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Flotation Concentration of a Peruvian Copper-Zinc-Iron Ore

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FLOTATION GOXdHTTRATICE: OF A PERUVIAN
CCPPER-ZIITC-IROIT ORE
By
Carlos H. Plenge-V/ashburn, B. S.
of
Lima, Peru
A Thesis
Submitted to the Department of liineral Dressing
in Partial Fulfillment of the
Requirements for the Degree of
Laster of Science in IZineral Dressing
/4S32
::CI:TAIVA SCHOOL O F LJ::CES
B U T T E , 110ITTA1IA
JU1S 4 ,
MONTANA SCdoo-
1941
,. O
t
iUi)iMl i '
LIBRARY-MONTANA TECH
^
BUXTE, MONTANA
UMI Number: EP33264
All rights reserved
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UMI EP33264
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ACIOrOWIEDGEliiEKTS
To Mr. Alberto Brazzini of Lima, Peru, for making
the investigation possible, and to Dr. S. R. B. Cooke,
Research Professor of Mineral Dressing, Eontana School
of Mines, for assistance and encouragement, acknowledgement
is gratefully made.
TABLE OF CONTENTS
INTRODUCTION
.
1
Present Milling Practice
3
Object of the Investigation
3
PRELIMINARY INVESTIGATIONS
,5
Microscopical Examination
5
Chemical and Spectrographic Analyses
•
FLOTATION FTJNDAilENTALS INVOLVED
7
9
Effect of Copper Salts
9
Effect of Cyanide Ions
10
Effect of Ferrous Iron
11
Effect of Ferrous and Zinc Ions
12
Effect of Sodium Sulphide
14
Effect of Sodium Sulphite
14
Effect of Wetting Agents
14
Effect of Potassium Bichromate
.................. 15
EXPERIMENTAL FLOTATION WORK
16
Grinding
1?
Flotation
17
SECTION I
De-activation of Sphalerite by Sodium Cyanide
SECTION II
The Effect of Ferrous Sulphate
19
... 19
24
24
SECTION III
29
Effect of Zinc Sulphate
SECTION IV
35
Effect of zinc and Ferrous Sulphate
SECTION V
35
38
Effect of Sodium Sulphide
SECTION VT
Effect
29
38
42
of 7 / e t t i n g Agents
42
SECTION V I I
45
SIL-JARY
49
CONCLUSIONS
51
BIBLIOGRAPHY
52
INTRODUCTION
It was not until between 1927 and 1930 that
sufficient progress was made in selective flotation to
permit the installation of commercial-sized plants for the
treatment by flotation of copper-zinc-iron ores. Until the
new processes had been worked out successfully, the lack of
treatment of ores of this type had proved a barrier in the
path of metallurgical progress.
Separation of galena and sphalerite is comparatively
simple. A low iron ore containing these minerals may be
concentrated by gravity methods provided that it is not
necessary to grind the ore fine. The specific gravities of
chalcopyrite and sphalerite are so nearly the same, however,
that their separation by gravity concentration is out of the
question.
Complex lead-zinc-iron ores in which the several
minerals are intimately associated, necessitating fine
grinding to free them, have been treated by flotation for
the past twenty five years, and very successfully since
Sheridan and Griswald introduced cyanide as a specific
depressant for sphalerite.
The problem of separating sphalerite and copper
minerals is frequently more difficult. There are a number
of sulphide minerals that carry copper, whereas galena is
the only common lead-bearing sulphide, and sphalerite,
2
including marmatite, the only zinc-bearing sulphide.
The copper sulphides occurring in the ore studied
are:
chalcopyrite, enargite, chalcocite, bornite, and the
"gray copper'* minerals. All of these minerals, except
chalcocite, contain other elements than copper and sulphur;
chalcopyrite and bornite contain iron; enargite contains
arsenic;
the "gray copper*1 minerals contain arsenic and
antimony.
Since the properties of a mineral depend upon
the character of the chemical elements of which it is
composed and even more upon the way in which the constituent
atoms are arranged in the crystal structure, variations in
these characters and arrangements would result in differences
in chemical properties, such as polarity, rates of oxidation,
rate of reaction with collecting agents, adsorption by
collecting agents* and in the formation of soluble salts, etc.
7/hen attempts have been made to use the standard
lead-zinc separation methods on copper-zinc ores, it is
found that the depressants added to inhibit the flotation
of iron and zinc minerals will, under certain conditions,
depress a large part of the copper-bearing minerals. It has
also been recognized that, in the grinding of copper-zinc
ores, soluble salts are generated, which, unless properly
controlled, are detrimental to flotation. This, together
with the fact that in most pyritiir ores the copper occurs
as chalcopyrite, has made these ores more difficult to
concentrate satisfactorily.
3
Present milling practice. The property of
Sociedad Minera Puquio-Cocha is situated about 65 miles
north-east of Lima, Peru, and 8 miles east of the continental
divide.
It is at an altitude of approximately 14,000 feet.
The present mill treats 250 tons of ore per 24 hours
and produces a copper concentrate.
The crushed ore is ground in a No. 66 Marcy ball
mill, operating in closed circuit with a 6 x 21 foot Dorr
classifier. About 11 pounds of lime, 0.33 pounds of sodium
cyanide, and 0.7 pounds of zinc sulphate per ton of ore
are added to the grinding circuit.
The classifier overflow, containing approximately
10 percent solids, 80 percent of which are minus 200-mesh,
passes to a 30 x 10 foot Denver thickner. From this the
pulp, now containing 20 per cent solids, flows into a
conditioner where it is conditioned with 0.06 pounds of
pine oil and 0.04 pounds per ton of Aerofloat 25. The
conditioned pulp passes into the copper rougher circuit.
This circuit consists of five Denver Sub-A flotation cells,
the tailings from which pass to a scavenger circuit. The
copper rougher concentrate is not cleaned. The scavenger
concentrate is returned to the rougher cells. The mill
consists of two sections, both identical.
Object of the investigation.
The metallurgical
results were satisfactory with the older method of flotation
4
until June, 1940. Prior to this date, the copper concentrate
contained an average of 28 percent copper and between 4 to
6 percent zinc. The heads contained from 0.5 to 1.5 percent
zinc.
In June, 1940, however, a change in the ore-body
resulted in an increase of the zinc content to as high as
4 percent. The treatment of this new ore resulted in a
drop in the grade of the copper concentrate
copper.
to 23 percent
The concentrate contained as much as 15 percent
zinc. A pennalty had to be paid to the smelter for each
unit of zinc above 10 percent.
The present investigation was undertaken with the
object, first, of obtaining a concentrate assaying at least
28 percent copper and containing less than 10 percent zinc;
second, of reducing the zinc content of the copper concentrate
to a minimum so as to be able to determine the possibilities
of obtaining a high grade zinc concentrate containing a
minimum of copper and iron.
A shipment containing 345 pounds of this new copperzinc ore was received at Butte on November 8th., 1940.
The arrangements for the shipment were made by l£r.
Alberto Brazzini of Sociedad liinera Puquio-Cocha.
5
PRELIIIINARY INVESTIGATIONS
Microscopical examination of the ore.
The ore was
sampled, and seven polished sections were prepared and
examined microscopically to determine the mineralogical
characteristics of the ore.
The microscope showed the ore to consist of massive
sulphides with minor amount of a non-sulphide gangue
material.
