JP7039936B2 - Solid-liquid separation method of nickel high-pressure leachate residue - Google Patents

Description

The present invention relates to a method for solid-liquid separation of nickel high-pressure leachate residue in hydrometallurgy of nickel oxide ore.

In recent years, as a wet smelting method for nickel oxide ore, a high pressure acid leaching method using sulfuric acid has attracted attention. Since this method does not include a dry treatment step such as a drying and roasting step and consists of a consistent wet step, it is advantageous in terms of energy and cost, and nickel with improved nickel grade to about 50% by weight. It has the advantage that a cobalt mixed sulfide can be obtained.

In the hydrometallurgical method of nickel by the high-pressure acid leaching method for obtaining a nickel-cobalt mixed sulfide, the nickel oxide ore was leached with high-temperature pressurized acid to obtain a leaching slurry, and the leaching step was obtained. A solid-liquid separation step is included in which the pH of the leaching slurry is adjusted in a preliminary neutralization step, and then solid-liquid separation is performed to obtain a crude nickel sulfate aqueous solution (leaching solution) containing zinc or the like as an impurity element in addition to nickel and cobalt. ..

In the solid-liquid separation step in this hydrometallurgical method, the leaching slurry obtained from the leaching step is usually separated into a crude nickel sulfate aqueous solution and a leaching residue by a thickener, and at the same time, the leaching slurry is washed in multiple stages. Specifically, as a multi-stage cleaning method, a continuous countercurrent cleaning method (CCD) in which thickeners are connected in multiple stages and the leached slurry is brought into contact with a cleaning liquid containing no valuable metal in a countercurrent manner to wash away the valuable metals adhering to the residue. Method: Counter Current Decantation method) is used, which improves the recovery rate of valuable metals.

Since the thickener underflow in the solid-liquid separation step is sent to the final neutralization step, all Ni contained in the thickener underflow becomes a loss. Therefore, if the sedimentation property of the leachate residue can be increased, the amount of liquid in the underflow slurry of the thickener can be reduced, and the solid content concentration can be increased, the Ni recovery rate can be improved.

In Patent Document 1, in the method for recovering nickel or cobalt, after leaching the oxide ore with sulfuric acid and adjusting the pH with a neutralizing agent, a coagulant is added to a neutralizing solution containing a neutralizing residue, and a thickener is used. It is described that the neutralizing solution and the neutralizing residue are separated by solid-liquid separation.

Further, in Patent Document 2, in the solid-liquid separation treatment method and the wet smelting method of nickel oxide ore, when a flocculant for agglomerating the solid content in the slurry is added, a predetermined proportion of the flocculant is first added. It is described that it is added to the feed well in the sickener of the second stage, and the remaining flocculant is added to the overflow portion in the sickener of the second stage.

However, in Patent Documents 1 and 2, the influence of the amount of the flocculant used on the increase in the solid content concentration in the thickener underflow slurry has not been investigated. Therefore, it has been required to prevent excessive addition of the flocculant to the thickener and to optimize the amount of the flocculant added so that the solid-liquid separability of the leachate residue is not impaired.

International Publication No. 2005/116279 Japanese Unexamined Patent Publication No. 2015-61951

The present invention has been made to solve such a situation, to prevent excessive addition of a flocculant to a thickener, improve the solid-liquid separability of the leachate residue, and increase the solid content concentration. It is an object of the present invention to provide a solid-liquid separation method of a nickel high-pressure leaching residue capable of forming a nickel.

In order to prevent excessive addition of the flocculant to the thickener, the present inventors set the standard of the amount of the flocculant added to the solid-liquid separation step as the residue supplied to the thickener, not the amount of the liquid supplied to the conventional thickener. The present invention was completed by changing the amount to match and examining how much coagulant was added per unit residual amount.

That is, one aspect of the present invention is a solid of a nickel high-pressure leaching residue in which a slurry of a leaching residue after high-pressure sulfuric acid leaching of a nickel oxide ore is pre-neutralized and then the solid content is aggregated and settled using a thickener to be solid-liquid separated. In the liquid separation method, the amount of leachate residue supplied to the thickener is estimated or measured, and the amount of coagulant to be added is adjusted according to the amount of leachate residue. The amount of the flocculant added per residual amount is 0.11 to 0.12 kg / t .

According to one aspect of the present invention, the amount of leachate residue supplied to the thickener is estimated or measured, and an appropriate amount of coagulant according to the amount of leachate residue is added to prevent excessive addition of the coagulant to the thickener. The solid-liquid separability of the leachate residue can be improved and the solid content concentration can be increased. In particular, in the solid-liquid separation method of nickel high-pressure leachate residue in hydrometallurgy of nickel oxide ore, it is preferable to add a flocculant in the above amount in order to increase the solid content concentration of the leachate residue. Further, in a slurry composed of an acidic aqueous solution and mineral mud such as a slurry after leaching, it is preferable to use a nonionic polymer flocculant.

Further, in one aspect of the present invention, the thickeners are provided in multiple stages, and the coagulant whose addition amount has been adjusted can be distributed and added to each thickener.

