KR101098483B1 - Recovery of rutenium from rutenium containing waste scraps - Google Patents

Abstract

The present invention comprises the steps of adding an alkali (alkali) to the waste scrap containing ruthenium (Ru) and other metal components, heated to above the melting point temperature of the alkali and then dissolved in water and filtered to obtain an alkali molten salt leaching solution; Neutralizing the hydrogen ion concentration of the alkali molten salt leachate using an acid and filtering to obtain a ruthenium hydrate precipitate powder; Heat treating the ruthenium hydrate precipitated powder at 300 to 1000 ° C. to obtain a ruthenium dioxide powder; It relates to a ruthenium recovery method comprising the step of heat-treating the ruthenium dioxide powder in a hydrogen atmosphere at 800 to 1600 ℃ to obtain a ruthenium metal (metal).

Alkali molten salt leaching, precipitation and reduction process using the method of the present invention, it is possible to recover ruthenium in the metal state from the ruthenium-containing waste scrap generated in the industry as a rare platinum group.

Ruthenium, Scrap Scrap, Alkali Molten Salt Leaching, Ruthenium Dioxide, Precipitation, Reduction

Description

Recovery method of rutenium from rutenium containing waste scraps

The present invention relates to a method for recovering ruthenium from ruthenium-containing waste scrap, and more particularly, adding alkali to waste scrap containing ruthenium and other metals, heating to above the melting point temperature of alkali, and then dissolving in water and filtering. Obtaining an alkali molten salt leachate; Neutralizing the hydrogen ion concentration of the alkali molten salt leachate using an acid and filtering to obtain a ruthenium hydrate precipitate powder; Heat treating the ruthenium hydrate precipitated powder at 300 to 1000 ° C. to obtain a ruthenium dioxide powder; It relates to a ruthenium recovery method comprising the step of heat-treating the ruthenium dioxide powder in a hydrogen atmosphere at 800 to 1600 ℃.

Ruthenium is a chemical element with the symbol Ru, atomic number 44 and a rare transition metal belonging to the Platinum group, produced together from platinum ores, polished silver white metal, hard and brittle. When heated in air or oxygen, it is oxidized to form blue ruthenium dioxide (RuO ₂ ), and some of it is volatilized as ruthenium tetraoxide (RuO ₄ ), extremely stable in acid and insoluble in aqua regia, but with potassium hydroxide Heating a mixture of potassium nitrate corrodes.

The commercial recovery and application of ruthenium began in the 1950s with the technology of extracting ion exchange resins from high-level liquid wastes in the United States in the 1950s. As super-capacity characteristics were developed and demand increased, it separated and refined from platinum mines mainly in resource-holding countries, and developed into mass supply and applied research.

Since the 1990s, interest in platinum group recovery technologies has increased in Germany, the United Kingdom, the United States, and Japan, and commercial processes have been in place to separate and purify ruthenium from platinum ore and secondary waste resources. At present, the platinum group is recovered from scrap commercially in China besides Heraeus, Johnson Matthey, INCO, Japan and Tanaka Metal in Japan. The study of ruthenium recovery in Korea has only been reported in 1998 by the Atomic Energy Research Institute with the ion exchange resin method and from the Korea Institute of Geoscience and Mineral Resources.

Since ruthenium is produced, separated and recovered together with the platinum group elements, it has been limited to some countries where the technology holders own ores. Recently, however, there has been an active movement to recover such metals from secondary sources such as electronic scrap. Ruthenium-containing waste resources exist in various types such as waste sconce, waste paste, and process sludge.

In the present invention, the study was focused on the recovery of ruthenium from the waste resources (waste scrap).

Such waste scrap is incinerated and discharged in the form of incineration ash. In order to recover ruthenium from the incineration ash, it is preferable to selectively leach ruthenium to recover the ruthenium. However, ruthenium metal exhibits poorly soluble properties to acid among the platinum group elements, which makes the recovery process difficult. Ruthenium metals have been reported to dissolve under conditions of supplying chlorine gas under sodium hypochlorite (NaOCl) solution. In the case of ruthenium oxide, the alkali melting method has been studied and applied classically.

Accordingly, the present inventors have made intensive studies to recover ruthenium having a high value added as a rare platinum group from a ruthenium-containing waste scrap incinerator, which is produced industrially, in a metallic state. It was confirmed that the recovery in the metal state can be completed the present invention.

Accordingly, a main object of the present invention is to provide a method for recovering ruthenium in a metal state having high added value from the ruthenium-containing waste scrap which is discarded to the rare platinum group.

