GB2338429A - Trailer mounted mixing apparatus for explosive emulsion of ammonium nitrate and gas oil - Google Patents

Abstract

The trailer has a hopper 4 for a mixture of ammonium nitrate prill and oil/water emulsion mounted on a tiltable subframe 14 which can be pivoted about a lower outlet 20 for discharging the contents under gravity. From the outlet 20 the nitrate prill/emulsion mixture is combined with gas oil from a tank 21 and pumped through a static mixer 8 for subsequent delivery via hose 25. The hopper 4 has a skew conical portion with the outlet 20 at the apex of the cone.

Description

2338429 1 1 Explosive emulsion mixing vehicle 2 3 This invention relates

to a vehicle for use in transporting and mixing the component parts of a pumpable explosive emulsion composition, particularly for use over rough terrain or over uneven ground.

4 5 6 7 8 Vehicles for the transport and mixing of bulk emulsions are know, such as those operated under the name 11Multiblendll by E xchem plc. These vehicles are trucks which have a hopper containing an oil/water emulsion and a hopper containing ammonium nitrate (AN) in the form of prills, which are granular in nature. The trucks are used to transport the bulk materials to the location where the explosive emulsion is to be used. During transport the bulk materials are not mixed and so do not present an explosive hazard. when the explosive emulsion is required, for example for pumping into predrilled holes, diesel or gas oil is added to the ammonium nitrate, the bulk components (emulsion and ammonium nitrate) are mixed together, gassing agents (sodium nitrate and acetic acid) are added to the mixture, and the mixture is pumped to the hole by means of an extendible hose. Tanks for the various additives (diesel, gassing agents etc) are provided on the truck, 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 2 1 2 3 4 6 7 8 9 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 as are the pumps, valves and control system which ensure the mixture is correctly mixed.

However, these trucks suffer from the disadvantage that they cannot operate on rough terrain, as is often found in quarry sites. The hoppers are mounted high above the vehicle chassis and the emulsion and AN are dispensed from the hoppers under gravity, with the result that a fully loaded truck has a very high centre of gravity and is prone to tipping when used on sloping ground.

It is an object of the present invention to provide a vehicle which can supply and mix explosive emulsion mixtures over rough terrain without tipping.

It is another object of the present invention to provide a method of mixing an explosive emulsion which does not require the presence of two large hoppers for the emulsion and AN.

According to a first aspect of the invention there is provided a mixing apparatus for mixing and delivering an explosive emulsion, comprising a hopper adapted to hold a mixture of emulsion and ammonium nitrate prill, a gas oil tank, an outlet pipe from said hopper, a feeding means adapted to feed gas oil from said gas oil tank to said outlet pipe, a pump adapted to pump said emulsion and ammonium nitrate prill from said outlet pipe to a delivery hose, and a static mixer, wherein: said outlet pipe is positioned at the bottom of said hopper; said hopper is tiltable about a horizontal axis from a lowered position to a raised position; and said hopper is shaped such that said outlet pipe is positioned at the bottom of the hopper in the raised 3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 21 22 23 24 25 26 27 28 29 31 32 33 34 35 36 position.

Preferably the hopper comprises a conical portion, most preferably a skew conical portion, the outlet pipe being positioned at the apex of the cone.

Preferably the hopper further comprises a cylindrical portion communicating with the conical portion. Preferably the axis of said cylindrical portion is horizontal in the lowered position. Preferably the outlet pipe is at substantially the same level as the lowest edge of the cylindrical portion in the lowered position.

Preferably the hopper is mounted on a tiltable subframe. Preferably the outlet pipe and/or the pump and/or the static mixer are also mounted on the subframe. Preferably the apparatus comprises a hydraulic ram adapted to raise and lower the subframe. Preferably the subframe is adapted to tilt from a substantially horizontal position in the lowered position to an angle of inclination between 300 and 900 from the horizontal in the raised position.

Preferably the hopper has a filling hole at the top of said hopper when the hopper is in the lowered position.

Preferably the apparatus further comprises a wheeled chassis. Preferably the apparatus further comprises a hose reel mounted on said chassis and comprising a delivery hose. Preferably the apparatus further comprises a flexible hose which connects the outlet pipe to the hose reel and which is adapted to permit relative movement of the hose reel and outlet pipe when the hopper tilts between the lowered and raised positions.

