global trends effecting the design of retention aid programs · global trends effecting the design...

Global Trends Effecting the Design of Retention Aid ProgramsLarry Hutchinson

Solenis LLC

IPPTA – “Enhancing Productivity, Quality, Value Addition, and Environmental Sustainability Through Specialty Chemicals”

Resort Rio, Goa, India, 19-20JUL2019

2 • Confidential and proprietary.

Global Trends

Importance of Retention

System Closure

Multifunctional Chemistry and the Crowded Wet End


Magic!


Water

Food Safety

EHS/

Hygiene

g/m²

Speed

Furnish

Complexity

Furnish

Strength

Ash Content

ContaminationVariation

Dewatering

pH

CaCO3

Temperature

Conductivity

Scale

System Charge

Functional Chemistry

Process Chemicals


34.0

35.0

36.0

37.0

38.0

39.0

Mill A Mill B Mill C Mill D Mill E Mill F Mill G Mill H Mill I Mill J

35# HPL - Basis Weight Comparison

Low BW for a totally

closed mill, but also the

slowest machine in this

survey @ 1900 fpm

Closed Open

Impact of Mill Closure on Sheet Strength


Retention Programs

Deposit Control

Drainage/Dewatering

Chemical Efficiency

What is the job of a paper machine?


Liquid/Solids Separation

Fiber Furnish & Contaminants

Filler

Water

Broke & Contaminants

Functional Additives:

DSA, Size, WSR, Dyes

Process Chemicals:

RDC, MB, AF/DF, CC

Accumulation = Efficiency Loss + Deposition

Sheet

Stock

PrepFormer Press

control of system inputs

and purge points


Softwood Fiber

Length = 3500 µm (50’)

So

ftw

oo

d F

iber

Wid

th=

36

µ m

PrecipitatedCalcium Carbonate

0.2-2.0 µm

Size

1 µm

Hardwood Fiber

Length = 1200 µm (17’)

Hard

wo

od

Fib

er

Wid

th =

22

µm

Pitch Particle

Dispersed

0.1 µm

Calcium Carbonate

Ground

0.2-5.0 µm

Titanium

Dioxide

0.1-1.0 µm

Small Fiber Fine

5 X 15 µm

Flocculant

0.1m µm

Coagulant

0.05 µm

Clay

0.3-2.0 µ m

“retention” is

not about just

one material


Size, Shape, Surface Chemistry

Kaolin Clay @ 8500x Talc @ 5000x Chalk @ 4500x TiO2 @ 10,000x

Rhombohedral PCC @4500x Aragonite PCC @ 4500x Scalenohedral PCC @ 4500x GCC @ 5000x

Increasing use of fillers

can place tremendous

demands on the

retention system. Filler

characteristics can vary

widely and should be

carefully factored into

the overall retention

system design.


100

50

75

25

0

INC

RE

AS

ING

RE

TE

NT

ION

INCREASING PARTICLE SIZE

Thickening & Filtration

Mechanism

Mechanical

AbsorptionMechanism

Chemical

CLAY, GCC

0.5-20 µm

WIRE SIZE150 MESH

FINES

<75 µm

TiO2, PCC

0.2 - 0.5 µm

LONG FIBER &

FIBER FRAGMENTS

Not only is retention

important but how

materials are retained,

how that effects where

they end up in the sheet

and impacts on drainage

and dewatering are

critical.


Sheet Forming

Water

Fiber

Fines

Filler

Stickies & Pitch

Sizing

Starch

Retention Aid

Water

Fines

Filler

Stickies

Other Stuff


The Retention Paradox

Cost

Deposits

Speed

Strength

… how low can we go?


Consequences of system closure …

HBMCBCTo

wer

Pre

ss

Polydisc

Short Loop

Long Loop

Cleaning

Th

ick

en

ing

Fib

er p

rod

.

