E. M. (Erwin M.) Wade.

A compendium of gold metallurgy (ores) : and digest of U.S. mining laws, water rights, desert land law, etc. online

. (page 1 of 8)
Online LibraryE. M. (Erwin M.) WadeA compendium of gold metallurgy (ores) : and digest of U.S. mining laws, water rights, desert land law, etc. → online text (page 1 of 8)
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VJua




tT N
760
W2

1901
MAIN



8ELCHtR



A COMPENDIUM OF

JOLD METALLURGY



AND



'igest of U. S. Mining Laws. Water
Rights and Desert Land Laws



E. M. AND M. L. WADE, B. Sc.

Los Angeles, Cal.



TANKS




OF EVERY DESCRIPTION FOR

Mines, Hills and Cyanide Plants

Patent tton-Shrinkable Oii and Water Tanks

The only tank that will stand the desert and hot climate
Write for Catalogue and estimate on any kind of tank work.

Pacific Tank Co.

flANUFACTURERS
35 Beale Street, San Francisco
348 East Second St., Los Angeles



"For the Land's Sake"



NOTICE




I



901-907 Macu St., Los flngeles, Gal.

MANUFACTURERS OF

FERTILIZERS

For Oranges, Lemons, Peaches, Prunes, Apricots,

Berries, Grapes, Pears, Walnuts, Beets, Olives,

Vegetables, Lawns and Flowers.

DEALERS IN

Ground Bone, Sulphate of Iron, Potash Salts,

Land Plaster, Phosphates Tankage,

Nitrates, Guanos.

Send for Descriptive Catalogue

Los Angeles and Pasadena Electric Cars
Pass our Office and Factory.



Selby
Smelting

...AND...

Lead Co.

Refiners of Gold and Silver
Bars, Gold Dust, etc.

Buyers of . . .

Gold, Silver, Lead and Copper Ores, Gold Concen-
trates, Lead Bullion, Cyanide Products, etc.



ORE AND BULLION ASSAYERS



Works at Vallejo Junction, Gal.
Office, 4i6 Montgomery Street,
SAN FRANCISCO, CAL.



PORTABLE

ONE-STAMP MILL




Patented



The above cut represents our Portable One-Stamp Mill opened for
cleaning, or to take apart for transportation.

This mill can be run by hand or belted for power. Will crush one-
half ton of average ore per day often hours.

Total weight of mill 405 Ibs.

" upper half 205 "

" " lower " 200 "

Price $100.00

Write for special illustrated circular to the undersigned

IflPORTERS AND DEALERS IN

Assayers' Materials,

Laboratory, Mine and Mill Supplies,

Chemicals, Acids, Etc.

JOHN TAYLOR & CO.,

63 First Street, ... San Franclscc, Cal.



A COMPENDIUM



GOLD




(ORES)



DIGEST OF U.S. MINING LAWS, WATER RIGHTS,
DESERT LAND LAW, ETC.



SECOND EDITION REVISED

PRICE, $1.00



E. M. AND M. L. WADE, B. Sc.



MEMBERS OF THE

AMERICAN CHEMICAL SOCIETY,
SOUTHERN CALIFORNIA ACADEMY OF SCIENCES

AND

CHEMISTS OF THE AGRICULTURAL EXPERIMENT AND CHEMICAL SECTION.

I_ATE CHEMISTS AT THE CHINO AND I^os ALAMITOS

BEET SUGAR FACTORIES.



JANUARY, 19O1

UNIVERSITY 1



WADE: &,

Analytical Ohemists and Assayers
115J4 North Hain Street, Los Angeles, Cal.




Our Milling, Concentration and Cyanide Plant, for Testing and
Sampling Ores, Tailings, &c., in ton lots, more or less.



V > / r

CONTENTS . .

CHAJPTER I.

Important Properties of Gold, Mercury, Sul-
phurets, Tellurides, Quartz, and Silicates
Minerals Mistaken for Gold, pages 19-22

CHAPTER II.
Outline of Processes and Operations, pages. . . 23-25

CHAPTER III.
Crushing Pulverizing Machinery Employed,

pages . 26-29

CHAPTER IV.

Free Milling Process The Stamp Mill
Screens Plates Retorting and Melting
Dressing of Plates Conditions of Good
Amalgamation Dropping of Stamps, Duty
of Power and Water Required Roller
Quartz Mills Arrastra Pan Amalgamation
Automatic Feeders Milling and Concen-
tration Tests, Automatic Sampling, etc.,

pages , 30-47

CHAPTER V.

