# Gold Ore and Bleach Insight



## f2fgold

Folks, my name Charles Stillman and I live Utah. Being a novice, most likely my questions will show my lack of understanding. I have an ore that has been assayed containing 4% gold. It is owned by a friend and he got the assay information from a Colorado company. I have reduced the ore to 150 micrometers in size and have removed most of its magnetics. 

The Internet showed instructions for HCL/Bleach extractions. It stated 2:1 ratio – Acid / Bleach. Use six times the volume of the ore. Let act for 4 hours stirring every 20 minutes. Then add Sodium Metabisulfate to drop the gold.

Questions: 
Does this sound accurate? 
Do I need to remove the bleach before adding the SMB? 
If so, how do I remove the bleach? 
If bleach is still in the solution will it cause the Stannous Chloride to respond falsely? 

I have read so much from different points of view but for different materials and under different conditions. I have done searches on the forum for bleach, ore, aqua regia and so on. Almost all of the advice is about gold refining and not gold extraction from ore. If I have missed something, please point out where to find it. It is like Butcher said, "sometimes just someone saying it a different way and we can understand it better, small details can easily be overlooked…" 

I have researched C M Hoke's book and C W Ammen's 2nd addition. Obviously I refer to them A LOT! Hoke's book is not about ore extraction and she makes that clear. Ammen's book doesn't bring bleach up very much; his is mostly aqua regia. I have even read on the forum the feelings of most on the value of, or lack of, extracting gold from ore and its challenges. Nevertheless, any insight from you folks would be of great help. Thank you in advance. (And by the way, I have had 9 children so you can say anything you want and it won't hurt my feelings.) I apologize if this has already been discussed and answered. I am still learning how to get around in the forum. 

I also wish to thank Harold _V and Butcher for their kind words and the quality they portray in their comments. It is an honor to be associated with people who have the desire to help others and the courage to reprove when needed.


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## chlaurite

We use the HCl/Clorox step for refining, not recovery (or in your case, "extraction"). It puts _almost everything_ into solution, not just gold, so you need to get rid of (at the very least) any other non-PM metals present before you try to dissolve the gold itself. For SMB, you can think of that the same way Ms. Hoke mentions Copperas. So that said...

4% ore sounds *incredibly* high - When you say "ore", do you mean something already partially processed, like black sand?

I ask because it makes a big difference how you proceed. If you have gold-on-quartz, you can probably go right to HCl/Clorox. If you have black sand, you need to remove a LOT of random ferrous metals before you even think about putting the gold itself into solution, or you'll just end up with a huge mess.

Disclaimer: Still a newbie myself.


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## bswartzwelder

Charles,

\Welcome to the forum. Almost anything you need to know has been tried by someone else (here on the forum) at least once. We do not try to reinvent the wheel, but we do make some mistakes. We learn from those mistakes and others learn from us as well. Most newbies want to join the forum and have everything hand fed to them one step at a time. Most members will not do that because it is far more important that you learn the basics and then move on to the more advanced things. You have not appeared like that having said you have already read Hoke and Ammen. There are TWO basic processes discussed on the forum, RECOVERY and REFINING. You must first get the values and then refine them by eliminating everything that is not the PM (Precious Metal) you are after. Read the forum, especially the safety sections. Nothing you do is worth jeopardizing your safety or the safety of those around you whether it be family, friends, or neighbors. DO NOT ALLOW anybody near when you are recovering or refining. Any distraction can be fatal. Do everything outdoors or in a well ventilated area. Use the proper safety gear. One drop of sodium hydroxide (lye, caustic soda, NaOH) can (AND WILL) blind you if it gets into your eyes. I have a pair of shoes where 1 drop of NaOH fell on them and now there is a nice big hole in them.

I have read your post and, one thing JUMPS OUT at me. You said you used sodium metabisulfAte. It will not work. You need to use sodium metabisulfIte. There's only one letter difference between the two chemicals, but their usage in dropping gold from solution is day and night. READ HOKE until you think you understand it, then READ IT AGAIN, and use the SEARCH function on the forum. It's all there for the reading and, it's FREE. You can't get a much better deal than that.

