AU726345B2 - A non-incendive water-in oil emulsion explosive composition - Google Patents

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): ICI India Limited- 52890/98 Orica Explosives Technology Pty Ltd 9.

9 .9 9 9* 9 9.

ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

INVENTION TITLE: A non-incendive water-in oil emulsion explosive composition The following statement is a full description of this invention, including the best method of performing it known to me/us:- P:\OPER\PHH\52890-98.WPD 2/3/00 -2- The present invention relates to water-in-oil emulsion explosive compositions that can be used as P-5 permitted explosives in underground coal mines of Degree III gassiness.

More particularly, the present invention relates to a non-incendive, water-in-oil emulsion explosive composition and a process for preparing such composition.

P-5-type explosives are commonly used in underground coal mines of high gassiness.

These explosives are also specifically approved for Blasting of solid application in Degree I II mines. Currently NG-type (nitroglycerine) explosives are used. However, these conventional explosives suffer from several inherent drawbacks. These include the physiological effects of use of NG explosives as well as high post-detonation toxic fumes and deflagration characteristics.

In an attempt to overcome some of the above-mentioned drawbacks watergel explosives have been used, with limited success. Watergel explosives show reduced postdetonation toxic fumes and low tendency to deflagrate. However, performance of the watergels has generally been unreliable.

15 P-5 emulsion explosives are expected to overcome these problems while affording the advantages of very low post-detonation toxic fumes. They are also non-deflagrating.

The design of P-5 explosives is an art in itself because of conflicting requirements with respect to statutory approvals and performance. In order to be able to pass the stringent gallery tests it is essential to dope the explosive with large quantities of inerts. However, doping explosives with inerts more often than not adversely affects the sensitivity of the explosive as well as its performance. Therefore, an optimum balance has to be arrived at in making such experiments.

Water-in-oil emulsion explosives which can be used under P1 P3 conditions, ie.

Degree I and Degree II gassiness mines, are disclosed in the prior art. These explosives require coolants since hot explosive gases which are released tend to ignite methane/air gas mixtures in underground mines. Such coolants have normally been water and salt. US patent 5,017,251 discloses the use of salt for P1 type explosives.

Similarly, the prior art literature also reports very high doping of salt and use of glass microballoons (GMB's) at high loading to achieve a desired sensitivity (Patent No. ZA 043516, US 6017261M, AU 0067072M, AU 8656181, US 4976793M, CN 1031363). The use of such high loading of GMB's is an economically unviable proposition.

P:\OPER\P--\52890-98.AME.DOC 4/9/00 -3- The basic object of the present invention is therefore, to provide a P-5 emulsion explosive which alleviates the drawbacks and disadvantages of prior art compositions.

According to the present invention there is provided a non-incendive, water-in-oil emulsion explosive composition which comprises an aqueous solution of one or more inorganic oxidiser salts, a fuel phase and from 5 to 50% by weight of the total composition of one or more solid dopants, wherein said solid dopant(s) at least include a coolant selected from one or more of alkali metal and alkaline earth metal salts and ammonium chloride and said non-incendive water-in-oil emulsion explosive composition includes a flame quencher selected from ammonium, alkali metal, alkaline earth metal or transition metal salts of phosphoric acid.

Further according to the present invention, there is provided a process for the manufacture of a non-incendive water-in-oil emulsion explosive composition as described in the immediately preceding paragraph which comprises forming an aqueous solution of said one S•or more inorganic oxidiser salts, combining said aqueous solution with the fuel phase, adding to said mixture the one or more solid dopant coolants, adding the flame quencher, and S 15 emulsifying said mixture to obtain said emulsion explosive composition.

S.By the invention, a P-5 emulsion explosive composition is provided by the use, in addition to water and one or more of ammonium chloride and salts of alkali and alkaline earth metals as coolants, of phosphoric acid salt as a flame quencher.