This non-sulphide gangue consists of quartz and
small amounts of carbonates occurring as small areas and
grains in the sulphides. The sulphides are pyrite,
chalcopyrite, enargite, sphalerite, bornite, chalcocite,
the "gray copper* minerals and galena. Though the sulphides
are commonly intimately admixed, they are rather coarsetextured, and even form large masses composed chiefly of
one or another of the individual minerals. These large
masses contain small grains of other sulphides. A small
percentage of the ore, in which the sulphides are intimately
admixed, forms a fine-textured phase.
Pyrite is disseminated in irregular grains. Some
portions of the ore consist almost entirely of this mineral.
In certain areas it is invaded and veined by enargite,
sphalerite, and more rarely by bornite and chalcopyrite.
Chalcopyrite forms large granular masses. These
usually contain sphalerite, enargite, and corroded remnants
of pyrite.
6
Host of the enargite occurs in coarsely-crystalline
masses which contain veinlets and blebs of bornite, chalcocite,
pyrite and some sphalerite. A minor quantity is disseminated
as coarse and fine grains and crystals.
Sphalerite occurs in large masses and small grains.
It often includes or partially surrounds the pyrite grains.
Numerous blebs of chalcopyrite, quartz, and more rarely
galena, occur within the sphalerite.
The bornite contains tiny veinlets of chalcopyrite.
An intimate intergrowth of bornite and chalcocite has been
observed.
Chalcocite, bornite and the "gray copper** minerals
are usually associated with enargite.
A microscopic grain count of the sulphide minerals
in a minus 100 plus 150-mesh sized fraction gave the
mineralogical composition of the ore. The results are
given in Table I.
TABLE I.
Mineralogical Analysis
Mineral
Pyrite
Chalcopyrite
Enargite
Sphalerite
Weight %.
65.0
7.0
5.4
5.5
The degree of liberation^, determined at three sizes,
is given in Table II.
f
A. It. Gaudin, **Principles of Flotation", p. 70, (1940).
7
TABLE II.
Degree of Liberation %
Mineral
Pyrite
Sphalerite
Copper minerals
Silicates
65
74.2
51.5
49.2
79.2
Size(mesh)
150
89.5
62.2
70.8
91.4
200
87.8
Chemical and spectrographic analysis
All of the sample as received contained ore ranging in size
from one inch to minus 2Q0-mesh.
The ore was crushed to minus -^ in. It was then
thoroughly mixed and a portion split out on the Jones sample
splitter.
This portion was further crushed until it all
passed a 14-mesh screen. This sample served for the head
assays.
The results of the chemical analysis are shown in
Table III.
TABLE III.
Assay of Head Sample#
Copper
Zinc
Silver
Lead
Iron
5.3
3.2
fa
fa
5.2
Oz/Fon
0.52 fo
34.5 %
~$ The chemical analyses were made by Mr. H. J. Harrity
of the Moonlight Laboratories, Butte, Montana.
8
The results of several spectrographic analyses,
of minerals hand-picked from the ore, are recorded in Table IV.
TABLE IV.
Qualitative Spectrographic Analyses of
Minerals Occurring in the Ore
Element
Speciment
Hematite
Pyrite in
Hematite
Head
Sample
Clean
Pyrite
Chalcopyrite
Enargite
Fe
#
#
#
#
Strong
Strong
Cu
Medium
#
#
#
Strong
Strong
Ag
None
None
#
None
#
Weak
Zn
None
None
#
None
#
None
Pb
None
None
#
Trace
#
None
Sn
Trace
Trace
Trace
None
Bi
None
None
Trace
Trace
Sb
None
None
Trace
None
Trace
#
As
None
None
#
None
None
#
Trace
#
Trace
None
# designates considerable amount.
An examination of Table IV indicates the presence
of silver in the minerals chalcopyrite and enargite. It
emphasizes the fact that the sphalerite and chalcopyrite are
intimately associated.
9
FLOTATION FUNDAMENTALS INVOLVED
Pure sphalerite- is perhaps the least floatable of
the common sulphide minerals. It is amenable to activation
however, by a number of metallic salts, especially by those
of copper.
Some of the copper sulphides, such as chalcocite,
tend to oxidise at the surface layer. The dissolution of
copper salts from partly oxidised ores results in a
concentration of copper ions in solution. It is true that
in modern practice most of the copper is precipitated as
hydroxide or as a basic carbonate, but evidently the
concentration of the copper ions in equilibrium with these
is sufficient to cause activation of sphalerite.
Effect of copper salts. Since copper sulphide is
less soluble than zinc sulphide, the following reaction
must occur to an appreciable extent.
Cu r
ZnS =
CuS +• Zn
The following experiment was conducted. A copper
solution containing 0.00249 grams of copper per cubic
centimeter was boiled with a piece of clean sphalerite for
approximately 14 days.
The solution then contained 0.00229
grams of copper per cc. and 0.0021 grams of zinc per cc.
These values show that, within the experimental error,
10
copper ion3 replaced zinc ions in the sphalerite lattice.
The zinc ions go into solution, conforming the above
equation.
Ravitz and Wall^- suggest that the copper ions are
adsorbed on the walls of the unit cell of which sphalerite
is composed, thus altering the surface properties of the
mineral.
Physieochemical principles indicate that the actual
copper-ion concentration, not the total dissolved copper,
is the deciding factor governing the coating of sphalerite.
Hence, there are two conceivable means by which the
flotation of sphalerite, using shor-carbon chain xanthates,
might be prevented:^
1.
The copper-ion concentration could so be reduced
that sphalerite would not be coated with cupric sulphide.
2. Although the sphalerite may be coated, the
copper-ion concentration could be so low that no copper
xanthate could form on the surface.
Effect of cyanide ion. There is a certain agreement
among the investigators that in general, the depression of
sphalerite by cyanide is due to the formation of complex
TZ S. F. Ravitz and W. A. Wall, Journal of
Physical Chemistry, Vol. 38, p. 13, (1934).
2. I. W. ¥ark and A. B. Cox, "Principles of
Flotation", Trans. Am. Inst. Min. and Met. Eng., Vol. 112,
(Milling Methods), p. 221, (1934).
11
cuprocyanides and is, therefore, a de-activating rather than
a depressing action.
Sodium cyanide is a good depressant of pyrite in
the presence of collectors such as xanthates. Its presence
in the circuit is necessary if selective flotation of a
capper-iron ore is tp be accomplished at a low pH value.
V/ark's theoretical work3indicates that in the flotation of
the copper minerals, chalcopyrite lies closest to pyrite
with regard to the influence of cyanide and alkalies.
Consequently, if conditions are found for which chalcopyrite
can be floated away from pyrite, the other copper minerals
will float with the chalcopyrite. This condition may be
realized
within a pH range of 7 to 8, for a low concentration
of cyanide;
or within a pH range of 7 to 7.5 for a high
concentration, when xanthates are used as collectors.
Effect of ferrous iron. Ferrous and ferric salts
are depressants of sphalerite.
In a study by Gaudin, Haynes
and Haas,^Qf the influence of thse salts on the flotation
of sphalerite, they states
Iron Salts activate sphalerite in distinctly acid
circuits. This activation decreases with increase
in pH until ferric salts become depressants in
substantially neutral circuits, when used with
xanthates.
37
Ian W. Wark, "Principles of Flotation", p.194,
4.
Ibid., p. 196.
(1938}
5. A. M. Gaudin, E. C. Haas and C. B. Haynes,
"Flotation Fundamentals", Utah Eng. Exp. Stat., Tech. Pub.