Broke

Conductivity

Speed

Strength

Additives Efficiency

Additives Effectiveness

Deposition


14

Bull

Screen

Chest

GWD

ThickenersGrinders

RCF

Tower

GWD

WW

Chest

WW

Chest

Screening &

Cleaning

GWD

Thickener

Chest

PM GWD

TowerGWD

Storage

Tower

GWD

Storage

Tower

PM Broke

Tower

UBKP

NBKP

TL BC

FL BC

BL BC

TL MC

FL MC

BL MC

TL Former

FL Former

BL Former

TL WW FL WW BL WW

OCC, MXW

Dry Broke(contains clay,

CaCO₃, starch,

latex from coating)

Wood

Fresh Water

Fresh Water

Perform PK 2320

Alum

PK 2320

Na2S2O4

6kg/t

Coating Effluent

Caustic

PC8717

Refining

Refining

DF

Alum

NaHCO₃

H₂SO₄

Clay

Biocide

Biocide

Biocide

Biocide

Biocide

Aquapel AL215/

Hi-pHase 40T

Biocide

Na2S2O4

(NNIU)

Couch Pit

System Overview - Major Chemical and Furnish InputsNote: Does not include wet end defoamer which is used intermittently, or

thin stock RDC

Map the system

and understand the

dynamics

System Closureconductivity is a marker …


System Closure

• Use the cleanest water you can get▪ Surface vs. bore well▪ Clarification

• Strategic use of low conductivity water streams

• Minimize high conductivity input streams

• Purge the most highly contaminated water

• ”Kidneys”▪ Clarification▪ Membrane filtration

• Chemistry selection for high conductivity systems▪ Nothing gets better with conductivity▪ The problem may be more to do with lignin or other soluble materials than conductivity▪ Get outside the box on flocculant selection▪ Trash management/Lignin management


Industry Experience

Chemical Efficiency

T&T

Recycled Container

Virgin Container

Conductivity: ~1,000

Conductivity: 5,000+

Conductivity: ~2,500

Does conductivity

adequately explain

the loss in chemical

efficiency?


Organic vs. Inorganic Comparison

▪ Higher organic concentration negatively impacted drainage / chemical efficiency

▪ Higher conductivity (inorganics) had a minimal impact to drainage / chemical efficiency

Organic load had a much greater impact

on chemical efficiency compared to

inorganic load (conductivity)


Effect of Lignin on Polymer Efficiency

Increasing lignin reduces

impact of drainage aid


Typical papermaking … more than one factor!

Chemical Efficiency

T&T

Recycled Container

Virgin Container

Conductivity: 1,000

Lignin: <30ppm

Conductivity: 5,000+

Lignin: 50-600ppm

Conductivity: 2,000

Lignin: 100-2200

Loss in chemical

efficiency is better

explained by increasing

soluble lignin content.


Lignin Management in Unbleached Kraft

Key Finding: Improving polymer efficiency requires

lignin removal, not conductivity reduction

The Challenge:

▪ Packaging Growth and Sustainability Drivers are

Creating a Need for More Effective Chemical

Solutions

▪ Wet end chemistry struggles in most unbleached

Kraft furnishes

Key Learnings:

▪ Organic contaminants, namely lignin, have a much

greater effect on chemical efficiency than inorganic

▪ Lignin can be monitored, controlled and managed to

improve performance of wet end chemistry

▪ Some chemistries are more resilient to lignin than others

▪ Significant lignin removal from the soluble phase is

possible and can greatly increase chemical efficiency

▪ Program design can be improved with Lignin

Management approach

Additives Multifunctional Role and Impact on Retention Chemistry

Strength

DrainageRetention

Fusion


Multi-Functional Chemistry & Trends

• Coagulants/Fixatives

▪ Inorganic

• Alum, PAC

▪ Organic

• Polyamines, polyDADMAC, PEI

• Flocculants

▪ Cationic, anionic, non-ionic

• Aqueous Dispersed Polymers

• Enzymes

• Dry Strength Additives

▪ Starch, APAM, CPAM, AmPAM, PVAM, GPAM,

on-site GPAM

• Wet Strength Additives

• “Microparticles”

▪ Silica Based Microparticles

• Structured, Surface Modified, On-site generation

▪ Bentonite

▪ Structured Polymers

• Coated Broke Treatment

• Furnish Pre-Treatment

• Filler Pre-Treatment

• Sizing

▪ Rosin, AKD, ASA

• Surface Applications

▪ Sizing

▪ DSA’s


Retention Program Design Considerations

• Furnish components have wildly different capacities for “chemistry”

• RCF: content ➚, strength ➘, ash content & contamination ➚

• CaCO3 ➚, pH ➚

• Sheet ash ➚

• g/m² ➘, speed ➚

• … the wet end is a lot more crowded and challenging place!


