Analysis of Alumina Based Material

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chemtag

Member
Joined
Oct 25, 2017
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14
I have some material that is largely alumina (~80 wt%) with Mo (~12%) and Co (~3%). While I can strip out some of the Mo and Co with heavy acid use, I cant get it all. In order to asses how well my acid stripping is, I need to know what the starting material contains, normally something done with an XRF. We do not have an XRF, but I do have analysis of one starting material (done by an outside lab with an XRF) which will allow me to determine when I get a full characterization with another method. I have tried doing full digestion of the material with hot 93% H2SO4 or hot 85% H3PO4, but in both cases there was significant left over residue, and ~10% of the contained metals wasn't digested.

I have since turned to trying to do some sort of pyrometallurgical process. I have my hands on "A Manual for the Chemical Analysis of Metals" by Dulski and it has lead me to the wide world of fire assays! So far I have tried a 1:1 mixture of Na2CO3/K2CO3 with a 4:1 mixture of LiBO2/Li2B4O7 with a flux to sample ratio of about 5:1. I fired this in a muffle furnace at 900 C and then digested with a dilute solution of H2SO4 for analysis with an ICP-MS. These were the first conditions I tried, and while it does appear to get a lot of the material, its not getting it all.

What other conditions would you recommend for Mo/Co/Al digestion? Different Flux? Different acid for digesting the fused material?

My hope is to be able to check other potential feeds for our scaled up process without having to ship samples to another lab for outside testing (which is expensive and takes far too long).
 
Your acids are too concentrated to start. Sulfuric acid needs to be cut to atleast 25% for digesting metals, HCl needs to be at 40% before it does what it does. At the high level you are using the metal will not disolve in the solution.
 
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