U.S. patent application number 14/809546 was filed with the patent office on 2016-02-11 for process and chemistry for reducing dolomite concentrations in phosphate processing.
This patent application is currently assigned to ARR-MAZ PRODUCTS, L.P.. The applicant listed for this patent is Arr-Maz Products, L.P.. Invention is credited to Lucas R. Moore, Todd Parker, Leon Willis.
Application Number | 20160038948 14/809546 |
Document ID | / |
Family ID | 55266701 |
Filed Date | 2016-02-11 |
United States Patent
Application |
20160038948 |
Kind Code |
A1 |
Moore; Lucas R. ; et
al. |
February 11, 2016 |
PROCESS AND CHEMISTRY FOR REDUCING DOLOMITE CONCENTRATIONS IN
PHOSPHATE PROCESSING
Abstract
A magnesium suppressant/flocculant for use in separating
dolomite from calcium phosphate. The magnesium
suppressant/flocculant may be applied at a mine site prior to
subjecting ore fractions to phosphate flotation or at a chemical
plant after grinding.
Inventors: |
Moore; Lucas R.; (Marietta,
GA) ; Parker; Todd; (Lakeland, FL) ; Willis;
Leon; (Bradenton, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Arr-Maz Products, L.P. |
Mulberry |
FL |
US |
|
|
Assignee: |
ARR-MAZ PRODUCTS, L.P.
Mulberry
FL
|
Family ID: |
55266701 |
Appl. No.: |
14/809546 |
Filed: |
July 27, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62035546 |
Aug 11, 2014 |
|
|
|
Current U.S.
Class: |
209/163 ;
526/287; 526/307.5; 526/318.42; 526/318.5 |
Current CPC
Class: |
C08F 220/06 20130101;
C08F 216/085 20200201; B03D 1/01 20130101; C08F 220/56 20130101;
B03D 1/016 20130101; B03D 2201/06 20130101; C08F 220/28 20130101;
B03D 1/008 20130101; B03D 2201/002 20130101; B03D 1/012
20130101 |
International
Class: |
B03B 5/44 20060101
B03B005/44; C08F 220/28 20060101 C08F220/28; C08F 216/08 20060101
C08F216/08; C08F 220/56 20060101 C08F220/56; C08F 220/06 20060101
C08F220/06; C08F 228/02 20060101 C08F228/02 |
Claims
1. A magnesium suppressant/flocculant for use in reducing dolomite
concentrations in phosphate processing, where the magnesium
suppressant/flocculant is a polymer comprising: a base monomer
comprising acrylic acid, acrylamide, or a combination of acrylic
acid and acrylamide; and a functional monomer comprising hydroxyl
ethyl methacrylate, 2-acrylamido-2-methyl propane sulfonic acid,
3-allyloxy-1, 2-propanediol, and/or a derivative thereof.
2. The magnesium suppressant/flocculant of claim 1 where the
molecular weight of the polymer is 3,000 daltons to 30,000
daltons.
3. The magnesium suppressant/flocculant of claim 1 where the
molecular weight of the polymer is 200,000 daltons to 100,000,000
daltons.
4. The magnesium suppressant/flocculant of claim 1 where the charge
of the functional monomer is 10% to 30%.
5. A method of reducing dolomite concentrations in phosphate
processing, the method comprising: adding a magnesium suppressant
to phosphate-containing fractions; conditioning the fractions with
fatty acid; and subjecting the fractions to a phosphate
flotation.
6. The method of claim 5 where the magnesium suppressant is a
polymer comprising: a base monomer comprising acrylic acid,
acrylamide, or a combination of acrylic acid and acrylamide; and a
functional monomer comprising hydroxyl ethyl methacrylate,
2-acrylamido-2-methyl propane sulfonic acid, 3-allyloxy-1,
2-propanediol, and/or a derivative thereof.
7. The method of claim 5 where adding the magnesium suppressant to
the fractions prevents magnesium within the fractions from
interacting with the fatty acid, which minimizes the extent to
which the magnesium interacts with hydrophobic bubbles during the
phosphate flotation.
8. The method of claim 5 further comprising grinding the fractions
prior to adding the magnesium suppressant.
9. The method of claim 8 where the grinding results in a particle
size of less than 100 microns.
10. A method of reducing dolomite concentrations in phosphate
processing, the method comprising: adding magnesium flocculant to
phosphate rock during processing at a chemical plant.
11. The method of claim 10 where the magnesium flocculant is a
polymer comprising: a base monomer comprising acrylic acid,
acrylamide, or a combination of acrylic acid and acrylamide; and a
functional monomer comprising hydroxyl ethyl methacrylate,
2-acrylamido-2-methyl propane sulfonic acid, 3-allyloxy-1,
2-propanediol, and/or a derivative thereof.
12. The method of claim 10, further comprising: transferring the
phosphate rock to a clarifier or thickener, where the magnesium
flocculant selectively flocculates dolomite in the phosphate rock
such that the dolomite settles to the bottom of the clarifier or
thickener; and removing the dolomite from the bottom of the
clarifier or thickener.
