Method for recovering gold from valuable metal containing waste

Abstract

To provide a method for efficiently recovering a metal from a valuable metal containing waste.SOLUTION: This recovery method comprises: a first step of mixing a valuable metal containing waste and a cement raw material to prepare a mixture; a second step of crushing the mixture prepared in the first step by a roller mill to separate mill refined flour and a mill stone waste; a third step of repeating a process for crushing the mill stone waste separated in the second step and the mixture prepared in the first step to separate mill flour and a mill stone waste, separating the mill stone waste into a metal and a non-metal through magnetic force selection and / or eddy current selection, then crushing the non-metal and the mixture prepared in the first step to separate mill fines and a mill stone waste, and separating the mill stone waste into a metal and a non-metal through magnetic force selection and / or eddy current selection for a prescribed period; a fourth step of separating, through wind force selection, the mill stone waste discharged after the prescribed period in the third step into a heavy product and a light product; and a fifth step of recovering the light product separated in the fourth step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for recovering gold from valuable metal-containing waste. [Background technology]

[0002] Conventionally, a technology for recovering cement raw materials and valuable metals from waste materials such as incineration ash, waste plastics, and shredder dust has been reported in which, for example, raw materials containing metal-containing waste are pulverized in a vertical roller mill, and separated into a first pulverized material containing cement raw materials and a second pulverized material larger in size than the first pulverized material; a sorted raw material having a lower metal content than the second pulverized material is obtained from the second pulverized material by eddy current sorting; and the sorted raw material is pulverized in a vertical roller mill as part of the raw material, thereby making it possible to recover a cement raw material intermediate with a low metal content while sufficiently reducing the load on the vertical roller mill and the manufacturing equipment downstream of it (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-80509 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned waste contains valuable metals such as gold, silver, copper, platinum, palladium, zinc, iron, and aluminum. Of these, gold is used in the form of gold plating on the surfaces of smartphones, personal computers, communication devices, etc., but since it is an extremely valuable metal that is produced in small quantities, it is desirable to recover and reuse it. An object of the present invention is to provide a method for efficiently recovering gold from waste containing valuable metals. [Means for solving the problem]

[0005] The inventors first (1) prepared a mixture containing valuable metal-containing waste and cement raw materials, (2) crushed this mixture in a roller mill to separate it into mill flour and mill waste, (3) crushed the mill waste together with the above mixture as part of the raw materials in a roller mill to separate it into mill flour and mill waste, and then separated the mill waste by magnetic separation and / or eddy current separation into metals and non-metals, and (4) crushed the non-metals together with the above mixture as part of the raw materials in a roller mill to separate it into mill flour and mill waste, and then separated the mill waste by magnetic separation and / or eddy current separation into metals and non-metals. They then repeated this process for a predetermined time, and after a detailed study of the mill waste discharged from the roller mill after the predetermined time, they discovered the following: Gold is a metal with a high specific gravity, but because it exists in the mill waste in a relatively small particle form, it is difficult to separate it into the heavy product by air separation. However, the majority of mill waste (approximately 60%) is iron and stainless steel, which have high specific gravity and exist as relatively large particles. Therefore, it is possible to separate iron and stainless steel into heavy products and gold and other metals into light products. Conventionally, in air sorting, the grain size of the materials to be sorted is uniformed and then sorted using differences in specific gravity. However, the inventors believed that even between high-specific-gravity metals, if differences in grain size could be exploited, it might be possible to separate the two. The inventors then discovered that air sorting under maximum airflow conditions could separate large-grain iron and stainless steel into heavy products and small-grain gold and other metals into light products. While sieving is typically considered when utilizing grain size differences, the high specific gravity of the mill waste itself results in rapid wear of the sieve meshes, increasing running costs. Furthermore, the mill waste also contains rod-shaped stainless steel and iron, which can pass through small sieve meshes, creating problems.

