JP7818697B2 - Method for separating stainless steel and method for processing scrap electrical and electronic parts - Google Patents

Description

The present invention relates to a method for separating stainless steel and a method for processing scrap electrical and electronic components.

In recent years, efforts to conserve resources have led to the recovery of valuable metals from scrap electrical and electronic components such as discarded home appliances, PCs, and mobile phones, and efficient recovery methods are being investigated. For example, Japanese Patent No. 6050222 (Patent Document 1) describes crushing copper-containing electrical and electronic component scraps to a specified size and processing the crushed electrical and electronic component scraps in a copper smelting furnace (flash furnace).

In addition, Japanese Patent Publication No. 6228843 (Patent Document 2) describes a process for pulverizing copper-containing electrical and electronic component scraps, classifying the pulverized electrical and electronic component scraps using an air classifier, and recovering the fine powder of the pulverized electrical and electronic component scraps. The recovered fine powder of the electrical and electronic component scraps is introduced into a smelting furnace for processing, and the unrecovered granular material is processed in an oxidation smelting furnace (converter).

Patent No. 6050222 Patent No. 6228843

As described in Patent Documents 1 and 2, in order to process electrical and electronic component scrap in a smelting furnace such as a flash smelting furnace, the electrical and electronic component scrap must first be pulverized. However, the pulverized electrical and electronic component scrap contains organic matter such as resin, and these organic matter, such as resin, contain components such as carbon that act as reducing agents in the flash smelting furnace. If these components are unable to react sufficiently with the combustion air, problems such as over-reduction can occur.

On the other hand, the amount of electrical and electronic component scrap being processed has been increasing in recent years, and depending on the type of substances contained in the raw electrical and electronic component scrap, larger amounts of substances that are undesirable for processing in the subsequent copper smelting process (smelting inhibitors) may be added to the furnace than before.

For example, in the case of a converter, if the amount of smelting inhibitors fed into the converter increases as the amount of electrical and electronic component scrap processed increases, impurities may not be completely separated in the converter, resulting in a high level of impurities when producing anodes for electrolysis. To improve this situation, it is desirable to remove smelting inhibitors from the electrical and electronic component scrap fed into the converter in advance. For example, pulverized scraps from electrical and electronic component scrap contain stainless steel, which contains nickel (Ni), chromium (Cr), and other smelting inhibitors. Therefore, it is desirable to efficiently remove stainless steel from the pulverized scraps before feeding them into the furnace.

In consideration of the above problems, the present disclosure provides a method for separating stainless steel and a method for processing scrap electrical and electronic components that can efficiently separate stainless steel from scrap electrical and electronic components, particularly from crushed scrap obtained by crushing scrap electrical and electronic components.

In order to solve the above problem, according to one aspect of the present disclosure, a method for separating stainless steel is provided, which includes a crushing process for crushing electrical and electronic component scraps, an airflow classification process for classifying the crushed material obtained in the crushing process using an airflow to obtain waste stones containing stainless steel as heavy materials, a coarse waste stone sorting process for selecting and recovering coarse waste stones of a predetermined size or larger from the waste stones, and a first magnetic sorting process for magnetically sorting the coarse waste stones to obtain coarse waste stones containing stainless steel from the coarse waste stones as magnetic materials.

According to another aspect of the present disclosure, there is provided a method for treating scrap electrical and electronic components, including the above-mentioned stainless steel separation method, comprising a smelting furnace treatment step in which the finely pulverized material obtained in the air classification step is fed into a smelting furnace for treatment, and an oxidation smelting furnace treatment step in which at least a portion of the non-magnetic material obtained in the first magnetic separation step is fed into an oxidation smelting furnace for treatment.

The present disclosure provides a method for separating stainless steel and a method for processing scrap electrical and electronic components that can efficiently separate stainless steel from scrap electrical and electronic components, particularly from pulverized scrap electrical and electronic components.

1 is a flowchart showing an example of a stainless steel separation method according to an embodiment of the present invention. 1 is a schematic diagram showing an example of the configuration of a vertical roller mill that can be used in a stainless steel separation method according to an embodiment of the present invention. FIG. 1 is a schematic diagram illustrating an example of an eddy current separator. FIG. 10 is a schematic diagram illustrating an example of an air table.

Embodiments of the present invention will be described below with reference to the drawings. The embodiments shown below are examples of devices and methods that embody the technical concept of this invention, and the technical concept of this invention does not limit the structure, arrangement, etc. of component parts to those described below.

