JP2023149014A - Tool for measuring liquid level in reaction vessel and method for measuring liquid level of reactor vessel - Google Patents

Abstract

To make an accurate measurement of a liquid level even if the level of liquid in a reaction vessel is not larger than a specific level when a regular resting repair, for example, is performed for the reaction vessel such as autoclaving to perform a high-pressure acid transudation in a nickel oxidation ore.SOLUTION: A liquid level measurement tool 1 includes a bar-like column 11 and a plurality of liquid collecting containers 12. The liquid collecting containers 12 are set at regular intervals in a side surface of the column 11 along the direction of the center axis of the column 11, with opening parts 121 of all of the liquid collecting containers 12 being directed to the upper part of the column 11, within the range of the column 11 which is on the lower terminal 111 side and the lower side of the column 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a liquid level measuring device for a reaction tank and a method for measuring the liquid level of a reaction tank. Specifically, the present invention provides a liquid level for a reaction tank that is suitable for measuring the liquid level of a large reaction tank that processes high-temperature, strongly acidic slurry, such as an autoclave used for high-pressure acid leaching treatment of nickel oxide ore. The present invention relates to a measuring device and a method for measuring the liquid level in a reaction tank.

As a hydrometallurgical method for nickel oxide ore, a high-pressure acid leaching method (HPAL method) is known that uses an oblong autoclave (see FIG. 4) in which a substantially cylindrical pressure vessel is turned sideways (see Patent Document 1). ). As shown in FIG. 4, the inside of the autoclave 2 is divided into a plurality of storage sections 21 (21A to 21F) continuous in the longitudinal direction by a weir having a slurry passage port that can be opened and closed, and charged with sulfuric acid. The slurry of nickel oxide ore is sequentially transferred from the upstream side to the downstream side of the plurality of storage sections 21 (21A to 21F) while overflowing the weir, but some of it passes through the liquid passage port. By doing so, it is transferred to the downstream side. After high-pressure acid leaching is performed in each storage section inside the autoclave, the slurry that has reached the most downstream storage section 21F is extracted via the extraction pipe 22 hanging from the top of the autoclave. It will be done. The amount of slurry extracted through this extraction pipe is adjusted according to the liquid level height (hereinafter also referred to as "liquid level") of the slurry in the storage section on the most downstream side.

Here, in a large reaction tank such as the autoclave 2 described above, periodic shutdown repairs are performed. During this shutdown repair, after the entire amount of liquid inside the autoclave is discharged, the manhole 23 at the bottom is opened, and the autoclave is entered inside to perform various repair work. When opening the manhole 23 at the bottom, if there is a pool of liquid inside, there is a safety risk due to the high temperature and strong acid liquid scattering around, and there is a risk of high temperature and strong acid liquid leaking outside the liquid barrier at the bottom of the autoclave. Before opening the bottom manhole, it is important to confirm that there are no remaining liquids inside, as there is a risk of environmental risks arising from the leakage of strongly acidic liquids.

In recent years, radiation level measuring instruments that can stably measure the liquid level even under high temperature and high pressure have been widely used to measure the liquid level in an autoclave (see Patent Document 2). This radiation level measuring device has a radiation source and a receiver placed opposite each other across the autoclave, and detects and measures the number of radiation counts that increase or decrease depending on the level of liquid in the autoclave. It is converted to liquid level.

As shown in FIG. 6(b), the radiation level measuring device described above detects radiation emitted from the radiation source section 31 during normal operation when the liquid level inside the reaction tank 3 is above a certain level. From the radiation dose detected in the section 32, the amount of slurry in the tank can be accurately measured. However, when the liquid level inside the reaction tank 3 drops below a certain level, as before and after the shutdown repair described above, accurate liquid level measurement cannot be performed (see Figure 6(a)). reference).

Japanese Patent Application Publication No. 2014-025143 Japanese Patent Application Publication No. 2017-146221

The present invention can be used even when the liquid level inside the reaction tank is low below a certain level, such as during periodic shutdown repairs in a reaction tank such as an autoclave that performs high-pressure acid leaching treatment of nickel oxide ore. An object of the present invention is to provide a liquid level measuring device that can accurately measure the liquid level.

