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Patented Dec. 10, 1946
‘2,412,217
UNITED ‘STATES PATENT OFFICE
2,412,217
FROTH FLOTATION OF CHROMITE
WITH FLUORIDE
Richard Havens, Salt Lake City, Utah, assignor to
the United States of America, as represented by
the Secretary of the Inter-lor
No Drawing.‘ Application December 19, 1944,
'
'
‘Y Serial'No. 568,908
' 5 Claims.‘ (01. zo9_166)
(Granted under .the act of March 3, 1883, as
amended April 30,1928; 370 0. G. 757)
The invention described herein may be_manu
cordance with this invention include any of the
factured and used by or for the Government of
the United States for governmental purposes
without the payment to me of any royalty thereon
in accordance with the provisions 'of the act of
usual ores from which chromium is derived such
as for example Oregon beach sands containing
plants formerly discarded, and other‘ similar
April 30, 1928 (Ch. 460, 45 Stat. L. 467).
chromite-containing ores.
chromite, the residues from gravity separation
'
This invention relates to the bene?ciation of
Suitable soluble ?uorides‘ for employment in
chromium ores, and more particularly to the
accordance with this invention include any ?u
production of a chromite ore concentrate. Here
orine compound which is soluble in an, aqueous
tofore, attempts have been made to bene?ciate 10 menstruum or pulp, or which becomes soluble
chromium ores by magnetic separation, gravity
therein under acidic conditions ranging from the
concentration, and ?otation methods but in the
strongly ‘acid to the moderately acid pH range.
case of gravity or magnetic methods very expen
Examples of suitable ?uorine compounds are hy
sive equipment is required and the ?otation meth
dro?uoric acid, the alkali metal ?uorides such
ods have not been particularly satisfactory from 15 as sodium, potassium and lithium ?uoride, the
the standpoint of yields and quantities of reagents
soluble silico?uorites such as sodium and potas
employed.
sium and ammonium silico?uorite, and similar
ionizable ?uorine compounds which are appre
Accordingly, this invention has as an object
the provision of a practical and economical proc
ciably soluble in water at a pH range between
ess for the bene?ciation of chromium ores. 20 about pH 1.5 and pH 5.5.
Another object is to provide a mineral concen
- The bene?ciation of chromium ores for example
trating treatment for the bene?ciation of chro
' chromites, is carried out under acidic conditions
ranging from the strongly acid to the moderately
mium ores involving selective ?lming of a desired
acid and generally within a pulp acidity of be
mineral and the production of a high-grade
chromium containing concentrate. A further 25 tween pH 1.5 and pH 5.5 peferably, however, the
object is the provision of a ?otation process or
pulp acidity is maintained within the more re
stricted pH range of between pH 2.5 and pH 4.5
other mineral ?lming treatment wherein a high
grade of concentrate is produced with maximum ' in order that the acidity cooperate to best ad
recovering of chromium-bearing material with
vantage with the soluble ?uoride to accomplish a
a very low consumption of reagents. Other and 30 good recovery of high-grade chromite concen
further objects will be apparent or will appear
trate, While the exact function of the soluble
hereinafter as this speci?cation proceeds.
?uoride in this method for bene?ciating chro
These objects are accomplished in accordance
mium ores is not entirely understood, and there
with this invention wherein chromium ores are
‘fore it is not desired to limit this invention
bene?ciated by subjecting them to a mineral 35 to any particular theory of reaction, neverthe
concentrating treatment involving selective ?lm
less it is thought that the soluble ?uoride under
ing under acidic conditions in the presence of
acidic conditions accomplishes several things
a soluble ?uoride. Desirably, a soluble ?uorine
among which may be mentioned the cleaning of
compound capable of yielding ?uoride ions under
the ‘mineral surface, the dispersion of slimes, the
acidic conditions is employed. 1‘ While agglomer
,depression of undesired gangue materials such as
ation tabling concentrating treatments, bulk ?o
tation and similar mineral concentrating treat
ments involving selective ?lming of one or more
selective activation of the chromite particles en
abling them to be readily ?oated away from
garnet, ilmenite, quartrv and the like, and the
ore constituents can be employed, it is preferred
gangue constituents.
