Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: FROTH FLOTA'rION PROCESS
E~ACKGROUND OF THE INVENTION
Froth flotation is a commonly employed process for
concentrating minerals from ores. In a flotation process,
the ore is crushed and wet ground to obtain a pulp. A froth-
5 ing agent, usually employed with a collecting agent, is addedto the ore to assist in separating valuable minerals from the
undesired or gangue portions of the ore in subsequent flota-
tion steps. The pulp is then aerated to produce a froth at
the surface thereof and the collector assists the frothing
10 agent in separating the mineral values from the ore by caus-
ing the mineral values to adhere to the bubbles formed during
this aeration step. The adherence of the mineral values is
selectively accomplished so that the portion of the ore not
containing mineral values does not adhere to the bubbles.
15 The mineral-bearing froth is collected and further processed
to obtain the desired minerals. That portion of the ore
which is not carried over with the froth, usually identified
as "flotation tailings", is usually not further processed
for extraction of mineral values therefrom. The froth flota-
20 tion process is applicable to ores containing metallic andnon-metallic mineral values.
In flotation processes, it is desirable to recover
as much mineral values as possible from the ore while effec-
ting the recovery in a selective manner, that is, without
25 carrying over undesirable portions of the ore in the froth.
I~hile a large number of compounds have foam or froth
producing properties, frothers widely used in commercial froth
' 3~
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flotation operations include polyalkylene glycol compositions
and alkyl ethers thereof (see, for example, U.S. Patent Nos.
3,595,390; 2,611,485 and 2,695,101). The frothers most wide-
ly used in froth flotation operations are compounds contain-
ing a non-polar, water-repellant group and a single, polar,
water-avid group such as hydroxyl (OH). Typical of this
class of frothers are mixed amyl alcohols, methylisobutyl
carbinol (~qIBC), hexyl and heptyl alcohols, cresols, terpinol,
etc. Other effective frothers used commercially are the
Cl-C4 alkyl ethers of polypropylene glycol, especially the
methyl ether and the polypropylene glycols of 140-2100 mol-
ecular weight and particularly those in the 400-1100 range.
More recently, sulfide-containing polyalkylene oxide (U.S.
Patent No. 4,122jO04) and mercaptan polyalkylene oxide (U.S.
Patent No. 4,130,477) have been found to be effective frothers
as well.
Although mineral recovery improvements from a pre-
ferred frother in the treatment of an ore can be as low as
only about 1 percent over other frothers, this small improve-
20 ment is of great importance economically since commercialoperations often handle as much as 50,000 tons of ore daily.
With the high throughput rates normally encountered in commer-
cial flotation processes, relatively small improvements in the
rate of mineral recovery result in the recovery of additional
tons of minerals daily. Obviously, any frother which promotes
improved mineral recovery, even though small, is very desir-
able and can be advantageous in commercial flotation opera-
tions, especially in view of increasing energy costs.
Thus, there exists a continuing need for frothing
30 agents which improve the selective recovery of mineral val-
ues from ores in the present flotation processes. Such
improvements act not only to enhance the state of metallurgy,
but can reduce the promoter consumption requirements of the
mining industry as a whole.
S~MARY OF THE INVENTION
The present invention provides for a process for
collecting mineral values from an ore wherein said process
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comprises mixing ground ore with water to form an aqueous ore pulp, adding tosaid aqueous ore pulp an effective amount of a frother, aerating said aqueous ore
pulp and thereafter recovering said mineral values, wherein the frother is of the
general structure:
] n
Y
wherein R is taken from the group consisting of a saturated aliphatic radical of1 to 12 carbon atoms, inclusive, a phenyl and an alkylaryl wherein the alkyl
group consists of a saturated aliphatic radical of 1 to 6 carbon atoms, inclus-
ive; n is an integer of 1 to 4, inclusive; X and Y are individually either hydro-
gen or a saturated aliphatic radical of 1 to 8 carbon atoms, inclusive; and Z istaken from the group consisting of -C-OR", -C - N, -~-NH2 and -O-R''I wherein R"
and R' " are aliphatic radicals having 1 to 8 carbon atoms, inclusive.
In accordance with the present invention there is provided a process
for collecting mineral values from an ore. The process of the present invention
is useful in the recovery of mineral values from all ores that employ a frother
in their processing, i.e. a frother in the froth flotation stage of their mineral
value recovery. These ores include, but are not limited to, the sulfide ores,
the oxide ores and also coal and talc.
The process entails initially mixing the ground ore with water to form
an aqueous ore pulp. The aqueous ore pulp is then conditioned with an effective
amount of the frother of the present invention. An effective amount is that
amount of frother sufficient to obtain the recovery level desired for
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the ore system being treated. Although this amount will vary
depending upon the ore being treated, the other additives within
the system and variables of a similar nature, it has generally been
found that from about 0.01 pounds of frother per ton of ore to
about 1.0 pounds of frother per ton of ore is effective, preferably,
0.02 to 0.5 pounds per ton. Other additives that are mixed with
the aqueous ore pulp at this stage in the process may include
promoters, dispersants, pH modifiers, depressants and the like.
