Deinking chemistry performance: from laboratory flotation tests to the simulation of an industrial pre-flotation line

Transcription

1 Deinking chemistry performance: from laboratory flotation tests to the simulation of an industrial pre-flotation line D. Beneventi, B. Carré, T. Hannuksela and S. Rosencrance Froth 2ry stage 2ry stage Air Air 2 1 1ry stage Froth 1ry stage Air Air Air Air Air Air Floated pulp Pulp feed

2 Guideline Motivations and objectives Materials and methods Laboratory flotation test procedure Data analysis and process simulation Results Laboratory flotation tests Process simulation Conclusions 2

3 Motivations and objectives Extrapolation of laboratory flotation tests to the industrial scale difficult/misleading Absence of a laboratory test/data analysis procedure to interpret and simulate the action of deinking chemicals at lab and industrial scale To develop a lab test procedure and a simulation tool to predict the influence of process chemistry on deinking selectivity in industrial lines Lab benchmark test Data analysis and process simulation Selectivity in industrial lines 3

4 Guideline Motivations and objectives Materials and methods Laboratory flotation test procedure Data analysis and process simulation Results Laboratory flotation tests Process simulation Conclusions 4

5 Materials and methods Laboratory flotation test procedure High consistency pulping Furnish: 50% OMG/50%ONP Consistency: 13% Temperature: 45 C Pulping time: 15 min Ca 2+ : 150 mg/l 5

6 Materials and methods Laboratory flotation test procedure Re-pulping chemistries tested in this study High consistency pulping Re-pulping chemistry NaOH (%) Silicate (%) Peroxide (%) Collector (%) Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate Furnish: 50% OMG/50%ONP Consistency: 13% Temperature: 45 C Pulping time: 15 min Ca 2+ : 150 mg/l 6

7 Materials and methods Laboratory flotation test procedure Laboratory continuous flotation Consistency: 0.8% Temperature: ~40 C Ca 2+ : 150 mg/l High consistency pulping Adjustable froth removal Pulp chest Furnish: 50% OMG/50%ONP Consistency: 13% Froth collection Temperature: 45 C Pulping time: 15 min To vacuum pump Floated pulp Air Ca 2+ : 150 mg/l Pulp aeration line 7

8 Materials and methods Laboratory flotation test procedure Laboratory continuous flotation Consistency: 0.8% Pulp feed flow: 2 L/min Temperature: ~40 C Ca 2+ : 150 mg/l High consistency pulping Adjustable froth removal Pulp chest Furnish: 50% OMG/50%ONP Consistency: 13% Froth collection Temperature: 45 C Pulping time: 15 min To vacuum pump Floated pulp Air Ca 2+ : 150 mg/l Pulp aeration line 8

9 Materials and methods Laboratory flotation test procedure Laboratory continuous flotation Consistency: 0.8% Pulp feed flow: 2 L/min Temperature: ~40 C Air flow: 4 L/min Ca 2+ : 150 mg/l High consistency pulping Adjustable froth removal Pulp chest Furnish: 50% OMG/50%ONP Consistency: 13% Froth collection Temperature: 45 C Pulping time: 15 min To vacuum pump Floated pulp Air Ca 2+ : 150 mg/l Pulp aeration line 9

10 Materials and methods Laboratory flotation test procedure Laboratory continuous flotation Consistency: 0.8% Pulp feed flow: 2 L/min Temperature: ~40 C Air flow: 4 L/min Ca 2+ : 150 mg/l volume: 14.5 L High consistency pulping Adjustable froth removal Pulp chest Furnish: 50% OMG/50%ONP Consistency: 13% Froth collection Temperature: 45 C Pulping time: 15 min To vacuum pump Floated pulp Air Ca 2+ : 150 mg/l Pulp aeration line 10

11 Materials and methods Laboratory flotation test procedure Laboratory continuous flotation Consistency: 0.8% Pulp feed flow: 2 L/min Temperature: ~40 C Air flow: 4 L/min Ca 2+ : 150 mg/l volume: 14.5 L High consistency pulping Froth removal thickness: 1, 2, 3, 5 cm Adjustable froth removal Pulp chest Furnish: 50% OMG/50%ONP Consistency: 13% Froth collection Temperature: 45 C Pulping time: 15 min To vacuum pump Floated pulp Air Ca 2+ : 150 mg/l Pulp aeration line 11

12 Materials and methods Laboratory flotation test procedure Laboratory continuous flotation Pulp characterization ERIC, Brightness Ash content (475 C), fibre content Mass flow High consistency pulping Adjustable froth removal Pulp chest Furnish: 50% OMG/50%ONP Consistency: 13% Froth collection Temperature: 45 C Pulping time: 15 min To vacuum pump Floated pulp Air Ca 2+ : 150 mg/l Pulp aeration line 12

13 Guideline Motivations and objectives Materials and methods Laboratory flotation test procedure Data analysis and process simulation Results Laboratory flotation tests Process simulation Conclusions 13

14 Materials and methods Data analysis and process simulation Flotation de-inking modelling Flotation dc dt k n n = = K n K n Q S Q S α g α g S cell cross section Q g air flow c n particle concentration K n experimental flotation rate c n d Adjustable froth removal Pulp chest Air Pulp aeration line 14

15 Materials and methods Data analysis and process simulation Flotation de-inking modelling Entrainment Adjustable froth removal Pulp chest dc dt n Q = φ V 0 f c n V cell volume Q 0 f water upstream flow c n particle concentration φ entrainment coefficient d Air Pulp aeration line 15

