Application of a Hydraulic Borehole Mining Apparatus to the Remote Extraction of Coal: Field Test of Borehole Crusher System. Final Technical Report, 18 September 1979-28 November 1980

摘要

Extensive factory and field testing of the hydraulic borehole coal mining tool was performed. The tests: (1) characterized cutting nozzle and crusher wear and reliability; (2) characterized cutting, cavity slurry flow, crushing, and slurry pumping processes under field conditions; and (3) compared laboratory cutting and pumping rates with those obtained in the field. The cutting nozzle wear test indicated a nozzle operating life span of at least 400 hours. The crusher reliability test demonstrated that the present crusher drive shifter mechanism can operate up to 8 hours without adjustment; the crusher wear test indicated that the shift mechanism and linkages can operate 100 hours between periods of maintenance. Field production tests demonstrated a cutting rate of 100 tph at 500 hhp. Coal particles averaging 1 inch in size were produced, although some fragments were up to 18 x 18 x 7 inches in size. It was necessary to break up the larger pieces with the cutting jet before they would flow into the sump. This, of course, reduced the average cutting rate. The transport subsystem demonstrated an average rate of 14 tph for crushing and pumping coal from the sump when the working face was more than 10 feet from the sump. The average particle raised to the surface via the slurry jet pump was 1/4 inch in size; the maximum size was 2 inches. The cutting nozzle and jet pump were shown to be reliable and possesedof good operating life spans while the crusher proved to be the least reliable system component. The production tests demonstrated good cutting rates but indicate the need to increase crushing and pumping capability in order to provide for subsystem compatibilty. It is concluded that design changes will be needed to effect improvements in crusher reliability. It is recommended that a commercial borehole coal mining system be developed and production tested. (ERA citation 07:001726)