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. 15, 2000
Filed:
May. 02, 1997
Olle Wennberg, Gothenburg, SE;
Kvaerner Pulping Ab, Karlstad, SE;
Abstract
Provided is a process for removing metals from a bleaching plant spent liquor and recovering a chelating agent which includes the steps of: heating a spent liquor containing a chelate comprising metals bound in a chelating agent to a temperature of at least about 140.degree. C. to break bonds in the chelate and release metals from the chelate; increasing the content of at least one of carbonate or sulphide in an alkaline material comprising at least one of green liquor or white liquor to form a carbonate or sulphide enhanced alkaline material; contacting the heated spent liquor with the alkaline material to form a solution containing precipitated metals, wherein the alkaline material is added in an amount sufficient to precipitate a majority of the released metals out of the solution; filtering the solution to separate the precipitated metals from the solution and form a filtrate containing recovered chelating agent; and supplying at least a portion of the recovered chelating agent to a chelating washing stage in a bleaching plant to bond with metals released from pulp and form a chelate. Also provided is a method of reducing encrustations.