PT1458660E - A method for preparing a sensitised emulsion explosive - Google Patents

Abstract

This invention relates to a method for rapid chemical gassing of an emulsion explosive without having toxic nitrogen oxides in the finished emulsion explosive product, when nitrite is used as the gassing component. Urea acts as a gassing accelerator and urea are added in the water lubrication solution or in both the water lubrication solution and in the gassing component. To achieve rapid gassing of an emulsion explosive, the emulsion is prepared at a pH in the range of 0-3, by using an organic acid having at least 3 carbon atoms.

Description

ΡΕ1458660 ι

A METHOD FOR PREPARING A SENSITIVE EMULSION EXPLOSIVE " The present invention relates to a method for preparing a water-in-oil emulsion explosive. (Hereinafter referred to as " emulsion explosive "). More particularly, the invention relates to a method for reducing the formation of toxic nitrogen oxides (NOx) in the finished emulsion explosive product which is rapidly sensitized or gassed with nitrite at low pH values.

BACKGROUND OF THE INVENTION

Emulsion explosives are well known in the art. They are fluid when formed (and can be designed to remain fluid at temperatures of use) and are used both in packaged form and in bulk. They may be used as emulsions for direct use or may be mixed with " prills " (porous grains) of ammonium nitrate and / or ANFO to form a heavy ANFO product having a higher energy and, depending on the proportions of the components, better water resistance than that of ANFO. The density of such emulsions can be reduced by the addition of voids in the form of hollow microspheres, other solid entrainers or gas bubbles, which 2 ΡΕ1458660 material sensitize the emulsion for detonation. A stable, uniform dispersion of an agent entraining air or gas bubbles is important for the detonation properties of the emulsion. The gas bubbles, if present, are normally produced by the reaction of chemical gasification agents.

When holes are charged with a chemically aerated or sensitized emulsion explosive, it is important to have the correct portion of the bore unloaded to prevent rocketing and possible personal and material damage. If the gasification process is slow, it is difficult to know when to stop the charging process and to what extent the emulsion will expand up into the bore to achieve the correct portion of the bore.

On the other hand, if the gasification process is fast, and in the same order or less than the time it takes to load the hole, it is easy to find the correct loading height and the hole attack can be stopped immediately. Also in the opening of blast tunnels it is important to have a gasification and expansion process that is as fast as possible, especially when vertical holes are loaded.

A common sensitizing agent is nitrite, which generates bubbles of nitrogen in the emulsion when the nitrite reacts with ammonium, preferably in the presence of an accelerator. 3 ΡΕ1458660 The reaction between these components can be illustrated as follows:

NH 4 + NO 2 -> N 2 + 2 H 2 O

However, when an emulsion explosive forms gas rapidly, if nitrite is used as a gasification component and at a reduced pH, there will often be formation of some toxic nitrogen oxide in addition to the nitrogen gas as the main gaseous product.

Carbonated emulsion explosives may, under certain conditions, fall or drip from a bore and therefore lose some of the sensitizing gas. When loading into service galleries, part of the sensitized emulsion can kill and lose gas, especially when the attack is applied in a bore with a low density emulsion explosive. In poor ventilation, people may be exposed to hazardous levels of NO2 when working near a sensitized emulsion explosive that is losing its sensitization gas, whether on the ground or in the laboratory. Ο NO2 is a very toxic gas and, in Europe, its maximum limit is reduced to 2 ppm. The present invention provides a novel method for rapidly sensitizing an emulsion explosive in which the toxic NOx gas will be reduced or eliminated during the gasification process. 4 ΡΕ1458660

Prior art technology:

A process and device for the manufacture of components for emulsion explosives is disclosed in U.S. Patent No. 6,165,297. This patent also relates to different accelerators, for example, in claim 12, wherein thiourea, thiocyanate, iodide, cyanate , acetate and combinations thereof.

According to the present invention there is provided a method for preparing a sensitized emulsion explosive in a bore or package, wherein a) a fuel phase and an oxidation solution containing ammonium species and oxidation salt are emulsified to form a emulsion, said emulsion being subjected to gasification by mixing with b) a gasification solution containing inorganic nitrite in the presence of urea as a gasification accelerator where the emulsion explosive is poured into a bore or package by means of a loading tube or hose, allowing gasification to occur at the end of said tube or hose, characterized in that the pH of the oxidation solution is in the range of 0-3, contains one or more organic acid (s) having at least three carbon atoms and that urea is present in the gasification solution and / or is present in a lubricating fluid added to the charge tube or hose. The pH should be adjusted to a value in the range of 0-3 by means of an organic acid having at least 3 carbon atoms, such as citric acid and / or tartaric acid. A preferred pH is in the range of 0.4-2.0, in particular of about 1.

