RU2404849C1 - Method of extracting platinum group metals from solutions - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to extraction of platinum group metals from industrial effluents and can be used for analytical definition of said metals by sorption-atomic-absorption method. Proposed method comprises bringing solution in contact with sorbent. The latter represents dispersion of collagen produced on mixing three parts of formalin with half the part of protein hydrolyzate extracted from leather production wastes, and 7.5 parts of hydrogen sulphide, mix neutralising, filtration, drying and fine-crushing.

EFFECT: high sorption capacity and selectivity, reduced costs.

3 cl, 1 tbl, 3 ex

Description

The invention relates to the recovery of platinum group metals from industrial wastewater. In addition, this invention may find application for the analytical determination of platinum group metals (PGM) by the sorption-atomic absorption method.

The development of methods for the purification of technological wastewater of any production from metals is one of the main tasks of the environmental services of the industry. Effective local water treatment, organized directly at the place of formation of technological wastewater, allows the reuse of treated effluents in technological production. Another aspect of the relevance of the claimed invention is the elimination of losses of PGM with wastewater.

A progressive wastewater treatment method is the adsorption method using activated carbon. Despite the high efficiency of this method, it has several significant drawbacks: the high cost of activated carbons, the absence of activated carbons with a sufficient fraction size, resistant to abrasion during operation.

A known method developed by the company "Ron-Pulenck Industries" (France) [Application N 2294239, France, 1976], intended for the separation of platinum group metals from acidic solutions. To obtain platinum metals by the specified method, acidic solutions are contacted in a flow column with the Duolit A 101D ion-exchange sorbent, after which the sorbent concentrate is burned. In the ash, metals remain in their pure form.

The capacity of the sorbent "Duolit A 101D" in the process is 1-50 mg of metal per 1 g of sorbent.

The main disadvantage of this process is the high consumption of the sorbent to be burned after the end of sorption. The burning of large quantities of matter requires considerable energy, because ashing is carried out in electric furnaces at a temperature of 870 ° C. The reason for the high consumption of the sorbent is the small capacity of the sorbent for the metal, due to the structure of the sorbent molecules. Another disadvantage of this method is the rather high cost of the sorbent itself.

A known method of extracting ions from metals (RF patent No. 2347755), according to which a sorbent based on a modified rubber crumb treated with an ozone-air mixture is used, and crushed tread rubber is used as a rubber crumb. The advantage of the sorbent used in this method is the low cost and availability of the starting component. In addition, a side, but very important from an environmental point of view, problem is solved - the disposal of hazardous waste. The disadvantage of the proposed method is a complex method for producing cateonite and a relatively low sorption capacity.

The closest in technical essence to the claimed method is a method for extracting precious metals from spent catalysts (RF patent 2116362, application. 04/01/1997, publ. 1998, BI 21), including the dissolution of precious metals with an acid-oxidative mixture, sorption of precious metals from solution and their selection from the sorbent concentrate by ashing, moreover, 1-hydroxy-2- (perhydro-1,3,5-dithiazine) -5-yl-ethane is used as the sorbent.

The disadvantage of this method is the low capacity of the sorbent 0.1-0.2 g per 1 g of sorbent, as well as the applicability of the sorbent only to solutions that do not contain other metals other than noble. The reason for the limited applicability of the method is the non-selectivity of these sorbents in relation to noble metals in solutions containing, along with noble mercury and some other metals. Another disadvantage is the rather high cost of the used sorbent, and therefore, the low profitability of the entire technological process.

The problem to which the invention is directed is to eliminate these drawbacks, namely, providing a high sorption capacity of the used sorbent with respect to the platinum group metals, increasing the selectivity of the extraction of precious metal ions, while reducing the cost of the process by reducing the cost and increasing the availability of raw materials .

The problem is solved in that in the method of extracting precious metals from solutions, including sorption them with the subsequent separation of precious metals from the sorbent, the composition consisting of formalin, protein hydrolyzate and hydrogen sulfide is used as the sorbent in the following ratio of components 3: 0.5: 7 ,5.

In addition, the problem is solved in that the protein hydrolyzate is obtained by treating leather wastes in an acid-base environment to obtain a homogeneous mass, and chrome tanned leather wastes are used as leather wastes.

The inventive method is implemented as follows.

Protein hydrolyzate (BG) product obtained as a result of exposure to acids of organic and inorganic origin on the waste of leather production, obtained by a known method / A.A. M., Light Industry, 1971, p. 36 /. We used leather wastes (leather chips of chrome tanning) to obtain PPH. Leather chips (OST 17-245-86) are obtained in the process of finishing leather in the leather and footwear industry at the planing stage. / V.P.Babloyan, N.A. Balberova, I.A. Eremin "Reference book of the tanner (Finishing. Production control)", M., Legprombytizdat, 1987, p.206 /. The output of leather chips with 100 m ^{2 of} skin is 1.2 kg. / I.P. Strakhov, I.S. Shestakova, D.A. Kutsidi "Chemistry and technology of leather and fur", M., Legprombytizdat, 1985, p. 383, 456 /.

