Method for separating residual leachate from the surface of a lump-like material

Abstract

To provide a method for separating a remaining leaching solution on a surface of a lump material, which is intended to reduce the amount of the remaining leaching solution.SOLUTION: A method for separating a remaining leaching solution on the surface of a lump material includes: a leaching step of leaching a leaching object in a leaching solution by bringing the lump material having the leaching object on at least the surface thereof into contact with the leaching solution in which the leaching object is leached; and a hydrophobic liquid replacement step of bringing the lump material after the leaching object is leached in the leaching step into contact with a hydrophobic liquid so as to replace the leaching solution remaining on the surface of the lump material with the hydrophobic liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a method for separating residual leachate from the surface of a lumpy material. [Background technology]

[0002] The permissible limits for copper (Cu) and tungsten (Sn), which are examples of trump elements, in steel products are low. In particular, in deep-drawn steel sheets and tinplate steel sheets, the permissible limits are the lowest, at 0.06 mass% or less for Cu and 0.010-0.02 mass% or less for Sn, as they can lead to cracking.

[0003] On the other hand, scrap is one of the sources of iron. According to the unified standards for inspection and acceptance of iron scrap, heavy scrap is distinguished by its thickness, size, and weight, and is classified into HS, H1 to H5, etc. The Cu content in H2 and H3 in aged waste scrap is higher than that of HS and H1, at 0.3 to 0.4% (estimated value), which is almost the same as the permissible limit for structural steel and steel bars. Furthermore, according to the unified standards for inspection and acceptance of iron scrap, the thickness of H2 and H3 is thinner than that of HS and H1, and there is a high possibility that surface treatment using other trump elements such as nickel, zinc, and tin has been performed, and it is thought that the total trump element content in H2 and H3 is even higher. In order to utilize waste scrap (H2 and H3) with a high content of trump elements as an iron source, we believe that technology to separate trump elements from scrap will be necessary in the future.

[0004] In response to this situation, among the trump element separation technologies, it is known that in the wet process, using ammonia or other substances, trump elements such as Cu, Ni, and Zn, which exist on the scrap surface or individually, can be leached and separated using ammine complexes. However, because a high-concentration ammonia leaching solution is used, the scrap must be washed with water after processing. In addition, wastewater treatment or replenishment of chemicals is required. Therefore, due to the high cost, it has not been put into practical use.

[0005] In contrast, regarding the separation of Cu, Zn, and Ni from agglomerate materials (such as scrap) by a wet process, a method for controlling the leaching process in the ammonia leaching step and a method for regenerating the ammonia leaching solution, utilizing ammonia and hydrogen sulfide contained in raw COG, has been disclosed (Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2018-178201 [Overview of the project] [Problems that the invention aims to solve]

[0007] When the lumps remaining after leaching the target material into the leachate (a leachate containing leaching agents such as ammonium salts) are discharged from the leachate, the leachate adheres to the lumps. Handling the lumps with leachate attached can lead to problems such as corrosion of equipment in subsequent processes, so it was necessary to wash the leachate-contaminated lumps with water. This washing necessitates wastewater treatment, increasing wastewater treatment costs. In addition, some of the expensive leachate is mixed into the wastewater and discharged, increasing chemical costs. This problem is a common challenge in wet processes.

[0008] Therefore, the object of this disclosure is to provide a method for separating residual leachate from the surface of a lump-like material that reduces the amount of residual leachate. [Means for solving the problem]

[0009] The means for solving the problem include the following aspects: <1> A leaching step in which a mass having at least the substance to be leached on its surface is brought into contact with a leachate from which the substance to be leached is leached, and the substance to be leached is leached into the leachate, A hydrophobic liquid replacement step is performed in which the lump, after the leaching of the target material in the leaching step, is brought into contact with a hydrophobic liquid, and the leaching liquid remaining on the surface of the lump is replaced with the hydrophobic liquid. A method for separating residual leachate from the surface of a lump-like material having [a certain characteristic]. <2> In the hydrophobic liquid replacement step, the lump is immersed in the hydrophobic liquid. <1> A method for separating residual leachate from the surface of a lump-like material as described above. <3> The density of the hydrophobic liquid is different from the density of the leachate from which the object to be leached was extracted. <1> or <2> A method for separating residual leachate from the surface of a lump-like material as described above. <4> The density of the hydrophobic liquid is greater than the density of the leachate from which the object to be leached was extracted. <3> A method for separating residual leachate from the surface of a lump-like material as described above. <5> The difference between the density of the hydrophobic liquid and the density of the leachate from which the object to be leached was extracted is 0.05 g / cm³. 3 That's all. <3> or <4> A method for separating residual leachate from the surface of a lump-like material as described above. <6> The process further includes a residual hydrophobic liquid removal step, in which the aggregate after the hydrophobic liquid replacement step is heated to remove any remaining hydrophobic liquid from the surface of the aggregate by volatilization. <1> ~ <5> A method for separating residual leachate from the surface of a lump-like material as described in any one of the items. <7> In the hydrophobic liquid replacement step, vibration or ultrasonic waves are applied to the lump. <1> ~ <6> A method for separating residual leachate from the surface of a lump-like material as described in any one of the items. <8> In the hydrophobic liquid replacement step, after replacing the leachate remaining on the surface of the lump with the hydrophobic liquid, the leachate that has floated or settled in the hydrophobic liquid is separated, and then the lump is removed from the hydrophobic liquid. <1> ~ <7> A method for separating residual leachate from the surface of a lump-like material as described in any one of the items. <9> The hydrophobic liquid replacement step is performed multiple times. <1> ~ <8> A method for separating residual leachate from the surface of a lump-like material as described in any one of the items. <10> The method for separating residual leachate on the surface of the agglomerate according to any one of <1> to <9>, wherein the boiling point of the hydrophobic liquid at normal pressure is 40°C to 95°C. <11> The method for separating residual leachate on the surface of the agglomerate according to any one of <1> to <10>, wherein the hydrophobic liquid contains a surfactant.

Advantages of the Invention

[0010] According to the present disclosure, a method for separating residual leachate on the surface of an agglomerate that reduces the amount of residual leachate can be provided.

