AU2021318904A1 - Granulated explosive based on a water-in-oil emulsion, and production and use thereof - Google Patents

Abstract

In a first aspect, the present invention relates to a granulated explosive based on a water-in-oil emulsion with one or more oxygen carriers, water, one or more fuel carriers and emulsifier. The invention also relates to a method for producing a granulated explosive according to the invention based on a water-in-oil emulsion containing oxygen carriers, water, fuel carriers and emulsifier. The invention lastly relates to a granulated explosive obtainable using the method according to the invention and to the use of the granulated explosive according to the invention.

Description

GRANULATED EXPLOSIVE BASED ON A WATER-IN-OIL EMULSION, AND PRODUCTION AND USE THEREOF

In a first aspect, the present invention relates to a granulated

explosive based on a water-in-oil emulsion with one or more

oxygen carriers, water, one or more fuel carriers and emulsifier.

Additionally provided is a method for producing a granulated

explosive according to the invention, based on a water-in-oil

emulsion, containing oxygen carriers, water, fuel carriers and

emulsifier. Lastly described is a granulated explosive

obtainable using the method according to the invention, and the

use of the granulated explosive according to the invention.

Prior art

Granular explosives based on ammonium nitrate, as typical

examples of commercial explosives used across a wide variety of

different sectors, are composite explosives. These so-called ANC

(ammonium nitrate-carbon) and ANFO (ammonium nitrate-fuel oil)

or ANDEX explosives are provided in the form of a flowable

mixture of ammonium nitrate and carbon carriers. ANFO is produced

typically in the form of millimeter-size porous granules, which

are also referred to as prills, by mixing with liquid

hydrocarbons, typically oil. The reaction of such explosives is

associated with the evolution of comparatively high amounts of

toxic blasting fumes. In particular, nitrogen oxides (NO and

NO 2 ) and also carbon monoxide (CO) represent critical fume

constituents, which must be reduced to the achievable minimum

for the protection of people and environment. Especially in mines

and underground pits, in other words in subsurface mining, there

is a requirement to reduce nitrogen oxide emissions (NOx). In

underground mining, the blasting fumes given off are conducted

as foul air through the mine workings, and the stated gases

pollute the underground working atmosphere (air). The workplace limits for components of these gasses in the air breathed in, are strictly regulated. Correspondingly there is a requirement to provide low-emission explosives, preferably in granular form, which when used give off only small amounts of environmentally and physiologically harmful off-gasses, in other words to further reduce the fraction of possible harmful gas components, including NOx, in the blasting fumes that are released.

Granular emulsion explosives represent a further embodiment of

such suitable explosives. Here, for example, there is the Landex®

product from Kayaku Japan Ltd., in the form of a granular

emulsion developed primarily for tunneling. The granules in the

form of pellets, are produced by extrusion and are composed,

along with the oxygen carriers ammonium nitrate and sodium

nitrate, of a fuel phase with emulsifier, wax and resin. This

product necessarily requires the presence of hollow microspheres

for sensitization; see also Taguchi et al., Sci. Tech. Energetic

Materials, 2005, 66, 393-397. An essential feature of this

product is that the structure is relatively soft and hence on

mechanical stressing, such as in pneumatic charging procedures

on densely packed charge columns, the extruded pellets are

deformed and crushed. By varying the pneumatic insertion

pressure it is therefore possible to adapt the density of the

charge column and thereby to exert a targeted influence over the

detonation properties, such as the velocity of detonation. The

presence of the hollow microspheres ensures the detonation

capability of the charge column even with the borehole filled

out to the maximum. Because of the comparatively low strength

and the presence of the hollow glass microspheres, however, this

product can only be sold in small packaging units of not more

than 20 kg; shipment and storage in large quantities is not

possible. Furthermore, after the detonation, it is possible for remnants of the hollow microspheres - i.e. the glass fragments - to be present in the blasted material.

The advantage of emulsion explosives, in comparison to conventional granular explosives, such as the aforementioned ANFO explosive, is an even greater reduction in the toxic blasting fumes. This is due to the intense mixing of the fluidized reaction partners within the emulsion. The finely disperse state is achieved through the homogenization of the fluid phases. Within solid bodies, such as ammonium nitrate prills, where the contact area of the reaction partners is determined by the pore network and the dimension of the solid state structure, this is possible only to a limited extent.

Emulsions are disperse systems composed of at least two mutually immiscible liquids, where the dispersed phase is present in the form of distributed droplets within a continuous phase. Water in-oil emulsions are emulsions where water is present as the disperse phase in a continuous oil phase. An essential feature of emulsions is the finely disperse state of the disperse phase. In the case of emulsion explosives, the emulsion matrix is a water-in-oil emulsion, with the fuel, in the form of mineral oil, for example, the continuous phase, and a supersaturated solution of oxidizing salts (oxygen carriers) constituting the disperse phase. The contact area of the reaction partners is increased substantially in comparison to conventional ANC explosives, owing to the finely disperse structure with droplet sizes in an order of magnitude of 10 pm, and the reactive reaction is additionally promoted by the dissolved state of the oxygen carriers. Corresponding structural properties favor the stoichiometrically balanced reaction of the composite explosive, and so the energy utilization of the reaction increases and fewer toxic reaction products are formed. Emulsion explosives, described for example in US3447978A, have been used commercially since the 1980s/1990s, and there are also descriptions of emulsion preparations which are solidified by polymerization reaction and employed in the form of cartridged explosives. In the prior art, furthermore, the structuring of granular emulsion explosives via the solidification of the continuous phase is described; the shaping may be accomplished by spray drying, vacuum pelletizing, or comminution of the cured emulsion matrix.