By distributing and adding the flocculant to each thickener, the solid-liquid separability of the leachate residue can be improved by an appropriate amount of the flocculant in each of the multi-stage thickeners.

Further, in one aspect of the present invention, the pH of the liquid phase portion of the slurry can be adjusted to 2.5 to 3.4 in the preliminary neutralization.

By adding an appropriate amount of a flocculant, the sedimentation property of the leachate residue can be improved even at a high value of pH 2.5 to 3.4 suitable for hydrometallurgical operations.

According to the present invention, it is possible to prevent excessive addition of the flocculant to the thickener, improve the solid-liquid separability of the leachate residue, and increase the solid content concentration.

It is a process drawing which shows the wet smelting method of nickel oxide ore which includes the solid-liquid separation method of the nickel high pressure leachate residue which concerns on one Embodiment of this invention. It is a block diagram of the processing apparatus which performs the CCD method by connecting the thickener in a multi-stage in the solid-liquid separation method of the nickel high pressure leaching residue which concerns on one Embodiment of this invention. It is a block diagram of the thickener (only one stage) in the solid-liquid separation method of the nickel high pressure leaching residue which concerns on one Embodiment of this invention.

Hereinafter, the solid-liquid separation method of the nickel high-pressure leaching residue according to the present invention will be described in the following order with reference to the drawings. The present invention is not limited to the following examples, and can be arbitrarily modified without departing from the gist of the present invention.
1. 1. Wet smelting method of nickel oxide ore 2. Solid-liquid separation method of nickel high-pressure leachate residue 2-1. Outline of solid-liquid separation method 2-2. Configuration of solid-liquid separation processing equipment

<1. Wet smelting method of nickel oxide ore ＞
First, prior to a more specific description of the solid-liquid separation method, a hydrometallurgical method for nickel oxide ore including a solid-liquid separation step in which the solid-liquid separation method of the present invention is used will be described. This wet smelting method for nickel oxide ore is a wet smelting method for leaching and recovering nickel and cobalt from nickel oxide ore by using, for example, a high-pressure acid leaching method (HPAL method).

FIG. 1 shows an example of a process diagram of a hydrometallurgical method by a high-pressure acid leaching method for nickel oxide ore. As shown in FIG. 1, the wet smelting method for nickel oxide ore includes a slurry preparation step S1 in which several types of nickel oxide ore are mixed and mixed and classified with water to prepare an ore slurry, and the obtained nickel oxide ore. The pH was adjusted by the leaching step S2 in which sulfuric acid was added to the slurry and subjected to the leaching treatment under high temperature and high pressure, and the preliminary neutralization step S3 in which the pH of the leaching slurry obtained in the leaching step S2 was adjusted to a predetermined range. It has a solid-liquid separation step S4 for obtaining a leachate containing an impurity element together with nickel and cobalt by separating the residue while washing the leachate slurry in multiple stages. The solid-liquid separation method of the nickel high-pressure leaching residue according to the embodiment of the present invention is mainly related to the solid-liquid separation step S4.

Further, in the hydrometallurgical method of nickel oxide ore, the pH of the leachate separated by solid and liquid in the solid and liquid separation step S4 is adjusted, the neutralized starch containing an impurity element is separated, and neutralization containing zinc together with nickel and cobalt. Zinc sulfide is generated by adding a sulfide agent such as hydrogen sulfide gas to the neutralization step S5 for obtaining the final liquid, and the zinc sulfide is separated and removed to recover nickel containing nickel and cobalt. The purification step S6 for obtaining the mother liquor, the sulfurization step S7 for forming a mixed sulfurized product containing nickel and cobalt by adding a sulfurizing agent to the mother liquor for recovering nickel, and the free sulfuric acid transferred from the solid-liquid separation step S4. It has a final neutralization step S8 for neutralizing the leachate residue contained and the filtrate (poor liquid) containing impurities such as magnesium, aluminum and iron transferred from the sulfurization step S7. The outline of each process will be described below.

(1) Slurry preparation step In the slurry preparation step S1, using nickel oxide ore as a raw material ore, several kinds of nickel oxide ores are mixed so as to have a predetermined Ni grade and an impurity grade, and they are mixed with water. Only undersized ore is used after slurrying and sieving to classify at a predetermined classification point to remove oversized ore particles.

The nickel oxide ore used in the slurry preparation step S1 is mainly a so-called laterite ore such as limonite ore and saprolite ore. The nickel content of the laterite ore is usually 0.8 to 2.5% by weight, and is contained as a hydroxide or a magnesium silicate (magnesium silicate) mineral. The iron content is 10 to 50% by weight, mainly in the form of trivalent hydroxide (goethite), but some divalent iron is contained in the magnesium magnesium mineral. Further, in the leachation step S1, in addition to such laterite ore, an oxide ore containing a valuable metal such as nickel, cobalt, manganese, and copper, for example, a manganese aneurysm endowed on the deep sea bottom may be used.

The method for classifying nickel-oxidized ore is not particularly limited as long as it can classify the ore based on a desired particle size, and for example, it can be performed by sieving using a general vibrating sieve or the like. Further, the classification point is not particularly limited, and a classification point for obtaining an ore slurry composed of ore particles having a desired particle size or less can be appropriately set.

