FIELD OF THE INVENTION
The present invention relates to a process for the preparation of free-flow copper (I) 5-
nitrotetrazolate (DBX-1).Furthermore, the present invention also relates to the
development of a lead-free green primary explosive composition based on DBX-1 i5 n
electric detonator No. 33.
BACKGROUND OF THE INVENTION
The energetic materials community is currently making efforts to produce ‘green’ or
10 environmentally less toxic explosives replacements for existing lead/mercury based
primary explosives, because of their deleterious effect on the environment as well as
health. [Reference: Huynh, M; Hiskey, M; Meyer, T; Meyer, M; Wetzler, M, Green
Primaries: Environmentally Friendly Energetic Complexes, Proc. Nat. Acad. Sci., 103
(2006) 5412-5412,Jenkins, J.M; White, J.R, Proceedings of International Conference on
15 Research in Primary Explosives, ERDE, Waltham Abbey, England (1975).]Although
lead azide is a good initiator, it suffers from many drawbacks such as less storage life
and extreme sensitivity towards thermal as well as mechanical stimuli. In view of these,
efforts are on globally to replace the above conventional initiatory explosives by
introducing eco-friendly, safe and storage-stable lead and mercury free initiators.
20
Transition metal complexes with high nitrogen containing heterocyclic as ligands have
been critically examined to replace the toxic metal (Pb/Hg) based initiators.
[Reference: Guchan, R.Mc., Improvements in primary explosive compositions and their
manufacture, Proceedings of 10th Symposium on Explosives and Pyrotechnics, (1979)
25 p. 1, Bates, L.R; Jenkins, J.M, Search for new detonant, Proceedings of International
Conference on Research in Primary Explosive, ERDE, Waltham, UK, March (1975) 1–
14, Barsan, M.E, Miller, A, Lead Health Hazard Evaluation, HETA Report No. 91-
0346-2572, 1996, National Institute for Occupational Safety and Health, Cincinnati,
USA] .
3
The search for new environmentally benign replacements for existing primary
explosives, has resulted in the development of copper (I) 5-nitrotetrazolate usually
known as DBX-1. DBX-1 has been extensively investigated and is considered as a
suitable replacement for lead azide in a variety of ordnance applications. DBX-1 ha5 s
excellent thermal stability and is comparatively less sensitive with explosive
performances against lead azide. It has safety and performance properties which are
equivalent to or exceed those for lead azide. (Reference: Fronabarger J. W., et al.,
DBX-1 – A Lead Free Replacement for Lead Azide, Propellants Explos. Pyrotech. 36
10 (2011) 541 – 550.
US8071784B2 relates to the synthesis of DBX-1 which involves the treatment of
cuprous chloride (CuCl) with sodium 5-nitrotetrazolate at elevated temperature. The
drawback of this method is due to the high temperature, it produces agglomerated fine
15 particles of DBX-1 crystals which limit its practical applications. Furthermore, the said
process involves removal of fine particles of DBX-1 by decanting the reaction mixture
and isolating only larger particles of DBX-1 as a result reduces the product overall
yield.
20 US8440008B2 is directed to a method for synthesis of DBX-1 wherein copper (II)
chloride is reacted with sodium 5-nitroterazolate in presence of reducing reagent under
elevated temperature. Sodium ascorbate is used as the reducing reagent to convert Cu
(II) in to Cu (I) in-situ and forming DBX-1. The drawback of this method is presence of
an additional reagent.
25
There is a need to overcome the limitations and drawbacks of the conventional reported
processes for the preparation of DBX-1 and hence develop an improved process for the
preparation of free-flow DBX-1 in good yield without adding any reagent or catalysts.