Brief Description of the Drawings

[0011] [Figure 1] It is a process diagram of an example of the method for separating residual leachate on the surface of the agglomerate of the present disclosure. [Figure 2] It is a schematic diagram for explaining the action of the surfactant in the method for separating residual leachate on the surface of the agglomerate of the present disclosure. [Figure 3] It is a schematic diagram for explaining the method for separating residual leachate on the surface of the agglomerate implemented in Example 1.

Modes for Carrying Out the Invention

[0012] Hereinafter, an example of the present disclosure will be described. In this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In a numerically defined range described stepwise, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of another numerically defined range described stepwise. In a numerical range, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples. <id= The term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved. "Combination of preferred embodiments" is a more preferred embodiment. <id=

[0013] The method for separating residual leachate from the surface of a mass (hereinafter also simply referred to as the "residual leachate separation method") described herein is: A leaching process in which a mass having at least the substance to be leached on its surface is brought into contact with a leachate from which the substance to be leached is extracted, and the substance to be leached is extracted into the leachate, A hydrophobic liquid replacement step is performed in which the lump, after the leaching of the target material in the leaching step, is brought into contact with a hydrophobic liquid, and the leaching liquid remaining on the surface of the lump is replaced with the hydrophobic liquid. It has.

[0014] In the residual leachate separation method of this disclosure, the leachate remaining on the surface of the aggregate after the leaching process has been performed is replaced with a hydrophobic liquid, thereby removing the leachate that remained on the surface of the aggregate. As a result, the amount of residual leachate remaining on the surface of the aggregate can be reduced.

[0015] The details of the residual leachate separation method described herein are explained below.

[0016] <Overall Process> The residual leachate separation method of this disclosure comprises a leaching step, a hydrophobic liquid replacement step, and a residual hydrophobic liquid removal step. The residual hydrophobic liquid removal step is an optional step that may be performed as needed.

[0017] The transport of lumpy materials between each process is carried out by methods such as transport using baskets, transport using electromagnets, or transport using belts (including the transport of buckets containing lumpy materials by belt).

[0018] The lumps targeted for each process are those that cannot be stirred even when immersed in the leachate and agitated with a stirrer; in other words, lumps that do not become slurry. For example, depending on the density of the lumps, these are lumps that are 5 mm or larger in size. Examples of bulky materials include scrap, ore, and waste electronic materials. Examples of scrap include home appliance scrap, automobile scrap, industrial machinery scrap, building scrap, beverage cans, and other metal fragments. Examples of ores include copper ore, nickel ore, zinc ore, uranium ore, and chromium ore. Examples of waste electronic materials include electronic circuit boards and batteries.

[0019] <Leaching process> In the leaching process, a mass having at least the material to be leached on its surface is brought into contact with the leachate from which the material to be leached is extracted, thereby leaching the material into the leachate. In the leaching process, it is advisable to conduct a leaching test on the material to be leached beforehand to determine the selection of the leaching solution, its concentration, temperature, and dissolved oxygen concentration.

[0020] The exudate is an aqueous solution containing the exudant and water. Based on the characteristics of the exudating agent, exudation methods can be classified into chemical exudations such as acid exudation, alkaline exudation, and exudation using complexing agents, and bacterial exudation, which utilizes an exudate containing microorganisms (bacteria).

[0021] In acid leaching, acids such as hydrochloric acid and sulfuric acid are used as leaching agents. The materials to be leached are metals or metal oxides such as Fe, Ni, Zn, Al, Ca, and Mg. The pH and temperature of the leaching solution are adjusted according to the metal oxide being leached. The pH of the leaching solution is often 2 or lower.

[0022] In alkaline leaching, alkalis such as sodium hydroxide and potassium hydroxide are used as leaching agents. The materials to be leached are, for example, amphoteric metals or amphoteric metal oxides such as Zn, Al, Sn, Cd, Pb, and Hg. The pH and temperature of the leaching solution are adjusted according to the type of amphoteric metal oxide being leached. The pH of the leaching solution is often 11 or higher.

[0023] In leaching using a complexing agent, the leaching agent can be, for example, NH3, CN -Compounds containing these elements (such as ammonium carbonate, ammonium sulfate, and sodium cyanide) are used. Examples of materials to be leached include Cu(II), Ni(II), Zn(II), Co(II), Au(I), and Ag(I). The pH, temperature, and complex ion concentration of the leaching solution are adjusted according to the elements of the material being leached.

[0024] In leaching using a complexing agent, for example, when NH3 is added to the leaching solution as a ligand for the complex ion to leach metallic copper from a lump, the NH3 concentration in the leaching solution should be 20-100 g / l at a pH of 9.5-12 in a sealed container. In addition, to oxidize the metallic copper, the oxygen concentration in the gas phase at the top of the leaching solution should be controlled to be above a certain value. By doing so, the oxygen concentration in the leaching solution is raised above a certain value, and the metallic copper is oxidized or leached out. + Ions Cu 2+ The copper is oxidized to ions, and then to stable ammine complex copper. Note that when metallic copper is leached from a lump in a sealed container without oxygen supply, the leaching of metallic copper will continue until almost all dissolved oxygen in the leachate and oxygen in the gas phase are depleted. Next, to regenerate the leachate containing dissolved copper ions, one method is to precipitate the ammine complex copper in the leachate as copper sulfide. In this process, a sulfidating agent (such as a liquid containing sulfide ions or a gas containing hydrogen sulfide) is added to or aerated into the leachate, converting the ammine complex copper into stable copper sulfide for precipitation. By performing this solid-liquid separation operation, the leachate with a reduced copper ion concentration can be recovered and reused. Furthermore, by measuring the oxidation-reduction potential of the leachate during the process, the addition of excessive sulfidating agents can be suppressed.

