Method for preparing siliceous machine-made sand from coal gangue

Abstract

The invention relates to a method for preparing siliceous machine-made sand by using coal gangue, which is characterized by comprising the following steps: feeding the coal gangue into a jaw crusher through a vibrating feeder, crushing the coal gangue to-200mm, then transporting the crushed coal gangue material to a medium and fine crushing processing section through a belt conveyor, wherein the medium and fine crushing processing section is mainly composed of a cone crusher and a vibrating screen, after materials are subjected to counterattack crushing, the vibrating screen plays a role in screening inspection, oversize products with the size of + 50 mm return to the cone crusher to be continuously crushed, the oversize products and undersize products enter a three-product dense medium cyclone for gravity separation after being crushed, medium-density gangue enters a sand making machine, and the medium-density gangue enters the sand making machine; the machine-made sand with uniform granularity is obtained. The method has the advantages that a dry-wet combination mode is adopted, two-stage crushing is firstly adopted, then medium-density gangue is selected through gravity separation of the three-product dense medium cyclone, then the vertical shaft type impact crusher is adopted for crushing the medium-density gangue, particles can be crushed to be about 5 mm, it is guaranteed that the shapes of the gangue particles are regular, and the yield of the gangue particles is improved. Qualified machine-made sand is obtained; the whole process is high in efficiency, energy-saving and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive utilization of tailings and relates to a method for preparing siliceous machine-made sand by utilizing coal gangue. Background Art

[0002] Construction sand and gravel are mainly used in the construction of buildings, roads, bridges, railways, water conservancy projects and other projects. In the early days, natural river sand was mainly used. However, as natural resources gradually become scarce, the mining of natural sand and gravel has become increasingly restricted, and the use of machine-made sand made from solid waste is increasing. Although my country's machine-made sand raw materials come from a wide range of sources and its output is huge, the demand is also huge. Coal gangue, as solid waste discharged during coal mining or coal washing, is a black-gray rock with a low carbon content and harder than coal that accompanies coal seams during the coal formation process. The accumulation has exceeded 5 billion tons per year, causing significant damage to the environment.

[0003] The main components of coal gangue are Al2O3 and SiO2, and there are also varying contents of Fe2O3, CaO, MgO, NaO2, etc. and trace rare elements (gallium, vanadium, titanium, cobalt). Some scholars have conducted research on the physical properties of coal gangue and found that coal gangue machine-made sand has the characteristics of angular shape and rough surface, and its adhesion and mechanical bite force are greater than natural sand. It has strong anti-disturbance and crack resistance and can be used to build high-stability bridges. Although the process of preparing machine-made sand from coal gangue is being carried out in various parts of the country, the raw materials of coal gangue are complex, and the composition and physical properties vary greatly. The sulfur content of coal gangue in some places is high, and it is easy to form soluble sulfates when encountering alkali metals, and SO2 is generated at a certain temperature to corrode equipment, and the utilization rate of different components is low; and the current standards for preparing machine-made sand are not clear, which limits the application of machine-made sand prepared from coal gangue. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the prior art and provide a method for preparing siliceous machine-made sand using coal gangue; the method can efficiently utilize coal gangue resources, produce high-quality machine-made sand, and save energy and protect the environment.

[0005] In order to achieve the purpose, the technical solution adopted by the present invention is as follows: A method for preparing siliceous machine-made sand using coal gangue, characterized by comprising the following steps: The gangue is fed into the jaw crusher through a vibrating feeder and crushed to -200mm. The crushed gangue is then transported to the medium and fine crushing section through a belt conveyor. The medium and fine crushing section is mainly composed of a cone crusher and a vibrating screen. After the material is impact crushed, the vibrating screen is used for inspection and screening. The material on the screen (+50mm) returns to the impact crusher for further crushing. After crushing, it enters the three-product heavy medium cyclone for re-selection together with the material under the screen. The medium-density gangue (2.3~3.0g / cm3 ) enters the sand making machine to obtain machine-made sand with uniform particle size (particle size is -5mm).

