JP2010077499A - Method for treating substance to be treated containing platinum group element, rhenium and arsenic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for concentrating a platinum group element, rhenium and arsenic in a substance to be treated which contains the platinum group element, rhenium and arsenic respectively, and separating each element from the others. <P>SOLUTION: This separating method includes: leaching the substance to be treated such as dust, which has been collected from an exhaust gas produced when various catalysts or the like, for instance, have been melted and smelted in an electric furnace and an oxidation furnace, and contains the platinum group element, rhenium and arsenic, with an alkaline solution such as an NaOH solution; subsequently separating a solid in which the platinum group element is concentrated, from a solution in which the rhenium and arsenic are leached; then adding a chloride such as potassium chloride into the solution; and subsequently separating the solid in which the rhenium is concentrated, from a solution in which the arsenic is concentrated. A liquid temperature in the step of adding the chloride and the subsequent step of solid-liquid separation is preferably 20-40°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention melts and smelts, for example, used petrochemical catalysts, used automobile exhaust gas purification catalysts, used electronic substrates and lead frames, etc., from materials to be treated containing platinum group elements, rhenium and arsenic. In addition, the present invention relates to a method for efficiently concentrating and separating the above elements from dust or the like as a by-product.

  Conventionally, as a method for recovering each contained element such as platinum group elements from used automobile exhaust gas purification catalyst (ceramic carrier catalyst and metal carrier catalyst of exhaust gas converter: these are called "automobile catalyst") Wet methods such as a solution in which an oxidizing agent is added to an acid such as water, a method of extracting a platinum group element or the like with an aqueous alkali solution or an aqueous ammonia solution, a method of dissolving a carrier using sulfuric acid or the like and separating it from an undissolved platinum group element or the like There is a processing method.

Further, JP-A-4-317423, JP-A-2000-248322, and JP-A-2005-5201 by the applicants disclose that a platinum group element-containing substance such as an automobile catalyst is contained in a copper source in an electric furnace. The platinum group element is transferred into the molten metal (molten copper metal) by melting with the material (copper oxide and / or metallic copper), and the molten metal containing the platinum group element thus obtained is further oxidized. Thus, there is a description of a dry processing method in which a molten oxide and a molten metal in which a platinum group element is further concentrated are separated into layers.
JP 2006-130387 A JP-A-6-17160 JP-A-4-317423 JP 2000-248322 A JP 200554201 A

However, for the treatment of a material to be treated containing platinum group elements, rhenium and arsenic, wet treatment methods such as the above-mentioned Patent Documents 1 and 2 (that is, leaching out the platinum group element or catalyst carrier using acid or alkali). Method), there are problems in terms of recovery rate and cost, such as poor extraction rate of platinum group elements, and the use of a large amount of acid to dissolve the carrier. It wasn't the way.
On the other hand, the dry processing method (that is, the melting processing method) for transferring the platinum group element into the molten metal such as Patent Documents 3 to 5 can recover the platinum group element at a high yield and at a low cost. Although it is an excellent method that has advantages not found in wet processing methods as an efficient method for recovering valuable metals, rhenium and arsenic are contained in the material to be treated along with platinum group elements In some cases, a method of concentrating and separating these rhenium and arsenic has not been solved.
The present invention melts and smelts used petrochemical catalysts, used automobile exhaust gas purification catalysts, used electronic boards and lead frames, etc., from the materials to be treated containing platinum group elements, rhenium and arsenic. It is an object of the present invention to provide a method for concentrating and separating each of the above elements from dust produced as a by-product.