CN 101555183 B describes emulsified explosive particles

comprising ammonium nitrate with at least one further oxygen

carrier from among sodium nitrate, aluminum nitrate, calcium

nitrate and magnesium nitrate, water, emulsifier, specifically

sorbitan monooleate or a mixture of sorbitan monooleate and

polyisobutylene succinimide, and a fuel carrier based on

paraffin, ceresin, rosin, asphalt and/or stearic acid. Known

from CN 110357755 is the production of mixed emulsion explosives,

which comprises adding an aqueous solution and an oil-phase

solution to an emulsifier to form a water-in-oil structure.

One problem of emulsion explosives is the use of water as solvent

for the oxygen carriers, as the water is detrimental to the

energy content of the explosive. In order to reduce the amount

of this inert component, the heavy temperature-dependence of the

solubility of oxygen-supplying salts is utilized, which rises

significantly as temperatures increase. The water content of

completed emulsions is usually 10% to 20%, as also in the above

mentioned Landex@ product.

Additionally there are usually emulsifiers present, which are

soluble in the continuous phase and lead to a critical reduction

on the surface tension.

An aim of the present invention is to provide granular explosives, especially those based on ammonium nitrate, which feature a reduced fraction of toxic gas components, especially NOx, in the blasting fumes released, with correspondingly high energy contents.

Description of the invention Improved emulsion explosives can be provided by improving the composition in respect of the oxygen carriers, water, fuel carriers and emulsifiers in order to provide granulated explosives based on a water-in-oil emulsion. These granulated explosives of the invention, based on a water-in-oil emulsion, exhibit much lower values in terms of the emission of the toxic gas components and especially of the NOx compounds (nitrogen oxide), but also of CO (carbon monoxide), in the blasting fumes released, while achieving a very good blasting effect. Provided accordingly, in a first aspect, is a granulated explosive based on a water-in-oil emulsion, comprising: oxygen carrier with a mass fraction of 78 to 90%; water with a mass fraction of 5 to 10%; fuel carrier with a mass fraction of 3 to 7%; and emulsifier with a mass fraction of 0.1 to 3%.

It has emerged that, relative to conventional ANC explosives, these granulated explosives have very much lower NOx fume volumes. It has been possible, furthermore, to achieve higher velocities of detonation relative to conventional explosives, especially to a granular explosive such as ANDEX LD as an example of an ANFO explosive.

In one embodiment the granulated explosive based on a water-in oil emulsion consists of oxygen carrier with a mass fraction of 80 to 90%; water with a mass fraction of 5 to 10%; fuel carrier with a mass fraction of 3 to 7%; and emulsifier with a mass fraction of 0.1 to 3 wt%, the total mass being 100%.

It has been found that these proportions and amounts of the individual components provide a granular emulsion explosive having very good usability.

Because the explosive of the invention contains less water by comparison with prior-art granular emulsion explosives, an example being the explosive sold under the Landex@ product name, the product is firmer, has good flow behavior, and in particular also displays improved storage stability.

A high water content additionally means that caking of the granulated explosive may occur and therefore impairs its use, particularly the charging of the blast boreholes.

The oxygen carrier may be one compound or a combination of compounds. In one embodiment the oxygen carrier is selected from alkali metal and alkaline earth metal nitrate, ammonium nitrate, alkali metal and alkaline earth metal chlorate, ammonium chlorate, alkali metal and alkaline earth metal perchlorate and ammonium perchlorate. Alkali metal nitrite or chlorate and perchlorate include sodium nitrate, potassium nitrate, sodium chlorate, potassium chlorate, sodium perchlorate and potassium perchlorate. Alkaline earth metal nitrate and chlorate and perchlorate include magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, calcium chlorate, strontium chlorate, barium chlorate, magnesium perchlorate, calcium perchlorate, barium perchlorate and strontium perchlorate.

In one embodiment a constituent of the oxygen carrier is ammonium

nitrate.

Ammonium nitrate is used typically in combination with a second

nitrate, especially an alkali metal nitrate, such as sodium

nitrate. In one embodiment in this case the oxygen carrier is a

mixture of ammonium nitrate and sodium nitrate, with the mass

ratio of ammonium nitrate to sodium nitrate being 5 to 8:1. In

one embodiment, however, the oxygen carrier ammonium nitrate is

also used on its own in the granulated explosive of the

invention.

If ammonium nitrate is used on its own, then in one embodiment

additionally an auxiliary is added, in particular for seeding

the crystallization of the ammonium nitrate in the granulated

explosive. The skilled person knows of suitable auxiliaries for

seeding. This auxiliary is added typically at not more than 0.5

percent by mass.

In one embodiment the granulated explosive is one based on a

water-in-oil emulsion, the fuel carrier being selected from

plant wax, plant oil, animal oil and fat, paraffin wax, light

crude oil, kerosine, mineral oil, lubricating oil, heavy oil,

carboxylic acid, carboxylic ester and microcrystalline wax, or

else combinations of at least two fuel carriers. Suitable fuel

carriers include in particular a paraffin, stearic acid and salts

of this carboxylic acid, such as magnesium stearate.

Monocarboxylic acids and their salts, especially salts with

alkali metals and alkaline earth metals, are preferred. In one

embodiment the fuel carrier is stearic acid. In another

embodiment the fuel carrier is a combination of stearic acid and

magnesium stearate or stearic acid with paraffin.

