Things which may be of interest to members
- Thread starter Deano
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Deano,
At the hypochlorous acid leach "zone", confrim a high density plastic tank (air tight tanl) can be opened for ph checks, with out interfering with the leach process.
if u were out prospecting hundreds of miles away in gold land and realize ur ph meter battery is dead. and the leach is already in water, a bag full of litmus paper is in the car together with its color chart coresponding to each ph scale from 1 till 14. how would u use litmus paper here?
Deano,
At the hypochlorous acid leach "zone", confrim a high density plastic tank (air tight tanl) can be opened for ph checks, with out interfering with the leach process.
if u were out prospecting hundreds of miles away in gold land and realize ur ph meter battery is dead. and the leach is already in water, a bag full of litmus paper is in the car together with its color chart coresponding to each ph scale from 1 till 14. how would u use litmus paper here?
labalkeny, please do not use text lingo on the forum. Many of our members have to use translation software to read, and things like "u" and "ur" do not translate well.labalkeny said:
Dave
Thank you. We all appreciate the effort. 8)
Dave
Dave
A pH 7 saline hypochlorite leach evolves very little free chlorine, the amount is so small that it will not affect the leach if this chlorine is lost.
Try making up a leach solution with 20% salt and 5 grams per litre calcium hypochlorite at pH 7- 8 (equals pH 8-9 on a meter), sniff it carefully and see what level of chlorine there is in the air. Usually you have to try fairly hard to smell any chlorine.
Dip the litmus paper in the solution and read the pH from the colour chart. You need to be quick, the leach will bleach the paper colour.
This gives you a direct comparison between meter pH and paper pH.
Deano
Try making up a leach solution with 20% salt and 5 grams per litre calcium hypochlorite at pH 7- 8 (equals pH 8-9 on a meter), sniff it carefully and see what level of chlorine there is in the air. Usually you have to try fairly hard to smell any chlorine.
Dip the litmus paper in the solution and read the pH from the colour chart. You need to be quick, the leach will bleach the paper colour.
This gives you a direct comparison between meter pH and paper pH.
Deano
Thanks Deano.
If I may ask. how is leaching at a specific pH, 7&8 different from
" Simultaneous sulfide oxidation and gold leaching of a refractory gold ore, by chloride hypochlorite solution, an Article in mineral engineering's September report.
is there no simultaneous oxidation and leach at ph7&8? this guys start there Leach from pH 11 down to around 8.
And how does one tell all the Ag and Au has been leached by the HYPOCHLORITE system and in how much time?
If I may ask. how is leaching at a specific pH, 7&8 different from
" Simultaneous sulfide oxidation and gold leaching of a refractory gold ore, by chloride hypochlorite solution, an Article in mineral engineering's September report.
is there no simultaneous oxidation and leach at ph7&8? this guys start there Leach from pH 11 down to around 8.
And how does one tell all the Ag and Au has been leached by the HYPOCHLORITE system and in how much time?
forgot something.
leaching in a large concrete tank.
is it necessary to separate the pregnant solution from the rest of the ore and silt prior to contacting this solution with activated carbon?
recovery in the cynide system with carbon is an adsorption process while in the gold and silver chloride system its a reduction process.
if the mud/ silt is not separated from the solution. for the HYPOCHLORITE system , won't values drop back into the silt and ore?
leaching in a large concrete tank.
is it necessary to separate the pregnant solution from the rest of the ore and silt prior to contacting this solution with activated carbon?
recovery in the cynide system with carbon is an adsorption process while in the gold and silver chloride system its a reduction process.
if the mud/ silt is not separated from the solution. for the HYPOCHLORITE system , won't values drop back into the silt and ore?
Spending a couple of minutes with the Preview button would save everyone else a lot of time trying to parse that.
Davelabalkeny said:
kurtak
Well-known member
labalkeny said:
I think what Dave was trying to tell you is please take the time to proof read your post (by using the preview button) before submitting your post - that way you can fix/edit any problems in your post "before" submitting it - such as the problem of words run together like the following
I had to "struggle" reading that "before" scrolling down to see that Dave had edited it to make it readable
Please go back & "edit" your original post labalkeny so others don't have to "try" reading it "before" figuring out that Dave edited it to make it readable
Kurt
Frugal I appreciate the correction and I have also done some correction on that post. I should also say I really spent a lot of time trying to fix such errors but I realized. when a lot of time is spent typing, the whole text body can't be submitted.
I am using a phone and out in the Field.Not sure if this only happens to me .
But trust me I typed several texts many many times and it just can't be submitted when you spend lots of time going through what is written. For even this may not submit.
I am using a phone and out in the Field.Not sure if this only happens to me .
But trust me I typed several texts many many times and it just can't be submitted when you spend lots of time going through what is written. For even this may not submit.
Labalkeny, I appreciate your efforts to fix your previous post and to get it right to begin with. I don't use a phone to post, so I can't really relate to the problems it might create when posting. Since we have members from around the world (like you), we ask that members make their best efforts. Even small errors can result in great difficulties when using translation software.
I type my posts on a laptop. I proofread what I've typed in the edit box. Then I always use the preview button and read it again. I almost always end up correcting something or adding some clarification. Then, once I submit the post, I read through it again. I know that's extreme, but it's just how I am.
Dave
I type my posts on a laptop. I proofread what I've typed in the edit box. Then I always use the preview button and read it again. I almost always end up correcting something or adding some clarification. Then, once I submit the post, I read through it again. I know that's extreme, but it's just how I am.
