Method of complex reworking of decontaminated platinum-rhenium catalysts

FIELD: extraction of platinum and rhenium from decontaminated used platinum-rhenium catalysts; reworking of secondary raw materials of petrochemical industry.

SUBSTANCE: proposed method includes high-temperature oxidizing roasting at temperature of 1200-1300°C, wet trapping of rhenium by alkaline solution, leaching-out of cinder in hydrochloric acid solution at concentration of 100-150 g/dm3 in presence of oxidizing agent for setting the oxidizing-reducing potential of platinum electrode in pulp relative to saturated silver-chloride electrode equal to 850-1000 mV. Used as oxidizing agent is sodium hypochlorite or elementary chlorine or hydrogen peroxide.

EFFECT: enhanced efficiency of process.

1 tbl, 13 ex

 

The invention relates to the field of metallurgy of non-ferrous and noble metals, in particular to methods for extracting platinum group metals and rhenium from deactivated (exhaust) platinum-rhenium catalysts, and can be used in the processing of secondary raw materials.

The known method (patent RF №2103395) extraction of platinum from spent catalysts consisting in leaching of the catalyst at a temperature 95-103°With a mixture of hydrochloric acid, hydrogen peroxide and dimethylformamide at a content in the mixture of hydrochloric acid 4-7 mol/DM3, hydrogen peroxide 1-4 mol/DM3, dimethylformamide 0.5 to 3 mol/DM3and subsequent recovery of platinum from the solution obtained at pH 3-4 and the temperature of 90-105°products of hydrolytic cleavage of dimethylformamide. The result is a concentrate of platinum. Extraction of platinum in concentrate is 98.3-98,5%. The solution after recovery regenerate and return to leaching (RF patent No. 2103395).

The disadvantage of this method is the lack of stabilizing oxidation firing, which leads to the fact that part of the alumina bases contained in the catalyst in the form of γ-Al2About3goes into solution. Solutions containing aluminum, have a gel-like consistency. This significantly reduces the speed of the filter is AI pulp after leaching and accordingly, the efficiency of the process and prevents reuse of the solution. The resulting gels are not allow to carry out washing of the precipitate, obtained by leaching of the catalyst in hydrochloric acid solution, resulting in partially platinum remains in the insoluble residue, which reduces the extraction of platinum in the finished product. On subsequent operations deposition of platinum from hydrochloric acid solution possible contamination of platinum concentrate aluminum also due to the inability to provide a quality cleaning concentrate because of the presence in solution of a gel-like aluminum compounds and, consequently, reduced quality of platinum concentrate.

Another disadvantage of the known method is that the technology is not provided for the extraction of rhenium in a separate product, which reduces the complexity of the use of raw materials.

Closest to the proposed method on a set of attributes and the achieved result is a method of extraction of rhenium from aluminium oxide-platinum catalysts (Thematic review. The extraction of valuable metals from used heterogeneous catalysts, Tsniiteneftehim, M., 1988, s, 3rd para.). In this method, the catalyst is subjected to oxidizing roasting at 300 to 500°C. When this temperature is burning carbon. Obojeni the catalyst leached 5M hcl (nitric) acid or Aqua Regia at temperatures 20-90° C. Allocation of precious metals from solution are realized by means of ion exchange.

The disadvantage of this method is the lack of a complex processing of raw materials, because there is no description of the extraction of rhenium catalyst. The firing temperature of the catalysts listed in the known method, insufficient for distillation of rhenium, and a full translation γ-Al2About3in α-Al2O3resulting in part of aluminum goes into the platinum solution. As mentioned earlier (section 2.1.), this leads to reduced filtration rate of the slurry, removing the platinum in the finished product and poor quality of finished products.

The challenge aimed generated the invention is to improve the efficiency of the recycling process of the deactivated catalysts.

The technical result from the use of the invention is that by increasing the temperature of the firing is complete distillation of rhenium from catalysts and stabilization of alumina bases catalyst (conversion γ-Al2About3in α-Al2About3insoluble in acids), which leads to increased filtration rate of the slurry during subsequent leaching of the calcine and, accordingly, to improve the performance of the process. The combination of operations oxidation is beige and hydrochloric acid leaching allows to increase the complexity of processing and to extract from latinoreview catalysts in selective concentrates as rhenium, and platinum, and the conditions of hydrochloric acid leaching of the calcine allow to obtain high recovery of platinum in hydrochloric acid solution and, respectively, in the finished product.

The invention consists in that in the method for integrated processing of deactivated platinum-rhenium catalysts, including oxidative roasting and leaching of calcine solution of hydrochloric acid in the presence of the oxidant according to the invention, the firing is conducted at a temperature of 1200-1300°With Stripping and wet recovery of rhenium alkaline solution, and leaching of calcine are in the hydrochloric acid concentration of 100-150 g/DM3in the presence of an oxidant to establish the oxidation-reduction potential (ORP) of the platinum electrode in the pulp against saturated silver chloride, equal 850-1000 mV with translation of platinum in the solution. As the oxidant used sodium hypochlorite solution, elemental chlorine or hydrogen peroxide.

