Dust Concentration Changing Regularities and Dust Reduction Technology by Spray Negative Pressure in Fully Mechanized Mining Face

Table 11

Dust concentration and dust fall rate before and after opening of devices.

No.	Dustiness	Total dust concentration (mg/m^3)		Exhaled dust concentration (mg/m^3)		Total dust fall rate	Exhalation rate
		Before opening	After	Before opening	After
1#	Coal	360	22.8	160	35.6	0.93	0.77
2#	Coal	500	30.1	200	60.1	0.93	0.70
3#	Coal	480	32.8	210	51.3	0.93	0.75
4#	Coal	400	38.7	190	44.3	0.90	0.76
5#	Coal	320	20.1	180	36.8	0.93	0.79
6#	Coal	200	19.7	130	26.9	0.90	0.79
7#	Coal	130	12.1	80	17.6	0.91	0.78