One embodiment of the present invention, then, relates to granulated explosives of this kind, the fuel carrier being at least one selected from paraffin, animal or plant oil and salts thereof, especially paraffin or stearic acid. Likewise possible are the combinations of these fuel carriers, especially paraffin and stearic acid, or stearic acid and stearate, or paraffin and stearic acid and stearate. The paraffin and stearate combination is also conceivable.

In accordance with the invention there is an emulsifier in the granulated explosive. Suitable emulsifiers are, for example, those based on polyisobutylene-succinic anhydride (PIBSA), based on sorbitan monoisostearate (SMIS), or an emulsifier based on polyisobutene lactone (PIB lactone), or mixtures thereof. In general an emulsifier may consist of one or a mixture of two or more emulsifiers. In one preferred embodiment the emulsifier is based on PIBSA. Emulsifiers are known in the form, for example, of products from Lubrizol or Croda Mining, such as Anfomul.

One embodiment uses only one emulsifier, this emulsifier being one, for example, based on PIBSA or one based on PIB lactone. It is optionally possible to use two or more emulsifiers based on PIBSA or two or more emulsifiers based on PIB lactone.

In one embodiment the water fraction in the granulated explosive is a mass in a range with a mass fraction of 6% to 10%, such as 6.5% to 9.5%, more particularly 6.5% to 9%, based on the total mass of the explosive. If the fraction of water is too high, the transportability and storability and also the flow behavior of the material are impaired. In particular, caking of the granulated materials may occur. Conversely, a minimum level of water is needed in order to enable production. The lower the water fraction, the higher the processing temperature when producing the granulated explosive and the firmer the explosive produced. The processing temperature ought not, however, to be above 1300C; for example, for safety reasons, the processing temperature ought not to be above 1250C, such as 120°C.

Corresponding amounts of water are provided, for example by providing the ammonium nitrate in the form for example of a hot solution, with one possible hot ammonium nitrate solution, i.e., ammonium nitrate dissolved in water, being at 91% to 93% (percent by mass) ammonium nitrate. Correspondingly a large proportion of the water needed is introduced by way of this hot ammonium nitrate solution.

In a further aspect, a granulated explosive based on a water in-oil emulsion is provided, wherein the granules have an average particle size in the 0.5 mm to 4 mm range, such as 1 mm to 3 mm, more particularly 1 mm to 2 mm. At smaller particle sizes, the storability and conveyability of a corresponding bulk material are impaired. The stated ranges are suitable especially for transport and for the charging procedure in blasting boreholes, and for forming corresponding charged densities. In contrast to the Landex@ product, whose extruded, cylindrical pellets have a size range of 3 to 10 mm in diameter and 5 to 15 mm in length, the average particle size presently, in the above-stated ranges, of the granulated explosive of the invention is preferred. The particle sizes stated for the explosive of the invention were determined by means of sieve analysis.

In a further aspect, the granulated explosive based on a water in-oil emulsion is one which has no further fillers, more particularly no cenospheres, e.g., hollow glass microspheres or foamed hollow spheres such as Styropor spheres.

In one embodiment the granulated explosive based on a water-in

oil emulsion is one which has no further additives at all; as

well as the further fillers not present, this explosive in

particular contains no further organic auxiliaries and

additives.

The absence of these hollow spheres, such as hollow glass

microspheres or Styropor spheres, is desirable in particular

when the explosives are used for extracting raw materials which

are processed further in the sectors of pharmacy, chemistry,

fertilizers, food stuffs, comestibles or animal feed, or

generally in sectors where contamination of the products with

remnants of explosive is unacceptable. The presence of hollow

microspheres in raw materials, in particular, such as in salts

which are used in the sectors of pharmacy, fertilizers, food

stuffs, comestibles or animal feed, is not permissible.

In one embodiment the granulated explosive is one based on a

water-in-oil emulsion, with

ammonium nitrate with a mass fraction of 70% to 77%;

sodium nitrate with a mass fraction of 8% to 13%;

water with a mass fraction of 6% to 9.5%;

paraffin with a mass fraction of 0% to 7%;

stearic acid with a mass fraction of 0% to 7%;

stearate with a mass fraction of 0% to 7%;

emulsifier based on PIBSA with a mass fraction of 0.1% to 3%;

wherein at least one fraction of paraffin and/or stearic acid

and/or stearate is present with a mass fraction of 3% to 7%,

based on the total mass. In particular the granulated explosive

is one consisting of ammonium nitrate and sodium nitrate, water

and also stearic acid and/or stearate, with the mass fractions

stated above.

In another embodiment the explosive granulated in accordance

with the invention is one based on a water-in-oil emulsion, with

ammonium nitrate with a mass fraction of 83% to 87%;

water with a mass fraction of 7% to 10%;

paraffin with a mass fraction of 0% to 7%;

stearic acid with a mass fraction of 0% to 7%;

stearate with a mass fraction of 0% to 7%;

emulsifier based on PIBSA or based on PIB lactone with a mass

fraction of 0.1% to 3%;

wherein at least one of paraffin and/or stearic acid and/or

stearate is present with a fraction of 3% to 7%.

This granulated explosive additionally comprises an auxiliary

for the crystallization of the ammonium nitrate, this auxiliary

being added typically in an amount of 0.01% to 0.8% mass

fraction, such as not more than 0.5% mass fraction.

In a further aspect, the present application is directed to a

method for producing a granulated explosive based on a water

in-oil emulsion, with this explosive comprising oxygen carriers,

water, fuel carriers and emulsifier. This method of the invention

comprises the following steps:

- providing a water-containing phase with oxygen carrier;

- providing a phase with fuel carrier and emulsifier;

- heating i) water and oxygen carrier and, separately

therefrom, ii) fuel carrier and emulsifier;

- uniting the two compositions mentioned in a reactor with

stirring function to homogenize the emulsion;

- cooling and granulating the water-in-oil emulsion,

optionally with shaping processes;

- and optionally comminuting and classifying the granules.

