NO124451B - - Google Patents

Description

Method and apparatus for processing

of a geological mass by drilling and blasting.

The invention relates to a method for the processing of

a geological mass by drilling and blasting, whereby one or more holes are drilled in the mass and a charge of concentrated secondary explosive is placed in each of the holes, and where the processing takes place by causing the charge or charges to detonate. The invention further relates to an apparatus for carrying out the aforementioned method, comprising a drilling device in the form of an elongated part with a drill bit at one end, and an explosives feeding device for supplying explosives to a hole drilled by the drilling device, which feeding device contains a pipe with a discharge end and a feed end.

The different methods of drilling and blasting have

has long been an effective tool for carrying out useful work,

as they provide the necessary energy, e.g. for excavation operations of various kinds, i.e. operations where the material is excavated and removed at or below the earth's surface, either to form a useful cavity, e.g. when drilling tunnels, or to produce yield from the removed material, e.g. in mining, The explosive energy produced by drilling and blasting processes has also been used for other purposes, e.g. by seismic surveys to obtain information regarding the location of useful geological layers, such as gas- or oil-bearing layers. IN

in our time, there is an ever-increasing need for investigation and excavation operations, and especially for excavations underground, e.g. in the construction of water and vehicle tunnels, car parks or military defense facilities, and for the exploitation of very large mineral deposits with regard to nature conservation standards. However, a considerable cost reduction and increase in the sustained work speed is necessary, e.g. tunnel progress, if investigations and excavations are to be used effectively to meet the challenges in connection with urbanization and conservation of the natural resources.

With the conventional drilling and blasting method when processing or excavating a geological mass, such as rock, holes are first drilled in a predetermined pattern in the rock. After all holes have been drilled, a charge of secondary explosive is placed in the holes, usually manually, and an ignition device, that is, a fuze cap or fuze cap, is placed in contact with the charge in each hole, or with a detonating fuse leading to the charge and connected with a remote common trigger device, such as a detonator. The charge is then ignited by energizing the igniter. During underground excavation work, a venting period is necessary to remove fumes and dust caused by the blasting and carried through the air. After this venting or "smoke time", the round or cycle ends with the unloading operation, i.e. the loading and transport of the crushed material (explosive mass) from the excavation to a placement area. The described cycle is then repeated.

In recent years, mechanical excavators or 'mole' have been developed which can bore a tunnel or shaft or excavate ore by means of a rotating cutting head driven by electric or hydraulic motors, the blasting mass being taken up by a wheel which empties the mass onto a conveyor belt which takes it backwards to a place behind the machine. At their current respective levels with respect to technological development, the mechanical excavators have greater operational capacity per day in loose and semi-solid rock than the drilling and blasting method. This is mainly due to the fact that the mechanical method involves an almost continuous operation, although delays occur due to changes in geological conditions, mechanical and electrical faults and the necessity of frequent cutting head replacements and so on.

However, serious limitations exist with respect to the use of mechanical excavators. One of these is that they cannot be used effectively in hard and/or abrasive rock, e.g. rock with a compressive strength of more than approx. 1000 kg/cm 2, or a hardness which, according to Moh's scale, is greater than approx. 5. Mountains of this type are now encountered at approx. 1/3 of the excavation projects, and it is assumed that this percentage will increase as future public construction requirements force the excavation work to be carried out at greater depths and in areas with known hard rock conditions. Another limitation is that the initial investment in mechanical excavators is high, and consequently the use of these in many short tunnels cannot be economically justified even if the excavator would be technically capable of drilling the tunnel. Furthermore, it is usually necessary to invest in a new excavator for each mechanical tunneling project as the different diameter requirements and geological conditions encountered from project to project make it necessary to design a machine for each individual tunnel, although machines that has been used in completed projects may still have a certain lifespan. When it comes to mining operations, continuous mining machines are sometimes too large and unwieldy to allow efficient mining of narrow ore veins. For the reasons stated above,

the drilling and blasting method for excavation work is the preferred method for many operations these days.

As it is now practiced, however, the drilling and blasting method of excavation has inherent delays in each cycle, which means that the speed of the stone advance or the operability per day, is low. The low advance speed, the need for larger work crews and the costs of materials used mean that the total excavation costs will be high. Cycle delays and high manpower requirements are inextricably linked with the methods currently used to prepare the formation for the crushing stage, i.e. the blasting, and with the environment in the work area during and after the blasting. The initial operations include moving the drilling equipment to the face, drilling the holes, moving the drilling equipment back, charging the holes with secondary explosives, placing assemblies (that is, fuze caps) containing primary explosive charges in contact with secondary explosives, or in contact with detonating fuses leading to the secondary explosive in the holes, and connecting the assemblies containing primary explosive charges with an energy source, so that a continuous energy-storing and energy-transferring circuit is formed from a remote common energy source, such as a detonator or a power line, to the secondary explosive charges. The starting energy, e.g. an electrical pulse emitted from the common energy source,1 is thus transferred to the secondary explosive through an active medium, that is, a medium containing stored energy (the primary explosive) which in turn is used to ignite the secondary explosive.

Because of the time required to drill, charge and otherwise prepare the holes for blasting, in order to achieve better efficiency it has been necessary to arrange the volleys (arrangement of drill holes on the surface) so that large cross-sectional areas of the surface are fired in one blast, e.g. the entire cross-sectional area (gable blasting method), or a large part of it (roof toll and pallet blasting method). Salvos of this size require a large number of boreholes and consequently the detonation of a large number of explosive charges. E.g. for a gable blast volley in a typical railway tunnel with a height of 9 m and a width of 7 m, approx. 400 kg of explosives are detonated in each volley. Due to the pressure and rock blasting effects of blasts of this size, the nearest blast area must be cleared of personnel and equipment. This is the reason why remote transmission of the ignition pulse, and thus connection of all the charges in an energy-transmitting circuit, has been necessary.

Large isolated explosions of the type that have

been used in the past, can cause strong ground vibrations that can be harmful to surrounding structures. In addition, such explosions produce large quantities of fumes and dust which are carried through the air and which must be blown out before personnel can enter with the unloading equipment. Generally, fans must be used for a period of at least approx. 20 min. to clear the area so that work can resume. After this "smoke time", the unloading machine is moved in, the blasting mass is transported out and the mass loader is moved.

Drilling methods have been made more efficient in recent years with the introduction of modern drilling machines, such as pneumatically driven impact drills mounted on a drill carriage or jig (a mobile working platform), and borehole loading time has been considerably reduced by the availability of such devices as a pneumatic cartridge loader with a semi-automatic tailpiece for automatically feeding cartridges into a loading tube, and a robotic loader or loading machine for moving the tube into the borehole. In order to achieve efficient utilization of equipment and manpower, it has nevertheless been necessary to use blasting with large volleys of shots, and the delays have therefore continued to be significant due to the time required for moving the drilling equipment forward to the formation to be blasted, moving the equipment back before the blasting, moving in and out of loading personnel and equipment, performing the manual operations for connecting the igniter wires (ignitor cap wires or lengths of detonating fuse or safety fuse) to form an ignition circuit for the remote triggering device, and "smoke time".

It is thus realized that the use of catch caps in a remote-triggered, comprehensive ignition circuit to ignite the charges in the boreholes during a drilling and blasting process is uneconomical in terms of consumption of time and manpower. As the fang caps are also used up during blasting, the price of these must also be taken into account. As far as safety considerations are concerned, the use of arrestor caps is also not completely without danger, as they contain a primary (extremely sensitive) main charge with secondary explosive, so that a continuous reaction train is formed from the primary explosive in the arrestor cap to the secondary explosive charge in the borehole when the arrestor cap has been placed in the ignition position. It is thus very important to ensure against accidental ignition of the incendiary charge which is located next to the primary explosive charge, both in fitted arrestor caps and in arrestor caps which are placed in a storage area or which are transferred to the charge in the borehole. In the case of electrical ignition, there is further interdependence between all the charges in a volley as soon as these have been connected, and in the event of a random voltage generation at any point in the electrical circuit, it is therefore likely that all the charges will be fired . Alongside considerations with regard to safety and material costs, however, there is another serious disadvantage to the ignition methods currently used in blasting, in that they cannot be subjected to mechanization and efficient operation with small blasting cycles. Consequently, these ignition methods represent a very significant obstacle in carrying out the drilling and blasting operations on a rapid and almost continuous basis, that is, as an essentially continuous, periodic sequence of uninterrupted drilling and blasting series, a mode of operation which is obviously the most reasonable method to reduce expenses and time consumption. Such mechanization and ice blasting operation would not only lead to a sharp increase in the efficiency of drilling and blasting operations, but also provide an effective aid for the utilization of the drilling and blasting technique by the common depth point method in seismic surveys. Particularly in areas where the surface layer (e.g. ice-blasted rock, coral formations, unconsolidated ice or tele) strongly absorbs seismic energy, according to the latter method the use of explosives in boreholes would provide signals with higher energy and information about deeper layer than the gas detonators currently in use.

