FR3018808A1 - INSTALLATION FOR THE PRODUCTION OF EXPLOSIVES BY MIXING WITH A GASIFICATION REAGENT - Google Patents

Abstract

The present invention relates to an in situ production facility for explosive product (10) by mixing (a) an emulsion-based matrix and a gasification reagent, comprising at least a first reservoir (1-1) containing said matrix, and a second reservoir (1-2) containing said gasification reagent, and a first hose (61) at least partially flexible cooperating with a first pump (2-1) and a first valve (V1), suitable transferring said matrix separately to a first mixer, preferably a first static mixer (7), and - a second transfer circuit (1b) of said gasification reagent comprising at least a second pipe (62) at least one flexible part cooperating with a second pump (2-2) and a second valve (V2), able to transfer said gasification reagent separately to said first mixer (7), characterized in that said second pipe (62) is disposed entirely at the i an interior of the first pipe (61) forming an assembly (6) of coaxial pipes, said first mixing device being disposed inside the first pipe at its downstream end (61f), said second pipe terminating just upstream of said first mixer .

Description

The present invention relates to the field of the preparation and use of explosive products including explosive emulsions used in the extraction of raw material and mining industry. These products are systematically constituted from a so-called inverse base emulsion or "water in oil" also called "matrix" obtained by a mixture of: - an organic continuous phase, constituted mixture of various fuels such as mineral oils, gas oil, and a discontinuous aqueous phase consisting of various oxidizing salts in aqueous solution. The most frequently used oxidizing raw materials in this industry are: ammonium nitrate, sodium nitrate, calcium nitrate. With regard to fuels, it is gas oil that is either pure or mixed with new or used mineral oils, especially recycled motor oil. To give this mixture improved detonation characteristics, it is necessary, in known manner, to disperse homogeneously "porosities" within it. To date, the method mainly used in the industry for the sensitization of bulk or cartridge emulsions is chemical gasification. This consists in generating as chemically and as homogeneously as possible gas bubbles in the medium. The "porosities" thus obtained will form hot spots, initiators of the detonation and thus help maintain the propagation of a shock wave from the priming system.

There are other ways, well known to create these "porosities" in the emulsion. In particular, small hollow bodies ranging from a few tens to a few hundred microns can be dispersed. Among these, there may be mentioned glass microbeads, thermoplastic polymer beads or expanded polystyrene beads. The present invention relates to the manufacture of explosive charges from an emulsion or matrix that is sensitized by mixing with reagents that react with the emulsion and generate a chemical gasification.

More particularly, but without limitation, to react with ammonium of said emulsion matrix (hereinafter M), a gasification reagent (hereinafter R) based on sodium nitrite or equivalent is used. in the presence of a catalyst such as an acid, especially acetic acid, of the following chemical reaction: NH 4 + + NO 2 - → N 2 + 2 H 2 O This chemical reaction generates nitrogen gas which leads to a reduction the final density of the mixture product obtained. Generally, we go from an initial density di of the matrix M di = 1 to 2 that we decrease to a value dj = 0.5 to 1.5 depending on the proportion of reagent R / M, typically di = 1.4 and dj = 1.2 at 0.9. In the rest of the text herein is understood to mean a matrix or emulsion, the emulsion itself supplemented with a catalyst component and preferably also water to serve as a lubricant to facilitate the displacement of the viscous emulsion within the pipeline. loading. Indeed, the present invention relates more particularly to the use of these products in a hole in which a priming charge and a detonator wire are placed and in which the explosive products (emulsion mixture + gasification reagent) are transferred using a flexible hose.

EP338707 describes an installation in which the two emulsion and gasification reagent components are mixed at a sort of rigid lance or gun which is introduced in small quantities into a hole. It is not an installation in which products are remotely stored in larger quantities in a truck and transferred using pipe (s) unwound (s) from a reel to a load hole . This type of installation can only be used to load holes of small diameter (less than 50mm) as it is insisted several times in this document.

This installation is therefore not suitable for loading holes with products stored remotely in a truck and transferred to the charging hole using a pipe unrolled from a reel. In addition, the two components (emulsion and gasification reagent) are introduced with a pump with two bodies and two pistons which does not allow to vary the relative proportion of two components in the mixture during filling of the hole. The present invention relates more particularly to a process in which mixing of the emulsion and porosity reactants is carried out at the site of use of the explosive and more particularly in a hole, in particular a borehole, which the an explosive charge is supplied by means of a transfer line from an installation where the emulsion matrix is made and / or stored at a distance from the hole. Typically the hole has a depth of 5 to 30m and a diameter of 5 to 50 cm.

The basic raw material, the emulsion matrix, can be produced on site by a modular plant as described in PCT / FR2014 / 050032 or by mobile installation called UMFE (Mobile Explosive Manufacturing Unit) therefore trucks carrying materials useful for manufacturing that go to the site of use (mines, quarries or construction site) for the production of explosives.

The transfer and mixing of the 2 components, emulsion on the one hand and gasification reagent on the other hand poses a number of difficulties. Usually, the reactants and catalyst are introduced together and mixed with the emulsion matrix in a static mixer upstream of the loading line, the downstream end of which is introduced into the borehole to pump the explosive product therein. The reason is that it is thus possible to convey the mixture in a single pipe that is unwound from a winding drum at its upstream end located at a distance from the hole typically 30 to 100 m. On the other hand, it avoids placing inside the hole metal parts such as the static mixer which by the size it generates, interfere or make it more difficult handling in the hole and especially to avoid shocks with the rock mass of my wall of the hole being able to cause sparks near the charge of priming and / or being in contact with the detonator wire damaged this one. In US Pat. No. 5,524,523, a component transfer installation is described in the hole with a pipe 12 containing 3 pipes arranged side by side, in parallel with a first one, the base emulsion feed pipe 16 already mixed with a pipe. gasification reagent called "gassing solution", the other pipes used to provide other additives such as stuffing products ("stemming"). In US Pat. No. 5,524,523, the emulsion and the gasification reagent are therefore already mixed (not separately) in the same duct 16 before being introduced into a static mixer located at the outlet end of the duct 20 in which the mixing and the reaction of the two components is complete. This introduction of the two components together (emulsion and gasification reagent) upstream of the same pipe, however, has several disadvantages. The gasification begins after the introduction of the gasification reagent and the mixture starts to be explosive from the introduction of the gasification reagent therefore in the transfer pipe which creates pressure increase constraints in the pipe and risks to look for safety because the pipe is filled with explosive. In addition, one can not vary the density in real time during filling of the hole, because there is a relatively large and reliably indeterminable product contained in the pipe to be taken into account. And, therefore, if we want to vary the density in real time of the final product arriving in the hole, depending on the power of the explosion to produce, as is the case in practice, there is a quantity unreliable reagent contained in the conduct difficult to estimate. It is therefore not possible to control the value of the density of the product arriving in the hole from the composition introduced due to the decrease in the density in the pipe.

