The deep cleaning processes now under investigation forcoal most often involve pulverizing and the use of a liquid processmedium. If the very fine deep cleaned coal is to be used in a dryform, a satisfactory drying technology is vital. Previous studieshave indicated a substantial probability of success if theultrahigh levels of centrifuge gravity are combined with thecentrifugal decanting/filtration process developed earlier. Newmethods have been developed for operating centrifuges, combiningdecanting and filtration at high levels of gravity and withoutblinding the filters. The new batch technology incorporatescomposites for the bowl and an ultraefficient variable frequency ACdrive so that the energy consumption is held to low levels. Theprocess involves no detrimental environmental impact. Bowl stress,vibration dynamics, and filter process technologies have beendeveloped and patented; the limits of their capabilities have notyet been explored. Phase I comprises an in-depth study of gravitylevels required for drying ultrafine deep cleaned coal to about 10to 12% surface moisture. By using existing hardware, in-housedeveloped software, and appropriate consultations, determination ofthe limitations within which the advanced centrifuges can bedesigned will be made. The work in Phase I is being supplementedby drawing on an extensive database developed during previousin-house centrifugal dryer research and development, which hasyielded a successful prototype centrifugal dryer for conventionalfroth flotation products.Anticipated Results/Potential Commercial Applications as described by the awardee:Phase I will produce data and calculationsconcerning the feasibility and limitations of the apparatus andprocess of the high gravity, deep bed centrifugal filter system. It will also yield specifications for an intermediate-sizeprototype centrifuge for Phase II. A further result will be theprojection of the optimum specifications for a commercialultracentrifuge to dry the output from the deep cleaning processes.