(Method of separating stainless steel)
As shown in FIG. 1, the stainless steel separation method according to an embodiment of the present invention includes a crushing step S2 in which electrical and electronic component scraps are crushed, an airflow classification step S3 in which the crushed material obtained in the crushing step S2 is classified using an airflow to obtain heavy waste stones containing stainless steel, a coarse waste stone sorting step S4 in which coarse waste stones of a predetermined size or larger are selected and recovered from the waste stones, and a first magnetic sorting step S6 in which coarse waste stones of the predetermined size or larger are magnetically sorted to obtain coarse waste stones containing stainless steel from the coarse waste stones as magnetically attached materials.

Prior to the crushing step S2, it is preferable to perform an incineration step S1 to incinerate at least a portion, preferably all, of the electrical and electronic component scrap. Incineration of the electrical and electronic component scrap in the incineration step S1 prior to the crushing step S2 removes at least a portion of the organic matter, such as resins, contained in the electrical and electronic component scrap, and reduces the volume of material to be processed. Furthermore, removing at least a portion of the organic matter, such as resins, contained in the electrical and electronic component scrap through incineration prevents over-reduction problems caused by carbon components contained in the electrical and electronic component scrap during processing in a smelting furnace, and also prevents damage to the furnace bricks and jacket. Furthermore, the metals contained in the electrical and electronic component scrap become brittle, facilitating crushing in the subsequent crushing step S2. Incineration removes volatile components from the electrical and electronic component scrap, thereby preventing the intrusion of fluorine, chlorine, bromine, and other smelting inhibitors into the smelting furnace.

Specific conditions for the incineration step S1 are not particularly limited, but for example, electrical and electronic component scraps are incinerated in a rotary kiln at approximately 550 to 1000°C and then cooled. The incinerated material after the incineration process may be further sieved, for example, using a sieve with openings of 10 to 20 mm.

In the crushing process S2, the scrap electrical and electronic components are crushed using a crusher. During this crushing process, the scrap electrical and electronic components are crushed to a particle size that allows unburned carbon to oxidize, Cu to react with S in the copper concentrate to form matte, and Fe to react with oxygen to form slag, before the scrap sinks to the bottom of the smelting furnace (e.g., flash furnace) settler or is discharged from the matte and slag discharge section.

Specifically, since the particle size of the concentrate charged into a smelting furnace is generally 10 to 150 μm in volumetric D50 (median diameter), it is preferable to pulverize, for example, electrical and electronic component scrap until the volumetric D50 is 150 μm or less. Alternatively, electrical and electronic component scrap may be pulverized until the volumetric D80 is 250 μm or less. Here, powders with a D50 of 150 μm or less and granules with a D80 of 250 μm or less are as fine as powder, and much finer than sand-like particles the size of sand grains. It is preferable to obtain a pulverized product by pulverizing until such fine particles like powder are obtained.

In the crushing step S2, scrap electrical and electronic components may be mixed with silica ore, which is charged into the smelting furnace together with the copper concentrate, and crushed. Typically, in non-ferrous smelting furnaces, a solvent such as silica ore is charged into the smelting furnace along with the raw concentrate to improve the fluidity of the slag. However, when purchasing the solvent, it is often purchased in inexpensive block form, and the solvent is often crushed in-house using a ball mill or similar. Therefore, if the solvent mill has sufficient capacity, scrap electrical and electronic components can be mixed with silica ore, which is charged into the smelting furnace together with the copper concentrate, and crushed, eliminating the cost of installing crushing equipment.

In the air classification process S3, the pulverized material obtained in the crushing process S2 is separated into light and heavy materials by adjusting the airflow using the air classification effect, thereby controlling the particle size of the crushed electrical and electronic component scrap after crushing. In other words, in the air classification process S3, crushed materials with a high specific gravity among the electrical and electronic component scrap cannot be carried upward by the airflow unless they are finely crushed. Therefore, by utilizing this effect, finely crushed materials below a predetermined size are carried upward by the airflow and collected in the light material side, and crushed materials with large particle sizes that could not be collected in the light material side are separated into the heavy material side as waste stone.