This means that the emulsion oxidation solution should normally contain the organic acid such as citric acid in a concentration of 0.2 to 5%, preferably from 1.5 to 3%.

When using urea as a gasification accelerator there is virtually no generation of nitrous gases (NOx), or any other toxic gases that can be produced using other gasification accelerators. Urea has been used or suggested for use in aqueous emulsion or gel type aquifer explosion agents and in ANFO blowing agents. For example, U.S. Pat. U.S. Patent No. 5,159,153 discloses the use of urea in the oxidation salt solution phase of an emulsion blowing agent for the purpose of stabilizing the blowing agent against thermal degradation in the presence of reactive sulfide and pyrite ores. Pat. U.S. Patent No. 4 338 146 discloses the use of urea as an additive in an emulsion explosive having a 6 ΡΕ1458660 responsive cap in an amount of less than 5% by weight. Pat. U.S. Patent No. 4,500,369 discloses the use of urea in an emulsion blowing agent to lower the crystallization temperature. Pat. U.S. No. 3,708,356 discloses the use of urea to stabilize ANFO against reaction with pyrite ores. Pat. US 5,608,185 discloses a method of reducing the formation of toxic nitrogen oxides (NO.sub.x) in post-explosion fumes using an emulsion blowing agent having an appreciable amount of urea in its discontinuous solution phase oxidizing saline. Thus, the urea in said patent is used to reduce the amount of nitrogen oxides formed in the post-explosion fumes, while, according to the present invention, the urea is used in conjunction with the gasification agent related to the sensitization of the explosive emulsion to prevent NOx formation in the sensitized emulsion prior to being detonated. USP 5 972 137 relates to the gasification of an emulsion explosive but the aim is not to reduce the amount of NOx in the sensitized emulsion but to use an organic solvent for the gassing agent in order to minimize the total amount of water in the composition of explosive and, consequently, increase the energy of the explosive. A relatively high pH is used and the gassing agent is a combined hose lubricant and gassing agent. The gasification accelerator is 7 ΡΕ1458660 added to the fuel phase and will be drawn up the oxidizing solution as the emulsion is formed. With this patent rapid gasification using a low pH oxidant is not possible because the urea (gasification accelerator) will decompose under these conditions.

USP 3 711 678 also describes a gasification technique but, in this case, gasification takes place at a very early stage, in particular at the stage where the initial emulsion is formed. The process of this patent can not be used for rapid gasification because the emulsion has to be formed at an elevated temperature of about 60 ° C and under these conditions trying to use a reduced pH will cause the emulsion to be gassed in seconds, such as is shown in the present invention; see example 14 below. The rapid gasification of an emulsion can only be carried out using a mixing device at the end of a hose otherwise the emulsion will lose its sensitizing gas at the emulsion pump and the loading hose. The sensitized emulsion explosive prepared in accordance with the present invention is poured into a bore or carton (cartridge) by means of a tubular loading hose which may suitably be lubricated by lubricating water to reduce the friction of the emulsion explosive through of the pipe or hose. Suitably, urea may be added to said lubricating water. It is also possible to add other substances to the lubricating water and examples of such substances ΡΕ1458660 substances are organic acids to reduce the pH value to the required level and also reducing energy and combustion agents.

In the gasification solution the urea concentration should preferably be 10 to 45%, in particular from 20 to 30% by weight. In the lubricating water the concentration of urea should preferably be 5 to 50%, preferably 20 to 40% by weight.

