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United States Patent [19]
Schmidt et aI.
[11]
[45]
USOO5106489A
Patent Number:
Date of Patent:
5,106,489
Apr. 21, 1992
14 Claims, 1 Drawing Sheet
3,482.688 12/1969 Bushell et a!. 2091166
4.214.710 7/1980 Wilson 241124
4,261.846 4/1981 Wilson 252/61
4.339.331 7/1982 Lim 209/167
4.362.615 12/1982 Llewellyn et aI 209/167
4,437,983 311984 Petrovich 2091166
FOREIGN PATENT DOCUMENTS
14780 10/1933 Australia 209/166
542775 6/1957 Canada 209/166
406018 211934 United Kingdom 209/166
406043 2/1934 United Kingdom 209/166
Primary Examiner-Stanley S. Silverman
Assistant Examiner-Thomas M. Lithgow
Attorney, Agent. or Firm-Darby & Darby
This invention relates to a method for recovering a bulk
concentrate of zircon and a bulk concentrate of rutileilmenite
from dry plant tailings. A process has been
discovered for froth flotation by manipulating the surface
charges of dry plant tailings. Conditioning reagents,
sulfuric acid to lower the pH; com starch to coat
the minerals to be depressed; sodium fluoride to activate
the minerals to be floated; and amine to float the activated
minerals, are used in the flotation process.
[57] ABSTRACT
2,387.856 10/1945 Pickens 209/166
2.557,455 6/1951 Moyer 209/166
2.610.738 9/1952 Cuthbenson 209/167
2.665.004 1/1954 Zukosky 209/166
2.792.940 5/1957 Baarson 209/166
2.904,177 9/1959 Michal 209/166
3.097,162 7/1963 Baarson 209/166
3.117.924 1/1964 Baarson 209/166
3.480.143 1111969 Mitzmager 209/166
[54] ZIRCO!'li·RUTILE·ILME1'IITE FROTH
FLOTATIO!'li PROCESS
[75] Inventors: Roland Schmidt, Lakewood; Dale L.
Denham, Jr., Louisville, both of
Colo.
[73] Assignee: Sierra Rutile Limited, Santa Rosa,
Calif.
[21] Appl. No.: 742,604
[22] Filed: Aug. 8, 1991
[51] Int. Cl.5 B03D 1/016; B03D 1/018;
B03D 1/02; B03D 1/08
[52] U.S. Cl 209/166; 209/167;
209/17; 209/10
[58] Field of Search 209/13, 17, 18, 164,
209/166, 167, 10; 423/73, 80, 81; 252161
[56] References Cited
U.S. PATENT DOCUMENTS
VERSIZE
25
IMES
SULFURIC ACID
20
AMINE
AMINE
RUTILE AND ILMENITE
51 NK PROOOCT
ZROOO
PRODUCT
NoOH
1
FEED
. OVERSIZE
25
IMES
SULFURIC ACID
STARCH
NaF FI G. 1
20
AMINE
30
AMINE
40
~
•TJ).
•
~=......
(D=......
>"Cl
:'
N
"""" ~
"'I"C""
'IC
N
RUTILE AND ILMENITE
SINK PRODUCT
ZIROON
PRODUCT
...t..i.l o
..0. \
~
QO
\0
SUMMARY OF THE INVENTION
DETAILED DES:RIPTION OF THE
INVENTION
BRIEF DESCRIPTION OF THE DRAWING
This invention is directed to a method for recovering
a bulk concentrate of zircon and a bulk concentrate of
rutile/-ilmenite from dry plant tailings. More specifically,
the invention is directed to a froth flotation process
which manipulates the surface charges of dry plant
tailings with conditioning reagents: acid to lower the
pH; starch to coat the minerals to be depressed; fluoride
ions to activate the mineral to be floated; and a cationic
amine collector to float the activated mineral.
2
zircon and the rutile/ilmenite can be recovered. Thus,
in the present invention both the zircon bulk concentrate
and rutilelilmenite bulk concentrate are recovered
as final products and are further cleaned as required by
5 dry processing to marketable grade products.