[0006] That is, the present invention provides the following [1] and [2]. [1] A first step of preparing a mixture by mixing valuable metal-containing waste with a cement raw material containing one or more selected from limestone, silica stone, clays, and slag; A second step of milling the mixture prepared in the first step using a roller mill to separate it into mill refined flour and mill waste; a third step in which the mill waste stone separated in the second step and the mixture prepared in the first step are pulverized in a roller mill to separate the mill waste stone and the mill fine powder, the mill waste stone is separated by magnetic separation and / or eddy current separation into metals and non-metals, the non-metals and the mixture prepared in the first step are pulverized in a roller mill to separate the mill fine powder and the mill waste stone, and the mill waste stone is separated by magnetic separation and / or eddy current separation into metals and non-metals, and this process is repeated for a predetermined time, wherein the amount of the mill waste stone used is 10 to 100 parts by mass per 100 parts by mass of the mixture; a fourth step of separating the mill waste stone discharged after a predetermined time in the third step by wind sorting into heavy products and light products; A fifth step of recovering the light product separated in the fourth step. A method for recovering gold from valuable metal-containing waste, comprising: [2] The recovery method according to [1], which includes a circulation step after the third step and before the fourth step, in which the mill waste stone discharged after a predetermined time in the third step is crushed in a roller mill to separate it into refined mill flour and mill waste stone, and then the mill waste stone is crushed in a roller mill to separate it into refined mill flour and mill waste stone, and this process is repeated for a predetermined time, and the mill waste stone discharged in this step after a predetermined time is supplied to the fourth step. [Effects of the Invention]

[0007] According to the present invention, gold can be efficiently recovered from valuable metal-containing waste. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a flowchart according to one embodiment of the method for recovering gold from valuable metal-containing waste of the present invention. [Figure 2] 1 is a flowchart according to another embodiment of the method for recovering gold from valuable metal-containing waste of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] The method for recovering gold from valuable metal-containing waste according to this embodiment (hereinafter also simply referred to as the "recovery method") will be described in detail below. Figure 1 shows a flowchart of a preferred embodiment of the recovery method according to this embodiment.

[0010] The recovery method according to this embodiment includes steps 1 to 5, as shown in Figure 1. Each step will be described below.

[0011] <First step> This step is a step of preparing a mixture by mixing valuable metal-containing waste with cement raw materials containing one or more selected from limestone, silica stone, clays, and slag. (Waste containing valuable metals) An example of valuable metal-containing waste (hereinafter simply referred to as "waste") is incineration ash, which typically contains valuable metals such as gold, silver, copper, platinum, palladium, zinc, iron, and aluminum. Suitable examples of incineration ash include bottom ash that accumulates at the bottom of an incinerator when municipal waste, industrial waste, sewage sludge, etc. are incinerated, and dust ash that falls through the gaps in the grate of a stoker-type incinerator. The bottom ash may also contain fly ash, which is soot in the exhaust gas from incineration. Examples of industrial waste include shredder dust from discarded automobiles, discarded home appliances, vending machines, office equipment, etc., and waste plastics such as construction waste, agricultural waste, fishing waste, and marine waste.

[0012] (cement raw material) Cement raw materials may include one or more selected from limestone, silica, clays, and slag. "Limestone" primarily refers to natural limestone, but also includes foundry sand. "Silica" includes natural silica as well as foundry sand. "Clays" include, for example, construction waste soil, water supply sludge, and sewage sludge. Construction waste soil includes, for example, soil and sludge generated secondarily during construction and civil engineering work. Water supply sludge and sewage sludge include, for example, sludge alone, as well as sludge dried and powdered with quicklime or limestone. "Slag" is a general term for slag, and examples include blast furnace slag, steelmaking slag, and non-ferrous metal slag.

[0013] (mixture) The mixture may be prepared by adding one to the other and mixing, or by adding and mixing both at the same time, and the order of mixing is not important. From the viewpoint of the recovery efficiency of valuable metals, the content of waste in the mixture is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 1.5% by mass or more, on a dry mass basis, and preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. Here, in this specification, "dry mass" refers to the mass when the moisture content is 10% by mass or less.

