JP2001009451A - Method of removing sulfate ion in salt water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly perform continuous operation and to reduce the time required for treatment by continuously transporting a zirconium hydroxide- carrying ion exchange resin in a slurry to circulate and performing simultaneously the adsorption reaction and the desorption reaction of sulfate ion in a sulfate ion-containing salt water. SOLUTION: The absorbed sulfate ion is desorbed from the zirconium hydroxide-carrying ion exchange resin in a desorption reaction vessel 1. The zirconium hydroxidecarrying ion exchange resin slurry regenerated therein is sent to a prestage separator 5 of a solid-liquid separation device 20. Solid- liquid separation-cleaning-transportation to the adsorption reactor 7 are carried out in the prestage separator 5. Sulfate ion is adsorbed and removed from the salt water in the adsorption reactor 7 and the zirconium hydroxide-carrying ion exchange resin slurry on which sulfate ion is absorbed is sent to a poststage separator 8 of the solid-liquid separation device 20. In the poststage separator 8, each process of solid-liquid separation-cleaning-transportation to the adsorption reaction vessel 1 are continuously carried out in this order. As a result, the time required for treating is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing sulfate ions from salt water, and more particularly, to adsorption and removal of sulfate ions from salt water containing sulfate ions using a zirconium hydroxide-supported ion exchange resin. This is a method for removing sulfate ions from salted water by desorbing, regenerating and reusing the zirconium hydroxide-supported ion-exchange resin.In particular, the zirconium hydroxide-supported ion-exchange resin is circulated and used while being transported without damage such as crushing. Accordingly, the present invention relates to a method for removing a sulfate ion of salt water which can shorten the continuous treatment time of adsorption and desorption, and can be treated efficiently and with a small treatment facility.

[0002]

2. Description of the Related Art When electrolyzing salt water, it is known that sulfate ions in the salt water adversely affect electrolysis performance.
For this reason, conventionally, sulfate ions in salt water have been removed during electrolysis. For example, JP-A-60-
JP-A-44056, JP-A-60-228691 and JP-A-3-153522 propose an ion exchange method for removing sulfate ions from salt water. That is,
The method described in Japanese Patent Publication No. 0-44056 is a method in which a polymeric hydrated zirconium oxide is supported on a macrobolic cation exchange resin to remove sulfate ions in salt water by a packed tower method. Further, the method described in Japanese Patent Application Laid-Open No. 3-153522 discloses a method in which zirconium hydroxide having a low water content is not directly carried on a cation exchange resin, but is directly brought into contact with salt water containing sulfate ions in a slurry state to adsorb sulfate ions. ,
In this method, zirconium hydroxide having sulfate ions adsorbed therein is contacted with an aqueous alkali solution in another reaction tank to desorb and regenerate sulfate ions for use. Further, JP-A-60-228
The method described in Japanese Patent No. 691 is a method of diluting salt water containing sulfate ions, adsorbing sulfate ions with an anion exchange resin, and desorbing the anion exchange resin adsorbing sulfate ions with concentrated salt water.

[0003]

However, all of the above methods have various problems such as low regeneration efficiency, high processing cost, increased processing equipment cost, and complicated operation. . For this reason, the applicant has previously disclosed in JP-A-8-6751.
No. 4 proposes an economical and highly industrial method for treating sulfate ion-containing salt water by solving these problems. In the proposed method, zirconium hydroxide is supported on a granular cation exchange resin and used as an adsorbent, and the adsorbent is brought into contact with a solution such as salt water in a predetermined fluid state to perform adsorption / desorption treatment. According to this method, the contact efficiency is remarkably higher than that of the conventional method, and the adsorption rate and the regeneration efficiency are improved, so that the salt loss and the like are small, the operation cost is reduced, and the method is excellent in industrial practicality. In addition, since the zirconium hydroxide-supported particulate ion exchange resin as an adsorbent is made into a fluid state by a fluid flow or the like without contacting mechanical means, crushing hardly occurs and the loss of the adsorbent is extremely small. It is excellent. Further, since the granular ion exchange resin is easily crushable, the above-mentioned excellent fluidization is also proposed, and the adsorption and desorption rate can be improved by effective fluid contact. However, since the zirconium hydroxide-supported particulate ion exchange resin is repeatedly held in the treatment tank, and the discharge and supply of the salt water to be treated, the desorption reaction liquid, the washing liquid, etc. are repeatedly performed, the treatment requires a long time, and the treatment time is long. In order to perform continuous operation, it is necessary to adopt a switch system in which a large number of processing tanks are provided in parallel and the operation process is switched sequentially, and equipment costs are incurred. It is considered that it is bulky,
In order to further improve the industriality of the above-mentioned proposed methods, further studies were made on their improvement.

That is, the present invention relates to the above-mentioned JP-A-8-6751.
In the method of removing sulfate ions from sulfate ion-containing salt water using zirconium hydroxide-supported ion exchange resin as the adsorbent proposed in No. 4, smooth continuous operation can be performed without increasing equipment costs, and the processing time is shortened. The purpose is to plan. For the above purpose, the inventors first reexamined the characteristics of the above-mentioned process, and at the same time, reexamined the properties of the ion exchange resin supporting zirconium hydroxide to be used. That is, with regard to the easily crushable ion exchange resin to be used, the crushability was examined in detail again, and the possibility of transfer was examined. As a result, the ion exchange resin carrying zirconium hydroxide is generally considered to be easily crushable, and when the inside of the reaction tank is actually stirred by a stirrer at the time of adsorption and desorption, the ion exchange resin is crushed by a stirring blade. It is found that, for example, in the case where the slurry is conveyed in a slurry state by an open impeller slurry pump or the like, crushing or breakage does not occur despite the fact that there has been a risk of crushing conventionally. Reached. That is, the present invention can use the ion-exchange resin as the adsorbent in each step, and can use the switch method for sequentially switching the steps, thereby enabling a smooth continuous processing completely different from that of the switching method and significantly reducing the processing time. Also, equipment and operating costs are reduced.