In WO / 2008 039823, there is described an installation in which the two components are transferred into two separate pipes with a helical outer pipe surrounding the main central pipe of larger diameter. The downstream end of the small pipe passes through the wall and joins the inside of the larger pipe so that their coaxial down ends open into the same nozzle. Thus one can mix the two components as close as possible to the hole in an external mixing nozzle. But this embodiment has the following drawbacks. First, this complex helical component pipe is relatively expensive and fragile. In fact, in particular, the outer pipe containing the most dangerous product, namely the gasification reagent, is exposed in the outer part of the pipe which undergoes fatigue and wear due to friction against the walls of the hole, during its winding and unwinding and manipulation in the hole. On the other hand, in practice, it is necessary to regularly shorten the downstream end of the pipe which degrades due to friction in the hole during installation and withdrawal including winding from a winding drum at its upstream end. However, the arrival of the reagent transfer pipe R inside the supply pipe of the matrix M is incompatible with the shortening of the pipe at this position. On the other hand, the gasification reagent must be conveyed over a helical path and therefore over a longer distance of pipe than the straight central pipe of the emulsion because of the helical disposition of the peripheral pipe which requires losses of load and therefore greater pumping force. Finally, no provision is disclosed in the art WO 2008/039823 to manage the respective amount of reagent and emulsion base or matrix or their intimate mixture in a static mixer that is not exposed in the hole. Another problem underlying the present invention relates to the implementation of explosive mixing products of different densities during filling according to the depth of the hole or between different holes. In practice, it is advantageous to be able to produce a product of higher density, about 1.2 in the bottom of the hole and a lightened density of about 0.8 at the top of the column. In fact, the downhole is more difficult to destroy and requires more explosive volumetric energy than the upper parts, and an optimal explosion in a borehole than the explosive energy column. On the other hand, the rock mass to be destroyed varies in composition and volume between the borehole and the free surface, depending on the depth and also because of the deviations resulting from the inclination of the substantially cylindrical borehole, and from one hole to another because of the different inclinations varying from 0 to 25 ° of the said holes and the heterogeneity of the rock mass composition. The justification for making a lower density explosive product is also to reduce the cost of the shot because if the density decreases, this means that there is less mass of product and therefore a lower cost of explosive product.

It is therefore advantageous to be able to adapt the energy of the explosive to the rock mass in a simple way. In the prior art, the production of explosive batches of different densities is not possible without removing the pipe and purging the loading pipe over a long distance of explosive product mixed upstream at a relatively large distance from the hole. According to the standard method, therefore, successive fillings of products having different densities must be made by removing the pipe from the hole and purging it between two filling procedures in the same hole to discharge the explosive product having a different density before producing a product of different density to avoid mixtures of products of different density. This is too time-consuming and therefore can not be realized in practice. Thus, with the device conventionally used, a medium density product 1.2 is produced for all the explosive charge. As a result, there is too much volumetric energy (the product of density and specific energy) consumed in the column, whereas higher explosive energy at the bottom of the hole and lower in height would be preferable.

It is therefore very advantageous to be able to vary the density of the product in the same production cycle. The object of the present invention is therefore to provide an improved installation and method of producing an explosive product comprising the implementation of flexible pipes for loading into a hole which are more suitable and therefore more reliable, more secure and simpler to produce. and implement on the one hand and which allow to: - put the two components in optimal contact with each other to mix at a static mixer in the hole downstream of the transfer pipe unwound from a winding drum, - shorten without difficulty the transfer lines when their ends are degraded by wear and friction in the hole, and - change in real time the density of the final product during loading and output of the transfer pipe in the hole being filled continuously without having to purge and / or remove the pipe from the hole, and - while avoiding the risks generated by the presence eventual metal parts exposed unprotected in the hole. To do this, the present invention provides an installation for producing explosive product in situ by mixing (a) a viscous product, called a matrix, comprising an inverse emulsion of an aqueous phase of oxidant and oily phase of fuel and (b) ) a liquid product containing a chemical compound capable of reacting with said matrix to increase its explosive character by gasification, called gasification reagent, said installation comprising at least: a first reservoir containing said matrix based on said explosive emulsion and a second reservoir containing said gasification reagent, and a first transfer circuit of said matrix comprising at least a first pipe at least partially flexible cooperating with a first pump and a first valve, able to transfer said matrix separately. to a first mixer, preferably a first static mixer, and - a second trans-circuit fermenting said gasification reagent comprising at least a second pipe at least partially flexible cooperating with a second pump and a second valve, adapted to transfer said gasification reagent separately to said first mixer, characterized in that said second pipe is disposed entirely within the first pipe forming a set of coaxial pipes, said first mixing device being disposed inside the first pipe at its downstream end, said second pipe terminating just upstream of said first mixer. It is understood that the outer diameter of said second pipe is smaller than the internal diameter of said first pipe so that said matrix is conveyed without contact with the gasification reagent, in the annular space between the two pipes on the one hand, and on the other hand, the matrix flow makes it possible to arrange the second pipe substantially coaxially with the first pipe without the need for a centralizer, the gasification reagent being conveyed separately without contact with the matrix until it opens in the static mixer in which an intimate mixture of the two products is produced to produce the explosive product at the outlet of the static mixer at the downstream end of the first pipe. In the present description, the term "upstream" and "downstream", the position in reference to the flow direction of the fluids in the pipes from the tanks to the first mixer and to the outlet opening into the dispensing hole of the product. explosive at the output of the first mixer. It is understood that in operation the downstream end of the coaxial pipe assembly is inserted into a hole to be filled with explosive material exiting said first mixer.

Thus, on the one hand, only the first pipe is in contact with the outside and in particular the walls of the hole during operations protecting the other equipment and in particular avoiding damage to the detonator wire, among others; and, on the other hand, by controlling the relative flow rates of the matrix and the gasification reagent, controlling in almost real time the density of the explosive product obtained, as the hole is filled continuously and thus varying the density of the product. explosive product, namely its explosive power according to the depth at which it is arranged in the hole or from one hole to another in different holes as explained below in connection with the method according to the invention.

The term "static mixer" is understood herein to mean, in a manner known to those skilled in the art, a device containing mechanical elements able to create a modification in the movement of a moving fluid traveling through it creating vortex movements allowing the mixing without adding energy to move said mechanical elements other than that provided by the movement of the fluid. Most often the static mixers consist of a tube containing one or more three-dimensional structures favoring the appearance of vortices during the passage of a flow of fluid in the longitudinal direction of the tube.

More particularly, the coaxial pipe assembly is connected to a reel drum, and is at least partially or coactably wound on said reel drum, the downstream end of the coaxial pipe assembly being disposed in or out of above an explosion hole, preferably a substantially cylindrical borehole having placed an explosive charge and a detonator connected to the surface by a detonator wire. Typically, a reel drum of 30 to 80 cm in diameter is used for 10 turns of winding of pipes 30 to 100m long with external diameters of first pipe of 30 to 50mm and internal diameters of 25 to 40mm and external diameters. second pipe from 5 to 15 mm with an internal diameter of 3 to 10mm. More particularly, said first and second pipes are connected coaxially to each other at their upstream ends by a first connecting piece comprising a sleeve with an external cylindrical wall and an internal bent piece, said first connecting piece being of preferably integral with a drum drum on which is wound at least in part or capable of being wound up said set of coaxial pipes, said first connecting piece comprising: a first inlet orifice, forming an upstream opening of said sleeve and disposed axially in a longitudinal direction (XX ') the cylindrical wall of said sleeve, said first inlet being connected to a portion, preferably a rigid portion, said first transfer circuit of said matrix, and - a second orifice of inlet, arranged laterally at the level of the cylindrical wall of said sleeve, forming an upstream opening of said bent piece through the cylindrical wall of said sleeve and disposed perpendicularly to said longitudinal direction (XX '), said second inlet being connected to a portion, preferably a rigid portion, of said second transfer circuit of said gasification reagent, and a first outlet opening, forming an opening downstream of said sleeve and disposed axially in said longitudinal direction (XX ') of the cylindrical wall of said sleeve, said first outlet being connected by a coupling to the upstream end of said first pipe; transferring said matrix, preferably to a portion, preferably a rigid portion of said first pipe upstream of said winding drum, a rigid portion of said first pipe upstream of said winding drum, and - a second orifice outlet, disposed axially in said longitudinal direction (XX ') of the cylindrical wall of said sleeve, forming an opening downstream of said bent piece in the said second sleeve, said second outlet being connected by a connector to the upstream end of said second transfer pipe of said gasification reagent.

