Note: Descriptions are shown in the official language in which they were submitted.
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FLOTATION OF SULFIDE MINERAL
SPECIES WITH OILS
BACKGROUND OF THE INVENTION
This invention relates to the beneficiating or concentrating of ores. In
particular, this invention relates to collectors useful in ore beneficiating.
Flotation is a process for concentrating minerals from their ores. Flotation
processes are well known in the art and are probably the most widely used
method
for recovering and concentrating minerals from ores. In a flotation process,
the
ore is typically crushed and wet ground to obtain a pulp. Additives such as
flotation or collecting agents and frothing agents are added to the pulp to
assist in
subsequent flotation steps in separating valuable minerals from the undesired,
or
gangue, portion of the ore. The flotation or collecting agents can comprise
liquids
such as oils, other organic compounds, or aqueous solutions. Flotation is
accomplished by aerating the pulp to produce froth at the surface. Minerals,
which adhere to the bubbles or froth, are skimmed or otherwise removed and the
mineral-bearing froth is collected and further processed to obtain the desired
minerals.
The basic technique behind froth flotation is to use chemicals to increase
the hydrophobicity of the mineral to be beneficiated to form a concentrate.
Meanwhile, chemicals are added, as necessary, to decrease the hydrophobicity
of
unwanted (gangue) minerals, so that these minerals report to the slurry and
are
discarded as tail. The main alternative technique in froth flotation is
"reverse
flotation." This consists of floating the gangue minerals as a concentrate and
keeping the mineral of interest in the slurry.
Chemicals that promote hydrophobicity of a mineral are called that
mineral's "promoter" or "collector." Collectors based on fatty acids have long
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been used in collecting one or more of the oxide minerals such as fluorspar,
iron
ore, chromite, scheelite, CaCO3, Mg C03, apatite, or ilmenite.
Also, early work used alkali metal salts of fatty acids, or soaps derived
from natural oils by the process known as saponification. When an oil
containing
triglycerides is treated with a caustic solution under certain harsh
processing
conditions, the triglycerides disassociate into the alkali metal salts of the
component fatty acids. The dissociation of the triglycerides into neutralized
fatty
acids is the saponification process. These neutralized fatty acids are soaps
that act
as non-selective flotation collectors.
Compounds containing sulfur, such as xanthates, thionocarbamates,
dithiophosphates, and mercaptans, will selectively collect one or more sulfide
minerals such as chalcocite, chalcopyrite, galena, or sphalerite.
Unfortunately,
sulfur based collectors are often toxic, have repugnant odors or both. Amine
compounds are used to float KCl from NaCl and for silica flotation. Petroleum-
based oily compounds such as diesel fuels, decant oils, and light cycle oils,
are
often used to float molybdenite. Those oils are also used as an "extender oil"
that
reduces the dosage of other more expensive collectors in the amine flotation
of
KCI.
Previous work on sulfide minerals has indicated that molecules containing
sulfur are useful compounds for the froth flotation of sulfide minerals. These
collectors'are usually grouped into two categories: water-soluble and oily
(i.e.,
hydrophobic) collectors. Water-soluble collectors such as xanthates, sodium
salts
of dithiophosphates, and mercapto benzothiazole have good solubility in water
(at
least 50 gram per liter) and very little solubility in alkanes. Oily
collectors, such
as zinc salts of dithiophosphates, thionocarbamates, mercaptans, and ethyl
octylsulfide, have negligible solubility in water and generally good
solubility in
alkanes.
Currently used collectors for most sulfide minerals are sulfur-based
chemicals such as xanthates, thionocarbamates, dithiophosphates, or
mercaptans.
These chemicals have problems with toxicity and/or repugnant odors. In
addition,
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3
these collectors can be very expensive. Therefore, a need exists for new
collectors that
are effective but not toxic or odiferous.
BRIEF SUMMARY OF THE INVENTION
This invention is directed to a method of beneficiating a mineral sulfide-
containing
material or a metallic species of gold, silver, copper, palladium, platinum,
iridium, osmium,
rhodium, or ruthenium by froth flotation in the presence of a collector as
well as a collector
for beneficiation of sulfide minerals, precipitates, or metallic species. In
both aspects, the
collector includes at least one oil which is either an essential oil or a
natural or synthesized
oil comprising triglycerides containing fatty acids of only 20 carbons or
less, or an ester
made from a fatty acid and an alcohol.
In the method aspect of the invention, the method includes the steps of (1)
providing an aqueous slurry of the mineral sulfide-containing or metal-
containing material,
(2) adding a selective collector to the slurry, the collector comprising at
least one oil
selected from the group consisting of (a) a natural oil or synthesized oil
comprising
triglycerides containing fatty acids of only 20 carbons or less, or an ester
made from a fatty
acid and an alcohol; and (b) an essential oil; (3) selectively floating the
mineral sulfide; and
then (4) recovering the mineral.
In the collector aspect of the invention, a collector is provided for
beneficiation of
sulfide minerals or precipitates from ores, concentrates, residues, tailings,
slags, or wastes.
The collector includes at least one sulfur-containing sulfide mineral
flotation promoter; and
at least one oil selected from the group consisting of (1) a natural or
synthesized oil
comprising at least one triglyceride, or at least one ester made from a fatty
acid and an
alcohol; and (2) an essential oil.
This invention has an advantage that the specified triglyceride, specialty, or
essential oil will selectively float sulfide minerals by itself or mixed with
other collectors.
This and other advantages will be apparent from the detailed description of
the invention
that follows.
