Process for making refiner mechanical pulp

Claim 2

A process of making an improved refiner mechanical pulp from wood particles, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk, and a higher brightness, without the use of bleaching chemicals, than refiner mechanical pulp made by a conventional refiner mechanical pulping process, which comprises: (a) wetting the surfaces of said particles by dipping them into or spraying onto said surfaces a solution of a sulphite salt of an alkali metal to add an amount of said alkali metal salt within the range of 1% to 10% of the oven dry weight of said particles, said solution having a pH within the range of 7 to 12.5; then (b) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature within the range between 80° C. and 165° C. and holding the particles for a time varying from 0.5 to 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (c) passing the particles, after the period of steam heating, through a disc refiner to produce refiner mechanical pulp.

Claim 3

The process of claim 1 in which the alkali metal sulphite salt is sodium sulphite.

Claim 4

The process of claim 1 in which said particles are wood chips.

Claim 5

The process of claim 1 wherein the temperature to which said alkali metal sulphite salt solution-bearing particles are steam heated is within the range between 80° and 100° C., and said particles are held within that temperature range for a period of about 2 to 80 minutes.

Claim 6

The process of claim 4 wherein said particles are held within said temperature range for a period of 10 to 80 minutes.

Claim 7

The process of claim 4 wherein said particles are held within said temperature range for a period of 15 to 80 minutes.

Claim 8

The process of claim 1 in which the time range is 5 minutes to 0.5 minutes.

Claim 9

The process of claim 1 in which any sulphite salt solution draining from wood particles during the heating period is separated from the heated particles, and fortified with concentrated sulphite solution for use in further treating particles.

Claim 10

The process of claim 1 wherein the amount of alkali metal salt ranges from 1% to less than 8% of the oven dry weight of said particles.

Claim 11

A process for making an improved refiner mechanical pulp from wood chips, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk and a higher brightness, without the use of bleaching chemicals, than refiner mechanical pulp made by a conventional refiner mechanical pulping process, comprising: (a) comminuting said wood chips by splitting them along the wood grain to make smaller particles; (b) wetting the surfaces of said particles by dipping them into or spraying onto said surfaces a solution of a sulphite salt of an alkali metal to add an amount of said alkali metal salt within the range of 1% to 10% of the oven dry weight of said particles, said solution having a pH within the range of 7 to 12.5; then (c) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature within the range between 80° C. and 165° C. and holding the particles for a time varying from 0.5 to 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (d) passing the particles, after the period of steam heating, through a disc refiner to produce refiner mechanical pulp.

Claim 12

A process for making an improved refiner mechanical pulp from wood chips, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk and a higher brightness, without the use of bleaching chemicals, than refiner mechanical pulp made by a conventional refiner mechanical pulping process, comprising: (a) comminuting said wood chips by splitting them along the wood grain to make smaller particles; (b) wetting the surfaces of said particles by dipping them into or spraying onto said surfaces a solution of a sulphite salt of an alkali metal to add an amount of said alkali metal salt within the range of 1% to 10% of the oven dry weight of said particles, said solution having a pH within the range of 7 to 12.5; then (c) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature within the range between 80° C. and 165° C. and holding the particles for a time varying from 0.5 to 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (d) passing the particles, after the period of steam heating, through a disc refiner to produce refiner mechanical pulp.

Claim 13

The process of claim 10 in which the alkali metal sulphite salt is sodium sulphite.

Claim 14

The process of claim 11 wherein the pH of the sulphite salt solution is about 12.

Claim 15

The process of claim 10 in which the wood chips are split predominantly into particles having dimensions in the cross grain direction of not over four millimeters.

Claim 16

The process of claim 10 wherein the temperature is within the range between 80° C. and 100° C. and wherein the particles are held within that temperature range for a period of about 2 to 80 minutes.

Claim 17

The process of claim 14 in which the alkali metal sulphite salt is sodium sulphite.

Claim 18

The process of claim 15 wherein both the steam heating and refining steps are carried out at atmospheric pressure.

Claim 19

The process of claim 14 in which the wood chips are split predominantly into particles having dimensions in the cross grain direction of not over four millimeters.

Claim 20

The process of claim 17 wherein the temperature to which said alkali metal sulphite salt solution-bearing particles are steam heated is within the range of 85° 100° C. and said particles are held within the range for about 30 minutes.