After the aqueous ore pulp has been conditioned sufficiently long
enough, the pulp is aerated to produce the froth or foam and the
mineral values are collected out of the flotation system in this
froth or foam.
The frother employed in the instant invention is
conveniently prepared by the Michael addition of alpha,beta
unsaturated ethylenic compounds or other unsaturated nitriles
with mercaptans in the presence of a catalyst such as potassium
hydroxide, sodium hydroxide, trimethylbenzylammonium hydroxide
and the like. The reaction temperature is in the range of 10 to
175C., preferably 30-80C. The reaction pressure will depend
upon the temperature of the reaction, volume of the autoclave and
~uantity of reactants. The duration of reaction is from one to
four hours. For a more detailed description on the Michael
addition of alpha-beta-unsaturated ethylenic compounds with
alcohols see U.S. Patent Nos. 2,280,791 and 2,280,792, issued to
Bruson; with amines see Journal of the American Chemical Society,
Vol. 68, page 1217 (1946), and with mercaptan see U.S. Patent
No. 2,413,917, issued to Harmon. An alternative method of
preparation is the condensation of HCN, aldehydes/Ketones with
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1 1 62B62
mercaptans as is set forth in ~ournal of the American Chemical
Society, Vol, 82, page 696 (1960).
With respect to the Michael addition, examples of
suitable starting mercaptans include methyl, ethyl, propyl,
isobutyl, n-butyl, tert.butyl, pentyl, hexyl, octyl, nonyl,
dodecyl, decyl, cyclohexyl, benzyl, mercapto ethanol and the like.
Suitable starting olefinic compounds include acrylonitrile, methyl
methacrylate, methyl vinyl ether, ethyl vinyl ether, n-iso or
tert.butyl vinyl ether, 2-methyl 2-butene nitrile, 2-methyl
lo 3-butene nitrile, 2-pentene nitrile, 3-pentene nitrile and the
like.
Examples of products derived from the Michael addition
include, but are not limited to, 2-cyanoethyl, iso-butyl sulfide;
2-cyanoethyl, hexyl sulfide; 2-cyanoethyl, cyclohexyl sulfide;
methyl,3-(isobutylthio)-2-methyl propionate; methyl,3-(pentyl-
thio)-2-methyl propionate; 2-(butylthio)ethyl, ethyl ether;
2-(benzylthio)ethyl, butyl ether; and the like.
With respect to the condensation reaction, suitable
starting materials include, but are not limited to, formaldehyde,
acetaldehyde, propionaldehyde, acetone, methyl ethyl ketone, ethyl
ketone and the mercaptans set forth above. An example o~ a
compound formed from such a condensation reaction is, without
limitation, l-(cyanopropyl)ethyl sulfide.
The following specific examples illustrate certain
aspects of the present invention and, more particularly, point
out methods of evaluating the unique advantages of em-
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ploying the novel frothers in the froth flotation system.However, the examples are set forth for illustration only and
are not to be construed as limitations on the present inven-
tion except as set forth in the appended claims. All parts
and percentages are by weight unless otherwise specified.
EXPERIME~TAL PROCEDURE
A 500 part sample of copper-molybdenum ore is
crushed to -10 mesh and thereafter further ground in a rod
mill in the presence of 333 parts of water to the size indi-
cated. To this ground ore pulp there is then added suffici-
ent lime to adjust the pH to 9Ø Next, 0.015 pound per ton
of ore of a sodium cyanide conditioner is added to the ground
ore pulp and allowed to condition for 1 minute at about 1100
rpms. Finally, 0.034 pound of reconstituted cresylic acid
per ton of ore is added as a promoter in conjunction with the
frother. The mixture is allowed to condition for 1 minute.
The pulp is then aerated and the COnCentrate collected for 7
minutes. The concentrate and tailings are assayed according
to conventional techniques and the data tabulated.
PREPARATION OF CYANOETHYL ISOBUTYLSULFIDE
241 Parts of isobutyl mercaptan are charged into a
suitable reaction vessel equipped with a condenser, stirrer,
thermometer and graduated addition funnel. The initial
charge is agitated as 5 parts of benzyltrimethylammonium
25 hydroxide (40% in methanol) is added. Next, 143.4 parts of
acrylonitrile are added dropwise at approximately 0.85 ml/
minute via the graduated addition funnel. The reaction com-
mences during the addition of the acrylonitrile. The reac-
tion temperature is maintained at about 40C., + 5C., for
the duration of the addition, approximately 3 1/2 hours.
Since the reaction is exothermic, external cooling is re-
quired.
After addition is complete the reaction is contin-
ued until the exothermic reaction subsides and the tempera- -
ture drops to approximately 25C. Thereafter 5.9 parts of10~ sulfuric acid is charged to neutralize the base catalyst.
The final charge is heated to 100C. to distill off any un-
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reacted materials, again cooled to a~bient temperatures,
filtered and a nearly quantitative yield is collected for use.
