Volume 05, Number 3
Jul 1992

Recent News on Chlorine-Free Bleaching

The General Services Administration, the U.S. government s purchasing agent for paper, among other things, is talking about modifying its specifications to exclude products bl6'ached with chlorine, chlorine dioxide, or hypochlorite, according to that same Pulp & Paper issue for May.

A book on the supply and demand for chlorine-free papers in Europe in 1991, 1992 and 1995 has been published by Papis Ltd. in London (Fax: 081/543-9032). Title: Chlorine Free Papers.

A report of the non-chlorine bleaching seminar at Hilton Head Island in March, sponsored by Pulp & Paper and Emerging Technology Transfer Inc., appeared in Pulp & Paper Canada, v.93 #5 (1992). Finnish, Swedish, New Zealand and Japanese mills reported that they are lowering their discharge of adsorbable organic halides (AOX) even below what regulations can for (usually 1.5-2.5 kg/ton for AOX and no "quantifiable" discharges for 2,3,7,8 TCDD), because of market demands. The American Paper Institute, however, along with International Paper and Georgia Pacific, have drawn the line at further reducing AOX discharges.

Terminology is typically loose in the paper industry, so there was a discussion on what was meant by "chlorine free." Some people, especially sales types, used the term broadly to describe paper produced without chlorine or chlorine derivatives, while others used it to mean paper produced without the chlorine gas. To be exact, the first can be referred to as "totally chlorine free" (TCF), and the second as molecular chlorine free or chlorine gas free (CGF).

Concerning the environmental significance of AOX, there was little discussion of the facts of the case; delegates seemed to feel, this report says, "that public perception has overridden science on the question."

In the future, many speakers and delegates saw the possibility of closed-cycle kraft mills, after a way to control transition metals is found. This would be something that would help mills selling to Germany and other environmentally aware markets.

Several ways have been found to compensate for the loss of chlorine as a bleaching agent. Extended cooking has been added after the pulping sequence and before the bleaching sequence in 31 mills, with 15 more planning to add it. This calls for the installation of new equipment. Enzyme bleaching is coming into use, to reduce the need for other bleaching agents. (Much of the research on this approach has been done by the USDA Forest Products Lab in Madison, through a biopulping consortium formed five years ago, which has proven so successful that participants are being invited for a follow-up consortium for the next five years.) There was a discussion at the conference on the possibility that enzymes might be perceived as hazardous by a hypersensitive public, despite the fact that enzymes are also used in food processing. Oxygen is widely used for the extraction stages (the equivalent of rinse cycles) in bleaching in Japan, Sweden and Australia, and is coming into use in Canada and the U.S. Equipment was first installed for this purpose in South Africa in 1970. An oxygen delignification system costing $31.5 million is being built by Pope & Talbot in Halsey, Oregon; eventually the mill there will become totally chlorine-free. "Lignox" and similar processes use chelating agents with large amounts of hydrogen peroxide, sometimes sequenced with oxygen and /or ozone. Ozone bleaching is being developed in Canada, France, Austria and Germany. The first use of this method will be at Union Camp's Franklin, Virginia, mill later this year. (Ozone is also replacing chlorine as a disinfectant in municipal water treatment systems, by the way.)

The non-chlorine bleaching conference described may be the one lampooned in a letter in Pulp & Paper for May. It humorously expresses what must be the reactions of many people in the U.S. pulp and paper industry.