Method for reducing fluorescence in pulp
A pulp and fluorescence technology, applied in the field of pulp source, can solve problems such as affecting the control cycle performance and affecting the response of the online color sensor, etc.
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Embodiment 1
[0040] D-H two steps, thickening between D and H
[0041] The pulp was first reacted with chlorine dioxide, then thickened to approximately 25% consistency, diluted to 11% consistency and further treated with sodium hypochlorite. Added ClO 2 The amount is 2.5 kg / ton (1000 kg) of dry pulp and the amount of sodium chlorite is 1.785 kg / ton of dry pulp. The total reaction time for the two steps was 7 minutes. Previous work has shown that the reaction ends after min. Chlorine dioxide times were 0, 2, 3.5, and 5 minutes. Zero represents the baseline case where both chemicals are added at the same time. The slurry concentration of chlorine dioxide and sodium hypochlorite reaction was 11% and the temperature was 71°C. The results are shown in figure 2 .
[0042] right figure 2 The analysis of ® showed increased fluorescence due to delays in sodium hypochlorite addition, even for delays as short as 2 minutes. Also, once such loss occurs, the increased delay has no additional...
Embodiment 2
[0048] H-D where there is no washing or thickening between D and H
[0049] Mixed office waste (MOW) was treated with a combination of chlorine dioxide and sodium hypochlorite in a two-stage process. In the first method, chlorine dioxide was mixed with paper and sodium hypochlorite was added after 5 minutes, followed by further mixing. The total residence time was 20 minutes and the temperature was 71 °C.
[0050] In the second method, chlorine dioxide was added and reacted alone for 20 minutes. Sodium hypochlorite is then added to the paper without intermediate washing or thickening. The residence time for this stage was also 20 minutes, for a total residence time of 40 minutes. The results are shown in Figure 6 .
[0051] right Figure 6 The analysis showed that both fluorescence and residual chemicals were reduced for the first method, albeit in half the time. Brightness and whiteness are both reduced for the D+H method.
Embodiment 3
[0053] FR Method - Zero Fluorescence Reduction
[0054] The recycled paper contained mixed office waste with an initial brightness of 89.95% ISO, including UV, and a fluorescence of 12.4, treated with a combination of chlorine dioxide and sodium hypochlorite, where both chemicals were added simultaneously.
[0055] Chlorine dioxide feed varied from 0 to 15.5 kg / t, while sodium hypochlorite was added at 2.9 kg / t and 5 kg / t. The paper was bleached for 15 minutes in a thermostatic bath set at 68C. The pH was not adjusted and allowed to fluctuate with the reaction. Brightness and fluorescence were measured with a Technidyne ColorTouch meter using D65 illuminant. The results are shown in Figure 7 .
[0056] right analysis Figure 7 It was shown that at 6 kg / t chlorine dioxide feed accompanied by 5 kg / t sodium hypochlorite, the fluorescence decreased to below zero. When sodium hypochlorite was reduced to 2.9kg / t, zero fluorescence was not achieved.
[0057] Measured ClO 2 Q...
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