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

Table 10

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

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	500	53.1	350	92.7	0.89	0.73
2#	Coal	1100	90.3	500	100.8	0.91	0.79
3#	Coal	1300	113.6	700	140	0.91	0.80
4#	Coal	900	98.7	600	178.2	0.89	0.70
5#	Coal	800	76.2	400	159	0.90	0.60
6#	Coal	400	59.6	200	63.2	0.85	0.68
7#	Coal	220	32.6	100	39.8	0.85	0.60