Sb recovery method

Abstract

This method allows for the selective recovery of Sb from a substance containing Sb and other heavy metal elements such as Pb, without using hydrofluoric acid solution. [Solution] The present invention provides a method for recovering Sb and related technologies, comprising: a first heating step of roasting a workpiece containing Sb and Pb at a temperature in the range of 250 to 350°C; a second heating step of roasting the workpiece under reduced pressure below atmospheric pressure after the first heating step to selectively volatilize the Sb-containing compounds; and a recovery step of recovering the Sb-containing compounds volatilized by the second heating step.

Description

Technical Field

[0001] The present invention relates to a method for recovering Sb. In particular, the present invention relates to a method for recovering Sb from lead electrolytic slime containing Sb (antimony) and Pb (lead).

Background Art

[0002] The summary of Patent Document 1 describes the following content. "By leaching antimony from an intermediate product of a process containing antimony (an object product containing antimony) by a wet method, a method for producing antimony oxide and the like that enhance the separability of antimony and impurities and can efficiently reduce impurities in a short time and reliably are provided. A method for producing antimony oxide, characterized by including at least a leaching step of treating an object product containing antimony with a fluorine-containing liquid and leaching antimony into the fluorine-containing liquid. A mode in which the fluorine-containing liquid is at least one selected from a hydrofluoric acid solution, a mixed solution of a soluble fluoride and sulfuric acid, etc. is preferable."

[0003] In Example 1 of Patent Document 1

[0038] , the following content is described.

[0004] As the above intermediate product of the process, an intermediate product generated when electrolytic slime generated in the lead smelting process (lead electrolytic slime in this specification) is reduced is described.

[0005] In Example 1 of Patent Document 1, first, lead electrolytic slime is reduced. The intermediate product of the process generated by the reduction is treated with a fluorine-containing liquid, and antimony is leached into the fluorine-containing liquid. An aqueous sodium hydrosulfide solution is added to the obtained leachate to obtain a filtrate. By adding the aqueous sodium hydrosulfide solution, heavy metal elements (for example, lead (Pb)) that become impurities other than Sb are transferred to the residue (

[0022] of Patent Document 1). Next, an aqueous sodium hydroxide solution is added to the obtained filtrate to obtain a precipitate containing antimony oxide (Sb2O3) produced from Sb by neutralization. The precipitate is separated by filtering the neutralized filtrate, and then washed with water to remove any sodium fluoride adhering to the precipitate. Finally, it is dried to obtain antimony oxide (Sb2O3). After a series of wet treatments starting with a fluorine-containing solution, the resulting dried antimony oxide (Sb2O3) is reduced using coke or the like to obtain metallic Sb. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-184653 [Overview of the project] [Problems that the invention aims to solve]

[0007] Figure 1 is a flowchart illustrating the method described in Patent Document 1, adapted to the situation at the time of filing this application.

[0008] Patent Document 1 proposes a method for removing Pb, a heavy metal element other than Sb, by a series of wet treatments starting with a fluorine-containing solution, as described above. However, hydrofluoric acid solution is given as an example of this fluorine-containing solution (see

[0016] of Patent Document 1). Hydrofluoric acid solution is an expensive chemical and must be handled carefully. As a result, there is a problem that the cost of purifying Sb becomes expensive. This problem is not limited to the recovery of Sb from lead electrolytic slime, but also arises similarly in the recovery of Sb from substances containing both Sb and Pb.

[0009] The object of the present invention is to provide a method for selectively recovering Sb relative to Pb from a substance containing Sb and another heavy metal element, Pb (particularly lead electrolytic slime), without using a hydrofluoric acid solution. In the present invention, recovering a substance from a material containing Pb and Sb in which the concentration of Sb is high and the concentration of Pb is low compared to the material being treated is expressed as "selectively recovering Sb relative to Pb." [Means for solving the problem]

[0010] Figure 2 is a flowchart illustrating a method according to one embodiment of the present invention.

[0011] In order to solve the above problems, the inventors diligently conducted research. The inventors focused on the flowchart in Patent Document 1. In Patent Document 1, the lead electrolytic slime is reduced first. On the other hand, the inventors discovered that if Sb is selectively volatilized relative to Pb from lead electrolytic slime containing Pb and Sb, the above series of wet treatments starting with hydrofluoric acid solution and further with the fluorine-containing solution as described in Patent Document 1 becomes unnecessary. In other words, the inventors discovered that the selective recovery of Sb relative to Pb from lead electrolytic slime (in a broad sense, a material to be treated containing Sb and Pb) can be done in a dry manner.