[0014] (Preparatory treatment process) In this process, as shown in Figure 1, the valuable metal-containing waste may be subjected to a preliminary treatment step A selected from a coarse crushing step, a magnetic separation step, a particle size adjustment step, and a water washing step, followed by addition of clay to the treated material, which may then be subjected to a preliminary treatment step B selected from magnetic separation, eddy current separation, a particle size adjustment step, and a drying step, followed by addition of one or more selected from silica stone, limestone, and slag. This allows for the removal of coarse impurities before feeding the valuable metal-containing waste into the roller mill, thereby reducing the load. Note that in the preliminary treatment step, the steps can be performed in any order, and each step may be performed multiple times.

[0015] Coarse grinding process This process involves roughly pulverizing valuable metal-containing waste to particle sizes below a predetermined value, thereby breaking down the waste and removing valuable metals adhering to the waste. A crusher can be used for coarse crushing. Examples of crushers include, but are not limited to, jaw crushers, impact crushers, hammer crushers, roll crushers, and rotary crushers. Coarse crushing may be carried out two or more times. When carrying out two or more times, the same or different crushers can be used. From the viewpoint of production efficiency, the maximum particle size of the waste after coarse pulverization is preferably 40 mm or less, and more preferably 30 mm or less. The "maximum particle size" here refers to the value obtained by taking the largest coarsely pulverized product from among the coarsely pulverized products and measuring the point where the diameter of the coarsely pulverized product is largest.

[0016] ·Particle size adjustment process This process is a process of sieving waste materials, etc. This removes large impurities, reduces the load on the inside of the roller mill due to wear, breakage, vibration, etc., and also adjusts the size to suit the operating conditions of the roller mill. A sieve sorter can be used for particle size adjustment. The sieve sorter is not particularly limited, and an industrial device can be used, and for example, any of a vibration type, an in-plane motion type, a rotary type, and a fixed type can be used. Furthermore, when waste materials or the like are coarsely crushed using a crusher, a screen with the desired mesh size can be attached to the crusher, or if no screen is attached, the fixed teeth, rotating teeth, inner wall, etc. can be adjusted to the desired clearance. The maximum particle size of the waste after particle size adjustment is preferably 8 mm or more from the viewpoint of preventing clogging of the sieve mesh, and is preferably 30 mm or less from the viewpoint of reducing the load on the inside of the roller mill due to wear, breakage, vibration, etc. The "maximum particle size" here refers to the particle size represented by the smallest sieve opening through which the entire sample passes.

[0017] Magnetic separation process This process involves magnetic separation of waste, etc. Incineration ash, construction waste, etc. contain magnetic metals such as iron and stainless steel from nails, bolts, wire, washers, bearings, etc., so by recovering the magnetic metals as valuable metals through magnetic separation, it is possible to reduce the load on the roller mill due to wear, breakage, vibration, etc. For magnetic separation, a magnetic separator can be used. The magnetic separator is not particularly limited, and an industrial device can be used, and for example, any of a drum type, pulley type, and hanging type can be used. From the viewpoint of removing magnetic substances, the surface magnetic flux density of the magnetic separator is preferably 100 to 3000 gausses, more preferably 150 to 2000 gausses, and even more preferably 200 to 1000 gausses.

[0018] Eddy current screening This process involves eddy current sorting of waste, etc. Incineration ash, etc., contains non-magnetic metals such as aluminum, so by recovering the non-magnetic metals as valuable metals through eddy current sorting, it is possible to reduce the load on the roller mill due to wear, damage, vibration, etc. For eddy current sorting, an eddy current sorter can be used. The type of eddy current sorter is not particularly limited, and an industrial device can be used, and for example, any of a rotating magnet type, a direct belt conveyor type, and a rotating cylinder type may be used. The rotation speed of the rotating magnet body is preferably 1500 rpm or more and 5000 rpm or less from the viewpoint of reducing the load inside the roller mill.

