WO2014158043A1 - Method for recovery of rhenium from nickel-containing superalloys - Google Patents

Abstract

The invention relates to regeneration of waste from refractory nickel superalloys containing rhenium. The method for recovery of components from the waste from nickel-containing superalloys comprises: treating the waste with hydrochloric acid thus transferring nickel and cobalt into solution (I) and producing a solid residue (I); separating the solution (I) produced; treating the solid residue (I) with an oxidizing agent thus transferring rhenium into solution (II); separating solution (II) from insoluble residue (II); and a sorption extraction of rhenium from solution (II). The oxidizing agent is selected from a group of substances, which includes hydrogen peroxide, chlorine and salts of oxygen-containing chlorine acids. Preferably the method is carried out at a hydrochloric acid concentration of 5-7 mole/l, at a ratio of the acid to the waste of (1-40):1 by volume, and a temperature of 70-90ºC. It is also possible to treat the waste with a mixture of hydrochloric acid and sulphuric acid at a hydrochloric acid concentration of 2-7 mole/l and a sulphuric acid concentration of 2-4 mole/l, and at a ratio of the acid mixture to the waste of (1-40):1, and a temperature of 70-90ºC.

Description

 METHOD FOR REGENERATING RHENIUM FROM WASTE OF NICKEL-CONTAINING SUPER ALLOYS The invention relates to the regeneration of secondary metal raw materials, in particular, to the processing of waste heat-resistant nickel superalloys containing rhenium.

 One of the most common types of such materials is waste from multicomponent aviation heat-resistant nickel alloys. As a rule, these alloys contain nickel, cobalt, tungsten, rhenium, tantalum and niobium. Chromium, molybdenum, and aluminum additives are also possible.

 Pyrometallurgical, electrochemical and hydrometallurgical methods can be used to extract valuable components from waste from heat-resistant alloys. Hydrometallurgical processing of waste heat-resistant alloys, based on reagent dissolution, is less energy-consuming and simpler in hardware design.

 A known method for the extraction of rhenium from waste of rhenium-containing superalloys (patent US 8038764, 2011), providing for the impact on flocculent waste highly oxidizing environment and the conversion of rhenium into a volatile oxide. The disadvantages of this method are the relatively low degree of rhenium extraction and the loss of other valuable alloy components.

 There is also known a method for extracting rhenium from wastes of rhenium-containing superalloys (published international application WO 2010/102391), in which rhenium is converted to perrenate form when treated with a mixture of hydrochloric and nitric acids at a temperature of 30-80 ° C. Next, perrenate is separated with the solution from the insoluble precipitate. The disadvantage of this method is the use of nitric acid, which leads to the release of toxic nitrogen oxides. In addition, the presence of nitrate ions complicates the sorption extraction of rhenium from the resulting solution, and the need to neutralize ammonium nitrate eluate leads to the pollution of rhenium acid ammonium with ammonium nitrate.

The closest to the proposed method for the extraction of rhenium from waste heat-resistant alloys is described in patent RU 2412267, 2011. The method includes treating the waste with sulfuric acid at elevated temperature and supplying hydrogen peroxide to a solution of leaching of rhenium, nickel and cobalt and concentration in the insoluble residue of tungsten, niobium and tantalum, separation of the solution from the insoluble residue, extraction of rhenium from the leach solution with secondary aliphatic alcohol, washing the extract and reextracting rhenium with an alkaline solution a thief. Peroxide feed hydrogen is carried out after the main part of nickel and cobalt is transferred into the solution and it is maintained while maintaining the oxidation-reduction potential in the range of 0.50- 0.75 V relative to the saturated silver chloride electrode, and rhenium is extracted, the extract is washed, and rhenium is re-extracted 2-5 steps. In the interaction of metals, including those contained in the waste residue after dissolution of the bulk (15-35% nickel and 10-30% cobalt), hydrogen is precipitated with sulfuric acid. The oxygen escaping during decomposition of hydrogen peroxide added to the waste residue can lead to the formation of explosive explosive gas, which should be attributed to the disadvantages of the process.

 The present invention is aimed at achieving a technical result, which consists in reducing the consumption of an oxidizing agent, in increasing the safety of the method due to the diversity in time and space of operations accompanied by the evolution of hydrogen and oxygen. The proposed method also allows complex use of other valuable components of superalloys.

