RU2114305C1 - Method and device for crushing rock - Google Patents

Abstract

FIELD: mining industry. SUBSTANCE: this is intended for crushing rock by means of vertical and inclined bore-holes. According to method, poured into drilled bore-hole is cryogenic liquid such as nitrogen. Then lowered into bore-hole is barrel of artillery cannon together with counterrecoil mechanism and recoil brake. Discharged through cannon barrel bore into drilled bore-hole is water heated to 99 C or overheated to 200 C in amount which is needed and sufficient for complete conversion of liquid nitrogen into gas. In result, rock mass is crushed in mode of physical explosion. Cannon barrel with counterrecoil mechanism and recoil brake are used for sealing off bore-hole. EFFECT: higher efficiency. 2 cl, 2 dwg

Description

 The invention relates to blasting and is intended for the destruction of rocks by vertical and deviated wells.

 The destruction of rocks is known by the interaction in the well of water with a cryogenic liquid - nitrogen in the mode of a physical explosion.

 The disadvantages of the prototype: the sealant at the wellhead, equipped with a check valve, will be ejected during a physical explosion without significant resistance and instead of destroying the rock mass, gas will be exhausted from the well. A tank with water or liquid nitrogen above the wellhead and resting on a destructible array, as shown in the prototype drawing, will also be discarded, deformed, or destroyed during an explosion, thus, the hardware implementation of the known method makes it inoperative.

 A method based on the shock contact of two fluids requires the fastest possible supply of one fluid to another located in the well. A sealant at the wellhead reduces its free cross-section, and a non-return valve inhibits fluid flow, which must be high-speed.

The technology of the known method does not provide the order of supply of components: nitrogen into water or water into liquid nitrogen, which is not uniform, since the density of liquid nitrogen at a boiling point of 77.35 K under a pressure of 1 kgf / cm ² is 0.808 kg / l.

The prototype does not accentuate the optimal temperature regime, which is crucial. So, at a water temperature of 15-20 ^o C, its flow rate will be 4-3 kg per 1 kg of liquid nitrogen, respectively, which leads to such a low (20-25%) content of nitrogen (serving as a "working fluid") in the well that the destruction efficiency of the medium will be very minor.

 The aim of the invention is the elimination of the above disadvantages.

 To achieve this goal, heated or superheated water is supplied under pressure in a well containing cryogenic liquid - nitrogen in an amount necessary and sufficient for the complete conversion of cryogenic liquid into gas, passing a high-speed stream of water through the barrel of an artillery gun, the muzzle of which is lowered into the well by the distance exceeding the length of the rollback of the barrel during a physical explosion in the well.

 The goal is also achieved by the fact that a device containing a tank and a well sealant is used to implement the method, while the sealant is an artillery barrel with a knurl and a retraction brake, a tank nozzle with a remotely controlled gate is adjacent to the breech, and the entire structure is mounted on a support in in the form of attachments to a drilling rig or a special mechanism with the possibility of joint movement of the tank and the barrel during rollback.

 A diagram of the method for resolving rocks and a device for its implementation is presented in FIG. 1 and 2.

 A device for implementing the method includes the following elements: well 1, artillery gun barrel 2, shutter 3, recoil brake 4, knurling 5, cradle skids 6, tank 7 with heated or superheated water with thermal insulation, electromagnetic tap 8, support of mounted equipment 9, with which the cradle of the artillery gun and tank 7 are rigidly fixed, the latter with the possibility of sliding up and down together with the artillery barrel when it is rolled back. (Mounting the gun carriage to the vertical support 9 and the support 9 itself in Fig. 2 are not shown).

Set out in the form of attachments can be installed on drilling rigs of the type SBSh, SBU, SBR GOST 26698-85 for drilling blast holes in open cast mining. A drilling rig compressor with an air supply of 0.417 to 0.834 m ³ / s can be used to discharge heated water into the well under the pressure of compressed air.

 A tank-doser with liquid nitrogen, equipped with a screen-vacuum superisolation, can be mounted on a rotary mechanism mounted on another support (not shown in the diagram).