(2) Leaching Step In the leaching step S2, the nickel oxide ore is subjected to a leaching treatment using, for example, a high-pressure acid leaching method. Specifically, sulfuric acid is added to an ore slurry obtained by crushing nickel oxide ore as a raw material, and the mixture is added under high temperature conditions of 220 to 280 ° C. using, for example, a high temperature pressure vessel (autoclave). Nickel, cobalt, etc. are leached from the ore by pressing to form an leached slurry composed of a leached liquid and a leached residue.

In the leaching treatment in the leaching step S2, a leaching reaction and a high-temperature thermal hydrolysis reaction occur, and leaching of nickel, cobalt and the like as sulfates and immobilization of the leached iron sulfate as hematite are performed. However, since the immobilization of iron ions does not proceed completely, the liquid portion of the obtained leachate slurry usually contains divalent and trivalent iron ions in addition to nickel, cobalt and the like. The amount of sulfuric acid added in the leaching step S2 is not particularly limited, and an excess amount such that iron in the ore is leached is used. In the leachate step S2, the pH of the obtained leachate is set to 0.1 to 1.0 from the viewpoint of the solid-liquid separability of the leachate residue containing hematite produced in the solid-liquid separation step S4 of the subsequent step. It is preferable to adjust.

(3) Pre-neutralization step In the pre-neutralization step S3, the pH of the leached slurry obtained in the leaching step S2 is adjusted to a predetermined range. In the leaching step S2 in which the leaching treatment is performed by the high-pressure acid leaching method described above, excess sulfuric acid is added from the viewpoint of improving the leaching rate. Therefore, the obtained leaching slurry contains excess sulfuric acid that was not involved in the leaching reaction, and its pH is very low. Therefore, in the preliminary neutralization step S3, the pH of the leachate slurry is adjusted to a predetermined range so that the washing is efficiently performed during the multi-stage washing in the solid-liquid separation step S4 of the next step.

Specifically, the leachate slurry to be subjected to the solid-liquid separation step S4 preferably has a pH adjusted to about 2 to 6, and more preferably adjusted to 2.5 to 3.4. .. In the preliminary neutralization step S3, it is preferable to raise the pH in consideration of suppressing the pH fluctuation range in the subsequent neutralization step S5 and improving the reaction efficiency in the purification step S6 and the sulfide step S7. If the pH is lower than 2, the cost for making the equipment in the post-process acid resistant is required. On the other hand, if the pH is higher than 6, the nickel leached into the leachate (slurry) precipitates during the washing process and remains as a residue, which may lower the nickel recovery rate and lower the washing efficiency. There is sex.

The method for adjusting the pH is not particularly limited, but the pH can be adjusted within a predetermined range by adding a neutralizing agent such as a calcium carbonate slurry.

(4) Solid-liquid separation step In the solid-liquid separation step S4, the leachate slurry whose pH has been adjusted in the preliminary neutralization step S3 is washed in multiple stages to remove the leachate and the leachate residue containing zinc as an impurity element in addition to nickel and cobalt. obtain. In the solid-liquid separation method of nickel high-pressure leaching residue according to the embodiment of the present invention, the amount of leaching residue supplied to the thickener at this time is estimated or measured, and the amount of the flocculant to be added is adjusted according to the amount of leaching residue. ..

In this solid-liquid separation step S4, after the leaching slurry is mixed with the cleaning liquid, a thickener is provided in multiple stages as a solid-liquid separation device to perform the solid-liquid separation treatment. Specifically, first, the leaching slurry is diluted with a washing liquid, and then the leaching residue in the slurry is concentrated as a sediment of thickener. Thereby, the nickel content adhering to the leachate residue can be reduced according to the degree of dilution thereof. Further, by using the thickeners in multiple stages in this way, it is possible to improve the recovery rate of nickel and cobalt.

As a multi-stage cleaning method in the solid-liquid separation step S4, a continuous countercurrent cleaning method (CCD method: Counter Current Decantation method) in which nickel-free cleaning liquid is used to contact the countercurrent is used. As a result, the amount of cleaning liquid newly introduced into the system can be reduced, and the recovery rate of nickel and cobalt can be improved.

The cleaning liquid is not particularly limited, but a liquid that does not contain nickel and does not affect the process can be used. Among them, it is preferable to use an aqueous solution having a pH of 1 to 3. When the pH of the cleaning liquid is high, bulky aluminum hydroxide is generated when aluminum is contained in the leachate, which causes poor sedimentation of the leachate residue in the thickener. Therefore, as the cleaning liquid, it is preferable to repeatedly use a poor liquid having a low pH (pH is about 1 to 3) obtained in the sulfurization step S7, which is a subsequent step.

The solid-liquid separation treatment by this multi-stage cleaning method will be described in detail later, including the configuration of the thickener.

(5) Neutralization Step In the neutralization step S5, the pH of the leachate separated in the solid-liquid separation step S4 is adjusted, the neutralized starch containing an impurity element is separated, and zinc is contained together with nickel and cobalt. Obtain a Japanese final solution.