The granulated explosive of the invention based on a water-in

oil emulsion, then, is produced by means of hot emulsification, with the phase containing fuel carrier and emulsifier (fuel phase) being heated to a suitable temperature, so that there is no degradation of the emulsifier. Generally speaking, the temperature in this case ought not to exceed a value of 90°C, with the heating taking place to not more than 800C, such as no more than 70°C.

Furthermore, the oxidant phase, the water-containing phase with

oxygen carrier, is heated. This heating takes place necessarily

above the crystallization temperature of the mixture of oxygen

carrier and water, such as the mixture of ammonium nitrate and

sodium nitrate, for example. The crystallization temperature

here is dependent on the water fraction and on the mixing ratio

of the salts provided. Heating in particular ought not to take

place above 1300C, such as above 1250C, in order to prevent

evaporation effects and also the formation of harmful gases (e.g.

nitrous gases).

The oxygen carrier present is dissolved here completely in the

water (oxidant phase). Separately from this, the fuel phase is

melted, and in one embodiment the desired temperature of the

fuel phase is achieved directly before the uniting of the fuel

phase with the oxidant phase. After the two compositions have

been united, in the heated state, the emulsion is homogenized in

a reactor with stirring function. In one embodiment,

subsequently, the water-in-oil emulsion is cooled below the

solidification temperature, where in one embodiment there is

simultaneous shaping by means of suitable shaping processes for

granulating the water-in-oil emulsion. The skilled person knows

of suitable shaping processes and granulating processes. Shaping

processes may be those selected from spray drying, extrusion,

prilling, pastillation or pelletizing.

In one preferred embodiment the shaping and granulation process takes place in the form of pastillation.

Depending on the shaping by granulation, there may be subsequent grinding and subsequent classifying, especially sieving. The skilled person knows of processes suitable accordingly.

The homogenization in the stirring vessel may take place, for example, with the aid of a disk stirrer, a coil stirrer or, preferably, with a conical stirrer. An alternative possibility is to use a suitable dispersing system operated in continuous flow, such as a rotor-stator mixer, for example. The skilled person knows of suitable systems for homogenizing the emulsion.

The method of the invention may further envisage the addition of further components to the emulsion during the homogenization in the reactor. Further components which may be present in the granulated explosive of the invention based on a water-in-oil emulsion include the following: fillers, such as perlite or zeolite, additional structuring components in the form of water insoluble polymers, e.g. polyisobutylene, natural rubber or synthetic rubber, or supplementary performance-enhancing constituents, such as aluminum powder, magnesium powder, sulfur, and explosives, such as nitro compounds or nitrate esters, for example.

The present invention additionally relates to a granulated explosive obtainable with the method of the invention for producing a granulated explosive based on a water-in-oil emulsion. This granulated explosive is notable for improved storage and free-flow properties and also for a reduced caking tendency. Following granulation, it is possible additionally to add anticaking agents or free-flow aids to the explosive of the invention in order to improve the flow and storage properties further. Moreover, the explosive of the invention exhibits, compared to ANFO explosive, a shortened initiation distance for detonation and also an increased velocity of detonation, with the consequence of a higher efficiency when blasting, because of the improved utilization of energy.

Lastly provided, in a further aspect, is the use of the

granulated explosive of the invention, based on a water-in-oil

emulsion, for producing explosives having improved properties of

the release of gaseous nitrogen oxides and carbon monoxide during

reaction, especially for use in cavity construction such as

tunneling or cavern construction and also in raw materials

extraction, such as quarrying, strip mining, excavation mining

or in underground mining beneath the surface. The granular

explosive of the invention is especially suitable for use as an

explosive for the extraction of raw materials for the sectors of

pharmacy, chemistry, fertilizers, food stuffs, comestibles and

animal feed, and also, generally, for the extraction of raw

materials for which instances of contamination with remnants of

explosive are unacceptable.

Additionally provided in accordance with the invention is a

packaging unit of the granulated explosive of the invention,

this explosive based on a water-in-oil emulsion being present in

the packaging unit in an amount of more than 25 kg, such as at

least 30 kg, such as at least 50 kg, e.g., at least 100 kg. These

packaging units are especially suitable for the transport and

the storage of the explosive of the invention.

The present invention relates lastly to the use of the explosive

of the invention based on a water-in-oil emulsion for blasting

soft or hard rock, especially for use in the mining of potash salts and rock salts. In this context no booster charge is necessary for initiation, especially in small-caliber blasting boreholes. It has emerged unexpectedly that the initiation by means of detonators is sufficient and, with inclusion, there is a detonative reaction with comparatively high velocity of detonation, without any booster charge being used. The initiation with a detonator of the customary nature and strength is sufficient, where legally permissible.

On the basis of the structural characteristics of the explosive of the invention based on a water-in-oil emulsion, water resistant granules can be produced, since with appropriate shaping the water-soluble salts are completely encased by the continuous phase. Where granules with fracture faces are present, the water resistance may be achieved by a suitable coating. In contrast to other granular ANC explosives, such as ANFO, for example, it is therefore also possible to use the explosive of the invention in wet and water-carrying boreholes.

Examples Below, the explosive of the invention is described further by means of examples, without being limited thereto.