[0025] In bacterial leaching, bacteria such as sulfur-oxidizing bacteria and iron-oxidizing bacteria are used as leaching agents. Examples of materials to be leached include pyrite (FeS2), chalcopyrite (CuFeS2), sphalerite (ZnS), and galena (PbS). The leaching solution is often acidic, with a pH of 3 or lower. In bacterial leaching, for example, low-grade ores such as pyrite and chalcopyrite (low-grade ores containing only a few percent of sulfides) are brought into contact with a leachate under oxygen-supplied conditions, and bacteria oxidize the sulfur components, leaching out metallic elements such as Fe, Cu, and Zn. Bacteria such as sulfur-oxidizing bacteria and iron-oxidizing bacteria can either directly oxidize sulfur compounds or indirectly oxidize them through trivalent iron ions produced when divalent iron ions are oxidized. Therefore, leachates containing bacteria can be reused.

[0026] In the leaching process, there are no particular limitations on the method of bringing the lump material into contact with the leachate. Examples include immersing the lump material in the leachate, spraying the leachate onto the lump material, and repeatedly bringing the lump material into contact with the leachate. One example of a method for immersing a lump in leachate is to immerse the lump in leachate contained in a leachate tank. One example of a method for spraying leachate onto a mass is to spray it onto a pile of masses stacked in a yard. Examples of methods for repeatedly bringing leachate into contact with the lumpy material include immersing the lumpy material in a leachate tank while circulating the leachate, and spraying leachate onto a pile of lumpy material in a yard, and then collecting and circulating the sprayed leachate. Among these methods, from the viewpoint of efficient leaching of the target material, it is preferable to use a method of immersing the lump material in the leachate when bringing the lump material into contact with the leachate.

[0027] <Hydrophobic liquid replacement process> In the hydrophobic liquid replacement process, the aggregate that has been leached in the leaching process is brought into contact with a hydrophobic liquid, and the leached liquid remaining on the surface of the aggregate is replaced with the hydrophobic liquid.

[0028] In the hydrophobic liquid replacement process, it is advisable to consider methods that facilitate the replacement of leachate adhering to the surface of the aggregate with the hydrophobic liquid beforehand. For example, it is advisable to consider methods of contact between the aggregate and the hydrophobic liquid, methods of vibrating the aggregate during contact with the hydrophobic liquid, and methods of applying vibration. Among the methods considered, operations that facilitate the replacement of the hydrophobic liquid should be applied to the hydrophobic liquid replacement process.

[0029] In the hydrophobic liquid replacement step, it is preferable to replace the leachate remaining on the surface of the lump with a hydrophobic liquid, separate the leachate that has floated or settled in the hydrophobic liquid, and then remove the lump from the hydrophobic liquid. Since hydrophobic liquids and leachates (aqueous solutions) are poorly compatible, the leachate and hydrophobic liquid can be separated by phase separation, such as by standing or centrifugation. The separated leachate can then be extracted and reused.

[0030] A hydrophobic liquid is a liquid that possesses hydrophobic properties, that is, a liquid with low affinity for water (it is poorly soluble in water or poorly miscible with water). For example, a hydrophobic liquid should ideally have a solubility in water at room temperature (25°C) of 0 g / L or more and 10.0 g / L or less (preferably 0 g / L or more and 5.0 g / L or less). Low solubility in water allows for efficient replacement of the leachate with the hydrophobic liquid. Furthermore, it facilitates the separation of the hydrophobic liquid from the leachate, making it easier to extract the leachate.

[0031] Note that "hydrophobic" refers to properties that include lipophilicity. Hydrophobic liquids may be, for example, hydrophobic organic solvents or various oils.

[0032] The solubility of a hydrophobic liquid in water should be determined using the solubility figures published by the manufacturer of the hydrophobic liquid. However, if these figures are not published, the solubility of the hydrophobic liquid in water should be measured as follows: Add 15 mL each of water and hydrophobic liquid to 50 mL stoppered centrifuge tubes and shake them at 150 times / minute for 1 hour in a 25°C constant temperature bath. Then, centrifuge the mixture (1,750 G, 5 minutes) and let the mixture stand in a 25°C constant temperature bath for about 1 hour. Next, take an arbitrary amount of the aqueous phase and measure the amount of solvent in the water by gas chromatography-mass spectrometry (GC / MS). This determines the solubility of the hydrophobic liquid in water.

[0033] It is preferable that the density of the hydrophobic liquid differs from the density of the leachate from which the material to be leached has been extracted. The difference in density between the hydrophobic liquid and the leachate facilitates separation operations such as standing or centrifugation. This reduces the amount of residual leachate from lumpy material. The density of the hydrophobic liquid may be less or greater than the density of the leachate from which the material to be leached has been extracted. However, from the viewpoint of easily recovering the leachate, it is preferable that the density of the hydrophobic liquid be greater than the density of the leachate from which the material to be leached has been extracted, as it is simpler to recover the leachate from the supernatant when the hydrophobic liquid and leachate are allowed to stand. This is because the leachate separated from the surface of the mass floats in the hydrophobic liquid and accumulates on the surface of the hydrophobic liquid.

[0034] Here, the density of the hydrophobic liquid and the density of the leachate containing the extracted material are almost never exactly the same, and therefore, phase separation can be achieved by separation operations such as standing or centrifugation. However, the greater the difference between the density of the hydrophobic liquid and the density of the leachate containing the extracted material, the easier phase separation becomes. 3 The above is preferable, 0.1 g / cm³ 3 The above is preferable. The upper limit of the density difference depends on the hydrophobic liquid selected, but is 0.8 g / cm³. 3 It is to that extent.

[0035] Furthermore, the depth to which the lump is immersed can be freely changed by storing it in a basket or the like, so the density of the lump may be less or greater than the density of the hydrophobic liquid and the density of the leachate from which the object to be leached has been extracted. However, when immersing the lump in a hydrophobic liquid without using a storage device such as a basket, from the viewpoint of easily immersing the lump, it is preferable that the density of the lump be greater than the density of the hydrophobic liquid and the density of the leachate from which the object to be leached has been extracted, and it is preferable that the density be in the order of decreasing density: lump, hydrophobic liquid, and the leachate from which the object to be leached has been extracted.

[0036] The density is measured as follows: The specific gravity of liquids such as leachates is measured using a hydrometer. The specific gravity of lumps and other solid materials is determined by placing a graduated cylinder filled with pure water on a weighing machine, immersing the lump in the pure water inside the cylinder, and calculating the density from the increased volume difference and weight difference.

