Drilling-and-blasting operations (DBO) are one of the most accessible and effective, and in a number of cases irreplaceable way of destructing rocks in mining and extracting minerals and conducting excavation. At present about 70% of blind workings are being conducted and 10% of coal is being mined with the help of these operations. However coal industry makes special requirements to the explosives. These requirements are dictated first by risk and danger of application of explosives in coal mines where the atmosphere often contains methane and breeze.
In 2005 year the enterprises of coal industry of Ukraine used up to about 8 thousand tons of explosives, from which there were used about 5 thousand tons of preventive explosives and about 8 million of electric detonators (ED).
In spite of advantages, blasting works (BW) have substantial disadvantage that is high danger of ignition of methane and air mixture and dust and air mixture. Last one can be illustrated by the following data, introduced in different specialized books and by data that have been gathered recently. Since 1980 to 2005 it happened more than 30 ignitions and explosion of methane and air mixture (MAM) in coal mines of Ukraine.
Energy that is emitted by some explosive in bore-holes is partly consumed by mechanical work. Unused part of energy proves to be sufficient to cause ignition and explosion of methane and air mixture or dust and air mixture in a mine.
Main causes of methane and air mixture ignition by blasting works are insufficient level of protection and stability against burning down safety explosives. There are also such causes as detonate blast-hole charge – 37%, burning down charge – 29%, laid on charge – 29%, destruction of blasting materials in a face – 5%.
One of the most important measures to ensure safety works in coal mines which are gas and dust dangerous is application of special explosives (such explosives are called safety explosives), as well as means and ways of out bursting that diminish probability of ignition of mine atmosphere.
In past years it has been conducted sufficient work aimed at the rise of safety and effectiveness of blasting works. In particular it has been developed and introduced high safety explosives belonging to V and VI classes which features by steady to burning down – 13Ď, 13Ď/1 and 10Ď it has also been worked out safety IV class explosive steady to burning down – ammonite Ô-5.
Primary reasons that provoke ignition of methane and air mixture by blasting works can be air percussive wave, burning hot scorching or burning hard particles and high temperature gases. Explosive’s composition, detonation velocity, presence of ignition delay catalysts (flash extinguisher), energy of explosives, conditions of explosion and a number of other factors also influence on ignition of mine atmosphere. So detailed study of factors, that influence on the level of safety properties of industrial explosives, is necessary for the development of new explosives, which would meet a number of requirements which are necessary for industrial safety explosives. One of such factors is detonation velocity.
Aim of work is the study the influence of detonation velocity on safety level of explosives. In connection with this aim some problems is necessary to realize arise, namely:
~ to conduct tests of explosives on safety in gas and dust dangerous conditions: in a channel mortar and a corner mortar to ascertain m50 or mlmt by the gas and dust tests of III – VII class explosives;
~ to ascertain empirical dependence of mlmt and m50 on detonation velocity which will allow to conduct preliminary assessment of safety properties of explosives in the methane and air mixture.
The study of the influence of detonation velocity on safety properties level of industrial explosives will allow to determine analytical dependence of safety properties of industrial explosives on detonation velocity, and this in it’s turn will allow to conduct preliminary assessment of safety properties of investigating explosives by explosion in the methane and air mixture before carrying out dear tests in experimental drift that will demand time expenditure. Analytical dependence will let one optimum explosive composition by working up a new explosive.
The work that has been done will allow to specify the known thesis about the influence of detonation velocity on ability of explosives to burn methane and air or dust and air mixtures by explosion in dangerous environment that is to specify the influence of detonation velocity on safety properties of explosives.
A number of undecided problems and questions:
1. There is a need to create new explosives, because existing once do not satisfy productions by many factors including ecological safety.
2. Mathematic dependence of influence of detonation velocity on explosive burning faculty in different conditions isn’t determined.
3. The problem of capacity rise of safety explosives with preservation of safety properties level of explosives isn’t decided. And this capacity rise of safety explosives with preservation of safety properties level is possible when one knows the dependence of m50=f(D).
Nowadays relating to references analytical dependence are known that have been treated and derived by different science. Those analytical dependences don’t completely reflect the influence of detonation velocity on the level of safety properties of explosives. If the work results in determining a clear and distinct dependence it will give possibility to develop high safety powerful explosives.