DETAILED DISCLOSURE OF THE INVENTION
The subject invention provides materials and methods useful in the recovery of
minerals. These materials and methods are specifically applicable to froth
flotation
procedures; whereby, minerals are removed and recovered from complex mixtures
of ores,
residues, concentrates, slags and wastes. The subject invention can be used in
remediation processes to remove unwanted materials or may be used in mining
processes
to recover valuable minerals. Specifically exemplified herein is the use of
certain
triglycerides, esters of fatty acids and long chain alcohols, and essential
oils of both
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terpene and aromatic chemistries. Any of these oils may be used alone, in
mixtures, or in
combination with other collectors.
In the method aspect of the invention, the method includes the steps of (1)
providing an aqueous slurry of the mineral sulfide-containing or metal-
containing material,
(2) adding a selective collector to the slurry, the collector comprising at
least one oil
selected from the group consisting of (a) a natural oil or synthesized oil
comprising
triglycerides containing fatty acids of only 20 carbons or less, or an ester
made from a fatty
acid and an alcohol; and (b) an essential oil; (3) selectively floating the
mineral sulfide; and,
then (4) recovering the mineral.
In the collector aspect of the invention, a collector is provided for
beneficiation of
sulfide minerals or precipitates from ores, concentrates, residues, tailings,
slags, orwastes.
The collector includes at least one sulfur-containing sulfide mineral
flotation promoter; and
at least one oil selected from the group consisting of (1) a natural or
synthesized oil
comprising at least one triglyceride, or at least one ester made from a fatty
acid and an
alcohol; or (2) an essential oil.
Preferably the mineral sulfide-containing material is selected from the group
consisting of chalcocite, chalcopyrite, bornite, galena, sphalerite,
pentlandite, molybdenite,
and other sulfide materials containing silver, gold, platinum, palladium,
iridium, rhodium,
and osmium, either in the crystal structure or in association as an
independent mineral
species, and combinations thereof.
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This material may be derived from ores, concentrates, precipitates, residues,
tailings, slag, or wastes.
Alternatively, the method may be used for
acting upon metallic species such as gold, silver, copper, palladium,
platinum,
5 iridium, osmium, rhodium, and ruthenium by froth flotation in the presence
of a
collector. The metallic species may be from material derived from any ore,
concentrate, residue, tailings, slag, or waste:
The oils used according to the subject invention can be readily obtained
and used by a person trained in the teaching of this patent. The natural oils
identified in this invention are obtained directly or indirectly from plants
or
animals.
In a specific embodiment, the process of the subject invention can comprise
the following steps:
a) pulverizing a mineral-containing material to appropriate fine-sized
particles;
b) mixing the pulverized particles with water to produce a slurry;
c) agitating the mixture and adjusting its pH as necessary to produce a
conditioned slurry;
d) adding a sufficient amount of a naturally occurring oil or a mixture
thereof to the slurry with conditioning to render the surfaces of the
particles containing the desired minerals hydrophobic;
e) agitating the resultant slurry under conditions and for a time
sufficient to obtain a sufficiently homogenous mixture;
f) adding a frothing agent to the homogenous mixture in an amount
sufficient to cause frothing of the homogenous mixture upon
injecting air or other gases;
g) injecting air or other gas into the mixture to form bubbles in the
resultant composition in an amount and under conditions sufficient
to cause the hydrophobic particles to become attached to the
bubbles and cause the resultant bubbles with attached particles to
rise and form froth; and
h) separating the froth fraction and recovering the desired mineral.
In a specific embodiment of the subject invention, the mixture produced in
Part (b) will have between about 1%o to 75% solids by weight. In Part (c) of
the
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process, the pH may be adjusted to anywhere in the 5 to about 13 pH range,
with
particularly good results in the 7 to 10 pH range. With regard to Part (d), a
natural
oil, such as cottonseed, may be used as the only collector or it may be used
with
other collector compounds. In a preferred embodiment, the concentration of the
natural oil used according to the subject invention can range from about I
gram
per ton of ore to about 1,000 grams per ton of ore. The temperature range of
the
use of these compounds goes from 5 to 75 degrees Centigrade with most normal
operations in the 15 to 40 degree Centigrade range. Preferably, the flotation
conditions should be kept mild enough to prevent significant disassociation of
the
triglycerides, or other components, contained in the natural oils into fatty
acids,
and to prevent the subsequent saponification into fatty acid soaps. The
selectivity
of the flotation when using oils according to this invention is evidenced by
the
selective recovery of the minerals, and substantiates this observation. A
skilled
artisan trained in the teachings of this patent can adjust the concentration
and
conditions to achieve optimization of the process for a particular mineral
once a
collector compound has been identified as useful for that mineral species.
Gold, silver and platinum metal group metals (platinum, palladium,
rhodium, and iridium) are often associated with sulfide minerals. These metals
may be also effectively collected by the oils described in this patent either
alone or
in combination with another collector.
The invention is specifically exemplified for the recovery of certain sulfide
minerals. A skilled artisan, having the benefit of the instant disclosure,
could
readily adapt the process for the recovery and/or removal of a broad range of
sulfide minerals, silver, gold or platinum group metals.
It was found, however, that there are unexpected benefits of using certain
organic compounds containing no sulfur, no nitrogen and no phosphorous for
selective froth flotation of certain sulfides. These molecules contain oxygen
in a
variety of functional groups such as triglycerides and esters. These groupings
occur in many natural oils, such as cottonseed, corn, palm, safflower, jojoba,
and
clove. Surprisingly many of these oils are non-toxic and are used in
foodstuffs
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throughout the world. The oils run in price from $0.40 per kilogram to over
$125 per
kilogram.
It was also unexpected that blends of these oils with each other and with
standard collectors frequently exhibit synergistic or enhanced effects, in
that a
mixture of a sulfur containing collector with a non-sulfur containing
collector may
perform better than either of the components alone, and mixtures of multiple
components may perform better than a two-component blend. This invention is
uniquely suited to such mineral species as chalcocite, chalcopyrite, bornite,
galena,
and sphalerite. However, sulfur species such as pyrite are not as readily
floated by
these non-sulfur-containing collectors.