Specifically, in the neutralization step S5, the pH of the obtained neutralization final solution is 4 or less, preferably 3.0 to 3.5, more preferably 3.1 to 1, while suppressing the oxidation of the separated leachate. A neutralizing agent such as calcium carbonate is added to the leachate so as to be 3.2, and a neutralizing final solution which is a source of a mother liquor for recovering nickel and a neutralized starch containing trivalent iron as an impurity element. Form with a slurry. In the neutralization step S5, by performing the neutralization treatment on the leachate in this way, the excess acid used in the leachation treatment by the high-pressure acid leaching method is neutralized, and the neutralization end which is the source of the mother liquor for recovering nickel. Along with forming a solution, impurities such as trivalent iron ions and aluminum ions remaining in the solution are removed as a neutralizing starch. This neutralized starch may be returned to the solid-liquid separation step S4 again.

(6) Purifying step In the purifying step S6, a sulfurizing agent such as hydrogen sulfide gas is added to the neutralized final solution obtained from the neutralizing step S5 to perform sulfurization treatment to generate zinc sulfide, and the zinc sulfide is produced. Zinc sulfide is separated and removed to obtain a nickel recovery mother liquor (dezincification final solution) containing nickel and cobalt.

Specifically, for example, zinc is selected for nickel and cobalt by introducing a neutralizing final solution containing zinc together with nickel and cobalt into a pressurized container and blowing hydrogen sulfide gas into the gas phase. Sulfide to produce zinc sulfide and nickel recovery mother liquor.

(7) Sulfurization step In the sulfurization step S7, a sulfurization reaction is generated by using a dezincification final solution, which is a mother liquor for recovering nickel, as a sulfurization reaction initial solution and blowing hydrogen sulfide gas as a sulfurizing agent into the sulfurization reaction initial solution. A mixed sulfide of nickel and cobalt having a small amount of impurity components and a poor liquid in which the concentration of nickel and cobalt is stabilized at a low level are produced.

The sulfurization treatment in the sulfurization step S7 can be performed using a sulfurization reaction tank or the like, and hydrogen sulfide gas is blown into the gas phase portion in the reaction tank with respect to the sulfurization reaction starting liquid charged in the sulfurization reaction tank. A sulfurization reaction is caused by dissolving hydrogen sulfide gas in the solution. By this sulfurization treatment, nickel and cobalt contained in the sulfurization reaction starting liquid are immobilized as a mixed sulfurized product. After completion of the sulfurization reaction, the obtained slurry containing nickel and cobalt mixed sulfide is charged into a solid-liquid separation device such as a thickener and subjected to sedimentation separation treatment, and only the mixed sulfide is separated and recovered from the bottom of the thickener. ..

The aqueous solution component separated through the sulfurization step S7 overflows from the upper part of the thickener and is recovered as a poor liquid. The recovered poor liquid is a solution having an extremely low concentration of valuable metals such as nickel, and contains impurity elements such as iron, magnesium, and manganese that remain without being sulfided. This poor liquid is transferred to the final neutralization step S8 and detoxified. Alternatively, it may be returned to the solid-liquid separation step S4 and used again for nickel recovery.

(8) Final Neutralization Step The final neutralization step S8 contains a leachate residue containing free sulfuric acid transferred from the above-mentioned solid-liquid separation step S4 and impurities such as magnesium, aluminum and iron transferred from the sulfide step S7. Neutralize the filtrate (poor liquid). The final neutralization step S8 is neutralization performed to dispose of the slurry from the hydrometallurgy process to the outside, and refers to the neutralization step performed at the end of the hydrometallurgy process. The leachate residue and filtrate are adjusted to a predetermined pH range by a neutralizing agent, and become a waste slurry (tailing). The tailing generated in this reaction tank is transferred to a tailing dam (waste storage).

Specifically, in the final neutralization step S8, the free sulfuric acid contained in the leachate residue is completely neutralized, the impurities contained in the filtrate are fixed as hydroxides, and the slurry containing the hydroxides of the impurities is tailored dam. Discharge to.

<2. Solid-liquid separation method of nickel high-pressure leachate residue>
(2-1. Outline of solid-liquid separation method)
So far, the flow of the hydrometallurgical method for nickel oxide ore has been described in general, but one embodiment of the present invention mainly includes (4) excessive addition of a flocculant to the thickener in the solid-liquid separation step. It is a solid-liquid separation method of nickel high-pressure leaching residue which can prevent and improve the solid-liquid separability of the leaching residue and increase the solid content concentration. That is, one aspect of the present invention is to pre-neutralize the slurry of the leachate residue after high-pressure sulfuric acid leaching of nickel oxide ore, and then use a thickener to coagulate and settle the solid component to solid-liquid separation. In the liquid separation method, the amount of leachate residue supplied to the thickener is estimated or measured, and the amount of coagulant to be added is adjusted according to the amount of leachate residue.

Since the thickener underflow in the solid-liquid separation step S4 is sent to the final neutralization step S8, all Ni contained in the thickener underflow becomes a loss. Therefore, if the amount of liquid in the underflow slurry of the thickener can be reduced and the solid content concentration can be increased, the Ni recovery rate can be improved.