[0005]

According to the present invention, (1)
A sulfate ion-adsorbing step of adsorbing and removing sulfate ions by contacting a sulfate-containing salt water with an ion-exchange resin carrying zirconium hydroxide under acidic conditions, and (2) supporting zirconium hydroxide adsorbing sulfate ions in the sulfate ion adsorption step. A first solid-liquid separation / transportation step in which a slurry containing an ion exchange resin is collected by solid-liquid separation and collected and transported in the form of a slurry; (3) hydroxylation of sulfate ion adsorption transported from the first solid-liquid separation / transportation step A desorption regeneration step in which the zirconium-supported ion exchange resin is brought into contact with an aqueous solution having a pH higher than the acidity in the adsorption step in a fluid state to desorb sulfate ions and regenerate the zirconium hydroxide-loaded ion exchange resin; and (4) a desorption regeneration step. The second solid-liquid separation in which the slurry containing the regenerated zirconium hydroxide-supported ion exchange resin is separated by solid-liquid separation, collected, and transported in a slurry state In addition to the transport step, the regenerated zirconium hydroxide-supported ion-exchange resin transported from the second solid-liquid separation / transport step is supplied again to the sulfate ion adsorption step to form a circulation system, and the zirconium hydroxide-loaded ion-exchange resin is slurried. And a step of removing the sulfate ion from the salt water, wherein the steps are carried out in a continuous manner.

[0006] In the above-mentioned method for removing sulfate ions of salt water of the present invention, it is preferable that the slurry is conveyed under conditions that do not apply a special force, and a flow state is formed by flowing the aqueous solution in the desorption regeneration step. Is preferred. Further, in the desorption regeneration step, it is preferable that a part of the solid-liquid phase in a fluidized state be extracted and returned to the desorption regeneration step and circulated again, and the partial extraction of the solid-liquid phase be performed by a slurry pump. preferable.

In the second solid-liquid separation / transportation step of the method for removing sulfate ions of salt water of the present invention, the slurry of the regenerated and solid-liquid separated zirconium hydroxide-supported ion exchange resin is treated under acidic conditions. Sulfate ion-containing salt water is added, the slurry is transported, and an adsorption process is performed simultaneously with the transport to perform a sulfate ion adsorption step.

Further, in the first and second solid-liquid separation / transportation steps, there is provided a solid-liquid separation apparatus capable of transporting separated solids having at least a solid-liquid separation barrel, a solids transporting section and a mother liquor receiving tank, A rotatable annular cylindrical body is used as a solid-liquid separation body, and the annular cylindrical body is divided into two or more by partition walls, and a slurry introduction portion is provided on an inner peripheral surface side of each of the divided regions, and mother liquor is transmitted on an outer peripheral surface side. A solid material transporting section having a solid object introduction part in the center space of the annular cylindrical body and having a transport jig, and integrally formed and rotated. It is preferable to use a solid-liquid separation device in which the slurry introduction section and the solid matter introduction section at the upper position are opposite to each other, and a mother liquor receiving tank is disposed below the mother liquor permeation section at the lower position. .

Further, according to the present invention, each of the first and second separators constructed in the same manner as the above-mentioned solid-liquid separation device is connected to each other by extending each of the solid material transporting portions. Using a solid-liquid separation device having a separated solid matter discharge port in the intermediate portion, and the separated solid matter discharge port being continuous with a predetermined processing section and the processing section being continuous with a subsequent solid-liquid separator, The zirconium hydroxide-supported ion-exchange resin-containing slurry from the desorption / regeneration step is supplied to the pre-stage solid-liquid separator, separated into a mother liquor by solid-liquid separation, washed, and then washed with a washing liquid and / or sulfate ion. The second solid-liquid separation / transportation step and the sulfate ion adsorption step are carried out by carrying the slurry in the form of slurry with the contained salt water, withdrawing the carried slurry from the separated solids discharge port to the treatment section, and keeping the treatment section in a fluid state. Do Then, the zirconium hydroxide-supported ion-exchange resin-containing slurry from the processing section is supplied to a subsequent solid-liquid separator, which is separated into a mother liquor by solid-liquid separation. The present invention provides a method for removing a sulfate ion in salt water, which comprises carrying the first solid-liquid separation / transportation step by carrying it to the desorption regeneration step.

In the present invention, the term "contact in a fluid state" means that the sulfate-containing salt water or aqueous liquid and the zirconium hydroxide-supported (granular) ion-exchange resin coexist during sulfate ion adsorption and desorption. The salt water and the ion-exchange resin are always in a state of motion without being stationary together with the fluid motion generated by the fluid circulation or the like without the mechanical fluidizing means being provided in the treatment area, and both are uniformly mixed. Contact with each other, usually about 0.0
It means that it is in a motion state at a moving speed of 01 m / sec or more. The transportation in a slurry state refers to a state in which sulfate ion-containing salt water or an aqueous liquid and a zirconium hydroxide-supporting ion exchange resin coexist and are mixed.

The present invention is directed to a zirconium hydroxide-supported (granular) ion-exchange resin (hereinafter referred to as
The ion-exchange resin is simply conveyed in a slurry state by a screw using an open impeller slurry pump or the like. Unlike a general pump transfer, there is no severe collision with the pump impeller and no crushing of the ion-exchange resin occurs. It can be transferred without loss of adsorption capacity. Since the transfer, which was conventionally avoided because of the risk of crushing, is possible, the process of adsorbing and desorbing sulfate ions and the process of solid-liquid separation and transport between them are performed in separate reactors, and the reactors are connected in series. To continuously process and circulate the process to remove sulfate ions continuously and smoothly from the sulfate ion-containing salt water. For this reason, in comparison with the conventional switch system corresponding to the discharge / supply operation of the liquid by holding the conventional ion-exchange resin in the adsorption / desorption treatment tower, the present invention performs continuous processing by circulating without interruption in time, There is no time loss and processing time is significantly reduced.