[0012] The inventions made based on the above findings are as follows: The first invention is, A first heating step involves roasting a material containing Sb and Pb within a range of 250 to 350°C, Following the first heating step, a second heating step is performed in which the workpiece is roasted under reduced pressure below atmospheric pressure to selectively volatilize the Sb-containing compound. A recovery step for recovering the Sb-containing compound that has volatilized by the second heating step, This is a method for recovering Sb, which has the following characteristics:

[0013] The second invention is, The material to be treated is lead electrolytic slime, and this is a method for recovering Sb according to the first embodiment.

[0014] The third invention is, The Sb-containing compound recovery method of Sb according to the first or second aspect, wherein the Sb-containing compound contains Sb2O3.

[0015] The fourth invention is The Sb recovery method according to any one of the first to third aspects, wherein the roasting temperature in the second heating step is in a range having a lower limit of a temperature 50°C higher than the temperature at which the saturated vapor pressure of Sb2O3 is reached under the reduced pressure and an upper limit of a temperature 200°C higher than the temperature at which the saturated vapor pressure of Sb2O3 is reached.

[0016] The fifth invention is The Sb recovery method according to any one of the first to fourth aspects, wherein the second heating step is performed at 1000 Pa or less. <00岁0081> The sixth invention is A first heating step of roasting lead electrolytic slime containing Sb and Pb within a range of 250 to 350°C, After the first heating step, a second heating step of roasting the lead electrolytic slime under a reduced pressure of 1000 Pa or less to selectively volatilize an Sb-containing compound containing Sb2O3, A recovery step of recovering the Sb-containing compound volatilized by the second heating step, having The Sb recovery method according to the first aspect, wherein the roasting temperature in the second heating step is in a range having a lower limit of a temperature 50°C higher than the temperature at which the saturated vapor pressure of Sb2O3 is reached under the reduced pressure and an upper limit of a temperature 200°C higher than the temperature at which the saturated vapor pressure of Sb2O3 is reached.

Advantages of the Invention

[0018] According to the present invention, it is possible to selectively recover Sb with respect to Pb from a substance containing Sb and another heavy metal element Pb without using a hydrofluoric acid solution.

Brief Description of the Drawings

[0019] [Figure 1]Figure 1 is a flowchart illustrating the method described in Patent Document 1, adapted to the situation at the time of filing this application. [Figure 2] Figure 2 is a flowchart illustrating a method according to one embodiment of the present invention. [Figure 3] Figure 3 is a schematic side cross-sectional view of the apparatus used in the example section. [Figure 4] Figure 4 shows the vapor pressure curves for each composition (vertical axis: Log[P(atm)], horizontal axis: temperature (°C)). [Modes for carrying out the invention]

[0020] The present invention will be described below. First, a preferred specific example will be given to explain its contents. Then, modifications outside of this specific example, and contents encompassing both examples, will be described. "~" indicates a value greater than or equal to a predetermined value and less than or equal to a predetermined value.

[0021] An example of a "material to be treated that contains Sb and Pb" is lead electrolytic slime, and lead electrolytic slime will be used as an example hereafter. However, it may be a substance other than lead electrolytic slime, for example, a substance generated by non-ferrous metal smelting (residue, dust, etc.). "Lead electrolytic slime" in the following description may be replaced with "material to be treated".

[0022] A preferred example of a method for recovering Sb according to the present invention comprises the following steps. • First heating step: Roasting lead electrolytic slime containing Sb and Pb within a range of 250-350°C. • A second heating step is performed after the first heating step, in which the lead electrolytic slime is roasted under reduced pressure of 1000 Pa or less to selectively volatilize Sb-containing compounds including Sb2O3. • Recovery process for recovering Sb-containing compounds that have volatilized by the second heating process.

[0023] The first and second heating steps selectively volatilize Sb-containing compounds, including Sb2O3, which is formed by the oxidation of Sb. One possible mechanism for this, although purely speculative, is that Pb may be alloyed with the following heavy metal element α in the lead electrolytic slime.

[0024] The heavy metal element α may include at least one of Bi, Ag, Cu, or Te. As the vapor pressure curves of each compound in Figure 4 show, the elements listed above exhibit similar volatility tendencies; that is, Sb2O3 remains highly volatile. In this specification, "heavy metal" refers to a compound with a density of 4 g / cm³. 3 This refers to the metals listed above.

[0025] By performing the first heating step, the Pb-containing alloy becomes less likely to volatilize relative to the Sb-containing compound, and the Sb-containing compound becomes more likely to volatilize relative to the Pb. As shown in the examples below, the present invention allows for the selective volatilization of the Sb-containing compound relative to the Pb.