[0019] ·Water washing process This step is a step of washing the waste material with water, thereby reducing the chlorine content in the waste material. The water washing method is not particularly limited as long as it can bring the waste, etc. into contact with water, and examples thereof include a method of placing the waste, etc. in a water tank and stirring it, a method of immersing the waste, etc. in water, and a method of spraying water on the waste, etc. Examples of water include tap water as defined in JIS A 5308 Appendix C, and water other than tap water (for example, river water, lake water, well water, groundwater, and industrial water). The amount of water used is preferably 0.5 to 5 times by mass, more preferably 0.75 to 4 times by mass, and even more preferably 1 to 3 times by mass, relative to the amount of waste, etc. The temperature of the water can be selected appropriately, but is usually room temperature (20°C ± 15°C). After washing with water, the washed material may be separated into a supernatant and a precipitate using, for example, a dehydrator, and the precipitate may be collected. The dehydrator may be an industrial device, such as a separator plate type, cylindrical type, or decanter type centrifuge, a filter press, or a belt filter. Alternatively, the washed material may be sieved, and only the under-sieve fraction with a high water content may be dehydrated using a dehydrator. The conditions for centrifugation may be selected as appropriate.

[0020] The preliminary treatment step can be selected appropriately depending on the type of raw material used. From the viewpoint of valuable metal recovery efficiency, however, one or more selected from a coarse crushing step, a particle size adjustment step, a magnetic separation step, and a magnetic separation step are preferred, and one or more selected from a coarse crushing step, a particle size adjustment step, and a magnetic separation step are more preferred. Furthermore, when clays are used as cement raw materials, the waste and clays can each be subjected to a preliminary treatment step before preparing the mixture. For example, the waste may be subjected to one or more selected from a coarse crushing step, a magnetic separation step, a particle size adjustment step, and a water washing step, and then the clays subjected to the magnetic separation step may be added to and mixed with the waste.

[0021] Drying Drying is carried out before feeding into a roller mill, thereby making the pulverization in the roller mill uniform and stable. The drying method is not particularly limited as long as it can adjust the moisture content to the desired level, but examples include modification with calcium oxide, drying on the ground, and heat drying. Among these, it is preferable to extract exhaust gas emitted from the cement production process and heat dry it. The temperature for heat drying is preferably 20 to 300°C, and more preferably 75 to 110°C.

[0022] The moisture content after moisture adjustment is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, from the viewpoints of preventing adhesion in the roller mill and efficiently recovering fine powder. The lower limit of the moisture content is not particularly limited, and it may be 0% by mass. Here, in this specification, the "moisture content" refers to the value calculated from the mass loss when 1 kg of a sample is dried at 105°C until it reaches a constant weight.

[0023] <Second process> In this step, the mixture prepared in the first step is pulverized in a roller mill to separate it into mill refined flour and mill waste stone. Here, in this specification, "fine powder" refers to fine powder discharged by the airflow during grinding, and "exhaust stone" refers to granular or lumpy solids that do not become powder and are discharged by the airflow during grinding.

[0024] The roller mill is not particularly limited as long as it is equipped with a mechanism for compressing and shearing a mixture between multiple rollers and a rotating table, pulverizing the mixture, and selectively discharging the pulverized fine powder using an airflow. For example, an industrial vertical roller mill can be mentioned. In a vertical roller mill, the mixture is classified by a separator at the top to obtain milled fine powder, and larger particles are pulverized again by the rollers and table. A dam ring is provided around the table, and the material that falls over the dam ring and is discharged is the mill waste.

[0025] In this process, for example, waste and cement raw materials are transported to a raw material supply section, which then supplies the waste and cement raw materials to a roller mill for grinding. This separates the waste into milled powder, which is discharged from the roller mill on the airflow, and milled waste stone, which is discharged from the discharge section at the bottom of the roller mill. The milled waste stone has a larger particle size than the milled powder and contains a large amount of valuable metals. Therefore, the milled waste stone discharged from the roller mill is transported to the raw material supply section via a circulation path. Meanwhile, the milled powder is collected in a cyclone along with the gas guided by the suction fan and recovered as a cement raw material intermediate.

[0026] The processing amount can be set appropriately depending on the type of waste, production scale, etc., but from the viewpoint of gold recovery efficiency, it is preferably 15 to 400 t / h, more preferably 50 to 300 t / h, and even more preferably 150 to 250 t / h.

