Geo said:
The copper didn't just appear. The copper was already there at the beginning or it wouldn't be there at the end. When smelting, There are different types of flux. Oxidizing flux and reducing flux. Oxidizing flux will dissolve base metal which is absorbed into the borax and a reducing flux reduces base metal which reports in the final metal casting. If you can't remove the copper before melting, try to use an oxidizing flux but be sure to use enough borax to absorb all the base metal.
vjodhani - I recieved this PM from you last week
Hi kurtak
got you reference from Geo it will be great if you could help me out with this.
viewtopic.php?f=49&t=27534#p290586
I have reached a almost dead end to it.
I am myself a metallurgist and I have seen a lot of precipitation in steels and aluminium but such thing is highly unlikely.Geo says you are very professional in smelting of precious metals.I hope if you could share you knowledge in that thread so that it will help other smelters also.Please share you views.
Regards,
vjodhani
I am not sure I am the one that can help with your problem as my smelting experience is (I believe) different then the process you are dealing with - my experience in smelting is recovering of PMs (Precious Metals) from low grade concentrates (like ore - or in my case electronic components that have been incinerated) where in a collector metal is used to collect the PMs & a "flux" is used to slag off the impurities --- that said - there are other members more experienced then I am - so maybe this post can kick off a more complete discussion to solving your problem
Geo - thanks for the reference to my smelting experience but (again - I believe) - per the underlined in your above quote - we are talking about two different process here
In the smelting we generally discuss here - we use chemical fluxes - such as borax, soda ash, silica, etc.to slag off unwanted elements from the concentrates of processing electronic scrap - which is a lot like smelting the concentrates of ore --- in this smelting process we are primarily slagging off the organics in the concentrate - but as well are able to slag of "certain" metal oxides that for the most part already exist as oxides - while at the same time using a collector metal (such as copper or silver) to collect the PMs in our concentrates & "to some" degree we can control oxidation &/or reduction with variations of our "chemical" fluxes - in other words - with different chemical fluxes we can oxidize (or keep them oxidized) some of the less noble metals & slag them off while at the same time keeping more noble metals such as copper or silver) in there reduction state for a collecter - which results in a dore metal that can then be further refined (copper or silver cell)
on the other hand - vjodhani is trying to "upgrade" - in a smelting process - an already existing dore metal (primarily silver) to produce a better grade anode for his silver cell
Because vjodhani is starting out with dore metal (silver "alloyed" with other metals) normal smelting with chemical fluxes doesn't work --- at best - "some" base metals "may" oxidize at the "surface" of the melt which "may" slag off "some" oxides - but you wont make a notable upgrade in the melt because the (chem) flux is only going to slag off the oxides at the surface of the melt while the majority of the melt remains nothing more then a molten alloy of metals
Hence the use of the BBOC (Bottom Blown Oxygen converter)
:arrow: https://en.wikipedia.org/wiki/Bottom-blown_oxygen_converter
The BBOC works by injecting blown oxygen at the "bottom" of the melt & as the oxygen passes up through the molten dore metal thereby allowing the less noble (base) metal to oxidize - the base metal oxides are then supposed to float to the surface of the melt producing a metal oxide slag (or dross) which is then taken off the top of the melt resulting in an upgrade of the starting dore
This - I think - explains the difference between smelting concentrates with chemical fluxes in order to get a dore metal & that of smelting with the BBOC to up grade the dore
But that doesn't explain the question vjodhani is asking & that may be that I don't fully understand the question - so -----
vjodhani - Metal going into the BBOC is (+/-) 95% Ag
After smelting operation in BBOC is run - metal is tested & test shows (about) 99.6% Ag
But when anodes are cast - & tested again - test shows (about) 99.3% Ag
so a difference of (about) .3% between BBOC test & cast anode test
Several questions
How is the BBOC metal test (sample) taken - (you said; - We are making a button cooling it and then sampling it.)
is the button made by taking a pin tube sample - then re-melting to make a button for testing - or are you dipping a sample from the top of the melt & pouring to a cone mold to get the button - or pouring a sample off the top off the melt & then producing a button from that sample pour - or ???
You said ; - You are right about the first and last sample of anodes.
Are the anodes being poured/cast directly from the BBOC & if so - what is the difference between first & last pour &/or those between first & last
You said; - But why are we getting high copper after casting from the initial anodes also
I don't understand this - what's the difference between "initial anodes" - and "after casting - are you saying you make a pour from the BBOC (like into ingots) & then re-melting the ingots to cast anodes
hopefully other more experienced members will chime in here
Kurt