Sierra County advocate. [volume] (Kingston, N.M.) 1884-1960, 1893-09-01
STUDIES IN GOLD MILLING.


J. A. Edman, in an article con
tributsd to the San Francisco Min
ing and Scientific Press, says:
Leaving ost of view other issue
OF less importance, the main hind
ranss 10 tho economically success
full treatment of geld ores appear
to lie in the generally prsvailins
ignorance OF the true physical sns
chemical character Of such ores
even amsng otherwise we'll in
formed nsn OF the craft, and tn
desply rSetea miIapprsh snsionl
and prsjudiess resulting thsrsfrom
1t IL true that assays and ana ysss
properly applied will partial Ia
solve the probls1, but whilo the
importance of these caanot by
denied, they have as yet signally
failed to throw full light upon ths
subject.
Convinced Of the enormous losses
in general nill practice, and after
repeated Intellectual steps to sslvs a
difficult question in tie treatment
Of low grade erss, the writer en-
tered upon 4 thorough microscopi-
cal examination Of gold ores and
mill prsdusts A. the only available
solution OF the difficulty, and with
very promising results. A general
outline Of his observations are here
given.
The investigators was carried ON
ia csnnsstien with test mill runs
OF ores Of different classes, mainly
from one large lode presenting q
great variety OF ores, both free
milling and highly pyritous, carry
Ing both coarse and very fine gold,
and was also supplsnsatsd by
ty pical samples Of the ores and
mill products of other mines diff
ering in mInsrslsgical and rsologi
cal conditions from the hrst msn-
The material subjected to
examination was as follows:
Ores OF every available variety;
pulp as issuing from batteries;
sands from plate tables; blanket
plain and esncsntratsd;
concentrations frsm different
classes OF ores shines frsm pan
and arastra grading; sands from
Jail slsisss; average taillngs and
shines; amalgsns from batteries,
aprons, plates and FROM pan grind
ngs; Toured mercury from batter !
es, plates, rifles and tailings;
,ontsnts Of Toured mercury; roast
I'd csncsntrates; tailings from
Information process; accessory
Minerals net csnsidarsd gold
,saring, and products OF infiltra-
ion, pereolation and deposition
within gold bearing lodes.
The loss OF gold in mill practice
IAN be traced to the following
'auses, stated in the order of their
nportancs to the industry
lst. The extreme diffusion Of
.old in its ores.
I'd. Oar imperfect knowledge
4 the laws governing analg.ma-
ion Of geld.
Sd. The frequency Of chemical
Q sm sinatioDs between gold and
thsr elements.
In giving the size of gold parti-
los the limit OF unaidsd nermal
umsn vision may be taken at the
.250 Of an inch, and smaller sizes
ill be considered microscopic.
Dimensions will bs given in frac-
ons Of an ineh.
While great diversity as 10 the
vsrags size Of gold particles
pssars in the ores Of different
,sss, the fast remains that a great
of ths metallic geld
.curs microscopic and invisiSls
vsn to magnifisrs in ordinary use,
hich readily egnlaina tie facl
lat ores giving sxen q high sssax .
,metimas show little or no geld
! panning. A great proportion Of I.
ls gold observed was below the !
1000 inoh in diameter, and the |
nit of diffusion has not been
cached with high powers repre- !
'ntiag 4 visibfs OF 10000 inoh Z.
his statement holds geed not only !
,r gold in quartz of all kinds, bat I
so fer that contained in pyrites, q
eth bright sKd oxidizsd. The q