AGGENEYS

Aggeneys

AGGENEYS (Aggeneys) is the large polymetallic ore field in the South Africa (Northern Cape Province). It includes the deposits Black Mountain, Broken Hill, Big Syncline. It has been discovered in 1929, the industrial ore content has been established in 1970.

The mineralization is in the conjunction with the Namaqualand Lower Proterozoic metamorphic complex, which is represented by the series of the alternating mica schists, ferruginous quartzites, and carbonate rocks, which are embedded accordingly on the thickness of the basal gneisses. The ore bodies of the tabular and lenticular forms are localized in the nuclei of the synclinal folds, gently plunging to the east. The ores are metamorphosed.

The ore minerals are galena, pyrrhotite, sphalerite, chalcopyrite, magnetite, and the non-ore minerals are garnet, quartz, biotite. The texture of the ores is massive, banded, interspersed. The content of the ore is: 1.1-6.3% Pb, 0.5-2.9% Zn, 0.04-0.8% Cu, and 16.0-90.2 grams per tonne Ag. The ore reserves by the deposits are (1978, million tonnes): Big Syncline 101, Black Mountain 86.0 (30 are suitable for the open pit development), Broken Hill 72. The mining and beneficiation enterprise is created on the basis of the deposits by the "Black Mountain Mineral Development Comp. Ltd." company.

The development of ores is performed by the open pit and underground methods. The ores of the Broken Hill deposit distinguish themselves by the greatest metal content. The underground communications in this deposit include the vertical shaft with the diameter of 5.5 metres and the depth of 400 metres, and the spiral slope with the cross section of 3.7-5.5 metres and the total length of 1,800 metres, which has the access to the surface and connects to the mine shaft at the depth of 350 metres. In order to develop the sections of the ore body with the angles of the dip greater than 50 degrees, they are working the sublevel drifts with the breaking out of the ore by the deep inclined boreholes.

The worked out space is filled with the rock, and is cemented by the dune sand and the material from the tailings. For the more gently inclined embedding of the ore body, the method of the mechanical development is used, also with the filling of the mined-out space. The reserves of the ore within the mining lease of the enterprise are 38 million tonnes with the average content in the ore of Pb 6.35%, Zn 2.87%, Cu 0.45%, and Ag 80.9 grams per tonne. Since the middle of 80's, it is expected to annually extract 1,125 million tonnes of the ore by the open pit and underground mining methods.