Bulong Ni Mine, Bulong Goldfield, Kalgoorlie-Boulder Shire, Western Australia, Australiai

Regional Level Types
Bulong Ni Mine	Mine
Bulong Goldfield	Ore Field
Kalgoorlie-Boulder Shire	Shire
Western Australia	State
Australia	Country

Nickel was the focus of attention at Bulong in the late 1990's, with far less success than the Bulong area gold chapter. In 1998 Preston Resources purchased the Bulong nickel deposit from Resolute Resources, in a complex deal for $319 million.

The ore is a laterite nickel deposit hosted in a nontronite clay zone. The intention was to pressure acid leach the material to extract the nickel. This technology had been used in Cuba since the 1950's, but had been unavailable for use elsewhere due to political reasons until the late 1990's. Few realised the technology as it stood at the time was unsuitable for most Western Australian laterite nickel deposits. Glowing reports were produced not only by the company, but independent media, about how another nickel boom was on the horizon, like that experienced in Western Australia in the early 1970's.

The process involves the ore going through an autoclave containing superheated acid at high pressure. The ore was having none of it. Magnesium at the deposit runs at 5-6% and is viewed in the process as an impurity which requires removal. More sulphuric acid was needed than anticipated, to the point they used up all available supplies in Western Australia, and had to import more at a high cost. The technology had worked in humid wet conditions, but the dry clay instead clogged the autoclave. The gypsum in the ore coated the pipes making them un-usable. Further, the nickel grade was only 1%, whereas the mines around Kambalda run at 3%. The high use of acid corroded parts of the processing plant that wasn't clogged. Costs skyrocketed, production levels plummeted. They persisted from 1998 to 2002, at which point the mine closed and Preston went into administration.

At the same time, the process was being used at two other Western Australian nickel mines with similar results. The Cawse nickel mine closed and Centaur Mining and Exploration sank under a sea of debt. The Murrin Murrin nickel mine run by Anaconda also ran into serious trouble. The shear size of this deposit probably saved it, and after the departure of Andrew 'Twiggy' Forrest, the mess was cleaned up. Twiggy went on to form Fortescue Metals, and become an iron ore squillionaire. Even as late as 2010, BHP abandoned its Raventhorpe laterite nickel project due to cost and processing issues.

At the time of writing (2012) Bulong is still in mothballs.

The Bulong Complex is a 37 kilometre long, folded and metamorphosed acid volcanoclastic, with an extensive tightly folded ultramafic rich sill zone. The structure has two opposite plunging synforms separated by an extensive saddle. Most of the sills are altered layered olivine rich rocks, with a few sills and rare dykes of altered pyroxenitic, gabbroic, dioritic and granophyric rocks. Large magma pulses produced olivine cumulate, and thin zones of pyroxene and pyroxene-plagioclase cumulate.

The altered layers are cumulate olivine and accessory cumulus chromite, in association with varying amounts of intercumular clinopyroxene, orthopyroxene, and plagioclase. Metaserpentinites form mesh textures, parallel vein texture, primary texture preservation, fibro-lamellar intergrowths, asbestos veins associated with magnetite, and abundant non-fibrous serpentine rich veins containing minor talc, carbonate, chlorite, amphibole, magnetite, and sulphide, associated with vesicular looking patches of dark green translucent serpentine. Antigorite is the dominant species with some chrysotile in weathered serpentine veins after relict olivine.

See also geology information for the Bulong North Complex Mindat listing, which contains the northern shallow pits.

Other Regions, Features and Areas containing this locality

References