Following intensive and wide ranging metallurgical investigative testwork, BMR has decided to use a brine/acid leach based process carried out at an ambient pressure and temperature to recover lead and zinc from the tailings. This leaching process has been developed over two years in conjunction with Kupfermelt Metal Processing C.C. in South Africa.
Lead and zinc extractions for the Wash Plant Tailings of 90% Pb and 79% Zn have been achieved. Recoveries for the Leach Plant Residue are in the region of 80% Pb and 50% Zn.
The testwork has produced electro-won lead sponge and zinc cathodes; cemented lead, and zinc sulphate heptahydrate which has the potential to attract a price premium and has a potential market in Zambia.
Aerial Film of the Kabwe Operations
The brine/acid leaching process is the key to the success of the project yielding the good metal extractions at low potential cost in terms of power and consumables, with sulphuric acid being readily available at competitive cost from the Zambian copper smelters.
The current testwork is focused on finalising the flow sheet, the process design and establishing the quality of the products.
BMR and EPL have assembled a highly experienced and motivated team to deliver the project.
The treatment capacity of the Processing Plant will be approximately 5 tonnes/hour. The design of the Processing Plant has been a collaborative effort between the BMR technical team and Kupfermelt Metal Processing.
The Processing Plant will enable BMR to finalise the design parameters of the Main Plant using different combinations of tailings.
The Processing Plant will be operated as a semi-production unit to simulate actual operating conditions.
Leach Plant Layout
Processing Plant Plot Plan
On 5 May 2016, EPL received confirmation from ZEMA that its Environmental and Social Impact Assessment (ESIA) in respect of its tailings retreatment process and the construction of its planned Treatment Plants in Kabwe, which was submitted in December 2015, had been approved. The terms of ZEMA's approval include conditions typical in such projects, such as the requirement to conduct air modelling and hydro-geological studies and to install pollution abatement equipment prior to commencing operations, and to submit bi-annual results of its monitoring programme to ZEMA, as well as to ensure continuous vegetation of new tailings.
Although sections of the original Kabwe underground mine still contain unrecovered resources of lead and zinc, the considerable technical challenges of re-opening the mine at current metal prices make the likelihood of this happening remote.