It is an advantage of the present invention that high
concentrations of two desired bulk products can be
recovered from dry plant tailings. Other advantages of
the present invention are that the flotation process provides
a means for recovering fine titanium and zircon
values that are not efficiently recovered by conventional
dry processing. Further, since these plant tailings
are rejects from the conventional dry processing. it is
likely that treating them again by the same dry methods
would be inefficient, and hence a new process is required
to allow the tailing to be recovered. It has been
determined that it is advantageous to separate two bulk
products in a froth flotation process by manipulating the
surface charges on the minerals of the dry plant tailings.
FIG. 1 is a flow diagram of the process according to
35 the present invention.
5,106,489
1
ZIRCOS-RL'TILE-ILMEl'IITE FROTH
FLOTATIOS PROCESS
BACKGROUND OF THE INVENTION
This invention relates, in general, to the separation of
dry plant tailings into two bulk concentrates. More
specifically, it relates to a froth flotation method for the
separation of a bulk concentrate which comprises zircon
from another bulk concentrate which comprises 10
rutile and ilmenite.
Conventional flotation processes have been used to
separate minerals such as copper, molybdenum, zinc,
iron, tungsten, and kyanite from waste and other minerals.
The minerals are separated by generating air bub- 15
bles which selectively attach to the mineral or minerals
to be floated. The proper conditions must be present in
the flotation process to permit attachment of the mineral
to the bubbles. The air bubbles, together with the
attached group, rise to the surface to form a froth which 20
is removed. However, if the weight of the particles is
too high or the forces of attachment are too weak, the
minerals will drop from the bubbles and the minerals
will not become part of the froth. Therefore, the weight
of the particles must be low enough and the forces of 25
attachment strong enough to permit the bubbles to rise
while carrying the mineral with it.
It is known in froth flotation technology to use anionic-
type promoters to provide proper conditions for the
attachment of minerals to air bubbles. For example, an 30
anionic-type promoter has been used to condition phosphorus-
bearing minerals for attachment to air bubbles.
See, for instance, U.S. Pat. Nos. 2,557,455 and
3,482.688. It is also known to use depressants in froth
flotation processes for depressing the minerals which
form the sink product. For example, U.S. Pat. No.
2,497,863 is directed to subjecting pulp to a processed
starch product to depress the minerals in the pulp.
In the conventional froth flotation systems, silicates It has now been discovered that a product of zircon
are separated from the titanium values. Titanium values 40 or zircon and aluminum minerals can be separated from
are present in. ilmenite and rutile. Ilmenite is a com- a sink product of rutile and ilmenite by flotation. In the
pound of ferrous oxide and titanium dioxide and rutile is process, the s~rface of the float product is made electroa
compound of titanium dioxide. After the separation of negative at low pH and, hence, ready to accept a catithe
titanium values, the titanium values are retained as onic (positive) amine collector. It is known that at very
the desired product and the silicates are discarded. 45 low pH values minerals such as zircon, garnet, silliman-
In U.S. Pat. No. 2,904,177 a flotation method is used ite, kyanite and corundum will have surfaces that have
for the removal of silicates from an ihnenite ore. The a net positive charge. Therefore, if a cationic collector
silicates present in the ilmenite ore are garnet, feldspar, having a positive charge is added to the minerals there
hornblende and augite. The silicates are removed by will be no electrostatic attraction between the two posigrinding
the ore to -60 mesh size; preparing an aque- 50 tive charges. However, it has been proposed that the
ous pulp with the ground ore; acidifying the pulp with addition of a fluoride ion or a fluorosilicate complex to
hydrofluoric acid; adding starch to the pulp to depress the mineral to be floated at low pH will render the
the titanium values present in the ilmenite ore; adding to surface of the mineral negative and it will then be capathe
pulp a cationic amine flotation agent; and SUbjecting hIe of accepting a cationic amine collector. The precise
the treated pulp to a froth flotation. According to this 55 mechanism for activation of these silicates is uncertain.
