U.S. patent application number 14/443870 was filed with the patent office on 2015-11-05 for settling separation process for nuetralized slurry and hydrometallurgical process for nickel oxide ore.
This patent application is currently assigned to SUMITOMO METAL MINING CO., LTD.. The applicant listed for this patent is SUMITOMO METAL MINING CO., LTD.. Invention is credited to Manabu ENOMOTO, Tatsuya HIGAKI, Yoshitomo OZAKI, Hirofumi SHOJI.
Application Number | 20150315671 14/443870 |
Document ID | / |
Family ID | 50775857 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150315671 |
Kind Code |
A1 |
SHOJI; Hirofumi ; et
al. |
November 5, 2015 |
SETTLING SEPARATION PROCESS FOR NUETRALIZED SLURRY AND
HYDROMETALLURGICAL PROCESS FOR NICKEL OXIDE ORE
Abstract
An object of the present invention is to provide a settling
separation process for a neutralized slurry in which a
neutralization step is efficiently performed for a leachate
obtained by the leaching of nickel and cobalt from a nickel oxide
ore, and further a neutralized precipitate obtained by
precipitation of impurity components can effectively be separated
and removed while inhibiting the filtration failure; and to provide
a hydrometallurgical process for a nickel oxide ore, in which the
above process is applied. In the present invention, a
neutralization step is performed by using a magnesium oxide for a
leachate obtained by the leaching of nickel and cobalt from a
nickel oxide ore to obtain a neutralized slurry, and a neutralized
precipitate is separated and removed by the addition of a cationic
flocculant into the neutralized slurry.
Inventors: |
SHOJI; Hirofumi; (Ehime,
JP) ; HIGAKI; Tatsuya; (Ehime, JP) ; OZAKI;
Yoshitomo; (Ehime, JP) ; ENOMOTO; Manabu;
(Ehime, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUMITOMO METAL MINING CO., LTD. |
Minato-ku, Tokyo |
|
JP |
|
|
Assignee: |
SUMITOMO METAL MINING CO.,
LTD.
Minato-ku, Tokyo
JP
|
Family ID: |
50775857 |
Appl. No.: |
14/443870 |
Filed: |
July 29, 2013 |
PCT Filed: |
July 29, 2013 |
PCT NO: |
PCT/JP2013/070476 |
371 Date: |
May 19, 2015 |
Current U.S.
Class: |
75/743 ;
75/711 |
Current CPC
Class: |
C22B 23/0407 20130101;
C22B 3/24 20130101; C22B 23/0461 20130101; C22B 23/0453
20130101 |
International
Class: |
C22B 3/24 20060101
C22B003/24; C22B 3/00 20060101 C22B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2012 |
JP |
2012-254569 |
Claims
1. A settling separation process for a neutralized slurry obtained
by performing a neutralization step for a leachate obtained by
leaching of nickel and cobalt from a nickel oxide ore, comprising:
performing a neutralization step for the leachate by using a
magnesium oxide to obtain a neutralized slurry; and separating and
removing a neutralized precipitate by adding a cationic flocculant
into the neutralized slurry.
2. The settling separation process for a neutralized slurry
according to claim 1, wherein the magnesium oxide is a magnesium
oxide obtained by grinding a bed rock of the nickel oxide ore.
3. The settling separation process for a neutralized slurry
according to claim 1, wherein the leachate is a leachate obtained
by leaching nickel and cobalt from the nickel oxide ore by a
high-temperature high-pressure acid leaching process using a
sulfuric acid solution.
4. The settling separation process for a neutralized slurry
according to claim 1, wherein an additive amount of the cationic
flocculant is 650 to 1350 g/t (solid content) with respect to a
solid content of a leach slurry.
5. The settling separation process for a neutralized slurry
according to claim 1, wherein an additive amount of the cationic
flocculant is 900 to 1100 g/t (solid content) with respect to a
solid content of a leach slurry.
