Classification methods for adsorbents

Abstract

To reduce final disposal matters as much as possible by separating wastes for each of desired concentration, and by recovering recyclable matters much more than ever in relation with wastes of adsorbent in which harmful heavy metals are adsorbed.SOLUTION: Provided are: an adsorbent classification method, which is a method for classifying adsorbent in which harmful heavy metals are absorbed into low concentration matters with low concentration of harmful heavy metals and high concentration matters with high concentration of harmful heavy metals, having a cleaning process for cleaning adsorbent with water alone or a combination of an alkaline detergent and water, a first solid-liquid separation process for separating water content out of cleaned adsorbent, and a classification process for classifying coarse products obtained in the first solid-liquid separation process as a low-concentration material, and micro products in water content separated in the first solid-liquid separation process as a high-concentration material; and its related technology.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for classifying adsorbents.

Background Art

[0002] Conventionally, it has been known to treat heavy metals contained in wastewater and the like by an adsorption method using a chelating agent (for example, Patent Document 1).

[0003] As a method for removing heavy metal ions by an adsorption method, it has been proposed to use an oxide adsorbent such as zeolite (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regulations on the import and export of adsorbents adsorbed with harmful heavy metals based on the Basel Convention have been continuously strengthened in each country.

[0006] In addition, due to the worldwide spread of the novel coronavirus infection, the transportation situation of goods is in turmoil, and it is impossible to transport quickly and reliably. Furthermore, the instability of the international situation due to the conflict is increasing this turmoil.

[0007] Due to the strengthening of regulations based on the Basel Convention and the increase in the above-mentioned turmoil, transportation costs have been continuously increasing.

[0008] Conventionally, adsorbents containing hazardous heavy metals are considered waste, and these adsorbents (and consequently the hazardous heavy metals) are collected in areas where disposal is possible. This "disposal" refers to methods such as separating and recovering the hazardous heavy metals from the adsorbents, or burying the adsorbents in final disposal sites.

[0009] Such waste is usually transported by vehicles or ships. As mentioned above, transportation costs continue to rise, and even fast and reliable transportation is unreliable these days. Therefore, it is advisable to reduce the amount of waste that is affected by the aforementioned disruptions in transportation. Furthermore, the disposal methods for waste vary depending on the amount and type of hazardous heavy metals it contains.

[0010] The object of the present invention is to address waste materials containing adsorbents that have adsorbed harmful heavy metals, by separating the waste according to desired concentrations, recovering more reusable material, and minimizing the amount that goes to final disposal. [Means for solving the problem]

[0011] The inventors have found that to reduce the amount of waste transported from adsorbents containing hazardous heavy metals, it is advisable to increase the amount of the adsorbent reused in the area where it is discarded. On the other hand, even if the adsorbent is transported because it cannot be processed in the area where it is discarded, it may be possible to separate and recover reusable portions by processing it before transport.

[0012] Therefore, the inventors diligently investigated the treatment before transportation. In order to increase the amount of adsorbent that can be reused in the area where the adsorbent is discarded, the concentration of harmful heavy metals should be reduced to a level that is suitable for reuse in that area. The inventors discovered that this can be achieved by picking out adsorbent with a concentration of harmful heavy metals below a predetermined level from the entire adsorbent.

[0013] Furthermore, it is conceivable to apply the technology described in Patent Document 1, which involves separating and reusing hazardous heavy metals from chelate resins after their adsorption. However, for such reuse, separation treatment of the adsorbed heavy metal ions and regeneration treatment to restore the adsorption capacity must be performed. Moreover, as described in Patent Document 1, selectively separating only hazardous heavy metals is time-consuming and costly. This further complicates the rapid and reliable transportation that is a prerequisite for the aforementioned risk hedging.

[0014] Furthermore, while the zeolite-based adsorbent used in Patent Document 2 does not require pH adjustment as is necessary with other types of adsorbents, it has the problem of being expensive, and moreover, the adsorbent described in Patent Document 2 does not address the issues of the present invention.

[0015] Therefore, the inventors conducted further intensive studies and, as a result, conceived a method for easily and inexpensively classifying adsorbents containing harmful heavy metals into adsorbents with concentrations below a predetermined level (which are the target for pickup) and other adsorbents by performing a washing step and a first solid-liquid separation step on the adsorbent.

[0016] The first invention is, A method for classifying adsorbents that have adsorbed harmful heavy metals into low-concentration materials with low concentrations of harmful heavy metals and high-concentration materials with high concentrations of harmful heavy metals, A washing step in which the adsorbent is washed with a washing solution to form coarse and fine products, A first solid-liquid separation step separates the post-wash liquid containing fine products, A classification step is performed to classify the coarse products obtained in the first solid-liquid separation step into low-concentration products, and to classify the fine products in the post-wash liquid separated in the first solid-liquid separation step into high-concentration products. This is a method for classifying adsorbents, which has the following characteristics.

[0017] The second invention is, The aforementioned harmful heavy metal is at least one of mercury, arsenic, and antimony, according to the method for classifying adsorbents as described in the first invention.

[0018] The third invention is where the harmful heavy metal is mercury, and the mercury concentration threshold for separating the low-concentration material and the high-concentration material is one numerical value within the range of 1000 ppm or more and 30,000 ppm or less, which is the classification method of the adsorbent described in the first invention.

[0019] The fourth invention is where the adsorbent is a granular catalyst, and the first solid-liquid separation step is a wet screening step for classifying the post-washing liquid, coarse products, and fine products using a sieve, In the classification step, the coarse products are the coarse washed catalysts remaining on the sieve in the wet screening step, and the fine products include at least one of the fine washed catalysts that fall below the sieve and the harmful heavy metals detached from the catalyst in the wet screening step, which is the classification method of the adsorbent described in the third invention.

[0020] The fifth invention is where the main material of the catalyst is copper or ceramics, which is the classification method of the adsorbent described in the fourth invention.

[0021] The sixth invention is where the average particle size of the catalyst is 1 - 10 mm, and the mesh opening of the sieve is 1.0 - 3.0 mm, which is the classification method of the adsorbent described in the fourth invention.

