International Paper Company

Jasper H Field

Robert W Hicks

Caifang F Yin

Leroy C Hofmann

Michael E Ring

Roy S Swenson

Stephen H Monroe

Donald M MacDonald

Christopher P Hung

Hugh P Gallagher

Vladimir B Lesokhin

Donald M Macdonald

The specification discloses an improved bleaching sequence which provides significant reduction in filtrate volumes and amounts of absorbable organic halide (AOX), color, and chemical oxygen demand (COD) in the effluent. These reductions are achieved without adversely affecting the brightness and viscosity properties of the bleached pulp and without a high capital cost and operating cost penalty or impact on existing mill processes. The bleaching sequence according to the invention for reducing filtrate volumes is an E D E D or E D E D bleaching sequence wherein substantially all of the filtrates from the later bleaching stages are recycled to earlier bleaching stages and eventually treated in the initial E or E stage prior to discharge from the plant. An advantage of the invention is that pulp having a Kappa number of greater than about 25 for softwood and greater than about 15 for hardwood may be fed to the bleaching process while still providing a bleached pulp having sufficient brightness, viscosity characteristics and good pulp yield.

Elemental-chlorine-free bleaching process having an initial Eo or Eop stage

The invention described in the specification relates to a process and apparatus for the reduction of adsorbable organic halide (AOX), chemical oxygen demand (COD) and color bodies from the filtrates generated in a chlorine compound-containing pulp bleaching sequence. The method involves vigorously and intensely mixing certain pulp bleaching filtrates in order to lower the AOX content of the filtrate and the use of a peroxy compound and a ferrous salt catalyst to treat a combined filtrate streams thereby significantly reducing the level of AOX, COD and color in the effluent leaving the pulp bleaching plant.

Oxidative treatment of bleach plant effluent

A method and apparatus for producing a paper product having a surface with enhanced gloss. The method includes the following steps: applying a continuous layer of an impressionable coating material to a paper product; contacting the layer of coating material with a polymer release film having a smooth and glossy surface substantially free of defects, the surface having non-adhering and release characteristics; and solidifying the coating material during contact with the release film. Using this technique, a smooth and glossy surface of the release film is substantially imparted to a surface of the layer of solidified coating material. In the case of clay-coated substrates, the coating is solidified by heating, whereas in the case of polyethylene-coated substrates, the coating is solidified by cooling. The end product is a coated substrate in which the coating has a glossy surface to which the texture of a film has been imparted.

Apparatus for making paper and paperboard having enhanced gloss

The specification discloses a method for the treatment of black liquor from a kraft or soda pulping process which comprises forcibly conveying the black liquor through an elongate conduit containing at least one vent at a position along its length while subjecting the black liquor to a working action and maintaining the temperature of the black liquor at least about 80.degree. C. so that the black liquor is compressed and mixed as it is conveyed through the conduit to promote the separation of liquid components from the black liquor into the vent by expression and vaporization. As a result, the solids concentration of the material may be increased to provide an improved quality fuel for soda recovery boilers. The process is advantageously carried out using a vented screw extruder which is equipped to supply heat to the black liquor from the screw interiors and barrel housing to promote vaporization of volatiles and to maintain the flowability of the material as it is conveyed through the extruder.

Treatment of black liquor with a screw extruder evaporator

A method and apparatus for producing a paper product having a surface with enhanced gloss. The method includes the following steps: Applying a continuous layer of an impressionable coating material to a paper product; contacting the layer of coating material with a polymer release film having a smooth and glossy surface substantially free of defects, the surface having non-adhering and release characteristics; and solidifying the coating material during contact with the release film. Using this technique, a smooth and glossy surface of the release film is substantially imparted to a surface of the layer of solidified coating material. In the case of clay-coated substrates, the coating is solidified by heating, whereas in the case of polyethylene-coated substrates, the coating is solidified by cooling. The end product is a coated substrate in which the coating has a glossy surface to which the texture of a film has been imparted.

Method for producing paper products having increased gloss in which

Both the wet strength and the folding endurance of kraft linerboard are improved by subjecting the board to steps of densification and high temperature treatment during its production.

Kraft linerboard by densification and heat treatment

Treatment of high yield wood pulp which has ether extractives of greater than about 3.0% at temperatures of about 105.degree. C. or higher for at least about 16 hours followed by fluffing of the heat treated pulp results in a relatively inexpensive absorbent for oil spills and the like. The oil is readily recovered from the absorbent or the oil and absorbent may be burned as fuel without separation.

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Goshen, NY, United States of America

Jasper H Field