[Stoves] At what temperature are the bad gases from zinc created, vs harmless zinc oxide?

[Robert Fairchild]

>From my research it's not zinc fumes but zinc oxide fumes that cause "metal fume fever".

http://en.wikipedia.org/wiki/Zinc_oxide  : 
"...Zinc oxide itself is non-toxic; however it is hazardous to inhale zinc 
oxide fumes, as generated when zinc or zinc alloys are melted and 
oxidized at high temperature.... Exposure to zinc oxide in the air, which also occurs while welding galvanized (zinc plated) steel, can result in a nervous malady called metal fume fever. For this reason, typically galvanized steel is not welded, or the zinc is removed first.[88]..."

Reference 88:  http://mysite.du.edu/~jcalvert/phys/zinc.htm
"...Zinc appears in very small amounts in the mineral supplements favored by
 those who think eating it will improve the health. Zinc is required in 
the diet in such small amounts that it is always present in a normal 
diet without the need for supplementation. Zinc appears to be rather 
non-poisonous, though in large quantities it is carcinogenic. ..."

According to the attached paper from the CDC, zinc oxide melts at more than 1800°C, so presumably there is no risk at temperatures below this, where stoves operate.

 Bob

--- On Fri, 2/1/13, Paul Anderson <psanders at ilstu.edu> wrote:

From: Paul Anderson <psanders at ilstu.edu>
Subject: At what temperature are the bad gases from zinc created, vs harmless zinc oxide?
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org>
Date: Friday, February 1, 2013, 2:38 PM

Stovers,

Galvanized metal in stoves gets mentioned occasionally.  Do we have a clear answer about what is the temperature at which the zinc makes poisonous gases (such as when welding) versus making zinc oxide (the white stuff that you can by in a tube to put on your nose to prevent sunburn)?   Is it bad if the temperature is at 400 C to 700 C?   Or does it need to get much higher?

Paul

-- Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.com

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