A lot of what I have written is for a total newcomer, so don't take it personally if you have progressed beyond the initial stages. It's better to hear someone spell out safety than it is to have a needless accident. Butcher stresses ALWAYS POUR ACID INTO WATER and not the other way around. There are good reasons why we do things the way we do. By the way, with nine kids, when do you have time for R&R (recovery and refining) much less R&R (rest and relaxation)? I have 4 boys, all grown now. Between work and the drive to and from, I had very little free time. Good luck, I hope this helps.

Bert

P.S. As with any chemical process (Aqua Regia AR, Acid Peroxide AP, or Acid Chlorox) the chemicals undergo a change whereby they are no longer the original chemicals you started out with. You cannot remove the bleach from your solution. However, most newbies (myself included) usually use too much of one thing or another and end up with excess nitric in our solutions. If this happens, trust me, you'll probably only do this once. Getting rid of excedss nitric is almost like trying to unring a bell once it's been rung.


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## FrugalRefiner

Charles,

Welcome to the forum. There is one common error in what you stated "Then add Sodium Metabisulfate to drop the gold." SMB is sodium metabisulphite, not metabisulphate. Both chemicals exist, but sodium metabisulphate will not precipitate gold.

I've recently been reading T. K. Rose's _The Metallurgy of Gold_. It deals extensively with ores, including roasting and leaching. You'll find that different ores require different treatments, but the general idea is to roast the ores to convert most metals to non-soluble compounds so the chlorine will leach primarily gold and not be wasted on all the other metals. It's an old volume, but worth a read if you're dealing with ores. It's beyond copyright protection so it is freely available. Try a search in Google books.

Dave


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## Traveller11

FrugalRefiner said:


> Charles,
> 
> Welcome to the forum. There is one common error in what you stated "Then add Sodium Metabisulfate to drop the gold." SMB is sodium metabisulphite, not metabisulphate. Both chemicals exist, but sodium metabisulphate will not precipitate gold.
> 
> I've recently been reading T. K. Rose's _The Metallurgy of Gold_. It deals extensively with ores, including roasting and leaching. You'll find that different ores require different treatments, but the general idea is to roast the ores to convert most metals to non-soluble compounds so the chlorine will leach primarily gold and not be wasted on all the other metals. It's an old volume, but worth a read if you're dealing with ores. It's beyond copyright protection so it is freely available. Try a search in Google books.
> 
> Dave



As he is speaking of "magnetics" in his ore, I would assume most of the iron in his ore is in the form of magnetite or haematite. As these are already oxides, would there be much point in roasting his ore to oxidize base base metals? A good analytical assay of his ore would show him if any base metals existed in his ore as free metals.

Also, we should be pointing out to him that the HCl/Clorox method, at a pH of 1-2, is far too acidic and the bonds of the oxides will get broken at that pH, allowing the base metals to go into solution. Trying to adapt the HCl/Clorox method, designed for refining gold, to leaching gold from ore is a waste of time. Plus, you will lay out more money in acid to try and remove base metals from ore than you will likely ever hope to recover from that ore in gold. Most patents show leaching with sodium hypochlorite to be done at a pH closer to neutral (7), at which point the sodium hypochlorite is converted to the powerful oxidizer hypochlorous acid. Addition of 10% sodium chloride by volume seems to be necessary as well. Also, the old timers made hypochlorous acid by adding chlorine gas to water. They then kept the solution under pressure, with the ore, in a sealed vessel, for two reasons. The pressure forced the chlorine to go into solution as hypochlorous acid more efficiently and the elevated pressure kept the hypochlorous acid molecule (HOCl) from losing its oxygen atom and becoming hydrochloric acid (HCl). Not only would this make the solution overly acidic, breaking the bonds of base metal oxides, it would prevent the hypochlorous acid from doing the job it was assigned, namely, dissolving gold.


