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There are still many ways the pulping process can be improved


December 1, 2000
By Pulp & Paper Canada

Haligonians heard a cacophony of languages at the end of June as the 16th International Pulp Bleaching Conference as 334 delegates representing 21 countries filled the city.Conference chairman Ilkka W…

Haligonians heard a cacophony of languages at the end of June as the 16th International Pulp Bleaching Conference as 334 delegates representing 21 countries filled the city.

Conference chairman Ilkka Wartiovaara, KCL, welcomed delegates to Halifax by discussing the evolution of the conference (held every two years) and how new technologies have taken over centre stage. Technologies such as oxidative extraction, oxygen delignification and two-stage oxygen delignification, TCF pulps, the trends to closure and the use of ozone and enzymes.

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The conclusions of many papers could only be considered a beginning as the speakers explained that as work progressed, more doors were opened and more questions raised that needed to be answered. There is much work yet to be done.

Three keynote presentations opened the conference. The first was by Greg Schmid, Instutite of the Future, Menlo Park, CA. Speaking from the perspective of the user of paper — the consumer — Schmid said that the pace and speed of change today cannot be compared to any other time. However, he said that it is not technology that’s changing our lives, but how we use it.

“The new consumer is sophisticated, information empowered and uses practical discretion (more control over what they do and how they do it).” By 2010, Schmid said that 60% of the population (North America) will have been to college versus 35% in 1985 and 50% today. Average family salary will rise to $50 000/y by 2010. PC use was over 50% in 1999 compared with 15% in 1990. He said that already 46% of the population in North America fulfill these three criteria as does 38% of the population in Europe. And, the figure is growing rapidly.

What does all this mean? The “new, sophisticated” consumer is not leaving paper behind, but using it more effectively. This consumer also receives information from more than one source. Therefore, Schmid said, the new consumer is more skeptical and will not rely on just one source.

“The sophisticated consumer likes information that they control.” This, he added, is not great news for paper. “These people find interactive information searching more useful.”

The response from business is to act more like retailers. “They need to be close to their customers, interact with the customers and respond quickly and effectively with customers.”

Schmid said that the need to develop the “right” product through R&D and the ability to reach the customer are essential to future success. He said that competition is good for information. “More information is good for paper. These should be good years for the pulp and paper industry as competition and information increase.”

Schmid spoke about some of the changes driven by the growth of the Net. He also discussed paper’s role as information becomes more targeted.

“One critical change driven by the Internet is permission-based marketing. The marketer knows the consumer’s needs/interests that the consumer willingly gives. A second key change is online strategy. This technology is available 24 hours a day, seven days a week. A third element is that targeted spending will increase. Interactive media will grow the fastest, but none are paper-based. Finally, consumer direct spending will rapidly, from 4% today to 10 or 11% by 2010.

Schmid said that the “searching” activity is important and even sophisticated consumers use paper to search, e.g., catalogues. “Paper retains and enriches the amount of information given. There is a need to rethink paper and the role it plays in lives. It enhances the effectiveness of the information it is giving.”

Michael Bradley is director of technology, Canfor pulp and paper marketing. His talk, Pulp market drivers in the new millennium, focused on the near term. He said that people are still the primary drivers of change. Technology is the enabler.

He described four drivers of market pulp: business, social and environmental, science and technology, and sustainable development.

Business: Global economic growth should average 2.8%/y through 2015. Paper and paperboard consumption should just about match that, 2.6%/y. Bradley sees no reason to believe that cyclicality will change. However, it is much less severe when compared with other industrial sectors. Pulp has always been a globally traded commodity. The mergers and acquisitions trend should continue. Companies will move out of their regions to pursue global growth and some will move out of their “niche”. Bradley noted that the pulp industry is still behind the newsprint industry in this field. For example, the top 10 market pulp producers control 37% of world capacity compared with 57% in the newsprint industry.

Social and environmental drivers: Under this heading, Bradley said that the public is increasingly willing to chose environmental protection over economic growth. “Citizens want their leaders to err on the side of environmental caution.” He added that at the Seattle protests at the WTO meetings, middle class groups, not just “anarcho-green” groups were represented.

He added that values associated with industry are changing from economic values to ecosystem ones. He discussed the various certification programs: FSC, ISO, CSA. “Holistic or life style thinking is taking root. ‘Beyond a product’s use’ is becoming a norm for regulators.”

Suppliers are being judged more and more on their approach to environmental issues, not just price and quality. “The leading companies have adopted a holistic approach to managing their supply chain.”

Science and technology: The debate over biotechnology will continue, i.e., benign (enzymes) versus the controversial (genetic manipulation). Bradley said the pulp industry is mature, but with room for improvement. He said that developments will probably be driven by the papermakers, e.g., stratified printing paper.