It will be understood that, upstream of said first connecting piece, said first and second circuits are separated and extend from said first and second reservoirs in different directions and said first part provides the coaxial connection of the first and second two pipes downstream thereof, the two flows of said matrix and said reagent, however, remaining separated to the first mixer.

More particularly, the fixing of the upstream ends of said first and second pipes on said first and second outlets of said first connecting piece is via two first and second rotary joint couplings each allowing separately the rotation on itself with respect to said longitudinal axis (XX ') of the upstream ends of said first and second pipes respectively, said first connecting piece and said rotary joint fittings being arranged upstream of said winding drum so that said so-called first and second outlet ports are disposed in the axis of rotation of said drum. This feature is particularly advantageous because it avoids twisting of said first and second pipes lords windings and unwinding of said pipes on said winder when the upstream uncoiled portions of said pipes are rotated relative to said axis of rotation of said drum. Fittings of the type referred to as "rotary joint coupling" are well known to those skilled in the art, and consist essentially of two parts interconnected by O-rings and sets of ball bearings allowing the rotary movement of one of them relative to the other about a common axis, each part being adapted to be connected to a separate element. Here, it is a tubular connecting piece adapted to be connected to tubular elements. It is understood that the fixing of the ends of the various pipes on said first connecting piece, possibly on said joints with rotating joints, is via rigid connection.

More particularly, said second pipe comprises at its end downstream, inside said first pipe, a valve adapted to open and let the flow of said gasification reagent under the pressure of said flow when the second pump is actuated and able to remain closed and prevent gasification reagent leakage when the second pump is deactivated. This characteristic is important to allow control and variation in real time during filling of the hole of the density of the explosive product obtained by mixing said matrix and said gasification reagent. More particularly, according to other features: - said first pipe comprises at least a rigid portion bent first pipes assembled to a flexible portion of first pipe tightly and reversibly by a collie, disposed upstream of said drum and secured to it and adapted to be rotated about the axis of rotation when said drum is actuated in rotation, said flexible portion of first pipe being adapted to be wound around said drum, and - said second pipe comprises two flexible parts connected between such by a rigid and reversible connection of the double union type disposed, the flexible portion of said second pipe disposed upstream of said double union type connection being shorter than the flexible portion of said second pipe disposed downstream, said double union type connection being preferably close to said collar.

Thus, when it is desired to shorten said second pipe due to the shortening made at the downstream end of the first pipe when it is worn and damaged, it is easy to open the first pipe at the said collar upstream. drum, unwind the set of coaxial pipes, and take out the downstream portion of said second pipe to shorten it; and this without having to uncouple the upstream portion of the second flexible pipe at the joint with rotating joint and out of said first mixer. One can also - when one wants to operate an installation without variation of density - completely leave the second pipe, shut off said second, inlet orifice and connect a bypass of the second circuit of arrival of gasification reagent on the said first circuit upstream of a second mixer upstream of said drum. In this case, there is no more coaxial circulation of matrix and gasification reagent.

Connections of the type called "double union" are well known to those skilled in the art, and consist essentially of the assembly of at least three pairs of male / female connection parts operating by removable links. More particularly, a hollow tubular abutment having a longitudinal central opening is removably disposed at the downstream end of the first pipe for retaining said first mixer within the first pipe allowing the explosive product to pass through the central opening of the first pipe. said stop, a thread on a cylindrical outer wall for screwing and thus removably fix said abutment against the inner wall of said first pipe, preferably using a screw wrench adapted to cooperate with the end swallowing said longitudinal central opening to screw inside said first pipe or unscrew said stop to remove it from said first pipe.

This feature makes it possible to protect the static mixer and especially to be able to easily remove it to cut the downstream end of the first hose when it is damaged or worn, before reintroducing said first mixer then said stop. More particularly, according to an original feature of the invention, said first mixer is a static mixer comprising a plurality of fins each having a helical surface, preferably extending in its axial direction over a length corresponding to a pitch of the corresponding helical curve, said helical surfaces being supported by a same reinforcing rod to which they are juxtaposedly attached in the longitudinal direction of said first pipe, said successive helical surfaces being angularly offset in rotation with respect to their virtual axis common helical surface substantially coinciding with a longitudinal axis of said first pipe coaxial axis with said first pipe, the diameter of said helical surfaces being substantially the same or just sufficiently smaller than the inner diameter of the first pipe to allow the rotation of said fins under the effect of the pressure of the flows of matrix and reagent mixed through them. This type of mixer manufactured according to the invention is more mechanically reliable and more efficient under the conditions of implementation according to the invention. More particularly, an automated central control and control unit comprising electronic means controlled by software with a keyboard or graphic interface, makes it possible to control and control the respective quantities and flow rates of said matrix and / or preferably said reagent of gasification, and varying the density of the explosive product obtained, by controlling and controlling first and / or second valves and / or controlling the speeds of said first and / or second pumps, preferably said central unit being supported on a vehicle motorized, more preferably said vehicle supporting said first and second tanks and said first and second pump. The present invention also provides a method for in situ production of an explosive product using an installation according to the invention comprising the steps of: 1) transferring a viscous product from said matrix, and a liquid product of said a gasification reagent, in said first and second coaxial pipes, and 2) mixing said matrix and said gasification reagent in a said first mixer, and 3) depositing said explosive product at the outlet of said first mixer, in an explosion hole, preferably a substantially cylindrical borehole having previously placed an explosive charge and a detonator connected to a surface-mounted detonator wire. The process according to the invention therefore consists, according to an original characteristic of the present invention, in varying the respective proportions of gasification reagent and emulsion matrix entering the mixer to change in real time the density of the product arriving in the hole and this in one and the same filling procedure. This is made possible, among other things, by the fact that the reactants R and matrix M are brought into contact just before the mixer and that the explosive product deposited in the hole leaves directly from said mixer. It is thus possible, according to the invention, to automatically adapt the energy of the explosive to the rock mass in a simple manner by making a single filling of explosive continuously or in the same production cycle, a single sequence of explosive pumping, a single continuous sequence means here that the dispensing pipe is placed in the hole, then actuates the transfer pump and deposits and pulls out the pipe once to fill the hole to the desired level. The method according to the invention therefore makes it possible to modify, almost in real time, the density of the product and therefore of the mass energy of the explosive, the latter being inversely proportional to its density, and more particularly to varying the density. of the product allows to have a high density, in the bottom of the hole and a lightened density in the column in height. Typically, holes 5 to 30 m deep and 5 cm to 20 cm in diameter are formed, and at least two, preferably 4, amounts of explosive product are defined for 4 density values corresponding to mass energies of 2 to 5 MJ. / kg (1063 / kg), in particular densities of 0.5 to 1.5. In practice the amount of explosive product substantially corresponds to the amount of said matrix because the relative amount of reagent is of the order of 0.1 to 2% only relative to the weight of explosive product obtained. More particularly, the quantities and flow rates of said matrix and of said gasification reagent are controlled and controlled so as to produce an explosive product of determined value density at the outlet of the first mixer. More particularly, the density of the explosive product obtained during filling is varied according to the quantity of explosive product deposited and / or the depth at which the explosive product is deposited in the same hole or from one hole to another in different holes.

More particularly, selected quantities of explosive products having different specific density values are respectively selected and controlled to be successively deposited in a hole being filled, preferably continuously. Preferably, one chooses from a plurality of predetermined density values corresponding to mass explosive energies of 2 to 5 MJ / Kg (106 J / Kg), preferably densities between 0.5 and 1.5.

