US3769874A - Method of pumping explosive slurry - Google Patents

Abstract

The invention is to a method of filling bore-holes by pumping an explosive slurry by a primary pump through a hose more than 50 ft. in length to a secondary unit in a restricted underground space. From the secondary unit the explosive slurry is pumped through a hose inserted in a borehole and an additive is pumped into the explosive slurry. Control devices for controlling the flow of explosive slurry are provided.

Description

Unite States Patent [1 1 Williams et al. Nov. 6, 1973 METHOD OF PUMPING EXPLDSHVE 1,038,806 9/1912 Welcker 302/12 SLURRY 3,380,333 4/1968 Clay et al.... 86/20 C 3,523,048 8/1970 Hopier, Jr 149/44 X [75 inventors: Darrell Andrew Williams, West Heidelberg; Adam Prus Wisinski, Parkdal? both of Vlctona, Primary Examiner-Leland A. Sebastian Australla Attorne Cushman, Darb & Cushman y y [73] Assignee: ICI Australia Limited, Melbourne,

Victoria, Australia [57] ABSTRACT [22] Filed: July 24, 1972 21 APPL 274 430 The invention is to a method of filling bore-holes by pumping an explosive slurry by a primary pump through a hose more than 50 ft. in length to e second- [30] Forelgn Apphcamm Pnonty Data ary unit in a restricted underground space. From the Aug. 16, 1971 Australia 5915 ondar unit th xplosive lurry is pumped through a hose inserted in a borehole and an additive is pumped [52] C 8 into the explosive slurry. Control devices for control- 302/12 ling the flow of explosive slurry are provided. [51] Int. Cl. F42d l/00 [58] Field of Search 86/20 C; 302/12 [56] References Cited 4 Claims, 2 Drawing Figures UNITED STATES PATENTS 827,296 7/1906 Donnelly 302/12 STATlC MIXER PATENTEDHUV 6 i975 PR\MARY PUMP CONTROL LINE SLURRY HOPPER SLURRY PUMP STATK: MIXER 1 METHOD OF PUMPING EXPLOSIVE SLURRY This invention relates to a method and apparatus for the manufacture and use of slurried explosives in mining operations.

Slurried explosives normally comprise at least one oxygen releasing salt selected from the group consisting of inorganic nitrates, and perchlorates and mixtures thereof, a thickening agent, a fuel and water. Optionally additives, for example agents increasing sensitivity and fuel content, may be added.

Usually the oxygen releasing salt is chosen from the nitrates of the alkali metals or ammonium such as ammonium nitrate and sodium nitrate. The amount of oxygen releasing salt is not narrowly critical; compositions containing amounts of oxygen releasing salts from 50% w/w to 90% w/w of the total composition are satisfactory. The particle size and'shape of the oxygen releasing salt is not critical and is well known from the art of ammonium nitrate manufacture; powders and prilled particles are satisfactory.

The nature of the fuels in such compositions is determined by the requirements that they burn in the presence of oxygen or an oxygen containing gas and that their physical nature is such that they may be incorporated in such compositions in a manner so as to be substantially uniformly distributed throughout the compositions. Such fuels arewell known in the art and they may be organic or inorganic and may also be derived from animals and plants.

The fuels employed in such compositions can be, for example, self-explosive fuel, non-explosive carbonaceous fuel, non-metallic and metallic fuels or mixtures of the aforementioned types of fuels. They can be varied widely provided that, in the composition in which any particular fuel is used, the fuel is stable, that is, prior to detonation, during preparation and storage, the fuel is chemically inert to the system. Examples of selfexplosive fuels include one or more organic nitrates, nitro compounds and nitramines such as trinitrotoluene, cyclotri(or tetra)-methylene tri(or tetra)nitramine, tetryl, pentaerythritol tetranitrate, explosive grade nitrocellulose and nitro-starch.

The self-explosive fuel can be for example in any of the well-known flake, crystalline orpelleted forms. In general up to 35 percent and preferably from to 30 percent by weight based on the weight of composition of self-explosive fuel is used.