*
to employ a froth ?otation concentration in 45 In carrying out the bene?ciation, of chromium
volving agitation and aeration of an aqueous pulp
ores, the ores are preferably ground by customary
of a comminuted chromium-bearing ore, and the
means to provide liberation of the chromite or
ensuing description will largely be directed to
other chromium-bearing material from the
gangue constituents, and generally the chromium
Suitable chromium ores for employment in ac 50 bearing ore is comminuted to particle size between
this type of mineral concentrating treatment.
_
51,412,217
3
minus 20-mesh and minus SOO-mesh; preferably
eral acids, generally in amounts of from 1 to 11
pounds of acid per ton of ore, and preferably
from about 3 to about 7 pounds‘ of acid per ton
of ore, such as for example nitric acid, hydro
the particle size of the ore is maintained within
the more restricted range of between minus
48-mesh and minus zoo-mesh.
By the expression "minus --—-mesh" is meant
a particle size which passes through a standard
Tyler screen having the stated number of meshes
per linear inch.
chlorlc acid, and preferably the cheap and read
ily available sulfuric acid. Sulfuric acid has the
additional advantage in this invention of remov
ing soluble calcium salts from the pulp and there
by preventing any interference with the mineral
concentrating treatment which might result from
the presence of soluble calcium salts in the pulp.
In carrying out this invention in accordance
with the foregoing principles, the selected chro
,
In general, it has been found that superior re
sults are secured when the selected chromium
ore is stage ground and when it is deslimed, that
is to say freed from particles having diameters
less than 10 microns, prior to the treatment of this
invention. In desliming the ore, treatment with a
mium ore is ground in a suitable device such as a
small amount of sodium silicate appears to facili 15 ball mill, then preferably although not necessarily
tate dispersion of the slimes and their subsequent
deslimed by washing with an excess of water to
removal. as by washing of the desired sands with
remove colloidally dispersed material, and there
a large excess of water. A suitable amount of
after the sands are diluted to a pulp consistency
sodium or other soluble silicate is from 1 to 10
of generally about 25 percent solids. Thereafter,
pounds of soluble silicate per ton of ore.
20 the pulp is conditioned by agitating with an
In the practice of this invention, it has been
amount of strong mineral acid su?icient to bring
found that the employment of along chain fatty
the pH range of the pulp within the desired acid
acid having from 8 to 18 carbon atoms-as a col
ity, and the fatty acid collector (preferably emul
lector or collecting agent results in a superior
si?ed or dispersed with the dispersing agent se
grade and recovery of chromium concentrate 25 lected), is incorporated with the pulp. There
when employed in conjunction with the acidic
after, the soluble ?uoride is incorporated in the
pulp and the soluble ?uoride of this invention.
selected amount, the pulp is conditioned for a
Suitable long chain fatty acids, generally em
suitable length of time, and flotation is initiated.
ployed in amounts of from 0.5 to 5 pounds per ton
Any suitable ?otation machine can be employed,
of ore and preferably within the more restricted 30 such as for examplethe Denver Cell or the Callow
range of from about 1 to 4.5 pounds of fatty acid
type of ?otation machine. The usual rougher and
cleaner procedures are employed and this inven
per ton of ore, include the fatty acids derived
from vegetable, animal, marine and synthetic
' tion can well be utilized in a cyclic process where
sources having from-8 to 18 carbon atoms in the
in the tailing water and middling ore fractions.
molecule, examples being the fatty acids derived
are returned to the process.
,
The following illustrative examples show how
from olive oil, palm oil, coconut oil, castor oil,
the invention may be carried out, but it is not
sun?ower seed oil, sesame oil, linseed oil, whale
limited thereto. Parts and percentage composi
oil, sardine oil, menhaden oil, and the synthetic
tions are by_ weight unless otherwise designated.
fatty acids produced in the oxidation of petroleum
and similar hydrocarbons. Lauric acid, palmitic 40
EXAMPLE I
acid, stearic acid and preferably oleic acid have
ORE: MoUAr Crmomrr:
been found eminently suitable for employment in‘
this invention.