patent, the titanium values form the desired product and FIG. 1 illustrates the basic concept of the froth flotathe
silicates are discarded. In this patent, the pH is low- tion flow pr()Ce5S of this invention. A scrubber 10 reered
before subjecting the treated pulp to froth flotation ceives the flotation feed prior to flotation. NaOH is
to remove the feldspars and other silicates. Although added to the scrubber 10 for removing coatings on the
this method has been used to recover titanium values, 60 minerals of the feed, such as slimes. The feed from the
this conventional process has not been used to recover scrubber 10 is transferred to the screens 25 for removing
a zircon float product from a rutile/ilmenite sink prod- minerals too coarse for the flotation process. The screen
uct. undersize product can be made denser in a hydrocy-
It has now been found that zircon, a valuable mineral, clone 27 prior to conditioning. The hydrocyclone can
can be effectively recovered from tailings by means of 65 also remove the slimes released from the minerals in the
froth flotation. In the present invention, dry plant tail- scrubber 10. The screen oversize product can be further
ings are used which comprise zircon, aluminum miner- upgraded and the slimes from the hydrocyclones 1.7 can
als, quartz, ilmenite and rutile from which tailtngs the be discarded. The feed from the hydrocyclones 27 is
5,106,489
4
oxides. The zircon and other silicates are the desired
float products.
The quantity of sulfuric acid used depends on the
desired pH and the presence of acid-consuming miner-
S als; generally, about 1-10 Ibs of sulfuric acid per ton of
feed to the flotation cells are used. Sulfuric acid has the
advantages of low cost and less corrosivity to equipment
than other acids. Also, concentrated sulfuric acid
can be used to lower the pH value without substantially
10 increasing the volume of the feed. Examples of other
acids which can be used as pH modifiers are hydrochloric,
hydrofluoric and nitric acid. However, hydrofluoric
acid at a pH of less than 2.5 may undesirably activate
the titanium oxides.
15 Fluoride is used in various forms, such as NaF, Na2-
SiF6 and HF, to provide fluoride ions for changing the
surface charge of the minerals to be floated. Thus, fluoride
activates the minerals to be floated such that the
surface of the minerals acquires a net negative charge.
The fluoride ions, F-, or fluorosilicate complex,
SiF62-, is attracted to the positively charged surface to
be floated such that a negative surface is produced.
During conditioning at low pH some of the NaF and
Na2SiF6 may be converted to HF. If HF is formed, the
25 HF has an active role in scrubbing the minerals. The
scrubbing of the minerals produces clean surfaces
which help the attachment of activators, depressants
and amine collectors to the mineral surfaces. The addition
of high levels of NaF at low pH can generate
slimes, which can be due to the attacking (or scrubbing)
of the ilmenite and other minerals. Preferably, NaF is
used at about 2.0 Ibs per ton of rougher flotation feed.
The amount of sodium fluoride added can be extended
from about 2.0 Ibs per ton flotation feed to about 5.0 Ibs
per ton of flotation feed depending upon the amounts of
silicate minerals present in the feed and tne concentration
of other chemicals in the flotation water. As the
amount of sodium fluoride is decreased, the froth becomes
darker, indicating that more ilmenite and rutile
are being floated instead of forming the desired sink
product. Since the fluoride ion is negative, if added in
excess, it can neutralize positive collector ions and,
. hence, interfere with flotation. The amount of NaF
required will increase or decrease with the amount and
size of the silicates that are present.
Starch is added to the pulp to depress the minerals
which form the sink product. Starch has been used in
conventional systems for the depression of iron oxides.
However, the possibility exists that starch, as an anionic
SO (-) molecule, could react with the cationic (+) collectors
and neutralize the collector without allowing the
collector to attach to the surface of the mineral. It has
been determined that starch can be used with sodium
fluoride without conflicting with the activation of the
products to be floated or the attachment of the cationic
collector to the activated mineral surfaces. It has been
determined that the starch and the cationic collector do
not conflict with each other to the extent that flotation
is noticeably affected because the titanium oxides remain
positively charged at a pH range of about 2.0-6.0.
It is known that titanium oxides are positively charged
because of having a high point of zero charge (PZC).
