# tanks for working with acids



## oro-del-sur (Mar 17, 2013)

Greetings...I joined the forum awhile back, been observing and learning. This is my first post. I am a gold miner by trade, originally from California. I live and work in Costa Rica (20 years now). I am starting a pilot project to evaluate the potential of recovering gold and silver values from old mine waste (natural ore tailings) as well as the waste produced by the numerous artesian miners still working with mercury. I will use physical concentration means for primary recovery. Initial tests and observations show recoverable free particle values, however, there are also recoverable values in complexed form, mostly gold bearing sulfides. The magnetite also carries values. Thus, the need to employ leaching methods for final recovery. I have limited experience with leaching. I recently received a copy of Hoke's book and have ordered Amman's book, and plan to follow advised protocol as a beginner. After initial practice, I will have a need to batch leach 1-5 gallons of concentrate, and then increase that volume to batch leach 20-25 gallons of concentrate. My questions is what type (material), design and size of tanks / vats can be used to treat 20-25 gallons of concentrate. And then recommended methods for process handling of the solids and liquids such as pouring, filtering etc.  I am accustomed to fabricating much of my own equipment to save costs but need some initial guidance on design, materials and methods. 

Logically, I have yet to determine what leach method(s) will be best suited for my application however I assume using strong acids, possibly AR or a more user friendly formula such as SSL. I am shipping a container here from the states very soon and would like to include critical leach equipment to have on hand when the time comes. Unless I can find the materials locally. I have access to plastic barrels used to store industrial chemicals. Are these suitable? 

Thanks in advance!


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## gmiller (Mar 18, 2013)

Blue barrels will indicate on the side if they are suitable for acids. If it doesn't say so , don't use it for that purpose.


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## Geo (Mar 19, 2013)

most HDPE will hold up pretty well to most acids. ive seen nitric shipped in the black HDPE containers and concentrated sulfuric as well.as in anything else, test a sample piece in the acids you will be using at a wide range of temperatures. if the plastic holds up well to the acids at higher temps, its a pretty good bet it will hold up well at lower temps.


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## oro-del-sur (Mar 19, 2013)

Action Mining sells leach tanks for their proprietary CLS leach but are a bit pricy..$250 for a 55 gal "poly" tank (see attached).


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## oro-del-sur (Mar 19, 2013)

Thanks Geo...I'll follow up on that advice. Actual liquid / solid capacity would be what, maybe 50% of the tank size? 

Leaching natural ores is not covered in Hoke, nor did I see examples of tank/vat leaching other than the section on large refineries. Searching the net gives bits and pieces of info but so far I have found nothing comprehensive. Where might I find more info on setting up a tank leach system? ...and related handling and processing issues i.e. pouring / draining liquids and solids, rinsing and filtering, agitation/stirring options etc. I have Charles Butler's leaching manual which describes their nitrate leach method, and the use of their proprietary Pachuca Tank on a lab / testing scale. Their tank uses two pumps to agitate the slurry in a manner that creates an "abrasion effect", in theory enhancing the reaction. 

I would consider paying a reasonable fee for a design concept, say using a 55 gallon tank as an example. A gravity system (draining) would be most practical versus pouring or pumping. Ideally, a setup that can be used with a variety of leaches included AR. SSN is probably my first choice since it's fairly user friendly and I understand that it is an aggressive leach for natural ores. I will not be leaching head ore. I will be leaching concentrates of head ore as well as waste (tailings) from old mine sites. 

I assume their are members of this forum that have been down this road. Would I benefit by posting to other sections? 

Thank you...all help is much appreciated!


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## butcher (Mar 23, 2013)

Most gold mined is the free gold which can be recovered with crushing and gravity methods, we have better equipment today for capturing and separating the fine gold than they had in the past.

sulfide gold ore can be froth floated for concentrating, most all leaching should be done on concentrates, it does not make sense to leach tons of ore, to just remove base metals, sulfide ore will need roasting before leaching, some times the ore is also treated in the roasting stage to prepare the ore for a certain leach, like when they used salt in the roast, to prepare the gold for a chloride leach.

Hokes is a very good book you should study, it is more based on refining gold from higher grade scrap mostly jewelry, not for mining, but it will also be very beneficial to understand what she teaches it can even be a help when mining. 

C.W.Ammens book is geared more towards mining it also covers some refining also, it does not go into great depth on each subject but covers a wide range of topics, it is a very good book,.

You can also find many documents, and books on the forum and on the internet that will cover more in depth certain subjects on mining, some of the old mining books have a ton of information, and with the internet these books are readily available, it is like having a whole library at your fingertips.


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## oro-del-sur (Mar 29, 2013)

To frame my application a bit better:

I am a miner by trade, mostly alluvial ore bodies. I have a fair amount of experience in heavy particle concentration using mechanical means. Yes, flotation is the most practiced method of concentrating sulfides and I may include a flotation component at some point but as a secondary process, post concentration. I will be using a proprietary design for two types of concentrators...a Muliti Helix Spiral (horizontal) and a Low-G Centrifuge (also a horizontal configuration). I am a former partner, one of the two original partners of Oro Industries in California who continued development of these concentrators originally invented by Bill Martin of Tri-R Engineering back in the late 70's and early 80's along with his son in law Paul Clift. 

