Process for efficiently enriching and recovering noble metals of platinum and palladium by solvent extraction

Abstract

The present invention relates to a process for efficiently enriching and recovering noble metals of platinum and palladium based on solvent extraction, wherein isoamyl alcohol is used as extracting agent and 2-methoxyphenyl thiourea is used as extraction-assisted complexing agent. 2-methoxy-phenyl thiourea is added to aqueous phase to react with platinum and palladium, and isoamyl alcohol is used as extracting agent to extract the organic phase, thus realizing the purpose of separating and extracting noble metals from base metals while enriching noble metals of platinum and palladium. The present invention, which can not only realize the separation of noble metals and base metals, but also enhance the enrichment and recovery ratios of noble metals of platinum and palladium, with low cost reagents, small influence on the environment and simple technical process, thus is a new and efficient extraction and enrichment system for noble metals.

Claims

1. A process for efficiently enriching and recovering noble metals of platinum and palladium based on solvent extraction, characterized in that: using isoamyl alcohol as extracting agent and 2-methoxyphenyl thiourea as extraction-assisted complexing agent to perform enrichment and extraction of a feed liquid containing noble metals of platinum and palladium, wherein the process comprises the following operation steps of: (1) adding 2-methoxyphenyl thiourea-hydrochloric acid solution to the feed liquid containing noble metals of platinum and palladium, adjusting the acidity of the feed liquid, so that H.sup.+ concentration is in the range of 3-5 mol/L to form an original solution of aqueous phase, shaking the original solution and standing the original solution of aqueous phase; the original solution of aqueous phase containing platinum and palladium with a concentration of 0.01-5 mg/L; (2) taking isoamyl alcohol as an organic phase; (3) adding the organic phase and the original solution of aqueous phase in a volume ratio of 1:1 to 1:2.5 to a separatory funnel, shaking for 1-5 minutes, then standing for liquid separation, to obtain raffinate and organic phase after the liquid separation, subjecting the organic phase after the liquid separation to stripping back extraction, and performing liquid separation again to obtain a stripping solution, thereby completing the enrichment and extraction of the noble metals.

2. The process for efficiently enriching and recovering noble metals of platinum and palladium based on solvent extraction according to claim 1, wherein the extraction-assisted complexing agent of 2-methoxyphenyl thiourea-hydrochloric acid solution has a HCl concentration of 2.5-6 mol/L, wherein 2-methoxyphenyl thiourea has a mass percent of 0.01% to 0.5%.

3. The process for efficiently enriching and recovering noble metals of platinum and palladium based on solvent extraction according to claim 1, wherein the volume ratio of the added 2-methoxyphenyl thiourea-hydrochloric acid solution and the resulting original solution of aqueous phase is 1:2 to 1:5.

Description

BEST MODE FOR CARRYING THE EMBODIMENTS

(1) The present invention will be further described with reference to the following specific examples.

Example 1

(2) 1. Working fluid with a concentration of 25 mg/L of each of platinum and palladium was prepared, respectively, and working fluid with a concentration of 400 mg/L of each of nickel, copper, iron, aluminium and manganese was prepared, respectively.

(3) 2-methoxyphenyl thiourea was dissolved with a HCl solution of 2.5 mol/L in a water bath at constant temperature of 35 C. with magnetic stirring, and the mass percent of 2-methoxyphenyl thiourea was 0.05%, so as to obtain a 2-methoxy phenyl thiourea-hydrochloric acid solution of 0.05%. 2. Preparation of original solution of aqueous phase:

(4) In the experiment, 25 ml of aqueous phase was used in each group of extraction experiment, and one group of experiment as an example was shown below:

(5) 1 ml of previously prepared working fluid of each of platinum, palladium, nickel, copper, iron, aluminum, manganese and 10 ml of 0.05% of 2-methoxyphenyl thiourea-hydrochloric acid solution were taken by pipettes, then the acidity ([H.sup.+]) was adjusted to 3 mol/L, to obtain 25 ml of original solution of aqueous phase, followed by shaking before use. The contents of each noble or base metal in the original solution of aqueous phase are shown in Table 1:

(6) TABLE-US-00001 TABLE 1 plat- palla- alumi- man- metal inum dium nickel copper iron num ganese concen- 1 1 16 16 16 16 16 tration mg/L 3. Solvent extraction:

(7) 25 ml of prepared original solution of aqueous phase and 15 ml of isoamylalcohol organic phase were poured into a separating funnel of 50 ml at room temperature, then the funnel was placed on speed adjustable shaker to perform extraction reaction for 4 minutes. After the completion of the extraction, it was left standing for liquid separation to obtain raffinate, and the organic phase remained in the separating funnel. 4. Stripping back extraction:

(8) A thiourea aqueous solution with 2% of mass percent concentration was prepared, 20 ml of the solution was taken by using pipette and poured into the separating funnel after the liquid separation of step 3, to perform stripping back extraction experiment with the organic phase therein with shaking time of 5 minutes. After the completion of the stripping back extraction, liquid separation was performed to obtain stripping solution and an organic phase after the stripping back extraction. The organic phase after the stripping back extraction may continue to be used for extraction in step 3 for repeated use. 5. Analysis of experiment results:

(9) After the completion of extraction and stripping back extraction experiments, the raffinate and the stripping solution were subjected to ICP test. It can be obtained through data analysis, the present system had a remarkable effect of enrichment and extraction of noble metals, the extraction rates of platinum and palladium were above 99% and 99.2%, respectively, the stripping rate was close to 100%. The system had no extraction effect on base metals with extraction rate of 0.

