ANALYSIS OF INK ELIMINATION IN FLOTATOR Junsuke Kawana*1, - PowerPoint PPT Presentation

ANALYSIS OF INK ELIMINATION IN FLOTATOR Junsuke Kawana*1, Shintaro Sasada*2, Atsushi Watanabe*1 *1: Oji Paper Co., Ltd. Pulp & Paper Research Laboratory *2: Oji Paper Co., Ltd. Technical Department

INTRODUCTION (1) Requirements for DIP from ONP High Brightness (70-78%) Lower dirt count Lower stickies Uses a lot of energy and chemicals ! Energy consuming multi-step process High dosage of H 2 O 2 , NaOH, and Surfactant Bleaching Kneader Kneader Flotator Flotator Washer Pulper Screen Screen

INTRODUCTION (2) Improvement of current equipment efficiency Pulper, Flotator, Disperser, Screen… focused on Flotator

INTRODUCTION (3) Self-manufacturing of OK-flotator from 1984 Background Japanese Newspaper inks firmly bonded to fiber ! - Resin - Vegetable oil ( quick-drying ) Kneader or Disperser (1 or 2 stage) Fine dispersed inks Washer? Original flotator needed! But less water

Many bound inks in Japanese newspaper 30000 25000 Dirt spec (ppm) 20000 JAPANESE NEWSPAPER (Nikkei Shinbun) 15000 10000 5000 0 Japan Canada CANADIAN NEWSPAPER (Disintegrated, and Completely washed) (Vancouver Sun)

FLOTATOR CELL (1)

Rotating with blowing air Blower view bubbles FLOTATOR CELL (2) Rotary tube blower

Rotary tube blower Shower Inlet FLOTATOR CELL (3) Outlet Side view Shower

PURPOSE OF THIS STUDY More ink removal and brightness gain in flotator First of all, we measured -Pulp quality before flotation -Conventional flotation efficiency Bleaching Kneader Kneader Flotator Flotator Washer Pulper Screen Screen

PULP BEFORE FLOTATION(1) Multi-step disperser Inks detached and fragmented at the same time Brightness, % ERIC Ink diameter , u m Non- Washed Non- Washed Non- Washed Washed Washed Washed Before 57 63 290 60 5.4 7.0 Disp. After 61 74 74 360 360 30 4.1 4.1 5.7 Disp.

PULP BEFORE FLOTATION(2) Detached inks before flotation 10 u m or smaller 400 350 300 detached ink particles, The Number of 250 2 number/ mm 200 150 100 50 0 0 5 10 15 20 Ink diameter, μ m

CONVENTIONAL FLOTATION EFFICIENCY (1) - Only 5 points Brightness gain - Leaving many inks after flotation Brightness,% ERIC Non- Washed Difference Non- Washed Difference Washed Washed Flotator 51 51 73 22 830 40 790 In 5 Flotator 56 56 74 18 18 490 490 40 450 450 Pts Acc.

CONVENTIONAL FLOTATION EFFICIENCY (2) Removal rate fell rapidly below 7 u m (While small detached inks increased !) 100 90 of detached inks,% 80 Removal rate 70 60 50 40 0 10 20 Ink diameter, u m

SUMMARY OF CONVENTIONAL FLOTATION Before Flotation -Most inks fragment smaller than 10 u m Conventional Flotation -Only 5 points brightness gain -Left many ink particles smaller than 7 u m Removal of 7 u m or smaller particles is required. Change operating conditions -Blower Rim Speed -Air Volume (G/L) G/L= Air Flow Rate （ m 3 /h ） / Pulp Slurry Flow Rate （ m 3 /h ）

OPERATING CONDITIONS AND INK REMOVAL (1) Blower Rim Speed - Higher brightness gain due to higher rim speed - More ink removal for 7 u m and less dia. due to higher rim speed 100 9 Removal ratio of detached ink, % Brightness gain, points 90 8 80 7 70 6 60 8.7m/s 5 12m/s 50 16.5m/s 4 40 5 10 15 20 0 5 10 15 20 Rotation speed of blower, m/s Ink Diameter, u m

OPERATING CONDITIONS AND INK REMOVAL (2) Air Volume (G/L) Speed 16.5m/s : brightness gain improved due to higher air volume Speed 12m/s : not improved so much 10 12m/s Brightness gain, points 16.5m/s 9 8 7 6 5 2 4 6 8 10 G/L

OPERATING CONDITIONS AND INK REMOVAL (3) Air Volume (G/L) Speed 16.5m/s : More ink removal for 10 u m or smaller Speed 12m/s : More ink removal for 10 u m or larger 100 100 100 Removal ratio of detached ink, % Removal ratio of detached ink, % Removal ratio of detached ink, % 95 95 95 90 90 90 85 85 85 80 80 80 75 75 75 70 70 12m/s,G/L=6 70 12m/s,G/L=6 16.5m/s,G/L=4 65 65 65 12m/s,G/L=8 12m/s,G/L=8 16.5m/s,G/L=6 60 60 60 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 Ink Diameter, u m Ink Diameter, u m Ink Diameter, u m *G/L= Air Flow Rate （ m3/h ） /Pulp Slurry Flow Rate （ m3/h ）

SUMMARY OF OPERATING CONDITIONS Changing operating condition -Higher Rim Speed Higher brightness gain -Larger Air Volume (G/L) with . . . with High Rim Speed. Why? Bubble size measured.