Concentration and Concentrators Various Ma-
chines, etc., pages 48- ;o

CHAPTER VI.

Cyanide Process MacArthur-Forrest, and
Modifications Cyanide Poisoning, Remedies
For, etc., pages 5 1-64

CHAPTER VII.
Chlorination Modern Barrel and Plattner, Hy-

181340



btLUHLK

L* t CONTENTS



posulphite and Russell Processes Roasting,
etc., pages ............................. 65-67

CHAPTER VIII.
Smelting, pages .......................... 68-70



APPENDIX I.

How to Soften and Amalgamate Copper Plates
To Make Sodium and Silver Amalgams, and
Purify Mercury Horning and Panning
Laboratory Mill Tests, (Amalgamation)

Analytical Methods, etc., pages 71-80

APPENDIX II.

Weights and Measures Metric System and
Equivalents Weights of Quartz and Water
Water Measurement Miner's Inch, etc.,

pages 8 r -86

APPENDIX III.

Prospecting Occurrence of Gold, Formations
in Which to Look for It Prospecting Outfit

for Gold, pages 87-89

APPENDIX IV.

Assaying and Sampling Different Methods of
Assaying Crucible and Scorification Meth-
ods Wet or Humid Method Check and
Umpire Assaying Assay of Tellurides

Sampling of Ores and Mines, pages 90-96

APPENDIX V.

Digest of U. S. Mining Laws Water Rights
California Arizona Desert Land Laws,
etc., pages 97~ T 4o



ESTABLISHED




H '. 3 VI i
TELEPHONE GREEN 1704



WADE <a WADE,

Assayers and Analytical Chemists

115*4 N. Main St., Los Angeles, Cal.



Oldest Firm and Host Complete Establishment in the Southwest.



WHAT WE DO.
Assaying and Analysis of

Gold, silver, copper, lead, iron, zinc,
chromium, mercury, and other metal-
lic ores; fertilizers, mineral waters,
petroleum, oils, dairy products, bitu-
mens, coal, limestones, clays, borates,
sulphur, acids, alkalies, nitrogen,
potash, phosphoric cid, urine,
citrus fruits, poisons, tannin, wines,
liquors, and industrial products gen-
erally.

WORKING TESTS.

Milling, Concentration and Cyanide TESTS of Ores
and Tailings

in large or small lots. Also tests of small
samples by the chlorination and hyposul-
phite processes.
We Call Your Attention

to our complete milling, concentration and
cyanide plant, the object of which is to make
practical working tests of ores for their
adaptability to treatment.





WADE & WADE




Chemical Laboratory



Analysis of Ores, Water, Fertilizers, Oils, and Natural
Products generally.



WADE & WADE 9

The plant consists of a stamp mill, a Frue-Vanner
concentrator, an automatic ore feeder, a Dodge
ore breaker, a set of pulverizing rolls, and cyaniding
vats, pumps, etc.

LARGE SAMPLES.

Only place in Southern California where large
lots of ore can be crushed and sampled accurately
for assaying or anaylsis. All crushing done by ma-
chinery and electric power in ton lots, more or less.

UMPIRE AND CHECK ASSAYS.
We make a specialty of umpire and check assay-
ing. Our work has been checked up repeatedly by
the smelting companies, the U. S. Mint, and the most
reputable commercial assayers and chemists in the
United States, and always found substantially cor-
rect. But we do not claim to be infallible or not
liable to mistakes, and are always glad to repeat our
work under reasonable circumstances, without extra
charges. (See Appendix IV Umpire Assaying.)

ASSISTANTS.

None but experienced and trustworthy assistants
are employed by us. Personal attention to all cus-
tom work.

SCIENTIFIC AND TECHNICAL LIBRARY.

Our library of scientific and technical works and
journals, devoted to mining, metallurgy, mineralogy,
chemistry, and cognate subjects, is unique for its
variety and select quality ; aM of which visitors arc
welcome to consult.



WADE & WADE.




Chemical Laboratory



Analysis of Limestones* Clays, Borates, Oils, Bitumens,
Sugar Beets etc.



WADE & WADE //

MINERAL AND ORE COLLECTION.
This consists of a ~reat variety of specimens of
rare and economic minerals and ores collected from
all over the United States, and foreign lands, which
we are always pleased to exhibit.

SPECTROSCOPE AND POLARISCOPE.