According to one aspect of the present invention, the present invention is a step of adding an alkali to the waste scrap containing ruthenium and other metal components, heated to above the melting point temperature of the alkali, dissolved in water and filtered to obtain an alkali molten salt leaching solution ; Neutralizing the hydrogen ion concentration of the alkali molten salt leachate using an acid and filtering to obtain a ruthenium hydrate precipitate powder; Heat treating the ruthenium hydrate precipitated powder at 300 to 1000 ° C. to obtain a ruthenium dioxide powder; It provides a ruthenium recovery method comprising the step of heat-treating the ruthenium dioxide powder in a hydrogen atmosphere at 800 to 1600 ℃.

In the step of obtaining the alkali molten salt leaching solution, the alkali is preferably at least one selected from the group consisting of sodium hydroxide (NaOH), sodium peroxide (Na ₂ O ₂ ), potassium hydroxide (KOH) and potassium nitrate (KNO ₃ ). .

In the step of obtaining the alkali molten salt leachate, the alkali is preferably added in an amount of 100 to 400 parts by weight based on 100 parts by weight of waste scrap.

In the step of obtaining the alkali molten salt leachate, the heating is preferably heated to 350 to 500 ℃.

In the step of obtaining the ruthenium hydrate precipitated powder, the neutralization is preferably such that the hydrogen ion concentration of the alkali molten salt leachate is pH 7-9.

Hereinafter, the step of recovering ruthenium from the ruthenium-containing waste scrap of the present invention will be described in more detail step by step.

The present invention relates to a method for recovering ruthenium, which is a platinum group precious metal, from industrially generated waste scrap, and to a method for recovering ruthenium in a metal state through alkali molten salt leaching, precipitation, and reduction as shown in FIG. 1. will be.

In the present invention, the waste scrap is an industrial waste resource generated in the form of waste sconce, waste paste, process sludge, etc. In the present invention, it may be used as a target material for recovering ruthenium, which is a rare transition metal belonging to the platinum group. Such waste scraps are generally incinerated and discharged in the form of incineration ash. If the waste scraps are not incinerated, it is preferable to remove unnecessary combustible components through incineration.

In the present invention, first, the ruthenium is leached from the waste scrap by using an alkali molten salt leaching method, and as the alkali, one or two or more of sodium hydroxide, sodium peroxide, potassium hydroxide and potassium nitrate may be used together. It is preferable to add alkali in 100 to 400 parts by weight based on 100 parts by weight. This means that if too little alkali is used, all ruthenium present in the waste scrap cannot be dissolved in alkali when leaching the alkali molten salt, and if too much alkali is used, some alkali is present as free alkali. It can be rather inefficient because it does not participate in the reaction and exists as a surplus.

Alkali molten salt leaching of the present invention is to dissolve ruthenium from metal components other than ruthenium which do not dissolve in alkali by reacting alkali with waste scrap to dissolve ruthenium in alkali. Thus, in order to dissolve ruthenium in alkali It is preferable to liquefy alkali. Therefore, it is preferable to liquefy the alkali by heating above the melting point temperature of each alkali as described above. If the temperature is increased more than necessary, the solubility of ruthenium in alkali may be lowered and the leaching rate may be reduced.

As above, the alkali is added and heated to react ruthenium and alkali contained in the waste scrap, and then dissolved in water, and the liquid ruthenium solution and the solid impurities must be separated. Any method that can separate the liquid and solid impurities may be used, but it is preferable to use a filtration method.

The ruthenium component must be recovered from the ruthenium dissolving solution (hereinafter, referred to as 'leach liquor') separated by the above method. In the present invention, a method of precipitating ruthenium hydroxide from ruthenium ion to neutral state by adding an acid is used. . At this time, any acid capable of neutralizing the leachate may be used as the acid, and preferably nitric acid, sulfuric acid, and formic acid may be used. In addition, when neutralizing the leachate using the acid, it is preferable to adjust the hydrogen ion concentration to pH 7 to pH 9.

Neutralizing the leachate converts the ruthenium component into a precipitate of hydroxide, wherein it is preferable to use a filtration method to separate the produced ruthenium precipitate and the liquid alkali.

In the present invention, the precipitate is heat-treated at 300 to 1000 ° C. to convert to ruthenium dioxide, thereby obtaining ruthenium dioxide powder. The ruthenium dioxide powder is heat-treated at 800 to 1600 ° C. in a hydrogen atmosphere to finally reduce ruthenium to a metal state. It can be recovered as a powder of.

Hereinafter, the present invention will be described in more detail with reference to Examples. These embodiments are only for illustrating the present invention, and thus the scope of the present invention is not construed as being limited by these embodiments.

Example 1 Alkali Molten Salt Leaching According to Alkali Concentration

Ruthenium-containing waste scrap used in the embodiment of the present invention was obtained from S as a waste plasma display panel (PDP) electrode paint incinerator, and a solid mill and a rotating ultra-fine atomizer for vibrating solid mass samples at high speed. It was pulverized by using the apparatus and sieved and then adjusted to a size of 250 mesh or less to prepare an incineration ash powder (hereinafter referred to as incineration ash).