 Waste nickel-containing superalloys can be generated by grinding and polishing parts with abrasive tools. In this case, the waste is a powder consisting of metal particles and abrasive materials. Before starting the proposed regeneration method, it is desirable to separate such waste from non-metallic components.

 If the waste is relatively large pieces, scraps, shavings, etc., it is advisable to grind it to a powdery state before processing.

 A method for recovering rhenium from waste nickel-containing superalloys involves treating the waste with hydrochloric acid, possibly mixed with sulfuric acid, transferring nickel and cobalt to solution (I), if the latter is present in the superalloy, and obtaining a solid residue (I). Then, the resulting solution (I) is separated off, and the solid residue is treated with (I) an oxidizing agent with rhenium being transferred into solution (II). The oxidizing agent may be hydrogen peroxide, chlorine, salts of perchloric acid, and sulfuric acids (preferably the first two oxidizing agents). The solution (II) is separated from the insoluble residue (I). Rhenium is isolated from solution (I) by sorption on a weakly basic anion exchange resin and subsequent desorption by an alkaline solution, preferably an ammonia solution.

From the eluate after the desorption step, rhenium can be isolated by electrodialysis and / or precipitation, while the eluate can be pre-evaporated. The mother liquors after precipitation and / or electrodialysis can also be sent for sorption purification. Nickel concentrate is precipitated from solution (I), in which a small amount of rhenium may be present, and the remaining liquid phase is sent to sorption extraction of rhenium. The insoluble residue (II) can be treated with an alkaline reagent and tungsten concentrate and solid tantalum can be obtained in solution (III). niobium concentrate.

 Filing one of the predominantly used oxidizing agents, hydrogen peroxide, after transferring the main part of nickel and cobalt to the solution and separating them from the residue, reduces the consumption of hydrogen peroxide by reducing the volume of solution required to dissolve the residue (I). In addition, the separation in time and space of the acid dissolution of nickel and cobalt, accompanied by the evolution of hydrogen, and the extraction of rhenium under the influence of hydrogen peroxide not only improves the safety of the process, but also the absence of tungsten transition at the stage of dissolution of waste in acid, which losses of the latter.

 The use of oxygen-free hydrochloric acid, which does not have oxidizing properties, reduces the likelihood of rhenium entering the solution during dissolution of the initial sections in comparison with the prototype where sulfuric acid is used.

 The supply of hydrogen peroxide while maintaining the redox potential in the range of 0.50-0.75 V with respect to the saturated silver chloride electrode makes it possible to control the redox process in the healing solution, to avoid the supply of excess oxidizing agent, and thereby optimize its consumption. Maintaining the redox potential below 0.5 V leads to a deficiency of the oxidizing agent in the reaction mixture and a decrease in the extraction of rhenium into the solution, and maintaining the potential above 0.75 V leads to an excess of oxidizing agent in the reaction mixture and its increased consumption with almost unchanged extracting rhenium.

 Sorption purification of the mother solutions of precipitation and / or electrodialysis, which also leads to an increase in the capacity of the sorbent and the displacement of impurities at the sorption stage, helps to improve the quality of the obtained marketable rhenium product.

 Examples of the method:

Example 1

Example. To 100 g of powdered nickel-based superalloys containing 1.1% rhenium and 58% nickel, 120 ml of hydrochloric acid with a concentration of 12 mol / L was added and dissolved at 90 ° C for 3 hours. After the completion of the process, the solution decanted, the phases were separated. 20 ml of hydrogen peroxide with a concentration of 38% was added to the residue and the dissolution process was carried out for 2 hours while maintaining oxidation-reduction potential in the range of 0.50 - 0.75 V relative to the saturated silver chloride electrode. Upon completion of dissolution, the phases were separated, and the resulting solution was sent to sorption by weakly basic ion exchanger under dynamic conditions. Rhenium was desorbed by an ammonia solution with a concentration of 8%, while the concentration of rhenium in the eluate was 12 g / L. After evaporation of the solution and its crystallization, 1.0 g of ammonium perrenate in terms of rhenium was obtained. The rhenium recovery rate was 91%.