[0022] The seventh invention is where the adsorbent is a filter, and there is a crushing step for crushing the filter before the first solid-liquid separation step, and the first solid-liquid separation step is a dehydration step for squeezing out moisture from the washed filter, In the classification step, the coarse products are the coarse washed filters after moisture has been squeezed out in the dehydration step, The aforementioned fine product comprises at least one of the fine washed filter particles in the water squeezed out in the dehydration step and harmful heavy metals detached from the filter, as described in the third invention, and is a method for classifying adsorbents.

[0023] The eighth invention is, The main material of the filter is at least one of polypropylene, polyester, polyamide, polyethylene, polycarbonate, acrylic, and cellulose ester, according to the seventh invention, which is a method for classifying adsorbents.

[0024] The ninth invention is, The ratio of the low-concentration substance to the adsorbent before the washing process is 70-99% by mass. The method for classifying adsorbents according to the fourth or seventh invention is such that the ratio of the high-concentration substance to the adsorbent before the washing step is 1 to 30% by mass.

[0025] The tenth invention is, The first solid-liquid separation step involves separating water from the washed adsorbent while also including the post-washing liquid from the washing step, as described in the fourth or seventh invention.

[0026] The eleventh invention is, An intermediate solid-liquid separation step in which the water separated in the first solid-liquid separation step undergoes one or more solid-liquid separation treatments, A coagulant addition step is to add a coagulant to at least one of the water separated during the intermediate solid-liquid separation step and the water separated after the intermediate solid-liquid separation step, A final solid-liquid separation step involves performing a solid-liquid separation procedure on the water obtained through the intermediate solid-liquid separation step and the coagulant addition step, It has, This is a method for classifying adsorbents according to the fourth or seventh invention, wherein the fine products obtained in the intermediate solid-liquid separation step and the fine products obtained in the final solid-liquid separation step are added to the high-concentration material.

[0027] The twelfth invention is, The aforementioned flocculant is comprised of one or more selected from aluminum sulfate, polyaluminum chloride (PACl), ferric chloride, ferric sulfate, polysilica iron (PSI) for water supply, polymer-based flocculants, and chelating agents, and is a method for classifying adsorbents as described in the 11th invention.

[0028] The 13th invention is, In the aforementioned high-concentration substance, the adsorbent material accounts for 50% by mass or more. The method for classifying adsorbents according to the fourth or seventh invention is such that the mass percentage of the adsorbent material in the low-concentration substance is greater than the mass percentage of the adsorbent material in the high-concentration substance. [Effects of the Invention]

[0029] According to the present invention, with regard to waste adsorbent materials on which harmful heavy metals have been adsorbed, the waste is separated according to desired concentrations, allowing for the recovery of more reusable materials and minimizing the amount that goes to final disposal. [Brief explanation of the drawing]

[0030] [Figure 1] Figure 1 is a flowchart illustrating the first aspect (catalyst) of the adsorbent classification method in this embodiment. [Figure 2] Figure 2 is an illustrative diagram showing the state of the adsorbent before (a) and after (b) the cleaning process in the embodiment 1 (catalyst) of this embodiment. [Figure 3] Figure 3 is an image diagram showing the before (a) and after (b) stages of the wet sieving process in embodiment 1 (catalyst) of this embodiment. [Figure 4] Figure 4 is a flowchart illustrating Embodiment 2 (filter) of the adsorbent classification method in this embodiment. [Modes for carrying out the invention]

[0031] The following describes the classification method for adsorbents according to this embodiment. "~" indicates a value greater than or equal to a predetermined value and less than or equal to a predetermined value.

[0032] [Adsorbent material that has adsorbed harmful heavy metals] The present invention is not limited to the specific type of "adsorbent material that has adsorbed harmful heavy metals" in this embodiment (for example, its use before becoming waste). Examples of each item are given below.

[0033] The aforementioned harmful heavy metals are not limited to any heavy metal harmful to the human body, but examples include at least one of mercury, arsenic, and antimony. In this embodiment, mercury is used as an example.

[0034] Mercury, one of the toxic heavy metals, is present in most natural gas fields at concentrations of 10 ppb to 1 ppm, as elemental (metal), organic, and inorganic compounds. Because mercury is toxic and primarily corrodes aluminum equipment, its removal to trace levels is required. Such mercury removal from natural gas is carried out, for example, using adsorbent catalysts or filters.

[0035] The following explanation will be divided into two cases: one where the adsorbent that has adsorbed harmful heavy metals is a catalyst, and another where the adsorbent is a filter.

[0036] [Aspect 1: When the adsorbent is a catalyst] The present invention is not limited to the material of the catalyst itself. For example, a catalyst is composed of a support and catalyst particles. The support is made of copper or ceramics. In this respect, the main material of the catalyst is copper or ceramics. In this specification, "main material" refers to, for example, the compound (including metal elements) that constitutes the catalyst and accounts for the largest mass % (preferably more than half). The same definition applies to the other term "main component" in this specification.

[0037] There are no specific limitations on the shape of the catalyst, but examples include granular (especially granular) form. There are also no limitations on the average particle size, but for example, an average particle size of about 1 to 10 mm is acceptable. There are no limitations on the method of calculating the average particle size, and an approximate average particle size may be calculated using multiple sieves. Alternatively, the average particle size of the waste catalyst may be calculated from the average particle size values ​​published by each catalyst manufacturer as product information and the approximate ratio of the amount of catalyst manufactured by each manufacturer to the total amount of catalyst to be processed. Furthermore, if the average particle size is outside the above range and is difficult to handle in the wet sieving sorting process described later, a crushing process may be performed on the catalyst separately before the washing process described later in order to set it within the above range of average particle size. There are no specific limitations on the method of the crushing process.

[0038] The following describes the classification method when the adsorbent in this embodiment is a catalyst, referring to the flowchart in Figure 1. In Figures 2 and 3 shown later, reference numeral 1 indicates the catalyst, reference numeral 2 indicates the sieve, reference numeral 3 indicates the low-concentration material, reference numeral 4 indicates the high-concentration material, and Hg indicates mercury, but these reference numerals will be omitted from now on.

