United States Patent [19]
Shaw
[11] Patent Number:
[45] Date of Patent:
4,690,752
Sep. 1, 1987
[75] Inventor:
[73] Assignee:
[54] SELECflVE FLOCCULATION PROCESS
FOR THE RECOVERY OF PHOSPHATE
Douglas R. Shaw, Arvada, Colo.
Resource Technology Associates,
Boulder, Colo.
[21] Appl. No.: 719,343
[22] Filed: Apr. 3, 1985
Related U.S. Application Data
[63] Continuation ofSer. No. 524,889, Aug. 19, 1983, abandoned.
4,265,770 5/1981 Thomas 2101715
4,298,169 11/1981 Iwasaki 209/166
4,555,329 11/1985 Sykes et al. 209/5
OTHER PUBLICATIONS
"Dispersion-Flocculation Characteristics of Florida
Phosphate Slimes", A. F. Colombo, Bureau of Mines,
Minnesota, U.S.A.
Friend et aI., "The Separation of Minerals from Mixtures
by Selective Flocculation", Filtration & Separation,
Jan.-Feb., 1972, pp. 25-28.
Primary Examiner-Peter Hruskoci
Attorney. Agent. or Firm-Sheridan, Ross & McIntosh
6 Claims, No Drawings
A process for separating and recovering non-metallic
minerals, particularly phosphate, from an ore containing
non-uniform sized particles, including colloidal particles.
The ore is slurried in an alkaline, aqueous solution
with a dispersing agent. A flotation collector is added,
and the mixture is contacted with a hydrophobic, high
molecular weight, nonionic polymer to flocculate the
fine particles and make them amenable to subsequent
flotation. A second embodiment provides a process for
the recovery of an upgraded non-metallic ore from ore
slimes, such as phosphate slimes, utilizing a high molecular
weight, polyacrylamide, anionic flocculating agent.
[51] Int. Cl.4 B03D 3/06
[52] U.S. Cl•.......................................... 209/5; 209/49;
209/167; 210/705; 210/907
[58] Field of Search 209/5, 49, 166, 167;
210/704, 705, 725, 727, 732, 734, 907
[56] References Cited
U.S. PATENT DOCUMENTS
2,660,303 11/1953 Haseman 209/5
3,020,231 2/1962 Colwell et aI 2101732
3,302,785 2/1967 Greene 209/5
3,314,537 4/1967 Greene 209/5
3,670,883 6/1972 Weir 209/5
3,837,482 9/1974 Sheridan, III 209/5
4,194,969 3/1980 Chung et aI. 209/166
4,235,709 11/1980 Baudet et aI 209/5
[57] ABSTRACT
4,690,752
This is a continuation of application Ser. No. 524,889, 5
filed Aug. 19, 1983, now abandoned.
FIELD OF THE INVENTION
2
of the references teach the use of a hydrophobic selective
flocculating agent.
It is therefore, the object of the present invention to
improve non-metallic mineral recoveries over those
obtainable by known conventional methods.
A further object of this invention is to provide an
improved and simplified method for phosphate recovery
from phosphate ores by utilizing both coarser sands
and previously waste slimes and subjecting the starting
phosphate feed material to a selective flocculation process
utilizing a hydrophobic flocculating agent.
A still further object of this invention is to provide an
improved and simplified process for phosphate recovery
from phosphate waste slime tailings.
The process of the present invention provides an
excellent overall phosphate recovery of an upgraded
product from a non-uniform size ore containing fine and
colloidal size particles, previously unattainable in, for
example, the Florida phosphate processing industries.
Utilizing the minus 150 mesh to colloidal size particles
of the ore according to the methods of the present invention
increases phosphate yield and reduces tailing
disposal problems now encountered in the Florida
phosphate industries. Moreover, ore slimes, the minus
150 mesh to colloidal size particles, now contained in
tailings ponds can be added to the larger sized particles
to reclaim the approximately 10 to 40% phosphorus
contained in the slimes.