Treatment-This sample represents consoli
Highly efficient results and considerable reagent
dated ores requiring grinding for liberation of
economy have been effected in the practice of this 45 the chromite from which chromite may be re
invention when the fatty acid collector employed
covered by ?otation. Ore roll crushed minus 10!
is incorporated in the form of a stabilized emul
mesh was stage ground minus 48-mesh and de
sion or dispersion with the ore pulp, and to this
slimed. Sands were conditioned 1/;_»-hour with
end it is preferred to employ a small amount
H2804 solution and deslimed. Sands were pulped,
of a dispersing agent together with the fatty acid, 50 conditioned and chromite ?oated. Chromite con
a suitable dispersing agent being the ammonium
centrate cleaned and recleaned.
salt of lauryl diethylene glycol sulfate sold by
Table 1
the Emulsol Corporation of Chicago, Illinois,
REAGENTS,
POUNDS
PER TON or ORE
under the trade name “Emulsol X-l.” Other
dispersing agents stable to acidic conditions can, 55
Cond. Rougher Cleaner Recleaner
of course, be employed to achieve the same and,
representative examples being starch, salts of
long chain amines, and alkylol amine salts of the
fatty acids themselves. “Emulsol X-l” as above
de?ned however constitutes apreferred dispers
ing agent for use. The dispersing agent, gener
ally employed in amounts of from .1 to 2.5 pounds
H¢SO4 _________________ __
60
NaF ___________________________ __
3.33‘
3.33
1.66
1.66
1.66
1.66'
Oleic acid ______________________ ..
“Emulsol X-l” ________________ ..
l. 33
. 27
. 50
. 10
. 25
.05
METALLURGICAL DATA
per ton of ore and preferably in an amount with
in the more restricted ores from 0.2 to 2.0 pounds
Per
per ton of ore, is preferably incorporated with a 65
suitable amount of water and with the selected
long chain fatty acid such as oleic acid prior to its
incorporation with the ore pulp for greatest re
agent economy.
Product
To achieve the desirable acidic pulp conditions 70
in accordance with this invention, one may em
ploy hydro?uoric acid itself to supply both the
soluble ?uoride and the necessary pH range as
above discumed, but in general it has been found
75
Assay, per cent
Chromite conct. 1..
Distribution
per cent '
cent
wt.
Cl‘zOa
Chromite conct. 2_ _ r
,
equally satisfactory to employ other strong min
5.8
37. 9
9. 5
F0
41.4
22. 0
39. 4
2o. 8
22.
16.
7.
l4.
17. 2
14. 6
9. 9
13. 8
3>
3
0
0
siol
CHO:
F8
l. 8
62. 2
50. 3
5. 2
14. 8
ll. 9
3.
6.
8.
4.
9
0
6
5
4. 5
8. 2
18. 5
6. 6
100. 0
100.0
77.0
62. 2
Recleaner tailing. __
Cleaner tailing- _ _ __
Rougher tailing- _ . _
Slimes ____________ __
4. 3
9. 3
31. 0
8. 0
______ _ _
______ __
______ _.
______ __
Calculated heads_
100.0
25. 2
l6. 6 ______ ._
Combined concts__ _
47 4
41. 0
21. 8
2. 5
9,412,217
5
EKAMPLEII
6
EXAMPLEIII
On: Casno Cmonrrr Burns
Scum Amman
Treatment-This sample represents a source
of chromite losses as tailing from a typical ?o
tation mill from which chromite can vbe recov
The unconsolidated sands as received were
screen sized and results are given in Table 3.
Table 3
ered by ?otation to improve plant metallurgy.
A sample of slimes as received was pulped with
SCREEN ANALYSIS OF HUMPHREYS GOLD
CORPORATION OONCEN’DRA'I‘ES
sodium silicate and deslimed. Bands were pulped, 10
conditioned. and chromite ?oated. Chromite
Distribution
concentrates were cleaned and recleaned.
P...
Wm... ‘WW "8"‘
“ct
Table 2
CnOl
15
REAGENTS, POUNDS PER TON OF ORE
+48-mesh _____________ __
10.3
CnOl
Fe
23.3
2.00
3.14
_
sue
22.6
23.0
88.15
02.41
3.10
21.0
23.0
ass
3.85
Calculated heads-.
100.00
225
2&0
Recleaner
“a
Fe
-10o+mman _______ ..
—48+100-mesh_-
Desliming Rougher Cleaner
mm '
cent
100.00 100.00
20
Sodium silicate ____ . _
3. 7
NaF .............. _.‘.
4. 6
0.