The invention provides an improved method of drilling and blasting, in which secondary explosive charges are confined in boreholes in a geological mass to be processed, e.g. fjell', is ignited by rapid release in the mass of energy that is emitted to the charges in the boreholes again about an inactive medium, e.g. the atmosphere, rather than via a continuous reaction chain containing a primary explosive.

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The method according to the invention is characterized by the fact that a number of series consisting of the steps drilling, charging and blasting are carried out one after the other and essentially continuously at different places in the mass, the ignition step in each series being carried out by transmitting propagating energy through an inactive medium to the charge of secondary explosive from a location immediately opposite and separated from the hole, in such a way that energy is released to the charge at a sufficient rate to cause its detonation.

"Propagnant energy" is energy that results from the intensity and time dependence of the dynamic-physical phenomena that are used to transfer the energy from one place to another, e.g. the energy due to the intensity and time dependence of an electromagnetic field or the pressure of a shock wave, the speed of a projectile, etc.

The expression "inactive medium" as used here to describe the environment through which the propagating energy is emitted to the charge, denotes a medium, such as the atmosphere, which does not contain any stored energy of its own, and which thus does not contribute any energy to the ignition process. The energy is thus shot into the charge without the presence or influence of a primary explosive in a physically continuous reaction chain with the charge, or more specifically, without the use of a capture cap.

A "series" as the term is used in this description, denotes an operation which consists of drilling, charging (charge placement) and detonation (charge ignition) at a certain location, i.e. drilling a hole, charging it with explosives, and igniting the explosives in same hole. This series is followed by one or more such series in different places, so that a "series" of series or cycles is produced.

The term "substantially continuous" when used to describe the drill-charge-blast series means that the steps in the series follow one another immediately without the interposition of additional steps not directly related to operations performed on the mass being processed. The series are not interrupted, for example, in the time needed to move moving equipment away from the formation and bring forward other equipment, connect ignition cables with the explosive charges and move all equipment and personnel away from the area to a remote location. A "substantially continuous" series in the present method is typically a series in which the total "dead time", that is, the time between the drilling and charge application steps plus the time between the charge application and charge ignition steps, is only of the order of 5 minutes or less.

The term "substantially continuous" when used to describe the sequence of series in a preferred embodiment, generally has the same meaning as described above for continuity of the series steps. This means that the series follow each other immediately both before and after the completion of the previous series, from the first to the last in the series, without delays or interruptions between the last step of one series (blasting) and the first step of the next (drilling ) to clear the area of fumes or to move equipment up to the mass from a remote position. A "substantially continuous" series of series in the present method is typically a sequence in which the "dead time", i.e. the time between series, is less than approx. 10 minutes, as the dead time between the series when the method is used for excavation work is usually much less, i.e. less than 1-2 minutes.

In a particularly efficient execution of the method, a number of series are performed largely simultaneously as a group or a set of series, followed by one or more other such groups, in a usually largely continuous sequence. In this connection, several drilling and charging steps can be carried out simultaneously or one after the other, before the antenna heating step in each series is started. In this case, each "cycle" in the cyclic process or sequence is a cycle of serial groups. The expression "substantially at the same time" as used here for the execution of the series in a group, indicates that all the series are started and finished within a certain time after which another cycle starts. The term is not used to imply that the same step is performed exactly at the same time in each series of the group.

All drilling-charging-blasting series, and preferably also cyclic series series or series groups, are carried out essentially continuously as explained above. However, the specific time used for each sequence and order, and the time course in which the series are performed in relation to other series, may vary depending on such factors as available equipment, available work space, etc. One or more drilling devices may be used, one or several explosive chargers, and one or more energy-emitting devices.

In order to achieve a fast and efficient performance of the method according to the invention, particularly in areas subject to restrictions, a new drilling and blasting apparatus has also been constructed. This device, which is of the type indicated at the outset, is characterized, according to the invention, by the fact that the drilling device and the explosive device are placed with a certain mutual adjustment on each of them or on a common support device and each can be moved axially in relation to this, and that on a own or the common support device, with a certain setting in relation to the drilling device and the explosives-rnate device, a device is placed for sending out energy to ignite explosives placed in the hole by the feeding device, the three devices being supported so that the drill bit of the drilling device, explosives- The discharge end of the rnate device and the output end of the energy device are arranged near a common working end, and further are set or adapted to be set so that the energy device emits energy in a path leading to the explosive charge in the hole, the drilling device and the explosive feeding device being able to move in this way in relation to the support device to drill the device's drill bit and feeding device

J-t- X X TJ X

the emptying end of the ning in sequence extends axially beyond all other parts of the apparatus at the said working end.

When the device is placed near a mass of material to be blasted, e.g. a rock formation or the surface of the earth, and operated in a suitable manner, the device in rapid succession drills a hole in the mass, charges explosives in the hole and ignites the explosives by sending out and releasing energy in the explosives, preferably by projectile impact, and the device can repeat the series in which any desired number elsewhere. For this reason, the three working components, i.e. the drilling device, the explosive device and the energy-emitting device, are arranged or adapted to be arranged in such a way that the explosive-delivering device emits explosives in a hole made by the drilling device, and the energy-emitting device device emits energy in a path that leads to the explosive in the hole. In other words, the longitudinal axes of the drilling device, the explosives supplying device and the energy emitting device pass simultaneously or in sequence through an essentially common point in space which is located at a desired distance outside the device near the operating end which corresponds to the place at which the drill bit in the beginning penetrates the formation, i.e. at the mouth of the borehole. By the expression "mainly common point" is meant that all three longitudinal axes at the desired location outside the device, that is at the mouth of the borehole, on a normal to the drill axis pass through the same point, or that the axes of the explosives supplying and the energy emitting device pass through points that lie within a borehole radius from the point through which the drill passes (that is, on the axis of the borehole). This passage through an essentially common point can be achieved by placing the three work components on axes that converge with the desired point, or by providing a setting device, e.g. a feed mechanism which causes the axes to essentially collapse in sequence. Although a converging, non-coincident design may be used, such is not preferred, as it requires accurate setting of the apparatus with respect to the distance from a point on the mass to be machined, and accurate maintenance of this same distance throughout drilling -charge-ignition series. In a preferred embodiment, the support device therefore cooperates with a setting device which is adapted for continuous setting, e.g. by turning and/or sliding, of the drilling device, the explosives-delivering device and the energy-emitting device on an essentially common longitudinal axis.

The "longitudinal axes" in the drilling device, the explosive-supplying and the| energy-emitting device that continuously coincides or converges as described, the longitudinal axis of the elongated part. e.g. the drill steel to which the drill bit is attached, the longitudinal axis in the supply pipe's borehole, and the axis along which energy is emitted from the energy-launching device, e.g. the longitudinal axis of a rifle barrel.

The device according to the invention is structured as a module, which means that it is a device that is a functional unit or assembly of components that is adapted to act as a unit or module in a larger assembly, in which it can be replaced with another such unit and, if desired, used together with other such units.

In the drawings showing particular embodiments of the apparatus according to the invention, fig. 1-4 longitudinal sections of a typical module according to the invention at different times, through a given mainly vertical plane, fig. IA - 4A show cross-sections along the respective lines A-A according to fig. 1 - 4 and set in the direction of the arrows, fig. 5 shows a longitudinal section of a part of the module according to the invention in which the energy emitting device is different from that shown in fig. 1 - 4, and fig. 6 is a picture seen from the front and partly from above, of a surface in a geological mass which is treated in small blasting cycles in accordance with the method according to the invention.

In the present method, charges of concentrated secondary explosive are placed in boreholes, and then each charge is ignited by rapid release of energy to the charge, as propagating energy is sent out to the charge through an inactive medium, e.g. the atmosphere. This ignition method is different from those that use a primary explosive in a continuous reaction chain with the charge, and from that used in drilling and blasting pro-

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sessions as they are usually carried out, i.e. igniting the charges in all the boreholes by means of a common energy emission, i.e. an electric pulse or flame that is produced far from the boreholes, as the many charges have been connected in advance in a single energy transmitting circuit. The use of the ignition method used in the method according to the invention eliminates the time-consuming operations required to produce conventional electric or non-electric ignition circuits, reduces labor requirements and allows excavation work to be carried out

with significantly fewer blast cycles than before. Moreover, the danger of accidental detonation which is present when sensitive primary explosive compositions, such as in arresting caps, are used in continuous reaction chains with the charges is avoided.

