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Successful recycling process developed for
smelting waste product
Melbourne Australia--November 16, 2001--
A world-first in treating a waste product from the aluminium smelting
industry has been developed at Portland Aluminium in Victoria’s south
west. The waste, spent pot lining (SPL), has been the subject of an
eight-year $26 million research and development program that harnessed
technology and expertise developed by Portland Aluminium, Alcoa Inc.,
Ausmelt Pty Ltd, and Australia’s CSIRO.
The Alcoa Portland SPL Process treats the hazardous waste and renders it
harmless. The process produces aluminium fluoride and a granulated
vitreous material referred to as ‘synthetic sand’. The
aluminium fluoride decreases the overall cost of the Portland Aluminium
operations by reducing the quantity of the expensive imported aluminium
fluoride required for the aluminium smelting process.
The synthetic sand has been given approval for unrestricted use by the
Environment Protection Authority of Victoria (EPAV), as long as it
continues to have fluoride leachability measures of less than 15 parts
per million. The Alcoa Portland SPL Process achieves this standard. The
EPA’s approval, granted on Tuesday this week, opens up opportunities for
the end product to be used in commercial applications such as road
making and concrete. Both products will conserve natural resources.
A paper - ‘The success of the Alcoa Portland SPL Process’ - will be
presented to representatives of 20 countries attending the Australasian
Aluminium Smelting Technology Conference, in Melbourne on Friday,
November 16.
SPL is a waste product of the electrolytic process in the smelting of
aluminium. Prior to treatment SPL is considered to be a hazardous waste
in various countries because it contains significant quantities of
absorbed fluoride along with traces of cyanide. The EPA’s acceptance
for these end uses means the Alcoa Portland SPL Process has treated the
hazardous waste material SPL successfully and converted it into non
hazardous useful products.
The disposal of SPL primarily has been in landfill because of
difficulties in the development of a successful techno-economic SPL
treatment process. Increasing concern about SPL land-filling practices
is resulting in regulations in some countries to ban this form of
disposal. As a consequence, stock-piling of SPL is occurring in an
increasing number of countries pending the development of a successful
treatment process.
Co-author of a paper to the conference, and Manager Spent Pot Lining
Project, Ken Mansfield, says the unique gas treatment process converts
hydrogen fluoride in the furnace offgases to aluminium fluoride in a
multi-stage fluidised bed reactor, designed by Portland Aluminium. “The
aluminium fluoride produced in the reactor has been trialed successfully
in Alcoa’s aluminium smelting process as a replacement for imported
aluminium fluoride,” Mr Mansfield said. “The installation in mid 2001
of a granulation system has enabled a granulated vitreous product with
excellent leachability qualities to be produced.”
Work on the Alcoa Portland SPL Process began in 1992 and involved
investigations into the suitability of Ausmelt’s submerged lance
technology furnace process for treating SPL. Portland Aluminium, Alcoa
and Ausmelt subsequently worked together on trials in Ausmelt’s
Dandenong premises until 1994.
Separate development work by Portland Aluminium, involving the CSIRO,
resulted in small scale production of aluminium fluoride from typical
offgases from the pyrometallurgical process and agreement was reached to
go ahead with the $26 million research and development program at
Portland.
COMPANY BACKGROUND
Portland Aluminium is a joint venture, which is owned by Alcoa of
Australia (55%), CITIC Australia Pty Ltd (22.5%) and Marubeni Australia
Ltd (22.5%). The joint venturers own one of the largest aluminium
smelters in the Southern Hemisphere located in Portland, Victoria,
Australia. The smelter is managed by Alcoa Portland Aluminium Pty Ltd,
trading as Portland Aluminium, a wholly owned subsidiary of Alcoa of
Australia. Alcoa of Australia Limited is an unlisted public company
whose principal shareholders are Alcoa Inc (60 percent) and WMC Limited
(39.25 percent). Alcoa is also the owner of the Point Henry aluminium
smelter near Geelong and the brown coal mine and power station at
Anglesea. The combined annual aluminium capacity of the two smelters is
more than 530 000 tonnes with most of it being exported.
In Western Australia Alcoa mines bauxite in the Darling Range south of
Perth and refines this material to alumina in its three refineries in
the south west region of Western Australia. Alcoa is the world’s largest
producer of alumina.
Note to editors: “Alcoa World Alumina” should not be contracted to
“AWA.” This acronym is the registered name of another company. In
second reference, please use “Alcoa.”
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