Measuring pulp consistency and fines content with a streak camera

The problem of determining the fines content of pulp in cases where consistency is not known remains to be solved. We explored the hypothesis that this problem may be solved by studying shape changes in a laser pulse after it has travelled through the pulp.A matrix was constructed of pulp samples with consistencies varying from 0 to 1.5% by increments of 0.2% and fines contents varying from 0 to 50% by 10% increments. A streak camera was used to record three pulses simultaneously. The first was a reference pulse, which was used to calibrate the measurement pulses. The second was a pulse measured at an angle of 90° to the straight light path. The third was the straight path pulse.Different fines contents form their own lines on consistency–maximum power graphs and consistency–time of 50% power fall graphs. When transmitted power is plotted against time of 50% power fall the lines representing different fines contents cross each other. These results indicate that the fines content and consistency can be measured in some cases with a single measurement. Also, if water is added in a controlled manner, measurement of the lowering in consistency allows the original consistency and fines content to be determined.