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Patented Oct. 29, 1946
2,410,021
UNITED STATES PATENT‘ orncr:
2,410,021
FLO'I‘ATION PROCESS
Fred D. De Vaney, Hibbing, Minn, assignor to
Erie Mining Company, Hibbing, Minn., a cor
poration of Mlnnesot
No Drawing. Application April 26, 1944,
Serial No. 532,867
10 Claims. (Cl. 209-466)
2
This invention relates to speci?c improvements
the ore pulp a relatively small amount of an
in the froth ?otative bene?ciation of silicious
iron ores, and is speci?cally concerned with a
mode of accelerating the rate of ?otative separa
tion of silicious gangue from such ores using
alkali metal sul?de (speci?cally, sodium sul?de),
higher molecular weight aliphatic amine com
pounds as cationic collectors.
the rate of ?otation of the silicious gangue parti
cles can be very materially increased, with no
decrease in the selectivity and with a small but
appreciable saving in the amount of amine col
lector required. As equivalent of sodium sul?de
there may be used potassium sul?de or calcium
It heretofore has been suggested that silicious
iron ores might be bene?ciated by froth-?oating
sul?de or barium sul?de or a polysul?de of sodi
the silicious gangue particles from the iron min 10 um, potassium, calcium or barium.
eral particles of a pulp of the ore by the use of
It has been found that the alkali ,metal or
a higher molecular weight aliphatic amine com
alkaline earth metal sul?de or polysul?de func
pound, having from 10 to 18 carbon atoms in the
tions most effectively when the pulp circuit is
aliphatic radical, as collector in conjunction with
a suitable frother. According to the suggested 15 maintained acid (i. e., less than pH 7) rather
than alkaline.
technique the pulp circuit was to be maintained
distinctly alkaline; preferably, also, the ?otation
was to be effected in the presence of a selectivity
improving agent such as acid-treated starch.
The influence of progressive additions of sodi
um sul?de, while maintaining a constant pH, may
be seen from the data of the following table:
TABLE 1
Effect of sodium sul?de on amine ?otation oi‘
Mesabi washing plant tailings
.ltirint.
um
so
sul?de,
lbs/ton
Product
.
pevllvctent
Assay},
percen
‘
on
Percen t
total
Iron
Silica
Silicious froth. _.
82. 41
8. 95
..... ..
41. 01
None_____ Concentrate.--.-
17. 59
60. 24
8.15
58. 99
Total. _ . -_
100.00
17. 97
..... ._
100. 00
Silicious froth. ..
82. 86
8 85
..... _.
41. 36
Concentrate... _.
17. i4
60. 61
o‘ 2 _____ __
'
-
Tm'ntg‘l’ganon
iron
Total“...
Silicious froth. .'.
100.00
82. 48
0_4_______ Concentrate".-.
17.52
61. 21
Total. . _ ._
100.00
i7. 84
8.02
17. 72 ..... -8. 63 _____ . _
7.17
..... -.
Silicious froth.-.
83. 06
m8 _____ __ Concentrate“..-
10. 34
61. 54
9. 61 ..... --
Total. _ _ __
100. 00
18. 10
_____ --
6. 60
58. 64
‘
min
100. 00
39. 92
60.08
3 min" 25 sec‘
100.00
44. 42
55. 58
3 min,
100. 00
Silicious froth. ..
84. 50
9. 98
_____ ..
47. 54
1.6_ _‘____ Concentrate“...
15. 50
59. 75
9 34
52. 46
Total. . . ..
100. 00
17. 65
_____ --
min” 25 sec.
mo. 00
2 mm" 35 sec_
'
Norm-In each test 500 gm. of washing plant tailing were treated without addi~
tional crushing and without desliming in a 500 gram Denver Sub A ?otation cell.