30 Electric Detonator No.33 is normally used to initiate secondary high explosive charge
for demolition purpose in military as well as civil applications, which has unique
4
dimension /size and charge mass to meet desired output. Typically, detonator No.33
contains 350mg of lead based ASA composition (i.e. lead azide, LA 65%; lead
styphnate, LS 32.5%; and aluminium, Al 2.5%) pressed over the base charge (550mg,
booster charge) of tetryl (CE) or PETN. The total explosive charge mass of
conventional electric detonator No.33 is 900mg. However such lead based explosiv5 e
formulations used in Electric Detonator No.33 are harmful to the health and
environment.
There is long felt need to develop a lead-free primary explosive composition which is
10 safe, demonstrates excellent performance properties and overcomes the drawbacks of
the conventional electric detonator No.33.
DBX-1 has been evaluated in PSEMC 104477-202 detonator and also stab primer mix
NOL-130 as replacement for lead azide. (Reference: Fronabarger, John W., et al.
15 "DBX‐1–A Lead Free Replacement for Lead Azide." Propellants, Explosives,
Pyrotechnics 36.6 (2011): 541-550). However, the said detonators replace lead based
composition with DBX-1 volume by volume; thereby resulting in the usage of higher
amounts of DBX-1 than required for an efficient performance of the detonator. The
usage of higher amounts of DBX-1 increases cost of manufacture of the detonator
20 explosive composition. The disadvantages of volume by volume replacement of DBX-1
are as follows:
(a) The main role of primary explosive charge (for e.g. ASA, DBX-1) is to
initiate the secondary booster charge (for e.g. PETN, RS-RDX). At the same
time the output performance of the detonator depends on the total charge
25 mass and density of the booster explosive.
(b) The energy output in terms of velocity of detonation (VoD) of DBX-1 is
greater than that of ASA composition. For DBX-1 = >7000m/s ; for ASA =
~4000m/s)
(c) The filling of higher amounts of DBX-1 in the aluminum tube (>150mg)
30 than required for an efficient performance of the detonator is not advisable.
5
Moreover, there should be an empty depth of ~24cm in the filled aluminum
tube left purposefully for placing the electric squib.
(d) The usage of higher amounts of DBX-1 increases cost of manufacture of the
detonator explosive composition.
(e) Furthermore, for filling higher amount of DBX-1 (>150mg) in th5 e
Aluminium tube, the existing design/dimension of the said aluminium tube
has to be changed , which may further increase the production cost of the
detonator.
10 Furthermore, the said detonators have different kind of size/dimension, explosive charge
mass and filling process. The conventional electric detonator No.33 is first filled with
550mg of PETN or CE and 350mg of ASA pressed at 7.2kg and 72kg respectively. The
said conventional filling process of explosives at such low dead weight in electric
detonator no.33 decreases density of charge mass. The performance of detonator is
15 dependent upon density of charge mass. Higher the density, higher the performance.
Therefore, the conventional lead based electric detonator no.33 demonstrates a low
performance.
The present inventors have surprisingly ameliorated the shortcomings of the prior art by
20 providing an optimized process for the preparation of free-flow DBX-1 in good yield
and also provides a lead-free green primary explosive composition based on DBX-1 in
electric detonator no.33.
OBJECTS OF THE INVENTION
25
It is an object of the present invention to provide a process for the preparation of freeflow
crystals of DBX-1 in good yield and high purity.
6
It is another object of the present invention to provide a process for the preparation of
free-flow DBX-1 without using additional reagents or catalysts thereby reducing the
overall manufacturing cost.
It is another object of the present invention to provide a process for the preparation o5 f
free-flow DBX-1 that can be scaled upto 10g per batch size.
It is another object of the present invention to provide a lead-free green primary
explosive composition based on DBX-1 as a single initiating charge in electric detonator
10 no.33 which is safe to environment, health and has excellent performance features.
It is another object of the present invention to provide a process for the filling of the
lead-free primary explosive composition in electric detonator no.33.
