RU2557264C2 - Bottomhole wad of blasthole charge - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: bottomhole wad of blasthole charge comprises a cylindrical solid body on the side surface of which in the plane, perpendicular to wad, circular grooves are made. The bottomhole wad is made from carbon fibre-reinforced plastic. The solid body of wad is made in the form of uniform monolithic structure from the material containing 74.8 weight fractions of small coal - small coal, slime, hardened by the cold hardening formaldehyde resin SFZh-3032 amounting 20.6 weight fractions and a hardener amounting 4.6 weight fractions of water solution of technical petrolsulphonic acid. The invention allows to increase efficiency of drilling-and-blasting works in coal mines due to reduction of labour input of processes of fabrication of wads and respectively their prime cost.

EFFECT: invention allows to improve quality of produced coal due to decrease of his impoverishment, the simplified bottomhole wad is suitable for charging of blastholes in automatic mode by respective robots.

4 dwg

Description

The invention relates to the field of blasting and can be used in the mining industry, in particular coal.

Downhole wads for blast holes and borehole charges of explosives are known, made in the form of water-filled ampoules from a plastic film in the form of elongated cylindrical vessels (see V.E. Aleksandrov et al. Safety of blasting in coal mines. M: Nedra, 1986, p. 66-69).

The disadvantages of these wads are the low reliability of the integrity of the hydraulic ampoules when they are filled with water under a pressure of not more than 0.05 MPa and sent to the hole when loading, which increases the complexity of the process of charge formation. In addition, to ensure the tightness of the borehole after hydraulic shut-in, a locking wad from clay or sand-clay mixture is introduced.

Downhole wads made in the form of separate blocks made of clay or sand-clay mixtures are known, while checkers are made directly in the face before loading holes in a special machine, and most often manually.

The disadvantages of these wads are the significant complexity of manufacturing them in the face, the difficulty of loading a hole or well, because wad made of plastic material during its sending, has a tendency to burst in the hole, the inability to extract it from the hole. It is known that the density of clay is significant, which determines the complexity of the delivery of wads, especially for rising workings on steep fall layers. Note that clay and sand clog the fired coal with explosives (hereinafter referred to as explosives), i.e. ash content of coal artificially increases, worsening its quality. In addition, clay and sand are rather scarce building materials, the price of which will inevitably increase due to the limited availability of their land resources.

In addition, the resistance time for detonation products for both wads is of the order of 7 ms (milliseconds), and therefore the development of designs of wads with high resistance should be considered quite appropriate, because this will help to save explosives and reduce environmental pollution by toxic gases.

A device for jamming holes (AS USSR No. 1536954), including a cylindrical body made of two single-slope wedges adjacent to each other by the planes of the ramps. Wedges are fastened together by means of shear spring elements installed in annular grooves. Slope planes may be coated with anti-friction material. Wedges are made by casting or stamping from metal, plastic or composite materials.

The disadvantages of this device, which we adopted as a prototype, are: its structural complexity, which determines the high complexity of its manufacture, a large assortment of components and parts determines the high cost of the product. The use of this device in coal mines will dilute the coal mass with fireproof ballast, which is unacceptable when it is exported to the international market.

The objectives of the invention are: increasing the efficiency of drilling and blasting operations in coal mines by reducing the complexity of the processes for the production of wad and, accordingly, their cost, as well as improving the quality of the beaten coal by reducing its dilution, as well as the development of downhole wad of a simplified design, suitable for loading holes in the automatic mode appropriate robots.

The problem is solved in that the downhole wad is made of carbon fiber.

Indeed, the proposed technical solution allows you to organize in-line production of wad on high-performance stamping equipment with extremely low labor costs using non-deficient raw materials - fine coal. Its raw material base in Kuzbass is almost unlimited and concentrated in the dumps of processing plants.

Utilization of small coal will positively affect the environmental situation of Kuzbass.