H2801 ___________ _- _
“Emulsol X-l" .... __
:9
6. 8
.2
________ _.
.1
2.6
.02
l. 8
.9
CHEMICAL ANALYSES, PER CENT ,
.1
1.8
.02
ono. Fe Bio. Mgo' 111,0. CaO zro, T10,
25
METALLURGICAL DATA
Humphreys
GoldCorp- 24.60
Assay, per cent Dist'gggém’
Product
wt" per
30
pe
cent
CHO]
Fe
CnOl
21.0 15.9_
4.2
17.4
1.0 __________ ._
Beach sands'as received were pulped with Salt
Lake City tap water to about 50 percent solids
and an emulsion of oleic acid stabilized with
Fe
“Emulsol X-l” was added until ?occulation was
Chromite conct. 1 _____ -_
Chromite oonct. 2 _____ __
Recleaner tail. 2 ....... ..
9. 33
2.19
3. 84
40. 8
34. 1
19. 3
11. 85
1O. 25
7. 2
37. 3
7. 3
7. 2
18. 6
3. 7
4. 7
Recleaner tail. 1...
11.33
18. 1
7. 2
20. 0
13.8
Cleaner tail ___________ _.
Rougher tail __________ ._
Slimes ................ . .
7. 31
39. 86
28. 14‘
ll. 4
1. 8
6. 0
4. 1
8. 1
7. 1
5. 1
6. 6
13. 0
7. 4
27. 3
24. 6
Calculated heads____
100. (X)
10. 2
6. 0
100. 0
1(1). 0
_ 39. 6
ll. 5
44. 6
22. 3
Combined eoncts ...... ._
11. 52,
fairly complete. Sodium ?uoride was added in
35 ‘stages until some depression of the garnet was
noted. The pulp was then diluted to about 25
percent solids and dilute sulfuric acid was added
untll‘?ocs were clean of garnet and gangue. The
?occulated chromite then ?oated rapidly ‘and usu
40 ally no additional collector was required.
Results of ?otation tests on Humphreys Gold
Remarkaqslimes as received contained 73.0
percent minus 200-mesh and sands ?oated con
tained 73.5 percent minus 200-mesh.
Corporation primary concentrates are given in
' Tables 4, 5, and 6, except that magnetic separa
tion was employed on the chromite cleaner con
centrates in the test recorded in Table 4.
‘ram.
CHROMITE FLOTATION USING LARGE AMOUNTS OF FATTY ACID
Assay, percent
P duct
Wt..
'0
percent
Ratio
Cr/Fe
CHO:
Chromite cleaner concentrate 1 _______________ ..
Chromite cleaner concentrate 2- _
Chromite cleaner tailing ____ __
Rougher tailing ......... ._
Calculated head_ _ __
Distribution,v percent
_
F6
5101
Ono]
SiO|
49. 4
3. 1
11. 4
36. 1
43. 10
3a. 32
23. 80
0. 32
21. 0
21.0
22. 0
14. 8
l. 0
3. 6
9. 0
42. 8
S4. 4
4. 3
10. 8
0. 5
54. 9
3. 4
13. 3
28. 4
2. 9
0. 6
.6. 0
90. 5
100. 0
25. 10
18. 9,
17. 1
100. 0
100. 0
100. 0 ‘_ _____ __
44. 0
5. 4
46. 7
22. 0
19. 8
34. 1
0. 8
0. 6
79. 8
4. 6
45. 2
9. 7
2. 6
1.62
0. 3 ______ _
49. 4
8
21. 4
0.8
84. 4
54. 9
Nonmagnetic from chromite cleaner concen
tra
....................................... -.
Magnetic from chromite cleaner concentrate l...
Calculated head chromite cleaner concentrate .................................. -.
'
2. 9 ______ _
REAGENTS, POUNDS PER TON 0_F ORE
Oleic acid
Rougher "MANN! ~
Cleaner "Mailm-
4. 12
l. 75
“lkli‘l‘lw
0. 82
0. 36
NaF‘
11. 8
4. 7
also.
pH
11. 8
2. 7 _
5. 9 ...... ._
2,412,217
By ?otation, 05.0 percent or, the chromium was.