In the process of oxidative roasting of the deactivated catalyst at a temperature of 1200-1300°there is a stabilization of alumina basis of the catalyst, which consists in translating soluble in acids, and poor filtering slurries γ-modification of Al2About3in α-modification of Al2About3that acid is not soluble and fully OST the fast leaching of calcine in the insoluble residue. In addition to stabilization of alumina fundamentals of catalysts in the oxidative calcination, oxidation of the rhenium contained in the catalysts, with the formation of volatile oxides which are removed from the gas phase of the kiln, proceed in the absorption system and are caught in it alkaline solutions. From alkaline solutions of rhenium is extracted by known methods of obtaining rhenium concentrate.

In the process of leaching of the calcine in hydrochloric acid solution with a concentration of 100-150 g/DM3in the presence of an oxidising agent, which is injected into the slurry before the establishment of the oxidation-reduction potential (ORP) of the platinum electrode in the pulp against saturated silver chloride, equal 850-1000 mV, the oxidation of platinum and its dissolution. Selected parameters of the leaching process, provide complete oxidation of platinum and its translation in hydrochloric acid solution. Obtained in the leaching of hydrochloric acid platinochloride solution is supplied to the operation of extracting platinum from it to obtain the corresponding concentrate. Removing platinum from solution is performed by known methods. The solution after the extraction of platinum and doreplace hydrochloric acid can be reused in the operation of the leaching of the calcine.

Thus, recycling of the catalyst p is the present method allows to obtain selective platinum and rhenium concentrates with high extraction of data elements into finished products and increase the efficiency of the process due to the stabilization of alumina basis.

The lower limit of the firing temperature is due to the fact that in the implementation process below 1200°is incomplete stabilization of alumina, that is, when the subsequent acid leaching of calcine aluminium part will go into solution. Solutions containing aluminum, have a gel-like consistency, which significantly reduces the filtration rate of the slurry after leaching and, accordingly, the productivity of the process. The resulting gels are not allow to carry out washing of the precipitate, obtained by leaching the calcine the catalyst in hydrochloric acid solution, resulting in partially platinum remains in the insoluble residue, which reduces its extraction into the solution and, respectively, in the finished product.

The upper temperature limit is due to the fact that with increasing temperature over 1300°With no further stabilization does not occur, but unproductive spent fuel and faster out of the furnace lining.

The leaching in hydrochloric acid concentration below 100 g/l leads to incomplete leaching of platinum and reduce its extraction into the solution.

Increasing acid concentration above 150 g/l did not increase the extraction of platinum, but it leads to unproductive consumption of the reagent.

The decrease in the redox potential of the slurry below +850 mV also riodic to incomplete oxidation of platinum and reduction of its extract in hydrochloric acid solution, and finished products.

Increasing the redox potential of the slurry above 1000 mV to unproductive consumption of the oxidant at a constant rate of extraction of platinum in solution.

According to the invention, the criterion of "inventive step" is proved as follows. The known method (Bonucei J.A., P.D. Parker Recovery of PGM from automobile catalytic converters//Precious Metals: Mining, Extr., and Process. Proc. Int. Symp. AIME Annu. The Meet. - Los Angeles, Calif., Febr. 27-29, 1984. Warrendale, Pa, 1984. - P.463-481), which has a characteristic similar to that claimed, namely, the firing of the original catalysts at high temperature (1500°). However, in the known object, the firing is carried out without a supply of oxidant and is intended only for the stabilization of the alumina base. In the proposed method through the use of an oxidant (oxygen) this feature has two functions: stabilization of the alumina substrate and the Stripping of the rhenium from the catalyst that enables the extraction of rhenium into marketable products. Therefore achieved a new effect, which could not be achieved in a known way. This demonstrates the compliance of the proposed facility to the criterion of "inventive step".

The method is as follows.

The original catalysts calcined in a tubular or shaft furnace at a temperature of 1250-1300°in the presence of air. The gases are directed into the gas purification system, where the absorption of rhenium alkaline solution. From the obtained is rastvorov by known methods to produce the deposition of rhenium. Then the candle with the preliminary grinding or without it leached in hydrochloric acid concentration of 100-150 g/l with a ratio of solid to liquid = 1:5. To the pulp add the oxidant: sodium hypochlorite, or hydrogen peroxide, or blow the pulp with gaseous chlorine to establish ORP platinum electrode in the pulp, equal 850-1000 mV relative to a saturated silver chloride electrode. The slurry is stirred after reaching the specified AFP within 30-60 minutes, then filtered. The cake is washed with water and sent for pyrometallurgical processing in conjunction with the primary sulphide copper-Nickel raw material, a solution for the deposition of platinum by known methods (for example, recovery of hydrazine hydrate or cementation of metal powders).

The following are specific examples of the method.