[0037] Preferably, the boiling point of the hydrophobic liquid is lower than the boiling point of the leachate under the same pressure conditions, and higher than the operating temperature of the hydrophobic liquid at the pressure during the hydrophobic liquid replacement process.

[0038] For example, when the temperature of the leachate is at room temperature (25°C), the boiling point of the hydrophobic liquid is preferably 40°C or higher and less than 200°C under the same pressure conditions. The upper limit of the boiling point is more preferably less than 100°C, and even more preferably 95°C or lower. When the temperature of the leachate is greater than 100°C and less than 150°C, the boiling point of the hydrophobic liquid is preferably 30 to 100°C higher than that of the leachate. Specifically, when the process is carried out at room temperature (25°C) and atmospheric pressure, the boiling point of the hydrophobic liquid is preferably 40°C to 95°C at atmospheric pressure. By setting the boiling point of the hydrophobic liquid within the above range, the hydrophobic liquid becomes easier to remove by volatilization and easier to separate from the lumpy material. As a result, the energy cost of removing the hydrophobic liquid from the lumpy material in the residual hydrophobic liquid removal process can be reduced.

[0039] Furthermore, it is preferable that the heat of vaporization of the hydrophobic liquid is smaller than that of water. In this case, the hydrophobic liquid is easier to remove by volatilization in the residual hydrophobic liquid removal process, and easier to separate from the lumpy material. As a result, the energy cost of removing the hydrophobic liquid from the lumpy material in the residual hydrophobic liquid removal process can be reduced.

[0040] There are no particular restrictions on hydrophobic liquids as long as they meet the above conditions. Examples of hydrophobic liquids include chlorine-based hydrophobic liquids (trichloroethylene, tetrachloroethylene, dichloromethane, etc.), fluorine-based hydrophobic liquids (dichloropentafluoropropane (HCFC), hydrofluorocarbon (HFC), hydrofluoroether (HFE), 1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane, etc.), bromine-based hydrophobic liquids (1-bromopropane, etc.), creosote oil, nitrobenzene, carbon disulfide, chlorobenzene, n-hexane, n-pentane, kerosene, etc.

[0041] The following shows the physical properties of an example of an applicable hydrophobic liquid. [Table 1]

[0042] In the hydrophobic liquid displacement process, from the viewpoint of efficiently applying the displacement effect of the hydrophobic liquid, it is preferable that the amount of hydrophobic liquid added to the mass be set to be greater than or equal to the amount to which the mass is immersed in the hydrophobic liquid.

[0043] In the hydrophobic liquid replacement process, the method of bringing the aggregate into contact with the hydrophobic liquid is not particularly limited. Examples include immersing the aggregate in the hydrophobic liquid, spraying the hydrophobic liquid onto the aggregate, and repeatedly bringing the aggregate into contact with the hydrophobic liquid. One example of a method for immersing a lump in a hydrophobic liquid is to immerse the lump in a hydrophobic liquid contained in a hydrophobic liquid replacement container. One example of a method for spraying a hydrophobic liquid onto a mass is to spray it onto a pile of masses stacked in a yard. Examples of methods for repeatedly bringing a hydrophobic liquid into contact with a mass include immersing the mass in a hydrophobic liquid while circulating the hydrophobic liquid contained in a hydrophobic liquid replacement container, and spraying a hydrophobic liquid onto a pile of masses in a yard, and then recovering and circulating the sprayed hydrophobic liquid. Among these methods, from the viewpoint of efficient displacement of the hydrophobic liquid, it is preferable to use a method of immersing the lump in the hydrophobic liquid when bringing the lump into contact with the hydrophobic liquid.

[0044] (A preferred embodiment of the hydrophobic liquid replacement process when the surface layer of a lump is hydrophilic and a large amount of leachate adheres to the surface.) If a lump is metal scrap and part of its metal surface is rusted, the rusted area becomes highly hydrophilic. Also, many ores, which are examples of lumps, are oxides and are often highly hydrophilic. When the surface of a lump is highly hydrophilic in this way, the amount of leachate adhering to the surface increases, and simply replacing the leachate in the free water and pore water regions with a hydrophobic liquid may be insufficient. In such cases, it is preferable to adopt one of the following methods. (1) Method of performing the hydrophobic liquid replacement step multiple times (2) A method of applying vibration or ultrasonic waves to a lump in the hydrophobic liquid replacement step. (3) Method of applying a hydrophobic liquid containing a surfactant

[0045] By performing the hydrophobic liquid replacement process multiple times, the lumps come into contact with each other, removing the leachate remaining on the surface of the lumps and replacing it with a hydrophobic liquid, thereby reducing the amount of leachate remaining on the surface of the lumps.

[0046] When a mass is vibrated, it comes into contact with other masses, which removes the leachate remaining on the surface of the masses and replaces it with a hydrophobic liquid, thereby reducing the amount of leachate remaining on the surface of the masses. Methods for applying vibration to a lump include striking it with a hammer, applying vibration by magnetizing and demagnetizing an electromagnet, applying vibration by stirring, and spraying a hydrophobic liquid into a hydrophobic liquid.

[0047] When ultrasound is applied to a mass, the shock waves or other forces strongly mix the leachate remaining on the surface of the mass with the surrounding hydrophobic liquid, thereby removing the leachate from the surface and replacing it with the hydrophobic liquid, thus reducing the amount of leachate remaining on the surface of the mass. The ultrasound can be applied continuously or intermittently.

[0048] When a hydrophobic liquid containing a surfactant is applied, the hydrophilic groups of the surfactant adsorb onto the hydrophilic parts of the aggregate surface, and the hydrophobic groups of the surfactant change the surface to hydrophobic, making it easier to remove the leachate remaining on the surface of the aggregate (see Figure 2). As a result, the leachate can be efficiently replaced with a hydrophobic liquid, and the amount of leachate remaining on the surface of the aggregate can be reduced. Furthermore, applying an leachate containing a surfactant can reduce or completely remove the amount of leachate accompanying the lumps when moving them from the leachate process to the hydrophobic liquid replacement process. It can also reduce or completely remove the contamination of the hydrophobic liquid with components from the leachate.

