The stock prep stages will vary by mill depending on the type of paper end product that is required; however nearly all mills will have some form of refining, chemical addition, and screening of the pulp. A typical first stage is to dilute the pulp and pass it through refiners. The refiners shred and flatten the pulp to improve its bonding characteristics. Chemical addition occurs downstream from the refiners.
pH Measurement Challenges
pH is measured throughout the stock preparation process. At the refiners pH control can have an effect on tensile strength (bonding) of the fi ber. Higher pH levels (> 8pH) will improve the ability to shred the pulp and may save on energy costs to run the refiner.
pH measurement in stock preparation areas can prove challenging. The pulp stock can be abrasive to the glass electrode. For applications where the stock consistency exceeds 12% abrasion becomes problematic; thus Barben Analytical recommends our “CF” flat glass coat resistant electrodes. Our standard hemispherical “R” and “CR” glass electrodes are well suited for lower stock consistency applications below 12%.