• Celgar - first mill on mill scale in Oct/93, now Hinton, Kamloops too. Found 5% increase in overall pulp strength (tear at tensile), initial freeness went down slightly, also backed temp down, EA down from 15.5% to 15%, but digester is a bit unstable, harder to move plug due to numerous extraction points. Enough benefits to justify optimizing and solving the problems. Will be paper at Whistler on LSC, sensitive to wood species.
• Hinton - not as full blown as at Celgar, so operators have not had a problem with plug movement. Increase in tear from 177 tear to 187 tear at 7000 tensile, similar at 9000 tensile.
• Kamloops - only for last 2 or 3 weeks

Chemical usage change when using LSC?

• Celgar - in theory it should be easier to bleach but have not yet seen it, although Kamyr says there is a chemical savings
• Hinton - probably have small incremental drop in oxygen, peroxide, chlorine dioxide, say 1-1.5 kg/t ClO2

Stone - On MC pumps what do people use for vacuum?

• Celgar - both external and internal de-gassing with scrubber on each one, internal preferred
• Harmac - external on titanium MC pumps, replacing with internal, replaced manual valve with automatic butterfly valve so operators can control from panel
• AlPac - all internal de-gassing, no adjustment necessary

Marathon - who is using MC Do? converting?

• Using: Celgar, AlPac, Grande Prairie, Canton, Western
• Converting: Espanola, Northwood, La Tuque, Harmac

Northwood - who has post tower sensors on MC bleach upflow towers after wet launder ring?

• Alpac - brightness and residual sensor on level controlled standpipe, have not used it since startup, very sensitive to consistency change

Thunder Bay - for those mills converting to medium consistency (MC) Do stages, what are the expected benefits?

• Harmac - to replace a washer that was used for another purpose, and to regain washing efficiency lost when hot stock screening added closing the screen room, so COD went from 2.5 to 20 kg/t
• EBEddy - to MC rather than low consistency due to space and cost for equipment
• Norhwood - based on lab studies expect 10% savings at MC (10% consistency)

EBEddy - what mixer would be best for MC Do?

• Celgar - don’t use Hastelloy
• Northwood - just installed two Ahlmixers on D1 stage in B bleach plant, worked well, would put on Do MC
• Celgar - nobody uses Ahlmixer on Do now because of concern about high chemical application
• Kamloops - D1 and D2 have Ahlmix after Gould MC pump, works well, would consider installing on Do (replaced "Weyerhauser Special Mixer")
• Prince Albert - one mill in Indonesia is using ahlmixer on Do

Are mills with MC Do acidifying?

• Celgar - 10% acid added, but bad corrosion on motor caused by acid fume from de-gassing pump, but found that the acid was actually 19%
• Hinton - pH 3.0 - 3.5 at 4% consistency before ClO2 addition
• AlPac controls pH after addition of ClO2 to about 2.5 pH

Crestbrook loses 2-3 tpd ClO2 from D1 and D2 tower tops, want to scrub with chilled water, but calculations show that the theoretical best they can do is 25% efficiency and 2 gpl on scrubber. Anybody else runinto this problem?

• Harmac - similar problem when venting top of tower, will scrub in Eop filtrate scrubber, baffle top of tower before any additional scrubbing
• Kamloops uses chilled water scrubbers (20 gpm) on top of each tower, then return into tower
• Dennis Owen did a study on this issue in past
• PA - loses 0.3 tpd, suggests look at better mixing, channelling

Celgar - ClO2 generator - anybody uses titanium instead of tantulum cloth?

• Sterling - R8 always use titanium, 200 denier

Elk Falls - anyone use R8 saltcake for brownstock acidification?

• Leaf River has been operating a system for a year
• Robert Dube is the Sterling contact
• Hinton is installing a titanium nozzle into the stock line going to the blend chest, they will also make up with fresh acid when possible

Where do mills add tri-butyl phosphate in methanol?