13. The method of claim 10, further comprising rinsing the
phosphate rock with pond water to extract soluble magnesium prior
to adding the magnesium flocculant.
14. The method of claim 13, further comprising adding coagulant
with the magnesium flocculant.
15. The method of claim 10, further comprising grinding the
fractions prior to adding the magnesium flocculant.
16. The method of claim 15 where the grinding results in a particle
size of less than 100 microns.
Description
CROSS REFERENCE
[0001] This application is based on and claims priority to United
States Provisional Patent Application No. 62/035,546 filed Aug. 11,
2014.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to a phosphate processing,
and more particularly, but not by way of limitation, to a process
and chemistry for dolomite suppression during phosphate flotation
or for selective flocculation of dolomite from process waters or
calcium phosphate, such as Francolite, apatite, etc.
[0004] 2. Description of the Related Art
[0005] Magnesium is becoming more and more of a concern to
phosphate producers. They have known about dolomite ores for
decades, but have been able to selectively mine the high quality
ores, thus bypassing those rich in the magnesium-containing
dolomite. The concern of magnesium comes from the quality or
concentration that must be processed at the fertilizer production
facilities, who are the customers of the mined phosphate product.
During the acidification process of converting phosphate
concentrate to phosphoric acid, which is needed for the synthesis
of most phosphorus-containing fertilizers, the magnesium can
interact with the sulfuric acid, thus increasing the demand and
cost for this acidification process. It is also known to produce a
range of undesired byproducts such as magnesium pyrophosphate
sludge.
[0006] At the mine site, the ore generally comes in and goes
through various washing and screening stages in an effort to remove
the high quality phosphate rock, which is high in particle size.
The remaining fractions are put through washing and desliming
through a hydrocyclone to further reduce the clays and silica. The
remaining size fraction, which is approximately 100 to
approximately 1000 microns, will move on to a multistaged flotation
where the rougher stage is a phosphate flotation using fatty acid
collectors and the second stage is a cleaner (reverse flotation)
process where the sand is floated with an amine and the phosphate
stays behind and moves on to a dewatering step followed by
transferring or being sold to a fertilizer production chemical
plant. The dolomite can contain a wide range of particle sizes, but
is generally on the higher end of the fraction that is collected
for flotation.
[0007] Once the product reaches the chemical plant, a size
reduction is required and generally occurs in a ball mill. This is
necessary for adequate dissolution and acidification during the
fertilizer production.
[0008] The reason why this problem has not been resolved over these
decades is because of the complex nature of coordinating to the
magnesium in magnesium carbonate versus the calcium in calcium
phosphate. Due to the similar structure, magnesium carbonate can
also be entrained within the calcium phosphate.
[0009] Based on the foregoing, it is desirable to provide a process
for reducing dolomite concentrations in phosphate processing.
[0010] It is further desirable for such a process to involve adding
a magnesium suppressant to the fractions that remain after removing
the high quality phosphate rock to change the characteristics of
the magnesium carbonate to allow it to be separated more easily
from the calcium phosphate during the flotation process.
[0011] It is further desirable for such a process to alternately
involve adding the magnesium suppressant at the chemical plant
during processing, again to change the characteristics of the
magnesium carbonate to allow it to be separated from the calcium
phosphate.
SUMMARY OF THE INVENTION
[0012] In general, in a first aspect, the invention relates to a
magnesium suppressant/flocculant for use in reducing dolomite
concentrations in phosphate processing, the magnesium
suppressant/flocculant is a polymer comprising a base monomer
comprising acrylic acid, acrylamide, or a combination of acrylic
acid and acrylamide and a functional monomer comprising hydroxyl
ethyl methacrylate, 2-acrylamido-2-methyl propane sulfonic acid,
3-allyloxy-1, 2-propanediol, and/or a derivative thereof. The
molecular weight of the polymer may be 3,000 daltons to 30,000
daltons when the polymer is a magnesium suppressant, or alternately
200,000 daltons to 10,000,000 daltons when the polymer is a
magnesium flocculant. The charge of the functional monomer may be
10% to 30%, or could be as high as 99%.
[0013] The magnesium suppressant/flocculant may be used in a method
of reducing dolomite concentrations in phosphate processing. The
method may comprise adding the magnesium suppressant to
phosphate-containing fractions; conditioning the fractions with
fatty acid; and subjecting the fractions to a phosphate flotation.
Adding the magnesium suppressant to the fractions may prevent
magnesium within the fractions from interacting with the fatty
acid, which may minimize the extent to which the magnesium
interacts with hydrophobic bubbles during the phosphate flotation.
The method may further comprise grinding the fractions prior to
adding the magnesium suppressant. The grinding may result in a
particle size of less than 100 microns.
[0014] The magnesium suppressant/flocculant may be used in an
alternate method comprising adding magnesium flocculant to
phosphate rock during processing at a chemical plant. The method
may further comprise transferring the phosphate rock to a clarifier
or thickener, where the magnesium flocculant selectively
flocculates dolomite in the phosphate rock such that the dolomite
settles to the bottom of the clarifier or thickener, and removing
the dolomite from the bottom of the clarifier or thickener.