15
SUMMARY OF THE INVENTION
It is an aspect of the present invention to provide a process for the preparation of copper
20 (I) 5-nitrotetrazolate (DBX-1) comprising the following steps:
i. Pre-heating copper (I) salt in a solvent;
ii. Adding solution of 5-nitrotetrazolate salt to the copper(I) salt
solution of Step (i);
iii. Refluxing the reaction mixture obtained in Step (ii);
25 iv. Cooling the reaction mixture obtained in Step (iii);
v. Isolating the crystals of DBX-1 obtained in Step (iv) by filtering,
washing, and drying under vacuum.
Wherein the copper (I) salt is pre-heated in a solvent at a temperature ranging
from 40 to 60°C in Step (i).
30
7
It is another aspect of the present invention to provide a lead-free primary explosive
composition for electric detonator no.33 comprising:
i. An initiating charge Copper (I) 5-nitrotetrazolate (DBX-1) present in an
amount ranging from 100 to 150mg.;
ii. A booster charge present in an amount ranging from 400 to 550mg5 .
It is another aspect of the present invention to provide a process for the filling of a leadfree
primary explosive composition in electric detonator no.33 comprising the steps of:
i. Filling a booster charge in an amount ranging from 400 to 550mg and
10 pressing at dead load ranging from 20 to 45kg;
ii. Filling an initiating charge of DBX-1 over the booster charge in Step (i)
in an amount ranging from 100 to 150mg and pressing at dead load
ranging from 80 to 100kg.
BRIEF DESCRIPTION OF THE DRAWINGS
15 Figure 1: SEM image of DBX-1 crystals
Figure 2: Schematic of electric detonator No. 33 illustrating the following parts:
A: Aluminum tube B: Electric squib C: Primary charge DBX-1 D: Booster charge
such as PETN, RS-RDX, CE or CL-20
20
Figure 3: Performance Evaluation Test by Dent on lead witness plate
(a) Detonator assembled on 9mm thick witness lead plate;
(b) Dent on the lead witness plate after firing on detonator containing:
X: DBX-1/PETN, Y: DBX-1/RS-RDX, Z: Control detonator containing ASA
25 composition
Figure 4: Schematic diagram of demolition charge with detonator No. 33 illustrating
the following parts: P: Detonator with squib Q: CE pellet (Demolition charge)
8
Figure 5: (a) Detonator assembled with CE pellet; (b) Hole on steel plate after detonator
functioning.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a process for the preparation of copper (I) 5 5-
nitrotetrazolate (DBX-1) and its application in the development of lead-free primary
explosive compositions for electric detonator no.33.
The process involves the reaction of aqueous solution of a 5-nitrotetrazolate salt (for
example, sodium 5-nitrotetrazolate dihydrate) and a copper (I) salt (for example,
10 cuprous chloride (CuCl)) under reflux condition. The starting material sodium 5-
nitrotetrazolate dihydrate (SNT) can be prepared by the conventional process reported
in the art. The process involved for synthesis of DBX-1 is described below in Scheme-1.
N
N N
NH
NH2
1) NaNO2 / HNO3
CuSO4 .5H2O
2) NaOH, 70 C
O
- CuO
CuCl
N
N N
N
NO2
Na
+
5-AT
SNT
N
N N
N
NO2
DBX-1
H2O, reflux, 30 min
- NaCl
Cu(I)
15 Scheme-1: Synthesis of DBX-1
The process for the preparation of copper (I) 5-nitrotetrazolate (DBX-1) comprises the
following steps:
i. Pre-heating copper (I) salt in a solvent;
20 ii. Adding solution of 5-nitrotetrazolate salt to the copper(I) salt solution of Step
(i);
iii. Refluxing the reaction mixture obtained in Step (ii);
iv. Cooling the reaction mixture obtained in Step (iii);
v. Isolating the crystals of DBX-1 obtained in Step (iv) by filtering, washing, and
25 drying under vacuum.
9
Wherein the copper (I) salt is pre-heated in a solvent at a temperature ranging from
40 to 60°C in Step (i).