The present invention made to solve the above-mentioned problems is not a conventional method of leaching a platinum group element nor a method of leaching a catalyst carrier, and is a treatment method based on a new viewpoint. In addition, after leaching a material to be treated containing platinum group elements, rhenium and arsenic with an alkaline solution, followed by solid-liquid separation to obtain a solid enriched with platinum group elements and a solution in which rhenium and arsenic were leached, A method for treating a substance containing platinum group elements, rhenium and arsenic, which is obtained by adding a chloride to a solution and then solid-liquid separation to obtain a solid enriched in rhenium and a solution enriched in arsenic. The material to be treated containing platinum group elements, rhenium and arsenic recovered as dust from the exhaust gas from the smelting furnace is leached with an alkaline solution, and then solid-liquid separation is performed to leach out the rhenium and arsenic. A solution containing platinum group elements, rhenium and arsenic, which is obtained by adding chloride to the solution and then solid-liquid separation to obtain a solid enriched in rhenium and a solution enriched in arsenic Third, a material to be treated containing a platinum group element, rhenium and arsenic, and a copper source material mainly comprising at least one selected from the group consisting of metallic copper and copper oxide, a flux component and After charging into an electric furnace together with a reducing agent and melting and separating into a primary slag layer mainly composed of oxide and a primary metal layer mainly composed of copper metal, the primary metal is charged into an oxidation furnace and oxidized to be mainly composed of oxide. The secondary slag layer and the secondary metal layer mainly composed of metallic copper enriched with platinum group elements are separated into layers, and dust is recovered from the gas introduced from the space inside the oxidation furnace, and then the dust is leached with an alkaline solution. Then solid-liquid separation and platinum group Platinum obtained after obtaining a solid enriched with elemental and a solution leached with rhenium and arsenic, and then adding chloride to the solution, followed by solid-liquid separation to obtain a solid enriched with rhenium and a solution enriched with arsenic This is a method for treating a substance containing a group element, rhenium and arsenic.
In the present invention, “rhenium” means a rhenium element and includes a case of rhenium alone, a rhenium alloy, a rhenium compound, etc., and “arsenic” means an arsenic element, It is a concept that includes cases of arsenic alone, arsenic compounds, and the like.

In these present inventions, it is preferable that at least a part of the collected dust is repeatedly charged into at least one of the electric furnace and the oxidation furnace, thereby removing rhenium and arsenic in the dust. The concentration can be further increased, and rhenium and arsenic can be concentrated to a higher concentration and separated.
In these present inventions, it is preferable that at least a part of the secondary slag is cooled with water in a molten state to obtain a granule containing copper oxide, and the granule is used as the copper source material, or It is preferable that at least a part of the secondary slag is reduced in a molten state to obtain a metallic copper-containing material and used as the copper source material. According to these aspects, at least a part of the copper raw material can be repeatedly used, the amount of waste slag can be reduced, and the cost can be reduced.
Furthermore, it is preferable to carry out a series of steps of adding chloride to the solution in which rhenium and arsenic are leached and then separating the solid and liquid at a liquid temperature of 20 to 40 ° C.

According to the present invention, for example, a used petrochemical catalyst, a used automobile exhaust gas purification catalyst, a used electronic substrate, a lead frame, etc. are melted from a material to be treated containing platinum group elements, rhenium and arsenic. Each of the above elements can be efficiently concentrated and separated from dust or the like by-produced by smelting.
Further, a series of addition and solid-liquid separation steps of solid-liquid separation after adding chloride to the solution leached with rhenium and arsenic is performed while maintaining the liquid temperature at 20 to 40 ° C. Thus, the ratio of rhenium precipitation can be increased, and the ratio of the arsenic in the solution maintained without being precipitated can be increased, so that rhenium and arsenic can be separated more efficiently.

In the present invention, rhenium is separated and recovered as a rhenium chloride precipitate by adding chloride to a solution in which rhenium and arsenic are obtained by solid-liquid separation of the slurry after alkali leaching, Rhenium can be collected from the precipitate by a known method, while the arsenic solution can be dearsenated by a known wastewater treatment process.
Sodium chloride, potassium chloride, ammonium chloride and the like can be used as the chloride for addition described above, and is not particularly limited.
Here, in a series of addition and solid-liquid separation processes in which chloride is added to the solution in which rhenium and arsenic are leached and then solid-liquid separation is performed, rhenium decreases in precipitation rate as the liquid temperature increases, In particular, when it exceeds 40 ° C., it rapidly decreases and the precipitation rate of rhenium is less than 60% even when an equivalent amount of chloride is added. On the other hand, in this series of addition and solid-liquid separation steps, arsenic begins to precipitate as the liquid temperature decreases, and the amount of arsenic precipitation increases sharply below 20 ° C., for example, the arsenic precipitation rate at 10 ° C. Reaches 50%. Therefore, in a series of addition and solid-liquid separation processes in which chloride is added to a solution in which rhenium and arsenic are leached and then solid-liquid separation is performed, the liquid temperature is maintained at 20 to 40 ° C., thereby performing rhenium. And arsenic can be separated more efficiently.
In the present invention, the material to be treated containing platinum group elements, rhenium and arsenic to be treated is not particularly limited, but dust is recovered using a waste catalyst or the like as a starting material, and this is treated. Examples of cases are described below.

