EXPLOSIONS IN MINES.

Sun (Christchurch), Volume I, Issue 195, 22 September 1914, Page 6

EXPLOSIONS IN MINES.

CAUSE OF THE HUNTLY DISASTER PROFESSOR H. R. DIXON'S VIEWS. T!;e popular idea regarding explosions in coal mines is that they are due to an accumulation of gas coming in contact with a naked light, and the popular idea is right, as far as the first cause of the explosion anyway. But the really disastrous clement, the true explosive, is coal dust, and' coal dust was the cause of the great disaster at Huntlv. Professor If. B. Dixon, F.R.S., Profesor of Chemistry at the University of Manchester, and one of the visiting men of science to the congress in Australia, is also one of the world's foremost authorities 011 the matter of coal mine explosions. He is in charge of an experimental station established in the north of England, for the purpose of observing the causes and effects of mine explosions under conditions such as would occur in mines. Therefore, the presence of such an expert in New Zealand was opportune, and the Government took propc-r advantage of it in engaging him to investigate the cause of the Huntly disaster. The Danger of Dust.-

Professor Dixon was interviewed by a SUN representative and asked not only his opinion of the Huntly disaster, but for some talk of causes of mine explosions generally. Professor Dixon > said there was ho doubt whatever that the explosion at. Huntly was due to coal dust; the question to answer was, What was the originating cause? He pointed out that it was always the main traffic drives of mines wherein coal dust was most, prevalent, for the reason that the greatest air current from the mainA-entilat-ing shaft passed through these drives along which .the coal trucks were hauled. Naturally, from 'the coal trucks, from the blasting and chopping, there was always a certain amount of dust in suspension in the passages where. the greatest volume of air penetrated. But coal dust is hot explosive in itself,' it : mtist be in suspension in the air to become inflammable, and it : must be >di»i turbed in - clouds and ~ be . ignited by flame before it can do any destruction. Ignition of Pire-Dampl;

Speaking of the Huntly disaster Professor Dixon said the most probable cause of/the primary explosion was the presence of fire-damp: Fire-damp is a gas, odourless and tasteless, which can be detected only by coming into contact with a naked...light, or by specially deS4sed- apparatus,- and the presence of fire-damp in small quantities had been found to be present occasionally in the Huntly mine. The gas is lighter than air arid, always rises to the top of the drive, and its presence is not easily detected. Professor Dixon pointed out that the explosion took place just about the time when the men wei r e going to their places ( preparatory ,to starting work, therefore it was not likely that •the pre!i 111 i h ary explosion and . flame could be due to. a charge, of explosive blowing out, "back-firing,." as it were, for ho charges would be set so easily. The overseers for the ' men had goue through the workings only a few minutes before the men cam; dow.n, and had reported all well, but it was possible that in making their inspection they had not noticed some escape of fire-damp, which, however, had exploded on\coming in contact with-a miner's naked light. The Huntly mine was considered a very safe mine, and the lamps used by the miners were not of the safety pattern but small acetylene Hares worn in the front of the cap.

The Cap and the Powder. Such an explosion would raise a cloud of dust, which the resultant flame would ignite, so causing a greater explosion, which would rush throughout the mine, and especially , along those passages where the coal dust was continually stirred in suspension. Another possible cause of flame such as would ignite coal dust was spontaneous combustion. This had also previously occurred in the Huiitly mine, and was due to soft, rubbishy coal igniting through heat generated in its own mass, but this was not nearly so frequent a cause of mine explosions as the cause of fire-damp, and Professor Dixon considered that fire-damp and .a naked light was the most probable .cause in the explosion discussed. Dampness a Safeguard.

There are. such things as "wet" and "dry" mines, coal mines, that is, wherein water is either present in the seams or is notj and a "wet" mine is much less liable to explosions of coal dust than a .''dry" mine, though in a "dry"-mi it 'is usual to take the precaution of spraying the workings with water. The Huntly mine was "dry".for the most part, with patches of dampness, and the professor was asked if these, damp spaces would not. provide some sort of safeguard against a continuous explosion of coal dust throughout, the mine. He replied that, unless they were of considerable extent they would not; it was only in cases where the workings were damp throughout that there could be an absence of coal dust suspended' in the air. A damp stretch of 50 or 60 yards, for instance, would be no obstacle to the effect of concussion and the volume of flame. The force of the prima I ,/explosion would raise clouds of coal dust in workings far beyond the intervening damp passage, and the burst of (lame would shoot across and ignite it. Firedamp and coal dust are the principal causes of disaster in coal mines, and for the first there is the expedient of spraying, but for the second there is no cure; it is one of the natural effects and disadvantages of coal-mining. There is some safeguard, though, in the use of safety lamps and of explosives which discharge without flame. Although the use of such explosives is compulsory in England tliey are not in common use here, and ordinary blasting powder was the explosive in use at Hunt Iv.