Global mining solutions provider Tenova TAKRAF Africa is introducing the Superbelt conveyor technology, devel-oped by Italian environment-friendly hot bulk materials handling solutions provider Magaldi Italy, to Southern Africa. The conveyor has been designed specifically for hot bulk materials handling applications and can withstand extremely high temperatures without distorting.
The conveyor’s superior temperature resis-tance is owing to a new method of connecting the pans to the belt, enabling all the conveyor’s components to expand in any direction without causing permanent deformation of the conveyer. “There have been reports of the conveyer handling materials of up to 1 100 ˚C,” says Tenova TAKRAF specialised equipment manager Antonie le Roux.
The Superbelt comprises a steel mesh belt, which carries partially overlapping steel pans that form a virtually sealed belt conveyor. The conveyer is supported by carrying idlers across its entire width, enabling it to withstand heavy mechanical loads. The driving force of the con- veyor is transmitted by friction between the head pulley and the belt, while a pneumatic take-up device on the tail pulley supplies constant tension.
The damage-tolerant design of the conveyor eliminates any risk of sudden failures, which is inherent with conveyors that use chains. Wear on the conveyor is also negligible, as material is slowly conveyed with no relative motion against its steel parts.
Le Roux notes that, because of its performance under high temperatures, the Superbelt conveyor can be used in various applications, including the power industry, where it can convey hot ash from underneath boilers, and the casting industry, where it can convey parts for high-temperature castings. Tenova TAKRAF engineered technologies GM Richard Späth adds that the technology can also be used to convey forged or cast metals that are still at elevated temperatures from furnaces and kilns, and in the cement industry to handle hot clinker.
Magaldi has also developed the Ecobelt DRI, whose design includes the Superbelt conveyor, for specific application in conveying direct reduced iron (DRI) produced from rotating hearth furnaces before further processing stages.
Iron-ore, usually in the form of pellets, is conveyed under hot reducing gases to remove the oxygen from the ore. The pellets are extremely porous and, thus, prone to re-oxidation on contact with air. This process, there- fore, demands an inert atmosphere inside the conveyor, which the Ecobelt DRI offers by enclos-ing the Superbelt conveyor in a steel casing to prevent the re-oxidation of the ore.
The inner walls of the steel casing are coated with a suitable insulation to prevent heat loss during the transportation of materials, with the thickness and characteristics of the insulation being determined by the DRI pellet temperature required at the unloading point. Nitrogen or other suitable gases can be injected into the Ecobelt under a small positive pressure to make the inner atmosphere inert and avoid any oxygen leaks.
The Ecobelt can also cool down DRI pellets, such as in the case of conveying DRI pellets to a briquetting machine, which typically runs at between 500 ˚C and 700 ˚C.
Le Roux explains that the Superbelt conveyor can be configured in an enclosed system for several applications, which ensures that any harmful emissions produced during the processing of the materials being conveyed are retained inside the system. A dust or gas extraction or suppressant system can then be easily attached to it.
“Tenova TAKRAF has a complete range of air cleaning equipment, with expertise in handling hot gases produced by furnaces and kilns as well, ranging from scrubbers to precipitators,” says Späth.
Le Roux notes that the conveyor’s ability to withstand such high temperatures also means that less rigorous cooling processes are needed when conveying materials that have been heated, which can result in significant water reductions. This is especially significant in a water-scarce country like South Africa, he points out.
The Superbelt conveyor also produces energy savings when smelting DRI pellets, as the pellets can be conveyed to electric arc furnaces at higher temperatures.
Further, the conveyer can be maintained while in operation, says Späth, adding that most main-tenance requirements can thus be carried out under continuous operation without having to shut down the machine, thereby reducing downtime.
“Internationally, Magaldi has several reference plants, so the claims they are making with regard to the Superbelt conveyor’s increased efficiency and ability to reduce or eliminate water use in heating processes are not just a theory – they are supported by global, practical examples,” he states.
Tenova TAKRAF was named the South African agent for Magaldi in 2014 and is investing in the promotion of the Superbelt conveyor as an efficient and environment-friendly alternative to older technologies used in the power industry and other industrial processes.