Components used: Ammonium nitrate and sodium nitrate are used as oxygen carriers, and various carbon carriers, solid at room temperature, and also various emulsifiers are used. A corresponding overview is shown below:

Ammonium nitrate: 99.9%, laughing-gas grade, crystalline, Yara GmbH & Co. Kg Sodium nitrate: 99.4%, VWR Chemicals

Paraffin: pastillated, melting range 56 580C, Merck Stearic acid: k90%, melting range 67-70°C, Alfa Aesar Magnesium stearate: melting range 148-152°C, Alfa Aesar Lubrizol@ 2820 PIBSA emulsifier, Lubrizol AnfomulTm 2000 PIBSA emulsifier, Croda Mining AnfomulTm S5 SMIS emulsifier, Croda Mining AnfomulTm 2887 PIB lactone emulsifier, Croda Mining

Production method: The water-in-oil emulsion according to the invention is produced by hot emulsifying. Both phases are heated/melted separately from one another, then united with one another with stirring and thereafter homogenized with vigorous stirring. For the production of the water phase, the oxygen carriers are weighed out together with the corresponding amount of water and are dissolved with heating. Further heating above the crystallization point should be avoided. The pH of this solution is in the range from 4 to 5. In parallel with this, the fuel phase is melted, being composed of the fuels and also the emulsifier. Phase unification takes place in the fuel phase preparation vessel at a peripheral stirrer speed of 1.5 m/s. For this purpose a Visco Jet® conical agitator mechanism is preferably employed. The water phase is poured slowly into the initially-taken fuel phase, until the crude emulsion begins to form. Thereafter the speed of phase unification is increased, with a simultaneous increase in the peripheral stirrer speed to 3 m/s, until the addition of the water phase is concluded. The homogenization of the emulsion then takes place at a peripheral speed of 6 m/s for 1 minute. In the next step, the emulsion is spread out over an area, with a layer height of 3 to 5 mm.

Immediately after the spreading-out, owing to the cooling, the

emulsion matrix begins to solidify, and so a solid body is

formed. From the solidified emulsion matrix, after cooling,

fracture granules are produced, and can be fractionated via

sieves having different mesh sizes.

Measurement of relevant fume constituents: For the measurement of the blasting fumes, the explosives under

test are ignited with enclosure in a steel tube closed off at

one end and having a length of 1 m, a wall thickness of 17.5 mm

and an internal diameter of 35 mm (see Elfferding, Triebel and

Wachsmuth, Kali & Steinsalz 01/2018). The initiation took place

using an electrical instantaneous detonator and a booster charge

with 20 g of nitropenta. In addition, selected tests were carried

out without a booster charge, and are described in example 4.

The gas constituents in the blasting fumes were measured by means

of a chemoluminescence instrument (CLD 822 Mr, ecoPhysics) and

NDIR spectrometer (Sidor, Sick Maihack). For comparability of

different measurements, the results are expressed as specific

fume volumes in liter of gas component per kg of explosive under

standard conditions, taking account of the mass of explosive

tested. The results reported represent mean values from at least

two measurements. The associated error indicators come from the

calculation of the 95% confidence interval.

Employed as a reference were the blasting fumes from ANDEX LD

with the composition, in terms of mass fractions, of 94% ammonium

nitrate prills and 6% mineral oil. The velocity of detonation

(VOD) was measured discontinuously by means of electrooptical

signal processing (Explomet-Fo-2000, Kontinitro SA), allowing

the development of the velocity of detonation to be appreciated

over the length of the steel tube. Where only one value is reported for the velocity of detonation, it is the mean value weighted by the lengths of the individual measurement distances.

Example 1 The composition of the formulation is represented in table 1.

Table 1: Composition of example formulation 1

Ingredient Mass fraction Ammonium nitrate 73.6% Sodium nitrate 11.0% Water 9.2% Paraffin 2.5% Stearic acid 3.1% Lubrizol@ 2820 0.6%

The oxygen balance of the formulation indicated in table 1 is minus 0.4% and the theoretical specific standard gas volume on complete reaction is 932 L/kg. In the present example, the fracture granules were sieved off using sieves with mesh sizes of 2.5 mm, 3.15 mm and 4 mm.

The production of the formulation stated in table 1 produces granules of the explosive of the invention with good properties. The strength, the caking tendency and the flow behavior are highly suitable for the application. For further evaluation, fume measurements were carried out. Depending on the sieve used, particle size distributions of the explosive of the invention with mean sizes of 1.4 mm, 1.8 mm and 2.1 mm were obtained. Table 2 represents a compilation of the corresponding granular characteristics, and table 3 gives an overview of the specific fume volumes of relevant gas components and also an overview of the velocities of detonation.

Table 2: Characteristics of the granular explosives from example 1 Explosive Mean Bulk Jolted particle density density size mm kg/L Kg/L ANDEX LD 1.5 0.70 0.77 Granules 1.4 0.75 0.83 2.5 mm sieve Granules 1.8 0.78 0.88 3.15 mm sieve Granules 2.1 0.77 0.85 4 mm sieve

Table 3: Specific fume volumes of relevant gas components and velocities of detonation of the explosives investigated in example 1 Explosive NOx in NO in N02 in CO in C02 in VOD in L/kg L/kg L/kg L/kg L/kg m/s ANDEX LD 2.27± 2.13± 0.14± 19.74± 75.8± 3798 0.14 0.15 0.02 0.92 4.5 Granules 0.79± 0.66± 0.12± 10.98± 82.1± 4202 2.5 mm 0.14 0.12 0.08 0.12 4.3 sieve Granules 0.84± 0.59± 0.24± 11.22± 71.9± 3960 3.15 mm 0.17 0.11 0.06 3.05 20.4 sieve Granules 1.11± 0.85± 0.25± 11.14± 70.0± 3918 4 mm 0.19 0.15 0.06 1.93 9.2 sieve

The results in table 3 show that the granular emulsion explosive

of the invention has a significant potential for reducing toxic

blasting fumes in comparison to ANDEX LD. Depending on the sieve

fraction used, on average specific NOx fume volumes in the range

from 0.8 to 1.1 L/kg were measured. It is found that lower

specific NOx fume volumes are achieved with reducing particle

size. The improved detonative reaction of smaller particle sizes

is attributable to the greater sensitization as a result of the

larger number of pores between the granules. A reduction in the

specific CO fume volumes relative to ANDEX LD is also achieved.