In practice the amount of explosive product substantially corresponds to the amount of said matrix in the relative amount of reagent is of the order of 0.1 to 2%. Typically, for holes 5 to 30 m deep and 5 cm to 20 cm in diameter, 4 quantities of explosive product are defined for 4 density values from 0.8 to 1.2. More particularly, in step 1), the said matrix and said gasification reagent are separately transferred from said first and second reservoirs respectively into first pipe and respectively second pipe cooperating with a first pump and a first valve and respectively a second pump and a second valve, and a constant flow rate of said matrix is controlled and controlled by controlling the speed of the first pump and / or the opening of said first valve, and the flow rate of said gasification reagent is varied in controlling the speed of the second pump and / or the opening of said second valve. More particularly, a constant flow rate of said matrix is controlled and controlled by controlling the speed of the first pump using a speed sensor of said first pump, and the flow rate of said gasification reagent is varied at controlling the speed of the second pump using a flow meter. Indeed, in a manner known to those skilled in the art, abacuses allow for a given density value, the respective rates of gasification reagent y and said matrix x vary linearly according to a formula y = ax + b. The values of a and b depend on the composition of said porosity reactants and said matrix. Charts provide graphs of said reactant flow rates in L / min relative to flow values of said matrix in Kg / min. Thus, for a set d matrix rate value, it is sufficient to vary the rate of gasification reagent.

On the other hand, because the viscous product is more difficult to control and it is easier to vary and control the dedication of a liquid fluid, it is advantageous to work with a constant matrix flow and to vary the flow rate of gasification reagent.

Typically; in practice, to produce an explosive product with a density of 0.5 to 1.5, use is made of: a said density matrix of 1 to 1.7 of a so-called inverse base emulsion or "water in oil" obtained by a mixture of ( a) an organic continuous phase consisting of a mixture of mineral oils and gas oil, and (b) a discontinuous aqueous phase of various oxidizing salts in aqueous solution based on ammonium nitrate and / or sodium nitrate and / or calcium nitrate at a flow rate of 25 to 300 Kg / min. (min = minute), preferably from 100 to 150 kg / min., and - a so-called gaseous reactive solution with a density of 0.5 to 1.5 based on sodium nitrite and / or sodium thiocyanate, at a flow rate of 0.1 at 2 L / min; in a reagent / matrix flow ratio varying from 0.1 to 2 L / 100 kg of the proportion. More particularly, when the downstream end of the first pipe is worn and / or damaged, the following steps are carried out: a) said first mixer is removed from said first pipe, b) the downstream end of the first used pipe is cut off and (c) replacing said first mixer within said first pipe, (d) disassembling said upstream end of said first pipe, and extracting an upstream portion of said second pipe and disassembling a first upstream portion of the second portion downstream of a second flexible hose, and e) exiting the first pipe and shortening said second downstream portion of the second flexible hose, then it is placed in said first pipe and connected to again to the upstream portion of the second pipe remained inside a rigid upstream portion of the first pipe. Other features and advantages of the present invention will emerge more clearly on reading the following description, given in an illustrative and nonlimiting manner, with reference to the appended drawings, in which: FIG. 1 represents a mobile manufacturing unit of explosives 1 (abbreviated "UMFE") namely a truck 1 carrying the equipment of the installation according to the present invention on its rear frame la, and - Figure 1A represents the deployment of a set of coaxial pipes 6 unwound from a reel 5 at the rear of said truck, and - Figure 1B shows a sectional view of a borehole 11 made in a rock mass 15 in which the explosive product 10 is deposited, the open down end of the assembly of coaxial pipes 6 according to the invention arranged in the hole, and - Figure 2 shows a diagram of the equipment of the installation according to the present invention for the implementation of the method according to the invention, and - Figure 3 shows the detail of a perspective view of the reel 5, and - Figure 3A shows a vertical sectional view at the first rigid portion 61a of the outer pipe 61 of the set of coaxial pipes 6, and - FIGS. 4A and 4B are sectional views of a said first connection piece 3 and two sets of rotary joint joints 41 and 42, and FIG. 4C is a view showing mounting said second gasification reagent transfer pipe 62 or inner pipe 62 to said first connecting piece 3 and the second rotating joint fitting 42, and FIGS. 5A, 5B and 5C show various views relating to the introduction of the first static mixer 7 inside and at the downstream end of the first pipe 61 downstream of the valve 64 of the downstream end 64 of the second pipe 62. Detailed description An installation 1 for the production of explosive products 10 in situ to di At the site of use of the explosive, namely, more precisely at a borehole 11 according to the invention, comprises the following equipment arranged in the following manner: a truck 1 supports on its chassis rearward the first tank 1-1 containing a product consisting mainly of an explosive emulsion called "matrix", and 20 - a second tank 1-2 containing a gasification reagent, especially based on sodium nitrite and thiocyanate, and a third reservoir 1-3 containing a reaction catalyst, namely an acid, especially acetic acid, for catalyzing the reaction of the matrix with the gasification reagent to release a gas as described below, and - a fourth water tank 1-4, and - a fifth tank of nitrates 1-5.

The truck 1 also supports on its chassis the following different pumps: a first pump 2-1 disposed at the outlet of the first tank 1-1 and intended to transfer the matrix of the first tank 1-1 towards the borehole 11 by the intermediate of a first circuit comprising a matrix transfer pipe la and a set of coaxial pipes 6 described below, and - a second pump 2-2 disposed at the outlet of the second tank 1-2 for transferring the reagent of gasification from its second reservoir 1-2 in a second circuit comprising a reagent transfer line lb to the set of coaxial pipes 6 as described below, and - a third pump 2-3 for transferring the catalyst from its reservoir 1-3 into the first reservoir 1-1, and - a pump 2-5 and / or extraction screw for transferring the nitrate of the fifth reservoir 1-5 to said first reservoir 2-1 - a pump 2-4 for transferring water from the fourth reservoir 1-4 in a circuit 1c to the first transfer circuit 1a of the matrix so as to lubricate the viscous product constituted by the matrix and facilitate its transfer within a first transfer pipe 61 as described below. The junction of the water circuit lc on the first matrix circuit la is by a piece ld called "lubrication water injector ring". The function of the water is only the lubrication of the matrix for a reduction of the losses of charges. The pipe constituting a first matrix transfer circuit connects the first tank 1-1 to a first external hose 61 of the hose assembly 6 wound on a reel 5. And the second gasification reagent transfer circuit 1b comprises pipes from the second reservoir 1-2 to a second internal gasification reagent transfer pipe 62 of the pipe assembly 6 wound on the reel 5. The second pipe 62 is disposed inside the first 61 and is positioned substantially coaxially inside the pipe 61 when due to the flow of matrix passing in the annular space between the first pipe 61 and the second pipe 62 when transferring said matrix to the hole of drilling 11. The truck 1 also supports a static mixer called "second mixer" static 2-6, upstream of the set of coaxial pipe 6. The truck 1 also supports on its chassi s back of the valves comprising: - a first valve V1 at the outlet of the tank 1-1 mounted on the first pipe transfer the matrix transfer, and - downstream of the first pump 2-1, a second valve V2 at the outlet of the second gasification reagent transfer tank 1-2 cooperating with the second gasification reagent transfer circuit lb upstream of the second pump 2-2, and - an isolation valve 1-2a upstream of the second reactant reservoir. gasification 1-2, and a third valve V3, a three-way valve for supplying a bypass line lb-1 of the second gasification reagent circuit lb connected to the first matrix transfer pipe 1a downstream of the first valve V1 but upstream of said second static mixer 2-6. Upstream of the second mixer 2-6 is connected an air injection bypass 1, joining the first circuit 1a of the matrix downstream of the first valve V1. It is thus possible, by sending compressed air, to clean the assembly. circuit downstream, at will, especially between two uses. The truck 1 also supports on its rear chassis the central control unit 9 comprising a keyboard 9a and / or a graphic interface 9b, cooperating with software capable of controlling the actuation of said pumps and said valves. Downstream of the third valve V3, the gasification reagent transfer circuit 1b joins the first matrix transfer circuit 1a downstream of the second mixer 2-6 at a connecting part referred to as the first connecting piece 3 which ensures the connection between the first pipe 1a and the second pipe 1b just upstream of the set of coaxial pipes 6 wound on the winder 5, so that the flow of gasification reagent is transferred into the second inner pipe 62 and the matrix flow from the first circuit is transferred inside the first pipe 61 and outside the second pipe 62 into the annular space between the inner wall of the first pipe 61 and the second pipe 62, as described herein. -after. The valve V3 makes it possible, by forcing the circulation of the gasification reagent to the shunt lb-1, to obtain a first mode of operation of the plant according to a traditional method in which the gasification reagent and the matrix are mixed within the mixer. 2-6 upstream of the set of transfer pipes 6 to the borehole 11. In this traditional embodiment, the explosive product 10 produced within the mixer 2-6 is conveyed over a long distance, that is to say along a long pipe joining the borehole 11. The chassis 1 of the truck 1 also supports upstream of the second pump 2-2 and downstream of the second tank 1-2 a filter 2- 5. Furthermore, the frame also supports it: downstream of the second pump 2-2, a flowmeter 2-2a of the variable section type, as sold by the company KROHNE (FR) under the reference H250 / RR / MXX / ESK, the second pump 2-2 being of the piston type in particular as sold by the company CAT PUMPS (USA) under the reference CAT2XX, and - a speed sensor 2-la of the rev counter type mounted on the hydraulic motor of the pump as sold by the company DANFOSS (FR) under the reference 151-5662 indicating the speed of rotation of the first pump 2-1, the first pump 2-1 being a so-called progressive cavity volumetric pump driven by a hydraulic motor of the type sold by Danfoss under the reference for example OMS160EM151F-3023. More particularly, the pump sends pulsed signals according to a known determined number of pulses per revolution to the speed sensor 2-la so that the quantity of product delivered by the pump can be known, by calibration according to the number of turns. of said first pump.