Example 2

(10) 1. Working fluid with a concentration of 50 mg/L of each of platinum and palladium was prepared, respectively, and working fluid with a concentration of 1000 mg/L of each of nickel, copper, iron, aluminum and manganese was prepared, respectively.

(11) 2-methoxyphenyl thiourea was dissolved with a HCl solution of 6 mol/L in a water bath at constant temperature of 40 C. with magnetic stirring, and the mass percent of 2-methoxyphenyl thiourea was 0.2%, so as to obtain a 2-methoxy phenyl thiourea-hydrochloric acid solution of 0.2%. 2. Preparation of original solution of aqueous phase:

(12) In the experiment, 25 ml of aqueous phase was used in each group of extraction experiment, and one group of experiment as an example was shown below:

(13) 1 ml of previously prepared working fluid of each of platinum, palladium, nickel, copper, iron, aluminum, manganese and 10 ml of 0.2% of 2-methoxyphenyl thiourea-hydrochloric acid solution were taken by pipettes, then the acidity ([H.sup.+]) was adjusted to 4 mol/L, to obtain 25 ml of original solution of aqueous phase, followed by shaking before use. The contents of each noble or base metal in the original solution of aqueous phase are shown in Table 2:

(14) TABLE-US-00002 TABLE 2 plati- palla- alumi- man- metal num dium nickel copper iron num ganese concen- 2 2 40 40 40 40 40 tration mg/L 3. Solvent extraction:

(15) 25 ml of prepared original solution of aqueous phase and 20 ml of isoamylalcohol organic phase were poured into a separating funnel of 50 ml at room temperature, then the funnel was placed on speed adjustable shaker to perform extraction reaction for 3 minutes. After the completion of the extraction, it was left standing for liquid separation to obtain raffinate, and the organic phase remained in the separating funnel. 4. Stripping back extraction:

(16) A thiourea aqueous solution with 2% of mass percent concentration was prepared, 20 ml of the solution was taken by using pipette and poured into the separating funnel after the liquid separation of step 3, to perform stripping back extraction experiment with the organic phase therein with shaking time of 5 minutes. After the completion of the stripping back extraction, liquid separation was performed to obtain stripping solution and an organic phase after the stripping back extraction. The organic phase after the stripping back extraction may continue to be used for extraction in step 3 for repeated use. 5. Analysis of experiment results:

(17) After the completion of extraction and stripping back extraction experiments, the raffinate and the stripping solution were subjected to ICP test. It can be obtained through data analysis, the present system had a remarkable effect of enrichment and extraction of noble metals, the extraction rates of platinum and palladium were above 99.5%, respectively, the stripping rate was close to 100%. The system had no extraction effect on base metals with extraction rate of 0.

Example 3

(18) 1. Working fluid with a concentration of 50 mg/L of each of platinum and palladium was prepared, respectively, and working fluid with a concentration of 1000 mg/L of each of nickel, copper, iron, aluminum and manganese was prepared, respectively.

(19) 2-methoxyphenyl thiourea was dissolved with a HCl solution of 6 mol/L in a water bath at constant temperature of 50 C. with magnetic stirring, and the mass percent of 2-methoxyphenyl thiourea was 0.5%, so as to obtain a 2-methoxy phenyl thiourea-hydrochloric acid solution of 0.5%. 2. Preparation of original solution of aqueous phase:

(20) In the experiment, 25 ml of aqueous phase was used in each group of extraction experiment, and one group of experiment as an example was shown below:

(21) 1 ml of previously prepared working fluid of each of platinum, palladium, nickel, copper, iron, aluminum, manganese and 10 ml of 0.5% of 2-methoxyphenyl thiourea-hydrochloric acid solution were taken by pipettes, then the acidity ([H.sup.+]) was adjusted to 4 mol/L, to obtain 25 ml of original solution of aqueous phase, followed by shaking before use. The contents of each noble or base metal in the original solution of aqueous phase are shown in Table 3:

(22) TABLE-US-00003 TABLE 3 plati- palla- alumi- man- metal num dium nickel copper iron num ganese concen- 2 2 40 40 40 40 40 tration mg/L 3. Solvent extraction:

(23) 25 ml of prepared original solution of aqueous phase and 25 ml of isoamylalcohol organic phase were poured into a separating funnel of 50 ml at room temperature, then the funnel was placed on speed adjustable shaker to perform extraction reaction for 2 minutes. After the completion of the extraction, it was left standing for liquid separation to obtain raffinate, and the organic phase remained in the separating funnel. 4. Stripping back extraction:

(24) A thiourea aqueous solution with 3% of mass percent concentration was prepared, 20 ml of the solution was taken by using pipette and poured into the separating funnel after the liquid separation of step 3, to perform stripping back extraction experiment with the organic phase therein with shaking time of 5 minutes. After the completion of the stripping back extraction, liquid separation was performed to obtain stripping solution and an organic phase after the stripping back extraction. The organic phase after the stripping back extraction may continue to be used for extraction in step 3 for repeated use. 5. Analysis of experiment results:

(25) After the completion of extraction and stripping back extraction experiments, the raffinate and the stripping solution were subjected to ICP test. It can be obtained through data analysis, the present system had a remarkable effect of enrichment and extraction of noble metals, the extraction rates of platinum and palladium were above 99.9%, respectively, the stripping rate was close to 100%. The system had no extraction effect on base metals with extraction rate of 0.