Multi ply fabric? PVC/PVG? Steel cord? When we choose a coal mine conveyor belt systems, there may be problems in how to choose. This article on the selection and use of coal mine conveyor belts will tell you how to choose a coal mine conveyor belt.
Types of conveyor belts for coal mines
Conveyor belt for underground coal mine
Underground coal mines contain gas (methane), and coal is a flammable substance. Therefore, the primary requirement for selecting coal mine conveyor belts is to ensure the safety of underground coal transportation.
There are two types of flame-retardant conveyor belts used in underground coal mines:
- Solid woven conveyor belts
- Steel cord conveyor belts
Solid woven conveyor belts
The solid woven conveyor belt is a special conveyor belt for underground coal mines. It has good flame retardant and antistatic properties, light weight, low manufacturing cost, good tear resistance and other advantages. In addition, installation and maintenance are also very convenient. Therefore, the fabric whole core flame retardant conveyor belt is the first choice for underground coal mines.
At present, more than 80% of underground coal mines on the market use fabric whole-core flame-retardant conveyor belts. It is divided into two types: PVC (plastic) and PVG (rubber cover).
- PVC type solid woven conveyor belts
The carcass and cover of the PVC type solid woven conveyor belts are all made of polyvinyl chloride. It is a plastic product with poor environmental adaptability and climbing performance. The maximum inclination angle is 16°, and the suitable temperature is 10℃ ~ 40℃.
- PVG type solid woven conveyor belts
The cover of PVG type solid woven conveyor belt is a blend of rubber and polyvinyl chloride, which is better than PVC type in environmental adaptability and climbing performance. Under normal circumstances, the conveying angle can reach 20°, If the covered surface is patterned, the conveying angle can reach 25°. Its suitable temperature is -10℃~50℃.
The solid woven conveyor belt is suitable for medium and low carrying capacity and medium and low speed conveying system.
Steel cord conveyor belt
Compared with the solid woven conveyor belt, the steel cord conveyor belt has the advantages of high tensile strength, small elongation, impact resistance, large carrying capacity, long transportation distance, and long service life. The temperature of steel cord conveyor belt is generally -10℃~50℃, and the conveying inclination angle can reach 25°. If the covering surface with pattern is used, the conveying inclination angle can reach 30°. The strength range is 630 N~5400 N/mm, and the width range is 800~2200 mm.
Steel cord conveyor belt is suitable for the transportation system with high speed, large transportation capacity and long distance.
Conveyor belts for surface coal mines
Compared with underground coal mines, surface coal mines have better transportation conditions, and flame retardant and antistatic requirements are no longer the main requirements. The physical and mechanical properties should be given priority to, while safety performance should be taken into consideration.
Due to the large changes in the ambient temperature of the ground and open-pit coal mines, in some countries and regions, the solid woven conveyor belt is not suitable for coal mine transportation. Multi ply fabric conveyor belts and steel cord conveyor belts should be preferred. When the temperature is lower than -10℃, it is necessary to choose cold-resistant multi ply fabric or steel cord conveyor belt.
Structure of conveyor belt for coal mine
The conveyor belt is generally composed of a carcass and a cover.
The carcass is the skeleton layer of the conveyor belt and can provide the necessary strength.
The carcass material of the layered conveyor belt is composed of multiple layers of fabric. The carcass of the solid woven conveyor belt is a whole structure woven by three or more layers of cotton and chemical fibers. The carcass of the steel cord conveyor belt is composed of multiple steel cords arranged longitudinally.
The cover is the protective layer of the carcass of the conveyor belt, which protects the carcass from direct impact, wear and corrosion of materials. It can prevent premature damage to the carcass and extend the service life of the conveyor belt.
The covering layer is divided into a top cover and a bottom cover. The surface in contact with the conveying material is the top cover. According to the different requirements of the conveyor belt, it can have different coverage levels, such as impact resistance, tear resistance, wear resistance, corrosion resistance, heat resistant, cold resistant, etc.
