings), such as vitreous volcanic rocks, tuff, floating rocks and so on, can also be used as active mixtures.

6. Correction raw materials for cement


Iron correction raw materials and siliceous correction raw materials. These two raw materials can also be used in tailings. The tailings of some metal ores, with high iron content, can be sold to cement plants as raw materials for iron correction; the tailings of some iron ores contain both large amounts of silicon and iron, and can also be used as correction raw materials.

7, used in the production of all kinds of bricks


At present, coal gangue brick has become one of the main wall building materials to replace clay brick. It can not only burn fighter red brick, but also make hollow brick. In fact, many shale waste stone is also suitable for brick making, but the energy consumption is higher than gangue brick. In addition, the unforged gypsum tailings is used as raw material, which is mixed with a certain proportion of ground slag and fly ash after grinding, which can be used to produce gypsum tailings brick, hollow block and other new wall materials under the action of compound exciter.

In fact, many tailings can be used to make steamed brick / autoclaved brick, which is made of steam curing and even high pressure steam curing of tailings with a certain gelling agent.

The wide-field brick is a kind of ceramic stone-like product which has just been used in the country, and can have various shapes and colors, and can be combined into various patterns. Generally,30-50% of tailings can be added, and some ceramic raw materials and coloring materials are added, and are fired at 1200-1300 DEG C.

8. Tailing with the tailings to make a field


The technique is to turn the unreclaimed land into arable land. In the early areas of North China, Northwest and the like, there are many geyser or semi-geysers, and the river beach is very wide. Even when it rains, the water channel is very narrow; and the banks on both sides of the river have a large amount of river and gravel with different sizes and cannot be used as the cultivated land. The method comprises the following steps of: using a stone base to form a surrounding dam with a height of from 3.5 to 5 meters on a river beach, wherein the area of each enclosure is about 40 mu; and the tailings are directly discharged into the pool, and when the pool is full, the pond is then discharged to an additional new enclosure. The pool is filled with the tailings, and the river and gravel are buried under the tailings, covering about 25 cm of the arable soil on the pond, so that the pool Become arable land, has been applied in some areas and has been successful.

9. Using waste stone or / and tailings to fill open pit to cover the field


The waste stone or tailings is discharged into the open pit in the past and covered with a certain thickness of tilable soil to make it arable land. This is the method being used in some mines.

10, as a raw material for the production of silicon bricks


The silicon brick is an acid refractory material, which is widely used in glass melting furnace, coke oven or hot-blast stove and other facilities, and the load softening start temperature is as high as 1640-1670 DEG C. The requirement for the raw material of the silicon brick is that the content of SiO2 is not less than 96%, and there are not too many impurities such as Al2O3, N2O, K2O and the like. The tailings of some kaolin ores are in full compliance with this requirement; in addition, there are quartzite or quartz sandstone which can meet this requirement in the waste stone of certain mines.

11. Use in the production of calcium carbonate


Papermaking white mud, carbide slag, phosphogypsum and alkali slag contain a large amount of calcium hydroxide or calcium oxide, which can be used as the raw material for the production of light calcium carbonate.

12, used as raw material for heavy calcium carbonate


Heavy calcium carbonate is mainly used as the main raw materials or fillers in plastics, rubber, glass, ceramics, toothpaste and other industries. It mainly takes calcite and dolomite as the main raw materials, and its requirements are high purity, low iron content, no sulfur and harmless to human body. In some deposits, there are fragments of large calcite veins or dolomite veins or pure marble and dolomite, which can be selected from waste rocks as raw materials.

13. Tailings re-separation: recovery of valuable components from tailings


Tailings re-separation is an important measure to improve the utilization rate of resources, and it is also helpful to reduce the emission of tailings. It can be seen from the results of tailings re-separation that not only the recovery rate of resources has been improved, but also great economic benefits have been brought to enterprises.

In the field of mining, the developed countries in the world have taken waste-free mines as the development goal of mines, and the comprehensive utilization of tailings as a symbol to measure the level of science and technology and economic development of a country. The utilization rate of tailings abroad can reach more than 60%. Some European countries are already developing to the goal of waste-free mines.

The comprehensive utilization of mineral solid waste is not only the pursuit of maximum economic benefits, but also the comprehensive recovery and utilization of resources and the protection of ecological environment. With the development of science and technology and the mutual penetration of disciplines, the way of tailings utilization will be more and more extensive.

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