The present inventor came to the idea that the above problem could be solved by a liquid level measuring device that includes a rod-shaped support and a plurality of liquid collection containers, and completed the present invention. Specifically, the present invention provides the following.

(1) A liquid level measuring device for a reaction tank, comprising a rod-shaped support and a plurality of liquid collection containers, wherein the plurality of liquid collection containers are located at the bottom end of the support and one near the bottom side. All of the liquid collection containers are installed at regular intervals on the side surface of the support along the central axis of the support, with the openings of all the liquid collection containers facing toward the upper side of the support. , liquid level measuring instrument.

According to the liquid level measuring device (1), the liquid level can be accurately measured even when the liquid level inside the reaction tank is low below a certain level.

(2) The liquid level measuring device according to (1), wherein a hanging rope is connected to the top end of the support.

According to the liquid level measuring device (2), by setting the length of the support to a length that is easy to handle (about 2 to 3 m as an example), and optimizing the rope length appropriately, it can be used in autoclaves, etc. In reaction tanks of various sizes, including large reaction tanks, the liquid level can be accurately measured even when the liquid level inside the reaction tank is below a certain level.

(3) Both the liquid collection container and the pillar are made of an acid-resistant resin selected from polyvinyl chloride, polyethylene, polypropylene, polystyrene, ABS resin, acrylic resin, polyvinylidene fluoride, and phenolic resin. ) The liquid level measuring device described in ).

According to the liquid level measuring device (3), by configuring the collection container and support with each of the above-mentioned resins that are lightweight and have excellent acid resistance, even when the slurry to be measured is strongly acidic, The ease of handling the liquid level measuring device described in (1) or (2), the durability of the device, and the safety of the measuring operation can be achieved at a high level.

(4) The liquid level measurement according to (2), wherein the hanging rope is made of an acid-resistant resin selected from polyvinyl chloride, polyethylene, polypropylene, polystyrene, ABS resin, acrylic resin, polyvinylidene fluoride, and phenol resin. utensils.

According to the liquid level measuring device (4), the rope, collection container, and support are made of the above-mentioned resins that are lightweight and have excellent acid resistance, so that the slurry to be measured is strongly acidic. In this case, the ease of handling the liquid level measuring device described in (2), the durability of the device, and the safety of the measuring operation can be achieved at a high level.

(5) A method for measuring the liquid level in a reaction tank, wherein the liquid level measuring device according to any one of (1) to (4) is inserted vertically into the reaction tank, and the liquid level is measured at the lower side of the support. A method for measuring the liquid level in a reaction tank, in which the end is brought into contact with the bottom of the reaction tank and then pulled up.

According to the liquid level measuring method (5), even when the liquid level inside the reaction tank is low below a certain level, the liquid level can be accurately measured.

(6) A method for measuring the liquid level in an autoclave used for high-pressure acid leaching treatment of nickel oxide ore, comprising inserting the liquid level measuring device according to (3) or (4) into the autoclave along the vertical direction, A method for measuring a liquid level in an autoclave, in which the lower end of the support is brought into contact with the bottom of the autoclave and then pulled up.

According to the liquid level measurement method (6), in an autoclave where the slurry to be measured is strongly acidic, even when the liquid level inside the autoclave is below a certain level, the liquid level can be measured safely and accurately. It is possible to perform position measurements.

According to the present invention, the liquid level inside the reaction tank is at a low level below a certain level, such as during periodic shutdown repair in a reaction tank such as an autoclave that performs high-pressure acid leaching treatment of nickel oxide ore. It is also possible to accurately measure the liquid level.

FIG. 2 is a side view of the liquid level measuring instrument of the present invention. FIG. 2 is a partially enlarged perspective view for explaining the configuration of the main parts of the liquid level measuring instrument of the present invention. FIG. 3 is a drawing for explaining the arrangement pitch of liquid collection containers in the liquid level measuring device of the present invention. 1 is a longitudinal cross-sectional view of an autoclave to which the liquid level measuring device and liquid level measuring method of the present invention are preferably applied. FIG. 5 is a general process flow diagram of a hydrometallurgical process for nickel oxide ore in which the leaching step using the autoclave of FIG. 4 is performed. 1 is a drawing schematically showing an operation mode of a conventionally known radiation type level measuring device.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. The liquid level measuring device and liquid level measuring method of the present invention are technical means for measuring the liquid level of a liquid phase accommodated inside various industrial reaction vessels. The present invention can be particularly preferably used for measuring the liquid level of a slurry in an autoclave used in a leaching step in a hydrometallurgical process for nickel oxide ore using high-pressure acid leaching treatment.