[0039] <Washing process> In this embodiment, the catalyst adsorbed with mercury is washed with a washing solution to form coarse and fine products. This process washes away the mercury particles adsorbed on the catalyst (see Figure 2). As a result, when focusing on a single mass of catalyst adsorbed with mercury particles, the mercury concentration in that mass decreases. A similar decrease in mercury concentration occurs in almost all of the masses constituting the catalyst to be treated in this invention. This process ultimately increases the amount of low-concentration material with a low mercury concentration. In other words, it increases the proportion of low-concentration material in the classification of catalysts, which is the main point of this invention. For example, while the mercury concentration in the catalyst before this process is approximately 70,000 ppm, the mercury concentration in the washed catalyst after this process is approximately 20,000 to 30,000 ppm.

[0040] In this specification, "cleaned catalyst (cleaned adsorbent)" also includes the catalyst (adsorbent) during the cleaning process.

[0041] Furthermore, washing with water alone or a combination of alkaline detergent and water results in a wet treatment, and when combined with the subsequent wet sieving process described later, it prevents mercury particles detached from the catalyst from becoming airborne.

[0042] There are no limitations on the specific method of the cleaning process. For example, the cleaning process may be carried out using a rotary drum cleaning machine. A specific example of a rotary drum cleaning machine is a well-known drum scrubber. By using a drum scrubber, the catalysts rub against each other. This rubbing efficiently removes the adsorbed mercury particles. Since these mercury particles were originally adsorbed on the catalyst, they are considered in this specification as catalyst (adsorbent) detached products.

[0043] Using a drum scrubber helps to loosen the catalyst to a reasonable degree. Therefore, when using a drum scrubber, it is often unnecessary to include a separate crushing process. On the other hand, some types of catalysts may not loosen easily, in which case a separate step of stirring the catalyst with water may be added to loosen it.

[0044] The cleaning solution used in the cleaning process is preferably a combination of an alkaline detergent and water. The alkaline detergent contains a surfactant. This surfactant effectively removes mercury particles adsorbed on the catalyst. The present invention is not limited to the composition of the alkaline detergent. Examples of alkaline detergents include those mainly composed of sodium bicarbonate, sodium hydroxide, and potassium hydroxide. The pH of the alkaline detergent may be alkaline (e.g., pH > 7), but a strongly alkaline pH (e.g., 9 ≤ pH ≤ 11) can further effectively remove mercury particles from the catalyst.

[0045] On the other hand, even when simply using water as the cleaning solution, the mercury particles adsorbed on the catalyst can be effectively removed by rubbing the catalysts together using the drum scrubber. The pH of the water is, for example, 6 to 7.

[0046] The specific method for this process may be selected depending on the type of catalyst used.

[0047] For example, when processing a granular catalyst, since the catalyst granules easily rub against each other, a shaking device may be used instead of a drum scrubber. In that case, the shaking time may be, for example, 30 minutes.

[0048] Furthermore, the fine products (specifically, adsorbed mercury particles) contained in the post-washing solution of this process may be recovered and added to the high-concentration product obtained from the water below the sieve in the wet sieving process described later. Adding all of the fine products contained in the post-washing solution of this process to the high-concentration product is preferable in that it reduces the amount of work involved. These fine products include the fine washed catalyst and desorbed materials that fall below the sieve along with the water in the wet sieving process. On the other hand, since the mercury concentration in the coarse products contained in the post-washing solution of this process is relatively low, the coarse washed catalyst may be added to the low-concentration product described later.

[0049] <First solid-liquid separation process (wet sieve sorting process)> In this process, the washed catalyst is classified using a wet process. This classification separates the mercury-adsorbed catalyst into a coarse washed catalyst with a low mercury concentration and a post-washing solution containing fine products with a high mercury concentration.

[0050] Following the washing process, the mercury concentration in almost all catalyst clumps of the coarsely washed catalyst is reduced. Then, in the wet sieving process, the catalyst clumps are separated into those larger than the classification standard and those smaller than the classification standard. Those smaller than the classification standard fall through the sieve along with the moisture. The larger the catalyst clump, the lower the mercury concentration (specifically, by mass%) in a single clump (see Figure 3). This invention utilizes this phenomenon.

[0051] In other words, the coarsely washed catalyst obtained in this process is classified as the low-concentration material. Conversely, the finely washed catalyst obtained in this process is classified as the high-concentration material. The coarsely washed catalyst is also called coarse grains, and the finely washed catalyst is also called fine grains.

[0052] In this embodiment, the threshold mercury concentration that distinguishes the low-concentration substance from the high-concentration substance is exemplified as a single value within the range of 1,000 ppm or more and 30,000 ppm or less, and more specifically, 20,000 ppm is exemplified. This is just one example, and 18,000 ppm may be adopted as in the later embodiment.

[0053] In the first solid-liquid separation step, water may be separated from the washed catalyst while the post-washing liquid from the washing step is also included. This allows the first solid-liquid separation step to be performed on fine products in the post-washing liquid (mercury particles, which are catalyst desorbed products, and, in some cases, very fine washed catalyst). If a separate solid-liquid separation treatment were to be performed on the fine products in the post-washing liquid, it would be a double effort, but this step is eliminated.

[0054] In this embodiment, the catalyst with adsorbed mercury is classified into two categories: low-concentration and high-concentration. However, further classification of the low-concentration material into lower and higher concentrations is not prohibited. Similarly, further classification of the high-concentration material into lower and higher concentrations is not prohibited. In any case, the low-concentration material can be processed within areas where the standard mercury concentration is 20,000 ppm.

[0055] The proportion of the low-concentration substance to the catalyst before the cleaning process may be 70 to 99% by mass, and the proportion of the high-concentration substance to the catalyst before the cleaning process may be 1 to 30% by mass.