In an embodiment of the present invention, there is provided a process for the
preparation of DBX-1 comprising the following steps5 :
i. Pre-heating copper (I) salt in a solvent at a temperature ranging from 40 to
60°C;
ii. Adding solution of 5-nitrotetrazolate salt at the rate of 1 to 3mL/min under
10 stirring at speed of 150 to 200RPM;
iii. Refluxing the reaction mixture obtained in Step (ii) at a temperature ranging
from 75 to 950C for a duration of 30 to 60 minutes;
iv. Cooling the reaction mixture obtained in Step (iii) at the rate of 3 to 6015 C /min
under stirring at speed ranging from 70 to 100RPM ;
v. Isolating the crystals of DBX-1 obtained in Step (iv) by filtering, washing, and
drying under vacuum.
20
Any suitable copper (I) salt, or combination of copper (I) salts, may be employed.
Suitable copper (I) salts include, but are not limited to, cuprous chloride and cuprous
bromide. Cuprous chloride (CuCl) may be used as the preferable copper (I) salt.
25 Any suitable 5-nitrotetrazolate salt or a dihydrate thereof, or combination of 5-
nitrotetrazolate salts or a dihydrate thereof, may be employed. Suitable 5-
nitrotetrazolate salts include, but are not limited to, sodium 5-nitrotetrazolate and
potassium 5-nitrotetrazolate. Sodium 5-nitrotetrazolate (SNT) may be used as the
preferable 5-nitrotetrazolate salt.
30
10
Any suitable solvent, or combination of solvents, may be employed. Suitable solvents
include, but are not limited to, water, N-Methyl-2-pyrrolidone (NMP),
Dimethylformamide (DMF), as well as polar organic solvents.
Regarding quantities of the components employed, the molar ratio of 5-nitrotetrazolat5 e
salt and copper (I) salts is 1: 1.0 to 1.1. In an embodiment of the present invention, the
molar ratio of SNT and CuCl is 1: 1.0 to 1.1.
The process of the present invention involves the step of preheating the copper (I) salt in
10 solvent at a temperature from 40 - 60°C under nitrogen atmosphere, before adding 5-
nitrotetrazolate salt. The said pre-heating step increases the solubility of copper (I) salt
in solvent which results in a higher yield of the product DBX-1. Furthermore, it is
observed that when copper (I) salt solution is pre-heated at a temperature above 60°C,
there are chances of conversion of Cu (I) to Cu (II), thereby resulting in low yield of the
15 desired product DBX-1.
In an embodiment of the present invention there is provided a process for preparation of
DBX-1 that involves the controlled addition of sodium 5-nitrotetrazolate (SNT) solution
into preheated (~60°C) copper (I) chloride (CuCl) in water. After the addition is
20 completed, the reaction mixture is refluxed with continuous stirring. The reaction
mixture is further cooled to room temperature with stirring. The dark-brown colored
high density crystals of DBX-1 remain at the bottom of the reaction flask. The solid is
filtered, washed with water, isopropyl alcohol and dried under vacuum.
25 The yield of DBX-1 crystals obtained by the process of the present invention is 85%-
87% with a high purity of >99.5% (based on copper content) as measured by Atomic
absorption spectroscopy (AAS).
In an embodiment of the present invention, there is provided a process for the synthesis
30 of DBX-1 scaled upto 10g per batch with high yield and purity.
11
The DBX-1 crystals manufactured by the process of the present invention are
characterized by spectral and thermal techniques.
The present invention also relates to the development of a DBX-1 based lead-free
primary explosive composition for electric detonator no.335 .
In an embodiment the present invention provides a lead-free primary explosive
composition for electric detonator no.33 comprising:
i. An initiating charge Copper (I) 5-nitrotetrazolate (DBX-1) in an amount ranging
10 from 100 to 150mg;
ii. A booster charge in an amount ranging from 400 to 550mg.