On average the results show that, irrespective of the particle

size, a reduction in the specific CO fume volumes of 40 to 50%

is possible using the booster charge. An indicator of the

improvement in the detonative reaction with decreasing particle

size is represented by the velocities of detonation. With a

decrease in the mean particle size of the emulsion granules, the

velocity of detonation increases.

Example 2 Below, the various emulsifiers were investigated. For this

purpose, the formulations represented in table 4 were produced.

The oversize of the fracture granules was removed by sieving

with a sieve of mesh size 3.15 mm.

Table 4: Example formulations for evaluation of different

emulsifiers

Ingredient Mass fractions Ammonium nitrate 73.3% 73.3% 73.3% 73.3%

Sodium nitrate 11.0% 11.0% 11.0% 11.0%

Water 9.1% 9.1% 9.1% 9.1%

Paraffin 2.5% 2.5% 2.5% 2.5%

Stearic acid 3.1% 3.1% 3.1% 3.1%

Lubrizol@ 2820 1.0% - -

Anfomul' 2000 - 1.0% -

Anfomul' S5 - - 1.0%

Anfomul' 2887 - - - 1.0%

Table 5: Specific fume volumes of relevant gas components of the

explosives investigated in example 2

Emulsifier NOx in NO in N02 in CO in C02 in

L/kg L/kg L/kg L/kg L/k/g

Lubrizol@ 0.63± 0.48± 0.15± 14.68± 84±8

2820 0.13 0.12 0.03 0.66 Croda 0.87± 0.77± 0.11± 13.29± 83±8

AnfomulTm 1.59 1.52 0.01 6.43

S5 Croda 0.46± 0.33± 0.13± 13.87± 81±9 Anfomul m 0.09 0.25 0.06 4.64

2887

Croda 0.44± 0.30± 0.14± 13.06± 78±90 AnfomulTm 0.83 0.71 0.14 11.09

2000

Table 5 shows that the resulting specific NOx fume volumes are

influenced by the type of emulsifier. On average the highest

specific NOx fume volume of 0.87 L/kg was measured for the Anfomul granules produced using S5. With the PIBSA-based

emulsifiers from Lubrizol (2820) and Croda (Anfomul T 2000), mean

specific fume volumes in the region of 0.63 L/kg and 0.44 L/kg

of NOx, respectively, were measured. The granules with the

AnfomulTm 2887 emulsifier give a specific NOx fume volume of

0.46 L/kg. In terms of the resultant CO fumes, no significant

differences were observed. The influences of the different

emulsifiers are attributable to the microstructures of the emulsion granules. The finer the distribution of the disperse phase within the granules, the lower the resultant toxic blasting fumes.

Example 3 In this example, the composition of the fuel phase is altered by

carbon carriers having different melting temperatures. An

increasing melting temperature is generally accompanied by an

increase in the strength of the substances. Through the targeted

selection of corresponding components, therefore, it is possible

to exert a direct influence over granule strength and caking

tendency. An overview of the formulations is represented in table

6. The oversize of the fracture granules was removed using a

sieve with a mesh size of 3.15 mm.

Table 6: Example formulations with altered mass-fractional

compositions of the fuel phase

Ingredient Paraffin + Stearic Stearic acid stearic acid acid + magnesium stearate Ammonium nitrate 75.5% 75.1% 75.1%

Sodium nitrate 11.3% 11.3% 11.3%

Water 6.6% 6.5% 6.5%

Paraffin 2.5% -

Stearic acid 3.2% 6.1% 5.1%

Magnesium - - 1.0%

stearate

Anfomul Tm 2000 1.0% 1.0% 1.0%

Table 7: Specific fume volumes of relevant gas components of the

explosives investigated in example 3

Fuel NO, in NO in N02 in CO in C02 in

L/kg L/kg L/kg L/kg L/kg

Paraffin+ 0.63± 0.44± 0.19± 16.56± 82±32

stearic 0.47 0.32 0.21 11.74

acid

Stearic 0.55± 0.30± 0.25± 16.16± 83±54 acid 0.18 0.29 0.02 14.68 Stearic 0.80± 0.53± 0.28± 22.26± 86±14

acid+ 0.51 0.48 0.02 3.28 magnesium

stearate

Table 7 represents the mean specific NOx fume volumes of the

granules with different fuels in comparison to ANDEX LD. The

alteration of the composition of the fuel phase with constant

oxygen balance shows that this also affects the resultant

blasting fumes. On average the lowest specific fume volume of

0.55 L/kg of NOx was measured for the formulation produced

exclusively with stearic acid. Relative to the formulation

composed of the combination with paraffin there is no significant

difference apparent. If additionally, on a comparative basis,

the strength and flowability of the bulk material are evaluated,

they are preferably improved through the use of stearic acid.

The incorporation of 1% of magnesium stearate does not result in

any significant improvement in these properties, and the

resultant NOx fume volume is also somewhat higher on average.

