Hi Al
thanks for that.
Interested in the separation process you describe, although it sounds
like flotation - sulpide vector, xanthate collector which we already use
for the concentration part of the process. The cyanide leach (CIL not
heap leach) is a subsequent step in the process and results in gold
being adsorbed on an activated carbon surface. The autoclave pressure
oxidation is an intermediate step which improves recovery by exposing
more gold particles to the cyanide.
Would appreciate any reference to the process you describe.
Will be staying with Gylon.
Cheers
steve
-----Original Message-----
From: Al [mailto:alwynk@shaw.ca]
Sent: Friday, September 10, 2004 5:41 AM
To: <a href="/group/PipingDesign/post?postID=gW4M4B63Oanb6Y3sfgfKemQw7nxJDW2ZQsXfpDMDmYZCtA1vB2anb3WzOZ3jyMGaTYoE9co0iAp8O_zhADyf281Bfbsgbb0">PipingDesign@yahoogroups.com</a>
Subject: [PipingDesign] Spiral Wound Gaskets - Acidic Oxygen Service
Steve
for Clarification
"Flanges on the autoclave are Ti spiral wound"... i presume means
gaskets are spiral wound Ti jacket. Gylon as I recall is s gortex/nylon
brand name gasket option. I presume an apps engineer selected it.
Ferralium is a good choice, it will always be around because the HF acid
plants have to have it, and there are still a gizzillion of them
does your client know that a company (right here in ft sask) developed a product that separates the gold, attaches to it and it floats to the top. Gets rid of nasty nasties like your horrible cynaide and leaching, and all the costly problems such as you describe that go with them. they just use regular cs piping. NEarly every gold producer has now switched to it, except the 3rd world where apparently environment matters less (there a couple of trolls in there).Wave of the future man.!
Spiral wound may be easier to source but wont be as good. As you say wont seat so well. not easy to get a gasket seating solution for all scenarios with just the spiral wound jacketed format. stick with what works unless it becomes unprocurable. anyway there are other options in soft seat gasketing.
<a href="/group/PipingDesign/post?postID=d3e1UEkKAO45FMgMAmJE_OSR47x35jppHXjyifbDI1v6cmuNvYcPKQRFydmT0A1sBCya-_tHZJfL">Altecheng@shaw.ca</a>
001(780)465-9762
Fax/Msg(780)465-9762
-----Original Message-----
From: Steve McKenzie [mailto:mechproj@xtra.co.nz]
Sent: Thursday, September 09, 2004 2:36 AM
To: <a href="/group/PipingDesign/post?postID=gW4M4B63Oanb6Y3sfgfKemQw7nxJDW2ZQsXfpDMDmYZCtA1vB2anb3WzOZ3jyMGaTYoE9co0iAp8O_zhADyf281Bfbsgbb0">PipingDesign@yahoogroups.com</a>
Subject: [PipingDesign] Spiral Wound Gaskets - Acidic Oxygen Service
Gents+1
an autoclave that I have "inherited" has oxygen injection lines which oxidise sulphide ore slurry; releasing heat and forming acid. The object is to shatter quartz encapsulation of gold particles in the slurry by thermal shock and chemical attack thereby improving downstream cyanide leach recovery ($$$). It works. Temperatures are around 250C and pressures around 31 bar. I think the internal (hot)oxy injection lines are Ferallium (havent had time to find out) and (cold) external lines are stainless; probably 316.But much of the wet area pipework is titanium, for corrosion resistance. Titanium + oxygen is normally a no-no as Ti can burn in oxygen. Ferallium doesnt burn but is becoming difficult to source. Flanges on the autoclave are Ti spiral wound. This is OK because the oxy concentrations are fairly low and can be adjusted by partial pressure regulation. The external 36 bar(cold)oxy lines are flanged (typically 50NB) with fawn (I think) Gylon gaskets which appear to have held up well (4 years). However it has been suggested replacing with spiral wound gaskets and I cant see the point. Presumably the flange faces would need to be ground, and I expect a spiral wound gasket would not be as forgiving as Gylon when it comes to alignment and torquing.
The question is: what advantage would there be in changing from Gylon to spiral wound, given successful operating experience with the former?
Personally I can only see disadvantages, but feel I may be missing something.
Your conjecture/experience would be appreciated.
Cheers
Steve
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