Most natural plant and animal oils are triglycerides of mixtures of fatty
acids. A triglyceride is simply the reaction product of a carboxylic acid and
glycerol. The general formula for a triglyceride is shown in Figure 1.
Triglycerides are generally made from fatty acids with typically 10 to 24
carbon
atoms and from 0 to 3 double bonds in their chains. Some triglycerides are
made
from hydroxyl fatty acids that have an alcohol group somewhere in the chain.
An
example of this is castor oil. Another oil, oiticicia, has three double bonds
and a
ketone functionality in its composition.
0
0 R
0
O R'
O R"
Figure 1. General Formula for Triglyceride
Saturated or highly saturated oils, such as coconut oil, contain triglycerides
made from a zero or a low percentage of fatty acids having double bonds.
Linseed
oil contains a high percentage of linolenic acid oil, an 18 carbon fatty acid
with
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three double bonds (expressed as C18:3). The composition of some common
natural oils is shown in Table 1. The iodine value is a measure of the
unsaturation
of the oil. The saturated fat column is for the percentage of saturated fat
when the
exact chain length is unspecified. A given type of oil composition will vary
with
the variety of plant, the growing conditions and the treatment of the oil
after
pressing. For instance, there are both high and low erucic acid (C22:1)
species of
canola oil. Some canola oil is also hydrogenated (hydrogen reacted with the
double bonds) before being sold.
It was unexpectedly found, however, that oils containing triglycerides that
have fatty acids with 20 carbon atoms or less, perform much better than oils,
such
as canola oil, that contain triglycerides with fatty acids having 22 carbons
or more,
such as erucic acid (C22:1). Moreover, since oils containing triglycerides of
fatty
acids with twenty carbon atoms or less do not contain free fatty acids, they
do not
behave as either fatty acids or soaps of fatty acids. The selective nature of
these
oils in flotation was surprising because fatty acids and fatty acid salts
(i.e., soaps)
are very non-selective.
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Other sources of triglycerides are animal oils. Commercially available
animal oils have a limited range of unsaturation values. A highly unsaturated
lard
oil will have triglycerides containing 46% C18:1 (oleic acid), 15% C1B.2
(linoleic
acid), 1% C18:3 (linolenic acid), and 62% saturated fatty acids.
5 There are some unique natural oils. Sperm whale oil contains esters made
from
long chain fatty acids and long chain fatty alcohols instead of esters of the
fatty
acid and glycerol as in triglycerides. Both the fatty acid and long chain
alcohol
usually contain at least 1 double bond. Sperm whale oil is, of course, no
longer
available due to whaling restrictions. However, its replacements, jojoba oil
10 (vegetable) and orange roughy oil (fish), have the same basic chemistry as
sperm
whale oil. The only differences between them are in the carbon numbers (chain
length) of the various components of the oils.
Chemical manufacturers can synthesize a long chain ester from a fatty acid
and a long chain alcohol. One example of a "synthesized oil" or "synthetic
oil" is
2-butyloctyl oleic acid ester. This compound contains one unsaturated site in
the
fatty acid molecule. The carbon numbers of the largest fractions of these oils
are
shown in Table 2.
Table 2. Carbon Numbers of Major Components of Specialty
Oils
of Material of Specified Carbon Number
Oil 30 32 34 36 38 40 42 44
Sperm Whale 21 23 20 12
Jojoba 6 31 50 8
Orange Roughy 11 16 25 23 15 5
2-butyloctyl oleic 100 T
acid ester
Preferably, the natural oils used in this invention include triglycerides that
contain only fatty acids having a carbon number less than 20. Also, it is
preferred
that the triglycerides include an alcohol, an ether, an aldehyde, or a ketone
functional group, or an aromatic group. A preferred group of natural oils
includes
cottonseed, corn, linseed, rice bran, safflower, soybean, avocado, jojoba,
menhaden, lard, castor, cod liver, tung, oiticicia, apricot, sunflower,
pistachio,
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herring, and coconut oils. A more preferred group of natural oils includes
cottonseed, corn, linseed, rice bran, safflower, soybean, avocado, jojoba,
menhaden, lard, castor, cod liver, tung, and oiticicia. A still more preferred
group
of natural oils includes cottonseed, corn, linseed, rice bran, safflower,
soybean,
avocado, jojoba, menhaden, lard, and castor oils. An even more preferred group
of natural oils includes cottonseed, corn, linseed, rice bran, safflower, and
soybean. The most preferred natural oil is cottonseed oil.
Another class of naturally occurring oils is called "essential oils" or
"volatile oils." These are fragrant oils derived from various plant species.
Since
ancient Egyptian times, they have been used for their fragrance and reputed
medicinal properties. The chemistry of most of these compounds is based on
either terpene chemistry or aromatic chemistry.
Terpenes are defined as compounds that can be assembled from two or more
molecules of isoprene, (C5H8) and the alcohol, aldehyde, and ketone
derivatives of such compounds. A terpene compound can be defined as a
monoterpene, sesquiterpene, or diterpene compound based on whether it contains
2, 3, or 4 isoprene units, respectively. Within each of these classifications
the
compounds can be further defined as being acyclic, monocyclic, bicyclic or
tricyclic depending on whether the terpene contains, respectively, 0, 1, 2, or
3 ring
structures (only diterpenes are tricyclic). Tricyclic diterpenes are generally
solids.
Aromatic chemistry for essential oils refers to the chemistry of derivatives
of
benzene. The two most common aromatic components of essential oils are
cinnamaldehyde and eugenol. These are olbtained from cinnamon and clove oil.