It has advantageously been found that such P-5 emulsion explosive compositions are 20 sensitive to detonation in 32 mm diameter cartridges using commercially available blasting caps which are approved for use in underground coal mines.

The one or more inorganic oxidiser salts, which in the aqueous solution constitute the discontinuous phase of the P-5 emulsion explosive compositions of the present invention, may be selected from ammonium nitrate, alkali metal nitrates such as sodium nitrate and potassium nitrate, and perchlorate salts of sodium, potassium or ammonium. The perchlorate salts may be added as a chemical sensitiser, the preferred one being sodium perchlorate.

The flame quencher is preferably selected from the dibasic salts of phosphoric acid such as disodium and ammonium, and is advantageously a hexametaphosphate. The most preferred salts are ammonium. The flame quencher(s) used in the present invention may be present either in the oxidiser solution phase of the P-5 emulsion formulations or as one of the components of /I solid dopants or both. The flame quencher salt(s) may be present in an amount ranging from P:\OPER\PHH\52890-98.AME.DOC 4/9/00 -4- 0.1 to 10.0%, preferably, in the range of 0.5 to 8.0% and most preferably, in the range of by weight of the composition.

In addition to the flame quencher salt(s) the coolant salt(s) are added as solid dopants to confer non-incendivity to the water-in-oil emulsion explosive when subjected to gallery testing as per IS:6609 (Part II/Sec. 2) 1974. The coolant salt(s) are selected from, preferably, chlorides of sodium, potassium and ammonium. The solid dopants, which may include some or all of the flame quencher salt(s) in addition to the coolant salt(s) are present in an amount in the range from 5 to 50%, preferably in the range from 10 to 40%, more preferably in the region of 20 to 35% by weight of the composition.

The water content of the aqueous solution of the one or more inorganic oxidiser salts is preferably in the range of from 5 to 16% by weight based on the total weight of the explosive composition. The aqueous solution may be present in a range of from 50 to 80% by weight of the explosive composition.

The fuel phase may be present in a range of from 3 to 60% by weight of the explosive 15 composition. The fuel phase may comprise one or more members selected from the group consisting of carbonaceous fuels such as low sulphur heavy stock, microcrystalline wax, slack wax, paraffin wax, montan wax, whale wax, bees wax, agro wax, ozokerite, diesel oil, paraffin oil, tall oil and other hydrocarbon fuels containing paraffinic hydrocarbons, aromatic oo& hydrocarbons, olefinic hydrocarbons or nitrocarbons.

20 More preferably, the fuel phase contains at least one fuel comprising highly branched paraffinic hydrocarbonand/or their isomers having from 14 to 40 carbon atoms.

The fuel phase may also contain one or more emulsifiers.

The fuel phase most preferably comprises a mixture of straight chain and branched chain waxy materials which are commonly referred to as microcrystalline and paraffin waxes, emulsifiers and fuel comprising paraffin oil either alone or in combination with a residue from petroleum crude of low sulphur content which is commercially known as LSHS (low sulphur heavy stock). This fuel makes the bilayers more flexible when subjected to stress and thus help reduce the shear sensitivity of the doped emulsions. Additional fuels selected from the above conventional carbonaceous and hydrocarbon fuels may be included in this most preferred fuel 0, phase, depending on consistency of the final emulsion compositions desired.

The addition of emulsifiers to the fuel phase of the composition may impart a high P\OPERPTHNS2890.98AME DOC 4/9/00 degree of stability to the composition, especially in view of the high quantity of solid dopants.

These emulsifiers, which are employed in predetermined molar ratios depending upon the other ingredients include the particularly preferred condensation product(s) of maleinised polyisobutylene based surface active agent(s) and alkanol amines which may be manufactured under the code name E-475/E-476. This is advantageously present in an amount ranging from to 3.0% by weight, preferably in the region of 1.0 to 3.0% by weight.

