JPH0978151A - Recycle method of valuable metals from scraps - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish an industrial recycle method being able to be substituted for a converter treatment of scraps. SOLUTION: Scraps containing valuable metals is charged from a ceiling part 4 of a shaft 1 to an autogeneous smelting furnace of smelting copper ore and the valuable metals are recovered into mattes staying in the furnace. It is the most practical way that scraps are in advance pulverized and are mixed with copper ores and then are charged into the furnace from a concentrate burner 5 of autogeneous smelting furnace. Organic insulating materials included in the scraps are completely decomposed and burnt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention processes scraps containing valuable metals such as copper, gold, silver and platinum in a copper ore smelting flash furnace to recycle valuable metals from scraps. It is about the method.

[0002]

2. Description of the Related Art In recent years, scraps (electric wire scraps, lead frames, IC chips, resin-containing board scraps, ultra-small coils, switches, etc.) are generated in the electronic parts manufacturing industry and products and industries using those electronic parts. The amount tends to increase significantly. These scraps include copper used as electrical conductors and valuable metals such as gold, silver, platinum, and palladium used for contacts and plated coatings. The recovery of these valuable metals is a recycling of resources. It is also important from the viewpoint of resource saving.

The above-mentioned scraps, of course, have been generated even before, and there are various recycling methods. If the amount of copper is large and the content of other valuable metals (noble metals) is low, scraps can be simply put into molten copper to recover copper.

There is also a method of incinerating scrap containing a noble metal (burning an organic insulator) and concentrating valuable metal in the ash after burning. However, in this method, a part of the valuable metal is oxidized, and therefore, in order to recover the valuable metal, it is necessary to refine the metal from the incinerated ash as a raw material.

On the other hand, as a method for recovering valuable metal in scrap without oxidizing it, for example, Japanese Patent Application Laid-Open No. 49-531.
23. This is a method in which the insulated wire scrap is immersed in molten lead to thermally decompose the organic insulating material in the state where the air is cut off and to recover it as a fuel, and further to recover the copper content without oxidizing it. As a similar method, JP-A-53-16302 discloses pressurizing and heating scrap in an airtight container to insulate the scrap (resin such as polyvinyl chloride, rubber, polyurethane and Teflon).
It 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 the process is troublesome.

By the way, unlike the above-described method of treating only scrap (or pretreatment), a method of directly treating scraps in a copper smelting step is also practiced. A commonly practiced method is to load the above 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 non-natural scrap can be easily slagged and melted by utilizing the strong stirring effect of the molten metal in the converter and the reaction heat in the furnace. Valuable metals such as copper, gold and silver in scrap are recovered in a mat, that is, a river (or blister) in a converter with a high yield of over 98%. In the above method of charging with an overhead crane, in order to load scrap into the furnace, it is necessary to suspend the air blowing of the converter and tilt the converter. There is a problem such as leakage of gas from the furnace. As a method of solving these problems, there is a method of charging scraps from the converter furnace top using a chute. In addition, Japanese Unexamined Patent Publication
As shown in -287655, a transfer device for transferring a defective anode, a transfer device, and a transfer input device are installed on the top of the converter furnace.
There is also a method in which scraps are placed on the defective anode and charged into the converter together when the defective anode is charged into the converter through the side door using this apparatus.

[0007]

As described above, the treatment in the converter has the advantages that it requires almost no fuel and pretreatment and can be performed simultaneously with the smelting of copper.
However, among the methods of processing in the above-mentioned converter, when scrap is introduced from the furnace top through the chute or loaded on a boat, it has an adverse effect on the furnace body. That is,
Since the organic insulator in the scraps generally undergoes thermal decomposition at 300 ° C. or lower, hydrogen gas and carbon fumes are generated by thermal decomposition immediately after being introduced into the furnace. These thermal decomposition products do not burn in a furnace with a low oxygen concentration, but burn with being mixed with free air near the converter exhaust gas hood,
The converter exhaust gas hood is heated to a high temperature to promote wear of the exhaust gas hood.

Further, a part of the organic matter volatilized from the organic insulator (synthetic resin) in the scrap is not completely decomposed and burned, and is absorbed and colored by the sulfuric acid product manufactured from the converter exhaust gas as a raw material. I have a problem.

An object of the present invention is to establish a new industrial recycling method which replaces converter processing of scraps.

