Heat technology supplier Ai-Tec’s manufacturing arm, Macrotec, is manufacturing a spent activated carbon gold recovery incinerator for use at a mine in Ghana, which will be supplied at the end of this month.

“The locally developed C100 is primarily for gold recovery from spent activated carbon and blasting wood chips,” says Ai-Tec group director Arnold Retief.

“This incinerator recovers the gold that was initially wasted in the previous extraction process,” he says.

“The smokeless incinerator, which uses Ai-Tec’s Macroburn technology, is environment friendly and will be important in the recycling of mine dumps in Ghana and for recovery of minerals otherwise lost,” says Retief.

“Macroburn incinerators are designed for efficient performance, low fuel use and limited environmental impact. These incinerators eliminate potential obnoxious emissions through a sophisticated system that automatically controls the rate of combustion,” says Retief.

“The footprint of the C100 is about 50 m2. It uses circular semifluidised-bed combustion chamber technology and dry ceramic filtration, which is imported from the UK,” explains Retief.

Dry ceramic filtration is important as it enables efficient particle removal and high-heat resistance. A fluidised bed is also critical because carbon needs to be suspended for incineration.

These incinerators are used in conjunction with top-mounted chimneys that have accurate draught control.

If the incinerator is fitted with a scrubber or dry filter, a mechanically induced draught system must be installed. The company manu- factures sensors and control dampers for these applications.

Because the efficient incineration of most wastes requires the addition of heat for the drying and ignition of waste and for smoke elimination, incinerators can be fitted with burners, as is the case with the incinerator for the mine in Ghana.

The Macroburn flame intensifier is a recupe- rative system that improves combustion efficiency and ensures substantial fuel savings, therefore, reducing consumption to about one-quarter of the fuel used by conventional incinerators.

Further, another advantage is a hotter, cleaner flame that produces less smoke than other systems. The smaller flame requires less combustion volume and incinerator capacity is increased by up to 20%.

Macrotec has also developed mechanical feeders that provide improved combustion, reduced fuel consumption and lower emission levels. This system includes screw feeders and hydraulic rams, as well as atomising sprays and blowers that feed and control material flows.

For optimum safety, explosion relief doors automatically swing open in the event of an explosion, while high alumina monolithic refractory linings withstand temperatures that exceed 1 500 ºC and ensure durability during sudden and extreme temperature changes.

High-quality insulation around the incine- rator ensures low surface temperatures and minimal fuel consumption. Further, dry-type smoke and fly ash elimination guarantees dry corrosion-free chimney stacks and hot, dry gases that rise straight off the top of the chimney. There is no wet, dragging plume.

There are also no moving or wearing parts in this system, which lowers maintenance requirements and significantly extends the service life of the system.

“Ai-Tec is currently manufacturing a unit for engineering firm DRA Mineral Projects for use in Tanzania,” says Retief.

The C100 is manufactured locally in Stanger, KwaZulu-Natal, and Macrotec sources bought electrical and electronic components from local suppliers.

Included in Macrotec’s service is the design and supply of turnkey installations to destroy hazardous wastes associated with incinerators.

Ai-Tec works according to a complete quality assurance plan, as well as a programme for stringent health and safety standards in every installation. The company also adheres to risk assessment guidelines.

The manufacturer’s network of specialist group companies supports these systems through a technical advisory, installation, repair and maintenance service.

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