6. A hydrometallurgical process for a nickel oxide ore in which
recovery of nickel and cobalt from a nickel oxide ore is performed
by a high-temperature high-pressure acid leaching process
containing a leaching step, a solid-liquid separation step and a
neutralization step, the neutralization step, comprising:
performing a neutralization step for a leachate obtained by
leaching in the neutralization step using a magnesium oxide to
obtain a neutralized slurry; and adding a cationic flocculant into
the neutralized slurry to separate and remove a neutralized
precipitate.
7. The hydrometallurgical process for a nickel oxide ore according
to claim 6, wherein the magnesium oxide is a magnesium oxide
obtained by grinding a bed rock of the nickel oxide ore.
8. The hydrometallurgical process for a nickel oxide ore according
to claim 6, wherein an additive amount of the cationic flocculant
is 650 to 1350 g/t (solid content) with respect to a solid content
of a leach slurry.
9. The hydrometallurgical process for a nickel oxide ore according
to claim 6, wherein an additive amount of the cationic flocculant
is 900 to 1100 g/t (solid content) with respect to a solid content
of a leach slurry.
Description
TECHNICAL FIELD
[0001] The present invention relates to a settling separation
process for a neutralized slurry, and to a hydrometallurgical
process for a nickel oxide ore. More specifically, the present
invention relates to a settling separation process for a
neutralized slurry obtained by performing a neutralization step for
a leachate obtained by the leaching of nickel and cobalt from a
nickel oxide ore; and to a hydrometallurgical process for a nickel
oxide ore, in which the above process is applied.
[0002] The present application claims a priority based on Japanese
Patent Application No. 2012-254569 filled on Nov. 20, 2012 in
Japan, and the Application is incorporated into the present
application by reference.
BACKGROUND ART
[0003] As a recovery process of a valuable metal from a nickel
oxide ore, a high pressure acid leach process (hereinafter,
referred to as "HPAL process") has been performed. In a HPAL
process, in order to efficiently recover the nickel and cobalt that
are valuable metals, operation in which an excess acid
concentration is maintained at 25 to 50 g/L at the end time of the
leaching has been performed (for example, see Patent document
1).
[0004] Accordingly, the excess acid contained in a leachate is
neutralized by the addition of a neutralizing agent such as alkali
in a neutralization step. Herein, as the neutralizing agent used
for the neutralization step, an inexpensive Ca-based agent
represented by calcium carbonate is employed in many cases.
However, in a case where the leach slurry is a sulfuric acid
solution, a large amount of gypsum is generated as a by-product,
therefore, large equipment is required for the solid-liquid
separation after neutralization.
[0005] Further, in recent years, in view of a short supply of iron
ores, and the like, leach residues having hematite as a main
component, which are generated by a HPAL process, are expected to
be utilized as a raw material of iron and steel. However, in the
leach residues, many components other than the hematite are
contained, therefore, it is desired to efficiently separate the
hematite from these components. In particular, sulfur in leach
residues has a problem that sulfur dioxide is generated in a steel
making step, and the like, therefore, it is desired to perform the
separation so as not to contain sulfur as much as possible (for
example, see Patent document 2).
[0006] In view of such social conditions, as a neutralizing agent
used in a HPAL process, a neutralizing agent with which gypsum such
as a calcium oxide is not generated as a by-product, a so-called
Ca-less neutralizing agent, is attracting attention.
[0007] For example, in Patent document 3, a recovery process
containing a preliminary neutralization step in which the pH of the
solution obtained in the previous step is increased by using a
magnesium oxide is shown.
[0008] However, in the neutralization using a magnesium oxide,
although impurity components in a leachate can effectively be
formed as a neutralized precipitate, when the neutralized
precipitate is subjected to solid-liquid separation in a
postprocess there is a problem of generation of filtration failure
such as clogging of filter cloth, or generation of decrease of
filtering speed. Further, there is a problem that the neutralized
precipitate is mixed into a supernatant after solid-liquid
separation as SS (suspended solid), and causes further filtration
failure or further decrease of filtering speed. Accordingly, a
process in which a neutralized precipitate formed by a
neutralization step can effectively be separated and removed while
inhibiting filtration failure is required.
PRIOR ART DOCUMENTS
Patent Documents
[0009] Patent document 1: Japanese Patent No. 4525428 [0010] Patent
document 2: Japanese Patent Application Laid-Open (JP-A) No.