Claim 21

The process of claim 14 wherein the alkali metal sulphite salt is added in an amount in the range of 2 to 10% of the oven dry weight of the chips.

Claim 22

The process of claim 14 in which any sulphite salt solution draining from the particles during the heating period is separated from the heated particles, and fortified with concentrated sulphite solution for use in further treating particles.

Claim 23

The process of claim 14 wherein cooling water is added to the particles after the heating step and before passing the particles through the refiner.

Claim 24

The process of claim 14 wherein the wetting step is carried out by spraying the solution onto the particles.

Claim 25

The process of claim 10 wherein said wood chips are comminuted predominantly by splitting them along the wood grain predominantly into particles having dimensions in the cross grain direction of not over four millimeters, and the alkali metal sulphite salt solution-bearing particles are steam heated under superatmospheric pressure to a temperature within the range between 125° C. and 165° C. and holding said particles within that temperature range for a period of 0.5 to 20 minutes.

Claim 26

The process of claim 23 in which the alkali metal sulphite salt is sodium sulphite.

Claim 27

The process of claim 23 wherein the alkali metal sulphite salt solution-bearing particles are held within said temperature range for about 2 minutes.

Claim 28

The process for making an improved refiner mechanical pulp from wood particles, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk and a higher brightness, without the use of bleaching chemicals, then refiner mechanical pulp made by a conventional refiner mechanical pulping process, comprising: (a) spraying a solution of a sulphite salt of an alkali metal onto the surfaces of said particles to wet them and to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said particles, said solution having a pH of about 7 to about 12.5; then (b) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature range between about 80° C. and about 165° C. and holding the particles for a time varying from 0.5 to 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (c) thereafter passing said particles through a disc refiner to produce refiner mechanical pulp.

Claim 29

The process for making an improved refiner mechanical pulp from wood particles, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk and a higher brightness, without the use of bleaching chemicals, then refiner mechanical pulp made by a conventional refiner mechanical pulping process, comprising: (a) spraying a solution of a sulphite salt of an alkali metal onto the surfaces of said particles to wet them and to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said particles, said solution having a pH of about 7 to about 12.5; then (b) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature range between about 80° C. and about 165° C. and holding the particles for a time varying from 0.5 to 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (c) thereafter passing said particles through a disc refiner to produce refiner mechanical pulp.

Claim 30

A process for making an improved refiner mechanical pulp from wood chips, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk and a higher brightness, without the use of bleaching chemicals, than refiner mechanical pulp made by a conventional refiner mechanical pulping process, comprising: (a) comminuting the wood chips by splitting them along the wood grain thereof to make smaller particles; (b) spraying a solution of a sulphite salt of an alkali metal onto the surfaces of said particles to wet them and to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said particles, said solution having a pH of about 7 to 12.5; then (c) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature ranging between about 80° C. and about 165° C. and holding the particles for a time varying from 0.5 to 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (d) thereafter passing said particles through a disc refiner to produce refiner mechanical pulp.

Claim 31

A process for making an improved refiner mechanical pulp from wood chips, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk and a higher brightness, without the use of bleaching chemicals, than refiner mechanical pulp made by a conventional refiner mechanical pulping process, comprising: (a) comminuting the wood chips by splitting them along the wood grain thereof to make smaller particles; (b) spraying a solution of a sulphite salt of an alkali metal onto the surfaces of said particles to wet them and to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said particles, said solution having a pH of about 7 to 12.5; then (c) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature ranging between about 80° C. and about 165° C. and holding the particles for a time varying from 0.5 to 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (d) thereafter passing said particles through a disc refiner to produce refiner mechanical pulp.

Claim 32

A process for making an improved refiner mechanical pulp from wood chips, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk and a higher brightness, without the use of bleaching chemicals, than refiner mechanical pulp made by a conventional refiner mechanical pulping process, comprising: (a) comminuting the wood chips predominantly by splitting them along the wood grain thereof to make particles having dimensions in the cross grain direction of not over four millimeters; (b) wetting said particles by spraying them with a solution of a sulphite salt of an alkali metal to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said particles, said solution having a pH of about 7 to about 12.5; then (c) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature ranging between about 85° C. and about 100° C. and holding the particles within that temperature range for about 30 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (d) thereafter passing said particles through a disc refiner to produce refiner mechanical pulp.