An efficient drilling and blasting process requires that as much as possible of the available explosive energy is applied in the form of high-pressure processing of the formation surrounding the borehole, e.g. to break up the formation. This is achieved by allowing as much of the explosive as possible to be surrounded by the formation, while avoiding any significant intermediate, compressible layer, e.g. an air ring, between the explosive and the formation. For this reason, the explosive charge is placed in the borehole in such a way that it is confined by the formation and touches the walls of the hole sufficiently to be supported by them. In each drill-charge blast series, the hole is drilled at the selected location, and then the explosive is placed in the drilled holes in one of the various ways suitable for the type of explosive charge used, and the length and direction of the borehole. For example, if the charge consists of one or more explosive cartridges or packings, or a solid explosive in bulk, it may pneumatic charging is used. Water-based explosives can be pumped into the borehole. The charging rate should be so low that the explosive does not detonate by itself on impact with the formation or with a previously charged cartridge. Such spontaneous detonation during charging must be avoided as it can destroy the charging equipment.

The choice of the explosive to be used in the present method is made as in any other blasting process, on the basis of safety, performance, convenience and economy. To provide the pressure required in hard rock, the explosive should be concentrated, e.g. solid (cast or packed powder), semi-solid or liquid detonating explosive, and it should be relatively insensitive to heat and weak shocks, i.e. a secondary explosive rather than a primary explosive. A primary explosive is an explosive that detonates when brought into contact with a flame or a glowing wire, while a secondary explosive requires, at least in practical commercial use, the use of a detonator and often a detonator to initiate detonation (Melvin A. Cook, The science and High Explosives, Reinhold, 1958 page 1 - 4). Representative secondary explosives include dynamite, mixtures of ammonium nitrate and fuel oil, TNT, PETN, nitrostarch, and the now popular waterborne explosives set forth in U.S. Patents 3,202,556, 3,355,336, 3,431,155, and 3,444,014. may be pre-mixed and the mixture charged into the holes, or when possible as is the case with ammonium nitrate and fuel oil, the components may be mixed during charging as they are fed in a common stream, or they may be charged separately and mixed into the holes. The explosive charge in a given borehole can have a uniform composition and/or density throughout its length, or different compositions can be used, or the same composition with different densities. If a specially chosen composition is not sufficiently sensitive for a given energy-emitting system, successful detonation can be achieved by adding to the composition a small amount of an ingredient that increases sensitivity, e.g. a finely divided metal fuel, or the charge can be made more sensitive only in the part of the charge where the energy is initially released, i.e. the part where the projectile impact occurs, however care must be taken to avoid making the charge as sensitive as those levels which are characteristic of primary explosives (e.g. lead trinitroresorcinate or lead acid), which are dangerous to handle in a loose state under the conditions that prevail in the workplace. However, special precautions to increase sensitivity can be avoided by changing the conditions of the energy emitting system, such as projectile velocity, impact area, nose configuration, etc., as will be described below.

After the borehole has been charged, the secondary explosive f the charge is ignited in the hole by means of propagating energy which is sent out to the charge through an inactive medium from a location directly opposite and separated from the hole, as the energy is supplied to the charge at a high rate per volume unit of the charge in the vicinity of the energy release. A high release or release rate is required to achieve a high local pressure and thereby initiate the detonation. Different types of propagating energy can be emitted in this way and triggered so that the desired explosion is produced. It can e.g. using kinetic energy (e.g. using a projectile), electromagnetic radiation (e.g. using a focused light pulse from a laser), or electrical energy (e.g. using a high-energy electrical discharge through an electrode). The medium through which the energy travels to the charge from the point of launch or emission, e.g. a firing chamber, a laser, or a source of electrical energy, such as a capacitor, is inactive or inactive (that is, it does not contain any stored energy), and in most cases simply consists of the atmosphere in the vicinity of the mass being processed. In the case of electrical energy, the energy is at least partially transferred through an electrode. Since the energy is emitted locally, and an energy pulse is emitted for each of the charges, the ignition step can be performed after charging without the delays required to connect the charges to each other and to a common energy source. This allows efficient blasting in small blast cycles.

Of the various ways of launching and releasing energy that can be used in the present method, propelling a projectile at high speed and impacting it with the charge is the preferred way because of the ease of operation and the availability and cost of the equipment. Different types of projectiles and projectile propulsion methods can be used. Provided that the impact velocity is sufficiently high and the mass of the projectile is sufficiently large to release the energy with a sufficiently high velocity, that is, subjecting the charge to high enough pressure over a sufficient area and for a sufficient time, so that it is caused to detonate completely with the expected velocity under the conditions present in the borehole. A complete, high-order detonation is required so that the explosive's maximum potential can be utilized, e.g. for splintering or introduction of seismic energy into the surrounding formation. The term "ignition" as used here thus relates to the supply of an impulse which brings the explosive charge in the borehole to complete detonation at a speed that is within the range that is common with the particular explosive composition in question when it is ignited by conventional means.

In the preferred case of ignition by projectile impact, the most important factors that determine whether or not such detonation will occur in a given explosive are the velocity of the projectile at impact, the impact impedance of the projectile, and its mass and shape. The minimum projectile velocity increases as the explosive's sensitivity to impact and the projectile's impact impedance decrease. With a given explosive and projectile material, the minimum impact velocity required to produce detonation will usually decrease as the mass of the projectile increases (up to a certain maximum) and as the area of the projectile nose, i.e. the area of the projectile surface that directly impacts the explosive, increases. For a given system and with a blunt-nosed projectile, the desired detonation can also be achieved with lower impact velocities if the projectile trajectory lies essentially on the axis of the borehole (front-to-front or non-stroking impact). As will be seen from the following examples, certain types of dynamite are reliably ignited by 22-gauge bullets (3.5 g, pointed nose) at impact velocities as low as 500 m/s, while certain water gel explosives require higher impact velocities, e.g. 900 m/s, with the same ammunition. On the basis of wider application with regard to explosives with which the projectile system is effective, a system is therefore preferred in which the bullets are launched with an exit velocity of at least approx. 1000 m/s, which gives an impact speed of approx. 900 m/s at a distance of 5 m from the mouth.

The projectile is a body of material that is propelled forward with great speed. It can be an undivided solid body, e.g. a rifle bullet, or solid particles, e.g. a shot. A high velocity liquid jet, such as a water jet, can also be used. As the desired impact velocity and high projectile impact impedance can be achieved more easily with solid projectiles, solid bodies and preferably unitary bodies are preferred. Projectiles consisting of unitary bodies must be made of materials, preferably metals, which are sufficiently strong to withstand the pressure and heat applied during propulsion. The shape is usually cylindrical, with the front end pointed, obtuse or spherical. For explosives that are easily ignited by projectile impact, e.g. gelatin dynamite, the pointed projectile found in commercial ammunition cartridges, can be used. For less sensitive explosives, it may be useful to use a blunt-nosed projectile, or one that has a conical cavity in the nose surface. Although the nose of the projectile may carry a secondary explosive charge to assist in ignition, inert projectiles are preferred as these are safer to store and deliver, and also cheaper. When the projectile is fired, the rifling may be essentially axially aligned with the bore, or form a slight angle with it. Near axial alignment is preferred to ensure accurate impact and complete detonation. If the projectile has a pointed nose, it can, however, enter at a certain angle, e.g. up to approx. 15° with the hole axis, as the permitted deviation in each given case depends on the properties of the mass being processed and the impact conditions.

The type of rifle that is used to launch the projectile is not critical, provided that it can provide the required exit and impact velocity with the type of projectile and propellant, or ammunition that is used. Any small arms, e.g. rifles, shotguns and pistols can be used. Air guns can also be used.

Another suitable method of igniting the explosive charge in the borehole is to allow the focused output of a pulsed laser to impinge on the charge. With such an embodiment, the ignition of a given explosive charge can be made even easier by increasing the laser power, e.g. by using a Q-coupled laser instead of a free-running one, and by keeping the end of the charge closest to the borehole mouth appropriately confined. A transparent plastic layer can e.g. is used over the end of the charge, either as a separate unit or as the end of a cartridge unit, and the focused laser beam is allowed to pass through the plastic layer of the charge. Although the specific amount of energy required for reliable ignition of an explosive by means of a laser beam varies with the particular explosive composition, for the more sensitive secondary explosives, such as pentaerythritol tetranitrate, gelatin dynamite, etc., an incident energy amount of approx. 0.025 joule/mm<2 >be capable of causing ignition when a Q-coupled laser beam is focused on the surface of the charge. The charge can often be made more sensitive to ignition by introducing a small amount of a material with a high light absorption coefficient, e.g. secondhand smoke. This increases the rate of energy release per volume unit.