Suitable water soluble fuels are organic water soluble substances, for example urea, carbohydrates such as sugars or molasses, water soluble alcohols or glycols, glues or mixtures of these. The proportion of water soluble fuel in such compositions should be at least 0.8% w/w and may be as high as 8% w/w of the total composition. v

Suitable water insoluble or sparingly water soluble fuels may be chosen from inorganic materials for example sulphur, aluminium, silicon, magnesium, titanium, boron, mixtures thereof and mixtures of aluminium with ferro-silicon or organic materials for example finely divided charcoal, anthracite, gilsonite, asphalt, cellulosic materials such as sawdust, or cereal products for example flours, dextrins or starches. When the inroganic fuel is a metal it is preferably in powder form ranging in particle size from very fine, for example a powder passing a 200 B.S.S. sieve, to coarse, for example a powder retained on a 30 B.S.S. sieve. ln particular aluminium powder passing a 300 B.S.S. sieve, for example paint fine aluminium, may often be used with advantage as a fuel; it also acts as a sensitiser. The propor tion of water insoluble or sparingly water soluble nonmetallic fuels in such compositions is usually in the range from 1% w/w to 10% w/w of the total composition. The proportion of metallic water'insoluble fuels, such as aluminium, when present in such compositions may be as high as 25% w/w and amounts in the range from 1% w/w to 15% w/w of the total composition are usually preferred.

The proportion of water in such compositions should be suffiicent to dissolve at least part of the water soluble fuel when present, and part of the oxygen releasing inorganic salt, say from 5% w/w up to 35% w/w, but not be in excess of the explosive limit of the composition.

Many thickening agents (viscosity raising agents) are known which have been employed with varying degrees of success, either alone or in combination, in waterbearing explosive slurries. Amongst these may be mentioned galactomannan polysaccharides such as guar gum, Tara and Paloverde gums, pregelatinised starches, hydroxyethylcellulose, carboxymethylcellulose, tamarind seed flour and hydrophilic vinyl polymers such as polyacrylamide. The most widely used of these thickening agents have been the galactomannans, particularly guar gum.

When compositions comprising polysaccharides such as guar gum are mixed with appropriate crosslinking agents, the viscosity of the composition is increased. Any of the known crosslinking agents conventionally employed for galactomannans can be used including potassium and sodium dichromate, sodium tetraborate, borax, certain transition metal salts and certain soluble antimony and bismuth compounds. However, alkali metal dichromates, for example sodium and potassium dichromates, are especially preferred.

The proportion of polysaccharide and conventional crosslinking agent used in preparing 'the thickening agent component of the viscous slurried explosives can vary over quite wide limits depending on the agent used as is well known in the art. For example, using-guar gum with zinc chromate as the crosslinking agent the proportion of guar gum may vary from'0.l to 5% w/w of total composition and the proportion of zinc chromate may vary from 0.01 to 3% of total composition.

Alternatively a mixture of sodium or potassium dichromate and a soluble iron, zinc, aluminium or antimony salt may be used. For example if sodium or potassium dichromate is used the proportion of sodium or potassium dichromate in the viscous slurried explosive should be in the range from 0.003 to 0.9% w/w, the proportion of soluble salt should be in the range from 0.001 to 0.3% w/w of the viscous slurried explosive.

There are many alternative combinations of free flowing materials which will on mixing give a viscous crosslinked slurried explosive.