SUMMARY OF THE INVENTION
The present invention involves a process forseparating
and recovering non-metallic minerals, particularly
phosphate, from an ore which has been sized to a nonuniform
size range, from about minus 20 mesh to colloidal
particles. The sized ore is slurried with an alkaline,
aqueous solution with a dispersing agent present. The
non-metallic minera is separated and recovered from
the ore when the slurry is treated by a selective hydrophobic
flocculating agent, followed by conventional
flotation methods, preferably in multiple stages.
In another embodiment of this invention, slimes previously
separated from the larger ore particles are
treated with selected dispersants and flocculating agents
to recover an upgraded phosphate product.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENT
This invention relates a process for the recovery of
non-metallic minerals, particularly phosphate, from an
ore containing said minerals, in which the particle size
of the ore is from about minus 20 mesh down to colloidal
sizes. The fine particles of the ore, the minus 150
mesh to colloidal size, are particularly beneficiated by
the process of this invention for recovering of the desired
non-metallic mineral.
As a broad concept, the process steps involve sizing
the ore to obtain a size range from about minus 20 mesh
to minus 150 mesh. The ore is then preferably washed
with deionized water and a slurry is formed with the
addition of the water. The ratio of solids to liquids is'
selected to allow effective dispersal of the ore particles
and yet provide frequent enough collisions of the particles
after treatment with the flocculating agent to form
recoverable agglomerates. Preferably the ratio of solids
to liquids is at most about 40%, and more preferably
between about 20% and about 30%. A dispersing agent,
such as sodium silicate or sodium hydroxide, is added to
the aqueous solution. If a non-alkaline dispersing agent
15
1
BACKGROUND OF THE INVENTION
SELECfIVE FLOCCULATION PROCESS FOR THE
RECOVERY OF PHOSPHATE
This invention is a minerals beneficiation process
involving selective flocculation for the recovery of 10
non-metalic minerals from slimes and feed materials of
non-uniform particle sizes including slimes, and in particular,
is a process for the recovery of phosphate from
phosphate ores which have not been subjected to desliming.
This invention provides an improved and simplified
process for the treatment of non-metallic minerals, particularly
phosphate, contained in an ore in which the 20
starting particle size of the ore for processing ranges
from about minus 20 mesh to colloidal size. Flocculation
and flotation are known methods for treating ores,
but non of the prior methods have been successful in
providing an economical and simplified method for 25
treating ore containing a significant fraction comprising
a fine particle size, e.g. less than about 10 microns.
In particular, phosphate ores contain substantial
quantities of very fine particles which renders treatment
and recovery of the desired phosphate difficult. In 30
known treatment methods for phosphate ore, the ore is
first sized and then separated into a sand fraction and a
waste slime portion. The particle size of the sand fraction
typically ranges from about minus 20 mesh to about
plus 150 mesh. The fine particles, minus 150 mesh down 35
to colloidal size, are the rejected waste slime portion.