The booster charge used in the lead-free primary explosive composition for electric
detonator no.33 is selected from pentaerythritol tetranitrate (PETN), Reduced
15 Sensitivity-RDX (RS-RDX), Hexanitrohexaazaisowurtzitane (CL-20) and tetryl (CE).
DBX-1 replaces the highly toxic and sensitive lead based ASA composition as a single
initiating charge along with booster charge selected from PETN, RS-RDX, CE and CL-
20 in tubular electric detonators No. 33.
20
The performance evaluation of the primary explosive composition for electric detonator
no.33 of the present invention is evaluated by various types of performance testing
including sensitivity to hot wire, priming ability to secondary explosives, dent on lead
witness plate and demolition of CE explosive charge.
25
The present invention also provides a process for the filling of the lead-free primary
explosive composition in electric detonator no.33 comprising the steps of:
i. Filling a booster charge in an amount ranging from 400 to 550mg and pressing
at dead load ranging from 20 to 45kg;
12
ii. Filling an initiating charge of DBX-1 over the booster charge in Step (i) in an
amount ranging from 100 to 150mg and pressing at dead load ranging from 80
to 100kg.
The performance of detonator is dependent upon density of charge mass. Whe5 n
increasing the charge mass density, overall output/performance of detonator increases.
The process provided by the present invention for the filling of lead-free primary
explosive composition in electric detonator no.33, wherein booster charge and DBX-1
based composition pressed at 20 – 45kg and 80 – 100kg dead load respectively (beyond
10 this, aluminium tube may get damaged) helps to achieve maximum density of charge
mass; thereby resulting in high performance as compared to conventional lead based
electric detonator no 33 detonators. The optimized dead loads for filling of DBX-1 and
booster charges help in achieving a high solid loading for enhanced output.
15 The benefits of implementing DBX-1 include environmental safety, and elimination of
the health hazards associated with manufacture and use of lead based composition.
EXAMPLES
The following examples are meant to illustrate the present invention. The examples are
20 presented to exemplify the invention and are not to be considered as limiting the scope
of the invention
Example-1
Synthesis of DBX-1
25 Solution of 4.20g (1.2eq) sodium 5-nitrotetrazolate in 40 mL distilled water was added
drop-by-drop into 500 mL preheated (60°C) Round bottomed flask contain 2.0g
(20.2mmol) of cuprous chloride (CuCl) in 40 mL distilled water with constant stirring
(200RPM) using magnetic stirrer under nitrogen atmosphere. After addition is
completed, the resulting mixture was refluxed using oil bath for 30 min with continued
30 stirring at 200RPM. Then, the reaction mixture was cooled at the rate of 3°C/min to
room temperature with stirring speed of 100RPM, a dark-brownish crystal of DBX-1
13
was settled down at the bottom of reaction vessel. The settled DBX-1 crystals were
filtered, washed with water, isopropyl alcohol and dried under vacuum at 60°C for 2 hrs
yielding pure crystals of DBX-1 with 87% yield (4.81g).
5
Example-2
Synthesis of DBX-1
Solution of 3.85g (1.1eq) sodium 5-nitrotetrazolate in 40 mL distilled water was added
drop-by-drop into 500 mL preheated (40°C) Round bottomed flask contain 2.0g
10 (20.2mmol) of cuprous chloride (CuCl) in 40 mL distilled water with constant stirring
(200RPM) using magnetic stirrer under nitrogen atmosphere. After addition is
completed, the resulting mixture was refluxed using oil bath for 45 min with continued
stirring at 100RPM. Then, the reaction mixture was cooled at the rate of 5°C /min to
room temperature with stirring speed of 100RPM a dark-brownish crystal of DBX-1
15 was settled in the reaction flask. The crystals were filtered, washed with water,
isopropyl alcohol and dried under vacuum at 60°C for 2 hrs yielding pure crystals of
DBX-1 with 86% yield (4.76g).