, Explosive slurries may also be thickened by viscosity raising agents formed from the in situ polymerisation of monomers or mixtures of monomers. Examples of monoethylenically unsaturated. monomers which are suitable include amides such as acrylamide, methacrylamide and N-methylacrylamide and hydroxyalkyl derivatives such as alpha,2-hydroxyethylacrylamide and alpha-hydroxymethylacfylamide; acids such as acrylic acid and methacrylic acid; salts of acrylic acid such as sodium, potassium or ammonium acrylate; and soluble salts of monovinylpyridines, particularly and preferably the nitrate salts of the 4-vinylpyridine. Acrylamide is a particularly preferred monomer because of its low cost and rapid polymerisation in the presence of free radical polymerisation promoters in the aqueous phase of the blasting compositions. Usually, the concentration of acrylamide used ranges from 0.3 to 10 percent and especially from 0.5 to 5 percent. Suitable promoters include sodium, potassium and ammonium salts of inorganic peracids such as persulphates, perborates and pervanadates; hydrogen peroxide and organic peroxide and azo catalysts such as azobis(isobutyronitrile),alpha,alpha'-a zobis(alpha,gamma-dimethyl-gammamethoxyvalero-nitrile), tertiary butyl hydroperoxide, methylvinyl ketone peroxide, benzoyl peroxide and peracetic acid. Persulphates are usually preferred. Redox systems, that utilise a source of persulphate ion (S,O ').as one component; are suitable throughout a range ofconcentrations of inorganic persulphate salt; can be used alone in the solution of inorganic oxidising salt to promote the copolymerisation reaction or an added reducing agent can also be employed to form a redox couple. Reducing agents that can also be used if desired include nitrogen bases such as hydroxylamine, carbohydrazide and, particularly, hydrazine. If needed, higher rates of polymerisation are achieved at lower temperatures when the polymerisation system also includes a minor amount of metal ion, usually a Group [B metal ion; These metalions' 'are introduced as soluble inorganic or organic salts, e.g. as the nitrates, sulphates or acetates. Other useful persulphate couples are I-ISO- (S2Og) and Fe -(S2O and SgO (S2Og) and nitro-tris-propionamide -(S O In general, the total amount of promoter used varies with the particular. promoter and monomers, and increases proportionately with the desired speed of polymerisation, but usually is at least 0.002 percent and preferably within the range of about from 0.002 to 3 percent based on the total weight of aqueous phase containing monomers to be polymerised, large excesses of promoter having no detrimental effect on the gel structure. The optimum concentration of the preferred persulphate ions, based on total monomers, i.e. both monoand polyethylenically unsaturated, can vary considerably depending'on the particular polymerisation system, the desired consistency of the gel, and the presence or absence of supplementary promoter components, but in general will be about from 0.005 to 2 percent by weight of'the aqueous phase.

In the past slurried explosives have been widely used in mining operations. Their major commercial use has been in open cut extraction of minerals but bulk loaded slurried explosives have not been used to any great extent in underground mining operations.

Packaged slurried explosives have been used in underground mining operations. Thus cartridge cases may,

be filled with slurried explosives in a factory anditransported to the mine for use. The cartridges'are, pushed into the borehole manually but it is difficult; to ensure that the borehole is completely filled andtherefore they are not reliable in use. Packaged slurried explosives are expensive and have none of the economies inherent in the use of bulk loaded slurried explosives. Bulk loaded slurried explosives are cheap and readily available and therefore it is surprising that they have not; been used widely in underground operations. The main reason for this lack of use resides in the fact that minimised. In addition the slurry is normally prepared and pumped at an elevated temperature so as to decrease the viscosity of the slurry.

This solution to the problem is not convenient for use underground as such operations must be carried out in the restricted spaces inherent in underground mining operations and it is difficult to provide supplies of the slurry raw material to the working area and also to find space at the point of use to fit in the large mixing and pumping unit required in the manufacture and use of explosive slurries.

The handling and manufacture of explosive slurries underground is hazardous especially if high temperatures are used to reduce the viscosity of the slurry. Boreholes in underground mining are often 300 or more feet away from the nearest point of access for heavy machinery so that even ifthe explosive slurry was prepared at'a high temperature, the temperature would fall by the time the slurry was pumped to the point of use.

A further difficulty in using explosive slurries underground is that the boreholes normally used underground are of a much smaller diameter than those used in open cut mining.

Small boreholes are used in underground mining operations because firstly, it is difficult,-and often impossible, to carry the large and heavy machinery required for boring large holes in the restricted passages adjacent to the working area and, secondly, because in underground mining there is a need for much greater control of blasting power to prevent ore dilution or excessive ground vibration leading to uncontrolled collapse of the roof of the mine passages.

The viscosity of explosive slurries suitable for use in long upwardly inclined boreholes is much greater than that required for the downwardly inclined boreholes normally used in above ground operations.

In downwardly inclined boreholes suitable explosive slurries need only have sufficient viscosity to prevent or reduce seepage of water desensitising the expolsive charge. In upwardly inclined boreholes suitable explosive slurries must in addition have sufficient viscosity to remain in place in the borehole. The required increase in viscosity of the explosive slurry also increases the shearing forces generated in the slurry when the slurry is manipulated by, e.g. pumping.

We have now found means whereby explosive slurries can be manipulated and used in restricted spaces.

Accordingly we provide an apparatus comprising in combination a primary pump adapted to .deliver explosive slurry through a hose more than 50 ft in length, connected to a secondary unit and a means of adding an additive to the slurry at, or after, the secondary unit.

