New gas blaster wz Air energy flexible cracking tube

1 Technical Principles

       Utilizing the performance of liquid oxygen's "combustion support+phase change", oxygen is used to assist in the rapid and intense combustion of combustible media, generating high temperatures in the blast hole, causing other liquid oxygen that has not participated in combustion to undergo phase change (from liquid to gas), generating a large amount of gas to expand and work, causing rock fragmentation. The detailed description is as follows:

1) Put the cracker (the composition structure is attached) into the blast hole and block the blast hole, then fill the liquid oxygen into the cracker in the blast hole through the "intelligent filling machine", ignite it with a resistance wire (the vaporization temperature can reach 600 ℃), so that the combustible medium burns. Under the combustion support of liquid oxygen, the combustible medium burns violently, and the hot spots spread rapidly, so that the combustible medium in the cracker will explode instantaneously, The heat generated by combustion causes other liquid oxygen that is not involved in combustion to undergo an instantaneous phase transition, changing from a liquid state to a gaseous state. The gas volume expands more than 800 times (theoretically), generating a certain amount of high-pressure stress in the blast hole.

2) High pressure gas acts on the wall of the blast hole, generating tensile stress in the rock mass, causing a large number of cracks. Subsequently, the high pressure gas enters the cracks and produces a "gas wedge" effect, causing the rock mass to further fracture. Finally, under the action of residual gas, the fractured rock moves forward to form a bulge. As the bulge ruptures, the gas pressure quickly decreases to zero, and the rock loses its kinetic energy of motion and falls freely, so it does not fly far.

3) On site testing shows that:

(1) After the combustion of "combustible medium+oxygen", CO2 and H2O are generated and returned to nature, without producing toxic gases. Therefore, the method of air gas expansion rock breaking is a green and environmentally friendly rock breaking method.

(2) After placing the cracker in air and filling it with liquid oxygen for ignition, the cracker only burns without phase change, and there is no public safety risk.

(3) After placing the cracker in the borehole for ignition, no air shock wave can be detected, resulting in low vibration and noise.

2 Equipment and equipment

2.1 Composition

The air expansion rock breaking equipment mainly consists of three major components: a Dewar can, an intelligent filling machine, and a fracturing device, as shown in Figure 1. Dewar tanks are used for transportation and on-site storage of liquid oxygen, provided by professional manufacturers and in compliance with relevant national standards. The intelligent filling machine is a patented product developed by the company, which can automatically adjust the amount of liquid oxygen filled into the cracker according to the design scheme, achieving precise filling.

（1）Intelligent filling machine

(2) Dewar jar

(3)Air Engergy Flexible cracking tuble 

 Figure 1 Composition of Main Equipment for Air Expansion and Rock Breaking

2.2 Composition of Air Engergy Flexible cracking tuble 

The Air Engergy Flexible cracking tuble is a combination device, and Figure 2 shows the structural schematic diagram of the flexible cracker. The cracker mainly consists of a plastic outer tube, a combustible medium, a liquid filling tube, an exhaust pipe, and an ignition head. The flexible outer tube is mainly used to store combustible media and liquid oxygen, and must have a certain degree of toughness and strength. After the liquid oxygen is filled, it cannot leak. The filling pipe is a regular aluminum pipe, while the exhaust pipe is a plastic pipe. The ignition head is a resistance wire, which is melted by an electric current and generates sparks, igniting the combustible medium in the cracker. The combustible medium burns under the combustion support of oxygen.

Figure 2 Structural schematic diagram of flexible cracker

1- Outer casing pipe, 2- Liquid filling pipe, 3- Exhaust pipe,

4- Ignition head, 5- Combustible medium

2.3 Rock breaking operation process

(1) Assemble the cracker. Firstly, fix the combustible medium on the liquid filling pipe and install it together into a flexible plastic pipe. While installing, fix the resistance wire in a suitable position, and finally insert the exhaust pipe to seal both ends of the plastic outer pipe to ensure that liquid oxygen does not leak.

(2) Place the cracker. Place the cracker into the blast hole, fix the inflation pipe, exhaust pipe, and ignition pin wire and expose them outside the blast hole. Block the blast hole with gunmud, and Figure 3 shows the cross-sectional view of the blast hole structure where the cracker is placed.

(3) Fill with liquid oxygen. Connect the intelligent filling machine to the Dewar tank and the filling pipe respectively, and charge liquid oxygen into the cracker.

(4) Connect to the network. After filling with liquid oxygen, connect the ignition network and conduct a conductivity check with an ohmmeter to ensure that the ignition network is smooth and the resistance value meets the design requirements.

(5) Safety alert. Based on the amount of liquid oxygen filled and the desired rock breaking effect, determine the safety warning distance and arrange warning posts, with a warning distance of generally 30-40 meters.

(6) Implement ignition. After checking the warning situation and confirming safety, issue the ignition command.

Figure 3: Sectional view of the borehole structure with the cracker installed

3 Safety testing

According to the "Test Report on the Harmful Effects of Air Energy Gas Expansion on Rock Breaking" issued by Nanjing Junyuan Science and Technology Co., Ltd., the safety of air energy gas expansion rock breaking technology can be evaluated and affirmed as follows:  

(1) All equipment and materials are free of civilian explosives and explosive materials, which will not endanger public safety;

(2) Using the hole filling technology (invention patent) to inject oxygen, on-site operators do not come into contact with oxygen, ensuring safe operation;

(3) There is no link of transportation, storage and operation of civil explosives (explosive materials), which greatly improves the Intrinsic safety level of blasting operation;

(4) There is no explosive shock wave, therefore, the distance between the flying rocks during blasting is controllable;

(5) The blasting vibration is small, generally 1/10 of the same amount of explosive blasting at a distance of 30 meters;

(6) Low blasting noise and no disturbance to residents;

(7) If it can be promoted and applied, it can also reduce the risk of responsibility for the safety supervision of civil explosives by public security organs.

New gas blaster wz Air energy flexible cracking tube Test Report