Research on Technical Principles, Application Status and Development Trends of Mine Mucking Machines

Mine Mucking Loader: Structure, Working Principle and Development Trend As a key piece of equipment for modern underground mine excavation operations, the mine mucking loader plays an irreplaceable role in improving mucking efficiency, reducing labor intensity and ensuring operational safety. This paper systematically expounds the structural composition and working principle of mine mucking loaders, analyzes their application status in coal mines, metal mines and tunnel engineering, discusses the intelligent and green development trends, and puts forward improvement suggestions for current technical bottlenecks, aiming to provide a theoretical reference for the upgrading of mining equipment. In underground mine excavation, the cleaning of rock debris after blasting or mechanical cutting (commonly known as "mucking") is a critical link affecting construction progress. The traditional manual mucking method has prominent problems such as low efficiency, high potential safety hazards and high labor intensity. Statistics show that mucking operation time usually accounts for 30%–50% of the entire excavation cycle, becoming the main bottleneck restricting the improvement of single-drum advance efficiency. The mine mucking loader (also known as scraper mucking loader) is a continuous operation equipment integrating mucking, conveying and transferring functions. Its application significantly shortens mucking time and improves the operating environment. In recent years, with the advancement of mechanization and intelligent construction in mines, mucking loader technology has witnessed leapfrog development from simple scraper type to full hydraulic drive, and from manual control to remote control. Structural Composition and Working Principle of Mine Mucking Loader Overall Structural Composition Modern mine mucking loaders mainly consist of the following five systems: 1. Mucking mechanism: As the core working device, it usually adopts a scraper or bucket structure. The scraper is driven by a steel cable or hydraulic cylinder to complete mucking, lifting and unloading. The scraper capacity generally ranges from 0.15 to 0.6 m³, which directly determines the single-machine production efficiency. 2. Traveling mechanism: To adapt to narrow underground spaces, crawler chassis are widely used, featuring low ground pressure, strong climbing ability (usually ≥20°) and small turning radius. Some models are equipped with rubber tracks to protect the roadway floor. 3. Conveying mechanism: Mostly scraper conveyors or belt conveyors are adopted to transfer the mucked rock to subsequent transportation equipment (mine cars, shuttle cars or belt conveyors). The conveying capacity must match the mucking capacity to avoid material blockage. 4. Hydraulic system: Modern mucking loaders generally adopt full hydraulic drive, with a system pressure of usually 16–25 MPa, providing power for mucking, traveling and conveying. Key components include variable pumps, multi-way directional valves, hydraulic motors and cylinders. 5. Electric control system: It includes explosion-proof motors, electric control boxes, operating valve groups and sensor networks. Coal mine equipment must comply with the GB 3836 explosion-proof standard to ensure intrinsic safety in gas environments.  Working Principle and Operation Flow The operation flow of the mucking loader follows the cycle mode of "mucking–lifting–unloading–returning": • Mucking stage: The operator controls the scraper to lower to the muck pile, and the hydraulic motor drives the scraper to close and insert into the rock debris; • Lifting stage: The lifting cylinder or winch pulls the scraper up along the guide groove, while keeping it closed to prevent debris leakage; • Unloading stage: When the scraper reaches the unloading height, it collides with the limit device and opens automatically, and the rock debris falls into the conveyor; • Returning stage: The unloaded scraper quickly returns to the working face for the next cycle.  In continuous operation mode, the cycle time for a skilled operator can be controlled at 20–40 seconds, with an hourly production capacity of 30–80 m³, which is 5–10 times higher than that of manual mucking.