We also provide a method of preparing a suitable ex-' plosive slurry for use in underground workingin restricted spaces which method comprises pumping explosive slurry through a hose to a secondary unit 10- cated in the restricted space and thence pumping the mixture to a borehole wherein an additive is added to the slurry at or after the secondary unit.

By secondary unit we mean a unit providing in combination a portable secondary pump and a portable buffer storage tank. Preferably the secondary unit is either of suitable dimensions and weight to be carried manually into the restricted areas without dismantling, or may be readily dismantled into easily portable sections and readily reassembled in a restricted area. We have found that it is often convenient to arrange the secondary unit so that it can be readily dismantled into a slurry pump section, a storage hopper section and additive tank and pump section.

The additive may be added to the slurry by any means known in the art. For example it may be added at the secondary unit or it may be injected into the hose leading from the secondary unit into the borehole. We prefer that the additive is pumped through a separate hose and mixed with the explosive slurry immediately prior to delivery of the slurry into the borehole. Preferably the means of adding the additive comprises an additive tank, the contents of which may be pumped via an additive pump through a separate hose to the end of the explosive slurry hose.

Preferably there is a means of automatically controlling the primary pump by the height of slurry in the slurry hopper of the secondary unit. The primary pump is automatically stopped when the hopper is full and restarts when slurry is removed from the slurry hopper.

Preferably the secondary unit is controlled by a remote control device which can be operated by an operator standing near the borehole to be filled. The advantage of using such a remote control device is that one operator may control the insertion of the hose into the borehole and also control the pumping of slurry into the borehole.

As a safety measure we prefer that a detonation trap is inserted between the bulk tank and the secondary unit. Suitable detonation traps are well known and include air voids or constrictions in the hose leading from the bulk tank to the secondary unit.

After use the slurry remaining the secondary unit and in the hose leading from the primary pump to the secondary unit may be returned by means of air pressure applied to the secondary unit. Thus using our system substantially all the explosive slurry prepared is used and large amounts of, difficult to dispose of, formed, highly viscous, sensitised, waste slurry are not encountered.

Preferably the additive is pumped in a separate stream into the borehole and mixed with the explosive slurry at the end of the hose carrying the explosive slurry into the borehole. Thus the additive and the slurry may be pumped into the borehole thorugh two separate hoses.

We prefer to encase the hoses carrying the separate streams of material in an outer casing or hose. In our preferred embodiment the hose carrying the major component of the product is used to encase the hoses supplying the streams of the minor components of the product. Alternatively a single hose may be used comprising two or more conduits.

The means of mixing the streams of material to form the product is any mixer of such dimensions that it can be inserted into the void when the mixer is attached to the end of the means for supplying the separate streams of materials.

Preferably the mixer is of the type known in the art as an interfacial surface generator mixer. Such a mixer is characterised by having no moving parts, but the mixer comprises a plurality of interfacial surface gener ators. It is also characteristic of such mixers that they may be made in any suitable external diameter. A suitable mixer, for example, is the Static Mixer manufactured by the Kenics Corporation of the U.S.A.

When the apparatus is used to fill boreholes with a slurried explosive, ideally the hose and mixing means should be withdrawn from the hole at, or approximately at, the rate at which it is being filled; however, it is, of course, impossible to observe the rate of charging visually and recourse must therefore be taken to indirect control, such as empirical operation or attempts to synchronise the linear rate of withdrawal with the linear rate of filling calculated from the pumping rate. As a rule this is a coarse approximation only and often maloperation results; if the hose is withdrawn too slowly it becomes embedded in the material and is likely to leave a columnar gap or cavity on being withdrawn or may even be permenently embedded in the slurry by excessive friction or blockages. Conversely, if the hose is withdrawn too rapidly, the material is likely to be dropped from a height above the rising surface of the slurry and entrap pockets of air or water. In most of these operations, discontinuity in the material filling of the hole is undesired or detrimental for the intended purpose.

Yet another problem is that boreholes frequently contain substantial quantities of water. lSlurried explosives dropped or pumped into such holes may be adversely affected by excessive dilution; for instance, the blasting agent mixture may not be initiated by a detonator or the explosion may fail to propagate through the mixture.