[0027] <Third process> This process involves grinding the mill waste stone separated in the second process and the mixture prepared in the first process in a roller mill to separate it into fine mill flour and mill waste stone, magnetically separating and / or eddy current separating the mill waste stone into metals and non-metals, grinding the non-metals and the mixture prepared in the first process in a roller mill to separate it into fine mill flour and mill waste stone, and magnetically separating and / or eddy current separating the mill waste stone into metals and non-metals. This process is repeated for a predetermined time. In this process, first, the mill waste stone obtained in the second process is used as part of the raw material, and is re-introduced into the roller mill together with the mixture prepared in the first process, where they are ground and separated into fine mill flour and mill waste stone, and the separated mill waste stone is then magnetically separated and / or eddy current separated into metals and non-metals. The separated non-metals are then used as part of the raw materials, and are re-introduced into the roller mill together with the mixture prepared in the first step, crushed and separated into mill refined powder and mill waste stone. The separated mill waste stone is then subjected to magnetic separation and / or eddy current separation to separate metals and non-metals. This process is repeated for a predetermined period of time. In this way, the non-metals separated from the mill waste stone by magnetic separation and / or eddy current separation are used as part of the raw materials, and together with the above-mentioned mixture, gold is concentrated in the mill waste stone by repeatedly treating it with a combination of roller mill crushing and predetermined physical separation for a predetermined period of time. This suppresses the migration of gold to the mill refined powder, making it possible to recover a high-quality cement raw material intermediate as mill refined powder.

[0028] In this process, for example, the mill waste stone discharged from the roller mill in the second process is returned to the raw material supply section via a circulation path, and the raw material supply section supplies the mill waste stone together with the mixture prepared in the first process to the roller mill and grinds it, separating it into refined mill powder, which is carried by the air current and discharged from the roller mill, and the mill waste stone, which is discharged from the discharge section below the roller mill. Next, the refined mill powder is recovered as a cement raw material intermediate, while the separated mill waste stone is transported to a magnetic separator / eddy current separator, where it is separated into metals and non-metals. Thereafter, the non-metals are returned to the raw material supply section via a circulation path, and the raw material supply section supplies the non-metals together with the mixture prepared in the first step to the roller mill, where they are crushed and separated into mill fine powder and mill waste stone. The mill fine powder is recovered as a cement raw material intermediate, while the separated mill waste stone is transported to the magnetic separation section / eddy current separation section, where it is separated into non-metals and metals. This process is repeated for a predetermined period of time.

[0029] In this step, the amount of mill waste stone used is 10 to 100 parts by mass per 100 parts by mass of the mixture prepared in the first step, but from the viewpoint of concentrating valuable metals, it is preferably 30 to 100 parts by mass, more preferably 50 to 100 parts by mass, and even more preferably 70 to 100 parts by mass. The amounts of mill waste stone and the mixture prepared in the first step used are based on dry mass. The amounts of mill waste stone and the mixture prepared in the first step used can be appropriately set depending on the capacity of the roller mill.

[0030] The magnetic separation and eddy current separation can be carried out in any order, but from the viewpoint of efficient removal of metals, it is preferable to carry out eddy current separation of non-metals separated by magnetic separation. A magnetic separator can be used for magnetic separation, and an eddy current separator can be used for eddy current separation. The specific configurations of the magnetic separator and the eddy current separator are as explained in the preliminary treatment step.

[0031] The treatment time is not particularly limited and can be set appropriately depending on the production scale, etc., but if it is too long, the amount of valuable metals scattered into the milled powder side increases, and if it is too short, the frequency of switching between operations increases, making the operation complicated and reducing the amount of grinding. Therefore, 1 to 20 days is preferable, 1 to 15 days is more preferable, 1 to 10 days is even more preferable, and 2 to 5 days is even more preferable.

[0032] <Fourth step> This process separates the mill waste rock discharged after a predetermined time in the third process into heavy and light products by wind sorting, thereby removing relatively large grains of stainless steel and iron with high specific gravity as heavy products and recovering gold and other light products. In this step, an air sorter can be used. The air sorter can be an industrial device, and may be, for example, a zigzag type or an internal circulation type, and the type is not particularly limited. The wind speed for wind sorting is preferably set at approximately maximum capacity, from the viewpoint of preventing stainless steel or iron from being mixed into the lightweight items, and can be, for example, 30 m / sec or more.