  That is, the raw materials for melting and smelting containing platinum group elements, rhenium and arsenic, which are the targets of the above-described electric furnace and oxidation furnace (referred to as melting and smelting), are, for example, used petrochemical waste catalysts, This includes not only used automobile exhaust gas purification catalysts, used electronic boards, lead frames, but also lot-out products and scraps obtained from these manufacturing processes. Such a raw material containing a platinum group element and rhenium and arsenic is usually in a state where a trace amount of the platinum group element and rhenium and arsenic are supported on a carrier such as a metal oxide or ceramics.

In melt smelting, the raw material containing these platinum group elements, rhenium and arsenic (these elements may be collectively referred to as platinum group elements) is first selected from the group consisting of metallic copper and copper oxide. At least one of the main copper source material, flux, and a reducing agent such as carbonaceous material are charged into an electric furnace and melted, and a molten primary metal mainly composed of copper metal is formed below the formed primary oxide-based molten primary slag layer. In this case, the platinum group elements and the like are concentrated in the molten primary metal layer that has settled down. At this time, the pressure in the electric furnace is changed from atmospheric pressure from the melting of the charge to the discharge of the melt. It is preferable to use a granular material having a particle size of 0.1 mm or more and 10 mm or less as a copper source material to be maintained at a low pressure and charged into the electric furnace.
Hereinafter, these matters will be described.

  FIG. 1 shows an example of an electric furnace used in melting and smelting. In FIG. 1, reference numeral 1 denotes a closed electric furnace. The closed electric furnace 1 includes a furnace body 3 having a furnace space 2 that is substantially blocked from outside air, a charge input port 4 and an exhaust port 5 provided in an upper body portion of the furnace body 3, At least two fluid discharge ports 6 and 7 having different height levels provided in the lower half of the furnace body 3, a charge input chute 8 connected to the charge input port 4, and the exhaust port And an electrode 10a, 10b, 10c for energizing and heating the charge charged in the furnace.

  The furnace body 3 shown in the figure is a furnace having a circular inner wall lined with a refractory, and a charge charging chute 8 is arranged at the substantially center of the ceiling surface. The three electrodes 10a, 10b, and 10c are arranged vertically from the ceiling surface at equal intervals from each other on the concentric circle. In other words, the positions of the vertical electrodes 10a, 10b, and 10c are at the vertices of the equilateral triangle, and the charge throwing chute 8 exists at the approximate center of the equilateral triangle.

  The closed electric furnace 1 configured in this way is mainly composed of at least one selected from the group consisting of a granular material to be processed (raw material) 11 containing platinum group elements, rhenium and arsenic, and metallic copper and copper oxide. The copper source material 12, the solid reducing material (powdered coke) 13, and the powdery flux 14 are mixed and charged. That is, these charging raw materials are weighed and cut out from the respective hoppers, and are fed into the charging charge chute 8 of the electric furnace 1 while being mixed and conveyed by the screw conveyor 15. The charging material charging chute 8 is provided with two upper and lower shutters 16 and 17 so that airtightness is maintained when the material is charged into the furnace. First, the upper shutter 16 is opened, the lower shutter 17 is closed, and one batch of charge is put into the chute 8, then the upper shutter 16 is closed, the lower shutter 17 is opened and stored in the chute 8. The batch that is being processed is put into the furnace. When the batch is charged into the furnace, the upper and lower shutters 16 and 17 are closed to prepare for the next charging operation. In the facility shown in the figure, the branch member 18 is attached to the lower end of the chute 8 (below the charge inlet 4), so that the charge falling into the furnace from the chute 8 is three electrodes 10a, 10b, 10c. Are landed in the vicinity of each side of the triangle connecting the two, more preferably near the midpoint position of each of the three sides. As a result, a new charge is deposited at the shortest distance connecting the electrodes 10a, 10b, and 10c, thereby increasing the melting efficiency.

  At the initial stage of operation of the furnace in which a new charge is charged, at least two fluid discharge ports 6 and 7 having different height levels provided in the lower body portion of the furnace body 3 are closed. The substance charged in the furnace starts to melt by energizing each electrode 10a, 10b, 10c, but during that time, the exhaust gas generated in the furnace by driving the exhaust device 9 passes from the exhaust port 5 to the dust removing device 19 Guided and exhausted after the exhaust gas treatment. By the continuous operation of the exhaust device 9, the furnace space 2 that is substantially blocked from the outside air is maintained at a pressure lower than the atmospheric pressure.