No. 7, Part 4, p. 32, (1930).
12
Whether these salts prevented activation or whether they
prevented adsorption of the collector by activated sphalerite
was not ascertained.
The effect of iron salts when used with phosphorus
pentasulphide (Aerofloat) as collector, depends upon the
quantity of the collector used.6
An excess of ferrous sulphate, particularly if used
in conjunction with cyanide, inhibits the floatability of
all sulphides. It is a practice in some mills to add just
enough lime to leave less than one pound per ton of ferrous
sulphate in solution. This is done with the purpose of
inhibiting the flotation of pyrite.
Effect of ferrous and zinc ions. Concerning the
effect of iron and zinc salts, Campbell, Howes and Ode7
states
Very small quantities of ferrous sulphate in
combination with zinc sulphate, in concentrations
of more than 250 parts of zinc per million parts
of water, depress the flotation of sphalerite to
a marked extend.
The general effect of using zinc sulphate as a
depressant for sphalerite i3, according to the law of
WZ A. B. Campbell, W. Howes and H. Ode, U. S.
Bureau of Mines, R. I. No. 3149, p. 23, (1932).
7.
Ibid., p. 26.
13
mass action, to reduce the solubility of the sphalerite ,
even to a poin at which the zinc sulphide would become les3
soluble than copper sulphide. The sphalerite would then
not be activated, that is, it would not be coated on the
surface by a film of copper sulphide.
Tucker and Head8 found that the depressant action
of zinc sulphate and sodium cyanide, in the presence of
copper sulphate, was greatest when the two reagents were
present in equivalent amounts. Referring to this combination
Wark9says s
It may be significant that the zinc cyanide, the
product of the interaction of cyanide and zinc
sulphate, is in equilibrium with very low but
definite concentration of cyanide ions, and that it
can therefore act as a reservoir for such ions if they
are required for any purpose by the pulps
Zn(CN)2(solid)
Zn(GN}2(a:issoIvedJ
Zn
2CN"
It is possible therefore, that the function of the
dual addition is to maintain the cyanide concentration
at some definite value that is effective for
depression (or to prevent activation) of sphalerite,
but it is without effect on the minerals that are
to be floated. This, however, is but a conjeture.
It should be noted that the function of alkalis is
undoubtedly to fix the cyanide ion concentration,
and that therefore zinc sulphate and alkalis may
act similarly.
8. 3.. L. Tucker, J. F. Gates and R. E. Head,
Trans. Am. Ins. Min. and Met. Eng., Vol. 73, p. 372, (1926).
9. Ian ¥. Wark, " Principles of Flotation",
p . 205, (1938).
14
Effect of sodium sulphide. The function of sodium
sulphide in preventing the flotation of sphalerite is not
fully understood. Warkl°states that the hydrosulphite ion
is the effective depressant. He also says that the alkali
itself becomes the depressant if a certain critical pH
value is exceeded.
Effect of sodium sulphite. It has been suggested
that sodium sulphite is an effective depressant of sphalerite
only in the presence of zinc saltst
these may be derived
from the ore.
Effect of wetting agents.
The application of
wetting agents to the flotation of sulphide minerals is a
a new field. Many wetting reagents are available in the
markel but only few have been fully investigated.
Selective flotation on mixed sulphide ores has been
accomplished by using wetting agents in conjunction with the
customary activators and depressants.12 Work along this
line was investigated in the School of Mines laboratories by
Dr. S. R. B. Cooke. A lead-zinc-copper-chlorite ore was
selectively floated by using small amounts of Aerosol O.T.
10. Ian W. Wark, " Principles of Flotation ",
p. 207, (1938)
11. M. Winkler, Met. und Erz, Vol. 31, p. 358, (1934)
12. R. S. Dean, J. Bruce Clemmer and S. R. B. Cooke,
•* Use of wetting agents in Flotation •', U. S. Bureau of Mines,
R. I. 3333, (1937).
15
or Aerosol A. Y., sodium cyanide and zinc sulphate to
depress the sphalerite.
In previous tests, without the use
of the Aerosol reagents, as much as 10 pounds per ton of
sodium cyanide had ^oeen used in an attempt to depress the
sphalerite, with the result thaf'the floatability of all
the sulphides was inhibited.
Effect of potassium bichromate. Bubble tests have
shown that potassium bichromate is an effective depressant
for both galena and activated sphalerite. The depression
of the former is generally attributed to the formation of
an inssoluble chromata film on its surface. This explanation
is inadequate for sphalerite because of the relatively high
solubilities of zinc chrornate and zinc bichromate. Gaudin,
Haynes and Haasl^ have shown, however, that the flotation
of sphalerite is adversely affected by bichromate.
13. A. M. Gaudin, C. B. Haynes and S. C. Haas,
"Flotation Fundamentals"» Utah Eng. Exp. Stat., Tech. Pub.
No. 7, Part 4, (1930)
16
EXPERIKENTAL FLOTATION TTOBK
The experimental flotation work of this thesis is
divided into seven sections. Each test, or group of tests,
as recorded in the different sections, represents the best
combination for a given set of reagents under conditions
which appeared to be most suitable.
In Section I, the de-activation of sphalerite by
sodium cyanide, with the subsequent removal of the cyanide,
was studied.
The results obtained"approximate conditions
under which to prosecute testing.
The effect of ferrous salts was studied in Section II..
Section III and IV represent experiments using zinc
sulphate, and a combination of zinc and ferrous sulphate.
The effect of adding sodium sulphide to the grinding
circiiit was studied in Section V.
Section VI deals with the study of wetting agents and
their effect upon the sphalerite.
The last section consists of a series of tests which
were performed at the beginning of this work.
In these
tests, the effects of potassium bichromate, sodium sulphite,
thiocarbanilide and sodium Aerofloat were studied.
The writer wishes to note here that the reactions
described in the following paragraphs are more or less
theoretical and may not represent what actually takes place.
The object is to attempt to describe what has taken place
17
from the data obtained, and if these data are of help to
any one, the writer is very glad indeed.
Test Procedure
Grinding.
The ore sample was crushed dry to minus
48-raesh and was then split into 600-gram charges. A
600-gram charge was placed in a one gallon Abbe pebble
mill and diluted with water to a pulp density corresponding •
to 40 percent solids by weight. The material was then stage
ground for a definite period of time as shown on the
accompanying log sheets.
Flotation. A ground 600-gram charge of material to
be tested was placed in a laboratory-size Fagergren flotation
cell, and diluted to about 22 percent solids. Reagents were
added as shown in the accompanying log sheets, and the pulp
was allowed to condition with the air valve closed. The
air valve was then opened and the resulting concentrate was
removed by skimmin'
The time of conditioning and flotation
are shown on the log sheets accompanying each test.
In the tests where a cleaning operation was performed
on the rougher concentrate the procedure was as follows: the
tailing restilting from the roughing operation was washed
from the laboratory-size Fagergren flotation cell. The
rougher concentrate was then placed in the machine and floated
as shown in the log sheets accompanying the tests where
18
such a procedure was used.
Llicroscopic examination of the flotation products
was used for control and where analytical analysis was
thought to be unnecessary.
19
SECTION I.
De-activation of sphalerite by sodium cyanide. In
this series of tests the effect of a chemical treatment of
the ore, prior to flotation, was studied.
