Good day. My name is Jean Louis, I am mentor in starting gold mines in Tanzania and other African countries. We deal with alluvial and lode ores. Ball mills may be good tools to handle lode ore, and there are also some avoidable pitfalls, such as over-grinding if you do not know the solution for that, or under grinding.

Each ball mill has its input size and possible ranges of output sizes. Some are batch mills which I really do not recommend for serious work. There is no secret that usually the material has to be crushed, normally by using the jaw crusher. Even middle crushing by using a hammer mill may be necessary to have the ball mill in final operation giving you good result with little maintenance.

Material coming out of the ball mill shall preferably and as best available method directly flow to sluices or other gravitational methods if you use such. I am not using chemical methods, but I know companies that are leaching gold after its discharge.

Ball mill is always usable in mining.

I suspect that you are primarily referring to recover of the contents left in the ball mill?  If there was free milling gold in the original feed to the mill, there will likely be metallics that are trapped in the liners and lifters.  When we have replaced liners, we routinely cleaned and recovered the residuals in the mill.  I could elaborate if you could share more of your specific suspicions of the remaining residues or the history of the ball mill use.

I have been a mill superintendent in large tonnage free milling gold ore plants in my past.

the contents I am looking to recover are many large plastic drums filled with chemicals and material. many barels are filled with a cemented hard packed material where the moisture or chemicals have most likely evaporated and some are still a mix of liquid and material and some are pure liquid. I have panned down samples and it is approximately 95% bright yellow pyrite with a high gold content (I found theyre assay records).  I noticed someone in the last 20 years has also found this site and they packed in a power source and cut small holes in the bottom of a couple of the barrels with power tools and let the sand and/or liquid mixture most likely nitric acid as I found many barells full pour out onto the ground but there is no evidence of anything on the ground as if they poured it into smaller buckets or onto a filter???. some are full of the mixture that went through the 4 ball mill cylinders, seperators, then finally through a small trommel, into two large cones which emptied into very large barrels. this place was shut down during mid process when the war started, someone flipped the switch while everything was running and abandoned it all.  would there be gold in those barells of nitric acid and if so how would I be able to remove it, did they cut the barrels open and let the lower portion of the nitric acid pour out onto a screen or filter of some sort. I can tell they came back more than once and was also told stories about the barrels having up to 100oz each of left over gold since they were high grading and going so fast, every sample I have taken from all barrels are approximately 90-95% pyritethe remaining 5-10% is pea sized steel balls and ferrous minerals. I also found many barrels of pure liquid which I believe are used nitric acid,

The company was going to or was waiting to do something with these barrels, they are not waste or tailings. 

Why would these barrels be just sat aside inside the building and all along the walls outside, and why would someone purposely cut open and drain some deliberately and NOT by vandalism, they packed a generator in almost a kilometer by hand more than once so is there a possibility of gold sinking to the bottom of those barrels of pure nitric acid or the ones with the sand acid mixture

. I'm sorry I have no idea how recovery is completed as I am a placer miner, the mill is very large from what I remember there was 4 cylinders each was about 12-14 feet tall and 20 feet long, many froth seperators, 4 huge shaker tables all stacked above each other and everything all ened up in these barells once ran through the system, any help would be greatly appreciated as ive been told there could be a lot of gold left there, I have brought 1 and a half five gallon pails of material back to my home and looks like a bucket of gold, I know it was a copper gold mine that was instantly abandoned without notice or warning when the war started

You need to take samples of all of the products, even the liquids and have them assayed by a good lab. You will then know exactly what you have and not be guessing. You will then be able to determine what to do. 