  The dust removing device 19 may be either a dry system that does not use a cleaning liquid or a wet system that cleans exhaust gas using a cleaning liquid. In the case of the dry method, lightning type flues (Zig-Zag Blue), dust collection chambers (Dust Chamber), cyclones, bag houses, cotrels, etc. can be arbitrarily selected. In addition, the dust collected by the dust removing device 19 can be sintered or made as needed and repeatedly charged into the closed electric furnace 1 together with new charged raw materials.

  When the charge begins to melt in the electric furnace, the metal copper in the raw material and the copper source material melts, and the copper oxide is reduced to metal copper by a reducing material (powder coke) to form molten primary metal copper. . Since the metal melt has a higher specific gravity than the oxide melt (slag), the metal melt descends in the slag and settles below the furnace to form a molten metal pool 20. An oxide melt, that is, a primary slag layer 21 is formed on the molten metal 20.

  In the process in which the molten metal copper produced by reduction of metallic copper and copper oxide descends in the slag, platinum group elements and the like existing in the slag are taken into the molten metal copper, that is, dissolved. As a result, the molten metal 20 is collected in a state in which the platinum group elements and the like are dissolved in the molten metal 20, and the molten metal 20 having a high concentration of the platinum group elements and the like is obtained. On the other hand, the concentration of the platinum group element or the like in the slag 21 is lowered by the amount of the platinum group element or the like dissolved in the molten metal 20. Therefore, the primary slag 21 having a lower concentration of platinum group elements or the like is separated from the higher fluid discharge port 6, and the primary metal melt 20 having a higher platinum group element concentration or the like is separated from the lower fluid discharge port 7. When flowing out of the furnace, it is possible to collect a molten metal having a high concentration such as platinum group elements (metal in which platinum group elements or the like are dissolved in metallic copper).

  Since this closed electric furnace 1 is in a reducing atmosphere, most of the rhenium and arsenic charged together with the platinum group element is transferred to the molten metal 20 together with the platinum group element. That is, any element of platinum group elements, rhenium, and arsenic charged in the closed electric furnace 1 in a reducing atmosphere is concentrated in the molten metal 20.

  In melt smelting, it is preferable to use a granular material having a particle size of 0.1 mm or more and 10 mm or less as a copper source material charged into an electric furnace. When a granular material having a particle size of 0.1 mm or more and 10 mm or less is used as the copper source material, the platinum group element or the like in the raw material may easily move into the molten metal at the stage where the raw material and the copper source material are heated and melted. all right. In particular, it is desirable that the copper source material has a particle size of 0.1 mm or more and 10 mm or less in an amount of 50% by mass or more. If the condition is satisfied, the other materials may be a lump of 10 mm or more. In some cases, a powder of less than 0.1 mm may be mixed.

  Also for the raw material containing a platinum group element or the like, at least 50% by mass or more of the raw material containing a platinum group element or the like is preferably a granule having a particle size of 10 mm or less. Both the raw material and the copper source material are granular bodies having appropriate particle sizes, and when this is mixed with the carbonaceous reductant and the flux in the furnace, the copper metal in the copper source material is easily melted. In addition, the copper oxide is easily melted and reduced, and the opportunity for the generated molten metal copper to come into contact with the platinum group elements in the raw materials present in the vicinity increases, so that the platinum group elements and the like become molten metal copper. Many will be captured.

In order to promote the meltdown of the raw material and the copper source material and improve the fluidity of the slag to be produced, it is desirable to add the flux to the charging raw material simultaneously. As the flux, a mixture of silica, calcium oxide, calcium carbonate and the like in an appropriate ratio is preferable. The mixing ratio of the flux components varies depending on the composition of the raw material, but as the composition of the slag after heating and melting, Al ₂ O ₃ : 20 to 40% by mass, SiO ₂ : 25 to 35% by mass, CaO: 20 to 30% by mass, FeO : It is preferable to mix | blend a flux component with a charging raw material so that it may become 1-30 mass%.

