The nickel sulphide deposit at Trojan Mine occurs within a pile of ultramafic lavas subjected to a lower amphibolite grade of metamorphism and are characterised by lensoidal bodies of serpentinite. The lavas form part of the Upper Greenstones (Bulawayan Group) of the Mazowe greenstone belt. The serpentinite bodies are separated from each other by cherts, BIFs, graphitic shales and felsic volcanics. The footwall and hanging wall of the nickel bearing serpentinites are formed by komatiitic and tholeiitic basalts. A doleritic dyke cuts through the serpentinites and displays nickel sulphide along its sheared contact. The regional setting and deformation of the Harare-Bindura schist belt with thrusting and doming of the Chinamora batholith has given rise to the deformation imprint observed in host rocks at the mine. The general strike of the ore bodies is east–west and dip steeply (75° to 85°) to the north and this is controlled by the regional foliation trend. The two major ore bodies are the Main Orebody and the Hanging Wall Orebody. The massive and near massive ores occupy a narrow and discontinuous zone along the footwall of the Main Orebody and this is called the Footwall Massive Orebody. The Main Orebody is the largest, and averages 250m long and 30m wide. There are other smaller ore bodies such as Trojan Hill, Cardiff East and Cardiff Far East, with dimensions of 100m x 15m and 200m x 15m respectively. Drilling has outlined the Main Orebody to a depth of 1180m below surface. Approximately 300m of longhole drilling is still planned to increase the confidence in the geometry of the Main Orebody at depth, and reduce the variation on estimation of grade, for the current shaft deepening programme.

Three types of nickel sulphide ore are found at Trojan Mine, namely: massive ore, near massive ore and disseminated ore, whose main sulphide minerals are pyrrhotite, pentlandite and chalcopyrite, with pyrrhotite being the most abundant. Minor amount of millerite and pyrite are also present. The massive and near massive ores are situated towards the base of the ultramafic units and are overlain by the disseminated ore. The main and hanging wall orebodies contain all three types of mineralisation.

Trojan Mine employs a sub-level caving mining method to extract ore from the Main Orebody; and the Hanging Wall Ore body that are steeply dipping (some 75-85o) and separated by a barren zone some 50m in thickness. The ore bodies are accessed from drives installed in the foot wall on levels developed from a sub-vertical shaft system, from 7L to 35L (the lowest working level and some 1,130m below surface), that is used to hoist rock and transport men and material to the workplaces.

Main levels are installed at 60m intervals and comprise a tracked haulage. Sub-levels are installed at 15m intervals from a footwall ramp that is developed between main levels. Currently mining is being conducted between 29L and 31L and the average historical drop down rate is equivalent to some 35m vertical per year. This rate is forecast to increase as the future footprint of the ore body decreases. The stoping operation is fully trackless using long-hole drill rigs and LHDs for all cleaning. Development is partially mechanised with some hand held drilling but all cleaning is by LHD.

Underground ore is received into a 2.5kt live capacity silo ahead of a primary jaw crusher and a secondary and tertiary cone crushing circuit. Crushed ore at approximately 80% passing 12mm is conveyed to a conical stockpile. The crushed ore is delivered to three primary ball mills and the combined mill discharge is pumped to two classifying cyclones, with cyclone underflow being returned to two of the primary ball mills operating in closed circuit.

Trojan Mine Concentrator (“TMC”) incorporates two stages of flotation each comprising roughing and scavenging in low volume conventional cells with concentrate cleaning and re-cleaning also in low volume conventional cells. In primary flotation, coarsely liberated and faster floating minerals are recovered at a relatively coarse grind of 50% passing 75 micron. Primary flotation tails are reground to approximately 65% passing 75 micron ahead of secondary flotation, where finer and slower floating minerals are recovered. Flotation concentrates are thickened and filtered using rotary vacuum filters ahead of road transport to the Bindura Smelter and Refinery (“BSR”). Flotation tails are separately thickened before being pumped to the current tailings dam facility.