U.S. patent number 3,865,718 [Application Number 05/313,155] was granted by the patent office on 1975-02-11 for frothers for the flotation of sulfidic ores.
This patent grant is currently assigned to The Dow Chemical Company. Invention is credited to Guy H. Harris, Lowell B. Lindy, Elmer C. Tveter, deceased.
United States Patent |
3,865,718 |
Tveter, deceased , et
al. |
February 11, 1975 |
FROTHERS FOR THE FLOTATION OF SULFIDIC ORES
Abstract
A process involving the use of a new and improved class of
frothing agents in the froth flotation of ores such as the sulfide
ores of copper, molybdenum, lead, nickel and zinc, as well as for
separating coal fines by flotation. The class comprises the
non-hydroxylated ether derivatives of dialkylene glycols such as
ethylene glycol and propylene glycol. Especially good results are
obtained when these frothers are employed in the treatment of
complex copper-molybdenum ores.
Inventors: |
Tveter, deceased; Elmer C.
(late of Walnut Creek, CA), Harris; Guy H. (Concord, CA),
Lindy; Lowell B. (Midland, MI) |
Assignee: |
The Dow Chemical Company
(Midland, MI)
|
Family
ID: |
23214605 |
Appl.
No.: |
05/313,155 |
Filed: |
December 7, 1972 |
Current U.S.
Class: |
209/166 |
Current CPC
Class: |
B03D
1/0043 (20130101); B03D 1/008 (20130101); B03D
1/012 (20130101); B03D 2201/02 (20130101); B03D
2203/02 (20130101); B03D 2201/04 (20130101); B03D
2203/08 (20130101) |
Current International
Class: |
B03D
1/004 (20060101); B03D 1/008 (20060101); B03d
001/02 () |
Field of
Search: |
;209/166,167
;252/61 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
542,966 |
|
Jul 1957 |
|
CA |
|
1,001,652 |
|
Jan 1957 |
|
DT |
|
1,004,442 |
|
Sep 1959 |
|
DT |
|
Other References
Chem. Abst., 1966, Vol. 65, 18218d. .
Chem. Abst., 1969, Vol. 70, 98894n..
|
Primary Examiner: Halper; Robert
Attorney, Agent or Firm: Lockhead; J. R.
Claims
We claim:
1. The method which comprises subjecting an aqueous pulp of a
sulfidic ore of one or more of the metals lead, zinc, copper,
molybdenum, nickel, cobalt, antimony, silver, mercury, gold,
cadmium and arsenic to froth flotation in the presence of a
collector and one or more organic frothing agents corresponding to
the formula ##SPC3##
wherein each A is an alkylene group having 2 or 3 carbon atoms, and
R is methyl, ethyl, n-propyl, i-propyl, i-butyl or t-butyl.
2. The method of claim 1 wherein, in the formula, R is t-butyl.
3. The method of claim 1 wherein, in the formula, R is methyl.
4. The method of claim 1 wherein the frothing agent is diethylene
glycol methyl, t-butyl ether.
5. The method of claim 1 wherein the frothing agent is diethylene
glycol di-t-butyl ether.
6. The method of claim 1 wherein the frothing agent is diethylene
glycol ethyl, t-butyl ether.
Description
BACKGROUND OF THE INVENTION
Heretofore, a large number of different compounds have been
employed as frothing agents. Alcohols such as methyl isobutyl
carbinol and pine oil received early use in this area.
Non-hydroxylated compounds have also been employed: for example,
U.S. Pat. Nos. 2,591,289, 2,687,214 and 2,982,787 illustrate the
use of compounds containing ether linkages.
It is also known that reaction products of alcohols with one or
more moles of alkylene oxide can be employed as frothing agents.
For example, in U.S. Pat. No. 2,611,485, Tveter describes the use
of monoethers of propylene glycol and of polypropylene glycols as
frothers. In U.S. Pat. No. 2,950,818, Moeller teaches the use of
monoethers of ethylene glycol and polyethylene glycols as
frothers.
