Indices for coal desulfurization and de-ashing processes

Coal upgrading processes are evaluated based on performance indices. Adequate definitions of these indices are very important because the process operating parameters are adjusted by a control system according to the required values of the indices. This paper discusses the following performance indices for physical processes of coal desulfurization and demineralization: coal matter recovery, total sulfur rejection, ash rejection, inorganic sulfur rejection, unit index of sulfur rejection, unit index of ash rejection, joint unit index of sulfur and ash rejection, and overall index of coal upgrading. The deficiences of the existing definitions of these indices are pointed out and new, more adequate indices are proposed. The advantages of the proposed indices are demonstrated by applying them to the assessment of selective agglomeration of coal, using the extensive experimental database for this process. Copyright (C) 1996 Elsevier Science Ltd.