Downstream of the first pump 2-1, are also mounted on the first circuit 1-a different sensors namely, a matrix fluid pressure sensor la-1, a temperature sensor la-2, and a detection sensor no flow rate of matrix flow la-3. In fact, the pressure of the matrix flow in the pipe 1a must not exceed 20 bars and the temperature must remain below 70 ° C for safety reasons, at the risk that the explosive emulsion becomes too sensitive. Indeed, the explosive emulsion becomes more sensitive to rapid decomposition when the pressure and the temperature increase. To better understand this risk, the limit pressure of 20bar was determined using a specific safety device called MBP ("Minimum Burning Pressure"). A device 2-2b cooperating with the second pump 2-2 is a safety valve used to lower the pressure when the pressure is above a threshold level.

According to an original feature of the present invention, a second gasification reagent transfer pipe is disposed within a first die transfer pipe 6-1, to form a pipe assembly 6 according to the following arrangement. The two independent matrix transfer pipes 1a and transfer gasification reagent 1b meet at a first original connecting piece 3 according to the present invention described in FIGS. 4A, 4B and 4C. The first connecting piece 3 comprises a main sleeve with an outer cylindrical wall 3a open at its upstream ends 31a and downstream 31b thus forming a first inlet orifice 31a with a circular section upstream and a first outlet orifice 31b downstream with a circular section. , both arranged along a longitudinal axis XX 'of said envelope 3a. The first inlet port 31a has a thread 33a so that the threaded end of a threaded connection threaded at the downstream end of the first matrix transfer pipe 1a can be screwed into it. At the downstream end of the first connection piece 3, the upstream end of the first pipe 61 and the upstream end of the second pipe 62 are coaxially mounted on first coaxial outlet openings 31b and 32b respectively. downstream end of said first connecting piece 3 via a first rotary joint connection 41 and respectively a second rotary joint connection 42. The first outlet orifice 31b has a threaded outer surface 33b on the outer surface of the downstream end of the cylindrical casing wall 3a on which can be screwed the female end of a first rotary joint connection 41 whose downstream end comprises an external peripheral thread 41c on which a female connector 61c1 will be screwed to the upstream end of a first rigid portion 6-la of the first pipe 61.

FIG. 4B shows the known structure of this type of first rotary joint coupling 41 comprising sealing O-rings 41d and ball bearings 41e ensuring the cooperation between two tubular pieces 41a and 41b juxtaposed in the axial direction. XX '. Said first piece 41a has an upstream female end screwed onto the external thread 33b of the male end of the part 3 forming the first outlet orifice 31b. A second part 41b of the first swivel joint coupling 41 comprises at its downstream end, the external thread 41c cooperating with the end fitting 61d of the first pipe 61. The 41e ball bearings 41d and O rings allow the rotation of the first rotary part 41b of the first rotary joint connection 41 around the common axis XX 'of the first connection piece 3 and the rotary coupling 41 with respect to the first fixed portion 41a of the rotary joint connection 41. Thus, the upstream end of the first pipe 61 can rotate on itself in case of torsion during its winding on the reel 5 as described below. The envelope wall 3a contains an internal bent piece 3b having a first tubular portion extending in a direction perpendicular to the longitudinal axis XX 'of the wall 3a and defining a second inlet orifice 32a passing through said wall 3-a and on which is screwed the threaded end of a terminal connector lb 'of the second conduit lb of gasification reagent feed. The bent part 3b also comprises a tubular part arranged axially in the interior of the part 3 and forming a second outlet orifice 32b on which is screwed a first upstream fixed part 42a of a second rotary joint fitting 42 comprising a second part Rotary swallow 42 juxtaposed in the axial longitudinal direction XX '. Said first upstream part 42a cooperates with the second downstream part 42b by seals and ball bearings (not shown), allowing the rotation of said second part 42b of the second rotary joint ratio 42 around the axis XX '.

The upstream end of the second pipe 62 is fixed on said second rotary part 42b of the second rotary joint connection 42, via an end fitting piece 62c. It is possible to use rotary joint fittings of reference TP 1100M / F marketed by PACQUET INDUSTRIE (France). The first connecting piece 3 and the two rotary joint connections 41 and 42 are arranged just upstream of a drum drum 5 supported by a structure or beam 5a. On the winding drum 5, a downstream flexible portion 61b of the first pipe 61 is connected to an upstream rigid portion 61a by a removable collar 61c. The upstream rigid portion 61a of the first pipe 61 secured to both the first connecting piece 3 via the first rotary joint connection 41 and also integral with the winding drum 5 is thus rotated with the winding drum 5 about the axis. common rotation of the winding drum 5 and said joints with rotating joint 41 and 42 and the connection piece 3. The rigid portion 61a has different bends, so that its upstream portion is arranged in the axial direction XX 'of the first connecting part 3 while its downstream part at the collar 61c is arranged in a tangential direction of a cylindrical portion 51 of the drum drum 5 on which can be wound the second flexible portion 61b of the first pipe 61 when actuated in rotation the drum drum 5. The second pipe 62 disposed inside the first pipe 61 but has two flexible portions 62a and 62b connected to each other by a coupling to double union 63. This double union connection 63 is of the type well known to those skilled in the art such as for example a double union connection reference 55-400-6 marketed by the company SWAGELOK (USA) also called under the name "tube fitting". This type of double union connection 63 cooperates with end connection pieces 62d and 62e respectively at the ends of the first upstream and downstream flexible portions 62a and 62b of the second pipe 62. The double union 63 is located just downstream of the collar 61c so that when opening and / or removing the collar 61c to separate the two first pipe portions 61a and 61b, the second pipe 62 can be withdrawn and the two parts 62a and 62b of the second pipe 62 uncoupled and thus easily shortened as far as necessary the downstream portion 62b when it has previously been brought to shorten the worn down end of the flexible portion 61b of the first pipe 61 as described below.

