FO Focus On: Buckman 25 September/October 2020

| It segregates and contaminants, ink and contaminants, It segregates small ink particles, very It envelops It acts as a penetrant drawing water drawing It acts as a penetrant Longer pulper times in the pursuit in the pursuit pulper times Longer time in the pulper does not More facilitating the breakdown of the bales of the breakdown facilitating into a slurry. on the their redeposition preventing surface. being adsorbed them from preventing lumen and causing into the fibre darkening. fibre irreversible break down the ink, coating and the ink, coating down break into smaller and contaminants This in turn smaller particle sizes. particles the of the removal makes and flotation more screening across difficult. The water soluble and the these ink particles can smallest of very actually be absorbed into the lumen along with the water as the fibres of (1) This results and swell. hydrate they that is the fibre of in a darkening irreversible. with it. This speeds up disruption of and the hydrogen coatings the surface the base sheets, of bonding structure within the fibre lumen. within the fibre detachment reduce increased of financial The negative throughput. this is obvious. impact of to ink but serves just detach more 2. 3. The ideal situation for the operator is the operator The ideal situation for balancing for practice The most common 1. It stands to reason that the more ink more that the It stands to reason 1. 2. to be able to get as much ink detached as to be able to get quickly as possible. pulper output with ink detachment is to chemistry into add a surfactant three provides The surfactant the pulper. benefits: we can detach from the fibre, the higher the fibre, can detach from we that can be the potential final brightness the pulp Driving detachment in achieved. due to two curve is not a linear benefit pulper times: longer detrimental impacts of Tissue World Magazine World Tissue ink that remains attached to ink that remains detached ink free floating in detached ink free Bound ink: Free ink: Free the slurry which now has the potential the slurry which now and rejected. to be separated trapped or has been surface the fibre 2. 1. Doing so relies on three key functions key on three Doing so relies takes Ink detachment predominately place in the pulper. The bales of collected collected The bales of in the pulper. place into the pulper along with placed are and mechanical water, clarified process rotor-to-fibre is applied to create energy friction that separates and fibre-to-fibre as separating each other as well them from surface. the fibre and from the coatings to This is critical because it is not possible the process of the rest ink through remove the from detached it has been first unless exiting the pulper, Along with fibre fibre. ink: types of two are there the deink plant to maintain brightness, dirt the deink plant to maintain brightness, without sacrificing yield. and stickies levels ink the deink plant: detachment of of of the ink and separation the fibre, from stream, the fibre from contaminants of the ink and rejection and finally This paper will examine contaminants. steps and provide process these key to optimise them. on how guidance Ink detachment producers are finding it difficult to source to source finding it difficult are producers can only do so at elevated SOP or they to consider them This then forces prices. highly contaminated and more uniform less to lower Moving fibre. recycled of sources on furnishes puts pressure quality recycled

Focus On: Buckman On: Focus

work from home edicts being applied home edicts being from work the global vast swaths of across ith the recent global shutdowns and global shutdowns ith the recent

