The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 11, 1978
Filed:
Aug. 26, 1977
Leonard Elmo Olds, Castle Rock, CO (US);
Johns-Manville Corporation, Denver, CO (US);
Abstract
A process is described for the reduction or prevention of deterioration of refractory metal components of an electric furnace by chromia-containing oxide melts. The process is based on the discovery of an unexpected series of oxidation/reduction reactions leading to formation of chromium trioxide and subsequent oxidation of the refractory metal (e.g., molybdenum or tungsten) by the chromium trioxide. The process comprises adding to the mixture of oxides in the furnace a component which is oxidized to an oxide with a lower free energy of formation per mole of oxygen than the refractory metal oxides (such as MoO.sub.2, MoO.sub.3, WO.sub.2 or WO.sub.3) and chromia, and which thus reduces CrO.sub.3 to a compound which is inert to the refractory metal. In a preferred embodiment the additive is a carbonaceous material and may be in the form of powdered coal. The stoichiometric amount of additive will be about 20 to 50 percent by weight of the percent by weight of chromia present.