Coinjection technology to improve furnace processes

If materials handling and pneumatic conveying systems supplier Clyde Bergemann Africa (CBZ) can successfully implement its coinjection process, as well as achieve its proposed 30% capacity increase outcomes, it will be the only company, to date, to have achieved this.

“This technology will poten- tially open up a number of doors in the beneficiation industry in terms of production capacity,” says CBZ business development executive director Jeremy Kirsch.

CBZ hopes to enter other thermal process sectors, in addition to the traditional metal processing industries, by combining its Rotofeed technology, a dense phase pneumatic conveying system, with its multiple solid product coinjection technology to produce a more accurate, consistent and reliable feed mechanism.

Kirsch tells Mining Weekly that the main advantages of using the coinjection system is its energy efficiency and ability to reduce an industry’s environmental impact.

The coinjection system transforms a mixture of accurately measured components in a single conveying pipe- line from multiple material- injection units into one stream of solid flow that is fed into the furnace.

Coinjection technology is able to produce a consistent stream of solid flow with no pulsing. The system is pressure neutral as it can operate under a pressurised environment and does not depend on pressure within the furnace to increase or decrease the feed rate.

The system also has a seal in the rotor mechanism to prevent dust from entering the bearings and shaft support system, resulting in less maintenance, downtime and feed interruption.

CBZ reports that clients using this technology experience up to two years between serious maintenance intervals, improving productivity.

Increased Production Capacity
“In terms of the copper processing industry, most copper furnaces were mothballed during the economic downturn and will not be recommissioned owing to their high-energy consumption and environmental footprints. The remaining flash furnaces account for 70% of the total copper furnaces globally,” notes Kirsch.

By installing an improved feed system, using coinjection technology, flash- furnace processing plants have the potential to increase their furnace production capacity by up to 30%, as well as decrease their carbon emissions, says Kirsch.

CBZ is currently in negotiations with an international copper producer regarding a contract to increase its flash furnace’s capacity by a proposed 30%.

Kirsch says that, if the company, with its new project, can optimise the furnace’s production capacity by implementing a more accurate, consistent and reliable feed mechanism, with 99.9% uptime throughout production, other industries are likely to follow this trend, which will influence 70% of the world’s smelter furnace processes.

The first Rotofeed system incorporating coinjection was commissioned at a copper smelter in Zambia, in 2008, to inject copper concentrate and coal into the copper furnace.

Environmental Considerations

The traditional beneficiation of simple ore differs in industries, such as titanium dioxide, where ore containing multiple metals are processed at the same time in the same furnace.

As a result of the different chemical compositions of the ores, they cannot be tailored in the same furnace.

One metal is removed from the furnace and put into a ladle for processing. This entails being injected with additional materials to produce a high-quality material enabling revenue from both the metals.

Meanwhile, performing ladle injections on ores results in the creation of fumes and dust as the molten components are mixed, therefore creating pollution that must be captured and controlled.

By implementing a more efficient co- injection technology, the injection process time can be reduced.

“There is a global trend towards the installation of top submerged lance furnaces, which have better sealing at both the top and bottom ends.

“This is a more environment-friendly furnace operation as less gas and dust is released into the atmosphere,” explains Kirsch.

Apart from benefiting the industry in general, CBZ’s coinjection system is aimed at feeding these types of furnaces as the trend of being environmentally conscious grows in South Africa.

In addition, CBZ provides accretion control in the offgas duct system of the furnace. Pulverised coal is injected directly above the slag to prevent accre- tion build-up near the furnace roof and duct area, ensuring that the system operates for longer periods and the energy use of the total operation is reduced as the furnace does not need to produce extra heat to reduce the accretion build-up.

Outlook
Going forward, the company aims to provide an energy efficient and environment-friendly product, while focusing on carbon-reducing technologies.

“CBZ needs to actively examine what it is that we are doing in terms of energy efficiency and improving the environ- ment. “We need to educate our workers and shareholders, and promote this message among our clients.

“We feel that the company is in a posi- tion to actively engage in this initiative as well as carbon-reducing technologies, owing to the technology we have at our disposal,” concludes Kirsch.