Cat has released the new Rock Straight System, the HRM220, a fully mechanised longwall system for continuous mining of flat and tabular deposits of hard rock minerals.
It features a hard rock shearer that uses Cat Activated Undercutting Technology.
A low-profile hard rock chain conveyor and hard rock hydraulic roof supports complete the system, which delivers simultaneous cutting, loading and hauling.
The technology is the first commercial continuous mining and hauling system for underground hard rock applications.
It replaces conventional drill-and-blast operations in low heights, ranging from 1.3 to 2.0 meters and in bedded deposits such as platinum, copper and gold. It follows the seam and increases the ore mined while minimising dilution.
It also reduces health and safety risks as fewer people are needed underground. The electrically powered rock cutter and hard rock conveyor have no exhaust emissions, and there is no need for explosives use in the production cycle.
According to Cat, its Cat Activated Undercutting Technology is the key to the success of the cutting machine, the HRM220. The design of the two cutting heads enables the picks to attack the rock from a suitable angle.
The activation movement enhances velocity, momentum and impact of each pick—while moving the pick away quickly to minimise wear and heating. This results in reduced energy consumption and replacement cost of cutting tools.
Each of the cutting units is powered by a 132-kW motor and can cut rock exceeding 120 MPa uniaxial compressive strength.
The haulage speed can be up to six meters per minute, depending on the rock, and, in combination with a cutting depth of 100 mm, can deliver high production rates of approximately 160 tonnes per hour. The cutting units can be positioned at different heights to increase the productivity of a single cutting sequence.
The HRM220 incorporates electronic modules that enable control, monitoring and protection of the miner. Remote operation and diagnosis of major components can be done from the operator cabin via on-screen information and data can be transferred to a surface location for analysis when needed.
The mainframe protects electrical equipment and hydraulics from cutting and haulage forces, enhancing reliability and the system’s life. The cutting system has a total weight of 41.0 tonnes.
The HRC30 Hard Rock Conveyor is designed to transport rock in low cutting heights. A single flight bar chain moves the apron pans across the length of the cutting face as they ride on the line pans. The apron pan system ensures reduced wear when moving abrasive rock.
The number of line pans can be varied to suit different face lengths up to 100m. The conveyor uses high-strength steel for long service life and reliable operation.
The HRS1220 Hard Rock Roof Support is specifically designed for the Rock Straight System.
The two-legged shield incorporates a solid base connected with an advancing mechanism on each side of the base.
The supports feature a working range of 1060 to 2155mm with a yield load of up to 2599 kN.
The Cat PMC-R electro-hydraulic control system provides roof support automation, providing equipment monitoring and remote diagnostics and increasing productivity.