Pyrites explosive

Pyrites are likely to catalyse the explosive decomposition of hydrogen peroxide. 

Finely powdered pyrites, especially in presence of moisture, will rapidly heat spontaneously and ignite, particularly in contact with combustible materials [1]. Inert gas blanketing will prevent this [2], Precautions to reduce the self-ignition hazards of powdered pyrites, and the explosion hazards of pyrites-air mixtures in the furnaces of sulfuric acid plants have been detailed and discussed [3], Further studies on minimum moisture content of Portuguese pyrites for safe transportation and storage are reported [4],... 

In presence of sulfide ores, specifically pyrites, explosives containing ammonium nitrate may undergo runaway reaction, leading to detonation at temperatures below 40°C if pH is less than 2. The reaction is acid catalysed. 

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°... 

The lower explosive limit and minimum explosive concentrations of flax, wool, cotton, jute, hemp and sisal fibres are of the same order of magnitude as those of highly explosive dusts [15], The explosibility of pyrites dusts with sulfur contents above 20% was evaluated experimentally. Dusts of 30% sulfur content gave explosion pressures of 3 bar at pressure rise rates of 16 bar/sec. Mixtures of 60% pyrites and 40% powdered limestone still showed significant pressure effects, and the proportion of limestone actually needed to suppress explosions was considerably above the values currently accepted by mining industries [16], Effects of mixtures of particle sizes in combustible dusts upon minimum ignition temperature (T ") and upon presence or absence of explosion were studied. Presence of 30% of fines in a coarse dust lowers Tf significantly [17], Experimental explosions of polyethylene,... 

In a special publication devoted to sulfide ore dust explosions, a dust explosion in a copper-zinc sulfide mine is discussed and related to causes and preventive measures [1]. Control measures [2] and prevention of secondary explosions are also discussed [3], and surveyed, including the need for further work [4], The results of experimental work on the use of limestone dust to suppress explosions in pyrites dusts are presented [5], For another special publication on ore dust explosion with numerous incidents and further studies on mechanism and control see [6], Explosibility declines in the order pyrrotite, pyrite, chalcopyrite, sphalerite, covellite, chalcocite, galena. Pyrite at 1000 g/m3 can give a peak pressure of 5.8 bar [7], Self heating of broken sulfide ore, to possible ignition, has been studied. Pyrrhotite seems primarily responsible [8],... 

Bronstein s Explosives, Blasting expls which consisted of AN 82.2, sugar 9 iron pyrites 8.8% (Ref 1) and NaN03 30-40, NS 25-55 marble dust 5 45%(Ref 2)... 

The presence of carbon in pyrites lowers the ignition temperature to 228—42°C and increases the explosivity of dust suspensions in air. 

Harkonen, H., H.Nordman, O.Korhonen, and I.Winblad. 1983. Long-term effects of exposure to sulfur dioxide. Lung function four years after a pyrite dust explosion. Am. Rev. Respir. Dis. 128(5) 890-893. 

Magnex A process for removing mineral matter from coal by first rendering it magnetic. The coal is treated with iron carbonyl vapor, which deposits a thin skin of magnetic material on the pyrite and other mineral matter, but not on the coal. Conventional magnetic separation is then used. Developed by Hazen Research in 1976. Piloted but not commercialized, probably because of the explosion and toxicity hazards involved. 

It is more than likely that when sulfur occurs in a crude oil or in coal (other than the pyrites), it is organically bound in one of the three forms listed in Table 3—the thiols, sulfides, or disulfides. The combustion of these compounds is very much different from that of other sulfur compounds in that a laige portion of the fuel element is a pure hydrocarbon fragment. Thus in explosion or flame studies, the branched-chain reactions that determine the overall consumption rate or flame speed would follow those chains characteristic of hydrocarbon combustion rather than the CS, SO, and S radical chains which dominate in H2S, CS2, COS, and Sg combustion. 

Up to World War 1 most industrial countries experienced a rapid increase in the production of sulphuric acid. This was a basic input product for the manufacture of traditional industries (such as textiles, iron and steel), as well as the newer heavy chemicals (oil refining, artificial fertilisers, and explosives) and the emerging fine chemicals (such as synthetic dyes). The strongest reasons for the early rise of this industry in Spain are the abundance of raw materials (sea salt and pyrites) and the existence of a consumer industry (textiles). The development of the acid industry was, however, difficult and slow in the previous century. The story of the pioneer enterprise, Cros, founded by a native of southern France in the surroundings of Barcelona in the... 

Some materials that are otherwise quite stable can become potentially explosive as their particle size is reduced to the colloidal size range. For example, aluminium particles that are not explosive in air at particle sizes of about 1 mm can become weakly explosive at about 100 pm in size and very explosive at about 10 pm in size. The critical mass mean diameter for explosibility of pyrrhotite (Fe 2) and pyrite (FeS) has been reported to be 49-63 and 85-145 pm, respectively [48]. Similarly, particle size affects the ease of ignition of a metal particle when subjected to heat or an explosion. For example, the critical size for prompt ignition of spherical magnesium particles has been reported to be between 85 and 240 pm [49]. 

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