Operating method of filtration equipment, dezincification method, and smelting method of nickel oxide ore

Abstract

To avoid degradation of a zinc removal rate, when restarting a slurry supply after a cleaning treatment of a filter, in a dezincification plant that constitutes a filtration unit performing solid-liquid separation treatment by connecting a plurality of filters in parallel.SOLUTION: An operational method of filtration equipment 10 consisting of a plurality of filters 13, 23, and 33 connected in parallel is such that, when the filtration equipment 10 is started up and operated, a total flow rate of slurry supplied to the filtration equipment 10 is, except the case where a target flow rate of the filter 13 having the smallest target flow rate is less than 50% of the target flow rate, the supply flow rate of the slurry distributed to each filter 13, 23, 33 does not become less than 50% of the target flow rate of each filter 13, 23, 33, the supply flow rate of the slurry distributed to each filter 13, 23, 33 is separately controlled.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an operation method of a filtration facility, a de-zincification treatment method, and a smelting method of nickel oxide ore. More specifically, the present invention relates to an operation method of a filtration facility, a de-zincification treatment method, and a smelting method of nickel oxide ore, which are suitable as means for implementing a de-zincification step of separating zinc from a neutralization final solution containing nickel, cobalt, and zinc to produce a mother liquor for nickel recovery in a smelting method of nickel oxide ore consisting of a wet process.

Background Art

[0002] In recent years, as a smelting method of nickel oxide ore, the High Pressure Acid Leach method using sulfuric acid has attracted attention. This smelting method is different from the conventional general dry smelting method of nickel oxide ore. Since it does not include a reduction and drying process and consists of a consistent wet process, it is advantageous in terms of energy and cost.

[0003] Smelting facilities where nickel smelting treatment by the high pressure acid leach method is performed generally include the following plants (a) to (d). (a) Leaching and solid-liquid separation plant: Sulfuric acid is added to a slurry of nickel oxide ore, and leaching treatment is performed under high temperature and high pressure. Subsequently, while the leaching slurry is washed in multiple stages, residues are separated to obtain a leaching solution containing nickel, cobalt, and impurity elements. (b) Neutralization plant: The pH of the leaching solution obtained in the "leaching and solid-liquid separation plant" of (a) is adjusted to separate a neutralization precipitate containing impurity elements, and a neutralization final solution containing nickel, cobalt, and zinc is obtained. (c) De-zincification plant: A sulfurizing agent is added to the neutralization final solution obtained in the "neutralization plant" of (b) to form zinc sulfide, and the zinc sulfide is separated by solid-liquid separation treatment to obtain a leaching solution (mother liquor for nickel recovery) containing nickel and cobalt. (d) Nickel recovery plant: By adding a sulfiding agent to the leachate obtained in the "zinc removal plant" of (c), a mixed sulfide containing nickel and cobalt is formed, and the mixed sulfide is separated.

[0004] In the nickel smelting process by the high-pressure acid leaching method, among the plants of (a) to (d) above, in the "zinc removal plant" of (c), it is required to reduce the zinc (Zn) concentration in the neutralized final solution to 1 mg / L or less. To meet this requirement, in the above-mentioned "zinc removal plant", as a filter for removing fine zinc sulfide precipitates, a closed-type filter typified by a polishing filter is widely used.

[0005] For a closed-type filter such as a polishing filter, it is essential to periodically interrupt the operation and perform a filter cleaning process. And in the "zinc removal plant", when restarting the slurry supply to the filter after this cleaning process, the flow rate of the slurry is not increased all at once to the target flow rate (appropriate flow rate during normal operation) for each filter at the fastest speed, but is increased to the target flow rate over a certain period of time step by step. By such an operation method, a high-quality cake layer can be formed on the filter to improve the efficiency of the filtration process (see Patent Document 1).

[0006] On the other hand, in the nickel smelting process by the high-pressure acid leaching method, for the purpose of removing zinc sulfide generated in the zinc removal process with a higher processing capacity, it has been proposed to use a filtration facility in which a plurality of filters are connected in parallel (see Patent Document 2).

[0007] However, in a zinc removal plant equipped with a filtration facility in which a plurality of filters are connected in parallel, when the flow rate of the slurry is increased step by step over a certain period of time as disclosed in Patent Document 1 when restarting the slurry supply after the filter cleaning process, the filtration rate may decrease and the zinc grade in the leachate containing nickel and cobalt may exceed the specified value.

Prior Art Documents

Patent Document

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] The present invention has been proposed in view of the above circumstances, and an object thereof is to avoid a decrease in the filtration rate that occurs when restarting the supply of slurry in a filtration facility in which a plurality of filters are connected in parallel.

Means for Solving the Problems

[0010] The inventor of the present invention has found that the above problems can be solved by optimizing the ratio of the supply flow rate of the slurry distributed to each of the plurality of filters connected in parallel, and has completed the present invention. Specifically, the present invention provides the following.

[0011] (1) An operation method of a filtration facility including a plurality of filters connected in parallel, wherein when performing a startup operation of the filtration facility, if the total supply flow rate of the slurry to the filtration facility is less than 50% of the target flow rate of the filter having the smallest target flow rate, the slurry is supplied only to the filter having the smallest target flow rate, and if the total supply flow rate of the slurry to the filtration facility is 50% or more of the target flow rate of the filter having the smallest target flow rate, the supply flow rate of the slurry distributed to each of the filters is individually controlled so that it does not become less than 50% of the target flow rate of each of the filters. An operation method of a filtration facility.

