Against the background of self-propelled machinery, scraper delivery looks archaic: the technology has been around for more than a century, and in many mines it has long been replaced by loading and unloading machines. But it's too early to write it off. Scraper equipment - a winch, a scraper, blocks and ropes - remains in service with underground mines around the world - not because of poverty, but because in a number of mining conditions this method of delivery objectively outperforms a diesel self-propelled gun. Let's look at exactly where and why.
How the scraper complex works
The scheme is extremely simple: a two- or three-drum winch, a scraper (bucket-travois), scraper blocks and ropes. The head rope pulls the scraper with ore to the ore outlet or hatch, the tail rope returns it to the face; blocks fixed in the mine set the trajectory. Three-drum winches allow you to change the direction of scooping without rewiring. The whole complex consists of metal—intensive mechanics without hydraulics, internal combustion engine and electronics.
The selection of the complex is also simple: the winch capacity is selected according to the length of delivery and the weight of the ore scraper, the number of drums is according to the slaughter scheme (two-drum for rectilinear scooping, three-drum for fan), and the capacity of the scraper is consistent with the size of the chipped rock mass and the section of the mine. This simplicity results in the main operational properties: minimum maintenance, maintainability by a local locksmith, undemanding quality of the workings' soil, and the ability to work where a self-propelled machine simply won't go.
Five situations where a Scraper wins
Low-power and vein ore bodies. When the core capacity is less than the size of the PDM, the machine is forced to take the empty rock, diluting the ore. The scraper works in a clearing space with a height of half a meter, where self-propelled vehicles have nothing to do.
Dangerous cleaning space. The operator is at the winch, under the fixed roof, and only the rope scraper moves in the danger zone. With an unstable roof, after massive explosions, and when working off the rear pillars, this is actually a deserted excavation - something that cannot be achieved with PDM without an expensive remote control.
Poor ventilation. The electric winch does not emit exhaust. For dead-end and poorly ventilated workings, this removes the requirement to pump air for diesel - and ventilation on deep horizons is expensive.