2010-95788 [0011] Patent document 3: JP-A No. 2007-77459
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0012] The present invention is proposed in order to solve the
problems described above. An object of the present invention is to
provide a settling separation process for a neutralized slurry in
which a neutralization step is efficiently performed for a leachate
obtained by the leaching of nickel and cobalt from a nickel oxide
ore, and further a neutralized precipitate obtained by
precipitation of impurity components can effectively be separated
and removed while inhibiting filtration failure and the like; and
to provide a hydrometallurgical process for a nickel oxide ore, in
which the above process is applied.
Means to Solve the Problems
[0013] The present inventors have conducted intensive studies in
order to achieve the object described above. As a result, the
present inventors found that a neutralization step is performed for
a leachate by using a magnesium oxide as a neutralizing agent to
obtain a slurry after neutralization step (neutralized slurry), a
cationic flocculant is added into the slurry to improve the
filterability of the formed neutralized precipitate, and
consequently the neutralized precipitate is effectively separated
and removed; and thus have completed the present invention.
[0014] That is, the settling separation process for a neutralized
slurry according to the present invention is a settling separation
process for a neutralized slurry obtained by performing a
neutralization step for a leachate obtained by leaching of nickel
and cobalt from a nickel oxide ore, including: performing a
neutralization step for the leachate by using a magnesium oxide to
obtain a neutralized slurry; and separating and removing a
neutralized precipitate by adding a cationic flocculant into the
neutralized slurry.
[0015] Herein, as the magnesium oxide, the one obtained by the
grinding of a bed rock of the nickel oxide ore can be used.
[0016] Further, as the leachate, the leachate obtained by the
leaching of nickel and cobalt from the nickel oxide ore by a
high-temperature high-pressure acid leaching process using a
sulfuric acid solution can be used.
[0017] Further, an additive amount of the cationic flocculant is
preferably 650 to 1350 g/t (solid content) with respect to a solid
content of the leach slurry. In addition, an additive amount of the
cationic flocculant is more preferably 900 to 1100 g/t (solid
content) with respect to a solid content of the leach slurry.
[0018] Further, the hydrometallurgical process for a nickel oxide
ore according to the present invention is a hydrometallurgical
process for a nickel oxide ore, including: performing a
neutralization step for a leachate obtained by leaching in a
neutralization step using a magnesium oxide to obtain a neutralized
slurry; and adding a cationic flocculant into the neutralized
slurry to separate and remove a neutralized precipitate; in which
the hydrometallurgical process performs recovery of nickel and
cobalt from a nickel oxide ore by a high-temperature high-pressure
acid leaching process containing a leaching step, a solid-liquid
separation step, and the neutralization step.
Advantageous Effects of the Invention
[0019] According to the present invention, a neutralization step is
performed for a leachate containing nickel and cobalt by using a
magnesium oxide as a neutralizing agent, and a cationic flocculant
is added into the neutralized slurry so as to separate and remove
the neutralized precipitate, therefore, the filtration failure and
the decrease of the filtering speed are inhibited, and the
neutralized precipitate can effectively be separated and
removed.
[0020] Further, by the adjustment of the additive amount of the
cationic flocculant, the SS concentration can effectively be
decreased, and the clogging of filter cloth, and the like are
prevented and the filterability is further improved, as a result, a
mother liquor for the recovery of nickel and cobalt with high
clarity can be obtained by the high productivity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a process chart of a hydrometallurgical process
for a nickel oxide ore.
[0022] FIG. 2 is a graph chart showing a relationship between the
SS concentration (mg/L) for the additive amount of a cationic
flocculant and the filtration time (seconds).
DESCRIPTION OF THE EMBODIMENTS
[0023] Hereinafter, a specific embodiment (hereinafter, referred to
as "the present embodiment") applying the settling separation
process for a neutralized slurry according to the present invention
will be described in detail in the following order. Further, the
present invention is not limited to the following embodiment, and
appropriate changes may be made as long as the spirit of the
present invention is not changed.