[0012] According to the operation method of the filtration equipment in (1), in a filtration equipment where a plurality of filters are connected in parallel, it is possible to avoid a decrease in the filtration rate that occurs when the slurry supply is restarted.

[0013] The operation method of the filtration equipment according to (1), wherein the supply flow rate of the slurry distributed to each of the filters is controlled based on the following distribution rules (i), (ii), and (iii). (i) When the total supply flow rate of the slurry to the filtration equipment is less than 50% of the target flow rate of the filter with the smallest target flow rate, the slurry is supplied only to the filter with the smallest target flow rate. (ii) When the total supply flow rate of the slurry to the filtration equipment is 50% or more of the target flow rate of the filter with the smallest target flow rate, in all the filters to which the slurry is supplied, as long as it is possible to supply at a flow rate of 50% or more of the target flow rate of each filter, the slurry is preferentially supplied to the filter with the largest target flow rate among the filters capable of supplying at a flow rate of 50% or more of the target flow rate. However, in all the filters to which the slurry is supplied, as long as it is possible to supply at a flow rate of 50% or more of the target flow rate of each filter, an appropriate amount of slurry can also be supplied to the other filters other than the filter to which the slurry is preferentially supplied. (iii) For each filter, the flow rate of the slurry supplied to each filter is gradually increased until the respective target flow rate is reached. Here, "gradually" means a state of adjusting the flow rate of the slurry in which a "flow rate increase step" and a "flow rate maintenance step" of increasing the flow rate with the maximum capacity of the pump for feeding the slurry are set as one set, and a plurality of sets (a plurality of steps) are performed every predetermined time.

[0014] According to the operation method of the filtration equipment in (2), in a filtration equipment where a plurality of filters are connected in parallel, it is possible to avoid a decrease in the filtration rate that occurs when the slurry supply is restarted with higher accuracy.

[0015] The zinc removal process of separating and removing zinc sulfide in the slurry by solid-liquid separation is carried out by the operation method of the filtration equipment described in (1) or (2), which is a zinc removal process method.

[0016] According to the zinc removal process method of (3), in a zinc removal plant equipped with a filtration facility in which a plurality of filters are connected in parallel, it is possible to avoid a decrease in the zinc removal rate that occurs when the slurry supply is restarted.

[0017] (4) The slurry is a slurry obtained by subjecting a neutralization final solution containing zinc together with nickel and cobalt obtained by neutralizing the leachate of the nickel oxide ore in a wet smelting method of nickel oxide ore to a sulfidation treatment to form zinc sulfide. The zinc removal process of separating and removing the zinc sulfide is carried out by the zinc removal process method described in (3), which is a smelting method of nickel oxide ore.

[0018] According to the smelting method of nickel oxide ore of (4), in the smelting of nickel oxide ore, it is possible to sufficiently reduce the zinc grade in the leachate containing nickel and cobalt without depending on an increase in the addition amount of the sulfiding agent or the like.

Advantages of the Invention

[0019] According to the present invention, in a zinc removal plant equipped with a filtration facility in which a plurality of filters are connected in parallel, it is possible to avoid a decrease in the zinc removal rate that occurs when the slurry supply is restarted.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0021] Hereinafter, specific embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiments, and various modifications are possible without changing the gist of the present invention.

[0022] <Nickel Oxide Ore Smelting Method> The "nickel oxide ore smelting method (hereinafter, also simply referred to as the 'nickel oxide ore smelting method')" of the present invention is a wet smelting method of nickel oxide ore for leaching and recovering nickel and cobalt from nickel oxide ore using a high-pressure acid leaching method (HPAL method) or the like.

[0023] As described above, the "nickel oxide ore smelting method" is carried out in a smelting facility including a "leaching and solid-liquid separation plant", a "neutralization plant", a "zinc removal plant", and a "nickel recovery plant".

[0024] And the "nickel oxide ore smelting method" is an overall process of sequentially performing a "leaching step S1", a "solid-liquid separation step S2", a "neutralization step S3", a "zinc removal step S4", and a "nickel recovery step S5" in the above smelting facility as shown in FIG. 1.

[0025] The "Method for Smelting Nickel Oxide Ore" is an overall process that, among the above-mentioned processes, in the "Zinc Removal Step S4", the filter is operated by a unique "Operating Method of Filtration Equipment" different from the conventional method, and the zinc removal treatment is carried out by a unique "Zinc Removal Treatment Method" different from the conventional method. In the following, first, the flow of the overall process of the "Method for Smelting Nickel Oxide Ore" will be described, and then, the details of the "Operating Method of Filtration Equipment" and the "Zinc Removal Treatment Method" of the present invention will be explained.

[0026] [Leaching Step] The leaching step S1 is a step of performing a leaching treatment on the slurry of nickel oxide ore using a high-pressure acid leaching method or the like. In the leaching step S1, specifically, sulfuric acid is added to the ore slurry obtained by pulverizing the raw material nickel oxide ore, and the ore slurry is stirred by pressurizing under high-temperature conditions of 220°C or higher and 280°C or lower using a high-temperature pressure vessel (autoclave) to form a leaching slurry composed of a leaching solution and a leaching residue.

