JP3535629B2 - Recycling of valuable metals from scraps - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing scraps containing valuable metals such as copper, gold, silver and platinum in a flash smelting furnace for smelting copper ore. And a method for recycling valuable metals from scraps. 2. Description of the Related Art In recent years, scraps generated from the electronic component manufacturing industry and products and industries that use those electronic components (electric wire scraps, lead frames, IC chips, resinous board scraps, microminiature coils, switches, etc.) ) Tends to increase significantly. These scraps contain copper used as electrical conductors, and valuable metals such as gold, silver, platinum, and palladium used for contacts and plating films. These valuable metals are collected by recycling resources. It is also important from the viewpoint of resource saving. [0003] Scraps as described above have naturally been generated, and recycling methods are diverse. If the copper content is high and the content of other valuable metals (precious metals) is low, scraps can simply be put into the molten copper to recover the copper. Further, there is a method of incinerating a scrap containing a noble metal (burning an organic insulator) and concentrating a valuable metal in ash after burning. However, in this method, a part of the valuable metal is oxidized. Therefore, in order to recover the valuable metal, it is necessary to refine the metal using incinerated ash as a raw material. On the other hand, as a method of recovering valuable metals in scrap without oxidizing, for example, JP-A-49-531
23. In this method, an insulated wire scrap is immersed in molten lead to thermally decompose an organic insulator in a state where air is shut off and collect it as a fuel, and further collect copper without oxidizing it. As a similar method, JP-A-53-16302 discloses that a scrap is pressurized and heated in an airtight container, and an insulator (a resin such as polyvinyl chloride, rubber, polyurethane, or Teflon) is contained in the scrap.
Discloses a method of recovering a metal in an unoxidized state by decomposing and removing the metal. However, these methods have a limited throughput and are cumbersome. By the way, unlike the above-described method of treating only scrap (or pretreatment), a method of directly treating scraps in a copper smelting process is also practiced. A commonly practiced method is to load the scraps on a boat, lift the scraps using a crane, and load the scraps into a copper smelting converter (PS converter). This method is advantageous in that even unnatural scrap can be easily turned into slag and melted by utilizing the strong stirring effect of the molten metal in the converter and the reaction heat in the furnace. In addition, valuable metals such as copper, gold and silver in the scrap are recovered to a mat in the converter, that is, to the Kawa (or blister copper) with a high yield exceeding 98%. In the above-mentioned method using the overhead crane, in order to load the scrap into the furnace, the ventilation of the converter must be temporarily stopped, and the converter must be tilted. There is a problem that gas leaks from the furnace. As a method for solving these problems, there is a method of throwing scraps from the converter furnace top using a chute. In addition, Japanese Unexamined Patent Publication
As in -287655, a transfer device for transferring defective anodes, a transfer device, and a transfer charging device are installed on the converter furnace top,
When a defective anode is charged into a converter through a side door using this apparatus, there is a method in which scraps are placed on the defective anode and then charged together into the converter. [0007] As described above, when the treatment is performed in the converter, there is an advantage that the fuel and the pretreatment are hardly required, and the treatment can be performed simultaneously with the smelting of copper.
However, among the above-described methods of processing in a converter, when scrap is loaded from a furnace top through a chute or loaded on a boat, there is an adverse effect on the furnace body. That is,
Since organic insulators in scraps generally undergo thermal decomposition at a temperature of 300 ° C. or lower, hydrogen gas and carbon fumes are generated by thermal decomposition immediately after being placed in a furnace. These pyrolysis products do not burn in a furnace with a low oxygen concentration, but mix and burn with free air near the converter exhaust hood,
The converter exhaust hood is heated to a high temperature to promote wear of the exhaust hood. Further, some of the organic substances volatilized from the organic insulators (synthetic resins) in the scrap are not completely decomposed and burned, and are absorbed and colored by the sulfuric acid in the product produced from the converter exhaust gas. There is a problem. [0009] It is an object of the present invention to establish a new industrial recycling method replacing the converter treatment of scraps. [0010] Generally speaking, the method of direct treatment in the copper smelting process requires little pretreatment, so that the treatment cost is low and even if the content of valuable metals in scrap is low. It is desirable as a recycling method because there is no problem in recovery rate and mass processing. Therefore, in order to solve the problems of exhaust gas hood wear and coloring of the product sulfuric acid due to the converter treatment, the present inventor has conceived of treating scraps in a flash smelting furnace for smelting copper ore. . Unlike a converter, in a closed type flash smelting furnace, organic substances volatilized from organic insulators (synthetic resins) in scrap are completely decomposed and burned, so that coloring of the product sulfuric acid can be avoided. On the other hand, in the method of processing in a flash furnace,