In the solid-liquid separation step S4, the solution and the residue can be efficiently separated with a thickener by adding a predetermined coagulant to the slurry, and the amount of this thickener underflow extracted is determined by the torque matching of the rake of each thickener. ing. That is, if the exudate residue accumulates in the thickener, the force (torque) applied to the rake of the thickener increases, and the amount of the thickener underflow extracted must be increased.

However, the parameters that affect the torque of the thickener are related not only to the amount of leaching residue in the thickener but also to the characteristics of the leaching residue. For example, the viscosity of the residue slurry and the size of the aggregated residue. If the viscosity of the residual slurry increases due to the addition of an excessive flocculant, or if the size of the aggregated residue increases, a larger force is required when the rake scratches the residue, and the torque increases. That is, when the torque of the thickener increases other than the accumulation of the residue, if the amount of the thickener underflow extracted is increased more than necessary, the amount of the residue in the thickener decreases and the solid content concentration of the thickener underflow slurry decreases. Therefore, the amount of Ni loss increases.

On the other hand, if the addition of the flocculant is small, the residues do not aggregate with each other and the sedimentation property of the residue deteriorates, so that the solid-liquid separability with the thickener deteriorates and the solid content concentration of the thickener underflow slurry decreases. Therefore, the amount of Ni loss increases. In addition, the slurry may overflow from the thickener and adversely affect the subsequent process.

Therefore, in the solid-liquid separation method of the nickel high-pressure leaching residue according to the embodiment of the present invention, the amount of the leaching residue supplied to the thickener is estimated or measured, and the amount of the flocculant to be added is adjusted according to the amount of the leaching residue. This prevents the viscosity of the leached residue slurry from increasing due to the excessive addition of the flocculant and the coarsening of the agglomerates, prevents the excessive addition of the flocculant to the thickener, and improves the solid-liquid separability of the leached residue. The solid content concentration can be increased.

Regarding the amount of leaching residue, for example, the flow rate of the leaching slurry after the preliminary neutralization step S3 is measured, and at the same time, the slurry concentration of the leaching slurry is measured, and the flow rate of the leaching slurry is multiplied by the slurry concentration to multiply the flow rate of the leaching slurry per unit time. The amount of leaching residue can be grasped. The flow rate of the leachate slurry can be measured by a general electromagnetic flow meter, ultrasonic flow meter, or the like. The slurry concentration of the leached slurry can be obtained by measuring the volume of the leached slurry collected at regular intervals, filtering the leached slurry with a filter paper or the like, drying the solid matter remaining on the filter paper, and then measuring the weight. good. Further, it may be obtained by preparing a calibration curve in advance and measuring the specific gravity of the leachate slurry. Of course, it may be measured by a general light transmission type densitometer, ultrasonic type densitometer, or the like.

Once the amount of leaching residue per unit time is known, the optimum amount of flocculant per unit time can be determined. Usually, the amount of the flocculant is added as a constant amount with respect to the amount of the leachate residue, that is, the amount of the flocculant is increased or decreased proportionally according to the increase or decrease of the amount of the leachate residue, but the present invention is not limited to this. The coagulant may be an aqueous solution having a constant concentration, and the flow rate of the coagulant aqueous solution may be increased or decreased. The flow rate of the flocculant may be adjusted by, for example, a general flow meter and a control valve, or may be adjusted by a general diaphragm type metering pump.

The flocculant is not particularly limited as long as it has the effect of coagulating the solid content of the slurry, and examples thereof include anionic or nonionic (weakly anionic) polymer flocculants. In the case of an acidic region such as a slurry after leaching and targeting so-called mineral mud such as a leaching residue, it is preferable to use a nonionic polymer flocculant. As the nonionic polymer flocculant, for example, a polyacrylamide-based or modified polyacrylamide-based polymer flocculant can be used.

As for the flocculant, the amount of the flocculant added per unit residue amount is preferably 0.11 to 0.12 kg / t. The flocculant used here is a solution prepared by dissolving 1 kg of the polymer flocculant at a ratio of 1 ton of water to obtain a 0.1% solution. The optimum amount of the flocculant added is found in the examples described later by the present inventors from the operation of hydrometallurgy of nickel oxide ore. When the addition amount is less than 0.11 kg / t, the solid-liquid separability in the thickener deteriorates, and the slurry overflows from the thickener. When the addition amount exceeds 0.12 kg / t, the viscosity of the leachate residue slurry increases, the agglomerates become coarse, and the (torque) applied to the rake of the thickener increases. Therefore, the amount of the thickener underflow extracted is increased. There is no choice but to increase it. As a result, the solid content concentration of the thickener underflow decreases.

In the present invention, when solid-liquid separation is performed, a coagulant may be added to the slurry, and a coagulant that weakens the electrical repulsive force between the colloidal particles may be added.

Colloidal particles have an electric double layer around them due to their own potential. When the particles aggregate, the electric double layer exerts a repulsive force to inhibit the aggregation of the particles. The coagulant has a function of alleviating this electrical repulsion, and by using this coagulant together with the coagulant, the sedimentation property of the leachate residue in the solid-liquid separation step can be improved.