[0033] <5th step> This process recovers the light products separated in the fourth process. This allows for the recovery of gold concentrate. In addition, the milled powder discharged on the air current can be effectively used as a high-quality cement raw material intermediate with reduced metal contamination.

[0034] Second Embodiment The recovery method according to this embodiment will be described below. Fig. 2 shows a flowchart of a preferred embodiment of the recovery method according to this embodiment.

[0035] The recovery method according to this embodiment includes steps 1 to 5, similar to the recovery method according to the first embodiment, but differs from the recovery method according to the first embodiment in that it includes a circulation step, after step 3 and before step 4, in which the mill waste stone discharged after a predetermined time in step 3 is crushed in a roller mill to separate it into refined mill powder and mill waste stone, and then the mill waste stone is crushed in a roller mill to separate it into refined mill powder and mill waste stone, and this process is repeated for a predetermined time, as shown in Figure 2. Note that steps 1 to 5 are as described in the first embodiment.

[0036] In the circulation process, the operation of separating the milled powder, which is discharged from the roller mill on the air current, and the milled waste, which is discharged from the discharge section at the bottom of the roller mill, is repeated for a predetermined period of time. This prevents gold from migrating to the milled powder side, while concentrating gold in the milled waste, allowing gold to be recovered more efficiently from valuable metal-containing waste.

[0037] The processing amount in the circulation step can be set appropriately depending on the type of waste, the production scale, etc., but from the viewpoint of gold recovery efficiency, it is preferably 15 to 400 t / h, more preferably 50 to 300 t / h, and even more preferably 150 to 250 t / h. The treatment time (circulation time) is not particularly limited and can be set appropriately depending on the production scale, etc., but is preferably 15 minutes to 24 hours, more preferably 20 minutes to 12 hours, even more preferably 25 minutes to 6 hours, and even more preferably 30 minutes to 3 hours.

[0038] The mill waste stone discharged after a predetermined time in the circulation step may be supplied to the fourth step and subjected to air sorting. [Example]

[0039] The following examples will explain the present invention in more detail, but the present invention is not limited to the examples below.

[0040] 1. Raw materials used in this example (1) Valuable metal-containing waste: municipal waste incineration bottom ash (2) Cement raw materials: clays, silica, limestone, and slag

[0041] 2. Equipment used in this example Wind sorter: Made by Impact Official model number: Zigzag Unit 600 Size: W1663×D7777×H7510mm ·Equipment power: 200V Fan: 22KW Input / output rotary valve: 1.5KW

[0042] 3.Analysis method Gold Analysis The samples pretreated by matte melting were crushed to 100 μm or less and analyzed in accordance with JIS M 8111.

[0043] Example 1 <First step> The incineration bottom ash and clay were mixed and dried in a dryer until the moisture content was 4% by mass or less to obtain a dried material. Next, 14% by mass of the dried material, 5% by mass of silica, 2% by mass of limestone, and 79% by mass of slag were mixed on the conveyor of the raw material supply section to prepare a mixture. The proportion of incineration bottom ash in the mixture was 4% by mass on a dry mass basis.

[0044] <Second process> The mixture prepared in the first step was fed into a vertical roller mill and pulverized to separate it into mill fine powder and mill waste stone. The mill fine powder was passed through a separator and collected in a cyclone, and the mill waste stone was collected from the bottom of the vertical roller mill. The mill fine powder was used as a cement raw material intermediate.

[0045] <Third process> The mill waste stone recovered in the first step and the mixture prepared in the first step were re-introduced into a vertical roller mill and crushed to separate it into fine mill powder and mill waste stone. The fine mill powder was recovered as a cement raw material intermediate in the same manner as above, and the mill waste stone was recovered from the bottom of the vertical roller mill. The recovered mill waste stone was then separated into magnetized and non-magnetized materials using a suspended magnetic separator (effective magnetic flux density 300 G), and some of the magnetic metals were recovered as magnetized materials. The recovered non-magnetized materials were then re-introduced into the vertical roller mill together with the mixture prepared in the first step and crushed to separate it into fine mill powder and mill waste stone. The fine mill powder was recovered as a cement raw material intermediate in the same manner as above, and the mill waste stone was recovered from the bottom of the vertical roller mill. This process of separating the mill waste stone into magnetized and non-magnetized materials using a suspended magnetic separator (effective magnetic flux density 300 G) was repeated for three days. The feed rate of the mixture was 3 t / h, and the amount of mill waste stone used was 99 parts by mass per 100 parts by mass of the mixture.