[0049] In Figure 2, 10 represents a lump, 12 represents an leachate, 14 represents a hydrophobic liquid, 16 represents a surfactant, 16A represents the hydrophilic group of the surfactant, and 16B represents the hydrophobic group of the surfactant.

[0050] Here, surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. One type of surfactant may be used, or two or more types may be mixed and used. The surfactant is preferably one that is stable at the temperature of the hydrophobic liquid in the hydrophobic liquid substitution step and whose functional group portion is ionized at the pH of the leachate. The surfactant is preferably one that dissolves in the hydrophobic liquid at a concentration of 1 mg / L or more at the temperature of the hydrophobic liquid during the hydrophobic liquid substitution step, and more preferably one that dissolves at a concentration of 1 g / L or more.

[0051] The surfactant should be evaluated and selected based on factors such as the surface properties of the aggregate, solubility in hydrophobic liquids, temperature of the leachate, and pH of the leachate. Examples of evaluation methods include the following: First, a small sample of the target mass is immersed in the leachate, and then transferred to a transparent, sealed glass container containing a hydrophobic liquid with a surfactant adjusted to a predetermined concentration. Next, the sealed glass container is shaken, left to stand, and the surface of the mass is observed for evaluation. Specifically, if leachate remains on the surface of the aggregate, an interface is formed between it and the hydrophobic liquid, distorting the appearance of the aggregate's surface. If no leachate remains on the aggregate's surface, no interface is formed with the hydrophobic liquid, and the aggregate's surface can be clearly seen. Alternatively, as shown in Example 3, a small sample of the aggregate may be used to evaluate the amount of residual leachate, and an appropriate surfactant may be selected.

[0052] <Removal process of residual hydrophobic liquid> In the residual hydrophobic liquid removal process, the aggregate after the hydrophobic liquid replacement process is heated to volatilize and remove any hydrophobic liquid remaining on the surface of the aggregate.

[0053] In the residual hydrophobic liquid volatilization process, a heat source such as steam or an electric heater is used to raise the temperature of the hydrophobic liquid remaining on the surface of the aggregate above its boiling point. In the case of steam, for example, indirect heating or direct heating by direct blowing can be performed. When direct blowing is performed, the heating rate can be increased, and at the same time, any leachate remaining on the surface of the mass can be washed away with water generated by the steam. Furthermore, it is preferable to cool the evaporated hydrophobic liquid to liquefy it and reuse it in the hydrophobic liquid replacement process. [Examples]

[0054] The present disclosure will be described in more detail below with reference to examples. However, these examples are not intended to limit the present disclosure.

[0055] (Example 1) Following the leaching process using the lump and leachate as shown in Table 2, a hydrophobic liquid replacement process is carried out using a hydrophobic liquid to separate the leachate adhering to the surface of the lump, and the residual leachate is removed. The elution amount was adjusted (see Figure 3). Specifically, it was done as follows. However, in the comparative example, the hydrophobic liquid replacement step was not performed. In Figure 3, 100 represents the lump, 102 the leachate, 104 the leachate container, 106 the basket, 108 the hydrophobic liquid, 110 the container for replacing with the hydrophobic liquid, 112 the pure water, and 114 the container for washing with water.

[0056] A lump (350-500g) was placed in a basket with many holes, and the basket was immersed in an extractant (1L) in an extractant container (sealed container) to extract the target substance from the lump. Next, after immersion for 10-60 minutes, the basket containing the lumps was immersed for 1 minute in a hydrophobic liquid (1 L) in a hydrophobic liquid replacement container (sealed container) to separate the leachate adhering to the surface of the lumps. Next, the basket containing the lumps was removed from the hydrophobic liquid replacement container and immersed in a water washing container containing pure water (1L) to measure the residual leachate. The leachate remaining on the surface of the lumps was washed with pure water to obtain a washing solution.

[0057] Subsequently, the concentrations of the tracer components listed in Table 2 in the washing solution were measured, and the amount of residual leachate per unit area adhering to the surface of the aggregate removed from the hydrophobic liquid storage container was calculated from these concentrations. Furthermore, when calculating the amount of residual leachate per unit area, the basket was operated independently to measure the amount of residual leachate per unit area and correct the calculation. The results are as follows.

[0058] In Comparative Example 1-1, Examples 1-2 to 1-5, and Example 1-14, copper-contaminated scrap was used, and the leachate was prepared as an aqueous solution of ammonium sulfate adjusted to pH 10.5 with sodium hydroxide. The effects of hydrophobic liquid substitution with various hydrophobic liquids were then investigated. As a result, the amount of residual leachate could be reduced by 55-77% by hydrophobic liquid substitution.

[0059] In Comparative Examples 1-6 and Examples 1-7, the effect of hydrophobic liquid substitution with 1-bromopropane was investigated using Sn-plated scrap as the leachate, with a sodium hydroxide aqueous solution as the leachate. As a result, the amount of residual leachate could be reduced by 68% by hydrophobic liquid substitution.

[0060] In Comparative Examples 1-8 and Examples 1-9, the effect of hydrophobic liquid substitution with 1-bromopropane was investigated using Sn-plated scrap as the leaching agent, with potassium hydroxide aqueous solution as the leaching agent. As a result, the amount of residual leaching could be reduced by 54% by hydrophobic liquid substitution.

[0061] In Comparative Examples 1-10 and Examples 1-11, copper ore was used as the target, and the leachate was adjusted to a sulfuric acid aqueous solution with a pH of 0.5. The effect of hydrophobic liquid displacement with 1-bromopropane was investigated. Sodium chloride was added to the leachate as a tracer at a concentration of 1 g / L in the sulfuric acid aqueous solution. As a result, the amount of residual leachate was reduced by 47% by hydrophobic liquid displacement.

[0062] In Comparative Examples 1-12 and Examples 1-13, nickel laterite ore was used as the target, and the leachate was adjusted to a pH of 0.4 using hydrochloric acid to create an aqueous hydrochloric acid solution. The effect of hydrophobic liquid displacement with 1-bromopropane was then investigated. Sodium chloride was added to the leachate as a tracer at a concentration of 1 g / L in the sulfuric acid aqueous solution. As a result, the amount of residual leachate was reduced by 53% through hydrophobic liquid displacement.