This waste slime portion, containing approximately 10
to 40% of the phosphate contained in the starting ore
material, is discharged into environmentally undesirable
tailings ponds. Known methods of treating the slimes 40
have typically involved processing them after separation
from the larger sands. U.S. Pat. No. 4,235,709 discloses
a treatment by selective flocculation for the fine
fraction of phosphate ores. This patent teaches conditioning
the ore with sodium silicate prior to the addition 45
of water and a subsequent flocculation agent consisting
of a cellulose derivative. U.S. Pat. No. 2,660,303 teaches
a process of adding a sodium hydroxide dispersant to
the slime, followed by starch to selectively flocculate
the phosphate and recover it for separation. U.S. Pat. 50
No. 3,302,785 discloses a process for treating Tennessee
phosphate slimes by negative ion froth flotation followed
by desliming the tailings and combining the tailings
with the froth concentrate to provide an electric
furnace feed. The process is not applicable to Florida 55
phosphate slimes due to the lack of plus 325 mesh phosphate
agglomerates in the Florida slimes. A. F. Colombo
in "Dispersion-Flocculation Characteristics of
Florida Phosphate Slimes," a U.S. Bureau of Mines
report, discloses treating an alkaline, aqueous slurry 60
comprising phosphate waste slimes at pH 8.5 to 10 with
a dispersant and subsequently with a high anionic functionality
cornstarch as a flocculating agent to recover
60-70 percent of the phosphate product, upgraded 2 to
5 percent. None of the above references teaches the 65
advantage of utilizing an ore having a non-uniform
particle size as a feed material for selective flocculation
utilizing a nonionic flocculation agent. In addition, none
4,690,752
3
is used, then the pH of the solution is adjusted to a pH
of about 9 to 11, preferably around 10. After mixing the
slurry with the dispersant, a flotation collector such as
sodium oleate, vapor oil, or other collector known to
the art, is added to render the coarser ore particles 5
hydrophobic. Next, a selective hydrophobic flocculating
agent, preferably polyethylene oxide (PED), is
added to the slurry. The polyethylene oxide will selectively
agglomerate the finer ore particles and render
them hydrophobic. The non-metallic mineral concen- 10
trate is recovered in a froth concentrate after bubbling
air into the slurry following conventional froth flotation
procedures.
More specifically, the ore, suitable for obtaining the
desired non-metallic mineral, is conventionally pre- 15
pared by crushing and/or grinding typically to less than
minus 20 mesh. Preferably, the ore is ground to less than
minus 48 mesh. The particle size distribution of the
crushed ore will typically be about 78% minus 20 to
plus 150 mesh; and 22% minus 150 mesh. Alternatively, 20
the desired ore particle sizes may be generated by the
ore mining methods, or be due to the inherent physical
characteristics of the ore. For example, in conventional
Florida phosphate processing the phosphate is not typically
ground. Instead, the phosphate ore is sized by use 25
of a 20 mesh screen and a cyclone, and the ore size
typically utilized for processing is sand ranging in size
from minus 20 to plus 150 mesh, with the minus 150
mesh size slimes constituting reject tailings. In the
method of a preferred embodiment of this invention, 30
both the sands and the slimes constitute the starting ore
feed material.
The sized ore is then slurried with water or an aqueous
solution, the percentage of solids being preferably
between about 20 and 30%. The water used is prefera- 35
bly obtained from the slimes portion of the feed. Dispersants
are next added to the slurry, such as sodium silicate
and sodium hydroxide. As will be known and un-
. .. derstood by those skilled in the art, other dispersing
agents serving the same purpose may be used. This 40
dispersing agent is added in an amount sufficient to
promote uniform and maximum separation of the particles,
including the extremely fine particles, preferably in
a ratio of dispersant to solids from about 2 to about 5
Ibs/ton of ore and most preferably from about 2 to 45
about 3 lbs/ton of ore. The pH of the slurry should be
alkaline, preferably in the range of about 9 to 11, most
preferably at least about 10. The slurry is mixed for a
short period of time, preferably from about I to about 3
minutes, for a time sufficient to adequately mix all of the 50
reagents within the slurry.
A flotation collector is then added to the dispersed
mixture in an amount sufficient to render the coarser
ore particles hydrophobic for later flotation. Flotation
collectors known to the art, such as sodium oleate, 55
vapor oil, tall oil and the like are suitable, and are pref·
erably added at a ratio of collector to solids of between
about 0.5 and about 4lbs/ton of ore, and most preferably
between about 1 and about 2 lbs/ton of ore. Agitation
of the mixture is then conducted, preferably at high 60
speed, to ensure the coating of all ore particles capable
of being coated with the hydrophobic collector.