Example 4 With the composition based on the exclusive use of stearic acid

as essential carbon carrier and on a water fraction of 6.5% (cf.

table 6), further tests were carried out. The oxygen balance of

this formulation is minus 1.7% and the theoretical specific

standard gas volume on complete reaction is 928 L/kg. Following production, the fracture granules were relieved of their coarse fraction > 2 mm and of their fine fraction < 1 mm by sieving.

Relevant fume constituents were measured in accordance with the

preceding description, except that is this example no booster

charges were used - instead, exclusively electrical detonators

were used for initiating the charge columns.

Table 8: Specific fume volumes of relevant gas components,

measured without booster charge

Explosive NOx in NO in N02 in CO in C02 in

L/kg L/kg L/kg L/kg L/kg

ANDEX LD 2.31± 2.20± 0.10± 13.83± 77±15

0.13 0.13 0.04 1.50 Emulsion 0.26± 0.20± 0.05± 7.16± 79±21

granules 0.04 0.05 0.01 1.57

with 1

2 mm

particle

size

Table 8 represents the specific fume volumes of relevant gas

components for ANDEX LD and for the emulsion granules with

particle sizes in the 1-2 mm range, measured without a booster

charge. With a mean specific fume volume of 0.26 LNOx/kg, it was

possible to demonstrate a significant reduction in nitrogen

oxides of 89% relative to ANDEX LD. Also, on average, a reduction

in the CO fumes by 48% was achieved. The narrow particle size

distribution of the emulsion granules, in the range from 1 to

2 mm, is therefore particularly advantageous for the quality of

the reaction. This is critically attributable to the

sensitization provided by the granular porosity. The flow

behavior of the bulk product as well is improved considerably by

the removal of the fine fraction < 1 mm. The quality of the detonative reaction may be seen, furthermore, from the development in the velocity of detonation over the length of the charge column.

Figure 1 represents the evolution of the mean velocities of

detonation of ANDEX LD and of the emulsion granules of the

invention with particle fraction 1 to 2 mm as a function of the

steel tube length. In the so-called initiation section, ANDEX LD

is marked by the characteristic evolution of the detonation

profile after initiation by the detonator. In the first third of

the steel tube length, the velocity of detonation increases

successively until an equilibrium state of the detonation is

reached. In the case of the granular emulsion, this evolution is

much less pronounced, since the reaction takes place with a

substantially higher quality, meaning that virtually no

significant initiation section is observed. As a result, in

comparison to other granular explosives, such as ANDEX LD, for

example, it is presumably possible to achieve a higher knockoff

efficiency when carrying out blasting works. There is also

confirmation that initiation does not necessarily require a

booster charge.

Reference example Production of a composition according to example 5 of CN

101555183 B:

Composition of formulation

86.0% ammonium nitrate

3.0% sodium nitrate

4.0% water

2.8% Span 80

1.4% paraffin

1.4% paraffin wax

1.3% rosin

0.1% stearic acid

The manufacturers thereof are those stated above and also

Span 80, Sigma-Aldrich, Paraffin, VWR Chemicals,

and

Rosin, Acros Organics

After the emulsifying operation as described herein, the matrix

was coated onto a steel plate and solidified by cooling. The

solidified product was subsequently processed by comminution and

sieving into granules having a particle size distribution in the

range of 1 - 2 mm.

This reference example was investigated in comparison to the

inventive example 4 in terms of NOx blasting fumes and velocity

of detonation, as described above, by means of steel tube

blastings:

Table 9:

NOx NO NO 2

L/kg L/kg L/kg

Example 4, 0.26 ± 0.04 0.20 ± 0.05 0.05 ± 0.01

inventive

Reference 5.74 ± 0.67 5.41 ± 0.70 0.35 ± 0.03

example CN

101555183 B

The composition produced according to example 5 of CN 101555183

B as reference example gives off a significantly higher degree

of nitrogen oxide compounds, under identical test conditions, than the inventive emulsion granules according to example 4. The granules described in the present invention achieve a mean specific fume volume of 0.26 LNOx/kg; the explosive granules according to the prior art, CN 101555183 B, are situated at

5.74 LNOx/kg.

From figure 2 it is additionally clear that the velocities of

detonation are very different. In the equilibrium state of the

detonation, the emulsion granules of the invention, at 4000 m/s,

attain a significantly higher velocity of detonation than the

explosive granules according to the reference example, at

2600 m/s.

Claims (25)

1. A granulated explosive based on a water-in-oil emulsion,

comprising:

oxygen carrier with a mass fraction of 78 to 90%;

water with a mass fraction of 5 to 10%;

fuel carrier with a mass fraction of 3 to 7%; and

emulsifier with a mass fraction of 0.1 to 3%.

2. The granulated explosive based on a water-in-oil emulsion

as claimed in claim 1, wherein the oxygen carrier is

selected from alkali metal and alkaline earth metal

nitrates, ammonium nitrate, alkali metal and alkaline earth

metal chlorate, ammonium chlorate, alkali metal and

alkaline earth metal perchlorates and ammonium perchlorate,

in particular a mixture of ammonium nitrate and sodium

nitrate.

3. The granulated explosive based on a water-in-oil emulsion

as claimed in claim 2, wherein the oxygen carrier is

ammonium nitrate.

4. The granulated explosive based on a water-in-oil emulsion

as claimed in any of the preceding claims, wherein the fuel

carrier is selected from plant waxes, plant oils, animal

oils and fats, paraffin wax, light crude oil, kerosine,

mineral oil, lubricating oil, heavy oil, carboxylic acid,

carboxylic ester and microcrystalline wax or combinations

of at least two thereof.

