At the time of Plainwell's conversion to alkaline papermaking, in 1982, the author was Manager for Technical Operations for Plainwell Paper Company. This paper was presented at the 32nd Annual Pulp and Paper Conference, sponsored by the Michigan Division of PIMA, the Kalamazoo Valley TAPPI and the Western Michigan University Department of Paper and Printing, Science and Engineering, in March 1988 in Kalamazoo.
Simpson-Plainwell Paper Company acquired its present name, the latest in a long line of names, in December, 1987, when Simpson Paper Company of San Francisco purchased this mill (located in Plainwell, Michigan, about 20 miles north of Kalamazoo) from Chesapeake Corporation.
This mill has been in existence for 102 years. The products produced over the years span the gamut of paper grades--brown paper, newsprint, uncoated printings, coated printings, colors and technical specialties are just a part of the product lines at one time or another. There have been many owners--Michigan Paper Company, Hamilton Crocker, Weyerhaeuser, Philip Morris and Chesapeake, to name the most recent ones. We are happy to be a Simpson mill now. We believe this acquisition will be beneficial to the corporation as well as to the industry in general, the state and community, and most of all to the employees at Plainwell.
The present grade structure has two main parts: high quality printing papers, both coated and uncoated; and products for the pressure sensitive label business. My subject concerns mostly the printing paper side of our grade structure. The mill is equipped to produce about 65,000 tons per year of printing paper grades on our three machines. The majority (45,000 tons) are coated on our No. 18 paper machine, which has a two-side trailing blade coater installed on it. We make Premium No. 1, No. 1 and No. 3 grade coated papers. Some are matte finished and some are gloss. In addition, we make a very nice enhanced offset called Satin Kote on our No. 16 P.M. Our No. 17 P.M. is devoted to the pressure sensitive business.
Both No. 16 and No. 18 P.M. are fully alkaline and have been so since 1982. "Alkaline!' to us means using CaCO3 as a filler, using a synthetic sizing agent and operating at around 8 pH. We use no alum at all in the mill.
It is important to realize that Plainwell uses certain products for historical reasons and because they work for us. We have not trialed all the alternate products. In many cases we have not tried any alternate products. So no one should look to us for endorsements.
The mill's philosophy about going alkaline was to do it as easily as possible, to change as few things as possible at once, and to allow the process to guide us to more optimal levels of operation, rather than force the operation to accept a new process.
The big question everyone asks is this: Is it hard to go alkaline? The answer is simple: YES AND NO. How hard do you want to make it? Do you have lots of technical staff banging around with not much else to do? Then you can make it as hard as anything. You can run multiple paper machine trials, repeated field evaluations and several printer consultations. Or, if you are strapped for people, time, money and knowledge, you can just go. All you need is a motivation, some management backup and a few (not too many) supplier experts who really want to sell you something.
The latter way is sort of the way we did it in 1982. Our motivation was simple: We had a badly screwed up acid wet end system. We used way too much alum and yet we still couldn't control pH. We added lots of rosin-size, but we couldn't count an getting the size test we wanted. We had deposits in the wet end, plenty of holes, lots of breaks, lots of broke, lots of down time and a few customers who were putting up with us. Much of the trouble grew out of replacing No. 18 P.M. with a brand new machine (same width, higher speed) in late 1980. 1981 was one amazing year. Just about everything that could be a disaster was.
There was another motive for going alkaline. We knew that all the high quality coated paper producers--the ones we wanted to emulate--were already alkaline in their high grade lines. We wanted to be a copycat, we wanted Plainwell to be equal to the best, so being alkaline was a natural and necessary step.
The choices come down to this: Should we work very hard to fix up the alum-rosin approach and then, sometime later, go alkaline, or should we just go alkaline? I argued for the latter approach, and the front office backed me up. Why not? It could hardly have been worse.
Since we didn't have much staff, much money or very much time, we took the easy approach. As quickly as possible, and as simply as possible, the mill went alkaline. We did run some trials. We did involve the suppliers and we did keep everyone informed. But we did just go, and we did just stay, alkaline, regardless of what else happened.
The switch on No. 18 P.M. was preceded by three trials of increasing length. Each trial had a specific goal.
The first trial was in October 1981. It was intended to be a 24-hour trial on a specific grade--our premium No. 1 matte line called Kashmir. The trial plan called for a Monday morning startup. We were supposed to shut down about 6:00 in the morning, boil out the machine and clean out the chests, bring in fresh furnish with CaCO3 in it and start up on 146-lb. coated two side basis weight. We had experts in from all the critical suppliers--carbonate, sizing, retention and biological--for advice. Everything was in place. The only thing was, the machine lost a wire an Saturday. Since they were already down, the manufacturing people went ahead with the boilout. Then they ran ahead of schedule' So when I came in Monday morning at six, they were already making the order we were going to start up on. I knew I wouldn't get this opportunity again soon, so I decided to switch anyway. I really didn't know you can't do that.