The results recorded in Table 4 show that 09.5
percent 01' the chromium was recovered in a
recovered in a rougher concentrate that assayed
38.8 percent CraOa. The ?nai chromite cleaner
rougher concentrate that assayed 39.3 percent
C1301. Final cleaner ?otation concentrate
showed a recovery of 88.4 percent of the chro
mium, assayed 43.1 per cent C1'2O3, 21 percent
lron,'1.0 percent S102, and had a chromium to
concentrate represented an 84.2 percent recov
ery oi’ the chromium. and assayed 41.50 percent
CraQs, 23.0percent Fe and 1.0 percent 810:. Re
suits were comparable to those given in Table 5
iron ratio of 1.40.
and reagent consumption wasiower.
'
.
By using low intensity magnetic separation to
reject magnetite and iimenite from the chromite 10
EXAMPLE 1v
'
_
' Proms: Mun-‘Sums A
cleaner concentrate, 79.8 percent of the total
chromium was recovered in a nonmagnetic prod
The following. ?otation tests recorded 111' Tables
uct that assayed 46.7 percent CrzOa, 19.8 per
7, 8, 9, and 10 were made on sands from the Pio
cent Fe, 0.8 percent 8102 and had a chromium to
neer mine. Procedure for ?otation on‘these sands
iron ratio of 1.62 to 1.
15 di?ers somewhat from procedure used in the ?o
Table 5
'
.
Assay, percent
Product
.
Distribution, percent
wt"
Ratio
percent
Cr/Fe
C1101
Fe
B10:
CHO‘
Fe
SlO|
Chromite cleaner concentrate 1 _______________ _.
Chromite cieaner concentrate 2 _______________ __
Chromite cleaner tailing ______________________ -Rougher tailing _____________ __
46. 6
4. 5
8. 8
40. 1
42.00
33. 72
21. 35
3. 33
20. 8
28. 4
25. 8
20. 9
1. 0
1. 6
9. 0
34. 3
80. 6
. 6. 2
7. 7
5. 5
44. 8
5. 8
l0. 5
38. 8
3. l
0. 5
5. 2
I 91. 2
Calculated heads ....................... __
100. 0
24.32
21. 6
15. 0
100. 0
100. 0
100. 0
.
REAGENTS, POUNDS PER TON 0F ORE
Oleic acid
“Exnlllllyol
NaF
H1801
pH
Rougher ?otation _________________________________________ _-
1. 49'
0. 30
2. 98
2. 19
3. 8
Cleaner ?otation __________________________________________ __
. 25
0.05
2. 39
1.00
______ __
The results given in Table 4 show a recovery
of 94.5 percent of the chromium in a rougher con
tation of chromite from Humphreys Gold Corpo
ration sands. The major object was to verify
substitution of hydro?uoric acid for the ?uoride
sulfuric acid circuit and study the effect of de
' in the ?nal chromite cleaner concentrate that 40 pressant addition ahead of fatty acid.
contained 42.00 percent CraOa, 20.8 percent Fe
CHEMICAL ANALYSES, PER CENT
and 1.0 percent S101. Smaller amounts of re~
agents were used in this test than in the one rec1101 1:. s10. MgO 111,01 c110_ 2101 T10,
centrate that assayed 38.4 percent C1‘2O3. How
ever, 80.6 percent of the chromium was recovered
corded in Table 4, but recovery of chromium was
not quite as good.
45 Pioneer-Mine
.
21.00I201 11.4
5.3
1.4
23 210 1.01
Table 6
Assay, percent ‘
Product
Distribution, percent
wt"
percent
Fe
810;
C1101
Fe
Chromite cleaner concentrate 1 ............... __
Chromite cleaner concentrate 2
50.1
2.9
41. 50
34. 26
21.0
25. 0
1. 0
2. 8
84.2
4. 0
53. 3
3. 3
Chromite cleaner
Rougher tailing
7.6
30.4
22.40
3.10
19.8
10.0
11.4
31.3
8.8
5.0
7.0
304
100.0
24.7
21.0
10.1
100.0
100.0
Y
' Calculated heads _________ _.- ............ ..
Ratio
‘
C1301
‘
Cr/Fe
' S10;
31
0. 5
1. z;
. 94
5.4 ______ __
91.0 ...... __
100.0
______ __
REAGENTS, POUNDS PER TON 0F ORE
Oleic acid
"1515111351
No!"
mso.
pH
Rougher ?otation _________________________________________ __
0. 97
0. 2)
2. 28
3. 04
3. 1
Cleaner ?otation __________________________________________ ._
. 25
. 05
1. 97
. 99
______ __
‘
Table 7
I
SCREEN ANALYSIS 0N PIONEER MINE HIGH CHROMITE SAND
Product
we,
mt
Assay, percent
01-101
+48-meah _________ __
—
-
oli-muh _____ ..