In the prior art, as in the aforementioned USP 6 165 297, the urea is added in small amounts in the gas forming composition. In said USP 6 165 297 it is necessary to mix two different gasification ingredients immediately prior to the gasification process because, otherwise, the gasification ingredients themselves in said patent will turn into gas. USP 6,165,297 (see col. 12, line 8-31) describes the gasification process in Example 3 as follows: An aqueous solution of sodium nitrite (SNI) and urea was stored in a vessel of the device of the present invention while an aqueous solution of ammonium nitrate (AN) and urea were stored in a separate vessel. The SNI solution and the AN / urea solution were pumped out of their containers through separate conduits into a small tank and mixed together using a rapidly rotating propeller. The premix thus formed was then injected into the water-in-oil emulsion immediately before the water-in-oil emulsion passed through a series of static mixing elements, which regularly distributed the components suitable for gas formation throughout the water-in-oil emulsion. The water-in-oil emulsion incorporating the components passed through the remaining length of stainless steel conduit into a flexible loading hose whose opposing end was inserted into a bore. The bore was filled with combinations of water-in-oil emulsions and blended components. The mixed components began to react after about 30 seconds and the gasification reaction took about 30 minutes to complete. The density of the water-in-oil emulsion gasified was 1.00 g / cc compared to 1.38 g / cc for the non-carbonated water-in-oil emulsion. The hole was detonated successfully. USP 6,165,297 describes a gasification process which is very different from that of the present invention. Although USP 6,165,297 and the present invention both comprise the use of urea, these two patents are very different. • USP 6 165 297 gasses slowly (typically 30 min to achieve a density of 1.05 g / cc) and makes no reference to NOx that can be formed in the gasification process itself. The object of the present invention is a rapid gasification and, at the same time, eliminating or minimizing the NOx formed in the gasification process. This is 10 10458660 achieved by using an organic acid in the oxidation solution, wherein citric acid and / or tartaric acid are the preferred organic acids. • USP 6 165 297 mixes two gasification ingredients immediately prior to injection into the emulsion. This premix is self-gassing and the water-in-oil emulsion itself has a relatively high pH of 4.2 (see col. 10, line 45), and the ammonium species in the oxidizing solution does not (or only very slowly) reacts directly with the nitrite in the gasification solution. In the present method, a solution of urea is used as a charge hose lubricant and is mixed with the emulsion in a spray nozzle at the end of the loading hose. The pH of the water-in-oil emulsion is very low (less than 3). The gasification component may alternatively be added as a yarn in the center of the emulsion (see PCT / N098 / 00275) or be mixed with a static mixture or in a mechanical mixer just before the emulsion enters the loading hose. USP 5,608,185 uses urea as a component in the discontinuous oxidant salt phase to reduce the formation of nitrogen oxide in the post-explosion fumes. This patent is also very different from the present invention for the following reasons: US Pat. No. 5,608,185 uses urea to reduce post-explosion fumes. The present invention uses urea to eliminate pre-detonation nitrogen oxides which may be generated during rapid gasification. USP 5,608,185 uses 5 to 30% urea. Preferably, the urea is dissolved in an oxidizing salt solution. The present invention uses urea as an additive to the aqueous lubrication solution that is required to be used to pump the emulsion through a long, thin loading hose. At the end of the loading hose (or conduit) the emulsion and the lubrication solution are mixed in a mixing nozzle. In accordance with the present invention the aim is to sensitize the emulsion rapidly and therefore to rapidly gasify it. In order to rapidly gasify the emulsion should have a reduced pH in the oxidation solution and in this case it is impossible to have urea as a component in the oxidizing solution because the urea will slowly decompose in the acidic solution. Under these conditions, the urea will decompose into carbon dioxide and ammonia, which increases the pH and slows down the rate of gasification. USP 5,159,153 also discloses the use of urea in 12 ΡΕ1458660 water-in-oil emulsion explosives but the said patent is also very different from the present invention for the following reasons: • In U.S. 5 159 153 urea is added with the aim of stabilizing the emulsion against thermal degradation with reactive sulfide / pyrite ores. Thus the aim of this patent is completely different from that of USP 5 08 185 and the current patent application in which the aim is to reduce the post-explosion fumes and to eliminate the NOx during the process of gasification (or sensitization) of the emulsion, respectively. In U.S. 5,159,153 the urea is added at 5-20%, preferably dissolved in the oxidizing phase, but may also be added as a powder or solid phase. • In the present method, urea is dissolved in the water lubrication solution and is mixed with the emulsion at the end of the conduit, where the urea acts as a gasification accelerator and minimizes or reduces the NOx normally formed during a rapid gasification process or , alternatively the urea is used in the gasification solution or both in the gasification solution and in the water lubrication solution. Several patents describe the use of gasification accelerators to accelerate the rate of gas generation by the chemical gasification agent. USP 4,960,475, 13 ΡΕ1458660 USP 5 017 251, USP 5 076 867, USP 5 346 564 and USP 6 165 297 all mention the use of gasification accelerators but none of them mention urea as a gasification accelerator. USP 6,165,297 mentions gasification accelerators such as salts of thiocyanate, iodides, sulfuric acid and its salts or thiourea. (See column 3, line 11-12). In these patents, it is more common to add the gasification accelerator to the oxidation solution of the water-in-oil emulsion or to add the gasification accelerator in the gasification solution.