  Coke is preferably blended as the reducing agent, but other than the coke, a base metal containing a valuable metal having a reducing action, a resin material as a carbon source, activated carbon, SiC, or the like can also be used. According to the present invention, valuable metals (noble metals and platinum group elements) contained in these reducing agents can also be recovered simultaneously.

  In melt smelting, a sealed electric furnace is charged with a mixture of raw materials, copper source material, flux and reducing agent, and the furnace internal pressure is maintained at a pressure slightly lower than atmospheric pressure. Preferably, heat melting is performed at a temperature of 1300 ° C. to 1500 ° C., the oxide in the charging material is melted, and the copper oxide in the charging material is reduced to copper. If the heating and melting temperature is lower than 1100 ° C, the molten state of the slag is not perfect and the viscosity increases, and the recovery rate of platinum group elements and the like may be reduced. This may cause damage, burnout, wear, etc. By maintaining the inside of the furnace under reduced pressure, a reducing atmosphere is maintained, the reduction of copper oxide to copper proceeds well, and the absorption efficiency of the platinum group elements and the like into the molten metal is also increased.

  In the melt-down state of the charge, most of the raw material is a glassy molten oxide layer (slag layer). Metallic copper melts, and copper oxide is reduced by a reducing agent to become molten metal copper. The slag layer and the metal layer are naturally separated into two layers due to the difference in specific gravity, and a primary slag layer is formed in the upper layer and a primary metal layer is formed in the lower layer. At this time, the platinum group element, rhenium, and arsenic in the raw material all move to the lower molten primary metal layer and are absorbed. As described above, the particle size of the copper source material reduces the settling time and reduces the molten metal. It greatly affects the improvement of the yield of platinum group elements and the like absorbed by the layer, and when the particle size of the copper source material is set to 0.1 mm or more and 10 mm or less, a remarkable effect appears on these improvements.

  The reason is not necessarily clear, but can be considered as follows. Platinum group elements and the like in the raw material are dispersed in slag having an appropriate viscosity when the raw material melts down together with the flux. In addition, immediately after the metal copper and copper oxide added simultaneously are reduced, the molten metal is dispersed in the slag as a molten metal, while absorbing the platinum group elements dispersed and suspended in the slag having an appropriate viscosity, Go down in the slag layer. The inventors named the behavior of the molten metal (copper metal) absorbing platinum group elements and the like as the “copper showering effect”. When the particle diameter of the initially supplied copper source material is less than 0.1 mm, the molten metal copper dispersed in the slag is also fine, so that it often settles down to the lower metal layer. It takes time and the copper showering effect does not work sufficiently. On the other hand, if the diameter of the initially introduced copper source material exceeds 10 mm, the molten metal copper is applied to the lower metal layer before sufficiently absorbing platinum group elements and the like dispersed in the slag. In this case, the copper showering effect does not function sufficiently. Further, in order for the descending molten metal copper to absorb the platinum group elements and the like dispersed in the slag, a certain surface area and cross-sectional area are required. That is, the absorption efficiency increases as the surface area and cross-sectional area increase even if the mass of the copper source material to be input is the same. For these reasons, the copper showering effect works most efficiently when the particle size of the initially introduced copper source material is 0.1 mm or more and 10 mm or less. It is considered that the migration of platinum group elements and the like to the substrate is favorably performed.

  According to the experience of the present inventors, there is substantially no problem in the recovery of platinum group elements and the like if the copper source material has a particle size in this range of 50% by mass or more, preferably 80% by mass or more. When the particle size is less than 50% by mass, it is necessary to take a long time for standing, that is, settling time, in order to increase the recovery rate of platinum group elements and the like. Here, standing, that is, a set ring, means that the slag that has already melted after being charged into the electric furnace is energized as it is to maintain a predetermined temperature. In the meantime, the pressure in the closed electric furnace is preferably maintained under reduced pressure.

  After this standing, the upper molten primary slag is discharged out of the furnace. At this time, it is preferable that most of the molten primary slag in the upper layer is discharged outside the furnace while part of the molten primary slag remains in the furnace because the thermal stress on the refractory in the furnace due to the temperature change in the furnace can be reduced. The molten primary metal layer that has absorbed platinum group elements and the like existing in the lower layer in the furnace is also tapped outside the furnace. Similarly, when the molten primary metal layer that has absorbed platinum group elements and the like existing in the lower layer in the furnace is tapped outside the furnace while leaving a part of it in the furnace, the refractory in the furnace due to the temperature change in the furnace. It is preferable because the thermal stress on the object can be reduced. In the above preferred state, molten slag and other parts of the molten metal remain in the furnace, but in this state, the raw material for the next heat is charged into the furnace to reduce the thermal stress on the refractory in the furnace. The same operation can be repeated again.