The conventional flotation collector does not completely
coat the fine particles of the slimes contained in
the slurry, however, and therefore a hydrophobic floc- 65
culating agent is selected for addition to the slurry at
this point. The hydrophobic flocculating agent is preferably
a high molecular weight nonionic polymer, most
4
preferably polyethylene oxide, which is added in an
amount sufficient to selectively flocculate or agglomerate
all the non-metallic mineral fines present. Flocculation
produces larger agglomerated fines of a particle
size range and chemical environment permitting recoveries
by froth flotation. Preferably the polyethylene
oxide is added at a ratio of flocculating agent to solids
from about 0.1 to about 2 Ibs/ton of ore, and most preferably
from about 0.3 to about 0.4 Ib/ton of dry ore.
This slurry is mixed gently so as not to break up the
formed floccules for a short period of time after the
addition of the polyethylene oxide.
Air is then bubbled through the mixture, preferably
for about 12 minutes at a rate of about 5 liters/minute to
selectively attach to the hydrophobic particles, and
form a froth concentrate containing the desired mineral
values. Phosphate recoveries in the rougher concentrate
of at least about 93% are achievable by the process
of this invention.
The dispersion, flocculation, and flotation steps are
performed preferably at ambient temperature and pressure.
In a preferred embodiment, the flocculation and flotation
steps are conducted in a continuous multiple stage
process.
Preferably the rougher flotation concentrate is
cleaned in at least two stages to produce a phosphate
concentrate having at least 66-67% BPL, with an overall
phosphate recovery of at least about 70%. Tailings
formed in the first cleaning stage can be recirculated to
rougher flotation or to final tailings.
Alternatively, in the methods according to this invention,
waste slime tailings can be added to the starting
feed material. Phosphate ore generally comprises approximately
80% sand to 20% slime. This invention
provides a process such that the slime percentage in the
starting phosphate ore feed material can be increased,
with the addition of tailings pond slime, for recovery of
the previously unrecoverable phosphate content.
In another embodiment of this invention, slurries
comprising only extremely fine ore particles, such as
Florida phosphate slimes unmixed with coarser ore
fractions, are treated by selective flocculation to recover
an upgraded phosphate product.
In the treatment of such slimes, the solid content is
adjusted, if necessary to between about 10 and about
30%, and most preferably between about 15 and about
25% solids.
A dispersing agent is then added, in an amount sufficient
to achieve separation of the fine particles, preferably
at a ratio of dispersant to solids of between about 5
and about 10 lbs/ton, and most preferably between
about 6 to about 8 lbs/ton. The dispersant should be a
low molecular weight polyacrylate such as Cyquest
3223, to avoid the effects of sodium dispersants in attracting
clay particles. The pH is adjusted to at least
about 10 with a pH adjusting agent such as potassium
hydroxide, and the mixture is agitated to disperse the
particles.
Next a flocculating agent is added comprising a high
molecular weight anionic polymer such as Separan MG
500, a polyacrylamide product ofDow Chemical Company.
The flocculating agent is added in an amount
sufficient to agglomerate a major portion of the fine ore
particles, preferably at a ratio of flocculating agent to
solids of between about 0.1 and about 1.0 lbs/ton of
slimes, more preferably between about 0.3 and about 0.5
Ibs/ton of slimes. The mixture is gently agitated for a
As used with these Examples, slimes are feed material
described as minus 150 mesh (Tyler screen sieve). The
sands are feed material described as minus 20 to plus 150 40
mesh.
Typical particle sizing for phosphate slimes is 95%
minus 20 microns, 85% passing 10 microns, and 60-70%
finer than 1 micron. Phosphate distributions are of like
percentages since the concentration of P205 tends to be 45
uniform across the particle size range. The slimes may
be considered as essentially colloidal.
6
EXAMPLE 2
EXAMPLE 3
A series of tests were conducted to evaluate the effect
of varying the slimes concentration in the starting feed
ore on phosphate recovery. The percentage of slimes in
the starting feed ore was varied utilizing 90/10, 80120,
70/30, and 60/40 sands/slimes ratios.