In the present method, the urea is used as a gasification accelerator and is added to the aqueous lubrication solution or to the gasification solution. Alternatively, the urea may be added to both the aqueous lubrication solution and the chemical gasification solution.

USP 4,273,147 and USP 4,259,977 disclose a method of reducing pumping pressure in conduits using a lubricating fluid which moves in an annular chain around the emulsion. The lubricating fluid comprises an ammonium nitrate solution or an aqueous saline solution wherein the salt of said lubricating fluid corresponds to the main salt present in the explosive emulsion. The main purpose of these two patents is to reduce the pumping pressure of an emulsion in a conduit and to prevent the conduit from clogging during the pumping interruption. 14 ΡΕ1458660

In the present invention the lubricating fluid does not contain a salt present in an explosive emulsion and the main presence of urea in the lubricating fluid is not intended to lower the pumping pressure but rather to eliminate or reduce the amount of NOx created during the gasification process with nitrite.

Conclusion: The aim of this patent is to be able to chemically rapidly gasify an emulsion explosive at both reduced and elevated temperatures without creating NOx during the gasification process. To achieve this it is necessary to have an emulsion with a reduced pH and use a gasification accelerator. Surprisingly, it has been found that by reducing the pH using an organic acid such as citric acid, practically NOx production is eliminated during the gasification process when urea is used as a gasification accelerator.

The invention comprises the addition of urea as a gasification accelerator in the gasification solution and / or using urea as a gasification accelerator in the lubricating fluid. It has also surprisingly been found that by reducing the pH of the oxidizing solution in the emulsion using citric acid (AC), NOx is completely eliminated during the gasification process. As can be seen in the examples presented, an increased amount of AC 15 ΡΕ1458660 produces a lower pH but also a reduced NOx as the amount of AC is increased. It has been found that AC is particularly advantageous and, at a level of 2% AC, where the NOx of the gasification process is completely eliminated. The rate of gasification is also increased as the amount of AC is increased. It has also been found that tartaric acid (TA) has a positive effect on NOx reduction in the gaseous emulsion.

On the other hand, if AC is replaced with acetic acid (HAc), this also produces a higher rate of gasification but also produces more NOx. As the amount of HAc is increased, more NOx is produced; therefore, HAc does not have the same advantageous effect as AC and AT.

It was also surprisingly discovered that the rate of gasification in these low pH emulsions was also increased by the replacement of some ammonium nitrate (NA) in a pure NA emulsion (see example 16) with other inorganic nitrates such as sodium nitrate (see examples 6-8 and 10-15) and calcium nitrate. (See Example 17). The NOx produced during the gasification process was still maintained at a very low level.

To illustrate that urea acts as a gasification accelerator as claimed in this invention, the gasification rates were tested using different gasification accelerators 16 ΡΕ1458660 in the gasification composition. The NOx level in the finished sensitized emulsion explosives was also measured.

All the different gasification compositions had the same level of 15% sodium nitrite and were tested at a level of 1% in the indicated standard emulsion. example 1 (not according to the invention)

A standard water-in-oil emulsion of the following composition was prepared for use in the following examples:

Oxidation solution: 94% by weight comprising:

Ammonium nitrate 72.5% by weight Sodium nitrate 1.00% Water 15.77% Citric acid 2.0% by weight The pH value of the oxidant was 0, 98

Fuel phase: 6% by weight comprising:

A hydrocarbon oil and emulsifying mixture. The emulsifier was of a polymeric type. 17 ΡΕ1458660 The emulsion was prepared by the slow addition of a stream of oxidizing solution to the fuel phase with rapid agitation to form a water-in-oil homogeneous emulsion. Both phases maintained a high temperature of 80 ° C during the preparation of the emulsion. The resulting standard emulsion was allowed to cool for one day to room temperature.