[0063] From the above, it was found that hydrophobic liquid displacement can reduce the amount of leachate remaining on the surface of the aggregate. While we have discussed the effect of hydrophobic liquid replacement in reducing the amount of residual leachate in lumps after chemical leaching due to chemical reactions, it can be seen that the same effect of hydrophobic liquid replacement can be expected in lumps after bacterial leaching using microorganisms.

[0064] [Table 2]

[0065] (Example 2) - Comparative Example 2-1- In Comparative Example 2-1, 350 g of copper-containing scrap with magnetic properties as a lump was used to perform a leaching step and a hydrophobic liquid replacement step. Specifically, it is as follows. First, the copper-containing scrap was immersed in a leaching solution (1 L of an aqueous ammonium sulfate solution at 100 g / L, adjusted to pH 10.5 with sodium hydroxide) in a leaching container (sealed container) using an electromagnet for 60 minutes to leach the copper component, which is the object to be leached, from the copper-containing scrap. Next, the copper-containing scrap was taken out of the leaching solution by an electromagnet and immersed in a water washing container containing pure water (1 L) to wash the leaching solution remaining on the surface of the copper-containing scrap in pure water, and a washing solution was obtained. After that, the sulfate ion concentration in the washing solution was measured, and from that concentration, the amount of residual leaching solution per unit area adhering to the surface of the copper scrap taken out from the leaching container was calculated, and it was 103 mL / m 2 resulted.

[0066] - Example 2-2- In Example 2-2, in Comparative Example 2-1, after the copper-containing scrap was taken out of the leaching solution by an electromagnet, it was immersed in a hydrophobic liquid (1-bromopropane, 1 L) in a hydrophobic liquid replacement container (sealed container) for 1 minute to separate the leaching solution adhering to the surface of the copper-containing scrap. After that, the copper-containing scrap was taken out of the hydrophobic liquid replacement container by an electromagnet and immersed in a water washing container containing pure water (1 L) to wash the leaching solution remaining on the surface of the copper-containing scrap in pure water, and a washing solution was obtained. After that, the sulfate ion concentration in the washing solution was measured, and from that concentration, the amount of residual leaching solution per unit area adhering to the surface of the copper-containing scrap taken out from the hydrophobic liquid replacement container was calculated, and it was 30 mL / m 2 resulted, and the amount of residual leaching solution could be reduced by 71% compared to Comparative Example 2-1.

[0067] - Example 2-3- In Example 2-3, after separating the leachate that floated up in the hydrophobic liquid replacement step of Example 2-2, the copper-contaminated scrap was removed using an electromagnet, and the effect of removing the leachate that floated up in the hydrophobic liquid replacement step was evaluated. As a result, by removing the floating leachate, the amount of residual leachate was reduced to 27 mL / m³. 2 As a result, the amount of residual leachate was reduced by 74% compared to Comparative Example 2-1. The density of the hydrophobic liquid (1-bromopropane) is 1.35 g / cm³. 3 The density of the leachate after extraction (100 g / L ammonium sulfate aqueous solution, pH adjusted to 10.5 with sodium hydroxide) is 1.09 g / cm³. 3 That is the case.

[0068] -Examples 2-4 to 2-6- In Examples 2-4 to 2-6, after applying vibration or ultrasonic waves to copper-contaminated scrap immersed in a hydrophobic liquid in the hydrophobic liquid replacement step of Example 2-3, the leachate that floated to the surface of the hydrophobic liquid was separated, and the effect of vibration on the copper-contaminated scrap was evaluated. In Example 2-4, an electromagnet was immersed in a hydrophobic liquid, and the process of magnetization and demagnetization was repeated three times to vibrate the copper-contaminated scrap. However, because the magnetic force of the electromagnet was insufficient, vibration could only be applied to about one-quarter of the copper-contaminated scrap at the top of the immersion chamber. In Example 2-5, the hydrophobic liquid replacement tank was stirred for 1 minute using a circulation pump, and the copper-contaminated scrap was vibrated. In Example 2-6, an ultrasonic transmitter was placed in a hydrophobic liquid, and copper-containing scrap was irradiated with ultrasound for 1 minute. As a result, the amount of residual leachate decreased compared to Examples 2-3, reaching 22-24 mL / m². 2 As a result, the amount of residual leachate was reduced by 77-79% compared to Comparative Example 2-1.

[0069] -Examples 2-7 to 2-10- In Examples 2-7 to 2-10, the hydrophobic liquid replacement process, which removes the floating leachate as performed in Example 2-3, was repeated 2 to 8 times to investigate the effect of the number of hydrophobic liquid replacements. As a result, the amount of residual leachate decreased as the number of hydrophobic liquid replacements increased, reaching 13 to 20 mL / m³. 2 As a result, the amount of residual leachate was reduced by 81-87% compared to Comparative Example 2-1. Furthermore, the amount of residual leachate on the surface of the copper-contaminated scrap decreased, resulting in a 71-87% reduction in the amount of leachate discharged from the system along with the copper-contaminated scrap. This suggests that the amount of water used for washing can also be reduced by 71-87%, which is expected to help control wastewater treatment costs. Furthermore, the post-leaching solution still contained a sufficient amount of f-NH3 to ammine-complex copper, indicating that it still possessed the ability to leach copper. In other words, we confirmed that the amount of chemicals (ammonium sulfate, sodium hydroxide for pH adjustment) needed to be replenished could be reduced as the amount of residual leaching solution on the surface of the copper-contaminated scrap decreased.

[0070] The results for Comparative Example 2-1 and Examples 2-2 to 2-10 are shown in Table 3.

