Process for preparing nickel hydrazine nitrate, for tubular detonators
FIELD OF INVENTION
The present invention relates to a process for the preparation of nickel hydrazine nitrate (NHN) an energetic co-ordination compound of bulk density >1.14 g/cm3 with free-flow nature and its use in tubular detonators (Detonator No.27 and 33) to replace the conventional lead / mercury based detonations as a single component.
Background and Prior Art
Detonators are the first-fire device of key importance in any explosive train. The detonators contain a small quantity of very sensitive explosive as means of initiation. The inorganic salts of weak acid i.e. mercury fulminate (MF), lead azide (LA), silver azide (SA) and lead styphnate (LS) are generally used as ingredients in detonator compositions.
Mercury fulminate (MF) was the first choice as the initiator. It still finds use as one of the ingredients in cap composition for Small Anns Ammunitions (SAA).
However disadvantage of using mercury fulminate is hypersensitive to mechanical stimuli, poor storage stability and deleterious effects on environment and health. The main disadvantage of using MF is that it is dead-pressed when compressed under pressure exceeding 200 kg/cm2 and becomes insensitive to ignite by flash.
Service lead azide (SLA) replaced the mercury fulminate in most of the devices in later stages, and unlike mercury fulminate, it does not get dead-pressed. The disadvantage of using SLA as initiatory compound is that it is highly sensitive towards mechanical stimuli and leads to hazards during manufacturing and processing. Moreover, SLA has poor storage stability in presence of moisture and carbon dioxide resulting in hazardous species. Further disadvantage of using SLA is its poor compatibility with metals like copper (casing material), resulting in hazardous and highly sensitive product of copper azide.
, Recently basic lead azide (BLA) replaced the use of SLA in most of the detonating compositions. BLA base compositions are generally the physical mixture of BLA, LS and Al powder called as BLASA. BLA replaces SLA in initiatory compositions. However, main disadvantage of using BLA is its relative insensitiveness to flame and poor storage stability in presence of moisture and carbon dioxide.
Lead Styphnate (LS) is another primary explosive which is widely used to make BLA flash sensitive. However, LS has the following drawbacks: (a) Its initiating power is less as compared to other primary explosives and therefore, cannot be used as the main charge; (b) It is very sensitive towards the electrostatic charge; (c) Its accelerating power to decompose the LA results in the formation of hazardous products.
Existing primary explosives include organic compounds, metastable-innerstitial-composites (MICs), and coordination complexes. The major disadvantages of organic compounds are that (1) they are susceptible to being degraded by boiling water, (2) they are unstable in moisture, and heat; (3) they darken rapidly by exposure to sunlight; (4) they contain perchlorate; and (5) they undergo molecular elimination followed by intramolecular rearrangement. Mixtures of aluminum nanoparticles and heavy metal oxides (MICs) are known to have appropriate sensitivity. However, instability toward atmospheric oxygen and moisture, safety concerns during large scale production, and residual heavy metal contaminations have prevented their adoption as lead primary replacements. The thermally stable cationic coordination complexes have desirable properties, but their perchlorate content makes them unacceptable.

explosives1"3 by introducing eco-friendly, safe, better storage-stability and lead/mercury
In view of these, efforts are on globally to replace these conventional initiatory explosives1"3 by free initiatories.
Synthesis and characterization of NHN have reported by Shunguan et at of bulk density 0.62 - 0.82. Present studies describe a method for higher bulk density (1.14g/cm3 and particle size 114um) of nickel hydrazine nitrate (NHN), which has potential to meet the
detonant requirements. NHN is a thermally and hydrolytically stable and easily prepared from available raw materials, NHN is less sensitive to impact, friction and electrostatic
S 8
charge, but is sensitive to flame/flash " .
To the best of our knowledge none of the publications reports the actual process for the preparation of NHN having bulk density 1.14g/cm3 with free flow nature, and its use as detonants in tubular detonators. In the view of processing and filling of NHN in the tubular detonators there is need for higher bulk density (>1) and free-flow nature of NHN. However, Sandia National Laboratories (SNL) USA, reported the potential use of NHN for hot wire applications9.
OBJECTIVES OF THE PRESENT INVENTION
The main objective of the present invention is to provide a well established process for the preparation of NHN of bulk density ~ 1.14 g/cm3 and particle size ~114|am with free-flowing nature by controlling the process parameters.
Another objective of the present invention is to establish a filling process using NHN as a single main charge mass with booster charge mass of pentaerythritol tetranitrate (PETN) in tubular detonators and evaluate their performance in comparison with regular detonators based on azide / styphnate / aluminium powder.
Yet another objective of the invention is to use eco-friendly, safe, and lead/mercury free intiatories.Still another objective of the invention is to provide an intiatories having better storage stability.
Yet another objective of the invention is to develop a cost effective, non toxic, stable NHN, which can be prepared from indigenously and commonly available chemicals.