Example-3
20 Effect of preheating at a temperature >60°C on synthesis of DBX-1
The example-2 was repeated, only change is preheating at a temperature >60°C of
cuprous chloride (CuCl) before addition of SNT.
Solution of 3.85g (1.1eq) sodium 5-nitrotetrazolate in 40 mL distilled water was added
drop-by-drop into 500 mL preheated (90°C) Round bottomed flask contain 2.0g
25 (20.2mmol) of cuprous chloride (CuCl) in 40 mL distilled water with constant stirring
(200RPM) using magnetic stirrer under nitrogen atmosphere. Other experimental
conditions are followed as mentioned in example-2. A brownish fine particles of DBX-
1 was filtered, washed with water, isopropyl alcohol and dried under vacuum at 60°C
for 2 hrs yielding only 58% (3.21g) of DBX-1 with agglomerated particles.
14
Example-4
Scale-up at 10g per batch size of DBX-1
Solution of 8.73g (1.1eq) sodium 5-nitrotetrazolate in 90 mL distilled water was added
drop-by-drop into 500 mL preheated (50°C) Round bottomed flask contain 4.545 g
(45.9mmol) of cuprous chloride (CuCl) in 90 mL distilled water with efficient stirring
(200RPM) using magnetic stirrer under nitrogen atmosphere. Other experimental
conditions are followed as mentioned in example-2. A dark-brownish particles of
DBX-1 was filtered, washed with water, isopropyl alcohol and dried under vacuum at
10 60°C for 2 hrs yielding 85% (9.77g).
Example-5
Characterization of DBX-1
The crystalline DBX-1 is chemically stable under ambient atmospheric conditions.
15 DBX-1 was characterized by spectral and thermal techniques and the results are found
comparable with available literature data (Table-1). The Raman spectrum (Δν) of DBX-
1 showed the frequency at 380 cm-1 confirms the presence of metal-ligand vibrations.
Purity of the synthesized DBX-1 was determined using Atomic Absorption
Spectrometer (AAS). Repeated results from AAS analysis shows measured copper
20 content was 35.60% (Theory: 35.78%). Compatibility tests with DBX-1 and a variety of
booster explosive charges like PETN, RS-RDX (Reduced Sensitivity-RDX) & ε CL-20
were done by blending equal amount of DBX-1 and booster explosives using 0.6-0.3mg
of the blend in DSC experiments with a heating rate of 10°C. The results were
compared to DSC thermograph of the individual components run under identical
25 conditions following STANAG 4147 test criteria. The results shows DBX-1 do not have
any compatibility issues with PETN, RS-RDX and CL-20. The SEM image of DBX-1
crystals is shown in Figure-1. It appears that DBX-1 has smooth surfaced rod shaped
crystal morphology with free flow behavior of particle size 30-50μm.
15
Table 1: Comparison of the Energetic Properties of DBX-1 vis-à-vis Lead azide
(LA)
S.No Properties DBX-1 Lead azide (LA)
1 Decomposition temp.
by DSC (°C,
@10°C/min)
322 315
2 Purity (based on Cu
content by AAS)
99.5%
Cu: 35.60%
(Theory: 35.78%)
-
3 Impact (2kg, H50%,
cm)
25 10
4 Friction, g <50* 15
5 ESD, (mJ) 3.8 4.6
6 Particle size, (μm) 30 - 50 -
7 Crystal Density
(g/cc)
2.54 4.80
8 Crystals morphology
by SEM
Smooth orange rod
shaped crystals
-
* Low explosion was observed at 50g load
Example-6
Evaluation of DBX-1 as primary explosiv5 e
Various type of performance testing including sensitivity to hot wire, priming ability to
secondary explosives, dent on lead witness plate and demolition of CE explosive charge
were conducted and the results were compared with conventional detonators containing
ASA composition.