A new problem arises when processing scrap containing a small proportion of valuable metals and containing a large amount of synthetic resin and inorganic insulators (such as glass fiber). That is, in the flash smelting furnace, the oxygen concentration immediately above the molten metal is extremely low, so even if the oxygen is simply introduced from the flash smelter settler, the atmospheric oxygen concentration is low. There is a problem that it will surface. Further, since the effect of stirring the molten metal in the flash smelting furnace is small as compared with the converter, the pyrolysis residue and the inorganic insulator in the scrap are not turned into slag. For this reason, transfer (sedimentation) of the valuable metal in the scrap to the mat is prevented. In addition, when a large amount is injected from the settler part, organic matter generated from synthetic resins is guided to the boiler together with the flue gas of the smelting furnace, burns in the boiler, and raises the temperature in the boiler, thereby increasing the boiler temperature of the smelting furnace dust. Induces fusion to the water tube. In order to realize the processing of scraps in a flash furnace, it is necessary to overcome these problems. As a result of repeated studies, the present inventors have found that by charging scraps from the shaft ceiling of the flash smelting furnace, these problems can be solved and the flash smelting treatment of scraps can be put to practical use. Was found. Thus, the present invention is characterized in that scraps containing valuable metals are loaded into a flash smelting furnace for smelting copper ore from a shaft ceiling portion, and the valuable metals are collected on a mat retained in the furnace. To provide a recycling method for valuable metals. It is most practical to grind the scraps in advance, mix them with the charge for smelting copper ore, and charge the scrap from the flash smelter concentrate burner into the furnace. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a flash smelting furnace for smelting copper ore is composed of a shaft 1, a settler 2 and an uptake 3. Equipped with one to four concentrate burners 5. A charge for copper ore smelting is injected from a concentrate burner, and generally a fine concentrate is blown together with a solvent (flux) simultaneously with oxygen-enriched air or oxygen or high-temperature hot air to cause an instantaneous oxidation reaction.
Since the calorific value is insufficient with only the heat of oxidation reaction, heavy oil is usually burned from a concentrate burner. While falling through the shaft,
The concentrate melts at a high temperature of 1300 ° C. or higher and is separated in a settler into a mat (kawa, sulfide melt) containing 50 to 68% of copper and a slag (kalami) floating above the mat. A slug hole and a mat hole are formed on the side surface of the setler (not shown). On the other hand, the exhaust gas contains about 10% SO ₂ at a high temperature of about 1300 ° C., and is passed from the uptake 3 to the waste heat boiler 6 of the incidental equipment. After recovering heat in the boiler, the cooled exhaust gas is sent to a sulfuric acid plant after collecting dust with an electric dust collector, and produces sulfuric acid. According to the present invention, as a method of recycling valuable metals from scraps, scraps containing valuable metals are charged from a ceiling 4 of a shaft 1 into a flash smelting furnace for smelting copper ore. It is characterized in that the metal is collected in a mat (sulfide melt) retained in the furnace. A loading port for scraps may be separately provided on the ceiling, but the scraps are crushed in advance, mixed with copper ore concentrate and a solvent, and loaded into the furnace from the flash smelter concentrate burner 5. Preferably. In particular, among the scraps, those having a flame retardancy and a low melting point are 40 mm or less, preferably 1 mm or less.
Crushed to 0 mm or less, more preferably 2 mm or less,
Charged into the furnace together with the ore from the flash smelter concentrate burner.
Scraps may be pulverized by using an appropriate pulverizing mill. However, it is convenient to perform the pulverization simultaneously with the pulverization of the solvent (silica) for the flash smelting furnace, and the cost is hardly increased. As a result, the scrap burns and melts together with the ore at a high temperature of 1300 ° C. or more while falling down the shaft, and the valuable metal is quickly absorbed by the mat after reaching the molten metal. Incombustible components such as SiO ₂ in the scrap are also quickly absorbed by the slag. At this time, some valuable metals
It is considered to be oxide when the shaft falls, but it is reduced (sulfided) by iron sulfide supplied from the molten ore particles,
Absorbed by the mat (sulfide phase). Further, in this method, since the scrap is evenly distributed over a wide range of the molten metal just below the shaft, even if there is some delay in the combustion and melting during the fall of the shaft, the scrap is located in one place in the settler portion. Dissolving after the molten metal has been reached and unnecessary slag are easier than in the case of intensive charging. Further, since organic matter generated by thermal decomposition from synthetic resins in the scrap is completely decomposed and oxidized while passing through the flash furnace, it does not burn in the boiler. When a halogen element such as chlorine or fluorine is contained in the organic insulator, it can be removed in a pretreatment stage of the sulfuric acid production process. EXAMPLE An operation was carried out in which scrap mainly composed of electric component waste was pulverized and charged into a flash smelting furnace. (I) Scrap before crushing The size of scrap before crushing is mainly about 80 mm at the maximum and about 20 mm at the minimum, and many substrates and copper wire cords are included. Table 1 below shows the average component analysis value of the whole processed scrap. Since an inorganic insulator is also included, the content of SiO ₂ is high. [Table 1] (Ii) Pulverization Method and Pulverization Particle Size Pulverization was carried out together with (simultaneously with) silica using a ball mill for pulverizing silica commonly used as a solvent (flux) for a flash furnace. Table 2 shows the scrap particle size distribution after pulverization. [Table 2] (Iii) The scrap charged into the flash smelting furnace is mixed with silica during the pulverization. The mixed scrap is further mixed with copper ore, and then dried. It was charged into the furnace from the installed concentrate burner. The ore and scrap loading rates were as follows: ore loading: 65 Ton / Hr scrap loading: 0.55 Ton / Hr (iv) Recovery of valuable resources The charged valuable metal is absorbed by the mat and sent to the converter in the next process, but the waste contained in and discharged from the slag becomes a loss. FIG. 2 shows the copper content in the flash slag during the test. It can be seen that the copper content in the slag during the test period was not different from that in the normal operation, and that the copper in the scrap was absorbed by the mat without loss. Gold and silver are also collected on the mat similarly to copper. Figure 3 shows the gold on the mat during the test.