Yet another objective of the invention is use of components in the process of preparation NHN based detonators that are not flammable or corrosive.
STATEMENT OF INVENTION
Accordingly, the present invention describes a process for preparing nickel hydrazine nitrate (NHN), for in tubular detonators comprising the steps of:
a) dissolving 90 to 110 g of nickel nitrate in distilled water;
b) dissolving 45 to 55ml of hydrazine hydrate in distilled water;
c) mixing the solutions of step (a) and step (b) dropwise to distilled water with
constant stirring at a speed of almost 40RPM for one hour at a temperature of 80
to 90°C and thereby obtaining precipitates of NHN;
d) washing the precipitates of step (c) with water and acetone followed by drying at
a temperature of 50-60°C for 1-2 hour to obtain NHN crystals
having bulk density of 1.10 to 1.15g/cm3 and particle size of 110-130 (am and wherein the molar ratio of nickel nitrate to hydrazine hydrate is 1:3.
SUMMARY OF THE INVENTION;
Developing qualified initiator is much like searching for effective drugs or creating efficient catalysts. Energetic materials chemists manipulate chemical functionality to obtain desirable sensitivity and choose molecular backbones to improve explosive performance. Coordination chemists judiciously select metals as well as ligands to design inexpensive catalysts and then fine-tune reaction conditions to maximize products. To achieve this goal, the present invention provides a process for preparing Nickel Hydrazine Nitrate (NHN), used as initiators in tubular detonators, having bulk density >1.14 g/cm3 with free-flow nature. NHN is thermally and hydrolytically stable and easily prepared from available raw materials.
DETAILED DESCRIPTIONS OF INVENTION
Accordingly, the present invention relates to a process for preparing nickel hydrazine
nitrate (NHN), of tubular detonators comprising the steps of: a) dissolving 90 to 110 g of nickel nitrate in distilled water;
b) dissolving 45 to 55ml of hydrazine hydrate in distilled water;
c) mixing the solutions of step (a) and step (b) dropwise to distilled water with
constant stirring at a speed of almost 40RPM for one hour at a temperature of 80
to 90°C and thereby obtaining precipitates of NHN;
d) washing the precipitates of step (c) with water and acetone followed by drying at
a temperature of 50-60°C for 1 -2 hour to obtain NHN crystals
having bulk density of 1.10 to 1.15 g/cm3 and particle size of 110-13 0 urn and wherein the molar ratio of nickel nitrate to hydrazine hydrate is 1:3.
One another embodiment of the embodiment of the present invention wherein the molar ratio of nickel nitrate hexahydrate and hydrazine hydrate is 1:3.
In one another embodiment of the present invention where-in the solutions of nickel nitrate hexahydrate and hydrazine hydrate are added simultaneously to the known quantity of warm water (~ 85 °C temperature)
Yet another embodiment of the present invention where-in the reaction mixture is stirred at low speed only (~ 40 RPM).
Still another embodiment of the present invention where-in the stirrer of blade size of diameter 25 - 40 mm half moon is used.
Another embodiment of the present invention where-in the digestion of reaction mixture is carried out for 30 - 40 minutes.
Yet another embodiment of the present invention where-in the mother liquor is decanted cautiously and the product is thus washed with plenty of water.
Another embodiment of the present invention where-in the product of NHN is then treated with acetone solvent to ensure removal of traces of water.
Still another embodiment of the present invention where-in the product is dried at 55 C for one hour.
Yet another embodiment of the present invention wherein single component with booster charge of pentaerythritrol tetranitrate (PETN) in tubular detonators is used.
Still another embodiment of the present invention wherein bulk density of NHN is 1.14 g/cm3.
Yet another embodiment of the present invention the particle size of NHN is 114 to 120 jam.
1. Working example: Synthesis of NHN
This invention comprises a simple method for synthesis of nickel hydrazine nitrate (NHN) having the molecular formula HiaNgNiOe as a single detonant in tubular detonators.
The method involves 100 ± 10 g (-0.4 mol) of nickel nitrate [Ni (NO3)2. 6 H20] is dissolved completely in 250 ml of distilled water and 50 ± 5 ml (~1 mol) of hydrazine monohydrate (-99%) is diluted to 400 ml of distilled water. Both solutions are added drop by drop to 500 ml distilled water at 85 ± 5°C over a period for 1 hr with control stirring. It is important to note that while adding the reagents, the temperature and stirring speed should be controlled to get desired bulk density and particle size distributions. During adding the solutions simultaneously, a colour change is observed in the reaction mixture after 20 min followed by a pink colored precipitate of NHN crystals. After completion of addition, the reaction mixture is stirred for another 30 min. Precipitate thus obtained is filtered, suctioned and washed with plenty of distilled water, followed by acetone and dried for 1 hr at 55°C to yield 75 - 86g of NHN; purity >98% and particle size of free-flow NHN ~120um.
