Pollution from the Mozal aluminium smelter, with or without filters, is insignificant compared with pollution from slash-and-burn agriculture, motor vehicles or wood fuel, academics from the physics department at Mozambique’s Eduardo Mondlane University argued on Thursday.
They were speaking at a public meeting held by Mozal in the southern city of Matola to explain plans to rebuild the smelter’s Fume Treatment Centres (FTCs). The plans mean that for six months the emissions from the smelter’s anode bake plant will go straight into the atmosphere and will not pass through any filters.
Environmentalist organisations have claimed, without any supporting evidence, that this will be extremely damaging to the environment and to human health. But independent studies have backed up the claims by Mozal that, even without the filters, the emissions will still be lower than the levels recommended by the World Health Organisation (WHO).
At the Thursday meeting physicist Juliao Cumbana told the audience that he is a victim of air pollution. One of his lungs is irreversibly scarred because of the dust particles he inhaled when he was a child.
But this pollution did not come from any factory – the dust that damaged Cumbana’s lung came from the firewood and charcoal that his aunt used to cook the household meals.
Cumbana and his colleague Amin Naran pointed to studies on air quality in Maputo and Matola. These found that the air is much cleaner around Mozal and even around the Matola cement factory, than it is on the major roads through Maputo, or in the bustling market areas of Xiquelene and Xipamanine. Road transport and domestic fuel were easily the largest contributors to urban pollution.
A university study from 2007 showed that the bush fires used to clear land for agriculture put almost 465,000 tonnes of dust (particles less than 10 microns thick) into the Mozambican atmosphere annually. The annual dust contribution from domestic fuel (firewood, charcoal and kerosene) was over 36,000 tonnes, while the production of charcoal resulted in over 13,000 tonnes of dust.
Compared with this, Mozal’s contribution is miniscule. The university team found that all Mozambican industries put together produced less than 500 tonnes of dust a year.
Cumbana pointed out that the Mozal emissions are released from chimneys that are 60 metres tall, and are diluted by the time they descend to ground level. The aluminium smelter, he stressed, “causes less pollution than our day-to-day activities”.
In the 1970s, he admitted, aluminium smelters had been highly polluting. But there have been huge technological advances since then, and Mozal is a modern smelter, using technology that is advance of anything found in such longstanding aluminium producers as the United States or Russia.
The major pollutant from aluminium smelters is hydrogen fluoride – but there is no conspiracy by Mozal to dump large quantities of fluoride in the atmosphere, argued Cumbana. Quite the reverse – fluoride is a raw material in the production of aluminium and so Mozal recycles as much of it as possible.
In any case, the concentration of fluoride from the Mozal chimneys “is much lower than you get from smoking a cigarette”, he added.
Cumbana pointed out that aluminium was now the second most common metal used in human activities, and anyone who drove to the meeting had done so in a car that largely consists of aluminium. “We want more aluminium smelters. This is the metal of the future”, he declared.
This was not what environmentalists in the audience wanted to hear, and some of them tried to interrupt Cumbana. One leapt to his feet and demanded that the moderator of the debate gag an inconvenient academic who refused to demonise heavy industry. The Maputo provincial director of environmental action had to intervene to calm down the meeting.
Mozal President Mike Fraser stressed that the smelter had no option but to rebuild the FTCs. This was because of serious structural problems which, if untreated, could lead to a “catastrophic collapse”. The steel sheets in the FTCs should be eight millimetres thick. Engineering inspections have shown that in places, at the base of the structure, the steel has corroded to a thickness of just one millimeter.
One participant suggested shutting the smelter down while the FTCs were rebuilt. Fraser pointed out that aluminium production is continual, 24 hours a day. If the power is turned off, so that there is no electricity flowing into the electrolytic furnaces (known as “pots”) where alumina is turned into aluminium, then the pots will freeze and become useless.
The smelter could not be switched off and restarted six months later. The damage would be such that all the potlines, which are the greater part of the smelter, would have to be rebuilt, at vast cost.
A second Mozal official, Alexandre Sitoe, said that when Mozal asked for permission to operate without the FTC filters for six months, the government set up a team consisting of experts, not only from the Environment Ministry, but also from the Health, Planning and Development, Industry, and Energy Ministries, and from the university. They carried out “a detailed and exhaustive study”, which took six months and reached the same conclusion as Mozal – that operating without the filters would not cause serious health or environmental damage.
The WHO recommendations allow fluoride concentrations of up to 17 micrograms per cubic metre. The studies indicate that, even without the filters, the concentrations caused by Mozal will not exceed 9 micrograms per cubic metre.
Under Mozambican legislation, dust emissions should not exceed 200 micrograms per cubic metre. WHO is working towards a much stricter limit of 50 micrograms per cubic metre. But Mozal claims that, even on a worse case scenario, dust emission will not exceed 40-50 micrograms per cubic metre. Furthermore the dust does not spread much beyond the immediate area of the smelter, and will not reach Matola city.
Antonio Rainha, of the environmental organisation Livaningo asked “if the emissions are so innocuous, why do we need the filters at all?”
Fraser replied that the filters made a considerable cumulative difference over the entire lifetime of the plant, but operating without them would not cause serious damage in the relatively brief space of six months.
He stressed that the FTCs are not merely being rebuilt, but also improved, so that there would be a faster flow of emissions through them. With these improvements, Mozal believed that the structural problems would not recur.
He assured the meeting that this was not a luxury – the existing FTCs were unsafe, and so MOZAL would spend 10 million US dollars to put them right. “It’s a very simple issue”, he said. “The FTCs need to be rebuilt. If we didn’t need to do it, we wouldn’t do it”.