GPS APPLICATIONS AT OPTIMUM COLLIERY

Optimum Colliery is an opencast strip mine producing 18Mt of bituminou s coal per annum for the export and inland markets as well as for dome stic power generation at the Hendrina Power Station. Coal is exposed b y four 60m(3) and four 11m(3) walking draglines and transported from t he open cuts to the processing plants by twelve 130 ton coal haulers. Overburden and interburden areas are drilled by nine 250mm-diameter ro tary drill rigs. Until 1997 all surveying tasks were conducted by elec tronic total stations requiring accurate control points from which lin e-of-sight XYZ readings could be taken. In 1997 a GPS system was intro duced which consisted of a fixed base station and two revers. The reve rs were able to perform most of the survey tasks assigned to total sta tions. In addition, two overburden drills were equipped with blasthole drill navigation systems, which includes the drill monitoring and mat erial (strata) recognitions system. The rest of the drilling fleet wil l also be equipped with GPS systems. Blasthole positions are designed in the office based on survey and geological/geophysical information a nd transmitted via radio link to an industrial PC on the drills. Toget her with GPS positional data, both the planned and actual drill positi ons are displayed on an LCD screen. This eliminates the need for surve yed hole positions to be staked before drilling, and for actual hole p ositions to be surveyed after drilling. As holes are drilled, performa nce and rock property data transmitted back to the office. Future appl ications will include GPS monitoring of dragline positions and pad ele vations. GPS receivers on the draglines will utilize the existing base station to calculate and transmit XYZ coordinates. Another applicatio n will be locating of boreholes in the field prior to the pumping of s pecified explosive charges into the blastholes, Charging instructions for each blasthole will be loaded into the computer on the explosives truck which will be equipped with a GPS system for hole identification .