[0024] 1. Overview
[0025] 2. Hydrometallurgical process for nickel oxide ore
[0026] 3. Settling separation process for neutralized slurry [0027]
3-1. Neutralization step [0028] 3-2. Solid-liquid separation
step
<1. Overview>
[0029] The settling separation process for a neutralized slurry
according to the present embodiment is a settling separation
process for a neutralized slurry obtained by a neutralization step
for a leachate that is obtained by the leaching of nickel and
cobalt from a nickel oxide ore by a leaching step using a sulfuric
acid solution and the like.
[0030] Specifically, in the settling separation process for a
neutralized slurry, a neutralization step is performed for a
leachate obtained by the leaching of nickel and cobalt form a
nickel oxide ore by using a magnesium oxide to obtain a neutralized
slurry, and a neutralized precipitate is separated and removed by
the addition of a cationic flocculant into the final neutralized
slurry.
[0031] According to such a process, a neutralization step for a
leachate can efficiently be performed, and further the formed
neutralized precipitate can effectively be separated and removed
while inhibiting the generation of filtration failure and the
like.
[0032] Further, according to the process, by the adjustment of the
additive amount of the cationic flocculant that is added to a
neutralized slurry, the SS (suspended solid) concentration in the
supernatant can effectively be decreased, and a solution after
neutralization step with high clarity, that is, a mother liquor for
the recovery of nickel and cobalt can be obtained. In addition, as
described above, the SS concentration can be decreased, therefore,
also in a solid-liquid separation step for separating and removing
a neutralized precipitate, the clogging of the filter cloth used
for the step, and the like are prevented, the filtration failure or
the decrease of the filtering speed can effectively be inhibited,
as a result, a mother liquor with high clarity can be obtained by
the high productivity.
[0033] Hereinafter, more specifically, the settling separation
process for a neutralized slurry will be described, however, prior
to the description, a hydrometallurgical process for a nickel oxide
ore, which can apply the settling separation process, will be
described. It is noted that in the following hydrometallurgical
process for a nickel oxide ore, an embodiment in which nickel and
cobalt are recovered by a high-temperature high-pressure acid
leaching process (HPAL process) using a sulfuric acid solution is
shown as a specific example.
<2. Hydrometallurgical Process of Nickel Oxide Ore>
[0034] As shown in a process chart of FIG. 1, the
hydrometallurgical process using a HPAL process for a nickel oxide
ore includes: a leaching step S1 in which a sulfuric acid solution
is added into a slurry of a nickel oxide ore, and the resultant
mixture is leached under high temperature and pressure conditions;
a solid-liquid separation step S2 in which leach residues are
separated while the leach slurry is multi-stage washed, and a
leachate containing impurity elements together with nickel and
cobalt is obtained; a neutralization step S3 in which the pH of the
leachate is adjusted to neutralize excess acid in the leachate, and
further the neutralized precipitate containing impurity elements is
separated and removed to obtain a neutralized final solution
containing nickel and cobalt; and a sulfurization step S4 in which
the neutralized final solution is subjected to a sulfurization step
to form a mixed sulfide containing nickel and cobalt.
(1) Leaching Step
[0035] In a leaching step S1, by using a high temperature pressure
vessel (autoclave) and the like, a sulfuric acid solution is added
into a slurry of a nickel oxide ore, and the resultant mixture is
subjected to a stirring step at a temperature of 220 to 280.degree.
C. to form a leach slurry including leach residues and a
leachate.
[0036] Examples of the nickel oxide ore include a so-called
laterite ore mainly such as a limonite ore and a saprolite ore. The
content of nickel in the laterite ore is generally 0.8 to 2.5% by
weight, and the nickel is contained as a hydroxide or a calcium
silicate (magnesium silicate) ore. Further, the content of iron is
10 to 50% by weight, and the iron is mainly in a form of a
trivalent hydroxide (goethite), and divalent iron is partly
contained in the calcium silicate ore. In addition, in a leaching
step S1, in addition to such a laterite ore, an oxide ore
containing a valuable metal such as nickel, cobalt, manganese,
copper, and the like, for example, manganese nodules existing on
the deep sea bottom, and the like are used.