For example, the PZC ofrutile is about 6.7 and the PZC
of ilmenite is about 6.5. The positively charged titanium
oxides selectively absorb the negatively charged starch
to prevent absorption of the collector on the titanium
oxides and, hence, cause depression of the oxides. It has
also been determined that starch and sodium fluoride do
3
transferred to the conditioners 20. Sulfuric acid. starch,
NaF. and amine are added in the conditioners 20. After
the conditioners 20, the conditioned flotation feed is
transferred to rougher flotation cells 30 for separating
the flotation feed into the zircon float product and the
rutile and ilmenite sink product. Amine is added during
flotation in the rougher flotation cells 30. The zircon
float product is transferred to cleaner cells 40. Amine is
added in the cleaner cells 40 as required. The cleaner
cells 40 separate the zircon float product from the
cleaner rutile and ilmenite sink product. The rutile and
ilmenite sink product from the cleaner cells 40 is combined
with the rutile and ilmenite sink product from the
flotation cells 30 or it is returned to join the feed to the
rougher cells.
It is desirable in the flotation process that zircon be
removed as the float product from an ilmenite/rutile
sink product. It is also desirable that the aluminum minerals
in the tailings are removed from the ilmenite/rutile
sink product. Examples of such aluminum minerals are 20
garnet, Fe3Ah(Si04h, Ca3AI2(Si04l3, kyanite (Ah03.SiOl)
and corundum (AI203). The aluminum minerals
are floated from the sink product, in a similar manner to
floating the zircon, by manipulating the charges on the
mineral surfaces.
In carrying out the process of the present invention,
the feed is either size classified to remove the coarse
fraction of the feed or is ground to a particle size which
is small enough to· allow the desired mineral to be
floated by air bubbles. Preferably, the feed is ground or 30
size classified to a particle size of about - 80 mesh.
Exemplary of the minerals which can be present in such
tailings are rutile, ilmenite, quartz, garnet, iron oxides.
zircon, corundum, sillimanite and kyanite. While the
preferred feed materials in the process of the invention 35
are dry plant tailings, the process also applies to materials
of the same minerals, such as an ore, or to minerals
other than those from a dry plant.
It may be necessary to process the dry plant tailings
ahead of flotation in order to make the material more 40
suitable for flotation. For example, the dry plant tailings
can be first upgraded by a spiral gravity circuit to remove
some of the low gravity quartz prior to flotation.
In some cases, there may not be enough quartz present
in the feed to warrant a separate gravity circuit ahead of 45
the flotation. Other treatments as are known in the art
can also be used to remove specific minerals ahead of
the flotation, if economically favorable.
Conditioning and subsequent flotation can be carried
out in any conventional cell suitable for froth flotation
at ambient temperature, e.g., a range of about 5° C. to
about 40° c., and at atmospheric pressure. Conditioning
agents comprise a scrubbing agent, a pH modifier, a
depressant, an activator and a collector.
The tailings can be scrubbed prior to flotation with 55
sulfuric acid, hydrochloric acid or sodium hydroxide.
The scrubbing removes coatings on the minerals which
would inhibit separation of the minerals during the
flotation process. It has been determined that sodium
hydroxide is advantageous for removing coatings and is 60
economically preferable.
Sulfuric acid is the preferred pH modifier to lower
the pH as required. Preferably, the pH is lowered to a
value between about 2.0 and 6.0 for flotation of zircon.
Most preferably, the pH is lowered to a pH value of 65
between 2.0 and 3.0 for flotation ofthe aluminum minerals
(i.e., gamet, kyanite sillimanite and corundum) and
zircon, present in the tailings, away from the titanium
5,106,489
6
derivatives of the coco amine can also be used. The
primary coco amines are produced from a coconut fatty
add by a reaction with ammonia. The coco amines are
weak bases, and are soluble in common organic sol-
S vents, but are insoluble in water. The salts are prepared
by reacting the amines with acetic acid and are water
dispersible. The primary amines are in a liquid form at
25" C. Coco primary amines are readily available in the
marketplace. For example, coco primary amines are
sold by Sherex Chemical and Akzo Chemicals. Arosurf
MG-I60, manufactured by Sherex Chemical, and
Armac C, manufactured by Akzo Chemicals, are examples
of coco amine derivatives which can be used as an
amine collector. Armac C is a corrosive paste with a
slightly acetic acid odor. Armac C has a melting point
of about 50" C. and it decomposes on extended heating.