The downstream end of the second pipe 62 comprises an anti-return valve 64, for example of the type marketed by Swagelok under the reference SS-4-HC-1-4. The valve 64 is located as close technically as possible to the upstream end of a first static mixer 7 disposed at the downstream end of the first pipe 61. The valve 64 opens under the pressure of gasification reagent passing through the pipe 62 when the pump 22 is running; and the valve 64 closes when the second pump 2-2 stops and the gasification reagent flow pressure ceases at the stop of the second pump 2-2. As shown in FIG. 4C, the valve 64 is connected to a fitting 62f at the downstream end of the inner pipe 62 by a second double union connection 64a. For the flexible portion 61b of first pipe 61, it is possible to use a thermoplastic hose with an external diameter of 42 mm and an internal diameter of 32 mm, 30 to 100 m long. For the second pipe 62, thermoplastic pipes of external diameter of 13.2 mm and internal diameter of 8.3 mm will be used. The first mixer 7 consists of eight helical surface fins 7a juxtaposed in the direction XiXi 'of the first mixer and the first hose 61, on a rod 7b. The rod 7b forms corrugations so that the entire surface of each helical fin is fixed on said rod in the longitudinal direction X1X1 'of the first pipe 61 and the first mixer 7 inserted inside the first pipe 61. The rod 7b is thus corrugated so as to follow the contour or the = profile of the helical elements 7a. The rod 7b thus constitutes a reinforcement of this type of fixation.

The fins 7a are juxtaposed against each other in the longitudinal direction X1X1 ', but the different portions of helical surfaces are not helically continuous, that is to say they are angularly offset in order to optimize the performances said mixer in particular shifted at 900 successively relative to the axis X1X1 '. The addition of the rod 7b supporting the helical fins 7a is an original feature of the present invention because under the conditions of implementation inside a small diameter pipe according to the present invention, the static mixer is under pressure. important. And it has been found that in the absence of support rod, a simple welding at the ends of the fins 7a to keep them connected together as in the prior art is insufficient. Specifically, the helical elements have a diameter of substantially 30mm, a helical surface thickness of about 2mm, a length of about 50mm and an angular offset of about 90 °, the total length of the mixer being about 400mm. The flow of gasification reagent leaving the valve 64 and the flow of matrix arriving at the valve 64 outside thereof, can mix intimately at the first mixer 7, by the helical shape of the fins whose diameter is just smaller than the inner diameter of the first pipe 61. Preferably, the different helical elements are successively reversed. The flow of material through the static mixer in the longitudinal direction X1X1 'becomes laminar and is divided into partial streams by a first helical element 7a, then redivated to the passage of a next helical element 7a and so on. The rotation of the product caused by the shape of the helical modules 7a accentuates the mixing phenomena. In principle, the helical elements 7a are not themselves in motion and in any case, no source of power is required other than that provided by said pumps to overcome the pressure drop induced by the baffles that form the successions of said helical elements 7a. According to an original feature of the present invention, the downstream end of the first pipe 61 downstream of the first static mixer 7 is equipped with a stop 8 having a threaded outer surface 8a adapted to be screwed against the inner wall 61e of the end. downstream 61f of the first pipe 61. The explosive product fluid obtained by mixing the matrix and the gasification reagent within the first static mixer 7 can flow through a central cylindrical orifice 8b of the abutment 8. As shown in FIG. 5C, a key 81 having lugs 81a cooperating with notches 8b1 at the periphery of the downstream end of the abutment 8 which allows to screw and unscrew the abutment 8 at will. The central orifice 8b of the abutment piece 8 allows wide passage of the explosive product and avoids undesirable effects that may result from an increase in the nuisance pumping or blocking pressure related to the accumulation of explosive products at this level. . In practice, the inner diameter of the central opening of the abutment piece 8 is about 20 mm.

The stop 8 has the essential function of holding the static mixer 7 within the downstream end of the first pipe 61. The unscrewing of the stop 8 makes it possible to remove the first mixer 7 from the downstream end of the first pipe 61 and thus to ability to cut the downstream end of the pipe 61 when it is damaged after a number of uses because the outer surface of the downstream end of the pipe 61 in contact with the walls of the drill holes 11 consist of rock mass 15 tend to damage the downstream end of the pipe 61 during the operation as described hereinafter. It is also possible to remove the first mixer 7, if it is not desired to implement a method according to the invention varying the density of the explosive product produced continuously during a production cycle. In this case, the second pipe 62 is removed from the inside of the first pipe 61 by uncoupling at the collar 1c as described above or by disconnecting the pipe 1b and closing said second inlet port 32a with a plugging and orienting the three-way valve V3 so that all the gasification reagent passes through the pipe 1b1 and mixes with the matrix flow upstream of the second mixer 26. At the outlet of the second mixer, the explosive product is transferred via the conduit 61 to a borehole in which the downstream end 61f of the pipe 61 is disposed.

The static mixer 7 in practice extends over a length of 0.5 to 1 meter so that the explosive product produced is in reduced quantity inside the first hose 61. Thus, it is possible to vary the composition. and therefore the density of the explosive product 10, almost continuously and in real time at the outlet of the pipe 61 by adapting the relative proportions of flow and / or composition of gasification reagent and matrix transferred in said first and second pipes, as described in the explosive product production process described hereinafter. Advantageously, a method according to the invention is used in which the density of the explosive product produced continuously is varied during the filling of a borehole 11 in a single pass, that is to say, without having to raise the pipe 6 during filling, as described below. The emulsion consists of the following components: - mineral oil and / or engine oil: 6.5 ° / (:), - gas oil: about 1%, - nonionic surfactants: 1%, - ammonium nitrate and / or calcium and / or sodium: about 75%, - water: about 15 to 20 ° h.

To the above emulsion thus obtained, ammonium and / or calcium nitrates are added in a proportion of 15 to 35% and a catalyst for example of acetic acid in a proportion of 0.5 to 2%. which can also be added aluminum (in the form of powder particle size between about 100pm and 2mm) in a content of 1 to 10 ° by weight also. This matrix is thus obtained according to the present description within the first reservoir 1-1. An example of a matrix formulation is therefore: - mineral oil and / or motor oil: 4.55%, - gas oil: 0.7% - surfactants: 0.7% - ammonium nitrate in solution: 52.5% - water: 11.55% solid ammonium nitrate powder: 30% To this matrix, is added according to the process of the present invention, a gasification reagent which is here in particular an aqueous solution of about 20% of sodium nitrite and 80% of water may include catalysts such as sodium thiocyanate, sodium formate, zinc nitrate and / or calcium nitrate. The method of sensitizing the matrix consists of a chemical reaction between said gasification reagent and the ammonium nitrate contained in said matrix. This chemical reaction releases a gas, in this case nitrite reacted with nitrate to form nitrogen gas, which generates sensitization of the product by the creation of "hot spots", that is to say interstices in the mixture product allowing the propagation of the shock wave, therefore the detonation of the explosive product. The product is therefore explosive because of this sensitization. The increase in the quantity of gas bubbles decreases the density of the product and therefore the explosive energy obtained for a constant volume of hole (volume energy). The density of the basic emulsion (not supplemented) described above is for example about 1.4 to 1.6 and the density of the supplemented emulsion defining said matrix as described above, before mixing with the gasification reagent is 0.8 to 1.3. The density of the gasification reaction mixture product within said first mixer is from 1.25 to 1.45 according to the respective proportions of quantities and / or flow rates of said matrix and said gasification reagent and the density of the explosive product after gasification. is from 0.8 to 1.2. The average energy of an explosive product of density 1.2 is 3.7 MJ / kg, ie 4.44 MJ / L. Thus, for an explosive product with a density of 0.5 to 1.5, the explosive energy will be 1.85 to 5.55 MJ / L. For a Y gasification reagent rate in L / min (product / liquid) as a function of a matrix flow X in kg / min of viscous product, the relation Y = aX + b is given by charts with values of a and b different according to the density values d of the explosive product obtained after gasification resulting from the reaction between said matrix and the gasification reagent by intimate mixing within the static mixer. Thus, the different values of a and b are, for example, here: for d = 0.8, Y = 0.0117 × + 0.002, and for d = 0.9, Y = 0.0085 × 0.0012, and - for d = 1, Y = 0.006X, and - for d = 1.1, Y = 0.0039X + 0.0019, and - for d = 1.2, Y = 0.0021X.