Claim 33

A process for making an improved refiner mechanical pulp from wood chips, said improved refiner mechanical pulp being capable of being used in competitive quality newsprint without the addition of chemical pulp, having a lower debris and shive content, a lower bulk and a higher brightness, without the use of bleaching chemicals, than refiner mechanical pulp made by a conventional refiner mechanical pulping process, comprising: (a) comminuting the wood chips predominantly by splitting them along the wood grain thereof to make particles having dimensions in the cross grain direction of not over four millimeters; (b) wetting said particles by spraying them with a solution of a sulphite salt of an alkali metal to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said particles, said solution having a pH of about 7 to about 12.5; then (c) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing particles, after draining any excess solution therefrom, to a temperature ranging between about 85° C. and about 100° C. and holding the particles within that temperature range for about 30 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (d) thereafter passing said particles through a disc refiner to produce refiner mechanical pulp.

Claim 34

A process for making an improved refiner mechanical pulp from sawdust or shavings, said improved refiner mechanical pulp having lower debris and shive contents, lower bulk and higher brightness, without the use of bleaching chemicals, than refiner mechanical pulps made from sawdust or shavings by a conventional refiner mechanical pulping process, comprising: (a) wetting said sawdust or shavings by spraying them with a solution of a sulphite salt of an alkali metal to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said sawdust or shavings, said solution having a pH of about 7 to about 12.5; then (b) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing sawdust or shavings, after draining any excess solution therefrom, to a temperature ranging between about 85° C. and 100° C. and holding the sawdust or shavings within that temperature range for about 2 to about 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating an holding; and (c) thereafter passing said sawdust or shavings through a disc refiner to produce refiner mechanical pulp.

Claim 35

A process for making an improved refiner mechanical pulp from sawdust or shavings, said improved refiner mechanical pulp having lower debris and shive contents, lower bulk and higher brightness, without the use of bleaching chemicals, than refiner mechanical pulps made from sawdust or shavings by a conventional refiner mechanical pulping process, comprising: (a) wetting said sawdust or shavings by spraying them with a solution of a sulphite salt of an alkali metal to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said sawdust or shavings, said solution having a pH of about 7 to about 12.5; then (b) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing sawdust or shavings, after draining any excess solution therefrom, to a temperature ranging between about 85° C. and 100° C. and holding the sawdust or shavings within that temperature range for about 2 to about 80 minutes, said particles not being immersed in liquid subsequent to said draining and prior to completion of steam heating an holding; and (c) thereafter passing said sawdust or shavings through a disc refiner to produce refiner mechanical pulp.

Claim 36

A process for making an improved refiner mechanical pulp from sawdust or shavings, said improved refiner mechanical pulp having lower debris and shive contents, lower bulk and higher brightness, without the use of bleaching chemicals, than refiner mechanical pulps made from sawdust or shavings by a conventional refiner mechanical pulping process, comprising: (a) wetting said sawdust or shavings by dipping the into or spraying onto them a solution of a sulphite salt of an alkali metal to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said sawdust or shavings, said solution having a pH of about 7 to 12.5; then (b) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing sawdust or shavings, after draining any excess solution therefrom, to a temperature ranging between about 80° C. and 165° C. and holding the sawdust or shavings within that temperature range for about 0.5 to about 80 minutes, said sawdust or shavings not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (c) thereafter passing said sawdust or shavings through a disc refiner to produce refiner mechanical pulp.

Claim 37

A process for making an improved refiner mechanical pulp from sawdust or shavings, said improved refiner mechanical pulp having lower debris and shive contents, lower bulk and higher brightness, without the use of bleaching chemicals, than refiner mechanical pulps made from sawdust or shavings by a conventional refiner mechanical pulping process, comprising: (a) wetting said sawdust or shavings by dipping the into or spraying onto them a solution of a sulphite salt of an alkali metal to add said sulphite salt in an amount of about 1% to about 10% of the oven dry weight of said sawdust or shavings, said solution having a pH of about 7 to 12.5; then (b) steam heating, by adding steam directly thereto, the sulphite salt solution-bearing sawdust or shavings, after draining any excess solution therefrom, to a temperature ranging between about 80° C. and 165° C. and holding the sawdust or shavings within that temperature range for about 0.5 to about 80 minutes, said sawdust or shavings not being immersed in liquid subsequent to said draining and prior to completion of steam heating and holding; and (c) thereafter passing said sawdust or shavings through a disc refiner to produce refiner mechanical pulp.