[0056] Note that this mass percentage includes moisture. Ideally, it would be more accurate to calculate the mass percentage excluding moisture, but such calculation is not practical in the technical field of this invention. This is because the catalyst to be treated in this embodiment is waste, and strict moisture control (e.g., non-exposure to air) is not performed. In this embodiment, the moisture content of the catalyst to be treated is usually 15-20% by mass. Under an atmospheric environment, the waste catalyst will have a moisture content of 15-20% by mass, both before and after the application of this embodiment, unless a separate drying treatment is performed. The numerical range of mass percentages specified herein takes this into account.

[0057] There are no limitations on the methods for treating the catalyst, but one example is using low-concentration materials as cement raw materials. An example of "reusable materials" in this specification is low-concentration materials used as cement raw materials.

[0058] In the high-concentration product, the catalyst material may account for 50% by mass or more, and the mass percentage of the catalyst material in the low-concentration product may be greater than the mass percentage of the catalyst material in the high-concentration product. This provision clarifies that Embodiment 1 relates solely to a method for classifying catalysts, and clearly distinguishes it from a technology that merely recovers harmful heavy metals from catalysts. As an example, in the low-concentration product, the filter material may account for 70% by mass or more.

[0059] There are no limitations on the specific methods used in this process, nor on the method for setting the classification criteria values, but an example will be given below.

[0060] In the wet sieving process, the coarse, washed catalyst remaining on the sieve is classified as a low-concentration substance, and the fine products (fine washed catalyst and harmful heavy metals detached from the catalyst) that fall below the sieve are classified as a high-concentration substance.

[0061] The mesh size of the sieve may be 1.0 to 3.0 mm. For example, it may be 2.0 mm. The sieve is part of the structure of the vibrating conveyor. Specifically, the washed catalyst passes over the sieve, which serves as the floor. At this time, the washed catalyst is transported forward by vibration. During this transport, low-concentration coarse material on the sieve of the vibrating conveyor is transported forward, while high-concentration material falls from the sieve floor along with moisture.

[0062] In the wet sieving process, the fine particles (in other words, the entire solid content) that fall below the sieve are classified as high-concentration materials. In this case, a solid-liquid separation process may be performed only once on the material that falls below the sieve in the wet sieving process. Alternatively, the following treatments may be performed on the material that falls below the sieve.

[0063] A second solid-liquid separation step (for example, using a high-mesh separator) may be performed to separate the finely washed catalyst into a high-concentration substance from the material that falls below the sieve in the wet sieving step.

[0064] A coagulant addition step may be performed, in which a coagulant is added to the water which is the fallen material after the second solid-liquid separation step, and a third solid-liquid separation step (for example, using a filter press) may be performed on the water which has undergone the coagulant addition step.

[0065] Furthermore, the fine products obtained in the third solid-liquid separation step may be added to the high-concentration product.

[0066] The processing from the second solid-liquid separation step onward may be carried out using, for example, the technology described in Japanese Patent Application Publication No. 2001-87739.

[0067] The aforementioned flocculant may consist of any one or more selected from aluminum sulfate, polyaluminum chloride (PACl), ferric chloride, ferric sulfate, polysilica iron (PSI) for water supply, polymer-based flocculants, and chelating agents (e.g., sulfur-containing (S-type)).

[0068] In the second and third solid-liquid separation steps, known solid-liquid separation methods may be employed. For example, filtration, centrifugation, etc., may be used.

[0069] The second solid-liquid separation step does not necessarily have to be a precise solid-liquid separation, because the fine products will ultimately be separated in the subsequent coagulant addition step and the third solid-liquid separation step.

[0070] The second solid-liquid separation step is also called an intermediate solid-liquid separation step, in which a solid-liquid separation treatment is performed once or more on the washed adsorbent from the water separated in the first solid-liquid separation step. The third solid-liquid separation step is also called the final solid-liquid separation step, in which solid-liquid separation is performed on the water separated through the coagulant addition step. Finally, the fine products obtained in the intermediate solid-liquid separation step and the final solid-liquid separation step are classified as the high-concentration product. As described in Example 2 (filter) below, a coagulant addition step may be performed in which a coagulant (aluminum sulfate in Example 2) is added to the water separated during the intermediate solid-liquid separation step. Then, in the final solid-liquid separation step, solid-liquid separation may be performed on the water separated through the intermediate solid-liquid separation step and the coagulant addition step.

[0071] For example, the mercury particles contained in the post-washing liquid from the washing process and the fine products obtained in the third solid-liquid separation process are added to the high-concentration material, and the resulting high-concentration material is disposed of in a region where it can be treated. However, thanks to the method described in this embodiment, most of the catalyst that has adsorbed mercury is transformed into a low-concentration material by the washing process, and this low-concentration material can be picked up on a sieve by the wet sieving process. Consequently, the mercury concentration in the high-concentration material is higher. On the other hand, this embodiment reduces the amount of high-concentration material itself. In other words, with regard to the waste of catalysts on which harmful heavy metals have been adsorbed, the waste can be separated by desired concentration, more reusable material can be recovered, and the amount that goes to final disposal can be reduced as much as possible. Specifically, the amount of adsorbent material transported outside the area where it is disposed of can be reduced, thus mitigating the risk of transportation problems associated with the aforementioned disruption.

[0072] <Classification process> Through the above steps, the catalyst waste can be classified into low-concentration and high-concentration materials. Accordingly, in the classification step of this embodiment, the coarse products obtained in the first solid-liquid separation step are classified as low-concentration materials, and the fine products in the water separated in the first solid-liquid separation step are classified as high-concentration materials. In this case, with regard to the classification into high-concentration materials, mercury particles, which are at least catalyst (adsorbent) detached products among the fine products in the liquid after washing in the washing step, may also be classified together as high-concentration materials.

[0073] In this embodiment, the classification step refers to labeling low-concentration materials as low-concentration materials and high-concentration materials as high-concentration materials. This "labeling" can be either physical labeling or data labeling. For example, a piece of paper or sticker indicating that it is a low-concentration material (e.g., a note indicating that it is scheduled for processing within the area) may be attached to a block consisting of low-concentration materials, or the low-concentration nature of the block may be managed digitally.