Below, details will be explained about an embodiment in which the liquid level measuring device and the liquid level measuring method of the present invention are used to measure the liquid level of slurry in an autoclave used in a hydrometallurgical process of nickel oxide ore. do. However, the application of the present invention is not limited to the above-mentioned autoclave, and can be used to measure the liquid level of various reaction vessels while making appropriate changes within the scope of the purpose of the present invention. In the following, first, an overview of the hydrometallurgical process of nickel oxide ore by high-pressure acid leaching using an autoclave, which is a preferred application target of the present invention, will be explained, and then the liquid level measurement of the present invention will be explained. The equipment and liquid level measurement method will be explained in detail.

<Hydrometallurgical process of nickel oxide ore>
As shown in Figure 5, the hydrometallurgical smelting process for nickel oxide ore is a leaching process in which sulfuric acid is added to a slurry of nickel oxide ore (hereinafter simply referred to as "ore slurry") as a raw material, and leaching is performed under high temperature and pressure. S1: Solid-liquid separation step S2: solid-liquid separation of the obtained leaching slurry into a leaching solution and leaching residue while washing the obtained leaching slurry in multiple stages; adding a neutralizing agent to the obtained leaching solution to adjust the pH to contain impurity elements; Neutralization step S3 of separating the neutralized precipitate in the form of a slurry to obtain a neutralized final solution containing nickel and cobalt, and adding a sulfiding agent to the obtained neutralized final solution to produce a mixed sulfide of nickel and cobalt. The sulfiding step S4 to generate is a process that is performed sequentially.

[Leaching process]
The leaching step S1 is a step in which an ore slurry containing nickel and cobalt is charged into an autoclave, which is a pressurized reaction vessel, together with an acid such as sulfuric acid, and subjected to leaching treatment.

In the leaching step S1, first, ore slurry to be treated is charged into a heater tank made of, for example, a pressure-resistant container via a pump, and high-pressure steam or the like is blown into the heater tank to bring the ore slurry to a desired high temperature and high pressure. Raise the temperature and pressure to the desired conditions. Next, the ore slurry adjusted to desired high-temperature and high-pressure conditions is charged into an autoclave 2 (see FIG. 4), which is a pressure-resistant container equipped with a stirrer. Excess sulfuric acid is added to the ore slurry charged into the autoclave 2, and high pressure steam is blown into the ore slurry. As a result, the ore slurry is subjected to acid treatment while being stirred under high temperature and high pressure, and metals such as nickel and cobalt contained in the ore are leached out. As a result, a leaching slurry consisting of a leaching liquid containing nickel and cobalt and a leaching residue containing hematite and the like is produced.

In the above leaching treatment in the autoclave, for example, leaching reactions of formulas 1 to 3 below and high-temperature hydrolysis reactions of formulas 4 to 5 below occur, resulting in leaching of nickel, cobalt, etc. as sulfates, and leached iron sulfate. is immobilized as hematite.
(Formula 1)
MO+ _{H2SO4 ⇒MSO4 + H2O}
(In the formula, M represents Ni, Co, Fe, Zn, Cu, Mg, Cr, Mn, etc.)
(Formula 2)
2Fe(OH) ₃ +3H ₂ SO ₄ ⇒Fe ₂ (SO ₄ ) ₃ +6H ₂ O
(Formula 3)
FeO+ _{H2SO4 ⇒FeSO4 + H2O}
(Formula 4)
2FeSO ₄ +H ₂ SO ₄ +1/2O ₂ ⇒Fe ₂ (SO ₄ ) ₃ +H ₂ O
(Formula 5)
Fe ₂ (SO ₄ ) ₃ +3H ₂ O⇒Fe ₂ O ₃ +3H ₂ SO ₄

