Bolting manual pillar and room method is a good future method of mining Mn ore body of medium thickness and small pitch.
人工柱锚杆房柱法是一种有前途的开采中厚缓倾斜锰矿床的采矿方法。
2
The formula presented in Tom 3 of "Mining Design Manual" is for approximate calculation, the area value determined from which is some less than that obtained from the formula given here.