Stone Dust.

[John]

What was it supposed to be for??

A bag made a good pillow, as teens underground stonedust fights were great. Made the roadways look bright, my overalls always looked sparkling white..

What was it supposed to be for..... ;D

[amanda]

Yes bags of stonedust made a decent pillow, but nothing beat a nice roll of Bondena for a materess


Stonedust was meant to dilute down any coal dust, take away it's exsplosive qualities


mand

Thats what it was used for A load of bags of it made good beds though.

Then along came large bulk stonedusting machunes and spoilt our fun on nightshifts..


Thats true Amanda, some pits changed from stone dust on barriers to water barriers, usually wet mines. It was still used to dust down on and near faces though, where it changed to an oozy sticky mess...

[John]

Whoops, don't know how that happened, I must have hit the modify button instead of the Quote button, sorry about that..

[amanda]

To be honest I've never heard of "stonedusting machines", but then again I worked at Moorgreen pit from the mid 70's and then when that closed I did about 5 years at Gedling pit. Neither of them was very technical advanced if you know what I mean

I remember how the gaffer's used to get into a "bit of a flap" when they knew an inspector was coming and they used to knock off all the jobs and have us all going round stonedusting everything in sight

Oh, if you're wondering about my name, I have to admit I wasn't known as Amanda then


mand

[John]

To be honest, I'd never seen a dusting machine until I worked down under. They have large rail mounted units that hook behind the locos. They start inbye end of rails on Sundays when the pit is empty and work their way outbye, creating a huge fog of stonedust! It permiates the faces and even gets into the return roads!

They did have smaller stonedusting machines to do the bords on the faces though. Much more efficient than hand dusting.

We used to have silos outside where the bulk dust was held until required.

Method of choice at old Clifton, south of the city Of Nottingham was the supply lads having a stone dust fight.. ;D

[Ragger]

I was lost. But now I have found the way.

Stonedust.

The danger from explosions is ever present in coal mines. The ignition of naturally occurring methane gas is serious enough, but if this propagated a coal dust explosion then the consequences could be devastating throughout the mine. To help reduce the risk of this happening stone dust was introduced, the idea being that it would provide a concentration of suspended dust particles in the path of the flame of an explosion, it was hoped that this would reduce temperatures and arrest the explosion.

Stone dust barriers were positioned at various points in roadways for this purpose. A simple wooden construction upon which stone dust was placed. In the event of an explosion these barriers would tip over and the stone dust dispersed. But another method of "stone dusting" was to actually spread the dust by hand. Bags full of stone dust would be positioned along the length of a roadway (tunnel), then a team of men were sent to scatter the contents. Simple enough, but you had to consider the direction of the airflow. Imagine throwing a hand full of flour in the air on a windy day the flour would soon be dispersed by the wind.

The same thing happened in the pit and men who worked on the down wind side were going to be dusted as well as the roadway. Self positioning was important, but each worker thought the same, nobody wanted to be covered in stone dust (some hope). ;D ;D ;D

The job had to be done (often just before the Mines Inspector was paying a visit). Someone would start throwing the dust about and "unintentionally", (maybe), dusted the others as well. The rest joined in throwing the stone dust about the roadway, roof, sides, and floor. "Accidentally" covering the the others and making sure the first man did not feel neglected or left out.

Mostly the operation was carried out in a happy go lucky way with each having their laugh periods (when not on the receiving end). When the job was completed the team would leave the roadway before the Inspector arrived.

Stonedusting had the effect of brightening up a roadway which was usually black, making it much easier to see. It had the same effect on the men who did the stone dusting. No other miner needed to ask them what they had been doing that shift. The evidence was there before their eyes they stood out like a snowman in front of a blackboard.

Stonedusting as mentioned above was an essential ingredient in the coal mining process (at times it was neglected ), and the method of distribution was not always in the manner described here.


Just as an after-thought. An explosion could occur through coaldust alone, without the presence of methane.


Regards,

The lost soul returns.

[John]

I remember a few of those stone dust battles Bill!! How you doing old mate, glad you dropped by!

[Ragger]

Hi. John,

Apart from the usual aches and pains we all suffer from after a few decades in the pits I'm OK.

I expect you've finished all that building work by now? Just living off the fruits of the land.

Gan canny bonny lad.


Bill.

[John]

ragger said:

Hi. John,

Apart from the usual aches and pains we all suffer from after a few decades in the pits I'm OK.