Although there is no particular limitation on the amount of sulfuric acid added in the leaching step S1, it is preferable to add it in excess so that the iron in the ore is leached out. Specifically, it is preferable to adjust the amount of sulfuric acid added so that the pH of the obtained leachate is 0.1 to 1.0. As a result, a leaching slurry is produced, which is composed of a leaching liquid containing nickel and cobalt together with impurity components, and a leaching residue containing hematite and the like. The obtained leaching slurry is subjected to preliminary neutralization treatment to partially neutralize excess sulfuric acid that did not participate in the leaching reaction, before performing solid-liquid separation treatment in the next solid-liquid separation step S2. is preferred. As for the conditions for this preliminary neutralization treatment, it is preferable to add a neutralizing agent so that the pH of the leaching slurry is approximately 2.8 to 3.2, for example.

[Solid-liquid separation process]
In the solid-liquid separation step S2, the leaching slurry obtained in the leaching step S1 is introduced into a solid-liquid separation means such as a sedimentation separator to perform multi-stage cleaning and leaching of the leachate containing valuable metals such as nickel and cobalt. This is a step of performing solid-liquid separation from the residue. In addition, it is preferable to use water that does not adversely affect the hydrometallurgical smelting process as the above-mentioned washing water, and for example, a poor liquid with a low pH obtained in the sulfurization step S4 described later can be repeatedly used.

[Neutralization process]
In the neutralization step S3, a neutralizing agent such as calcium carbonate is added to the leachate collected as the overflow liquid of the thickener in the solid-liquid separation step S2 to neutralize the leachate, which contains trivalent iron as an impurity element. This is a step of precipitating Japanese sediment. The pH of the treatment solution in this neutralization treatment is preferably within the range of 4.0 or less, more preferably 3.0 or more and 3.5 or less, and most preferably 3.1 or more and 3.2 or less. It is preferable to adjust the amount of addition. After this neutralization treatment, the neutralized precipitate is removed by introducing the slurry containing the neutralized precipitate into a solid-liquid separator such as a thickener, and the neutralized final liquid is obtained as a mother liquor for recovering nickel and cobalt. to recover.

[Sulfurization process]
In the sulfurizing step S4, a sulfurizing agent is added to the mother liquor for recovering nickel and cobalt (sulfurizing reaction starting liquid) as the neutralization final liquid recovered from the solid-liquid separator of the neutralizing step S3 to perform sulfurizing treatment. This is a process in which a sulfurization reaction is caused and the nickel and cobalt contained in the sulfurization reaction starting solution are fixed as a mixed sulfide. The mixed sulfide can be recovered by introducing the slurry containing the mixed sulfide of nickel and cobalt after the sulfurization reaction into a solid-liquid separator.

<Liquid level measuring device>
The liquid level measuring instrument of the present invention is an instrument used for measuring the liquid level within a reaction tank. A good example of a reaction tank to be measured is the above-mentioned autoclave used for high-pressure acid leaching treatment of nickel oxide ore. The liquid level measuring device of the present invention can accurately measure the liquid level even when the liquid level inside the reaction tank is below a certain level, especially when the reaction tank such as an autoclave is regularly shut down and repaired. Its main functional feature is that it can measure

The liquid level measuring instrument 1 shown in FIGS. 1 to 3 is an example of a preferred embodiment of the liquid level measuring instrument of the present invention. As shown in FIG. 1, a liquid level measuring device 1, which is a liquid level measuring device for a reaction tank such as an autoclave, includes a rod-shaped support 11, a plurality of liquid collection containers 12 installed at equal intervals on the support 11, Equipped with Preferably, a hanging rope 13 is connected to the top end of the support 11 of the liquid level measuring device 1.

The length of the support column 11 is not particularly limited, and can be optimally designed depending on the depth of the reaction tank to be used. Specifically, the length of the support column 11 is preferably 80% or more of the depth of the reaction tank to which it is applied. On the other hand, since it is assumed that the liquid level measuring device 1 will be handled manually by the measuring worker, the length of the support 11 should be within 3 m from the viewpoint of maintaining good handling during work. It is preferable to do so.

