Improvement and application of spraying dust control method for hydraulic powered support in high cutting fully-mechanized coal mining face

According to a serious dust pollution problem of the high cutting fully-mechanized coal mining face, based on the spraying features experiment of a PDI2 00MD phase Doppler laser interferometer, macro spraying features of six sparing dust control conventional nozzles with a 8 MPa spraying pressure were individually m easured and the distribution of the spaying particle sizes were measured under the disturbance air flow of 1.2 m/s. According to the experiment results, a Venturi negati ve-pressure sprayer and a new spraying dust control method of the hydraulic powered support were designed and finally the site dust concentration measurements wer e applied to investigate the application effect. The results showed that the mixed type wide angle solid cone nozzle with X type diversion core and with a pore diameter of 2.2 mm would be best in the spraying features. Under the jet pressure of 8 MPa, the spraying angle would be 73.5°, the effective range would be 5.3 m and the flow would be 7.05 L/min. Under the influences of the 1.2 m/s disturbance air flow, the feature partical size Do 5, Sauter average partical size D32 and Herdan average partic al size D43 would be 38.541, 33.951 and 41.162 μm individually. The axial velocity of the droplet would be 26.415 ~ 57.468 m/s. After the application of the new type sp raying dust contral method to the hydraulic powered support, a total dust and respirable dust concentration at the sampling points of the coal mining face would be obvi ously reduced than the conventional spraying dust contral method, the dust contral rate of the total dust was 86.4% and the dust control rate of the average respirable d ust concentration was 82.5%.