The following aqueous solution components were combined to produce the following gas forming composition:

Sodium nitrite 15% Water 85% 1.0% of this gas-forming composition was added to the water-in-oil emulsion. The mixture was blended for 40 seconds and transferred to a plastic cup of 160 cc. The beaker was filled to the top with the emulsion and the emulsion was leveled using a rigid, flat blade. As the emulsion in the beaker gassed, the emulsion expanded to the top of the beaker and was scraped to level. The level cup was weighed minute by minute and the weight of the emulsion explosive was recorded. The density of the gasified emulsion explosive was found by dividing its weight by the cup volume of 160 cc. When the emulsion explosive reached its final density, the cup with the sensitized emulsion explosive was transferred to a box of built-in gloves. The glove box 18 ΡΕ1458660 contained a volume of 100 liters and was equipped with a small 12-volt blower to mix the air in the box and with a Multi-gas monitor (pm-7400) from Metrosonics Inc. The box had a cover in acrylic powder and the assembled gloves allowed a spatula to be used to withdraw the sensitized gas from the emulsion explosive. The fan efficiently mixed the sensitizing gas as a total of 100 liters of air in the box and the Multi-gas Monitor media the NOx concentration. For this particular blend no accelerator was used in the gas forming composition and it was found that gasification rate was greater than 3 hours and a concentration of 10 ppm of NOx in the glove box was measured. EXAMPLE 2 (not according to the invention)

For this experiment the following gasification component was made:

Sodium nitrite 15%

Sodium thiocyanate 30% Water 55% 1% of this gasification component was added to the standard emulsion and mixed for 40 seconds. The gasification rate was recorded and it was found that this emulsion composition reached a density of 0.80 g / cc in 6 minutes and the final density of the cup ended at 0.68 g / cc. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor showed a NOx concentration of 130 ppm. EXAMPLE 3 (not according to the invention)

For this experiment the following gasification component was made:

Sodium nitrite 15%

Thiourea 5% Water 80% 1% of this gasification component was added to the standard emulsion and mixed for 40 seconds. The gasification rate was recorded and this emulsion composition was found to have reached a density of 0.80 g / cc after 55 minutes and ended with a final cup density of 0.75 g / cc after 2 hours. When the gas was removed from the emulsion in the glove box, the Metrosonics Multi-gas Monitor showed a NOx level of 300 ppm. EXAMPLE 4 (not according to the invention)

For this experiment the following gasification component was made: 15%

Sodium nitrite 30% potassium iodide 20 ΡΕ1458660 1% of this gasification component was added to the standard emulsion and mixed for 40 seconds. The gasification rate was recorded and it was found that this emulsion composition reached a density of 0.80 g / cc after 70 minutes and ended with a final cup density of 0.75 g / cc after 2.5 hours. When the gas was removed from the emulsion in the glove box, the Metrosonics Multi-gas Monitor showed a NOx level of 22 ppm. EXAMPLE 5 (not according to the invention)

For this experiment the following gasification component was made:

Sodium Nitrite 15% Ammonium sulfate 30% Water 55 q. " 0.1% of this gasification component was added to the standard emulsion and mixed for 40 seconds. The gasification rate was recorded and this emulsion composition was found to have reached a density of 0.80 g / cc after 160 minutes. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor showed a NOx concentration of 33 ppm. EXAMPLE 6 (according to the invention)

The same emulsion and the same type and amount of gasification component were added as in EXAMPLE 1. 21 ΡΕ1458660

In addition, 2% lubrication solution containing 50% urea and 50% water was also added. This was done by first mixing the gasification component for 10 seconds and then incorporating 2% of the lubricating water in 40 seconds. The rate of gasification was measured. It was found that this emulsion composition gassed to a density of 0.80 g / cc in 9 min. and reached a final density of 0.68 g / cc. When sensitization gas was withdrawn from the emulsion by shaking in the glove box, no NOx could be detected. This example shows that urea acts both as an accelerator and as NOx formation during the gasification process. EXAMPLE 7 (according to the invention)

For this experiment the following gasification component was made:

