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Gold/Mining/Energy : ECHARTERS -- Ignore unavailable to you. Want to Upgrade?


To: Bill Jackson who wrote (2110)1/2/1998 8:01:00 PM
From: E. Charters  Read Replies (1) | Respond to of 3744
 
Not too much I would argue with there except for the fact that you said it so it must be inaccurate somehow. Bond index of gold ores varies from 15 to 28 (tough). Sulfides can be VERY hard to grind fine. I will bet that there are some pyrites that you will not grind beyond 80 mesh with the hammer of Thor and a nuclear turbine.

Mica is the hardest substance in creation to grind next to bubblegum and horseshit(mixed). Mica has a Bond index of 128!.

But that gold with tweezers is not of course a joke. At my mines that is how we do it. We use the spatulate tipped no 12 copper tipped gold tweezer. After blowing the magnetite away we dip the tweezer in mercury and then nitric acid quickly then tweeze, tweeze tweeze. (Don't do this at home folks, mercury fumes gonna GET yah.)

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I used to tweeze gold with a very fine pointy set of tweezers out of pan concentrated and table concentrated till and river samples under a 100 power binocular microscope. Spent a couple of seasons doing that in Alberta. Tweezed the odd diamond indicator too. You can actually tweeze down to 20 microns. .02 MM. When you put the grains on sticky tape you could not see them with the undressed eyeball. The silicates are usually biggish grains and crystals at around 100- 200 microns +. The sulfides can go finer or coarser and go to odd shapes in till. Spheres and tubes and aggregates abound as well as crystals and lumps. Gold is the one substance whose colour still is retained in the finest of grains (Because of its reflectivity). If you can barely see it and still detect a yellow colour chances are its gold. Sulfides will not show bright colour in extremely fine grains. With magnification the difference between gold and sulfide magnifies. It is impossible to miss gold or mistake sulfide for it at 60 magnification. If you do a lot of microscope work you start to realize one thing. Certain minerals are rare and others are very common. It is very uncommon to see copper or silver minerals in some locales. In Alberta I saw more gold than copper. Zinc, pyrite, magnetite chromite and ilmenite are very common. Garnet, zircon, quartz, hematite are everywhere.

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Give me a real silver anomaly and I will show you a mine.
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echarter@vianet.on.ca

The Canadian Mining Newsletter



To: Bill Jackson who wrote (2110)1/2/1998 8:35:00 PM
From: E. Charters  Read Replies (1) | Respond to of 3744
 
I would say that rock is usually crushed at 80% passing 160 mesh as in Kirkland Lake to 80% passing 300 mesh as the most usual. This usually takes one horsepower day per ton. So a 1000 horsepower mill about 12 feet in diameter and 12 feet long should reduce a medium silicate ore from pea gravel to 200 mesh at a rate of one ton per horsepower day. Ergo 1000 tons in one day. That is the use of 18,000
kilowatt hours in one day which should cost you $2,700.00 If you generate by diesel you can make that $5,400.00 per day. (your fuel is only 18 cents a KWH but maintenance and capital and fuel transport) is the other 12 cents.)40 hp diesel= 1 gallon per hour.=24 hp electric = 18 KWH = 18 cents per KWH in Toronto plus other costs.