The pulp in each case was maintained at an acidity of pH 5.2. The ?otation reagents
used in each test were Identical and consisted of 0.4 lbJton of “AM Coco," i. e., a
canonically-acting collector consisting of the hydrochlorides. acetates or other water
soluble forms of mixed primary aliphatic amines corres nding in aliphatic chain
length to fatty acids of coconut oil, made by Armour & ompan and .104 lb./ton of
methyl amyl alcohol which were added in small increments.
hen sodium sul?de
was used this reagent was conditioned with the pulp for 5 minutes prior to ?otation.
It has now been found that if with the usual
higher molecular weight aliphatic amine collector
The in?uence of ‘varying the acidity of the pulp
circuit, while maintaining constant the amount
aforesaid and suitable frother there be added to
of sodium sul?de (and all other variables) at
i
2,410,021
3
' arbitrary levels, may be seen from the data of
increased rate‘ of ?otation means that a ?otation
the following table:
plant would require approzdmately only 60% as
'
TABLE 2
E?'ect of varying pH of pulp on amine ?otation of
Mesabi washing plant _tailinas
pH of
PM at
pulp
Percent Assay' percent Pf'ggf‘
‘1
wt.
.
Siliclcus froth__.
a o _____ __ Concentrate..._.
80. 90
19. 10
Total.__._
100.00
_
-
time
Silica
°n '
7. 99
58. 72
9. 79
B6. 64
63. 46
17.68
79. 00
8. 00
..... .-
35. 39
20. 34
5?. 16
12. 63
64. 61
Total. ._..
silicious froth- ._
100. 00
7a 73
a” _____ __ Concentrate"-..
21. 27
65. 69
14. 61
100. 00
17. 76
..... -_
Total- . _-_
,
3 mm.’ a) m.
100.00
silicious froth. ..
7.1 _____ __ Concentrate-_.--
I
Total ?otation
h‘!
Iron
18. 00 ..... ..
7. 61 ..... ._
v
5 mm.
100. 00
33. 28
06. 72
5 mm" 45 m.
100. 00
Test conditions same as given in Table 1, ex
many ?otation cells to handle the same tonnage '
cept 0.5# fused sodium sul?de used in all tests
per day provided the alkali metal sul?de, in acid
and alkalinity and acidity controlled by addition
circuit, expedient is employed.
of either sulphuric acid or sodium carbonate.
Repetition of the above example, substitut
25
By using in the pulp circuit both the sul?de
ing the equivalent amount of potassium sul?de
and the acid-treated starch it is possible to main
for the sodium sul?de, gives results almost iden
tain the high selectivity attributable to the use
tical with those above set out. Calcium sul?de
of the starch material while simultaneously
and barium sul?de have been substituted by me
achieving the high rate of feed made possible by 30 for the sodium or potassium sul?de and found to
use of the sul?de.
be helpful in accelerating the rate of ?otation
separation.
'
EXAMPLE
The accelerated ?otation rate achieved when
The starting material was a washing plant tail
' alkali metal or alkaline earth metal sul?de or
ing from the Danube mine, Minnesota, analyzing 35 polysul?de is used appears to be due to a selective
16.66% Fe, mostly as hematite. The silicious
?occulating effect of the sul?de or polysul?de on
gangue was mostly quartz. The material as ob-‘
the gangue particles. Whatever may be the cor
tained was essentially of a size through 48 mesh
rect explanation, it is an observable fact that,
and was not further subdivided.
with use of the sul?de or polysul?de, ?occulation
The starting material, without having been 40 of the gangue particles does take place, and this
subjected to a desliming treatment, and in the
?occulation of the ga'ngue is de?nitely a very de- form of an aqueous pulp of approximately 25%
sirable condition for rapid ?otation.
solids, was added to a mechanically agitated ?o
I have found that non-alkali inorganic sul?des
tation cell, and to it were added 0.5 lb./ton of
such as ammonium sul?de and hydrogen sul?de
acid-treated starch, 1/4 lb./ton of sulfuric acid
not only do not serve to accelerate the rate of
monohydrate, and 0.8 lb.-/ton _of sodiumlsul?de in
' separating but positively are harmful in the ?ota
the form of 60% fused ?ake. Afterthorough mix
ing _of these ingredients with the pulp and con
ditioning for 3 minutes, froth ?otation was in
duced by the addition of 0.25 lb./ton of 9AM
(.looo”v collector and 0.05 lb./ton of “B-23" frother,
tion.