3 4 Preferably the apparatus comprises attachment means adapted to attach to a tractor and permit the towing of the apparatus by a tractor. Preferably the apparatus comprises drive take-off means adapted to take hydraulic and/or rotary power from a tractor.

4 5 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 i.; I b) c) d) e) According to a second aspect of the invention there is provided a method of mixing and delivering an explosive emulsion, comprising the following steps: a) delivering a gas oil-free mixture of emulsion and ammonium nitrate prill in a hopper on a wheeled apparatus, providing gas oil in a separate tank, dispensing under gravity the mixture of emulsion and ammonium nitrate prill from said hopper, adding gas oil to said mixture to form an explosive emulsion, and pumping said emulsion to a delivery hose.

Preferably the method comprises the further step of raising the hopper on the wheeled apparatus to assist the gravity dispensing of the mixture.

Preferably the method comprises the further step of adding gassing agents, most preferably sodium nitrite and/or acetic acid to the mixture. Preferably the method comprises the further step of mixing the explosive emulsion by means of a static mixer.

Preferably the method uses an apparatus according to the first aspect.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying figures, where:

1 3 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 1 Fig 1 shows a side elevation of an apparatus according 2 to the invention; 4 Fig 2 shows a plan of the apparatus of Fig 1; Fig 3 shows a section through Fig 2 on line A-A; and Fig 4 shows a side elevation of the hopper of the apparatus of Fig 1.

Referring to Figs. 1 to 3 there is shown an apparatus according to the invention mounted on a trailer. The trailer has a chassis 1 and wheels 15, and can be connected by coupling 16 to a tractor. on the trailer is a hydraulic pump 12 which may be connected to the tractor (not shown) to provide hydraulic power for the apparatus.

Mounted on the chassis 1 by means of a hinge 17 is a tiltable subframe 14. The subframe tilts by action of a hydraulic ram 18 connected to the subframe and chassis. Fixed to the subframe 14 is a hopper 4, which has a hatch 19 at the top into which can be loaded a mixture of ammonium nitrate prill and oil/water emulsion. The hopper is made of a cylindrical barrel part 41 connected to a conical part 4" which narrows down to a neck 20 at one end. The neck 20 is positioned so that it remains at the lower point of the hopper 4 even when the subframe is tilted. An outlet pipe 22 is connected to the neck 20, so that the mixture of ammonium nitrate (AN) prill and emulsion can be fed through the outlet pipe under gravity. The hopper 4 has a capacity of about 2600 litres typically, so that it can carry a load of about 3 Tonnes.

Also mounted on the subframe 14 are a progressive f 1 2 3 4 5 6 7 8 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 6 cavity pump 9 (such as a pump supplied by PCM Moineau) and various valve connections (not shown) which permit the addition of additives to the AN/emulsion mixture. Flexible hoses lead from the valve connections to the additive storage tanks which are mounted on the chassis. A gas oil or diesel tank 21 is mounted at the front of the trailer and a hose 23 delivers gas oil so that it can be mixed with the AN/emulsion to form an explosive emulsion. Gassing agent tanks 5 of typically 100 litre capacity are mounted at the rear of the trailer and deliver sodium nitrite and acetic acid to the explosive mixture by means of hoses 24. From the pump 9 a pipe leads to a static mixer 8 and then to a flexible pipe 25 which delivers the explosive mixture to a delivery hose 26 mounted on a hose reel 6. The delivery hose is typically 40m long with a 32mm diameter bore. The hose reel 6 is mounted at the rear of the trailer. A rotary coupling 27 allows relative rotation of the hose reel 6 and the flexible pipe 25. A ring jet 28 allows the injection of water into the pipe 25 to reduce friction in the hose 26.

Also mounted on the trailer are a compressor 13 for blowing out the hose, a hydraulic oil tank 2 (typically 250 litres capacity) for the hydraulic motors and ram, and a water tank 3 (typically 250 litres capacity), which stores water for the ring jet 28, for lubrication of the gland of the pump 9 and for high pressure water washing of the delivery system after use. The water pump 11 and gland flush pump 10 are mounted on the trailer near the water tank 3.

