Aspects to be Contemplated in the development process of Explosive Formulations
INTRODUCTION:
Formulations in vogue and age-old are like corporate monuments and deep-rooted protocols. They are difficult to be fine-tuned, amended, or replaced. Any long practice in place, for example, to take written approval to avail a casual leave in writing, is like a sanctity in the administrative process. Someone who tries to take approval in verbal form is looked down on as a maverick. In explosive manufacturing one can imagine the challenges one has to go through to make fine-tuning, forget establishing a new formulation in place. Many good products in the name of safety (?) fail to see the lights of the day. It is worth discussing some small but important case studies.
SAFETY PARAMETERS:
Safety, without exception, is the prime parameter that needs consideration in the development of new explosive formulations. MSDS of input, semi-finished, and finished products need addressing in the first step. Next would come to the thermodynamic parameters like melting point, boiling point, vapor pressure, heavy atom count, formal charge, covalently bonded unit count, physical form, odour, solubility, density, vapour density, vapour pressure, stability, shelf life, autoignition temperature, decomposition, viscosity, corrosivity, heat of vaporization, pH, surface tension, ionization potential, dissociation constants, heat of fusion, health hazards, environmental hazards, disposal methods, accidental release measures, hazard identification and analysis, aspect impact analysis, FDA aspects, agrochemical information, pharmacology and biochemistry, absorption, distribution and excretion, metabolism, metabolites, biochemical reactions, use and manufacturing, use classifications, industry uses, consumer uses, household products, methods of manufacturing, consumption patterns, general manufacturing information, analytic laboratory methods, clinical laboratory methods, OSHA chemical sampling, safety and hazards, hazard classes and categories, substance of very high concern, health hazards, fire hazards, fire potential, flammable limits, critical temperature and pressure, explosives limit and potential, first aid measures, firefighting, firefighting procedures, accidental release measures, spillage disposal, cleaning methods, disposal methods, preventive measures, handling and storage, non-fire spill response, safe storage, recommended exposure limit, permissible exposure limit, immediately dangerous to life or health, threshold limit values, allowable tolerances, personal protective equipment, respirator recommendations, fire prevention, exposure prevention, stability and reactivity, reactivity profile, hazardous reactivities and compatibilities, transport information, shipping methods and regulations, and many more.
QUALITY PARAMETERS:
The very purpose of making an industrial explosive is to generate enough energy to break the rock. Thus, the prime quality parameter is – the energy content. Energies of two types are important, viz. heat energy and gas energy. Gas energy becomes most effective in the presence of the high-heat-energy. The other thermodynamic parameters important are oxygen factor of materials, oxygen balance of the combination of materials, the heat of formation, activation energy needed to decompose the oxidizers, fuels that can quickly use the oxygen generated by the decomposition of the oxidizers, free energy (Gibbs free energy), the density of the final product, the form (gel or emulsion) of the final product, and the moles of oxygen generated from the decomposition of the oxidizers. Additionally, the final product should be safe in terms of friction, spark, static energy, and laser energy. It should withstand the borehole temperature for about 24 hours. High temperature inside the borehole should not initiate the explosive before it is ignited.
ORNAMENTAL QUALITY PARAMETERS:
Parameters like waterproofness are important for bulk explosives, that is explosives without an outer package. Examples are site mix emulsion, site mix slurry, and ANFO. Waterproofness is an ornamental parameter for packaged explosives. Fall hammer test is another test that is ornamental for class 2 slurry and emulsion explosives. The bullet fire test is one more ornamental test.
DEVELOPMENT OF NEW FORMULATION BY KEEPING EYES ON DIFFERENT PARAMETERS:
There are standards in the Indian context to clear safety and quality parameters for explosives and accessories. These are available in different standards like
1. IS 6609: Part 1: 1972 | (Reaffirmed Year: 2021) | Methods of test for commercial blasting explosives and accessories: Part I Gun powder
2. IS 6609: Part 2: Sec 1: 1973 | (Reaffirmed Year: 2021) | Methods of test for commercial blasting explosives and accessories: Part II Explosives Section 1 Explosives, general
3. IS 6609: Part 2: Sec 2: 1974 | (Reaffirmed Year: 2021) | Methods of test for commercial blasting explosives and accessories: Part II Explosives Section 2 Explosives, permitted
4. IS 6609: Part 2: Sec 3: 1980 | (Reaffirmed Year: 2021) | Methods of test for commercial blasting explosives and accessories: Part II Explosives Section 3 Explosives, slurry
5. IS 6609: Part 3: 1973 | (Reaffirmed Year: 2019) | Methods of test for commercial blasting explosives and accessories: Part III Detonators, general and permitted
6. IS 6609: Part 4: 2020 | Methods of test for commercial blasting explosives and accessories: Part IV Detonating fuses
7. IS 6609: Part 5: 1972 | (Reaffirmed Year: 2021) | Methods of test for commercial blasting explosives and accessories: Part V Safety fuses
These standards amply define the safety and quality parameters that explosives and accessories should meet for the users to use products with safety and to obtain desired results. That means these standards are good guides in the manufacture of an effective explosive product for use in mining and excavation. There are other consolidated parameters too to make effective explosives for rock blasting. One such set of parameters is defined by the GPeng Model developed by the present author. According to the GPeng, the parameters are:
A new product necessarily has to pass all the tests mentioned in the BIS 6609 standards, and additionally be reinforced with the passing of the parameters mentioned in the GPeng Model. The sequence also has to be followed as the parameters are appearing both in the BIS 6609 and GPeng standards. Random tests by skipping parameters will only add to the confusion.
ONE CASE STUDY:
One, like all of the explosive manufacturing organizations in India, is facing challenges arising out of (i) high cost-plus scarce availability of ammonium nitrate, (ii) rising cost of fuels like hydrocarbon oils, (iii) other fuels like carbohydrates, polysaccharides, sulfur, and (iv) sensitizers like micro balloons and aluminum powder. The management wanted to work on possible aspects to reduce cost without hampering the quality of final products. To begin with, some formulations were suggested for trial on the laboratory scale. The chemists in the laboratory tried out the new formulations and tested the products with respect to (a) VOD, and (b) 24-hour waterproofness. The formulation was rejected. Reason – it did not pass the waterproofness test. No other tests were carried out. This (reporting of failure) happened for many different formulations. In the BIS 6609 standard, the waterproofness test comes as the 10th test, in sequence. There are other tests like Trauzl lead Block expansion, energy content, etc. These tests were ignored. The result – the organization is still producing formulations high in ammonium nitrate that is scarce, and of high cost. The endeavor of the present author is still on to convince their technical as well as the administration teams that – the factors that need monitoring should be (a) oxygen balance, (b) heat of formation, (c) gas energy, (d) density at which is detonable, and NOT (e) VOD and waterproofness tests.
It is not the purpose of this article to do deliberate on the “ignorance of the organization” but to bring in a couple of relevant points that may help it to achieve its objectives of achieving – a good quality product at the most competitive cost.