Carbon fiber in its composition contains 74.8 mass fractions of fine coal bonded with SFZh-3032 cold curing phenol-formaldehyde resin (20.6 mass fractions) and a hardener in a volume of 4.6 mass fractions of an aqueous solution of technical benzosulfonic acid.

The production of carbon fiber was mastered at the NPO Prokopyevskhydrogol (Kuzbass) for the manufacture of tubing supports for rising mines (see V.V. et al. Polymer composite materials in mining. M .: Nedra, 1988, p. 187-189).

Carbon fiber has the following physical and mechanical characteristics: Density 1.15-1.2 g / cc, compressive strength 25-40 MPA, tensile 4MPa, bend 5.8 MPa.

Phenol-formaldehyde resin belongs to the category of hardly combustible materials, i.e. almost non-combustible.

As can be seen from the characteristics, the density of the carbon layer is 6.4-6.5 times lower than the density of steel (7.7-7.9 g / cc), which means that the laboriousness of delivering bottom-hole material to the mine decreases by the same amount drilling and blasting site. Note that the process of delivering carbon-fiber wad to the hole itself is not difficult, because it is similar to the process of introducing a cartridge of explosives into a hole. In the future, the operation of introducing a cartridge of explosive and downhole wad into a hole can be assigned to special robotic devices, which will undoubtedly increase the productivity and safety of drilling and blasting operations. We also note that the use of carbon fiber wad does not in any way impair the quality of the beaten coal, because carbon fiber is almost the same coal.

The proposed technical solution is illustrated by drawings, where figure 1 shows a longitudinal section of a carbon fiber wad; figure 2 shows a longitudinal section of the channel of the explosive charge, in which the explosive charge and the stemming of carbon fiber wad; figure 3 presents the node 1 of figure 2, explaining the principle of operation of the gas shutter; figure 4 presents the node 2 of figure 2, explaining the sealing circuit of the borehole channel using a ring of elastic material.

The bottomhole carbon fiber wad is a checker 1 of cylindrical shape, in the end of which a conical or sphere-shaped recess 2 and transverse annular grooves 3 are made. The wad or wads are placed in the hole after the explosive blocks 4, while the ends of the wad with recesses 2 are oriented towards the explosive charge . In the groove or grooves of the last locking wad, rings 5 of elastic non-combustible material, for example of non-combustible rubber or basalt cord, are placed.

Downhole wad works as follows. After detonation of charge 4 of the explosive, a sharp increase in the pressure of detonation products occurs, which, acting on the walls of the cone-shaped part 2 of wad 1 in the direction normal to the surface of the cone, ensure the turn of the wad edges and their wedging in the borehole. Gases that burst into the lint space move along the slotted channel along the borehole and enter the space of the transverse annular grooves 3, where they expand, resulting in the formation of a vortex flow of the opposite direction of gases, creating additional hydraulic resistance to gases in this area, preventing their leakage. The installation in the extreme groove 3 of the locking wad of an elastic ring 5 of non-combustible material helps to additionally seal the hole, as well as to keep the garland of checkers from falling out of the hole having a bias towards the bottom.

The implementation of the proposed solution will improve the efficiency of drilling and blasting operations in coal mines by reducing the complexity of the manufacturing processes of wad from non-deficient fine coal, as well as improving the quality of the beaten coal by reducing its dilution by non-combustible ballast.

Claims (1)

Downhole blast hole of a blast hole, including a solid body of cylindrical shape, annular grooves are made on the lateral surface of which in a plane perpendicular to the axis of the wad, characterized in that the solid body of the wad is made in the form of a single monolithic structure of a material containing 74.8 mass fractions of fine coal - a lint, sludge bonded with phenol-formaldehyde resin of cold curing SFZh-3032 in an amount of 20.6 mass fractions and a hardener in a volume of 4.6 mass fractions of an aqueous solution of technical benzosulfonic acid.

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