Their structures are shown in Figure 2.
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O
O
Cinnamaldehyde Eugenol
Figure 2. Structure of Eugenol and Cinnamaldehyde
Most essential oils have one single major terpene or aromatic component or
are a mixture of closely related terpenes or aromatics. Table 3 shows the
composition of some representative essential oils. Note that any particular
oil's
composition can vary with variety, weather, etc.
Table 3. Major Constituent of Representative Essential Oils
Major Component
Oil Plant Source Name % Chemical Family
Citronella Cymbopogon Citronellal: 33 Aldehyde and
winterianus Citronellol: 16 Alcohols of acyclic
Geraniol: 24 monoterpene
Limonene Citrus (Orange) Limonene 95 Monocyclic monoterpene
Eucalyptus Eucalyptus globus Cinole 90 Bicyclic monoterpene
ether
Sandalwood Sandalwood Mixture 80 Sesquiterpenes
Clove Clove Eugenol 85 Aromatic
Preferably, the essential oils used in the methods of this invention include
either a terpene compound or an aromatic compound. More preferably, the
essential oil includes a terpene derivative having a functional group selected
from
an alcohol, and ether, an aldehyde and a ketone. Specific preferred essential
oils
include limonene, citronella, eugenol, eucalyptus globus, camphor, and clove
oil.
A more preferred group of essential oils includes limonene 4nd citronella.
As work with the triglycerides, esters and alcohols has indicated, other
oxygen-containing compounds such as aldehydes, ketones, and ethers of
sufficient
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carbon number to be water-insoluble function as collectors for sulfide
minerals.
These compounds may or may not have carbon-carbon double bond(s).
The literature has shown that emulsified collectors can give better results
than unemulsified collectors. Emulsification should also allow the combining
of
inexpensive water-soluble xanthates and sodium sulfide into the oils. Other
water-
soluble collectors that may be amenable to emulsification into oil include
sodium
dithiophosphates and mercaptobenzothiazole.
The invention also includes the use of the plant and animal oil collectors
blended with known commercial collectors. Commercial collectors are also known
as "flotation promotors" and are identified herein as "sulfur-containing
flotation
promotors." These common commercial promotors are usually separated into two
classes of chemicals based on their water solubility. Water soluble sulfur
containing collectors, or promotors, used in the froth flotation of sulfide
minerals
include such well-known collectors as xanthates and dithiophosphates. These
are
usually used as sodium or potassium salts of the respective organic acids. An
example of a water-soluble collector would be sodium isopropyl xanthate. The
other class of sulfur containing collectors would be water insoluble
collectors.
These collectors are generally referred to as oily collectors, because they
are
liquids that are insoluble in water. These collectors include
thionocarbamates,
mercaptans, organic sulfides, and the zinc salts of dithiophosphates. Even
though
these compounds are chemical reaction products, they are called oils.
Another grouping of collectors commonly used in froth flotation of
substances such as coal, sulfur, and molybdenite are petroleum-based products
that
are truly oils. These oils generally consist of kerosene, vapor, diesel, fuel,
turbine,
light cycle, and carbon black oil. These petroleum oils are generally called
"extender oils" and generally exhibit poor collecting ability and very poor
selectivity when used by themselves. To distinguish these "petroleum-based
collectors" from other described collectors, the term "oily collector" used in
this
text means a synthesized organic chemical compound containing sulfur such as
the
group of "sulfur-containing flotation promotors" described above.
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This invention also includes the use of any of these aforementioned natural,
synthetic or essential oils in combination. The essential oils are found to be
very
potent collectors. As such they are ideally suited for use in small amounts in
combination with other oils or with other sulfide-containing flotation
promotors.
Good results have been obtained when using the essential oils in amounts of
less
than 10% by weight blended with other collectors. Preferably, less than 2% by
weight is used.
Also, any of the natural oils including the higher carbon fatty acid-
containing triglycerides, and in particular, the preferred natural oils alone
or in
combination with other preferred oils, may be used blended with any number of
sulfur-containing flotation promotors. In such blends, the natural oils make
up
preferably between 20% and 80% by weight of the blend, and the flotation
promotors make up preferably between the remaining 80% and 20% by weight of
the blend. Optionally, a frother may be added to that blend, preferably in an
amount between about 10% and 40% by weight of the composition. Frothers are
commercially available compositions that are used to develop a froth or foam
on
top of a slurry that has been aerated. A particular suitable frother is one
such as
that sold by NALCO under the designation 9743. Methyl isobutyl carbonol
(MIBC), also known as methyl amyl alcohol, is one of the most widely used
frothers in the mining industry.
The collectors and blends of collectors in accordance with the methods of
this invention can be used in standard froth flotation processes known by
those
skilled in the art and modified by the teachings of this patent as illustrated
in the
following examples.
EXAMPLES
The following are examples that illustrate procedures for practicing the
invention. These examples should not be construed as limiting the invention,
but
are provided to further illustrate the teachings of the invention. All
percentages
are by weight and all collector mixture proportions are by volume unless
otherwise
noted.
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Example I.
This example illustrates the effectiveness of cottonseed oil as a collector
for
molybdenite and chalcopyrite. The ore had a head grade of 0.259% Cu and
0.0064% Mo. The ore charge of 1.0 kilogram was ground at 60% solids to 60%
5 passing (P60) a 150 micron (100 mesh) screen. The ground ore slurry was
adjusted to a pH of 10.5 with lime. The ore was ground with 10 gram/ton (0.020
pound/ton) of secondary collector. A Denver laboratory flotation machine was
used. The ore slurry charge was diluted with water to 29 percent solids, and 6
grams per ton of the main collector, sodium ethyl xanthate, and 25 gram/ton
(0.05
10 pound/ton) of the OrePrep F-533 frother were added. The flotation was
carried
out for a total of six minutes with a two minute break for conditioning at the
halfway point. During the conditioning break, 4 gram/ton dosage of the sodium
ethyl xanthate was added.