[0027] In the leaching treatment in the leaching step S1, for example, the leaching reactions and high-temperature thermal hydrolysis reactions represented by the following formulas (1) to (5) occur, and the leaching of nickel, cobalt, etc. as sulfates and the immobilization of the leached iron sulfate as hematite are carried out. However, since the immobilization of iron ions does not proceed completely, usually, the liquid part of the obtained leaching slurry contains divalent and trivalent iron ions in addition to nickel, cobalt, etc.

[0028] (Leaching Reaction) MO + H2SO4 → MSO4 + H2O ··· (1) (In the formula, M represents Ni, Co, Fe, Zn, Cu, Mg, Cr, Mn, etc.) 2Fe(OH)3 + 3H2SO4 → Fe2(SO4)3 + 6H2O ··· (2) FeO + H2SO4 → FeSO4 + H2O ··· (3) (High-Temperature Thermal Hydrolysis Reaction) 2FeSO4 + H2SO4 + 1 / 2O2 → Fe2(SO4)3 + H2O ··· (4) Fe2(SO4)3 + 3H2O → Fe2O3 + 3H2SO4 ···(5)

[0029] Further, in the leaching step S1, from the viewpoint of the filterability of the leaching residue containing hematite produced in the subsequent solid-liquid separation step S2, it is preferable to adjust the pH of the obtained leaching solution to 0.1 to 1.0.

[0030] [Solid-Liquid Separation Step] In the solid-liquid separation step S2, after mixing the leaching slurry formed in the leaching step S1 with a washing liquid, it is washed using a solid-liquid separation device such as a thickener to separate the residue, and a leaching solution containing zinc as an impurity element in addition to nickel and cobalt is obtained. In the solid-liquid separation step S2, specifically, first, the slurry is diluted by the washing liquid, and then the leaching residue in the slurry is concentrated as a sediment in the thickener. Thereby, the nickel content adhering to the leaching residue can be reduced according to the degree of dilution. In actual operation, by connecting thickeners having such functions in multiple stages and using them, the recovery rates of nickel and cobalt can be improved.

[0031] [Neutralization Step] The neutralization step S3 is a step of adjusting the pH of the leaching solution separated in the solid-liquid separation step S2, separating the neutralization precipitate containing impurity elements, and obtaining a neutralization final solution containing zinc together with nickel and cobalt. In the neutralization step S3, specifically, while suppressing the oxidation of the separated leaching solution, a neutralizing agent such as calcium carbonate is added to the leaching solution so that the pH of the obtained neutralization final solution is 4 or less, preferably 3.0 to 3.5, more preferably 3.1 to 3.2, to form a neutralization final solution that is the basis of the mother liquor for nickel recovery and a neutralization precipitate slurry containing trivalent iron as an impurity element. In the neutralization step S3, by performing the neutralization treatment on the leaching solution in this way, the excess acid used in the leaching treatment by the high-pressure acid leaching method is neutralized to generate a neutralization final solution that is the basis of the mother liquor for nickel recovery, and impurities such as trivalent iron ions and aluminum ions remaining in the solution are removed as neutralization precipitates.

[0032] In the neutralization process S3, it is preferable to leave a suspension composed of neutralization precipitate and the leaching residue obtained in the leaching process S1 in the neutralization final solution (sulfidation treatment starting solution) so that the turbidity of the neutralization final solution transferred to the zinc removal reaction tank in the subsequent zinc removal process S4 exceeds 0 NTU and is 100 NTU or less. By adjusting the turbidity of the neutralization final solution by leaving the suspension in this way, the filterability of the zinc removal sulfide formed in the zinc removal process S4 can be improved.

[0033] [Zinc removal process] The zinc removal process S4 is a process of adding a sulfiding agent such as hydrogen sulfide gas to the neutralization final solution obtained from the neutralization process S3 to perform a sulfidation treatment to generate zinc sulfide, and separating and removing the zinc sulfide to obtain a mother liquor for nickel recovery (zinc removal final solution) containing nickel and cobalt. In the zinc removal process S4, specifically, for example, a neutralization final solution containing zinc together with nickel and cobalt is introduced into a pressurized container, and hydrogen sulfide gas is blown into the gas phase to selectively sulfide zinc with respect to nickel and cobalt, generating zinc sulfide and a mother liquor for nickel recovery.

[0034] The zinc removal process S4 can be carried out in the above-mentioned "zinc removal plant". The "zinc removal plant" includes a "zinc removal reaction tank" for blowing a sulfiding agent such as hydrogen sulfide gas into the neutralization final solution to perform a sulfidation reaction, a "zinc removal final solution storage tank" for storing a slurry composed of the generated zinc sulfide and the sulfidation reaction final solution, and a filtration facility composed of a filter such as a "polishing filter" for separating and removing zinc sulfide precipitate (see the zinc removal process S4 in Figure 1). Among these, it is preferable that the "zinc removal final solution storage tank" is provided with a function for adjusting the flow rate of the slurry when feeding the slurry to the "filtration facility".

