Evander Gold Mine

 mine, gold mine

This is the Mining Right for the Evander Operations which are owned and operated by Harmony Gold. The Evander operation (Evander 8), located in Mpumalanga, mines the Kimberley Reef in the Evander Basin. Ore mined is milled and processed at the Kinross plant, which has a hybrid CIP/CIL process. Evander 8 shaft has an expected life-of-mine of around 11years. A project to deepen this shaft, by means of an additional twin decline system down to 25 level and extensions to the infrastructure, is currently under way. Following a review by Harmony of uneconomical operations, the Evander 7 shaft ceased production given that its orebody had been depleted while the Evander 2 and 5 shafts were closed.

The Evander operation employed 3 331 people – 3 052 employees and 279 contractors – in FY10.

Operations review

Ore milled for the year totalled 788 000 tonnes, a decline of 30% on FY09. This together with a decline in grade resulted in a 41% decrease in gold produced to 111 724 ounces. This drop in operational performance was caused by a combination of factors, the most significant being the restructuring during the year of the Evander operations. A due diligence of these operations – Evander 2, 5, 7 and 8 – led to the conclusion that the only economically viable shaft was Evander 8. Mining operations at Evander 2, 5 and 7 shafts thus ceased during the year and Evander 8 was restructured. The shaft infrastructure at Evander 7 will be utilised by Evander 8 for the pumping of water and the hoisting of rock as well as being available for use as a second escape. High temperatures underground, caused by ventilation return capacity restrictions at Evander 8, remained problematic and hampered production.

Once the restructuring of Evander had been completed, a feasibility study was undertaken which proved the viability of Evander 8. Greater attention was thus given to this shaft and a re-engineering project was implemented which involves not just the deepening of the decline but its repositioning within the payshoot. This will give immediate access to the high-grade areas between 24 and 25 level, and will contribute to improved productivity with consequent financial benefits. The project’s parameters include the optimisation of logistics, cooling and ventilation as well as an upgrade of the refrigeration plant. It is estimated that, on a monthly basis, this project will yield 245 kilograms (7 876 ounces) from 29 000tpm at an average grade of 8.56g/t. The monthly capacity of the conveyor belt is to be upgraded to 46 000tpm.

Following the closure of the Evander 2 and 5 shafts as well as the Winkelhaak plant, a one-year clean up programme was begun at and in the vicinity of the plant. The aim of this programme, which will continue into FY11, is to clean up any metal contained in the plant footprints, to process rock from the dumps in the vicinity, to rehabilitate the Winkelhaak plant, and to clean the surface rail network. In FY10, around 292 642 tonnes were treated via this programme at a recovered grade of 1.81g/t, yielding 528 kilograms (16 975 ounces) of gold.

Current productivity rates of 93g/TEC are planned to increase to an average of 145g/TEC over the remaining life of this operation.


Geology

The Evander Basin is a tectonically preserved sub-basin outside the main Witwatersrand Basin and forms an asymmetric syncline, plunging to the north-east. It is structurally complex with a series of east-north-east striking normal faults. At the south-east margin of the basin, vertically to locally overturned reef is present. The only economic reef horizon exploited in the Evander Basin is the Kimberley Reef. The Intermediate Reef is generally poorly mineralised, except where it erodes the sub-cropping Kimberley Reef to the south and west of the basin.

Reference for information:
www.har.co.za/evander.htm
www.har.co.za/businessreview_mineral_eastrand.htm
www.silver-info.com/harmony-gold-presentation.htm

Reference for article about shaft work:
www.saimm.co.za/Conferences/ShaftSinking2009/06a-Strach...


General:

www.harmony.co.za/b/res_tbl_doornkop.asp

www.bomar.co.za/projects.htm

www.referenceforbusiness.com/history2/80/Harmony-Gold-M...

deepbio.princeton.edu/samp/evander.htm