Well Deano, that was a lot to digest. I always send my assays to American Assay because I'm not an assayier. The one vien I'm on Assaed at 6oz. Per ton. The other vien I'm on Assaed at 11oz pet ton. My goal is to just crush the rocks and than table the cons and smelt it. I have been using a RP-4 table, but now I bought a MSI 255 table like on the Gold rush show, I just learned that you have to run different mesh sizes on the table, you just can't take the cons from the roughing table and put it on the MSI table. I'm hoping I can use gravity separation for my small operation. Deano mentioned not to take a magnet to the cons, why is that? Please explane. My last run I had 19lbs of cons off my table #1. I than roasted it and than ran a magnet thru it. I was left with 5 1/2 lbs. of cons. I did save the roasted cons that stuck to my magnet just in case there is gold in there. At the end of the day, I just want to smelt my own cons. This shouldn't be rocket science, but it's so much harder than one would think.
Smelting high sulfides Gold concentrates
- Thread starter Jimijoe
- Start date
Help Support Gold Refining Forum:
Human nature being what it is, there is a great difficulty in sampling a vein to get a representative sample for assay.
The temptation is always to cherry pick the better looking pieces and reject the not so good looking pieces.
Unfortunately if you mine the vein you will have to mine all of the vein material plus any country rock required to give you working room in the drive.
If you are doing it all by small scale hand mining then you can hand sort the mined ore to give you an upgraded semi concentrate.
Whether you are going to use the run of mine ore or the hand picked semi con you will have to mill it to release the sulfides.
This is one area where it will be much better and easier to have someone who has done similar tests to carry out milling of small parcels of ore, say around 0.5 to 1 kg at a time to see what grind size you need to mill to to liberate the sulfides.
The degree of sulfide liberation is determined by doing a float on the milled product and comparing the quantities of sulfides recovered for each grind size.
It shouldn't matter whether you have a friend or a commercial lab carry out this testing but it really has to be done.
You make the small parcels of ore by putting a larger quantity, say 20 kg of run of mine ore, through a jaw crusher to get a minus 6mm or minus 10mm product, depends on what the crusher can get it down to.
The crushed material is thoroughly mixed and then the smaller samples are split out for the testing.
The above will only give you the milling size you have to aim for but it will also allow you to assay the products to see where the gold actually is in the ore.
6 oz ore is rich and rare, what you need to know is where in the ore is the gold.
If it is just in the quartz then you have a different processing route than if the gold is either just in the sulfides or in a mix of quartz and sulfides.
It would be unusual to have 6 oz ore where the gold was just in the quartz and not showing as large pieces but I have seen this occur.
Assuming that the gold is in the sulfides and you can recover the sulfides by tabling (this is why you have to do the above tests) you then have to find out how you have to run the table to get the best recovery of sulfides.
This starts with the rougher table, depending on the grind size required in the mill you will run hundreds of kilos per hour over the table for a coarse grind on a full size table to tens of kilos per hour for a fine grind on the same table.
No matter what table you use it is vital that you have the correct grind size and tabling rate.
If you have lost values on the rougher table you are not magically going to get them back on the clean up table, those values are now in your tailings dam.
Depending on the type of magnet used some sulfides will be attracted to a magnet, this attraction will be fairly weak but still apparent.
It is worth testing to see if your sulfides as is after milling can be separated magnetically with a high strength magnet.
Depending on the type of sulfides you have and how you roast them there is a good chance that you will turn non-magnetic sulfides into magnetic roasted oxides.
If you carry out a magnetic separation on the roasted material you will remove material which is carrying the gold originally in the sulfides.
Get fire assays done on the magnetic cons and tails to see where the gold is.
I am not trying to tapdance around the processing but when all of the answers relate to unknown material I can only give you general directions.
Deano
The temptation is always to cherry pick the better looking pieces and reject the not so good looking pieces.
Unfortunately if you mine the vein you will have to mine all of the vein material plus any country rock required to give you working room in the drive.
If you are doing it all by small scale hand mining then you can hand sort the mined ore to give you an upgraded semi concentrate.
