Explosives blasting

Air blast, explosion, or earthquake. Nearby unbalanced macliinery. Blows, impact. Present in all rotating machinery. 

Concerned mainly with the security of explosives and restncted substances. Applicable to the acquisition, keeping, handling and control of explosives, e.g. blasting explosives, detonators, fuses, ammunitions, propellants, pyrotechnics and fireworks. 

Military Blasting Explosives and Military Demolition Explosives. See under Demolition Explosives, Vol 3, D56-R to D61 -L... 

Mining Explosives. See under COMMERCIAL OR INDUSTRIAL EXPLOSIVES in Vol 3, pp C434-R to 406-L, and BLASTING EXPLOSIVES in Vol 2, pp B202-L to 211-R in this Encycl... 

See also under Blasting Explosives in Vol 2, B202-L to B211-R... 

Oil-Explosive Combinations. See under Slurry Explosives in Vol 6, E469-R, and under Ammonium Nitrate Blasting Explosives in Vol 1, A341ff... 

Barnhart, R.E. and Sawyer, F.C. "Gelled Ammonium Nitrate Blasting Explosive and Process," US Patent 3,072,509(1963). 

In the 1950 s a sudden and dramatic change affected the explosives industry in many parts of the world. This was the introduction in the U.S.A., Sweden and Canada of ammonium nitrate sensitised with fuel oil as a major blasting explosive. A slower but also important change started in the 1960 s with the development of slurry explosives in the U.S.A., Canada and other countries. 

The above represent accessories which do not directly perform blasting operations, but which are essential for the efficient and safe use of blasting explosives. For the explosives industry and for the user they are as important as the blasting explosives themselves. 

Use of a narrower diameter tube. This leads to a longer length of base charge which in general is more effective in initiating blasting explosives. 

Delay detonators for use in coal mines must be constructed so as not to ignite methane/air mixtures even if iired accidentally outside a cartridge of a blasting explosive. This requires a suitable selection of fusehead and the provision of the delay element in a form which will not produce large particles of hot slag on burning. In the British design the delay elements are... 

Further properties which a detonating fuse should have are the ability to initiate blasting explosives (tested with suitable relatively insensitive mixtures usually of TNT and ammonium nitrate) resistance to low temperatures without cracking on flexing and to hot storage without desensitisation and toughness to prevent damage from stones, etc. The fuse must always be waterproof and must often withstand diesel oil, which can separate from ANFO. 

Gunpowder was first employed as a propellent explosive in guns, although later it was also employed for blasting. In neither case, however, does it detonate in the same way as the blasting explosives described in Part I, or the initiating explosives described in Part II of this book. 

According to an O.S. amendment sheet, the procedure as described [1] is dangerous because the reaction mixture (dicyanodiamide and ammonium nitrate) is similar in composition to commercial blasting explosives. This probably also applies to similar earlier preparations [2]. An earlier procedure which involved heating ammonium thiocyanate, lead nitrate and ammonia demolished a 50 bar autoclave [3], TGA and DTA studies show that air is not involved in the thermal decomposition [4], Explosive properties of the nitrate are detailed [5], An improved process involves catalytic conversion at 90-200°C of a molten mixture of urea and ammonium nitrate to give 92% conversion (on urea) of guanidinium nitrate, recovered by crystallisation. Hazards of alternative processes are listed [6],... 

A mixture containing 51% of calcium nitrate and 12% ammonium nitrate with 27% formamide and 10% water is detonable at —20°C [1]. Addition of aluminium powder improves performance as a blasting explosive [2],... 

The main factors leading to spontaneous explosions of blasting explosives in sulfide ore mines are identified as presence of ammonium nitrate, presence of pyrites and their weathering products, as well as the pH and temperature. At pH below 2, the critical temperature for spontaneous explosion may be lower than 40°... 

MSER covers the manufacture, storage and handling of all explosives (e.g. ammunition and blasting explosives) and there is specific reference to fireworks, fusing fireworks and assembling fireworks displays from components. 

If an atmosphere contg a combustible dust above lower limit is not completely confined, if might only burn when ignited by means of a flame or an electric spark, but it will detonate if in complete (or even pattial) confinement, especially if initiated by a detonator, primer, etc or when initiated by a blasting explosive such as takes place during mining operations... 

Other commercial expls described in our Encycl include Agriculture and Forestry Explosives (Vol 1, p A112-R) (Ref 8), Ammonium Nitrate Blasting Explosives (Vol 1, p A341) and Ammonium Nitrate Dynamites (Vol 1, p A335)... 

See Vol 3 of Encycl, p D38-R) and the energy liberated is called the beat of deflagration. Some other explosives (such as blasting explosives, or even high explo-... 

---