Example 1. Platinum-rhenium reforming catalyst CU-110 containing, %: platinum - 0,32; rhenium - 0,32; aluminium oxide - 90,87; silica - 0,73, in the amount of 100 g was burned in a laboratory furnace at a temperature of 1250°C for 1 hour. During firing continuously pull air into the working space of the furnace. In the candle after burning was determined by the content of rhenium. After that, the calcine the catalyst was videlacele in a glass beaker with a mechanical stirrer 0.5 DM3hydrochloric acid is concentratie 125 g/DM 3. After heating the slurry to a temperature of 100°C glass was applied to the solution of sodium hypochlorite to establish ORP platinum electrode in the pulp against saturated silver chloride, 900 mV. After that, the slurry was stirred for 1 hour and filtered. To measure the filtration rate of the slurry. In the solution, and the cake was determined by the content of platinum and aluminum.

In the experiment under these conditions, the extraction of rhenium in the gas phase was 99,93%, platinum in hydrochloric acid solution of 99.3%, aluminum in hydrochloric acid solution of 0.12%, and the filtration rate of the slurry 120 DM3/m2including These parameters are optimal, they allow for carrying out the process with high efficiency.

Examples 2-5.

The method is carried out as described in example 1, the difference is that the firing temperature is taken on the boundary limits: 1200°With (example 2) and 1300° (example 3).

In both cases the best results.

Example 4.

The method is carried out as described in example 1, the difference is that the firing temperature is taken below the cutoff limit - 1180°C.

In the result due to incomplete stabilization of the alumina component extracting aluminum in the solution increased to 5,98%, which led to the decrease in filtration rate of the slurry hydrochloric acid leaching of calcine catalysis is tori and accordingly, performance of the process.

Example 5.

The method is carried out as described in example 1, the difference is that the firing temperature is taken above the boundary limit - 1350°C.

Process indicators have not improved compared to the optimal. This means that the temperature rise is unproductive and leads to increased costs for the implementation of the method.

Examples 6, 7.

The method is carried out as described in example 1, the difference is that the concentration of hydrochloric acid in the leaching of the calcine is taken on the boundary limits of 100 g/DM3(example 6) and 150 g/DM3(example 7).

In both cases the best results.

Example 8.

The method is carried out as described in example 1, the difference is that the concentration of hydrochloric acid in the leaching of the calcine is taken below the cutoff limit - 90 g/DM3.

As a result, the extraction of platinum in hydrochloric acid solution and, respectively, into finished products decreased to 93,55%, which led to a decrease in the efficiency of the process.

Example 9.

The method is carried out as described in example 1, the difference is that the concentration of hydrochloric acid in the leaching of the calcine is taken above the boundary limit of 160 g/DM3.

Indicators of process n is improved compared to the optimal. This means that increasing the concentration of hydrochloric acid is unproductive and leads to increased costs for the implementation of the method.

Examples 10, 11.

The method is carried out as described in example 1, the difference is that the redox potential of the platinum electrode in the pulp against saturated silver chloride in the process of leaching of the calcine taken by the boundary limits - 850 mV (example 10) and 1000 mV (example 11).

In both cases the best results.

Example 12.

The method is carried out as described in example 1, the difference is that the redox potential of the platinum electrode in the pulp against saturated silver chloride in the process of leaching the calcine is taken below the cutoff limit is 800 mV.

The result is that platinum is not fully oxidized and its extraction into the solution decreased to 90,45%, respectively, and reduces the efficiency of the process.

Example 13.

The method is carried out as described in example 1, the difference is that the redox potential of the platinum electrode in the pulp against saturated silver chloride in the process of leaching the calcine is taken above the boundary limit - 1050 mV.

Process indicators have not improved compared to the optimal. This means that the increase of the redox potential is unproductive and leads to increased consumption of the oxidant and the cost of implementation is their way.

Thus, the technical result (or efficiency) of the proposed method is as follows:

1. The increasing complexity of processing catalysts: removing selective products such as rhenium and platinum.

2. Achieving high extraction of platinum 98,35 99.3 percent due to the found parameter limits hydrochloric acid leaching.

3. Improving the performance of the process by stabilizing alumina substrate and increasing the filtration rate of the slurry from 15 to 115-145 DM2/m2PM

1. Method for integrated processing of deactivated platinum-rhenium catalysts, including oxidative roasting and leaching of calcine solution of hydrochloric acid in the presence of an oxidising agent, wherein the oxidizing calcination is carried out at a temperature of 1200-1300°With Stripping and wet recovery of rhenium alkaline solution, and leaching of calcine are in the hydrochloric acid concentration of 100-150 g/DM3in the presence of an oxidant to establish the oxidation-reduction potential (ORP) of the platinum electrode in the pulp against saturated silver chloride, equal 850-1000 mV, with translation of platinum in solution.

2. The method according to claim 1, characterized in that as the oxidant used sodium hypochlorite solution, or basic PI is p, or hydrogen peroxide.



 

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2 ex

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3 cl, 3 tbl, 1 ex

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