Ivanhoe Mines, the Canadian based – focused and diversified mining project developer is reportedly making headways in its underground diamond-drilling program at its Kipushi unit in the Democratic Republic of Congo.
The diversified miner, formerly known as Ivanplats said initial assay (sample) results from its 70 year-old Kipushi copper/zinc/germanium/lead and precious-metals mine, in the mineral rich Democratic Republic of Congo, had confirmed initial visual estimates of high-grade zinc and copper mineralisation in both the Big Zinc and copper-rich Serie Recurrente zones, info mine online reported citing the Mining Weekly.
According to the report, among the first significant results were three holes drilled to validate historical models of the down-plunge continuity of Big Zinc mineralisation, which returned zinc grades of 40.9 percent over 348.5 m, 44.8 percent over 339.4 m and 33.3 percent over 305.8 meters underground.
The down-plunge geometry of the holes did not allow it to estimate the true widths of the deposits, the Canadian company is cited as saying.
The exploration program found that internal zones of exceptionally rich mineralisation in the first two holes, KPU001 and KPU002, returned zinc grades of 60.4 percent over 35.1 m, 56.3 percent over 18 m and 56.6 percent over 71 metres. These internal zones also returned germanium grades of 87.2 g/t, 120.4 g/t and 111.9 grams a ton (g/t) respectively.
An internal copper/silver/germanium-rich zone in the third hole, KPU003, graded 6.1 percent copper, 44.5 percent zinc, 144 g/t silver and 66.9 g/t germanium over 31 m from 197 m. Historical resource estimates at Kipushi excluded silver and germanium.
The KPU003 also discovered a zone grading 58.6 percent zinc and 293.8 g/t germanium over 22.3 m, about 180 m below the historical measured and indicated resources. This exceptional grade intersection might represent an extension to the Big Zinc or the start of a new zinc- and germanium-rich zone, and would be followed up by ongoing drilling.
Further, Ivanhoe reported that two holes targeting the Serie Recurrente zone at the north end of the Kipushi deposit returned high copper and silver grades. Hole KPU008 intersected 11.4 m (estimated true width of 11.2 m) grading 17 percent copper and 89.6 g/t silver.
“Zinc grades of between 56% and 60% typically are found in high-quality zinc concentrates, rather than primary mineralisation. These initial assay results highlight the remarkable metal endowment of the mineralisation extending below the Kipushi deposit as previously mined by Gecamines,” Ivanhoe executive chairperson Robert Friedland is cited as having said recently.
“At current spot prices of about $2 000/kg for germanium and $21/oz for silver, we expect the germanium and silver grades could add to the overall metal value at Kipushi. Sulphur content, particularly in the Big Zinc, also represents a potentially significant value addition given the scarcity of primary sulphur supply in the Copperbelt region and the demand for acid in conventional in-country oxide recovery circuits,” CEO Lars-Eric Johansson added.
Additionally, Ivanhoe stated that Kipushi staff were continuing to upgrade underground and surface infrastructure to support the drilling program and prepare the mine for potential future redevelopment and operations, subject to engineering and other studies. The mine had been dewatered to the 1 305 m level on the Cascade side (Shafts No 1 to 4), where drilling operations were taking place.
The scope of drilling had been expanded to evaluate the high-grade, copper-rich Serie Recurrente zone. The 1 272-m-level hanging-wall drill drift had been dewatered and was being prepared for drill access. Drilling from this level was expected to start once the Serie Recurrente program was completed.
This drill access would facilitate detailed confirmatory and exploratory deep drilling of the Big Zinc, and of down-plunge unmined extensions to the copper-rich northern portion of the historical Kipushi deposit. Also on the Cascade side, a water dam was being built on the 1 112 m level to reduce pumping requirements. Fabrication of a new ventilation fan for Shaft No 4 was complete and the fan would be commissioned later this month.
Refurbishment of the No 5 shaft was ongoing, with the hoist ropes being replaced. Soon after resuming operations, the main pump station would be refurbished at the bottom of the shaft, improving the efficiency of pumping operations, and delivering mechanised underground equipment to the active part of the mine.
According to the report, In the Kipushi mine’s 70 years of operation, 60-million tons of material was extracted at a grade of 6.78 percent copper and 11.03 percent zinc. In addition, 400 000 t of lead, 45 000 t of cadmium and 120 t of germanium were extracted through the existing processing plant.
Kipushi currently has a historic measured and indicated resource – stated only to the 1 500 m level – of 16.92-million tones, grading 2.32 percent copper and 16.76 percent zinc.
Ivanhoe Mines also owns the high-grade Kamoa copper deposit in the DRC, as well as the Platreef polymetals project, in South Africa.