5. The granulated explosive based on a water-in-oil emulsion

as claimed in claim 4, wherein the fuel carrier is at least

one selected from paraffin, animal or plant oils and their salts, especially paraffin or stearic acid, or a combination of these fuel carriers, especially paraffin and stearic acid, or stearic acid and stearate, or paraffin and stearic acid and stearate, or paraffin and stearate.

6. The granulated explosive based on a water-in-oil emulsion

as claimed in any of the preceding claims, wherein the

emulsifier is one based on polyisobutylene-succinic

anhydride (PIBSA), based on sorbitan monoisostearate (SMIS)

or an emulsifier based on polyisobutene lactone (PIB

lactone), or mixtures thereof; more particularly the

emulsifier is one based on PIBSA.

7. The granulated explosive based on a water-in-oil emulsion

as claimed in any of the preceding claims, wherein the

emulsifier is not present as a mixture of two or more

individual emulsifiers but is instead selected from

polyisobutylene-succinic anhydride (PIBSA) or an emulsifier

based on polyisobutene lactone (PIB lactone).

8. The granulated explosive based on a water-in-oil emulsion

as claimed in any of the preceding claims, wherein the water

fraction in the granulated explosive as a mass fraction is

in a range from 6% to 10%, such as 6.5% to 9.5%, more

particularly 6.5% to 9%.

9. The granulated explosive based on a water-in-oil emulsion

as claimed in any of the preceding claims, wherein the

granules have an average particle size in the range of

0.5 mm to 4 mm, such as 1 mm to 3 mm, more particularly

1 mm to 2 mm.

10. The granulated explosive based on a water-in-oil emulsion as claimed in any of the preceding claims, which comprises no further fillers, more particularly no hollow spheres, e.g., hollow glass microspheres or organic hollow spheres such as Styropor spheres.

11. The granulated explosive based on a water-in-oil emulsion as claimed in any of the preceding claims, with: ammonium nitrate with a mass fraction of 70% to 77%; sodium nitrate with a mass fraction of 8% to 13%; water with a mass fraction of 6% to 9.5%; paraffin with a mass fraction of 0% to 7%; stearic acid with a mass fraction of 0% to 7%; stearate with a mass fraction of 0% to 7%; emulsifier based on PIBSA with a mass fraction of 0.1% to 3%; wherein at least one of paraffin and/or stearic acid and/or stearate is present with a fraction of 3% to 7%.

12. The granulated explosive of a water-in-oil emulsion as claimed in any of claims 1 to 10, with ammonium nitrate with a mass fraction of 83% to 87%; water with a mass fraction of 7% to 10%; paraffin with a mass fraction of 0% to 7%; stearic acid with a mass fraction of 0% to 7%; stearate with a mass fraction of 0% to 7%; emulsifier based on PIBSA or based on PIB lactone with a mass fraction of 0.1% to 3%; wherein at least one of paraffin and/or stearic acid and/or stearate is present with a fraction of 3% to 7%.

13. A method for producing a granulated explosive based on a water-in-oil emulsion containing oxygen carrier, water, fuel carrier and an emulsifier, comprising the following steps: - providing a water-containing phase with oxygen carrier; - providing a phase with fuel carrier and emulsifier; - heating i) water and oxygen carrier and, separately therefrom, ii) fuel carrier and emulsifier; - uniting the two compositions mentioned in a reactor with stirring function to homogenize the emulsion; - cooling and granulating the water-in-oil emulsion, optionally with shaping processes; - and optionally comminuting and classifying the granules.

14. The method for producing a granulated explosive based on a water-in-oil emulsion as claimed in claim 13, wherein the shaping process is one selected from spray drying, extruding, prilling, pastillation or pelletizing, especially pastillation.

15. The method for producing a granulated explosive based on a water-in-oil emulsion as claimed in claim 13 or 14, wherein the shaping takes place by granulating or grinding and subsequently classifying, especially sieving.

16. The method for producing a granulated explosive based on a water-in-oil emulsion as claimed in any of claims 13 to 15, wherein the composition containing water and oxygen carrier is heated to a temperature of not more than 1300C, in particular up to the crystallization temperature of the oxygen carriers.

17. The method for producing a granulated explosive based on a water-in-oil emulsion as claimed in any of claims 13 to 16, wherein any further components are added to the emulsion during the homogenization in the reactor.

18. The method for producing a granulated explosive based on a

water-in-oil emulsion as claimed in any of claims 13 to 17,

for producing a granulated explosive as claimed in any of

claims 1 to 12.

19. A granulated explosive obtainable by a method for producing

a granulated explosive based on a water-in-oil emulsion as

claimed in any of claims 13 to 18.

20. The use of a granulated explosive based on a water-in-oil

emulsion as claimed in any of claims 1 to 12 for producing

explosives having improved properties of NOx release on

reaction, especially for use in cavity construction such as

tunneling and cavern construction and also in raw materials

extraction, such as in quarrying, strip mining, excavation

mining and in underground mining, such as in potash salt

and rock salt mining.

21. A packaging unit of granulated explosive based on a water

in-oil emulsion as claimed in any of claims 1 to 12 or 19,

comprising granulated explosive in an amount of more than

25 kg, such as at least 30 kg, such as at least 50 kg, such

as at least 100 kg, more particularly suitable for the

transport and the storage of the granulated explosive.

22. The use of the granulated explosive based on a water-in

oil emulsion as claimed in any of claims 1 to 12 or claim

19 for blasting soft rock or hard rock, especially for use

in the mining of potash salts and rock salts, where in small-caliber blast boreholes no booster charges are required.