A method of obtaining a protein hydrolyzate includes several stages. The process begins with the processing of the waste from the leather industry (leather chips of chrome tanning) with an alkaline salt solution at 20 ° C, ZhK 6 (from the initial weight) for 48 hours with periodic stirring. The alkaline salt bath contains caustic soda - 100 g / l and crystalline sodium sulfate - 322 g / l. After alkaline-salt treatment - washing with a solution of Na ₂ SO ₄ - 322 g / l with a liquid coefficient (LC) of 10 (from the initial weight) for 4 hours, neutralization with a 3% solution of H ₃ BO ₃ at 10 (from the initial weight). The duration of neutralization is 5 hours. Then, dissolution in pure ethylenediamine is carried out at LC 20 (from the initial weight). Duration of dissolution 48 hours, temperature no higher than 30 ° C. BGs are cloudy due to the formation of a finely divided solid phase. Next, we carry out the separation of turbidity by filtration in a centrifuge. The obtained transparent BG is used for the purposes of the present invention.

To obtain the sorbent, 0.5 mass parts of the protein hydrolyzate is added to three mass parts of formalin (CH ₂ O) and 7.5 mass parts of hydrogen sulfide (H ₂ S) are gradually introduced with vigorous stirring. The process proceeds at room temperature. Since the process proceeds with the release of heat, after mixing is completed, the solution is allowed to cool, it is leveled with concentrated sulfuric acid.

Further, to extract the noble metals, the sorbent is contacted with a solution containing one or more platinum group metals. After a predetermined time, the solid phase is separated from the liquid by filtration, the solid phase is washed with water, dried and ashed. The ash determines the content of precious metals.

The invention is illustrated by examples.

Example 1

In a solution containing 10 M hydrochloric acid, 1 g of iron, copper, zinc, chromium, nickel, cobalt in the form of chloride salts, 50 mg of platinum and gold, 1.0 g of collagen dispersion was added and shaken for 5 minutes at room temperature 20 ° С. The sorbent was filtered off, dissolved in nitric acid, and the content of PGM in the solution was determined by the sorption-atomic absorption method. The results are shown in table 1.

Example 2

In a solution containing 0.1 M hydrochloric acid, 1 g of copper, nickel, cobalt, calcium, cadmium, iron in the form of chloride salts and 50 mg of platinum, palladium, rhodium, iridium were added 2.0 g of collagen dispersion and kept for 15 minutes at 100 ° C. The sorbent was filtered off, dissolved in nitric acid, and the platinum content in the solution was determined. The results are shown in table 1.

Example 3

In a solution containing 0.1 M hydrochloric acid, 1 g of copper, nickel, cobalt, calcium, sodium in the form of nitric salts, 50 mg of platinum in the form of nitric salts, 1.0 g of collagen dispersion was added and shaken for 1 minute at 20 ° C. The sorbent was filtered off, dissolved in nitric acid, and the platinum content in the solution was determined. The results are shown in table 1.

The results of the tests indicate the achievement of almost complete extraction of precious metals from solutions - from 99.98% to 100% at any temperature, acidity of the medium and the amount of non-precious components of the solution, which is sufficient for the application of the proposed method for the extraction of platinum group metals from solutions.

The inventive method is industrially applicable, because It does not require unique equipment and reagents.

When analyzing patent and scientific and technical literature, no information was revealed about the popularity of the proposed method, which allows it to be considered as meeting the criterion of "novelty."

However, the sorbent used in this method is new, unknown from the prior art.

Indeed, although the properties of BG have been previously studied and found application in medicine (eye drug films, collagen sponges for treating burns), in construction (glue), in agriculture (protein feed, fertilizers), etc., but they were not used anywhere in means for the extraction of platinum group metals from solutions. This possibility was not known and identified by the authors for the first time, which allows us to conclude that the proposed solution meets the criterion of "inventive step". In addition to the main advantage - high efficiency of extracting precious metals from wastewater while reducing the cost of the process, the claimed method solves an additional problem - reducing the environmental load on the environment by utilizing waste from two industries - leather (protein hydrolyzate) and oil industry (hydrogen sulfide), which are components the claimed sorbent. Thus, the feedstock for producing the sorbent is cheap and affordable, and the sorbent itself has good capacity and selectivity.

In this regard, this method may be most preferable for the extraction of platinum group metals from solutions, especially in regions with a high concentration, oil refining and leather and shoe industry.

Table 1 Item to be defined The content of the element, mg The degree of extraction,% Source After sorption one Gold fifty 49.99 99,99 Platinum fifty 49.99 99,99 2 Palladium fifty 50.00 one hundred Platinum fifty 49.98 99.98 Rhodium fifty 49.98 99.98 Iridium fifty 49.55 99.10 3 Platinum fifty 49.99 99,99

Claims (3)

1. A method of extracting platinum group metals from solutions, comprising contacting the solution with a sorbent and subsequent separation of platinum group metals from the sorbent, characterized in that a collagen dispersion is used as the sorbent, the collagen obtained by mixing 3 parts of formalin with 0.5 parts of protein hydrolyzate obtained from leather wastes, and 7.5 parts of hydrogen sulfide, followed by neutralization of the mixture, filtration, drying and grinding. 2. The method according to claim 1, characterized in that the protein hydrolyzate is obtained by treating leather wastes in an acid-base environment until a homogeneous mass is obtained. 3. The method according to claim 2, characterized in that as waste leather processing use waste leather chrome tanning.