Domtar Inc.

Alkibiadis Karnis

John R Wood

Paul M Shallhorn

A method and apparatus for liberating the latent properties of a mechanical pulp is disclosed. The method is a laboratory technique for sample preparation for further pulp testing. 'Latency' is released by recirculating pulp from a pool thereof through a centrifugal pump at a rate of at least four times per minute for the period required to release all the latent properties of the pulp sample ('Latency'). This depending on the rate of circulation may be completed in as little as one minute.

Rapid method for liberating the latent properties of mechanical pulps

Process for producing a mechanical pulp of improved linting properties by screening the pulp to provide a through and a retained fraction, fractionating the through fraction by means of a hydrocyclone into at least two fractions one fraction having an average specific surface less than a predetermined value between 1.2 and 4 m.sup.2 /g and the second fraction having an average specific surface greater than the first fraction and subjecting the first fraction to mechanical processing thereby to form a processed fraction having an average specific surface of 4 to 10 m.sup.2 /g and recombining said process fraction and said second fraction into a combined pulp. The invention also relates to a method of determining specific surface distribution of fibres of the mechanical pulp by fractionating the pulp in a hydrocyclone system into a plurality of underflow fractions and a plurality of overflow fractions each of said underflow and overflow fractions containing a different portion of fibres of said sample and analyzing each of said underflow fractions or of said overflow fractions or both to determine the specific surface of each of said selected underflow or overflow fractions.

Bonding properties of mechanical pulps

The specific surface distribution of a pulp may be obtained by fractionating the pulp in a hydrocyclone means into an overflow and an underflow fraction and measuring the specific surface of each of the fractions and the amount of each of the fractions and based on a cumulative normal distribution relationship of cumulative weight fraction as a percent of feed to specific surface, determining the specific surface distribution for said pulp. Also disclosed is a method and apparatus for determining the specific surface of a pulp sample by measuring the light scattering characteristics to obtain a turbidity measurement of the pulp sample, measuring the consistency of the sample and determining the specific surface of said pulp based on the relationship of specific surface to the turbidity measurement for the measured consistency of the pulp.

Method and apparatus for on-line monitoring of specific surface of

A method and apparatus are disclosed for obtaining an indication of fibre flexibility by spraying a pulp sample of preselected average fibre length against the bottom of a horizontal screen having a negative pressure thereabove whereby a selected pressure drop is applied across the screen and the pulp sample is divided into a retained and a passed fraction. The flexibility index is obtained by a ratio indicative of the fibre mass in the passed fraction or retained fraction to the fibre mass in the feed.

Fibre flexibility meter

A method and apparatus for providing a cleaned stock issuing directly from a hydrocyclone cleaning system at a consistency of at least 1%, comprising injecting pulp to said hydrocyclone means at a consistency of at least 1%, said hydrocyclone having a tangential inlet for stock, a base outlet for an accepted fraction an apex outlet for a rejected fraction, and at least one dilution water tangential inlet adjacent to said apex outlet for dilution water, adding dilution water to said cyclone means through said dilution water inlet adjacent the apex outlet, rejecting a reject fraction through said apex oulet, and ejecting an accept fraction through said base outlet at a consistency substantially equal to said feed consistency.

High consistency pulp cleaning

A method and apparatus for determining the fractional distribution of fibers by specific surface in a sample of mechanically treated pulp comprising: a hydrocyclone, at least two collecting chambers, a pump to feed pulp to said hydrocyclone, means to selectively connect the pump inlet with each chamber and means to selectively connect one of the outlets of the hydrocyclone to a selected chamber.

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Dollard des Ormeaux, Canada

Alkibiadis Karnis