[0035] [Nickel recovery process] The nickel recovery step S5 uses the mother liquor for nickel recovery obtained through the dezincification step S4 as the starting solution, and causes a sulfidation reaction by blowing a sulfiding agent such as hydrogen sulfide gas into the starting solution, producing sulfides of nickel and cobalt with few impurity components (nickel-cobalt mixed sulfide) and a lean solution (sulfidation final solution) with the concentrations of nickel and cobalt stabilized at a low level. Note that the mother liquor for nickel recovery is an aqueous sulfuric acid solution containing nickel and cobalt. In the nickel recovery step S5, nickel and cobalt contained in the starting solution are immobilized and recovered as sulfides through a sulfidation treatment using a sulfidation reaction tank or the like. After the sulfidation reaction is completed, the resulting slurry containing the nickel-cobalt mixed sulfide is charged into a sedimentation separation device such as a thickener for sedimentation separation treatment, and only the sulfide is separated and recovered from the bottom of the thickener. On the other hand, the aqueous solution component is overflowed from the upper part of the thickener and recovered as a lean solution.

[0036] <Dezincification treatment method> The "dezincification treatment method" of the present invention (hereinafter, also simply referred to as the "dezincification treatment method") is a treatment method that can be used to perform the "dezincification step S4" among the above-mentioned respective processes (S1 to S5) performed in the "smelting method of nickel oxide ore". And this "dezincification treatment method" is a treatment method that performs a dezincification treatment for separating and removing zinc sulfide in the slurry by solid-liquid separation treatment by the "operation method of filtration equipment" of the present invention described in detail below.

[0037] <Operation method of filtration equipment> The "operation method of filtration equipment" of the present invention (hereinafter, also simply referred to as the "operation method of filtration equipment") is an operation method for an filtration equipment composed of a plurality of filters connected in parallel.

[0038] [Filtration equipment] As an example of the "filtration equipment" which is the object of implementation of the "operation method of filtration equipment" of the present invention, as shown in Fig. 2, a filtration equipment 10 in which three filters 13, 23, and 33 are connected in parallel can be cited.

[0039] Each of the filters 13, 23, and 33 that make up the filtration equipment 10 performs a solid-liquid separation process on the slurry as the object to be treated, and it may be a filter having a filter cloth with a predetermined mesh size, but it is preferably a "polishing filter" which is a closed-type filter.

[0040] The filtration equipment 10 is provided with a "slurry distribution mechanism" that can individually control the supply flow rate of the slurry distributed to each of the filters 13, 23, and 33 connected in parallel. Thereby, the "operation method of the filtration equipment" can be implemented in the said equipment. This "slurry distribution mechanism" can individually control the supply flow rate of the slurry distributed to each of the filters 13, 23, and 33 when performing the "start-up operation" of the filtration equipment 10, which is performed after the backwashing operation described later, etc., for each of the filters.

[0041] The above-mentioned "slurry distribution mechanism" is not limited to a specific mechanism as long as it can individually control the supply flow rate of the slurry distributed to each of the filters 13, 23, and 33 connected in parallel. As an example of its preferred configuration, as shown in FIG. 2, the liquid supply pipe of the slurry sent from the slurry tank (dezincified final liquid storage tank) 1 branches into three, and the filters 13, 23, and 33 are connected to the respective branch pipes 11, 21, and 31, and a configuration in which primary side valves 14, 24, and 34 are provided as the primary side pipes of each filter and secondary side valves 15, 25, and 35 are provided as the secondary side pipes can be cited.

[0042] The material of the filter cloth provided in the filters 13, 23, and 33 is not particularly limited, but it is preferably a polypropylene filter cloth capable of achieving a permeate flux of 0.5 m 3 / hr·m 2 or more and 3.0 m 3 / hr·m 2 or less. Also, the filtration area (filterable area) in the filters 13, 23, and 33 is not particularly limited either, and it can be appropriately set according to the flow rate of the target slurry, etc., but generally it is preferably 10 m 2 or more and 30 m 2 or less.

[0043] In the filtration equipment 10, solid matter is separated by each of the filters 13, 23, and 33, and the final solution of the sulfidation reaction discharged as filtrate from each filter is sent to the filtrate tank 2.

[0044] [Operating method of filtration equipment] Here, in the filtration equipment 10, during operation, clogging may occur in the filter cloths of the filters 13, 23, and 33. When clogging occurs in the filter cloth of any of the filters, for the corresponding filter, a backwash liquid such as warm water supplied from the backwash unit 40 (see Fig. 2) is supplied through the backwash liquid supply piping system 41 (see Fig. 2), and by flowing the backwash liquid in a direction opposite to the normal liquid flow direction (i.e., from the secondary side to the primary side), the wet cake composed of fine particles causing the clogging is peeled off and washed away. The cake peeled off by this backwash is discharged out of the system through the backwash drainage discharge piping system 42 (see Fig. 2) together with the washing drainage. This backwash operation is generally performed after stopping the operation of the entire dezincification plant (start-up of the plant) and draining the liquid. Then, after subsequent inspection and "start-up operation" of the plant, it returns to normal operation.

