Technical and economic analysis on control method of hard top coal roof in mine

The hard top plate (coal) of coal face can not collapse in time, which leads to a series of problems such as surrounding rock control and safety assurance.The traditional method of dealing with hard roof (coal) is explosive blasting.In recent years, new methods of hard roof (coal) control such as hydraulic fracturing, fracturing by CO₂ phase transition, and static expansion agent has been studied and explored.In this paper, from the viewpoint of energy control, according to whether the rock-breaking energy is alterable in the fixed borehole, dynamite blasting, fracturing by CO₂ phase transition and static expansion agent are classified as rock-breaking methods with fixed energy, and hydraulic fracturing is classified as rock-breaking method with variable energy.Comparing those roof (coal) control methods in terms of the range of control and economic cost, it is concluded that hydraulic fracturing is superior to dynamite blasting, and dynamite blasting is superior to fracturing by CO₂ phase transition.Hydraulic fracturing has obvious advantages in many aspects, such as safety, single hole action range, construction convenience and economy.Hydraulic fracturing control technology is the future development direction for mining hard roof(coal).