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Recovering Silver from Sulphide Concentrates (7 replies)

Zander Barcalow
9 months ago
Zander Barcalow 9 months ago

How to recover silver from silver sulphide concentrates. Our method cannot melt the silver to reduction. What could be the reason?

Alan Carter
9 months ago
Alan Carter 9 months ago

You should have an oxidation step of sulphide to SO2; you can go by roasting or by hydro-metallurgy route by caustic soda. after the sulphide are oxidize to silver oxide than you can have reduction step by dextrose and then melting it as minimum 99% silver.

9 months ago
OberstGruppen 9 months ago

Leaching with cyanide (intensive cyanidation) is also an option. Have you tried cyanide leaching?

9 months ago
Oberstorm 9 months ago

There is no one universal method for processing sulfide ores because they can contain a variety of different metals in all different ratios of one to another. Additionally, once you crush the ore down and concentrate it you have a high sulfide concentrate unless you are processing sulfide free ore. Something that may help someone out it has worked really well for me but still takes a lot of time. I’ve experimented with aqua regia and found it is really useful in processing it but is not needed in most cases. Well here it goes if you have a low sulphide content gold mineral break it does and separate it all till all you see is the yellow shiny stuff then by weight mix a about a 50/50 ratio of it with pure malleable silver. Put your silver and low sulphide content in the bottom of a clay crucible and cover it with about 3 times weight of borax then let it go in your kiln till it hits 2000 degrees and give it some time to react. Pour your mix into a cone mold let it cool then break off the borax on top of your prill. Now you should have a prill that is a brittle gray on upper portion and a little gold/silver button at bottom. Break off the little button from the bottom if you reached high enough temperature it should separate if not it will be stuck with the gray stuff. Take your gray section of the prill and crunch it up and put it into a clean silica graphite crucible with no flux heat that up to about 2000 degrees and let it sit at 2000 degrees for a bit. Give it a little swish as your pulling it out of kiln then pour into a pre-heated mold. Let it cool and clean the carbon scale off the outside now you should have process-able gold/silver mix. If you have high gold content sulphide ore you should see a nice gold looking bar if not it may have been mostly silver. If you’re processing a high sulphide content gold ore this will not work. With high sulphide gold ore break it down and separate it till all you see is the yellow shiny stuff then take that and put it into a hydrochloric acid solution and let it sit for a week or so swirling it in bottom of container occasionally. Pour off your acid and save in another container so you can use it later just add a little new hydrochloric to perk it up again, clean your gold sulphide on bottom with water and use same process above. If your acid turned a nice yellow you can extract the gold out of it with small amounts of zinc just add small amounts until your acid turns clear this part is fun as it seems like magic. Do not overdue the zinc though just a little bit at a time until it slowly removes the yellow out of acid. Well if you did all this stuff right you should be very happy with the results and you do not ever need to roast sulphide as long as you break it down into small enough particles.

Marshal Meru
9 months ago
Marshal Meru 9 months ago

I must make some preliminary questions. That Ag and Cu content of the concentrates having sulfides?

The process of recovering Ag sulfide concentrates need to do small-scale laboratory level or for large volumes?

Rahil Khan
9 months ago
Rahil Khan 9 months ago

I tried with silver sulphide (1 kg) 500 gram of sodium nitrate 250 gram of sodium carbonate 125 gram of borax. Melted in clay bonded graphite crucible! Molten mass l is poured in conical. Silver we will get. No problem. Please try a pilot melting to set a melting time. Good exhaust is needed.

Carl Jenkins
9 months ago
Carl Jenkins 9 months ago

I would like to know the content of the concentrate so as to define a concept of aid; scheme leaching should be taken according to the contents of elements accompanying silver. And probably you can use a method where no use cyanidation.

Victor Bergman
9 months ago
Victor Bergman 9 months ago

Are you fully aware of the mineralogical host(s) for Silver? Knowledge of this should guide you in ascertaining both thermodynamic and rational evaluation of how Ag should behave. For example, if you are leaching at all, but precipitating a jarosite phase, for example, the precipitate might sequester Ag and re-route Ag to a product you neither hope nor think it's going to. Otherwise, as mentioned, intensive cyanidation maybe required for a complex mineralogy.

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