[0045] (Operating method of conventional filter) When performing the "start-up operation" of the dezincification plant as described above, in order to form a cake layer by coating a predetermined amount of zinc precipitate on the surface of the filter cloth by sending the slurry after dezincification treatment to the filter, the operation of the filter is carried out in such a manner that the flow rate of the slurry is gradually increased within a predetermined time and adjusted to the target flow rate (see Patent Document 1).

[0046] Specifically, for the adjustment of the flow rate to gradually increase the flow rate of the above slurry, as shown in FIG. 3, when the liquid feed pump for feeding the slurry is operated at the maximum flow rate increase rate, if the time from the start of slurry supply to reaching the target slurry flow rate is set as T1, it is preferable to adjust the flow rate of the slurry supplied to the filter press to gradually increase to the target slurry flow rate at a time T2 that satisfies the following relational expression (i). 3×T1≦T2≦5×T1···(i) Here, the time T1 from the start of slurry supply to reaching the target slurry flow rate when the liquid feed pump is operated at the maximum flow rate increase rate is the time until the end of the startup operation (start of normal operation) shown in the graph of FIG. 4. Also, the "stepwise" in the stepwise increase adjustment refers to an adjustment state in which a plurality of sets (multiple steps) are implemented at predetermined time intervals with one set of the "flow rate increase step" and the "flow rate maintenance step" shown in the graph of FIG. 3.

[0047] More specifically, first, as the first step, immediately after the start of the startup operation, set the flow rate of the liquid feed pump to the maximum flow rate increase rate and perform an operation to increase the flow rate of the slurry for a certain period of time (the circled part X in FIG. 3). That is, adjust the flow rate so that the slope of the slurry flow rate with respect to the required time immediately after the start of the startup operation in the graph of FIG. 3 is the same as the slope of the slurry flow rate increase with respect to the required time from immediately after the start of the startup operation in the graph of FIG. 4. Next, as the second step, after that certain period of time has elapsed, operate the liquid feed pump to maintain the flow rate at that time for a predetermined period of time to adjust the flow rate (the circled part Y in FIG. 3). Then, by repeating this first step (X) and the second step (Y) as one set (step) at predetermined time intervals, the flow rate of the slurry can be adjusted to gradually increase. In this way, the flow rate of the slurry is gradually increased, and when the flow rate of the slurry reaches the slurry flow rate (target flow rate) during normal operation, the pump operation is adjusted to maintain the flow rate of the slurry. In addition, it is more preferable to adjust the flow rate of the slurry to gradually increase in 3 to 6 steps.

[0048] Furthermore, the control of the liquid feed pumps in the above-described first and second steps can be easily carried out, for example, by inverter-controlling the power supplied to the pumps. Also, the cake layer formed in this way is a cake layer formed such that fine particles (zinc-depleted precipitate so small that it cannot be completely separated by solid-liquid separation) slowly adhere to the surface of the filter cloth to create small gaps that serve as flow paths for liquid passage, and moreover, it is a cake layer that has grown to a thickness that does not break even at the flow rate (target flow rate) during normal operation.

[0049] (“Operation Method of Filter Press” of the Present Invention) When the inventor of the present invention implements the above-described “conventional operation method” in a “filtration facility” in which a plurality of filter presses are connected in parallel as illustrated in FIG. 2, by controlling the distribution of the slurry to each filter press based on a specific distribution rule unique to the present invention, when performing the startup operation of the “filtration facility” in which a plurality of filter presses are connected in parallel, the flow rate of the slurry to each filter press is increased at an earlier stage to form a cake layer earlier, and as a result, it has been found that the zinc removal rate can be improved. This is presumably because a cementation reaction occurs between the metal elements in the cake layer and the zinc ions contained in the slurry, so by forming the cake layer at an earlier stage, more zinc can be removed accordingly.

[0050] For example, FIG. 5 is a diagram showing the relationship between the integrated liquid passage amount of the slurry passing through the “filter press” and the zinc removal rate. In the case of this filter press, from where the total liquid passage amount exceeds 500 m 3 and up to about 800 m 3 , the zinc removal rate increases rapidly. Therefore, when performing the startup operation of the filtration facility, when passing the slurry through this filter press, the flow rate of the slurry to the filter press is increased at an earlier stage so as to exceed 800 m 3 as soon as possible and the target flow rate is reached, then more zinc can be removed accordingly.

[0051] The "filtration equipment" to which the present invention is applied is, for example, three filters connected in parallel. In this case, by adjusting the opening degree of the primary side valve connected to each filter, the flow rate of the slurry supplied to each filter can be adjusted. That is, in this "filtration equipment", for each filter, by adjusting the opening degree of the primary side valve, the slurry supplied to the filtration equipment can be distributed to each filter at an arbitrary and appropriate ratio.

[0052] According to the "operation method of filtration equipment" of the present invention, when performing the startup operation of the "filtration equipment", at each stage where the supply flow rate of the slurry supplied to the "filtration equipment" increases so that the cake layer is formed at an earlier stage, by individually adjusting the opening degree of the valve installed in each filter, in the "filtration equipment" where a plurality of filters are connected in parallel, the separation and recovery rate of the solid content from the slurry can be improved.