[0026] The Sb-containing compounds that volatilize in the second heating step are recovered in the recovery step. As a result, as shown in Figure 2, it becomes possible to recover metallic Sb from lead electrolytic slime by dry treatment alone, without using hydrofluoric acid solution. Specifically, from the drying of the lead electrolytic slime obtained from the electrolytic cell to the recovery step of the precipitate obtained by selectively volatilizing the Sb-containing compounds including Sb2O3 (and furthermore, to selectively recover metallic Sb relative to Pb from the precipitate), dry work is possible.

[0027] The roasting temperature range for the first heating step is preferably 250 to 350°C. If the first heating step is performed within the range of 250 to 350°C, a good Sb volatilization rate can be obtained, as shown in the examples below, and the Pb content, which is an impurity in the precipitate resulting from the volatilization of Sb, decreases. The lower limit of the temperature range for the first heating step is preferably 260°C or 270°C, and the upper limit is preferably 320°C, 300°C, or 280°C. If the upper limit is 280°C, the Sb volatilization rate increases, as shown in Examples 1 and 2 below. On the other hand, even if the upper limit is not 280°C, there is the advantage that the amount of Pb, an impurity, becomes extremely low, as shown in Example 3 (300°C) below.

[0028] Aside from the roasting temperature in the first heating step, there are no particular limitations on the other conditions. The pressure does not need to be reduced or increased and can be atmospheric pressure. The atmosphere is not particularly limited and can be, for example, air or nitrogen.

[0029] From the viewpoint of reducing the amount of Pb in the precipitate, the duration of the first heating step is preferably 0.5 to 20 hours, more preferably 1 to 10 hours, and particularly preferably 1 to 5 hours.

[0030] The conditions for the second heating step are not limited as long as the Sb-containing compound, including Sb2O3, can be selectively volatilized. The Sb-containing compound contains Sb2O3 as its main component. Some of this Sb2O3 was originally present in the lead electrolytic slime, while other parts were generated from Sb during the first heating step. Alternatively, if the first heating step is not performed, the Sb2O3 in the Sb-containing compound will consist of both the Sb originally present in the lead electrolytic slime and the Sb generated from Sb during the second heating step.

[0031] In this specification, the "main component" is the substance that is present in the largest quantity among the various substances (compounds, metal elements) that make up the Sb-containing compound, and preferably the substance that is present in a proportion exceeding 50%. The Sb-containing compound may also contain unreacted metallic Sb in addition to Sb2O3.

[0032] The following is an example of the range of roasting temperatures for the second heating process. Lower limit: A temperature 50°C higher than the temperature at which Sb2O3 reaches its saturated vapor pressure under reduced pressure of 1000 Pa or less (or 0.01 atm or less). In a more specific example, the horizontal axis value at the intersection point at 500 Pa (0.0049 atm) on the vapor pressure curve of Sb2O3 in Figure 4 is approximately 400°C + 50°C = 450°C (i.e., in this specific example, reduced pressure of 500 Pa or less is assumed). Upper limit: A temperature 200°C higher than the temperature at which Sb2O3 reaches its saturated vapor pressure under reduced pressure of 1000 Pa or less (or 0.01 atm or less). In a more specific example, the horizontal axis value at the intersection point at 500 Pa (0.0049 atm) on the vapor pressure curve of Sb2O3 in Figure 4 is approximately 400°C + 200°C = 600°C (i.e., in this specific example, reduced pressure of 500 Pa or less is assumed).

[0033] The atmosphere during the second heating step may be anything other than air, such as a nitrogen atmosphere, provided it is under reduced pressure. The duration of the second heating step can be, for example, 0.5 to 5 hours.

[0034] The recovery step for recovering the Sb-containing compound that has volatilized in the second heating step can be performed by recovering the precipitate formed by the volatilized Sb-containing compound. Any known method can be used to obtain Sb from the precipitate. For example, the dry treatment process from the Sb precipitate stage onward shown in Figure 1 may be used.

[0035] From the viewpoint of shortening the time until the Sb-containing compound volatilizes, the lead electrolytic slime to be processed preferably has an average particle size D50 of 1 mm or less, more preferably 50 μm or less, and particularly preferably 10 μm or less, as determined by laser diffraction.

[0036] Furthermore, the first and second heating processes can be carried out using the same heating device.

[0037] The pressure conditions in the second heating process only need to be reduced pressure below atmospheric pressure. The above values ​​of 1000 Pa or less, 500 Pa or less (or 0.01 atm or less, 0.0049 atm or less) are merely examples. An example of reduced pressure below atmospheric pressure is a vacuum level higher than so-called low vacuum (pressure of 100,000 Pa or less, preferably 1,000 Pa or less).