• Mirimachi - add one litre into storage per methanol car
• Can-Oxy - pulp mills were adding to railcars, corroding cars, ruins hoses, forms oily surface
• Northwood - supplier was adding to tanker truck, probably dedicated to pulp mill service, concerned that it ruins hoses
• Thunder Bay, Hinton - dumps into storage tank
• Kamloops - adding to R8 generator continuously
• Marathon - add 1 liter per month to sample chamber, which is now titanium
• Prince Albert - switch from tygon to nylon hose

EBEddy - Anyone using soda ash for sodium makeup to liquor cycle?

• Northwood used soda ash as makeup, difficult to unload, hard to use
• Cariboo using for over a year, some unloading problems, but okay, used to reduce chloride in recovery since it is purer than caustic.
• Kamloops stores as saturated solution, draws off from top section of tank and makes up to 15% solution, then adds soda ash into green liquor clarifier. They don’t use purchased caustic makeup. Still have unloading problems

Stone - R10 users, where is the best place to add neutral saltcake?

• EBEddy - dissolves in 50% BL and returned to concentrator, does not dissolve well, so not sent to storage
• St. Felicien - WBL
• Avenor - oxidized BL
• Stone uses scrubber WL

St. Felicien - want to decrease ClO2 saltcake addition to reduce sulphidity, so where should we add caustic makeup?

• Harmac 10% to WL
• Miramichi 50% to WL pump
• Celgar 50% directly to WL storage tank
• Stone 50% to cascade

Northwood - what is best oxygen mixer and location for mini-oxygen stage?

• Histed - location under reactor tower, no bends
• Harmac - ahlmixer just before entrance on horizontal, then up, works well, draws very little power
• Crestbrook - 30% delig, problem seems to be oxygen mixer too close to high pressure steam addition (2 feet before oxygen) - will change Jun/95
• Celgar - single injection of steam and oxygen to mixer with interlocks to prevent steam backing into oxygen line
• Harmac discontinued using steam and oxygen together because steam backed up into oxygen storage
• Canadian Liquid Air - some oxygen mixing references are:
• "A Mill Survey of Oxygen Utilization in Extraction and Delignification Processes", D. Hornsey, A.S.Perkins, J. Ayton, M. Muguet, TAPPI June, 1991
• "Flow and Mixing Behavior of Low and Medium Consistency Pulp Suspensions Downstream of a Valve", D.W. Francis and R.J. Kerekes, Paprican, TAPPI September, 1992
• "Measurement of Mixing in High-Consistency Pulp Suspensions", D.W. Francis and R.J. Kerekes, JPPS July, 1990

Western Pulp - secondary effluent treatment - high TSS, BOD related?

• Stone - seen same thing in lagoons
• Air Products - too many filamentous bacteria?

Cariboo - now have two static mixers in Do stage - any benefit to hi-shear?

• Mirimichi - 2 komax + hi-shear,
• Mackenzie - 2 komax + hi-shear, on and off , no change in chemical usage, now out-of-service

La Tuque - any one have hi-shear mixer after clove rotor pump?

• Northwood - had peg mixer after clove rotor pump,changed to MC mixer and temperature profile was 12^oC. After modifications to the ClO₂ injector this dropped to 8^oC. Changed to MC pump and 2 hi-shear mixers, temp profile down to 2^oC.
• EBEddy now has 1^oC temp difference

Kamloops - who does chip species segregation?

• Celgar - 4 (very small) separate piles, fir, pine, hemlock, SBP, also had an aged pine pile in past
• Harmac - like most coastal mills Harmac has always separated species
• Elk Falls and Crofton also separate species
• Stone separates species
• St. Anne separates species
• Mackenzie Pulp - will be separating SPF within next few years

Stora - want to replace old Noss canister cleaning system - what do newer mills use for cleaning?

