RU2447934C1 - Method of producing modified granulated carbon active sorbent of noble metals - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of modified carbon sorbents. Proposed method of producing ''sibunit''-type modified carbon comprises processing it by modifying agent, i.e. poly-1-vinyl-1,2,4-azimide at polymer:carbon weight ratio of 0.02. Application of modifying agent is performed form either water solution of polymer, or from water solution of its monomer with subsequent polymerisation. Drying is made at 100°C after application.

EFFECT: higher sorption capacity with respect to noble metal ions.

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Description

The invention relates to the field of adsorption technology and can be used to obtain modified carbon sorbents, namely, the development of methods for modifying granular carbon material of the Sibunit type with a nitrogen-containing heterocyclic polymer - poly-1-vinyl-1,2,4-triazole, for sorption of noble metals from technological solutions, in particular, in hydrometallurgy processes.

Sibunit is a class of porous carbon-carbon composite materials that combines the advantages of both graphite (chemical stability, electrical conductivity) and activated carbons (high specific surface and adsorption capacity) [G.V. Plaksin. Porous carbon materials such as sibunit. Chemistry for sustainable development. 2001.V.9. No. 5. S.609-620].

A known method for modifying activated carbon, including impregnation using an aqueous solution of ε-caprolactam for 12-24 hours, heating at 250 ° C for 4 hours and carbonization when heated to 900 ° C, followed by cooling, to increase the sorption capacity of coal in relation to to heavy metal ions (patent No. 2276099, Russia, IPC СВВ 31/08, B01J 20/20, publ. Bull. Inventory No. 13, 05/10/2006).

The disadvantages of this method include the duration and complexity of the process of modifying coal and the use of high temperature.

Closest to the proposed method is a method for producing carbon sorbents IPI-T from phenol-formaldehyde resins and the use of these sorbents for the extraction of gold and silver during the leaching of cyanides from ores of complex composition [Yu.E. Golodkov, V.V. Yelshin, V.I. Dudarev, L.M. Oznobikhin. The study of sorption of precious metals on carbon sorbents. Housing and communal services. 2001.V. 74. Issue 1. S.22-24].

However, the IPI-T carbon sorbent shows a reduced efficiency of sorption extraction of gold and silver (the equilibrium concentration of gold ions on the sorbent is 18 mg / g and silver is 10 mg / g) from cyanide solutions and is inferior to foreign activated carbons Norit and Futamura (23% for gold) mg / g, silver - 13 mg / g). In addition, the mechanical strength of IPI-T (85%) is lower than that of foreign analogues (93%).

The aim of the present invention is to increase the sorption capacity of activated carbon "sibunit" in relation to noble metal ions using an affordable and inexpensive modifier. For this, the synthetic carbon material “Sibunit” (specific surface - 450 m ² / g, average pore diameter - 62A, total pore volume - 0.68 cm ³ / g, granule diameter 1.4-2 mm) was subjected to poly-1-vinyl-1 treatment , 2,4-triazole (from the class of heterocyclic, nitrogen-containing compounds); the processing process includes: impregnation of coal with a 2% aqueous polymer solution (at a mass ratio of poly-1-vinyl-1,2,4-triazole to coal equal to 0.02), drying at 100 ° C for 5 hours to a granular state and constant mass.

The technical result achieved in the invention is to increase the efficiency of the carbon sorbent modified in this way in the extraction of precious metals from technological solutions, in particular in hydrometallurgy processes.

The choice of poly-1-vinyl-1,2,4-triazole as a “Sibunit” coal modifier is explained by the fact that the proposed polymer has an effective complex-forming ability due to the nitrogen atom in the 4 position of the five-membered ring with respect to metal ions [Patent No. 23232131. Russia. IPC C08F 226/06. B01J 20/26, publ. Bull. fig. No. 16. 06/10/2008; Patent No. 2321600. Russia. IPC C08F 226/06. B01J 20/26. Bull. fig. No. 10, 04/10/2008].

This goal is achieved by the development of a method for modifying synthetic sibunit coal with poly-1-vinyl-1,2,4-triazole. The invention allows to fix the polymer modifier inside, in the pores of the carbon matrix and on the surface of the coal, and thereby increase the sorption capacity for gold from 20 to 35 mg / g, for silver from 30 to 41 mg / g due to the properties of the polymer modifier containing complexing nitrogen atoms in macromolecules, which allows the formation of additional complexes with noble metals. Intensive mixing of coal provides a uniform distribution of the polymer on the surface of "sibunit" and its penetration into the porous granules.

Drying of modified coal is necessary to fix the polymer modifier and remove the solvent.

