To: Jerry in Omaha who wrote (7225 ) 12/16/1997 12:05:00 AM From: sh Read Replies (1) | Respond to of 20681
Gerard, I was able to get my single post "crash course" in basic mining from Mr. Greg John. Mining novices like myself will find it educational. Mr. John can be reached at nxr123@aol.com, although give the gentleman a break with your e-mails, I'm sure he's got a lot to deal with already. "Hi! I read your questions on the thread. My name is Greg John and I take care of the operations down here at Death Valley Junction (just north of the Franklin Lake Playa.) I'll try to answer your questions briefly, since you probably have found most of the answers on-line already. But, just in case, this e-mail might clarify some points. Really, the distinction between the terms assay and recovery come from traditional mining. For example, let us consider gold. A standard fire assay for gold takes about 30 grams (technically approx. 29.167 grams, which is termed an assay ton) of ground ore and mixes it with a flux usually composed of litharge (lead oxide - lead is the "collector" of the gold), borax, sand (silica), flour (or some such carbon source - carbon "reduces" the lead and precious metals from their positive valance or oxidation states to their neutral or zero oxidation metallic state), and other ingredients. Fundamentally, the flux lowers the melting temperature of the ore and the lead collects the gold out of the ore. Sometimes an inquart or addition of silver or gold is added to aid the lead in collecting the gold.The gold is then gotten out of the lead by a process called cupellation. The lead is "sucked" into the cupel, leaving a gold + silver bead. This bead is analysed for its gold content either by separation or by disolving and reading the solution using an atomic absorption machine or ICP, &c.; naturally, if an inquart was used, that amount must be numerically subtracted. The fundamental point, is that a standard lead fire assay such as this is not an economical method of extracting gold from the ore. In traditional mining, a recovery process is a economical method of extracting gold from the ore, such as cyanide leaching. Typically, however, cyanide leaching does not extract as much gold out of the ore as a fire assay. Usually, recovery methods extract on the order of 80% of the gold that can be extracted by assay methods. It is not impossible, though, to get as high as 97% recovery efficiency. So the assay essentially gives you a benchmark to measure the efficiency of recovery. The terms assay and recovery can become undifferentiated when the assay method is economical; i.e., it is a recovery method. Industry standard for evaluating an ore body is still standard fire assay. So one approach is to treat the ore to make is fire assayable. Thus satisfying industry standard. Another approach is to go straight to production. Thus showing large scale extraction. The Johnson Process seems to be the key to making the Franklin Lake material fire assayable and to be a recovery process. Testing continues. Please feel free to e-mail if you have any more questions or comments. I hope this has been helpful. Greg" One of the issues that came to mind is the possibility of innocent contamination if "gold is added to aid the lead in collecting the gold" and the addition is not calculated into the reading properly. However, with the professionalism of Ledoux, a very unlikely scenario to say the least. Given the complexity of the process, I would surmise that the hire-ups at Ledoux simply wanted a re-test to make sure everything was exact given what's at stake here. Best regards, sh