Sodium nitrite 15%

Urea 42% Water 43% 1% of this gasification component was added to the standard emulsion and mixed for 40 seconds. The gasification rate was recorded and it was found that this emulsion composition reached a density of 0.80 g / cc after 9 minutes, reaching a final cup density of 0.68 g / cc. When gas was withdrawn from the emulsion by stirring in the glove box, the Metrosonics Multi-gas Monitor could not detect any NOx. EXAMPLE 8 (according to the invention)

The same emulsion and the same type and amount of gasification component were added as in EXAMPLE 7. In addition to these, 2% lubrication water containing 50% urea was also added. This was done by first mixing the gasification component for 10 seconds and then incorporating 2% of the lubricating water for 40 seconds. The rate of gasification was measured. This emulsion composition was found to have gassed to a density of 0.80 g / cc in 9 min. and reached a final cup density of 0.68 g / cc. When the gas was withdrawn from the emulsion by shaking in the glove box, no NOx could be detected. EXAMPLE 9 (not according to the invention)

For this experiment the following gasification component was made:

Sodium nitrite 15%

Urea 42% Water 43% 1% of this gasification component was added to an emulsion in which the 2% citric acid was 23 ΡΕ1458660 replaced with 2% acetic acid (60%). The gasification component and this emulsion were mixed for 40 seconds. The gasification rate was recorded and this emulsion composition was found to have reached a density of 0.80 g / cc after 40 minutes. When the gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor detected a NOx concentration of 45 ppm. EXAMPLE 10 (according to the invention)

For this experiment the following gasification component was made:

Sodium nitrite 15% Water 85% And the following aqueous lubrication solution was made:

Water 60% Urea 40% 1% of this gasification component was added to a standard emulsion along with 2% of the aqueous lubrication solution and mixed for 40 seconds at a temperature of 50 ° C. The rate of gasification was recorded and this emulsion composition was found to have reached a density of 0.80 g / cc after 1 minute and 24 ΡΕ1458660 reached a final density in the beaker of 0.68 g / cc after 3 min. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor was unable to detect any NOx. EXAMPLE 11 (according to the invention)

For this experiment the following gasification component was made:

Sodium nitrite 15%

Urea 42% Water 43% 1% of this gasification component was added to a standard emulsion containing 0.3% citric acid in the oxidation solution and mixed for 40 seconds at room temperature. The gasification rate was recorded and it was found that this emulsion composition reached a density of 0.80 g / cc after 180 minutes. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor detected a NOx concentration of 2.5 ppm. EXAMPLE 12 (according to the invention)

For this experiment the following gasification component was made: 25 ΡΕ1458660

Sodium nitrite 15%

Urea 20% Water 65% The following aqueous lubrication solution was made: Water 50% Urea 50% 1% of this gasification component was added to a standard modified emulsion together with 2% of the aqueous lubrication solution and mixed for 40 seconds at a temperature of 23 ° C. The standard modified emulsion had 3% citric acid in the oxidizing solution instead of the 2% described in example 1. The pH value in this oxidizing solution was 0.65. The gasification rate was recorded and it was found that this emulsion composition reached a density of 0.80 g / cc after 9 minutes. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor detected a NOx concentration of 2.9 ppm. EXAMPLE 13 (according to the invention)

For this experiment the following gasification component was made: 26 ΡΕ1458660

Sodium nitrite 15%

Urea 42% Water 43% And the following aqueous lubrication solution was made:

Urea 42% Citric acid 14% Water 44% 1% of this gasification component was added to a standard emulsion containing 0.8% citric acid in the oxidizing solution and mixed for 10 seconds. Then, 2% of the aqueous lubrication solution was added and mixed for 40 seconds at room temperature. The gasification rate was recorded and it was found that this emulsion composition reached a density of 0.80 g / cc after 15 min with a final cup density of 0.76 g / cc after 20 min. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor detected a NOx concentration of 0.2 ppm. EXAMPLE 14 (according to the invention)

For this experiment the following gasification component was prepared: 27 ΡΕ1458660

Sodium nitrite 15%

Urea 20% Water 65% And the following aqueous lubrication solution was made:

