Chrome oxide green grinding mill, ore mill

Chrome ore mine

Chrome ore mine Locality – Chromite operations at Dwarsrivier Mine form portion of the Chrome Division of Assmang Restricted. The mine is situated on the farm Dwarsrivier 372KT, approximately 30 kilometres from Steelpoort and 60 kilometres from Lydenburg, in Mpumalanga province in South Africa. Situated at longitude 30°05'00"E/latitude 24°59’00”S, Assmang bought the farm from Gold Fields Restricted,

together with all surface and mineral rights in October 1998. copper ore crusher

Chrome ore mine History – Neighbouring properties for the north and south of Dwarsrivier had current chrome mining operations in the time of acquire. The Feasibility Study in the plant, tailings dam and styles for the open-cast and underground mines then commenced. After the completion in the Feasibility Study, approval to proceed using the final style and construction work was given in July 1999.

Chromite was obtained from the open-cast mining areas at a rate of approximately 0,9 million tons a year and these areas were mined out within five years. Underground mining commenced in 2005 at a rate of 1,2 million ROM tons a year. Dwarsrivier Mine is particularly geared to deliver high-quality metallurgical-grade chromite towards the Machadodorp smelter. Additionally, the plant has been created to generate chemical-grade merchandise. perlite ore crusher

Mining authorisation – An old-order Mining Licence 21/99 was granted in October 1999. It was granted for the mining of chrome and platinum group metals. An application for the conversion to a new-order mining appropriate was submitted during

October 2007.

Geology – Dwarsrivier Mine is situated inside the eastern limb in the Bushveld Complex, which comprises persistent layers of mafic and ultramafic rocks, containing the world's largest known resources of platinum group metals, chromium and vanadium. The mafic rocks, termed the Rustenburg Layered Suite, are roughly 8 kilometres thick within the eastern lobe, and are divided formally into 5 zones.

The rocks in the Marginal Zone at the base in the succession consist primarily of pyroxenites with some dunites and harzburgites. Above the Marginal Zone, the Lower Zone comprises primarily pyroxenites, harzburgites and dunite, and is present only in the

northern component with the Eastern Lobe, and only as far south as Steelpoort. The appearance of chromitite layers marks the begin in the Crucial Zone, economically by far the most significant zone.

The layers are grouped into three sets termed the Lower, Middle and Upper groups. The sixth chromitite seam inside the Lower Group (LG6), is an important source of chromite ore and would be the orebody becoming mined at Dwarsrivier Mine. In the Eastern Lobe, within the vicinity of Dwarsrivier, the strike is practically northsouth, having a dip of roughly 10 degrees towards the west. Average thickness in the LG6 seam is about 1,86 metres within the Dwarsrivier area. Pipe-like dunite intrusions are evident within the area, also as dolerite dykes that on average strike northeast-south-west. No considerable grade variation is evident, primarily not vertically inside the ore seam. Modest, insignificant regional variations do, nonetheless, exist. basalt stone crusher

Mineral Resources and Reserves – Facts was obtained from boreholes with 300 to 150-metre grid spacing. Resources had been determined with a decreasing level of confidence.

• Measured Resource (150 metres drill grid spacing).

• Indicated Resource (300 metres drill grid spacing).

• Inferred Resource (drill grid spacing greater than 300 metres).

All possible Resources down to a mineable depth of 350 metres beneath ground level have been deemed. Vertical diamond drill holes are made use of for geological and grade modelling, except where information and facts is required to clarify large-scale fault planes. The Mineral Resource at Dwarsrivier Mine is based on a total of 232 diamond drill holes that have been made use of for grade estimation and orebody modelling purposes. The drill core is NQ size and is geologically and geotechnically logged. The collar position in the drill holes is surveyed, but no down hole surveys are done, and also the holes are assumed to have minimal deflection.

The chromitite seam is bounded above and beneath by pyroxenites. As such, the ore horizon is clearly defined. The core is sampled from the top speak to downwards at 0,5-metre intervals. The core is split and half is retained as reference material within the core sheds. The other half is crushed and split into representative samples, which are crushed and pulverised for chemical analysis. The samples are analysed fusion/ICP-OES for chrome oxide (Cr2O3), SiO2, FeO, Al2O3, MgO and CaO. Three laboratories, all ISO 17025 accredited for this method, are utilised. Every tenth sample is analysed in duplicate. SARM 8 and SARM 9 standards, as well as in-house reference material (CRI), are integrated each and every 20 to 30 samples in every batch. The density for each sample is measured making use of a gas pycnometer.

Mineral Resources have been estimated applying Ordinary Kriging, where Cr2O3, FeO-, Al2O3, MnO and MgO-contents with the LG6 seam and densities were determined, using block sizes of 50 x 50 x 4 metres.

During mining, a slightly diluted run-of-mine ore inclusive in the “false” hangingwall is fed towards the beneficiation plant. In the dense media separation part of the plant, the coarse fraction is upgraded to 40% Cr2O3 using a yield of 80%. Inside the spiral section from the plant, the finer fraction is upgraded to 44% Cr2O3, and 46% Cr2O3 respectively, for metallurgical-grade fines and chemical-grade fines. A 67% yield is accomplished within the spiral circuit.

Year-on-year change – When compared to 2009, the 2010 Mineral Reserves improved by 3,86 million tons to 39,five million tons (35,64 million tons) and the Mineral Resources elevated by two,72 million tons to 50,60 million tons. The increase within the Mineral Resources was resulting from the extension in the block model by remodelling with the Indicated Resources. The raise in the

Mineral Reserves is resulting from the remodelling and incorporation of the "false" hangingwall. The latter brought on a decrease inside the Cr2O3 grade to 35,75% inside the 2010 model.