THE MINE

 

The mine on the Goro plateau will be opencast.  Ore will be extracted from a series of terraces and taken by dumper truck to the ore processing plant situated in the north-west of the mine. 
Key factors:

• 4 million tonnes of dry ore extracted annually;
• 12 million tonnes of earth shifted each year;
• 29 year mining plan;
• Mining pits that will be filled and replanted at the end of each mining cycle.

Mining activity

Mining exploration at Goro first began in 1969.  COFIMPAC, a subsidiary of Inco, carried out drilling there and this went on for several years. 

In 1992 Inco acquired mining rights for the deposit at Goro. Its composition of laterites with low nickel content made it an unattractive prospect as the processes in use at that time meant it was not possible to mine profitably.

In 2000 and 2001 an intensive programme was carried out in the mining zone of Southern Goro.  This involved drilling 600 boreholes and sampling.

Terraced opencast mining

The mine at the Goro deposit is opencast and dug to a depth of 50 to 60 m on a plateau area.

First of all, the superficial layers which have no commercial use will be cleared away.  A good proportion of this material will be used for construction (dams, verges, haulage roads, etc).  

The laterite and saprolite ore will then be extracted from a series of terraces using hydraulic excavators and bulldozers. Haulage will be carried out by a fleet of dumper trucks which will take the ore to the preparation unit opposite the excavated area. 

As the deposit is a single, continuous but thick layer, several faces will be opened laterally and vertically so that the entire profile can be extracted from the surface lateritic layer and the saprolite which is deeper down.

The hydro-geological study will show how best to manage the waters in the mining pit. The mine is a single pit which means that areas can be identified every five years for the disposal of waste from the hydrometallurgical process.  Thanks to this method, which includes a final replanting stage, the morphology of the plateau will be re-established. 

The objective of mining production is to provide the best possible control of nickel and magnesia content for the metallurgical plant, by processing these two types of ore in advance in the ore preparation unit.

mining operations

The ore preparation unit

The preparation unit is situated near the mine.

The ore is screened and ground and then mixed with water to create a combined pulp of limonite and saprolite. Rigorous control of chemical quality and particle size is undertaken.

The pulp is then conveyed via a pipe which extends for 8km to the autoclave at the processing plant. When it is in full production, the plant will process approximately 536 tonnes of pulp per hour.

• Coarse material is separated from the saprolite ore and disposed of. The waste is crushed and either used for construction or stored with the overburden where it will be used when the mining pit is gradually rehabilitated which will make it possible to replant the site.

• A further screening is carried out on the limonite and saprolite to remove more coarse material. As a precaution waste tanks have been constructed to enable regulated decantation from the pipe transporting the pulp to the treatment plant.

On the foreground the ore preparation unit and on the background the mine