Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning2017-04-21T02:33:06-04:00
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Flux Recipe Formulation Help (4 replies and 1 comment)

WildWestMining
12 months ago
WildWestMining 12 months ago

Hello, I am an artisnal miner in northern Arizona and am having trouble fluxing a sulfide ore. The ore is composed mainly of arsenopyrite, pyrite, galena, and polybasite. There is minor barite present as well. The ore was crushed to 150 micron and calcined using a two stage process, 90 minutes at 900F in a reducing atmosphere (to reduce arsnic), and again for 4 hours at 900f in an oxidizing atmosphere to drive off sulfur. The calcine was prepared in 100g samples for flux testing. I have attempted several flux formulations with varying composition of silica, borax, soda ash and potassium nitrate, all of which have produced a matte button. Attempts to further smelt the matte have been unsuccessful. In my latest test I tried adding litharge to a high nitrate, low silica flux and managed to still make matte. Any help would be appreciated, I have a background in physics but chemistry is still new to me. Thanks!

Richard S
12 months ago
Richard S 12 months ago

If you are reducing the arsenic and then putting the ore back in an oxidizing circuit, you may be oxidizing the arsenic also, so I am wondering about your two stage process. None the less, a couple of suggestions:  You can try scorifying the matte in scorifying ceramic dish after wrapping the matte in a lead sheet so that there is extra lead present and after it is complete (the litharge eye closes in the center of the dish), you can then try fire assaying the residual button with a standard flux.  Alternatively, you might try adding an iron nail (a large nail for a standard fire assay charge of 1 Assay ton) with some niter in your flux and a little flurospar to increase the fluidity.

WildWestMining
12 months ago

Thanks for the reply. I'm not attempting an assay, but rather trying to formulate a flux recipe for smelting the calcine to produce dore.The two stage roasting was recommended for high arsnic ores in a document that I read on this website. I'll try to locate a link.

Joeram
12 months ago
Joeram 12 months ago

I am having similar problem arsenic and sulfur. I tried all kinds of flux combo's, roasted 5 hr then roasted 12 hr, lead in the smelt and nothing. The assay's say a gram per pound of cons. I tried acids. Everything comes down to the same, arsenic and sulfur. Any sure way of removing them first? Thanks

Eric_Pushie
12 months ago
Eric_Pushie 12 months ago

What's your current flux recipe?

WildWestMining
12 months ago
WildWestMining 12 months ago

My base recipe was:

40% fused borax, 25% potassium nitrate, 20% soda ash, 15% silica. 

I chose this as a starting point because it has been successful with other local sulfide ore that I've smelted. I tried other formulations, including variations of the above as well as the classic Chapman's Flux.

 

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