The crushing step S2 and the air classification step S3 are preferably carried out simultaneously using a vertical roller mill such as the one shown in Figure 2. In processing using a vertical roller mill, the electrical and electronic component scraps to be crushed are first fed to the center of a horizontally rotating table via a screw feeder. The table has recesses formed along its outer periphery. The electrical and electronic component scraps fed to the center of the table are then moved toward the outer periphery of the table by centrifugal force. At this time, the electrical and electronic component scraps are crushed between the table and two to three rollers attached along the top surface of the recesses in the table.

The finely pulverized electrical and electronic component scraps move outward and are blown upward by an ascending air current (using atmospheric air) flowing from below. They are classified (air current classification) and transported to the rotor above for collection. Meanwhile, crushed materials with a high specific gravity fall downward, are crushed again by the rollers and table, and are blown upward again and transported to the rotor for collection. Crushed materials with a high particle size or specific gravity that were not classified into the lighter materials remain around the table. The heavy materials remaining around the table are called waste rock. This waste rock contains stainless steel, which constitutes smelting inhibitors such as Ni and Cr, in addition to copper. Separating the stainless steel from this waste rock allows for efficient recovery and effective use, while also reducing the amount of smelting inhibitors input into smelting processes such as converters and flash smelting furnaces.

The pulverization step S2 and the air classification step S3 may be carried out separately in separate devices without using a vertical roller mill. Furthermore, the pulverized material may be roughly crushed using a hammer crusher or the like before being processed in the vertical roller mill.

In the coarse waste stone sorting process S4, coarse waste stones of a predetermined size or larger are sorted from the waste stones obtained in the air classifying process S3. The coarse waste stone sorting process S4 is not particularly limited as long as it is capable of sorting coarse waste stones into predetermined particle sizes, but it is preferable to include a sieving process in which sieves are used to sift out waste stones of a predetermined size or larger.

Table 1 shows examples of chemical analysis values for valuable metals contained in waste rocks of various sizes when the waste rocks were sieved using sieves with different mesh sizes. The component analysis of valuable metals was evaluated using inductively coupled plasma optical emission spectroscopy (ICP-OES). The waste rock sizes shown in Table 1 represent the nominal mesh size W (mm) of the sieve based on JIS Z8801-1. The "%" listed as the unit for each element refers to the weight percentage of the target element in the waste rocks of each size. Because the concentrations of Au and Ag are low, they are evaluated in "g/t (equivalent to ppm)."

As shown in Table 1, it has been newly discovered that the larger the size of the waste stone, the higher the content of Cr and Ni, which make up stainless steel. To efficiently recover stainless steel, it is preferable to use a sieve with a nominal mesh size W of 3.35 mm or more, preferably 5.6 mm or more, and more preferably 9.5 mm or more, and collect the waste stone that has been separated into the oversized material as coarse waste stone for stainless steel recovery. Here, for example, a size of greater than 1.0 mm to 3.35 mm refers to waste stone that has been separated into the undersized material using a sieve with a nominal mesh size of 3.35 mm and that has been separated into the oversized material using a sieve with a nominal mesh size of 1.0 mm.

Furthermore, for the coarse waste stone sieved into the specified size groups shown in Table 1, we focused on five components - Cu, Fe, Al, SUS, and other metals - as the main metallic elements contained in the coarse waste stone with particle sizes of over 5.6 mm to 6.7 mm, over 6.7 mm to 9.5 mm, over 9.5 mm to 16.0 mm, and over 16.0 mm - and examined the proportion of SUS among these. Analysis of Cu, Fe, Al, SUS, and other metals was performed by hand sorting, and a comprehensive judgment was made based on the magnetic properties of the raw material, the color, hardness, and weight of the polished surface when the raw material was sanded. As a result, it was found that the SUS ratio in the coarse waste stones with a particle size of more than 5.6 mm to 6.7 mm was 11.4%, the SUS ratio in the coarse waste stones with a particle size of more than 6.7 mm to 9.5 mm was 16.5%, the SUS ratio in the coarse waste stones with a particle size of more than 9.5 mm to 16.0 mm was 17.2%, and the SUS ratio in the coarse waste stones with a particle size of more than 16.0 mm was approximately 27.4%, and that the larger the particle size, the higher the ratio of SUS in the composition.

