Proverb, dating back to 1772
I had just returned from my visit to family in Australia when I was faced with the latest issue of papers for the May Journal. To find a common theme from this mixed bag of topics was not as difficult as first anticipated thanks to some experiences on my visit. Our family in Melbourne is like almost all households in Australia, highly digitalized with five computers in a family of five. I and my laptop were very soon hooked up to high-speed facilities. Perhaps the most enjoyable were the 24-hour broadcasts from the Australian Broadcast Corporation, completely free of advertisements and excellently presented, authoritative and thoroughly informative and entertaining with news, topical, political, science, international and general discussion features.
High on the focus list of topics were global warming (real or science fiction?), the voracious appetite of China for raw materials, the looming world food shortages, the shortage of water for agriculture in many states, and a move to put the famous Murray/Darling Basin water scheme under federal control to restore it to some semblance of its former glory providing irrigation for 40% of the country’s food production. The common theme on most programmes was the avoidance of waste. And pollutants. Victoria and Melbourne were reeling in the throes of a seven-year drought. In our household and in most others in the neighbourhood, there were no baths, only a dribbling shower while one stood in a large basin to collect the water, which was poured into the most drought stricken part of the garden.
There is very little random waste in Melbourne. Soft vegetable waste goes into worm boxes for compost used in organic vegetable gardens. Glass, metal cans, paper and heavy organic waste is collected in separate bins. Rain tanks and solar water heaters are now pretty standard for many households. In summary, my impression is that Australia is moving resolutely to a zero-waste society, and this applies equally to its mining and metallurgical industry. But climate change is hitting hard and the looming threat of Kyoto penalties giving rise to fossil fuel savings is imminent. On my return, and looking at the list of papers in the forthcoming May Journal, I was struck that almost all of them were indirectly related to resources and waste materials in mining and mineral extraction.
By far the most mathematically erudite paper is ‘Geostatistical modelling of rock type domains with spatially varying proportions’. The Plurigaussian simulation model, had it been available at the assessment stage of the Phalaborwa carbonitite orebody, would have been invaluable in what was at that time a great step forward in openpit protocols with minimum waste material and maximum recovery of valuable content of the most complex mineralogical domains located in South Africa. Nevertheless, if one considers a list of materials initially dumped as waste, after recovery of the copper and phosphate, it is remarkable how many have been reinstated as saleable products.
And will continue to be of interest for many decades to come. Titaniferous magnetites are the best known examples. The importance of allocation of mining sorting and waste dumping protocols must today take into account the possibility that what is considered as waste might be recoverable in future. Pay limit determination is a statistical exercise. Waste material left underground, on the surface and finally on slimes dams very often becomes recoverable later. The value of such waste material in mining the platinum and chromium constituents of the Bushveld Igneous Complex are highly significant. The paper: ‘The development and implementation of industrial hydrometallurgical gallium and germanium recovery’ illustrates how minor elements of the periodic table in orebodies can suddenly become of cardinal importance in the electronics and super materials industry.
It was not too many decades ago that the europium content of the fluorapatite at Phalaborwa was the world’s richest occurrence of europium, a desperately needed constituent of colour TV tubes, but sadly never exploited commercially and left behind on waste dumps of phosphor-gypsum. The papers: ‘Development of a viable process for the recovery of zinc from oxide ores’ and ‘Outotec direct leaching Application in China’, are examples of how whole ore leaching is now being considered as an option coupled with the treatment of the waste solutions and residues for recovery of other subsidiary constituents, which can contribute some added value and provide for long-term waste disposal. As intimated in the papers, hydrometallurgy plays a key role in total metal recovery and toxic waste avoidance. I was most interested to learn that it is not impossible that there may be another bite at the cherry, Ergo style, at treating the waste residues from the gold mining activities of the Witwatersrand.
Ultimately and in the not too far distant future, these ‘golden mine dumps’ will contain nothing more than white fine silica sand for which a use will be found, maybe as a filler constituent in an innovative super–strength plastic composite. Or perhaps as a substrate for the new look in agricultural hydroponic fertigation. In past decades, the mining industry has an unfavourable reputation for waste dumping—waste coal dumps, waste slag heaps, waste boiler ash and waste calcium sulphate residues from acid neutralization added to that from treatment of apatite for phosphatic fertilizer production. Yet all these contain the elements most useful in our modern civilization: aluminium, titanium for dioxide pigments, constituents for building materials such as cement and plaster, and of course carbon, the most basic form of energy.
We are not too far distant in terms of economics and energetics from achieving useful conversions of such waste to useful products. Nor is the mining industry’s reputation as bad as most people think in comparison with other vital industries. Wasting electrical power is now a cardinal crime in terms of national conscience and very soon water wastage will be in the same category. A recent survey in the UK has shown that £9 billion of usable food is discarded every year. The efficiency of utilization of fertilizer and irrigation water in commercial agriculture is remarkably low at around 15%. It is easy to pontificate on the ‘waste not, want not’ crusade. It is much more difficult to achieve the balance between planned obsolescence and maximum sustainable profitability. A great deal of research and sophisticated simulation and modelling are needed to achieve the balance between abstinence and global competitiveness. In the light of impending shortages of some of the taken-forgranted essentials such as energy, raw materials, food and water, we can expect ominous outcomes arising from inefficient plundering of resources, and production and dumping of waste. Only continued technical innovation can keep our vision on the longer-term horizons. R.E. Robinson May 2008
- Written by R.E. Robinson