Other emulsifiers include polymers prepared by the condensation of long chain aliphatic carboxylic acids with polyethylene glycol of molecular weight between 400 and 3000, esters of sorbitol with long chain fatty acids such as sorbitan monoleate (SMO), sorbitan trioleate (STO) or sorbitan sesquioleate (SSO), phospholipids such as soyalecithin (SL) or oxazoline or imidazoline derivatives thereof, lanolin, a steroidal product obtained from wool fat, phosphoric acid esters, and also other paraffinic fuel-compatible surfactants available under different brand names.

In the method of the invention the aqueous solution of the oxidiser salts is preferably S 15 maintained at a temperature of 60°C to 100°C while the fuel phase is kept at a temperature of C to 90 0 C before being fed for emulsification to an emulsification apparatus. This apparatus can be either a motionless static mixer or rotary emulsifying equipment.

The flame quenching agent may be incorporated into said aqueous inorganic oxidiser salt solution and/or with the solid dopants prior to combination thereof with the fuel phase and 20 emulsification of the mixture.

After emulsification, a chemical gassing agent such as described above may be incorporated into the emulsion for controlling its density. More preferably, the gassing agent is incorporated into said emulsion by shearing action in order to disperse it properly therein and facilitate interaction between the gassing agent and the oxidiser salts present in the micro droplets.

If required, the resulting emulsion can be further refined in any known manner.

Depending upon the purpose and the end use of the products, the emulsions can be cooled to a desired temperature lower than the temperature of manufacture.

Finally, the emulsion explosives may be cartridged in suitable packages of desired diameter.

The invention will now be described, by way of a comparative Example I and a non-limiting SQ illustrative Example II. It must be borne in mind that the embodiment described is P:\OPER\PHH\52890-98.WPD 2/3/00 -6merely illustrative of the present invention which is not limited to the specific example mentioned herein.

Example I Ingredient Ammonium Nitrate Sodium Nitrate Sodium Perchlorate (100%) Water PIBSA Surfactant Sorbitan Mono Oleate Paraffinic Oil Rubber Latex Sodium Nitrite Sodium Chloride by weight 45.4 7.7 5.6 7.7 2.1 0.14 2.24 0.07 0.10 30.00 eeee r Example II Ammonium Nitrate Sodium Nitrate Sodium Perchlorate (100%) Diammonium hydrogen phosphate Water PIBSA Surfactant Sorbitan Mono Oleate Paraffinic Oil Rubber Latex Sodium Nitrite Sodium Chloride 42.6 5.6 2.8 7.7 2.1 0.14 1.89 0.07 0.10 30.00 P:\OPER\PHH\52890-98.AME.DOC -4/9/00 -7- The compositions of Examples I and II were subjected to incendivity tests as applicable to Group P5 permitted explosives as per IS:6609 (Part II/Sec. 2) 1974 and the results are given below: No. of shots Ignitions allowed Example I Example II 1) Inverse initiation to methane/air under cutoff condition 20 shots of 565g Ci

S

CC..

.CC

C

C

C

*SC

CC

2) Direct initiation into methane/air 3) Inverse initiation into coal dust 5 shots of 1030 g 5 shots of 565 g Not done Not done The above examples clearly delineate the role of salts of phosphoric acid in conferring non-incendive character to a formulation.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Claims (15)

1. A non-incendive, water-in-oil emulsion explosive composition which comprises an aqueous solution of one or more inorganic oxidiser salts, a fuel phase and from 5 to 50% by weight of the total composition of one or more solid dopants, wherein said solid dopant(s) at least include a coolant selected from one or more of alkali metal and alkaline earth metal salts and ammonium chloride and said non-incendive water-in-oil emulsion explosive composition includes a flame quencher selected from ammonium, alkali metal, alkaline earth metal or transition metal salts of phosphoric acid.

2. A non-incendive water-in-oil emulsion explosive composition as claimed in claim 1 wherein the flame quencher is a dibasic salt of phosphoric acid.

3. A non-incendive water-in-oil emulsion explosive composition as claimed in claim 2 15 wherein the flame quencher is a hexametaphosphate salt.