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## f2fgold

chlaurite: Thank you for that understanding. It actually helps. Yes the 4% is very high and it's even higher for the Platinum group. Even the assayer was surprised but he said it would be hard to get out. Not sure why though. The ore, as I am told, is many years old waste from extraction at an old mine. It is very heavy and reminds me of galena by color and weight (but it is not I am told).

Bert and Dave, you are correct and it is my mistake in spelling. It is Sodium MetabisulfITE. Thank you for correcting me. I know how important it is to be accurate.

Now I actually am very familiar with safety, protection, acids and bases etc. I am surprised at the lack of cleanliness and controls a lot of Internet videos show. I have an excellent fume exhaust system, gloves, aprons and so forth and I do not use large amounts until I am familiar with reactions. I do everything I can to read and understand before action, have the correct tools and equipment even if I need to make them. That said, I appreciate the forums constant reference to following safety precautions.

Traveller11, I have actually heated the ore to 1500 degrees in an electrical furnace. I crushed the ore to 150 micrometers, used a magnet to remove the magnetics, put it then in an iron skillet about a ¼ inch thick to roast. It became a connected mass as a crust. When I removed it, it was basically one piece. I then used the HCL/Bleach, mistakenly as you men have taught me. I have also tested it for sulfur with a test tube as per Ammen's instruction and found no sulfur. I've used aqua regia, evaporated it (yet I may have boiled to high), used pure copperas crystals I have created, yet it has only worked on electronic scrap. I have created stannous chloride and tested it with electronic gold. It works great but cannot get a reaction from the ore. 

Gentlemen, I appreciate your responses. You have given me very important items to assess my actions. I will review them many times to get all I can out of them. I have been working alone for so long in the learning process that it will take some getting used to having people with skills answering my questions and double checking my messages. Thank you.


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## f2fgold

Bert,

I am 60 years old and my last son is 18 so I do have a little time.... a little. I would tell people when they would ask how many children I had, "I have 9 children... five living and four teenagers."


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## Traveller11

f2fgold said:


> chlaurite: Thank you for that understanding. It actually helps. Yes the 4% is very high and it's even higher for the Platinum group. Even the assayer was surprised but he said it would be hard to get out. Not sure why though. The ore, as I am told, is many years old waste from extraction at an old mine. It is very heavy and reminds me of galena by color and weight (but it is not I am told).
> 
> Bert and Dave, you are correct and it is my mistake in spelling. It is Sodium MetabisulfITE. Thank you for correcting me. I know how important it is to be accurate.
> 
> Now I actually am very familiar with safety, protection, acids and bases etc. I am surprised at the lack of cleanliness and controls a lot of Internet videos show. I have an excellent fume exhaust system, gloves, aprons and so forth and I do not use large amounts until I am familiar with reactions. I do everything I can to read and understand before action, have the correct tools and equipment even if I need to make them. That said, I appreciate the forums constant reference to following safety precautions.
> 
> Traveller11, I have actually heated the ore to 1500 degrees in an electrical furnace. I crushed the ore to 150 micrometers, used a magnet to remove the magnetics, put it then in an iron skillet about a ¼ inch thick to roast. It became a connected mass as a crust. When I removed it, it was basically one piece. I then used the HCL/Bleach, mistakenly as you men have taught me. I have also tested it for sulfur with a test tube as per Ammen's instruction and found no sulfur. I've used aqua regia, evaporated it (yet I may have boiled to high), used pure copperas crystals I have created, yet it has only worked on electronic scrap. I have created stannous chloride and tested it with electronic gold. It works great but cannot get a reaction from the ore.
> 
> Gentlemen, I appreciate your responses. You have given me very important items to assess my actions. I will review them many times to get all I can out of them. I have been working alone for so long in the learning process that it will take some getting used to having people with skills answering my questions and double checking my messages. Thank you.