The cottonseed oil was used by itself in place of the standard decant oil-
15 light cycle oil-mercaptan (tertiary dodecyl mercaptan) secondary collector.
Also,
a 33% each mixture of cottonseed oil, zinc di (1,3 dimethylbutyl)
dithiophosphate,
and the tertiary dodecyl mercaptan was tested. For comparison a 33% each
mixture of decant oil, the zinc dithiophosphate and the mercaptan was tested.
The
dosage of the main and secondary collector was 10 grams collector per ton of
ore
(g/t) for all tests. As shown in Table 4, cottonseed oil by itself improved
the
recovery of both molybdenum recovery and copper grade over the standard
collector. The cottonseed mixture had a similar copper recovery as the decant
oil
mixture while improving copper grade.
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16
Table 4. Chalcopyrite Ore containing MoS2 Flotation
Main Secondary Cu Cu Mo
Collector Collector Recovery Grade Recovery
Xanthate Cottonseed Oil 94.5% 3.68 82.2%
Xanthate Standard 93.9% 2.96 79.1%
Xanthate Decant Oil Mixture 97.0% 2.85 87.3%
Xanthate Cottonseed Mixture 96.2% 4.25 83.7%
Example H.
This example shows that cottonseed oil can be used to collect some galena
(PbS). It can be used either alone in place of the main collector, sodium
isopropyl
xanthate, or in a mixture with a mercaptan (tertiary dodecyl mercaptan)
collector
in place of the main collector.
The ore was ground to a P80 of around 240 microns. The ore charge was
2.0 kilograms and had a head assay of 70 gram/ton Ag, 0.70% Pb, and 1.32% Zn.
Fifty gram/ton of zinc sulfate and fifteen gram/ton of dextrin were added to
the
grind. The flotation was conducted in a Denver laboratory flotation machine
with
a 5-liter cell. The float was conducted at the natural pH of the ore, 7.5 to
8.
Before the first float, the slurry was conditioned with 30 gram/ton of the
collector
and 80 gram/ton of the frother for two minutes. The ore was floated for three
minutes, then conditioned with 10 gram/ton collector and 16 gram/ton of
frother.
The results are shown in Table 5, and demonstrate the enhanced effects for a
blend
of the natural oil and the mercaptan flotation promotor in comparison to the
use of
each alone.
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Table 5. Lead-Zinc-Silver Sulfide Ore Flotation for Lead
Grade Recovery into Pb Concentrate
Collector Pb As Weight Ag Pb Zn Fe
Xanthate 2.18 1.23 23.6% 74.9% 79.5% 18.0% 82.9%
Cottonseed Oil 6.38 0.49 5.1% 51.4% 50.6% 17.2% 15.7%
Mercaptan 7.08 0.76 5.7% 42.9% 49.1% 19.3% 14.7%
50% Mercaptan + 3.21 0.78 13.8% 53.9% 64.5% 21.1% 38.6%
50% Cottonseed
The ore was then conditioned for two minutes with 125 gram per ton of
copper sulfate. A further 10 gram/ton of collector and 32 gram/ton of frother
were
added and conditioned in for two minutes. The first zinc float was conducted
for
three minutes. Finally, another 50 gram/ton of frother was added. The results
of
these zinc floats are shown in Table 6.
Table 6. Lead-Zinc-Silver Sulfide Ore Flotation for Zinc
Grade Recovery into Zn Concentrate
Collector Zn Weight Ag Pb Zn Fe
Xanthate 8.63 9.5% 16.5% 7.1% 42.1% 6.3%
Cottonseed Oil 9.13 6.6% 13.9% 20.4% 48.1% 10.1%
Mercaptan 12.20 5.6% 16.7% 19.8% 46.4% 6.2%
50% Mercaptan + 11.54 5.0% 9.1%1 7.1%1 45.6% 3.8%
50% Cottonseed
Example III.
Apricot, sunflower, pistachio, cottonseed, and jojoba oils were tested on
chalcopyrite ore containing molybdenum sulfide. The head assays of the ore
were
0.704% Cu and 0.0119% Mo. The ore charge of 2.0 kilograms was ground at 65%
solids to 90% passing a 212 micron (65 mesh) screen. The ore charge was
diluted
with water to 27% solids and placed in a Denver laboratory flotation cell. The
ore
was conditioned for two minutes by agitation at 2000 rpm. The ore was floated
for one minute by allowing air to be drawn in by the impeller. Subsequently,
the
ore was conditioned for two minutes, floated for two minutes, conditioned for
two
minutes, and finally floated for three minutes. The standard collector is a
mixture
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of 33% of the allyl ester of isopropyl xanthate, 33% of 2-ethylhexanol, and
33% of
sodium diisobutyl di-thiophosphate collector.
The standard reagent addition is as follows. Enough lime is added to the
ball mill to adjust to a pH of 10.4. At the same time, 7.7 gram/ton (0.0154
pound/ton) of the standard collector or oil being tested, 7.5 gram/ton (0.0
150
pound/ton) of diesel fuel are added. During the first conditioning step, 20
g/t
(0.040 lb/ton) of frother is added. During the second conditioning step, 8 g/t
(0.016 pound/ton) of sodium isopropyl xanthate (SIPX), 2.5 g/t (0.005 lb/t) of
frother, and 5 g/t (0.010 lb/ton) of the standard reagent or oil are added.