In yet another method for igniting the explosive charge in the borehole, one or more expendable electrodes are placed in, or in the immediate vicinity of, the charge, e.g. by means of a. wire feed mechanism of the type that has been developed to feed welding wire from a roll, and energy is emitted via the electrode by means of an electrical discharge of a capacitor through the electrode.

A major advantage of the method according to the invention arises from the fact that all steps in the method, including the ignition of the charges, are carried out on site, as the necessary equipment works close to the mass being worked on. The energy that is to be released to the charges is thus emitted from a location directly opposite the mass, even if it is separated from it. The minimum distance between the energy projecting device, e.g. a rifle, and the boreholes will mainly depend on the total weight of the explosive that is detonated in a blasting cycle (that is, in holes that detonate at intervals of a few milliseconds), the nature of the rock fracture produced (direction and speed of rocks), and the device's impact strength and impact resistance. As a general rule, the energy-emitting device will be separated from the mass by a distance that is approximately proportional to the cube root of the weight of the explosive that is detonated per cycle. Although large separation distances can be used, e.g. up to approx. 1 to 2 tunnel or shaft diameters, it is preferred to work as close to the mass as possible with the equipment used. This applies in particular when the drilling and blasting module according to the invention is used. In this case, the module is placed so close to the front that the drill can produce holes with the desired depth, e.g. about. ch, and it is more efficient to perform the blasting step, e.g. firing the rifle, with the module in approximately the same position, or at least avoid the module having to be moved back from the drilling site before the blast.

The length of the explosive charge in relation to the length of the borehole will vary depending on the type of work being carried out.

When digging, it will normally be most effective to fill the hole with explosives. A layer of gas or liquid, such as air or water, or a solid layer, such as cardboard or plastic, between the mouth of the hole and the end of the charge where the energy is to be released does not preclude satisfactory ignition of the charge under certain conditions, although the properties and the the maximum depth of such a layer beyond which ignition becomes impossible or uneven varies with the particular type of propagating energy used for ignition, and with the explosive composition and magnitude of the energy. The material between the mouth of the borehole and the end of the charge where energy is to be released, as well as between the energy launch site and the mouth of the borehole, must be a material which, in the quantity present, does not absorb any large part of the emitted energy.

E.g. a light-absorbing, light-scattering or light-defocusing environment must be avoided between a laser device and the charge, and an electrically conductive environment must be avoided around an electrode. With laser ignition, any optically transparent material can be present. When it comes to ignition on projectile impact, gases may be present, as well as liquids or solids up to a certain depth. E.g. can explosives, such as certain types of dynamite ("Gelex" 2), when they are wrapped in a paper cartridge (where the cartridge end, for example, has a thickness of about 0.5 mm) and is covered by a layer of water up to a thickness of about. 10 cm in a borehole with a diameter of 4.5 - 5 cm, easily ignited by the impact of a standard fully jacketed 22 caliber projectile (3.5 g) hitting the water at a speed of 900 - 1000 m/s. In practice, any layer of liquid or solid material present above the end of the charge will usually be due to conditions encountered in the area to be blasted, e.g. water, or the condition of the charged explosive, e.g. a cartridge end.

The emplacement pattern of the series (hole pattern), the time order in which the drill-charge-blast series are performed, the number of series simultaneously performed (holes per cycle), and the amount of explosive detonated for each series or simultaneous group of series are all conditions that can vary widely, depending on many factors, such as the nature of the work to be carried out, the total size and the physical properties of the mass being processed, the number of drilling and blasting modules (or separate components) which is available, the equipment's impact resistance and impact safety (as it is directly opposite the mass during blasting), the working area's degree of narrowness, ventilation as well as the requirements and ability for noise attenuation, etc. For such operations as seismic surveys, secondary blasting, etc., a vehicle-mounted module can be moved along the surface as desired and is used to carry out a number of individual and rapid drill-load-blasting series at desired locations in a desired time pattern. For operations such as trenching and underground digging, it is more efficient to use several modules to perform multiple series simultaneously in groups, since more modules (or more series per group or cycle) provide faster progress. The specific number of series used for each simultaneous group (that is, holes per cycle) depends on the number of modules and on the available space, the impact and shock resistance of the modules and the mounting assembly used, how close to the formation the modules are used, the size of the charges and the time interval between the blasts. When all these factors are taken into account, we-1 the size of the cycles in most cases be less than approx. half the size of the full salvo,

and usually up to approx. 35% of the total number of required holes, or, so that no more than approx. 45 kg, usually up to approx. 15 kg, explosive detonates per cycle.

The angle of the borehole with the surface will also depend on the type of work desired. In some cases, the holes must be drilled not normally on the surface due to space restriction zones at the sides, roof and bottom of a tunnel. In other cases, crooked holes will be used to obtain a special type of cut. Any of the patterns commonly used in drilling and blasting operations

tions can be used in the method according to the invention.

The present process can be used when excavating any geological mass, but is particularly well suited when it is used in hard, abrasive rock, e.g. rock with a compressive strength of more than 1000 kg/cm o or a hardness greater than approx. 5 on Moh's scale, where mechanical excavators are currently not effective. Furthermore, as the method is applicable under many different geological conditions, the method provides the important advantage that it can be adapted for use with changing conditions as they are usually encountered, that is, large differences with regard to rock types and arrangements that occur within relatively small vertical and horizontal distances . The method can of course be used for excavation work for construction purposes, as well as for mineral extraction, e.g. ore mining of ferrous and non-ferrous metal, rock mining and quarrying, etc., and in seismic survey operations.

The drilling and blasting module according to the invention contains three main working parts in its structure, namely a drilling device, a device for releasing explosives containing an explosives f delivering or borehole charging pipe, and an energy emitting device, such as a gun, as well as a support device on which the three parts are mounted and which maintains the desired relative positions of the three parts. Any fitting system that is appropriate can be used, provided that the working end of each part, namely the drill bit, the discharge end of the supply pipe and the energy output end of the energy-emitting part, e.g. a gun muzzle, is placed close to a common end, i.e. the operating end of the module, and provided that the parts can be moved as desired, i.e. that the drill and the supply pipe can be moved axially in relation to the support device, and that the support device in the preferred embodiment can moved e.g. pivotable and/or sliding, so that it is possible to place the three main parts in sequence on a common axis. With these basic parts and movements, the module can in rapid succession drill a hole in a geological mass, load explosives into the borehole, ignite the explosives, and quickly repeat the series, whereby it performs the desired work on the machine.

The general design and dimensions of the module are determined on the basis of economic factors as well as the extent of borehole depths that will be necessary to produce and charge, the number and types of structural elements and types of drive mechanisms used in the module, the positions of the main parts in relation to each other , etc. Taking into account the relative dimensions of boreholes that are usually used for blasting, i.e. diameters of 1.2 - 40 cm and depths of up to approx. 35 m, and while avoiding telescopic components which, even if they can be used, are not preferred as it can be difficult to achieve reliable repeated function with these in a possibly dusty atmosphere, the module will usually be oblong, i.e. long in relation to its width. The overall design of the module, that is, the shape of the body formed when one or more surfaces are generated around the circumference of its parts, is immaterial to its function, and it may be broadly cylindrical or prismatic, of any suitable cross-section, e.g. circular, oval or polygonal, as is the case when the main parts are essentially mutually parallel, or shaped like a truncated cone or wedge-shaped, which can occur when the axes of the main parts converge. Whereas, as aforesaid, it is preferred that the correct setting of the principal parts under their function depends on their being successively brought to coincide, instead of their axes converging, and as convergence is unnecessary when the axes are adapted to coincide successively, and also less efficient with regard to space utilization, a largely parallel arrangement of the main parts is preferred, and therefore an essentially cylindrical module. In this preferred embodiment, it will be understood that the cylinder's cross-sectional area along the cylinder axis can vary, e.g. decrease from one end to the other, due to the presence of certain structural elements, or a slight inclination, e.g. up to approx. 10°, of the main parts in relation to the cylinder axis.