I expect you've finished all that building work by now? Just living off the fruits of the land.

Gan canny bonny lad.


Bill.

I wished I could say that was so Bill, been pretty ill since last September, Lyme disease mate. Still unable to do a lot of things I used to be able to do.

[Ragger]

Sorry to hear that John,

If you lived a bit nearer we could have rounded up a gang of market men to give you a dig out.

[John]

I'm starting to get back into things Bill, but I'm still having trouble with my knees arms, shoulders and hands. I came pretty close to throwing the towel in, I was in constant pain 24 hours a day and it hard just about wore me down. It's a pretty nasty disease that even has the medical profession just about stumped, and it's in epidemic proportions worldwide Bill.

[plantfit]

Ayup John,

Probably a stupid question but what type of stone was Stone dust made from,

Rog

[John]

Limestone Roger, ground to almost talcum powder texture. They call it rock dust in the USA.

[plantfit]

Ayup John,

As part of my confined spaces training and because we have limestone quarries within the group we were told that when lime stone gets wet it gives off carbon dioxide gas, did this have any effect underground or was the pits dry?

Rog

[John]

Far from it Roger, most pits had some water. I don't think the small amount of CO2 would be an issue as most pits had good ventilation, besides, the coal itself releases CO2 through oxidisation.
In fact we had a "gas" called Blackdamp, not really a gas as such, but absense of oxygen, usually CO2 and N in large quantities escaping from old workings and very badly ventilated roadways.


Our resident Deputy/Safety Officer, "Ragger" will probably comment further on that one, more down his alley than a tired pit electrician like me..

[limey]

As John said - Blackdamp is a mixture of CO2 and Nitrogen. If my understanding is correct, the suffix "damp" is derived from the German "dampf" which means gas and the reason it was "black" was because it put out the flame on a safety lamp!

Similarly, methane was "firedamp" - self explanatory (when you see it go up the bonnet of a safety lamp it gives you pause for thought!) and carbon monoxide was "whitedamp" because it made the lamp flame burn white.

[plantfit]

Ayup all,

Thanks for the replies, Certainly learned from asking the question,
Just goes to show John, if you want to know owt, ask the man thats done the job. much appreciated

Rog

[John]

We have plenty of experts Roger, Ragger was a Deputy, Daz was a fitter and myself an electrician, I know we have a surveyor, plus I'll bet we have other folks who worked underground who read the posts and would have jumped in.

[Ragger]

Hi. all.

For a while I was a Section 10 offical. (read all reports produced at the pit, including the surface, and produced a written report for the pit manager).

I came across some of my old notes, which may interest you all, or not as the case may be.

If there's any mistakes I'm sure someone will put me right.

Gases.

Fresh Air.

20.93% Oxygen
79.04% Nitrogen (includes 0.94% argon + other 0.01%).
0.03% Carbon Dioxide.

Flammable gases.

A) Firedamp (methane).
B) Carbon Monoxide.
C) Hydrogen.

B + C are produced in the thermal decomposition of, coal, wood, rubber, etc.

Hydrogen is also given off during both charging and discharging of electric storage batteries.

Toxic gases.

A) Carbon monoxide.
B) Oxides of nitrogen.

A, produced by oxidation of coal, exhausts from diesel engines, fumes from shotfiring.
B, produced by exhausts from diesel engines, shotfiring fumes.

Other toxic gases.

Chlorine, hydrogen, chloride, hydrogen, cyanide, phosgene.
May be produced by decomposition, by heat of synthetic material such as PVC belting.

Sulphur dioxide. From shotfiring fumes, and exhausts from diesels engines.

Hydrogen sulphide.
May arise from the action of acidic mine waters on naturally occurring pyrites and the results of bacterial action on sulphates.

Ammonia occurs from fumes of some explosives and from reaction of alkaline whitewash on timber impregnated with fire retardant salts.
Suffocating gases.

a) Methane.
b) Carbon dioxide.
c) Nitrogen.

Are not poisonous in themselves but if they occur in sufficient quantity, will reduce oxygen content to a dangerous level.

High methane emission involves risks of both explosion and suffocation.

Nitrogen and carbon dioxide are given off by coal strata, but serious emissions are rarely experienced in Great Britain.

Oxygen deficient atmospheres nearly always arise as a result of the slow oxidation of coal. But dangerous conditions will only occur in confined spaces or where the ventilation is markedly inadequate.