Water 70% Urea 30%

The containers of the Dyno Site Mixes Emulsion truck were filled with these solutions. The SME truck produced an emulsion equal to that indicated in EXAMPLE 1, except that the fuel phase contained sorbitan mono-oleate (SMO) as an emulsifier instead of a polymeric type. The emulsion was produced at a temperature of about 80 ° C and pumped through a loading hose 80 meters long into the bore. 0.8% of this gasification component was added to the center of the emulsion as described in PCT / NO / 00275, and 2% of the aqueous lubrication solution was used to lubricate the loading hose. A mixing nozzle was mounted at the end of the loading hose. 100 kg / min were pumped through the loading hose into the holes and the gasification component and the aqueous lubrication solution were mixed with the emulsion at the end of the loading hose. This blend 28 ΡΕ1458660 was charged into 40 holes having a diameter of 102 mm. The explosion was successful throughout the round. During the charging process the rate of gasification was recorded in a small cup of density and it was found that this emulsion gassed completely in 10 seconds, reaching a final density in the cup of 0.80 g / cc. When the gas was removed from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor was unable to detect any NOx. EXAMPLE 15 (according to the invention)

For this experiment the following gasification component was prepared:

Sodium nitrite 15%

Urea 20% Water 65% And the following aqueous lubrication solution was made:

Water 50% Urea 50% 1% of this gasification component and 2% of the aqueous lubricating component were added to a standard emulsion in which the 2% citric acid was 29 Å and 45458660 replaced with 2% Tartaric Acid. The oxidizing solution had a pH of 0.55 before the emulsion was made. The gassing solution plus the aqueous emulsion lubrication solution was added and mixed for 40 seconds. The gasification rate was recorded and it was found that this emulsion composition reached a density of 0.80 g / cc after 6 minutes. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor detected a NOx concentration of 2.1 ppm. EXAMPLE 16 (according to the invention)

For this experiment the following gasification component was prepared:

Nitrite Sodium 15 g. " Urea 20 > " Water 65.0 15 the following aqueous lubrication solution was made:

Water 50 Urea 50 1% of this gasification component and 2% of the aqueous lubrication component were added to an emulsion 30 ΡΕ1458660 prepared as described in EXAMPLE 1 using an oxidizing solution of the following composition:

Ammonium nitrate 55% Calcium nitrate (Hydro TQ) 30% Water 13% Citric acid 2% and 6.5% of the polymeric fuel phase. The pH of the oxidant solution was measured to 0.0 before the emulsion was made. The gassing solution plus the aqueous emulsion lubrication solution was added and mixed for 40 seconds. The gasification rate was recorded and this emulsion composition was found to have reached a density of 0.80 g / cc after 4 minutes. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor detected an NOx concentration of 0.0 ppm. EXAMPLE 17 (according to the invention)

For this experiment the following gasification component was prepared:

Sodium nitrite 15 Urea 20

The following aqueous lubrication solution was made: Water 50% Urea 50% 1% of this gasification component and 2% of the aqueous lubrication component were added to an emulsion prepared as described in EXAMPLE 1 using a solution oxidant: Ammonium nitrate 82% Water 16% Citric acid 2% and 5.6% of the polymeric fuel phase. The pH of the oxidizing solution was measured up to 0.75 before the emulsion was made. The gassing solution plus the aqueous emulsion lubrication solution was added and mixed for 40 seconds. The gasification rate was recorded and this emulsion composition was found to have reached a density of 0.80 g / cc after 18 minutes. When gas was withdrawn from the emulsion by shaking in the glove box, the Metrosonics Multi-gas Monitor detected a NOx concentration of 1.7 ppm.