[0053] The "operation method of filtration equipment" of the present invention distributes the slurry to each filter in the following manner when performing the startup operation of the "filtration equipment" composed of a plurality of filters connected in parallel so that the cake layer is formed at an earlier stage. That is, when the total supply flow rate of the slurry to the "filtration equipment" is less than 50% of the target flow rate of the filter with the smallest target flow rate, the slurry is supplied only to the filter with the smallest target flow rate. Also, when the total supply flow rate of the slurry to the "filtration equipment" is 50% or more of the target flow rate of the filter with the smallest target flow rate, the supply flow rate of the slurry distributed to each filter is individually controlled so that the supply flow rate of the slurry distributed to each filter does not become less than 50% of the target flow rate of each filter.

[0054] Furthermore, the supply flow rate of the slurry distributed to each filter during the startup operation of the filtration equipment in the "operation method of filtration equipment" of the present invention is more preferably controlled based on the distribution rules (i), (ii), and (iii) shown in Table 1 below as an example.

[0055]

Table 1

[0056] Moreover, when multiple filters with equal target flow rates meet the criteria of "the filter with the largest target flow rate among the filters capable of supplying at a flow rate of 50% or more of the target flow rate" in Rule (ii), the slurry may be preferentially supplied to any one of them.

[0057] In addition, the "preferential" supply of slurry to the "specific filter" (the one with the largest target flow rate) in Rule (ii) does not necessarily mean supplying the entire amount of slurry supplied to the filtration equipment only to the "specific filter". As shown in the latter part of Rule (ii), as long as it is possible to supply at a flow rate of 50% or more of the target flow rate of each filter in all the filters to which the slurry is supplied, an appropriate amount of slurry can also be supplied to other filters other than the above-mentioned "specific filter" to which the slurry is preferentially supplied.

[0058] When "gradually increasing the slurry supply flow rate to each filter" in accordance with Rule (iii), the slurry flow rate in the "flow rate maintenance step" is adjusted so as to satisfy the conditions regarding the slurry supply flow rate defined in Rules (i) and (ii).

[0059] In addition, usually, since the target flow rate for each filter is set to about 80% of the maximum processing flow rate of each filter, in this case, as described above, in order to ensure a flow rate of 50% or more of the target flow rate, the maximum processing flow rate may be adopted as an alternative index, and the flow rate of the slurry distributed to each filter may be controlled so as to ensure a flow rate of 65% or more thereof.

[0060] As an example, as shown in FIG. 2, in a filtration equipment 10 in which three filters 13, 23, and 33 are connected in parallel and the target flow rate and the maximum processing flow rate of each filter are as shown in Table 2 below, the distribution of the slurry can be specifically performed in the control modes exemplified in the following paragraphs

[0060] to

[0070] .

[0061]

Table 2

[0062] (When the total supply flow rate of the slurry is less than 50 m 3 / h) Immediately after the start of the startup operation, etc., when the total supply flow rate of the slurry supplied to the filtration facility 10 is less than 50% of the target flow rate (100 m 3 / h) of the filter (filter 13) with the smallest target flow rate, for example, 40 m 3 / h, the slurry is supplied only to the filter (filter 13) with the smallest target flow rate (rule i).

[0063] As a specific operation of the "slurry distribution mechanism" in this case, with the primary side valves 24 and 34 of the filters 23 and 33 closed, the primary side valve 14 of the filter 13 is opened so that the slurry is supplied only to the filter 13. By this operation, the total amount of the slurry supplied to the filtration facility 10 can be concentrated on the filter 13. Therefore, compared with the case of evenly distributing it to the three filtration units while forming a good cake layer, the flow rate of the slurry in the filter 13 can reach the target flow rate earlier.

[0064] (When the total supply flow rate of the slurry is 50 m 3 / h or more and less than 100 m 3 / h) After the start of the startup operation, when the total supply flow rate of the slurry supplied to the filtration facility 10 becomes 50% or more of the target flow rate (100 m 3 / h) of the filter (filter 13) with the smallest target flow rate, for example, 90 m 3 / h, in this case as well, still, the only filter that can be supplied at a flow rate of 50% or more of the target flow rate is the filter 13. Therefore, the slurry is supplied only to the filter 13 as described above (rule ii).

[0065] (When the total supply flow rate of the slurry is 100 m 3 / h or more and 200 m3 (when it is less than / h) Continue the startup operation, and when the total supply flow rate of the slurry supplied to the filtration equipment reaches 50% or more of the target flow rate (200 m 3 / h) of the filters 23 and 33 (for example, 150 m 3 / h), supply the slurry preferentially to the filter (filter 23) with the largest target flow rate among the filters capable of supplying at a flow rate of 50% or more of the target flow rate (rule ii). As described above, when the target flow rates of filter 23 and filter 33 are the same, there is no particular limitation on which filter to give priority to for supplying the slurry, and any one of the filters can be arbitrarily selected.

[0066] As a specific operation of the "slurry distribution mechanism" in this case, with the primary side valves 14 and 34 of filter 13 and filter 33 closed, open the primary side valve 24 of filter 23 so that the slurry is supplied only to filter 23. By this operation, the total amount of slurry supplied to the filtration equipment 10 can be concentrated on filter 23, and the flow rate of the slurry supplied to filter 23 can also be maintained at 50% or more of the target flow rate of filter 23. Therefore, while forming a good cake layer, compared with the case of evenly distributing it to the three filtration units, the flow rate of the slurry in filter 23 can reach the target flow rate faster.