During
the third and final conditioning step, 4g/t (0.008 lb/ton) of SIPX, (0.005
lb/t) of
frother, and 5 g/t (0.010 lb/ton) of the standard reagent or oil are added.
The results for the final combined concentrates are presented in Table 7,
sorted by copper recovery. Every oil listed above the sunflower oil gave
essentially the same copper and molybdenum recovery as the standard reagent.
Table 7. Chalcopyrite Ore containing MoS2 Flotation
Cu Recovery Recovery
Tested Oil Grade Cu Mo
Standard 5.04 92.4% 84.6%
Cottonseed 3.62 91.9% 84.4%
Pistachio 2.92 91.9% 88.3%
Sunflower 2.97 91.8% 84.7%
Apricot 2.70 91.7% 79.6%
Jojoba 2.69 91.5% 86.5%
Example IV.
There are two primary types of cotton in the United States, Pima long
staple cotton and short staple cotton. The oils derived from both were tested
on a
copper-molybdenum ore with a head grade of 0.663% Cu and 0.0134% Mo. The
ore was floated as in Example III. The results of the test are shown in Table
8.
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Table 8. Comparison of Cottonseed Oils
Grade Recovery
Cottonseed Oil Source Cu Cu Mo
Pima Long Staple 5.36 94.8% 84.7%
Short Staple 5.23 90.9% 83.9%
Standard Collector 5.76 90.6% 82.1%
Example V.
This example shows the selectivity of cottonseed against calcite. Pure
calcite crystals were crushed and screened for the fraction passing a 355
micron
(42 mesh) screen. A sample size of 812 grams was obtained. The sample was
slurried in a 2.5 liter cell of a Denver laboratory flotation machine. The ore
was
conditioned for two minutes with 123 gram/ton cottonseed oil and 26.2 gram/ton
frother. The slurry was floated for two minutes and then conditioned again for
two minutes with 61.5 gram/ton cottonseed oil and 10.5 gram/ton frother. The
slurry was floated again for two minutes. During both flotations, a slime-
stabilized froth was obtained. The results of the test are shown in Table 9.
Table 9. Recovery of Calcite from Pure Calcite Sample Float
Concentrate Recovery
1 10.70%
2 1.88%
Combined 12.58%
Example VI.
This example shows cottonseed's selectivity against silica. Pure quartz
crystals were crushed and screened for the fraction passing a 150 micron (100
mesh) screen. A sample size of 1000 grams was obtained. The sample was
slurried in a 2.5 liter cell of a Denver laboratory flotation machine. The ore
was
conditioned for two minutes with 123 gram/ton cottonseed oil and 26.2 gram/ton
frother. The slurry was floated for two minutes and then conditioned again for
two minutes with 61.5 gram/ton cottonseed oil and 10.5 gram/ton frother. The
slurry was floated again for two minutes. During both flotations, a small
amount
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of slime-stabilized froth was obtained. The total recovery was less than 2% of
the
total silica.
Example VII.
A number of triglyceride, specialty, and essential oil collectors were tested
5 on chalcopyrite ore containing molybdenite. The head assays of the ore were
0.579% Cu and 0.010% Mo. The ore charge of 1.0 kilograms was ground at 65%
solids to 90% passing a 212 micron (65 mesh) screen.
The standard flotation procedure was as follows. Enough lime (0.9 grams)
was added to the grind for the flotation slurry to have a pH of 10.4. The
following
10 reagents were added to the grind, 5.5 gram/ton of the standard
thiophosphate
copper collector, 7.7 gram/ton of diesel fuel, molybdenum collector, and 10
gram/ton of Nalco 9743 frother. A Denver laboratory flotation cell was used.
The
ore charge was diluted with water to 27% solids. The ore was floated for two
minutes. The slurry was then conditioned for one minute with 6.5 gram/ton of
15 frother and 8 gram/ton of sodium isopropyl xanthate. The slurry was floated
for
two more minutes, then conditioned for one more minute with half of the dosage
of the previous conditioning step, and floated for a final three minutes. All
concentrates were collected into one pan for a single concentrate for the
whole
flotation.
20 The oils were tested by using them as the only collector. Only lime, 10
grams/ton of frother and 24 gram/ton of the oil being tested were added to the
grind. No xanthate or other collector was added to the conditioning step, only
the
listed frother dosage.
The results for the triglyceride tests are presented in Table 10. As tested,
no triglyceride was as good a collector for copper as the standard collector
system.
Due to the low molybdenum grade of the head ore, molybdenum recoveries often
have a large standard deviation in repeated tests on the same ore. Generally,
compounds that show a 5% better recovery than another compound in single tests
will have an average higher molybdenum recovery on multiple tests.
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Table 10. Results of Triglycerides Flotation
Number of Double Bonds, % Assay Con Recovery
Collector 0 1 2 3 5 Cu I Mo Cu Mo
Standard 4.94 0.071 88.3% 79.2%
Cottonseed 27 30 43 0 3.82 0.063 87.3% 84.7%
Lard Oil 31 48 12 1 5.61 0.094 85.4% 80.9%
Corn 13 29 57 1 5.64 0.084 85.3% 81.6%
PBO Lard 38 46 15 1 5.01 0.082 85.2% 83.4%
Linseed 9 19 15 57 4.91 0.080 85.1% 80.2%
Tung 85 5.71 0.088 85.1% 78.2%
Menhaden 18 18 37 13 14 8.52 0.144 84.5% 80.7%
Safflower 21 79 3.75 0.071 84.2% 83.9%
Herring 14 49 23 7.88 0.122 84.0% 78.9%
Avocado 70 15 1 6.38 0.111 84.0% 85.0%
Oiticicia 75 4.63 0.074 83.8% 78.2%
Soybean 16 24 54 7 5.14 0.094 83.7% 80.2%
Peanut 15 45 40 0 8.33 0.142 82.8% 81.3%
Casto 12 88 7.20 0.122 82.2% 77.95/o
Canola 8 59 22 11 8.43'0. 130 82.0% 80.6%
Rice Bran 64 2 32 2 8.0210.142,' 81.5% 78.7%0
Coconut 94 4 21 1 7.3810.133174.1%1 75.0%0
Notes: Has a ketone functionality; has a alcohol functionality
The results of the testing of specialty and essential oils are shown in
Table 11. The bicyclic compounds equaled or surpassed the standard for copper
and molybdenum recovery.