The transition of the silver content is shown. As can be seen from FIG. 3, the content of gold and silver in the mat increased with the start of the test operation, indicating that gold and silver were collected on the mat. Next, in order to examine the recovery rate of valuable metals to the mat, the loss rate of silver to slag is evaluated. Most of the silver loss to the slag is included in the mat particles suspended in the molten slag, so it is also evaluated taking into account that the silver content in the mat has increased due to the charging of scrap. There is a need. Therefore, it is appropriate to evaluate by the distribution coefficient between slag and mat (= content in slag / content in mat). Figure 4 shows the transition of the silver distribution coefficient during the test period.
Shown in As can be seen from FIG. 4, the distribution coefficients of silver are not different from those in normal operation. Thereby, it can be determined that the recovery rate of silver in the scrap on the mat was equal to the recovery rate (99% or more) from the ore during the normal operation. (V) Coloring of Product Sulfuric Acid and Influence on Boiler Temperature Further, the coloring of product sulfuric acid and the degree of increase in boiler temperature were examined. The product sulfuric acid produced from the furnace exhaust gas was not colored. It is considered that the organic insulator contained in the scrap was completely decomposed and burned. The boiler temperature did not rise as a result of the scrap flash furnace charging test operation. Pyrolysis and combustion of scrap were completed in the flash furnace shaft and settler section. According to the present invention, since scrap processing is combined with copper smelting in a copper smelting flash furnace, valuable metals can be recovered at low cost even from scraps having a low content of valuable metals. be able to. In the case of flame-retardant scraps, pulverization must be performed in advance. However, since the pulverization may be performed simultaneously with the pulverization of the solvent (silica) for the flash furnace, the cost hardly increases. Further, since the organic insulator can be reliably thermally decomposed and burned in the smelting furnace, the quality of the product sulfuric acid does not deteriorate even if the smelting furnace exhaust gas is treated in the sulfuric acid production process. Further, since halogen elements such as chlorine and fluorine contained in the organic insulator can be removed in the preliminary treatment stage of the sulfuric acid production process, it is not necessary to newly provide a gas treatment facility for preventing pollution. Refurbishment of the copper smelting flash furnace itself and changes in operating conditions are virtually unnecessary. As described above, the conventional method does not meet the treatment cost, and can be applied to industrial waste that is difficult to dispose of finally, so that it is useful not only for resource saving but also for environmental protection.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a flash smelting furnace for copper ore smelting and a waste heat boiler. FIG. 2 is a graph showing a copper content in a flash slag during a test. FIG. 3 is a graph showing changes in the gold and silver contents of the mat during the test period. FIG. 4 is a graph showing a change in a distribution coefficient of silver during a test period. [Description of Signs] 1 Shaft 2 Settler 3 Uptake 4 Ceiling 5 Concentrate burner 6 Waste heat boiler

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-13543 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22B 1/00-61/00

Claims (1)

(57) [Claims 1 organic insulator, inorganic insulator only containing and copper,
At least selected from the group of gold, silver, platinum and palladium
Also, scraps containing a kind of valuable metal are crushed together with the solvent for flash smelting furnace, mixed with the charge for copper ore smelting, and sent to the copper smelting flash smelting furnace from the flash smelting furnace. Charge
Is said chromatic <br/> valent metal recycling method from scrap such that and recovering the mat staying in the furnace of the valuable metal by operating a flash smelting furnace, an organic insulation in scrap
The recycling method of the valuable metal, wherein the organic matter volatilized from the rim is completely decomposed and burned to prevent coloring of the product sulfuric acid.