4. A non-incendive, water-in-oil emulsion explosive composition as claimed in any preceding claim wherein the flame quencher is present in an amount of 0.1 to 10% by weight. C 20 5. A non-incendive, water-in-oil emulsion explosive composition as claimed in any preceding claim wherein the flame quencher is present at least partly in the aqueous solution of inorganic oxidiser salt(s). C*

6. A non-incendive, water-in-oil emulsion explosive composition as claimed in any preceding claim wherein the flame quencher is present at least partly as one or more of the solid dopants.

7. A non-incendive, water-in-oil emulsion explosive composition as claimed in any preceding claim wherein said coolant is selected from one or more of chlorides of sodium, potassium and ammonium. i RA uJ '~~iOJT P:\OPER\PHH\52890-98.WPD 2/3/00 -9-

8. A non-incendive, water-in-oil emulsion explosive composition as claimed in any preceding claim wherein said one or more solid dopants are present in an amount of from to 40% by weight, preferably from 20 to 35% by weight of the composition.

9. A non-incendive, water-in-oil emulsion explosive composition as claimed in any preceding claim wherein said one or more oxidiser salts are selected from ammonium nitrate, alkali metal nitrates and perchlorate salts of sodium, potassium and ammonium. A non-incendive, water-in-oil emulsion explosive composition as claimed in any preceding claim wherein the water content of said composition is in the range of from 5 to 16% by weight.

11. A non-incendive, water-in-oil emulsion explosive composition as claimed in any 1 preceding claim wherein said fuel phase comprises one or more members selected from the group consisting of carbonaceous fuels such as low sulphur heavy stock, microcrystalline wax, slack wax, paraffin wax, montan wax, whale wax, bees wax, agro wax, ozokerite, diesel oil, paraffin oil, tall oil and other hydrocarbon fuels containing paraffinic hydrocarbons, aromatic hydrocarbons, olefinic hydrocarbons or nitrocarbons.

12. A non-incendive water-in-oil emulsion explosive composition as claimed in any preceding claim wherein said fuel phase contains at least one fuel comprising highly branched paraffinic hydrocarbon and/or their isomers having from 14 to 40 carbon atoms.

13. A non-incendive water-in-oil emulsion explosive composition as claimed in any preceding claim wherein said fuel phase comprises an emulsifier selected from one or more of condensation products of polyisobutylene surface active agent and alkano amines and long chain aliphatic carboxylic acids with polyethylene glycol of molecular weight between 400 and 3000, esters of sorbitol with long chain fatty acids such as sorbitan monooleate (SMO), sorbitan trioleate (STO) or sorbitan sesquioleate (SSO), phospholipids such as soyalecithin (SL) or oxazoline or imidazoline derivatives thereof, lanolin, a steroidal product obtained from wool fat or phosphoric acid esters and also other paraffinic fuel compatible surfactants. P:\OPER\PHH\52890-98.WPD 2/3/00

14. A non-incendive water-in-oil emulsion explosive composition substantially as herein described with reference to Example II. A process for the manufacture of a non-incendive water-in-oil emulsion explosive composition as claimed in claim 1 which comprises forming an aqueous solution of said one or more inorganic oxidiser salts, combining said aqueous solution with the fuel phase, adding to said mixture the one or more solid dopant coolants, adding the flame quencher, and emulsifying said mixture to obtain said emulsion explosive composition.

16. A process as claimed in claim 15, wherein at least some of the flame quencher is added to the aqueous solution.

17. A process as claimed in claim 15 or claim 16 wherein at least some of the flame .quencher is added to the mixture as solid dopant.

18. A process as claimed in any one of claims 15 to 17 wherein said emulsification is carried out in the presence of a gassing agent and/or density reducing agent. DATED this 2nd day of March, 2000 ICI INDIA LIMITED o By Its Patent Attorneys DAVIES COLLISON CAVE