[0071] [Table 3]

[0072] (Example 3) In Examples 3-1 to 3-4, in Comparative Example 2-1, after removing the copper-contaminated scrap from the leachate using an electromagnet, the scrap was immersed for 1 minute in a hydrophobic liquid (1-bromopropane, 1 L) containing a dissolved surfactant (Na-sulfonate) in a first hydrophobic liquid replacement container (sealed container) to separate the leachate adhering to the surface of the copper-contaminated scrap. Next, after removing the leachate that had floated to the surface of the hydrophobic liquid in the first hydrophobic liquid replacement container using a dropper, the copper-contaminated scrap was removed from the hydrophobic liquid using an electromagnet. Then, it was immersed for 1 minute in a hydrophobic liquid (1-bromopropane, 1 L) containing a dissolved surfactant (Na-sulfonate) in the second hydrophobic liquid replacement container (sealed container) to further separate the leachate adhering to the surface of the copper-contaminated scrap. Next, the copper-contaminated scrap was removed from the second hydrophobic liquid replacement container using an electromagnet, immersed in a water washing container containing pure water (1L), and the leachate remaining on the surface of the copper-contaminated scrap was washed with pure water to obtain a washing solution. Subsequently, the sulfate ion concentration in the washing solution was measured, and from that concentration, the amount of residual leachate per unit area adhering to the surface of the copper scrap removed from the hydrophobic liquid storage container was calculated.

[0073] In Examples 3-1 to 3-4, the surfactant concentration in the hydrophobic liquid in the first and second hydrophobic liquid displacement containers was varied as shown in Table 4, and the effect of the surfactant concentration was investigated. As a result, it was found that the amount of residual leachate decreased when a surfactant was added. The amount of surfactant added was 2.3 g / m². 2 -In the case of scrap (Examples 3-4), the residual leachate volume was 2.3 mL / m². 2 As a result, it was found that the amount of residual leachate could be reduced by 97.8% compared to Comparative Example 2-1.

[0074] [Table 4]

[0075] (Example 4) In Example 2-3, the scrap removed from the hydrophobic liquid replacement tank was placed in a drying oven maintained at 120°C for 5 minutes to allow the remaining hydrophobic liquid to volatilize and be removed. The scrap removed from the drying oven no longer had the pungent odor caused by the hydrophobic liquid, and when the amount of residual hydrophobic liquid was measured, it was not detected. Therefore, it was determined that the hydrophobic liquid had been completely removed from the scrap surface. Furthermore, the scrap removed from the hydrophobic liquid replacement tank in Example 2-3 was immersed for 5 minutes in hot water in a hydrophobic liquid volatilization tank maintained at 90°C to remove any remaining hydrophobic liquid. The scrap removed from the hydrophobic liquid volatilization tank no longer had the pungent odor caused by the hydrophobic liquid, and when the amount of residual hydrophobic liquid was measured, it was not detected. Therefore, it was determined that the hydrophobic liquid had been completely removed from the scrap surface.

[0076] (Example 5) Lumpy material (copper-containing scrap, Cu content: 0.6%, surface area approximately 330 cm²) 2 100g was leached for 5 hours in a sealed container containing approximately 2L of leachate (38g-NH3 / L, pH 10, DO (dissolved oxygen concentration) controlled to 10mg / L). After leaching, the scrap was magnetically attached using an electromagnet, removed from the leachate, and placed in a hydrophobic liquid (1-bromopropane, 1 L) in a hydrophobic liquid replacement container (sealed container). The scrap was immersed for 1 minute, and the leachate adhering to the surface of the scrap was separated. Next, the scrap was removed from the hydrophobic liquid displacement container using an electromagnet, immersed in a water washing container containing pure water (1L), and the leachate remaining on the surface of the scrap was washed with pure water to obtain a washing solution. Subsequently, the sulfate ion concentration in the washing solution was measured, and from that concentration, the amount of residual leachate per unit area adhering to the scrap surface removed from the hydrophobic liquid storage container was calculated to be 32 mL / m². 2 This was the result. Comparative Example 2-1 (residual leachate volume: 103 mL / m²) 2 Compared to the previous method, the amount of residual leachate was reduced by 69%. In addition, the Cu content in the recovered scrap was 0.13%, and the Cu removal rate was 78%.

[0077] On the other hand, a sulfidizing agent (NaHS aqueous solution) was added to the leached solution (pH 10) containing copper ions after leaching until the oxidation-reduction potential reached -150 mV, causing the copper ions in the leached solution to precipitate as copper sulfide. The leached solution was filtered to separate the copper sulfide, and the regenerated leached solution (leached solution) was recovered. The recovered leachate was reused, and the leaching process was repeated. Specifically, approximately 2 L of the recovered leachate (37 g-NH3 / L, pH 10, DO controlled to 10 mg / L) was placed in a sealed container, and a lump-like material (copper-containing scrap, Cu content: 0.58%, surface area approximately 330 cm²) was leached. 2 100g was steeped for 5 hours. After leaching, the scrap was magnetically attached using an electromagnet, removed from the leachate, and placed in a hydrophobic liquid (1-bromopropane, 1 L) in a hydrophobic liquid replacement container (sealed container). The scrap was immersed for 1 minute, and the leachate adhering to the surface of the scrap was separated. Next, the scrap was removed from the hydrophobic liquid displacement container using an electromagnet, immersed in a water washing container containing pure water (1L), and the leachate remaining on the surface of the scrap was washed with pure water to obtain a washing solution. Subsequently, the sulfate ion concentration in the washing solution was measured, and from that concentration, the amount of residual leachate per unit area adhering to the scrap surface removed from the hydrophobic liquid storage container was calculated to be 29 mL / m². 2 This was the result. Comparative Example 2-1 (residual leachate volume: 103 mL / m²) 2 Compared to the previous method, the amount of residual leachate was reduced by 72%. In addition, the Cu content in the recovered scrap was 0.14%, and the Cu removal rate was 76%.

[0078] Based on the above, it was confirmed that the amount of residual leachate adhering to the surface of the aggregate could be reduced while simultaneously regenerating the copper leaching capacity of the leachate. As the amount of residual leachate on the surface of the aggregate decreased, the amount of leachate discharged outside the system along with the aggregate decreased by approximately 70%. Consequently, the amount of leachate to be replenished also decreased by approximately 70%, and the cost of replenishing the leachate also decreased by approximately 70%. Furthermore, because the amount of residual leachate on the surface of the aggregate decreased, the amount of water used for washing could be reduced by approximately 70%, thereby suppressing wastewater treatment costs.