The type of the coagulant is not particularly limited as long as it has the effect of weakening the electrical repulsive force between the particles, but the inorganic coagulant includes a sulfate band, PAC, aluminum chloride, ferric chloride and the like. Examples of the organic coagulant include cationic polyamine, alkylamine epichlorohydrin condensate, and ethyleneimine. Among these, cation polyamines can be used without adversely affecting the operation because the amount of cation polyamine added is smaller than that of the inorganic coagulant and it may be used in the neutralization step which is a subsequent step. It is particularly preferable in that it can be done. In particular, when a nonionic polymer flocculant is selected as the optimum flocculant, in a slurry consisting of an acidic aqueous solution and mineral mud such as a leached slurry, the surface charge originally possessed by the colloidal particles is the flocculant. The condensing agent with the opposite charge works effectively because it remains uncancelled by.

Further, the coagulant is preferably added at a ratio of 0.001 to 0.010% by weight with respect to the flow rate of the slurry to be treated. As will be described later, in the solid-liquid separation step, a continuous countercurrent washing method (CCD method: Counter Current Decantation method) in which thickeners are provided in multiple stages is mainly used, so that the addition ratio is, for example, condensation with respect to the inlet flow rate of the thickener. It is the addition amount ratio of the agent. If the ratio of the amount of the coagulant added is less than 0.001% by weight, the effect of the coagulant cannot be sufficiently obtained. In addition, since organic coagulants are generally expensive, if the ratio of the amount of the coagulant added exceeds 0.010% by weight, it is not cost-effective and adversely affects the post-process and the final product. It is not preferable because there is a risk. Further, the particles further agglomerated by the coagulant are repelled by the excess charge of the coagulant itself, so that the settling property is deteriorated.

(2-2. Configuration of solid-liquid separation processing device)
Next, the configuration of the solid-liquid separation processing apparatus used in the solid-liquid separation method of the nickel high-pressure leachate residue according to the embodiment of the present invention will be described. FIG. 2 is a configuration diagram showing an example of a processing device that performs a CCD method by connecting thickeners in multiple stages. In the processing apparatus 1 shown in FIG. 2, a configuration example in which the thickeners are connected in five stages is shown, but the number of connected stages is not limited to this.

In the CCD method, a processing device is used in which a thickener consisting of a combination of a sedimentation separation tank in which solid-liquid separation processing is performed and a stirring tank is set as one stage, and the thickeners are connected in a plurality of stages, for example, 5 to 8 stages in series. .. In this processing apparatus 1, the leaching slurry obtained in the leaching step S2 is charged into the first-stage thickener at one end (A side in FIG. 2), and the final stage at the other end (B side in FIG. 2). A cleaning liquid such as industrial water is charged into the thickener of the eyes (fifth stage). Then, the leached slurry and the cleaning liquid come into contact with each other in a countercurrent manner in the processing apparatus 1, and at the same time, a coagulant and a coagulant are added to the leached slurry charged from the A end to reduce the solid content in the slurry. Aggregates and promotes solid-liquid separation.

Here, FIG. 3 shows a configuration diagram of a thickener (only one stage) constituting each stage of the processing device 1 shown in FIG. As described above, the processing apparatus 1 is a device in which a plurality of thickeners are connected in multiple stages, and the thickener 10 is composed of a stirring tank 11 and a settling separation tank 12.

The stirring tank 11 is a tank provided with a stirring member such as a stirring shaft and a stirring blade inside. In the stirring tank 11, the leachate slurry flowed from the thickener in the previous stage and the overflow liquid flowed from the thickener in the rear stage are charged and mixed by stirring. The stirring tank 11 of the first-stage thickener is charged with the leaching slurry obtained in the leaching step S2 instead of the previous-stage thickener, and is in the final stage (fifth stage in the example of FIG. 2). The stirring tank 11 of the thickener is charged with fresh washing water instead of the overflow liquid. In the stirring tank 11, the leaching slurry and the overflow liquid are stirred and mixed, so that the leaching slurry is washed and the adhering water adhering to the solid content is washed away.

The settling separation tank 12 is, for example, a processing tank having a conical bottom and a cylindrical top, and a leachate slurry is charged therein to settle and separate the solid content in the leachate slurry.

The settling separation tank 12 is provided with a tubular feed well 13 vertically arranged inside the settling separation tank 12. For example, when the settling separation tank 12 has a cylindrical shape, the feed well 13 is provided substantially concentrically with the settling separation tank 12. The feed well 13 is a feeding path for feeding (feeding) the leachate slurry supplied from the stirring tank 11 into the sedimentation separation tank 12.

Further, the sedimentation separation tank 12 has an overflow portion 14 for overflowing (OF) the leachate, which is the supernatant liquid obtained by sedimenting and separating the solid content in the leachate slurry, on the peripheral edge of the upper part of the tank. It is provided. The overflow portion 14 has a shape like a gutter, for example, and is connected to a flow path for flowing the overflow liquid from the thickener in the subsequent stage to the stirring tank 11. In the sedimentation separation tank 12, the overflowing solution (hereinafter, also referred to as overflow liquid) is sent to the stirring tank 11 in the previous stage as described above, while the slurry containing other solids is pumped. It is taken out from the lower part of the settling separation tank 12 and pumped to the stirring tank 11 in the subsequent stage by the pump 15.