It is widely recognized that sphalerite will respond
to short-chain xanthates only in the presence of some heavy
•letal salt such as copper sulphate. It has also been
3u™gested14that sodium cyanide can remove the copper-bearing
film that causes sphalerite to float when using short-chain
xanthates as collectors. Since cyanide has a depressing
effect on copper sulphides, the removal of the excess
cyanide was found to be necessary.
The ore was crushed dry to pass a 48-mesh screen.
A 600-gram charge was taken and stage ground to approximately
55 percent minus 200-mesh at a dilution of 40 percent solids.
Sodium cyanide was added in the lasT four minute period of
grinding.
The ground charge was allowed to settle and the
water was then removed by decantation. After diluting
it to 20 percent solids with fresh water, the pulp was
conditioned with the reagents as shown in the accompanying
log sheets, and then floated for a period of five minutes.
The results and details of these tests are shown in
lAl
I. ¥. wark and A. B. Cox, "Principles of Flotation",
Trans. Am. Inst. Kin. and net. 3ng., Vol. 112, (Killing Methods),
p. 245, (1934).
20
Tables V. and VI.
An examination of Table V shows that 87.7 percent of
the copper was recovered in a concentrate which assayed
26.5 percent copper and 7.7 percent zinc.
To determine the state of the copper sulphides in
the tailing briquetts were made and studied under the
microscope:
it was found that the copper sulphides were
present mostly as locked grains and as blebs within the
sphalerite and pyrite. Large, free chalcopyrite grains were
also present.
The influence of the pH value on the grade of the
concentrate will be noted on examining Table VI.
In tests recorded in Table VI, an attempt was made to
obtain less brittle froth by using cresylic acid in place
of pine oil. Using this frother, the zinc assay in the
concentrate dropped to an average of 4.5 per cent zinc. The
significance of this fact is not clear. Tentatively, it
might be assume;that it is due to the flotation of clean
sphalerite by impurities in the pine oill°\
The present work is in agreement with the vie1:/ that
the function of cyanide in preventing the flotation of
sphalerite is to remove the copper-bearing film from the
surface, if it has been activated previously.
15. J. E. Horuan and 0. G. ILalston, "Conditioning
Surfaces for Froth Flotation", Trans. Am. Inst. L.in. and Ilet.
r.ng., Vol.134, (Hilling Methods), p. 67, (1939).
21
Table
V
No,
Test
CONDITIONS
Time
Mins.
%
Solid
REAGENTS POUNDS PER TON
PH
| Grind
40
I Condition
21
7.6
Flotation
21
7.6
Remarks:
AND REAGENTS
CONDITIONS
I POINT OF
ArDITION
No.
Lime
NaCN
4.0
1.0
208
KBX
P.O.
0.20
0.05
0.05
208 d e s i g n a t e s R e a g e n t 2 0 8 , American Cyanamid
KBX d e s i g n a t e s P o t a s s i u m B u t y l X a n t h a t e
P.O. designates Pine O i l .
METALLURGICAL
PRODUCT
%
Weight
RESULTS
% DISTRIBUTION
ASSAYS
Cu
Zn
Co,
Cu
Zn
Concentrate
18.2
26.5
7.7
87.7
46.9
Tail
81.8
0.8
1.9
12.3
53.1
Feed
100.0
5.49
3.0
100.0
100.0
i
i
Ratio of Concentration:
Remarks:
5.5 to 1
>
Table
RESULTS
TEST
NO.
PRODUCT
OF
BATCH
WEIGHT
Zn
Concentrate
Tailing
Feed
18,0
82.0
100.0
0.99
O
O ft TS
*•> ft W
Z
Concentrate
Tailing
Feed
17.8
82.13
100.0
26.0
1.0
5.48
5.0
4
Concentrate
Middling
Tailing
Feed
11.7
14.6
73.7
100.0
5
Concentrate
Tailing
Feed
17,7
82.'6 .
100.0
H6.7
15.0
0.4
5.6
23,5
1.7
5.56
Concentrate
Tailing
Feed
19.1
80.9
100.0
28.0
1.48
5.4
6
FLOTATION
4.15
It
TESTS
$ DISTRIBUTION
ANALYSIS .
1
%
Cu
2
No. y/
REMA3KS
l
Cu
Zn
85.0
15.0
100.0
2? . 5
76,7
100,0
84,5
15.5
100.0
55.7
39.1
5.2
100.0
74.8
100.0
77.8
op
p
10!).0
pH:
7,8
pH:
7.9
KBX a l o n e
was used as
the c o l l e c t o r
Note e f f e c t
of h i g h pH
pilj 10
pH: 10.5?
23
Table
VI"
REAGENTS
'"""
1 — —
TEST |
Ho. §
2
5
—'
•
'
REAGENTS
1
i
1
I
|
j
3
4
-
Lime
Sodium cyanide
Aerofloat 208
Butyl xanthate
Cresylic acid
Lime
Sodium cyanide
Aerofloat 208
Butyl xanthate
Cresylic acid
Lb/TON
\
POINT OF ADDITION
i
J
»
!
<
j
i
4.0
1.0
0.2
0.05
0.05
4.0
1.0
0.2
Ball mill.
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
0.05
0.07
4.0
I
|
|
I
Lime
Sodium oyanide
Butyl xanthate
Cresylic acid
I
1
1
J
|
Lime
Sodium cyanide
Aerofloat 208
Butyl xanthate
Cresylic acid
8.0
1.0
0.2
1
8
I
I
J
Lime
Sodium cyanide
Aerofloat 208
Ethyl xanthate
Pine oil
7.0
0.5
Ball mill.
Ball mill.
.flotation cell.
Flotation cell.
0..8
0.1
0.07
0.05
0.05
Ball mill.
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
.
Ball mill.
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
>
6
*
1
0.18
0.05
0.05
Ball mill.
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
24
S3CTI02T II.
The effect of ferrous sulphate. These tests were run
.ith the object of determining the action of ferrous sulphate
^:. flotation of the ore.
The procedure used was identical with that used in
jection I, with, the exception that the 600-gram charge was
stage ground to approximately 82 percent minus 200-mesh.
Lime, sodium cyanide, and ferrous sulphate were added in
the last nine minute period of grinding.
The ground charge
was then transferred to the flotation cell and conditioned
with the reagents as shown in the accompanying log sheets.
The first objective was to attempt to remove the
excess cyanide used in the chemical treatment of the ore.
It will be noted, Test 7, 8 and 9, Table VII, that ferrous
sulphate does not counteract the depressing effect of cyanide
upon the copper minerals.
It was found that if ferrous
sulphate was used in excess, it would inhibit the flotation
of all minerals, in as much as it produces poor froth conditions.
?or these tests the copper recoveries were approximately the
samej
63.3 percent using ferrous sulphate, and an average
of 66.5 percent of the total copper when this reagent was
not added.
The fact that in Test 7 the gra.de of the copper
concentrate was 26.5 percent copper suggests that the action
of ferrous sulphate in conjunction with cyanide is to depress
pyrite.
A microscopic examination of the concentrate showed
25
that sphalerite was present in approximately e<pual amounts
m. all three products.
It will be observed also that an
increase of the grinding time did net improve the copper
recovery in Test 9.
In Test 10 and 11, the effect of cleaning the concentrate was studied in an endeavor to determine what grade
could be expected.
An examination of Table VIII shows that
62.5 percent of the copper was recovered in the cleaner
concentrate which assayed 29 percent copper and 8.12 percent
zinc.
The assays of the various products of this test show
that 97.7 percent of the total copper and 90.2 percent of
the total zinc had 'oeen recovered in the concentrate and
middling.
