Wood-based lignosulfonate versus synthetic polycarboxylate in concrete admixture systems: The perspective of a traditional pulping by-product competing with an oil-based substitute in a business-to-business market in central Europe

Forest Products Journal, Jan/Feb 2008 by Stern, Tobias, Schwarzbauer, Peter

Abstract

A primary data survey was conducted to evaluate the market potential of lignosulfonate as a raw material for plasticizers in the concrete industries of Austria and southern Germany (Bavaria). The results showed significant differences between the countries. Since 2002 lignosulfonate-based products have been massively displaced from Austrian markets. This development was found to be a consequence of new mandatory standards for the construction industry, technical advantages of new polycarboxylate-based products, and the market power of their producers. It was determined that especially smaller concrete companies, which use only one plasticizer or superplasticizer product, have been much harder hit by these changes than bigger companies. Larger companies in Austria and southern Germany (with an annual plasticizer consumption of more than 250 t) tend to use both product types (lignosulfonate-based and polycarboxylate-based) to improve their cost efficiency. In total, the consumption of lignosulfonate-based products within a stagnating or declining market shows a downward trend. Because of the polycarboxylate-based products' higher efficiency, a price ratio in relation to the lignosulfonate-based products of 2.5 to 1 is required to ensure the competitiveness of the latter products. Plasticizer price changes of about 14 percent have been found to be a sensible range to enable the concrete industry to take a possible product change into account.

The Austrian Kompetenzzentrum Holz-Wood K plus (Competence Center for Wood Composites and Wood Chemistry) focuses on industrially oriented technical research and development. The technical research conducted by the center is supported by a market research team, which ensures that the newly developed products and processes meet market demands and requirements.

The content of lignins in wood is between 15 and 35 percent, therefore lignins are indeed one of the most abundant renewable organic materials on the Earth (Fengel and Wegener 1984). In the chemical pulping process, celluloses are removed from the wood chemicals complex. The spent liquor consists of remaining hemicelluloses and lignins. Pulp industries use this spent liquor to extract marketable by-products for the improvement of material recovery, as well as for their profitability. One of the most traditional by-products of the sulfite pulping process is lignosulfonate. Depending on the pulping process and the raw material used, 1 metric tonne (t) of pulp produces between 330 and 540 kg of lignosulfonate (Sj�str�m 1993). Although various applications for lignosulfonate exist, a large proportion of lignosulfonate is just burned (as fuel) for the production of energy.

According to Will and Yokose (2005), the annual global production capacity of lignosulfonates is approximately 1.8 million t. Another estimation made by Gargulak and Lebo (2000) anticipates an annual production capacity of about 1 million solid t, excluding producers from former Soviet Union states. Carves et al. (1997) published several figures applying to the market for lignosulfonate. According to them, the sales volumes in the United States and Western Europe were about 1 million t annually in 1994. They also cited the European production capacity as 500,0001 in 1995 with sales of 310,000 in the same year. Gargulak and Lebo (2000) estimated the total revenue from the use of lignin material to be at US$600 million in 1996, whereas Will and Yokose (2005) estimated the 2004 world production value to be between US$490 and 550 million.

Around 66 percent of the accruing lignosulfonate is used as fuel for the production of energy during the pulping process, generating an average fuel value of 23.4 Mj/kg (Busch et al. 2006, Ringena 2006). Modern pulp plants using energy efficient processes can produce an energy surplus using this process, which can be fed into the power grid.

The goal of finding alternative lignin applications has always been driven by the aim of producing added values and improving the raw material recovery rate. The utilization of lignosulfonate as a raw material for the production of chemicals has only had limited success in the past. The conversion of lignosulfonate to vanillin was the first and most successful process of this kind to present. In 1874 Haarmann found that lignin from spruce bark sap can be used to manufacture vanillin (Krammer et al. 2006). Today lignosulfonate derived from wood during the pulping process is one source for the commercial production of vanillin, which is used as a flavoring agent in food and other industries (Lewis 1989, Priefert et al. 2001). The vanillin manufactured by this process is the same chemical substance that creates the vanilla aroma of original vanilla beans. The introduction of this process was the prerequisite for introducing vanilla aroma as a bulk ingredient in the food industries (B�tehorn and Pyell 1996). However, in comparison to the amount of lignosulfonate produced by the pulping industry, the market for vanilla flavor is far too small (Hocking 1997).