16 Materials and methods Data analysis and process simulation Flotation de-inking modelling Frothing Adjustable froth removal Pulp chest ε = Q f Q f + Q g ε = ε 0 e L d FRT ε water holdup ε 0 water holdup at the froth/pulp interface Q f water upstream flow Q g gas flow FRT froth retention time L d water drainage coefficient d Air Pulp aeration line 16

17 Materials and methods Data analysis and process simulation Flotation de-inking modelling Drainage Adjustable froth removal Pulp chest dm dt f = δ c nf Q d dm f /dt particle drainage rate δ particle drainage coefficient c nf particle concentration in the froth water drainage flow Q d d Air Pulp aeration line 17

18 Materials and methods Data analysis and process simulation Flotation de-inking modelling Adjustable froth removal Pulp chest Experimental data fitting with model equations Laboratory flotation tests d Air Pulp aeration line Extraction of transport coefficients Process scale-up and design using model equations Industrial line simulation 18

19 Materials and methods Data analysis and process simulation Industrial pre-flotation line Parameters used to simulate an industrial pre-flotation unit volume (L) cross section area (m 2 ) Pre-flotation feed flow (L/min) nominal flow (L/min) Gas flow (L/min) Number of 1ry cells Number of 2ry cells Recirculation rate on 2ry cells (%)

20 Materials and methods Data analysis and process simulation Industrial pre-flotation line Parameters used to simulate an industrial pre-flotation unit volume (L) cross section area (m 2 ) Pre-flotation feed flow (L/min) nominal flow (L/min) Gas flow (L/min) Number of 1ry cells Number of 2ry cells Recirculation rate on 2ry cells (%) Froth 2ry stage 2ry stage Air Air 2 1 1ry stage Froth 1ry stage Air Air Air Air Air Air Floated pulp Pulp feed 20

21 Guideline Motivations and objectives Materials and methods Laboratory flotation test procedure Data analysis and process simulation Results Laboratory flotation tests Process simulation Conclusions 21

22 Results Laboratory flotation tests Comparison of fatty acid soap and fatty acid-surfactant blend ERIC of floated pulp Fibre consistency in the froth Soap, 1% silicate Blend, 1% silicate Soap, 1% silicate Blend, 1% silicate ERIC (ppm ) cm 1cm 3 cm 5 cm Fibre consistency (g/l) cm 1cm 3 cm 5 cm Time (min) b) Time (min) 22

23 Results Laboratory flotation tests Comparison of fatty acid soap and fatty acid-surfactant blend Ash consistency in the froth Fines consistency in the froth Ash consistency (g/l) Soap, 1% silicate Blend, 1% silicate 2 cm 1cm 3 cm 5 cm Fines consistency (g/l) Soap, 1% silicate Blend, 1% silicate 2 cm 1cm 3 cm 5 cm ) Time (min) b) Time (min) 23

24 Results Laboratory flotation tests Comparison of fatty acid soap and fatty acid-surfactant blend Water loss vs. froth removal thickness Water holdup in the froth vs. FRT Water loss (%) Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate Water holdup (%) Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate Froth thickness (cm) b) Retention time (s) 24

25 Flotation yield of tested deinking chemicals Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Fibre loss (%) Blend, 1% silicate Fines loss (%) Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate a) Froth thickness (cm) b) Froth thickness (cm) Ash loss (%) Soap, 2% silicate Total loss (%) Soap, 2% Silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate 10 5 c) Froth thickness (cm) d) Froth thickness (cm) 25

26 Ink removal efficiency Results Laboratory flotation tests Ink removal (%) Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate Froth thickness (cm) 26

27 Guideline Motivations and objectives Materials and methods Laboratory flotation test procedure Data analysis and process simulation Results Laboratory flotation tests Process simulation Conclusions 27

28 Results Process simulation Froth 2ry stage 2ry stage 2 Air Air 1 Process yield 1ry stage Air Air Air Air Air Air Froth 1ry stage 6 Floated pulp Pulp feed Total loss 1ry Total loss 2ry Fibre loss Ash loss Loss (%) Fines loss Water loss Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate 28

29 Ink removal (%) Results Process simulation Laboratory and pre-flotation line flotation selectivity Blend, 2% silicate Soap, 2% silicate Soap, 1% silicate Blend, 1% silicate Soap, 2% silicate Soap, 1% silicate Blend, 2% silicate Blend, 1% silicate Lab flotation column Adjustable froth removal Pulp chest Air d Pulp aeration line Industrial pre-flotation line 2ry stage Froth 2ry stage Air Air 2 1 1ry stage Froth 1ry stage Air Air Air Air Air Air Pulp feed Floated pulp Total loss (%) 29

30 Guideline Motivations and objectives Materials and methods Laboratory flotation test procedure Data analysis and process simulation Results Laboratory flotation tests Process simulation Conclusions 30

31 Conclusions Laboratory flotation tests Froth collection Adjustable froth removal Pulp chest To vacuum pump Floated pulp Air Pulp aeration line Silicate decreases fibre loss by depressing fibre entrainment and promoting fibre drainage in the froth A decrease in ink removal due to more intense ink drainage in the froth was also observed when increasing silicate dosage from 1 to 2%. The fatty acid-surfactant blend gave a higher ink removal selectivity than that obtained with fatty acid soap 31

32 Conclusions Process simulation 1ry stage Froth 2ry stage 2ry stage 2 Air Air 1 Froth 1ry stage Air Air Air Air Air Air Floated pulp Pulp feed The performance scale determined during laboratory trials was respected and further emphasized by the layout of the simulated line The presence of a secondary stage in modern deinking lines boosts the ink removal selectivity The fatty acid-surfactant blend used with 2% silicate demonstrated the most favourable deinking performance 32