[0079] Furthermore, comparing the case where the leachate is regenerated (Example 5) and the case where the leachate is not regenerated (Example 2), if the reduction rate of residual leachate volume is the same, the reduction in wastewater treatment costs is about the same, but the cost of replenishing chemicals can be reduced more when the leachate is regenerated.

[0080] (Example 6) Iron sulfide ore containing 0.9% copper was sieved to separate lumps larger than 10 mm, and 10 kg of these lumps were piled up to a height of approximately 10 cm on a drainage pallet. From the top of the piled lumps, 1000 mL of a sulfuric acid solution containing trivalent iron ions (containing Na ions as a tracer) was sprayed as an leachate and collected on the drainage pallet to extract copper ions. This process was repeated every 15 minutes for 3 days. Pyrite (FeS2), chalcocite (Cu2S), and chalcopyrite (CuFeS2) in the ore are oxidized by trivalent iron ions, producing divalent iron ions, divalent copper ions, and sulfate ions, which are then leached out. The divalent iron ions are oxidized back to trivalent iron ions by iron-oxidizing bacteria and used again as leachate.

[0081] After three days of watering, metallic iron was added to the leachate containing copper ions extracted from the iron sulfide ore. This reduced the copper ions in the leachate to metallic copper, which was then precipitated, separated, and recovered.

[0082] On the other hand, a 100g mass of material that had been watered for three days was placed in a basket with many holes, and the basket was immersed for one minute in a hydrophobic liquid (1-bromopropane, 1L) in a hydrophobic liquid exchange container (sealed container), and the leachate adhering to the surface of the mass was separated. Next, the basket containing the lumps was removed from the hydrophobic liquid replacement container and immersed in a water washing container containing pure water (1L) to measure the residual leachate. The leachate remaining on the surface of the lumps was washed with pure water to obtain a washing solution. Subsequently, the sodium ion concentration in the washing solution was measured, and from that concentration, the amount of residual leachate per unit mass adhering to the surface of the lump-like material removed from the hydrophobic liquid storage container was calculated to be 42 mL / kg. Furthermore, 100g of the lumpy material after 3 days of watering was immersed in a water-washing container containing pure water (1L), and the leachate remaining on the surface of the lumpy material was washed with pure water to obtain a washing solution. Subsequently, the sulfate ion concentration in the washing solution was measured, and from this concentration, the amount of residual leachate per unit mass adhering to the lumpy material removed from the leachate container was calculated to be 95mL / kg. As a result, the amount of residual leachate was reduced by 56% through hydrophobic liquid displacement. Note that when calculating the amount of residual leachate per unit mass, the basket was operated independently, and the amount of residual leachate adhering to the basket was measured and corrected. [Explanation of symbols]

[0083] 100 Lumps 102 Exudate 104 Leaching container 106 Basket 108 Hydrophobic liquids 110 Hydrophobic liquid displacement container 112 Pure water 114. Container for water washing.

Claims

1. A leaching step in which a mass having at least the substance to be leached on its surface is brought into contact with a leachate from which the substance to be leached is leached, and the substance to be leached is leached into the leachate, A hydrophobic liquid replacement step is performed in which the lump, after the leaching of the object to be leached in the leaching step, is brought into contact with a hydrophobic liquid, and the leaching liquid remaining on the surface of the lump is replaced with the hydrophobic liquid. It has, The substances to be leached are metals, metal oxides, amphoteric metals, amphoteric metal oxides, Cu(II), Ni(II), Zn(II), Co(II), Au(I), Ag(I), pyrite (FeS₂), chalcopyrite (CuFeS₂), sphalerite (ZnS), or galena (PbS). The aforementioned lump-like material is scrap, ore, or waste electronic material. The aforementioned leachate is an aqueous solution containing a leachate and water. The aforementioned leaching agent is an acid, alkali, complexing agent, or bacteria. The hydrophobic liquid is a liquid whose solubility in water at 25°C is 0 g / L or more and 10.0 g / L or less. A method for separating residual leachate from the surface of a lumpy material.

2. The method for separating residual leachate from the surface of a lump according to claim 1, wherein in the hydrophobic liquid replacement step, the lump is immersed in the hydrophobic liquid.

3. The method for separating residual leachate from the surface of a lump-like object according to claim 1 or claim 2, wherein the density of the hydrophobic liquid is different from the density of the leachate from which the object to be leached has been leached.

4. The method for separating residual leachate from the surface of a lump-like object according to claim 3, wherein the density of the hydrophobic liquid is greater than the density of the leachate from which the object to be leached has been leached.

5. The difference between the density of the hydrophobic liquid and the density of the leachate from which the object to be leached was extracted is 0.05 g / cm³. ３ The method for separating residual leachate from the surface of a lump-like material according to claim 3 or claim 4.

6. A method for separating residual leachate from the surface of a mass according to any one of claims 1 to 5, further comprising a residual hydrophobic liquid removal step of heating the mass after the hydrophobic liquid replacement step to volatilize and remove the hydrophobic liquid remaining on the surface of the mass.

7. A method for separating residual leachate from the surface of a lump according to any one of claims 1 to 6, wherein vibration or ultrasonic waves are applied to the lump in the hydrophobic liquid replacement step.

8. A method for separating residual leachate from the surface of a lump according to any one of claims 1 to 7, wherein in the hydrophobic liquid replacement step, the leachate remaining on the surface of the lump is replaced with the hydrophobic liquid, the leachate that has floated or settled in the hydrophobic liquid is separated, and then the lump is removed from the hydrophobic liquid.

9. A method for separating residual leachate from the surface of a lump-like object according to any one of claims 1 to 8, wherein the hydrophobic liquid replacement step is performed multiple times.

10. A method for separating residual leachate from the surface of a lump-like object according to any one of claims 1 to 9, wherein the boiling point of the hydrophobic liquid at atmospheric pressure is 40°C to 95°C.

11. The method for separating residual leachate from the surface of a mass according to any one of claims 1 to 10, wherein the hydrophobic liquid comprises a surfactant.

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