Further, for example, one cycle of 60 minutes of adsorption (20 minutes) -draining / washing / draining (10 minutes) -desorption (20 minutes) -draining / washing / draining (10 minutes) is operated. If you do
In the conventional switching method, the same amount of ion-exchange resin is held in each step, but in the present invention, when the continuous operation reaches an equilibrium state, the same amount of sulfuric acid is used in about 1/3 of the amount of ion-exchange resin. Ions can be removed.
The fact that sulfate ions can be removed with a small amount of ion exchange resin in substantially the same manner as in the prior art means that the apparatus can be reduced in size and equipment costs can be reduced. In addition, the miniaturization of the apparatus may be performed depending on conditions such as extending the retention time of adsorption and / or desorption to improve the sulfate ion removal rate, or increasing the amount of ion exchange resin used to shorten the residence time. It can be selected appropriately, can be applied in a wide range, and has high industrial practicality. Furthermore, when the operation is performed with a high sulfate ion removal rate, the salt water containing a high concentration of sulfate ions can be treated, so that the amount of the treated salt water decreases. For this reason, the load of the dechlorination process essential before removing the sulfate ions from the salt water can be reduced, and the size of a series of treatment processes for electrolysis of the salt water can be reduced. Furthermore, the present invention forms a circulating system of a series of continuous steps for the adsorption treatment of sulfate ions and the regeneration treatment of the ion exchange resin as an adsorbent as described above to return to the adsorption treatment, thereby removing the sulfate ions from the salt water. Is performed smoothly, so that it is not necessary to provide a large number of reaction vessels in parallel as in the conventional switch system, and a predetermined solid-liquid separation device that can easily and easily perform solid-liquid separation and slurry transportation is used. Thus, the number of reaction equipment such as a reaction tank and a solid-liquid separator can be reduced as much as possible. This also makes the process of removing sulfate ions from the salt water more compact and simple.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail. The main points regarding the adsorption and desorption of the zirconium hydroxide-supported ion exchange resin and the sulfate ion as the adsorbent of the present invention will be described below. However, their basic configuration and mechanism are based on the technology proposed in Japanese Patent Application Laid-Open No. Hei 8-67514 by the applicant. That is, the ion-exchange resin supporting zirconium hydroxide, which is a substantial adsorbent component for sulfate ions, is preferably in the form of particles having an average particle diameter of 300 to 1200 μm. When the average particle size is smaller than 300 μm, a filter material having a fine mesh is used at the time of solid-liquid separation, and the filtration efficiency is reduced due to an increase in resistance. On the other hand, if the average particle size is larger than 1200 μm, the rate of adsorption and desorption of sulfate ions decreases and the rate of sedimentation is high, so that the slurry during transport is not uniform, which is not preferable. Usually, an ion-exchange resin having a particle size of several 100 μm is used. This is because the solid-liquid separation operation at the end of the adsorption or desorption becomes easy, and the workability such as handling is excellent. As proposed in JP-A-3-153522, the use of zirconium hydroxide as an adsorbent without using a carrier can reduce the particle size even if the predetermined solid-liquid separator of the present invention is used. Is difficult. As the ion exchange resin, any of a strongly acidic cation exchange resin, a weakly acidic cation exchange resin and a chelate resin may be used and may be appropriately selected. An anion exchange resin cannot be used because zirconium hydroxide has a low loading efficiency and the resin itself adsorbs and desorbs chloride ions, which impairs the selectivity of sulfate ion adsorption by zirconium hydroxide. Further, both a so-called gel type and macroporous type ion exchange resin classified according to the surface condition can be used. The gel-type resin generally has a small surface area, and thus the adsorption / desorption rate of sulfate ion tends to be lower than that of the macroporous type. However, it can be appropriately selected and used depending on the conditions.

In the sulfate ion adsorption step of the present invention, the sulfate ion in the salt water is adsorbed and removed by bringing the zirconium hydroxide-supporting ion exchange resin into contact with a sulfate ion-containing salt water under acidic conditions in a fluid state. The acidity is performed by adding an acid such as hydrochloric acid or nitric acid, and the salt water often contains an alkali metal chloride. Usually, hydrochloric acid is used. The acidity at the time of contact is usually in the range of pH 1 to 5, preferably pH 2 to 3. In general, lowering the pH value is preferable because the amount of sulfate ions adsorbed by zirconium hydroxide increases and the adsorption rate also increases. However, if the pH value is lowered too much, zirconium hydroxide dissolves and flows out of the system to cause a problem of cost increase, which is not preferable. In the present invention, since zirconium hydroxide is supported on the ion exchange resin, even if some of the zirconium hydroxide is dissolved to generate zirconyl ions, the functional groups of the ion exchange resin capture the zirconyl ions, so that the zirconyl ions are trapped outside the resin. Zirconyl ions are not diffused into the metal. For this reason, compared with the sulfate ion adsorption removal method using zirconium hydroxide powder, in the sulfate ion adsorption step of the present invention, the contact treatment is usually performed under acidic conditions in the range of pH 1 to 5, preferably pH 2 to 3. It is possible to increase the adsorption efficiency by a synergistic effect with the fluid state.

In the sulfate ion adsorption step of the present invention, the ion exchange resin regenerated in the desorption / regeneration step is separated into solid and liquid by a predetermined solid-liquid separation device described below without the need of providing an adsorption reaction tank, and the slurry is conveyed. In this case, the salt water to be treated under an acidic condition may be added to adsorb and remove sulfate ions simultaneously with the transportation. In addition, a reaction tank is provided in the middle of the transport section of the solid-liquid separation device, and the slurry after the completion of the adsorption reaction is once extracted at the time of transport, and then the second solid-liquid separation / reaction step (second-stage separator) of the next step is performed. Send to For this reason, it is possible to cause the adsorption reaction at the time of transfer, and also to perform the adsorption reaction in the slurry flowing state in the reaction tank in the middle of the transfer section or only in the reaction tank.

In the desorption regeneration step of the present invention, the following ion-exchange resin adsorbing sulfate ions, which has been conveyed by solid-liquid separation / slurry transportation, is treated in a desorption reaction tank with a pH higher than the above-mentioned adsorption pH
An aqueous solution having an H value, that is, pH 3 to 11, preferably pH 5 to 10 is contacted with the slurry in a fluidized state to desorb sulfate ions. For pH adjustment during desorption, an alkali such as caustic soda is usually added. When the pH value at the time of desorption is lower than 3, the desorption efficiency of sulfate ions is low, and when the pH value is higher than 11, sodium ions reacting with zirconium hydroxide increase and the basic units of caustic soda and hydrochloric acid are unfavorably deteriorated.

