Freerails Home 
Home Search search Menu menu Not logged in - Login | Register

Freerails IS ACCEPTING new Members ... To join Freerails ... See how to Register as a Member in the 'Joining Freerails' Forum

Mine Stamps Details
 Moderated by: .
New Topic Reply Printer Friendly
 Rate Topic 
AuthorPost
 Posted: Sun Jun 28th, 2015 11:41 pm
  PMQuoteReply
1st Post
Salada
Registered


Joined: Mon Nov 4th, 2013
Location:  
Posts: 1190
Status: 
Offline
In view of the overwhelming (?) response to my previous "Mine Mill Interior" photos
(thanks to Jose for counting all 5) I thought some of you may appreciate a little more info on the 'black art' of successfully stamping metal ores.

A set of stamps usually comprises 5 individual "heads" within a single frame, the whole also being known as a "battery". So a 50 battery mine stamp mill would comprise 50 x 5 individual stamp heads. An individual battery could stamp anywhere between 1 - 20 tons of mine run ore per day, depending on many other factors as outlined below.

The classic 1800's gold mining stamp is also known as a "percussive" stamp, of which there are two types :

Rotary Percussive or Californian & :

Square Percussive, more usually known as Cornish Stamps.

All the below photos are of the Californian or Rotary percussive type. Firstly a photo of the 'business end', the actual stamp heads :


Photo 1 :






This front view of the battery shows the 5 stamp heads (confusingly called "shoes" by Americans) inside the "mortar" (a.k.a. mortar box or stamp box). Actually there are only 4 heads, one is missing. Also missing is the sieve plate which normally fits into the inclined grooves left & right of the box, retained by the central lower lip. Stamp head weights can vary from about 80 lbs up to about 1,100 lbs per head. This is a relatively lightweight battery.

The stamps must never be allowed to run empty - the mortar box would be shattered in seconds. Someone has put a small piece of timber in place of the rock-ore.

Running up vertically above each stamphead are the "lift-poles" (or lifters in U.S. speak) which run through loose fitting guides in the main frame.


Photo 2 :






This shows the rear of the battery (together with Madame Salada - wondering where is the nearest shopping mall ?!).

Just above the twin cylinder engine can be seen the small feed hopper. Often the feed hopper spans the full width of the stamp box. This feed hopper will be directly fed from a much larger timber chute constructed on site.

Immediately below the upper cross timber/lift-pole guide can be seen the "collars" or bobbins attached to each lift-pole by which the camshaft cams lift each stamp head in turn.



Photo 3 :





T




This shows the curved lift cams (looking like curved horns) fastened to the drive shaft.

The lift on each cam isn't much, usually only about 7" - 8" but that is eneough to smash any normal ore-bearing rock.



Photo 4 :






This shows how the lift cams only operate on one side of the lift-pole collars. This imparts a partial rotation at each drop of the lift-pole - hence the name Rotary Percussive. The square or Cornish Stamp lifters are arranged centrally on each lift-pole so no rotation is imparted to the stamp head. Rotaries are better as stamp head wear is even all round & output is higher per hour. Cornish stampheads wear terribly on one side with attendant down time & reduced efficiency.



Photo 5 :
  





This front view also shows the offset arrangement between lift cams & lift-pole collars.

The stamp box sieve can also be seen in place - the light grey perforated sheet with output spout running down to the left. The horizontal pipe running across behind the lift-poles is the water feed for wet stamping.


Correct adjustment of the running of the stamps could be critical to the success or failure of a mine & so was usually entrusted to an experienced &  skilled engineer.

Factors such as stamphead weight, sieve mesh size, the number of "drops" per minute of each head, ore-rock feed rate, ore particle size, the sulphide content of the ore & whether to dry or wet stamp could make all the difference to recovery rates.

Was it better to stamp all day to produce only 1 ton of very fine pulp through a 40 mesh or better to bash through 20 tons/day with an 8 mesh ?
With higher sulphide content gold ores was it better to run the pulp off onto the mercury amalgamation tables or do the amalgamation by adding mercury directly into the stamp box ?  Both methods were used.

 'Old timers' reckoned overall mill recovery rates were determined 'in the mortar' - probably correctly.

So how good were rotary percussive stamps ?

In their day nothing could beat a well managed Californian for stamping gold, tungsten, tin & some silver ores ( anything where the metal ore particles were finely dispersed through the lumps of ore) when values ran to many ounces or lbs per ton of mine run ore.

But percussive stamps are now totally obsolete due to reducing ore values & increasing costs. No stamp can cope with gold recovery rates that are often now measured in decimal points of a gram per ton. Modern low grade ore mining relies on strip (open-cast) mining, cone crushers, ball mills, cyanide extraction, froth flotation or electro-magnetic separators.

