C. Water sprays [16]: Water sprays are the most common methods for dust control. They are installed to suppress dust at all major sources including cutting, loading, transporting and support advancing. The basic principle of dust suppression [17] by water sprays is that the high-velocity water droplets [18] in the mist that are ejected [19] from a nozzle [20] impact and wet the surface of the airborne dust particles, thereby capturing them to become the settled dust.

D. Air scrubbers [21] for intake [22]: To reduce the airborne dust concentration in intake, water sprays should be installed at each transfer point of coal transportation. At these locations, an air scrubber is usually employed in conjunction with the water sprays. A new water-powered scrubber [23] in which the air is moved and cleaned by the water sprays without the need for an electric or hydraulic motor is installed at the stage loader and can reduce by 50% the dust level.

E. Water infusion: Water infusion tends to wet the coal before it is broken by the cutting machine. Therefore, water infusion is not only effective for methane control, it also reduce the airborne dust generation. Tests have proven that it can reduce airborne dust by 69- 79%.

NOTES TO THE TEXT

[1] Dust Control������������

[2] airborne dust��������������

[3] settle dust������Ŀ�

[4] heath hazard����������

[5] inhale�� ����

[6] bronchial disorders��֧���ܲ���

[7] pneumoconiosis�����β�

[8] silicosis����β�

[9] degradation������

[10] visual inspection���Ӿ����

[11] dust explosion��ú����ը

[12] transfer points��ת�ص�

[13] coal lumps��ú��

[14] dilute��ϡ�ͣ��嵭

[15] air leakages��©��������й©

[16] Water spray����ˮ����ˮ

[17] dust suppression���ֳ�������

[18] water droplets��ˮ��

[19] eject������

[20] nozzle������

[21] Air scrubbers������ϴ����

[22] intake���������

[23] water-powered scrubber��ˮ������ϴ����

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