[0067] In addition, as described above, when the total supply amount of the slurry to the filtration equipment reaches or exceeds the total flow rate of 50% of the target flow rate of the "filter 13 with the smallest target flow rate" and 50% of the target flow rate of the "other filter 23", in all filters, as long as it is possible to supply at a flow rate of 50% or more of the target flow rate, the slurry may be supplied to the filters other than the "filter 23 to which the slurry is preferentially supplied".

[0068] (when the total supply flow rate of the slurry is 200 m 3 / h or more and less than 250 m 3 / h) Continue the startup operation, and when the total supply flow rate of the slurry supplied to the filtration equipment can supply a flow rate of 50% or more of the target flow rate of each filtration machine to a plurality of filtration machines including the filtration machine that preferentially supplies the slurry (for example, 200 m 3 ), then, in all the filtration machines that supply the slurry, as long as it is possible to supply at a flow rate of 50% or more of the target flow rate of each filtration machine, supply the slurry to the filtration machine 13 other than the filtration machine 23 that preferentially supplies the slurry as well (the latter part of Rule ii).

[0069] As a specific operation of the "slurry distribution mechanism" in this case, in addition to the primary side valve 24 of the filtration machine 23, with the primary side valve 34 of the filtration machine 33 closed, further open the primary side valve 14 of the filtration machine 13, and adjust the opening degrees of the opened primary side valves 14 and 24 so that the flow rate of the slurry supplied to the filtration machine 13 is 50% or more of the target flow rate (100 m 3 / h) (for example, 50 m 3 / h), and while ensuring that the flow rate of the slurry supplied to the filtration machine 23 is also 50% or more of the target flow rate (200 m 3 / h) (for example, 150 m 3 / h). By this operation, while distributing the slurry supplied to the filtration equipment 10 to the filtration machine 13 and the filtration machine 23, and maintaining the flow rate of the slurry supplied to both filtration machines at 50% or more of the target flow rate of each filtration machine, it is also possible to reach the target flow rate of the slurry of the filtration machines 13 and 23 earlier than in the case of evenly dispersing it to the three filtration units while forming a good cake layer.

[0070] (When the total supply flow rate of the slurry is 250 m 3 / h or more and less than 300 m 3 / h) Continue the startup operation, and when the total supply flow rate of the slurry supplied to the filtration equipment can supply an even larger flow rate of 50% or more of the target flow rate of each filtration machine to a plurality of filtration machines including the filtration machine that preferentially supplies the slurry (for example, 250 m 3Even when this occurs, as long as it is possible to supply slurry at a flow rate of 50% or more of the target flow rate for each filter in all the filters to which the slurry is supplied, the slurry is preferentially supplied to filters 13 other than filter 23 that supplies the slurry (the latter part of rule ii).

[0071] As a specific operation of the "slurry distribution mechanism" in this case, with the primary side valve 34 of filter 33 closed, the primary side valves 24 of filter 23 and 14 of filter 13 are continuously opened, and the opening degrees of the opened primary side valves 14 and 24 are adjusted so that the flow rate of the slurry supplied to filter 13 is 50% or more of the target flow rate (100 m 3 / h) (for example, 100 m 3 / h), and while ensuring that the flow rate of the slurry supplied to filter 23 is also 50% or more of the target flow rate (200 m 3 / h) (for example, 150 m 3 / h). By this operation, while distributing the slurry supplied to the filtration facility 10 to filter 13 and filter 23, and maintaining the flow rate of the slurry supplied to both filters at 50% or more of the target flow rate of each filter, it is possible to reach the target flow rate of the slurry of filter 23 earlier than in the case of evenly dispersing it among the three filtration units while forming a good cake layer.

[0072] (When the total supply flow rate of the slurry is 300 m 3 / h or more) Continue the start-up operation further. When the total supply flow rate of the slurry supplied to the filtration facility reaches a larger flow rate (for example, 400 m 3 ) that can supply a flow rate of 50% or more of the target flow rate of each filter to a plurality of filters including the filter that preferentially supplies the slurry, in all the filters that supply the slurry, as long as it is possible to supply at a flow rate of 50% or more of the target flow rate of each filter, the slurry is supplied to filters 13 and 33 other than filter 23 that preferentially supplies the slurry (the latter part of rule ii).

[0073] In the specific operation of the "slurry distribution mechanism" in this case, open the primary side valves 14, 24, and 34 of all the filters 13, 23, and 33, and adjust the opening degrees of the opened primary side valves 14, 24, and 34 to make the flow rate of the slurry supplied to the filter 13 reach 50% or more of the target flow rate (100 m 3 / h) (for example, 100 m 3 / h), and also ensure that the flow rate of the slurry supplied to the filters 23 and 33 reaches 50% or more of the target flow rate (200 m 3 / h) (for example, 150 m 3 / h) respectively. By this operation, while distributing the slurry supplied to the filtration equipment 10 to the filters 13, 23, and 33, the flow rate of the slurry supplied to all the filters can also be maintained at 50% or more of the target flow rate of each filter. Therefore, compared with the case of evenly dispersing to the three filtration units while forming a good cake layer, the flow rate of the slurry in the filters 13, 23, and 33 can reach the target flow rate faster.