Actually, I have never recommended the HCl/Clorox method for ore or concentrates. I also think you could have saved yourself a lot of work if the base metals in your ore already existed as oxides, as, outside of reducing them in particle size, you may have been able to leach them just as they were. When dealing with microscopic particles of gold, any unnecessary process, such as removing magnetics, has the potential to lose gold out of your ore or concentrate.

Here is some interesting reading. It is an article from an Australian newspaper dated Jan. 31, 1891.

http://trove.nla.gov.au/ndp/del/article/71248750


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## f2fgold

Thank you Traveller11. I will review that right know. I can see I am using the wrong process completely. 

And thank you FrugalRefiner for the link. I have downloaded it and am going through it. 

THIS is why I decided to join.


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## Platdigger

You might try SSN. As it is a a good leach for gold and the pgms. And you shouldn't need a pressurized vessel to do it in.


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## Traveller11

Platdigger said:


> You might try SSN. As it is a a good leach for gold and the pgms. And you shouldn't need a pressurized vessel to do it in.




Does the SSN leach not also put everything into solution, including base metals?


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## mitchd

Hi, The assay is really high, that comes out to 80 pounds per ton not troy, would be a bit less in troy weight. I would find another assay lab and run it again.
when most mines are mining gold ore that is around .10 of a ounce per ton, 80 pounds per ton is just so very high and the fast that is has been mined before it just seen to good to be true. also don't think that there is any PT at all but it would be nice and I wish you all the luck in the world that you have such great ore, but PLEASE get another assay done and not from the same lab.

Mitch.


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## Traveller11

mitchd said:


> Hi, The assay is really high, that comes out to 80 pounds per ton not troy, would be a bit less in troy weight. I would find another assay lab and run it again.
> when most mines are mining gold ore that is around .10 of a ounce per ton, 80 pounds per ton is just so very high and the fast that is has been mined before it just seen to good to be true. also don't think that there is any PT at all but it would be nice and I wish you all the luck in the world that you have such great ore, but PLEASE get another assay done and not from the same lab.
> 
> Mitch.



Holy crap, Mitch, you're right. I glossed over the assay part but it does indeed work out to 80 pounds per ton or 97 Troy pounds or 1,164 Troy ounces. At even $1000/Troy ounce, that would be $1,164,000/ ton of ore. Another assay might just be a good idea.


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## Harold_V

f2fgold said:


> Yes the 4% is very high and it's even higher for the Platinum group.


Red flag time, Charles. I want you to step back, take a deep breath, then consider that everything you've posted simply isn't true. And, please understand I'm not trying to be rude (nor am I charging you with being a liar). 

Lets look at this logically.

Gold is mined at concentrations as low as .10 ounce per ton, and the operation is profitable. As I stated in a different thread, just this evening, one percent content is nearly 300 ounces/ton. Armed with that idea, the ore you discuss would contain in the area of 1,200 ounces/ton, with a value of approximately $1,530,000/ton, and that would be just for the gold. Do you still think you've found something that rich? 

Lets look beyond that for a moment. The US is not known for its platinum group production. Sure, there's some here---Kennecott produces platinum and palladium, and most likely some of the other platinum metals---but they are nothing but traces, with hundreds of thousands of tons processed per ounce. Were it not for the copper, silver and gold produced, they couldn't recover the platinum group economically. 



> Even the assayer was surprised but he said it would be hard to get out. Not sure why though. The ore, as I am told, is many years old waste from extraction at an old mine. It is very heavy and reminds me of galena by color and weight (but it is not I am told).


Another red flag, Charles. 
That's to imply that those who went before us were stupid. Being from Utah myself, and having been raised in the greater Salt Lake Valley, I am all too aware of the fact that mining is what built Utah. At one point in time, there were 28 smelters in the greater Salt Lake Valley. I remember when assay labs were abundant on the west side of Salt Lake City, and I used to use the last one in existence, Union Assay. 

To suggest that the ore in question contained such riches and was discarded as waste can't be anything more than a myth, and I suggest to you that the person doing your assaying doesn't know what he's doing. I would further state that if he isn't doing a fire assay, you're wasting your time. 

