Drying and reconstitution of subbituminous coal - CRADA 90-004. Final report

AMAX Coal Company (AMAX) has built a 200 tph, demonstration scale fluidized-bed drying process at their Belle Ayr Mine in Wyoming to dry the subbituminous coal of Wyodak seam from an average moisture content of 25-30 wt% to about 10 wt%. Currently, the dryer generates too many fines for proper transportation and handling. Though the raw coal is about 2-inch top size, about 80 wt% of the dryer product ends up finer than 28 mesh, and about 10 wt% of the dried coal is collected in the dryer bag house (minus 200 mesh). Paul Woessner, Director of Research and Development of AMAX, met with personnel from PETC Coal Preparation Division and expressed an interest in an investigation of the feasibility of applying the PETC`s humic acid binder to reconstitute the bag house fines from the dryer. This was an area in which PETC had been doing some research and had some expertise. As a result, AMAX and the U.S. Department of Energy`s Pittsburgh Energy Technology Center (PETC) signed a Cooperative Research and Development Agreement (CRADA, see appendix A) in June 1990 to produce, from fine subbituminous coal, economic low moisture reconstituted solid fuel forms that have suitable storage, handling, transportation, and combustion properties. PETC`s task in this agreement was to conduct broad, baseline studies in three areas: (1) to develop a humic acid binder from AMAX subbituminous coal using the PETC-developed Humic Acid Binder Process, (2) to reconstitute AMAX`s dried subbituminous coal fines from the bag house and the fluidized bed dryer product with humic acid binder, and (3) to produce low moisture, water-resistant pellets from raw subbituminous coal by the PETC-developed Lignipel Process. AMAX, on the other hand, agreed to produce 1-2 tons of reconstituted solid fuel for handleability and combustion tests and partially funded PETC`s efforts