We could help you arrange analytical for the samples of your material if you wish or help review and suggest recovery processes after you obtain assay results.  The nitric acid solutions are unlikely to contain gold as gold does not dissolve in nitric acid alone; however they may contain some silver if it was present.  However, it instead of being nitric acid, the solutions are aqua regia, it could contain gold.  Analysis of the solutions is important to determine.  You probably could get a reading on an AA or ICP OES instrument to quickly get an answer concerning precious metal content or elemental content of the solutions.  If there is sufficient metal present, the solutions can be precipitated and the precipitate fire assayed to give good analytical answers about content.  The pyrite assuming it contains gold (analytical needed) will likely need to be oxidized prior to leaching for extracting the gold.  First get an analysis, then a recovery method can be suggested.

agree with max s. i suggest you temporarily forget about the liquids and take samples of what you believe to be pyrite. remove any ball mill rejects ( small steel balls) and have the pyrite analysed at a lab. you should also make an estimate of the total potential tonnage of this pyrite material , as this would work into the determination of the potential economics of this exercise. be warned tho, this whole exercise might not be as profitable as you hope.

Very interesting Devon. Might be good find. I definitely agree with testing each stream of material. Taking a representative sample is key in projecting the potential value against the individual lots. Once sample is collected you want to ensure that all the organics are roasted off, or any water content is <3%. This would leave you with a dry concentrate, ready to be milled and subsequently reduced into a smaller representative sample for assay. I wouldn't solely focus on the pyrite based materials, any sludge, steel, solutions, all could hold considerable value.

We encounter these scenarios from time to time, and often find a solution for recovery for our clients. 

Regards,
Dan

hello, thank you all very much for the replies.  I contacted an assay lab and am having samples from the barrels sent to the lab to get a g/ton assay done.  If the results come back with high results, how would I personally be able to remove all the gold from the ore at home or on our mine site and what would a profitable g/ton be, we added up an approximate weight of 2-3 tons of material maybe up to 6, there could be a lot of barrels I didn't see, a closer examination of the samples last night showed it is crushed to a dust-sand grain size particles, we have removed all ferrous materials and steel balls, and I have approximately 40kg here at home. 

I have a couple hundred gallons of pure, unopened barrels of nitric acid, and many gallons of "muriatic acid" I believe it is called (if that is a component needed for extraction). 

Do you all think it would be worth it to spend the time and money on extracting the gold myself if the assay quantity is high, and what g/ton would make it worth it, by the looks of it there is no freegold present but may be too fine to see with a jewelers loupe.

My father told me it was possible that I could have missed something when inspecting the mill itself, and the shaker tables may have distributed the freegold into a separate trough which emptied into something else and this material they were storing in barrels could be the material that went off the end of the shaker tables with the access gold that was too fine to recover and were most likely saving to do very large aqua regia baths, which could be the barrels I thought were used nitric acid, I had a friend go look at the liquid and it is a dark brownish black color and not clear inside of black and blue barrels labeled nitric acid, which seems to me like they have added something into that acid that is now dissolved.

From what I remember the line up of barrels were aligned in a row with one end being pure material, and the other end being barrels of that brownish black liquid with the 50-50 mixture inbetween, (almost as if the end ones are ready to extract/all liquid, the middle ones are in mid process and weren't mixed leaving them undissolved, and the end barrels haven't been started yet,

All barrels that have liquids are completely sealed and he said guaranteed no water has leaked inside. and there could be a lot more he did not and I have yet to see.  The first time I went was the longest I stayed and I was young so I didn't have the mining experience or knowledge about mining other than what specific things were (shaker tables, cylinders, trommels..) all i knew when I was a kid was pyrite usually means entrapped gold when in a gold bearing area let alone inside an actual mill so my only thought was I better show this to dad lol, years have passed now and the thought of possibly thousands of dollars sitting there waiting for someone else is making me edgy. it is a very very large building with obviously no power so its next to pitch black inside.  My friend found pictures inside of a camoflauge rolls Royce with a certain countrys flags on it infront of the mill parked beside a large army truck, I found the truck years ago but no rolls royce, also found hundreds of boxes of core samples which were mostly solid yellow and purple pyrite,

Can I do the extraction myself of just the crushed material or will a larqe quantity like that take me a lifetime to extract.  I would like to thank you all very much for your advice and replies, I am a 26 year old placer miner with 6 years minin which obviously cannot work during the winter and this could possibly help pay for some my fuel costs next season, (if it doesn't take 10 years to extract)

   highly unlikely that you could process this material yourself unless you want to start playing with cyanide in your garage.......  which would be highly dangerous to you and everyone else within about a 2-20 mile radius.   if you insist on trying to do something .  research "knelson concentrators" which might provide you with at least an upgraded concentrate which would reduce your transportation costs for moving the con to a buyer.

Great conversation everyone.

Knelson is a curse word around here https://www.911metallurgist.com/equipment/product-tag/iconc/

Devon you have not said where you are, obviously because you do not want others on site, but I'd advise you to look into the environmental regulations where you are.  Disposal of Nitric and Muriatic acid can be very expensive.  Once you have taken possession of a site you are deemed to be responsible, you cannot use the excuse "the other guys left it here."

I feel that you need professional help. With what you have brought up, they were likely using aqua regia which is very toxic. Hire a competent metallurgist to help you so you don't get into trouble. And I also believe "knelson" to be a curse word, very expensive junk.

I agree, attempting to recover the gold content yourself could have some environmental implications, not to mention health and safety. See recent news from Detour Gold, one of their employees died from cyanide exposure last year. 

Also, if you do manage to recover the gold content, and produce a concentrate, you will still require a refinery to treat the final product. The difference in cost from a sending a dry con you produced, to sending the material "as is" is likely ~5%. 

Hello everyone, thank you all for the replies. I recently borrowed a microscope from a friend to look at the sample of pyrite from the mill for the very first time.  I did some further research about the mill process and pictures from the mill itself. There were four shaker decks inside built onto the mill 5ft wide 12ft long all stacked above each other but in the pictures I cannot see where the free gold and sulphides went after the table process. Under the microscope the sample seems to look like it is the sulphides and microscopic gold that went off the end of the shaker tables. When I took my car key and dipped in into the sample and sprinkled it on the glass slide it was instantly noticeable that it was laced with free gold. At first we thought it was just a yellow pyrite but lots seemed a lot smoother and had rounder edges so I grabbed about 1 cup of nitric acid and added a level teaspoon of the sample. Approximately 2 minutes after stirring it started boiling and fizzing and was emitting orange reddish fumes. (this was done outside and I was 100yds away inside my house during this process, I set up my GoPro to watch the reaction).  

Every couple hours I went upwind and stirred the mix and approx 6hours after adding the sample the fizzing stopped and I was left with a yellow and black dust/sand material and the nitric acid had turned greenish black. It was late and I thought I’d let it sit overnight to further dissolve, went back the next morning and the nitric acid had turned yellow and had small black clumps in the bottom, rinsed with water, dried, inspected under the microscope and you can see all the gold particles are now impossible to mistake for pyrite and some larger pieces of pyrite are half dissolved and where there was pyrite there is now gold, why did the nitric acid not dissolve the pyrite entirely and why did it turn yellow and create clumps of what was the greenish black suspended minerals when I let it sit overnight, I decided to roast the sample and put it back into fresh nitric acid to further dissolve and nothing happened at all like absolutely nothing as if I put it in water, 

if I were to restart the process with a new sample, and once the acid turns greenish black and stops fizzing should I pour it out and add fresh nitric acid and will that make it further dissolve.... did my nitric acid become too contaminated when I left it in overnight and caused it to stop reacting and clump the dissolved solids together,

But now I am left with pyrite that has been roasted and half dissolved with nitric acid, I can clearly see now there is between 2-5% freegold in the concentrate in the barrels once treated with nitric acid... well how I did it anyways. Is there any way I can further dissolve these pyrites and not the gold?

thank you all very much for taking the time to help out a fellow miner and happy holidays 🙂

And the town high school here takes all my used nitric acid and recycles it for free for me as they have to recycle they’re own every so often and since it’s paid for by the school board and I’m recycling such a little amount they don’t care