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Generalcan dexpan be used for mining for minerals

10th Jun 2012 10:48 UTCAqua marine

HI

i was wondering if it will be practical to use dexpan instead of blasting for mining minerals. alot of minerals get damaged because of blasting.

here are my mining conditions.check the videos

http://www.youtube.com/watch?v=zF6oLrOxsFk

http://www.youtube.com/watch?v=vZjvFKbuchQ

http://www.youtube.com/watch?v=Wenhuu0LfaU

if dexpan is feasible here. it would reduce the damage that we get in minerals .

please discuss this possibility.

10th Jun 2012 15:21 UTCLuiz Alberto Dias Menezes, Fo.

I am not familiar with dexpan, but I suppose it is a kind of an expansive putty; I don't think this is the best solution for replacing blasting in pegmatite mining; I think the best alternative is a combination of a high-pressure hydraulic breaker and a diamond-chain saw; the method was developed by Bryan Lees and extensively used to mine rhodochrosite at the Sweet Home mine, as you can see on the special issue of The Mineralogical Record about that mine (Vol.29, no.4, July-August 1998).

If you will attend to the Sainte Marie aux Mines show please come to my tent CT-004 and I can explain you how this equipment works.

10th Jun 2012 17:49 UTCJohn M Stolz Expert

I've used dexpan and it worked great for my application--breaking up reinforced concrete footings. I'm not sure that this will work for all your applications though:

- After mixing, the dexpan shouldn't be exposed to water. I doubt you have much in way of groundwater from what I saw in the videos.

- You can't use it in overhead or upward sloping holes. I've wondered though if you couldn't just mix the dexpan thicker and use a blowpipe to get it in. I would think you'd want to start at the bottom of the hole.

- I would think that if you have a lot of fissures and open joints, the expansive agent could extrude into them.

I would just try it and see.

Let us know how it works.

John

10th Jun 2012 22:25 UTCRock Currier Expert

You can use many techniques for mining including the ancient method of fire setting. There is however little better than explosives to move quantities of rock. Usually when you get near a pocket in a pegmatite there are indicators that you should slow down and take it easy so as to preserve the specimens that may be there. What kind of explosives are commonly used in your area for mining pegmatites? Ammonium Nitrate? I might suggest you look into getting a "micro blaster". Here you use small drill hole, perhaps the diameter of a pencil that can be made rapidly with several different kinds of rotary hammer drills. Then you load the holes with small explosive charges that look like regular small caliber bullet casings, but without the bullet. You can detonate the charge by pulling on a string. This tends to crack a small amount of rock and will cause minimal damage to nearby crystals. Unless you are prepared to the trouble and expense of setting up a diamond chain saw and the accompanying equipment to operate the hydraulics needed for the saw, this may be the answer for you.

11th Jun 2012 02:14 UTCBart Cannon

I wish I didn't have so much to contribute, but here I am again.

I have used every kind of explosive except ANFO, and every kind of expanding mortar such Bristar etc.

Expanding mortars will not break a face and the time needed for cracking takes overnight. If you don't mix them with the exact water content and temperature, you will find out the next day when you see no action..

I once had explosives permits for Californian and Washington State. No permits were needed in Montana in those days.

Now a legal magazine is needed everywhere, and you can not just buy your powder and take it to your project. You are required to have the dealer drive it to your magazine from their facility. Using explosives is now so expensive that the operation is futile.

The Micro-Blaster is what I use now, but Washington State is planning to make it illegal. Buy the charges now. The noise of the explosion is about the same as that as a .22 long rifle bullet. 22 caliber rifle rounds are not illegal yet.

To make the hole I use a 5/16 th inch tungsten carbide bit and a Bosch lithium ion rotary hammer. Great in the fresh air and underground as well.

Bart

13th Jun 2012 15:21 UTCBob Jackson Expert

Agree with Bart's advice on the expanding grouts ... they have little application in mining, except perhaps to split boulders. Products I find very useful in specimen mining are propellant-based. There is no explosion, hence no P-wave to shock specimens. One brand is RockCrackers, made in Canada. Most states do not require a blasting license to use, but may for the shock tube assembly that initiates the reaction.

That said, a blaster with specimen mining experience will time the explosive speed to the rock conditions and preserve your pockets for gentle extraction.

Good luck,

Bob

15th Jun 2012 20:34 UTCTim Jokela Jr

Surely you don't have any trouble getting dynamite in Skardu!!!? With practice and experience you can move plenty of rock with minimal damage to pockets; when you drill into an opening proceed with quarter sticks, or hammers and wedges would be even better.

15th Jun 2012 23:24 UTCBob Jackson Expert

A quarter stick in an opening! That should produce some colorful sand...

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