For a baseline control, each varying starting feed ore
was tested both by the flocculation and flotation process
as described in Example 1, and by conventional
flotation processing. Table 1 illustrates the results attained
from this test.
15
Testing was done to evaluate the effect on phosphate
recovery when the starting feed ore constituted 80% by
weight sands (minus 20 to plus 150 mesh) and 20% by
weight slimes (minus 150 mesh). 700 grams of the material
were slurried to a pulp density of 25% solids and
sodium silicate was added as a dispersant in the amount
of 3 Ibs/ton of ore. A flotation collector consisting of
sodium oleate was then added in the amount of 1 to 2
Ibs/ton of ore, and the slurry was vigorously agitated.
PEO was then added in the amount of 0.3 to OAlbs/ton
of ore, and after gentle mixing, air was bubbled into the
mixture and the rough froth concentrate collected.
In the first rough phosphate concentrate of the flotation
process, before cleaning, the phosphate recovery
was 79%. After cleaning of the concentrates by the
methods described above, the final product assayed
65% BPL (bone phosphate of lime) with a recovery of
20 68% phosphate.
Additional testing was done using the same test procedures
and starting ratios of feed material with the
variation of grinding of the plus 48 mesh fraction of the
ore sand feed to provide better liberation of the locked
25 quartz/fluorapatite particles. This testing produced
phosphate recoveries of as much as 93% in the rougher
phosphate concentrates. The cleaned product assayed
67% BPL, with a phosphate recovery of 70%.
Assay/size analysis showed in a very high recovery
of phosphate from all particle sizes, particularly in the
minus 400 mesh slime range where the recovery of
phosphate was over 92%. Study of the kinetics of phosphate
flotation showed that the flocculated phosphate
slimes were consistently recovered preferably ahead of
the individual phosphate grains.
4,690,752
Wt% Composition
20-25 CaJQ(p04.C03l6P2_3
30-35 Si02
20-25 (Fe.AI,Mgh(AI.Sil4
OJQ(OHh(Ca.Nal 30
5-10 (Mg.Al.Fe)s(AI.Sil60 20
(OHh8H20
4-6 AI3(OH13(P04125H20
2-3 KAlSi30g + NaAISi30g
0-3
35
Mineral
5
short period of time, preferably about 3 minutes, to
allow the agglomerates to form, but not subsequently
break up.
The slurry is then allowed to settle for a short period
oftime, typically from a few minutes to about one-half 5
hour, while the phases disengage, and movement within
the slurry is stopped.
At this point the disengaged slimes may optionally be
siphoned off the top of the mixture. Typically about
two-thirds of the water and up to 60% alumina is re- 10
moved with the slimes. The flocculated phase, typically
containing about 20-30% solids, remains in the lower
portion of the mixture.
An upgraded phosphate product is then recovered by
flotation methods from the flocculated phase.
Alternatively, the flocculated mixture is not deslimed,
but is treated by conventional froth flotation
methods to recover a high phosphate froth concentrate.
The following examples are by way of illustration,
not by way of limitation.
EXAMPLE 1
The feed material used in Examples 1 through 6 was
analyzed, with results shown in Table 1.
TABLE 1
Attapulgite
Carbonate-fluorapatite
Quartz
Montmorillonite
Wavellite
Feldspar
Others (zircon. garnet.
rutile. kaolinite.