Two important and useful adjuncts to our appa-
ratus, are, a direct vision spectroscope (valuable
among" other things as a means of testing lithium
in water, etc., and other rare metals,) and a mag-
nificent polariscope, such as is used in testing sugar
beets and saccharine products generally.

MINE EXAMINATION AND SURVEYING.
This department is conducted by Messrs. John
Goldsworthy and Harry V. Wheeler, civil and min-
ing engineers and experts, who have had long ex-
perience on the Pacific Coast, in Mexico and else-
where. Will make thorough and practical exam-
ination and survey of mines or mineral deposits, with
plats or any other graphical information desired.
Any business in this lirie will be carefully and
promptly attended to.

MINING LAW DEPARTMENT.
In connection with our establishment we have also
a mining-law department, which is carefully looked
after by Messrs. Geo. W. King and Willoughby
Cole, Attorneys-at-Law. These gentlemen have had
extensive practice in mining law> and will conscien-
tiously attend to any mining cases presented to them,
in the State, Territorial or Federal Courts.



WADE & WADE




Assay Office, Library and Weighing Room



N. Main St., Los Angeles, Cal.



WADE & WADE 13

MINING BLANKS.

Location notices and other blanks furnished on
application.

ASSAYING OUTFITS MINING MACHINERY.
Either first-class or second-hand, handled on com-
mission. We are always glad to assist or advise in
their purchase or sale. For assaying outfits and
second-hand mining machinery we have frequent
calls. MINES.

Parties desiring to purchase or sell mines or min-
eral deposits, or have them examined, surveyed, plat-
ted, etc., will also do well to consult with us.

STANDARD METHODS.

We have no secret processes or nostrums, but
employ the standard methods used and proven by
experience throughout the world.

WADE & WADE,

115^ N. Main St., Los Angeles, Cal.

Graduates of the University of Georgia, and of the Columbian
University, Corcoran Sc. Department, Washington, D. C.
Long experience in the West.

REFERENCES.

Farmers & Merchants Bank, L. A.
First National Bank, L. A.
L. A. National Bank.

F. W. Braun & Co., wholesale druggists, L. A.
Los Angeles Business College, L. A.
Jno. Taylor & Co., dealers in mining and assay
supplies, S. F., and our advertisers, et al.



i 4 WADE & WADE




Assay Office Crushing nachinery and Electric Motor



Large Samples Sampled and Assayed.
\\5 l /z N. Hain St., Los Angeles, Cal.



PREFACE 15



PREFACE TO FIRST EDITION.

We off er this little volume to the mining 'public ;
especially to those, unhappily too numerous, who
possess little or no knowledge of metallurgy. To
such we believe it will be of value. It is not in-
tended as a text-book, or for the making of experts,
but to give a general idea of the scope and applica-
tion of metallurgical processes used in extracting
gold from its ores. Hence, we omit largely the
technical details which may be found in numerous
technical works and journals giving chiefly an out-
line of the common commercial processes and the
principles involved.

In this connection we are reminded of a "mining"
man who inquired of us about the cost of a cyanide
plant. Upon being asked if he had had any cyanide
tests of his ore, he replied, "No," but that he knew
it would work, because it was from a "cyanide coun-
try," (meaning syenitic granite!)-

It being beyond the purview of this work, as set
forth above, we omit any lengthy homilies on miner-
alogy, geology, etc., but add in appendices much
information in regard to amalgams, amalgamation
tests, prospecting, weights and measures, water
rights, measurement of water, assaying and mining

law * THE AUTHORS.



i6



WADE & WADE




Assay Furnaces



Petroleum Oils Analyzed



PREFACE 17



PREFACE TO SECOND EDITION.

The great appreciation and continued demand
induce us to issue a new and revised edition of this
work. We have endeavored and believe we have
made the subject-matter standard and up to date.
Many new ideas and processes are floating around,
but their practicability or commercial success being
not evident, we forbear the mention of them. Also
processes mentioned in the former edition, which
have proved a failure or had only a- limited success
have been eliminated. We do not endorse or advo-
cate any particular process or machinery, though
it may be mentioned in this work, unless it is within
our own experience. The title has been slightly
enlarged from that of the former edition, in order to
emphasize the value and importance of the Chapter
on Mining Laws, etc., which has been thoroughly
revised by Mr. Geo. W. Knox, Mining and Corpora-
tion Attorney, of Los Angeles, to whom we extend
our thanks. THE AUTHQRS _



z8

THE OLDEST AND THE BEST

LO5 ANGELES

Business College

AND

School of Assaying

212 West Third Street

Currier Block

Offers superior advantages to young people desiring
to fit themselves for useful positions in life. Thor-
ough courses in Bookkeeping, Shorthand, Tpyewrit-
ing and ASSAYING. Write for catalogue or call on
the LOS ANGELES BUSINESS COLLEGE, 212 W.
Third St., Los Angeles, Cal.