[0006] Furthermore, the jaw crusher is a compound swing jaw crusher.

[0007] Furthermore, the medium and fine crushing stage uses a cone crusher.

[0008] Furthermore, the vibrating screen is a circular vibrating screen.

[0009] Furthermore, the gravity separation device is a three-product heavy medium cyclone.

[0010] Furthermore, the sand making machine is a vertical shaft impact crusher (sixth generation).

[0011] The present invention adopts two-stage crushing (i.e., a combination of a first-stage jaw crusher and a second-stage cone crusher) for large-sized coal gangue, which can not only be crushed step by step to the target particle size, so as to facilitate entering the three-product heavy medium cyclone for re-selection; and the compound swing jaw crusher has a working efficiency about 20~30% higher than that of the simple swing jaw crusher. Compared with the traditional hammer crusher or impact crusher, the cone crusher is more suitable for the medium and fine crushing of coal gangue, and the material is crushed by the swinging motion of the cone. The cone crusher has the advantages of large crushing ratio, high crushing efficiency and uniform particle size, and can control the particle size of coal gangue at -50mm; the re-selection device selects a three-product heavy medium cyclone (composed of a cylindrical cyclone and a conical cyclone in series), and the low-density gangue (density less than 2.3g / cm 3 ) is mainly composed of coal, which can be used for power generation to reduce secondary pollution to the environment; medium-density coal gangue (density is 2.3~3.0g / cm 3 ) is mainly composed of silicon-aluminum compounds, which can be used to make siliceous machine-made sand. The part with high silicon content and low aluminum content can also be used to make high-silicon glass; high-density gangue (density greater than 3.0g / cm 3 ) The main components are pyrite and high-value additional metals; after gravity separation and classification, the gangue particles can be fully utilized. The selected gangue particles are shaped into -5mm particles by a sand making machine.

[0012] Beneficial effects of the present invention: 1. Gangue is crushed in two stages. The production capacity of traditional gangue rough crushing is about 1000t / h. This process uses a jaw crusher with a large inlet, which can handle gangue particles below 1500mm. In addition, the gangue particles are crushed by extrusion in the crushing chamber, which produces less dust and is efficient and environmentally friendly. Jaw crushers are mainly divided into single-swing jaw crushers and compound-swing jaw crushers according to their internal structure. The jaw plate movement of traditional single-swing jaw crushers is simple, and the crushing ratio is generally 3~6. When producing gangue, the hourly output range is 1~1500 tons. The production capacity of the compound-swing jaw crusher can reach 1~2200t / h, and the discharge port range can be adjusted to 10~400mm. The use of a compound-swing jaw crusher can greatly improve the production capacity of gangue rough crushing; 2. The secondary crushing section uses a cone crusher. The secondary crushing equipment used in the traditional process is generally a hammer crusher or an impact crusher. However, the impact crusher and the hammer crusher can only crush the gangue particles to about -100mm. When the cone crusher is used to crush the gangue, the particle size of the gangue can be accurately controlled to about -50mm; 3. Use three-product heavy medium cyclone to re-select -50mm coal gangue, and the density can be 2.3g / cm 3 Below, 2.3~3.0g / cm 3 、3.0g / cm 3 The above classification of coal gangue particles fully recycles the components in the coal gangue particles. Low-density coal gangue particles are mainly composed of coal and are used for power generation in power plants, etc. Medium-density coal gangue particles are used to make machine-made sand. High-density coal gangue particles can be used to extract pyrite and high-value additional metals through acid leaching, avoiding waste of resources. 4. Use vertical shaft impact crusher (sixth generation) to crush medium density gangue, which can crush the particles to less than 5mm and ensure the regular shape of gangue particles to obtain qualified machine-made sand. Since its main components are silicon-aluminum compounds, it is mainly used as one of the raw materials for C60 and below strength grade concrete in construction, municipal administration, transportation and other construction projects. When meeting the corresponding technical requirements, it can also be used in concrete projects such as ports and water conservancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention is a schematic diagram of a process for preparing siliceous machine-made sand using coal gangue. DETAILED DESCRIPTION