iron oxide. organics)
TABLE 1
Sandi Cleaner Concentrate Rougher Concentrate Tailings
Slime Test BPL BPL BPL
Weight Conditions Wt% % BPL Recovery % Wt% % BPL Recovery % % BPL Distribution. %
100 Conventional 16.6 66.1 48.6 27.4 44.9 54.3 4.91 30.00
100 Conventional 14.0 44.9 25.8 35.0 32.6 46.7 20.1 53.3
90/10 Conventional 7.5 47.6 21.5 13.0 39.0 30.6 t3.3 69.4
90/10 Flocculation 18.0 67.1 68.2 25.2 55.7 79.1 4.96 20.9
80120 Conventional 10.2 39.7 22.3 23.9 30.9 40.5 14.3 59.5
80120 Flocculation 18.9 64.9 68.8 36.3 77.3 78.6 6.77 21.4
80120 Flocculation 17.5 66.5 70.1 42.2 36.7 92.6 2.42 7.4
80120 Flocculation 52.7 31.1 95.7 1.60 4.3
70/30 Conventional 10.3 39.7 22.3 23.9 30.9 40.5 14.3 59.5
70/30 Flocculation 49.6 24.1 65.6 70.1 21.5 82.7 10.6 17.3
60/40 Conventional 12.9 35.4 23.8 28.2 30.1 44.2 15.0 55.8
60/40 Flocculation 52.8 22.7 64.6 68.6 22.2 82.0 10.7 18.0
Typical particle sizing for the sands is minus 20 mesh
by 150 mesh.
65 EXAMPLE 4
The starting feed was 200 grams of phosphate slimes
of minus 150 mesh. The feed was mixed with deionized
water to a pulp density of 15% solids, and 61bs/top of
4,690,752
35
7
ore of Cyquest 3223 as a dispersing reagent was added
to the mixture. The pH was adjusted to about 10. The
slurry was mixed for 3 minutes with moderate shear
force. Next, 0.4 lbs/ton of Separan MG 500 was added
as a flocculating agent. The flocculant was mixed in 5
with the slurry for a short period of time sufficient to
allow complete mixing, and then the solution was allowed
to settle and the two phases to separate. The two
phases were a top layer slime phase, comprising fine
clay particles, and a lower concentrate phase, compris- 10
ing the phosphate floccules. The slime phase was removed
as waste and not further processed.
Five consecutive selective flocculation and desliming
stages were conducted. The flocculated concentrate
assayed 30% BPL with a recovery of phosphate of over 15
81%. The combined five slime products (waste) represented
44 weight percent and assayed 8.7% BPL (equivalent
to 4% P205). This indicated a large increase in the
rejection of clay slimes (over 25% rejection previously
obtained with only one flocculating and desliming 20
stage) and a corresponding increase in phosphate upgrading
in the flocculated phase. The selectivity of
flocculation of phosphate fines from clays was, therefore,
increased by prolonged and repeated contact of
the flocculant with slimes. 25
The test products were analyzed for various elements
to determine the distribution of the major minerals in
selective flocculation. The results, presented in Table 2,
show that approximately 60% of the alumina (clays)
and silica (quartz, feldspars) gangue constituents were 30
rejected to the waste slime by selective flocculation.
Between 78 and 83% of calcium and fluorine constituents
of the phosphate mineral, fluropatite, reported to
the flocculated concentrate. This is consistent with the
81% BPL recovery in this product.
TABLE 2
8
feed. Phosphate recoveries in the conventional and
column tests, respectively, were 55% and 44% from the
original slimes feed which assayed 20% BPL.
A further test was conducted with flocculation but
without desliming of the clays prior to flotation to determine
the effect of clay slimes removal on phosphate
flotation. This gave only marginal phosphate upgrading
and very poor recoveries.
