JP3744014B2 - Production method of rhodium powder - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for producing metal rhodium, and more particularly to purification of metal rhodium obtained from a hydrochloric acid rhodium solution.
[0002]
[Prior art]
In general, rhodium is obtained as a by-product of copper smelting or as a recovered product from an automobile waste catalyst or the like. Usually, rhodium is rarely present alone, and coexists with platinum, palladium, ruthenium and the like. As a result, in order to recover rhodium, not only various impurities but also separation from these platinum group metals is indispensable.
[0003]
All of the proposed methods for separating platinum group metals are composed of a combination of precipitation separation, ion exchange, and solvent extraction. It is that it is separated in the physical system. This is because it is most convenient for each platinum group metal to easily form a coordination compound with chloride ions, and to separate each metal by the difference in stability between these coordination compounds. .
[0004]
In any case, rhodium is usually first recovered as a chloride solution after various separation steps. Then, rhodium is precipitated as rhodium hydroxide by neutralization treatment, or a complexing agent is added to form a rhodium complex salt. After precipitation and separation and recovery, these are heated to obtain a metal rhodium powder. Yes.
[0005]
[Problems to be solved by the invention]
In recent years, high purity has been demanded for various metals, and rhodium is an object. However, the rhodium powder obtained as described above has many impurities such as sodium, chlorine and oxygen, and as it is, it does not reach the high purity. Therefore, the obtained metal powder is usually treated with a strong acid such as hydrofluoric acid or hydrochloric acid to reduce the sodium content, or heat-treated at a temperature exceeding 1100 ° C. in a hydrogen stream to volatilize sodium as sodium chloride. Such a method is adopted.
[0006]
However, since the former method uses a strong acid that is liable to volatilize or become mist, there is a drawback in that corrosion of related equipment is remarkable, and an apparatus made of an expensive material is required to prevent this. In the latter case, the obtained metal rhodium powder is in a sintered state, and a pulverization step is required thereafter.
[0007]
This invention is made | formed by such a condition, and makes it a subject to provide the manufacturing method of the low sodium, low chlorine, and low oxygen rhodium powder which does not have the said fault.
[0008]
[Means for Solving the Problems]
In the method of the present invention for solving the above problems, hydrogen is blown into a chloride solution containing rhodium , rhodium ions are precipitated as metal powder, and the metal powder is heated in a hydrogen atmosphere at 800 to 1000 ° C., preferably 800 to 900 ° C. 1 to 4 hours, preferably 2 to 4 hours, and then heated in an inert atmosphere at 800 to 1000 ° C., preferably 800 to 900 900 ° C. for 1 to 4 hours, preferably 2 to 4 hours.
[0009]
[Action]
In the present invention, hydrogen is used for the reduction of rhodium ions in order to prevent unnecessary impurities from being brought into the system and thereby improving the quality of impurities in the resulting metal powder. In addition, the reduction conditions are moderated to minimize the incorporation of impurities into the metal powder. Various conditions such as pH and temperature when hydrogen gas is blown are determined by what physical properties of the metal powder are obtained, and are naturally within a range that can be selected by those skilled in the art. Moreover, the end point of this reaction can be easily determined by the disappearance of the color of the rhodium ion in the solution.
[0010]
The rhodium solution is preferably a chloride system.
[0011]
Although the metal powder obtained in this way has low sodium quality, the quality of chlorine and oxygen, which is a gas component, is high as with conventional products. In the method of the present invention, this metal powder is heated in a hydrogen atmosphere to volatilize chlorine as hydrogen chloride and oxygen as water vapor. At this time, if the heating temperature is too low, the reaction becomes insufficient, and if it is too high, sintering occurs. Therefore, the heating temperature is 800 to 1000 ° C, preferably 800 to 900 ° C.
[0012]
The relationship between the heating time and the temperature is important. However, if the reaction time is short, the reaction is not sufficient. If the reaction time is too long, sintering starts depending on the temperature. Depending on the temperature, although sintering does not occur, a further effect cannot be expected, and the economy is impaired. Therefore, the heating time is 1 to 4 hours, preferably 2 to 4 hours in the temperature range of the present invention.
[0013]
Although the quality of chlorine and oxygen in the metal powder can be lowered by this treatment, the quality of hydrogen is increased. For this reason, in order to further reduce chlorine, oxygen, and adsorbed hydrogen, the metal powder is heated in an inert atmosphere. If the heating temperature at this time is too low, these components are not sufficiently reduced, and if it is too high, the metal powder is sintered. Therefore, the heating temperature is 800 to 1000 ° C, preferably 800 to 900 ° C.
[0014]
The heating time has an important relationship with the temperature as described above. In general, if the reaction time is too short, the reaction is not sufficient. If the reaction time is too long, sintering starts depending on the temperature. Depending on the temperature, although sintering does not occur, further effects cannot be expected so much and the economy is impaired. Therefore, in the temperature range of the method of the present invention, the heating time is 1 to 4 hours, preferably 2 to 4 hours.
[0015]
【Example】
Next, examples of the present invention will be described.
[0016]
Example 1
Blowing hydrogen chloride at a rate of 1.0 l / min into a hydrochloric acid rhodium solution containing rhodium at a rate of 50 g / l and Cl at a rate of 45 g / l until the solution is colorless and transparent, rhodium as a metal powder Precipitated. This metal powder was subjected to solid-liquid separation, and a part was used as an analysis sample, and a part was used in the subsequent tests. The obtained analytical values were Na: 1.1 ppm, chlorine: 6800 ppm, oxygen: 29000 ppm, and very little sodium. The yield was 99.9% or more.