To 10 g of the incineration ash, 1, 5, 10, 20 or 40 g was added in a 1: 1 weight ratio of sodium peroxide and sodium hydroxide or potassium nitrate and sodium hydroxide, and reacted at 500 ° C. for 2 hours.

250 ml of water was added to the incineration ash and the alkali molten salt reactant to dissolve the reaction and filtered to obtain a leach residue (solid that did not pass the filter) and a leachate (liquid passed through the filter).

Example 2 Alkali Molten Salt Leaching with Different Leaching Temperatures

20 g was added to 10 g of the incineration ash in a 1: 1 weight ratio of sodium peroxide and sodium hydroxide, and reacted at 400, 500, 600 or 700 ° C. for 2 hours.

250 ml of water was added to the incineration ash and the alkali molten salt reactant to dissolve the reactant and to obtain a leach residue and a leach liquid.

Experimental Example 1. Component Analysis of Ruthenium-Containing Waste Scrap Samples

It was measured by SQX (Semi-quantitative X-ray) to identify the components of the incineration ash used in the above example, X-ray diffraction (XRD) for qualitative analysis.

TABLE 1

Ingredient result unit Det.limit El. line Intensity w / o normal Na ₂ O 0.0000 mass% 0.0086 Na-KA 0.2298 0.0000 MgO 0.0084 mass% 0.0041 Mg-KA 0.0791 0.0080 Al ₂ O ₃ 0.7336 mass% 0.0020 Al-KA 15.6094 0.6977 SiO ₂ 30.2310 mass% 0.0061 Si-KA 552.7943 28.7494 P ₂ O ₅ 0.0697 mass% 0.0012 P-KA 2.6992 0.0663 Cl 0.1388 mass% 0.0060 Cl-ka 1.2578 0.1320 K ₂ O 0.0072 mass% 0.0018 K-KA 0.1872 0.0068 CaO 0.0413 mass% 0.0024 Ca-KA 0.8640 0.0393 TiO ₂ 0.0824 mass% 0.0055 Ti-KA 0.3699 0.0783 Fe ₂ O ₃ 0.3189 mass% 0.0020 Fe-ka 9.3621 0.3032 Co ₂ O ₃ 0.5176 mass% 0.0017 Co-ka 21.0440 0.4923 NiO 0.0241 mass% 0.0013 Ni-KA 1.5272 0.0230 CuO 0.0225 mass% 0.0011 Cu-KA 1.8272 0.0214 ZnO 0.2861 mass% 0.0010 Zn-KA 30.7341 0.2721 ZrO ₂ 0.2939 mass% 0.0012 Zr-KA 35.3402 0.2795 RuO ₂ 15.1712 mass% 0.0066 Ru-ka 47.4239 14.4277 Rh ₂ O ₃ 0.0000 mass% 0.0065 Rh-KA 0.0621 0.0000 Ag ₂ O 0.5818 mass% 0.0138 Ag-KA 4.6747 0.5533 BaO 0.9687 mass% 0.0119 Ba-LA 1.9086 0.9212 HgO 0.0227 mass% 0.0028 Hg-LA 1.2039 0.0216 PbO 49.6934 mass% 0.0190 Pb-LA 71.3880 47.2581 Bi ₂ O ₃ 0.7868 mass% 0.0045 Bi-la 43.5070 0.7483

As a result of SQX measurement of incineration ash, as shown in Table 1, ruthenium was found to contain 14.43%, and lead (Pb) was the highest as 47.26%, followed by silicon (Si). In addition, it was confirmed that barium (Ba), bismuth (Bi), silver (Ag), zinc (Zn), cobalt (Co), iron (Fe).

As a result of XRD measurement of the incineration ash, as shown in FIG. 2, many peaks were identified. As a result of analyzing the main peaks, ruthenium was present in a mixed state of Ru, Pb ₂ (Ru 1.69, Pb 0.31), and RuO ₂ . In the case of Si, which was found to be the second largest as a result of SQX measurement, it was difficult to discriminate by XRD measurement.

Experimental Example 2 Ruthenium Concentration of Leachate

The concentration of ruthenium contained in the leachate obtained in Examples 1 to 2 was measured by using an atomic absorption spectrophotometer (AAS, Varian), and the ruthenium concentrations before and after alkali molten salt leaching were compared to FIG. The leaching rate is shown.

As a result, as shown in Fig. 3, when the total amount of sodium peroxide and sodium hydroxide or potassium nitrate and sodium hydroxide was 200% of the incineration ash, the leaching rate of ruthenium was found to be 75%, which was the highest. Above 200%, no further increase in ruthenium leaching rate was observed. In addition, the leaching rate was found to decrease as the leaching temperature is higher than 400 ℃.

