The next meeting is at Pointe Claire scheduled for early November. Dan Brinson from Northwood is chairman.

The committee meetings usually include visits to new mechanical pulping installations. The committee receives regular updates on mechanical pulping research being carried out by the Mechanical Wood-Pulps Network of Centres of Excellence.

There has been no correspondence or communication from this Committee.

The new chair is Ron Fujino from Canfor-Northwood who replaces Paul Stuart.

The Committee Co-sponsored International Environmental Conference in May with TAPPI. The conference was held in Denver, Colorado.

Next meeting is October 23,24 in Espanola (Domtar-Eddy)

Current Subcommittees:

Environmental Effects Monitoring

Environmental Management Systems

Activated Sludge Treatment Monitoring and Control

There has been no correspondence or communication from this Committee.

Richard Presley is the chairman and Wayne Bucher is the vice-chairman. Bob Packwood is the secretary.

Two subcommittees are presently in place, although our charter allows for more.

Steve Legge coordinates the Operations subcommittee (present operations issues)

Pete Gleadow coordinates the Minimum Effluent subcommittee (including R&D)

Major activities this committee sponsors include:

* IPBC: International Pulp Bleaching Conference (held every two years)

* TAPPI Pulping Conference, all bleaching sessions, roundtables, etc.

* TAPPI Bleaching Short Course

* Symposium on Minimising Bleaching Effluent

BP Operations Short Course was just held with good attendance. For the next two years, the dates and sites have been selected. These are April 17-20, 2001 at the Crown Plaza, Hilton Head SC, and March 25-28, 2002. Doug Reeve leads this short course, and has done an excellent job with this topic. We would like to see this continue however, maybe to consider other locations besides Gulf Shores and Hilton Head, maybe on the US west coast or in BC. Another suggestion is to have an audit committee of maybe 5 members to attend (free admission) and review the class for suggested changes.

Bleaching designations need to be reviewed. A suggestion has been made that Barbara van Lierop will co-ordinate with PAPTEC and then lead discussion at our committee’s fall meeting in Boston, with the objective of having one method agreed upon at the close of the fall meeting in Boston. It was questioned if this was realistic, given the history of this topic, however, we all realize this is only a guideline to establish a common short-hand language.

An existing task assignment CA # 960606.02, Controls for O₂ delig, has been approved by TAPPI. Bill Miller will revise the survey (make it shorter) prior to issuing to the US mills.

Two new committee task assignments submitted.

1. Impacts of O₂ delig on recovery cycle and impact of pulp washing efficiency on bleaching. TAPPI Note: 000606.01

2. What technologies are US mills using for bleaching today? Jeff Zierdt has volunteered to organise this effort to survey mills represented within the committee only. Anticipate output being a presentation at a pulping conference to open a round table discussion about sequences. TAPPI Note: CA number is 000606.02

By chairman Peter Gleadow:

Current activities of this subcommittee include:

* Closed-cycle short course – Tony Johnson, likely in fall, 2001

International Pulp Bleaching Conference in Halifax, report by Tom McDonough. This will be held 27-30 June in Halifax, Novia Scotia.

Dave Thirealt of Pope and Talbot at Halsey, Oregon discussed briefly their O₂ system, installed in 1993. They run campaigns alternating Douglas fir chips and mixed sawdust. Cooking is in M&D digesters with very short retention time, followed by 3 stages of vacuum washers. Slotted screens (0.014") are followed by the decker and the O₂ system. MgSO4 is added first. A custom-built system mixes O2 gas and steam with the pulp prior to going through two Ahlmixers, which are separated by about 2.5 minutes. They add typically 2% alkali and 2.2% oxygen, ratio controlled from the alkali charge. The reactor pressure control valve is at the blow tank with a back-pressure surge chamber inside the blow tank. This arrangement has avoided shaking and hammering of the blowline, a problem typical of many installations. Washing is with two wash presses, 0.9 meter diameter by 4.5 meter rolls. Pulp typically goes to bleach plant via the low consistency stock chest, but can be diverted to a brown HD.

Control is with a kappa analyser system. Pulmac wet zero span tensile is used to monitor pulp strength through the process.

Normal operation is 625 t/d with typical delignification rate of 45% on K No. Data was presented graphically on the operation with correlation between several parameters.

Ken Kendall of Weyerhaeuser at Longview, WA described their single stage O₂ delig system, now in operation for five years. They add either caustic or oxidised white liquor with a kappa analyser control system. Fibre length is also analysed, with three species run as separate grades. Softwood delig is 45% delig, and hardwood is about 40% delta kappa.

Operational problems include a physical movement at the top of the reactor, in a harmonic type sway. Adding more dilution at the top of the reactor eliminated this. Plugging of the stock line was a problem until a second valve was added at the top of the reactor. This valve is closed to facilitate flushing the blow line when shutting down.