The Young flan's Opportunity

NO profession offers greater opportunity to make
an independent fortune, or to utilize the tal-
ents, and sharpen the mind, than those of Min-
ing and Metallurgy. They require a knowledge of
more of the Chemical and Physical Sciences and Arts
than almost any other profession. The foundation
and open sesame of these is Practical Assaying and
Chemical Analysis. In order to give the young man
an opportunity of starting in these professions, we
offer a practical course of ASSAYING, which is con-
ducted by Prof. E. M. Wade, of ihe well known and
reputable firm of Wade & Wade.

Los Angeles Business College



j. P. MCALLISTER, A. j. MCCONB w. LEWIS BELL,

President Vice- President Manager



. . INCORPORATED . .

PULTON ENGINE WORKS

OIL WELL TOOLS AND MACHINERY
ENGINES AND BOILERS



Power, Centrifugal and Steam Pumps, Shafting, Boxes,

Split Wood and Iron Pulleys and all Appliances

for Power Transmission, Brass and

Iron Castings

QUARTZ mil, MINING AND 8AWMILL
MACHINERY

Cor. Chavez and Quierolo Sts.

OFF N. /W/4/A ST.

P. O. Box 296, Station C, mcnM^PiPC ^ n I
Tel. Main 661 |_08 ANGELES, (AL



fl.



& Sons Rope Go.



Sole Manufacturers



PATENT FLATTENED STRflND




(TRADE MAKK RKGISTKRED)

This is not a new brand of Rope. It has been on the flarket for

years.



Lescnen co.'s Pot flerioi Hire Rope Tranoy

For transportation of ore, dirt, timber. Loads and
unloads automatically. Operated by one man.




929-922 North First St., ... ST. LOUIS, MO.

47-49 South Canal St , CHICAGO, ILL



GOLD MERCURY



CHAPTER I



IMPORTANT PROPERTIES OF GOLD, MERCURY/SUIVPHUR-
ETS, TELLURIDES, QUARTZ AND SILICATES.

GOLD.

Is a yellow metal, with metallic lustre ; malleable ;
ductile; sectile. Specific gravity about 19.3 when
pure; in nature (native) from 14.5 to 17.5, aver-
aging about 17 in California; hardness, 2.5 to 3.
Fuses at about 1915 deg. F. Soluble in nitro-muri-
atic acid (aq. reg., ) and in solutions of chlorine,
bromine, iodine, and alkaline cyanides. Native gold
is always alloyed with silver and copper ; sometimes
with iron, lead and other metals platinum, iridium,
et al. In regard to its distribution in ores, veins,
etc., see Appendix III.



MERCURY, OR QUICKSILVER.

Is a white lustrous metal ; opaque; liquid; boils
at about 680 deg. F. ; distills and condenses similarly
to water. Specific gravity, about 13.6. Forms
amalgams, (no doubt more or less weak chemical



20 SUL PHURE TS or SUL PHIDES

compounds,) which are white, pasty or somewhat
hard at common temperatures, with gold, silver, cop-
per, sodium, and a few other metals. This property
is utilized in the "free milling" process. (See
Chapter III.)

Ine common ore of mercury is cinnabar, the sul-
phide ; a heavy, carmine red mineral ; specific gravity
8.9 ; hardness, 2 to 2 . 5 ; lustre adamantine to earthy.
Occurs native also.



SULPHURETS OR SULPHIDES.

Are chemical compounds of sulphur and the met-
als. In color, from white to black, usually of metal-
lic lustre ; brittle or sectile. Specific gravity, from
about 4. to 6.5, and hardness, 2. to 7. Separated
from ores, when conaining gold, silver, copper, lead
or other values, by means of concentrating ma-
chines, as concentrates. See Chapter V., on "Con-
centration."