Control panels 7 for operation of all aspects of the mixing procedure are provided at the rear end of the trailer 1.

7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 The trailer is provided with outriggers 30 so that the trailer is fixed in a stable position where necessary before the hopper is raised.

In use the hopper holds about 2600 litres, and about two thirds of the contents can be dispensed without needing to raise the hopper. When it is necessary to provide a greater hydraulic head for the AN/emulsion mixture, which is fairly viscous, the subframe 14 is lifted hydraulically by means of the ram 18 so that the subframe tilts to an angle of about 450.

The apparatus of the present invention has a low centre of gravity, meaning that the trailer can be pulled over rough terrain and sloping ground without danger of tipping. The hopper can be raised by tilting when necessary, once the trailer is in position for supplying the explosive emulsion, but it is not necessary to transport the trailer with the hopper in the raised position. The shape of the hopper is selected to give a low centre of gravity of a filled hopper.

Prior art delivery trucks have two separate hoppers for the emulsion and AN, and these components are only mixed once the truck is in position for supplying the explosive emulsion. The nature of AN prill means that when supplying it in an unmixed state it is necessary to have a vertical hopper to ensure smooth delivery. It would be unsafe to transport a ready mixed mixture of emulsion, AN and diesel, or a mixture of diesel and AN, since such a mixture is classified as an explosive and strict regulations apply to its transport. The invention overcomes these problems by transporting only a safer mixture of AN and emulsion, tilting the hopper to avoid the need for a high fixed hopper, and

1 1 1 1 - 1 2 3 4 5 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 8 supplying the diesel separately.

The method of making the explosive emulsion using the apparatus of the invention differs from the method of the prior art in that diesel or gas oil is added after mixing the AN prill and emulsion. In the prior art AN prill and emulsion are stored in separate hoppers, and the diesel is added to the AN prill. Tests have been carried out to determine whether the method of the invention provides satisfactory results. The tests are described below.

EXAMPLE 1

The following tests were carried out to determine if satisfactory Blendex 70 (a Trade Mark of Exchem plc describing an explosive emulsion) can be made if diesel is added to an emulsion/AN blend using an apparatus according to the invention.

The laboratory tests suggest that Blendex 70, with late addition of the diesel:

a. can be mixed satisfactorily; b. is stable to loss of gas; and C. has satisfactory sensitivity.

Introduction

The use of a pre-mix of emulsion/AN/diesel (ungassed Blendex 70) would be unlikely to be acceptable to safety authorities. However, a pre-mix of emulsion/AN, with the diesel added together with the gassing agents when loading the holes, would be more acceptable. Laboratory tests investigated the feasibility of this later addition of diesel and the effect on the 1 1 sensitivity of Blendex 70.

4 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 9 Discussion The mixing tests were carried out in the laboratory Guedu bowl. A mixing method modified from that normally practised for Blendex 70 was used. Ingredients are added consecutively with some mixing after each ingredient is added. This models the sequence on the trailer of the invention. The amount of mixing is not directly related to that on the truck. It is, however, chosen so as to give a near uniform product at each stage and a uniform final product without over-mixing. The mixing on a vehicle seems to be at least as effective. The modification of the mixing method for the present work involved adding the diesel to the mix at a later stage.

The later addition of diesel did not cause any significant problems with mixing Blendex 70. It was nearly all absorbed, but not mixed in homogeneously, after its initial mixing stage. After the final mixing stage, there was no visible difference from Blendex 70 mixed in the normal manner.

It was postulated that the diesel could thin down the emulsion and allow easier escape of gas bubbles. A sample kept for three days showed no more than the minimal change in density expected. The stability of the Blendex 70 is therefore considered to be satisfactory.

The sensitivity to initiation of the Blendex 70 produced was satisfactory. It detonated at both low and high densities.

i 2 1 The use of matrix alone would have several advantages:

3 no premixing with AN required no storage or immediate use problems with the matrix 6 no diesel required pumping should be easier 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Experimental The normal laboratory mixing procedure for Blendex 70 in the lab Guedu bowl is as follows:

AN is placed in the bowl and then the diesel is added to it. This is mixed for 30 turns of the Guedu handle. The emulsion is added and the mix stirred for 30 turns. 40% acetic acid is added and mixed for a further 30 turns. Finally, the nitrite solution is added and mixed in with two lots of 30 turns.