100____ _.
Fe
Distribution, percent
010,
58
12.3
30.5
20.
20.3
53.3
18.6
241
21.3
20.1
21.0
143
7.2
—100-mesh ........ -.
10.0
20.9
21.0
Calculatedhcads"
1000
22.7
201
01,0. .
‘
Fe
8101
3.0
5.1
103
203
51.0
30.1
525
301
400
100
11.1
100.0
1000
4.1
100.0
2,419,817
9
10
The screen analysis given in the table shows an
increase in chromite grade in the finer sizes with
silica, tending to remain in the coarser sizes.
Only a very small amount of minus 200-mesh
1. Sands as received were pulped with tap
water to about 50 percent solids and an emulsion
of oleic acid stabilized with “Emulsol X--1” was
material was present in the ore.
2. A dilute solution of 10 percent HF‘ was added
until the ?ocs were clean of garnet and gangue.
added until ?occulation waspronounced.
_
The procedure-for ?otation of chromite from
the Pioneer mine sands recorded in Table 8 was
‘as follows:
3. Flotation was carried out until all recover
able chromite had been removed in the froth.
.
Table 9_
-
.
CHROMITE FLOTATION EMPLOYIN G HYDRO GEN FLUORIDE IN PLACE OF vFLUORIDE-AO:ID
1
Product
Assay percent
wt"
Chromite cleaner concentrate ................. --
Distribution, percent
,
percent
Ono:
Fe
'
‘
Ratio
SiO|
a7
Ono:
Fe
Slog
Chromite cleaner tailing ...................... _-
53.0
7. 2
41.0
23. 6
2o. 3
20- 3
14. 6
19. e
7. 6
46. a
7. 8
Rougher
------------------------------ -_
49. B
5. 7
17. 0
30- 3
- 12. 8
45. 4
Calculated heads ....................... -_
100. 0
22. 2
18. 7
17. 8’
100. 0
100. 0
Cr/Fe
c. e
1.38
6. 0 ______ _
i
87. 4 ______ __
100. 0 ______ __
REAGENTS, POUNDS PER TON OF ORE
Olelo acid
Rongher ?otation
“Iii-111.1901
1. 94
Cleaner ?otatiom-
. _ _ . _
1. Sands as received were pulped with tap
30
’ water to about 50 percent solids, equal amounts
of sodium ?uoride and sulfuric acid were added
and the pulp was conditioned for 2 minutes.
0. 39
. . . _ . _ . . . . . . _.
HF
0. 62
..50
pH
3. 9
.... _
The rougher ?otation concentrate contained
38.6 percent CrzOa and showed a recovery of 87.2
percent ‘of the chromium.
By cleaning 'the
rougher ?otation concentrate 79.6 percent of the
chromium was recovered in a concentrate which
2. An emulsion of oleic acid stabilized with '
“Emulsol X-l” was added until all the chromite 35, assayed 41.0 percent CrzOa, 20.3 percent Fe, and
was well ?occulated.'
_
2.7 percent SiOz. Results were comparable to
those obtained in previous work but the con
sumption of HF was less in relation to the indi
3. The pulp was diluted with tap water to‘
, about 25 percent solids and all recoverable chro
mite was ?oated.
Table. 8
CHROMITE FLO'I‘ATION EMPLOYIN G FLUORIDE-AOID TREATMENT AHEAD OF FATTY ACID’
Assay percent
Product
Wt.,
percent
,
Ratio
I
Ono: ' Fe
Chromite cleaner concentrate ................. --
Distribution percent
’
'
S10,
2o. 9
Cr/Fe
CHO:
41.3
41. 5
1. s
77. 5
Chromite cleaner tailing ______________________ __
12. 7
25. 2
18. 4
13. 1
14. 4
Bonghertailing _______________________________ ._
46.0
3.9
16.6
32.9
&1
Calculated heads ....................... __
100. 0,
22. 1
18. 6
17. 4
100. 0
Fe
4e. 4
12. 6
~
41.0
100. 0
Bio:
3. c
1. 3c
i 9. 5 ______ __
sec
...... -_
100- 0 ______ ._
REAGENTS, POUNDS PER TON OF ORE
Oleic acid
"lki‘fwl
NaF
mso.
pH
Rough“- ?nfa?nn
4. m
0. 84
2. 0
2. 0
Cleaner ??’m??n
. 25
. 05
1. 0
1. 6 ______ ..