The decomposition rate of Armac C increases with
increasing temperature.
Primary amines can be prepared or mixed in several
ways prior to adding these amines to the flotation conditioners
and flotation cells. There are advantages and
disadvantages to each method of preparation and the
method selected depends on many factors which are
peculiar to the flotation circuit. However, each method
of preparation will result in flotation. For example, the
primary coco amine can be added as a free base, the
amine can be neutralized about 50% with acetic acid
and made up to about a 4.0% solution in water, and the
amine can be mixed with water, neutralized and a
frother added. Other methods for preparing the primary
amines are also known in the art.
Preferably, the pH modifier is added first, followed
by the starch, the fluoride, and the cationic amine collector.
The starch, sodium fluoride and pH modifier can
be added and conditioned in any order before the addition
of the cationic amine collector, but if the preferred
order is not used the results may not be optimal. The pH
modifier, starch, fluoride and cationic amine collector
are all added and conditioned before the flotation begins
in the flotation cells. These flotation cells can be described
as a rougher flotation, which flotation produces
a zircon froth product and an ilmenite/rutile sink product.
It is preferred, but not required, that the amine be
conditioned separately in its own conditioner. The initial
addition of amine can be added to the feed in the
first flotation cell, or added just ahead of the first flotation
cell, rather than being added to the feed in a special
conditioner cell. After the flotation begins, an additional
amount of the starch depressant can be added
based on the color of the froth observed during the
flotation process. For example, if the froth becomes
black in color then ilmenite and rutile are being pulled
into the froth and an additional amount of starch can be
added to depress the ilmenite and rutile, Also, after the
flotation begins, cationic amine collector can be added
as necessary in several stages depending on an analysis
of the froth observed during the flotation process. If the
froth is not mineralized, then more amine is needed.
When the reagents are in balance, the froth has a brown
color (from the zircon) or a pink color (if considerable
garnet is present). The cationic amine collector addition
rate can also be automatically controlled to increase
recovery of the zircon.
The zircon froth product can be subjected to a second
flotation, described as a cleaner flotation, for upgrading
the zircon froth product. In the cleaner flotation,
the zircon froth product from the rougher flotation
is moved to another set of cells called cleaner cells, the
5
not compete for the same mineral surfaces, that is. the
starch interacts with the titanium minerals and slimes
and not with the silicates. The NaF interacts with the
silicates and does not interact to any noticeable degree
with the titanium minerals.
Preferably, corn starch, consisting of polymers of
dextrose, is used as the depressant for rutile, ilmenite
and quartz. Many industrial corn starch products can be
used as a depressant for titanium minerals and to control
slimes, as are known in the art. As an example of the 10
starch, it is possible to use a starch sold under the tradename
Corn Products Starch 3005 by the Corn Products
International Company. The carboxylate group of the
starch provides the negative charges on the starch molecule.
The starch is a dry, fine grained powder and is 15
slightly acidic when dispersed in water. A 2.5% solution
becomes slightly viscous and opalescent upon heating.
Concentrated solutions of the starch become very
viscous and difficult to work with.
To develop the adhesive properties of the starch, the 20
starch is dispersed in water to form a slurry. The slurry
is heated, preferably to a boiling temperature, to disrupt
bonding of the starch molecules. The amount of starch
used in the process is dependent on the quantity of
titanium oxides in the feed, the quantity of amine collec- 25
tor used, the amount of slimes present and the pH value.
It is desired that the quantity of starch is balanced with
the feed composition, size of particles in the feed and
amount of reagents so that the titanium oxides are sufficiently
depressed. It is also desired that the starch be 30
added in a sufficient amount but not be added in excess.