10
Sensitivity to hot wire
Sensitivity to hot wire was tested by pressing 50mg of DBX-1was filled into the stem of
aluminum tubular detonator No. 33 and pressed at 50kg dead load with 20 second dwell
time. An electric squib shouldered with a bridge wire (Nichrome) coated with pyro
15 composition, lead ferrocyanide (LFCN) was inserted in to the tubular detonator
touching the filled DBX-1 layer and crimped gently. The electric squib was initiated by
electric circuit and the study established that DBX-1 responds to initiation by hot wire
stimuli.
16
Example-7
Evaluation of DBX-1 as primary explosive: Ignition of secondary explosives
In order to examine ignition ability of DBX-1 with secondary explosives like PETN or
CE normally used as booster charge in detonators. 400 mg of PETN or CE filled in th5 e
tubular detonator and pressed at 20kg followed by 100 mg of DBX-1 was filled over
booster charge and pressed at 80kg load. The electric squib (LFCN) was inserted into
detonator tube and initiated by electric circuit. The booster charge was initiated
successfully and repeated experiments shows that DBX-1 has exceptional initiation
10 characteristic to secondary explosives.
Example-8
Process for Filling of DBX-1 in electric detonator No. 33
550mg of PETN (GPX-1) or RS-RDX (GPX-2) booster charge was filled into Al tube
15 detonator No. 33 pressed at 45kg dead load with a 20 second dwell time using Arbor
hand press. Followed by 150mg of DBX-1 was filled over booster charge (PETN or RSRDX)
and pressed 100kg with a 20 second dwell. The empty depth of above filled Al
tubular detonator was kept 24cm ±1cm for inserting the electric squib as shown in
Figure-2. The total charge mass (GPE-1 & GPX-2) is 700mg in the present invention,
20 whereas the conventional lead based detonator consists 900mg in detonator No. 33. The
details of charge mass filled in the detonators and their test results are summarized
below in the Table-2.
Table 2. Electric Detonator No. 33 filled with DBX-1 and PETN or RS-RDX and
their performance
Composition
PETN or RS-RDX
(Booster charge)
DBX-1
(Primary charge)
Test method*
Results#
Charge
mass
(mg)
D/L
(kg)
Charge
mass
(mg)
D/L
(kg)
GPX-1
550
(PETN)
45 150 100
Lead plate test Functioned &
observed desired
dent
Initiation of CE pellet exploded
17
CE pellet with enormous
sound
GPX-2 550
(RS-RDX)
45 150 100
Lead plate test Functioned &
observed desired
dent
Initiation of
CE pellet
CE pellet exploded
with enormous
sound
* Test methods are normally applied to evaluate the performance of electric detonator.
No. 33. # Results were compared with control detonator containing ASA composition
and found satisfactory.
Example-9
Performance of DBX-1 in detonator No. 33: Dent on lead witness plat5 e
An electric squib based on lead ferrocyanide (LFCN) (general purpose squib) was
inserted into the said DBX-1 and PETN or RS-RDX filled detonator and crimped the
aluminum tube to hold the squib suitably. The squib was connected to an electrical
circuit and functioning trials were carried out on 9mm width lead witness plate. It has
10 been observed from the firing results that detonator No. 33 comprising the lead-free
explosive composition of the present invention shows consistent and comparable
performance with conventional detonators. The impression on witness lead plate after
functioning of detonator No. 33 have been shown in Figure-3 wherein, detonator No.
33 was fixed horizontally on the 9mm witness lead plate. The series of test results
15 indicate that the impression developed after firing DBX-1 based detonator No. 33 are
comparable or better than that of conventional detonator No. 33. Also the composition
GPX-2 showed superior performance (dent) on lead witness plate as compared GPX-1.
This is due to GPX-2 contain RS-RDX which is more powerful than PETN.