The support device for the three working parts can be a unit element, e.g. a bar, rod, tube or plate, or a skeletal frame of elements of rigid construction, preferably of metal, e.g. steel. If an outer casing part, such as a cylinder or a box, is used to protect the parts against impact, the casing part can serve as a support device with each of the three parts mounted in the casing wall. Alternatively, the casing part can serve as a support device together with an internal support. When e.g. the energy-emitting device is a laser, it may be desirable to mount the laser in the wall of the casing, and the explosives-supplying pipe and the drilling device on a common internal support device. Any suitable device for mounting the parts on the support device can be used, provided that the drilling device and the explosive supply tube can be moved unhindered in an axial direction in relation to the support device, so that they can both continuously project beyond all other components of the module at its operating end, as the drill bit must be able to project beyond the other parts a distance at least equal to the depth of the required borehole, and the supply pipe must be capable of projecting beyond at least the short distance required to introduce its discharge end into the borehole, although preferably it will be capable of to extend further into the hole.

In order for the module to be able to work in a predetermined way, i.e. so that the conditions achieved, such as the location and angle of the borehole, the charge and density of the explosive, and the path of the emitted energy, are in accordance with the conditions chosen in advance, it is necessary that the relative positions of the main parts are maintained during operation of the module, that is to say that the parts are supported both in the extended and retracted positions. For this reason, it is preferred that any axially movable main part which is not sufficiently rigid to retain its desired position during operation is held in position by the support device along most of the length of the part, and preferably along its entire length when in the retracted position, and that the distance between the support end at the operating end of the module and the mass to be machined when the part is extended beyond the support end is not sufficient to cause the part to move out of its predetermined axial position. Extra security for correct setting of the extendable parts is achieved by providing guide devices on the support device near its end, through which the parts travel when moved axially outside the support end. The distance between the support end and the surface can also be reduced without the entire module having to be moved closer to the surface, by the fact that the support device can be independently moved axially in relation to a module mounting part to which it is attached. A protruding plug capable of anchoring itself in a rock formation, e.g. by piercing (a sting) or by suction, can, if desired, be arranged at the end of the support device.

The specific distances to which the axially movable parts can be extended are not critical for the module's function, and depend on the borehole depth and how close to the surface the module works. From a given working position for the module, the pipe delivering the explosive does not need to extend as far as the drill bit, and both pipe and drilling device will extend further than the support device when this moves in relation to a mounting part.

The module is adapted for mounting on an external support arm, preferably via the support device in the module. Although the module's support device can be constructed so that it can be connected directly to an outer support arm, it will usually be more practical to attach a separate mounting part to the module's support device, this mounting part being later connected to a mounting part on the outer support arm. A suitable construction is one in which the module's mounting part provides the reset capability required by the main parts to cause them to collapse one after the other. The assembly part can e.g. contain a pivot pin that allows rotation of the support device that is in connection with it. Alternatively, the reset can also be achieved by sideways sliding of the support device. Turning and/or sliding the support device and locking the support device in position is achieved by operation of a setting or feeding mechanism which is connected to the mounting part or the support device. The feed mechanism can e.g. be a hydraulically driven mechanism that provides either linear motion, such as with a hydraulic cylinder, or rotary motion, such as with a rotary drive mechanism. The feeding mechanism is preferably in direct connection with the module's mounting part, e.g. a groove-containing part through which the support device slides in an axial direction. With regard to rotational movement, it is preferred to have the drilling device arranged on the desired axis in a rest (vertical) position, with the explosive delivery tube and the energy emitting device mounted on the same side, or on opposite sides of the drilling device, and rotate the support device in a direction to set the tube on the desired axis, and further in the same direction, or in the opposite direction, to set the energy-emitting path on the axis.

All Tconstruction parts in the module, as well as the moving mechanisms in it, must be protected against the effects of air pressure and possible rock collisions resulting from the detonation of the explosive charges in the boreholes. Such shielding can be achieved e.g. by means of a transverse metal plate (that is, a plate whose surfaces are mounted essentially normally on the module axis) between the module or modules and the mass being processed, as the module or modules work through openings in the plate. However, this shielding of the module or modules provides less maneuverability for the module, and it cannot be easily adapted for use with masses of all sizes. It is therefore preferred that the module parts are surrounded by impact-resistant and impact-resistant shielding devices, that is, a casing part that allows the module to be operated in direct confrontation with the mass, without the need for any additional shielding between the module and the mass. The cover part is made of a sufficiently tough material, e.g. a metal, such as certain types of steel, and which is sufficiently thick so that it does not crack or plastically deform to a particular extent as a result of the air pressure and stone collisions to which it is exposed. For a given metal, the minimum necessary thickness of the jacket in each given case will be determined by the size of the blast (that is, the amount of explosive that is detonated), the size and speed of the rock fragments produced, how close to the blast the module works, etc. operation under moderate conditions, e.g. explosions with less than approx. 2 kg of explosives, stones with a size of up to approx. 30 cm and which moves at speeds of up to approx. 15 m/s, and distances of at least 65 cm between the module and the surface, a jacket can be used that has a mantle with a thickness of at least 12 mm. As with the design of the module, the design of the casing part is unimportant, but it will usually be largely cylindrical or prism-shaped, as described above for the design of the module.

The module is usually mounted in the wall of the cladding part by attaching a mounting part to the cladding wall which engages with the module's support device. Attaching the support device directly to the casing wall is not preferred, as resetting the parts with such a construction would also require movement of the casing.

The casing part is as long as the module itself, and since it is necessary at least during the blasting to shield all the module's parts, the operating or working end of the casing part is adapted to be able to be closed. The non-working end may be open, but will usually be permanently closed. The working end is adapted for opening and closing, e.g. as shown in fig. 1-5, where a shock-proof and impact-resistant, pivotable closing part, e.g. one or more doors mounted on the jacket cylinder at the working end of the module are adapted to assume an open or closed position relative to the end of the jacket cylinder in response to a force applied by means of a moving device, such as a hydraulic cylinder, which from somewhere inside the casing part is in connection with the closing part. An opening or valve is arranged in the closing part which, when the part is closed, falls on an axis that coincides with the axis with which the module's three working parts preferably fall together one after the other. The closing part is moved to the open position when the drilling device, charger or support device is to be moved axially to an extended position, and to the closed position when all axially extendable parts are in the retracted position and the energy is to be emitted from the energy-emitting device. The opening allows the energy to travel unhindered from the energy-emitting device to the explosive charge in the borehole. A conical or wedge-shaped closure design is preferred, as a means of providing additional protection against rock impact.

The effect of blows and shocks on the module can also be reduced by crumpling an energy-absorbing device together with the jacket, e.g. by using springs in the system for mounting the module on the support arm. A particularly effective energy-absorbing device is an inflated pneumatic part, e.g. an elastic part containing fluid under pressure. when such a part which in its function resembles e.g. a car tyre, rests against the end of the casing cylinder, e.g. as shown in fig. 1-4, it serves as a shock cushion for the module front and protects it against collisions with shock waves and flying stones. Several such parts can be used side by side around the cover when additional, and lateral suspension is desired.

With the method according to the invention, greater efficiency is achieved, e.g. expressed by the weight of excavated material per unit of time, as several drilling-charging-blasting series are carried out simultaneously. With the module according to the invention, cycles are achieved which consist of multiple series using a number of modules equal to the selected number of series to be performed simultaneously. Multiple modules can be used which each consist of a single drilling device, a single explosives delivering device and a single energy emitting device, and which are suitably supported and protected. When efficient utilization of space and weight is of primary importance, however, it is preferred to use a composite module containing two or more single-component modules or module units which are suitably grouped within a common casing part. The geometric arrangement or grouping pattern of the basic module units within the composite module, and the specific number of units, may vary as desired. E.g. for simultaneous operation in largely rectilinear or aggregate borehole patterns, a linear or aggregate unit grouping can be used, the module in such cases having a shape that largely resembles a parallelepiped. For operation in a curved pattern, the grouping can be designed as a circular arc. In the composite module, each unit can be complete in itself, i.e. have its own drilling device, explosives-delivering device and energy-emitting device, or a common component, e.g. an explosive substance delivery device can be shared by more than one unit.

Any type of drilling device can be used in the module, e.g. an impact drill or impact hammer, a rotary drill, or one that uses both impact and rotary action. An electric crushing drill that provides heat and rotation can also be used. For hard rock, rotary impact drills are preferred. For convenience, e.g. in order to make use of ready-made components where such are available, and to avoid an unnecessary increase in the number of structural elements, the drilling device and the support part in a preferred module constitute a rotating impact drill or feeding device, both of which are made of metal, e.g. steel. The drill rotation can be transmitted from a pneumatic or hydraulically driven motor mounted in feed channels, and axial force for extension and drilling can be supplied via a heavy chain driven by a pneumatic or hydraulic motor. The explosive supply pipe and the energy emitting device are mounted on the support device, e.g. the drill feed channel, predict such a way that axial movement of the drill and supply pipe is not hindered.