A number of experiments with organic
I compounds of sulfur, e. g., petroleum sulfonates,
sulfonic acids and a number of xanthates, have
established that such compounds are not helpful
for accelerating the rate of ?otation.
both of which agents were added, in small in
It is to‘be noted, in this connection, that the
function of the alkali metal or alkaline earth
metal sul?de or polysul?de is not that of a sul
crements, during the agitation and aeration of -
the pulp. After 1 minute 45 seconds, a ?rst froth,
constituting a ?nished tailing, was removed. Ad
?dizing agent toward the mineral to be?oated,
ditional amounts of the collector (0.10 lb./ton) 55 ‘as obtains in the ?otation of base metal ores,-e. g.,
and the frother (0.025 lb./ton) were added, and
oxidized copper and lead ores. where a sul?de
after 1 minute and 30 seconds a second froth was
actually forms a base metal sul?de "sheath” or
removed. This second froth was a middling prod
surface layer on the mineral particle. In the
uct which, in thecontinuous ?otation ‘process,
present process, no chemical combination be
60
would be retreated along with fresh feed.
tween the vsilica and the sul?de or polysul?de of
The following results were obtained:
sodium, potassium, calcium or barium has been
- observed.
.
'
Pmd‘m
Per cent
wt.
Per cent
Fe
Per cent
SlOl
silicious froth (tailing)---
60. 24
2d lrotli (middling) ____ _ _
23. 62
13. 86
l6. 14
61. 66
7. 45
59. 72
100.00
16.66
7. 45
100.00
Concentrate __________ -_'_
5. 71 ________ -_
Per cent
total iron
________ _ _
20. 65
10. 63
It is to be noted that the time required for
the over-all ?otation (both roughing and clean
ing) was 3 minutes and 15 seconds, whereas in
the absence of the sodium sul?de the normal ?o
tation time is from 5 to 6 minutes. This ‘greatly
'
I claim:
a
'
.
1. In the process of bene?ciating silicious iron
ore by cationically froth-?oating the silicious
gangue particles from the iron mineral particles
of an aqueous pulp of such an ore by the use of
a ‘higher molecular weight aliphatic amine col
70 lector and a frother, the step of accelerating the
rate of ?otation of the silicious gangue particles
which consists in incorporating a relatively very
small amount of sodium .sul?de into‘ the pulp
prior to the froth ?otation step.
- .
2. In the process of bene?c'iating silicious iron
5
2,410,021
6
ore by cationically froth-?oating the silicious
gangue particles from the iron mineral particles
of an aqueous pulp of such an ore by the use of
a higher molecular weight aliphatic amine col
lector and a frother, the step of accelerating the
rate of ?otation of the silicious gangue particles‘
which consists in maintaining the pulp at a pH of
less than 7 but not less than about 5 and in
corporating into the acidic pulp, prior to the
froth ?otation step, a relatively very small
amount of sodium sulfide.
3. In the process of bene?ciating silicious iron
ore by froth floating the silicious gangue particles
from the iron mineral particles oi.’ an aqueous
pulp of such an ore using a higher molecular
weight aliphatic amine as collector, a suitable
frother, and acid-treated starch as selectivity
'1. In the process of bene?ciating silicious iron
ore by cationically froth-?oating the silicious
gangue particles from the iron mineral particles
of an aqueous pulp of such an ore by the use of
a higher molecular weight aliphatic amine col
lector and 01' a frother, in a slightly acidic cir
cuit, the step of selectively ?occulating the
silicious ~gangue particles which consists in in
corporating into the pulp, prior to the ?otation
operation, a relatively small amount of a com
pound of the group consisting of the alkali metal’
sul?des, the alkaline earth metal sul?des, the
alkali metal polysul?des and the alkaline earth
metal polysul?des.
