Re: pH of Sulphide ore

"Peter Piper" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
>     Hi,
> I work in a silver/ lead/ zinc mine.  Usually our ore runs into the mill
at
> a pH or around 9, but lately our acid consumption has gone through the
roof!
> Testing the pH of the raw ore (just soaking a crushed up sample of high
> grade ore in distilled water), the ph is aound 12.  I cannot explain it-
can
> anyone out there help??
> There is no cement backfill or backfill of any sort where we are mining,
so
> in theory it should be mineralogically related.  Any adive would be really
> apprieciated!



Why would a Pb-Zn mill use acid if it is using the standard selective
flotation process? This does not make any sense. What is the pH that you try
to maintain?

Please advise the name of your mine and the description of the flowsheet
used to process the ore.

Off-hand I know of no ore that is that alkaline but it may be a naturally
occuring hydroxide that's shown up in your feed. numbers like your 12 would
excite the environmental department of your government EP agency. What do
they have to say about this?

Given the universal concern about acid mine waste why would your company be
concerned about a highly alkaline ore? why exactly are they adding acid to
the ore? A normal ore with a ph of nine would require addition of lime, not
acid.

What is your job description/tittle at this mine? Why is the ph or the acid
consumption your concern?

Z