Therefore, this means that the amount of alkali affects the leaching reaction up to 200% of the nitric acid leaching residue, so it is best to use the amount of alkali to 200% of the waste scrap during alkali molten salt leaching. In the case of adding alkali, it means that some alkali is present as free alkali and thus does not participate in the leaching reaction and is present in surplus, which is rather inefficient.

In addition, the leaching temperature does not need to be increased to be 400 ° C. or higher, and if the heat treatment is performed at a temperature higher than that, the leaching reaction may be disturbed or the alkali may react with impurities other than ruthenium.

Example 3. Precipitation

5% (v / v) nitric acid solution was added to 315 ml of the leaching solution of Examples 1 to 2 to adjust the hydrogen ion concentration to pH7 or pH9, and then filtered through a filter paper (No.5C) to precipitate ruthenium hydrate. Obtained. The obtained hydrate was heat-treated at 600 ° C. for 2 hours to obtain 2.63 g of ruthenium dioxide (RuO ₂ ) powder.

Experimental Example 3. Characterization of Ruthenium Dioxide Powder

Particle size distribution, TG-DTA, BET and SEM image observation methods were used to evaluate the properties of the ruthenium dioxide powder obtained in Example 3.

As a result, as shown in Figure 4, the average particle diameter of the ruthenium dioxide powder is about 200 to 400nm, it was confirmed that the particle size is smaller than the case of 9 when the pH is 7.

This means that the final neutralizing pH affects the particle size of the ruthenium dioxide powder.

In addition, as shown in Figure 5, the weight loss of ruthenium dioxide was generated about 16% in the case of pH7, 22% occurred in the case of pH9. The specific surface area results in the case of pH7 and 118m ² / g, the case of pH 9 was 75.9m ² / g.

Example 4. Reduction

2.63 g of the ruthenium dioxide powder obtained in Example 3 was reduced to 1400 ° C. in a hydrogen atmosphere for 1 hour to obtain 1.98 g of ruthenium metal.

Experimental Example 4. Characterization of Ruthenium Metal

The SEM image observation method was used to evaluate the properties of the ruthenium metal obtained in Example 4, and ICP (Perkin Elmer) analysis was performed to confirm the ruthenium content of the ruthenium metal.

As a result, as shown in FIG. 6, the particle shape of ruthenium metal was found to have a particle size of about 0.5 to 1 μm and a small surface area compared to ruthenium dioxide, and the ruthenium content was 67.5%. .

As described above, the alkali molten salt leaching, precipitation, and reduction process using the method of the present invention enables the recovery of ruthenium, which exhibits high added value as a rare platinum group, from the industrially generated ruthenium-containing waste scrap in a metallic state. do.

1 is a flow chart showing the steps for a method for recovering ruthenium from ruthenium-containing waste scrap of the present invention.

Figure 2 is a graph showing the XRD analysis of the waste PDP electrode paint incinerator used in the embodiment.

3 is a graph showing the leaching rate of ruthenium according to the change of the amount of alkali addition and the change of heat treatment temperature during alkali molten salt leaching.

Figure 4 is a graph showing the particle size distribution of the ruthenium dioxide powder obtained after the precipitation process and a table thereof.

Figure 5 is a graph showing the results of TG-DTA and BET analysis of the ruthenium dioxide powder obtained after the precipitation process and a table thereof.

Figure 6 is a SEM photograph of the ruthenium metal powder obtained after the reduction process of ruthenium dioxide.

Claims (5)

a) adding alkali to waste scrap containing ruthenium and other metals, heating to above the melting point temperature of the alkali, dissolving in water and filtering to obtain an alkali molten salt leachate; b) neutralizing the hydrogen ion concentration of the alkali molten salt leachate using an acid and filtering to obtain a ruthenium hydrate precipitate powder; c) heat treating the ruthenium hydrate precipitated powder at 300 to 1000 ° C. to obtain a ruthenium dioxide powder; d) a ruthenium recovery method comprising the step of heat-treating the ruthenium dioxide powder in a hydrogen atmosphere at 800 to 1600 ℃. The method of claim 1, wherein the alkali of step a) is at least one selected from the group consisting of sodium hydroxide, sodium peroxide, potassium hydroxide and potassium nitrate. The ruthenium recovery method of claim 1, wherein the alkali is added in an amount of 100 to 400 parts by weight based on 100 parts by weight of the waste scrap. The method of claim 1, wherein the heating in step a) is ruthenium recovery method characterized in that the heating to 350 to 500 ℃. The ruthenium recovery method of claim 1, wherein the neutralizing in step b) sets the hydrogen ion concentration of the alkali molten salt leachate to pH 7-9.

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