What is claimed is:
1. A process for separating an upgraded phosphorus
ore from an aqueous slurry containing said phosphorus
ore comprising particles from about minus 20 to about
minus 150 mesh, comprising:
(a) contacting the slurry at a pH of at least about 10
with a dispersing agent selected from the group
consisting of sodium silicate, sodium hydroxide and
polyacrylate in an amount sufficient to achieve
dispersion in the slurry of substantially all the ore
particles;
(b) contacting the dispersed mixture of step (a) with a
flotation collector in an amount sufficient to coat
and render hydrophobic substantially all the ore
particles capable of being coated therewith;
(c) vigorously agitating the mixture of step (b) to
achieve said coating;
(d) contacting the mixture of step (c) with a hydrophobic
nonionic polyethylene oxide in an amount
sufficient to cause the agglomeration of substantial
portions of the fine particles of about minus 150
mesh;
(e) gently mixing the mixture of step (b) to provide
dispersion of the polyethylene oxide of step (d) and
form said agglomerates without significantly
breaking up said agglomerates;
(t) subjecting the mixture of step (e) to froth flotation
Weight Distribution, %
Product % BPL Ca H2C03 CO2 F Mg AI203 Si02
Flocculated conc 56.23 81.4 83.3 79.3 91.3 78.5 65.7 41.3 43.8
5th Slime 7.62 3.9 3.7 4.4 2.4 4.5 6.6 9.8 9.6
4th Slime 9.76 4.0 3.5 4.5 2.2 4.7 7.8 13.0 12.9
3rd Slime ILl5 3.8 3.5 4.5 1.6 4.5 8.9 15.2 14.5
2nd Slime 9.48 3.3 2.9 4.2 Ll 4.0 7.2 13.3 12.2
1st Slime 5.76 3.6 3.1 3.1 1.4 3.8 3.8 7.4 7.0
Head (calc) 100.00 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
Combined slimes 43.77 18.6 16.7 20.7 8.7 21.5 34.3 58.7 56.2
EXAMPLE 6
EXAMPLE 5
The multiple stage selective flocculation process of
Example 4 was reproduced on another similar sample of 50
phosphate slimes from a Florida operation. After four
stages of selective flocculation and desliming, the flocculated
concentrate assayed 32% BPL with a phosphate
recovery of over 82%. The total slimes rejected
assayed 14% BPL at a weight rejection of 32%, The 55
higher BPL assay of the slime reject reflected the 26%
BPL head assay of this sample in contrast to about 20%
BPL for the previous sample.
60
Two flotation tests of the highly agglomerated phosphate
fines of Example 5 were conducted using a conventional
mechanical flotation machine and a column
aspirated with finely divided air bubbles. The tests used
a conventional fatty acid and vapor oil collector 65
scheme, but the mechanical test also used PEO prior to
flotation. The froth products, which assayed 35% BPL,
were only slightly higher than the 30% BPL flotation
by the addition of gas bubbles thereto;
(g) separating the phosphorus-rich froth concentrate
from the mixture of step (t).
2. The process according to claim 1 in which the
particle size of said ore ranges from about 500 to about
10 microns.
3. The process according to claim 1 jn which the
solids to solution ratio in said aqueous slurry is between
about 10% and about 30%.
4. A process for recovering a phosphorus ore upgraded
by at least about 5% phosphate content from a
phosphate slime containing clays and said phosphorus
ore comprising particles of about minus 150 mesh in an
aqueous slurry of a ratio of solids to liquids of between
about 10% and about 30%, comprising:
(a) adjusting the pH of said aqueous slurry to a pH of .
at least about 10;
(b) contacting said slurry with a dispersing agent
selected from the group consisting of sodium silicate,
sodium hydroxide and polyacrylate in an
10
hydrophobic substantially all of the ore particles
capable of being coated therewith;
(0 subjecting said concentrate phase to froth flotation
by the addition of gas bubbles thereto; and
(g) separating the phosphorus-rich froth concentrate
from said concentrate phase.
5. The process of claim 4 in which the dispersing
agent is a low molecular weight polyacrylate.
6. The process of claim 4 in which phosphate is re10
covered from particles of from about 10 microns to
about 500 microns in size.
* * * * *
4,690,752
9
amount sufficient to disperse the fine particles in
the slurry;
(c) contacting said slurry with an anionic polyacrylamide
in an amount sufficient to agglomerate a
substantial portion of the fine ore particles to the 5
exclusion of the clay particles;
(d) allowing the mixture of step (c) to separate into an
upper slime phase and a lower flocculate concentrate
phase;
(e) contacting the concentrate phase with a flotation
collector in an amount sufficient to coat and render
15
20
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30
35
40
45
50
55
60
65