There is therefore a linear relationship between X and Y depending on the final density of the explosive product resulting from the reaction by intimate mixing of the two products. The automated control and control unit 9 makes it possible to control the proportional valves V1 and V2 regulating the flows of matrix and gasification reagent, and the actuation and speed of the motors of the pumps 2-1 and 2-2. The flow rates X and Y are provided by calibrating the pump 2-2 speed sensor 2-2 for the values of X (kg / min) and by the flow meter 2-2a for the gasification reagent Y flow (L / 2). min). In practice, since the gasification reagent R2 is in a smaller quantity and in liquid form it is easier to control the flow rate so that it operates with a constant matrix flow X = 125 kg / min.

Thus, the operator driving the selected plant will select the desired explosive product densities as well as the corresponding quantities for each density based on his needs analysis in the relevant borehole given the surrounding rock mass environment. the hole to be felled. X being constant, the flow rate of gasification reagent is determined automatically from the chart according to the desired density. In practice, for each blast hole 11, the operator will choose up to four different densities called dl, d2, d3 and d4. The densities d1 to d4 of explosive products to be produced and the corresponding quantities are entered at the level of the central unit 9 via a touch pad 9a appearing on the screen of the graphic interface 9b. The operator can then start a pumping cycle. The centralized and automated control unit 9 then automatically controls the regulation of the flow and therefore the flow rate of reagent R2 for a given matrix flow M. Thus, for example, the production cycle of a cylindrical hole 20 m deep and 115 mm in diameter will be performed as follows for a supplemented matrix having a density, in the example below, of about 1.3 20 kg of explosive products of density 1.2 are charged at a value of 0.21 L / min with, for example, a gasification reagent flow rate of 0.21 L / min, and the set point is changed and ordered to load 25 kg of explosive product 10 of density 1 which will therefore be deposited on top of the 20 kg of 1.2 density explosives previously deposited at the bottom of the hole from the downstream end of the pipe 61, putting for example, a gasification reagent flow rate of 0.60 L / min; 50 kg of explosive products with a density of 0.9, above the explosive product previously deposited, using for example a gasification reagent flow rate of 0.80 l / min, then loaded at the top. of the column, 30 kg of explosive product 10 of density d = 0.8, obtained by transferring, for example, a gasification reagent flow rate of 0.90 L / min. The automated central unit 9 thus makes it possible to control and control the gasification reagent flow rate values as described above simply by adjusting the speed of the hydraulic motor of the second pump 2-2 transferring the gasification reagent, and now a substantially constant flow rate of 125 kg / min of said matrix. Such control and flow regulation of the gasification reagent makes it possible to vary, almost in real time, the product density value obtained at the outlet of the first static mixer 7 and discharged directly into the borehole, because of the automation. the control and regulation of the flow of gasification reagent by the central unit 9.

The CPU 9 may offer additional advantageous features such as the import and export of data, instructions and results in terms of quantity, throughput and density. The method according to the invention is also advantageous in that it generates an improvement in terms of safety, the mixture product becoming explosive only at the end of the flexible hose 61, thus avoiding the transport over a long distance of dangerous product to the inside the pipe. The coaxial introduction system of the gasification reagent to bring it into contact with said matrix promotes a faster and more efficient intimate mixing of the two components, which induces, not only: the possibility of optimally varying in real time the density of the product obtained in mixture with the matrix, but also - the improvement of the safety of the process and finally, - a greater mechanical reliability of the installation insofar as no material is required outside the explosive product removal pipe may be in contact with the other components necessary to generate the explosion that is the ignition charge 12, the detonator 13 and especially the detonator wire 14 which is often a source of accident in case of shock metal products nearby. With regard to the variation of the density of the product obtained almost in real time, it should be observed that the quantity of product contained within the downstream end of the pipe 61 is limited to the explosive product produced gasified in the second downstream portion of the static mixer, or for a mixer 50 cm long in a pipe 61 32 mm in internal diameter, an amount less than 0.5 kg of a relatively negligible value compared to the amounts of explosive products of different densities that it is necessary to introduce, one can thus consider that the variation of density is thus obtained almost in real time by modification of the ratios of flow of reagent of gasification and matrix. The measurement of the density can be carried out by weighing in the open air in a calibrated pot of known volume.

The process for producing a variable density explosive product according to the present invention therefore consists in varying the gasification of the explosive product in the blasthole, in a manner that is almost instantaneous in order to obtain a differentiation of the density of explosive product in the column. within the borehole, while performing only one loading pass.

Claims (17)