[0074] [Aspect 2: When the adsorbent is a filter] The following describes the case where the adsorbent material that has adsorbed harmful heavy metals is used as a filter. Any matters not described below may be the same as those described in Embodiment 1 above, or the same methods may be employed.

[0075] The present invention is not limited to the material of the filter itself. For example, the main material of the filter may be at least one of polypropylene, polyester, polyamide, polyethylene, polycarbonate, acrylic, and cellulose ester.

[0076] <Crushing process> While there are no specific limitations on the shape of the filter, unlike a catalyst, the filter's initial form is not granular. Therefore, it is preferable to have a crushing step to crush the filter before the washing step described later.

[0077] There are no limitations on the equipment used in the crushing process; any known crusher may be used. In this embodiment, an example is given of using a wet crusher that can perform crushing simultaneously with the washing process described later. On the other hand, the present invention does not exclude cases where the washing process is performed after the crushing process.

[0078] There are no limitations on the average particle size of the filter after the crushing process, but for example, an average particle size of about 20 to 150 mm is acceptable. There are no limitations on the method of calculating the average particle size, and an approximate average particle size may be calculated using multiple sieves.

[0079] <Washing process> In this embodiment, the crushed filter that has adsorbed mercury is washed with a washing solution to form coarse and fine products. As described above, the washing water can be water alone or a combination of alkaline detergent and water. This process washes away the mercury particles adsorbed on the crushed filter. As a result, when focusing on one mass of the crushed filter that has adsorbed mercury, the mercury concentration in the coarse products decreases. A similar decrease in mercury concentration occurs in almost all of the coarse products that constitute the crushed filter to be processed in this invention. This process ultimately increases the amount of low-concentration material with a low mercury concentration. In other words, it increases the proportion of low-concentration material. For example, while the mercury concentration in the filter before this process is approximately 70,000 ppm, the mercury concentration in the crushed and washed filter after this process is approximately 20,000 to 30,000 ppm.

[0080] In the first solid-liquid separation step, water may be separated from the crushed and washed filter while it still contains the post-washing liquid from the washing step. This allows the first solid-liquid separation step to be performed on the fine products in the post-washing liquid (mercury particles, which are filter detachments, and, in some cases, very fine washed filters). If a separate solid-liquid separation treatment were to be performed on the fine products in the post-washing liquid, it would be a double effort, but this step is eliminated.

[0081] In this specification, "crushed and washed filter" also includes the crushed filter (adsorbent) during the washing process.

[0082] There are no specific limitations on the cleaning process. For example, the cleaning process may be carried out using a wet crusher. By using a wet crusher, the crushed filters rub against each other. This rubbing efficiently removes the adsorbed mercury particles. These mercury particles are also called filter residue.

[0083] Depending on the type of filter, the specific methods for the crushing process and this process may be selected accordingly.

[0084] Furthermore, the fine products contained in the post-washing liquid of this process, in other words, the filter detached material (specifically, adsorbed mercury particles), may be recovered and added to the crushed and washed filter (high-concentration material) obtained from the water squeezed out in the dehydration process described later. Adding all of the fine products contained in the post-washing liquid of this process to the high-concentration material is highly preferable in that it reduces the amount of work involved. These fine products include at least one of the fine crushed and washed filter and the detached material from the filter in the water squeezed out in the dehydration process described later. On the other hand, since the mercury concentration in the coarse product of the crushed and washed filter contained in the post-washing liquid of this process is relatively low, this coarse product may be added to the low-concentration material described later.

[0085] <First solid-liquid separation process (dehydration process)> In this process, water is squeezed out of the washed filter. Finally, the coarse product remaining after the water has been squeezed out is classified as low-concentration material, and the fine product (in other words, all the solids) in the squeezed-out water is classified as high-concentration material.

[0086] As a result of the previous washing process, the mercury concentration in almost all of the coarse products of the crushed and washed filters has decreased. Then, in the dewatering process, the fine washed filters with high mercury concentrations fall out along with the squeezed water. On the other hand, the coarse washed filters become the coarse products after the water has been squeezed out.

[0087] This process allows for the selection of crushed and washed filters with low mercury concentrations from the entire batch of crushed and washed filters. As a result, with regard to filter waste containing adsorbed hazardous heavy metals, the waste can be separated by desired concentration levels, recovering more reusable material and minimizing the amount that goes to final disposal.

[0088] Specifically, this pickup method allows filters classified as low-concentration to be set to a concentration that can be processed within the area where filters containing adsorbed mercury particles are discarded. As a result, it becomes possible to increase the amount of filters that can be processed within the area where the mercury-adsorbed filters are discarded, and ultimately reduce the amount of filters containing mercury particles that need to be transported outside that area.

[0089] In this embodiment, the threshold mercury concentration that distinguishes the low-concentration substance from the high-concentration substance is exemplified by a single value within the range of 1,000 ppm or more and 30,000 ppm or less, and more specifically, 20,000 ppm is exemplified.

[0090] In this embodiment, filters with adsorbed mercury particles are classified into two categories: low-concentration and high-concentration. However, further classification of the low-concentration material into lower and higher concentrations is not prohibited. Similarly, further classification of the high-concentration material into lower and higher concentrations is not prohibited. In any case, the low-concentration material can be processed within areas where the standard mercury concentration is 20,000 ppm.

[0091] The proportion of the low-concentration substance to the filter before the washing process may be 70 to 99% by mass, and the proportion of the high-concentration substance to the crushed filter before the washing process may be 1 to 30% by mass.

[0092] In the high-concentration substance, the filter material may account for 50% by mass or more, and the mass percentage of the filter material in the low-concentration substance may be greater than the mass percentage of the filter material in the high-concentration substance. This provision clarifies that Embodiment 2 relates solely to a method for classifying filters, and clearly distinguishes it from a technology that simply recovers harmful heavy metals from filters. For example, in the low-concentration substance, the filter material may account for 70% by mass or more.

[0093] There are no limitations on the specific method used in this process, nor on the type of dewatering process employed. In this embodiment, a screw press is used as an example, but other dewatering processes that squeeze out moisture (e.g., a press type) may also be used. In any case, the highly concentrated, finely crushed and washed filter and the filter detached material will fall together with the moisture (including the post-washing liquid).

