The Plasmare Furnace

CIM Bulletin, 1964

G. Magnolo Then Development Engineer, Union Carbide Canada Limited, Linde Gases Division, Toronto

Plasmarc melting produces metals of the highest quality; the physical qualities are equal to those of vacuummelted metals. Plasmarc furnaces utilize conventional furnace hearth shapes and refractory materials. Furnace capacity is limited to 10 tons due to the economies of direct- current power supply requirements. The Plasmarc torch, utilizing a water-cooled tungsten electrode, produces temperatures of 30,000°K and has a service life of more than 100 hours. The electrode is electrically negative; the melt itself acts as the anode. Argon, used to stabilize the arc, also provides the required inert furnace atmosphere. The charge is melted by radiation and conduction, and not by direct arc contact. Melting proceeds more rapidly from the bottom up. This accelerates melt-in and protects the refractory from arc exposure during early heat periods. Standard argon, having an average moisture content of not more than two grains per 1,000 cu. ft., provides the atmosphere over the bath. The composition of this atmosphere is dependent on the condition of t he furnace. Carbon monoxide values decrease with time, and the Jow partial pressure of carbon monoxide above the bath produces sufficient driving force to effectively utilize carbon as a deoxidizing agent.
Keywords: argon, carbon monoxide, partial pressure, tungsten, welding torch, Atmosphere, Carbon monoxide, Electrodes, Furnaces, Heat, metals, Oxygen, Tungsten, Welding