The geological succession at Two Rivers Platinum Mine is broadly similar to other areas of the eastern limb of the Bushveld Complex. An exception is the presence of the Steelpoortpark granite in the south-western part of the project, which is unique to this area. At Two Rivers, both the Merensky and UG2 reefs are present, but only the UG2 Reef is currently exploited, with Merensky Reef mining anticipated in the near future. The middlingbetween the Merensky Reef and the UG2 Reef is approximately 140 metres to 160 metres, although this reduces significantly in the northern part of the mine, to about 70 metres.

The UG2 Reef outcrops in the Klein Dwarsrivier valley on the Dwarsrivier farm, with a north-south strike length of 7.5 kilometres, dipping to the west at between 7º to 10º. The elevated topography results in the UG2 occurring at a depth of approximately 935 metres towards the western boundary. The UG2 is bottom loaded with peak PGM values occurring in the basal 10 centimetre portion.

The following reef facies have been defined for the UG2 at Two Rivers Platinum Mine:
• UG2 Normal Reef facies which is characterised by a 100 to 120 centimetre-thick chromitite overlain by up to three chromitite “leaders” collectively termed the UG2A chromitites;

• UG2 Split Reef facies in the southern, west-central and north-eastern parts which is characterised by a chromitite seam that is separated by a layer of a fine to medium-grained internal pyroxenite unit;

• The UG2 Multiple Split Reef facies which is represented by multiple splitting of the UG2 chromitite by internal pyroxenite. It occurs mainly in the southern section of the mine on the Dwarsrivier farm as well as the east-central section of the Buffelshoek farm.

The Merensky Reef consists mainly of orthopyroxene with lesser amounts of plagioclase and clinopyroxene. Thin chromitite layers, usually 1 to 4 millimetres thick, occur near the upper and lower contacts of the reef. The Merensky Reef has variable thickness but generally reduces in thickness from the Dwarsrivier farm towards Kalkfontein and Buffelshoek farms. The regional northnortheast to south-southwest trending Kalkfontein fault, with a vertical displacement of up to 1 000 metres down-thrown to the west, defines the limits of the eastern structural domain for both the UG2 and Merensky reefs.

The ground beyond this fault remains an exploration target where both reefs are at depths in excess of 1 000 metres. Both reefs are affected by the granite intrusion in the southern portion of the Buffelshoek farm where both reefs are absent.

The UG2 Reef is accessed via two decline shaft systems situated 3km apart, namely the Main Decline and the North Decline. Production of the UG2 Reef is through a fully mechanised bord and pillar stoping method. A mining section consists of 6m, 8m and 10m bords, with pillar sizes increasing with depth below the surface. The pillars are 6m x 6m to 12m x 12m in size. The bords are mined mainly on strike.

Conventional drilling, blasting and scraper mining is utilised in the stoping and secondary development areas. Drilling of the main development faces are done by means of mechanised drill rigs, whilst stoping, secondary development and support drilling is done by pneumatic hand-held drills. Explosives are transported to the faces by means of an explosives carrier and charged up. The broken rock is loaded with load haul dumps (LHDs) and transported with dump trucks to the tipping points.

Stoping sections exercise a multi-cycle operation during a shift. The full mining cycle in an eight bord section comprises two faces being drilled, two faces being cleaned, two faces being supported, with two faces standing idle. All the various phases are decoupled from one another, which assists in productivity. The two faces standing idle are essential when geological discontinuities are encountered as this provides additional face flexibility.

Construction of the Merensky Reef section commenced. The mining method will also be based on fully mechanised bord and pillar mining.

Crushing
ROM and stockpile ore is crushed from 400mm to -90mm size in a primary jaw crusher. This is further crushed to -20mm in a cone crusher that operates in closed circuit with a vibrating screen. The secondary crusher was an addition to the circuit to enable the milling rate to be increased by providing the primary mill with smaller feed.

The primary and secondary crushing plants are located halfway between the Main Shaft complex and the TRP plant, such that ROM ore existing the Main decline is first conveyed ~1km to a coarse ore silo over a section of overland conveyor. Ore from the crushing plant is subsequently conveyed to the fine ore silos, located at the TRP process facilities.

Milling
The standard MF2 process flow is employed, namely mill - float; mill – float. There are two Vecor ball mills installed in series, individually powered by 5,200 kW Alstom motors:
- One 24ft (grinding length) Primary mill;
- One 26ft (grinding length) secondary mill.

Primary milling is to 35% -75 microns. Secondary milling is to 75% -75 microns. The mills are installed in closed circuit with cyclone banks, which perform the separation of material, based on the size, with the undersize (overflow) from the cyclones being directed to the flotation plant, while the oversize (cyclone underflow (being returned to the mills).

Two Rivers has a concentrator plant on-site where initial processing is undertaken. It comprises a standard MF2 design as generallyused in the industry for UG2 Reef ore. A new concentrator will conduct Merensky Reef processing. Concentrate is transported by road to Impala Mineral Processes in Rustenburg, where further processing occurs in terms of an agreement with Impala.

At the Two Rivers Platinum Mine, which ARM manages, material from the UG2 Reef is milled and processed to recover the PGMs at the mine’s MF2 PGM concentrator. The chromite recovery plant then reprocesses the UG2 Reef tailings generated by the concentrator to recover the chromite. The chromite recovery plant was commissioned in 2013 and is owned and operated by Two Rivers, which also has an offtake agreement with Chrome Traders whereby all of the concentrate produced is purchased on a free carrier basis from TwoRivers. Currently, some 280kt per annum of chromite is produced at a Cr2O3 grade of 40.1% and a ........