Going neutral/alkaline changes the alum scenario …

Using alum at alkaline pH requires understanding what you want to do with it and getting the dose point(s)

right. PAC and or cationic polymers are often a better option.


Balancing System “Charge”

“Charge” (Soluble, Total, Colloidal)

“0”

“R

ete

nti

on

”

“-” “+”

“Threshold Charge”

behavior, just need to

keep charge above a

minimum or chemical

is wasted.

“Sweet Spot

Charge” behavior,

ideal charge range

for stable retention.

Retention theory says best retention

should be with charge near “0” but …

Sensitive to cationic

demand, narrow

operating window

Less sensitive to

cationic demand, wider

operating window


Dosing Regime, Injection, Mixing

Primary

Screen

Fan

Pump

Cationic Starch

or DSA

Flocculant

Structured Silica

VMAX

Injection

VMAX

Injection

VMAX

Injection

Dry Strength

Structured Polymer

Sizing

Alum or

PAC

Alum or

PAC

Wide variety of options, key

is choosing correct

scenario for planned

chemistry and insuring

good mixing with best

practice injection

technology.

Best practice injection

and mixing technology

enables a greater

number of dosing

options post-screen

which greatly increases

performance

Thick/thin dual DSA

addition.

Filler pre-treatment

Broke Pre-Treatment

Stock Pre-Treatment

Dilution water

quality matters;

• Hardness

• Conductivity

• Temperature

• pH


Think multi-component retention systems …

#2Polyacrylimide

Addition

(Bridging /

Flocculation)

Process

Generated

Shear

#3Structured Silica /

Structured Polymer

Addition

(Micro-flocculation)

#1Coagulation,

Cationic

Demand

Modification

+ +

+

++

+

++ + +

++

++

+

Thick/thin dual DSA

addition.


Broke Pre-Treatment

Stock Pre-Treatment

Multi-component, high

performance retention

systems integrated with

…

Filler pre-Treatment


Filler pre-treatment … balancing strength & loading

TreatedFiller

BondingPolymer

Fiber

1)

2)

Aggregation Polymer

Filler


Optimal Particle Size Distribution

0

1

2

3

4

5

6

7

1 10 100 1000

Freq

uenc

y %

Diameter µm

Particle Size with Treated PCC

Blank Filler-Fiber Optimization Over aggregation

• Moderate aggregation targeted for optimal strength, retention and optical properties• Aggregates are shear stable

0

2

4

6

8

10

12

14

16

18

20

0 5 10 15 20 25 30 35

Fre

qu

ency

%

Diameter µm

Particle Size with Treated PCC

Filler-Fiber Optimization plus 1 min sonication


Pilot machine results: Filler-Fiber optimization program can maintain ZDT

Tensile and ZDT Impact

15

17

19

21

23

25

27

15 17 19 21 23 25 27 29

GM

T N

∙m/g

Ash %

Dry Tensile on 50 lb/3000 ft² Paper

Blank Bonding Bonding &Aggregation

40

45

50

55

60

65

15 17 19 21 23 25 27 29

lb/i

n²

Ash %

ZDT on 50 lb/3000 ft² Paper

Blank Bonding Bonding &Aggregation


• Handsheet data showing wet web tensile (on never dried sheets)

• Loss recovered with aggregation + bonding approach

Wet Web Strength

0

0.2

0.4

0.6

0.8

1

Ten

sile

lbf

Tensile on Never Dried SheetsSheet Solids 50%; PCC 20 30%

Untreated 20% Untreated 30% 30% Filler-Fiber Optimization Program


Z-directional Filler DistributionImproved Distribution with Higher Filler Content

• Uniform z-directional filler distribution helps limit dusting tendency.• More potential for filler increase.

20

25

30

35

40

0 10 20 30 40 50 60 70 80 90 100

Sh

eet

ash

co

nte

nt

(%)

Cumulative % of sheet from bottom to top

Baseline 25,1% Ash Bonding & Aggregation 28,8% Ash

Poly. (Baseline 25,1% Ash) Poly. (Bonding & Aggregation 28,8% Ash)


Grade

Furnish

Process

System Closure

Strength Program


Broke Pre-Treatment

Stock Pre-Treatment

Injection & Mixing

Retention Program

global trends effecting the design of retention aid programs · global trends effecting the design...

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