Bradley added that fibre segregation is an area of opportunity. “There is great diversity within a tree but producers are taking advantage of it. Can we separate the fibre within a tree, e.g., spring wood vs. summer wood.”

There is also real untapped potential in the bio-energy field. “Too much wood is being wasted (burnt). It can be easily converted to other sources of energy.”

Sustainable development: This is not a new idea, Bradley said. “We have to meet the needs of today without compromising the needs of tomorrow. The idea now is that the whole system is what we should be thinking about.” Economics are only a part of it.

“Forest companies must recognize the forest for its natural capital. It must be recognized for all the services it can provide, not just the timber.”

The final keynote speaker traveled about as far as humanly possible to be in Halifax. Tony Johnson, AGRA Simons/Beca Simons, New Zealand, took a technical turn with his paper — Fibreline technology in the new millennium. The industry’s drivers will be profit, product quality and environmental sustainability. How do they connect with one another?

More fundamental R&D is needed, Johnson said, to realize the breakthroughs needed. “This is a means to a competitive edge.” He noted that 23 of 100 pulp and paper companies lost money in 1998, “so something needs to change.

“We need to re-establish fundamental science as the path forward. We cannot sacrifice science to ‘market idols’.”

Johnson then discussed some of the process negatives the industry faces. It loses 50% of its raw material. It uses large amounts of water. Mills come with high capital costs. There are odor and color issues. These issues need to be addressed, he added. Ways need to be developed to increase yield and fibre quality through biotechnology. There is some fundamental understanding of the structure of lignin, but no real breakthrough has taken place. Johnson also spoke of genetic modification technology. It has huge potential, but as most companies are well aware, it is “fraught with controversy.”

Johnson provided a few methods to improve the process. These include optimizing chip feed, precipitating the lignin to help realize extra capacity, reducing the extreme conditions in the pulp
making/bleaching processes and convincing customers to accept decolorized lignin in the end product.

Johnson also discussed several of the chemical and physical limitations in oxygen delignification and bleaching and gave delegates some ways to overcome them. Again, he spoke of the application of biotechnology to bleaching and delignification, saying it has “great potential. It mimics natural systems.”

In conclusion, Johnson said it was necessary for companies to integrate their R&R, operations, projects, marketing and suppliers. “Envision the fibreline in a pipe. Committing to fundamental research is critical.”

Chairman program Richard Berry, Paprican, and his team put together a full program that included 10 technical sessions and a two-day poster session. All of the graphics were shown via computer. There were no slides or overheads. Although it took a bit of work, it was well worth the effort and organizers of any future conferences should look seriously at this method.

Rather than give a summary of all the papers here, those interested should contact PAPTAC, which has the full conference proceedings, both in book (two preprints) and CD form. Again, for the informative content presented at this conference, obtaining the literature would sure to prove valuable for most mills. The CD contains all the poster presentations as well. To order, contact PAPTAC at 514-392-6963; fax: 514-392-0369; E-mail: pubs@paptac.ca.

The first session dealt with pulping. Bo Hortling, KCL, opened with a paper titled Influence of alkaline cooking methods on the bleachability and reinforcement power of softwod pulps. The objective of the work was to monitor the effects of different cooking methods on the bleachability and reinforcement properties of pulp. Four cooking methods were used: kraft (reference pulp), soda AQ, polysulphite AQ and sulphite.

The target brightness was 90 % for ECF pulps. The sequences tried were DEDED, ODEDED and OQPPPP. Hortling and his team looked at four properties: tensile, fracture energy, apparent tensile strength and apparent breaking strain.

The results showed that the carbohydrate composition of the pulps is almost unchanged after bleaching. Bleaching had the primary influence over fibre strength. Bonding ability correlates with a high hemicellulose content.

In the first of two sessions on oxygen delignification, Jean Bouchard, Paprican, spoke about the usefulness of PMS — peroxymonosulphate — and how the Opx process can improve oxygen delignification. The goal was to increase delignification in the oxygen stage. Now, delignification is limited to 40 to 60% at the industrial level because of the fear of strength losses. Adding a recovery-compatible oxidant (PMS) may be an answer. Although studies with PMS have been done before, Paprican was able to develop an alkaline mixture of PMS with no decomposition problems.

Bouchard said PMS can be added at the inlet of the O2 stage (PxO), between a double O2 stage (OPxO) or at the end of the O2 stage (Opx). Three trials were conducted. The best results were achieved when the PMS was added at the end (blowline addition). There was good delignification and good pulp viscosity.

Bouchard said that after three minutes, whatever the charge of PMS, the reaction is complete so there is no further effect on kappa number. He noted that there was some viscosity loss with time so the pH was adjusted.

How does the pulp bleach? The OPxDoEODED pulp had a similar viscosity, low COD and high brightness compared with the reference oxygen bleached pulp. OPx allows a 40% reduction in ClO2 use, a 30% reduction in AOX and a 39% reduction in COD. Versus an oxygen bleached pulp, there is slight loss in strength but they are comparable, Bouchard said.