Here, if the depth of the reaction tank to which the application is applied, such as the above-mentioned autoclave, is approximately 4 m or more, a hanging rope of any length is additionally attached to the upper end of the support 11 whose length is 3 m or less. By joining 13, it is possible to accurately measure the liquid level in the area near the bottom of the reaction tank while maintaining good handling properties.

The material of the support column 11 is not particularly limited as long as it has the necessary strength and resistance to the liquid phase to be measured, but from the viewpoint of keeping the weight low and maintaining good handling by the operator. , preferably resinous. Further, in order to enable use even when the slurry to be measured is strongly acidic, it is more preferable to use a resin with excellent acid resistance. As the acid-resistant resin preferable as the material for the pillar 11, specifically, a resin selected from polyvinyl chloride, polyethylene, polypropylene, polystyrene, ABS resin, acrylic resin, polyvinylidene fluoride, and phenolic resin is used as the material for the pillar 11. Can be used. Among these, polypropylene, which has acid resistance, heat resistance, and economic efficiency in a well-balanced manner, can be particularly preferably used as the material for the pillars 11.

The shape of the liquid collection containers 12 installed on the support column 11 is not particularly limited as long as the container has an opening 121 on the upper side through which the liquid phase flows in and can store the liquid phase flowing therein. For example, it may be a cup-shaped container like the liquid collection container 12 shown in FIG. 2, or a bottle-shaped container such as a sample bottle for a reagent.

The capacity of the liquid collection container 12 can be optimally designed depending on the depth of the reaction tank to be used. For example, when used in an autoclave with a depth of 4 m, the capacity of the liquid collection container 12 is preferably 50 ml or more and 150 ml or less from the viewpoint of balance between ease of handling and measurement accuracy.

The material of the liquid collection container 12 is not particularly limited as long as it has the necessary strength and resistance to the liquid phase to be measured. It is preferable to use any resin selected from vinyl chloride, polyethylene, polypropylene, polystyrene, ABS resin, acrylic resin, polyvinylidene fluoride, and phenol resin.

In the liquid level measuring device 1, as shown in each drawing of FIGS. 1 to 3, the liquid collection containers 12 are connected to all the liquid collection containers within the lower end of the support 11 and a part of the lower side. 12 are installed on the side surface of the support 11 at regular intervals along the central axis direction of the support 11, with the openings 121 of the support 12 facing toward the upper side of the support 11. The method of installing the liquid collection container 12 on the support column 11 is not particularly limited as long as the durability of the joint can be ensured, and known joining means such as adhesion, welding, tightening, and suspension can be used.

More specifically, the arrangement range of the liquid collection container 12 with respect to the strut 11 is a range from the lower end 111 of the strut 11 to the upper end 112 to a height of 50% or more and 80% or less of the total length of the strut 11. It is preferable to set it as an upper limit. Since the main purpose of the liquid level measuring device 1 is to measure a relatively small amount of low liquid level remaining at the bottom of the reaction tank, the arrangement range of the liquid collection container 12 is set to the above range. This is because sufficient effects can be enjoyed.

Further, the arrangement interval (arrangement pitch p shown in FIG. 3) of the liquid collection container 12 with respect to the support column 11 can be optimally designed depending on the depth of the reaction tank to be used. When used in a 4 m autoclave, the arrangement pitch of the plurality of liquid collection containers 12 is preferably 10 cm or more and 30 cm or less from the viewpoint of appropriately maintaining the measurement accuracy of the liquid level. Note that the number of liquid collection containers 12 to be installed is not particularly limited, but it is preferable that the number of liquid collection containers 12 that is necessarily required when installed at the above arrangement pitch is preferably installed within the preferred installation range explained above, and It is preferable that at least three or more liquid collection containers 12 are installed.

The length of the hanging rope 13 is not particularly limited, and can be optimally designed depending on the depth of the reaction tank to be used and the length of the support column 11. Specifically, when the length of the support column 11 is approximately 80% of the depth of the reaction tank to which the application is applied, the length of the hanging rope 13 is set to 50% or more and 70% or less of the depth of the reaction tank. It is preferable to set it as approximately. When the depth of the target reaction tank is approximately 4 m or more, such as the above-mentioned autoclave, by configuring the liquid level measuring device 1 in this way, the bottom of the reaction tank can be easily accessed while maintaining good handling. It is possible to accurately measure the liquid level in the area near the side.