COMPARATIVE EX~PLE _
The Experimental Procedure set forth above is fol-
lowed in every material detail on an ore sample ground to
2.4~ +100 mesh and 60.2% -200 mesh and employing 0.17 pound
per ton of ore of a polypropylene glycol frother with a mole-
cular weight of 425 of the general structure:
OH-CH2- ~CH-o~CH2-C-OtnH
CH3 CH3
Test results are set forth in Table I below.
COMPARATIVE EXAMPLE B
The Experimental Procedure set forth above is
followed in every material detail on an ore sample ground to
2.4% +100 mesh and 60.2% -200 mesh and employing 0.17 pound
per ton of ore of a methyl isobutyl carbinol frother of the
general structure:
~CH3
CH -CH-CH2-CH
OH CH3
Test results are set forth in Table I below.
COMPARATIVE EXAMPLE C
. _
The Experimental Procedure set forth above is fol-
lowed in every material detail on an ore sample ground to
2.4% +100 mesh and 60.2% -200 mesh and employing 0.17 pound
per tone of ore of a butoxy propanol frother of the general
structure:
3 2 2 2 2~
CH3
Test results are set forth in Table I below.
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_~MPLE 1
The Experimental Procedure set forth above is followed
in every material detail on an ore sample ground to 2.4% +100 mesh
and 60.2% -200 mesh and employing 0.17 pound per ton of ore of an
isobutyl cyanoethyl sulfide frother of the general structure:
N-- C-CH2CH2-S-CH2CH-'~CH3
CH3
Test results are set forth in Table I below.
EXAMPLE 2
The Experimental Procedure set forth above is followed
in every material detail on an ore sample ground to 2.4% +100 mesh
and 60.2% -200 mesh and employing 0.17 pound per ton of ore of a
2-isobutylthioethyl butyl ether frother of the general structure:
CH3
C4Hg O C 2C 2 2 ~ CH
Test results are set forth in Table I below.
EXAMPLE 3
The Experimental Procedure set forth above is followed
in every material detail on an ore sample ground to 2.4% +100 mesh
and 60.2% -200 mesh and employing 0.17 pound per ton of ore of a
methyl 3-isobutylthio-2-methylpropionate frother of the general
structure:
O CH
CH3o-c-fHcH2-s-cH2cH\
CEI3 3
Test results are set forth in Table I below.
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9 1 ~ 62662
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COMPARATIVE EXAMPLE D
The Experimental Procedure set forth above is followed
on an ore sample ground to 2.4% +100 mesh and 60.2% -200 mesh
and employing 0.17 pound per ton of ore of a methyl isobutyl
carbinol frother of the general structure:
/ CH3
CH3-CH-CH2-CH
OH
Test data and results are set forth in Table II below.
EXAMPLE 4
The Experimental Procedure set forth above is followed
on an ore sample ground to 2.4% +100 mesh and 60.2% -200 mesh and
employing 0.17 pound per ton of ore of an isobutyl cyanoethyl
sulfide frother of the general structure:
CH3
N_ C C 2C 2 2 ~ CH
Test data and results are set forth in Table II below.
-10-
1 1 62662
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1 1 B2662
COMPARATIVE EXAMPLE E
-
The Experimental Procedure set forth above is followed
on an ore sample ground to 10% +65 mesh and employing 0.06% pound
per ton of ore of a commercial alcohol frother. Test data and
results are set forth in Table III below.
EXAMPLE 5
The Experimental Procedure set forth above is followed
on an ore sample ground to 10% +65 mesh and employing 0.069 pound
per ton of ore of an isobutyl cyanoethyl sulfide frother of the
general structure:
CH3
N- C-CH2CH2-S-CH2CH
CH3
Test data and results are set forth in Table III below.
; -12-
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1 1 B2662
CO_PARAT IVE EXAMP~E F
The Experi~ental Procedure set forth above is followed
on an ore sample ground to 33% ~100 mesh and 45~ -200 mesh and
employing 0.06 pound per ton of ore of a methylisobutyl carbinol
frother of the general structure:
/ C~3
CH -CH-CH CH
OH C~3
Test data and results are set orth in Table IV below.
EXAMPLE 6
The Experimental Procedure set forth above is followed
on an ore sample ground to 33% +100 mesh and 45% -200 mesh and
employing 0.06 pound per ton of ore of an isobutyl cyanoethyl
sulfide frother of the general structure:
CH3
N~_ C 2 2 2
CH3
Test data and results are set forth in Table IV below.
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~ 1 62662
-- 15 --
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1 1 62~2
COMPARATIVE EXAMPLE G
The Experimental Procedure set forth above is followed
on an ore sample ground to 25~ +65 mesh and employing 0.036 pound
per ton of ore of a polypropylene glycol monomethyl frother. Test
data and results are set forth in Table V below.
EXAMPLE 7
The Experimental Procedure set forth above is followed
on an ore sample ground to 25~ +65 mesh and employing 0.036 pound
per ton of ore of a isobutyl cyanoethyl sulfide frother of the
general structure:
/ CH3
N- C-CH2CH2-S-CH2CH \
CH3
Test results are set forth in Table V below.
-16-
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1 ~ 62662
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