(2) Solid-Liquid Separation Step
[0037] In a solid-liquid separation step S2, a leach slurry formed
in a leaching step S1 is subjected to multi-stage washing, and
separated into a leachate containing nickel and cobalt, and leach
residues. In the solid-liquid separation step S2, for example, an
anionic or nonionic (weak anionic) flocculant is added into a leach
slurry, and the resultant mixture is subjected to a solid-liquid
separation step.
(3) Neutralization Step
[0038] In a neutralization step S3, a neutralization step is
performed in which a neutralizing agent is added into a leachate to
neutralize the excess acid in the leachate, and further an impurity
component such as trivalent iron contained in the leachate is made
into a neutralized precipitate, while inhibiting the oxidation of
the leachate. Further, in the neutralization step S3, the
neutralized precipitate in the slurry after neutralization step
(neutralized slurry), which is obtained by the neutralization step,
is subjected to settling separation, and then subjected to a
solid-liquid separation step by using a solid-liquid separator such
as a thickener to separate and remove the neutralized precipitate.
As a result, a neutralized precipitate slurry, and a neutralized
final solution that is to be a mother liquor for the recovery of
nickel and cobalt are obtained.
[0039] In the present embodiment, in the neutralization step S3, it
is characterized in that a neutralization step is performed by
using a magnesium oxide as a neutralizing agent, and further a
solid-liquid separation step in which the neutralized precipitate
is separated and removed by the addition of a cationic flocculant
into the final neutralized slurry is performed. Details will be
described later.
(4) Sulfurization Step
[0040] In a sulfurization step S4, hydrogen sulfide gas is blown
into a neutralized final solution that is a mother liquor for the
recovery of nickel and cobalt, as a result, a mixed sulfide
containing nickel and cobalt (nickel-cobalt mixed sulfide), which
has less impurity components, and a barren liquor (solution after
sulfurization) in which a nickel concentration is stabilized at a
low level are obtained. It is noted that in the sulfurization step
S4, in a case where zinc is contained in a mother liquor for the
recovery of nickel and cobalt, prior to the separation of nickel
and cobalt as sulfides, zinc can selectively be separated as a
sulfide.
[0041] Further, in the sulfurization step S4, a slurry of the
obtained nickel-cobalt mixed sulfide is subjected to a settling
separation step by using a settling separation apparatus such as a
thickener, the nickel-cobalt mixed sulfide is separated and
recovered from the bottom of the thickener, and further the aqueous
solution component is overflowed and recovered as a solution after
sulfurization.
<3. Settling Separation Process for Neutralized Slurry>
[0042] As described above, in a hydrometallurgical process for a
nickel oxide ore, a leach slurry generated in a leaching step S1 is
subjected to solid-liquid separation in a solid-liquid separation
step S2, as a result, a leachate is obtained. In addition, the
leachate is subjected to a neutralization step in a neutralization
step S3, as a result, the neutralization of the excess acid
contained in the leachate and the separation and removal of the
impurity components contained in the leachate are performed.
[0043] At this time, in the present embodiment, in the
neutralization step S3, a neutralization step using a magnesium
oxide as a neutralizing agent, and a solid-liquid separation step
adding a cationic flocculant into the final neutralized slurry are
performed.
<3-1. Neutralization Step>
[0044] In a neutralization step S3 in the present embodiment, a
magnesium oxide is added as a neutralizing agent into a leachate
containing nickel and cobalt, which is obtained by solid-liquid
separation of a leach slurry to perform a neutralization step. By
the neutralization step, the neutralization for the excess acid in
the leachate and the hydroxylation (precipitation) of the impurity
components contained in the leachate are performed, as a result, a
slurry after neutralization step (neutralized slurry), which
contains a neutralized final solution and a neutralized
precipitate, is obtained.
[0045] More specifically, as a magnesium oxide used as a
neutralizing agent, for example, a bed rock of a nickel oxide ore
containing magnesium silicate and magnesium hydroxide, such as a
saprolite ore can be used. In using a bed rock, the bed rock is
ground into appropriate sizes (for example, roughly 100 to 300 mm)
to be used. As described above, by using a bed rock as a
neutralizing agent, the neutralization step cost can effectively be
reduced.
