The construction of a new R4.5-million baghouse for secondary aluminium producer Zimalco has been completed.

Air pollution control company About Air Pollution built the baghouse, which will enable the producer to maintain a continuous improvement of its air quality to fully comply with the new Air Quality Act, which came into effect in 2010.

The baghouse project was started in November 2011 and completed in July. The baghouse filters and cleans the emissions from the melting process, ensuring the final emissions comply within the limits set in the new Act.

Meanwhile, Zimalco engineering manager Neels van Niekerk tells Engineering News that the producer has also installed a new reverberatory melting furnace, which was commissioned in April.

This furnace has enabled Zimalco to save substantially on electricity and gas costs incurred during melting, and combat the escalating energy costs experienced over the last few years that are also expected in the coming years.

Engineering company Tager Engineering undertook the structural work for the furnace installation, while industrial process control specialist PSY Systems installed and commissioned the controls and burners.

“We did the bricklaying and used the opportunity to give inexperienced furnace bricklayers on-the-job experience. “The industry is under pressure in terms of furnace construction, as there are not many skilled furnace bricklayers in South Africa.

“We used our own in-house bricklayers, which helped us to save costs while providing invaluable training and cost saving in the process. “We also saved R500 000 on manufacturing and labour costs by doing the majority of the work ourselves,” Van Niekerk says.

The company will not divulge exactly how much it spent on the furnace but realised significant savings when comparing it with a turnkey furnace, which would have cost up to R7.5-million. Being able to plan and manage the project in-house resulted in these substantial cost savings, he notes.

Energy Saving
Meanwhile, Zimalco sales and marketing director Bob Stone says the use of aluminium powder for various applications has started to increase.

“Aluminium powder in South Africa is mainly used in the explosives industry. It is used in packaged explosives, instead of bulk explosives, mainly for underground mining and rock-blasting purposes. It is also used in the manufacture of flocculants, in chemical processes to purify South Africa’s drinking water, in drain cleaners and in exothermic welding of railway lines,” Stone notes.

“Aluminium thermic welding is used to join rail lines together to create one continuous rail. Aluminium powder is mixed with iron oxide and other elements, with the aluminium acting as the energy source when ignited, to melt the iron oxide and the rail, forming a seamless joint,” he explains.

Stone adds that the exothermic property of aluminium is also used in the production of ferro-alloys as an alternative to using large amounts of electricity.

He adds that in addition to the use of aluminium powder in the production of ferroalloys, such as ferrotitanium and ferrovanadium, it is also used to generate heat when ignited. This replaces the heat that would be required from other sources, such as electric arc furnaces, to melt the iron- and titanium-ore material to form the ferroalloy.

“This is one of the reasons why aluminium scrap is in high demand worldwide and it is something our government does not realise, as it continues to allow the free export of aluminium scrap out of South Africa.

“We are therefore exporting not only a strategic raw material and, by implication, many jobs, but also a massive store of potential energy,” Stone states.

Zimalco MD Willie Willemse says, although the use of aluminium powder to substitute other forms of energy in such applications is not new to the market, it is most viable now, because electricity costs are so high and increasing yearly.

“Owing to aluminium’s property of burning thermites at 2 700 °C, it is an ideal substitute for other forms of energy in the production of ferroalloys and reduction of oxides.

Willemse adds that, owing to the high cost of electricity, people are currently experimenting with this concept and other uses of aluminium, more than before.

“Where electrical energy was not available, there was a trend in South Africa to export primary ore and metals without beneficiation. “As a replacement for that energy, companies are using aluminium powder in various fraction sizes to beneficiate the ore by reduction into metal for local use and, also, before it is exported,” he says.

Social Responsibility

As part of Zimalco’s social responsibility initiatives, the company takes students from various universities and learning centres who would otherwise not have had the opportunity of being introduced to the industry, and gives them exposure to practical training to compile their portfolios of P1 and P2 towards their final qualification.

“We have taken in engaged apprentices, as well as mechanical, electrical and chemical engineering students for in-service training. The feedback has been positive and the trainees have achieved a great pass rate on their P1 and P2 certification,” says Willemse.

He adds that, as part of the company’s social and rural development responsibilities, Zimalco works closely with Kgothalang Primary School, in Wattville, Benoni, where it has implemented many projects to improve the school’s facilities.

“We recently roofed a section of the school that is used for assemblies and as a recreation area. “The new roof protects the learners from the harsh sun and rain during lunchtime and gatherings,” says Willemse.

The company plans to further upgrade the school’s facilities, including the ablution blocks, in the near future.

Zimalco has ISO 9001, ISO 14001 and OHSAS 18001 certification as audited by the South African Bureau of Standards. It was recently certified as a Level 8 broad-based black economic- empowerment-compliant company.

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