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Pulp and Paper Research Institute of Canada

Denys Francois Leclerc

Thanh P Trung

Gilles Marcel Dorris

Thomas Hu

Michael H Kester

Victor Charles Uloth

Stephen P A Betts

Ronald Peter Van Heek

Edward A Dylke

A method for the determination of a cellulosic-fibre property, namely, residual lignin content or Kappa number of chemical pulp, with the aid of a spectroscopic technique obtained over a range covering the visible and the near-infrared regions of the electromagnetic spectrum, comprising exposing the wet fibres to a light source covering a range in the visible region of 350 nm to 750 nm and a range in the near-infrared of 1100 nm to 2400 nm, reflecting light from the wet fibres, establishing a spectrum, comparing the spectrum with a known spectrum of the property and evaluating the comparison; the method has particular utility in a pulp manufacture line; an apparatus is described for carrying out the method.

Method for determining chemical pulp kappa number with visible-near infrared spectrometry

Oxidized white liquor is heat treated to increase the concentration of polysulphide measured at 285 or 286 nm (PS) or measured at 416 nm (PS) and the PS/PSor PS/PSratio, whereby the content of active polysulphide in the total polysulphide is increased which active polysulphide can be exploited to increase pulp yield in Kraft pulping.

Kraft pulp yield by heat treatment of polysulphide liquors generated by oxidation

A rapid method is provided for the on-line spectroscopic determination of lignin content and/or kappa number in wood pulps. Unlike currently available commercial instrumentation, the method enables one to measure lignin content independently of species variations and pulp consistency. The method includes the steps of: (1) withdrawing high-consistency samples of wood pulp from a chemical pulp manufacturing process; (2) subjecting these samples to a monochromatic visible-light source; (3) recording the resulting scattered light and its Raman spectrum over a predetermined range of wave numbers so as to produce Raman-scattered light intensity measurements; (4) determining either the uncorrected, baseline-corrected and/or integrated Raman-scattered light intensity of the samples over a predetermined range of wavenumbers shown by different combinations of lignin content, cellulose content, and consistency; (5) correlating by either univariate or multivariate calibration the relationships between the Raman-scattered light intensity measurements of unknown samples and the Raman-scattered light intensity shown by known combinations of lignin content, cellulose content, and consistency so that the lignin content and/or kappa number in wood pulps can be accurately determined over a Kappa range of 5 to 110 and preferably 5 to 20, for any levels of sample cellulose content or pulp consistency.

Method for determining liquid content in chemical pulps using ramen spectrometry

A method for determining the concentration of hydrogen ion, organic anionic species and anionic species selected from the group consisting of OH , CO , HS , ClO , SO , S O , polysulphide and peroxide in an aqueous sample solution, said method comprising subjecting said solution to near infrared radiation at a wavelength region of wave numbers selected from about 7,000 to 14,000 cm through a solution path length of at least 3 mm to obtain spectral data for said solution; obtaining comparative spectral data for said anionic species at known concentrations in aqueous solutions; and correlating by multivariate calibration the relationships between said spectral data of said sample solution and said comparative spectral data to determine said concentration of said anionic species in said sample solution. The method is of particular value for use with pulp liquor determination and control in regards to the rapid and accurate determination of the OH , HS , CO , ClO , SO , S O , polysulphide and peroxide anionic species, hydrogen cation and of organic species present in pulp liquor.

Determination of ionic species concentration by near infrared spectroscopy

Growing community of inventors

Vancouver, Canada

Denys Francois Leclerc