Cellulose (2025) 32:1835–1850
1839
Fig. 1 Schematic representation of the laboratory suction box used for the study
the desired pulse frequency. The reservoirs would be evacuated to a specific vacuum pressure to allow the administration of vacuum pulses to the hand sheets thus removing filtrate. The experimental setup is shown in Fig. 1. Fibre characterisation methodology Three pulp types were studied as specified i n Table 2. All samples were collected directly fro m the paper mill pipeline during stock preparation at different refining points. A sample of each wa s taken before the refiners. There were three bleache d hardwood pulp sample types, namely, the fee d to the refiner, refiner one and two. Recycled an d
groundwood pulp samples were categorised into th e feed and refiner one, equivalent to the number o f sampling points. The pulp concentration of the collected slurr y was computed as specified in ISO 4119:1995. Th e concentration for each characterisation method wa s obtained using Eq. (1) below. where C and V represent the pulp concentration and volume of slurry, respectively. Subscripts 1 and 2 signify the sample before and after dilution to the desired pulp concentration for the specific characteri- sation method. (1) C 1 V 1 = C 2 V 2
Table 2 Pulp sample specification
Pul p type
Pulping process
Wood species/grade
Bleached hardwood pulp
Kraft
Eucalyptus
Groundwood pulp
Mechanical
Spruce
Recycled pulp
None
New corrugated kraft waste
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