REVENDICATIONS1. In-situ explosive product production system (10) by mixing (a) a viscous product, referred to as a matrix, comprising an inverse emulsion of an aqueous oxidant phase and an oily fuel phase and (b) a liquid product containing a a chemical compound capable of reacting with said matrix to increase its explosive character by gasification, called a gasification reagent, said installation comprising at least: a first reservoir (1-1) containing said matrix based on said explosive emulsion, and - a second reservoir (1-2) containing said gasification reagent, and - a first transfer circuit (1a) of said matrix comprising at least a first hose (61) at least partially flexible cooperating with a first pump (2 -1) and a first valve (V1), able to transfer said matrix separately to a first mixer, preferably a first static mixer (7), and - a second transfer circuit (lb) t of said gasification reagent comprising at least a second pipe (62) at least partially flexible cooperating with a second pump (2-2) and a second valve (V2), able to transfer said gasification reagent separately until said first mixer (7), characterized in that said second pipe (62) is disposed entirely inside the first pipe (61) forming an assembly (6) of coaxial pipes, said first mixing device being arranged at the the interior of the first pipe at its downstream end (61f), said second pipe terminating just upstream of said first mixer. 2. Installation according to claim 1, characterized in that the set of coaxial pipes (6) is connected to a drum drum (5), and is wound at least partially or able to be wound on said drum drum, the end downstream of the set of coaxial pipes (6) being disposed in or above an explosion hole (11), preferably a substantially cylindrical borehole in which an explosive initiation charge has been placed ( 12) and a detonator (13) connected at the surface by a detonator wire (14). 3. Installation according to one of claims 1 or 2, characterized in that said first and second pipes are connected coaxially to each other at their upstream ends by a first connecting piece (3) comprising a sleeve to outer cylindrical wall (3a) and an inner bent piece (3b), said first connecting piece being preferably integral with a drum drum (5) on which is wound at least in part or able to be wound up said set of coaxial pipes, said first connecting part comprising: - a first inlet orifice (31a), forming an upstream opening of said sleeve and disposed axially in a longitudinal direction (XX '), the cylindrical wall of said sleeve, said first orifice of inlet being connected to a portion, preferably a rigid portion, of said first transfer circuit of said die, and - a second inlet port (32a) disposed laterally at the cylindrical wall said sleeve, forming an upstream opening of said bent piece (3b) passing through the cylindrical wall of said sleeve and disposed perpendicularly to said longitudinal direction (XX '), said second inlet being connected to a portion, preferably a rigid part, of said second transfer circuit of said gasification reagent, and - a first outlet orifice (31b), forming an opening downstream of said sleeve and arranged axially in said longitudinal direction (XX ') of the cylindrical wall of said sleeve, said first outlet orifice being connected by a connection (41) to the upstream end of said first transfer pipe (61) of said matrix, preferably to a rigid portion (61a) of said first pipe upstream of a said winding drum and a second outlet orifice (320, disposed axially in said longitudinal direction (XX ') of the cylindrical wall of said sleeve, forming an opening downstream of said bent piece (3b) within said sleeve, said second outlet being connected by a connector (42) to the upstream end of said second transfer pipe of said gasification reagent. 4. Installation according to claims 2 and 3, characterized in that the fixing of the upstream ends of said first and second pipes on said first and second outlets of said first connecting piece is via two first and respectively second joints rotary joints (41,42) allowing each separately the rotation on itself with respect to said longitudinal axis (XX ') of the upstream ends of said first and second pipes respectively, said first connecting piece and said connectors to rotary joints being disposed upstream of a said winding drum so that said so-called first and second outlet are disposed in the axis of rotation of said drum. 5. Installation according to one of claims 1 to 4, characterized in that said second pipe (62) comprises at its end downstream, inside said first pipe, a valve (64) adapted to open and leaving the flow of said gasification reagent under the pressure of said flow when the second pump is actuated and able to remain closed and prevent leakage of gasification reagent when the second pump is deactivated. 6. Installation according to one of claims 1 to 5, characterized in that: - said first pipe comprises at least a rigid portion bent (61a) of first pipes assembled to a flexible portion (61b) of first pipe tightly and reversible by a collar (61c), disposed upstream of said drum and secured thereto and adapted to be rotated about the axis of rotation when said drum is actuated in rotation, said flexible portion of first hose being fit to be wrapped around said drum, and - said second pipe comprises two flexible portions (62a, 62b) interconnected between such by a rigid and reversible connection of the double union type (63) arranged, the flexible portion (62a) of said second pipe disposed upstream of said double union type connection (63) being shorter than the flexible portion of said second downstream pipe (62b), said double union type connection being preferably at least of the said collar. 7. Installation according to one of claims 1 to 6, characterized in that a hollow tubular abutment (8) comprising a longitudinal central opening (8b) is removably disposed at the downstream end of the first pipe to retain the said first mixer inside the first pipe by passing the explosive product through the central opening (8b) of said stop, a thread (8a) on a cylindrical outer wall for screwing and thus removably fix said stop against the inner wall (61e) of said first pipe, preferably using a screwdriver (81) adapted to cooperate with the downstream end of said longitudinal central opening for screwing inside said first pipe or unscrewing the said stop to take it out of said first pipe. 8. Installation according to one of claims 1 to 7, characterized in that said first mixer (7) is a static mixer comprising a plurality of fins (7a) each having a helical surface, preferably extending in its axial direction over a length corresponding to a pitch of the corresponding helical curve, said helical surfaces being supported by a same reinforcing rod (7b) to which they are attached juxtaposed in the longitudinal direction of said first pipe, said helical surfaces successive ones being angularly offset in rotation with respect to their common virtual axis of helical surface coinciding substantially with a longitudinal axis of said first pipe coaxial axis with said first pipe, the diameter of said helical surfaces being substantially identical or just sufficiently smaller than the diameter internal of the first pipe to allow rotation of the di your fins under the effect of the pressure of the flow of matrix and reagent mixed through them. 9. Installation according to one of claims 1 to 8, characterized in that an automated central control and control unit (9) comprising electronic means controlled by software with a keyboard / or graphical interface, allows control and controlling the respective quantities and flow rates of said matrix and / or preferably said gasification reagent, and varying the density of the explosive product obtained, by controlling and controlling first and / or second valves and / or controlling the speeds of said first and or second pump, preferably said central unit being supported on a motor vehicle (10), preferably said vehicle supporting said first and second tanks and said first and second pump. A method for producing an explosive product in situ (10) using an installation according to one of claims 1 to 9, comprising the steps of: 1) transferring a viscous product from said matrix, and a liquid product of said gasification reagent, in said first and second coaxial pipes, and 2) mixing said matrix and said gasification reagent in a said first mixer, and 3) depositing said explosive product at the outlet of the said first mixer, in an explosion hole (11), preferably a substantially cylindrical borehole having previously placed an explosive charge (12) and a detonator (13) connected to a detonator wire (14) rising to the surface. 11. Process according to claim 10, characterized in that the quantities and / or flow rates of said matrix and of said gasification reagent are controlled and controlled so as to produce an explosive product of determined density at the output of the first mixer. 12. Process according to claim 11, characterized in that the density of the explosive product obtained during filling is varied according to the quantity of explosive product deposited and / or according to the depth at which the explosive product is deposited in the same hole. from one hole to another in different holes. 13. The method of claim 12 characterized in that one chooses and controls specific amounts of explosive products having different density values respectively determined to deposit successively in a hole being filled, preferably continuously. 14. The method of claim 12 or 13, characterized in that in step 1), said matrix and said gasification reagent are separately transferred from said first and second reservoirs respectively into first pipe and respectively second pipe cooperating. with a first pump (2-1) and a first valve (V1) and respectively a second pump (2-2) and a second valve (V2), and a constant flow rate of said matrix is controlled and controlled by controlling the speed of the first pump (2-1) and / or the opening of said first valve (V1), and the flow rate of said gasification reagent is varied by controlling the speed of the second pump (2-2) and / or the opening of said second valve (V2). 15. Method according to claim 14, characterized in that a constant flow rate of said matrix is controlled and controlled by controlling the speed of the first pump (2-1) with the aid of a speed sensor (2-la). ) of said first pump, and the flow rate of said gasification reagent is varied by controlling the speed of the second pump (2-2) with a flow meter (2-2a). 16. The method of claim 10 to 15 characterized in that implements: a said density matrix of 1 to 1.7 of a so-called inverse base emulsion or "water in oil" obtained by a mixture of (a) ) an organic continuous phase consisting of a mixture of mineral oils and gas oil, and (b) a discontinuous aqueous phase of various oxidizing salts in aqueous solution based on ammonium nitrate (s) and / or sodium and / or calcium, with a flow rate of 25 to 300 Kg / min - a so-called gaseous reactive solution with a density of 0.5 to 1.5 based on nitrite and / or sodium thiocyanate, at a flow rate of 0.1 to 2 L / min; in a reagent / matrix flow ratio varying from 0.1 to 2 L / 100 kg of the proportion. 17. Method according to one of claims 10 to 16 characterized in that the following steps are carried out, when the downstream end of the first pipe is worn and / or damaged: a) said first mixer is removed from said first pipe b) the downstream end of the first worn and / or damaged pipe is cut off; c) the first mixer is placed inside the said first pipe; and d) the upstream end of the flexible part of the first pipe is disassembled. pipe, and an upstream portion of said second pipe is removed and a first upstream portion (62a) of second downstream portion (62b) of second flexible pipe is disassembled, and e) the first pipe is withdrawn and the second downstream portion is shortened ( 62b) of second flexible pipe, then it is replaced in said first pipe and is connected again to the upstream portion of the second pipe remained inside a rigid upstream portion of the first pipe.