Until recently, nickel laterite projects have been largely ignored,
due to their supposedly higher treatment costs compared with
sulphides, and to their perceived processing difficulties. A
number of laterite projects in the 1970s were abandoned because
of high capital and operating costs, while others experienced
severe technical difficulties. Conventional wisdom had it that
laterites would not be exploited until most of the sulphide
orebodies had been depleted. Why then, have Australian mining and exploration companies
started a resurgence of interest in the treatment of nickel laterites?
It all began with the Bulong project, which has been under study
since 1987, while more recently two further projects, Murrin
Murrin and Cawse, have been initiated and are being fast-tracked
to take advantage of the current high nickel and cobalt prices. A
further project in NSW, Syerston, has also been investigated at
bench-scale, but no further development has yet been announced.
All these projects have the following advantages: 1. Good location near a major mining centre and,reasonably
close to power, water, roads, accommodation and a
developed service industry. 2. Straightforward, low cost mining.
3. Low cost of acid or sulphur. 4. Good to very good cobalt credits. In addition, there have been significant technological
developments in the design and operation of high pressure
autoclaves and high rate thickeners, as well as solvent extraction
and electrowinning technology. This has helped to decrease
capital costs and technical risks, and has allowed the development
of alternative flowsheets to the existing laterite operations
(Taylor, 1996).