The examples are summarized in the following table - 32 - ΡΕ1458660

Example No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Oxidizing solution: Ammonium nitrate 72.5 72.5 72.5 72.5 72.5 72.5 72.5 72.5 72.5 72.5 73.7 71.8 73.4 72.5 72.5 55.0 82.0 Sodium nitrate 9.8 9.8 9.8 9.8 9.8 9.8 9, 8 9.9 9.8 9.8 10.0 9.7 9.9 9.8 9.8 - Calcium nitrate (Hydro, TQ) 30.0 Water 15.7 15.7 15.7 15, 7 15.7 15.7 15.7 15.7 15.7 15.7 16.0 15.5 15.9 15.1 15.7 13.0 16.0 Citric acid 2.0 2.0 2, 0 2.0 2.0 2.0 2.0 2.0 - 2.0 0.3 3.0 0.8 2.0 - 2.0 2.0 Tartaric acid - - - - - - - - - - - - - - 2,0 - - Acetic acid (60% ig) - - - - - - - - 2,0 - - - - - - - - pH of the oxidizing solution 0,98 0,98 0,98 0 , 98 0.98 0.98 0.98 0.98 1.90 0.98 1.60 0.55 1.10 0.98 0.55 0.00 0.75 Fuel stage: Mineral oil + polymeric emulsifier (¾ total emulsion) 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0, 5 5.6 ΡΕ1458660 33 (Continued) Mineral oil + sorbitan monooleate (¾ of the total emulsion ) 6.0 Gasification solution: Sodium nitrite 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 15.0 Sodium thiocyanate - 30.0 Thiourea - - 5.0 - - - - - - - - - - - - - Potassium iodine - - - 30.0 - - - - - - - - - - - - - - - Ammonium sulphate - - - - 30,0 - - - - - - - - - - Urea - - - - - - 42,0 42,0 42,0 - 42 , 0 20.0 42.0 20.0 20.0 20.0 20.0 Water 85.0 55.0 80.0 55.0 55.0 85.0 43.0 43.0 43.0 85, 0 43.0 65.0 43.0 65.0 65.0 65.0 65.0 Amount in% emulsion 1.0 1.0 1.0 1.0 1.0 1.0 1.0, 0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 ΡΕ1458660 - 34 - (Continued)

Aqueous lubricating solution: Urea - - - - - 50.0 - 50.0 - 40.0 - 50.0 42.0 30.0 50.0 50.0 50.0 Citric acid 14.0 - - - - - 50.0 - 50.0 - 60.0 - 50.0 44.0 70.0 50.0 50.0 50.0 Amount in% of emulsion 0.0 0.0 0.0 0.0 0.0 2.0 0.0 2.0 0.0 2.0 0.0 2.0 2.0 2.0 2.0 2.0 2.0 Gasification temperature (° C) 23 23 23 23 23 23 23 23 23 50 23 23 23 74 23 20 20 Gasification speed 11 210 min 6 min 55 min 70 min 160 min 9 min 9 min 9 min 41 min 1 min 180 min 9.0 min 15 min 10 sec 6 min 4 min 18 min NOx (ppm) in sensitized emulsion 21 10 130 300 22 33 0.0 0.0 0.0 45 0.0 2.5 2.9 0.2 0.0 2.1 0.0 1,7 According to the invention no no no no no yes yes yes no yes yes yes yes yes yes yes yes 11 Gasification rate is measured as time to reach a cup density of 0.80 g / cc 21 NOx is measured as the concentration when the sensitizing gas is withdrawn by stirring 160 cc of emulsion gassed and diluted in 100 liters. 35 ΡΕ1458660

Lisbon, November 26, 2007

Claims (7)

A method for preparing a sensitized emulsion explosive in a bore or package, wherein a) a phase of fuel and an oxidizing solution containing ammonium species and oxidizing salt are emulsified to form an emulsion, said emulsion being subjected to the gasification by mixing with b) a gasification solution containing inorganic nitrite in the presence of urea as a gasification accelerator where the emulsion explosive is poured into a bore or in a package by means of a loading tube or hose, allowing the gasification to occur at the end of said tube or hose, characterized in that the oxidizing solution has a pH value in the range of 0-3 and contains one or more organic acid (s) having at least three carbon atoms and the urea being present in the gasification solution and / or being present in a lubricating fluid added to the charging tube or hose. The method of claim 1, wherein the pH of the oxidizing solution is in the range of 0.4-2. 2 ΡΕ1458660 The method of claim 1-2, wherein the pH of the oxidizing solution is about 1. The method of claim 1, wherein the organic acid in the oxidizing solution is citric acid. The method of claim 1 or 4, wherein the organic acid in the oxidizing solution is tartaric acid. The method of any of claims 1, 4 or 5, wherein the oxidizing solution contains 0.2-5% of the organic acid. The method of any of claim 6, wherein the oxidizing solution contains 1.5-3% of the organic acid. Lisbon, 26 November 2007 ΡΕ1458660 ι REFERENCES REFERENCED IN THE DESCRIPTION The list of references cited by the applicant is intended only to clarify the reader. It is not part of the European patent document. Even if great care has been taken in compiling the references, errors or omissions can not be excluded and IPE does not assume any responsibility in relation to them. U.S. Pat. Nos. 5,169,168 to 4,499,146; and 4,299,168; and 4,899,167; and 4,249,197; and 4,249,167; THE