[0038] The second heating step may use an electric furnace as shown in Figure 3, or any other known heating furnace. There are no limitations as long as the set vacuum level can be maintained. The same applies to the first heating step.

[0039] An example of an electric furnace that can be used in the present invention, shown in Figure 3, will be briefly described. The electric furnace comprises a horizontally elongated quartz tube on which a dish for holding the object to be processed is arranged, and a horizontally elongated tubular furnace for heating the quartz tube. The inner diameter of the quartz tube is 32 mm, the outer diameter is 36 mm, and the length is 700 mm. A vacuum gauge is attached to one end of the quartz tube, and a membrane filter is attached to the other end. The thickness of the membrane filter is 0.2 μm. The inside of the quartz tube and a vacuum pump are connected via the membrane filter. Between the vacuum pump and the membrane filter, a leak valve and a float-type flow meter are installed in that order from the perspective of the membrane filter. By controlling the suction amount of the vacuum pump with the flow meter, the quartz tube can be maintained at a constant pressure.

[0040] If the first heating step is performed within the range of 250 to 350°C, it may be accompanied by a first preheating step in which heating begins from the state in which the lead electrolytic slime is placed in the heating furnace, i.e., passing through a state below 250°C. Similarly, it may be accompanied by a first slow cooling step in which slow cooling begins from the state in which the lead electrolytic slime is placed in the heating furnace, i.e., passing through a state below 250°C. Of course, the lead electrolytic slime may also be placed in a heating furnace that has been pre-set to a temperature within the range of 250 to 350°C.

[0041] The second heating step may be accompanied by a first preheating step, which starts heating from a state where the lead electrolytic slime is placed in the heating furnace, i.e., passes through a state below the above lower limit, provided that the second heating step is performed at a temperature within a range where the lower limit is 50°C higher than the temperature at which Sb2O3 becomes saturated vapor pressure under reduced pressure, and the upper limit is 200°C higher than the temperature at which Sb2O3 becomes saturated vapor pressure. Similarly, the second heating step may be accompanied by a first slow cooling step, which starts slow cooling from a state where the lead electrolytic slime is placed in the heating furnace, i.e., passes through a state below the above lower limit. Of course, the lead electrolytic slime may also be placed in a heating furnace that has been pre-set to a temperature within the above range.

[0042] By going through the second heating step, it is preferable to make the volatility and recovery rate of Sb 60% or more (preferably 80% or more), and it is preferable to make the grade of Pb, an impurity in the precipitate 150 ppm or less (more preferably 100 ppm or less, or 50 ppm or less). In the examples shown below, the volatility of Sb is 60% or more, and the Pb impurity in the precipitate is 150 ppm or less, so the recovery efficiency of Sb is good, and consequently, Sb can be selectively recovered from Pb.

[0043] The technical scope of the present invention is not limited to the embodiments described above, and includes various modified and improved forms to the extent that specific effects can be obtained by the constituent elements of the invention or combinations thereof.

[0044] For example, as shown in the section on the embodiments below, the second heating step may be repeated on the precipitate obtained in the second heating step between the second heating step and the recovery step. [Examples]

[0045] The present invention will be described more specifically below with reference to the examples. However, the present invention is not limited to these examples.

[0046] In Example 1, lead electrolytic slime containing Sb2O3 was treated. The metal element content of the lead electrolytic slime after the drying treatment described below is as shown in the table below. [Table 1]

[0047] Before performing the first heating step, the lead electrolytic slime underwent the following treatment. First, the lead electrolytic slime was placed in a constant temperature bath and dried. The temperature of the constant temperature bath was set to 110°C, and the drying time was 17 hours. Coarse grinding was performed on the dried lead electrolytic slime. A jaw crusher was used for coarse grinding, and the particle size was reduced to 10 mm or less. The coarsely ground dried powder was classified using a 1 mm sieve, and the dried powder on the sieve was separately crushed. Subsequently, the dried powder below a 1 mm sieve and the separately crushed dried powder were sieved using a stainless steel sieve (particle size 100 μm or less) to obtain dried powder with a particle size of 100 μm or less. This dried powder was then finely ground to obtain finely ground material. An ultrafine grinder (mascoloider) was used for the fine grinding. Finally, the finely ground material was placed in a constant temperature bath and dried. The temperature of the constant temperature bath was set to 110°C, and the drying time was 17 hours. As a result, lead electrolytic slime powder with a D50 of 10 μm was obtained.

