A jet pump injector was developed and successfully tested, thereby demonstrating the feasibility of a jet injector for introducing coarse coal into an operating slurry face haulage system. In phase I, a variety of injection concepts were evaluated, and the jet pump was identified as best, owing to its simplicity, compactness, and performance potential. In Phase IIa, subscale jet pump injector tests were conducted, and a computer model of a jet pump injector was developed whose performance predictions correlated well with subscale test results. In Phase IIb, various system configurations were defined for integrating a jet pump injector into a fully operational underground coarse slurry face haulage system, further highlighting the feasibility and practicality of such a system. In Phase III, a full-scale mobile haulage vehicle embodying a jet pump injector and coal sizing equipment was detail designed into a practical vehicle with attractive performance characteristics. More importantly, fully operational full-scale jet pump injector and feeder-breaker subassemblies were tested and proven successful in their ability to down-size coal to 3 inches in all three dimensions and to consistently provide slurry of 42% weight concentration at 6.4 T/min throughout under a wide range of operating conditions including zero to maximum feed rate within 5 s.