This test suggest the possibility of producing
a bull: concentrate -which could be treated so as to produce
a copper and a zinc concentrate.
This would permit the
selective flotation of the bulk concentrate even in an acid
circuit.
It will be noted that ferrous sulphate dees not
possess a selective depressing action upon sphalerite. Its
toxicity may be due to the precipitation of xanthate, in
which case it would net act selectively.
"• • '
Table
RESULTS
TEST
NO.
PRODUCT
V/EIGHT
Cu
OF BATCH
Zn
•"
IHJI
NQ. Vll
FLOTATION
ANALYSIS
%
'• • ""'•
TESTS
% DISTRIBUTION
CU
Zn
REMAIUCS
7
Concentrate
Tailing
Feed
15.4
86.6
100.0
26.5
2.3
5.54
64.1
35.9
100.0
pH: 7.8
55$ -200 mesh
8
Concentrate
Scavenger
Tailing
Feed
16.0
8.3
75.7
100.0
. 23.4
16.7
0.5
5.53
67.7
25.1
7.2
100 !o
55$ -200 mesh
Ferrous s u l phate omitted
9
Concentrate
Tailing
Feed
16.6
83.4
100.0
23.0
2.0
5.5
69.4
30.6
100.0
82$ -200 mesh
Clean. Cone. 13.5
11.5
Middling
Tailing
75.0
Feed
100.0
28.6
10
7.4
pH: 8.3
27
Table
VII
REAGENTS
TEST
No.
REAGENTS
Lb/TON
j
!
!
t 2.0
| 1.0
0.3
0.2
0.05
0.05
! Ball mill.
! Ball mill.
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
8 . Lime
Sodium cyanide
Aerofloat 208
Butyl xanthate
Cresylic acid
2.0
1.0
0.2
0.05
0.05
Ball mill.
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
9
Lime
Sodium cyanide
Aerofloat 208
rsutyl xanthate
Cresylic acid
2.0
1.0
0.2
0.05
0.08
Ball mill.
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
Lime
Sodium cyanide
Ferrous sulphate
Sodium cyanide
Aerofloat 208
Butyl xanthate
Cresylic acid
5.0
0.35
0.3
0.1
0.2
Ball mill.
Ball mill.
Ball mill.
Conditioner.
Conditioner.
Flotation cell.
Flotation cell.
7
10
POINT OF .ADDITION
i Lime
t Sodium cyanide
; Ferrous sulphate
Aerofloat 208
Butyl xanthate
Cresylic acid
I
8
J
J
8
,'•••
- — . i
• ••
"'i.'.j,..-r:
\
\
ri
0.05
0.1
*
28
Table
No,
VIII
Test
CONDITIONS
AND REAGENTS
CONDITIONS
POINT CF
ADDITION
Time
Mins.
%
Solid
Grind
No.
11
REAGENTS POUNDS PER TON
PH
40
Condition
5
21
7.6
Flotation
Cleaner
Flotation
5
21
7.7
3
9
7.2
Lime
NaCN
FeS04
3.0
0.45
0.3
208
KBX
C.A.
0.2
0.05
0.05
0.1
i
Remarks:
C.A. d e s i g n a t e s C r e s y l i c Acid
No f r o t h e r was a d d e d i n t h e c l e a n i n g
METALLURGICAL
PRODUCT
Clean.
Cone
Cu
12.5
29.0
Middling
12.3
16.7
Tail
75.2
Feed
100.0
Zn
8.12
16.1
0.22
0.43
5.8
3.3
••*
Ratio of Concentration: 8 t o 1
Remarks:
RESULTS
% DISTRIBUTION
ASSAYS
%
Weight
Hrr-—
operation.
Cu
Zn
62.5
30.6
35.2
59.6
<J
9.8
100.0
100.0
2.
i
•
.
29
SECTION III.
Effect of zinc sulphate.
In Test 12, the procedure
of Section II was followed, with the exception that zinc
sulphate was used as depressant instead of ferrous sulphate.
It was found necessary to shorten the time of flotation.
The procedure of Tests 13 to 17 was identical with
that used in Test 12, with the exception that the ore was
ground to 55 percent minus 200-mesh.
An examination of Table IX shows that 80.i percent
of the copper was recovered in the concentrate which assayed
25.4 percent copper. Attention is drawn to the short flotation
period.
It was found that a long time of flotation resulted
in a concentrate high in'iron, and that it was not until
the time of flotation was shortened that a good copper
concentrate was obtained.
In comparing results of Test 12 with those obtained
in Test 17, it will be noted that a close control of the
hydrogen ion concentration is necessary.
The low weight
percent of the tailing in Test 17 may be attributed to the
low pH value which caused flotation of pyrite. On the other
hand, a very high pH value does not favor selectivity.
Probably, because of the formation of zincates in strongly
alkaline solutions, fewer zinc ions are available to oppose
activation than in neutral solutions; activa,tion is therefore
possible with lower copper-ion concentration in more
alkaline solutions.
Tests 13, 14 and 15, were run under identical laboratory conditions.
The object was to study the effect of*
higher and lower xanthates in the series. Apparently, all
three xanthates are suited for this work.
The results of the experimental runs show that, under
the stated conditions, a rejection of 22 percent of the
total zinc is all that can be expected. An increase of
sodium cyanide added to the conditioner results in a
decrease of the copper recovery. An increase of the amount
of zinc sulphate does not affect the results.
31
Table
IX
No.
Test
CONDITIONS
CONDITIONS
Time 1 %
Mins, Solid pH
POINT OF
ADDITION
Grind
40
7.0
Condition
6
21
7.7
Flotation
Cleaner
Flotation
2.5
21
8.0
AMD REAGENTS
REAGENTS POUNDS PER
Lime
NaCN
ZnS04
4.0
0.25
1.0
C l e a n . Cone,
Feed
TON
208
.
v-». A .
0.2
0.1
0.05
0.05
.
i
.
Note short flotation time.
Ore ground to 81 per cent minus 200 mesh,
PRODUCT
Tail
KBX
0.2
METALLURGICAL
Middling
12
6
j
Remarks:
No.
%
Weight
RESULTS
.
% DISTRIBUTION
ASSAYS
Cu
Zn
Cu
15.8
28.4
9.32
80.1
43.3
8.0
8.2
11.8
34.8
76.2
0.6
8.1
21.9
100.0
100.0
100.0
5.6
14.7
0.98
3.4
Zn
!
L _ _ _ —
Ratio of Concentration:
Remarks:
6.3 to 1
32
Table
No,
X
Test
CONDITIONS
Time j %
MIns. j S o l i d
Grind
5
21
Flotation
6
21
Flotation
6
16
TON
REAGENTS POUNDS PER
PH
Lime
NaCN
ZnS04
7.0
0.1
0.3
40
Condition
13
AND REAGENTS
CONDITIONS
PCINT OF
ADDITION
No,
208
KBX
P.O
0.05
0.05
0.04
-*
0.2
10.2
0.03
*
1 ,
Remarks:
C r e s y l i c Acid was used a s the frother,
METALLURGICAL RESULTS
% DISTRIBUTION
ASSAYS
%
Weight
Cu
Concentrate
22.3
21.8
Scavenger
14.3
Tail
63.4
Feed
100.0
PRODUCT
Zn
Fe
Cu
11.8
17.6
90.0
88.0
10.4
3.1
1.8
40.0
8.1
8.8
15.2
0.16
0.15
44.4
1.9
3.2
74.4
5.4
2.99
37.5
100.0
100.0 100.0
,_
Ratio of Concentration:
5 to 1
Remarks:
Fe
Zn
~Ji_
Table
RESULTS
TEST
NO.
