Utilization of residuals from flue gas desulfurization

Abstract

Vioerse large-scale ,sources of FGV gypsum, the plentijiul wuste by-product from SO2 emissions cleanup in mujor industrial countries, are charucteriwd in tenns of properties including crystal form and contained impurities that affect commercial usability. New technology to expand FGD gypsum usage by economical conoersion to alphu hemih ydrute of culcium suljiute is cktuiled. INTRODUCTtON W d w i d o FGD Gypaum ProductionAs a result of a major program hegun in 1983 for control of SOz emission from coal-fired boilers in West Germany, The Netherlands, and other European countries, by-product gypsum from flue gas desulfurization (FGD) is likely to become a major new resource. This commercial development closely parallels the typical method of management of FGD residuals in japan where extensive SOz control activity since the early 1970s has become the basis for major FGD gypsum supply in that wuntry. Japan, like Europe, lacks ample land s p a c e for discarding of air pollution control residuals and thus FGD system design in these two highly industrialized areas has become strongly oriented to generation of usable sulfurous byproducts. At the same time this approach avoids converting the original air pollution problem into a solid waste environmental problem. This contrasts sharply with practice in U.S.A. where, due to abundance of spacv for land disposal, F G D system installations generally yield a throwaway solid waste. Since many areas of the European continent, includingThe Netherlands, lack deposits of natural gypsum, the future availability of a new, highquality synthetic source of this raw material is seen as a major benefit for the growth of the gypsum industry there. However, there has been a prior history of difficulty in commercially using by-product gypsum from phosphoric acid production by the fertilizer industry, tied to impurities in this waste product.Thus, in view of a diversity of gypsum-producing F G D processes being installed in Europe by six major system suppliers, there is substantial concern about the usability of each of the new F G D gypsum sources. Moreover, detailed assessments to date indicate that usable F G D gypsum may b e expected to completely supplant natural gypsum usage in most or all of Western Europe, including use as feedstock in manufacture of gypsum wallboard, a major market in many areas of Western Europe. Accordingly, questions about quality of future F G D gypsum supplies have become of critical importance. OVERVIEW OF FGD GYPSUM STUDIES IN THf NETHERLANDSThis paper presents general results of current tests and evaluations being carried out for the government of The Netherlands to characterize individual F G D gypsum stocks from processes of greatest significance in that cwuntry. Samples and trial shipments are being taken from representative, existing, commercial-scale sources in the U.S.A. and Europe to pennit assessment of use o f gypsurn from chew processes in major large-scale gypsumconsuming activities. T h e Netherlands study is; investigating the size of available...