In such cases layering of methane in the roof and carbon dioxide on the floor may occur.

[John]

Looks pretty accurate to me Bill.

[aardvark]

Had a lad on underground training with us at Grimethorpe who used to do martial arts he told us he could do press ups with a bag of stonedust on his back so he got down and someone put a bag on his shoulders and he did a press up someone said can you do it with more he said i'll try so we put one more on more of a struggle but he did it he couldn't when we piled about ten on could hardley breathe either come to think of it

[aardvark]

admin said:

What was it supposed to be for??

A bag made a good pillow, as teens underground stonedust fights were great. Made the roadways look bright, my overalls always looked sparkling white..

What was it supposed to be for..... ;D

I remember once at Barnsley Main we were sitting in the FSV garage underground me and my mate had been changing a burst pipe outbye and had stopped for a chinwag somebody had fetched a stuffed toy to fasten to the front of the FSV similar to what you see on the front of dustbin wagons(round barnsley anyway) somebody had the idea of taking the stuffing out and filling it with stone dust and setting a booby trap so we got some rope and hung up the tortoise and wedged a piece of wood attatched to the toy in the air door and sat and waited ,we heard the first door open then the last air door opened and we just had time to see an oil lamp before the tortoise swung down and hit the overman in the chest he disappeared in a cloud of dust and we just dissappeared

[inbye]

I never saw a stonedust "machine" as such. The nearest we got, at Park mill was a device that looked like it might have been made in the fitting shops. It was a simple hopper which would take one bag at a time, it was connected to the compressed air main & the operator simply squirted it all round the roadway. Did the job.

Thing I could never understand..........there was always a lot of emphasis on keeping dust properly suppressed, but stonedusting took place in the intake on the dayshift? Not sure how that worked?

[dazbt]

Jul 13, 2008 14:18:45 GMT -5 inbye said:

I never saw a stonedust "machine" as such. The nearest we got, at Park mill was a device that looked like it might have been made in the fitting shops. It was a simple hopper which would take one bag at a time, it was connected to the compressed air main & the operator simply squirted it all round the roadway. Did the job.

Thing I could never understand..........there was always a lot of emphasis on keeping dust properly suppressed, but stonedusting took place in the intake on the dayshift? Not sure how that worked?

The propaganda at the time was that stone dust (Dolomite limestone) was non injurious and its particle size was calculated as being breathable without causing harm to humans ......... err, personally I would rather have carried it than breathe it.

[John]

We had stonedust machines of various sizes when I worked in NSW pits. Outside on the surface was a huge bin full of stonedust. Never saw bags of the stuff like we had in UK pits though.
Both the pits I worked in downunder had a huge railmounted stonedusting machine, it was hooked up to the diesel loco and air line from the loco. They used to start inbye on a Saturday and work out bye stonedusting the roads. Its amazing how far that stuff goes when thrown into the air by those machines!
Other roads used to be done with a stonedusting machine in the bucket of an LHD and a bloke with a two inch hose spraying the stuff out, again hooked to an air line.

[erichall]

Regarding stonedust machines, I always carried, as a shotfirer, 40 in my det bag. A couple of dets together placed inside a well positioned stonedust bag used to disperse the dust very quickly when exploded.
With regard to the gases and coaldust, methane would only explode within a given range - 5-15% I believe- but it would stir up and probably ignite the coal dust lying around. This made a much more serious explosion.
Whilst care had to be taken to reduce concentrations of methane., the gas that was the real killer was After- or White damp - Carbon Monoxide. Anyone who has ever de-clinkered a coke oven whilst it was burning will know of the effects of this. A feeeling of tightness in the chest, and difficulty breathing meant th operative should get into fresh air very quickly. This was the gas which rescue teams used Canaries for. The canary showed many of the same symptoms as a human, except much quicker. CO would be the after effect of an underground fire or explosion, and in its presence the canary would fall off its perch. this was the sign to don BA and get out quickly.

[Sam from Kent]

We had the compressed air type of "home made" stonedust "machine" if you could call it that at Tilmanstone. It was an inverted pyramid with an open top and a spout and was connected up to a compressed air hose. Didn't see it used. I always found the stonedust bags a bit hard as pillows, but bags of stemming gel were ideal. We also used to spray Calcium Carbonate (?) which was meant to "consolidate" the coal dust. Anyone spreading this wore little clothes and would have been horrified to read the manufacturer's safety precautions on the packaging. After spreading they were red raw and hosed down with the fire hose

[John]

Stone dust machines were common in NSW pits, we had the small ones used in districts and a large rail mounted one used at the weekends to stonedust the main roads. Good job it did too!!