Dave
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I know we're helping this new chap here with forum posting and it's a great thing to do however is there a way we can avoid clogging up this brilliant thread with this Dave?
Jon, this thread has already been cleaned up and archived in the Library. From time to time, as new posts add to the content, and time allows, one of the moderators will undertake to copy the thread to an area where we can work on it, move the new, deserving posts to the Library copy of the thread, then clean up the detritus of the process.anachronism said:
This is an open forum. Every member is free to post wherever they choose. We do ask that they try to choose an appropriate section of the forum when creating a new thread. We also ask that if they study the forum and if they have questions about a thread, they post their questions in that thread rather than starting a new one which simply adds to the fragmentation of information.
When we add a thread to the Library, we provide a link to the original thread and Encourage members to add to the original thread.
This is not the first time you have felt the need to question the way I, or other moderators, post or moderate this forum. If you have a problem with the way I post or carry out my responsibilities as a moderator, I suggest you contact the board administrator, Noxx, and voice your complaints to him.
Dave
- Joined
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- Messages
- 3,496
Good heavens where did all that come from? I was asking for your help and advice not having a go at you Dave. I'm really not sure how you managed to read my post in such a negative light because being negative wasn't the intention.
The article on sulfide oxidation and gold leaching is a research article, not a how to actually do it best article.
All hypochlorite leaches will attack sulfides.
At high pH values the hypochlorite is in the form of the hypochlorite complex and will attack the sulfides at the slowest rate of any of the hypochlorite forms.
Around pH 8 the predominant form of the hypochlorite is as the hypochlorous complex, this will attack the sulfides at the fastest rate of any of the hypochlorite forms depending on the agitation supplied.
Around pH 3 and below, the predominant form of the hypochlorite complex is as free chlorine, not recommended for any leaching process on safety grounds.
The higher the pH for any hypochlorite solution, the less free chlorine that is evolved, but always some will be evolved.
At pH 8 you can smell weak levels of chlorine, at pH 11 the smell is very weak but still present.
Note that with the 20% level of salt present the true pH levels will read about 1 unit lower on a meter, so true pH 8 will read pH 7 on a meter.
If you are running a saline hypochlorite leach at any pH where there are sulfides present you will have a lowering of the pulp pH caused by the formation of sulfuric acid during the oxidation of the sulfides.
Any variation in the sulfide levels will cause a corresponding variation in the final leach pH.
The best process route is to monitor the pH during the leach procedure and adjust the pH to around 8 with caustic soda on a continuous basis.
At the same time you are monitoring the Eh of the pulp to ensure that you have not run out of hypochlorite in the leach.
The sulfides will be a major consumer of the hypochlorite so you could be adjusting the pH to 8 but have no hypochlorite left to do any further leaching.
Good luck if you would prefer to hope that the pH and eH levels will miraculously end up at pH 8 with all gold in solution, just because they had a result does not mean that this will always occur.
The gold and silver in solution levels are read on AAS, this is the only easy way to do this.
Leaching is continued until there is no rise in the gold in solution levels, at this stage consult your clock for leach times.
Deano
All hypochlorite leaches will attack sulfides.
At high pH values the hypochlorite is in the form of the hypochlorite complex and will attack the sulfides at the slowest rate of any of the hypochlorite forms.
Around pH 8 the predominant form of the hypochlorite is as the hypochlorous complex, this will attack the sulfides at the fastest rate of any of the hypochlorite forms depending on the agitation supplied.
Around pH 3 and below, the predominant form of the hypochlorite complex is as free chlorine, not recommended for any leaching process on safety grounds.
The higher the pH for any hypochlorite solution, the less free chlorine that is evolved, but always some will be evolved.
At pH 8 you can smell weak levels of chlorine, at pH 11 the smell is very weak but still present.
Note that with the 20% level of salt present the true pH levels will read about 1 unit lower on a meter, so true pH 8 will read pH 7 on a meter.
If you are running a saline hypochlorite leach at any pH where there are sulfides present you will have a lowering of the pulp pH caused by the formation of sulfuric acid during the oxidation of the sulfides.
Any variation in the sulfide levels will cause a corresponding variation in the final leach pH.
The best process route is to monitor the pH during the leach procedure and adjust the pH to around 8 with caustic soda on a continuous basis.
At the same time you are monitoring the Eh of the pulp to ensure that you have not run out of hypochlorite in the leach.
The sulfides will be a major consumer of the hypochlorite so you could be adjusting the pH to 8 but have no hypochlorite left to do any further leaching.
Good luck if you would prefer to hope that the pH and eH levels will miraculously end up at pH 8 with all gold in solution, just because they had a result does not mean that this will always occur.
The gold and silver in solution levels are read on AAS, this is the only easy way to do this.
Leaching is continued until there is no rise in the gold in solution levels, at this stage consult your clock for leach times.
Deano
Just a question regarding the Hypochlorite leach.
I found references that states it can leach both Gold and Silver.
Do anyone here have a explanation on how this can be done, and why the silver do not form AgCl immediately?
How about PGM's ?
I have seen a video from one of the biggest PGM mines in South Africa and they used HCl/Cl in pressure tanks but will it leach PGms as a simple Hypochlorite leach?
I found references that states it can leach both Gold and Silver.
Do anyone here have a explanation on how this can be done, and why the silver do not form AgCl immediately?
How about PGM's ?
I have seen a video from one of the biggest PGM mines in South Africa and they used HCl/Cl in pressure tanks but will it leach PGms as a simple Hypochlorite leach?