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Table 11. Results of Specialty and Essential Oil Testing
Grade Recovery
Oil Chemical Family Cu 1 Mo Cu Mo
Eucalyptus globus Bicyclic Ether 5.25 0.088 88.8% 87.8%
Standard Thiophosphate -4.94 0.071 88.3% 79.2%
Camphor Bicyclic Ketone 5.32 0.082 87.9% 85.7%
2-butyloctyl oleic Mono-unsaturated 5.62 0.092 87.3% 86.0%
acid ester Ester
Jojoba Di-unsat. Ester 5.11 0.088 85.7% 84.8%
Limonene Cyclic 4.87 0.082 84.7% 81.2%
monoterpene
Example VIII.
A number of triglyceride, specialty, and essential oil collectors were tested
on a molybdenum sulfide ore. The head assay of the ore was 0.0638% Mo. The
ore charge of 1.0 kilogram was ground at 65% solids to 90% passing a 425
micron
(35 mesh) screen.
The flotation procedure is as follows. The 100 gram/ton of oil was added
to the grind. A Denver laboratory flotation cell was used. The ore charge was
diluted with water to 27% solids. To the two minute conditioning step, 40 g/t
frother was added. The ore was floated for 1 minute. The slurry was then
conditioned for one minute, floated for two minutes, conditioned for one
minute,
and finally floated for six minutes. Each concentrate was collected separately
and
assayed separately. One test was conducted with frother alone to test the free
flotability of the ore. The standard collector used at the mine was diesel
fuel.
The results of the flotation of molybdenum sulfide for the triglycerides are
shown in Table 12. The percentage of fatty acids in the triglycerides with the
shown number of double bonds is listed. All of these oils did better than the
free-
flotability test.
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Table 12. Results of Triglycerides on Molybdenum Recovery
Number of Double Bonds, % 1 s Concentrate Overall
Collector 0 1 2 3 5 Grade Recovery Grade Recovery
Oiticicia 75 2.19 68.9% 0.892 72.5%
Peanut 15 45 40. 0 0 1.15 57.9% 0.602 71.9%
Coconut 94 4 2 9.42 60.1% 1.355 67.5%
Menhaden 18 18 37 13 14 4.14 59.0% 0.938 66.8%
Pfau 1JJ 31 48 12 1 3.11 54.9% 0.736 64.9%
Rice Bran 64 2 32 2 2.21 48.7% 0.763 61.4%
Cottonseed 27 30 43 0 4.44 51.1% 1.084 60.1%
Tung 85 3.57 54.8% 0.989 59.1%
Sunflower 12 24 64 3.21 48.8% 0.736 58.1%
None 0 0 0 0 0 3.38 53.9% 0.870 57.8%
Corn Oil 31 48 12 1 4.15 54.2% 1.013 57.7%
Linseed 9 19 15 57 2.61 48.4% 0.570 56.2%
Diesel 0 0 0 0 0 1.38 53.3% 0.565 56.1%
Notes: Has a ketone functionality
The results of specialty and essential oils are shown in Table 13. All of
these oils did better than the free-flotability test.
Table 13. Results of Testing Specialty and Essential Oils on Molybdenite
First Concentrate Overall
Collector Type Grade Recovery Grade Recovery
2-butyloctyl oleic Mono-unsaturated 0.73 71.6% 0.589 80.2%
acid ester' Ester
Jojoba Di-unsat. Ester 0.96 68.5% 0.507 78.1%
Clove Oil Aromatic 2.08 73.5% 0.817 77.9%
limonene oil Cyclic monoterpene 2.24 75.0% 0.902 76.7%
Citronella Acylic 2.00 69.8% 0.598 74.6%
monoterpenes
Eucalyptus, globus Bicyclic Ether 2.77 67.0% 0.759 71.6%
Camphor Bicyclic Ketone 4.41 61.0% 1.056 64.9%
None 3.38 53.9% 0.870 57.8%
Diesel 1.38 53.3% 0.565 56.1%
Note: Oil synthesized from natural products and used as a sperm whale oil
replacement
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Example IX.
In this example the synergistic effect of various oils and a sodium isopropyl
xanthate is shown. A chalcocite ore with a head assay of 0.602% Cu and 0.0 16%
Mo was used. The ore charge of 1.0 kilogram was ground at 65% solids to 90%
passing a 212 micron (65 mesh) screen.
The standard flotation procedure is as follows. Enough lime (1.9 grams)
was added to the grind for the flotation slurry to have a pH of 10.8. To this
grind
30 g/ton (0.060 lb/ton) of either the standard collector, Cytec S-8399,
believed to
be a blend of dithiophosphate and thionocarbamate available from Cytec, Inc.,
Wayne, New Jersey, U.S.A., or the natural oil collector being tested was
added.
The grind charge was transferred to a Denver laboratory flotation cell. The
ore
charge was diluted with water to 27% solids. The ore was conditioned for two
minutes with 20 gram/ton of Oreprep F-533, a blended alcohol frother. The ore
was floated for three minutes. The slurry was then conditioned for three
minutes
with 10 gram/ton of frother and 1.5 gram/ton of sodium isopropyl xanthate
(SIPX). The slurry was floated three more minutes. The concentrates were
collected separately except for the avocado oil and Cytec S-8399.