Regarding chemicals, when I was at Wongawilli, just south of Wollongong in NSW, it was a damp to wet pit, so used water barriers spread around the pit.
Now the dust was wet, so it would stand no chance to propagate into a coal dust explosion, but instead of sanity prevailing, the law required some consolidating agent being used. Can't for the life of me remember what it was, but I'd hazard a guess it was calcium carbonate.

Miss them stone dust fights though!! ;D ;D

[erichall]

A further few comments on stonedusting etc. Stonedust - dolomite Limestone - is classed as an 'inert' material, meaning it will not explode. It's amazing the number of things that, when stirred up into a fine cloud will explode - not the least simple plain flour. In the case of the mines however, the greatest danger was not from an explosion of Methane gas. Methane will only ignite within the range of 5 - 15 % mixture of methane in air which normally contains around 20% Oxygen. The major problem is that the resulting explosion derived from a source of methane will stir up the surrounding fine coal dust and cause this to consequentially ignite. Methane is not the only source of ignition, however. SMRE used to do an experiment whereby a spark raised from metal striking rusted iron (as in arches etc) would cause a relatively minor explosion. This was done by striking a simple piece of iron bar contained in an explosive mixture with a descending ball pane hammer to cause the spark. An explosion could be thus demonstrated. The next stage however, was much more impressive. The experiment would be repeated, with the addition to the face of the iron of a piece of aluminium foil (usually from the inside of someone's cig packet). The spark thereby created was much hotter and the explosion so much more impressive. This was the reason for withdrawing aliminium from the mines.
A coal dust explosion was so much fiercer than any other explosion, and was the reason that roadways had to have a minimum percentage of 'inert' material vis stonedust. This was why samples had to be taken and inspected regularly, and why stonedust was applied before an inspector's visit. I remember accompanying an HMI on one surprise visit, along a roadway that hadn't seen stonedust for months. 'I require samples of roof, floor and sides in 3 places' said the HMI, 'Would you care to take them, Mr Hall?' I knew they would fail the test. 'I shall repeat my visit next week' he said, and on this visit was delighted when I invited him to take his own samples, anywhere he chose.'You got the message , then' was his reply.

Incidentally, the 'simple' stonedust barriers, whilst being simple in construction, and being designed to tip and spread a curtain of Stonedust to attempt to smother any explosion, were in fact far from simple, but the subjest of intense testing in the Safety in Mines Research Establishment, part of the government inspectorate, in the galleries at Buxton, derbys. where all explosives, oil lamps, and much more were carried out. This establishment is still in existance close to where I now live.

[John]

If I remember right Eric, aluminium was involved in an explosion in the 50's?.
Had them baffled for ages what had caused it.
Fact, the explosion was methane, fact, it had happened at a ripping lip.
No contraband was found, all cables up to and under the lip were in a safe condition.
State of the ripping lip was safe and had been drilled ready for explosives at the time of the ignition, although none had been charged up.

I think the SMRA at Bretby were brought in to build a true scale mock up at the centre.
Even then it proved an almost impossible task to simulate.

It was at a time the NCB went overboard on aluminium, GEB cases, tools, "Rams heads" etc, all hardened using magnesium.

I don't think the outcome could be totally proved, but, it's believed a ripper, threw or dropped the ramshead, and the rails were close to the face, the ramshead struck the rusty rails and produced an incendiary spark. The rest is history.

Now here's the bit I'm bemused about, all power shall be switched off when CH4 in the general body of the air reaches 1.25%. all men to be withdrawn at what?? 2%??
Now here's a ripping crew using electric power with over 5% CH4 in the general body of the air.

Had they not of ignited methane, would magnesium/aluminium materials have been banned??

"Rams Heads" were still made of aluminium way up to when I left in 1968, minus the magnesium.
I know aluminium foil was banned underground, but usually a blind eye was turned if you took it out with you at the end of a shift, as chocolate and chewing gum was wrapped in it as were many other things.
At Cotgrave they upheld the rule, it was classed as contraband with the same rulings as cigarettes and smoking materials.

I was a little shocked aluminium was still used in NSW, Australian collieries, albiet with special regulations.