After each group of 30 turns, the sides, the mixing paddle, bowl sides and central pillar are scraped down.

After the first 30 turns the diesel is absorbed by the AN, but may not be homogeneous. The appearance after addition of the emulsion and its 30 turns depends on how the emulsion was added to the ANFO mix. If the emulsion was spread out over all the ANFO, then the composition appears uniformly mixed after 30 turns. if the emulsion was added in one place in the bowl then after 30 turns an area will still appear to be AN rich. After the further 30 turns for the acetic addition, the AN appears uniformly distributed and the acetic has been absorbed. A total of 60 turns is used for the sodium nitrite solution. It may be absorbed after 30 turns but a total of 60 is used to ensure uniform 1 2 3 4 5 6 7 8 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 mixing.

For the Blendex 70 achieved by the present invention, a modified mixing procedure was used. Two batches of Blendex 70 were prepared. One was made with a small quantity of sodium nitrite solution to produce a high density batch. This was test-fired with a Beston 8L booster to determine if there was any effect on sensitivity.

The second used the normal production quantities of gassing agent to give a low density batch of Blendex 70. The sample from this was retained to see if there was any undue change in the density with age. The main part of the batch was also test fired with a Beston 8L booster.

The mixing methods used with the low density and high density batches differed slightly.

For the high density batch:

Emulsion was added to AN in the Guedu bowl and the mix stirred for 30 turns. Acetic acid was added and stirred for 30 turns. The diesel was then added and stirred for a further 30 turns. Finally, the sodium nitrite solution was added and stirred for two lots of 30 turns.

The diesel appeared to be absorbed after its 30 turns. The batch was cartridged into an 85 mm diameter RP cartridge, with a sample added to a weighing pot for density determination. After overnight storage, the cartridge was fitted with a witness line and test fired with a Beston 8L booster.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 E A 12 For the low density batch:

Emulsion was added to AN in the Guedu bowl and the mix stirred for 30 turns. Acetic acid was added and stirred for 30 turns. The diesel and the nitrite solution were both added to the bowl and mixed in with two lots of 30 turns. After the first of the last pair of 30 turns, the diesel (and nitrite) seemed to be absorbed at first glance, but not uniformly. Closer examination when scraping the sides showed some small amounts of lower viscosity material - probably diesel, though possibly thinned down matrix. After the final 30 turns the mix appeared uniform. It was cartridged into an 85 mm diameter RP cartridge, with a sample added to a weighing pot for density determination. After overnight storage, the cartridge was fitted with a witness line and test fired with a Beston 8L booster. The density pot was retained for further examination. The density was rechecked, with the addition of further product, if necessary, after two and three days.

A further high density batch of Blendex 70 was made, but following the method used for the low density batch, ie adding the diesel and nitrite together. There were no problems with mixing and the final product appeared uniform. It was cartridged into an 85 mm diameter RP cartridge, with a sample added to a weighing pot for density determination. After overnight storage, the cartridge was fitted with a witness line and test fired with a Beston 8L booster.

The laboratory mixing method chosen differs from what would be most representative of what will happen on the trailer. On the trailer the diesel and acetic acid will be added together before the pump. The nitrite will be added later, after the pump and before a stati 13 1 mixer [4]. In the lab experiments adding the diesel 2 with the nitrite solution is therefore more severe. 3 14 Table 1 - Blendex 70 Compositions Tested High Density Low Density (parts) (parts) AN (D8 Prillex) 29.10 RC7192 Emulsion 70.00 40% acetic acid 0.32 Diesel 0.90 20% sodium nitrite 0.06 1 0.22 plant samples Table 2 - Test Results High Low Density High Density 1 Density 2 oil mixing okay after not quite okay after turns uniform 30 turns, after 30 may not be turns; okay quite after 60 uniform turns Gassed Density 1.29 kg/1 1.15 kg/1 1.29 kg/1 Detonated? Y Y Y Y complete detonation Table 3 - Variation in Density with Age Age Density (days) (kg/1) 0 1.15 2 1.16 3 1.16 Blendex 70 produced normally shows an average density increase of 0.01 kg/1 every two days.