Mark Christopher Global market development manager – tissue, Buckman The situation is highly variable and other This reduction in supply is tempered in supply is tempered This reduction FO PRIVATE LABEL. PRIVATE DECLINES IN VOLUME SHARE IN SHORT- TO MID-TERM FORECAST, WITH MID-TERM FORECAST, TO DECLINES IN VOLUME SHARE IN SHORT- BRANDS AND PRICED LOWER HOUSEHOLDS SHIFTING MORE TOWARDS UNDER DIFFICULT OPERATING ENVIRONMENT AND IN VIEW OF CONSUMER ENVIRONMENT AND IN OPERATING UNDER DIFFICULT OFFER BRANDED THAT COMPANIES THAT IT IS EXPECTED PRICE SENSITIVITY, WILL SEE KIMYA, TUKETIM AND HAYAT TISSUE, SUCH AS ECZACIBASI RETAIL resulting in an easing of demand as they demand as they in an easing of resulting their inventory. down to draw begin during the early stages of the shutdowns in the shutdowns of during the early stages which potential shortages anticipation of a tighter supply early and is now created is the predominant user of recycled fibre fibre recycled user of is the predominant began Many companies SOP. like streams of SOP furnish a significant stockpiling somewhat by the concurrent reduction reduction the concurrent by somewhat which products, tissue AfH in demand for The reduction in office-based work has in office-based The reduction SOP being created in much less resulted collection. for and available economy, the sorted office pack (SOP) the sorted office economy, tissue by which is preferred waste stream impacted. has been significantly makers Christopher, global market development manager – tissue, Buckman, explains how deink plants can turn deink plants can turn how Buckman, explains – tissue, manager development global market Christopher, into a viable option. quality fibre lower AND YIELD QUALITY Mark Here world. the across work-from-home by increased been hit have of high quality fibre sources Office FOCUS ON: OPTIMISING DEINK PLANT PLANT DEINK OPTIMISING ON: FOCUS W Focus On: Buckman FO 26 ensure concentration of the contaminants re-cleaned inseveral steps tofurther banks suchthatrejects are re-screened/ size andweight respectively. contaminants from thefibre slurrybasedon operations of thedeinkplantseparate Screening andcleaning from Richard Venditti from NCSU(Figure 1). nature andsize are depictedinthediagram removing contaminants basedontheir steps andtheirrelative efficiencies at contaminants. processes toremove alltypesandsizes of Deinking plantsare designedwithvarious contaminants, from thefibre stream. fibre, we mustnow separate it,andother bound inkconcentration. final brightness of your pulp by reducing outlined above allows for higherpotential monitoring inkdetachmentefficiency as to impactdetachmentinthepulperinclude: efficiencies. brightness even atequalinkremoval is increased, resulting inhigherfinal it, thebrightness ceiling of thepulp Figure 1: The mostcommonly employed process Having detachedtheinkfrom the Optimising your pulpingoperation while • • Other parameters than canbeadjusted By removing more inkandsegregating They are typicallysetupincascading The screening andcleaningunit to disperse stickies. However, higherpHhasbeenproven bicarbonate, willspeeduptheprocess. the additionof causticoreven pH: speed upthepulpingprocess. Temperature: Tissue World Magazine Deinking processstepsandtheirefficiencies higher pH,often achieved via higher temperature will |

September/October 2020 Figure 2: plant iswithenzymatictechnology that to address these stickiesinthedeink itself (6). that are smaller thanthestickiesparticle can extrude through screen holesandslots pass through. Even larger stickiesparticles and stickiessmallerthanthisthreshold will larger thanthenominalslotsize, butink contaminants includingstickieswhichare screens willbeabletoseparate most approach mostmillsemploy (3).These stickies removal by screens, andthisisthe considered tobethebestapproach for many stickies. stages, butthisdoesnotincludeinkand can beeffectively rejected withcleaning specific gravity greater orlower thanwater and reduce yieldloss. Particles thathave a Another methodology often applied Low consistency slottedscreening is Total Stickies prevalence bysamplepoint distribution within both the pulp slurry and distribution withinboththepulpslurryand layer atthetopof theflotation cell. undesirable contaminants withinafoam This results inaconcentration of the they risetothetopof thesuspension. preferentially attachtothesebubblesas like inkandstickieswithinthepulpslurry suspension. Hydrophobic contaminants using airbubblesfloatedthrough apulp Flotation (Firgure 2). pulp asshown inthemillapplicationbelow significantly reduced stickies counts inthe include increased inkdetachmentand are notimpacted.Operational benefits specific, otherchemistriesandoperations mills. Becauseenzymetechnology is operations of pulp, packaging andtissue applied for over 20years intherecycled them more hydrophilic. characteristics of thestickies,rendering breaks down andchanges thesurface Bubble structure andstabilityinthecell order toensure highspecificair volume. air systemanditsinjectors isimportantin in theFigure 3(4). particle attachmenttakes place asdepicted over viaarange of methodswhereby bubble/ assumed thatstrong attractive forces take we denoteasthe“critical gap,” gc, thenitis to withinacertain minimumdistance, which interaction: Asabubbleapproaches aparticle removal efficiency andyieldloss (2). the foam layer whichsitsontopimpactsink The numberof bubblesandtheirsize The flotationdeinkingprocess works by This approach hasbeensuccessfully Proper optimisationandoperation of the Let usconsider thebubble/contaminant FO Focus On: Buckman 27