Carcass material of coal mine conveyor belt
The role of the carcass is to withstand the forces from the inside and outside the conveyor belt, increase the strength of the conveyor belt, and limit its deformation. It largely determines the performance, life and value of the conveyor belt.
The carcass materials of coal mine conveyor belts mainly include cotton canvas, nylon canvas, polyester canvas, solid woven and steel cord.
Cotton canvas mainly includes polyester/cotton, polypropylene/cotton, pure cotton and other canvases. Cotton fiber has the characteristics of good adhesion to rubber, and the conveyor belt made of cotton canvas has the advantages of good flexibility and low price. It is mainly used for short-distance transportation of small lumps and powdered coal on the ground. The disadvantages of cotton canvas are low strength, easy corrosion, short life, flame retardant and poor cold resistance.
Both the radial direction and the weft direction of nylon canvas are nylon fibers, which have good wear resistance and high strength. The nylon canvas conveyor belt has the advantages of thin belt body, high strength, and impact resistance. However, nylon fiber has a high elongation rate, so it is mostly used in medium conveying distances and conveyor belts that require good carcass elasticity. Nylon conveyor belts are widely used in surface coal mines, coal preparation plants and open pit mining.
In addition to the advantages of nylon canvas, polyester canvas also has the advantages of low elongation, good heat resistance, and low price. It is the most widely used conveyor belt material. Polyester canvas conveyor belt has the advantages of small elongation and impact resistance. It is mainly used in conveyor belts with large transportation distance, large load, strong chemical resistance and strong dimensional stability. Especially suitable for ground and open-pit coal mining and transportation.
Solid woven material
The fabric core is a special matrix material for PVC and PVG flame retardant conveyor belt, and the strength range is 680n-2240n / mm. It is an integral structure of three or more layers woven by polyester cotton and nylon cotton. The warp thread is usually nylon and polyester fiber, and the weft yarn is nylon / cotton fiber. The whole core flame retardant conveyor belt is non layered, and its comprehensive performance is better than that of layered fabric conveyor belt. It is the main variety of coal mine conveyor belt.
Steel cord conveyor belts used in coal mines are generally made of No. 70 high carbon steel after drawing and stranding. The steel wire used in the conveyor belt is galvanized on the surface. The diameter of the steel wire rope ranges from 2.5 to 14 mm, and the strength ranges from 3.3 to 164 kN.
Main Specifications and splicing methods of coal mine conveyor belts
Coal mine conveyor belt specifications
The technical parameters of the coal mine conveyor belt include physical and mechanical performance indicators and safety performance indicators. The physical and mechanical performance indicators include the physical properties of the conveyor belt cover, the full thickness tensile strength, and the interlayer adhesion strength. The safety performance indicators include surface resistance and Roller friction, etc.
Splice method of coal mine conveyor belt
The strength of the conveyor belt is determined by the strength of the splice.
- The splice strength of mechanical splicing is 60-65% of the original belt strength.
- The strength of the cold vulcanized splice is 75%-80% of the original belt strength.
- The strength of the hot-vulcanized splice can reach 90-95% of the original belt.
The layered fabric conveyor belt for coal mines can choose mechanical splicing, cold vulcanization and hot vulcanization according to the use environment and load. Steel cord conveyor belts can only choose thermal vulcanization splices. Solid woven conveyor belts(PVC/PVG) are generally mechanically spliced. When the strength exceeds 1250 N/mm, it is recommended to choose thermal vulcanized splices.
Through the introduction of the types, structure, carcass material, technical parameters and splice methods of coal mine conveyor belts, I believe you have a more comprehensive understanding of coal mine conveyor belts.
As a manufacturer and supplier of conveyor belts for coal mines, Rayco provides a wide range of conveyor belts for coal mines. As a manufacturer and supplier of conveyor belts for coal mines, rayco provides a wide range of conveyor belts for coal mines.