PRODUCT
%
V/EIGHT
Cu
No. XI
OF BATCH
ANALYSIS
Zn
FLOTATION
TESTS
% DISTRIBUTION
Cu
Zn
. " ' -1, '.• •• ••—:-.
Trt.iT •
REMARKS
14
Concentrate 23.1
Scavenger
15.5
61.3
Tailing
100.0
Feed
19.1
3.2
1.24
5.6
78.7
8.8
13.5
100.0
PH: 10.5
55# -200 mesh
15
Concentrate 23.3
Scavenger
11.2
Tailing
65.5
Feed
100.0
21.7
3.6
0.3
5.6
89.1
7.1
3.8
100.0
Amyl Xanthate
was used as
the c o l l e c t o r
16
Concentrate 20.8
79.2
Tailing
100.0
Deed
22.0
1.2
5.5
17
Clean. Cone 18.3
24.7
Middling
57.0
Tailing
Feed
100.0
26.0
10.6
1.2
3.2
83.2
16.8
100.0
69.9
30.1
100.0
ijL~.
pH: 10.6
55$ -200 mesh
pH: 7 . 0
J
34
Table
XI
REAGENTS
<
—
TEST
No. •
•
•
•
••
•
• '
REAGENTS
Lb/TON
1
POINT OF .ADDITION
i
l
14 j
Lime
Sodium cyanide
Zinc sulphate
Aerofloat 208
1 Ethyl xanthate
Pine oil
i Cresylic acid
15 j
:
1 6
17 j
!
.
j
7.0
0.1
0.3
0.23
0.09
0.05
0.05
7.0
0.1
0.3
Lime
Sodium cyanide
Zinc sulphate
Aerofloat 208
Amyl xanthate
Pine oil
Cresylic acid
0.23
0.09
0.05
0.05
2.5
Ball mill.
0.35
Ball mill.
1.0
0.2
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
0.6
0.2
0.05
0.1
•
Ball mill.
Ball mill.
Ball mill.
Blotation cell.
Flotation cell.
Flotation cell.
Flotation cell.
0.05
0.05
0.25
Lime
Sodium cyanide
Zinc sulphate
Aerofloat 208
Butyl xanthate
Cresylic acid
Ball mill.
Bail mill.
Ball mill.
Flotation cell.
Flotation cell.
Flotation cell.
Flotation cell.
Ball mill.
Ball mill.
Ball mill.
Conditioner.
Flotation cell.
Flotation cell.
7.5
Lime
Sodium cyanide
Zinc sulphate
Aerofloat 208
Butyl xanthate
Pine oil
I
!
!
j
J
35
SSCTIOE" IV.
Sffect of zinc and ferrous sulphates, A 600-gram
charge was ground for a period of 45 minutes to approximately
SC percent minus 200-mesh. Lime, sodium cyanide, zinc and
ferrous sulphates were added at the start of the grinding
period.
As may be noted in comparing Table XII with Tables VTII
and IX, these two salts have a slightly greater toxic effect
when combined than when used independently.
The procedure of Test 19 was identical with that
used in Test 18 except that the amount of ferrous sulphate
was increased to 0.3 pounds per ton. Under these conditons,
the froth became brittle. This in turn may be said to have
caused the low percentage of the concentrate.
Lacrosccpic examination of the products showed that the
cleaner concentrate contained very little pyrite; however,
a considerable percentage of sphalerite was present. The
tailing contained 3 to 4 percent of £he total sphalerite.
The results of these tests indicate that, though
an excellent rejection of the pyrite was obtained, the copper
sulphides cannot be separated from sphalerite
with this
combination of reagents under the conditions investigated.
36
Table
No.
XII
Test
CONDITIONS
Time
Mins.
%
Solid
45
40
Condition
5
21
Flotation
Cleaner
Flotation
4
21
3
5
Grind
REAGENTS
pH
8.3
18
AND REAGENTS
CONDITIONS
POINT OF
ADDITION
No,
Lime
4.0
POUNDS PER TON
NaCN
F e S 0 4 ZnS0 4
0.13
KBX
208
0.3
0.7
0.05
0.15
0.05
8.2
i
Remarks:
C r e s y l i c Acid was used as the f r o t h e r .
Ore ground to 80 per cent minus 200 mesh.
METALLURGICAL
PRODUCT
%
Weight
RESULTS
% DISTRIBUTION
ASSAYS
Cu
Cu
Zn
Zn
14.0
28.5
11.9
72.5
53.5
2.8
27.2
21.7
13.9
19.7
Tail
83.2
0.9
1.0
13.6
26.8
Feed
100.0
5.5
3.1
100.0
100.0
Clean.
Cone.
Middling
i
Ratio of Concentration:
:
The p y r i t e was e f f e c t i v e l y
depressed.
.
37
Table
No.
XIII
Test
CONDITIONS
AND
CONDITIONS
POINT OF
ADDITION
Time
Mins.
No.
19
REAGENTS
REAGENTS
POUNDS
%
Solid
pH
Lime
FeS04
ZnS04
38
40
6.6
4.0
0.3
0.7
Condition
5
21
Flotation
Cleaner
Flotation
4
25
3
5
Grind
PER
NaCN
TON
208
KBX
0.3
0.15
1.0
0.05
8.2
i
Remarks:
Very brittle froth.
Cresylic Acid was used as the frother.
Ore ground to 66 per cent minus 200 mesh.
METALLURGICAL
PRODUCT
C l e a n . Cone
Middling
%
Weight
% DISTRIBUTION
ASSAYS
Cu
Zn
CU
Zn
10.1
4.2
Tail
85.7
Feed
100.0
Ratio of Concentration:
Remarks:
-
RESULTS
10 to 1
The cleaner concentrate contained no pyrite; however,
a considerable percentage of sphalerite was present.
The tailing contained approximately 4$ of the total
sphalerite.
38
SECTIOE V.
gffect of soditim sulphide. For Test 20, two 600-gram
charges of ore were prepared. Uach charge was ground and
floated separately following the procedure of Section IT,
except that sodium sulphide was added in place of ferrous
sulphate.
The resulting concentrates were combined and
cleaned by refloating in a loboratory-size Fagergren flotation
cell with additon of a small amount of cresylic acid. The
resulting products were assayed for copper and zinc. Details
of the test are shown in Table XIV.
An examination of Table XIV shows that 80.7 percent
of the copper was recovered in the cleaned concentrate which
assayed 29»2 percent copper and 4.1 percent zinc. The overall recovery of the copper in the rougher operation was
94.2 percent.
The results of these tests show an excellent improvement
in the rejection of sphalerite. However, a very close control
of the alkalinity seems to be necessary.
Considering the small amount of sodium sulphide added
one could attempt to explain its action as that of a
precipitant of the soluble copper, and also, as a reducer of
the amount of soluble zinc. The latter probably forms zinc
sulphite which is supposed to be an active depressant for
sphalerite.
39
Table
No,
XIV
Test
CONDITIONS
Time
Mins.
20
AND REAGENTS
CONDITIONS
POINT OF
ADDITION
No.