[0046] The pH conditions in a neutralization step are not
particularly limited, however, neutralization is preferably
performed by the addition of a magnesium oxide so as to be pH 4.0
or less. When the pH exceeds 4.0, a hydroxide of the nickel and
cobalt in a leachate is generated and contained in a neutralized
precipitate, as a result, a recovery loss of these valuable metals
is generated.
<3-2. Solid-Liquid Separation Step>
[0047] In a solid-liquid separation step, a neutralized precipitate
is subjected to settling separation from the neutralized slurry
obtained by the neutralization step described above, and the
neutralized precipitate is separated and removed by using a
solid-liquid separator such as a thickener, as a result, a
neutralized final solution (solution after neutralization) that is
to be a mother liquor for the recovery of nickel and cobalt is
obtained.
[0048] Herein, the present inventors obtained findings that a
neutralized precipitate can efficiently be formed by using a
magnesium oxide as a neutralizing agent in the neutralization step
described above, however, the filterability of the neutralized
precipitate formed is decreased. In particular, in a case where, as
a magnesium oxide, the magnesium oxide obtained by the grinding of
a bed rock of a nickel oxide ore such as a saprolite ore is used,
since a large amount of amorphous silica is contained in the bed
rock, when a neutralization step is performed by using the ground
one as a neutralizing agent, the clarity in a supernatant of the
neutralized final solution is decreased, and the filterability is
significantly lowered.
[0049] Therefore, in a neutralization step S3 in the present
embodiment, it is characterized in that a cationic flocculant is
added into a neutralized slurry to perform solid-liquid separation.
Although the detailed mechanism is not clear, it is considered that
the surface charge of amorphous such as amorphous silica can be
changed by the addition of a cationic flocculant into the
neutralized slurry obtained by a neutralization step using a
magnesium oxide. Consequently, it is considered that the
flocculation of a neutralized precipitate is promoted to improve
the filterability, and further the generation of SS (suspended
solid) from the neutralized precipitate is prevented, as a result,
the filtration failure such as clogging of filter cloth, which is
caused by SS, can be inhibited.
[0050] As described above, in the present embodiment, a cationic
flocculant is added into a neutralized slurry to perform a
solid-liquid separation step, as a result, a neutralized
precipitate (residue) that is excellent in the filterability can be
obtained, and the neutralized precipitate can effectively be
separated and removed.
[0051] The cationic flocculant is not particularly limited, and a
cationic flocculant commonly used can be used. Specifically,
examples of the cationic flocculant include a polyacrylate-based
polymer, a polymethacrylate-based polymer, a polyamine-based
polymer, a dicyandiamide-based polymer, a polyacrylamide-based
polymer, and a vinyl formaldehyde-based polymer.
[0052] The additive amount of the cationic flocculant is not
particularly limited, however, is preferably in the range of 650 to
1350 g/t with respect to a solid content. Herein, in general, the
SS concentration in the neutralized final solution is preferably
controlled to a concentration of less than 100 mg/L, and more
preferably controlled to a concentration of 50 mg/L or less, and
when the SS concentration is controlled to less than 10 mg/L, there
are no problems with the clarity, and it is considered that the
filterability is enhanced. In this respect, the additive amount of
the cationic flocculant falling within the range of 650 to 1350 g/t
allows the SS concentration to be decreased to 100 mg/L or less,
and a mother liquor (mother liquor for the recovery of nickel and
cobalt) with high clarity to be obtained. Further, as described
above, effective decreasing in the SS concentration makes it
possible to the clogging of filter cloth, and the like to be
prevented during the filtration step, and the filterability to be
further improved.
[0053] Furthermore, the additive amount of the cationic flocculant
is more preferably in the range of 750 to 1200 g/t, and furthermore
preferably in the range of 900 to 1100 g/t with respect to a solid
content. Setting of the additive amount in such a range makes the
filtering speed even faster, and the neutralized precipitate
effectively separated and removed while inhibiting the filtration
failure. Further, the setting of the additive amount in the range
described above makes it possible for the SS concentration to be
decreased to around 50 mg/L or less, and further up to less than 10
mg/L, as a result, a mother liquor with higher clarity to be
obtained.
