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Section 5. Chemistry
Mamedov Elnur Shamhal, leading researcher, Azerbaijan National Academy of Sciences, Institute of Catalysis and Inorganic Chemistry named after acad. M. Nagiyev, Baku, Azerbaijan,
Veliyeva Dilara Safar, leading researcher, Azerbaijan National Academy of Sciences, Institute of Catalysis and Inorganic Chemistry named after M. Nagiyev, Baku, Azerbaijan, Kulibekova Tamilla Nasraddin, researcher,
Azerbaijan National Academy of Sciences, Institute of Catalysis and Inorganic Chemistry named after acad. M. Nagiyev, Baku, Azerbaijan,
Mamedov Anar Elnur, leading researcher, Azerbaijan National Academy of Sciences, Institute of Control Systems, Baku, Azerbaijan, Aliyeva Fidan Maharram, leading researcher, Azerbaijan National Academy of Sciences, Institute of Catalysis and Inorganic Chemistry named after acad. M. Nagiyev, Baku, Azerbaijan,
E-mail: namsa@science.az
UTILIZATION OF ROCKET FUEL OXIDIZERS BASED ON NITRIC ACIDS
Abstract: Continuous emission sources of ecological condition of the planet together with industrial wastes are both non-standard rocket fuels and their oxidizers. In this connection the task of utilizing non-liquid components of missile fuels is vitally important, relevant and requires rapid solution. The paper offers processing method of oxidizer into the technical and industrial goods. Keywords: missile fuel oxidizer, utilization, nitric acid, nitrogen tetraoxide.
In the world the situation has developed in such a way that scientists began paying much special attention to the processes which negatively influence on the environment. It is obvious that industrial wastes are a constant source of pollution of an ecological condition of the planet.
These wastes, for example chemical wastes, can be valuable raw materials for producing various chemicals to recycle them in industry.
For the last decades in Germany essential changes have occurred in the management ofwastes: country passed a way from simple burial to processing and reasonable use of secondary resources. Recycling process is any way of utilization in which materials of wastes are subjected to the processing that makes products, materials or chemicals suitable for their utilization. Germany is a pioneer in the field of a recycling of wastes both in Europe, and beyond its boundaries. There is hardly any other country where so many raw materials are produced from wastes, as it is done in Germany. German recycling technologies are leaders all over the the world.
Therefore the first stage of development of a recycling system in Germany is related to the creation of the Federal Union of German industry on waste management in the beginning of 1960s.
One of the examples of negative impact on ecology is the storage of sub-standard missile fuels.
In the territory of the Commonwealth of Independent States including Azerbaijan a large number of various components of missile fuel which are not used since the former Soviet Union are concentrated. After the breakup of the Soviet Union many military bases were faced the fact of various toxic components of missile fuel which after many years and the expiration of storage time represent a serious threat to the environment and the population in settlements. In this regard the problem of elimination and utilization of accumulated components of missile fuel is vital and very relevant, requiring the solution at the international level.
As it is known two-component fuels (TG-02, TM-185, etc.) were used in liquid rocket engines (LME) with nitrate oxidizers under the technical name "Melange". These oxidizers were developed in the middle of the last century.
Now the storage of all these components results in the risk of violation of an ecological condition in certain regions. Therefore the high-priority problem is to start the elimination dangerous unsuitable components of rocket fuel for the environment and mankind as soon as possible without waiting for an ecological disaster.
Nitrate oxidizers is the category of components of liquid rocket fuel applied in military missiles, space carrier - vehicles, etc. where the use of liquid oxygen is impossible or inexpedient due to its evaporation.
These oxidizers contain concentrated nitric acid, and corrosion inhibitors added to decrease corrosion effect of an oxidizer on communications and the equipment of the rocket engine as well as tanks in which oxidizers are stored.
Physical properties of these oxidizers are defined by content of nitrogen oxides and water in them. Main properties: from light yellow to brown; density at 15.6 °С 1.511-1.575 г/см3; temperature of boiling 66-86 °С.
The mixture of HNO3:N2O4H2O is a strong oxidizer and therefore the interaction with the vast majority of combustible substances leads to spontaneous ignition.
Notwithstanding that nitric acid and oxidizers on its basis are corrosion active agents, some metals interact with it very poorly. Among these are aluminum and its alloys nickel-chromium alloyed steels, cast iron and ferro-salicyl alloys. Due to the corrosion of metal of tanks and technical means under long-term contact with an oxidizer the composition of an oxidizer changes, it is polluted with salts and technical means are destroyed.
Effective means of reducing corrosion dissolution rate of metals is the use of corrosion inhibitors,
the most effective of which is iodine - and fluorinated inhibitors in an amount of 0.4 - 0.5%.
