Abstract: A method for brightening chemical pulps with less than 18% lignin utilizing a magnesium compound in a sodium silicate solution to form a higher percentage of high molecular weight silicates. Such high molecular weight silicates preferentially adsorb transition metal impurities, which, if left in solution, would tend to decompose hydrogen peroxide and organic peroxides. Hydrogen peroxide is added to peroxide and peroxide/oxygen stages, while it is generated, along with organic peroxides during an oxygen stage.
Type:
Grant
Filed:
January 11, 2001
Date of Patent:
March 2, 2004
Assignees:
National Silicates Partnership, Research Foundation of State University of New York
Abstract: Improved silicate drilling fluids are produced by the addition of tetra alkyl ammonium compounds, in particular tetra methyl ammonium hydroxide to silicate drilling fluid mud to lower the co-efficient of friction between drill string and wellbore. It has also been discovered that the same tetra alkyl ammonium lubricant compounds greatly lessen the viscosity breakdown of swelled hectorite clay in the presence of silicate. This allows the preparation of silicate drilling fluids not only with enhanced lubricity but having stable rheology at the higher temperature and pressures encountered in some drilling operations.
Type:
Grant
Filed:
June 4, 2001
Date of Patent:
November 4, 2003
Assignee:
National Silicates Partnership
Inventors:
Jonathan L. Bass, Michael J. McDonald, John C. Urquhart