[0017]
100 g of the obtained metal powder was filled in a quartz boat, and this was inserted into a soaking part of a quartz tube provided in an annular furnace, and a nitrogen purge was performed while raising the temperature. When the temperature of the soaking part reached 200 ° C., nitrogen was switched to hydrogen, hydrogen was blown into the quartz tube at a rate of 0.5 l / min, and the temperature was continued. When the temperature of the soaking part reached 850 ° C., the temperature increase was stopped, and then the temperature was maintained at 850 ° C. for 4 hours while flowing hydrogen into the quartz tube.
[0018]
Subsequently, the hydrogen was switched to argon, the blowing rate was 1.0 l / min, and the mixture was held at 850 ° C. for 4 hours.
[0019]
After allowing to cool, the obtained rhodium powder was analyzed to determine the quality of Na, chlorine and oxygen. As a result, it was found that Na: 0.4 ppm, chlorine: 170 ppm, and oxygen: 80 ppm were greatly reduced. The fired product was not sintered and was in a good dispersion state.
[0020]
(Example 2)
100 g of the metal powder obtained in Example 1 was filled in a quartz boat, which was inserted into a soaking part of a quartz tube provided in an annular furnace, and purged with nitrogen while raising the temperature. When the temperature of the soaking part reached 200 degrees, nitrogen was switched to hydrogen, hydrogen was blown into the quartz tube at a rate of 0.5 l / min, and the temperature was continued. When the temperature of the soaking part reached 850 ° C., the temperature increase was stopped, and then the temperature was maintained at 850 ° C. for 2 hours while flowing hydrogen into the quartz tube.
[0021]
Subsequently, the hydrogen was switched to argon, the blowing rate was 1.0 l / min, and the mixture was held at 850 ° C. for 2 hours.
[0022]
After allowing to cool, the obtained rhodium powder was analyzed to determine the quality of Na, chlorine and oxygen. As a result, it was found that Na: 0.7 ppm, chlorine: 340 ppm, and oxygen: 180 ppm were greatly reduced. The fired product was not sintered and was in a good state.
[0023]
Example 3
100 g of the metal powder obtained in Example 1 was filled in a quartz boat, which was inserted into a soaking part of a quartz tube provided in an annular furnace, and purged with nitrogen while raising the temperature. When the temperature of the soaking part reached 200 degrees, nitrogen was switched to hydrogen, hydrogen was blown into the quartz tube at a rate of 0.5 l / min, and the temperature was continued. When the temperature of the soaking part reached 800 ° C., the temperature increase was stopped, and then the temperature was maintained at 800 ° C. for 2 hours while flowing hydrogen into the quartz tube.
[0024]
Subsequently, the hydrogen was switched to argon, the blowing rate was 1.0 l / min, and the temperature was maintained at 800 ° C. for 2 hours.
[0025]
After allowing to cool, the obtained rhodium powder was analyzed to determine the quality of Na, chlorine and oxygen. As a result, it was found that Na: 0.9 ppm, chlorine: 560 ppm, and oxygen: 280 ppm were greatly reduced. The fired product was not sintered and was in a good state.
[0026]
(Comparative Example 1)
Using a commercially available rhodium powder obtained from rhodium hydroxide, the same treatment as in Example 1 was carried out to obtain a fired product.
[0027]
The Na quality in the commercially available rhodium powder was 2780 ppm, and the quality of the fired product was 502 ppm. Although the Na quality is certainly reduced by the heat treatment, it can be said that it is far from being highly purified.
[0028]
(Comparative Example 2)
A fired product was obtained in the same manner as in Comparative Example 1 except that the treatment temperature was 1100 ° C.
[0029]
The Na quality of the fired product was 207 ppm, and the fired product was sintered.
[0030]
(Comparative Example 3)
100 g of the metal powder obtained in Example 1 was filled in a quartz boat, which was inserted into a soaking part of a quartz tube provided in an annular furnace, and purged with nitrogen while raising the temperature. When the temperature of the soaking part reached 200 degrees, nitrogen was switched to hydrogen, hydrogen was blown into the quartz tube at a rate of 0.5 l / min, and the temperature was continued. When the temperature of the soaking part reached 600 ° C., the temperature raising was stopped, and thereafter, the hydrogen was passed through the quartz tube and kept at 600 ° C. for 9 hours.
[0031]
Subsequently, the hydrogen was switched to argon, the blowing rate was 1.0 l / min, and the temperature was maintained at 600 ° C. for 2 hours.
[0032]
After allowing to cool, the obtained rhodium powder was analyzed to determine the quality of Na, chlorine and oxygen. As a result, it was found that Na: 1.0 ppm, chlorine: 1100 ppm, oxygen: 430 ppm, and sufficient reduction effects were not obtained.
[0033]
(Example 4)
The rhodium powder obtained in Comparative Example 3 was used for reprocessing according to the method of Example 2.
[0034]
After allowing to cool, the obtained rhodium powder was analyzed to determine the quality of Na, chlorine and oxygen. As a result, it was found that Na: 0.6 ppm, chlorine: 390 ppm, and oxygen: 160 ppm were greatly reduced. The fired product was not sintered and was in a good dispersion state.
[0035]
【The invention's effect】
According to the method of the present invention, since hydrogen is used as a reducing agent, it is possible to obtain a metal powder with low Na quality, and since this is dry-processed, it is possible to easily obtain rhodium powder of low Na, chlorine and oxygen. It is.

Claims (1)

Hydrogen is blown into a chloride solution containing rhodium to precipitate rhodium ions as a metal powder . The metal powder is heated in a hydrogen atmosphere at 800 to 1000 ° C. for 1 to 4 hours, and then in an inert atmosphere at 800 to 1000 ° C. for 1 hour. A method for producing rhodium powder, which comprises heating for 4 hours.