[0010]

[Means for Solving the Problems] Generally speaking, the method of directly treating in the copper smelting process requires almost no pretreatment, so the treatment cost is low, and even if the content rate of valuable metals in scrap is low, the recovery rate and Since there is no problem in large-scale processing, it is desirable as a recycling method. Therefore, in order to solve the problems such as exhaust gas hood wear and coloring of the product sulfuric acid due to the converter treatment, the present inventor has conceived to treat scraps in a copper ore smelting flash furnace. . Unlike a converter, in a closed-type flash smelting furnace, organic substances that have 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, even in the method of processing in a flash furnace,
A new problem arises when processing scrap containing a small amount of valuable metal and containing a large amount of synthetic resin and inorganic insulator (glass fiber, etc.). That is, in the flash furnace, the oxygen concentration directly above the melt is extremely low, so even if it is simply charged from the settler section of the flash furnace, the oxygen concentration in the atmosphere is low, so it will not completely burn and the melt surface (on top of the slag) There is a problem that it will surface. Further, since the stirring effect of the molten metal in the flash smelting furnace is smaller than that in the converter, the pyrolysis residue and the inorganic insulator in the scrap do not form slag. Therefore, the transfer (sedimentation) of valuable metal in scrap to the mat is prevented. Also, when a large amount is input from the settler section, the organic substances generated from synthetic resins are introduced to the boiler together with the exhaust gas of the flash furnace, burned in the boiler, and the temperature inside the boiler is raised, so that the boiler of the flash furnace dust is heated. Induces fusion to the water tube.

In order to realize the treatment of scraps in the flash smelting furnace, it is necessary to overcome these problems. As a result of repeated research, the inventors of the present invention can solve these problems and put the scraps into practical use by throwing them into the shaft ceiling of the flash furnace. Found. Thus, the present invention is characterized in that scraps containing valuable metals are charged into a copper ore smelting flash smelting furnace from the shaft ceiling, and valuable metals are recovered to a mat that remains in the furnace. Provide a method of recycling valuable metals from. Most practically, the scraps are crushed in advance, mixed with the charge for smelting copper ore and charged into the furnace from the flash smelting furnace burner.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1, a flash smelting furnace for smelting copper ore comprises a shaft 1, a setler 2 and an uptake 3. The book concentrate burner 5 is equipped. A copper ore smelting charge is generally blown from a concentrate burner together with a fine powder concentrate together with a solvent (flux) together with oxygen-enriched air or oxygen or high-temperature hot air to cause an instantaneous oxidation reaction.
Since the amount of heat is insufficient only with the heat of oxidation reaction, heavy oil is usually assisted from the concentrate burner. While falling through the shaft,
The concentrate melts at a high temperature of 1300 ° C. or higher, and is separated by a setler into a mat (kawa, sulfide melt) containing 50 to 68% of copper and a slag (karami) floating above it. A slag 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 auxiliary equipment. After recovering heat in the boiler, the cooled exhaust gas collects dust with an electric dust collector and is then sent to a sulfuric acid factory to produce sulfuric acid.

According to the present invention, as a method of recycling valuable metals from scraps, scraps containing valuable metals are charged from the ceiling part 4 of the shaft 1 into the self-melting furnace for smelting copper ore, and valuable metals are charged. The feature is that metal is collected in a mat (sulfide melt) that stays in the furnace. Although a charging port for scraps may be separately provided in the ceiling, scraps are crushed in advance and mixed with copper ore concentrate and a solvent to be loaded into the furnace from the flash smelting furnace burner 5. It is preferable to enter. In particular, for scraps that are flame-retardant and flame-melting, 40 mm or less, preferably 1
Crushed to 0 mm or less, more preferably 2 mm or less,
It is charged into the furnace with ore from the flash furnace concentrate burner.
The scraps may be crushed by using an appropriate crushing mill, but it is convenient to crush the solvent (silica) for the flash smelting furnace at the same time, and the cost hardly increases.

As a result, the scrap burns and melts with the ore at a high temperature of 1300 ° C. or higher while the shaft is falling, and the valuable metal is quickly absorbed by the mat after reaching the molten metal. In addition, incombustibles such as SiO ₂ in scrap are quickly absorbed by the slag. At this time, some valuable metals are
It is thought that it becomes an oxide while the shaft falls, but it is reduced (sulfided) by iron sulfide supplied from molten ore particles,
Absorbed by matte (sulfide phase).

Further, in this method, since the scrap is evenly dispersed in a wide range of the molten metal just below the shaft, even if there is scrap with a slight delay in combustion and melting during the fall of the shaft, it will be in one place of the settler section. It is easier to melt after reaching the molten metal and to slag unnecessary parts, as compared to the case of intensive injection. Further, since the organic substances generated by thermal decomposition from the synthetic resins in the scrap are completely decomposed and oxidized while passing through the flash furnace, they are not burned in the boiler. When a halogen element such as chlorine or fluorine is contained in the organic insulator, it can be removed in the pretreatment step of the sulfuric acid manufacturing process.