[0054] As described above, in the present embodiment, for example,
in a neutralization step in which the neutralization of the excess
acid and the removal of the impurity components are performed in
the leachate leached with sulfuric acid by a HPAL process, a
neutralization step is performed by using a magnesium oxide as a
neutralizing agent, and a cationic flocculant is added into the
final neutralized slurry to separate and remove a neutralized
precipitate. Consequently, an efficient neutralization step can be
performed, and further the filterability of the neutralized
precipitate formed is improved, as a result, the separation and
removal can effectively be performed onto the solid side by a
solid-liquid separator such as a thickener.
[0055] Further, by the control of the additive amount of the
cationic flocculant to be added into a neutralized slurry, the SS
concentration in a neutralized final solution (supernatant) can
effectively be decreased, the clogging of filter cloth and the like
is prevented and the filterability is further improved, and further
a mother liquor for the recovery of nickel and cobalt with high
clarity can be obtained.
EXAMPLES
[0056] Hereinafter, Examples of the present invention will be
described, however, the present invention is not limited to the
following Examples.
[Investigation of Settling Separation Effect of Neutralized
Precipitate]
[0057] A nickel oxide ore was leached with sulfuric acid by a HPAL
process, a neutralization step was performed by using a magnesium
oxide (magnesium silicate and magnesium hydroxide) for the leachate
obtained by solid-liquid separation, and the neutralization of the
excess acid and the removal of the hydroxides of impurity
components were performed in the leachate. According to the
neutralization step, a neutralized slurry containing a mother
liquor and a neutralized precipitate was obtained.
[0058] After that, 100 mL of the final neutralized slurry was
transferred to a graduated cylinder with scale marks up to 100 mL,
a flocculant shown in a list of the following Table 1 was added at
a level (additive amount) shown in the following Table 2, and the
resultant mixture was shaken up and down three times and then left
to stand to perform solid-liquid separation. 50 mL of the
supernatant was collected 30 minutes after the standing, and was
subjected to suction filtration at 100 torr in the filtering area
of 17.3 cm.sup.2 by using a membrane filter made of cellulose with
a pore size of 0.45 .mu.m.
[0059] Measurement results of the SS (suspended solid)
concentration and filtration time at this time are shown in the
following Table 2. Further, the SS concentration and filtration
time of the leachates (mother liquors) before and after the
neutralization step are also shown in the Table 2 as a
comparison.
TABLE-US-00001 TABLE 1 Dilution Model concentration number
Manufacturer Type (% by weight) PN802 Kurita Water Nonionic 0.03
Industries Ltd. PA804 Kurita Water Anionic 0.03 Industries Ltd.
FL45C SNF Floerger Cationic 1.0
TABLE-US-00002 TABLE 2 Additive SS concen- Filtra- Floccu- amount
(g/t tration tion time lant solid content) (mg/L) (seconds)
Leachate Before neutralization pH 0.5 142 9 Mother liquor After
neutralization pH 3.0 102 1640 Test Example 1 PN802 200 86 2092
Test Example 2 PA804 200 46 2280 Test Example 3 FL45C 500 150 60
Test Example 4 FL45C 900 4 15 Test Example 5 FL45C 1400 124 68
[0060] As shown in Table 2, from the results of the filtration time
of a leachate before neutralization step and the filtration time of
a mother liquor after neutralization step, it was found that the
impurities contained in a leachate are effectively precipitated and
can be made into a neutralized precipitate by a neutralization step
using a magnesium oxide as a neutralizing agent.
[0061] Next, with respect to the separation and removal of the
neutralized precipitate formed in such a manner, from the results
of Test Examples 1 and 2, in the nonionic flocculant and the
anionic flocculant, the separation effect on a neutralized
precipitate was low, and the neutralized precipitate remained in
the supernatant as SS. As a result, the filtration time was 2000
seconds or more, and the filtration failure was generated,
therefore, the neutralized precipitate could not effectively be
removed. On the other hand, in a case where a cationic flocculant
was added, it was found that the filtration time is significantly
faster, and the neutralized precipitate can effectively be
separated and removed.