 Pouring the first component, nitrogen, into the well does not require high feed rates, up to the pulsed ejection required when the second component, heated water, is fed into the well. Therefore, pouring liquid nitrogen into the well can be performed from a tank on a vehicle, for example, a tank truck, after pouring it hurries off to the side of the destruction zone.

 The given order of supply of components and the need for heating water are due to the ratio of their volumes.

At a water temperature of 15 ^o C and its cooling after contact with liquid nitrogen to 2 ^o C, taking into account heat losses of 10%, for the complete conversion of liquefied nitrogen into gas, 4 kg of water per 1 kg of liquid nitrogen is required, i.e. 20% of the latter in the well, and 80% of the water, which serves only as a coolant for converting liquid nitrogen into gas. The low efficiency of a physical explosion upon contact of nitrogen with cold water is obvious.

At a water temperature of 95 ^o C, the evaporation of 1 kg of liquid nitrogen requires 0.56 kg of heated water (taking into account losses of 10% heat), and at a temperature of 190 ^o C - 0.29 kg of superheated water at 15% loss during heat and mass transfer.

 Heated water is much smaller in volume than liquefied nitrogen with a density of 0.808 kg / l, and if it is necessary to quickly supply the second component to the well, the expediency of quickly supplying water to the well containing liquid nitrogen is obvious.

The maximum temperature of the heated water is limited by the natural limit of 99 ^o C, and the extremely high temperature of superheated water is 200 ^o C - by technical reasons, since with a further increase in temperature the pressure rises sharply and, accordingly, the metal consumption of the equipment increases.

 The water supply is limited by the diameter of the barrel of the artillery gun, which can be increased by removing from the barrel of the liner that protects the barrel from erosion. Along with increasing the channel cross-sectional area, the main surface of the pipe will be opened - without grooves that would inhibit the high-speed fluid flow. In view of the foregoing, it is advisable to use trunks with smooth-bore channels for firing fixed projectiles.

 Examples of the application of the method.

1) Well: diameter 0.25 m, depth 15, 3 m from the wellhead is not filled with components, the length of the charged part is 12 m with a volume of 0.589 m ³ .

Water heated to a temperature of 99 ^o C, is poured into the tank 7 with thermal insulation. The tank is connected by a flexible high-pressure hose to the compressed air receiver from the compressor of the drilling rig. The attachment support to the drilling rig is oriented with the calculation of the quick lowering of the gun barrel into the well. At a flow rate of 0.56 kg of water for the conversion of 1 kg of nitrogen with a density of 0.808 kg / l to gas, the composition of the interacting liquids in volume percent: 31% water and 69% liquid nitrogen.

 Of the 589 l of the charged volume of the well, 406 l is occupied by liquid nitrogen - up to 8.3 from the wellhead; 6.7 wells - free from its mouth.

The barrel length of the gun is 2.5 m, for 1 m the barrel is immersed in the well. The total length of the gun channel and the nitrogen-free part of the borehole is 6.7 + 1.5 = 8.2 m. The thickness of the borehole walls (at the muzzle) is 25 mm, the annular gap between the borehole and the borehole walls is 5 mm. With a bore diameter of 250 mm, the bore
250 - (25 + 25) + (5 + 5) = 190 mm.

 Water supply is limited by the diameter of the barrel bore 190 mm. With a length of 8.2 m, the volume of the cylinder from the water will be 230 liters, and 184 liters of heated water must be supplied, the length of the cylinder from this volume of water will be 6.5 m with the length of the free volume of the well and the barrel of the gun 8.2 m.

 Thus, the ejected volume of heated water after the release has not yet reached the surface of liquid nitrogen, the contact of two liquids and their interaction in the mode of physical explosion of a cryogenic liquid will not occur even after the release of all the volume of heated water, which is necessary and sufficient for the complete conversion of liquid nitrogen into gas, consequently, after the discharge of water, the electromagnetic tap or gate 8 of the tank 7 and the shutter 3 of the gun, the remote closing of which should be provided, will be freely closed.