The material of the hanging rope 13 can be a light weight acid-resistant resin with excellent acid resistance, as long as it has the necessary strength and resistance to the liquid phase to be measured, like the support 11 and the liquid collection container 12. It is preferable to use a resin selected from polyvinyl chloride, polyethylene, polypropylene, polystyrene, ABS resin, acrylic resin, polyvinylidene fluoride, and phenol resin, and among them, it is preferable to use a resin that has a good balance of acid resistance, heat resistance, and economic efficiency. A rope made of polypropylene and having a diameter of 3 mm or more and 7 mm or less can be particularly preferably used.

<Liquid level measurement method>
The liquid level measuring method of the present invention can be carried out using the liquid level measuring instrument of the present invention described in detail above. When implementing the liquid level measuring method of the present invention using the liquid level measuring device 1, first, the liquid level measuring device 1 is inserted into the reaction tank along the vertical direction, and the lower end 111 of the column 11 is inserted into the reaction tank. Make contact with the bottom of the reaction tank. Then, the liquid level measuring device 1 is pulled up from the reaction tank.

Next, it is confirmed to which liquid sampling container 12, counting from the lower end 111, the slurry has flowed into among the plurality of liquid sampling containers 12 of the liquid level measuring device 1 that has been pulled up. Thereby, the liquid level of the slurry or the like remaining inside the reaction tank can be safely measured with necessary and sufficient accuracy.

In addition, if the target is a large reaction tank that handles strongly acidic slurry, such as the autoclave 2 shown in Figure 4, and if the presence or absence of liquid accumulation inside is to be confirmed during periodic shutdown repairs, If the liquid level measured by the liquid level measuring device 1 exceeds a predetermined height, the existence of a liquid pool is presumed, and the liquid is discharged repeatedly until the liquid pool is presumed to have disappeared. conduct. After the liquid level is sufficiently lowered and the liquid pool is presumed to have disappeared, the manhole 23 at the bottom of the autoclave 2 is opened and the worker can enter the interior of the autoclave 2 to safely carry out repair work. It can be done.

1 Liquid level measuring device 11 Strut 111 Lower end (of the strut) 112 Upper end (of the strut) 12 Liquid collection container 121 Opening 2 Autoclave 21 Storage section 22 Extraction pipe 23 Manhole 3 Reaction tank 31 Radiation source section 32 Detection Part S1 Leaching process S2 Solid-liquid separation process S3 Neutralization process S4 Sulfurization process

Claims (6)

A liquid level measuring device for a reaction tank,
A rod-shaped support,
a plurality of liquid collection containers;
The plurality of liquid collection containers are arranged within the lower end of the support and a portion of the support, with the openings of all of the liquid collection containers oriented toward the upper side of the support. installed at regular intervals on the side of the support column along the central axis direction;
Liquid level measuring device. A hanging rope is connected to the top end of the support.
The liquid level measuring device according to claim 1. The liquid collection container and the support column both include:
Acid-resistant resin selected from polyvinyl chloride, polyethylene, polypropylene, polystyrene, ABS resin, acrylic resin, polyvinylidene fluoride, and phenolic resin,
The liquid level measuring device according to claim 1. The hanging rope is
Acid-resistant resin selected from polyvinyl chloride, polyethylene, polypropylene, polystyrene, ABS resin, acrylic resin, polyvinylidene fluoride, and phenolic resin,
The liquid level measuring device according to claim 2. A method for measuring a liquid level in a reaction tank, the method comprising:
Inserting the liquid level measuring device according to any one of claims 1 to 4 vertically into a reaction tank, bringing the lower end of the support into contact with the bottom of the reaction tank, and then pulling it up.
Method for measuring liquid level in reaction tank. A method for measuring a liquid level in an autoclave used for high-pressure acid leaching treatment of nickel oxide ore, wherein the liquid level measuring device according to claim 3 or 4 is inserted vertically into the autoclave, and A method for measuring the liquid level in an autoclave, in which the lower end is brought into contact with the bottom of the autoclave and then pulled up.

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