The explosives supply pipe has an explosives feed end which is connected to an explosives feed system located on the outside of the module's boundary. The explosive feed system consists of an explosive supply unit, e.g. a magazine containing explosives in cartridges or loose, solid explosives, or a storage and mixing tank for slurry explosive components, and a feed unit which is connected to the supply unit and can release explosives from it, e.g. a pneumatic charging device for solid explosives, or a pump for mud blast victims. The tube from the module can be

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connected to the charging pipe in a pneumatic charging device or to the drain hose in a slurry pump, or if it is long enough, it can replace the entire 1 charging pipe or drain hose and be attached directly to the explosives delivery mechanism strainer pump in the explosives feeding system. For loading explosives in cartridges, e.g. dynamite,

a preferred feed unit is a pneumatic cartridge loader of the type described in US Patent 3,040,615 and in "The Modern Technique of Rock Blasting", by N. Langefors and B. Kihlstrom, Stockholm, Almqvist & Wiksell, 1967 page 91 - 101. Both the part of the supply pipe that is inside the module and the part that is outside the module should be somewhat flexible and can e.g. be made of metal or plastic. With the pneumatic cartridge loader, a semi-automatic rear part can be used for continuous feeding of cartridges.

The axial movement of the pipe in relation to the support device

can be achieved in many different ways. One way is to leave a spot

say, belt pipe, such as a plastic pipe, lead into a rigid pipe, such as a metal pipe, which is slidably mounted on the support device, e.g. in a guide slot, in the desired position with its free end at the working end of the module and its other end in connection with a pneumatic setting cylinder. In another method, namely that shown in fig. 3, the pipe can be moved using a device, that is, the so-called "robot charger", which is also described by N. Langefors and B. Kihlstrom in the aforementioned work. The robotic loader works in conjunction with a pneumatic cartridge loader. The robot charger which is mounted on the support device, e.g. the drill feed channel consists of a pneumatic cylinder that drives a tubular piston rod back and forth. The supply pipe is led axially through the piston rod. Connected to the piston rod is a pneumatic gripping device, a "hand" which, by means of friction, holds the tube so that it performs a reciprocating movement. As the piston rod moves back and forth, the pneumatic "hand" engages during forward movement and releases during backward movement, thus giving the supply tube a step-by-step forward movement. For the withdrawal of the pipe after the borehole has been charged, the opposite "hand" action occurs. The supply pipe is preferably moved all the way down to the bottom of the borehole and slowly pulled out with repeated light counter movements, so that the driven-in cartridges are packed to a high density.

In a preferred module, the energy-launching device is a gun. The term "gun" denotes an assembly consisting of a metal tube or barrel having one open end (the muzzle end) and the other end (the rear end) being adapted to form a chamber into which the projectile is introduced and gas under pressure on command supplied or generated behind the projectiles. The term is intended to include devices in which projectiles are propelled using gas that is admitted into the chamber at high pressure, as well as those devices in which the propellant gas is produced in the chamber by the combustion of a propellant charge. When necessary, as in the latter case, the rear end of the barrel is closed by means of a breech block or wedge provided in a housing which can be opened for loading ammunition into the chamber (in front of the wedge), and which can be closed for ignition of the propellant charge on command by means of a chamber mechanism. The type of gun used is not critical, provided that it can propel the projectile material with sufficient mass and sufficiently high speed to expose the explosive in the borehole to high enough pressure over a sufficient area and for sufficient time to cause the explosive to detonate. The required impact energy is most easily achieved by means of fixed projectiles, and particularly unit-; bodies, i.e. bullets as opposed to shot, and for this reason bullets are the projectiles of choice. Although the projectile can be propelled by means of a gas stream which is admitted into the chamber under high pressure such as in an air rifle, there are less limitations on the achievable impact speed when the projectile is propelled by combustion of a propellant composition in the chamber. Consequently, guns that work on the propellant-combustion principle are preferred. In the preferred embodiment, the rifle thus consists of a metal barrel, the rear end of which is closed by means of a breech block or a wedge which can be opened for loading a salvo of ammunition into the chamber in front of the wedge, and closed for ignition of the propellant charge in the salvo by means of a chamber mechanism which operates on command from the module's outside. Empty cartridges can be continuously ejected from the module, or collected in a container arranged in the module for this purpose, the container being adapted for periodic emptying. The ammunition priming charge may be a percussion priming cap, an electric priming cap or a combination priming cap. Electrical firing of the ignition charge may be preferred in certain cases when greater precision is required with respect to time intervals between detonations.

The magazine for ammunition can be arranged inside or outside the module's boundaries. An external magazine is preferred due to space limitations in the module, and also because storage of ammunition in a location separate from the work area is desirable from a security point of view. With an external magazine, therefore, a loading or supply tube for ammunition runs from an external ammunition feeding system to the rifle's chamber. The feeding system can e.g. be a pneumatic charging device of the type described for charging cartridge explosives in a borehole.

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Although the rifle can be constructed completely custom-made, in most cases it will be possible to adapt a commercially available rifle, e.g. a breech-loading rifle, semi-automatic rifle or pistol, for use in the module. Although it may be desirable, rifling of the barrel is not absolutely necessary, due to the relatively small distance the projectile will travel when the module is in operation. Remote firing of the rifle can be achieved by applying an electrical current to a solenoid which triggers a conventional mechanical trigger mechanism, i.e. trigger action to cause movement of the firing pin so that the firing mixture is ignited on impact, or by applying current to an insulated firing pin in contact with a bridge wire or an electrically conductive ignition mixture in an electric ignition charge, the electrical circuit being closed by means of the cartridge sleeve and earth, and the ignition mixture being ignited by ohmic heating of the bridge wire or the conductive mixture.

When a laser is used as an energy-emitting device, a shroud is needed to prevent the penetration of light-absorbing material, such as rock dust, into the path of the laser beam. The "laser" contains a laser rod (e.g. ruby) with a total reflector at one end and a partial reflector at the other end of the rod, one or more floodlights for pumping or pulsing the laser rod, a high-voltage electrical source for powering the floodlight or the lamps, a Q-switch or Q-destroyer in the beam path between the forward end of the rod and the partial reflector, and a focusing lens. To provide maximum protection for the laser during the blast, it is preferred that the laser is in a retracted position relative to the beam path. The laser can e.g. is mounted in the wall of the casing and the beam is reflected in the desired path by means of suitably arranged reflectors. In this case, the reflectors, if one makes use of placing the working parts on a common axis, can be placed on a support device and moved on this to project the beam in the desired path.

The module also contains or is in connection with suitable motion transmitting mechanisms, e.g. hydraulic or pneumatic devices which perform such movements as axial movement of the drilling device, the explosive supply pipe and the support device (e.g. the drill feed channel). Furthermore, these devices carry out such movements as drilling, supplying explosives to the borehole, in a preferred embodiment supplying ammunition volleys to the gun chamber and firing the gun, resetting the main parts (that is, step-by-step feeding), and opening and closing the casing door at the working end. Such mechanisms are well known to professionals, and their basic mode of operation will therefore not be described here. All power supply lines, such as hydraulic lines, for these devices are shielded in the same way as the module's parts, preferably by being surrounded by a suitable shroud. When the module contains a casing part, all power supply lines enter the module through the casing wall via the mounting part, or via one or more special openings for this purpose.

As previously mentioned, the module according to the invention can, when placed near a surface of the material to be processed, such as a rock formation, and operated in a suitable manner, drill a hole in the rock in rapid succession, charge explosives in the hole and ignite the explosives by rapid release of energy in this, e.g. at projectile impact. Since the application of the module produces an explosion each time energy is applied to the explosive, the module must be mechanically mounted on a supporting arm or base and its function controlled from a suitably shielded location. Although any mounting and control system can be used, e.g. impact- and impact-proof lifting leg or lifting rod assembly with control devices separated from the mass being processed by means of a barricade which is essentially parallel to the mass, the greatest benefit of the module is achieved when it is incorporated into a machine designed to support counting, maneuvering and operation of one or more modules in an essentially continuous manner. For this reason, the module or modules are usually mounted on a vehicle, such as a truck or lorry, and controlled by personnel sitting inside the vehicle, this and the personnel being suitably protected from the effects of the relatively

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small explosions.

In order to achieve a clearer understanding of the method and apparatus according to the invention, reference is now made to the drawings which show the construction and operation of typical modules, and a typical cyclic pattern for carrying out the method.

In fig. 1 - 4 is a module placed in position in front of a stone surface 1 on a longitudinal axis which is essentially normal to the surface 1 and is parallel to the surface 2. Each main working part in the module is shown in three different radial positions, the drilling device being located in the vertical plane in fig. 1 and 2, the explosive supply pipe in fig. 3 and the energy projecting device in fig. 4. When a working part is in this vertical plane, the longitudinal axis of the part falls

substantially together with the axis of the borehole (indicated by a dashed line into the rock in fig. 1).