Thus, the modification method involves “impregnating” “sibunit” synthetic coal with poly-1-vinyl-1,2,4-triazole and drying it.

The impregnation of "Sibunit" polymer is carried out by two methods.

1. Processing of coal with an aqueous solution of monomer - 1-vinyl-1,2,4-triazole in the presence of a radical type initiator - azoisobutyronitrile at 60-80 ° С, during which polymerization and modification of coal with the polymer - poly-1-vinyl-1 2,4-triazole (PVT).

2. Processing of coal directly with an aqueous solution of poly-1-vinyl-1,2,4-triazole (HTP) at 20 ° C.

The following examples illustrate the invention.

Example 1

5 g of sibunit coal is placed in a glass and a mixture consisting of 2 g of 1-vinyl-1,2,4-triazole, 0.04 g (2 wt.%) Azoisobutyronitrile and 10 ml of distilled water is kept at 60-80 ° С stirring vigorously for 1.5 hours. After the lapse of time, the coal is separated from the solution by decantation and washed with ethanol. Then, the carbon impregnated with the formed poly-1-vinyl-1,2,4-triazole is dried at 100 ° C for 5 hours to a free-flowing state and constant mass. In the process of coal modification, the polymerization of 1-vinyl-1,2,4-triazole takes place. Sibunit coal treated in this way does not lose its initial state, flowability, according to elemental analysis, it contains 2.01% nitrogen, a weight gain of 98.80% based on the amount of polymer taken.

Example 2

In a 0.5 L glass, 2 g of HTP and 200 ml of distilled water are placed, stirred until the polymer is completely dissolved (2 hours). 100 g of Sibunit coal (brilliant granules, fraction 1.4-2.0 mm) are introduced into the crystallizer and treated with a solution of HTP. Strong foaming is observed. Maintain coal with a polymer solution for 0.5-1 hours at 20 ° C until gas evolution is completely stopped. Then the water is evaporated, periodically mixing the contents to avoid sticking. The modified wet coal impregnated with the polymer is dried at 100 ° C for 5 hours. The appearance of “sibunit” does not change. The product is a polymer modified "sibunit" in the form of shiny balls; according to elemental analysis, it contains 2.56% nitrogen, a gain of 99.98% based on the amount of polymer taken.

Example 3

Extraction of gold by leaching it with cyanides from ores of complex composition.

A portion of a modified sorbent (from Example 2) weighing 1-2 g is placed in a solution obtained by cyanide leaching of gold ore. The initial concentration of gold in the solution is from 10 to 25 mg / l. The concentration of sodium cyanide is ~ 0.05%. Sorption time 1-24 hours. Gold recovery by a modified sorbent reaches 99%.

Modification of the sibunit sorbent with poly-1-vinyl-1,2,4-triazole leads to an increase in sorption capacity in relation to gold from 7.0 mg / g to 35.0 mg / compared with unmodified coal.

Example 4

Extraction of gold and silver from ores of complex composition.

A solution containing gold (I) ions 5.0 mg / L, silver (I) 10.0 mg / L, zinc (II) 23.0 mg / L, copper (II) 34.0 mg / L, iron (III) 5.0 mg / L, nickel (II) 0.3 mg / l, tested for the extraction of metal ions by the obtained modified sorbent (from examples 1 and 2). The sorbent selectively extracts gold and silver by 98 and 96%, respectively. The sorption capacity of the modified poly-1-vinyl-1,2,4-triazole sorbent increases with respect to gold from 7 mg / g to 20.0-34.8 mg / g and to silver from 18 mg / g to 30.0-41.0 mg / g, respectively (relative to the initial coal “sibunit”).

Thus, the proposed modified synthetic carbon “sibunit” treated with poly-1-vinyl-1,2,4-triazole containing complexing nitrogen heteroatoms in the macromolecules is used for sorption extraction of gold and silver from cyanide solutions and has the following advantages:

- the simplicity of the coal modification process;

- low concentration of polymer embedded in coal micropores;

- does not lose its initial flowability;

- the ability to complex with metal ions;

- high values of sorption capacity in relation to noble metal ions: gold 20-35 mg / g; silver 30-41 mg / g compared with modified 7 mg / g and 18 mg / g, respectively.

Claims (1)

A method of obtaining a modified granular carbon material used for sorption of precious metals, including the modification of the carbon material "Sibunit" with a nitrogen-containing heterocyclic polymer poly-1-vinyl-1,2,4-triazole with a mass ratio of polymer to "Sibunit" equal to 0.02 and the subsequent drying the material at 100 ° C for 5 hours, while the modification is carried out either with an aqueous solution of the aforementioned polymer at 20 ° C, or with an aqueous solution of its monomer, followed by polymerization at 60-80 ° C.