THE PROCESS OF ALUMINIUM PRODUCTION
Aluminium never occurs naturally in its pure state. It has been estimated that 8% of the earth's crust is composed of aluminium, usually found in the oxide form and known as bauxite.
All aluminium production is based on the Hass-Heroult
process. Alumina refined from bauxite is dissolved in a cryolite bath with
various fluoride salt additions made to control bath temperature, density,
resistivity and alumina solubility. An electrical current is then passed
through the bath to electrolyse the dissolved alumina with oxygen forming
at and reacting with the carbon anode, and aluminium collecting as a metal
pad at the cathode. The separated metal is periodically removed by siphon
or vacuum methods into crucibles, which are then transferred to casting
facilities where re-melt or fabricating ingots are produced. The major
impurities of smelted aluminium are iron and silicon, but zinc, gallium,
titanium, and vanadium are typically present as minor contaminants.
Refining steps are available to obtain high levels of purity. Purities
of 99.99% are achieved through fractional crystallization or Hoopes cell
WHICH COUNTRIES DOES IT COME FROM?
Three countries accounted for 60% of bauxite world output in 1994, Australia, Guinea and Jamaica, while the three leading alumina producing countries, Australia, the USA and the CIS together accounted for around 50% of total output.
Bauxite is one of the key minerals produced
by the African mining industry. Africa produces 16% of world bauxite. Out
of an estimated world total production of 109.1 million tonnes (1991),
Africa produced some 19.35 million tons. The leading African producer is
Guinea with an output of 17.5 million tons and one third of the world's
known bauxite reserves. Other major African producers of bauxite are Ghana
and Sierra Leone while Cameroon possesses bauxite reserves which are still
unexploited. Ghana, Cameroon and Egypt possess primary aluminium smelters.
Nigeria has a 180,000 ton capacity smelter under construction while in
South Africa, Alusaf has completed commissioning of a 466,000 ton capacity
aluminium smelter, the largest in the Western world and has announced plans
to build a smelter in Mozambique.
ECOLOGICAL IMPLICATIONS OF BAUXITE MINING
Bauxite mining involves the removal of an entire layer of the lateritic soil profile. Before mining, the trees are cleared and if possible utilised for timber. Then the topsoil is stockpiled and mining proceeds. After the bauxite has been mined out, the ironstone or clay underneath is deeply ripped and the topsoil is replaced. If the topsoil can be returned to a mined-out area after only a short time, it still contains most of the original soil fungi, bacteria and micro fauna. In addition, the seeds from the original community are more likely to be viable. On slopes, rigorous soil conservation measures are implemented, and the area is then normally planted with suitable native species so that it gradually reverts to bushland.
In the Darling Ranges of Western Australia there has been increasing success in this kind of revegetation as root penetration and nutritional problems have been overcome. Areas near Weipa on Cape York Peninsula and at Gove in Arnhem Land are also showing very good results. In all areas early revegetation had some setbacks as methods were being developed and improved. At Weipa 250 hectares per year are treated, and a total of over 50 square kilometres of revegetation has now been successfully established there. In connection with this work, a total of over 60 scientific papers had been published to the end of 1990, as well as research reports and theses. There has been a similar contribution to scientific knowledge from other long-established mining rehabilitation work elsewhere in Australia.
Thus land use on mining company leases is not
all digging and building. At Mount Isa, which had long been without adequate
water, the great Lake Moondarra was built in the midst of spinifex covered
hills. This project created a recreation area, wildlife reserve and reservoir
which was then almost unique in outback Australia. More recently the Lake
Julius dam was completed, and this created an even larger lake in the same
area. Behind the steel complex at Port Kembla the company has for many
years maintained l,300 hectares of its land as natural bushland for recreation
and nature conservation. This area is now a fauna and flora reserve.
ECOLOGICAL IMPLICATIONS OF BAUXITE REFINING
Once mined, Bauxite requires a fair amount of (electrical) energy to refine it into Aluminium.
For information on what is being done in Australia
to make the process of Aluminium production more eco-friendly, see: http://www.dpie.gov.au/resources.energy/environment/greenhouse/challenge/agreements/aac.html
SUMMARY OF ECOLOGICAL IMPLICATIONS OF WATER & ALUMINIUM POWERED ENGINES
Although it can be seen that the environmental impact of Aluminium production is far from negligible, the impact of billions of people constantly burning fossil fuels as a means of power and transport is far more serious.
As long as every effort is made to replace / replant any environment destroyed as a result of Bauxite mining, the biggest ecological cost of Aluminium production is creating the power needed to refine it. Indeed the Aluminium Oxide which the Hydrogen generator produces could be turned back into Aluminium. Hopefully in the near future the energy to do this will come from an environmentally friendly process (i.e. not nuclear or fossil fuel power). Methods already exist to extract energy from the sea and the wind. Methods may already exist (although not publicly) to tap into the vast abundances of energy which exist everywhere - after all there is far more energy in one gram of matter than all the power stations in the world produce in a year!
So the water / aluminium engine is not an ideal solution while we still produce electricity by non environmentally friendly means, but it is an essential design which can give us some breathing (literally!) space until our scientists come up with a method of tapping into the abundant energy which surrounds us everywhere.
If you have the intelligence and knowledge
to tackle these and other critical problems then it is your duty to do
so. After all what is the point in living out your life ignoring
the bigger picture, only for your descendants and species to die out when
the planet that supports them is poisoned beyond repair.