We stopped feeding alum and rosin-size. We put soda ash in the chests to raise the pH. We started adding calcium carbonate. I stood on the slice walkway and watched. A technician kept me up to date on the pH. As the pH increased towards 7, the formation on the wire got worse and worse. It finally looked like someone was throwing handful's of stock on the wire. At about 7 pH things started to get better. The formation improved and the paper became saleable again. We never broke down, we made about l reels of broke (maybe 15,000 pounds), and then we settled into the new conditions like they were normal. Of course, we never told the customers or the Sales Department that we had made a switch on this order. The paper printed just fine.
The second trial was intended to show that alkaline paper is stronger than acid made paper. We had made the cover for a major annual report soon after the 1980 rebuild, which gave the printers a lot of problem with the sheet delaminating during a flying splice. We had to make the order again in December 1981, and I wanted to make a tougher sheet this time. Alkaline was supposed to take care of that. We ran three days on a 135 lb. coated two side supercalendered sheet. The system worked just fine and the paper was OK. The printing went very well also, a month or so later.
The final trial was run for 10 days starting on January 2, 1982. We had spent the Christmas-New year's week with the mill down for maintenance. We thoroughly cleaned No. 18 P.M.'s wet end system. We boiled out several times, took down almost all the major pipe lines and high pressure cleaned them, and we polished some of the welds.
On start-up, we ran lighter weight paper--60, 70 and 80 lb. coated grades--to prove that it could be done. We were particularly concerned about the biological situation and watched it carefully. We then went back acid, and ran for a week finishing some orders that had been started before Christmas.
On January 18, 1982, Plainwell made the change from an alum-rosin sized, pH 4.5 system to an AKD sized, pH 7.8 system in a permanent way on No. 18 P.M. The change on No. 16 P.M. followed in less than a month.
No. 16 P.M. was changed over because of one characteristic of alkaline CaCO3 -filled paper, that everyone should take into account, even if we didn't. When broke containing CaCO3 is reused in an acid system, foam results. In the case of our No. 16 P.M., I was warned by the Superintendent that if the foam in the basement reached the ceiling, he was going to go alkaline right then. I came in one morning to be greeted by his smiling face saying, "Well, the foam got to the ceiling!" Enough said.
During the changeover, we identified eight major goals that we would use for evaluating the process change. Here is the list:
It appears obvious that the only cost savings item that could be easily quantified was Item No. 3, using CaCO3 as a filler. We expected that this item alone would cover any cost increases we might encounter in other areas.
The economic data that are given in Table 1 should be looked on as an example, not as hard facts. There are many ways to disguise data, and some of them have been used here.
The cost savings can be calculated in several ways. The two most important ways involve answering these questions:
The data under "Actual Usage" in the table show the answer to Question No. 1. It appears to show that we are saving $1.6 million per year at our current production rate m No. 18 P.M. The pulp figures are the actual percentages we used in 1981 and 1987 in the entire mill. I do not believe the difference in the percentages has anything to do with being alkaline, but the fiber mix would be strongly affected by differences in grade mix.
The Total Cost Savings ($1.6 million) appears to be taken from the savings in titanium dioxide ($1.68 million). While it is true that we are using only half as much TiO2 per ton now as we did in 1981, being alkaline is only a small part of the reason. Control of usage is a much larger part.
The actual source of the savings Table 1 is found in the pulp area, where high cost bleached kraft was replaced by calcium carbonate.
The answer to Question No. 2 is more difficult. Since I couldn't really know how we would be making acid paper, I assumed that nearly everything we do now would be mirrored in the acid process. There are a few things--biological control, filler amount, defoamer, and sizing costs--that are specific to alkaline papermaking, so these were not equalized.
Table 1 also shows that with all but these few items equalized there is an overall savings of $632,000 per year at standard tonnage. Most of this is pulp savings, offset by increases in filler and sizing costs.
A review of the impact of alkaline papermaking on the use of the other components, excluding pulp and filler, is in order. A pitch control agent is the next item. We now use it regularly as an insurance against pitch problems. We used to use it only when we had problem. It probably is not a factor in the alkaline versus acid equation. Therefore, I equalized it out.
Biological control probably costs more in the alkaline mode then it would have in acid, but the system is more complex, and again it is hard to say. I left in a small difference. That seems to be the industry experience.
The retention aid program probably would have approximately equalized and is shown that way in the table.
The filler situation is self-explanatory. We can use more carbonate now than we could have used clay, even in an up-to-date acid system. The calcined product is a minor additive for one particular grade, which we did not make in 1981.
Titanium dioxide (TiO2) has been touched on. I can see no particular reason why our alkaline system would be more efficient at using TiO2 than a well-run acid system. Therefore I singly equalized it.
It probably takes a little more defoamer to run alkaline, although some people would not agree with that idea. Defoamer is used for more than just keeping the trays free of foam. In our case, defoamer helps control dandy roll spray. We appear to have more of a problem with this factor in the alkaline mode.
The sizing situation is also self-evident. Synthetic sizes cost more than natural ones. But you can't use rosin at pH 7.8 and you probably wouldn't use AKD at pH 4.5. So they can't be equalized.