[0046] <Circulation grinding> In the second step, the mill waste stone recovered after three days was recharged into the vertical roller mill and crushed to separate it into refined mill powder and mill waste stone, the refined mill powder was recovered as a cement raw material intermediate in the same manner as above, and the mill waste stone was recovered from the bottom of the vertical roller mill. Thereafter, the recovered mill waste stone was recharged into the vertical roller mill and crushed to separate it into refined mill powder and mill waste stone, the refined mill powder was recovered as a cement raw material intermediate in the same manner as above, and the mill waste stone was recovered from the bottom of the vertical roller mill. This process was repeated for 30 minutes.

[0047] <Fourth process (wind sorting)> The mill waste collected in the circulation process was separated into heavy and light products using an air sorter. The air sorting was carried out at a mill waste supply rate of 3 t / h and at the maximum capacity of the equipment, 60 Hz (internal wind speed 30 m / s).

[0048] <5th step (recovery)> The gold (Au) concentration of the recovered light products was analyzed, and the results are shown in Table 1.

[0049] Example 2 In the fourth step, gold (Au) was recovered as a light product by the same procedure as in Example 1, except that the hourly supply rate of mill waste stone was changed to 10 t / h. The gold (Au) concentration of the recovered light product was then analyzed. The results are shown in Table 1.

[0050] Comparative Example 1 The mill waste stone was collected after the recycling process without air separation and analyzed for gold (Au) concentration. The results are shown in Table 1.

[0051] [Table 1]

[0052] Table 1 shows that gold can be significantly concentrated in light products by repeating the following process for a predetermined time: (1) preparing a mixture containing valuable metal-containing waste and cement raw materials; (2) crushing this mixture in a roller mill to separate it into mill flour and mill waste; (3) crushing this mill waste together with the mixture as part of the raw materials in a roller mill to separate it into mill flour and mill waste, and then separating the mill waste by magnetic separation and / or eddy current separation into metals and non-metals; (4) crushing the non-metals together with the mixture as part of the raw materials in a roller mill to separate it into mill flour and mill waste, and then separating the mill waste by magnetic separation and / or eddy current separation into metals and non-metals; and then air separating the mill waste after the predetermined time has passed to recover the light products.

Claims

1. A first step of preparing a mixture by mixing valuable metal-containing waste with a cement raw material containing one or more selected from limestone, silica stone, clays, and slag; a second step of milling the mixture prepared in the first step using a roller mill to separate it into mill fine powder and mill waste; a third step in which the mill waste stone separated in the second step and the mixture prepared in the first step are pulverized in a roller mill to separate the mill waste stone and fine mill powder, the mill waste stone is separated by magnetic separation and / or eddy current separation into metals and non-metals, the non-metals and the mixture prepared in the first step are pulverized in a roller mill to separate the mill waste stone and fine mill powder, and the mill waste stone is separated by magnetic separation and / or eddy current separation into metals and non-metals, and this process is repeated for a predetermined time, wherein the amount of the mill waste stone used is 10 to 100 parts by mass per 100 parts by mass of the mixture; a fourth step of separating the mill waste stone discharged after a predetermined time in the third step by wind sorting into heavy products and light products; A fifth step of recovering the light product separated in the fourth step. A method for recovering gold from valuable metal-containing waste, comprising:

2. 2. The method for recovering waste stone according to claim 1, further comprising a circulation step, after the third step and before the fourth step, of crushing the mill waste stone discharged after a predetermined time in the third step with a roller mill to separate it into refined mill flour and mill waste stone, and then crushing the mill waste stone with a roller mill to separate it into refined mill flour and mill waste stone, and repeating this process for a predetermined time, and supplying the mill waste stone discharged after the predetermined time in this step to the fourth step.

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