[0094] The entire solid content in the water squeezed out in the dewatering step may be classified as a high-concentration filter. Alternatively, the squeezed-out water may be subjected to further processing. Specifically, the second solid-liquid separation step, the coagulant addition step, and the third solid-liquid separation step described in Embodiment 1 may be performed.

[0095] <Classification process> Through the above steps, the waste filters can be classified into low-concentration and high-concentration materials. Accordingly, in the classification step of this embodiment, the coarse products obtained in the first solid-liquid separation step are classified as low-concentration materials, and the fine products in the water separated in the first solid-liquid separation step are classified as high-concentration materials. In this case, with regard to the classification into high-concentration materials, mercury particles, which are at least the desorbed material from the filter (adsorbent) among the fine products in the post-washing liquid of the washing step, may also be classified together as high-concentration materials.

[0096] In this embodiment, the classification step refers to labeling low-concentration materials as low-concentration materials and high-concentration materials as high-concentration materials. This "labeling" may be either physical labeling or data labeling. For example, a piece of paper or sticker indicating that it is a low-concentration material (e.g., a description of the planned processing within the area) may be attached to a block consisting of low-concentration materials, or the low-concentration nature of the block may be managed digitally.

[0097] [Summary] In both Embodiment 1 and Embodiment 2, a classification step is performed in which the coarse products obtained in the first solid-liquid separation step are classified as low-concentration products, and the fine products in the water separated in the first solid-liquid separation step are classified as high-concentration products.

[0098] In embodiment 1, the fine product includes at least one (preferably both) of the fine washed adsorbent and the detached material from the adsorbent that fall below the sieve along with the moisture in the wet sieving process, and in embodiment 2, it includes at least one (preferably both) of the washed adsorbent and the detached material from the adsorbent in the moisture squeezed out in the dewatering process. The washing process, the first solid-liquid separation process, and the classification process (and other suitable processes) allow for the selection of catalysts or filters with low mercury concentrations from the entire adsorbent. As a result, with respect to waste adsorbent containing harmful heavy metals, the waste can be separated according to desired concentrations, allowing for the recovery of more reusable material and minimizing the amount that goes to final disposal.

[0099] Specifically, this selection process allows adsorbents classified as low-concentration adsorbents to be easily and inexpensively adjusted to a concentration that can be processed within the area where the adsorbent containing mercury particles is discarded. As a result, it becomes possible to increase the amount of adsorbent that can be processed within the area where the adsorbent containing mercury particles is discarded, and ultimately, the amount of adsorbent containing mercury particles that needs to be transported outside that area can be reduced.

[0100] [others] The technical scope of the present invention is not limited to the embodiments described above, and includes various modified and improved forms to the extent that specific effects obtained by the constituent elements of the invention or combinations thereof can be derived.

[0101] There are no limitations on the method of processing catalysts or filters within the region, but one example is using low-concentration materials as cement raw materials. Furthermore, low-concentration materials from catalysts and filters may be processed together in a region where processing is possible. Similarly, high-concentration materials from catalysts and filters may be processed together in a region where processing is possible.

[0102] According to this embodiment, the majority of the adsorbent to be processed can be processed within the area where the adsorbent is discarded. Incidentally, before the invention was created, numerically, only about 5% by mass of the adsorbent waste could be processed within the area, and 95% by mass was subject to disposal outside the area. Incidentally, if the adsorbent is a catalyst, the ends of the container enclosing the catalyst clearly do not contain mercury and are therefore subject to processing within the area. If the adsorbent is a filter, the ends of the filter clearly do not contain mercury and are therefore subject to processing within the area.

[0103] Prior to that, in the technical field of the present invention, under conventional thinking, there is no reason to wash adsorbents that would otherwise be sent for processing in areas where they can be processed as is, as in this embodiment. Washing would result in mercury particles being mixed into the post-wash liquid, increasing the workload. On the other hand, the technical idea of ​​the present invention is based on solving the problem of recovering more reusable materials (for example, as cement raw materials) and minimizing the amount of material that ends up in final disposal (adsorbents containing high concentrations of mercury). In order to solve this problem, the above steps, including the washing step and the first solid-liquid separation step, are carried out.

[0104] As the first solid-liquid separation step, Embodiment 1 (catalyst) employs a wet sieving process, while Embodiment 2 (filter) employs a dehydration process. In both cases, the intention is to separate fine adsorbent containing high concentrations of mercury from low-concentration substances along with water (by allowing the water to fall). The present invention utilizes the fact that the smaller the adsorbent, the more it moves with water. Therefore, it is acceptable to use the expression "water dehydration (or water fall) process" to encompass both processes.

[0105] The specific examples in this embodiment correspond to either a catalyst (Aspect 1) or a filter (Aspect 2) among the adsorbents. Depending on the application of the adsorbent (e.g., how much harmful heavy metal is typically contained), the material, and the form, each of the above specific examples should be modified as appropriate.

[0106] For example, both the catalyst (Aspect 1) and the filter (Aspect 2) are processed wet from the initial stages of this embodiment (washing process for the catalyst, crushing process for the filter) up to the third solid-liquid separation process, in order to avoid generating dust containing harmful heavy metals.

[0107] Since the catalyst is granular, we believe that using a sieve is more convenient for classification, and therefore, we perform a wet sieve sorting process as the first solid-liquid separation step. Furthermore, in the filter (Aspect 2), the filter is broken down into fragments through the crushing process. However, compared to the catalyst which was originally granular, each of these fragments varies in size. Therefore, in the filter (Aspect 2), instead of using a sieve, a process to extract moisture (e.g., a dewatering process using a screw press) is performed. This allows the somewhat coarser fragments of the filter to be collected in the extraction residue, and the fine fragments of the filter and the filter detached material to fall together with the extracted moisture. Thus, a dewatering process is performed as the first solid-liquid separation process. Thus, the specific details of each step can be modified as appropriate depending on the type of adsorbent.