Iron and copper "pyrites" are the most commonly
occurring sulphurets in ores; frequently auriferous,
and very often barren. Their color ranges from
brass-yellow to bronze, and sometimes whitish when
arsenical pyrites are present. Copper pyrites have
usually more of a golden color, and are frequently
iridescent from oxidation. Hardness, 2.5 to 3. Iron
pvrites have more of a brassy color ; usually crystal-
line ; hardness, 6 . to 6.5; brittle. Atmospheric
agencies change them to oxides noticed in the often
prevalent shades of brown, red and yellow colors in
surface ores.



TELLURIDES- QUARTZ SILICA TES 21

Pvrites are sometimes utilized in the manufacture
of sulphuric acid. See tests for sulphur in Appen-
dix I.



TELLURIDES.

Are chemical compounds of tellurium (an element
very similar to sulphur in many respects, but also
having metallic properties,) and gold, silver, lead,
bismuth and some other metals. They usually carry
considerable gold and silver ; are associated with,
and often like sulphurets. Color, from silver white
to bronze yellow ; metallic lustre. Such ores are
usually roasted, and either chlorinated or cyandied.
Oxidized tellurium ores occur also. (See tests,
Appendix I.)

QUARTZ AND SILICATES.

Quartz is essentially silica (the oxide of the met-
allic element, silicon.) In color, it ranges from
white to black, and is transparent, translucent,
opaque, crystalline or amorphous ; massive ; granu-
lar, etc. ; specific gravity, 2.5 to 2.8; hardness, 7.
It is very hard, scratching glass easily; infusible
alone ; not attacked by the common mineral acids ;
is etched by hydrofluoric acid, and forms a glass
when melted with soda and other metallic oxides.
It is a large constituent of most mineral veins and
country rocks, either free or combined as silicates
with the metallic oxides (soda, potash, lime, iron and
alumina, principally.)



22 MINERALS

MINERALS MISTAKEN FOR GOLD.

Yellow quartz and mica, and pyrites, iron sulphur-
ets ("fool's gold/') are the most common.

Mica is cleavable, fissile. Pyrites are brittle, acted
upon by nitric acid, giving off reddish brown vapors,
and easily fusible, emitting sulphurous fumes. The
knife-point applied to the mineral will often suffice
to determine the presence or absence of gold, which
is not brittle, and appears the same from all points
of view, while pyrites glitter usually and change
appearances when turned in the light. "All is not.
gold that glitters" and in fact, native gold very
seldom glitters.



NOTE.

"Specific gravity" is the ratio of the weight of it
body to that of an equal volume of some standard
substance water in the case of solids and liquids.

"Hardness" is that quality of a mineral the degree
of which is determined by its power to scratch or be
scratched by other minerals, as arranged by an arbi-
trary scale. The scale of hardness in general use is :
i, talc 2, gypsum; 3, calcite; 4, fluorite; 5, apatite;
6, feldspar ; 7, quartz ; 8, topaz ; 9, sapphire ; 10, dia-
mond.



HARPER & REYNOLDS Co.

Carry a complete line of

Miners'
Supplies^

Steel, Picks, Shovels,
Hose and Beiting,
Steel and Iron Rope,
Dynamite, Caps and Fuse,
Corrugated Iron



CORRESPONDENCE SOLICITED



Harper & Reynolds Co.

152 and 154 North Plain St,

153 and 1 55 North Los Angeles St.



LOS ANGELES, - - - CALIFORNIA



C DUCOMMUN



300=302 N. Main St., Los Angeles, Cal.
ASSAY,

Mill and Mine supplies



Becker and Troemner
Assay Scales,
Bohemian Glass Ware, Etc.
Denver Fine Clay
Crucibles Etc.

Write lor Prices and ask for Catalogue.



PROCESSES 23



CHAPTER II

OUTLINE OF PROCESSES AND OPERA-
TIONS.

Three properties of gold are utilized in its extrac-
tion, viz., forming an amalgam or an alloy ; dissolv-
ing in chemical solutions ; and its specific gravity.

The methods or processes are :

1. Mechanical, including milling and concen-
tration.

2. Chemical, including cyaniding and chlorina-
tion, with various modifications and smelting, ap-
plicable more especially to silver, lead and copper
ores, and for gold incidentally.

Crushing and pulverizing are nearly always neces-
sary ; and also sometimes sizing (separating the pul-
verized ore into different grades of fineness,) and
other mechanical operations ; or roasting, (to rid of
sulphur, zinc, arsenic, etc.,) and drying, as a pre-
liminary preparation.