So, I have the mining and primary recovery end covered. Leaching and refining is sort of the missing component to my field of work where we would normally do a primary smelt and then sell the dore bullion to a refinery. I have searched for equipment design ideas (tank leaching) but find very little in the public domain, only bits and pieces...no functional setup designs for leaching, pumping, filtration etc. I have Action Mining's CLS manual which does offer good information but is mostly geared towards their proprietary system. 

*Ore Concentrates*: I will be leaching concentrates only, not head ore. The portion of the concentrate to be leached will have been stripped of most of the free gold, ferrous and magnetite, residual mercury etc i.e. the richest percentage of the final concentrate which would either be smelted or treated separately. My initial testing shows the mags and some of the ferrous are gold bearing as well as the residual mercury. 

*SSN:* Of the most common and known leach recipes I am leaning towards SSN since it's fairly low cost, available ingredients, simple and user friendly, low toxicity...but yet an aggressive leach. I have Walter Lashely's article published in 1994 in the California Mining Journal and also a paper written by him when he worked at The American Society for Applied Technology. Does anyone know of any follow up work or publications by him? Or other information on the use of SSN with natural ores ? 

*Method theory & prototype* - Maybe a column (4"-6" PVC pipe x 2'-3' tall) set up to create a slow trickle or percolation effect down thru the column - theoretically the ideal flow could be achieved by experimenting with different filter porosities at the bottom of the tube...and then recirculate the leach back to the top of the column. What type of pump would work best for this? ...a vacuum pump maybe? 

The method is straight gravity however the column could be flipped over every hour or two to "resettle" the ore which should help keep the material porous and help prevent packing, dead spots and clogging. Concentrates are fairly clean (washed) by nature so I theorize a "gravity column" method being very practical. Or, stack 5 gal buckets...or barrels. 

Applying heat would aid the reaction...maybe by placing a ceramic heater inside the leach vessel somehow? Or possibly a heat exchanger in the recirculation loop? (keeping in mind the leach vessel is plastic) 

So, any ideas for a pumping method and a heat method would be greatly appreciated. 

thanks in advance!


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## Lou (Mar 29, 2013)

Try www.usplastic.com


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## oro-del-sur (Mar 29, 2013)

thanks Lou...I'll check it out


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## oro-del-sur (Mar 30, 2013)

To all...I have an initial concept (attached drawing) to leach & precipitate as a "single process" - intended for primary recovery of complexed values in ore concentrates: SSN leach + electrolytic cell. However, I do not begin to understand the chemistry / reaction of the SSN in the cell. I am in need of some opinions to judge if this is feasible. The design in the drawing is for 5-10 gallons of ore concentrate.

View attachment CLCP.pdf


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## jimdoc (Sep 25, 2013)

ShayneThill said:


> Lou said:
> 
> 
> > Try http://www.usplastic.com
> ...




ShayneThill,

Don't bother adding a spam link to this post.
You are caught!


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## FrugalRefiner (Sep 25, 2013)

Come to Columbia! :twisted: 

Dave


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## The Refiner49er (Jan 18, 2014)

I am curious if anyone can comment on the feasibility of electrolytic recovery in an SSN leach circuit? The presence of the nitric species seems to me would defeat formation of metal solids and/or redissolve the values?


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## butcher (Jan 19, 2014)

I am curious if anyone can comment on the feasibility of electrolytic recovery in an SSN leach circuit? The presence of the nitric species seems to me would defeat formation of metal solids and/or redissolve the values?

The SSN leach is basically a poor mans aqua regia solution, where nitric acid could give similar results, and can be dealt with in similar matters, basically you could use electrolytic recovery, but when you deal with ore, you can be dealing with very complicated mixtures, and complex chemical mixtures, and the leach from the ore may become a problem for and electrolytic recovery itself.

With ore many times a process for recovery will have to be developed around that particular ore, it is not like one method or recovery will work, or leach, values from every type of ore, the process to extract metals from an each type of ore can be different, just as the chemistry of one rock will be very different than the chemistry of another rock, or type of ore, the methods of treatment and your chemistry used in extractions of values may need to be different for each type of ore, and the extraction method may have to be developed around the particular ore you are dealing with.

Electrolysis may work, but I believe a metal replacement reaction would work much easier and better, to remove values from solution.

Cyanide was one of the most used and better leaches for ore, many of the other leaches were developed to try to find another safer or different type of leach to try to replace cyanide, some of these leaches you will find very little information about, as many times they were not used to the extent of cyanide, and many of these other leaches really have not been proven to work all that well, some of these other leaches can be very difficult to use, even if they will extract values from a particular ore, they may be very critical in pH or oxidization potential or having a catalyst involved in solution, which may be very hard to keep the leach in the working parameter to where the leach will leach the values from the ore.


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