-1 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 EXAMPLE 2

The following tests were carried out to determine if it is possible to develop a pumpable Blendex composition, with the same oxygen balance as Blendex 70, that can be made on the proposed trailer if diesel is added to an emulsion/AN blend on the trailer.

The laboratory tests gave the following results:

The composition developed and tested was Blendex 75.5, which contained 0. 5% diesel compared to 0.9% in Blendex 70. Blendex 75.5% is:

RC7192 Emulsion AN Diesel 75.5 24.0 0.5 2. The smaller amount of diesel used for Blendex 75.5 blended in easier than the diesel in Blendex 70.

3. The sensitivity of Blendex 75.5 to initiation was satisfactory.

Introduction

Tests on the Blendex 70 system (see Example 1) showed that it could be made without any undue problems. However, it needs a reasonable amount of mixing to incorporate the diesel. Therefore, this work looks at a system with less diesel but with the emulsion:AN ratio increased to maintain the same oxygen balance as Slendex 70.

i 1 Discussion 2 3 4 5 6 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 16 Blendex 70 made on the Multiblend truck has the diesel flow spilt. Half is added alone to the AN. The other half is added at about the same place as the emulsion matrix. There doesn't seem to be problem with incorporating the half amount of diesel at this point. Blendex 70 uses 0. 9% diesel. So 0.45 parts diesel is mixed with 70 parts emulsion (plus some AN/diesel). I therefore looked at a composition containing 0.5% diesel. Arranging the composition to have the same oxygen balance as Blendex 70 gave:

RC7192 Emulsion AN Diesel 75.5 24.0 0.5 Details of the oxygen balance are given in Table 1.

Mixing tests with this composition were carried out in a laboratory Guedu bowl in the same manner as for the Blendex 70 in Example 1. The smaller amount of diesel used for Blendex 75.5 blended in easier than the diesel in the Blendex 70. The sensitivity of the Blendex produced was satisfactory.

Experimental The mixing method used was that developed for mixing Blendex 70 using trucks. The Blendex mixture is prepared in the laboratory Guedu bowl. The diesel and nitrite solution are added last and mixed in together for 60 turns.

Two batches of Blendex 70 were prepared. one was made with a normal quantity of nitrite solution and one with 17 1 2 3 a small quantity, to produce a high density batch. The formulations are given in Table 2. In both cases, the batch was cartridged into an 85 mm diameter RP cartridge, with a sample added to a weighing pot for density determination. After overnight storage, each cartridge was fitted with a witness line and test fired with a Beston 8L booster. Comments on the mixing, the gassed density and the test firing results are given in Table 3.

4 5 6 7 8 9 18 Table 1 - Oxygen Balance (OB) of Blendex Compositions Ingredient In-redient OB Blendex 70 Blendex 75.5 Composition OB contribution Composition OB contribution AN 0200 29.1 5.82 24.0 4.80 Diesel -3.478 0.9 -3.13 0.5 -1.74 Emulsion -0.0662 70.0 -4.63 75.5 -5.00 1 Total 100.0 -1.94 100.0 -1.94 The effects of the gassing agents are ignored for convenience in this calculation. They will have the same effect in both cases.

Table 2 - Blendex 75.5 Compositions Tested High Low Density Density (parts) (parts) AN (D8 Prillex) 24.00 RC7192 75.50 Emulsion 40-15 acetic acid 0.32 Diesel 0.50 20% sodium 0.05 0.22 nitrite plant samples 19 Table 3 Test Results Low Density High Density Oil Mixing all oil and nitrite both oil and nitrite absorbed after 30 solution appeared turns, though may not fully absorbed after have been uniformly 30 turns distributed Gassed Density 1.13 kg/1 1.29 kg/1 cl 9 Y Y Detonat.

Y complete detonation 1 2 3 4 5 6 7 8 Although the drawings show the apparatus mounted on a trailer, the apparatus may be mounted on a motorised vehicle. other shapes of tiltable hopper are possible, for example a non-circular cone which is positioned with one edge horizontal in the lowered position. The hopper may be cylindrical, or parallelepiped shaped.

The terms diesel and gas oil are used interchangeably in the specification. These and other modifications and improvements can be incorporated without departing from the scope of the invention.