Results show that 91.9 percent of the chro
mium was recovered in the rougher chromite
concentrate at a grade at 38.4 percent CrzOc. By
cleaning the rougher concentrate, 77.5 percent
4. 4
cated consumption in the ?uoride-sulfuric acid
circuit.
EXAMPLE V_
Locxnn Tnsrmc
‘of the chromium was recovered at 41.5 percent
A locked rougher ?otation test was run on
CrzOa, 20.9 percent Fe and 1.5. percent SiOz. Re
Pioneer mine sands to determine the effect of re
sults were comparable to those obtained in pre
turning middlings and ?otation water to the cir
vious work, but the consumption of oleic acid
was higher in relation to that of NaF and H2804. 70 cuit. Six rougher tests were run, each of which
produced a clean roughervconcentrate, a-scaven
The object of the following test was to study
ger concentrate, and a rougher tailing. The
the e?ect of hydro?uoric acid on the ?otation of
scavenger concentrate, . together with tailing
chromit‘e when it is substituted for the ?uoride
water from each test, was added to the feed in
sulfuric acid circuit. The procedure employed
was as follows:
76 each succeeding test. Combined rougher tailings
2,412,217
11
.
12
ball mill and re?oated to produce a concentrate
Various changes can be made in the invention
since many apparently widely di?erin: em
and a clean tailing.
bodiments thereof will occur to one skilled in the
were later reground for 5 minutes in a laboratory
The combined ?otation
art.
What is claimed is:
1. A process for the bene?ciation of chromium
ores which comprises agitating and ‘aerating an
products were further: cleaned by removing mag
netite and ilmenite on a disc-type high intensity 5
magnetic separator. The results are given in
Tables 10 and 11..
Table 10
LOOKED TEST - 0N PIONEER MINE BANDS
-
P
‘°
,
duct
Assay percent
wt"
Distribution percent
'
percent
.
CnOt
I
‘ Fe
5101
C110:
Ratio
Cr/Fe
Fe
BiO:
A. Combined rougher chromite concentrate-..-.
D. Scavenger
its conet. irom No. 8 of
43. 8
41.4
no 5.
3. 0
81. 1
48. 6
............................ .-,.---_.._
Combined rougher tailings ....... _ _
.7
55. 5
23.0
7. 8
18.8
17. 0
15 0
29 4
.7
18. 2
.7
50. 7
Calculated heads ....................... _ _
100. o
22. 4
1a 4
17 a
100.0
100.0
B. Regrind cleaner chromite concentrate ______ ..
C. Regrind cleaner chromite taiiings'n'n
Regrind rougher tailings
’
5. 4
7. 0
43. l
36. 2
20. 9
l. 5
19. 2
16. 3
16. 8
4. 6
17. 0
34. 6
8. 7
6. 5
3. 0
39. 0
84. 0 ...... -
Calculated rougher tailings ............. _.
I 55. 5
7. 3
17.0
29 4
i8. 2
50. 7
92. 1 ...... -.
5. 6
5. 1
1. 4
6. 7
1. 29
. 88
TOTAL, REAGENTS, POUNDS PER TON OF ORE
Oleic acid
W215i???“
NaF
mso. “51””
R0“ her ?nfm?nn
___
____ _ _
Reg!’ (1 rougher ?otation _________________________________ __
2. 38
. 66
0- ‘8
. 14
0. 59
. 54
1. 60
l. 32
3- 6
3. 3
Regrind cleaner ?otation ..... _. ___________________________ _.