DESCRIPTION OF THE INVENTION
The invention comprises subjecting an aqueous pulp of an ore
containing copper, molybdenum, lead, nickel, zinc, and the like to
froth flotation in the presence of a collector and a particular
organic frothing agent. The invention further comprises removing
coal fines by the froth flotation of same utilizing the frothers
taught herein.
The organic frothing agents utilized herein correspond to the
formula ##SPC1##
Wherein each A is an alkylene group having 2 or 3 carbon atoms, and
R is methyl, ethyl, n-propyl, i-propyl, i-butyl or t-butyl.
Examples of frothing agents useful alone or in admixture include
diethylene glycol methyl, t-butyl ether; dipropylene glycol ethyl,
t-butyl ether; diethylene glycol n-propyl, t-butyl ether;
dipropylene glycol di-t-butyl ether; and dipropylene glycol
i-butyl, t-butyl ether.
Frothing agents of the invention may be employed as pure compounds
or, instead of using the purified compounds, reaction mixtures
obtained by the usual methods of making the compounds, or mixed
fractions thereof, may also be used. The frothers of the invention
can also be employed in conjunction with additives such as fuel oil
or other frothing agents.
Frothers employed in the invention are prepared by known methods.
One such method is a multi-step process which involves reacting 1
or 2 moles of ethylene or propylene oxide with an alcohol having 1
to 4 carbon atoms or a mixture of such alcohols. A specific example
of such a reaction is described in U.S. Pat. No. 2,611,485
incorporated herein by reference. The resulting hydroxy ether is
"capped" by reacting the hydroxyl group to form an ether, as, for
example, by reacting the hydroxy ether with isobutylene using
macroreticular ion exchange beads as a catalyst (see U.S. Pat. No.
3,037,052).
In using the frothing agents, the amount employed is from about
0.001 to about 1.00 pound per ton of ore, and preferably is from
about 0.01 to 0.20 pound per ton of ore. The ore is ground to a
particle size suitable for flotation. Flotation is carried out at a
pulp density of from about 15 to about 40 percent solids. Acidity
in the pulp is controlled to provide a pH range of from about 7 to
about 12.
The frothers are employed with any of the standard collectors such
as xanthates (e.g., ethyl xanthate), dithiophosphates,
phosphocresylic acids, or diphenyl thiourea. The frothers are
especially suitable for use with collectors such as those described
in U.S. Pat. Nos. 3,590,997, 3,590,998 and 3,590,999.
The frothing agents of the invention are applicable to sulfidic
ores, primarily ores of such metals as lead, zinc, copper,
molybdenum, nickel, cobalt, or antimony, which are often associated
with other elements such as silver, mercury, gold, cadmium or
arsenic. The frothers find particularly useful application in the
beneficiation of complex molybdenum-copper ores containing on the
order of about 0.2 to about 1.5 weight percent of copper and about
0.01 to about 0.1 weight percent of molybdenum. Such ores are found
in the southwestern United States (Arizona, Utah, Nevada), Wester
Canada (British Columbia) and in wester South America (Peru,
Chile). They may also find utility with copper/cobalt ores, such as
are formed in southern Africa. In addition, they are useful in the
froth flotation of coal fines.
The frothers disclosed herein are effective producers of a strong
froth possessing the physical properties required for supporting
mineral particles and permitting a relatively clean separation from
gangue. As compared with chemically similar standard frothers such
as hydroxylated mono ethers of alkylene glycols (e.g., mono and
poly propylene glycol mono ethers), the new agents are capable of
producing an equivalent froth with a materially smaller quantity of
frothing agent, hence are markedly superior in specific frothing
power. In the case of many ores (e.g., complex Mo-Cu sulfidic) they
show a greater selectivity, producing a richer concentrate with a
lower content of acid-insoluble gangue materials. The frothers are
not effective as mineral collectors but function solely as frothing
agents. The art has long recognized, however, that it is
disadvantageous for frothing agents to possess good collecting
properties, as better selectivity is found when the two functions
are separately performed by appropriate agents.
The following example illustrates the improved results obtainable
by use of the invention.