These analysis results demonstrate that, in order to efficiently recover stainless steel from coarse waste stone, it is effective to carry out a process of recovering coarse waste stone of a certain size or larger. Considering the efficiency of stainless steel recovery and the ease of handling the material to be sorted when using a sorting device such as a metal sorter, described below, it is preferable to use a sieve with a nominal mesh size W of 5.6 mm or more, preferably 6.7 mm or more, or even 9.5 mm or more, to collect waste stone of a size that will be sorted into the oversize material. There is no particular upper limit to the size of the coarse waste stone, but it is typically 100 mm or less, or even 50 mm or less.

The sieving process is preferably performed after the air classification process S3. If the pulverized material after the crushing process S2 is sieved directly without performing the air classification process S3, there is a risk that finely pulverized material adhering to the surface of the large-particle-sized pulverized material will be separated as sieved material. Because the finely pulverized material has a high copper and precious metal content, it will cause a loss of valuable resources when recovering coarse waste stone containing stainless steel. By performing the air classification process S3 on the pulverized material after the crushing process S2 and then selecting coarse waste stone above a predetermined size in the sieving process, the finely pulverized material can be separated and recovered from the waste stone in the air classification process S3, thereby minimizing the amount of finely pulverized material adhering to the waste stone.

Next, in the first magnetic separation process S6, coarse waste containing stainless steel is obtained as magnetic material (magnetic material 2) from the coarse waste recovered in the coarse waste separation process S4. Most of the copper, aluminum, etc. that make up the coarse waste is separated into the non-magnetic material (non-magnetic material 2). In order to efficiently obtain coarse waste containing stainless steel as magnetic material, it is preferable to perform high-force magnetic separation in the first magnetic separation process, for example, using a magnet pulley, with a magnetic flux density of 3000 to 7000 G. This allows coarse waste containing copper, aluminum, etc. to be separated into the non-magnetic material, while coarse waste containing stainless steel can be selectively and efficiently recovered into the magnetic material.

It is preferable to include a second magnetic separation process S5 prior to the first magnetic separation process S6, in which the coarse waste stone is magnetically separated at a lower magnetic force than the first magnetic separation process S6, and the coarse waste stone containing iron is preliminarily removed as the magnetized material (magnetized material 1), thereby obtaining the non-magnetized material 1. Because iron is more easily attracted to magnets at a lower magnetic force than stainless steel, performing the process at a lower magnetic force than the first magnetic separation process S6 can ensure that nearly 100% of the coarse waste stone containing iron is separated into the magnetized material. For example, it is preferable to perform low-force magnetic separation in the second magnetic separation process, using a suspended magnetic separator with a magnetic flux density of 200 to 600 G. By preliminarily removing the iron that would otherwise be magnetically attracted to the magnetized material in the second magnetic separation process S5, the incorporation of coarse waste stone containing iron can be prevented in the first magnetic separation process S6, and the coarse waste stone containing stainless steel can be efficiently concentrated in the magnetized material.

Next, in the eddy current sorting process S7, the magnetically-attached material obtained in the first magnetic sorting process S6 is eddy-current sorted, and coarse waste stones containing stainless steel are obtained as non-repulsive material from the magnetically-attached material obtained in the first magnetic sorting process S6. In the eddy current sorting process S7, for example, sorting can be performed using an eddy current sorter as shown in Figure 3.

The eddy current separator includes, for example, a belt conveyor stretched between a tail pulley (not shown) and a head pulley, an eccentric magnet located inside the head pulley, a drive unit (not shown) that rotates the belt conveyor, a non-repulsive object collection unit located below the head pulley to collect non-repulsive objects that fly up from the belt conveyor, a repulsive object collection unit located below the head pulley and forward of the non-repulsive object collection unit, and a damper located between the non-repulsive object collection unit and the repulsive object collection unit to separate the repulsive objects that fly up from the non-repulsive objects. As shown in Figure 3, by using an eccentric eddy current separator in which the rotation axis of the pulley and the rotation axis of the eccentric magnet do not coincide, the entrapment of magnetic objects is reduced and rough waste stone, including stainless steel, can be separated efficiently.

In order to efficiently separate coarse waste stones containing stainless steel from the magnetically attached materials 2 in the first magnetic separation process S6 and transfer them to the non-repulsive materials, for example, the rotor rotation speed of the eddy current separator is set to 2000-2700 rpm, preferably 2250-2500 rpm, and the belt conveyor speed is set to 90-110 m/min, preferably 95-105 m/min. Furthermore, in order to efficiently separate coarse waste stones containing stainless steel and transfer them to the non-repulsive materials, it is preferable to appropriately adjust the damper angle (angle θ in Figure 3).