The stamp battery shown in Photos 1-3 is a fairly rare type - it is a rotary percussive tappet stamp, a patented variation claimed to improve output rates; the only one I have ever seen. But for practical purposes it is almost identical to the normal type of Californian.


All photos by Salada.           Additional fashion by Madame Salada.


Regards,             Michael



 



Back To Top

 Posted: Mon Jun 29th, 2015 03:45 pm
  PMQuoteReply
2nd Post
Herb Kephart
Moderator


Joined: Thu Jul 19th, 2007
Location: Glen Mills, Pennsylvania USA
Posts: 6017
Status: 
Offline
 Mr Miner

Great pulley in photo 3!

Perfect example of ''use what ya got''

Herb



____________________
Fix it again, Mr Gates--it still works!"
Back To Top

 Posted: Mon Jun 29th, 2015 08:13 pm
  PMQuoteReply
3rd Post
Salada
Registered


Joined: Mon Nov 4th, 2013
Location:  
Posts: 1190
Status: 
Offline
This type of "plywood" pulley, fabricated out of bits of wood, seems to have been fairly common on stamps throughout the bits of the U.S. Southwest that we visited.
I saw quite a few exactly the same but I have never seen the like in England nor Europe - though there are very few stamps left intact anywhere over here.

Regards,         Michael

Back To Top

 Posted: Mon Jun 29th, 2015 11:56 pm
  PMQuoteReply
4th Post
Herb Kephart
Moderator


Joined: Thu Jul 19th, 2007
Location: Glen Mills, Pennsylvania USA
Posts: 6017
Status: 
Offline
Made ones myself--but I have to say a little better looking, and from laminated dimensional lumber--not ply.

Wonder how an old car wheel with overinflated treadless tire would work-------

'erb



____________________
Fix it again, Mr Gates--it still works!"
Back To Top

 Posted: Wed Jul 1st, 2015 05:36 am
  PMQuoteReply
5th Post
Ray Dunakin
Registered
 

Joined: Wed Jul 25th, 2012
Location: San Diego
Posts: 1243
Status: 
Offline
I know that stamp battery in the first three photos, it's in Randsburg, CA.



____________________
Visit http://www.raydunakin.com to see photos of the rugged and rocky In-ko-pah Railroad!
Back To Top

 Posted: Wed Jul 1st, 2015 09:40 am
  PMQuoteReply
6th Post
Helmut
Registered


Joined: Sun Feb 17th, 2013
Location: Friedberg, Germany
Posts: 1131
Status: 
Offline
Herb Kephart wrote:
Wonder how an old car wheel with overinflated treadless tire would work-------

Not too well. You have two areas where you rely on friction, one of which ( the rim ) is prone to slipping under load. The other one is critical, too, because you have two elastic surfaces ( the belt and the tyre ) that have a tendency to smear when slippage occurs. Also the starting of such an arrangement would always be with a jerk instead of the smooth transition you'll have with the common belt-on-wood/steel arrangement.
Last, if sufficient lateral force is exerted on the tyre, it may leave the rim, as the belt cannot slip laterally on its surface.



____________________
Regards, H.
Back To Top

 Posted: Wed Jul 1st, 2015 01:12 pm
  PMQuoteReply
7th Post
Herb Kephart
Moderator


Joined: Thu Jul 19th, 2007
Location: Glen Mills, Pennsylvania USA
Posts: 6017
Status: 
Offline
Helmut

You might be right about it not working, but only an under inflated tire will slip on its rim. A properly inflated tire will not, as proved by the idiots in this country who delight in grinding up their rear tires in clouds of smoke.

https://www.youtube.com/watch?v=9tNj7HG5Ow4

Can you say "goodbye $500''?

Herb



____________________
Fix it again, Mr Gates--it still works!"
Back To Top

 Posted: Thu Jul 2nd, 2015 07:01 pm
  PMQuoteReply
8th Post
SJSlots
Registered


Joined: Sun Nov 4th, 2012
Location: Cincinnati, Ohio USA
Posts: 142
Status: 
Offline
While I can not argue that it is done here... that video is of a right hand drive Camaro in Melbourne Australia. There are rubber burning 'idiots' the world over! Wasn't it the Japanese that made 'drifting' so popular?



____________________
Shawn
http://sjslots.webs.com/
Back To Top

 Posted: Sat Jul 4th, 2015 02:00 pm
  PMQuoteReply
9th Post
elminero67
Registered


Joined: Sun Dec 27th, 2009
Location:  
Posts: 906
Status: 
Offline
Great post on stamp mills. We still have a few tucked away in the hillsides of the American West, and a couple which hobby miners will set up and run on ore (actual small scale miners, not museums) once in a while, but they are becoming less common.



____________________

Back To Top


 Current time is 12:40 pm

Top



UltraBB 1.172 Copyright © 2007-2016 Data 1 Systems