Name and Location
Forrestania mill recovery enhancement project, Australia.

Client
Western Areas.

Project Description
The mill enhancement project will process one of the tailings streams from one of the flotation plants that contain valuable amounts of nickel that cannot be recovered into concentrate using traditional flotation methods. This stream will be leached at atmospheric pressure using the Western Areas patented BioLeach technology in fiberglass reinforced polyvinyl chloride tanks to recover the additional contained nickel.

The BioLeach process has been developed to operate at a pH of 3 to 3.5, which enables the removal of iron and other gangue elements during the leaching stage to form stable compounds for safe disposal in the company’s existing tailings storage facility.

A conventional thickener and filter are used to dewater the leach circuit. The solids are discarded to tailings and the filtrate is passed to the sulphide precipitation circuit. Sodium sulphide is used to recover the nickel from the solution and will produce a nickel-in-concentrate product grading between 50% and 60% of nickel. This high-grade nickel concentrate will be combined with the processing plant’s normal nickel concentrate of 14% to 14.5% nickel to produce an overall slightly higher-grade nickel concentrate. It will take seven days to produce a nickel concentrate for blending into existing material.

Mill recoveries will increase to between 3% to 5% over the life-of-mine and up to an additional 1 200 t/y of nickel in concentrate is expected to be recovered.

The project has been designed to complement any existing flotation circuit to enable the recovery of valuable sulphide minerals, such as nickel, copper, zinc, which cannot be recovered by conventional flotation. Consequently, Western Areas believes that this process can have significant positive results for several base metal projects worldwide considering the improvement in metals recovery. An additional potential benefit might, therefore, arise from demonstrating the patented BioLeach technology in this niche application.

Net Present Value/Internal Rate of Return
The project has an internal rate of return of 39% and a payback of 39 months using consensus nickel prices.

Value
The project has an estimated capital cost of A$22-million.

Duration
The project has an estimated construction period of six months, which could start on July 1, 2016.

Latest Developments
GR Engineering Services has been awarded an engineering, procurement and construction (EPC) contract as part of a guaranteed maximum price arrangement.

Key Contracts and Suppliers
GR Engineering Services (EPC).

On Budget and on Time?
Not stated.

Contact Details for Project Information
Western Areas, tel +61 8 9334 7777, fax +61 8 9486 7866 or email info@westernareas.com.au.
GR Engineering Services, tel +61 8 6272 6000, fax +61 8 6272 6001 or email gres@gres.com.au.