  The molten primary metal, which is concentrated from the sealed electric furnace and separated from the molten primary slag, is concentrated in the molten primary metal (preferably in a molten state) and charged in an oxidation furnace. Is concentrated in the molten metal.

  In the oxidation furnace, this molten metal is oxidized in the molten state, and the molten oxide (mainly copper oxide) generated on the molten metal surface is discharged out of the furnace, leaving a molten metal in which the platinum group elements are further concentrated. That is, since the platinum group element hardly transfers to the molten oxide layer (secondary slag) formed on the molten metal surface and remains in the lower molten secondary metal layer, every time the generated molten oxide layer is discharged. In addition, the platinum group element concentration in the molten metal layer increases. The oxidation treatment in this oxidation furnace is preferably performed by introducing oxygen gas or oxygen-containing gas while maintaining the material temperature at a temperature of 1100 ° C. to 1700 ° C., preferably 1200 ° C. to 1500 ° C. If it is less than 1100 ° C., solidification of the molten oxide or molten metal occurs, and the progress of oxidation is inhibited. If the temperature exceeds 1700 ° C., the furnace body will be damaged, burned out, worn out, and the like.

  In this way, the content of the platinum group element in the molten secondary metal layer enriched with the platinum group element is increased to 10 to 75% by mass by repeating the oxidation process and the discharge process of the oxide layer in the oxidation furnace. be able to. After taking this out from the oxidation furnace, it is sent to the platinum group element recovery and purification step of the next step to separate and purify the copper metal and the platinum group element.

  On the other hand, the molten oxide layer (oxide mainly composed of copper oxide) discharged from the oxidation furnace can be reused as a copper source material charged in the electric furnace. At that time, by putting the oxide layer discharged in a molten state from the oxidation furnace into water, that is, by granulating, the granular material having a particle size of 0.1 mm or more and 10 mm or less is preferably 50% by mass or more. It can be set as the copper source material containing 80 mass% or more. The obtained granulated product can be dried and then further sized with a sieve or the like to obtain a copper source material having a particle size suitable for treatment in an electric furnace. Moreover, the oxide layer discharged | emitted in the molten state from this oxidation furnace can be reduce | restored, and it can also be made into copper source material as metallic copper. The molten oxide layer (oxide mainly composed of copper oxide) discharged from the oxidation furnace is inevitably accompanied by a small amount of platinum group elements. Since the group element eventually moves into the molten metal layer, the recovery rate of the platinum group element is further increased.

  In addition, in this oxidation furnace, an oxygen atmosphere or an oxygen-containing gas is introduced in an oxidizing atmosphere. Therefore, most of the rhenium and arsenic in the molten metal charged with the platinum group element into the oxidation furnace becomes dust, and in the oxidation furnace The generated exhaust gas containing dust is guided from the space in the oxidation furnace to the dust recovery device via the exhaust port, and the dust is recovered. That is, both the elements of rhenium and arsenic in the molten metal charged in the oxidation furnace in an oxidizing atmosphere are separated from the secondary metal solution as dust.

  This dust recovery device from the oxidation furnace exhaust gas is a dry dust recovery device that recovers dust from the oxidation furnace exhaust gas without using the cleaning liquid, and cleaning the oxidation furnace exhaust gas using the cleaning liquid to recover the dust in the exhaust gas into the cleaning liquid. Any of the wet dust collecting apparatuses can be employed. Since the oxidation furnace charge is a primary solution metal, almost no moisture is contained in the oxidation furnace exhaust gas. Therefore, in the dry method, a lightning-type flue (Zig-Zag Fluid), a dust chamber (Dust Chamber) ), No matter which cyclone is used, there is no inconvenience such as wet dust adhering to the exhaust gas passage, narrowing the passage, applying load to the exhaust fan, and unstable dust collection, Even when the baghouse is adopted, the bag filter is not clogged with moist dust, and the exhaust fan is loaded and the dust collection becomes unstable, and even when the cotrel is adopted, There will be no inconveniences such as fluctuations in moisture in the exhaust gas or dust adhering to the dust collecting electrode, resulting in unstable electric field and unstable dust collection. In addition, the dust recovered by the dry method can be temporarily stored in a powder state in a dust storage unit such as below in the recovery device.