REAGENTS POUNDS
%
Solid
PH
Lime
NaCN
ZnS04
48
40
*
4.0
0.3
0.7
Flotation
6
22
7.8
Flotation
6
8
Grind
PER TON
NaoS
208
KBX
0.15
0.07
0.5
i
Remarks:
* pH b e l o w 7 a t b a l l m i l l .
C r e s y l i c A c i d was u s e d a s t h e
METALLURGICAL
PRODUCT
%
Weight
frother.
RESULTS
% DISTRIBUTION
ASSAYS
Cu
Zn
Cu
15.2
29.2
4.1
80.7
19.4
4.5
16.4
9.3
13.5
13.1
Tail
80.3
0.4
2.68
5.8
67.5
Feed
100.0
5.5
'T,
100.0
100.0
Clean.
Cone,
Middling
Ratio of Concentration:
Remarks:
O
Zn
Table
RESULTS
TEST
NO.
PRODUCT
Cu
21
Clean. Cone. 14.7
7.9
Middling
Tailing
77.4
Feed
100.0
28.8
16.5
0.42
5.86
22
Concentrate
Scavenger
Tailing
Feed
20.4
21.5
23
8.7
11.6
79.7
100.0
Clean. Cone. 15.2
8,5
Middling
Tailing
82.3
Feed
100.0
BATCH
ANALYSIS
%
V/EIGHT
OF
No,
Zn
4.7
11.0
2.23
3.28
0.7
5.4
FLOTATION
TESTS
12.4
32.0
0.75
3.3
1
% DISTRIBUTION
1
Cu
Zn
72.2
?P P
5.6
100.0
21.0
26.4
52.6
100.0
78.8
10,2
11.0
100.0
REMARKS
57.1
24,2
Id.7
100.0
i
84$ minus
200 m e s h .
pli: 7 . 6
55$ m i n u s
200 m e s h .
pH: 1 0 . 9
32.9
46.2
20.9
100.0
1.4
5.4
28.0
22.0
XV
pH:
8.4
;
Table
x v
REAG55ITS
J
TEST
No.
—
"•
•• "
REAGENTS
,
-
Lb/TON
POINT OF ADDITION
— ^
i
21
j
22
•
1
23
-
l
1
Lime
Sodium cyanide
Zinc sulphate
Sodium sulphide
Aerofloat 208
Butyl xanthate
Cresylic acid
4.0
0.3
0.7
0.15 gr
0.15
0.07
0.05
Ball mill
Ball mill
Bail mill
Ball mill
Conditioner
Flotation cell
Flotation cell
Lime
Sodium cyanide
Sodium sulphide
Aerofloat 208
Aerofloat 31
Butyl xanthate
Cresylic acid
7.0
0.12
3.0
0.22
0.07
0.02
0.05
Ball mill
Ball mill
Ball mill
Conditioner
Conditioner
Scavenger circuit
Flotation cell
Lime
Sodium cyanide
Ferrous sulphate
Zinc sulphate
Sodium sulphifle
Aerofloat 208
Butyl xanthate
Cresylic acid
5.0
0.35
0.02
0.7
0.07
0.15
Ball mill
Ball mill
Ball mill
Ball mill
Bail mill
Conditioner
Flotation cell
Floation cell
ffl.06
0.1
42
SECTION VT.
In Tests 24 and 25 the effect of Aerosol 0. T. added
to the reagent combination of Test 12, Section III, was
studied.
Since Aerosol O.T. possesses distinct frothing
properties, a less amount of Aerofloat 208 was added at the
start of the conditioning period. This procedure allowed
the ore to be stage ground to pass a 150-mesh screen.
An examination of Table XVI shows that 79.8 percent
of the copper was recovered in a cleaned concentrate which
assayed 27.6 percent copper and 3.6 percent zincf
The writer
obtained a concentrate assay of 29.0 percent copper. This
assay, substituted in the metallurgical balance, gave a
composite assay which is closer to the head analysis than
that obtained by the use of the first quoted assay. Using
this value, the over all copper recovery is 91.2 percent.
The role of the wetting agent in this flotation test
is not fully understood.
Since Aerosol O.T. is a powerful
wetting agent, its action could be said to be analogous to
that of a detergent in laundering.
That is, it cleans the
surface of the sphalerite thus permitting zinc -sulphate and
sodium cyanide to act more readily as depressants.
The results of these tests are satisfactory; however,
an improvement in the results may be obtained by adjusting
the amounts of reagents to the proper conditions. Lack
in time prevented further investigation.
f? Assay by Moonlight Laboratories, Butte, Montana.
43
I
Table
No.
XVI
Test
CONDITIONS
AND REAGENTS
CONDITIONS
POINT OF
ADDITION
Time
Mins.
Grind
%
Solid
3
21
Flotation
Cleaner
Flotation
8
21
24
REAGENTS POUNDS PER TON
pH
40
Condition
No.
Lime
HaCN
ZnS0 4
O.T.
4.0
0.3
1.0
0.1 '
7.8
208
KBX
0.15
0.06
0.2
6
*
1
Remarks:
Ore g r o u n d t o 100 p e r c e n t m i n u s 2 0 0 - m e s h .
C r e s y l i c A c i d was u s e d a s t h e f r o t h e r .
METALLURGICAL
PRODUCT
%
Weight
RESULTS
% DISTRIBUTION
ASSAYS
Cu
Zn
Cu
Zn
13.8
27.6*
3.66
79.8
18.0
5.4
9.74
6.6
11.0
i,-:.6
Tail
80.8
0.54
2.4
9.2
69.4
Feed
100.0
4.77
2.81
100.0
100.0
Clean.
Cone.
Middling
„
Ratio of Concentration:
„ ±
7 to 1
Remarks:
* 2 9 . 0 p e r c e n t c o p p e r a s a s s a y e d by t h e
writer.
44
Table
No.
XVII
Test
CONDITIONS
Time
%
LELns. Solid
Grind
REAGENTS POUNDS PER TON
PH
3
Flotation
8
Lime
WaCN
ZnS04
0.3
1.5
4.0
40
Condition
25
AND REAGENTS
CONDITIONS
POINT OF
ADDITION
No.
21
O.T.
208
KBX
0.15
0.06
0.2
0.1
8.2
i
.
---
Remarks:
Ore g r o u n d t o 1 0 0 p e r c e n t m i n u s 2 0 0 - m e s h .
C r e s y l i c .kciu was u s e a a s t h e f r o t h e r .
METALLURGICAL
PRODUCT
%
Weight
RESULTS
% DISTRIBUTION
ASSAYS
Cu
Zn
Cu
Zn
9.2
22.3
2.89
38.0
8.8
Middling
10.3
16. a
4.24
30.9
11.4
Tail
80.5
2.0
2.97
31.1
79.8
Feed
100.0
5.4
3.00
100.0
100.0
Clean.
Cone.
Ratio of Concentration:
Remarks:
45
SECTION V I I .
Test 2 6 .
Object:
To i n v e s t i g a t e t h e e f f e c t of sodium
s u l p h i t e as a d e p r e s s a n t of s p h a l e r i t e .
Reagents:
Ball mill
Lime
Sodium cyan I d e
7.0
0.1
3.0
pounds p e r ten.
II
II
»
«
•
•
0.2
pounds per tQn .
0.04
0.05
pounds per ton.
0.03
0.02
0.05
pounds per ton.
"
•
•
"
" "
Sodium s u l p h i t e
Conditioner
Aerofloat
208
Copper rougher
Butyl x a n t h a t e
Pine o i l
Copper s c a v e n g e r
Reagent 208
Butyl x a n t h a t e
Pine o i l
Rftttarks:
H
N
N
The weight p e r c e n t of t h e p r o d u c t s was:
copper rougher concentrate 21.6 percent;
copper scavenger
concentrate 2.8 percent; t a i l i n g 71.4 percent.
