Experiment study on raw coal sample preparation and permeability of structure coal

In order to study the permeability variation law of the raw coal sample from the structure coal and the difference to the briquette coal sample, with the CO al sample preparation method improved, a method to pick up large lump coal from the underground mine and to process the briquette in the lab was applied to successf ully prepare the raw coal sample of the structure coal with a Protodyakonov coefficient of 0.4 and the raw coal sample of the structure coal prepared was applied to the permeability experiment. Under the changed confining pressure, gas pressure and other single condition, a study was conducted on the different confining pressure and gas pressure affected to the raw coal sample permeability of the structure coal. A comparison analysis was conducted between the experiment results and the briquette coal samples under the same confining pressure and the gas pressure. The results showed that under the certain gas pressure status, the gas permeability of the two ki nd coal samples would be decreased with the confining pressure increased and the decreasing speed of the briquette permeability was higher than the raw coal sample of the structure coal. Under the condition of the certain confining pressure, when the scope of the gas pressure was 0.2 ~ 0.8 MPa, with the influence of the Klinkenberg effect, the gas permeability of the raw coal sample of the structure coal and the coal sample of the briquette would be reduced with the gas pressure increased. The per meability variation law of the briquette coal sample and the coal sample of the briquette would have the same point, but also would have the different point and the raw coal sample of the structure coal could not be fully replaced in the lab.