8. The process of bene?ciating a silicious oxidic
iron ore, which comprises adding to an aqueous
pulp of the ore a mineral acid in an amount
improving agent,_steps of accelerating the rate of
su?lcient to give the pulp a pH of about 6.0, con
?otation of the silicious gangue particles which
ditioning the pulp with from about 0.4 lb. to
consists in maintaining the pulp containing the 20 about 1.6 lbs/ton of a compound of the group
aforesaid agents at a pH of less than 7 but not
consisting of alkali metal sul?des, alkaline earth
less than about 5 and incorporating into the
metal sul?des, alkali metal polysul?des and
acidic pulp, prior to the froth ?otation step, a
alkaline earth metal polysul?des, and subjecting
relatively very small amount of sodium sul?de.
the acidi?ed and conditioned pulp to froth ?ota
4. In the process of bene?ciating silicious iron 25 tion in the presence of a frother and of a higher
are by cationically froth-?oating the silicious
molecular weight aliphatic amine collector,
gangue particles from the iron mineral particles
thereby rapidly raising a froth product rich in
of an aqueous pulp of such an ore by the use of a
silicious gangue particles.
higher molecular weight aliphatic amine col
9. The process of bene?ciating a silicious oxidic
lector and a frother, the step of accelerating the 30 iron ore, which comprises adding to an aqueous
rate of ?otation of the silicious gangue particles
pulp of the ore a mineral acid in an amount su?l
which consists in incorporating a relatively very
cient to give the pulp a pH of about 6.0, condition
small amount of an alkali metal sul?de into the
ing the pulp with acid-treated starch and from
pulp prior to the froth ?otation step.
about 0.4 lb. to about 1.6 lbs/ton of a compound
5. In the process of bene?ciating silicious iron 35 of the group consisting of alkali metal sul?des,
ore by cationically froth-?oating the silicious
alkaline earth metal sul?des, alkali metal poly
gangue Particles from the iron mineral particles
‘sul?des and alkaline earth metal polysul?des,
of an aqueous pulp of such an ore by the use of a
and subjecting the acidi?ed and conditioned pulp
higher molecular weight aliphatic amine collector
to froth ?otation in the presence of a frother and
and a i'rother, the step of accelerating the rate 40 of a higher molecular weight aliphatic amine col
of ?otation of the silicious gangue particles which
lector, thereby rapidly raising a froth product
consists in incorporating a relatively very small
rich in silicious gangue particles while depressing
amount of an alkali metal polysul?de into, the’
?ne oxidic iron particles into the under?ow
pulp prior to the froth ?otation step. .
, product.
6'. In the process of bene?ciating silicious iron
‘10. The process of 'bene?ciating a silicious
ore by cationically: froth-?oating the silicious
oxidic iron ore, which comprises adding to an
gangue particles "from the iron mineral particles‘ -' aqueous pulp of the ore a mineral acid in an
of an aqueous pulp of such an ore by the'use of a
amount sufficient to give the pulp a pH of about
higher molecular weight aliphatic amine col-:'
lector and 'a-‘frother, the stepof'accelerat'ing the
rate of ?otation of thel’silicious gangue particles
which consists in incorporating a relatively very
small amount of a compound ‘of the group con
‘16.0, conditioning the pulp with from about 0.4 lb.
50 “to about '1.6 lbs/ton of sodium sul?de, and sub
jecting the acidi?ed and conditioned pulp to froth
; ?otation in the presence of a frother and of a pri
‘ mary alkylamine having from 10 to 18 carbon
slsting of the alkali metal sul?des, the alkaline
atoms in the alkyl radical as collector, thereby
earth metal sul?des, the alkali ‘metal polysul?des 55 rapidly raising a froth product rich in silicious
and the alkaline earth metal-polysul?des into the
gangue particles.
oulp prior to the froth ?otation.
FRED D. DE VANEY.
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