FEATURE - New aluminium process aims to cut pollution
Date: 26-Oct-01
Country: UK
Author: Jeremy Smith
An innovation to standard electrolysis, the traditional way of producing the world's most widely used industrial metal, is now being seen by industry experts and environmentalists as a key to serious pollution reduction.
Most children learn the basics of electrolysis at chemical-spattered desks in their school science labs, wiring up electrodes to a battery and then passing an electric current through copper sulphate solution to produce a thin coating of copper metal on the cathode, or negative electrode.
The principle is broadly the same for aluminium production.
The smelting process demands vast amounts of energy, which causes many producers to locate their plants close to areas where there is good access to power resources.
But it also eats up a great deal of carbon, most of which eventually spirals up into the atmosphere as either carbon monoxide or dioxide. About 430 kilograms of carbon are needed to process just one tonne of aluminium metal, experts say.
Now, the aluminium industry is eager to develop a non-carbon anode, or positive electrode, that is not consumed by oxygen during electrolysis. Instead, it would actually release oxygen.
While still undergoing tests, the new "inert anode" would be made of another metal such as nickel or iron. In theory, this should reduce not only pollution but also cut producer costs - possibly by as much as 20 percent, manufacturers say.
"It still has to be demonstrated in practice but if this works, then we'd definitely have a significant improvement in the environmental situation," said Eirik Nordheim, environment director at the European Aluminium Association (EAA).
"In theory, if you get rid of the carbon anodes, you would have a situation in the electrolysis where you would be actually emitting oxygen instead of carbon dioxide," he said.
ALL EYES ON ALCOA'S ANODE RESEARCH
So far, the world's largest aluminium producer Alcoa Inc. has been blazing the trail with inert anode technology while the rest of the industry waits to see the results, although some others are also conducting research projects.
The U.S. company started operation of one commercial inert anode "pot", or electrolytic cell, earlier this year and hopes to have a "potline", or row of bath-tub like cells, running in the first three months of 2002.
"The first thing is that Alcoa, or somebody else, has to show that this is working in an operating cell. As far as we know, this hasn't really been shown over a longer period of time in any full-size cell in an operating situation," said Nordheim.
"It's a long way away...but from the day it's really shown that this is working, then we're talking a little shorter time."
In a statement to Reuters, Alcoa said development of the technology was "progressing well" and would generate large production savings if it proved commercially viable.
"Assuming the technology proves to be commercially feasible, Alcoa believes that it will be able to convert its existing potlines to this new technology, resulting in significant operating cost and capital investment savings," it said.
"However, we're not relying on technology alone to lower costs. Operating and productivity improvements are continuous activities and will ensure our plants are among the world's low cost facilities," the company added, without elaborating.
CARBON DOMINATES TRADITIONAL ALUMINIUM PRODUCTION
While aluminium ranks as the third most abundant element in the earth's crust, it is still perceived as a "young" metal, according to the International Aluminium Institute. In contrast, mankind has used copper, lead and tin for thousands of years.
But it is not found free in nature and must be refined into its pure silvery-white state from its oxide, alumina, which is produced from bauxite - an ore mainly found in the tropical and sub-tropical regions of Latin America, Africa and Australia.
Scientists spent many years of painstaking research to "unlock" the meta