Breaking the Scale

April 5, 2012
Induction melting has long offered many advantages, but lately it is the technologys scalability that is getting recognition thanks to some high-capacity projects.
ABP Induction’s IFM coreless furnace design is the basis of two new projects, where it will be relied upon to produce up to 30 metric tons/ hour.

Proponents of induction melting have long held it is ideal for foundry operations because it satisfies so many objectives: it is a lowemission and energy-efficient process that maximizes the value of raw materials and alloys, and it is a scalable process that can be installed to suit a wide range of production strategies. Lately, however, the emphasis is on large-scale furnace designs.

“We now see coreless furnace orders of 35 to 85 metric ton capacity as the norm,” Inductotherm Europe Ltd. managing director Steve Hill said recently, explaining his group’s decision to build a new plant to manufacture larger vessels.

The European furnace division of the Inductotherm Group and its affiliate Consarc built a new manufacturing plant at Droitwich, in Worcestershire, England, to accommodate production of larger-capacity coreless induction furnaces, including steel-shell furnace vessels and vacuum furnace systems. The new operation has a plant floor covering more than 800 m2 and a ceiling height of 14.5 m. It houses two cranes, each one capable of lifting 40 metric tons (total lifting capability of 80 metric tons.)

“With this increase in size, the existing facility in Droitwich had started to struggle with the physical size and weight of these heavy-duty steel shells,” Hill continued. “The decision to expand production facilities is important for us as it maintains our reputation for reliability by helping us to meet current and future demand at all levels.”

Also maximizing the scale of its induction melting product line is ABP Induction, the furnace builder that last year announced a contract to build “the largest induction melting plant in the world.” The project at Taiyuan Iron and Steel Group Ltd. (Tisco), at Taiyuan in China’s Shanxi Province, is due for completion this year.

Tisco’s order called for a melt shop capable of producing 180 metric tons per hour of ferrochrome, pouring at a temperature of 1,670°C, to produce stainless steel. As ABP Induction explained, the determining factor in the design of this high-volume melt shop was the economic advantage of induction melting over arc melting (which is more common in steelmaking operations), based on significantly lower material losses as a result of the combustion process — specifically, the chromium used to produce stainless alloys

“Fifty metric tons from an induction furnace with a tap-to-tap time of 60 minutes is a tremendous achievement, and requires a lot of power,” noted Dr. Wolfgang Andree, ABP Induction’s managing director.

The furnaces to be installed include two IFM 9 vessels, from ABP’s line of medium-frequency coreless furnaces for melting and holding ferrous or nonferrous metals. Two such units will be installed with capacities of 30 metric tons, powered by 24,000-kW and a 3,000-kW induction power source. In addition, six IFM furnaces will be supplied with capacities of 65 metric tons and powered by three, 42,000-kW power supplies and three more 1,800-kW sources.

Tisco noted that the sizes of the furnaces underscored its need for reliability, energy efficiency, and automation. ABP Induction said its melt shop design was enhanced by inclusion of the Ecotop system — a welded steel, refractory-lined furnace hood that attaches to the vessel with a floating system to seal the melt from the atmosphere. A telescoping duct optimizes exhaust gas removal. “ABP Induction has a convincing overall concept for a sustainable technical solution,” according to Liu Fuxing, Tisco’s general manager.

A similarly large-scale induction melting installation will take place in India.

Nalwa Steel & Power contacted ABP Induction to build a melt shop capable of producing 700 metric tons/day of direct reduced iron. It will be one of the largest DRI operations in India. The plant melts of 85% DRI to a tapping temperature of 1,640°C, and the liquid metal is transferred to 32- and 38-metric ton ladle furnaces for refining, to produce steel.

ABP is supplying two 30-metric ton capacity IFM furnaces with a 16,000- kW power source based on ABP’s Twin- Power concept: a single power source that distributes the energy supply “steplessly” to two induction furnaces, with no switch time losses or overheating in the melt.

The two furnaces will have the Ecotop fume-extraction system, as well as an automated slag-skimming capability. Also, ABP will provide two ladlerefining furnaces, 32 metric tons and 38 metric tons, with an electrical rating of 7.2 MVA.

“The major deciding factor for the decision in ABP’s favor was its advanced automation, high-energy melt process, ABP’s Ecotop system, and the automated slag remover that reduces the number of operating personal,” Nalwa executive director P.S. Rana noted. Like Tisco’s installation, the size of the equipment designed for the Nalwa project increased the need for furnace reliability, maximized energy efficiency, and process automation. “Thirty metric tons from an induction furnace with a tap-to-tap time of 120 minutes for 85% sponge … requires a lot of automation,” Dr. Andree added.

This project will be completed later this year, according to the developer — demonstrating that the scalability of induction melting may be greater than previously understood.