Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

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Spontaneous oxidation (2 replies)

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FranLaraMonge
6 years ago
FranLaraMonge 6 years ago

I am Francisco Lara Monge, peruvian chemical engineer working in a flotation plant in Ecuador. Few days ago, for second time, we have a bigbag, with low grade concéntrate, which have violent reaction producing SO2, high temperature 250°C, and with a visible oxidation of suphurs. Do you have any idea which could be the reason of this spontaneous reaction?. Thank you. Francisco

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Frank
6 years ago
Frank 6 years ago
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Francisco,

You have a problem with self heating concentrate.  McGill university has done a lot of work in this area.  Under certain conditions, sulfur containing concentrates can self heat causing a reaction of oxidation where the concentrate can begin to burn.  Frank Rosenblum is the expert in this area.  He can be reached at Frank Rosenblum .  He is giving a paper in Moscow IMPC on the subject.

http://www.flottec.com/Prd/Products.asp

R
Richard S
6 years ago
Richard S 6 years ago
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My first best guess is that you have pyrrhotite in your concentrate.  It is known for spontaneously combusting at ambient temperatures particularly if there is moisture present in the concentrate.  This happened a few time at the old Homestake Mine in Lead South Dakota.  The mineral has an extra sulfur that can cause the formation of thiocyanate in cyanide circuits and can oxidize to SO2 in a mineral concentrate.  Try minimizing the moisture content of your concentrate particularly if you can identify a larger amount of pyrrhotite in your flotation feed.  You might be able to alter your float conditions to depress it, but depending upon your other minerals present you may depress others that you want.  Copper will activate it if you are adding any as a collector modifier.

http://www.kuntermetallurgy.com/

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