Selection of cemented carbide materials for coal mining and mine drilling tools

Coal resources are the main energy. Most coal fields have the characteristics of large reserves, wide distribution, complete varieties, good texture, shallow burial and easy mining. Therefore, coal mining has become the most direct way of our energy source. However, in the process of coal mining and construction, various problems will be encountered. Due to the complexity of the geological structure of the coal mine itself and the harshness of the coal mining environment, it poses a severe test for mining and drilling.

 

coal mining tools

 

How to meet the needs of coal mine exploration and development, further improve the quality of coal mining equipment, speed up drilling and mining, and reduce exploration costs are the primary problems to be solved at present. The high quality of equipment and tools and advanced drilling technology the guarantee efficient implementation of coal mining. Let’s take a look at the geological conditions of coal rocks:

According to the characteristics of drilling construction and geological conditions, we divide complex coal-rock strata into the following categories:

(1) Loose and broken formations: mainly include loose and broken formations and hard, brittle and broken formations. The more typical Permian strata are composed of poorly cemented sandstone and limestone. This stratum contains a large amount of sandstone, and there are mudstone, sandstone, conglomerate and some pebbles in some areas. Affected by the vibration and collision of drilling tools and the erosion of mud, drilling holes are prone to accidents such as collapse, leakage, and overdiameter.

(2) Water-sensitive formations: mainly include hydration-loose, hydration-spalling, hydration-swelling and hydration-dissolution coal measure formations.

(3) Leakage and water gushing formations: it is extremely difficult to drill and construct protection holes in this kind of formation, and the leakage is divided into large, medium and small leakages; the water gushing formation generally has a water inflow of 10-50 m3/h. Coal-measure strata are siliceous cemented, limestone is mostly broken and abrasive, and structural fissures are developed, poor stability, strong water permeability, abundant groundwater, strong hydraulic pressure, borehole diameter shrinkage or water gushing occurs from time to time.

In the process of coal mining, it is very important to choose the right material as a mine drilling tool. Cemented carbide has become the most suitable material for coal mining tools because of its special corrosion resistance, high hardness, excellent fracture toughness and compressive strength.

Cemented carbide is formed by the powder metallurgy process of refractory metal hard compound and bonding metal, through powder preparation, compression moulding and high-temperature sintering. Has a series of excellent characteristics. Including very high hardness and wear resistance, surpassing the normal temperature hardness of high-speed steel at 600°C and surpassing the normal temperature hardness of carbon steel at 1000°C; it has high compressive strength and elastic modulus; it has low impact toughness and Small thermal shrinkage coefficient. These excellent properties make cemented carbide widely used in coal mining, geological exploration, mining and other fields.

Rocks are divided into four categories and twelve grades according to their hardness. In specific work, abrasive materials and drilling methods should be selected according to rock drillability, abrasiveness, and integrity.

Rocks of grade 1-6 and some grade 7 can be drilled with cemented carbide, diamond and composite chips;

Diamond rotary drilling can be used for grade 4-12 rocks;

Steel grain drilling can also be used for grade 7-12 rocks;

Rocks of grades 6-8 can be drilled with cemented carbide percussion rotary drilling;

Diamond impact rotary drilling can be used for grades 6-12.

Cemented carbide materials are indispensable tools in the process of coal mining and mine drilling.

LMM provides a variety of hard alloy wear-resistant and corrosion-resistant tool parts for the coal chemical industry and provides customers with solutions for various harsh working conditions. Welcome to pay attention to LMM Group

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