[0108] Examples of factors that may be modified include the size of the sieve opening, whether to use only water or a combination of alkaline detergent and water for washing, whether to perform a crushing process before the washing process, and the standard values ​​for the concentration of harmful heavy metals in a designated area where the adsorbent is discarded.

[0109] In embodiment 1 (catalyst), for example, a dry sieving process may be performed before the washing process, and lumps of adsorbent that clearly do not contain mercury and would interfere with the washing and wet sieving processes (e.g., catalyst containers) may be excluded in advance from the candidates for picking up low-concentration materials. The ends of the containers containing the catalyst clearly do not contain mercury and are therefore subject to local processing. Conversely, lumps that clearly contain mercury (or rather, adsorbents composed mostly of mercury particles) can be dropped from the sieve in a dry manner, and these lumps that clearly contain mercury can be excluded from the candidates for picking up low-concentration substances.

[0110] In this modified example, in embodiment 2 (filter), lumps (for example, the ends of the filter) that clearly do not contain mercury and would interfere with the washing and dewatering processes may be excluded from the candidates for picking up low-concentration materials before the crushing process. [Examples]

[0111] The present invention will be described more specifically below with reference to the examples. However, the present invention is not limited to these examples. The following embodiment provides an example of continuously processing used adsorbent material. The ppm values ​​used below, and the ppm values ​​mentioned above, refer to mg / kg. Furthermore, the mercury concentration was measured using a heated vaporized mercury analyzer (MA-3000 manufactured by Nippon Instruments Co., Ltd.). Furthermore, the mercury concentration threshold separating the low-concentration and high-concentration substances was set to 18,000 ppm, which is one value within the range of 1,000 ppm or more and 30,000 ppm or less. In fact, the legal limit value at the location where the examples were conducted is 20,000 ppm, but to be on the safe side, the threshold was set to 18,000 ppm in the following examples.

[0112] (Example 1) A catalyst with adsorbed mercury particles was used as the adsorbent material for harmful heavy metals. In this embodiment, the catalyst was a used catalyst (waste material) that had been used to remove mercury from natural gas. The main material of the catalyst was ceramics. The catalyst was granular in shape with a diameter of approximately 1 to 10 mm.

[0113] In Example 1, the total amount of catalyst treated was 1.08 t / h, the mercury concentration relative to the total amount was 28413 ppm, and the amount of mercury was 31 kg.

[0114] A cleaning process was performed on the catalyst. The supply rate of tap water was set to 25 L / min. A drum scrubber (also known as a drum washer; see the website below for details: http: / / www.dowa-ecoj.jp / catalog / 2017 / pdf / 20170801_pdf05.pdf) was used as the apparatus. The cleaning time was set to 1 minute.

[0115] In Example 1, the supply amount of catalyst to be treated and the supply amount of tap water used in the washing process were set to a mass ratio of 1:1.

[0116] A wet sieving process was performed on the washed catalyst. Specifically, the washed catalyst was transported using a vibrating conveyor with a sieve opening of 2.0 mm, and the coarse washed catalyst remaining on the sieve was collected in one place.

[0117] The coarse, washed catalyst remaining on the sieve was classified as low-concentration material. In fact, the mercury concentration of the coarse, washed catalyst remaining on the low-concentration sieve was 13,941 ppm, which was below the threshold of 18,000 ppm. The total amount of coarse, washed catalyst remaining on the sieve was 1.08 t / h, the amount of mercury was 15 kg, and the mercury distribution ratio in the initial catalyst was 49.1%.

[0118] Next, a second solid-liquid separation process was performed to separate the finely washed catalyst as a high-concentration substance from the material that fell below the sieve during the wet sieving process. Specifically, the material was passed through a high-mesh separator (model number KUC-102S, manufactured by Kiko Co., Ltd., classification point 75 μm) for solid-liquid separation. The mercury concentration in the finely washed catalyst obtained as residue was 20,000 ppm, exceeding the threshold of 18,000 ppm. The residue (solid) was classified as a high-concentration substance. The total amount of residue was 0.06 t / h, the amount of mercury was 1 kg, and the distribution rate of mercury in the initial catalyst was 3.3%.

[0119] Next, the slurry, which was the material that fell out during the second solid-liquid separation step, was placed in a thickener, and a flocculant addition step was performed in which a flocculant was added. As flocculants, ferric chloride (46%) (manufactured by VS Chem (1970) Limited), a chelating agent (product name Welclean K-900, manufactured by KURITA-GK CHEMICAL CO.,LTD.), and a polymer-based flocculant (poly(1,4-butylene terephthalate), manufactured by Sipchem Chemical Company) were used. In addition, sulfuric acid (20%, w / w, manufactured by LabChem Inc.) and sodium hydroxide (50%, w / w, manufactured by LabChem Inc.) were also added to adjust the pH.

[0120] A third solid-liquid separation step was performed on the slurry that had undergone the coagulant addition step. A filter press was used for this solid-liquid separation. The mercury concentration in the dewatered cake obtained after the third solid-liquid separation step exceeded 18,000 ppm. The dewatered cake was added to the high-concentration substance.

[0121] (Example 2) As an adsorbent material that adsorbs harmful heavy metals, a filter that has adsorbed mercury was used. In this embodiment, the filter is a used filter (waste) that was used in a car. The main material of the filter is at least one of polypropylene, polyester, polyamide, polyethylene, polycarbonate, acrylic, and cellulose ester.

[0122] In Example 2, the total volume of material processed in the filters was 0.25 t / h, the mercury concentration relative to the total volume was 25415 ppm, and the amount of mercury was 6.35 kg.

[0123] The filters underwent both crushing and washing processes simultaneously. A wet crusher was used as the equipment. The average particle size of the crushed filters was approximately 20-150 mm. Tap water and an alkaline detergent (product name JetCleen, strong alkaline, made in Thailand) were used in the washing process.

[0124] In Example 2, the supply volume of filters to be processed, the supply volume of tap water used in the washing process, and the supply volume of alkaline detergent were set to a mass ratio of 2:10:1.