[0048] 30 g of lead electrolytic slime powder with an average particle size of 10 μm was packed into a 30 mL magnetic round-bottom evaporating dish, and roasted in an electric furnace shown in Figure 3 at 270°C for 4 hours in an air atmosphere to obtain a roasted product (first heating step).

[0049] Subsequently, 5g of the roasted material was separated and placed in a Nikkatoh alumina boat #5B, and heated for 1.5 hours at a furnace temperature of 575°C and under a nitrogen atmosphere at a pressure of 500 Pa (second heating step).

[0050] After returning to atmospheric pressure, the Sb-containing compound precipitated in the electric furnace was recovered (recovery step).

[0051] ICP-AES (ICP emission spectroscopy) was performed on Sb-containing compounds to obtain information about the composition of each element.

[0052] The following table shows the test conditions for the first heating step (temperature, time, atmosphere) and the second heating step (pressure (Pa), temperature, time, which is also a value indicating the degree of vacuum) in each example, the amount of Sb in the residue remaining after the second heating step (i.e., the residual rate), the amount of Sb in the precipitate recovered after the target Sb has been volatilized (i.e., the volatilization rate), and the Pb grade (ppm), which is an impurity in the precipitate. In Example 2, the lead electrolytic slime pretreatment was limited to crushing, and no fine grinding was performed. Otherwise, the procedure was the same as in Example 1. In Example 3, the lead electrolytic slime pretreatment was limited to crushing, and no fine grinding was performed. The temperature set in the first heating step was 300°C. Otherwise, the procedure was the same as in Example 1. In Comparative Example 1, the first heating step described above was omitted. Otherwise, the procedure was the same as in Example 1. In Comparative Example 2, the first heating step described above was omitted. The setting temperature for the second heating step was 600°C and the heating time was 0.5 hours. All other aspects were the same as in Example 1. In Comparative Example 3, the temperature set for the first heating step was 400°C and the heating time was 1 hour, while the second heating step was omitted. In other words, only the roasting under atmospheric pressure, which is the first heating step, was performed. Everything else was the same as in Example 1. The volatility of Sb was obtained using the following formula. Sb volatility [%] = (Weight of Sb in raw material [g] - Weight of Sb in residue [g]) / Weight of Sb in raw material [g] × 100 [Table 2]

[0053] In Examples 1-3, Sb could be selectively recovered from substances containing Sb and other heavy metals (particularly lead electrolytic slime) relative to Pb without using hydrofluoric acid solution. Comparative Examples 1 and 2 contained more Pb than Examples 1-3. In other words, Comparative Examples 1 and 2 could not selectively recover Sb relative to Pb as well as Examples 1-3. In Comparative Example 3, Sb did not volatilize at all.

Claims

1. A first heating step involves roasting a material containing Sb and Pb within a range of 250 to 350°C, Following the first heating step, a second heating step is performed in which the workpiece is roasted under reduced pressure below atmospheric pressure to selectively volatilize the Sb-containing compound. A recovery step for recovering the Sb-containing compound that has volatilized by the second heating step, A method for recovering Sb, comprising the following:

2. The method for recovering Sb according to claim 1, wherein the material to be treated is lead electrolytic slime.

3. The aforementioned Sb-containing compound is Sb ２ O ３ A method for recovering Sb according to claim 1 or 2, including the method described in claim 1 or 2.

4. The roasting temperature in the second heating step is Sb under reduced pressure. ２ O ３ The lower limit is set to a temperature 50°C higher than the temperature at which the saturated vapor pressure of Sb is reached. ２ O ３ A method for recovering Sb according to claim 1 or 2, wherein the upper limit of the temperature is 200°C higher than the temperature at which the saturated vapor pressure of Sb occurs.

5. The method for recovering Sb according to claim 1 or 2, wherein the second heating step is performed at 1000 Pa or less.

6. A first heating step involves roasting lead electrolytic slime containing Sb and Pb in the range of 250 to 350°C, After the first heating step, the lead electrolytic slime is roasted under reduced pressure of 1000 Pa or less to obtain Sb ２ O ３ A second heating step in which an Sb-containing compound containing the above is selectively volatilized, A recovery step for recovering the Sb-containing compound that has volatilized by the second heating step, It has, The roasting temperature in the second heating step is 50°C higher than the temperature at which the saturated vapor pressure of Sb ２ O ３ is the lower limit, and the temperature is within the range where the upper limit is 200°C higher than the temperature at which the saturated vapor pressure of Sb ２ O ３ is the saturated vapor pressure. The method for recovering Sb according to claim 1.

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