In the present invention, the reaction tank (including the intermediate reaction tank of the solid-liquid separation device) for carrying out the adsorption / desorption reaction of the sulfate ion maintains a uniform fluid state of the slurry of the ion exchange resin and the aqueous liquid. Any shape can be used, and the shape is not particularly limited. In addition, the adsorption / desorption speed varies depending on the adsorption / desorption reaction conditions such as the amount of salt water to be treated and the concentration of sulfate ions contained (the amount of sulfate ions to be removed), temperature, pH value, and flow rate of the circulating slurry. What is necessary is just to select suitably according to it. In this case, in the present invention, since the ion exchange resin circulates and moves continuously, the slurry concentration is 50 to 50% with respect to the circulation amount of the ion exchange resin.
It is preferable to be able to stay at 60% by weight for about 15 to 20 minutes.

In the present invention, the flow state of the slurry during the adsorption / desorption reaction in the reaction tank is described in the above-mentioned JP-A-8-675.
It is formed without using a mechanical stirrer or the like as in the method proposed in Japanese Patent Publication No. This is to avoid crushing of the resin. In other words, the acidic treated salt water is supplied from the lower part of the reaction tank at the time of adsorption and the desorbed alkaline aqueous liquid at the time of desorption, and the ion exchange resin retained in the tank is made into a uniform slurry fluidized state.
Each liquid is usually supplied to the reaction tank at an LV value of 70 to 80 m / hour, whereby the development rate of the ion exchange resin can be set to 1.7 to 1.8, and the slurry concentration in the tank can be controlled. Can be approximately 50 to 60% by weight. In particular,
In the desorption reaction tank, the circulation amount of the ion exchange resin in the process system may be withdrawn by a slurry pump at a slurry concentration in the tank and returned to the desorption tank again. The tank circulation of the ion exchange resin slurry is preferable because the contact in the fluidized state is more effectively promoted and 80% or more of the adsorbed sulfate ion can be desorbed. Further, by using an open impeller type slurry pump, the ion exchange resin is not crushed by contact with the impeller.

In the present invention, the ion-exchange resin which has completed the adsorption / desorption reaction as described above is fed into a solid-liquid separator in the form of a slurry, solid-liquid separated, and the mother liquor is recovered by filtration. It is sent in the form of a slurry of the aqueous liquid, and is again subjected to the adsorption / desorption reaction. In this case, transportation to the solid-liquid separation device
Usually, the use of the same slurry pump as in the desorption tank circulation system can prevent the ion exchange resin from being crushed. The solid-liquid separator is not particularly limited as long as it can perform solid-liquid separation without crushing without giving an impact force to an ion exchange resin such as a general rotary drum type filter, and is not particularly limited. It is preferable to use the solid-liquid separation device described. That is, the solid-liquid separation device will be described in detail below,
It consists of two separators in the front and rear stages with an annular separator rotating at the same time and rotating at low speed. The transporter is concentrically arranged through the center of each separator, and the ion exchange that has completed the desorption reaction outside the device Receiving the resin in the form of slurry, separating the mother liquor, washing and recovering the ion exchange resin, transporting the aqueous liquid, preferably a sulfated salt-containing salt water again,
Simultaneously with transportation and / or adsorption of sulfate ions in the adsorption reaction tank, the slurry-like ion-exchange resin after adsorption is similarly separated and washed with mother liquor, and the ion-exchange resin is continuously slurry-like in the desorption reaction tank outside the apparatus. It has a function of sending out the information.

In addition, an intermediate part of the conveying part provided through each of the separation cylinders of the solid-liquid separating device is provided with a conveyed slurry discharge part, and an intermediate reaction tank is provided so as to be connected to the conveyed slurry discharge part. The ion-exchange resin conveyed in the form of slurry with the ion-containing salt water is once extracted, and if necessary, after the adsorption reaction is completed in the intermediate reaction tank, it is moved to the post-separator in the form of slurry. Normally, the mother liquor is separated and washed after adsorption in the pre-separator, and after adsorption in the post-separator.The transporter in the center collects the ion-exchange resin that has fallen off from each separation cylinder. The exchange resin is sent from the slurry extraction portion to the reaction tank, and in the latter-stage separator, the sulfate ion-adsorbed ion exchange resin is sent out of the apparatus and is recycled to the desorption tank. In the solid-liquid separation device, it is preferable that the pH value of the washing water after the adsorption is equal to or lower than the pH at the time of the adsorption when washing the ion-exchange resin separated from the mother liquor by the solid-liquid separation. This is because when the pH value is higher than the pH at the time of adsorption, a part of the adsorbed sulfate ions is desorbed. This point, as described above,
This is related to increasing the amount of adsorption by lowering the value as much as possible. Therefore, by controlling the pH value at the time of washing after adsorption, the amount of collected salt can be increased.

According to the present invention, as described above, each ion-exchange resin after the completion of the adsorption / desorption reaction is continuously sent in a slurry state from each reaction tank (or the reaction zone of the transport section) to the solid-liquid separation device, The mother liquor is separated by solid-liquid separation and collected by filtration, sent again in a slurry state of a predetermined aqueous liquid, and subjected to the adsorption / desorption reaction again. That is, the present invention is a method for removing sulfate ions in salt water by moving a zirconium hydroxide-supported ion exchange resin as an adsorbent and continuously repeating adsorption and desorption regeneration of sulfate ions. Conventionally, the adsorbent supporting zirconium hydroxide as the adsorbent component on the granular ion exchange resin, which is considered to be easily crushed, and is considered to have low workability and its handling is complicated, for removing sulfate ions contained in salt water. Transporting, circulating and using for adsorption and desorption,
This is the first proposal proposed by the present invention. Further, according to the present invention, the present invention provides one reaction tank (desorption reaction tank).
And the solid-liquid separation device and the minimum unit, and successively perform the steps of adsorption-solid-liquid separation-washing-transportation-desorption-solid-liquid separation-water-washing-transportation to convert sulfate ions from salt water. It can be removed efficiently, stably and economically.

Embodiments of the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited by the following embodiments. FIG. 1 is a process flow explanatory diagram of an example of a sulfate ion removal method of the present invention in which a zirconium hydroxide-supported ion exchange resin is used as an adsorbent, and adsorption and desorption of sulfate ions are repeated to regenerate and use the adsorbent. FIG. 2 is an explanatory diagram of an example of the solid-liquid separation device used. In FIG. 1, an ion-exchange resin adsorbent used in an adsorption process and having reduced adsorption capacity is supplied as a slurry to a desorption reaction tank 1, and a desorption treatment mother liquor and cleaning water or a predetermined cleaning solution described below are supplied from a line L1. Line L
The caustic soda solution is supplied from 2 and desorbed. The desorption reaction tank 1 and the aqueous liquid tank 2 are connected via a line L3, a pump P1, and a line L4 to form a desorption circulation system, and the aqueous liquid in the aqueous liquid tank 2 flows in from the line L4 by the pump P1 to be desorbed. The slurry in the reaction vessel is made to flow uniformly. In the desorption reaction tank 1, adsorbed sulfate ions are desorbed from the ion-exchange resin with reduced adsorption function as sodium sulfate (Glauber's salt) to regenerate the ion-exchange resin. Further, the slurry containing the regenerated ion exchange resin in which sodium sulfate (Glauber's salt) is dissolved by the desorption reaction treatment is continuously supplied from the line L5 by the pump P2 to the solid-liquid separation unit 5 of the pre-separator 5 of the solid-liquid separation device 20 shown in FIG. It is sent to the separation trunk 51.

Next, the solid-liquid separation device 20 shown in FIG. 2 will be described, and the steps after the above-mentioned steps for removing sulfate ions will also be sequentially described. In FIG. 2, in the solid-liquid separation device 20, two front-stage separators 5 and a rear-stage separator 8, which are formed in substantially the same manner, are connected in series by a connecting / conveying unit 6.
Each of the separators 5 and 8 mainly includes a solid-liquid separation body 51 (51 ′),
81 (81 '), solid transport sections 52 and 82, and mother liquor receiving tanks 53 and 83. The solid-liquid separation barrels 51 (51 ′) and 81 (81 ′) are formed in an annular cylindrical shape, and the solid material transporting units 52, 8 are provided in the central space of the annular cylinder of the solid-liquid separation barrel.
2 is provided with the intermediate spaces 57 and 87 interposed therebetween.
The solid-liquid separation barrels 51 (51 ') and 81 (81') are connected to the transmission G1 and are driven by driving rollers R1, R2 which rotate in conjunction therewith.
And are connected to driven rollers R3 and R4 to be rotatable. A partition is provided in the annular cylinder of each solid-liquid separation body to form two or more divided areas. For example, eight sections are equally divided into four section areas 51 and 81 located at the lower part of the rotating solid-liquid separation cylinder and four section areas 51 ′ and 81 ′ located at the upper part. At the same time, the slurry introduction section 5
4 (solid discharge section 54 'at the upper position), 84 (8
4 ′) and the mother liquor transmitting portions 55, 8 on the outer peripheral surface side.
5 is arranged. The mother liquor transmitting portions 55 and 85 are, for example, formed of a net or a grid having an outer shape made of a hard material such as metal, hard plastic, and wood, and are provided with mesh openings through which solids containing the supply slurry do not pass. It is formed by disposing a filter material of a flexible mesh body made of resin such as saran net. Further, the slurry introduction sections 54 and 84 (the solid substance discharge section 5)
4 ', 84') are formed by opening some or all of the spaces between the partitions on the inner peripheral surface of the solid-liquid separation cylinder.

The transporting units 52 and 82 are provided with a transporting jig substantially similar to a conventionally known screw conveyor, that is, a transport rotating shaft 62 having a screw blade 63 and a circular or U-shaped tubular body 61.
And is rotated in conjunction with the transmission G2. Further, the solid introduction portions 56 and 86 are provided at predetermined upper positions, and the solid discharge portions 54 'and 8 are provided at the upper position by rotation of the solid-liquid separation cylinder.
4 ′. Further, the mother liquor receiving tanks 53 and 83 are disposed below the mother liquor transmitting parts 55 and 85 at the lower position by the rotation of the solid-liquid separation cylinder, and the mother liquor corresponding to the liquid phase separated by the solid-liquid separation is collected. A slurry supply pipe 58 is disposed in the intermediate space 57. A transport slurry discharge section 64 is disposed in the connecting transport section 6 and a partition wall 65 is disposed to isolate the transport sections 52 and 82 of each solid-liquid separator. In addition, an adsorption reactor 7 is installed between the solid-liquid separator 5 and the solid-liquid separator 8 so as to be continuous with the discharge section 64, and is provided between the regenerated ion exchange resin and the washing liquid conveyed from the solid-liquid separator 5. The regenerated ion-exchange resin slurry is sent through the discharge unit 64. A delivery pipe 66 is provided in the adsorption reactor 7, and the sulfate-adsorbed ion-exchange resin slurry overflows through the intermediate space 87 of the subsequent solid-liquid separator 8 to form a solid-liquid separation body 81.
To send to.

The regenerated ion exchange resin slurry is supplied from the slurry supply pipe 58 to the intermediate space 57, and is further introduced into the rotating solid-liquid separation body 51 via the slurry introduction section 54. The regenerated ion exchange resin slurry is supplied to the solid-liquid separation body 5.
1, the aqueous solution containing the mother liquor, ie, sodium sulfate, is filtered from the line L1 through the mother liquor permeation part 55.
And the regenerated ion exchange resin is separated and left in the solid-liquid separation body 51. In addition, washing water is supplied simultaneously with slurry supply,
The regenerated ion exchange resin supplied and separated from the spray nozzle (not shown) provided in the intermediate space 57 is washed, and the washing water is returned to the desorption reaction tank 1 together with the mother liquor. The solid-liquid separation cylinder 51 holding the regenerated ion-exchange resin becomes the solid-liquid separation cylinder 51 ′ at the upper position by rotation, and the held regenerated ion-exchange resin is moved by its own weight from the solid discharge section 54 ′ to the intermediate space 57 and It flows down to the transport section 52 via the solid matter introduction section 56. Further, the washing water is sprayed from the washing water supply unit 59 (line L6 in FIG. 1) disposed above the solid-liquid separation cylinder 51 ′ to wash the solid-liquid separation cylinder 51 ′, and at the same time, the remaining regenerated ion exchange resin is transferred to the conveyance unit. Outflow to 52. The regenerated ion exchange resin is transported in a slurry state together with the washing water in the transport section 52 and is supplied to the adsorption reactor 7. At the same time, the sulfuric acid ion-containing salt water of the liquid to be treated, which is adjusted to a predetermined acidic pH by adding hydrochloric acid, flows into the adsorption reactor 7 from the line L7 through the inlet 67. Due to the inflow of the salt water, the regenerated ion exchange resin slurry transported in the adsorption reactor 7 is brought into a fluid state together with the replenishment ion exchange resin to be replenished if necessary, and the sulfate ion adsorption reaction is smoothly performed. The slurry containing the sulfate ion-adsorbed ion-exchange resin, in which the sulfate ions in the salt water in the adsorption reaction tank 7 are adsorbed, overflows in the delivery pipe 66.
(Line 12 in FIG. 1) is sent out to the post-stage separator 8 of the solid-liquid separation device 20.

In the second-stage separator 8, the slurry supplied to the solid-liquid separation body 81, which rotates similarly to the first-stage separator 5, is filtered through the net-shaped outer peripheral portion 85, and is filtered into the mother liquor, ie, the desulfated ion-treated salt water. Is simultaneously recovered from the line L8 into the salt water system together with the washing water for the sulfate ion-adsorbed ion exchange resin supplied to the solid-liquid separation body 81. On the other hand, the solid-liquid separation body 81
Similarly, the sulfate-ion-adsorbed ion-exchange resin, which has been separated and left, is also rotated by the solid-liquid separation cylinder 81 in the upper solid-liquid-separation cylinder 81 ′, and the sulfate-ion-adsorbed ion-exchange resin is removed from the washing water supply unit 89 ( The washing water sprayed from the line L9) in FIG. 1 flows down from the solid discharge section 84 ′ to the transport section 82 through the intermediate space 87 and the solid introduction section 86. The sulfate ion-adsorbed ion-exchange resin is transported in a slurry state together with the washing water in the transport section 82, and is fed into the desorption reaction tank 1 from the slurry outlet 68 (line L10) and circulated. The aqueous liquid overflowing the desorption reaction tank 1 is sent from the line L3 to the aqueous liquid tank 2, and a part of the aqueous liquid is discarded outside the system from the line L4 of the desorption circulation system.

The solid-liquid separation device 20 of FIG. 2 configured as described above differs from the conventional solid-liquid separation device in that the solid-liquid separation process and the separated ion-exchange resin separated and conveyed are performed without separately providing a conveying device. Can be simultaneously performed in the same apparatus, and the form and the adsorption function of the easily crushable ion exchange resin are not impaired by the transportation. Therefore, it is suitable for forming a circulation treatment system for adsorption and desorption of sulfate ions, and removing sulfate ions from salt water while continuously transporting the ion-exchange resin carrying zirconium hydroxide in the system. Further, the solid-liquid separation device 20 includes:
Sulfate ion-containing salt water of the liquid to be treated can be supplied from the supply port 69 (line L13 in FIG. 1), and the regenerated ion exchange resin adsorbent can be adsorbed while carrying the slurry. Further, as shown by the broken line in FIG. 1, a part of the slurry in the fluidized state in the desorption reaction tank 1 is withdrawn by the pump P3, circulated again to the desorption reaction tank 1 in a slurry state by the line L11, and The flow state can be made more active, the contact can be increased, and the desorption efficiency can be improved.

[0028]

EXAMPLES The cation exchange resin supporting zirconium hydroxide used in this example was prepared by the following method. That is, a cation exchange resin (trade name: Diaion PK2, manufactured by Mitsubishi Kasei Corporation)
16) 10 liters were placed in a polypropylene container, 20 liters of a 2 mol (M) aqueous solution of zirconium oxychloride was added, and immersion treatment was performed for 2 hours with appropriate stirring. After decantation removal of the aqueous solution of zirconium oxychloride, the cation exchange resin was washed five times using a total of 25 liters of pure water. The washed cation exchange resin was put into 40 liters of a 2M sodium hydroxide solution, and immersed for 1 hour with appropriate stirring. After decantation of the caustic soda solution, the cation exchange resin was washed five times using a total of 25 liters of pure water. In the fifth washing, concentrated hydrochloric acid was added dropwise without removing the washing water to adjust the pH to 2.5, and then the liquid was decanted off. Then pH
2.5 The cation exchange resin from which the adjusted solution was removed
The immersion treatment and washing with an aqueous solution of zirconium oxychloride and the immersion treatment and washing with a 2M sodium hydroxide solution were similarly repeated. However, the pH of the fifth final washing in the 2M caustic soda solution treatment was 8.5. The 2M aqueous solution of zirconium oxychloride and the 2M aqueous solution of caustic soda in the second treatment were previously used and recovered by decantation. The total amount of the zirconium hydroxide-supported cation exchange resin prepared as described above was used in this example.

Using a solid-liquid separator similar to that shown in FIG. 2, sulfate ions were removed in the same manner as in the process shown in FIG. As the desorption tank 1, an acrylic resin tower having a diameter of 250 mm and a height of 600 mm was used. Further, the separators 5 before and after the solid-liquid separation device 20,
8 are the same size, and solid-liquid separation barrels 51 (51 ′) and 81 (81 ′) for performing a substantial solid-liquid separation process are:
50m inner diameter with solid material transfer units 52 and 82 arranged at the center
It was formed into a cylindrical shape with both ends closed and having a diameter of mφ and a length of 1600 mm. The outer peripheral surface of each of the solid-liquid separation cylinders 51 (51 ′) and 81 (81 ′) is provided inside a porous titanium material having a large number of perforations.
A 0-mesh titanium net is stretched to form a mother liquor transmitting portion 55, 8
5 was formed.

In the desorption tank 1 constructed as described above, first, a total of 10 liters of a cation exchange resin carrying zirconium hydroxide (hereinafter simply referred to as ion exchange resin) prepared as an adsorbent, which is an adsorbent, for start-up, and city water. 10 liters were supplied. At the same time, the pH of the slurry in the desorption tank 1 is adjusted to 8.
A 32% by weight caustic soda solution is fed from the line L2 so as to maintain the solution at 5 to 9.0, and city water (aqueous liquid) previously stored in the aqueous liquid tank 2 having a capacity of 10 liters is pumped by the pump P.
1, the aqueous solution overflowing the desorption tank 1 was sent out to the aqueous liquid tank 2 via line L3 to form a circulation system. Next, the ion-exchange resin slurry was withdrawn from the desorption tank 1 by the pump P2 at a flow rate of 20 liter / hour, and was fed into the slurry supply pipe 58 of the pre-stage separator 5 via the line L5. The ion-exchange resin slurry flows through the intermediate space portion 57 from the slurry introduction portion 54 into the solid-liquid separation cylinder 51 located below, and is subjected to solid-liquid separation processing. All of the filtrate which was separated into solid and liquid and flowed down from the mother liquor permeation section 55 to the mother liquor storage section 53 was sent out to the desorption tank 1 via the line L1. The solid-liquid separation cylinder 51 holding the separated and remaining ion-exchange resin moves to the separation cylinder 51 ′ at the upper position by rotation, and the washing water supply unit 59.
Was sprayed with city water at a rate of 10 liters / hour for washing. For this reason, in the separation cylinder 51 ′, the ion exchange resin flows down by its own weight, and at the same time, flows down to the transport section 52 through the solid substance discharge section 54 ′ and the solid substance introduction section 56 by washing.
Was transported in slurry form.

The transported ion exchange resin was sent out from the transport slurry discharge section 61 to the adsorption reactor 7 having a capacity of 20 liters. In the adsorption reactor 7, the sulfate-containing salt water (Na at 70 ° C.) of the liquid to be treated is supplied from the inlet 64 under acidic conditions (pH 2)
200 g / l of Cl and 8 g / l of Na2SO4) were introduced at a flow rate of 100 l / h to fluidize the ion exchange resin and simultaneously remove sulfate ions from the salt water by contact with the ion exchange resin carrying zirconium. The ion-exchange resin having reduced adsorption capacity by adsorbing sulfate ions overflowed from the adsorption reactor 7 in the form of slurry, and was sent to the post-separator 8 through the delivery pipe 63. The fed ion-exchange resin slurry was supplied to the solid-liquid separation cylinder 81 located below from the slurry introduction part 84 via the intermediate space part 87 of the post-stage separator 8 and subjected to solid-liquid separation processing. All of the filtrate that was solid-liquid separated and flowed down from the mother liquor permeation section 85 to the mother liquor storage section 83 was discharged out of the system from the line L8. The solid-liquid separation cylinder 81 holding the separated and remaining ion-exchange resin moves to the separation cylinder 81 ′ at the upper position by rotation, and the washing water supply unit 89.
Was sprayed with city water at a rate of 2 liters / hour for washing. Separation cylinder 8
In 1 ', the ion-exchange resin flows down by its own weight, and at the same time, flows down through the solids discharge section 84' and the solids introduction section 86 to the transport section 82 by washing, and is transported in the transport section 82 in a slurry form. Was. The ion exchange resin transported in the transport section 82 was discharged from the discharge port 68 and fed into the desorption tank 1 through the line L10. As described above, the desorption tank 1 is supplied with the 32% by weight caustic soda solution, the mother liquor from the pre-separator 5, the washing water and the circulating aqueous liquid from the aqueous liquid tank 2 through the line L 1. It was kept at zero. Also,
A part of the aqueous liquid is transferred from line L4 of the aqueous liquid circulation system to line L.
At 14 the gas was discharged out of the system.

As described above, the desorption of the adsorbed sulfate ion from the ion exchange resin in the desorption tank 1, the feeding of the ion exchange resin slurry to the pre-separator 5 of the solid-liquid separator 20 and the pre-separator 5 Solid-liquid separation-washing-conveyance to adsorption reactor 7, adsorption and removal of sulfate ions from salt water in adsorption reactor 7, introduction of ion-exchange resin slurry into solid-liquid separation device 20 into post-separator 8, post-separation Each processing step of solid-liquid separation-washing-transfer to the desorption tank 1 in the machine 8 was continuously performed.
The continuous operation of the above process reached equilibrium in about 6 hours. The desorption liquid in this case (the liquid discharged from the aqueous liquid tank 2 to the outside of the system) is
Flow rate 10 l / h, 10 g / l Na
It contained 2SO4. That is, Na2SO4 is 100
g / h. In addition, the ion exchange resin transported inside the solid-liquid separation device is not damaged or crushed,
Even after continuous operation for 24 hours or more without deteriorating the functional characteristics such as the adsorbing ability, it had a sufficient adsorbing ability and could be used further.

A comparison between the above embodiment of the present invention and a conventional multi-column process is shown in Table 1 below. As is clear from Table 1, it can be seen that the present invention significantly reduces the amount of adsorbent used. Table 1 shows that the amount of Na2SO4 removed was 100 kg.
/ H, the result of operating at a Na2SO4 concentration of 7 g / l and a NaCl concentration of 200 g / l in the feed saline.

[0034]

[Table 1]

[0035]

According to the method for removing sulfate ions of salt water of the present invention, the zirconium hydroxide-supported ion-exchange resin is continuously transported in a slurry state and circulated for use. Since the desorption reaction is performed at the same time, the time required for the treatment is remarkably reduced as compared with the conventional method in which a batch-type or switch-type ion-exchange resin is held in a reaction tank, and the practicability is excellent. Moreover, the workability is improved by automatically transporting the easily crushable ion-exchange resin in a slurry state, and at the same time, the ion-exchange resin is hardly damaged, the loss is small, and the loss of salt can be reduced. And operating costs are reduced. Furthermore, it can be easily operated and operated with a minimum number of reaction tanks and separators, and does not require expensive control equipment, so that the equipment cost is not increased and it is extremely industrially useful.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a process flow according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an example of a solid-liquid separation device used in the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Desorption reaction tank 2 Aqueous liquid tank P1, P2 Pump 20 Solid-liquid separation apparatus 5 Pre-separator 6 Connection conveyance part 7 Adsorption reactor 8 Post-separator 51, 51 ', 81, 81' Solid-liquid separation cylinder 52, 82 Solid Material transport section 53, 83 Mother liquor receiving tank 54 (54 '), 84 (84') Slurry introduction section (solid substance discharge section) 55, 85 Mother liquor transmission section 56, 86 Solid substance introduction section 57, 87 Intermediate space section 58 Slurry supply Pipes 59, 89 Cleaning water supply unit 61 Pipe body 62 Transport rotation shaft 63 Screw blade 64 Transport slurry discharge unit 65 Partition wall 66 Delivery pipe 67 Inflow port 68 Slurry discharge port 69 Supply port G1, G2 Transmission R1, R2 Drive roller R3 , R4 driven roller

Claims (8)

[Claims] (1) Sulfate ion-containing salt water is prepared under acidic conditions.
A sulfate ion adsorption step of contacting in a fluid state with a zirconium hydroxide-supported ion exchange resin to adsorb and remove sulfate ions,
(2) a first solid-liquid separation / transportation step in which a slurry containing a sulfate ion-adsorbed zirconium hydroxide-supported ion exchange resin in the sulfate ion adsorption step is separated by solid-liquid separation, collected, and transported in a slurry state; 1 The sulfated zirconium hydroxide-supported ion-exchange resin transported from the solid-liquid separation / transportation step is transported in a fluidized state to a pH higher than the acidity of the adsorption step
And (4) a solid-liquid slurry containing the zirconium hydroxide-supported ion-exchange resin regenerated in the desorption regeneration step, wherein the slurry contains solid-liquid. It has a second solid-liquid separation / transportation step of separating and collecting and transporting it in the form of a slurry, and supplies the regenerated zirconium hydroxide-supported ion exchange resin transported from the second solid-liquid separation / transportation step again to the sulfate ion adsorption step. Forming a circulating system, and transporting the zirconium hydroxide-supporting ion-exchange resin in a slurry state to continuously carry out each of the above steps. 2. The method for removing sulfate ions from salt water according to claim 1, wherein the transportation in the form of a slurry is performed under such a condition that no special force is applied to the ion exchange resin. 3. The method for removing a sulfate ion from salt water according to claim 1, wherein the fluid state is formed by flowing the salt water in the sulfate ion adsorption step and the aqueous solution in the desorption regeneration step, respectively. 4. The method for removing a sulfate ion from salt water according to claim 1, wherein in the desorption regeneration step, a part of the slurry in a fluidized state is extracted, returned to the desorption regeneration step, and circulated in a slurry state. . 5. The method according to claim 4, wherein the extraction is performed by a slurry pump. 6. In the second solid-liquid separation / transport step,
To the slurry of the regenerated and solid-liquid separated zirconium hydroxide-supported ion-exchange resin, a sulfuric acid ion-containing salt water to be treated is added under acidic conditions, and the slurry is transported. A method for removing sulfate ions from brine according to any one of claims 1 to 5. 7. A solid-liquid separator capable of transporting separated solids having at least a solid-liquid separation body, a solids transporter, and a mother liquor receiving tank in the first and second solid-liquid separation / transportation steps, A rotatable annular cylindrical body is used as a solid-liquid separation body, and the annular cylindrical body is divided into two or more by partition walls, and a slurry introduction portion is provided on an inner peripheral surface side of each of the divided regions, and mother liquor is transmitted on an outer peripheral surface side. A solid material transporting section having a solid object introduction part in the center space of the annular cylindrical body and having a transport jig, and integrally formed and rotated. 2. A solid-liquid separation device comprising a slurry introduction section and a solid substance introduction section at an upper position of the solid liquid introduction section, and a mother liquor receiving tank disposed below the mother liquor permeation section at a lower position. 7. The method for removing a sulfate ion from brine according to any one of claims 6 to 6. 8. A solid-state separation unit connected to the solid-liquid separation unit in a manner similar to that of the solid-liquid separation unit according to claim 7 by extending the solid-state transfer units and connecting the solid-state transfer units. Using a solid-liquid separation device having a separated solids discharge port in the middle of the solid-liquid separator, and the separated solids discharge port being continuous with a predetermined processing section and the processing section being continuous with a subsequent solid-liquid separator. Supplying the slurry containing the zirconium hydroxide-supported ion exchange resin from the desorption regeneration step to the former-stage solid-liquid separator, separating the mother liquor by solid-liquid separation, washing, and then washing the zirconium hydroxide-supported ion exchange resin with a washing liquid and / or Alternatively, the slurry is conveyed in the form of a slurry with sulfate ion-containing salt water, the conveyed slurry is withdrawn from the separated solids discharge port into the processing section, and the processing section is kept in a fluid state to thereby carry out the second solid-liquid separation / transport step and the sulfate ion. Forming the adsorption process Then, the slurry containing the zirconium hydroxide-supported ion-exchange resin from the treatment section is supplied to the latter-stage solid-liquid separator, separated into a mother liquor by solid-liquid separation, washed, and then washed with a zirconium hydroxide-supported ion-exchange resin. The method for removing sulfate ions from salt water according to any one of claims 1 to 5, wherein the first solid-liquid separation / conveying step is formed by conveying the cleaning liquid and slurry in the form of the desorbing / regenerating step.