While I can't predict his motive, one of them may be to keep you coming back. I know that when I lived there (that's where I lived when I refined), there was one individual who continually made grandiose claims, none of which were ever substantiated. You may be being victimized by the same individual. Sorry, I do not know his name, as I heard of him only through folks who were told they had riches, but did not. 

Before you do anything, including trying to extract any values you hope to find in your ore, it would be prudent to pay for a fire assay, requesting a report on silver and gold alone, as a matter of economics. Don't worry about the platinum metals. I suspect they don't exist, but if you find you actually do have silver and gold worthy of recovery, you could consider them at a later date. I guarantee you---even if you find the ore contains them, you won't have enough of them, even cumulatively, to process this ore for their extraction alone. 

Harold

Edited to correct misinformation----thanks goes to FrugalRefiner


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## f2fgold

Gentlemen,

THIS is exactly why I am here. It all makes sense. I think the problem is that my friend is also one who knows precious (no pun intended) little about the ore he has and is going by hearsay. 

I knew when I started with the forum that I would most probably find out I know even less than I thought I knew. Nevertheless I took a deep breath, tightened my belt and forged ahead. I will be a rough stone for a while until you folks polish me. I appreciate it very much.

I will do some more research into what he thinks is going on and even see if I can get the assay report. I do know however that his motives are not to get something from me or harm me in any way. I think he is the one who may have been deceived. And yes, now that you bring it up, Harold, it is totally impossible to think the miners would have left that much PM in their waste. I will tell him to get a fire assay of his ore.

Again, Thank You. I'll have more information soon hopefully.


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## f2fgold

PS: Thank you Traveller11 for the link. I have downloaded it and read it. Very helpful.


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## Traveller11

f2fgold said:


> PS: Thank you Traveller11 for the link. I have downloaded it and read it. Very helpful.




You are welcome. Interested in reading some more from that period?


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## f2fgold

Absolutely Traveller11! I am a sponge.


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## f2fgold

And Harold, I think I first read that you were saying my friend may have motives not in my best interest. However, after reading it again and again I realize you were referring to the assayer and THAT may be true.


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## Traveller11

f2fgold said:


> Absolutely Traveller11! I am a sponge.



Here you go. This is the same process, only the chlorine solution is generated electrolytically from salt water and, instead of sodium metabisulphite to precipitate gold, it is deposited in the electrolysis process at the cathode.

Once again, from the 1890's, so the language is a bit hard to follow.

http://www.miningandmetallurgy.com/metallurgy/electrolytic-precipitation-gold


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## f2fgold

Thank you again Traveller11. (Am I supposed to thank as often as I do? I don't want to use up letters and have others run out. )


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## niteliteone

f2fgold said:


> Thank you again Traveller11. (Am I supposed to thank as often as I do? I don't want to use up letters and have others run out. )



Let me give you a hand with that.
Thank You Traveller11, I enjoyed that read as well.


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## Harold_V

f2fgold said:


> And Harold, I think I first read that you were saying my friend may have motives not in my best interest. However, after reading it again and again I realize you were referring to the assayer and THAT may be true.


Yes--the assayer.. He's one of two things. He's a simple person who means no harm, but doesn't know what he's doing---or he's a con man and is setting up a mark. The very idea that ANYONE would claim an ore with a content of more than one percent is most assuredly not being truthful. When you do see ore that rich, you won't wonder if it contains gold---you'll KNOW it contains gold. I've handled a gold ore that ran 325+ ounces/ton. It was painfully obvious. 

Your friend must keep a clear and open mind, otherwise he will be taken for a ride. 

Best policy is to emulate my position. Think that the ore is barren, and that it isn't worth pursuing. Then look to disprove your conviction. That way you won't be blinded. Please trust me on this. It's much easier to think you have nothing, to be pleasantly surprised to discover you have a little, than to think you have plenty, only to discover you have nothing. The let-down can be horrible. 

