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:
Feb. 17, 1981
Filed:
Dec. 06, 1977
Applicant:
Inventors:
Stig A Petersson, Skelleftehamn, SE;
Allan F Norro, Skelleftehamn, SE;
Assignee:
Boliden Aktiebolag, Stockholm, SE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H05B / ; F22B / ; C01B / ;
U.S. Cl.
CPC ...
219284 ; 159D / ; 159D / ; 204 / ; 2042 / ; 204292 ; 219275 ; 219288 ; 423531 ;
Abstract
A method is provided for directly heating a concentrated sulphuric-acid solution by passing alternating electric current between surface-passivated electrodes immersed in the solution and by using electrodes of iron or an iron alloy having a low resistance iron or iron alloy inner core covered by an outer high resistance passivating surface layer which are so surface-passivated that the transition resistance between the electrodes and the concentrated sulphuric-acid solution is at least as great as the resistance exerted by the concentrated sulphuric-acid solution.