Abstract: A known "spark cup process" may be operated without the spark cup if the violent fluctuations in the melt surface with which the electric arc is struck are accommodated so as to allow the electric arc to be maintained substantially continuously. Controlling the dynamic profile of the melt surface without a spark cup allows continuous operation of the electric arc which generates enough plasma to permit addition of as much as 1000 lb/hr of a spray of superheated feed material to a flowing stream of melt which assimilates the feed material.

Abstract: Apparatus for commutating an electrical current to an electrically conductive rod of an alloying element during the feed thereof to a body of molten metal for purposes of changing the alloy composition of the metal. The apparatus includes a power supply capable of providing electrical current in amounts sufficient to melt a free end of the rod of alloying material into the molten metal, and a pair of parallel adjacent shafts of substantial cross-section. A pair of commutation wheels are mounted respectfully on said shafts for rotatably engaging the rod between the wheels and for conducting current to the rod. Means are provided for forcing the wheels against the rod to provide intimate electrical and physical contact between the rod and wheels. A plurality of stationary brushes are disposed to physically engage each of said shafts along the length thereof for supplying current to the shafts from the power supply, and from the shafts to the wheels engaging the rod.