[0125] A dewatering process was performed on the crushed and washed filters using a screw press. The coarse product, the pressing residue (pomace), was classified as low-concentration material. In fact, the mercury concentration of the low-concentration pressing residue was 10,506 ppm, which was below the threshold of 18,000 ppm. The total volume of pressing residue was 0.23 t / h, the amount of mercury was 1.83 kg, and the distribution ratio of mercury in the initial catalyst was 28.8%.

[0126] Then, the water squeezed out in the dehydration process was subjected to a second solid-liquid separation process, a flocculant addition process, and a third solid-liquid separation process using the same method as in Example 1. However, in Example 2, aluminum sulfate (1.2%) (manufactured by Fujifilm Wako Pure Chemical Industries) was added as a flocculant to the slurry, which was the fallout from the second solid-liquid separation process, in an amount equivalent to 3% by mass of the catalyst supply.

[0127] The mercury concentration in the finely crushed and washed filter obtained as residue in the second solid-liquid separation step (high-mesh separator) was 19,000 ppm, exceeding the threshold of 18,000 ppm. The residue (solid) was classified as high-concentration material. The total amount of residue was 0.03 t / h, the amount of mercury was 0.29 kg, and the distribution rate of mercury in the initial catalyst was 4.5%.

[0128] A third solid-liquid separation step was performed on the slurry that had undergone the coagulant addition step. A filter press was used for this solid-liquid separation. The mercury concentration in the dewatered cake obtained after the third solid-liquid separation step exceeded 18,000 ppm. Specifically, the mercury concentration was 34,392 ppm, the total volume was 0.123 t / h, the amount of mercury was 4.24 kg, and the mercury distribution rate in the first filter was 66.7%. The dewatered cake was added to the high-concentration material.

[0129] As a result of the above steps, the proportion of low-concentration substances to the adsorbent (catalyst or filter) before the washing step was 70% by mass or more. The proportion of the high-concentration substance to the adsorbent before the washing process was 30% by mass or less. The adsorbent material accounted for 50% by mass or more of the high-concentration substance. [Explanation of Symbols]

[0130] 1. Catalyst 2...Sieve 3...Low concentration substances 4...Highly concentrated substances Hg...Mercury

Claims

1. A method for classifying adsorbents that have adsorbed harmful heavy metals into low-concentration materials with low concentrations of harmful heavy metals and high-concentration materials with high concentrations of harmful heavy metals, A washing step in which the adsorbent is washed with a washing solution to form coarse and fine products, A first solid-liquid separation step separates the post-wash liquid containing fine products, A classification step which involves classifying the coarse products obtained in the first solid-liquid separation step into low-concentration products, and classifying the fine products in the post-wash liquid separated in the first solid-liquid separation step into high-concentration products, It has, The aforementioned harmful heavy metal is mercury. A method for classifying adsorbents, wherein the threshold mercury concentration that distinguishes the low-concentration material from the high-concentration material is a single value within the range of 1,000 ppm or more and 30,000 ppm or less.

2. The adsorbent is a granular catalyst, The first solid-liquid separation step is a wet sieving sorting step in which the post-wash liquid, coarse products, and fine products are classified by sieving. In the aforementioned classification step, The aforementioned coarse product is the coarse, washed catalyst remaining on the sieve in the wet sieving process. The method for classifying an adsorbent according to claim 1, wherein the fine products include at least one of the fine, washed catalyst that falls below the sieve in the wet sieving step and harmful heavy metals detached from the catalyst.

3. The method for classifying adsorbents according to claim 2, wherein the main material of the catalyst is copper or ceramics.

4. The average particle size of the catalyst is 1 to 10 mm. The method for classifying adsorbent materials according to claim 2, wherein the mesh opening of the sieve is 1.0 to 3.0 mm.

5. The adsorbent material is a filter, The process includes a crushing step in which the filter is crushed before the first solid-liquid separation step, The first solid-liquid separation step is a dehydration step in which water is squeezed out from the washed filter. In the aforementioned classification step, The aforementioned coarse product is a coarse, washed filter from which water has been squeezed out in the dewatering process. The method for classifying an adsorbent according to claim 1, wherein the fine products include at least one of the fine washed filter particles in the water squeezed out in the dehydration step and harmful heavy metals detached from the filter.

6. The method for classifying adsorbents according to claim 5, wherein the main material of the filter is at least one of polypropylene, polyester, polyamide, polyethylene, polycarbonate, acrylic, and cellulose ester.

7. The ratio of the low-concentration substance to the adsorbent before the washing process is 70 to 99% by mass. The method for classifying adsorbents according to claim 2 or 5, wherein the ratio of the high-concentration substance to the adsorbent before the washing step is 1 to 30% by mass.

8. The method for classifying adsorbents according to claim 2 or 5, wherein the first solid-liquid separation step separates water from the washed adsorbent while also including the post-washing liquid from the washing step.

9. An intermediate solid-liquid separation step in which the water separated in the first solid-liquid separation step is subjected to solid-liquid separation treatment one or more times, A coagulant addition step is to add a coagulant to at least one of the water separated during the intermediate solid-liquid separation step and the water separated after the intermediate solid-liquid separation step, A final solid-liquid separation step involves performing a solid-liquid separation procedure on the water obtained through the intermediate solid-liquid separation step and the coagulant addition step, It has, A method for classifying adsorbents according to claim 2 or 5, wherein the fine products obtained in the intermediate solid-liquid separation step and the fine products obtained in the final solid-liquid separation step are added to the high-concentration material.

10. The method for classifying adsorbents according to claim 9, wherein the flocculant comprises one or more selected from aluminum sulfate, polyaluminum chloride (PACl), ferric chloride, ferric sulfate, polysilica iron (PSI) for water supply, polymer-based flocculants, and chelating agents.

11. In the aforementioned high-concentration substance, the adsorbent material accounts for 50% by mass or more. The method for classifying adsorbents according to claim 2 or 5, wherein the mass percentage of the adsorbent material in the low-concentration substance is greater than the mass percentage of the adsorbent material in the high-concentration substance.

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