September/October 2020

| Reducing inlet consistency. Almost inlet consistency. Reducing Ash content preserved across flotation across preserved Ash content to the pushed forward Ash content in the sheet reduces Ash retained invariably, lower inlet consistency into inlet consistency lower invariably, in greater will result a washing stage the stage across increase consistency as ink separated) of fraction (greater at in the removal an improvement well perceived softness and increases and increases softness perceived dusting. will be rejected in subsequent washing will be rejected steps. retain difficult to machine is extremely consistency low in the high sheer, tissue used by process forming machines. Washing operation efficiency can be can efficiency operation Washing 1. One or more washing stages may be may be washing stages One or more • • • the mat and not rejected here. the mat and not rejected mechanisms: via the following improved Washing within a deink plant layout. present in a deink plant is A washing stage stage, technically just a thickening although depending on the plant water source a clarified configuration, may be used to dilute the stock just prior ink In washing, stage. to the thickening is efficiency removal and contaminant in increase the percent a function of A washer the stage. across consistency 1% a pulp slurry from that takes has to 2% consistency consistency assume If we the water. 50% of removed in the water dispersed the ink was evenly would we and no mat filtering occurred, Of course, a 50% ink removal. expect equipment, the depending on the design of are of mat filtering amounts different particles of and as such larger exhibited, within trapped are ink and contaminants the approach above, which increases SAV, SAV, which increases above, the approach This is via flotation. ash loss will increase the tissue for a concern of less generally the benefits by is overridden because it maker and the reduced pulp quality, the overall of benefits. in itself provides ash content Tissue World Magazine World Tissue It has been shown by Peters and Romigio and Romigio Peters by It has been shown not via flotation are Although ash losses The importance of this will become this will become of The importance Specific air volume (SAV) is defined as the is defined volume (SAV) Specific air as sensitive to cell consistency, applying consistency, to cell as sensitive we can maintain brightness at lower overall overall at lower can maintain brightness we yield loss. ink can of concentration (5) that improved cell operating be obtained at high flotation can be as long as the SAV consistencies along with it. In other words, increased at ink removal maintaining and improving ever requires consistencies higher flotcell air. of volumes larger considerations Yield flotation cell feed, generally expressed as expressed generally feed, cell flotation can see that changing We or L/Kg. cm3/gms consistency or the cell either the air volume in the SAV. in a change will result Depending on the floatation equipment may or may not have design, the operator but all the ability to impact air volume, consistency targeted can dictate operations the cells. of operation of to most how examine as we apparent the ink and other concentrate effectively such that stream in the reject contaminants Application of the correct deinking the correct Application of stickies improves in the cells surfactant systems. It in these and rejection collection Tinna Sarja that upwards by has been shown via can be removed microstickies 80% of of flotation (7). solids in the of air per unit mass of volume HYDROPHOBIC FORCES, AND STICKIES ARE HIGHLY HYDROPHOBIC PARTICLES. PARTICLES. HYDROPHOBIC HIGHLY ARE STICKIES AND FORCES, HYDROPHOBIC IN THE CELLS CORRECT DEINKING SURFACTANT OF THE APPLICATION AND REJECTION IN THESE SYSTEMS. STICKIES COLLECTION IMPROVES AN OFTEN IGNORED BENEFIT OF FLOTATION IS THE HIGHLY EFFECTIVE IS THE HIGHLY OF FLOTATION IGNORED BENEFIT AN OFTEN ALREADY WE HAVE PULP. QUALITY LOW STICKIES FROM OF REMOVAL IS ONE DRIVEN BY OF FLOTATION MECHANISM THE BASIC EXPLAINED HOW Schematic representation of a relative Effects of deinking surfactants on brightness vs. yield loss Effects of deinking surfactants An often ignored benefit of flotation is benefit ignored An often Modern deinking surfactants are intended are Modern deinking surfactants how the basic mechanism of flotation is the basic mechanism of how and forces, hydrophobic by one driven particles. highly hydrophobic stickies are the highly effective removal of stickies from of stickies from removal the highly effective explained already have We quality pulp. low down more easily. The effect is the ability The effect easily. more down equivalent at lower higher brightness to get 4. in the Figure as shown yield loss but carry through to the flotation cells where cells where to the flotation but carry through collection efficient to more contribute they that breaks froth the air and a foam ink by of reduces ink rejection or more fibre carryover carryover fibre or more rejection ink reduces yield. which reduces process the repulping to not just improve bubbles still float ink, but the resulting froth resulting froth bubbles still float ink, but the effect the has often This stable. more much is set points which level cell driving lower of floated fibre to drop down through the foam the down through drop to floated fibre acceptance. for and back into the cell froth the air is employed, When no surfactant froth, which is rejected, impacts yield as well. well. as yield impacts rejected, is which froth, bubbles do not allow Highly stable foam gap, gc, and capture radius, Rcap radius, gap, gc, and capture Figure 3: bubble/particle trajectory and definition of the critical Figure 4: Focus On: Buckman FO 28 with inkorstickies,problems withquality reintroduced intoyour system. of the clarified water streams as they will be important tomonitorandcontrol thequality to asthekidneys of thedeinkplant.Itis press. Thesesystems are often referred to afurtherthickening stage suchasascrew clarified waterstream. to maximisethequalityof thereclaimed operation treated withapolymericprogram fraction. Thisiscommonly doneviaaDAF and minimisedisposalcosts of therejects to maximisewaterrecovery andreuse streams mayemploy athickening stage(s) may besentdirectly toeffluent. Other reject Some stages, like secondary flotation rejects, must now reject themfrom thesystem. contaminants from thepulpsubstrate, we Rejection ofthecontaminants When watersystemsare contaminated The DAF rejects themselves maybesent Having detachedandseparated the 2. efficiency ofboth. stickies size range, improve washing stickies technology whichcanreduce break down inkparticlesorenzymatic Dispersing surfactants, whichcan spectrum. the larger particleendof theremoval Tissue World Magazine |