DEVICE FOR MEASURING BUBBLE SIZE DISTRIBUTION - Fluid containing air passed through the measuring cell. - Pictures were taken with CCD Camera. - Bubble diameter was measured by image analysis. - Measured at different heights (lower, medium, and upper).

MEASUREMENT OF BUBBLE SIZE Factors which may influence the bubble size distribution (1) Fluid (2) Bubble growth (3) Blower rim speed (4) Air flow rate (G/L)

BUBBLE SIZE DISTRIBUTION (1) Fluid Water>Water with surfactant>Pulp Slurry with surfactant Water Water with surfactant Pulp Slurry with surfactant Water with Pulp slurry with Water surfactant surfactant Average bubble 1.4 0.681 0.447 diameter, mm

BUBBLE SIZE DISTRIBUTION (1) Fluid Water>Water with surfactant>Pulp Slurry with surfactant 80 Water 70 Water with surfactant 60 Pulp slurry with surfactant 50 Frequency,% 40 30 20 10 0 0 1 2 3 4 5 6 Air bubble diameter, mm

BUBBLE SIZE DISTRIBUTION (2) Bubble growth Bubble growth may affect ink removal UPPER MEDIUM LOWER

BUBBLE SIZE DISTRIBUTION (2) Bubble growth Water ; Bubbles grew at upper position. Lower 80 70 Medium 60 Upper 50 Frequency,% 40 30 20 10 0 0 1 2 3 4 5 6 Air bubble diameter, mm

BUBBLE SIZE DISTRIBUTION (2) Bubble growth Pulp Slurry ; No growth occured 80 Lower 70 Upper 60 50 Frequency,% 40 30 20 10 0 0 1 2 3 4 5 6 Air bubble diameter, mm

BUBBLE SIZE DISTRIBUTION (3) Blower rim speed The faster the rotation speed, the smaller the bubble diameter Smaller bubbles led to higher brightness! 40 15m/s 35 0.42mm 17m/s 30 19m/s 25 0.45mm Frequency,% 20 15 0.59mm 10 5 0 0 1 2 Air bubble diameter, mm

BUBBLE SIZE DISTRIBUTION (4) Air Flow Rate-1 Air flow rate up ; bubbles smaller than 2mm decrease and bubbles larger than 2mm increase. 45 15m/s,30m3/h 40 15m/s,70m3/h 35 30 Frequency,% 25 20 15 10 5 0 0 1 2 3 4 5 6 Air bubble diameter, mm

BUBBLE SIZE DISTRIBUTION (4) Air Flow Rate-2 Air flow rate up + rotation speed up ; Smaller bubbles increased Smaller bubbles led to higher brightness! 45 15m/s,30m3/h 40 15m/s,70m3/h 35 19 ｍ /s,70m3/h 30 Frequency,% 25 20 15 10 5 0 0 1 2 3 4 5 6 Air bubble diameter, mm

CONCLUSIONS (1) In the conventional state Before flotation -Most inks fragment into particles of less than 10 u m Conventional flotation -Only 5 point brightness gain -Left many ink particles smaller than 7 u m Operating conditions Higher brightness & removal of smaller ink particles at -Higher rim speed -Larger air volume (G/L) with high rim speed.

CONCLUSIONS (2) Air bubble size measurement Small bubbles at… -High rim speed -Large air volume with high rim speed lead to higher brightness gain By applying these findings, we could succeed in improving the deinking efficiency with our flotator

FUTURE TASKS … More improvement in efficiency （ Electricity consumption, Retention ） Optimal Cell structure Optimal surfactant Thank you for your kind attention!

Optimal Cell structure FUTURE TASKS

CONVENTIONAL FLOTATION EFFICIENCY (3) Smaller inks significantly influence brightness! 70 70 70 ISO brightness, % ISO brightness % ISO brightness,% R2 = 0.63 R2 = 0.93 R2 = 0.99 65 65 65 60 60 60 55 55 55 50 50 50 0.0 1.0 2.0 0.0 0.5 1.0 0 500 1000 3-100um inks, % 3-10um inks, % ERIC