Example

[0074] Next, an example to which the present invention is applied will be described, but the present invention is not limited to the following examples at all. In this example, in the wet smelting of nickel oxide ore in a dezincking plant, after regular inspection, when starting up this dezincking plant, a "filtration equipment" for performing a dezincking treatment to separate and remove zinc sulfide in the slurry by solid-liquid separation treatment was operated by the "operation method of filtration equipment" of the present invention, and the improvement effect of the filtration rate was verified.

[0075] (Example) By the "operation method of filtration equipment" of the present invention, the start-up operation of the "filtration equipment" was carried out, and then a test operation for 4 months (from September 2020 to December 2020) including the start-up operation period (2 days) was implemented. During the start-up operation, the primary side valves 14, 24, and 34 were controlled under the same control conditions as those exemplified in the above paragraphs

[0058] to

[0070] to adjust the flow rate of the slurry distributed to each filter.

[0076] (Comparative Example) As usual, the start-up operation of the "filtration equipment" was carried out by always dispersing an equal amount of slurry into each filter, and then, a test operation for 8 months (from January 2020 to August 2020) including the start-up operation period (2 days) was implemented.

[0077] (Verification of effects) Regarding the examples, comparative examples, and each test operation, when the zinc grade in the leachate containing nickel and cobalt as the final solution exceeded the specified value, it was evaluated as "defective", and the "defective rate" was obtained. The results were as shown in Table 3.

[0078]

Table 3

[0079] As shown in Table 3, it was confirmed that by performing the "start-up operation" of the "filtration equipment" for zinc removal treatment according to the "operation method of filtration equipment" of the present invention, the occurrence of defects related to the filtration treatment can be suppressed to 1 / 3.

Explanation of symbols

[0080] 1 Slurry tank (zinc removal final solution storage tank) 10 Filtration equipment 11, 21, 31 Branch pipes 13, 23, 33 Filters (polishing filters) 14, 24, 34 Primary side valves 15, 25, 35 Secondary side valves 40 Backwashing unit 41 Backwashing liquid supply piping system 42 Backwashing drainage discharge piping system 2 Filtrate tank S1 Leaching process S2 Solid-liquid separation process S3 Neutralization process S4 Zinc removal process S5 Nickel recovery process

Claims

1. A method for operating a filtration facility comprising a plurality of filters connected in parallel, wherein the filtration facility is used in a de-zinc plant for nickel smelting treatment by an acid leaching method, when starting up the filtration facility, if the total supply flow rate of the slurry to the filtration facility is less than 50% of the target flow rate of the filter with the smallest target flow rate, the slurry is supplied only to the filter with the smallest target flow rate, if the total supply flow rate of the slurry to the filtration facility is 50% or more of the target flow rate of the filter with the smallest target flow rate, the supply flow rate of the slurry distributed to each filter is individually controlled so that the supply flow rate of the slurry distributed to each filter does not become less than 50% of the target flow rate of each filter, A method for operating a filtration facility.

2. Controlling the supply flow rate of the slurry distributed to each filter based on the following distribution rules (i), (ii) and (iii), The method for operating a filtration facility according to Claim 1. (i) When the total supply flow rate of the slurry to the filtration facility is less than 50% of the target flow rate of the filter with the smallest target flow rate, the slurry is supplied only to the filter with the smallest target flow rate. (ii) When the total supply flow rate of the slurry to the filtration facility is 50% or more of the target flow rate of the filter with the smallest target flow rate, in all the filters to which the slurry is supplied, as long as it is possible to supply at a flow rate of 50% or more of the target flow rate of each filter, the slurry is preferentially supplied to the filter with the largest target flow rate among the filters capable of supplying at a flow rate of 50% or more of the target flow rate. However, in all the filters to which the slurry is supplied, as long as it is possible to supply at a flow rate of 50% or more of the target flow rate of each filter, an appropriate amount of slurry can also be supplied to the other filters other than the filter to which the slurry is preferentially supplied. (iii) The flow rate of the slurry supplied to all the filters is gradually increased step by step until the target flow rate of each filter is reached for each filter. Here, "step by step" means a state of adjusting the flow rate of the slurry in which a "flow rate increase step" and a "flow rate maintenance step" of increasing the flow rate with the maximum capacity of the pump for feeding the slurry are set as one set and a plurality of sets (a plurality of steps) are implemented at predetermined time intervals.

3. The zinc removal treatment for separating and removing zinc sulfide in the slurry by solid-liquid separation treatment is carried out by the operation method of the filtration equipment according to claim 1 or 2. Zinc removal treatment method.

4. The slurry is a slurry obtained by subjecting a neutralization final solution containing zinc together with nickel and cobalt obtained by neutralizing a leachate of the nickel oxide ore in a wet smelting method of the nickel oxide ore to a sulfidation treatment to form zinc sulfide. The zinc removal treatment for separating and removing the zinc sulfide is carried out by the zinc removal treatment method according to claim 3. Smelting method of nickel oxide ore.

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