[0014] Combine the following Figure 1 , the present invention is described step by step: A method for preparing siliceous machine-made sand using coal gangue, the specific implementation steps are as follows: Example

[0015] The gangue (mainly composed of CaO, SiO2, Fe2O3, F, Al2O3, of which SiO2 is about 49wt%, Al2O3 is about 30wt%, Fe2O3 is about 4wt%, CaO is about 10wt%, Na2O is about 0.36wt%, MgO is about 0.77wt%, and K2O is about 0.65wt%) is transported from the silo to the compound swing jaw crusher by a belt conveyor, and the gangue is crushed to -200mm. Then, the material discharged from the discharge port of the compound swing jaw crusher is transported to the impact crusher by a belt conveyor for secondary crushing. After the material is impact crushed, the circular vibrating screen plays a role of inspection and screening. The material on the screen (﹢50mm) returns to the impact crusher for further crushing. After crushing, it enters the three-product heavy medium cyclone for re-selection together with the material under the screen, and low-density gangue (density less than 2.3g / cm 3 ), medium density coal gangue (density 2.3~3.0g / cm 3 ), high-density gangue (density greater than 3.0g / cm 3 ); the mineral particles of medium-density coal gangue are collected and sent to the vertical shaft impact crusher (sixth generation) for crushing and shaping to obtain machine-made sand with uniform particle size, with an average particle size of less than 5mm. The SiO2 content of the machine-made sand after sorting can be increased to about 65%, and the Al2O3 content can be reduced to about 18%. It can be used as high-silica quartz sand as an important component of concrete, mainly used as one of the raw materials for C60 and below strength grade concrete in construction, municipal administration, transportation and other construction projects. When meeting the corresponding technical requirements, it can also be used in concrete projects such as ports and water conservancy.

[0016] This example is only an example for clearly explaining the process flow, and is not intended to limit the implementation method. For ordinary technical staff in the field, different forms of changes or extensions can still be made based on the above description. There is no need to exhaust all examples. The extensions made thereby are still within the scope of protection of the invention.

Claims

1. A method for preparing siliceous machine-made sand using coal gangue, characterized in that The steps include: The gangue is fed into the jaw crusher through a vibrating feeder and crushed to -200mm. The crushed gangue is then transported to the medium and fine crushing section by a belt conveyor. The medium and fine crushing section is mainly composed of a cone crusher and a vibrating screen. After the material is impact crushed, the vibrating screen plays a role in inspection and screening. The +50mm screen material returns to the cone crusher for further crushing. After crushing, it enters the three-product heavy medium cyclone for re-selection together with the screen material. The medium-density gangue enters the sand making machine to obtain machine-made sand with uniform particle size.

2. The method for preparing siliceous machine-made sand by using coal gangue according to claim 1, characterized in that: The jaw crusher is a compound swing jaw crusher.

3. The method for preparing siliceous machine-made sand by using coal gangue according to claim 1, characterized in that: The medium and fine crushing section uses a cone crusher.

4. The method for preparing siliceous machine-made sand by using coal gangue according to claim 1, characterized in that: The vibrating screen is a circular vibrating screen.

5. The method for preparing siliceous machine-made sand by using coal gangue according to claim 1, characterized in that: The sand making machine is a vertical shaft impact crusher.

6. The method for preparing siliceous machine-made sand by using coal gangue according to claim 1, characterized in that: The density of the medium density gangue is 2.3-3.0 g / cm 3 .

7. A method for preparing siliceous machine-made sand by using coal gangue according to any one of claims 1 to 5, characterized in that: The particle size of the machine-made sand is -5 mm.

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