Harold


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## maynman1751

No truer or wiser words spoken!!!!!!


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## f2fgold

Thank you Harold. I believe you. I have so much to learn, it is good that I am not poisoned by gold fever. I have a purpose for learning everything I can, but not to get rich. The only thing that is hard to deal with is that the elements are smarter than I am. Nevertheless, with patience, study, gratitude for help and knowledge... I just may get to know them well enough to set up the environments necessary for them to do what they do best.


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## meatheadmerlin

I liked the article at http://trove.nla.gov.au/ndp/del/article/71248750
It originally appeared in the Australian Town and Country Journal,
on Saturday, January 31, 1891 on pages 24 and 25.

I noticed the OCR text provided on the site contained a good number of errors
and corrected them for my own copy of the article.
I decided against creating an account with the site to post the changes there,
and have included the text of the article here.
I have tried to preserved the original text including line breaks.
The addition of (sic.) has been used to show how a word actually appears when spelling is in question.
Also, references to sulfur and its compounds use the ph spelling.

(on page 24)
Chlorination
------------
The chlorination process of extracting gold
from its matrix, and from from concentrates, is 
often freely alluded to in newspapers and amongst(sic.)
miners; and yet, as a rule, the principle is but
vaguely understood, even by men who make
mining their business. Our explanation will be
principally for persons who understand but little,
if anything, of chemistry. To the scientific man
the great affinity of chlorine for the precious
metals has been known almost ever since the dis-
tinguished German chemist, Schule, first dis-
covered chlorine, about the year 1774. Chlorine,
then, is an element, that is a simple substance,
out of which nothing can be produced but itself,
chlorine. It is a gas, and has many remarkable
properties- bleaching almost all colored sub-
stances, and being very heavy as compared with
common air, and being also very deleterious to
breathe. It is largely consumed by man and the
lower animals in food as common salt, which
contains a little more than half of pure chlorine.
It comes into use in mining in consequence chiefly
of its great affinity or liking for gold and silver.
If it can get sufficiently near it will seize hold of
them, appropriating a certain portion to itself,
making what is called chloride of gold or silver.
It being so abundant in nature, salt being so
common, it is made cheaply- a little dilute sul-
phuric acid put on salt liberates chlorine gas, and
its attraction for silver can be witnessed by the
curious any day in the Sydney Mint by watching
the chlorine gas being put into the bottom of the
molten gold in the pot, and as it bubbles up to
top seeing it seize hold of the silver, carrying it
to the top of the gold as a chloride of silver. In
using chlorine to extract gold you simply crush
the stone or matrix so fine that it can get at the
gold and take hold of it as a chloride. The
easiest way to do this is to put the chlorine in
solution in water, and so powerful is its action on
gold that it dissolves that metal, holding it in
solution as water holds sugar. There is
no difficulty in making a solution of
chlorine, as at ordinary temperatures water
dissolves about twice its volume of chlorine.
Thus then having liberated the gold from the
stone by crushing, and having made chlorine gas,
as can be done cheaply, say from common salt,
and having passed the chlorine so made through
water, and thus made a solution of chlorine, and
bringing it and the crushed stone together, in a
short time you have your chlorine solution, con-
taining all the gold in solution that was in the
crushed stone. Having then the auriferous
chlorine solution decanted or run off from the
sludge or crushed stone or pyrites, you put some-
thing into it which will deposit or throw down
the gold. Either one of two things, both of them
very cheap and easily obtained, will do this
effectuallly(sic.), viz., a solution of sulphate of iron,
common green vitrol(sic.), or pieces of common wood
charcoal. The first will throw all the gold down
as a powder; the other, wood charcoal, will
take to itself the gold out of the solu-
tion as a brown film, and upon the charcoal
being burned away the pure gold remains. This
is the rationale or reason of what is called the
chlorination process, and any person of ordinary
capacity, upon reflecting upon the foregoing, will
not fail to comprehend the method used through
the aid of certain machinery, which we will
presently describe. It may help to understand
this subject if we remind the reader that each of
the three chief processes of extracting gold from
its matrix or stone or pyritous matter consists in
bringing it into contact with some substance
which has so great an affinity or liking for it that
it is taken up or amalgamated, and then the
amalgamating substance got rid of or the gold
taken from it. Thus in the common stamper bat-
tery or grinding mill mercury is the amalgamat-
ing material, as all miners know, which takes up
the gold. In smelting, matter containing gold is
put by intense heat, often assisted by fluxes of
various kinds, into a state of fusion, and then
brought in contact with molten lead, which,
like mercury, has an intense affinity for gold,
and it is thus extracted- the lead in the one case
and the mercury in the other being ultimately
taken from the gold by evaporation, or as regards
the lead by cupellation, which is in effect evapo-
ration. As regards the third great process, viz.,
extracting by chlorine, we have explained upon
what principle that is carried out, being, in fact,
like the other two, merely making use of a sub-
stance which, by its great affinity, will seize hold
of the gold and collect it, so to speak.