 As heated water penetrates from the surface of the cryogenic fluid to the bottom of the well, an ever-increasing mass conversion of liquid nitrogen into gas occurs, accompanied by shock waves incident on the walls of the well and reflected. A physical explosion, composed of foci of macroexplosions, will be extended in time. An increase in the duration of shock wave processes in the well increases the efficiency of explosive destruction.

 The barrel of the artillery gun contributes to the work of the destruction of the medium by the piston pressure of the gas held in the well until the destruction of the array, since, unlike conventional jamming, the trunk is not ejected from the well.

 During rollback, the well remains in the borehole at a length of 1.5-2.0 borehole diameter - from the muzzle to the wellhead. An annular gap between the borehole and the borehole walls of the order of 5 mm over a length of 375-500 mm will create a sufficiently strong resistance to prevent a significant leakage of gases (taking into account the short duration of the rollback) without committing fracture work.

 The effective work of destruction performed by gases under similar conditions is confirmed by the practice of using "hydrox" cartridges, where for a cartridge in a steel sleeve with a diameter of 53 mm, cutters are used for drilling holes with a diameter of 60 mm.

2) The tank 7 is filled with water, superheated to 200 ^o C under a pressure of 15.86 kgf / cm ² . Taking the temperature of the water after the emission of 190 ^o C and further heat loss during heat and mass transfer of 15%, we obtain a flow rate of 0.29 kg of superheated water per 1 kg of liquid nitrogen. Volume ratio of components: 81% nitrogen and 19% superheated water.

For 600 l of the volume of the well filled with two fluids, 486 l falls on nitrogen and 114 l on water. Facilitates the rapid supply of a significantly smaller volume of water, and most importantly - increases the mass of liquid nitrogen in the well and the intensity of the physical explosion, since the temperature gradient between the cryogenic liquid and superheated water increases to 390 ^o C.

 When working with superheated water, it is not necessary to connect the tank 7 with an external pressure source - a receiver of compressed air from the compressor, since superheated water in the tank 7 is under excess pressure.

 The shutter after the discharge of water must be automatically and quickly closed. Upgrading the shutter, especially the piston for large-caliber guns, can be difficult.

 A rigid layout of the outlet pipe of the tank 7 with the breech of the gun (with the shutter removed) with the strengthening of the valve 8 with an electromagnetic actuator and increasing the wall thickness of the pipe to the level of the artillery barrel is possible.

With the main advantage - environmentally friendly products of a physical explosion (water and nitrogen), the method has the following limitations:
not applicable in wells with a diameter of less than 200 mm due to difficulties in quickly supplying the required volumes of water through small sections, as well as deterioration of the conditions for mixing components and difficulties in heat and mass transfer processes in the well itself necessary for the development of a physical explosion;
for the same reasons, the method is not applicable for deep (25 - 40 m) wells;
explosive destruction of the whole block by explosion of a series of wells is excluded.

 The latter drawback is compensated by the possibility of blasting without stopping the quarry due to the absence of explosives and explosive means, the exclusion of toxic (and other) chemical explosion gases, and the safety of work due to the small expansion distances of the destruction products during a physical explosion.

 The preferred area of application of the method is the destruction of the environment near populated areas with the introduction of open blasting.

Claims (2)

 1. The method of destruction of rocks by interaction in the well of a cryogenic liquid - nitrogen with water in a physical explosion mode, characterized in that heated or superheated water is supplied to the well containing liquid nitrogen in an amount necessary and sufficient for the complete conversion of the cryogenic liquid into gas, passing a high-speed stream of water through the barrel of an artillery gun, the muzzle of which is lowered into the well at a distance exceeding the length of the recoil of the gun in a physical explosion.  2. A device for rock destruction containing a water tank and a well sealant, characterized in that the sealant is an artillery barrel with a knurl and a retraction brake, a tank nozzle with a remotely controlled gate is adjacent to the breech shaft, the entire structure is mounted on a support in the form attachments to the drilling rig or a special mechanism with the possibility of joint movement of the tank and the barrel when rolling back.

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