For example, the damper angle is preferably 55° or more, and more preferably 60° or more. On the other hand, if the damper angle is too large, there is a risk that coarse stone waste containing copper, aluminum, etc. may be mixed into the non-repulsion side. In this embodiment, the damper angle is preferably adjusted to approximately 50-70°, more preferably approximately 55-67°, and even more preferably approximately 58-65°. For example, by adjusting the damper angle to approximately 58-65°, 90% or more of the stainless steel in the coarse stone waste can be recovered on the non-repulsion side.

Next, in the shape sorting process S8, the non-repulsive materials obtained in the eddy current sorting process S7 are shape-sorted, and crude waste containing stainless steel is obtained as a heavy product. In the example of Figure 1, the shape sorting process S8 is performed after the eddy current sorting process S7. However, the order of processing may be changed, for example, by omitting the eddy current sorting process S7 and shape-sorting the magnetic materials obtained in the first magnetic sorting process S6, resulting in crude waste containing stainless steel as a heavy product. Various sorting machines that utilize differences in specific gravity and shape of the target materials can be used as shape sorters, and the type is not particularly limited. For example, a rolling sorter that rolls the raw material for sorting can be typically used, and an air table, for example, is preferably used.

The coarse waste stone containing stainless steel separated in the first magnetic separation process S6 is often plate-shaped. On the other hand, other coarse waste stone containing copper, aluminum, etc. is often nearly spherical in shape. Therefore, by using shape separation in the shape separation process S8, which takes advantage of differences in specific gravity and shape of the target materials, it is possible to more efficiently recover plate-shaped coarse waste stone containing stainless steel.

A single-axis air table sorter can be used as the shape sorter. For example, but not limited to, an air table sorter such as the one shown in Figure 4 can be used. The air table sorter is used to separate light and heavy products by dry gravity separation. It is equipped with a vibrating table that is inclined at a predetermined angle and has multiple small vents (not shown) that allow air to pass through, and that vibrates in a predetermined direction, a holding section (not shown) that holds the vibrating table, an upflow fan (not shown) that is installed below the holding section and supplies air from the bottom to the top of the vibrating table, and a hopper (not shown) that feeds raw materials onto the vibrating table.

The plate-shaped coarse waste rock containing stainless steel fed onto the vibrating table is subjected to a force that moves it towards the heavy product side due to the vibration of the vibrating table. On the other hand, light or spherical objects are strongly affected by the tilt and are recovered on the light product side.

In the shape sorting process S8, to more efficiently recover coarse waste rock containing stainless steel, the inclination angle of the vibrating table relative to the horizontal plane is preferably 10° or less, more preferably 9° or less, and even more preferably 8° or less. If the inclination angle is too small, the separation efficiency between light and heavy products may not be improved. Therefore, the inclination angle of the vibrating table is preferably 5° or more, more preferably 6° or more, and even more preferably 7° or more. In this embodiment, for example, by adjusting the inclination angle of the vibrating table to 6-10°, 85% or more of the stainless steel can be distributed to the heavy product side of the coarse waste rock containing stainless steel, and in one embodiment, 92% or more can be distributed, thereby enabling efficient separation and recovery of stainless steel. The vibration frequency of the vibrating table can be adjusted as needed. Typically, the frequency is adjusted between 50 and 60 Hz, more preferably between 55 and 60 Hz. Air may also be supplied from a blow-up fan as needed.

Next, in the metal sorting process S9, the heavy product obtained in the shape sorting process S8 is sorted for metals using a metal sorter equipped with a sensor capable of detecting the strength of metal reactions, and the coarse waste containing stainless steel is separated and recovered from the coarse waste containing copper and brass. By including the metal sorting process S9, the concentration of stainless steel in the separated and recovered material can be increased, further increasing the efficiency of stainless steel recovery.

The metal sorter used in the metal separation process S9 requires sensing technology that can selectively detect stainless steel from mixed metals that include stainless steel, copper, brass, etc. Examples of metal sorters include metal sorters that use sensing technologies such as transmission X-ray (XRT), X-ray fluorescence (XRF), laser-induced plasma (LIBS), near-infrared (NIR), visible light (VIS), electromagnetic induction (ISS), and Raman spectroscopy.