In regard to their free-milling qualities, ores may
be divided technically into :

1. FREE MILLING, OR MILLING

the gold of which is practically all capable of amal-
gamation by ordinary "milling." (See Chapter IV.)

2. REFRACTORY



24 PROCESSES

That is, the gold being incapable of amalgamation
ordinarily, on account of some prohibiting physical
or chemical condition, as for instance, it is so fine
that it floats ; is coated with sulphur, arsenic or iron ;
intimately associated with sulphurets ; chemically
combined with tellurium (tellurides) or other ele-
ments ; or, on account of the physical nature of the
ore (talcose, clayey,) too much sulphurets, or heavy
metallic oxides. The gold of this class may some-
times be largely amalgamated by means of intimate
grinding with mercury.

An ore is nowadays rarely fully free-milling, the
gold being generally both free and refractory. The
extent to which it belongs to the one or the other
decides largely what methods should be adopted in
treatment.

This should be decided generally by means of
careful working tests.

A combination of processes is often necessary for
success.

Concentration may follow milling, or milling be
preceded or followed by cyaniding, etc. Concen-
trates are either smelted, cyanided, chlorinated or
roasted and amalgamated by grinding in pans.

The tailings from free-milling ores usually carry
sufficient values to pay for cyaniding.

Ores of less than $3.00 per ton value are being
worked at a profit, by milling and concentration.
Likewise, gold tailings of less than $1.00, and ore
of less than $4.00 per ton value, by cyaniding.

In Colorado, a high-grade concentrate is obtained
after chlorination.



PROCESSES 25

A system of treatment sometimes suitable to
mixed gold and silver ores, is to wet-crush, amal-
gamate on plates, concentrate and treat the tailings
by pan amalgamation.

Local conditions, transportation, fuel, water, la-
bor, etc., requiring the attention of an expert, must
be considered in regard to selecting the method of
treatment.

CAUSES OF FAILURE-
TWO general causes of failure in mining opera-
tions prevail, viz., incompetent management and in-
sufficient development of the mine before erecting
machinery, or so that the general character of the
ore and its extent, on which the methods of treat-
ment and the magnitude of the plant depend largely,
may be determined. Free-milling ores often change
to sulphurets and become refractory below the water
level ; and it may happen that the ore becomes too
wet for dry crushing, thus necessitating the putting
in of drying or calcining machinery.

A vein does not always grow richer as it goes
down. Experience in a particular locality is usually
the only guide as to that. A practically inexhausti-
ble low-grade ore may be, and is, in fact, being
worked in places, by means of very large machinery.
Failure is also not infrequently due to experiment-
ing with untried machinery, or to the lack of suffi-
cient capital.



P.&B.
PAINT

..FOR..

HINES, CHLORINATION WORKS,

SMELTERS AND REFINERIES



THE CYANIDE

PROCESS

PC* C> ROOFINGS put up in

0t fj rolls to lay 200 square feet

with paint and nails. Absolutely acid, and alkali
proof.

PARAFFINE PAINT
COHPANY

SOLE nANUFACTURERS

116 Battery St., San Francisco, Cal.

3i2=3i4 W. Fifth St., Los Angeles, Cal.





LOS ANGELES, CAL.
WHOLESALE



Grooers



And Wholesale




Headquarters RQESSLER-H ASSLACHER

CYANIDE



Guaranteed to be 98 to 99 per cent.
Chemically Pure



CORRESPONDENCE
SOLICITED.



26 CRUSHING AND PULVERIZING



CHAPTER III



CRUSHING AND PULVERIZING MACHINERY

EMPLOYED.

The degree of fineness necessary for proper treat-
ment of an ore depends on its chemical and physical
nature and the methods of treatment. Generally,
hard, compact ores require fine pulverizing; and
porous ores, or those with much sulphurets or coarse
gold, require only coarse crushing. Fine pulveriz-
ing is often 'more necessary in milling than in cyan-
iding or chlorination.

The operation of crushing or pulverizing gener-
ally consists of the following:

1. CpARSE CRUSHING

or breaking, by means of breakers, followed by

2. FINE PULVERIZING-

by means of rolls, stamps, ball pulverizers, etc.

3. SCREENING

This is done in connection with fine pulverizing,
in order to regulate the size of the ore particles.

Before being broken, fine ore is usually separated


1 3 4 5 6 7 8

Online LibraryE. M. (Erwin M.) WadeA compendium of gold metallurgy (ores) : and digest of U.S. mining laws, water rights, desert land law, etc. → online text (page 1 of 8)