The addition of excess starch can depress zircon and
other minerals which are to be floated. The addition of
starch controls slimes, which can be present in the flotation
cell, by flocculating the slimes. At low pH slimes 35
have a positive charge and the negative starch adheres
to the slimes so that flocculation will occur. Flocculation
of the slimes gathers the slimes together so that the
slimes are not attracted to the mineral surfaces. Excess
starch could neutralize the amine collector and require 40
the use of more amine than is normally necessary. For
example, it has been determined that if starch is added in
excess, the flotation of zircon and other minerals to be
floated can be diminished completely due to the neutralization
of the cationic collector with the anionic starch, 45
since neutralization of the collector can result in con!>
umption of the cationic collector. It is, therefore, preferable
to balance the amount of starch used with the
feed composition and the amount of reagents used. For
example, the quantity of starch used can range from SO
about 0.5 to about 10.0 lbs/ton of flotation feed.
If quartz is present in the feed, the quartz can be
depressed by the addition of starch. The starch preferentially
coats the rutile and the ilmenite and the excess
starch coats the quartz. If it is desired that the quartz be 5S
depressed, starch in excess of the amount to depress the
rutile/ilmenite and control slimes can be added. Alternatively,
if it is desired that the quartz be floated, then
less starch is used in the flotation.
A collector is used to float the desired minerals. Spe- 60
cifically, a collector is adsorbed on the surface of the
mineral to be floated to make the particles hydrophobic
(water repellent) which promotes adherence to the air
bubbles present in the flotation cells.
The amine collector which is used is a fatty amine. 6S
Preferably, the amine collector is a coco amine having
the formula RNH2, where R is C6-e18 with 55% C12
having a molecular weight of about 203, The salts and
5,106,489
A composition of 20.4% Zr02, (about 30% zircon)
and 38.3% Ti02 (about 21% ilmenite and 27% rutile),
with the remainder of the composition consisting of
quartz (about 10%), garnet (about 9%), minor constituents
of kyanite, sillimanite, corundum and iron oxide SS
(about 3%) was scrubbed with 1.0 Ibs/ton NaOH at
82% solids in a rubber-lined, four compartment (I cubic
ft. each), Denver attrition scrubber. Retention time was
9-11 minutes and throughput was 1400 Ibs/hr. The
scrubbed sample was wet screened at 80 and 325 mesh 60
on Derrick and Sweco screens, respectively. This composition
forms the conditioned feed shown in FIG. 1.
H2S04 was added at 3.0 Ibs/ton feed to obtain a pH
value of 2.7. The 80X 325 mesh product was conditioned
with 1.0 Ibs/ton feed ofa 2.5% solution of boiled 6S
com starch. A 3.0% solution of NaF was added at 2.0
Ibs/ton feed at 50% solids. Arosurf 160 was added as a
cationic amine collector at 0.1 Ibs/ton feed.
7
pH is held in the same range as used in the rougher
flotation, and the amine, if used, is added at about 0.05
to 0.30 Ibs per ton of feed to the rougher cells. The
cleaner stage can be used to drop out unwanted ilmenite
and rutile from the froth product into the sink product. 5
where it can be discarded or sent back to the rougher
cell feed. If the cleaner feed is fully reagentized it may
not be necessary to add more amine, starch or sodium
fluoride to the cleaner cells.
Ifsufficient quartz is in the rougher sink product, that 10
product can be taken to another flotation cell where a
cationic silica flotation is carried out at about pH 10.
Sodium hydroxide is added in sufficient quantity to raise
the pH and amine is added in sufficient amount to float
the quartz. Normally, no additional starch is required to 15
keep the ilmenite and rutile depressed. The quartz float
product is discarded and the sink product is a rough
concentrate of rutile and ilmenite.
Lime maybe added prior to the tailings disposal to
neutralize excess sulfuric acid and flocculate slimes 20
produced in the flotation system.
In an embodiment of the present invention, NaOH is
used to increase the pH after flotation so that the quartz
that was depressed by the starch can be floated away
from the titanium oxides. The product produced after 25
removal of the quartz is a high grade titanium oxide
product. The sodium hydroxide also cleans the mineral
surfaces to free the surfaces of slimes by providing
OH- to the slimes which become electronegative and,
hence, are dispersed. For example, the quantity of 30
NaOH used is about 1.0 Ib/ton of feed.