In particular, in order to efficiently separate and recover coarse waste stone containing stainless steel from the electrical and electronic component scrap of this embodiment, it is preferable to use a metal sorter that uses electromagnetic induction (ISS) sensing technology. In such metal sorters that use electromagnetic induction (ISS) sensing technology, there are two types of detection methods for metal reactions: one that detects the presence or absence of metal, and one that detects the strength of the metal reaction. In this embodiment, it is more preferable to use a metal sorter that uses a detection method that detects the strength of the metal reaction in order to efficiently separate and sort waste stone containing stainless steel. This allows for efficient separation and recovery of stainless steel from the coarse waste stone.

Although not limited to the following, a metal sorter may include, but is not limited to, a pair of pulleys (not shown) that hold the belt conveyor, a metal object recovery section and a non-metal object recovery section located below the belt conveyor, a detection section located on the underside of the belt conveyor that detects metal reactions in the raw materials by emitting electromagnetic waves from a specified area on the underside of the belt conveyor, and a sorting device such as an air nozzle that sorts objects detected by the detection section into the metal object recovery section or the non-metal object recovery section.

In metal sorters using electromagnetic induction (ISS) sensing technology, if the particle size of the raw material supplied to the metal sorter is too small, the sorting section may be unable to sort the raw material efficiently, resulting in reduced recovery efficiency. Therefore, it is preferable to set the particle size of the coarse waste ore supplied to the metal sorter so that it is equal to or greater than the lower limit of particle size that can be sorted by the metal sorter. For example, by determining the size of the coarse waste ore in advance in the above-mentioned coarse waste ore sorting process S4 so that it is equal to or greater than the lower limit of particle size that can be sorted by the metal sorter, the metal sorting efficiency in the subsequent metal sorting process S9 can be improved. The specific conditions for the lower limit of particle size of the coarse ore that can be sorted by the metal sorter are not particularly limited, but are, for example, approximately 5 mm, more preferably 8.0 mm or more, and even more preferably 10.0 mm or more.

Table 2 shows the SUS recovery rate (weight ratio) and concentration ratio when coarse waste rock of various particle sizes is sorted using a metal sorter with ISS-type sensing technology that detects the strength of metal reactions. The sizes of each coarse waste rock shown in Table 2 correspond to the nominal mesh size W (mm) of the sieve based on JIS Z8801-01. The concentration ratios shown in Table 2 represent the concentration ratio of SUS contained in the recovered coarse waste rock after sorting relative to the weight of SUS contained in the coarse waste rock before sorting. As shown in Table 2, in the case of coarse waste rock with a particle size of 8.0 mm or larger that is sorted into the oversized material using a sieve with a nominal mesh size W of more than 8.0 mm, the SUS ratio in the recovered material after sorting is 90% or higher in all cases. In other words, by sorting coarse waste rock with a particle size of 8.0 mm or larger using a metal sorter, the SUS ratio in the recovered material after sorting can be improved.

Table 3 shows examples of measurement results for the composition ratios and distribution rates of the major components in the coarse waste stone contained in the sieved material separated in the coarse waste stone sorting process S4 in Figure 1, the magnetic material 1 separated in the second magnetic sorting process S5, the non-magnetic material 2 separated in the first magnetic sorting process S6, the repulsed material separated in the eddy current sorting process S7, and the heavy and light products separated in the shape sorting process S8. In the coarse waste stone sorting process S4, a sieve with a nominal mesh size of 5.6 mm was used. In the second magnetic sorting process S5, a suspended magnetic separator was used to set the magnetic flux density to 400 G, and in the first magnetic sorting process S6, a magnetic pulley was used to set the magnetic flux density to 7000 G. In the eddy current sorting process S7, the damper angle was 62°, the rotor rotation speed was 2250 rpm, and the belt conveyor speed was 103 m/min. In the shape sorting process S8, the tilt angle was 8°, the table vibration frequency was 50 Hz, and the wind speed was 0 mm/s. In Table 3, the analysis of the composition ratios of stainless steel, copper/brass, iron, and aluminum was performed by manual sorting, comprehensively assessing the magnetic properties of the raw materials, the color, hardness, and weight of the polished surface when the raw materials were sanded, as judgment criteria. The composition ratio (%) refers to the weight ratio of the target material in each sorted product. The distribution ratio was calculated by setting each component of the sieved material as 100%, and calculating the weight ratio of each component separated as magnetic material 1, non-magnetic material 2, repulsive material, light product, and heavy product. As shown in Table 3, it can be seen that more than 70% of the stainless steel in the sieved material can be recovered as heavy product in the shape sorting process S8. Furthermore, most of the heavy product separated in the shape sorting process S8 is crude waste containing stainless steel and crude waste containing copper or brass. This shows that by using a metal sorter that employs sensing technology that can selectively detect stainless steel from mixed metals to separate metals from heavy products, it is possible to increase the concentration of stainless steel in the separated and recovered material and further improve the stainless steel recovery efficiency.