These difficulties may be overcome by use of a withdrawal apparatus. Withdrawal apparatus is defined as apparatus comprising a tube which is sealingly connected to the smaller opening of a truncated conical mantle made of a material sufficiently rigid or reinforced to be incapable of inversion, which mantle is mounted coaxially with, on and around said tube ator near its lower end and the wider opening of which mantle is nearer to the bottom end of said tube, and a flexible hose connecting the inlet end of said tube to the mixing means. The tube is either sealingly attached to the mixing means or may itself be the outer case of the mixing means.

The purpose of the truncated conical mantle is to seal the hose against the wall of the borehole; thereby the cavity into which the blasting agent is being discharged is sealed, ingress of water into it is minimised and the fluid discharge pressure of the pump is exerted against the enclosed end of the hole thus producing upward thrust against the seal formed by the hose and the surrounding truncated conical mantle. Consequently the pump pressure aids or effects the raising of the hose synchronously with the rate of charging.

Preferably said conical mantle can be folded axially, downwardly but not upwardly towards the axis of said tube, so as to envelop it at least partly; in this folded down position, not unlike an inverted, folded-up umbrella, said assembly of tube and mantle may readily be inserted into the hole and subsequently on withdrawal of the hose the mantle is unfolded into its conical shape.

The material of construction of the mantle is not critical, but it must be strong enough to withstand upward thrust into the cone of up to several hundred pounds without collapsing, without being inverted upwardly and without tearing; its ability to resist upward inversion is critical and determines the choice of material, its thickness and its reinforcement. It may be made of rigid material, eg a metal or plastic sheet or, preferably, or flexible material of sufficient thickness, e.g. a rubber or polyethylene terephthalate sheet; preferably the sheet is pretreated to facilitate the operation of folding it downwards, centrally around the tube, e.g. by providing axial folds in the rubber sheet or by making the cone of a number of metal vanes slideable against each other and capable of being unfolded into a progressively wider cone.

Preferably, also, flexible truncated cones, particularly rubber sheet cones, are reinforced by rods or strips running along the length of the cone in several, say, 2,3, 4 or 6 symmetrically placed positions; these strips may be made of particularly strong materials, e.g. spring steel and prevent inversion and expansion of the bottom opening of the cone beyond a predetermined size.

Optionally the larger opening of the truncated cone may be fitted at its widest (bottom) section with a skirt, which is an extension of the truncated cone, but is made .of a more flexible material such as rubber or foam rubber sheet and may act as a sealing washer at the walls of the hole between the discharged slurry and any water above it.

The term truncated cone implies that the central angle of the cone is, at all times, less than 180, in practice preferably less than 140 and most preferably less than 120. The larger, bottom outlet of the truncated cone, in its fully unfolded position forms a circle or quasicircle having a diameter which approximates the diameter of the borehole, but which is characterised in that it is substantially smaller than 21, wherel is the length of the conical mantle. By this means the above stated angles cannot be exceeded. Consequently, the cone can at no time be inverted upwardly without destruction since the'tensile strength of the sheet resists expansion beyond its maximum diameter; the term truncated cone includes cones of less regular shapes,

such as bulging cones, bell-like shaped cones or cones of somewhat irregular, quasicircular cross sections, the essential feature of thecone being that it is capable of enveloping a fluid thrust upwardly into it, without folding backward and that, inserted into a cylindrical or quasicylindrical hole, it is capable of forming against the wall of said hole a seal, or a restriction reducing the flow of liquids past it. I

The truncated cone may be sealingly attached to the tube exactly at or near the lower end of the tube which is to be inserted into the borehole; it may be wired on, or fittedremovably by means of a screw or bayonet fitting; the tube may protrude into the interior of the cone or even through both the top (small) and bottom (large) opening of the truncated cone. More than one, say 2 or 3 cones, mounted in series may also be used.

Preferably, additionally, there may be a cap closing the bottom (larger) opening of said truncated cone and removable from it by the pressure of fluid being discharged from the tube.

The nature of the additive is dependent on the nature of the explosive slurry. pumped from the tank into the secondary unit.

In general the physical nature of the explosive slurry .will fall between two extremes. At one extreme the slurry has adequate viscosityfor use in upwardly inclined holes but will be desensitised by the shearing forces generated in the hose leading to the secondary unit. At the other extreme the slurry will of of low viscosity so that sensitivity is not lost by pumping but the viscosity is not sufficient for use in upwardly inclined holes. ln slurries of the first extreme the additive required is a sensitizing agent such as e.g. the finely divided metal described hereinbefore. In slurries of the second extreme the additive required is a viscosity raising agent as have been described hereinbefore.

