New CO₂ Rock Breaking System

Composition of a new gas blasting system

The new air gas blasting system is mainly composed of special plastic film, special paper roll, electric ignition head , liquid oxygen (including a small amount of liquid nitrogen), air hose (2), Dewar tank (below 499l), intelligent filling machine, etc., as shown in the figure below.

Intelligent filling machine, Horizontal 500KG Dewar tank

100KG Vertical Dewar tank

Plastic film

Special electric ignition head

Paper Roll

plastic air hose

Stainless steel air hose

Sandvik drill rig drilling hole 90mm hole for Gas blaster \'s gas tube inserting

Gas blaster working in Saudi granite quarry

Saudi quarry staff speaking gas blaster rock demoltion effect

Field operation of gas expansion rock breaking

1. Put the special roll of paper in the special plastic film, insert two air ducts and electric ignition heads, fix and seal them into a flexible paper drum, which is used to temporarily store liquid oxygen in the blast hole;

2. Put the flexible paper reel into the blast hole, and then block the upper space of the blast hole with blast mud; See attachment 1 (Video 1) for the operation of loading flexible paper roll

3. Connect the intelligent filling machine to the dewar tank and the air duct respectively to inflate the flexible paper drum (mainly liquid oxygen + a small amount of liquid nitrogen);

4. After filling the liquid oxygen hole by hole, connect the ignition heads in each paper drum (in series) to form an initiation network, and check the circuit with an ohmmeter;

5. Set up a warning and detonate after warning; See Annex 2 (Video 2) for blasting effect;

6. Under the action of air energy (gas expansion force), the rock produces cracks and separates from the original rock mass.

Principle of liquid rock breaking by oxygen

Using the characteristic that oxygen can quickly change from liquid to gas, the time is short (on the order of milliseconds), and its total expansion ratio is as high as 860:1. A quasi-static pressure of about 280-300mpa can be formed in the blast hole and act on the hole wall to crack and move the rock. The expansion mechanism is as follows:

1. When the liquid oxygen is poured into the flexible paper drum, the plastic film bag is a heat insulation device, so that the liquid oxygen cannot absorb a large amount of heat from the external environment to achieve instant gasification.

2. After putting in the roll paper, because the roll paper is a loose structure, there are a lot of voids in the loose structure, and the paper contains a certain amount of water. When the roll of paper is put into the plastic bag, some air also exists in the bag. These moisture and air are heat relative to liquid oxygen with a boiling point of - 183 ℃! Therefore, before the ignition head is not excited, a small amount of liquid oxygen has been heated by the roll of paper, water and air in the plastic bag at high temperature (compared with liquid oxygen at - 183 ℃, water and air at 10-20 ℃ are high-temperature heat sources), and a small amount of oxygen is generated, which is in an unstable state.

3. Under the instantaneous excitation of the heat source of the ignition head, the unstable liquid oxygen in the paper roll gap (which may have partially become a mixture of liquid oxygen and oxygen) is rapidly gasified and the volume expands 860 times. When the expansion force acts on the blast hole wall and is greater than the tensile and shear strength of the rock, the rock around the blast hole will crack and move.

In addition, the roll paper is a multi-layer structure. In the gap, the liquid oxygen is - 183 ℃, while the roll paper is 10-20 ℃ (assuming that the on-site temperature is 10-20 ℃), which greatly increases the heat exchange area. According to the heat exchange theory, in the same space, the larger the heat exchange area, the faster the heat exchange, which is conducive to the rapid and stable transfer of low excitation energy in the flexible paper drum (blast hole), so as to achieve the effect of rapid and simultaneous vaporization of liquid oxygen in the blast hole.

Gas plastic tube wz electric ignition

Gas plastic tube filling hole

Safety characteristics of air energy gas explosion

1. Blasting safety. Air energy gas blasting is safer than carbon dioxide gas blasting. First, all objects in the system have no civil explosives or dangerous chemicals that are easy to explode. Second, there is no explosion shock wave. Third, the blasting vibration is very small. Fourth, due to gas expansion, the blasting dispersion distance can be controlled. The warning distance for explosive blasting is required to be no less than 200m, The warning distance of air energy gas explosion is 30m.

2. Loading safety and public safety. Air energy gas blasting adopts the filling technology in the hole. The flexible paper drum assembled outside the hole does not have any dangerous goods, so the operation of assembly and loading into the blast hole is safe. After the loading hole is blocked, the liquid oxygen is filled into the flexible paper drum through the conduit. Such static atmospheric pressure operation is also safe. Moreover, criminals can not use this flexible paper drum gas storage device to engage in sabotage activities.

Dangerous characteristics of air energy gas explosion

In the air energy gas blasting device, the most dangerous substance is liquid oxygen. Liquid oxygen is a dangerous chemical. First, liquid oxygen has fire risk. Although it is nonflammable, it can strongly support combustion. The fire risk is class B. Second, liquid oxygen has explosion risk. When liquid oxygen accumulates in a closed system and cannot be insulated, pressure damage may occur. When the temperature rises to - 118.4 ℃ without increasing the pressure, liquid oxygen cannot maintain the liquid state, and part of it will change to gaseous state. If the pressure is not relieved in time, it will also lead to physical explosion. Therefore, in actual operation, it is OK to operate and protect according to the dangerous characteristics of liquid oxygen and safe operation procedures.

Safety management of air energy and gas blasting

1. At present, the state has no special laws and regulations for the management of gas blasting. The Ministry of public security also has no regulations on the management of permit and filing of gas blasting operation by blasting companies.

2. In March 2020, the Ministry of Public Security issued the national special action plan for deepening the fight against gun explosion crimes (2020-2022), which requires grass-roots public security organs to "strengthen the safety supervision of gas blasting". We understand that where we conduct gas blasting operations, we should take the initiative to report to the local public security organ so that they can supervise the safety of our gas blasting.

3. Article 9 of the regulations on the safety management of civil explosives stipulates that "the State encourages the industrial units of civil explosives to adopt new technologies to improve the safety performance of civil explosives". The blasting operation unit is the industrial unit of civil explosives, and the air energy gas blasting technology is "a new technology to improve the safety performance of civil explosives", which should be supported by the national management department.

4. Since the most dangerous substance in this unit is liquid oxygen - dangerous chemicals, according to Article 10 of the work safety law (implemented on September 1, 2021), "if the responsibility for the supervision and administration of work safety in emerging industries and fields is not clear, the local people\'s governments at or above the county level shall determine the supervision and administration department according to the principle of similar business". We understand that departments with similar businesses are emergency management departments, and we should also report to the local emergency management department in order to accept their safety management.