Next, as shown in FIG. 3, the basic flow when the leachate slurry is washed in multiple stages by the processing device 1 (FIG. 2) in which the thickeners including the stirring tank 11 and the sedimentation separation tank 12 are connected in multiple stages. To explain. The arrows in FIG. 2 indicate the flow of the leachate slurry and the overflow liquid.

First, in the first-stage thickener, the leaching slurry obtained in the leaching step S2 (pH adjusted in the pre-neutralization step S3) and the sedimentation of the second-stage sickener in the subsequent stage are placed in the stirring tank. The overflow liquid from the separation tank is charged, and they are stirred and mixed. In this stirring tank, the adhering water adhering to the solid content in the leachate slurry is washed with the overflow liquid, and nickel ions and the like in the adhering water are recovered to the liquid side. Then, the leachate slurry washed from the stirring tank via the feed well is charged into the sedimentation separation tank.

At this time, for example, in the first-stage thickener, a flocculant for aggregating the solid content in the slurry is added together with the leached slurry via the feed well. Then, the leachate slurry and the flocculant are mixed in the charged sedimentation separation tank, and the solid content in the slurry is coagulated and settled and separated. The slurry containing the separated solid content is extracted from the lower part of the sedimentation separation tank and transferred to the stirring tank of the second-stage thickener in the subsequent stage via a pump. On the other hand, the supernatant liquid overflowing from the sedimentation separation tank via the overflow portion is supplied to the neutralization step S5 of the next step in the hydrometallurgical method.

Next, in the second-stage thickener, a slurry containing the solid content extracted from the lower part of the sedimentation separation tank of the first-stage thickener in the previous stage is charged into the stirring tank, and the slurry in the latter stage is charged. The overflow liquid from the sedimentation separation tank of the third-stage thickener is charged, and nickel ions and the like in the water adhering to the solid content are washed away by the overflow liquid. Then, the slurry obtained by washing in the stirring tank is charged into the sedimentation separation tank via the feed well, and the solid content in the slurry is aggregated and precipitated and separated. The slurry containing the separated solid content is extracted from the lower part of the sedimentation separation tank and transferred to the stirring tank of the third-stage thickener in the subsequent stage via a pump. On the other hand, the overflow liquid overflowing from the sedimentation separation tank via the overflow portion is charged into the stirring tank via a pipe or the like connected to the stirring tank of the first-stage thickener in the previous stage. ..

After that, also in the third-stage thickener and the fourth-stage thickener, the slurry containing the solid content comes into contact with the overflow liquid in a countercurrent manner by the same procedure, so that the slurry is washed in multiple stages.

Then, in the fifth-stage thickener, which is the final stage, a slurry containing the solid content extracted from the lower part of the sedimentation separation tank of the fourth-stage thickener in the previous stage is charged into the stirring tank. , New washing water (for example, a process liquid having a low nickel concentration in the wet smelting process) is charged, and nickel ions and the like in the water adhering to the solid content are washed away by the washing water. Then, the slurry obtained by washing in the stirring tank is charged into the sedimentation separation tank via the feed well, and the solid content in the slurry is aggregated and precipitated and separated. The slurry containing the separated solid content is pumped out from the lower part of the sedimentation separation tank and treated as a leachate residue (CCD residue). On the other hand, the overflow liquid overflowing from the sedimentation separation tank via the overflow portion is charged into the stirring tank via a pipe or the like connected to the stirring tank of the fourth-stage thickener in the previous stage. ..

In this way, by performing the solid-liquid separation treatment while performing multi-stage cleaning on the leachate slurry, it is sufficient to charge only the final stage thickener as new cleaning water, so that the final stage cleaning water is required. No new wash water is required for the thickeners on each stage other than the stages. This makes it possible to save a lot of washing water. As a result, it is possible to prevent a decrease in the nickel and cobalt concentrations of the leachate, improve the equipment efficiency and processing efficiency of the next process after the neutralization step S5, and perform efficient operation with low equipment cost and low operating cost. be able to.

In the solid-liquid separation method of the nickel high-pressure leaching residue according to the embodiment of the present invention, in the treatment of separating the solid content while providing the above-mentioned thickener in multiple stages and washing the leaching slurry in multiple stages, for example, the solid content in the leaching slurry. When adding a flocculant for agglomerating, a predetermined amount (0.11 to 0.12 kg / t) of the flocculant can be added to the first-stage thickener. As a result, the aggregation of the solid content in the leachate slurry proceeds more effectively, and the sedimentation property of the leachate residue can be improved. As a result, the pH of the preliminary neutralization step S3 can be maintained high, the pH fluctuation range in the neutralization step S5 can be suppressed, and the reaction efficiency in the purification step S6 and the sulfide step S7 can be improved. can.

In the solid-liquid separation method of the nickel high-pressure leaching residue according to the embodiment of the present invention, the required amount of the flocculant (0.11 to 0.12 kg / t) may be added separately to each thickener. That is, when it is composed of five-stage thickeners, the flocculant may be divided into five equal parts and added to each thickener. Alternatively, coagulants having different concentrations may be added separately depending on the solid content concentration of the underflow slurry in each thickener. Even in this case, the total amount of the flocculants added in each stage is preferably in the range of 0.11 to 0.12 kg / t.

