The Uis tin project involves the redevelopment of the historic Uis hard-rock tin mine located in the Erongo region of Namibia.
The brownfield open-cast tin mining project is being developed by AfriTin Mining, a London-listed company that focuses on the development of tin assets in Namibia and South Africa.
AfriTin is developing the project in two phases, with phase one involving an estimated capital expenditure of £7m on a pilot processing plant capable of producing 60 tonnes (t) of tin concentrates a month.
The phase one pilot processing plant commenced partial operations in August 2019 while the first shipment of tin concentrate was delivered to Thailand Smelting and Refining Company (Thaisarco) in February 2020.
The throughput capacity of the pilot processing plant was increased from 5,800t of ore in December 2019 to 11,400t in January 2020, which is further expected to be ramped up to 45,000t to reach its nameplate capacity of producing 60t of tin concentrates a month by the end of 2020.
The phase two expansion, with an estimated capital investment of £42m, targets to produce 500,000t of tin concentrates a year.
Uis tin project financing
AfriTin Mining secured a £2.4m working capital loan from the Nedbank Namibia in August 2019.
Further, the company raised £3.8m by issuing convertible notes with the African tin trading group AfriMet, as well as some of its existing shareholders in November 2019.
Project location and site details
The Uis tin project comprises three mining license areas, namely ML 134, ML 129 and ML 133, in the Erongo region of Namibia.
The current project activities are located in the ML 134 that is spread over 197km², while the mining footprint is just 8km².
The site lies approximately 35km away from the Uis town and 333km away from Namibia’s capital Windhoek.
Geology and reserves
Tin at the Uis deposit is predominantly hosted in pegmatites and the ore bodies are found to be up to 40m-thick, along 500m strike length.
The mine was estimated to hold 71.54 million tonnes (Mt) of JORC-compliant measured, indicated, and inferred resources as of September 2019.
The contained tin is estimated to be 95,539t, while the contained tantalum and lithium oxide are estimated to be 6,091t and 450,265t, respectively.
Uis tin project background
The Uis tin mine was discovered in 1911, while mining was commenced in 1923. The mine was expanded after Imcor Tin, a wholly-owned subsidiary of the Iron and Steel Corporation of South Africa (Iscor), assumed ownership in 1958. It became the world’s biggest hard-rock tin mine in 1980.
The mining operations were, however, ceased due to the fall in tin prices in 1990.
AfriTin received environmental clearance for the mine redevelopment in August 2017 and started civil construction works for the phase one development in June 2018.
Ore extraction was started in December 2018, while the construction of the phase one processing plant was completed in July 2019.
AfriTin Namibia, the operator, holds 85% stake in the project, while the remaining 15% stake is held by The Small Miners of Uis (SMU), an enterprise owned by the Namibian Government.
Mining and processing at Uis tin mine
The conventional open-pit mining method involving blast-load-haul operations is employed for the Uis tin mine.
Mining is carried out in 10m-high benches, while loading and hauling are performed using a fleet of excavators and dump trucks.
The phase one pilot processing plant consists of a four-stage crushing circuit and a three-stage concentrating circuit.
The concentrating circuit includes dense medium separation (DMS), fine gravity concentration, and wet high-intensity magnetic separation (WHIMS) modules for the production of salable tin and tantalum concentrates.
The phase one pilot processing plant is capable of processing 500,000t of ore a year to produce 60t of tin concentrates a month.
In phase two expansion, the processing plant is planned to be scaled-up for three million tonnes per annum (Mtpa) throughput capacity.
Thaisarco agreed to buy the tin concentrate from the Uis mine for a period of one year, under an off-take agreement concluded with AfriTin in August 2019.
The agreement also includes an option to extend the off-take contract period beyond 12 months.
Power supply for the Uis tin mine
The Uis tin mine will receive power supply through an 800m-long, 66kV new transmission line connecting to an existing high-voltage power supply line of the state-run Namibia Power Corporation (NamPower).
NamPower will be responsible for the development of power transmission infrastructure for the project.
Environmental Compliance Consultancy (ECC) was engaged to undertake the environmental impact assessment (EIA) of laying the new transmission line to the mine site.