Whether you are going to use the run of mine ore or the hand picked semi con you will have to mill it to release the sulfides.
This is one area where it will be much better and easier to have someone who has done similar tests to carry out milling of small parcels of ore, say around 0.5 to 1 kg at a time to see what grind size you need to mill to to liberate the sulfides.
The degree of sulfide liberation is determined by doing a float on the milled product and comparing the quantities of sulfides recovered for each grind size.
It shouldn't matter whether you have a friend or a commercial lab carry out this testing but it really has to be done.
You make the small parcels of ore by putting a larger quantity, say 20 kg of run of mine ore, through a jaw crusher to get a minus 6mm or minus 10mm product, depends on what the crusher can get it down to.
The crushed material is thoroughly mixed and then the smaller samples are split out for the testing.
The above will only give you the milling size you have to aim for but it will also allow you to assay the products to see where the gold actually is in the ore.
6 oz ore is rich and rare, what you need to know is where in the ore is the gold.
If it is just in the quartz then you have a different processing route than if the gold is either just in the sulfides or in a mix of quartz and sulfides.
It would be unusual to have 6 oz ore where the gold was just in the quartz and not showing as large pieces but I have seen this occur.
Assuming that the gold is in the sulfides and you can recover the sulfides by tabling (this is why you have to do the above tests) you then have to find out how you have to run the table to get the best recovery of sulfides.
This starts with the rougher table, depending on the grind size required in the mill you will run hundreds of kilos per hour over the table for a coarse grind on a full size table to tens of kilos per hour for a fine grind on the same table.
No matter what table you use it is vital that you have the correct grind size and tabling rate.
If you have lost values on the rougher table you are not magically going to get them back on the clean up table, those values are now in your tailings dam.
Depending on the type of magnet used some sulfides will be attracted to a magnet, this attraction will be fairly weak but still apparent.
It is worth testing to see if your sulfides as is after milling can be separated magnetically with a high strength magnet.
Depending on the type of sulfides you have and how you roast them there is a good chance that you will turn non-magnetic sulfides into magnetic roasted oxides.
If you carry out a magnetic separation on the roasted material you will remove material which is carrying the gold originally in the sulfides.
Get fire assays done on the magnetic cons and tails to see where the gold is.
I am not trying to tapdance around the processing but when all of the answers relate to unknown material I can only give you general directions.
Deano
As far as digging the vein goes, I hired a Geologist to go in the mine I'm working in. He pointed out where to dig on the vein, he also did some sampling while he was there. Being a beginner I didn't want to make a lot of costly mistakes. So at that point we dug this vein for 2days, I took that material and crushed it, than thru the impact mill and on to the table, I understand what your saying about the different sizes on the milling. I'm not sure how to do that when I can't adjust my impact mill to different sizes. I understand screening the different mesh sizes for the table. I was told that I should screen 20/30/50/100 mesh and process them separately on my table. I just bought a used MSI table and it's very hard to operate. So I'm going to start screening my cons. Than back to trying to smelt.
j2000
Well-known member
Jimijoe said:
Thanks for the story....
So any news now jimijoe?
Joel
Cody Reeder
Well-known member
Jimijoe said:
Remember those pieces of cupel that were left after the lead disappeared, did you have a good look at them? Ive had bits get stuck to those and mess up my assay before.
solarsmith
Well-known member
a pin head bead? good job sounds like you did it just right. now dvide the size of your sample into 1000000 grams. and multiply this by the weight of the pin head.
you will know the expected grams per ton 2.200 lbs this is the total pgms in the bead. you will need to do one more step to remove the silver from the bead then weight whats left and you now know the gold content. this is basic assay for gold/silver. when you get your ore to be over 20 oz a ton of gold your ready to do a direct smelt! Bryan
you will know the expected grams per ton 2.200 lbs this is the total pgms in the bead. you will need to do one more step to remove the silver from the bead then weight whats left and you now know the gold content. this is basic assay for gold/silver. when you get your ore to be over 20 oz a ton of gold your ready to do a direct smelt! Bryan
