SamW
Member
Re-opening a 150 year old Gold Mine and solving the refining process
Hi All,
This thread will be to share my progress in an attempt to re-open an old gold mine and solve the refining process specific to my ore.
About myself, I am an industrial electrican and instrument technician by trade, and have spent a bit of time working as an operator / maintainer in the mining industry. I have worked both underground and above, and have had exposure to most types of machinery, including looking after all electrical/mechanical items in a large CIP plant.
By no means am I an expert in what I am attempting here, but I love a good challenge and look forward to any comments or suggestions you may have along the way!
This is a personal project and entirely self funded, so the budget is tight. Luckily I have some existing machinery to work with to get me started.
The Mine:
Originally discovered in 1869, it has historically produced around 4000oz of gold, mostly from running the quartz ore through a ten-head stamp and over a mercury amalgam plate.
The quartz orebody averaged 1metre wide and was mined to a depth of 30metres over a strike of 100m.
Back then, all the small underground mines in this area ran into difficulty as they got towards the water table and encountered sulphide ore. This mine was no different and was likely the reason it shut down. Luckily there is still enough unmined shallow ore to get me started before moving on to the more difficult sulphides. The surrounding mines in the area who went to cyanide recovery all reported good success, however this is currently not an option for me on this site right now.
The Crusher:
Already on site was a stamp mill consisting of 5 x 500kg stamps. I managed to get the whole thing running again and have fitted a 0.6mm screen on both discharge ports. With this screen I only get a total throughput of about 180kg/hr. This is not really enough to run a good profit, however it will do for now to get started and work out a reliable gold recovery method. It is fed by an ore bin with 50mm grizzly screen and a vibrating feeder into the mortar box of the stamp mill.
The Wilfley Table:
This table was apparently saved from a mine scrap heap and re-furbished by the previous site owner. This has been my biggest headache so far, mainly as I have no experience with these and finding support has been very challenging. Initially I could not get this table to perform at all, the ore would not travel over the first riffle, instead it would just go lengthways across the table! I later got ahold of some engineering drawings and found out all the riffle heights were wrong! many days were spent on a belt sander correcting this. I have now got it to a stage where it is producing a nice line of clean concentrate after many weeks of trial and error.
I found that a smooth and even water distribution was extremely critical and the original timber water feed trough was just too finicky to mess with. I replaced it with PVC pipe and holes drilled at 25mm spacings. This was a huge improvement but was having still having issues at the corner discharge end of the table. I added an experimental short spray bar at the corner which worked quite well in keeping the concentrate travelling properly, however I don't think this should be necessary if set up properly.
I still need to work on tuning the table correctly - spray bars need refining more, and I need to confirm the correct tilt and shaking frequency. I also believe my concentrate line may need to be discharging higher up the table (not at the corner?)
The Wave Table:
I purchased an Action Mining Wave Table to trial as a production table, it does do its job but I found it extremely sensitive to variations in feed or water and can actually loose gold quite easily if conditions are not perfect. I find it great for doing concentrate cleanups so that will be its purpose from now on.
Results so far?
At this stage I can produce a clean concentrate of sulphides and free milling gold. The next step is to further tune the table for correct operation and better recovery. I also need to perform proper lab testing to confirm how much I am losing to tails.
This morning I ran about 400kgs of ore through the plant, here are some photos and the end result:
Hi All,
This thread will be to share my progress in an attempt to re-open an old gold mine and solve the refining process specific to my ore.
About myself, I am an industrial electrican and instrument technician by trade, and have spent a bit of time working as an operator / maintainer in the mining industry. I have worked both underground and above, and have had exposure to most types of machinery, including looking after all electrical/mechanical items in a large CIP plant.
By no means am I an expert in what I am attempting here, but I love a good challenge and look forward to any comments or suggestions you may have along the way!
This is a personal project and entirely self funded, so the budget is tight. Luckily I have some existing machinery to work with to get me started.
The Mine:
Originally discovered in 1869, it has historically produced around 4000oz of gold, mostly from running the quartz ore through a ten-head stamp and over a mercury amalgam plate.
The quartz orebody averaged 1metre wide and was mined to a depth of 30metres over a strike of 100m.
Back then, all the small underground mines in this area ran into difficulty as they got towards the water table and encountered sulphide ore. This mine was no different and was likely the reason it shut down. Luckily there is still enough unmined shallow ore to get me started before moving on to the more difficult sulphides. The surrounding mines in the area who went to cyanide recovery all reported good success, however this is currently not an option for me on this site right now.
The Crusher:
Already on site was a stamp mill consisting of 5 x 500kg stamps. I managed to get the whole thing running again and have fitted a 0.6mm screen on both discharge ports. With this screen I only get a total throughput of about 180kg/hr. This is not really enough to run a good profit, however it will do for now to get started and work out a reliable gold recovery method. It is fed by an ore bin with 50mm grizzly screen and a vibrating feeder into the mortar box of the stamp mill.
The Wilfley Table:
This table was apparently saved from a mine scrap heap and re-furbished by the previous site owner. This has been my biggest headache so far, mainly as I have no experience with these and finding support has been very challenging. Initially I could not get this table to perform at all, the ore would not travel over the first riffle, instead it would just go lengthways across the table! I later got ahold of some engineering drawings and found out all the riffle heights were wrong! many days were spent on a belt sander correcting this. I have now got it to a stage where it is producing a nice line of clean concentrate after many weeks of trial and error.
I found that a smooth and even water distribution was extremely critical and the original timber water feed trough was just too finicky to mess with. I replaced it with PVC pipe and holes drilled at 25mm spacings. This was a huge improvement but was having still having issues at the corner discharge end of the table. I added an experimental short spray bar at the corner which worked quite well in keeping the concentrate travelling properly, however I don't think this should be necessary if set up properly.
I still need to work on tuning the table correctly - spray bars need refining more, and I need to confirm the correct tilt and shaking frequency. I also believe my concentrate line may need to be discharging higher up the table (not at the corner?)
The Wave Table:
I purchased an Action Mining Wave Table to trial as a production table, it does do its job but I found it extremely sensitive to variations in feed or water and can actually loose gold quite easily if conditions are not perfect. I find it great for doing concentrate cleanups so that will be its purpose from now on.
Results so far?
At this stage I can produce a clean concentrate of sulphides and free milling gold. The next step is to further tune the table for correct operation and better recovery. I also need to perform proper lab testing to confirm how much I am losing to tails.
This morning I ran about 400kgs of ore through the plant, here are some photos and the end result: