Valuable metal recovery system

Abstract

The present invention provides a valuable metal recovery system that uses an adsorbent capable of adsorbing a target valuable metal and recovering the valuable metal by firing or incineration. [Solution] The valuable metal recovery system 1 consists of a wastewater treatment device 2 and a valuable metal recovery device 3. The wastewater treatment device 2 consists of a tank 21, a coagulation and sedimentation tank 22, a membrane filtration device 23, and a valuable metal adsorption device 24, each comprising a water treatment unit. The valuable metal adsorption device 24 is equipped with a removable adsorbent-filled column. These water treatment units are modularized and can be transported to the wastewater discharge site on one or more trailers T and installed on-site. The adsorbent-filled column after adsorption is transported to the valuable metal recovery device 3, where the valuable metal is recovered as salt or the like by calcining the adsorbent filled with valuable metals.

Description

Technical Field

[0001] The present invention relates to a system for recovering valuable metals in wastewater, and particularly to a system for recovering valuable metals using an adsorbent capable of adsorbing the valuable metals to be recovered.

Background Art

[0002] Conventionally, valuable metals from which profit can be expected have been recovered, while valuable metals from which no profit can be expected have been discarded as industrial waste. However, due to the increasing expectations for building a circular economy and the rising value of valuable metals such as rare metals and precious metals, further reuse of valuable metals is desired.

[0003] As a method for recovering such valuable metals, Patent Document 1 discloses a process of contacting an adsorbent with a solution in which a precious metal is dissolved to adsorb precious metal ions in the solution to the adsorbent, and contacting a reducing agent with the precious metal ions adsorbed on the adsorbent to reduce the precious metal ions and desorb them from the adsorbent to form particles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, recovering valuable metals from wastewater containing valuable metals requires equipment to recover the valuable metals at each site where the wastewater is generated. This equipment requires both a wastewater treatment device that adsorbs or concentrates the valuable metals contained in the wastewater, and a valuable metal recovery device that recovers the adsorbed or concentrated valuable metals. However, when the amount of wastewater is small, or when wastewater is generated irregularly, such as at specific times, the initial investment burden of the valuable metal recovery device becomes large, and the operation and management of these devices also becomes necessary. Therefore, there is little business benefit for users (dischargers) who discharge wastewater containing valuable metals to recover the valuable metals, and this has been an obstacle to the progress of building a circular economy.

[0006] Therefore, it is conceivable that a user who discharges wastewater containing valuable metals could entrust the recovery of these valuable metals from the wastewater to a company capable of refining them. However, if the wastewater containing valuable metals were to be transported from the user's site to the metal refining company without any volume reduction, the concentration of valuable metals in the wastewater would be very low, resulting in a large volume of wastewater. This would lead to poor transport efficiency and extremely high transport costs, making it impractical.

[0007] This invention has been made in view of the above problems, and aims to provide a valuable metal recovery system using an adsorbent that is capable of adsorbing a target valuable metal and recovering the valuable metal. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides a system for recovering valuable metals from wastewater containing valuable metals, comprising: a wastewater treatment device having a column (adsorbent-packed column) packed with an adsorbent capable of adsorbing the valuable metals and being calcined or incinerated as a water treatment unit; and a valuable metal recovery device that recovers the adsorbed valuable metals by calcining or incinerating the adsorbent, wherein the adsorbent-packed column is detachable from the wastewater treatment device, and the valuable metals are recovered in the valuable metal recovery device after removing the adsorbent-packed column from the wastewater treatment device (Invention 1).

[0009] According to this invention (Invention 1), after adsorbing valuable metals from wastewater containing valuable metals using an adsorbent-packed column in a wastewater treatment device, the adsorbent-packed column can be detached from the wastewater treatment device, and the valuable metals can be recovered using a valuable metal recovery device. In this case, since the adsorbent-packed column is sufficiently reduced in volume for wastewater containing valuable metals in the wastewater treatment device, it can be easily transported after detachment, making it suitable for placing the wastewater treatment device for wastewater containing valuable metals and the valuable metal recovery device for recovering the valuable metals adsorbed on the adsorbent-packed column in different locations. Furthermore, since the valuable metal recovery device burns or incinerates the adsorbent, valuable metals can be recovered as compounds such as salts with fewer steps and simpler equipment. As a result, wastewater treatment and recovery of valuable metals can be performed separately from the source of the wastewater containing valuable metals.

[0010] In the above invention (Invention 1), it is preferable that the wastewater treatment device is composed of one or more water treatment units, and that the water treatment units are portable (Invention 2).

[0011] According to this invention (Invention 2), since the water treatment unit constituting the wastewater treatment device can be transported to the wastewater discharge point of a specific user, the user does not need to construct the wastewater treatment device as a fixed structure, and a valuable metal recovery system can be made that reduces the user's initial costs.

[0012] In the above invention (Invention 1), it is preferable that the wastewater treatment device and the valuable metal recovery device are located in different places (Invention 3).

[0013] According to this invention (Invention 3), since the adsorbent-filled column is detachable from the wastewater treatment device, by removing the adsorbent-filled column from the wastewater treatment device, the wastewater treatment device installed at the user's wastewater discharge point and the valuable metal recovery device can be located in different locations. By transporting the adsorbent-filled column to the installation location of the valuable metal recovery device, the system installed at the user's wastewater discharge point can be made into a wastewater treatment device, thereby reducing the space required on the user's side. Furthermore, by selecting the main recovery device using the valuable metal recovery device according to the valuable metal to be recovered, a suitable recovery process can be performed.

[0014] In the above invention (Invention 1), it is preferable to heat and calcine the adsorbent on which the valuable metal has been adsorbed in an oxidizing atmosphere (Invention 4).

[0015] According to this invention (Invention 4), the adsorbent is heated to volatilize the carbon, the valuable metal is recovered as a compound such as a salt, and this compound can be reused as a valuable metal by subjecting it to appropriate treatment.

[0016] In the above invention (Invention 1), it is preferable to fire or incinerate the adsorbent on which the valuable metal has been adsorbed at a temperature of 500°C to 900°C (Invention 5).

[0017] According to this invention (Invention 5), the adsorbent is heated to volatilize the carbon, the valuable metal is recovered as a compound such as a salt, and this compound can be reused as a valuable metal by subjecting it to appropriate treatment.

[0018] In the above invention (Invention 1), it is preferable that the adsorbent constituting the adsorbent-packed column is selected in accordance with the valuable metals contained in the wastewater (Invention 6).

[0019] According to the above invention (Invention 6), by selecting an adsorbent according to the valuable metal to be recovered, the valuable metal to be recovered can be selectively recovered.

[0020] In the above invention (Invention 3), it is preferable that the wastewater treatment device has, as a pretreatment device as a water treatment unit in the front stage of the adsorbent-filled column, a pretreatment device composed of one or more selected from sand filtration, activated carbon, coagulation filtration, coagulation sedimentation, coagulation pressurized flotation, and membrane filtration (Invention 7).

[0021] According to the above invention (Invention 7), by removing impurities, turbidity components, and substances that inhibit the recovery of valuable metals by the pretreatment device, the adsorption of valuable metals in the adsorbent-filled column can be effectively performed, thereby improving the recovery efficiency of valuable metals in the valuable metal recovery device.

[0022] In the above inventions (Inventions 1 to 7), the entity discharging the wastewater containing the valuable metal is different from the entity providing the wastewater treatment device, and it is preferable that the entity providing the wastewater treatment device calculates the wastewater treatment cost according to the market value and recovery amount of the valuable metal for each type of valuable metal (Invention 8).

[0023] According to the above invention (Invention 8), by calculating the wastewater treatment cost according to the type and recovery amount of the target valuable metal by the entity providing the wastewater treatment device, a specific user can recover valuable substances without owning either the wastewater treatment device or the valuable metal recovery device.

Effects of the Invention

[0024] According to the valuable metal recovery system of the present invention, when valuable metals are adsorbed by the adsorbent-packed column in the wastewater treatment device, the adsorbent-packed column can be desorbed and recovered in the valuable metal recovery device. Therefore, the wastewater treatment for adsorbing valuable metals from the wastewater containing valuable metals and the recovery treatment for recovering the valuable metals adsorbed on the adsorbent-packed column can be performed separately. Thereby, the recovery of valuable metals can be efficiently performed. Further, in the valuable metal recovery device, by heating and firing or incinerating the adsorbent, the valuable metals can be recovered as compounds such as salts, and the valuable metals can be recovered as compounds such as salts with fewer steps and simple equipment.

Brief Description of Drawings

[0025] [Figure 1] It is a schematic diagram showing the configuration of a valuable metal recovery system according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0026] Hereinafter, an embodiment of the valuable metal recovery system of the present invention will be described in detail with reference to the accompanying drawings.

[0027] [Valuable Metal Recovery System] For the valuable metal recovery system of this embodiment, for example, one having the configuration shown in FIG. 1 can be used.

[0028] In FIG. 1, the valuable metal recovery system 1 comprises a wastewater treatment device 2 and a valuable metal recovery device 3.

[0029] [Wastewater Treatment Device] The wastewater treatment device 2 consists of a tank 21 for storing wastewater W containing valuable metals, a coagulation and sedimentation tank 22 and a membrane filtration device 23 such as MF or UF as pretreatment means, and a valuable metal adsorption device 24, each comprising a water treatment unit. The valuable metal adsorption device 24 is equipped with a removable column (adsorbent-filled column) filled with an adsorbent that can adsorb valuable metals and can be calcined or incinerated. These water treatment units are assembled by installing the necessary equipment and piping on a pallet that can be loaded onto a transport means such as a trailer T, and are transported on one or more trailers T to the customer's wastewater discharge site containing valuable metals. They can then be unloaded from the trailers T or installed on-site while still mounted on the trailers T.

[0030] (Wastewater containing valuable metals) In this embodiment, examples of valuable metals to be recovered include, but are not limited to, Li, Rb, Cs, Ti, Mo, Ni, In, Cu, Co, Ga, and V. If two or more valuable metals are present in the wastewater W, only one type may be recovered, two or more types may be recovered separately, or two or more types may be recovered simultaneously. The valuable metals in the wastewater may be dissolved by immersion in water, acid, or alkali. Furthermore, the eluted water from the waste may also be used as wastewater W. In this case, the waste 25 may be immersed and washed in pure water to remove dirt and impurities, and then the valuable metals may be eluted from the waste using chemicals such as acid or alkali, and this eluted water may be used as wastewater W, or the eluted water may be added to the wastewater W. In this wastewater W, the valuable metals exist in an ionic state, and this method can be suitably applied to wastewater W with a concentration of 10 to 10000 mg / L.

[0031] (Pre-treatment means) In the coagulation and sedimentation tank 22 and the membrane filtration device 23, pretreatment is performed to remove suspended solids and coexisting substances that inhibit adsorption / extraction (rough removal) by solid-liquid separation. In addition to these, one or more pretreatment methods selected from sand filtration, activated carbon, coagulation filtration, and coagulation-pressurized flotation may be used.

[0032] (Valuable metal adsorption device) The valuable metal adsorption device 24 is configured to house one or more adsorbent-filled columns, each filled with an adsorbent capable of adsorbing valuable metals in the wastewater W containing the aforementioned valuable metals, in a series or parallel configuration that can be attached and detached. The shape and size of the adsorbent-filled columns can be appropriately selected according to the volume of wastewater W to be treated.

[0033] As for the adsorbent, there are no particular restrictions as long as it is capable of adsorbing valuable metals and can be calcined or incinerated. Ion exchange resins (cation exchange resins, anion exchange resins), chelate resins, etc., can be used, but are not limited to these.

[0034] Cation exchange resins adsorb ionic substances in wastewater by exchanging cations in the resin with cations in the wastewater. For example, they are suitable for adsorbing valuable metals such as Li, Rb, Cs, Ni, Cu, and Co, which exist as cations in solution. Anion exchange resins adsorb ionic substances in wastewater by exchanging anions in the resin with anions in the wastewater. For example, they are suitable for adsorbing metal ions that exist as oxoanions.

[0035] Chelate resins are resins that incorporate functional groups that form chelates (complexes) with specific metal ions. By forming chelates with the ions of valuable metals to be recovered, they can selectively adsorb valuable metal ions. Chelate resins with the most common iminodiacetic acid functional group are suitable for the adsorption of Cu, Ni, and Co.

[0036] The adsorbent can be appropriately selected and used depending on the valuable metal to be recovered, and an adsorbent-packed column can be constructed. It is preferable to use an adsorbent that exhibits a high partition coefficient with respect to the valuable metal to be recovered. Specifically, a partition coefficient of 100 mL / g (mg / mL-solution / mg / mL-adsorbent) or higher is preferable, and particularly 10,000 mL / g (mg / mL-solution / mg / mL-adsorbent) or higher is preferable. Such an adsorbent contains carbon components that volatilize upon calcination or incineration and non-volatilizing components that remain in the residue, such as sulfone groups (-SO3).- It is preferable that the functional groups include the following:

[0037] <Valuable Metal Recovery Equipment> The valuable metal recovery device 3 recovers the adsorbed valuable metals as compounds such as salts by heating or incinerating the adsorbent in the adsorbent-packed column that has adsorbed the valuable metals. Preferably, this valuable metal recovery device 3 is installed in a location separate from the wastewater treatment device 2 and receives and processes the adsorbent-packed column. This valuable metal recovery device 3 may be configured according to the valuable metals to be recovered.

[0038] [Methods for recovering valuable metals] Next, we will explain the method of recovering valuable metals using the valuable metal recovery system described above. <Wastewater storage process> First, wastewater W containing valuable metals to be treated is stored in tank 21. This wastewater W containing valuable metals may be wastewater discharged from various factories, or it may be leachate from waste discarded by various factories. In the case of leachate from waste, the waste is immersed and washed in pure water to remove dirt and impurities, and then the valuable metals are leached from the waste using chemicals such as acids or alkalis to obtain leachate. In this wastewater W, the valuable metals exist in an ionic state.

[0039] <Wastewater Treatment Process> (Pre-treatment process) As described above, the wastewater W containing valuable metals stored in tank 21 is transferred to coagulation and sedimentation tank 22 for coagulation and sedimentation treatment. This coagulation and sedimentation treatment removes suspended solids in the wastewater W and coexisting substances that inhibit adsorption / extraction (rough removal). Subsequently, a membrane filtration device 23 removes fine suspended solids contained in the wastewater W by filtration.

[0040] (Valuable metal adsorption process) The wastewater W, pre-treated in this manner, is then treated in a valuable metal adsorption device 24. In this valuable metal adsorption device 24, ionized valuable metals are adsorbed by an adsorbent. In this valuable metal adsorption process, an upper limit for the ion concentration of valuable metals in the treated water obtained by treating the wastewater W in the valuable metal adsorption device 24 is predetermined according to the ion concentration of valuable metals contained in the wastewater W to be treated, the amount of wastewater W to be treated, and the amount of adsorbent used in the adsorbent column of the valuable metal adsorption device 24. The SV of the wastewater W should then be set so that the ion concentration of valuable metals in the treated water W falls below this upper limit. Alternatively, the wastewater W may be circulated in the valuable metal adsorption device 24 until the ion concentration of valuable metals in the treated water falls below this predetermined upper limit.

[0041] In this case, it is preferable to provide the valuable metal adsorption device 24 with a means for measuring the amount of treated water, such as an integrated flow meter, and to replace the adsorbent column before the adsorbent breaks through. Furthermore, it is preferable to provide a means for measuring the concentration of valuable metals in the treated water of the valuable metal adsorption device 24, and to set a maximum standard value for the concentration of valuable ions in the treated water measured by the valuable metal concentration measuring means based on the concentration and amount of valuable metals in the wastewater W and the adsorption capacity of the adsorbent column. When the concentration of valuable metals in the treated water exceeds the maximum standard value, it is preferable to determine that the adsorbent is about to break through and replace the adsorbent column. By managing the replacement of the adsorbent column in this way, by transmitting the measured values ​​from the integrated flow meter and the valuable metal concentration measuring means to a remote receiver via a transmission means and managing this received data at a management facility, a stable valuable metal adsorption process can be stably carried out.

[0042] In this embodiment, the column filled with adsorbent (adsorbent-filled column) is detachable from the valuable metal adsorption device 24. Therefore, by removing it from the valuable metal adsorption device 24 and replacing it with a new column, processing can be resumed. In addition, the wastewater after adsorption of valuable metals may be returned to the existing wastewater treatment facility.

[0043] Through the valuable metal adsorption process described above, wastewater W with a valuable metal concentration of 10 to 10,000 mg / L can be reduced in volume to 0.01 to 10% of the wastewater volume W by treating it with an adsorbent having a distribution coefficient of 100 mL / g or more, particularly 10,000 mL / g or more, for the valuable metal.

[0044] (Valuable metal recovery process) Next, valuable metals are recovered from the adsorbent in the column removed from the valuable metal adsorption device 24. This recovery is performed by heating the adsorbent under conditions corresponding to the valuable metal to be recovered, thereby firing or incinerating it. In the case of firing, it is preferable to incinerate at a temperature and time such that the residual carbon concentration in the residue is 5% by weight or less, and particularly 1% by weight or less. Specifically, the firing temperature is preferably 500°C to 900°C, and particularly preferably less than 600 to 700°C. In addition, the oxygen concentration in the gas phase at the inlet of the incinerator is preferably 10 to 30% by volume, but an air atmosphere is also acceptable.

[0045] For example, by incinerating an ion exchange resin used as an adsorbent at around 600°C, the carbon components in the resin volatilize into the gas phase as CO2. Functional groups in the resin (e.g., sulfone groups (-SO3)) - )) and adsorbed valuable metals (M + Since it does not volatilize, salts such as M2SO4 remain as residue, so valuable metals can be recovered by removing the residue as an impurity as needed.

[0046] According to this embodiment as described above, the valuable metal adsorption process reduces the volume of the wastewater W containing valuable metals to approximately 0.01 to 10% by volume, making it easy to transport the adsorbent-filled column that is the target of the recovery process. Therefore, by transporting the column along with the valuable metals to a company that recovers them, processing can be performed at a location different from the wastewater treatment process.

[0047] The present invention has been described above with reference to the accompanying drawings and based on the embodiments described above. However, the present invention is not limited to the embodiments described above, and various modifications are possible. For example, in the above embodiments, the valuable metal was recovered as a salt, but it can also be recovered as a compound such as an oxide of the valuable metal by heating. [Examples]

[0048] The present invention will be described in more detail by the following specific examples.

[0049] [Example 1] For the purpose of recovery, wastewater W containing 8000 mg / L of cesium (Cs), a valuable metal that behaves as a cation in wastewater, was prepared as simulated raw water. 400 mL of this raw water was passed through a column (Φ=20 mm) packed with 10 g of strongly acidic cation exchange resin as an adsorbent in a downward flow. The breakthrough point was defined as the point when the concentration of the target valuable metal in the treated water after adsorption reached 10% of the concentration of the target valuable metal in the raw water.

[0050] A strongly acidic cation exchange resin containing adsorbed valuable metals was calcined at 600°C in an air atmosphere. The residue after calcination was collected and its composition was analyzed.

[0051] At the breakthrough point, the highly acidic cation exchange resin contained approximately 200 mg / g of valuable metals in the adsorbent (approximately 20% by weight). Since the valuable metal content in the raw water was 8000 mg / L (0.8% by weight), it was confirmed that the valuable metals were concentrated 25 times in the adsorbent compared to the raw water. This confirmed that transporting the adsorbent required 1 / 25th the volume of transporting the raw water.

[0052] Analysis of the residue after calcination confirmed that it consisted of sulfates (Cs2SO4) derived from the target valuable metal ions and sulfate ions from the sulfone groups of the strongly acidic cation exchange resin. [Explanation of symbols]

[0053] 1. Valuable Metal Recovery System 2. Wastewater treatment equipment 21 tanks 22 Coagulation and sedimentation tank (pretreatment means) 23 Membrane filtration apparatus (pretreatment means) 24 Valuable metal adsorption equipment 25 Waste 3. Valuable metal recovery equipment W Wastewater containing valuable metals T-trailer (transportation method)

Claims

1. A system for recovering valuable metals from wastewater containing valuable metals, A wastewater treatment apparatus having a column (adsorbent-packed column) filled with an adsorbent capable of adsorbing the aforementioned valuable metals and being calcined or incinerated, as a water treatment unit, The system includes a valuable metal recovery device that recovers the adsorbed valuable metal by firing or incinerating the adsorbent, A valuable metal recovery system comprising: an adsorbent-packed column that is detachable from the wastewater treatment device; the adsorbent-packed column being removed from the wastewater treatment device and valuable metals being recovered in the valuable metal recovery device.

2. The valuable metal recovery system according to claim 1, wherein the wastewater treatment device is composed of one or more water treatment units, and the water treatment units are portable.

3. The valuable metal recovery system according to claim 1, wherein the wastewater treatment device and the valuable metal recovery device are provided in different locations.

4. The valuable metal recovery system according to claim 1, wherein the adsorbent on which the valuable metal has been adsorbed is heated and calcined in an oxidizing atmosphere.

5. The valuable metal recovery system according to claim 1, wherein the adsorbent on which the valuable metal has been adsorbed is fired or incinerated at a temperature of 500°C to 900°C.

6. The valuable metal recovery system according to claim 1, wherein the adsorbent constituting the adsorbent-packed column is selected in accordance with the valuable metals contained in the wastewater containing valuable metals.

7. The valuable metal recovery system according to claim 3, wherein the wastewater treatment device has a pretreatment device consisting of one or more selected from sand filtration, activated carbon, coagulation filtration, coagulation sedimentation, coagulation pressurized flotation, and membrane filtration as a water treatment unit prior to the adsorbent-packed column.

8. A valuable metal recovery system according to any one of claims 1 to 7, wherein the entity that discharges the wastewater containing the valuable metal is different from the entity that provides the wastewater treatment equipment, and the entity that provides the wastewater treatment equipment calculates the wastewater treatment cost for each type of valuable metal according to the market value and amount recovered of the valuable metal.

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