Method of selecting wood for mechanical pulping

Abstract

A method of selecting bulk wood units for mechanical pulping, which consists of establishing a reference scale by selecting a test sample measuring the acoustic velocity through each sample unit, selecting acoustic velocity band from the sample results, processing the sample units using known mechanical pulping processes, testing the resulting pulp to measure the freeness of the pulp, and then graphing the pulping energy measurements against the pulp freeness measurements for each of the velocity bands to produce a reference scale; measuring the acoustic velocity through each of the units, comparing the velocity measurement for each unit against the reference scale, and then dividing the tested units into subgroups according to the predicted mechanical pulping energy.

1 . A method of sorting for mechanical pulping a batch of bulk wood units, comprising the steps of: 
 1) Establishing a reference scale for the timber group to be sorted by: 
 a) selecting at random a plurality of sample units of bulk wood from the timber group;  
 b) measuring the acoustic velocity through each of said sample units using a predetermined measuring technique;  
 c) recording said acoustic velocities and grouping said velocities into two or more velocity bands;  
 d) processing all or part of each of said sample units to pulp using a predetermined mechanical pulping process;  
 e) measuring the energy used to pulp each said sample unit;  
 f) measuring the freeness of the pulp from each said sample unit;  
 g) for each of said velocity bands, graphing pulping energy measurements against the corresponding pulp freeness measurements to produce a reference scale;  
   2) Measuring the acoustic velocity through each of said bulk wood units in turn, using said predetermined measuring technique;    3) Comparing said acoustic velocity measurements against the reference scale and said velocity bands to predict the mechanical pulping energy required to pulp each tested unit; and    4) Dividing the tested units into subgroups according to the predicted mechanical pulping energy.    
     
     
         2 . The method as claimed in  claim 1  wherein before said acoustic velocity bands are selected, the acoustic velocities from all of said sample units are graphed to show th distribution of acoustic velocity in the total sample, to enable the velocity bands to be selected such that a predetermined proportion of bulk wood units fall within each of the selected velocity bands.  
     
     
         3 . The method as claimed in  claim 1  or  claim 2  wherein each of the batch of bulk wood units is of the same or similar species and has a similar history, in that each of the bulk wood units is of about the same age, has been grown under similar conditions, and managed in a similar fashion.  
     
     
         4 . The method as claimed in any one of the preceding claims, comprising the additional steps of: 
 h) measuring the fines content of each of said sample units;    g) for each of said velocity bands, graphing fines content against pulp freeness measurements to produce a reference scale.    
     
     
         5 . Paper made from bulk wood units sorted according to the method of any one of claims  1 - 4 .