In March this year, Ellis Mining & Tunnelling trialled a Wirtgen 2200SM surface miner at the Sand and Soil Company in Tamborine, Queensland.
The mining of material in this quarry is usually carried out with a D9 dozer, which rips the rock and crushes the large fragments with the tracks. A loader or excavator loads the crushed rock into trucks, which transports the material to the on-site treatment plant. The end product is sand, used for construction. The quarry does not have a crusher on-site and there is only a 35 per cent recovery of saleable product utilising this method.
There was an escarpment at the site, about 40m high by 40m across the top, that had a 1m to 1.5m cap of very abrasive sandstone on the surface, which could not be ripped with a D9 dozer and blasting was not permitted. This cap was hindering access to the softer sandstone beneath it.
Ellis Mining & Tunnelling offered the Wirtgen 2200SM surface miner to remove this cap. Various picks and drum speeds in the harder material were trialled to achieve the best compromise between costs and production, and the soft sandstone was finally exposed.
Production rates in the hard cap were 50 tonnes an hour but varied from 500 to 700 tonnes an hour in the softer material. The recovery rate – from 50 to 65 per cent – was a major improvement on traditional methods.
Ellis Mining & Tunnelling is working with Wirtgen and the quarry owner to reduce the costs of extracting the harder material on-site, but has found the Wirtgen surface miner an ideal, cost-effective method of extracting the softer sandstone that represents 90 per cent of the material on-site.
Source: Wirtgen Australia