Example 2

 After dissolving the starting material and separating the solution, as in the previous example, the treatment of the solid residue was carried out using chlorine as an oxidizing agent. To the solid residue (I) was added a solution of gaseous chlorine at a volume ratio of residue (I) to the solution (1: 30) and maintaining the concentration of dissolved chlorine at 6 g / l at a temperature of 22 ° C. The contact time was 3 hours. Further regeneration stages were carried out as in Example 1, using an ammonia solution (6%) as eluent. The concentration of rhenium in the eluate was 12 g / l. 1.05 g of ammonium perrenate was recalculated to rhenium. The degree of extraction was 95.5%.

Example 3

 After the starting material was dissolved and the solution was separated, as in Example 1, the solid residue was treated with a sodium hypochlorite solution under the following conditions: sodium hypochlorite concentration was 5%, contact time 2.5 h, temperature 20 ° C. Further regeneration steps were carried out as in Example 1. The concentration of rhenium in the eluate was 12 g / L. 0.99 g of ammonium perrenate, calculated as rhenium, was isolated. The degree of recovery was 89.9%.

Example 4

Example. To 180 g of powdered nickel-based superalloys containing 0.8% rhenium and 55% nickel, a mixture of hydrochloric and sulfuric acids was added at a concentration of hydrochloric acid of 4 mol / L, and a concentration of sulfuric acid of 3 mol / L. The volumetric ratio of hydrochloric and sulfuric acids was 1: 1, and the ratio by weight of the mixture of acids to the waste of the supersolid was 18: 1. Dissolution was carried out at a temperature of 78-80 ° C. After the dissolution and phase separation process was completed, the solid residue was treated with a sodium chlorate solution under the following conditions: the concentration of sodium chlorate was 6%, the contact time was 3 hours, and the temperature was 20 ° C. Further stages of regeneration were carried out as in Example 1. The concentration of rhenium in the eluate was 10 g / L. 1.3 g of ammonium perrenate in terms of rhenium was isolated. The degree of extraction was 90.6%.

The given examples confirm the achievement of intensification of the process of dissolution of metal waste from heat-resistant nickel alloy containing rhenium. At the same time, harmful gaseous gaps are minimized due to optimization of the technological mode, selected methods and reagents.

 The method according to the invention is relatively simple and can be implemented using standard equipment.

Claims

Claim 1. A method of recovering components from waste nickel-containing superalloys, comprising treating the waste with hydrochloric acid to transfer nickel and cobalt into solution (I) and obtain a solid residue (I), separating the resulting solution (I), treating the solid residue (I) an oxidizing agent with rhenium being transferred into solution (II), separation of the solution (II) from the insoluble residue (II) and sorption extraction of rhenium from solution (II), the oxidizing agent being selected from the group of substances that include hydrogen peroxide, chlorine, oxygen salts chlorine acids.  2. The method according to claim 1, characterized in that the waste is treated at a hydrochloric acid concentration of 5-7 mol / l, with a volume ratio of acid to waste (1-40): 1, and a temperature of 70-90 ° C.  3. The method according to claim 1, characterized in that the waste is treated with a mixture of hydrochloric and sulfuric acids at a concentration of hydrochloric acid of 2-7 mol / l, a concentration of sulfuric acid of 2-4 mol / l and the ratio of the mixture of acids to waste (1 -40): 1 and a temperature of 70-90 ° C.  4. The method according to p. 2 or 3, characterized in that hydrogen peroxide is used as an oxidizing agent with its ratio to the solid residue (I) (1-10): 1 and maintaining the redox potential in the range of 0.50-0.75 V relative to - saturated silver chloride electrode.  5. The method according to p. 2 or 3, characterized in that to the solid residue (I) is added a solution containing gaseous chlorine as an oxidizing agent with a volume ratio of residue (I) to the solution (1: 10 50) and maintaining the concentration of dissolved chlorine 5-7 g / l.  6. The method according to claim 1, characterized in that the sorption of rhenium is carried out by a weakly basic anion exchange resin, and the desorption of rhenium from it with an alkaline solution.  7. The method according to claim 6, characterized in that an ammonia solution is used as the alkaline solution.  8. The method according to claim 6, characterized in that rhenium is isolated from the eluate by electrodialysis and / or precipitation.  9. The method according to p. 8, characterized in that the eluate is pre-evaporated.  10. The method according to p. 1, characterized in that nickel concentrate is precipitated from solution (I), and the remaining liquid phase is sent to sorption extraction of rhenium together with solution (II).