In fig. 1, IA and 2 show an elongated support device 3, e.g. a drill feed channel, on which is mounted a drilling device, shown as a rotary impact drill, with an elongated tubular part 4, e.g. a drill steel, and a drill bit 5. The drilling device is axially movable on the support device 3, e.g. by means of a chain feed or screw feed driven by a motor 6, e.g. a compressed air engine. The motorized chain feed or screw feed adds feed pressure or

-power for drilling. Drilling action (alternation and rotation) is obtained by means of a motor 7, e.g. a pneumatically driven motor. The support device 3 is connected to a mechanism 9, e.g. one

hydraulic cylinder, which is adapted to move the support device 3 back and forth independently in an axial direction in an axial groove in a slide part 37 (the device 3 is shown in front in Fig. 2). The track-holding slide part 37, the associated pivot part 8 which has an axis of rotation which is parallel to the axis of the elongated part 4, and the flange 12 together form the mounting part for the module. An adjustment part 31, in this case a hydraulic cylinder (shown in Fig. 1A), is in connection with the sliding part 37 and the cover 13 which e.g. is a metal cylinder. A pointed metal plug or stick 10 extends axially from the end of the support device 3 facing the surface 1, and hook-like guide elements 11 extend from the support device 3 at the same end normally to the longitudinal axis, in such a way that the elongated part 4 goes through the guide elements 11. The flange 12 which is attached to the pivot part 8 is fitted into an opening in the wall of the casing 13, and is adapted to engage with a fastening part 14 in a suitable support arm for the module. At the working end of the module, i.e. where the drill bit 5 is located, a pumped-up pneumatic part 15 is arranged, e.g. a rubber tire, which rests against the end of the jacket 13. At the same end is a closing part 16, e.g. a door, adapted for opening and closing by the action of a motor 17, such as a hydraulic motor, which is mounted inside the casing and is connected to the closing part 16. The latter is provided with an opening or a hole 18 which is arranged so that when the closing part is closed, the axis on which the working parts successively collapse (the axis of the oblong part 4 in fig. 1) passes through the opening 18.

In fig. 3 shows an explosive supply pipe 19 which is somewhat flexible, e.g. made of plastic, and which is mounted on the support device 3 essentially parallel to the elongated part 4, and at the same radial distance from the pivoting part 8 as the elongated part. One end of the pipe 19 leads to a conventional explosives feeding system, such as a pneumatic cartridge loader as described above, which is arranged outside the module. The other, free end of the pipe is the discharge end and this is arranged at the working end of the module. The pipe 19 passes through the opening in the wall of the jacket 13. 20 denotes a feed mechanism which is adapted to move the tube 19 axially, e.g. a robot charger as described above. Annular guide elements 21 extend from the support device 3 at the working end normally on the longitudinal axis, in such a way that the pipe 19 passes through the guide elements.

In fig. 4 shows a rifle with a barrel 22, a chamber 23 and

a recoil jacket 30., A flexible ammunition supply tube 24

leads into the chamber 23 and is connected to an ammunition feeding system, such as a pneumatic loader as described above and which is located outside the module, the pipe 24 passing through the opening in the wall of the casing 13. The gun is fixedly mounted on the support device 3 essentially parallel to the elongated part 4, and at the same radial distance from the pivoting part 8 as the elongated part and the explosive supply tube. The muzzle of the rifle is at the working end of the module.

Before a drill-load-blast series, the module is placed as shown in fig. 1 and IA, the oblong part 4 being coaxial with the axis of the desired borehole and in a vertical line with the swing part 8. The motor 17 has been started to open the closing part 16. In the first phase of the series (fig. 2 and 2A ) energizing the mechanism 9 means that the support device 3 is moved axially on the sliding part 37 in the direction of the surface 1 until the stick 10 is in firm engagement with the surface 1, and thus helps to stabilize the module when the parts are advanced. With the support device in this position, the elongated part 4 is moved axially in the direction of the surface 1 by energizing the motor 6, and the drill bit then drills a hole 25 of the desired thickness in the stone by means of the pressure and rotation effect which is transferred to it by the chain- or the screw feed and the motor 7.

After the hole has been drilled, the drilling device is pulled back into the casing 13 by means of the chain or screw feed, and the hydraulic cylinder 31 moves the slide part 37 so that the support device 3 which is mounted on it, by the action of the pivot part 8, is turned in a clockwise direction so that the explosive supply pipe 19 is placed coaxially with the hole 25 and on a vertical line with the pivoting part 8 (fig. 3 and 3A). The pipe 19 is moved axially and into the borehole 25 by the action of the feed mechanism 20. While the supply pipe is in this position, cartridges with high-explosive explosives 26 are fed through the pipe 19 and hurled from this into the hole 25, e.g. using a pneumatic cartridge loader.

After the hole has been charged with explosives, the pipe 19 is drawn back into the casing 13 by means of the feed mechanism 20, and the hydraulic cylinder 31 is restarted, and in this case moves the sliding part 37 and the support device 3 which is mounted on it,

in a clockwise direction so that the rifle barrel 22 is placed coaxially with the hole 25 and on a vertical line with the pivot part 8 (fig. 4 and 4A). The closing part 16 is closed by energizing the motor 17, and the opening 18 which: has a larger diameter than the ball 27 used, is then

coaxial with hole 25. The gun is fired, e.g. in that electric current is supplied to the ignition piston for the ammunition thermal cap, and the projectile 27 is propelled at high speed from the muzzle of the gun, through the opening 18 and the space between the module and the hole 25 and into the explosive 26 in the hole 25, along the path indicated by the line - drawn line. The impact causes the explosive to detonate and the rock to crack and move in the manner indicated as a typical example in fig. 4.

Fig. 5 shows part of a module similar to that shown in fig. 1-4, except that in this embodiment a laser is used as an energy-emitting device, and that the construction of the closing part 16 has been modified. The module is shown with parts working in the series ignition phase. In fig. 5 is a laser assembly 32, i.e. rod, lamps, Q switch device, partial reflectors, total reflectors and focusing lens, mounted on the wall of the jacket 13. The locking unit 32 is connected to a power source outside the module, and the laser is offset in relation to the axis of the borehole. After passing through the focusing lens in the locking assembly 32, the laser beam 33 is reflected from parallel reflectors 34 and 36 which direct the beam in a path coaxial with the borehole 25. The explosive 26 in the borehole has a transparent end cap 36, e.g. a cartridge end such as is made of plastic. The module has such a position in relation to the surface 1 that the focal point of the beam 33 is located on the surface of the explosive 26. The reflectors 34 and 35 are mounted on the support device 3 in such a way that operation of the setting device 31 causes the reflectors to take such a position that the path of the beam 33 is coaxial with the hole 25. The closing part 16 is wedge-shaped and has an upper and a lower part which are adapted for opening and closing. Supply of energy from the power source to the locking assembly 32 causes the emission of a beam 33 of electromagnetic radiation which travels through the atmosphere to the hole 25, passes through the transparent end cap 36 and focuses on the surface of the charge 26 so that it detonates.

Typical ways of carrying out the method and operating the module according to the invention when processing a geological mass shall be described in the following examples.

Example 1

As shown in fig. 6, a substantially smooth and vertical surface 1 has been exposed in the geological formation, such as hard rock, and the surface is processed, e.g. for driving a tunnel, using* the method according to the invention. The surface is mostly square and about 2.5 m high and 2.5 m wide. Every volley

(all the series or holes required to advance the entire surface)

consists of 30 holes which are arranged in parallel columns and rows which for the most part have the same distance from each other. This means that the drill-charge-blast series in the present method is carried out at thirty locations. The process is carried out in five successive serial groups, or five drill-load-blast cycles for each salvo,

in

with six series or holes for each cycle. Six modules are used, and in each cycle six holes are drilled mostly simultaneously. Then the holes are charged substantially simultaneously and six projectiles are fired, one projectile to each charged hole, at intervals of a few milliseconds, to detonate the six charges, the cycle ending when the series of detonation series is interrupted in the time required to drill a new series hole (the beginning of the next cycle).

In the one in fig. 6 situation, the first three cycles (three center rows marked cycle 1, 2 and 3) have been completed, and the fourth cycle 4 is being executed in the bursting phase of the series. The completed blasting has produced rock fragments that have been separated from the mass 1 so that horizontal surfaces 2a and 2b have been formed with essentially the same depth as the boreholes and which are largely in the same plane as the original holes in cycles 2 and 3. Rock fragments 28 have piled up on the bottom of the tunnel and part 29 of the new vertical surface that is produced has been uncovered.