20
Example-10
Performance of DBX-1 in detonator No. 33: Demolition of CE explosive charge
In order to evaluate potential of DBX-1 based detonator in main demolition charge, the
filled detonator No. 33 was inserted into demolition explosive charge, CE pellet (No. 5,
25 supplied by Ammunition Factory Khadki) as shown in the Figure-4. The assembled
detonator was initiated by electric squib. The functioning of the explosive train was
18
established by observing initiation of demolition charge and damage if any on the mild
steel witness plate. The test results shows DBX-1 based detonator detonated the main
demolition charge (CE pellet, 50gram) with more than one inch sharp hole over a 5mm
thick steel witness plate and found the performance similar or better than that of ASA
composition as demonstrated in Figure-5 5.
It is to be understood that the present invention is susceptible to modifications, changes
and adaptations by those skilled in the art. Such modifications, changes and adaptations
are intended to be within the scope of the present invention.
10
19

WE CLAIM:
1. A process for the preparation of copper (I) 5-nitrotetrazolate (DBX-1)
comprising the following steps5 :
i. Pre-heating copper (I) salt in a solvent;
ii. Adding solution of 5-nitrotetrazolate salt to the copper(I) salt solution of
Step (i);
iii. Refluxing the reaction mixture obtained in Step (ii);
10 iv. Cooling the reaction mixture obtained in Step (iii);
v. Isolating the crystals of DBX-1 obtained in Step (iv) by filtering,
washing, and drying under vacuum.
Wherein the copper (I) salt is pre-heated in a solvent at a temperature ranging
from 40 to 60°C in Step (i).
15
2. The process as claimed in claim 1, wherein solution of 5-nitrotetrazolate salt is
added to the copper(I) salt solution of Step (i) at the rate of 1 to 3mL/min under
stirring at speed of 150 to 200RPM;
20 3. The process as claimed in claim 1, wherein the reaction mixture obtained in
Step (ii) is refluxed at a temperature ranging from 75 to 950C for a duration of
30 to 60 minutes;
4. The process as claimed in claim 1, wherein the reaction mixture obtained in
Step (iii) is cooled at the rate of 3 to 6025 C /min under stirring at speed ranging
from 70 to 100RPM ;
5. The process as claimed in any one of the preceding claims, wherein the copper
(I) salt is selected from cuprous chloride or cuprous bromide.
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6. The process as claimed in any one of the preceding claims, wherein the 5-
nitrotetrazolate salt is selected from sodium 5-nitrotetrazolate or potassium 5-
nitrotetrazolate or a dihydrate thereof.
7. The process as claimed in any one of the preceding claims, wherein the mola5 r
ratio of 5-nitrotetrazolate salt and copper (I) salt is 1: 1.0 to 1.1.
8. The process as claimed in any one of the preceding claims, wherein the solvent
is selected from water, N-Methyl-2-pyrrolidone (NMP), dimethylformamide
10 (DMF) or polar organic solvents.
9. A lead-free primary explosive composition for electric detonator no.33
comprising:
i. An initiating charge Copper (I) 5-nitrotetrazolate (DBX-1) present in an
15 amount ranging from 100 to 150mg;
ii. A booster charge present in an amount ranging from 400 to 550mg.
10. The lead-free primary explosive composition as claimed in claim 9, wherein the
booster charge is selected from pentaerythritol tetranitrate (PETN), Reduced
20 Sensitivity-RDX (RS-RDX), Hexanitrohexaazaisowurtzitane (CL-20) or tetryl
(CE).
11. A process for the filling of a lead-free primary explosive composition in electric
detonator no.33 comprising the steps of:
25 i. Filling a booster charge in an amount ranging from 400 to 550mg and
pressing at dead load ranging from 20 to 45kg;
ii. Filling an initiating charge of DBX-1 over the booster charge in Step (i)
in an amount ranging from 100 to 150mg and pressing at dead load
ranging from 80 to 100kg.
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12. The process as claimed in claim 11, wherein the booster charge is selected from
pentaerythritol tetranitrate (PETN), Reduced Sensitivity-RDX (RS-RDX),
Hexanitrohexaazaisowurtzitane (CL-20) or tetryl (CE).