September/October 2020 it ispulping, screening, cleaningorother unit isdesignedtoaccomplish -whether mill withminimalloss of fibre orwater. objective isfor thecontaminants toleave and operational efficiency will result.The equipment andtheproper useof chemistry. a good design,proper operation of the A properly operated deinkplantrelies on the constant search for higherqualityfibre. viable optionthuseasingtheburden of lower qualityfibre sources are now a separation andremoval of contaminants, of eachpayseasydividends. operation -anddeterminingtheefficiency 3. 2. 1. With careful attentiontodetachment, Understanding whateachoperational pdf?sequence=1 EMERSON_ZACHERY_45. edu/bitstream/handle/10415/98/ University. https://etd.auburn. Systems. Dissertation. Auburn Bubble Interactions inFloatation T307-T312 (1993). flotation. Pulp& Paper Can. 95(8): Deinking of water-bornflexo inks by I JokinenH,ÄmmäläA,VirtanenJA, Emerson, IanZachery. Particle and Ackerman,C; Putz,H.J.;Gottsching,L. manager –tissue,Buckman. Christopher, globalmarketdevelopment 7. 6. 5. 4. This articlewas writtenforTWM byMark (2007). removal of stickiesindeinked pulp.” 11(3): 17-23. Single Slot. Progress in , Pressure Sensitive Adhesives Through a H., Lucas,B.E.2002.ThePassage of events/07recycle//peters.pdf http://www.tappi.org/content/ Flotation Cell Operating Variables. and Marc Degenais. Interaction of studies. VOL. 79:NO. 4TAPPI JOURNAL. 1: modelresults andexperimental predicting flotation efficiency Part V.THOMPSON. Globalmodelfor W. BOUSFIELD, ANDEDWARD DONNA A.JOHNSON,DOUGLAS Paper Research Journal21(4):451-459. pressure screening. Nordic Pulpand performance –alaboratory studyon of bargeometry onscreen plate Lindroos K&NiinimäkiJ(2006)Effect Sarja, T.. “Measurement, nature and Flanagan, J.,Venditti, R.A.,Jameel, Henry Peters, Tom Remigio, TimEvans RONGGEN PAN, FRITZG.PAULSEN,