## 3 Application
### Application of Foam Dust Reduction in Jinjia Coal Mine  
The foam system for dust control was applied in the 11,181 fully mechanized mining working faces of the Jinjia coal mine. The detecting devices, which were also used to collect the density of mine dust, were installed at the ventilation corner and 5 m and 10 m from the ventilation corner. The average density of the total mine dust and respirable mine dust is presented in Figures 11 and 12.  
Figure 10: Comparing the efficiency of containing falling dust in the ventilation area (within 5 m).  
Figure 9: Comparing the efficiency of containing falling dust around the roadheader driver.  
According to Figures 11 and 12, the average density of the total mine dust decreased by 22.75-32.95% using foam technology and by 67.30-84.85% using water spray. Similarly, for respiratory mine dust, dust density decreased by 20.07-29.53% using foam technology and by 38.96-69.79% for water spray. It is not hard to noticed that the foam technology for dust control can effectively reduce the mine dust in the practical application of fully mechanized mining working faces.  
11,225 excavating ventilation roadways  
When the foam system for dust control was applied in the excavation working face of 11,225 ventilation roadways, the devices for detecting the density of mine dust were installed around the roadheader driver and 10 to 20 m from the ventilation side of the roadheader driver. The facility was instructed to independently measure the average density of total mine dust and respirable mine dust, and the measured data are shown in Figures 13 and 14.  
Figure 11: Average density of total mine dust in fully mechanized mining working.  
Figure 12: Average density of respirable mine dust in fully mechanized mining working faces.  
According to Figures 13 and 14, with the foam technology for dust control, the efficiency of decreasing total mine dust and respirable mine dust reached 95.33% and 94.76%, respectively, around the roadheader driver, 76.28% and 61.33% in the ventilation area within 10 m of the roadheader driver, and 89.29% and 92.18% in the ventilation area within 20 m of the roadheader driver. The average density of total mine dust and respiratory mine dust was 4.67-23.72%, comparing with5.24-38.67% in the event of \"no measures\", respectively.  
According to the tests, the foam technology for dust control has been proven to be effective in reducing the density of total mine dust and respirable mine dust in the practical application of mining and excavation working faces. Currently, the majority of the mine dust generated at the moment of coal rock breaking is brought out with the rotation direction of the cutting drum. With the foam, the dust source that may diffuse outward is strictly covered. As a result, the mine dust is effectively suppressed in the initial stage of diffusion. The tests also reveal that an effective dust suppression demands the foam sprayed on the dust producing point or the dust producing area before the mine dust becomes airborne. Despite the effectiveness of the foam dust reduction technology, this technology is limited due to the high cost. Therefore, the further research needs to focus on cost reduction and efficiency enhancement, providing possibilities in mine dust control for more coal mines.