As described above, the stainless steel separation method according to an embodiment of the present invention recovers waste rock from crushed scraps obtained by crushing electrical and electronic component scraps, and then performs the above-described process for separating and recovering stainless steel from the waste rock, thereby enabling efficient separation of stainless steel. This reduces the amount of smelting inhibitors, such as Ni and Cr, derived from stainless steel supplied to an oxidation smelting furnace such as a converter, and minimizes the impact of impurities in the oxidation smelting furnace that may impair processing. Because the separated and recovered coarse waste rock containing stainless steel has had fine powder and other impurities removed in the airflow classification process S3, the impact of valuable metal recovery losses due to the adhesion of fine powder containing valuable metal components is reduced, and the waste rock is easier to handle than powdered material. Therefore, the stainless steel separation method according to an embodiment of the present invention allows for selective and efficient separation and recovery of stainless steel while suppressing a decrease in valuable metal recovery efficiency.

(Method for disposing of scrap electrical and electronic components)
The method for treating scrap electrical and electronic components according to an embodiment of the present invention can include a smelting furnace treatment step in which the separated materials obtained in each step constituting the stainless steel separation method shown in Fig. 1 are fed into a smelting furnace such as a flash furnace for treatment, and an oxidation smelting furnace treatment step in which the separated materials are fed into an oxidation smelting furnace such as a converter for treatment. That is, the method for treating scrap electrical and electronic components according to an embodiment of the present invention includes a smelting furnace treatment step in which the finely pulverized material obtained in the air flow classification step S3 is fed into a smelting furnace for treatment, and an oxidation smelting furnace treatment step in which at least a portion of the non-magnetized materials 2 obtained in the first magnetic separation step S6 is fed into an oxidation smelting furnace for treatment.

The smelting furnace may be of any type, but may, for example, be comprised of a shaft, settler, and uptake (not shown), with a concentrate burner attached to the roof of the shaft. The finely pulverized material obtained in the air classification process S3, copper concentrate, a solvent (flux), and oxygen-enriched air are simultaneously blown in from the concentrate burner, causing an instantaneous oxidation reaction. The finely pulverized material and other materials that have undergone the oxidation reaction are separated into matte and slag in the settler. Furthermore, exhaust gas generated in the smelting furnace is sent to the uptake. The operating conditions of the smelting furnace in the smelting furnace treatment process may be similar to known operating conditions, regardless of whether or not scrap electrical and electronic components are added, as long as over-reduction does not occur. The treatment conditions are not particularly limited.

The oxidation smelting furnace may be of any type, but for example, it may have a furnace opening at the top of a furnace body (not shown) and a tuyere at the bottom of the side of the furnace body. At least a portion of the non-magnetic materials 2 obtained in the first magnetic separation process S6, the matte separated in the smelting furnace, and the solvent (flux) are introduced into the furnace through the furnace opening. Oxygen-enriched air is then blown in through the tuyere to oxidize at least a portion of the non-magnetic materials 2 obtained in the first magnetic separation process S6. The operation of the oxidation smelting furnace in the oxidation smelting furnace treatment process may be carried out using a known operating method as long as it does not impair the original intended function of the oxidation smelting furnace.

As shown in Figure 1, the following waste rocks are preferably fed into an oxidation smelting furnace: the coarse waste rock separated as magnetized material 1 in the second magnetic separation process S5, the coarse waste rock separated as non-magnetized material 2 in the first magnetic separation process S6, the coarse waste rock separated as repulsive material in the eddy current separation process S7, the coarse waste rock separated as light products in the shape separation process S8, and the coarse waste rock other than stainless steel separated as coarse waste rock not containing stainless steel in the metal separation process S9. Furthermore, the magnetized material 1 from the second magnetic separation process S5 and the non-magnetized material 2 obtained in the first magnetic separation process S6 may be further subjected to metal separation using a metal sorter to separate the coarse waste rock containing stainless steel into the metal side. This separated material may then be fed into any of the eddy current separation process S7, shape separation process S8, or metal separation process S9 to improve the recovery efficiency of stainless steel.