EXAMPLE 1
A series of tests was made with a copper-molybdenum ore assaying
0.68 percent copper and 0.034 percent molybdenum. The particle size
of the ore was minus 20 mesh. Five hundred gram samples of the ore
were ground in a ball mill with 300 ml. of water and with lime in
proportion of 1.5 pounds per ton of ore to prepare a pulp in which
47 percent of the solids passed a 325 mesh screen. The pulp was
conditioned in a flotation cell with a collector in the amount of
0.021 pound/ton of ore, and with the amount of frothing agent shown
in the following table, after which the concentrate was removed in
6 minutes of frothing. The collector was a xanthate-derived
compound corresponding generally to the formula ##SPC2##
Table I shows the analysis of the concentrate and percentage
recovery of copper and molybdenum. As a comparison, tests were
carried out using standard frothing agents. These agents were the
diacetate ester of ethylene glycol and also a mixture of
polypropylene glycol monomethyl ethers available commercially as
Dowfroth 250 (a product of The Dow Chemical Company).
TABLE I
__________________________________________________________________________
Concentrate Analysis Lbs. of (Wt. %) % Frother/Ton Cu Mo Recovery
Run Frother of Ore % % Cu Mo
__________________________________________________________________________
1 Diacetate ester 0.202 9.1 0.251 85.7 50.8 of ethylene glycol 2
Dowfroth 250 0.120 11.7 0.499 86.0 56.4 3 Diethylene glycol 0.090
8.1 0.335 88.4 65.5 methyl, t-butyl ether
__________________________________________________________________________
The amounts of frother used in the tests were those required to
produce approximately the same volume of froth. From the results
depicted in Table I, it can be seen in comparison with standard
frothers that use of an exemplary frother of the invention resulted
in increased copper and molybdenum recovery even though smaller
amounts of said agent were employed.
EXAMPLE 2
An additional series of tests was made with a copper-molybdenum ore
similar to that of Example 1 and assaying 0.77 percent copper and
0.030 percent molybdenum. Five hundred gram samples of this ore
were ground with 275 ml. of water, with lime in proportion to 0.4
pound per ton of ore, and with isopropyl ethyl thionocarbamate in
proportion of 0.064 pound per ton of ore to prepare a pulp in which
5 percent of the solids were retained on a 100 mesh screen and 50
percent passes a 200 mesh screen. The pulp was conditioned for 1
minute in a flotation cell with the amount of frother shown in
Table II, after which the concentrate was removed in 3 minutes of
frothing. In each case duplicate tests were conducted, the
arithmetic average values for the analysis of the concentrates and
the percentages of recovery of copper and molybdenum being
reported. As a comparison, methyl isobutyl carbinol (M.I.B.C.),
which is customarily used in this process, and Dowfroth 250 were
also tested as standards.
TABLE II
__________________________________________________________________________
Concentrate Analysis Lbs. of (Wt. %) % Frother/Ton Cu Mo Recovery
Run Frother of Ore % % Cu Mo
__________________________________________________________________________
4. MIBC .078 25.35 0.68 65.1 46.2 5. do. .109 26.00 0.62 67.7 42.1
6. do. .140 22.10 0.64 74.6 55.1 7. Dowfroth 250 .094 25.10 0.66
70.1 48.9 8. do. .125 22.00 0.84 79.1 77.0 9. Diethylene glycol
.084 20.60 0.71 83.4 71.6 methyl, t-butyl ether 10. do. .180 20.20
0.74 83.2 76.1
__________________________________________________________________________
EXAMPLE 3
In another series of tests, an ore containing 0.33 percent of
copper and 0.22 percent of molybdenum was subjected to a procedure
similar to the above. Twelve hundred fifty gram samples of the ore
were ground in a ball mill with water to give a slurry containing
60 percent solids and with lime added in proportion to 4.8 pounds
per ton of ore, stove oil equivalent to 0.040 pound per ton of ore
and allyl amyl xanthate equivalent to 0.012 pound per ton of ore,
to prepare a pulp in which 75 percent of the solids passed a 100
mesh screen. The pulp was conditioned in a flotation cell with the
amount of frothing agent shown in Table III, after which the
concentrate was removed in 2 minutes of frothing. At this point an
amount of potassium amyl xanthate equivalent to 0.005 pound per ton
of ore was added and concentrate was removed during an additional 3
minutes of frothing. Table III shows the analysis of the
concentrate and the percentage of recovery of the copper and
molybdenum.