The copper
c o n c e n t r a t e a s s a y e d 24.2 p e r c e n t copper which would give
a r e c o v e r y of a p p r o x i m a t e l y 90 p e r c e n t .
The r e s u l t s I n d i c a t e t h a t t h e method h a s
of p r o d u c i n g a s a t i s f a c t o r y
separation.
possibilities
46
Test 27.
Object:
To study t h e effect of potassium bichromate
as a depressant of s p h a l e r i t e .
Reagents:
Ball mill
Lime
Sodium cyanide
Conditioner
Potassium bichromate
Reagent 208
7.0
7-0
pounds per t o n .
pounds per t o n .
1.0
0.2
pounds per t o n .
0.05
0.05
pounds per ton
w
"
"
11
n
II
Copper c i r c u i t
Butyl xanthate
Pine o i l
pH: 10.5
Remarks:
The approximate copper content, as determined
by a grain count, was:
copper rougher concentrate 21 percetat.
T a i l i n g 4 percent copper.
Appaeently, potassium bichromate has no effect upon
the s p h a l e r i t e .
.Another t e s t was performed at a pH value
of 7-Q with I d e n t i c a l r e s u l t s .
47
Test 2 8 .
Ob j ect:
To regulate t h e pH value by t h e use of
sodium carbonate, and to study the effect
of t h i o c a r b a n l l i d e as c o l l e c t o r .
Reagents:
Ball m i l l
Sodium carbonate
Sodium cyanide
Thiocarbanllide
4.5
0.2
0.08
pounds per toon.
0.05
pounds per t o n .
n
H
II
Copper c i r c u i t
Cresylic acid
Ph : 7.7
Remarks::
22 percent copper.
The copper cleaner concentrate contained
The 73 percent by weight of the t a i l i n g
I n d i c a t e s a f a i r l y good r e j e c t i o n of p y r i t e .
48
Test- 2 9 .
Object:
To I n v e s t i g a t e the effect of sodium
Aerofloat In conjunction with cyanide In
a highly a l k a l i n e c i r c u i t .
Reagents:
Ball m i l l
Lime
8.5
0.1
pounds per t o n .
»
«
H
Sodium cyanide
Conditioner
Sodium Aerofloat
Copper c i r c u i t
Pine o i l
pH: 12
0.2
pounds per t o n .
0.1
pounds per ton.
Remarks:: Sodium Aerofloat did not produce a s u i t a b l e
s e l e c t i v i t y under t h e s e c o n d i t i o n s .
The concentrate
contained approximately 17 percent copper.
I t contained
a l s o a considerable percentage of the s p h a l e r i t e .
49
SUlffiLARY
The flotation results on a sample of ore from the
Alejandria mine of Sociedad Minera Puquio-Cocha, Lima, Peru,
may be summarized as followst
1.
The head assay is given bellow:
Capper
Zinc
Silver
Iron
Lead
2.
A microscopical examination
5.3 %
3.2 %
5.2 Oz/Ton
34.5 %
0.52 %
showed the presence
of pyrite, chalcopyrite, enargite, sphalerite, bornite,
chalcocite, "gray copper1* minerals and galena. Silicates
and carbonates appeared to be the chief constituents of
the non-sulphide gangue.
3.
The silver minerals apparently occur with the
chalcopyrite and enargite.
4.
Fine grinding, 85 percent minus 200-mesh, is
necessary to liberate the copper minerals from the sphalerite.
5.
The de-activation of sphalerite by sodium cyanide,
with subsequent removal of the cyanide, was studied. A
concentrate assaying 25.5 percent copper and 4.1 percent
zinc was obtained.
6.
Using ferrous sulphate in conjunction with
cyanide, no selectivity could be obtained. A bulk concentrate
of sphalerite and copper minerals was obtained.
50
7.
Using zinc sulphate in conjunction with cyanide,
a rejection of 22 per cent of the total zinc is all that can
be expected.
8. A test in which ferrous sulphate and zinc sulphate
were used indicates that though an excellebt rejection of
the pyrite was obtained, the copper sulphides cannot be
separated from sphalerite with this combination of reagents.
9. A concentrate assaying 29.2 percent copper and
4.1 per cent zinc was obtained when grinding in the presence
of sodium sulphide.
10.
A concentrate assaying 27.5 percent copper and
3.6 percent zinc was obtained when grinding in the presence
of a small amount of Aerosol O.T.
11. Potassium bichromate and sodium sulphite were
tried as depressants, and thiocarbanllide and sodium
Aerofloat as collectors. Very poor results were obtained
with these reagents.
51
COFCLUSIOUS
The results of the flotation tests show that a
recovery of approximately 80 percent of the copper was made
in a high grade cleaner concentrate assaying 29 percent
copper containing an average of 4.5 percent zinc. In calculating
the recovery no attempt was made to eliminate the middling
product.
From experimental work not recorded, it has been
found that at least 60 percent of the copper in the middlings
can be recovered, thus raising the total recovery.
The practice, as indicated by Tests 23 and 24, will
be to grind with cyanide, zinc sulphate and sodium sulphide
or Aerosol 0. T. to at least 85 percent through 200-mesh.
The copper can then be floated by addition of Aerofloat 208
to the classifier overflow and butyl xanthate to the head
of the copper flotation circuit. A close control of the
alkalinity is necessary when using sodium sulphide as the
zinc depressant.
Attention is called to the results obtained in
Section VI. Lack of time prevented further investigation
along this line. Hovrever, it is believed that a substantial
improvement in the results may be obtained by adjusting the
amount of reagents to the proper conditions. Doubtless,
the low results are also due to excessive oxidixation taken
place as the acidity of the ore showed a consistent increase
as the work progressed.
BIBLIOGRAPHY
1.
Gaudin, A. K . ,
" P r i n c i p l e s of I ' i n e r a l D r e s s i n g " ,
(1939).
2.
R a v i t z , S . F . and 7 . Ao 7 / a l l , J o u r n a l of P h y s i c a l Chemistry, Vol. 38, (1934).
3.
7/ark, I. 77. and A. B. Cox, "Principles of flotation",
Trans. Am. Inst. Kin. and ^et. Eng., Vol. 112, (1934)
4.
Tark, I. "/., "Principles of Flotation", (1938).
Gaudin, A. K., C. B. rlaynes and 2. C. Haas, "Flotation
Fundamentals", Utah Zng. Exp. Stat., Tech. Pub. no. 7,
Part 4, (1930).
6.
Campbell, A. B., 77. Howes and H. Ode, U. S. Bureau of
Mones, R. I. ITo. 3149, (1932).
7.
Tucker, 3. L., J. F. Gates and R. S. Head, Trans. Am.
Ins. Min. and wiet. Sng., Vol. 73, p.372, (1926).
8.
Winkler, k.,
9.
Dean, R. S., J. B. Clemmer and S. R. B. Cooke,
"Use of wetting agents in flotation", U. S. Bureau of
Kines, R. I. 3333, (1937).
irorman, J. 2. and 0. C. Ralston, "Conditioning Surfaces
for Froth flotation", Trans. Am. Inst. Kin. and Let.
Eng., Vol. 134, (1939).
10.
Ket. und Erz, Vol. 31, p.358, (1934).
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