GotTheBug said:
In my not so infinite wisdom, I decided to put incinerated IC's into the furnace, no collector metal, thinking the other metals already contained in the ashes might collect PM's successfully.
Equal volume of ashes and borax, and added half volume (of borax, store bought not anhydrous) of sodium carbonate.
After the pour, I ended up with beads, rather than a cone, in the bottom of the mold, about the size of a pencil eraser.
GotTheBug
I see a couple problems here - first is not enough collector metal & (if I understand it right) your flux mix/ratio (& also that you may not have had your flux "well mixed" with the ash)
The two most important things in smelting are that you have enough metal in the smelt so that when everything becomes molten there is enough metal contacting metal to allow it to form large enough molten beads/globs that will flow & settle down through the flux - in other words there needs to enough metal that metal is in close proximity to metal in order for it to make contact & collect together with the surrounding metal as it becomes molten --- to achieve this you need at least 30% of your total smelt load to be metal --- your "smelt load" is the total combination of ash, flux & metal - so of that total combination you need right in the ball park of 30% of it to be metal
If you did not get your metal to settle to a nice full metal cone in the pour but instead got eraser size beads - then most likely your slag is also full of smaller beads - lots of smaller beads - some being "
very" small --- you need to do a re-melt of your slag - you want to put your slag back in the furnace - bring it up to temp & let it become molten "first" - then once the slag is molten - add your collector metal (assuming you are using copper) adding the copper "after" the slag becomes molten reduces the amount of copper that oxidizes during the smelt allowing for better collection & less copper oxide going off into the slag
The other thing (& this is "very" important) is that when molten - your flux needs to runs fluid - "very" fluid - this is so that during the smelt you have "good" circulation taking place in the crucible - in other words your molten flux/slag needs to be thin enough that it has a "circulating" rolling boil motion to it so that small beads can move, bump & contact one another to collect into large enough beads to settle to the bottom of the crucible in a pool of molten metal
If your molten flux/slag has a bubbling/sputtering action to it - it is to thick & therefor not circulating & therefor not allowing ether popper collection &/or settling --- it needs to be thinned --- this can be helped (to a degree) with the addition of more soda ash - however I highly recommend using a little fluorspar - it doesn't take a lot of fluorspar
The basic recommended "starting" flux is 50/50 borax/soda ash - personally when making up my flux (for IC chips) I go with about 40/60 borax/soda ash & for every 3 cups of this flux I add one "heaping" table spoon fluorspar --- then I also mix up a flux of just soda ash & some fluorspar - one "level" table spoon fluorspar per cup soda ash --- then if my smelt is not running fluid enough I will make additions of this flux till it gets a good fluid circulating motion going
You need to "mix" your starting load of flux to ash ratio "at least" with 2 parts flux to 1 part ash - if not 3 flux to 1 ash --- this depends somewhat on how concentrated your ash is going into the smelt --- in other words how much of the ash you have washed off before going to smelt - the more ash you have going into the smelt the more flux you need in the smelt --- & you need the flux "well mixed" with the ash when you load the crucible
Keep in mind that when going with the smelting method of recovering you gold bonding wires from IC chip ash - you then need to part the gold from your collector metal --- Chemical leach parting is NOT the way to go because (1) you are going to create a huge amount of waste dissolving away the collector metal & (2) because the ratio of collector metal to gold is so great you are going to end up with "ultra" fine gold that will be hard to settle &/or filter --- you really need to run it in an electrolytic parting cell & then treat the anode slimes for the recovery of the gold from them - or sell your smelted dore metal to a refiner that deals with such & they will only pay around 80 - 85% of the gold --- but you create no chem waste other then your slag
Now here's the fun part: I was thinking that tin would be a primary metal to deal with, and that I could take the beads, boil in HCl to remove the tin, and leave primarily PM's and a bit of copper
I am sure you had at least "some" tin in your final smelted dore metal - the reason the HCl did nothing to remove it is because it is "alloyed" with what ever other metals are in the final smelted dore metal (copper, nickel, zinc, silver, gold, cobalt, iron, etc) in order for the HCl to dissolve the tin - the tin would need to be the predominant metal & predominant by "a lot"
Another thing to think about when smelting is that you can use silver as your collector metal instead of copper - I mention this because if you intend to part your gold from your collector with chem leaching (nitric) it will take MUCH less nitric to do so --- 1 gallon of (68 - 70%) nitric will only dissolve about 2 pounds of copper but it will dissolve about 8 pounds of silver --- also it is easier to set up & run a silver cell rather then a copper cell & a silver cell runs faster then a copper cell --- the down side to using silver as your collector is having a lot of silver on hand & tied up for use as your collector
Hope this helped
Kurt