TABLE III
__________________________________________________________________________
Concentrate Analysis Lbs. of (Wt. %) % Frother/Ton Cu Mo Recovery
Run Frother of Ore % % Cu Mo
__________________________________________________________________________
11. MIBC .089 5.58 0.421 90.25 86.21 12. Diethylene glycol .033
4.14 0.190 90.35 81.55 methyl, t-butyl ether
__________________________________________________________________________
EXAMPLE 4
The procedure of Example 2 was repeated on a new ore sample from
the same location. This sample analyzed 0.68 percent copper and
0.015 percent molybdenum. Again duplicate tests were made and Table
IV shows the arithmetic average results for concentrate analysis
and metal recoveries.
TABLE IV
__________________________________________________________________________
Concentrate Analysis Lbs. of (Wt. %) % Frother/Ton Cu Mo Recovery
Run Frother of Ore % % Cu Mo
__________________________________________________________________________
13. MIBC 0.156 23.6 .322 55.7 34.0 14. do. 0.125 24.6 .370 50.7
34.5 15. Dowfroth 250 0.150 21.8 .571 69.8 85.8 16. Diethylene
glycol 0.096 23.6 .422 55.9 47.1 methyl, t-butyl 0.120 22.7 .453
64.9 59.7 ether
__________________________________________________________________________
EXAMPLE 5
In this series of tests, an ore containing 0.55 percent copper and
0.047 percent molybdenum was ground in like manner with lime
equivalent to 6.0 pounds per ton, stove oil equivalent, to 0.039
pound per ton and isopropyl 2-methylthio ethyl thionocarbamate
equivalent to 0.034 pound per ton of ore to prepare a pulp with 10
percent of the solids being retained on a 100 mesh screen and 60
percent of the solids passing a 200 mesh screen. The pulp was
conditioned for 1 minute with the frother in amount shown in the
Table following, and concentrate was removed in 5 minutes of
frothing. In this series, a mixture of a frother containing chiefly
C.sub.7 and C.sub.8 primary alcohol (Aerofroth 71, a product of
American Cyanamid Co.) was blended with MIBC in a ratio of 3:1, was
tested as a comparison, this blend being the customary practice
used in treating this ore. In each case duplicate tests were made
with each frothing accent and the results tabulated are the
arithmetic averages.
TABLE V
__________________________________________________________________________
Concentrate Analysis Lbs. of (Wt. %) % Frother/Ton Cu Mo Recovery
Run Frother Of Ore % % Cu Mo
__________________________________________________________________________
17. 3:1 Aerofroth .072 10.3 0.96 81.3 89.2 71/MIBC 18. Diethylene
glycol .072 9.4 0.88 83.4 90.1 methyl, t-butyl ether
__________________________________________________________________________
EXAMPLE 6
Additional tests were made with a different ore sample but one from
the same source as Example 5. The procedure was as that of Example
5 with the exception that the isopropyl 2-methylthio ethy
thionocarbamate collector was replaced as indicated in Tables VI A
and VI B following. Again, duplicate tests were averaged.
A. using the equivalent of 0.0108 pound per ton of ethyl
thionocarbamate plus 0.0108 pound per ton of ally amyl xanthate as
the collector added in the grinding step.
TABLE VI A
__________________________________________________________________________
Concentrate Analysis Lbs. of (Wt. %) % Frother/Ton Cu Mo Recovery
Run Frother Of Ore % % Cu Mo
__________________________________________________________________________
19. 3:1 Aerofroth .240 13.42 1.34 37.95 74.50 71/MIBC 20.
Diethylene glycol .240 12.00 0.91 63.35 86.85 methyl, t-butyl ether
__________________________________________________________________________
B. using the equivalent of 0.0216 pound per ton of isopropyl
2-ethoxyethylthionocarbamate as the collector added in the grinding
step.
