CdS is located in the eastern part of the lower to middle greenschist facies archaean Rio das Velhas greenstone belt. The CdS I, II and III gold deposits and associated targets are located in a gold trend that extends for about 14km in a north-easterly direction, from Grota Funda (CdS I areas) in the south to Jambeiro (CdS III areas) in the north. The main gold targets and deposits are distributed over three trends, namely the CdS trend, the Donana Trend and the Cristina Trend. CdS mineralisation occurs in a greenstone belt geological environment, associated with quartz and sulphides (mainly arsenopyrite) in a structurally controlled corridor approximately 16 – 20km in strike length and about 500m vertical extent.

The CdS deposits consist of narrow north east/south-west elongated lenses of mineralisation dipping 60° to 70° south-east and plunging 20‚ to 30° north-east. CdS is an orogenic type deposit and comprises many hydrothermal lodes with quartz veins and low sulphide content disseminated in the wall rocks. The deposits are narrow, elongated and folded. In general, the mineralisation consists of sericitic zones and quartz veinlets.

The gold occurs as free and coarse gold and also as microscopic or sub-microscopic inclusions in arsenopyrite and sometimes iron-antinomy sulphide berthierite (FeSb2 S4). Other typical sulphide minerals are pyrrhotite, pyrite and chalcopyrite.

The Corrego do Sitio (CdS) complex is located in the municipalities of Santa Barbara and Barão de Cocais in Minas Gerais State, in the southeast of Brazil and consists of open pit and underground mines.

The underground mining method for CdS is sub-level stoping. Each panel consists of three levels with secondary development drives varying from 100m to 600m along strike. The stopes are around 15m high and the mining sequence method varies between top-down and bottom-up, which is only used in specific areas. Geotechnical parameters require that sill pillars are 4 to 7m high, and rib pillars 5m wide. The access into CdS I underground is by decline and into CdS II underground is by shaft.

The open pit operation uses conventional bench mining, with 8m individual benches and 3.2m berms. The material transport (ore and waste) is done by trucks and the excavation by a back hole. The rock breaking method varies according to the rock strength, using either explosives or mechanical excavation.

Corrego do Sitio (CdS) is operates of two metallurgical plants:

Corrego do Sitio 1 plant uses one distingt process for the production of gold, for oxide ore treatment. The heep leaching process is used to treat oxide ore and includes operations of crushing, leaching, adsorption, desorption/electrolysis and effluent neutralization.

Crushing
The ROM ore (Run of Mine) is trucked to the metallurgical plant yard whan it is crushed. Next step is agglomeration of the ore adding cement and water.

Leaching
After agglomeration, the ore is again transported by belt conveyor; while in an impermeable area a 20% concentration of NaCN strip solution (dye colored) is added, as the purpose of the pre-curing stage is to provide for an increased rate of gold extraction.The ore is arranged in heaps, each about 80 m long, 40 m wide, and 3 m high, stacked at an angle of repose of 38°. After the heap has been arranged, a 72-hour pre¬cure interval has to elapse befor ........