[0017]

[Example] An operation was carried out in which scrap mainly consisting of electric component scrap was crushed and charged into a flash furnace. (I) Scrap before crushing The particle size of the scrap before crushing is mainly about 80 mm at maximum and about 20 mm at minimum, and many substrates and copper wire cords were also included. The average component analysis values for the entire processed scrap are shown in Table 1 below. Since it also contains an inorganic insulator, it has a high SiO ₂ content.

[0018]

[Table 1]

(Ii) Grinding Method and Grinding Particle Size Grinding was carried out together with silica using a ball mill for grinding silica stone which is usually used as a solvent (flux) for a flash furnace. Table 2 shows the particle size distribution of scrap after crushing.

[0020]

[Table 2]

(Iii) Charging into the flash furnace The scrap is mixed with silica during crushing. This scrap is further mixed with copper ore and then dried, and then it is put on the ceiling of the flash furnace shaft. The furnace was charged from the installed concentrate burner. The ore and scrap charging rates were as follows: Ore charging: 65 Ton / Hr Scrap charging: 0.55 Ton / Hr

(Iv) Recovery of valuables The valuable metals charged in the flash furnace are absorbed by the mat and sent to the converter in the next step, but the amount contained in the slag and discharged is lost. Becomes FIG. 2 shows the copper content in the flash slag during the test period. It can be seen that the copper content in the slag during the test period did not differ from normal operation, and the copper in the scrap was absorbed by the mat without loss.

Gold and silver are also collected in the mat, like copper. Figure 3 shows the matte gold during the test period,
The change of silver content is shown. As can be seen from FIG. 3, the gold and silver contents in the mat increased with the start of the test operation, indicating that gold and silver had been collected in the mat.

Next, in order to investigate the recovery rate of valuable metals to the mat, the loss rate of silver to the slag is evaluated. Most of the loss of silver to the slag is contained in the suspended matte particles in the molten slag, so it is evaluated in consideration of the increase in the silver content in the matte due to scrap charging. There is a need. Therefore, it is appropriate to evaluate by the distribution coefficient between slag / mat (= content in slag / content in mat). Figure 4 shows changes in the distribution coefficient of silver during the test period.
Shown in As can be seen from Fig. 4, the distribution coefficient of silver is not different from that during normal operation. From this, it can be judged that the recovery rate of silver in the scrap into the mat was equal to the recovery rate from the ore during normal operation (99% or more).

(V) Coloring of product sulfuric acid and influence on boiler temperature Furthermore, as a result of examining the degree of coloring of product sulfuric acid and the rise in boiler temperature, it was found that the self-melting of scrap due to the operation of the flash-charging furnace charging test operation. Product sulfuric acid produced from furnace exhaust gas as a raw material was not colored. It is considered that the organic insulator contained in the scrap had completely decomposed and burned. The boiler temperature did not rise due to the operation of the scrap flash furnace charging test operation. Thermal decomposition and combustion of scrap had been completed in the flash furnace shaft and settler section.

[0026]

According to the present invention, since scrap processing is combined with copper smelting in a copper smelting flash smelting furnace, valuable metals can be recovered at low cost even from scraps having a low valuable metal content. . In the case of flame-retardant scraps, it must be crushed in advance, but since this crushing can be performed at the same time as the crushing of the solvent (silica) for the flash furnace, there is almost no cost increase. Further, since the organic insulator can be reliably pyrolyzed 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 manufacturing process. Further, since halogen elements such as chlorine and fluorine contained in the organic insulator can be removed in the pretreatment stage of the sulfuric acid manufacturing process, it is not necessary to newly provide a gas treatment facility for pollution prevention. It is virtually unnecessary to repair the copper smelting flash furnace itself or change the operating conditions. As described above, the conventional method does not match the treatment cost and can be applied to industrial waste that is difficult to be finally disposed of. Therefore, it is useful not only for resource saving but also for environmental protection.

[Brief description of 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 the copper content in the flash slag during the test period.

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 changes in the distribution coefficient of silver during the test period.

[Explanation of symbols]

 1 Shaft 2 Setler 3 Uptake 4 Ceiling 5 Concentrate burner 6 Waste heat boiler

Claims (2)

[Claims] 1. A scrap which is characterized in that scraps containing valuable metals are loaded into a flash ore smelting furnace for copper ore smelting from the shaft ceiling, and valuable metals are recovered to a mat that remains in the furnace. Method for recycling valuable metals. 2. The scraps are crushed in advance, and the scraps are mixed with a copper ore smelting charge and charged into the furnace from a flash smelting furnace concentrate burner. A method of recycling valuable metals from scraps.