The mining criteria and characteristics of granite quarries are mainly reflected in obtaining complete rock blocks that meet specific specifications and have no cracks from the ore body - that is, waste material. During the mining process, the planning of the working face and the selection of transportation methods need to fully consider the bedding planes, joints, and fractures of the ore body to reduce their negative impact on the mining process and ensure the successful extraction of large pieces of waste material.
In the initial stage of granite quarry mining, it is necessary to select the first mining area based on resource conditions and market demand, clarify the scope of mining, determine the production scale and work system of the mine. Mining work should be carried out on the basis of comprehensive consideration of natural environment and economic and technological conditions. The entire mining process includes stages such as development, transportation, stripping, and mining.
During the mining process, it is necessary to remove the covering layer, weathered layer, interlayer, surrounding rock, and broken and non valuable ore parts.
1、 Mining technology
The basic process of stone mining includes three main steps: separation, cutting, and trimming.
1) Separation process: Common separation methods include using iron wedges for splitting separation, using expansion agents for drilling separation, flame cutting separation, and comprehensive separation technology.
-Splitting separation: By driving iron wedges into the rock mass to create cracks, it is suitable for small-scale mines, with low cost but low efficiency. Another method is to use expansion agents, which generate expansion force through hydration to crack the rock mass. The operation is simple and safe, but the efficiency is relatively low.
-Flame cutting separation: Using high-speed flames to heat rocks, different minerals in the rocks react differently to heat, resulting in explosive spalling and the formation of separation grooves. This method is suitable for rocks with high quartz content, low thermal capacity, and poor thermal conductivity, such as granite.
-Silent blasting separation: The rock drill drills holes in the rock mass and loads blasting materials as needed (currently used include Stone Cracking Powder, Expansive Mortar, Non Exploratory Demolition Agent, etc.) for controlled blasting. This method is efficient, safe, widely used, and can effectively avoid the generation of harmful cracks during use.
2) Cutting process: Flip the separated stones and use the splitting method to cut them into the required waste material according to the crack pattern and the specifications of the waste material.
3) Trimming process: Trimming materials that do not meet the requirements, using a hammer or trimming machine to remove excess parts, ensuring that the materials are flat and the edges and corners are neat.
1. Flame rock drilling mining method
The flame rock drilling mining method, combined with flame cutting and handheld rock drill drilling, supplemented by detonating wire controlled blasting, is the basic method for granite mining in China. The main process flow of this method is similar to manual mining, which uses a flame cutting machine to cut a connecting surface between the separation body and the ore body, achieving more reliable separation.
2. Artificial rock drilling and bead sawing method
The manual rock drilling bead saw mining method uses diamond bead saws and handheld rock drills for drilling, combined with detonating cord controlled blasting, which is an advanced mining technology that replaces traditional methods.
3. Diamond bead saw full cutting mining
The diamond bead saw full cut mining method is an efficient method for mechanized mining of granite, which separates, disintegrates, and shapes the separation body and ore body through the bead saw.
4. Circular saw string bead saw combination method for mining
The combination method of circular saw and bead saw mining combines circular saw and bead saw technology, which is suitable for small and medium-sized mechanized granite mines.
5. Bench rock drill string bead saw mining method
The bench mounted rock drill string saw mining method is an advanced mechanized mining method that uses a bench mounted rock drill instead of a handheld rock drill to improve mining efficiency.
2、 Technical specifications
Under normal conditions, the minimum economic waste material rate for granite mines should be between 15% and 25%, with a stripping ratio of approximately 0.3.
-Mining site step height: 4-6 meters when using a mobile crane; When using a small mast crane, it is less than or equal to 14 meters; When using a large mast crane, it is less than or equal to 62 meters.
-The angle of the stepped slope is usually 90 °, and the final slope angle is determined based on the stability of the rock.
-The width of the strip stone is determined based on the performance of the mining equipment, the specifications of the waste material, and the condition of the cracks, generally between 1-3 meters.
-Working face length: 5-15 meters for manual mining; The flame cutting machine mining is 15-20 meters long.
-The minimum width of the work platform is usually 20-25 meters.
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