[0062] From this, it was found that a cationic flocculant is added
into the neutralized slurry obtained by a neutralization step for a
leachate using a magnesium oxide as a neutralizing agent to
separate a neutralized precipitate, as a result, the separation and
removal can effectively be performed while inhibiting the
filtration failure.
[Investigation of Additive Amount of Cationic Flocculant]
[0063] Next, when the additive amount of the cationic flocculant is
changed as shown in the following Table 3 for the neutralized
slurry obtained by a neutralization step for a leachate, the SS
concentration and filtration time in the neutralized final solution
(mother liquor) were measured.
[0064] The measurement results are shown in Table 3. In addition,
in FIG. 2, a graph showing the relationship between the SS
concentration (mg/L) for the additive amount of a cationic
flocculant, and the filtration time (seconds).
TABLE-US-00003 TABLE 3 Additive SS concen- Filtra- Floccu- amount
(g/t tration tion time lant solid content) (mg/L) (seconds) Test
Example 6 FL45C 500 150 60 Test Example 7 FL45C 700 68 32 Test
Example 8 FL45C 900 4 15 Test Example 9 FL45C 1100 6 13 Test
Example 10 FL45C 1400 124 68
[0065] As can be seen from the results shown in Table 3 and FIG. 2,
it was found that a neutralized precipitate is subjected to
filtration separation by the addition of a cationic flocculant, as
a result, the separation and removal can effectively be performed
while inhibiting the filtration failure, however, when the additive
amount exceeds 1350 g/t (solid content), the filtration time is
slightly longer. Further, it was found that also in a case where
the additive amount is less than 500 g/t (solid content), the
filtration time is similarly slightly longer. In addition, it was
found that in the additive amount exceeding the 1350 g/t (solid
content), and in the additive amount less than 500 g/t (solid
content), the SS concentration in a mother liquor is increased.
[0066] On the other hand, it was found that when the additive
amount of a cationic flocculant is in the range of 650 to 1350 g/t
(solid content), the filtration time is 60 seconds or less, and the
SS concentration in a mother liquor is also a preferred value of
100 mg/L or less. Further, it was found that when a cationic
flocculant is added in the range of 750 to 1200 g/t (solid
content), the filtration time is faster of around 30 seconds or
less, and the SS concentration in a mother liquor also is a low
concentration of 50 mg/L or less. In addition, it was found that
when a cationic flocculant is added in the range of 900 to 1100 g/t
(solid content), the filtration time is extremely faster of 15
seconds or less, and the SS concentration in a mother liquor is
also an extremely low concentration of less than 10 mg/L.
[0067] From this, it was found that when the additive amount of a
cationic flocculant is preferably in the range of 650 to 1350 g/t
(solid content), more preferably in the range of 750 to 1200 g/t
(solid content), and furthermore preferably in the range of 900 to
1100 g/t (solid content), a neutralized precipitate is effectively
separated and removed while inhibiting the filtration failure, and
further a mother liquor (mother liquor for the recovery of nickel
and cobalt) with high clarity can be obtained.
[FIG. 1]
[0068] NICKEL OXIDE ORE [0069] LEACHING STEP [0070] LEACH SLURRY
[0071] FLOCCULANT [0072] SOLID-LIQUID SEPARATION STEP [0073] LEACH
RESIDUE SLURRY [0074] LEACHATE [0075] NEUTRALIZING AGENT (MAGNESIUM
OXIDE) [0076] NEUTRALIZATION STEP [0077] NEUTRALIZED SLURRY [0078]
CATIONIC FLOCCULANT [0079] SOLID-LIQUID SEPARATION STEP [0080]
MOTHER LIQUOR [0081] NEUTRALIZED PRECIPITATE SLURRY [0082]
SULFURIZATION STEP [0083] BARREN LIQUOR [0084] MIXED SULFIDE
[FIG. 2]
[0084] [0085] FILTRATION TIME [0086] ADDITIVE AMOUNT (G/T SOLID
CONTENT)
* * * * *