As an example, a predetermined amount of the flocculant may be added separately to the first-stage thickener and the second-stage thickener. Of the predetermined amount (0.11 to 0.12 kg / t) of the coagulant, a predetermined ratio of the coagulant is added to the feed well of the first stage thickener, and the remaining coagulant is added to the second stage. Add to the overflow part of the thickener. As the ratio of the amount of coagulant added, that is, the ratio of the amount of coagulant added to the first-stage thickener and the amount of coagulant added to the second-stage thickener (first stage: second stage). Is not particularly limited, but is preferably 95: 5 to 50:50, and particularly preferably 90:10.

According to such a solid-liquid separation treatment method, a coagulant acts on each of the feed well where sedimentation occurs and the overflow liquid supplied from the subsequent stage, and the coagulation of the solid content in the leached slurry proceeds more effectively. .. Therefore, even if the number of thickener stages is small, the SS concentration of the overflow liquid finally discharged from the first stage thickener can be reduced. As a result, as an accompanying effect, it is possible to reduce the number of stages of the thickener, the installation space of the solid-liquid separator can be reduced, and the initial capital investment can be significantly reduced, so that efficiency is achieved. It is possible to perform a solid-liquid separation process.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Example 1)
In Example 1, in the solid-liquid separation step, Cryfarm (manufactured by Kurita Water Industries, Ltd.), which is a nonionic polymer flocculant, was added to the thickener and operated. The solid content concentration of the thickener underflow discharged to the final neutralization step was measured while changing the total amount of coagulant added per unit residue amount between 0.11 and 0.12 kg / t in the solid-liquid separation step. .. As a result, the data shown in Table 1 (Sample 1, Sample 2) were obtained.

(Comparative Example 1)
In Comparative Example 1, the total amount of coagulant added per unit residue amount was increased in the solid-liquid separation step, and the amount of coagulant added per unit residue amount was adjusted to around 0.13 kg / t. The operation was carried out in the same manner, and the solid content concentration of the thickener underflow dispensed in the final neutralization step was measured. As a result, the data shown in Table 1 (samples 3 to 7) were obtained.

(Comparative Example 2)
In Comparative Example 2, when the total amount of coagulant added per unit residue amount was reduced from 0.11 kg / t in the solid-liquid separation step, the amount of coagulant added per unit residue amount was 0.10 kg / t. Deterioration of solid-liquid separability with the thickener was observed in the vicinity, and the slurry overflowed from the thickener. Therefore, it was found that an addition amount of 0.10 kg / t or less was inappropriate.

From the results in Table 1, when the addition amount is 0.10 kg / t or less, the slurry overflows from the thickener, and the solid content concentration of the underflow slurry of the thickener is the highest between 0.11 and 0.12 kg / t, which is higher than that. In the vicinity of 0.13 kg / t where the amount of the flocculant added was large, the solid content concentration of the underflow slurry was about 4 to 9% lower than that in the case of the case where the amount of the flocculant added was 0.11 to 0.12 kg / t. From this, it was found that in the solid-liquid separation method of the nickel high-pressure leachate residue in the wet smelting of nickel oxide ore, it is not necessary to have a large amount of flocculant, and an optimum addition amount exists.

Although one embodiment of the present invention and each embodiment have been described in detail as described above, those skilled in the art will be aware that many modifications that do not substantially deviate from the new matters and effects of the present invention are possible. , Will be easy to understand. Therefore, all such modifications are included in the scope of the present invention.

For example, a term described at least once in a specification or drawing with a different term in a broader or synonymous manner may be replaced by that different term anywhere in the specification or drawing. Further, the configuration of the solid-liquid separation method for the nickel high-pressure leaching residue is not limited to that described in one embodiment of the present invention and each embodiment, and various modifications can be carried out.

1 processing device, 10 thickener, 11 stirring tank, 12 settling separation tank, 13 feed well, 14 overflow part, 15 pump

Claims (3)

This is a solid-liquid separation method for nickel high-pressure leached residue, in which the slurry of leached residue after high-pressure sulfuric acid leaching of nickel oxide ore is pre-neutralized, and then solids are aggregated and settled using a thickener for solid-liquid separation.
The amount of the leachate residue supplied to the thickener is estimated or measured, and the amount of the flocculant to be added is adjusted according to the amount of the leachate residue.
The flocculant is a nonionic polymer flocculant and is
A method for solid-liquid separation of nickel high-pressure leached residue, wherein the amount of flocculant added per unit leached residue amount is 0.11 to 0.12 kg / t . The solid-liquid separation method for a nickel high-pressure leaching residue according to claim 1 , wherein the thickener is provided in multiple stages, and the flocculant whose addition amount has been adjusted is distributed and added to each thickener. The solid liquid of the nickel high-pressure leachate residue according to claim 1 or 2 , wherein the pH of the liquid phase portion of the slurry is adjusted to 2.5 to 3.4 in the pre-neutralization. Separation method.

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