Subsequently, the leaching process of the dust collected by the dust collecting device of the oxidation furnace is performed. When dust is collected by a dry method, the dust is extracted from the dust collecting part or the dust storage part and leached with an alkaline solution. By this leaching treatment, rhenium and arsenic in the dust containing rhenium, arsenic, a small amount of platinum group element, and copper are leached together.
Here, sodium hydroxide, potassium hydroxide, ammonium hydroxide, or the like can be used as the alkaline solution.

  In addition, when a wet dust recovery device for cleaning the oxidation furnace exhaust gas using an alkaline solution as a cleaning liquid and recovering dust in the exhaust gas into the cleaning liquid is adopted as the dust recovery device from the oxidation furnace exhaust gas, dust recovery and alkali Solution leaching can be performed simultaneously.

  Here, the leaching process may process the entire amount of collected dust. In addition, if a part of the collected dust is charged into at least one of the electric furnace and the oxidation furnace and repeated in the system, and the remainder is leached, the rhenium and arsenic in the dust are concentrated. As a result, rhenium and arsenic can be leached to a high concentration.

  Next, the slurry after the dust leaching treatment is subjected to solid-liquid separation to be separated into a solution in which rhenium and arsenic are dissolved and a leaching residue. Since the leaching residue contains a small amount of rhenium, arsenic, copper scattered from the oxidation furnace, and a platinum group element, it is charged into at least one of the electric furnace and the oxidation furnace and repeated in the system.

Thereafter, rhenium is separated and recovered as a rhenium chloride precipitate by adding chloride to a solution in which rhenium and arsenic are obtained by solid-liquid separation of the leached slurry, while the arsenic solution is Arsenic removal can be performed by a known wastewater treatment process. As described above, the liquid temperature in the chloride addition step and the solid-liquid separation step is preferably maintained within a predetermined temperature range.
Moreover, sodium chloride, potassium chloride, ammonium chloride etc. can be used as said chloride for addition.

[Example 1]
As a smelting raw material, 700 kg of a copper source material (metallic copper) is mixed with 1500 kg of a substance to be treated containing 900 ppm of Pt, 40 ppm of Re, and 100 ppm of arsenic as an impurity, and further 1000 kg of CaO as a flux component. 200 kg of Fe ₂ O ₃ and 800 kg of SiO ₂ and 60 kg of coke as a reducing agent were mixed.
This mixture is put into an electric furnace, heated to 1350 ° C. and held in a molten state for 4 hours, and then the primary slag, which is a glassy oxide formed in the upper layer, flows out from the side of the electric furnace, and then the lower layer copper metal The primary metal (500 kg) was extracted from the lower part of the electric furnace and led to a heated oxidation furnace. Analysis of this metallic copper revealed Pt: 1890 ppm, Re: 82 ppm, and As205 ppm. Oxygen-enriched air with 40% oxygen was blown onto the metallic copper (primary metal) at a position approximately 50 mm below the surface of the hot water melted with a lance, and a portion of the metallic copper was oxidized to obtain 450 kg of copper oxide. . During this time, dust was collected from the upper part of the oxidation furnace, and 1.05 kg of oxidation furnace dust was collected on the bag filter.
When this dust was analyzed, they were Pt: 520 ppm, Re: 26000 ppm, As: 65000 ppm, Cu: 12.7 mass% (simply expressed as%).

Next, 1000 g of the dust was leached into 4 liters of 25% NaOH solution (denoted as L). The leaching rate of Re was 96.4%, the leaching rate of As was 75.6%, and the leaching rate of Cu was 2%. , Pt did not leach and remained in the residue.
This leaching residue was washed with water, dried at 100 ° C., and measured for mass. As a result, it was 570 g, Pt: 910 ppm, Re: 1640 ppm, As: 27800 ppm, Cu: 21.8%. The leaching residue was put into an electric furnace together with a new smelting raw material in order to recover Pt.
On the other hand, 4 L after the NaOH leaching contained Re: 6.6 g / L and As: 12.9 g / L. The following chloride addition operation was performed about this liquid.
After leaching with NaOH, 150 g of potassium chloride was added to 1 L of the liquid with stirring to obtain a precipitate. The steps of adding potassium chloride and solid-liquid separation were performed while maintaining the liquid temperature at 30 ° C.
When this precipitate was washed with water and dried at 100 ° C., a Re concentrate having a mass of 12 g, Re: 51.7% by mass (recovery rate 94%), and As: 4.3% by mass (mixing rate 4%) was obtained. Obtained. The Re concentrate was targeted for Re recovery, and the filtrate was sent to the As wastewater treatment process.