Alternately, the method may further comprise rinsing the phosphate
rock with pond water to extract soluble magnesium prior to adding
the magnesium flocculant, either alone or with coagulant. The
method may further comprise grinding the fractions prior to adding
the magnesium flocculant, potentially resulting in a particle size
of less than 100 microns.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The devices and methods discussed herein are merely
illustrative of specific manners in which to make and use this
invention and are not to be interpreted as limiting in scope.
[0016] While the devices and methods have been described with a
certain degree of particularity, it is to be noted that many
modifications may be made in the details of the construction and
the arrangement of the devices and components without departing
from the spirit and scope of this disclosure. It is understood that
the devices and methods are not limited to the embodiments set
forth herein for purposes of exemplification.
[0017] In general, in a first aspect, the invention relates to a
process and chemistry for reducing dolomite concentrations in
phosphate processing.
[0018] As discussed above, the typical process for removing
phosphate from ore at a mine site involves a four stage process.
First, the ore may go through various washing and screening stages
to remove large, high quality phosphate rock. Second, the remaining
fractions may be washed, deslimed, and put through a hydrocyclone
to reduce clays and silica. Third, the remaining fractions, which
are typically between 100 and 1000 microns, may be subjected to a
phosphate flotation using fatty acid collectors. Fourth, the
remaining fractions may be subjected to a reverse flotation process
where the sand is floated with an amine and the phosphate stays
behind. The phosphate may then move on to a dewatering step before
being transferred or sold to a fertilizer production chemical
plant.
[0019] In a first embodiment, the process for reducing dolomite
concentrations may involve adding a step prior to step 3, the first
flotation step. Prior to conditioning the phosphate slurry or rock
with fatty acid before entering the rougher float cell, a magnesium
suppressant may be added. The magnesium suppressant may selectively
complex with the magnesium, which may prevent or minimize the
magnesium from interacting with the fatty acid, thus minimizing its
interaction with the hydrophobic bubbles, which is what removes the
phosphate. Essentially, by complexing with the magnesium carbonate,
the magnesium suppressant may inhibit the magnesium carbonate from
complexing with the fatty acid that would generally make it float
due to the similar chemical characteristics to the desired calcium
phosphate.
[0020] Further improvement may be found by grinding the material
prior to adding the magnesium suppressant, as discussed above. The
grinding may occur through pipe sheering during transportation or
through an external mechanical source, such as a ball mill. The
smaller particle size may make the magnesium more liberated and
thus easier to complex. The grinding may result in a particle size
of less than 100 microns.
[0021] In a second embodiment, the process for reducing dolomite
concentrations may occur at the chemical plant. During processing,
the phosphate rock may be transferred into a clarifier or
thickener. During this step, the magnesium suppressant may be added
to selectively flocculate the dolomite from the calcium phosphate.
The dolomite may then settle to the bottom of the thickener or
clarifier and be removed from the bottom and transferred to a
tailings pond while the calcium phosphate is separated.
Alternately, the phosphate product entering the chemical plant may
be rinsed with pond water, which may extract much of the magnesium
as soluble magnesium. The calcium phosphate may be filtered or
removed by some other means. The now magnesium enriched water may
then be treated with either the magnesium suppressant or a
combination or coagulant and magnesium suppressant. In both
in-plant options, the magnesium suppressant should complex with the
magnesium carbonate preferentially over calcium phosphate and
settle, thus separating from the calcium phosphate.
[0022] As with the first embodiment, further improvement may be
found by decreasing the size of the material prior to adding the
magnesium suppressant. Once the product reaches the chemical plant,
a size reduction may be required and may occur in a ball mill. This
is often necessary for adequate dissolution and acidification
during the fertilizer production. During the grinding, not only is
the calcium phosphate ground smaller for the required processing,
but the dolomite is also ground smaller. This may be beneficial for
the application of the present invention. The smaller particle size
may make the magnesium more liberated and thus easier to complex.
The grinding may result in a particle size of less than 100
microns.
[0023] The magnesium suppressant may be a polymer. In particular,
the magnesium suppressant may be at least a copolymer if not a
tertpolymer. The base chemistry may be acrylic acid, acrylamide, or
a combination of acrylic acid and acrylamide. The functionality for
the magnesium complexation may come from adding one or more of the
following monomers to the polymer: hydroxyl ethyl methacrylate,
2-acrylamido-2-methyl propane sulfonic acid, 3-allyloxy-1,
2-propanediol, and/or a derivative thereof. When used during the
flotation stage, the molecular weight of the polymer may be from
around 3,000 daltons to 30,000 daltons, but may go as high as
500,000 daltons. When used at the chemical plant, the molecular
weight of the polymer may be from around 200,000 daltons to
millions of daltons, but may go as low as 20,000 daltons. The
charge of the functionalized monomer may be around 10% to 30%, but
could be higher or lower.
[0024] Whereas, the devices and methods have been described in
relation to the drawings and claims, it should be understood that
other and further modifications, apart from those shown or
suggested herein, may be made within the spirit and scope of this
invention.
* * * * *