2. Characterization
The synthesized NHN was characterized by spectroscopic and thermal techniques. IR (KBr) spectrum of NHN revealed that peaks at 3238 and 1626 cm"1 corresponds to NH2 group; peaks at 1356 and 550 cm"1 attributed to NO3 and Ni-N respectively. Nickel content of NHN was estimated to be 20.6% (calculated 21%) by gravimetric method. The final free flow material of NHN was measured for its bulk density which was the order of 1.14g/cm3 and particle size distributions (~114um) measured by Malvern instrument whereas fluffy material of NHN of bulk density ~0.6g/cm3 and particle size 31 urn. NHN was subjected to sensitivity test and the data show that impact (h5o%) and friction sensitivity of NHN are 45 cm and 1kg respectively. SEM image (fig. 1) of NHN indicates the square shaped crystal.(Figure Removed)
Fig. 1 scanning electron micrograph (SEM) of NHN
3. Performance evaluations
(a) The demolition of explosive charges based on RDX/TNT along with booster charge (CE) has been initiated by NHN based detonator using safety fuze or squib. The initiation process was found to be satisfacty. The details of explosive composition, methods of initiation and results are summarized in Table 1.
Table 1. NHN based detonators for demolition of explosive charges(Table Removed)LFCN: Lead ferrocyanide CE: Composition exploding (Tetryl)
The results are compared with control same
(b) The conventional tubular detonators normally contain ASA composition (Azide-Styphnate-Al powder) as the initiating charge and CE as the booster charge. Among these detonators, det. No. 27 are initiated using safety fuze No 11 and 16 whereas, safety fuze No 16 showed partial functioning of detonator No 27. This partial function is probably due to slow burning nature of safety fuze No 16. Detonators No. 33, which have been initiated by Electro explosive devices (EED), are functioned satisfactorily (table 2).
Table 2. Function test of NHN based detonators No.27 using slow and fast burning safety fuse(Table Removed)MFE = Mean functioning efficiency
The results are compared with control same
(c)We have tried to replace the initiating composition by NHN and the base charge by PETN in both the types of detonators, with varying proportion of PETN/NHN and all of them performed very satisfactorily. The results are given in the tables 3 and 4.Table 3. Filling detonators No 27 with different NHN bulk density (BD) (Table Removed)Table 4. Filling detonators No 33 with different NHN bulk density (BD) (Table Removed)D:
BD of NHN -1.1 33 350 7.2 400 72 100
g/cm3
(d) The impression on witness lead plate after functioning of detonator No.33 have been shown below where, detonator No.33 was fixed horizontally on witness lead plate. The functioning results indicate that the impression developed after firing NHN based detonator No.33 are comparable with regular detonator No.33 (figure 2-4)
Figure 2. Photo copy of impression on witness lead plate of ASA (regular det. No.33) and NHN based detonators No.33
(Figure Removed)Figure 3. Photo copy of impression on witness lead plate of NHN based detonators No.33
(Figure Removed)Figure 4. Photo copy of impression on witness lead plate of NHN based detonators No.33(Figure Removed)
Advantages;
1. Nickel Hydrazine Nitrate are quantitatively precipitated and analytically pure without
the need for purification and re-crystallization. Hence, their production is quite cost-
effective.
2. These compounds are insensitive when are thermally and hydrolytically stable
3. Their chemical compositions do not contaminate the air, expensive personal protective
gear and special equipment can now be avoided.
4. Since the production of these NHN does not generate any hazardous waste solvents,
their manufacture eliminates the costs of waste disposal. All of the waste is non-
hazardous aqueous waste that contains non-toxic salts.

We Claim:
1.
A process for preparing nickel hydrazine nitrate (NHN), for tubular detonators comprising the steps of:
a) dissolving 90 to 1 1 0 g of nickel nitrate in distilled water;
b) dissolving 45 to 55ml of hydrazine hydrate in distilled water;
c) mixing the solutions of step (a) and step (b) dropwise to distilled water with
constant stirring at a speed of atmost 40RPM for one hour at a temperature of 80
to 90°C and thereby obtaining precipitates of NHN;
d) washing the precipitates of step (c) with water and acetone followed by drying at
a temperature of 50-60°C for 1-2 hour to obtain NHN crystals;
having bulk density of 1.10 to 1.15g/cm3 and particle size of 110-130um and wherein the molar ratio of nickel nitrate to hydrazine hydrate is 1 :3.
2. A process as claimed in claim 1, wherein bulk density of NHN is 1.14 g/cm3'
3. A process as claimed in claim 1, wherein the particle size of NHN is 1 14 to 120
jam.
4. A process as claimed in claim 1 , wherein precipitates of step (c) are dried at a
temperature of 55°C for one hour.
5. A process as claimed in claim 1, wherein NHN is of free flow nature.
6. A process of preparing Nickel hydrazine nitrate substantially herein described
with reference to the forgoing examples and figures.