Volume 1, Number 2
Mar 1988

Alkaline Papermaking Conference, Kalamazoo

The 32nd Annual Pulp and Paper Conference took place March 16 and 17 in Kalamazoo, sponsored by the Michigan Division of PIMA, the Kalamazoo Valley TAPPI and the Western Michigan University Department of Paper and Printing, Science and Engineering. Over 150 people attended, not counting the speakers or the faculty and students from the University. There was a pre-conference tour through the Simpson-Plainwell mill nearby, which converted to alkaline papermaking on January 18, 1982. (Until December 1987, when it was acquired by Simpson, it was the Plainwell Paper Co.)

Thirteen papers that day and the next covered sizing, wet end operations, forming fabrics, retention aids, precipitated and ground calcium carbonate, and other topics. Only a few of the points brought out by the speakers or by participants in the question periods afterwards will be summarized here.

Conversion to Alkaline Papermaking

The main attraction of alkaline papermaking is the opportunity to save money by substituting filler for fiber. Calcium carbonate, unlike clay, allows the production of a stronger sheet with good opacity and brightness. The numerous advantages of alkaline papermaking listed by several of the speakers included that of permanence, but this was not a major incentive. There are disadvantages too, but they are not experienced uniformly, and those present agreed that they are outweighed by the advantages.

Savings are substantial for the mill. One mill cited savings of over $600,000 a year; figures around $40 a ton are given in the literature. But it is hard to give a meaningful average, since each mill's experience is unique.

The conversion process itself is more complex than one might think. Normally the production problem are worked out in a series of trials (trial runs) with the aid of a consultant from one or more suppliers. This used to take longer than it does now, and used to be less certain of success. (Someone mentioned a company that had made four separate efforts to convert.) But this is only part of the picture. Since everyone in the mill is involved or affected somehow by the conversion, and may be needed as a problem-solver under the new conditions, it pays to train the machine crews and involve them in planning. The first paper, by Donald Pryor, was a case history of how Consolidated had done this in 1968 when they set up their Alkaline Papermaking Task Force and made a major commitment to going alum-free." The involvement in planning was widespread, with committees on all the major aspects that would be affected by the change, to anticipate problems and be ready with solutions. There was a post-conversion evaluation of the system, which ran smoothly. The process they followed strongly resembled the Preservation Planning Program used by American research libraries to facilitate setting up a preservation program. The resemblance is not coincidental: in both settings a major and (if successful) pervasive alteration in an organization's operations is facilitated by the use of good management techniques.

The customers and sales force may or may not be told about the conversion. Probably it is better if they are not told right away. One company planned to convert on a certain date, and notified its customers and salespeople; but something came up and they had to postpone conversion for a month. During that month, customers who had not heard about the postponement called and complained that they couldn't print an the stuff they were getting. It was all in their mind.

Use of Alum in Alkaline Papermaking

Although mixing alum-rosin-sized and alkaline paper in broke (scraps recycled within the plant) is hard because so much foam is generated, alum is used by a number of papermakers at a level of around 1-4 lbs./ton for the following reasons (though not everyone agreed on every reason):

• to help first pass retention of fines and fillers
• to improve drainage
• to minimize deposits
• to control size hydrolysis and tackiness

One speaker recommended not adding it too early, but putting it in the white water loop.

The Big Picture

One of the speakers, Jim Matters of Pfizer, said that over the next few years he expected 48% of free sheets to be alkaline. He knows of 12 companies that will go alkaline in the next 10 years.

In Europe, whiting and ground limestone (which are form of calcium carbonate) are cheap, and clay is expensive, so they use a lot of carbonate (30% of total filler in 1984); in the U.S., much less (5% of the total). But it is in demand here, and companies are building their own plants to make precipitated calcium carbonate at the mill site. There are at least five now in operation.

Calcium Carbonate

Some papermakers complain of its abrasiveness, which can dramatically shorten the life of wires (paperforming fabrics) and guillotine blades; but several speakers said that the wear problem can be avoided by using ultrafine ground limestone (UFGL) or precipitated calcium carbonate (PCC) instead of fine ground limestone, as long as the particles are retained in the web instead of draining through, and if certain adjustments are made in the table (suction boxes under the forming fabric) to minimize friction at the dry end.

Calcium carbonate doesn't make a weaker sheet; with alkaline refining, the fibers swell more and grow softer, enhancing bonding and giving a much stronger sheet.

Companies Making Alkaline or Neutral Paper

The companies that make only alkaline paper are marked with an asterisk (*). Any of their papers may be ordered without checking to make sure they are alkaline. With the other companies, however, it is necessary to specify the brand name, or even to test the pH of the paper before buying (mill, Nekoosa, Newton Falls). Remember that the picture changes all the time.

Paper may be sold either through local distributors or the company's sales offices, or both; call the company to learn the name of the nearest outlet.

This list does not include papers made by foreign companies; alkaline papers not used in publishing or office work; or private brands (papers made to order for a distributor or retailer). Apologies are offered for any errors in the list. All efforts will be made to eliminate them in future printings. Corrections and additions are welcome.