Nupro Corporation – Process Tech, Slag Detection, and Ladle Stirring

Plasma melting and refining

PLASMA D.C. Electric Arc Furnace Technology

Aluminum Recycling

A 500 kW D.C. plasma arc furnace was built (shown at right) to demonstrate the commercial viability of melting aluminum with high yield, low energy
consumption and low waste generation. The furnace was designed to melt aluminum at a maximum rate of 2,000 lb./hr. using 500 kWh of electricity per ton (850 BTU/lb.). A major goal was to decrease oxidation loss in the melting of aluminum chips by 50% or more. An additional goal was to carry out the melting operation without the use of a salt flux.
Furthermore, gaseous emissions were to be reduced by 90%, and solids emissions by more than 50%. Solid waste (dross) was to be further treated to produce a usable by-product, thus eliminating this waste stream altogether. Reported in The
Pittsburgh Business Times

Aluminum Recycler

D.C. Plasma Arc Recycler.

Steel Refining

This furnace was developed as a cost effective alternative to AOD processing for the foundry industry. A 500 kW D.C. plasma arc ladle furnace with 5 ton steel capacity was constructed and then commissioned in June, 1993. Several immediate benefits with this technology were realized:

-reduction of total oxygen to under 30 ppm.
-100% alloy yield
-reduction of sulfur to 10 ppm.
-heating efficiency of 37 to 67%
-90 to 100 minute cycle time
-100 kWh/ton decrease in melting energy consumption.

The results indicate that the D.C. plasma arc ladle furnace is a valuable tool for the foundry industry. Steel quality can be improved, while increasing productivity and reducing cost.

Steel Refiner

D.C. Plasma Arc Steel Refiner at Steel Foundry.


This furnace was initially designed and constructed as an experimental furnace for steel processing with a 200 lb. capacity. The furnace is comprised of a refractory lined foundry ladle with porous plug gas stirring and two electrodes to generate the D.C. plasma arc. Steel processing tests were conducted under a government contract to produce ultra low O and S, low inclusion CN7M test blocks. Subsequently, the furnace was converted to be used for aluminum dross processing trials.

For dross processing, a carbon lining was added and pilot tests were conducted. After these tests, the furnace was converted back to steel processing configuration and then shipped to a foundry for plasma processing tests. The furnace versatility and portability has enabled it to be transported to various locations around north America.

Our experience with plasma processing theory and practice is invaluable to clients wishing to investigate the potential of this powerful tool. Contact us to discuss the implementation of plasma processing in your unique application.

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Experimental plasma furnace at university.

Exp Furnace Schematic

Schematic diagram showing cross-section of experimental furnace.

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D.C. Plasma Arc.

Nupro Corporation – Process Tech, Slag Detection, and Ladle Stirring