Of the three processes, the crushing and amal-
gamating with mercury, the smelting and amal-
gamating with lead, and the crushing and absorp-
tion by a solution of chlorine, each is suitable
according to the way the gold is found in the
stone or auriferous material. Rich pyrites or
black sand, or concentrates, require smelting as a
rule, because all the grinding, to whatever degree
of fineness it may be carried, will not
liberate all the gold from the iron and metals, so
that mercury can act on it. Again, crushing by
stampers or grinding in mills will be suitable
where much of the gold is fairly coarse, and, as it
is called, free in the stone. And chlorination
comes in and is useful where gold is free in the
stone, but is so very fine that in crushing in the
ordinary way the mercury can't take hold of it
but is carried away in the sludge or tailings.
Chlorination also is useful in extracting the pre-
cious metal from concentrates, though in this
case it may be found more suitable to sell them
to the smelting works than to treat them by
chlorine at the mine.

Having thus described what may be termed
the principles of chlorination, we now describe
the appliances by which they are carried into
effect. First, the stone is crushed dry, and, as in
the case of the iron-clad reef at Cargo where chlori-
nation is carried on, by heavy steel rollers driven
by steam power. Next the crushed stone is
calcined in an ordinary reverberatory calcining fur-
nace to eliminate all the sulphur and arsenic
which it is advisable to get rid of before treat-
ment by chlorine. Then the calcined crushed stone
is put into a large iron barrel about 8ft long
by about 3ft in diameter, and lined with lead,
because chlorine acts powerfully on iron as it does
on gold and silver, but will not touch lead. A
(On page 25)
sufficient quantity of water is put in the barrel
to make a thin sludge, then a quantity of chloride
lime- that stuff much used as a disinfectant, and
which is simply common lime saturated with
chlorine gas- is put to the sludge, and upon that
a small quantity of sulphuric acid. The barrel
is then closed down air-tight, and made to
revolve very slowly. The acid acting on the
lime evolves the chlorine, which is taken up by
the water, and the chlorine solution takes up the
gold in the stone. After some hours of the barrel
revolving, the whole contents are turned out into
a cask or receptacle and allowed to settle. The
clear liquor is then drawn off, and made to pass
through a cask or vessel partly packed with com-
mon wood charcoal, which, as the auriferous
chlorine solution passes through it, takes the gold
to itself; and upon the charcoal being burned
away, say in an iron pot, the pure gold remains.
This, then, is the chlorination process, which, we
think, our readers- even those quite unacquainted
with chemistry- will clearly comprehend. Whether
this process, admirable as it is in many cases,
should be used at any particular gold mine is a
question for serious consideration. As a rule, the
stamper battery and amalgamation with mercury
and concentrating the pyrites is the best. In
some cases, however, such as the celebrated
Mount Morgan stone, chlorination is of the
greatest advantage on account chiefly of the ex-
treme fineness of much of the gold.


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