The method for processing scrap electrical and electronic components according to an embodiment of the present invention allows for the preliminary removal of stainless steel, which contains smelting inhibitors such as Ni and Cr, from raw materials supplied to an oxidation smelting furnace such as a converter. This, for example, prevents various operational problems caused by the inclusion of smelting inhibitors in the oxidation smelting furnace treatment process, enabling efficient processing. Furthermore, by recovering waste rock containing stainless steel, the stainless steel can be reused.

The present invention has been described using the above embodiments, but is not limited to these embodiments and can be embodied by modifying the components within the scope of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in each embodiment. For example, some components may be deleted from all of the components shown in the embodiments. Furthermore, components from different embodiments may be combined as appropriate.

The processing flow shown in FIG. 1 is merely an example, and various other processing procedures can be adopted. For example, the eddy current sorting process S7, the shape sorting process S8, and the metal sorting process S9 may be omitted or their order may be reversed as appropriate. For example, the eddy current sorting process S7 and the shape sorting process S8 may be omitted. It is also possible to reverse the order of the eddy current sorting process S7 and the magnetic sorting process (first magnetic sorting process S6 and second magnetic sorting process S5). Furthermore, while the above-described embodiment describes an example in which a metal sorter using ISS-type sensing technology is used as the metal sorter, it is also possible to use metal sorters using other sensing technologies, such as X-ray sorters and LIBS sorters.

S1... Incineration process S2... Crushing process S3... Air classification process S4... Rough waste stone sorting process S5... Second magnetic sorting process S6... First magnetic sorting process S7... Eddy current sorting process S8... Shape sorting process S9... Metal sorting process

Claims (9)

a crushing step of crushing scrap electrical and electronic components;
an air classification step in which the pulverized material obtained in the pulverization step is classified by airflow to obtain waste stones containing stainless steel as heavy materials;
a coarse waste stone sorting step of sorting and recovering coarse waste stones of a predetermined size or larger from the waste stones by sieving ;
a first magnetic separation step of magnetically separating the coarse waste stone to obtain coarse waste stone containing stainless steel as a magnetically attached material from the coarse waste stone. a second magnetic separation step, which is performed before the first magnetic separation step, of magnetically separating the coarse waste stones at a magnetic force lower than that in the first magnetic separation step, and removing coarse waste stones containing iron from the coarse waste stones;
2. The method for separating stainless steel according to claim 1, further comprising an eddy current sorting step of subjecting the magnetic matter obtained in the first magnetic sorting step to eddy current sorting to obtain coarse waste stone containing stainless steel as non-repulsive matter. The stainless steel separation method according to claim 1, further comprising a shape sorting step in which the magnetic material obtained in the first magnetic separation step is sorted by shape to obtain crude waste containing stainless steel as a heavy product. The stainless steel separation method according to claim 2 further comprises a shape sorting step in which the non-repulsive materials obtained in the eddy current sorting step are sorted by shape to obtain crude waste containing stainless steel as a heavy product. The stainless steel separation method according to claim 3 or 4 further includes a metal sorting step in which the heavy product obtained in the shape sorting step is sorted for metals using a metal sorter equipped with a sensor capable of detecting the strength of metal reactions, and the crude waste rock containing stainless steel is separated and recovered as metals. The stainless steel separation method described in claim 5, wherein the coarse waste stone sorting process selects and recovers coarse waste stone having a particle size equal to or larger than the lower limit of particle size selectable by the metal sorter. The method for separating stainless steel according to any one of claims 1 to 4, wherein the coarse waste stone sorting step includes a sieving step in which the sieving is performed using a sieve, and the sieving step includes obtaining, as the coarse waste stone, a sieved product obtained by sieving using a sieve having a nominal mesh size of 3.35 mm or more. The stainless steel separation method according to any one of claims 1 to 4, further comprising an incineration step of incinerating the electrical and electronic component scraps prior to the crushing step. A method for treating scrap electrical and electronic components, including the stainless steel separation method according to any one of claims 1 to 4,
a smelting furnace treatment step in which the finely pulverized material obtained in the air classification step is charged into a smelting furnace and treated therein;
an oxidation smelting furnace treatment step of charging at least a portion of the non-magnetic materials obtained in the first magnetic separation step into an oxidation smelting furnace for treatment.