Bentonite clay is used to remove the amine from the
float product, to render the zircon suitable for subsequent
processing. Bentonite has a very high negative
charge. Therefore, bentonite has a high affinity for a 35
positively charged amine. If bentonite is added to the
flotation concentrate and conditioned, the bonds between
the positive amine and the zircon are broken and
new bonds are formed between the positive amine and
the bentonite. Thereafter, the bentonite, with the at- 40
tached amine, can be removed from the float product by
desliming in a unit operation such as cycloning. Bentonite
is composed of the clay mineral montmorillonite
«Na,Ca)(J.33(AI,MghSi40Io(OHh·nH20). Bentonite
can be added at about 2.0 to about 5.0 Ibs/ton of zircon 45
flotation product.
In order to illustrate the process of the present invention,
the following examples are presented:
EXAMPLE 2
The zircon froth product was put back into the same
flotation cell and refloated (cleaner flotation) at pH 2.5
with no collector addition. The froth was conditioned
for one minute (no air) to break loose any entrapped
ilmenite and rutile particles. The sink product from the
cleaner flotation was joined with a new quantity offeed.
The zircon concentrate (final froth product) was removed.
2.5
0.1
0.05
1,500
Flotation
35
4-6
0.20-0.35
2.5
3.5
2.0
SO
3.0
0.1
1,500
Rougher Flotation Conditions
Conditioning
TABLE I
Parameter
1st, Ibslton
Subsequent, Ibs/ton
Cell rpm
Sulfuric Acid. pH
Swch. Ibs/ton
Sodium Fluoride, Ibs/ton
Percent Solids
Time, minutes
Armac C, Ibs/ton
Stages of amine (Armac C)
collector addition
A three stage locked cycle flotation scheme was used
having a zircon rougher flotation at low pH, a zircon
cleaner flotation at low pH and a quartz flotation from
the rougher sink product at high pH. About 500 grams
of a composition having zircon 31.7%, other silicates
11.1%, rutile 33.9%, ilmenite 21.1 %, and miscellaneous
unidentified minerals 2.2%, was used. The rougher
zircon flotation was carried out at a 2.5 pH value. The
conditions of the rougher flotation are summarized in
Table 1.
8
The starch. H2S04, NaF and amine were added to the
scrubbed sample by transferring the sample to a first set
of four plexiglass conditioning cells and adding the
reagents to the cells. Retention time was two minutes
per cell.
The conditioned feed was diluted to 35% to 40%
solids and floated in rougher cells. The feed rate was
220 Ibs/hour to this set of cells to give a retention time
in the cells of about six minutes. Amine was added to
the second and third of four rougher cells at 0.06
Ibs/ton of rougher feed. The rougher concentrate was
diluted to about 20% solids in a launder.
The float product from the rougher cells was transferred
to cleaner cells. In the cleaner cells, the float
product was cleaned. Additional amine was added to a
first, second and third cleaner cell of four cleaner cells
at a rate ofO.03Ibs/ton feed. There was a retention time
of about 12 minutes in the cleaner flotation.
The cleaned zircon flotation product shown in FIG.
1 assayed 47.7% Zr02 and 2.13% Ti02 which is 89.3%
of the Zr02 and 2.0% of the Ti02 in the feed. If the
rougher and first cleaner tailings are combined, recovery
is 98.0% of the Ti02 in the feed and the product
assayed 59.2% TiO,. The major contaminants are
quartz and garnet. The garnet is readily activated and
most is pulled into the final froth product with zircon
since it is activated in a similar manner. The quartz
tends to distribute itself such that most of the coarse
quartz sinks into the ilmenite/rutile product and some
of the finer quartz floats with the zircon. The combined
product also contains 3.2% Zr02 which is 10.7% of the
Zr02 in the feed.
EXAMPLE I so
10
5
25
subjecting the mixture contaInIng the added acid
solution, the fluoride ions, the starch and the cationic
collector, to froth flotation; and
withdrawing a float product comprising the zicron
and a sink product comprising the ilmenite and
rutile.
