Tom Buck on thu 27 sep 01
John Britt asked about the use of hydrofluoric acid (HF) in processing of
feldspars, and Michael Banks, geoscientist and maker of claybodies,
explained that this chemical (HF) is a key component of the Flotation Cell
technology to separate feldspar and silica; and that these two materials
often are combined in the orebody (rock) mined to produce them. and that
some fancy mineralogical processing is needed to effect the separation.
When I queried Michael, he wondered about the big deposit of
potash feldspar near Custer, South Dakota, USA. So I asked Cindy S. to
check: she reported that the company simply mines the rock (a high-grade
feldspar), grinds it, screens it, and ships it. No beneficiating there.
That leaves, G-200, the other major potash feldspar mined on the
east coast of USA (see Feldspar Corp. Atlanta, GA). The company's website
says G-200 is "beneficiated" so that would mean, most likely, that the
pulverized rock is processed through a flotation cell, and that HF would
be one of the reagents.
But John Britt doesn't really have to be worried about residual HF
in G-200... the Loss on Ignition is 0.16% which suggests the HF would be
miniscule if present at all. The company does say, however, that there is
some silica in the G-200 and since the mesh is 200 or smaller, there would
be some hazard if some G-200 were inadvertently turned to dust during
handling. A good dust-mask is mandatory, as would be an effective air
exhaust system.
Anyone further interested in data on the feldspars should try a
Net search, using say the Google search engine.
til later. Peace. TomB.
Tom Buck ) tel: 905-389-2339 (westend Lake Ontario,
province of Ontario, Canada). mailing address: 373 East 43rd Street,
Hamilton ON L8T 3E1 Canada
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