The overall objective of this investigation was to determine the basic principles and mechanisms which underlie selective oil agglomeration processes for beneficiating fine-size coal. The investigation focussed on the following key areas: (I) the relationship between particle recovery and various system parameters, (2) the separation of coal and pyrite, and (3) rate of agglomeration. Special laboratory equipment and experimental techniques were developed for studying particle agglomeration, including a method for continuously monitoring the progress of agglomeration in a batch mixing system by measuring the turbidity of the particle suspension. This method provided an indication of the rate of " agglomeration. Since particle agglomeration depends on particle surface properties, ,. several methods for measuring such properties were evaluated and found to yield " comparable results. Numerous agglomeration tests were conducted with several types of low-ash coal and graphite, high grade mineral pyrite, and other materials. Relatively pure hydrocarbons, including heptane and hexadecane, were used as agglomerants. Access of air to the system was controlled. Particle recovery by agglomeration was observed to depend on a m FURTHER CONSIDERATION OF SURFACE PROPERTIES