2. The method according to claim 1, wherein the
mixture of minerals further comprises aluminum silicate
minerals wherein the adding of fluoride ions activates
10 the aluminum silicate minerals and the amine cationic
collector floats the activated aluminum silicate minerals,
the float product further comprises the aluminum
silicate minerals.
3. The method according to claim 2 wherein the
15 mixture is acidified to a pH of between about 2.0 and
3.0.
4. The method according to claim 1 wherein the acid
solution comprises H2S04.
5. The method according to claim 1 wherein the
20 fluoride ions are obtained from at least one member
selected from the group consisting of NaF, HF and
Na2SiF6.
6. The method according to claim 5 wherein the
source of fluoride is NaF.
7. The method according to claim 1 wherein the
amine collector is coco amine having the formula
RNH2 wherein R is C6-C18 with 55% C12.
8. The method of claim 1 further comprising the step
of adding bentonite clay to remove the amine collector
30 from the zircon.
9. The method of claim 1 wherein the starch is com
starch.
10. The method of claim 9 wherein the starch is prepared
by mixing the starch in water to form a slurry and
heating the slurry to a temperature for disrupting bonding
of the molecules of the starch.
11. The method according to claim 1 further comprising
before the step of adding an acid solution, the step of
adding water to the mixture and the step of processing
the particles of the mixture such that the particle sizes of
the minerals are suitable for flotation.
12. The method of claim 1 wherein the mixture of
minerals further comprises quartz and the adding of the
starch depresses the quartz so that the sink product
further comprises the quartz.
13. The method of claim 12 further comprising adding
NaOH for increasing the pH after the step of subjecting
the mixture to flotation and subjecting the sink
product to a second froth flotation and withdrawing a
second float product comprising quartz and a second
sink product comprising the ilmenite and rutile.
14. The method of claim 1 further comprising adding
a second cationic amine collector to the float product
and subjecting the added second cationic amine collector
and the float product to a cleaner froth flotation, and
withdrawing a cleaned float product.
• • • • •
5,106,489
1.500
Flotation
2.5
15
None
2.0-2.5
1.200
Flotation
10.0
25
4.0-4.5 minutes
0.1
0.05
1,500
10.0
25
30 second,
0.20-0.25
2.5
15
None
).0
1.500
TABLE 3
TABLE 2
Qua", Flotation Condition,
Condllioning
Cleaner Flotation Condlllon,
Parameter Conditioning
Sulfuric ACId. pH
c;( Solid~
Reagent Addition
Time. minute,
Cell rpm
The weight splits from the locked cycle flotation 35
scheme are shown in FIG. 1.
Microscopic minerals point count analyses were carried
out on the flotation products and the following
approximate analyses were obtained, The quartz float
product contained about 95% quartz. The zircon float 40
product contained about 72% zircon and the rutile/ilmenite
sink product contained about 97% of rutile and
ilmenite.
We claim:
1. A method for separating a mixture of minerals 45
comprising at least zircon, ilmenite and rutile which
comprises:
adding an acid solution to the mixture to acidify to a
pH of between about 2.0 and 6.0; 50
adding starch to the mixture to depress the ilmenite
and the rutile;
adding a source of fluoride ions to the mixture to
provide a negative surface charge on the zircon
surface to activate the zircon; S5
adding an amine cationic collector to the mixture to
float the activated zircon;
Parameter
1st two. Ib./ton
Subsequent. Ibs/ton
Cell rpm
SodIum Hydroxide. pH
Percent Solid,
TIme
Armac C. Ib./ton
Stage. of amine (Armac C)
collector addition
The sink product from the rougher flotation was then
put in a 500 gram cell and the pH was raised to 10.0
using sodium hydroxide for quartz flotation. The material
in the cell was conditioned for 30 seconds after each
addition of Armac C and the quartz was floated. The
conditions which were used for the quartz flotation are
summarized in Table 3.
9
The conditions of the cleaner flotation are summarized
in Table 2.
60
65