Keith, TO THE HEAD OF THE CLASS, YOUNG MAN!!!! See, Wild Bilge, stick'it in yer ear!!!
Assaying & refining is an artform and constantly in need of tweaking, due to the in situ material as well as the nugget effect!
I encourage folks to use logic here...
Minus 30 screening produces a fine sand consistence such as beach.
Even an occasional grain or two of salt makes it thru a -30 mesh screen, ok? So, go to your corporate lunchroom, grab the saltshaker and try to pour out a couple of INDIVIDUAL grains of salt to get an idea of the approximate size of -30.
Now, go to your pencil tray in your office desk drawer and grab a pencil and SHARPEN IT over there by the watercooler...y'all can find the water cooler right? Tis over there close to the desk where the purdiest girl with the shortest skirt usually has her desk, right?
Anyhow, now break off the tip of that sharpened pencil...THE TIP, not the entire exposed lead, okay, guys/gals?!! If you have to wet the tip of your finger on your tongue to pick it up, then you've got the size about right...That's about -12 size mesh: VOILA, a nugget.
Now place the 2 screen-sized items on your desk blotter...the grain of salt and the tippy tippy end of your sharpened pencil.
Now, imagine for a second, dripping HEATED CYANIDE WITH AN OXIDANT on the grain of salt, and on the "nugget" represented by your pencil tip.
GUESS WHICH ONE DISSOLVES IN CYANIDE FASTER? Yep, I said Dissolves!
Now figure out how big a sample 750grams is...and why screening for "pencil point" nuggets would be critical to both dissolution time for the salt sized grains stuff as well as the thousands of assays needing to be done at the same time. I mean c'mon, folks. Do you really think Bre-X was the ONLY customer of that lab in Indonesia?????
I seem to remember that FCX uses 'em, also from previous press releases.
What if some lab employee mislabelled which batch pencil point "nuggets" go with the dissolved and fired results?*
Now, you've got an idea of the difficulty of cyanide leaching modus operandae.
And then there is the problem of killing/neutralizing the cyanide so that you can DROP OUT the gold, gravity or vacuum filter to retrieve it, dry that zinced precipitate so that it doesn't create excess moisture problems in your flux "recipe," thereby aglomerating that mixture in your crucible...(I usually mix mine in a butter tub before pouring all into a crucible, personally)and use a new paintbrush to make sure I get it ALL into the crucible...
(Yes, for you sharpies out there, usage of an existing paintbrush by a lazy lab employee can skew the sample because of how tiny particles with zinced gold can stick to individual bristles...)
Now which "nuggets" went with which dissolved/zinced crucible fired resultant piece of cupelled gold shot? What if the wrong "nuggets" got weighed with the goldshot and assayed for purity in its little lead envelope in the cupel?
I hope you all have a better idea of some of the processes and problems encountered in the labs, re: the nugget effect, and why it is so DAMNED DIFFICULT to do an assay in this business, let alone the lab person working for the "acquirer or the jv partner." Anybody see a conflict of interest here besides me???? AYUP, you sharpies already spotted that as well, since it has been discussed thoroughly on this thread.
O/49r
PS...see WildBilge, I tole'ya', "I've Been there; Done that!!! |