Frank Steffes consultant to Valmet, talked about the present state of the science regarding oxygen delignification systems. He presented data from Pulp & Paper Canada magazine, Dec 1999. The survey data should not be taken as performance ability as some of the mills do not push the O2 system as hard as possible. This may be due to their objective of levelling the kappa into the bleaching system, or to optimise the balance between cooking, washing and oxygen delignification.

Normal maximum performances measured by delta kappa are:

Softwood Hardwood

Single stage systems 45 35

Mini- O₂ systems 5-30

Modern two stage systems 60-70 50

One primary reason for installing the newer technology is the improved yield of two stage O₂ compared to Kraft cooking yield. To take advantage of this, the cooking target kappa is raised, using the more selective chemistry of oxygen delignification to traditional kappa targets prior to bleaching.

Questions and comments from the floor about the general topic of oxygen delignification were diverse and spirited. Performance can be increased (% delta kappa) by increasing the oxygen driving force via raising the pressure rather than adding more oxygen gas. Ideally, to the raise the temperature of the pulp first (let the steam condense) prior to adding the oxygen, which should be preheated prior to mixing with the pulp stream. Heat load to the recovery boiler is probably insignificant, while the dry solids load is increased. The black liquor that is oxidised in the reactor is more of the temperature rise rather than the lignin on the pulp. Washing improvements are typically made when O₂ delig is added, with the washing alone making a significant change in the recovery load.

Tom Rollbuhler of EKA Chemicals presented the basics of chlorine dioxide generation, with customisation is possible for site specific needs. Acid and reducing agent are the two major types of changes that are practical. Neutral sulphate allows recovery of the saltcake. Systems operating at lower acidity require addition of a catalyst. System designs were originally at near atmospheric pressure, with modern systems under significant vacuum (22" water column). Integrated systems make sodium chlorate from NaCl, with added system complexity.

Reducing agents now are typically H₂O₂ or methanol. Site specific concerns may favour one over the other.

Small generators are being used for water treatment.

Ken Kendall of Weyerhaeuser described the MoDo integrated ClO₂ system at Longview, WA. Chlorine, electricity and dionized water are the feed streams.

Ed Bechburger of Sterling talked about implications of pushing a chlorine dioxide generator for maximum capacity. Considerations include safety and hazard reviews for changes, including regulatory permits, operator attention, reliability, significant or marginal increases, trade-offs in efficiency and operability, and cost (is replacement an option?).

Each piece of equipment and supporting process should be reviewed for its contribution to the expected capacity increase, trying to assess the limitations. Mass flux is impacted by the fixed equipment (size of the vessels), and mass flow. Minimise water inputs with proper mechanical seals, high strength methanol (80% v/v) and 700 g/l chlorate solution. More frequent liquor tests (every 2-4 hours) are recommended when pushing the system. Filters should be cleaned once a week. De-ionised water is one way to improve a system that is plagued by other minerals entering the system. Operating parameters such as heat transfer will need to be optimised, where shell side fouling can be a frequent problem.

Absorption towers can be optimised with special packing, water distribution systems (designed for the new, higher rate). Some mills make 13-14 g/l chlorine dioxide solutions, however, the explosion hatches should be reviewed for this condition. Saltcake filters can be optimised to more efficiently remove the crystals. Systems are unique so what helps at one system may actually hinder another installation.

Eric Fletty of TAPPI discussed the 2010 Vision committee and provided a handout to each of us about this effort.

At the request of the membership, TAPPI’s Board of Directors has looked at ways to modernise TAPPI so that it is streamlined, nimble, and responsive to members' needs now and in the future. We call this change the 2010 vision (nothing to do with the year 2010).

TAPPI members will have

• The opportunity to be involved in member communities that:

• Are easy to participate in
• Deliver high value to those involved
• Operate with minimal rules and maximum flexibility
• Are free from cumbersome structures and processes
• Are easy to form as new needs arise

• Products, services, information and staff competencies that are aligned to industry needs
• A more responsive association that can move more quickly to meet their needs

• TAPPI will continue to focus on what brings value to members:

• Access to technical information and experts, including peer interaction
• Content that is directly and immediately relevant
• Immediate accessibility, often on-line
• Industry information and news

Nothing to report.

• Carry on with courses the way they have been doing, i.e. maintain status quo.

• Take an active role in converting courses like the bleaching course to lever the best computer based training and delivery methods available today, which would first supplement and potentially replace the current courses.

• Move strongly to adopt the best computer based training and delivery methods as the PRIMARY mechanism for new course development.

• Move strongly to adopting short course methodology, typically one-day courses.

This Committee met in May in Whitecourt Alberta hosted by Alberta newsprint. The main focus of the meeting was harvesting and processing of lumber and pulp ( CTMP ) from fire killed timber

Guy Normandeau - DMI

Ralph MacDonald - ALPAC

Halsey, Oregon - Fall 2001

Dryden, Ontario - Spring 2001

Crestbrook, BC - Fall 2001

Chair - Don McCabe