In the session on mill experiences, Fred Munro, Domtar Eddy Specialty Papers, described the project done at the company’s Espanola, ON, mill. The title of the paper was Operating experience with an ozone-based ECF bleaching sequence. The Espanola mill has two pulping and bleaching lines, one softwood, one hardwood. Production is 1000 tonnes per day (t/d) of pulp. There are two integrated paper machines in the mill produce 200 t/d of fine and specialty papers.

The mill’s interest in ozone was spurred by AOX, dioxin and TCF concerns. An ozone pilot plant project was approved in 1992-93. In 1996, the mill received the go-ahead to modernize the hardwood line. An ozone-based bleaching sequence was developed in 1996-97 and the ozone stage started in May 1999.

Pilot plant results showed that low black liquor carryover is a key for efficient operation. Ozone is an economical bleaching agent. It raises the brightness ceiling and there are low environmental loadings. Munro told delegates that northern hardwood can absorb large amounts of ozone with no loss in strength or degradation of physical properties.

The mill’s bleaching sequence development work was based around an ozone stage. An acid stage was included for metals removal. Pilot plant trails showed acid pretreatment did not improve an ozone stage. It was installed to strip metals and eliminate calcium-based scaling on the bleaching equipment. In the paper, Munro wrote, “The acid charge required for the ozone stage is actually added to the A stage, extending the usefulness of the sulphuric acid.”

The mill chose a Z/D configuration based on a number of factors. These included work done by Air Liquide and the Centre Technique du Papier (France) as well as Paprican laboratory trials. The Do segment could be sized to handle the full bleaching load as a back-up to the ozone stage. Finally, there were no adverse effects on strength. It maintains pulp quality as 40% of production is sold as market pulp.

In its specifications for the ozone stage, the mill wanted excellent brownstock shives removal and low COD carryover to the bleach plant. The ozone plant capacity is 3.6 t/d.

Giving some details about performance, Munro said that aspen is easier to bleach than birch. As gas volume in the mixer increases past 30%, there is a loss of efficiency as not all the gas is consumed. He added that it looks like higher temperatures in the MC system can lead to better delignification efficiency.

On the pulp machine, the mill found no difference in pulp viscosity whether it used ozone or not. It seems, Munro explained, that the mill loses most of the viscosity in the ozone stage and not much in bleaching.

On birch, Munro said that ozone is a much more effective bleaching agent than chlorine dioxide. The replacement ratio is 3.8:1 (i.e., 1 kg ozone is equal to 3.8 kg chlorine dioxide). For aspen, the replacement ratio is 2:1 and there is not as high a gain in brightness.

In conclusion, Munro said that the use of ozone helped decrease bleaching costs by 8% and it decreased the pulp’s TOX content by 50 to 70%. Final brightness increased by 0.5% ISO. Mill effluent color was reduced by 27%.

The final paper of the conference showed that the future is now. Lou Edwards, University of Idaho, spoke about the “virtual bleach plant” in his paper, New predictive ECF bleaching models and their applications. Why a virtual bleach plant on the computer in front of you? It can do data auditing, online minimization of chemical costs, advanced process control applications and training. What’s in it? Mass and energy balances, chemical kinetic models, multi-phase, multi-component chemical equilibrium calculations (scale control, pH, metals management). As part of the presentation, Fredrik Lundqist showed a process simulation done at STFI. In his conclusion, Edwards said the virtual bleach plant has been “born and is growing”. Mill validations and applications are needed to produce “mature” results. He is looking for mill partners.

There were close to 40 posters presented at the conference. Prizes were awarded to the top three. The first prize winners were F. Chakar and A.J. Ragauskas along with Tom McDonough of IPST, Atlanta, for their poster Laccase-Mediator systems and oxygen delignification — A comparative study. Second prize went to C. Chirat, Centre technique du papier, for the poster Formation of chrom
ophores from carbohydrates during pulping and their impact on bleaching. Co-authors were C. Mateo and H. Furstoss, CTP, along with A. Jeunet, Universite Joseph Fourier, and D. Lachenal, Ecole franaise de papeterie et des industries graphiques.

Third prize was awarded to two posters — P.G. Caldas, C.J.G. Carneiro and V. Manfredi, Bahia Sul Celulose S.A., Brazil: Industrial evaluation for continuous production of ECF pulp at Bahia Sul Celulose; R.M. Lunn, Celgar Pulp, Castlegar, BC: Bleach plant washing: Mill experience in measurement technology and cost/benefit analysis.

Besides the high quality of the technical conferences, delegates were also treated to a great social program which included a night at Halifax’s historic Citadel fort and a lobster supper. The next IPBC will be held in Portland, OR, in 2002.


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