The estimated composition of some oxidizers of rocket fuels is given below:
AK-20I: 80% HNO3, 20% N2O4, iodine-containing inhibitor
Table 1. - Oxidizers on the basis of nitric acid
AK-27I: 73% HNO3, 27% N2O4, iodine-containing inhibitor
AK-27P: 73% HNO3, 27% N2O4, fluorine-containing inhibitor
Parameters Oxidizer
AK - 20I AK - 27I AK - 27P
Weight percent of nitrogen oxides (N2O4),% 17.5 - 22.5 24.0 - 28.0 26.7 - 28.0
Weight percent of water,% 3.3 - 4.3 1.3 - 2.0 1.3 - 1.6
Weight percent of iodine,% up to 0.04 0.12 - 0.16 -
Weight percent of hydrogen fluoride (HF),% - - 0.3 - 0.55
Weight percent of ortho-phosphoric acid (H^V/o - - 0.05 - 0.13
Weight percent of dissolved aluminum salts (AL,Oj,% 0.04 - -
Weight percent of nitric acid,%, not less than 72.9 69.8-70.2 69.5
Weight percent of mechanical mixtures,%, not more than 0.01 0.01 0.01
Weight percent of phosphate ion, %, not more than - - 0.002
Density at 20 0C, g/sm3 1.587 - 1.604 1.603 - 1.616 1.606 - 1.611
Two directions of utilization of melange are generally used.
- Destruction (burning). For economic and ecological reasons this method cannot be realized commercially.
- Processing of oxidizer to technical and industrial goods. This method of utilization opens the possibilities for production directed to the agricultural application.
Considering high toxicity of nitrogen-containing oxidizers of a rocket fuel Azerbaijan finished the destruction of reserves of rocket fuel oxidizers which remained in the territory of the state since the Soviet Union by the program of NATO "Science for the world and safety".
About 1,3 thousand tons of "Melange" were processed using the chemical process which did not do any harm to the environment in Azerbaijan.
If consider that "Melange" generally consists of concentrated nitric acid and nitrogen tetroxide the
neutralization process of oxidizers proceeds according to the scheme:
N2O4 + H2O HNO2 + HNO3 The assigned task is solved by processing it to diluted nitric acid. Melange is dosed in water at 0-50C. The process proceeds smoothly in dosage of an oxidizer in water. This is due to the fact that water in this case is not only a reagent, but also a solvent, i.e. interaction process of nitrogen tetroxide with water, absorption by water and formed nitric and nitric acids proceeds in the diluted solutions.
Nitric acid externally represents the colourless transparent liquid without mechanical impurities which does not smoke in an open air. Changing molar ratio of mélange: water (1-10) and temperature (0-15 0C) we defined:
- running of the process at higher temperatures (above 5 0) decreases the yield of a target product to 92% against 96%.
- running of the process at a mass ratio of N2O4 H2O exceeding 1:5 is undesirable since it leads to the production of diluted acid.
Further solution of calcium nitrate "Norwegian saltpeter" which can be used as mineral feed is produced by the reaction of extracted nitric acid with calcium carbonate (there is enough calcium carbonate in the territory of the country) to perform the assigned task aqueous:
2HNO3 + CaC03Ca(N03)2 + C02 + H2O 2HN02 + CaC03Ca(NO2)2 + C02 + 2H2
2HF + CaC03CaF2 + CO2 + H20 The mobile processing plant which was constructed within the joint project of the government
ofAzerbaijan with NATO was used for implementation of these works.
The project was developed and was performed by the Ministry of Defence of the Republic ofAzerbaijan and Azerbaijan National Academy of Sciences. The Azerbaijani in turn provided necessary infrastructures and materials for implementation of the project.
The similar utilization technology of rocket fuel oxidizers was further used in other country which faced a similar problem. Specifically in Uzbekistan where about 1,1 thousand tons of "Melange" were destroyed.
References:
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2. Liquid rocket fuel in the territory of Organization for Security and Co-operation in Europe: review of utilization aspects. FSC.DEL/443/07/Rev.2. Russian 23.10.2008
3. Method ofprocessing mélange-oxidiser ofrocket fuel: Patent Ukraine № 67466. Application 03.10.2003; published. 15.09.2005, ewa. No. 9.
4. Karpovich E. A., Vakal S. V., Zolotaryov A. E., Drobat A. G. Creation ofpilot plant for utilization of substandard rocket fuel oxidizer. / Ecology and human health. Air-pollution control.
5. Development of primary data on projection of utilization installation utilization of rocket fuel oxidizer (melange) by processing to mineral fertilizer with production of 1 ton of mélange per hour: report of Sumy Research State Institute of Mineral Fertilizers and Pigments,- 2009.
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