The phase II expansion of the Gamsberg zinc mine in the North Cape province, South Africa is planned to double the mine capacity to eight million tonnes per annum (Mtpa) of run-of-mine (ROM) ore.
Black Mountain Mining (BMM) is the owner and operator of the mine. The company is 69.6% owned by Indian mining firm Vedanta, through its subsidiary THL Zinc, while Exxaro Base Metals and Industrial Minerals Holdings, a subsidiary of Exxaro Resources, holds a 24.4% stake. The remaining stake of 6% is held by the Voorspoed Trust.
Vedanta approved an investment decision on phase two expansion of the zinc mining project in March 2022. The expansion will be carried out with an estimated investment of £354m ($466m) to produce additional 200 kilo-tonnes per annum (ktpa) of zinc-in-concentrate (MIC) from the mine.
The Gamsberg zinc project is estimated to have the potential for phase three expansion with an option for underground mining to further increase the production by 150ktpa of MIC.
Gamsberg is the largest zinc mine in Africa, with an estimated mine life of more than 30 years. The mine recorded a production volume of 145kt in the financial year April 2020- March 2021.
Location, geology and mineralisation
The Gamsberg zinc mine is located in the Khâi-Ma municipality, Northern Cape province, South Africa.
The site lies approximately 30km from the Black Mountain Mining site in Aggeneys town and 120km east of Springbok town, along the national route N14.
The Gamsberg deposit is located in the Aggeneys area that occurs in the Precambrian metavolcanic metasedimentary Bushmanland Group, part of the Namaqualand Metamorphic Complex.
It is a Broken-Hill type deposit that forms that part of the Bushmanland Group, a volcano-sedimentary categorisation hosting the ore deposits. It consists of pyrite-pyrrhotite-sphalerite type ore hosted by quartz-biotite-sillimanite gangue.
The mineralisation occurs as magnetite-rich banded iron formations in the form of discrete massive sulphide bodies.
The Gamsberg zinc mine was estimated to contain a reserve and resource of 214Mt with a grading of 6% - 6.5% zinc, as of January 2019.
The ore deposit is located at Gamsberg North, Gamsberg East and Gamsberg South.
Mining and ore processing
The Gamsberg zine mine is an open-pit mining operation employing a conventional drilling and blasting method, followed by loading and haulage.
The ore is processed through crushing and milling operation, before it is sent for aeration and flotation procedure, and eventually to the concentrator for zinc concentrate production.
The final product is transported to the Saldanha port, located on the west coast of South Africa, via trucks for shipment by sea.
Gamsberg phase two infrastructure details
The phase two infrastructure at the Gamsberg mine will involve the construction of a second concentrator stream with a capacity of 4Mtpa.
The required facility is estimated to produce approximately 200 to 250ktpa of additional zinc-in-concentrate.
Gamsberg smelter-refinery development
The development of a zinc smelter-refinery facility is being planned for Gamberg to make the mine a fully integrated zinc production operation, with the mine, concentrator, and a smelter-refinery complex placed at a single site.
The smelter complex is proposed to utilise a Roast-Leach-Electrowinning (R-L-E) with Jarosite precipitation and Jarofix conversion process for concentrates produced at Gamsberg.
The complex will be designed with a capacity to produce 250ktpa of finished zinc metal.
Gamsberg zinc mine phase one details
Developed with an investment of $400m, the phase one of the Gamsberg zinc mine comprises an open-pit mine, concentrator and related infrastructure.
The other infrastructure includes a tailing pipeline to the high-density polyethylene-lined tailings storage facility (TSF). Located 3.2km from the concentrator plant, the tailing dam is capable enough to store approximately 3.55Mtpa of tailings.
The support facilities include a 40MVA power transmission line from the ESKOM substation, a 66/11kV main receiving substation (MRSS) at Gamsberg site, a 38km-long water pipeline from the Orange River, and other building infrastructure.
Gamsberg has a design production capacity of 4Mtpa of ore and 250ktpa of zinc concentrate under phase one. It is estimated to have a mine life of 13 years in phase one.
Vedanta Group acquired a zinc oxide orebody asset, including Gamsberg, from Anglo American in 2011.
Discovered in 1977, Gamsberg is one of the world’s largest zinc deposits. The first blast at the site deposit took place in 2015 and the zinc mine started trial ore production in 2018. Commercial production at the site began in March 2019.