• AlPac - 5 stage Noss cannister, only problem is plugging on fourth stage
• Miramichi - 6 stage Celleco
• Sandwell - in Sweden some mills are using 0.2 mm slotted screens instead of cleaners
• Harmac - replaced old Noss system with Celleco so could see pluggage
• Smooth Rock Falls 6 stage Noss
• Mackenzie Pulp 6 stage Noss, 0.3 ppm average

Crestbrook considering Eop to BS washer - anyone else?

• Hinton - considered 25% recycle target (400 gpm), did not pursue due to high chloride levels
• Howe Sound considered it
• LP-Samoa (TCF) recycle 70%, no scaling problems
• Modo-Husum does it (OZD)

Alcell - any experience with removal of calcium oxalate scale - can only remove it with 30,000 psi water?

• Hinton - formic acid may work
• Port Alice has same problem
• some people say EDTA may help

EBEddy - Anyone using tall oil in digesters to control aspen pitch problems?

• Avenor Dryden and Thunder Bay
• Dryden reports 18 kg tall oil/t, they feel it is effective - when off they notice increased pitch problems.

AlPac - who uses pitch dispersant instead of talc?

• Donahue St Felicien in winter because of chips not aging
• Thunder Bay tried it for two or three days, got very dirty, so went off
• Miramichi - pitch dispersant in bs and detackifier on pulp machine. Adding pitch dispersants will clean up the system, so expect high pitch for a while after startup.
• Harmac replaced pitch dispersants with talc
• Celgar did trial, then went back to talc

Cariboo - who has good sensors on soap in BL storage - Cariboo shut down for 5 days

• Mackenzie Pulp has had two soap events in the last 4 years, operators now carefully check level daily
• St. Felicien has tanks half full of soap
• EBEddy swings between tanks when full of soap

Elk Falls - anyone running Do stage stricly on kappa factor?

• AlPac - has kappa estimator built into control, have almost cut outlet brightness signal to nothing, gradually cutting back on inlet brightness as well, so getting closer to kappa control
• Hinton - brightness is a poor way to control Do, better to use inlet Do kappa number, are moving towards kappa control

Crestbrook - For anybody using 100% ClO2 without peroxide, what kappa factor and brightness?

• Mackenzie - 0.21 kappa factor, 91 brightness
• Harmac - 0.19 to 0.2, 90 brightness

Stora - their sodium based sulphite mill is recovery boiler and evaporator limited, anybody transporting weak/heavy liquor off-site due to excess?

• Marathon - burning BL from Terrace Bay and returning GL, fairly common in US
• International Falls to Red Rock

Cariboo - any experience with Pulmac Fibre Strenth?

• Marathon - loves it, has dropped viscosity
• Mackenzie - evaluated, but found no relationship between strength parameters and Pulmac result

Marathon - Anybody looking at Environmental Management Systems?

• EB Eddy have looked at ISO 14000, looking at environmental console for DCS
• Harmac feels it is a bit premature to look at ISO 14000, but possibly BS 7750
• Mackenzie Pulp looked at ISO 14000 and BS 7750, decided not to pursue certification at this time, but is starting an in-house EMS
• Kamloops trained some people, but decided not to pursue at this time

Miramichi - Planning a CO2 trial, what should I expect? Where is the best place to inject it?

• La Tuque - drains much more, need to control pH carefully, added to shower last stage + vat last stage, pH should not be less than 10.5 pH or will precipitate lignin, can burn more liquor (viscosity?), also corrosion problems
• La Tuque - into interstage dilution pump and #2 bs washer shower bar
• Crofton will present a paper on CO2 at Whistler, 1995
• Histed - more Ca in pulp, more precipitation of lignin

How do you measure AQ yield increase? How much EA drop?

• Full mill month inventory change, 13.5% EA down to 12.75%
• Northwood - on-off trials, chip usage factor dropped during AQ trial
• Hinton - good article at Vancouver meeting TOC balance to prove yield increase