[Example 2]
After leaching NaOH of Re: 6.6 g / L and As: 12.9 g / L obtained in Example 1, 100 g of potassium chloride was added to 1 L of the liquid with stirring to obtain a precipitate. The steps of adding potassium chloride and solid-liquid separation were performed while maintaining the liquid temperature at 20 ° C.
When this precipitate was washed with water and dried at 100 ° C., the Re concentration was 19 g, Re: 33.0% by mass (recovery rate 95%), As: 1.8% by mass (mixing rate 2.6%). I got a thing. The Re concentrate was targeted for Re recovery, and the filtrate was sent to the As wastewater treatment process.

[Reference Example 1]
The same procedure as in Example 1 was performed except that the steps of adding potassium chloride and solid-liquid separation were performed while maintaining the liquid temperature at 10 ° C.
When the precipitate was washed with water and dried at 100 ° C., a Re concentrate having a mass of 65 g, Re: 10% by mass (recovery rate: 98%), and As: 11.5% by mass (contamination rate: 57%) was obtained. . The Re concentrate was targeted for Re recovery, and the filtrate was sent to the As wastewater treatment process.

It is a schematic sectional drawing which shows the example of the electric furnace used by melt smelting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealed type electric furnace 2 Furnace space 3 Furnace body 4 Charge input 5 Exhaust 6 Higher fluid (primary slag) discharge 7 Lower fluid (primary metal) discharge 8 Charge input chute 9 Exhaust device 10 Electrode

Claims (7)

  The material to be treated containing platinum group elements, rhenium and arsenic is leached with an alkaline solution and then solid-liquid separated to obtain a solid enriched with platinum group elements and a solution leached with rhenium and arsenic. A method for treating a substance to be treated containing platinum group elements, rhenium and arsenic, wherein chloride is added and then solid-liquid separation is performed to obtain a solid enriched in rhenium and a solution enriched in arsenic.   Processed materials containing platinum group elements, rhenium and arsenic recovered as dust from smelting furnace exhaust gas were leached with an alkaline solution, then solid-liquid separation was performed and rhenium and arsenic were leached. After obtaining a solution, a chloride is added to the solution, followed by solid-liquid separation to obtain a rhenium-concentrated solid and an arsenic-concentrated solution of a substance to be treated containing platinum group elements, rhenium and arsenic. Processing method.   A material to be treated containing a platinum group element, rhenium and arsenic, and a copper source material mainly composed of at least one selected from the group consisting of metallic copper and copper oxide are charged into an electric furnace together with a flux component and a reducing agent. After being melted and separated into a primary slag layer mainly composed of oxide and a primary metal layer mainly composed of metal copper, the primary metal is charged into an oxidation furnace and oxidized to form a secondary slag layer mainly composed of oxide and a platinum group element. While separating into a concentrated metallic copper-based secondary metal layer, the dust is recovered from the gas introduced from the space in the oxidation furnace, and then the dust is leached with an alkaline solution, followed by solid-liquid separation. A platinum group element that obtains a concentrated solid and a solution leached with rhenium and arsenic, and then adds chloride to the solution, followed by solid-liquid separation to obtain a solid enriched with rhenium and a solution enriched with arsenic. , Rhenium and arsenic Treatment of the treated substance containing.   The processing method according to claim 3, wherein at least a part of the collected dust is charged into at least one of the electric furnace and the oxidation furnace.   The processing method according to claim 3 or 4, wherein at least a part of the secondary slag is cooled with water in a molten state to obtain a granular material containing copper oxide and used as the copper source material.   The processing method according to claim 3 or 4, wherein at least part of the secondary slag is reduced in a molten state to obtain a metal copper-containing material and used as the copper source material.   The processing method according to any one of claims 1 to 6, wherein the step of adding chloride to the solution leached with rhenium and arsenic and then performing solid-liquid separation is performed while maintaining the liquid temperature at 20 to 40 ° C.

Images