View single post by Salada
 Posted: Thu Jun 11th, 2015 09:45 pm
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Salada



Joined: Mon Nov 4th, 2013
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For anyone interested in seeing the inside of an intact mine mill, or wishing to model one, here are some photos of a small mill in working order. Little has changed inside the mill since the 1950's, in fact it is probably still looks very similar to how it would have been at the start of the 20th C.

Firstly, a remarkable survivor (not me - the "turbine") :

Photo 1 :







This is a water powered "Turgo Impulse Wheel" - an evolutionary 1/2 way step between an older Pelton Wheel and a modern turbine. This same machine was installed here, new, in 1918 & is possibly the world's oldest working Turgo still in it's original position.

These machines are still in use in some remote 'back country' mining districts (especially Africa) because they will happily run on a dirty, gritty water supply that would wreck a modern high precision turbine.

I replaced the shaft bearings in 1995 but the rotor had recently developed an ominous but hard to locate heavy rumble - hence the facial look seeking mechanical revelation ! This is the mill's second oldest prime mover, it was previously powered by overshot waterwheel only.

The "hard-hat" is for scale only, I can't stand actually trying to work in one, except in low roof mine workings. The 3" pipe leading off behind the hard-hat supplies water to the stamps from the Turgo penstock (feed-pipe). Stamps are run either wet or dry, according to the type of rock/ore being processed.  The drive is via a 3 speed mechanical reduction using different sized belt pulleys (manual change only !); these pulleys can be seen upper right.


Photo 2 : The "3 speed" pulley arrangement :





The drive pulleys (left & right) have been temporarily removed from the Turgo rotor shaft  to allow access to the bearings. The large, green spoked LHS pulley is for driving the stamps (1st gear !). The other pulleys are for general power, air compressor & the tramway haulage incline winder.


Photo 3 :  Looking down onto the Turgo from the haulage winder drum :







 
The large handwheel just left of centre is the penstock on-off valve supplying the Turgo.

To the left is an early Ingersoll compressor for the rock drills. Right foreground is the incline haulage winding drum. Access to the main valve & the Turgo power/speed control valve involves squeezing along this 'passageway' between whizzing 6" heavy canvass belts & whirling drive-wheel spokes - a certain sense of balance & lack of fear (stupidity ?) is helpful !.


Photo 4 : An overall view of part of the mill interior :







Note the piles of essential stuff everywhere. Stacks of steel piping, steel props, spare pulleys, gears etc.  The floor is simply compacted dirt, rock dust etc.  that has become so compacted over the years it is almost solid. 'Economy' roof props, cut from the surrounding woods as required.

The Turgo can be seen at rear upper right. Elsewhere, behind the camera are fitters/mechanics benches & tool stores (the mill is also the mine engineering base) and extensive ore settling tanks set into the ground.

The chute behind the stamps, sloping down from the upper left, is the ore feed from the tram system outside the mill.




Photo 5: Partial overview from above & behind the stamps :





 
 
Right foreground is the incoming ore chute & water sprinkler bar (just below the red line-shafting. Note the 'economy' roof structure ! - no small mining concern ever wasted money !.

The vertical lever, immediate foreground, is the 'clutch' for the stamp's drive. The stamp drive belt is temporarily run-off it's pulley - it would normally pass over either the rusty crowned pulley or the green pulley. One of these pulleys is fixed to the drive shaft, the other is free to rotate. Operating the clutch lever simply pushes the belt across, via a sort of open 'banjo' from one pulley to the other. Any attempt at 'clutch slipping' for a gentle start can push/pull the belt right off so the clutch lever is thrown smartly - Zap ! Judder & the stamps start at almost full speed !.

My lack of photographic skill/knowledge has weirdly foreshortened the far end of the mill - the settling tanks, tool store etc. seem to have disappeared !

The main message is : you can't have too much clutter around a working mill, unless it is one of these new fangled, white suited, computerised jobs - & who wants to model one of those ?.

This is a hard rock, metal ore mine but NOT a gold mine, though the principles are generally the same except :

Outside : a gold mine would have cyaniding tanks* + stirrers, external ore bins, waiting stock piles of "mine-run" ore (i.e. as raised from below, awaiting grading, sorting, preliminary crushing etc. * depending on location & era.

Inside : a gold mine would have shaker tables, Wilfleys etc


- but otherwise there ain't a lot of difference in overall appearance (we ain't got no rattlers or tumble weed !).


That's all folks.......


Photos by Salada.


Regards,                   Michael

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