In the opening cycle (Cycle 1 with a center row of six holes) the six holes are fired in a different order from the firing three used for the remaining cycles. In cycle 1, the two center holes are fired first, then the two holes adjacent to the center holes are fired, and the two outer holes are finally fired, each pair of holes being fired essentially simultaneously with approx. 2 ms space between each pair. The two center holes lie on converging axes that form approx. 10° with the surface normal, and the remaining holes diverge to the sides by approx. 15° from normal. In the remaining cycles, the hole axes diverge at the surface perimeter, while the remaining holes are substantially normal to the surface (slanted holes at the top, bottom and sides are necessary due to the limited maneuverability of the module at the perimeter). The six holes in each of these cycles are fired individually in direct linear order.

The holes have a diameter of 3.2 cm and a length of 0.5 m.

Each hole is filled and contains approx. 0.25 kg in cartridge form of "Gelex" 2 which is a semi-gelatin dynamite. (See examples 2 - 6). The Borean arrangements on the modules are of the rotary hammer drill type and the chargers are pneumatic cartridge chargers in which the dynamite cartridges are pushed forwards through charging tubes and flung into the drill holes, so that the cartridge paper tears and the explosive is packed to a high density. The rifles are of the type that use ordinary 22-caliber shots, and they are fired on an axis with the holes at a distance of approx. 3 m, which gives an impact speed of 1000 m/s. Each cycle is completed in approx. 2.5 minutes, and the total dead time in the cycle is approx. 45 sec. In fig. 6, the six holes in cycle 4 have been drilled and charged with explosives 26. The projectiles 27 are shown just before impact. Collisions between the projectiles and the charges (at about 2 ms intervals) cause detonation and rock breakage, so that a new surface 29 is formed up to the level of the holes in cycle 4.

The procedure described for cycle 4 is repeated for cycle 5 after removing any rock pieces blocking the borehole positions (in the places marked with "+") to expose the complete new surface.

After the round of five cycles has been completed (five 2.5 minute cycles with approx. 60 sec intervals between cycles) and the stone fragments have been removed from the area, a completely new surface has been uncovered which lies approx. 0.5 m behind the original surface. Similar tunnels, e.g. with a diameter of 2 to 7 metres, can be made by adjusting the device.

The following examples serve to illustrate the performance of the method according to the invention when a high-velocity projectile is used as propagating energy for igniting the explosive. The procedure is illustrated with different state combinations, i.e. explosive composition, borehole conditions, and impact speed, mass and trajectory of the projectile. The impact speeds that have been used as examples should not be interpreted as limit speeds for the systems shown, and in any case the operating limits can be changed by changing such conditions as have been described, e.g. limitations, contact area or explosive density. For each example, unless otherwise stated, a hole with a diameter of 4.5 cm and a length of 30 cm is drilled in a rock mass in the first phase of the series. The hole is then charged with densified high-explosive explosives, and the explosives are ignited by firing a projectile from a gun that is aligned coaxially with the hole, unless otherwise specified. The rifle is fired using a remote-controlled trigger. The distance between the rifle muzzle and the hole is approx. 3 m. The specified impact speed is the projectile speed achieved with the ammunition used and measured 5 m from the muzzle. Except when otherwise stated, the projectiles used are bullets with a soft (unjacketed) tip. When material other than explosives is present in the borehole, the projectile passes through this material and eventually hits the explosives. In each example, the drill-charge-blast series is followed by another series at a location different from the first, and carried out under the same conditions as the first. In each case, the explosive charge detonates and blasts the rock to pieces.

Example 17

The present method is used for carrying out secondary blasting, i.e. blasting of large stone blocks that have been produced in a previous blasting operation. A single module of the type shown in fig. 5, and the module is mounted on and controlled from a vehicle which moves on the surface between the rocks as desired to perform a desired sequence of drill-charge-blast sequences. The drill and charging apparatus, and the hole and charge size, are the same as in example 1, except that the bottom (external end) of the outer cartridge in this case consists of a 13 mm thick disk of transparent plastic, e.g. polystyrene. The energy-emitting device in the module is a laser head, model LHM6 manufactured by the Raytheon Company, where the laser head consists of a ruby rod with a length of 168 mm and a diameter of 16 mm, two FX-47A-6.5 spotlight lamps, a front mirror which is 65% reflective at 6950Å and a 99.9% reflective rear mirror. Q-switching is achieved by placing a cell filled with a passive, liquid Q-switching solution in the beam path between the front end of the rod and the 65% mirror. A focusing lens with a focal length of 114 cm is placed in front of the 65% mirror. The laser head, Q-switch resolution and lens are mounted on the wall of the jacket. Two total reflectors (right-angled glass prisms) are placed in front of the lens in such a way that the axis of the focused beam changes from the axis of the laser rod to an axis that is parallel to, but 15 cm apart from, this. The reflective prisms are mounted on the drill feed channel. During operation, the module is positioned so that the laser beam is aligned coaxially with the borehole, and the distance between the charge in the borehole and the prism closest to it is 90 cm. After the hole has been drilled and charged, the laser is activated by applying a high current pulse to the laser head from a remote power supply unit (Raytheon Model.LPS4, with LPS4A control chassis and LPS4B capacitor banks) with a capacity of 220 uF. The capacitors are charged to a voltage of 3000V, which gives an energy supply of 10000 joules to the laser cavity. The laser's output signal is focused on the surface of the charge, causing it to ignite with an incident energy of 0.1 joule/mm (observed using a Lear Siegler Laser Energy Monitor Ml-2). The detonation of the charge causes the rock to explode into pieces.

Claims (8)

1. Procedure for processing a geological mass by drilling and blasting, whereby one or more holes are drilled in the mass and a charge of concentrated secondary explosive is placed in each of the holes, and where the processing takes place by causing the charge or charges to detonate, characterized in that a number of series consisting of the steps of drilling, charging and blasting are carried out in succession and essentially continuously at different places in the mass, the ignition step in each series being carried out by propagating energy being emitted through an inactive medium to the charge with secondary explosive from a location immediately opposite and separated from the hole, in such a way that energy is released to the charge at a sufficient rate to cause its detonation. 2. Method according to claim 1, characterized in that the propagating energy in each series is a laser pulse, whereby the energy is released to the charge by a focused laser beam colliding with the charge. 3. Method according to claim 1, characterized in that the propagating energy in each series is emitted by a projectile, preferably from a rifle, being propelled forward at high speed, whereby the energy is released to the charge by the projectile colliding with the charge. 4. Apparatus for carrying out the method specified according to one or more of the preceding claims, comprising a drilling device in the form of an elongated part (4) with a drill bit (5) at one end, and an explosives feeding device (19) for supplying explosives to a hole (25) drilled by the drilling device, which feeding device contains a pipe with an emptying end and an emptying end, characterized in that the drilling device and the explosives feeding device are placed with a certain mutual adjustment on each or a common support device (3) and each can be moved axially in relation to this, and that the on a separate or common support device (3), with a certain setting in relation to the drilling device and the explosives feeding device, a device (22, 2 3 and 30) is placed for sending out energy to ignite explosives (26) which of the feeding device (19) is placed in the hole (25), the three devices being supported so that the drill bit (5) of the drilling device, the discharge end of the explosives feeding device and the energy device out walking end is arranged close to a common working end, and further is set or adapted to be set so that the energy device emits energy in a path leading to the explosive charge (26) in the hole (25), as the drilling device and the explosive feeding device can be moved in this way in relation to the support device (3) that the drill bit (5) of the drilling device and the discharge end of the feeding device in sequence extend axially beyond all other parts of the apparatus at the aforementioned working end. 5. Apparatus according to claim 4, characterized in that the support device (3) is movable, preferably rotatable, by means of a setting device (31) which cooperates with this and is adapted to sequentially place the drilling device and the explosive f-feeding device and preferably also the energy device's transmission path on an essentially common longitudinal axis. 6. Apparatus according to claim 4 or 5, characterized in that the support device (3) is placed on a stand part (12) for the apparatus and can be moved axially in relation to this, which stand part is attached to the inner wall of a casing part (13) to which Finally, at the working end of the device, a closing part (16) is attached which can be opened and closed and which has an opening (18) which lies in the energy device's sending path. 7. Apparatus according to one of claims 4-6, characterized in that the energy-emitting device is a gun (22, 23 and 30). 8. i Apparatus according to one of claims 4-6, characterized in that the energy-emitting device is a pulsed laser (32), preferably with a focusing lens in the path of the laser beam.