Claims (1)

1 CLAIMS:

2 3 4 5 6 7 8 9 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 1. A mixing apparatus for mixing and delivering an explosive emulsion, comprising: a hopper adapted to hold a mixture of emulsion and ammonium nitrate prill; a gas oil tank; an outlet pipe from said hopper; a feeding means adapted to feed gas oil from said gas oil tank to said outlet pipe; a pump adapted to pump said emulsion and ammonium nitrate prill from said outlet pipe to a delivery hose; and a static mixer; wherein: said outlet pipe is positioned at the bottom of said hopper; said hopper is tiltable about a horizontal axis from a lowered position to a raised position; and said hopper is shaped such that said outlet pipe is positioned at the bottom of the hopper in the raised position.

2.

A mixing apparatus according to Claim 1, wherein the hopper comprises a conical portion.

3. A mixing apparatus according to Claim 2, wherein said conical portion is a skew conical portion.

4. A mixing apparatus according to either Claim 2 or Claim 3, wherein the outlet pipe is positioned at the apex of the conical portion.

5. A mixing apparatus according to any of Claims 2 to 4, wherein the hopper further comprises a 21 1 2 3 4 6.

6 7 8 9 7.

11 12 13 8.

14 is 16 17 9.

18 19 21 10.

22 23 24 26 27 28 11.

29 31 32 33 34 35 36 cylindrical portion communicating with the conical portion.

A mixing apparatus according to Claim 5, wherein the axis of said cylindrical portion is horizontal in the lowered position.

A mixing apparatus according to either Claim 5 or Claim 6, wherein the outlet pipe is at substantially the same level as the lowest edge of the cylindrical portion in the lowered position.

A mixing apparatus according to any preceding claim, wherein the hopper is mounted on a tiltable subframe.

A mixing apparatus according to Claim 9, wherein the apparatus further comprises a hydraulic ram adapted to raise and lower the subframe.

A mixing apparatus according to either Claim 8 or Claim 9, wherein the subframe is adapted to tilt from a substantially horizontal position in the lowered position to an angle of inclination between 300 and 900 from the horizontal in the raised position.

A mixing apparatus according to any preceding claim, wherein the hopper has a filling hole at the top of said hopper when the hopper is in the lowered position.

12. A mixing apparatus according to any preceding claim, wherein the apparatus further comprises a wheeled chassis.

22 1 2 3 4 6 i 7 8 9 10 11 12 13 14 is 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 13. A mixing apparatus according to Claim 12, wherein the apparatus further comprises a hose reel mounted on said chassis and comprising a delivery hose.

14. A mixing apparatus according to Claim 13, wherein the apparatus further comprises a flexible hose which connects the outlet pipe to the hose reel and which is adapted to permit relative movement of the hose reel and outlet pipe when the hopper tilts between the lowered and raised positions.

15. A mixing apparatus according to any preceding claim, wherein the apparatus comprises attachment means adapted to attach to a tractor and permit the towing of the apparatus by a tractor.

16. A method of mixing and delivering an explosive emulsion, comprising the following steps: delivering a gas oil-free mixture of emulsion and ammonium nitrate prill in a hopper on a wheeled apparatus; providing gas oil in a separate tank; dispensing under gravity the mixture of emulsion and ammonium nitrate prill from said hopper; adding gas oil to said mixture to form an explosive emulsion; and pumping said emulsion to a delivery hose.

17. A method according to Claim 16, wherein the method comprises the further step of raising the hopper on the wheeled apparatus to assist the gravity dispensing of the mixture.

18. A method according to either Claim 16 or Claim 17, 23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 wherein the method comprises the further step of adding gassing agents to the mixture.

19. A method according to Claim 18, wherein the gassing agents are sodium nitrate and/or acetic acid.

20. A method according to any of Claims 16 to 19, wherein the method comprises the further step of mixing the explosive emulsion by means of a stati mixer.

21. A method according to any of Claims 16 to 20, wherein the method uses an apparatus according to any of Claims 1 to 15.

16 17 22. A mixing apparatus as hereinbefore described with 18 reference to the accompanying drawings.

19 23. A method of mixing and delivering an explosive 21 emulsion as hereinbefore described with reference 22 to the accompanying drawings.