Comparison of 1981 and 1987 Furnish Component Usage: Both Analysis Methods
|Actual Usage||Components Equalized|
|Percent Acid||Percent Alkaline||Cost Savings||Percent Acid||Percent Alkaline||Cost Savings|
|Pitch control agent||0||1||($166,693)||1||1||$0|
|Retention aid svgs||$152,228||($407)|
|Biological control program||($13,845)||($13,845)|
|Pulp weight, lb./ton||1645||1595||N/A||1714||1595||N/A|
|Total cost savings||$1,600,812||$632,123|
In the process of preparing this paper I reexamined the original goals. I have drawn the following conclusions:
1. Wet end chemistry is really much simpler. There is no need for pH control because the system is stabilized at 7.8 by the CaCO3 and almost always stays right there. There are apparently fewer water-based reactions going on in the wet end. Retention appears easier to obtain.
2. The system is cleaner. No hard alum-based deposits are being formed. The headbox has fewer strings and lumps forming in it. Boilouts are easier, under normal conditions. There is a reduced need for high pressure water cleaning.
3. We use as much CaCO3 filler as we can, consistent with sheet strength considerations. In the cost area, at least, more is better.
4. We have not been able to run a waterleaf (unsized) base sheet. We have to use an internal sizing agent (AKD) to get the paper through the size press. We ran two ASA trials, in the early days of being alkaline. Our conclusion was that AKD was the size we should use.
5. Retention is much greater than it was in the past. Normal first pass total retention values are above 90%. on all grades. It should be noted that there is a very real question about how much of this is a function of alkaline conditions. The mill is using a dual polymer system at the present time. This has been in place since December 1982.
6. The biological control system has not changed much from the one we used in the alum-rosin days. The basic slimicide is still the same. Costs are similar. We have never really lost control of the biological situation.
7. We are now able to use substantial amounts of CaCO3 in coatings. While using CaCO3 as a filler is the major cost reason for going alkaline, using CaCO3 in coatings is the major quality reason. This goal, by itself, would have made the switch practical and necessary, even if costs had gone up. The key point is that the competitors are all using substantial amounts of CaCO3 in their coatings.
8. It is not possible to tell whether being alkaline improves or harms the waste treatment situation. We started up major rebuilds in our waste treatment plant in 1981 and 1983 and the facility is so different now that comparisons are impossible. Certainly, alkaline conditions are ideal for some processes such as microorganism growth. But the lack of alum may actually decrease settling rates. As far as I am able to estimate, the difference between the two processes has no cost impact on the waste treatment plant.,
No discussion on the conversion process is complete without a mention of wire life. Ground limestone is an abrasive material. If handled improperly on the fourdrinier, it can cause extreme wire wear. However, one can hardly go alkaline without using CaCO3 in some form. The trick becomes learning how to manage the pigment. That is fundamentally a papermaking problem rather than a technical one.
In 1981, using alum-rosin size and filler clay, Plainwell averaged only 32 days per plastic forming fabric on No. 18 P.M. (excluding damaged wires). This was a poor and unacceptable figure and would have been greatly improved as time went by. Remember that this was a new, higher speed machine than we were used to running.
The first year of being alkaline saw an average wire life of 16 days! At current prices that reduction was worth about $900/day in wire costs, including downtime.
On Thanksgiving weekend, 1982, substantial changes were made on the table of No. 18 P.M. to reduce wear. Foil boxes were repositioned so that each was a multiple of nine inches from the next. Several new low-vacuum boxes were installed and several high-vacuum boxes were removed. The covers on the remaining vacuum boxes were changed from a ceramic material to a high density polyethylene material. The wire that was put on after these changes were made ran 92 days. The current average for otherwise not damaged wires is about 80 days.
Many mills would have given up when the wire life deteriorated so significantly. Plainwell did not give up, for two basic reasons. The first was that we had increased our filler loading in the coating base sheet from around 10%. to around 17%. At current prices, this is worth more than $4000/day. That made the $900/day wire costs well worth it. The second reason was that we knew we had to be alkaline in order to compete with the best quality coated free sheet makers, all of whom were alkaline already. We had no competitive choice.
The wire life comparison is given in Table 2. Although the data indicate that alkaline operation is more economical as far as wire life goes, we would expect much longer wire life in a well-operated alum-rosin system than we get in our alkaline system.
|1981 (acid)||1987 (alk.)|
|Average days per wire||32||90|
|Individual wire cost (1988)||$18,000||$29,000|
|Tons per wire||5,000||14,000|
|Wire cost per year||$200,000||$114,000|
Savings, 1987 over 1981
From Simpson-Plainwell's point of view, we can say that alkaline was not particularly difficult, because we had clear objectives and a simple plan to get there. We changed as little as we could and we adapted to the changing conditions as that became necessary.
We are not through with the process of change. We have a need to look at some of the alternates that, so far, we have not tried. There are a number of successful approaches being used in the industry that deserve our attention. we have a plan in place to look at a variety of these successful methods over the next year or two. Perhaps in the future I can compare being alkaline in 1987 to another year with even greater savings.