TABLE VI B
__________________________________________________________________________
Concentrate Analysis Lbs. of (Wt. %) % Frother/Ton Cu Mo Recovery
Run Frother of Ore % % Cu Mo
__________________________________________________________________________
21. 3:1 Aerofroth 71/ .240 12.04 1.10 46.20 71.30 MIBC 22.
Diethylene glycol .240 11.06 0.72 69.00 86.80 methyl, t-butyl ether
__________________________________________________________________________
EXAMPLE 7
In a manner similar to the procedure of the previous Examples, an
ore containing 3.83 percent total copper of which 0.74 percent was
as acid soluble copper, plus 0.227 percent of cobalt, 500 gram
samples of this ore were ground with 300 ml. of water, lime
equivalent to 0.2 lb. per ton of ore and isopropyl
2-ethoxyethylthionocarbamate equivalent to 0.06 lb./ton of ore to
prepare a pulp in which 22 percent of the solids were retained on a
200 mesh screen. This pulp was transferred to a flotation cell and
conditioned 1 minute with the amount of frother shown in the Table.
Concentrate was collected during 4 minutes of frothing. For
comparison tests were made with 1,1,3-triethoxybutane, known as
Powell Acelerator (National Chemical Products), the frother
customarily used in treating this ore. The results of duplicate
tests arithmetically averaged are presented in the following
Table.
TABLE VII
__________________________________________________________________________
Concentrate Analysis Lbs. of (Wt. %) % Frother/Ton Cu Mo Recovery
Run Frother of Ore % % Cu Mo
__________________________________________________________________________
23. 1,1,3-triethoxy- 0.184 40.9 1.37 70.0 39.7 butane 24.
Diethylene glycol 0.120 37.1 1.32 76.4 45.5 methyl, t-butyl ether
__________________________________________________________________________
EXAMPLE 8
Crude coal is generally treated in a preparation plant to reduce
the ash content resulting from continuous mining procedures. The
process involves washing, screening and gravity separation of the
coarse (+600 micron) fractions and froth flotation of the fine coal
fractions. The coal generally floats naturally, although
occasionally fuel oil or kerosene is added to render the coal more
hydrophobic. Frothing agents such as MIBC and pine oil are used to
produce the froth. In order to demonstrate the ability of the
frothers of the instant invention to froth and float coal fines,
diethylene glycol methyl, t-butyl ether and MIBC were added to
"oxidized" coal in roughly equivalent doses and flotation was
carried out until all the coal fractions appeared to have floated.
In the case of the former, this consumed 5-10 minutes, whereas with
MIBC 20-30 minutes were required, demonstrating the superior
ability of the frother of the instant invention in separating coal
fines.
EXAMPLE 9
In order to illustrate the frothing ability of a representative
group of the frothers disclosed herein, tests were made on a
copper-containing ore from Arizona, the ore assaying 1.06 percent
Cu. As in Example 2, 500 gram samples were ground with 300 ml. of
water, with lime in proportion to 0.2 pound per ton of ore, and
with isopropyl ethyl thionocarbamate in proportion of 0.032 pound
per ton to prepare a pulp in which 7 percent of the solids were
retained on a 65 mesh screen. The pulp was conditioned for 2
minutes in a flotation cell with the amount of frother shown in
Table VIII, after which the concentrate was removed in 5 minutes of
frothing. The calculations were the same as in Example 2.
TABLE VIII ______________________________________ Lbs. of Frother/
Ton of % Cu Run Frother Ore Recovered
______________________________________ 25. MIBC .181 59.35 26. .226
60.26 27. Diethylene glycol methyl, .207 66.19 28. t-butyl ether
.259 67.17 29. Dipropylene glycol methyl, .121 60.11 30. t-butyl
ether .181 63.45 31. Diethylene glycol .125 62.43 32. ethyl,
t-butyl ether .175 61.84 33. Dipropylene glycol .100 55.44 34.
di-t-butyl ether .200 64.15 35. Diethylene glycol .133 63.95 36.
di-t-butyl ether .182 65.54
______________________________________
* * * * *