December 16 1997
DANBURY, Conn., December 16, 1997 — Praxair, Inc. (NYSE: PX) announced today it received U.S. Patent No. 5,674,309 covering its argon purging system for controlled-atmosphere steel casting. This new technology can save a typical steel mill an estimated $500,000 per year.
Praxair's technology uses argon gas injectors to create a controlled atmosphere that protects molten steel from exposure to air in a partially open tundish. Molten steel exposed to air during casting is rejected more frequently for defects and poor quality. In addition, the technology enables operators to conduct necessary tasks under an inert atmosphere even when access openings to the tundish are uncovered.
The invention is based on the principle of turbulence control and relies on the number, size and location of simple and reliable argon gas injectors to create an inert, protective atmosphere. The turbulence control concepts were tested on a commercial, three-strand caster that processes a variety of carbon and alloy steel grades for use in the automobile and other industries.
Praxair has received more than 275 patents for steel-making technologies using industrial gases in innovative, money-saving ways. For example, Praxair's patented post-combustion technology for electric arc furnace steel makers uses oxygen to increase productivity, decrease power consumption and lower carbon monoxide emissions up to 40 percent. Praxair's patented slag splashing technology for integrated steel mills injects nitrogen gas to help coat the steel-making vessel with slag, extending the refractory life of a basic oxygen furnace 400 percent.
Praxair is the world's leading supplier of industrial gases and application technology used by manufacturers of steel, aluminum, copper and other primary metals, with 1996 sales to this segment of more than $750 million. More than half of all steel manufacturers in North and South America, and many new steel mills in Asia, are Praxair customers.
Praxair is the largest industrial gases company in North and South America, and one of the largest worldwide, with 1996 sales of $4.4 billion. The company produces, sells and distributes atmospheric, process and specialty gases. A subsidiary, Praxair Surface Technologies, supplies metallic and ceramic coatings and powders for high-performance applications. Praxair is a recognized leader in the commercialization of new technologies that bring productivity and environmental benefits to a diverse group of industries.