The explosive slurries used in practice will often fall between these two extremes and thus require the addition of both viscosity raising agents and sensitizing agents.

The apparatus of our invention will now be illustrated by reference to a preferred embodiment illustrated in FIGS. 1 and 2 wherein FIG. 1 is a schematic plan of a loading system of our invention, and FIG. 2 is a flow diagram of the system.

In FIG. 1 a bulk tank 1 is connected by means of hose 2 to the primary pump 3. The primary pump is connected to the secondary unit 4 through the hose 5. Crosslinking agent is stored in the tank 6 and pumped using the pump 7 to the static mixer 8 via the line 9. The slurry is pumped to the static mixer 8 through the hose l0.

The bulk tank 1 is of conventional construction and may either remain outside the mine or may be located in a main gallery in the mine. The primary pump 3, preferably a pneumatically powered pump is controlled by the air delivery valve 11. The valve 11 is preferably controlled by an automatic control 12 which automatically cuts off the pump 3 when the slurry hopper .13 is full and starts the pump 3 when the slurry hopper 13 is partially empty. Suitable automatic controls 12 are well known in the art; a convenient control is shown schematically in the figure. The slurry in the hopper 13 is pumped via the pneumatically driven pump 13 to the inline mixer 8 where it is mixed with crosslinking agent from the line 11. The loading hose 10 is fitted with a loading cone 15 and cap 16. The operation of the secondary unit may be controlled by an operator standing by the unit and manually controlling the rate-of the slurry pump 14 and the crosslinking agent pump 7, however we prefer that the pumps 14 and 7 are controlled by remote control from a point near the borehole to be filled. Suitable pneumatic remote control devices for such pumps are well known in the art.

The secondary unit may be readily dismantled into two parts by uncoupling the flanges shown in FIG..]

along the line AB. The two parts may be manually carried and readily reassembled.

We claim:

1. A method of filling boreholes from a restricted underground space which method comprises pumpingan explosive slurry from a bulk tank by means of a primary pump through a hose more than 50 ft. in length from a point outside the restricted underground space to a secondary un'it situated in the restricted underground space said secondary unit comprising a slurry hopper, a secondary pump, an additive tank and an additive pump; pumping the explosive slurry from the secondary slurry hopper by means of the secondary pump through a hose inserted into the borehole; pumping an additive from the additive tank by means of the additive pump into the slurry at, or after the secondary hopper; the operation of the primary pump being con- 9 w trolled automatically by the level of the slurry hopper sive slurry hose in the borehole. of the secondary unit, the secondary unit being con- 3. A method according to claim 1 wherein the explotrolled by a remote control device from a point adjasive slurry hose encases the additive hose and is termicent to the opening of the borehole; and said secondary nated by an interfacial surface generator mixer.

unit may be readily dismantled into readily portable 5 4. A method according to claim 1 wherein there is a sections and readily reassembled in a restricted area. detonation trap between the bulk tank and the second- 2. A method according to claim 1 wherein the addiary unit.

tive is pumped through a hose to the end of the explo-

Claims (4)

1. A method of filling boreholes from a restricted underground space which method comprises pumping an explosive slurry from a bulk tank by means of a primary pump through a hose more than 50 ft. in length from a point outside the restricted underground space to a secondary unit situated in the restricted underground space said secondary unit comprising a slurry hopper, a secondary pump, an additive tank and an additive pump; pumping the explosive slurry from the secondary slurry hopper by means of the secondary pump through a hose inserted into the borehole; pumping an additive from the additive tank by means of the additive pump into the slurry at, or after the secondary hopper; the operation of the primary pump being controlled automatically by the level of the slurry hopper of the secondary unit, the secondary unit being controlled by a remote control device from a point adjacent to the opening of the borehole; and said secondary unit may be readily dismantled into readily portable sections and readily reassembled in a restricted area.

2. A method according to claim 1 wherein the additive is pumped through a hose to the end of the explosive slurry hose in the borehole.

3. A method according to claim 1 wherein the explosive slurry hose encases the additive hose and is terminated by an interfacial surface generator mixer.

4. A method according to claim 1 wherein there is a detonation trap between the bulk tank and the secondary unit.

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