. 20
. 04
13
. 33
3. 4
aqueous pulp of such an ore in the Presence of
The‘ results of the locked ?otation tests in
dicated that the middlings would not build up 35 hydro?uoric acid, and a long-chain fatty acid at
in a continuously operated ?otation circuit and
a pulp acidity of between pH 1.5 and pH 5.5, and
that recovery and grade of concentrate are not
separating a chromium-containing froth as a
lowered by return of middlings to the ?otation
concentrate.
circuit. A chromite concentrate was made assay
ing 41.4 percent CrzOa and containing 81.1 per
cent of the chromite in the ore. The regrinding
and re?otation of the rougher ?otation tailing
indicated that a large part of the chromite lost
in the rougher tailing could be recovered in a
aerating aqueous pulp of a comminuted chromite
ore in the presence of a long-chain fatty acid,
and an acidic ?uorine compound at a pulp acidity
between pH 2.5 and pH 4.5, and recovering a
froth containing a chromite concentrate.
medium-grade product.
_
‘
2. In a process for the beneiiciation of chro
40 mium ores the steps which comprise agitating and
Table 11
I
MAGNETIC SEPARATION OF FLOTATION CONCENTRATEB [OBTAINED FROM LOCKED TEST
'
Product
Assay percent
Wt.,
percent
Distribution percent
'
CHO:
F8
’
S10:
CHO:
Fe
Ratio -
5104
Nonm
etlc from rodnct A ................. __
Magnet 0 from pro not A _____________________ _.
38. 8
5. 0
45. 3
18. 2
18. 9
33. 4
2. 0
0. 8
77. 1
4. 0
39. 6
9. 0
0. 3
7. 0
Calculated heads product A ____________ ._
' 43. 8
42. 2
20. 6
1. 9
B1. 1
48. 0
7. 3
Nonmagnetic from products A and B ______ ___...
Magnet 0 from products A and B _____________ ._
43. 1
6.1
44. 5
18. 8
18.4
33.0
2. 4
1. 6
84. 7
5. 1
43. 2
11. 0
0.8
7. 9
Cr/Fe
Calculated head products A and B _____ __
49. 2
41. 3
20. 2
2. 3
89. 8
54. 2
8. 7
Nonmagnetic from (Products A, B, C, D ______ _.
~ 50.0
41. 9
18.0
4. 4
91. 4
49. 0
0. 8
Magnetic from pro note A, B, C, D .......... -_
6. 9
19.0
> 32.2
1.6
5. 6
12.0
15. 2
Calculated head products A, B, C, D_..__
56. 9
39. 1
19. 7
4. 1
97. 0
61. 0
16.0 ______ __
The use of magnetic separation to remove
'3. Ina process for the bene?ciation of chro
small amounts of magnetite and ilmenite from ~65 mium ores, the improvement which comprises
?otation concentrates would permit plus 90 per
agitating and aerating an aqueous pulp of a
cent recoveries at 41.9v percent CrzOa grade or
comminuted chromite ore in the presence of a
grades up to 45.0 .percent CrzOa with lower re
long-chain fatty acid, a dispersing agent, and a
soluble ?uoride at a pulp acidity between pH 1.5
coveries.
Asshgwn in the foregoing examples, the ?ota 70 and pH 5.5, and recovering a froth containing
tion procedure can be‘ followed by a agnetic
a chromite concentrate.
concentration further to remove magnetic iron
4. In a process for the bene?ciation of chro
compounds from the concentrate s cured by
mium ores, the improvement which comprises
agitating and aerating a chromite ore pulpcom
tfzlrottaétion to yield a still higher grade; concen
a
.
75 minuted to a particle size between minus 20
‘2,412,217
mesh and minus 800-mesh in ‘the presence 01.’,
and aerating an aqueous pulp or a
per ton of ore, from 0.1 to 10 vpounds of a. soluble _
chromite ore comminuted to a particle size be
?uoride, from 0.5 to 5 pounds of a long-chain
fatty acid having from 8 to 18 carbon atoms, ,
and an amount of a strong mineral acid sufficient
tweenminus 48-‘mesh and minus 200-mesh in
the presence of, per ton of ore, from 0.6 to 7.0
pounds ‘of sodium ?uoride, from 1 to 4.5 pounds
to maintain the pulp acidity between pH 2.5 and
pH 4.5, and recovering a chromite concentrate
of oleic acid and from 1 to 11 pounds of sul
iuric acid, and recovering a chromite concen
as a ?oated product.
trate as a ?oated product.
'
5. In a process for the bene?ciation oi chro
,mium ores, the improvement which comprises 10
RICHARD HAVENS.
'
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