The results are shown in Table 14. These results show that limonene oil
has the best synergy with SIPX despite not collecting much chalcocite by
itself as
shown in the recovery in the first concentrate (1" Con). All the oils
performed
better as a secondary collector than the regular thiophosphate based Cytec S-
8399.
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Table 14. Results of Tests with Oils and SIPX
Overall 15 Con
Copper Mo Copper Mo Calc Head
Collector Grade Recovery Recovery Grade Recovery Recovery Cu Mo
Limonene 5.50 92.2% 71.7% 2.02 9.98% 59.00% 0.599 0.0162
Safflower 5.23 92.2% 68.2% 1.11 6.26% 55.24% 0.604 0.0168
Coconut 5.77 92.1% 72.2% 1.95 8.67% 49.50% 0.608 0.0179
Eucalyptus 6.00 92.0% 65.9% 2.48 8.09% 39.14% 0.619 0.0154
Avocado 5.63 91.9% 65.9% 0.660 0.0157
Corn 4.90 91.9% 69.0% 2.13 11.42% 52.23% 0.571 0.0164
Cottonseed 5.57 91.7% 71.0% 2.76 12.66% 56.19% 0.590 0.0165
Tung 4.83 91.2% 67.1% 1.39 4.61% 42.21% 0.604 0.0167
S-8399 3.69 90.6% 69.5% 0.599 0.0148
Example X.
In this example, the various combinations of oils and standard collectors
5 are shown. A chalcocite ore with a head assay of 0.543% Cu and 0.014% Mo was
used. The ore charge of 1.0 kilograms was ground at 65% solids to 90% passing
a
212 micron (65 mesh) screen.
The standard flotation procedure was as follows. Enough lime (1.9 grams)
was added to the grind for the flotation slurry to have a pH of 10.8. To this
grind
10 30 g/ton (0.060 lb/ton) of either the standard collector, Cytec S-8399, or
the
natural oil collector being tested was added. The grind charge was transferred
to a
Denver laboratory flotation cell. The ore charge was diluted with water to 27%
solids. The ore was conditioned for two minutes with 20 gram/ton of Oreprep F-
533 frother. The ore was floated for three minutes. The slurry was then
15 conditioned for two minutes with 1.5 gram/ton of sodium isopropyl xanthate
(SIPX). The slurry was floated three more minutes.
The mixtures tested are shown in Table 15. The mercaptan used was
tertiary dodecyl mercaptan. The zinc dithiophosphate used was zinc di- (1,3
dimethylbutyl) -dithiophosphate. The thionocarbamate used was n-ethyl, o-
20 isopropropyl thionocarbamate.
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Table 15. Composition of Mixture Tested
Staple. Percentage Zinc Glycol
Type of of dithio- Thiono- Still
Collector Cottonseed Cottonseed Mercaptan phosphate carbamate Bottoms
Mixture 1 Pima Long 40 40 10 10 0
Mixture 2 Short 40 40 10 10 0
Mixture 3 Short 20 20 20 20 20
Mixture 4 Short 50 10 30 10 0
The results of the flotation tests are summarized in Table 16. The results
show that cottonseed interacts well with the mercaptan, zinc dithiophosphate
and
thionocarbamate collectors.
Table 16. Test results for Various Mixtures
Overall Results Calc. Head
Collector Grade Cu Mo Cu Mo
fixture 3 1.48 0.4% 72.1% .532 p.0144
Mixture 14.99 9.6% 59.4% .562 .0144
Mixture 2 5.48 8.8% 57.8% .544 P.0 14
-8399 1.88 8.6% 55.0% .525 p.0137
Mixture 415.75 8.1% 57.9% .583 p.0142
Example XI.
Pure mineral samples of chalcopyrite, chalcocite and galena were floated
with cottonseed and limonene oils.
The flotation procedure was as follows: 500 gram charges of mineral were
crushed to minus 1.7 millimeter (10 mesh) then ground with 50 gram per ton of
collector to around 90% passing 212 micron (65 mesh). A charge was then placed
in a Denver laboratory flotation cell with enough water to make the slurry 27%
by
weight solids. The slurry was then conditioned with 18 grams/ton of an alcohol
frother for two minutes. The ore was floated for two minutes. The slurry was
then
conditioned for one minute and floated for three minutes. Each concentrate was
collected and weighed separately. One test was conducted with frother alone to
test the free flotability of the mineral. The results are shown below.
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Table 17. Results of Pure Mineral Flotation
Chalcocite Chalcopyrite
Collector Con 1 Con 2 Total Con 1 Con 21 Total
None --- 1.20% 1.20% 4.90% 3.31% 8.20%
Cottonseed 2.51% 1.87% 4.38% 58.75% 5.74% 64.49%
Limonene 3.59% 2.05% 5.64% 19.15% 4.70% 23.85%
Galena
Collector Con 1 Con 2 Total
None 18.98% 2.55% 21.54%
Cottonseed 90.95% 5.57% 96.52%
Limonene 18.53% 2.07% 20.60%
The cottonseed oil collected a good proportion of the pure mineral
chalcopyrite. Comparing the results of cottonseed on chalcopyrite to the
results of
the "no collector" test shows that the cottonseed was responsible for
collecting the
chalcopyrite and that it is a better collector than the limonene oil.
Of course, it should be understood that changes and modifications can be
made to the preferred embodiments described above without departing from the
scope of the present invention. It is therefore intended that the foregoing
detailed
description be regarded as illustrative rather than limiting, and that it be
understood that it is the appended claims including all equivalents, which are
intended to define the scope of this invention.
