RU2493915C1 - Method of producing easily regenerated ionite - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to methods for synthesis of selective sorbents for extracting gold from solutions and pulp. The method is realised by diethylenetriamine aminolysis of a porous copolymer of acrylonitrile, divinylbenzene and styrene, with weight content of acrylonitrile of 34-45%, divinylbenzene - 12.5-20%, styrene - 20-46% and ethylstyrene 8-14%. The copolymer is synthesised by suspension copolymerisation of a mixture consisting of said monomers, benzoyl peroxide as a polymerisation initiator, a mixture of ammonium chloride solution and hydroxyethyl cellulose as a suspension medium, alkylbenzene as blowing a agent.

EFFECT: invention enables to obtain easily regenerated ionite for sorption of gold from cyanide hydrometallurgical media.

2 cl, 2 tbl, 7 ex

Description

The proposed method relates to methods for the synthesis of selective sorbents for the extraction of gold from solutions and pulps obtained by leaching gold-containing ores, concentrates and sludges with alkaline cyanide solutions.

Known methods for producing gold-selective anion exchangers of mixed basicity with tertiary and quaternary amino groups are polymer analogous to the copolymers of 2-methyl-5-vinylpyridine, styrene and divinylbenzene by chloromethylation, amination with dimethylamine and alkylation of the pyridine component with dimethyl sulfide or USSR alkylated pyridine. component (US Pat. RF No. 2006506 C1, 1992). Sorbents based on 2-methyl-5-vinylpyridine due to the cessation of its production have not found industrial application.

A known method of producing selective anion exchangers with benzyldimethylamine and dibenzyl dimethylammonium functional groups: AM-2B, Rossion 12, Purolite A 100/2412, used on an industrial scale for the extraction of gold from cyanide environments ("Underground and heap leaching of uranium, gold and other metals" ed Prof. Doctor of Engineering M.I. Fazlullina, M., “Ore and Metals”, 2005, v.2, p.130).

A single synthesis scheme for such sorbents consists in sequentially carrying out chloromethylation and amination with dimethylamine of porous copolymers of styrene and divinylbenzene (ed. Certificate of the USSR No. 394391, 1973). The capacity and gold selectivity of the obtained anion exchangers depends on the concentration of amination solutions, which is responsible for the number of strongly basic groups in the anion exchangers, and the porometric characteristics of the copolymer. To increase the selectivity of the sorbent in its matrix by re-polymerization can be introduced an additional network polymer (patent RU 2387673 C1, 2010).

Along with the unconditional advantages of the sorbents obtained by the above method, the experience of their industrial application revealed a number of problems associated with the complexity of regeneration, consisting of eight consecutive operations, a total duration of more than 200 hours, with the transition from alkaline-cyanide to acid-thiourea treatment, which negatively affects the strength of sorbents, the release of toxic hydrocyanic acid gas, the need for its detoxification and organization of personnel protection measures, the use of expensive acid-resistant About equipment and reagents (thiourea).

A recently developed non-waste method for the regeneration of ion exchangers saturated with gold and impurity metals during sorption from cyanide media using reagents used in the leaching of gold from ores (i.e. cyanide and alkali) is free of these drawbacks, but requires the creation of specific sorbents that meet the conditions of the new technology ("Non-ferrous metals", 2010, No. 1, p.22-26).

The technical result of the invention is to create a sorbent that meets the requirement of effective desorption of gold with alkaline cyanide solutions.

A method has been developed for the production of easily regenerated ion exchange resin for sorption of gold from cyanide hydrometallurgical media by treating a porous copolymer of acrylonitrile, divinylbenzene (DVB), styrene and ethyl styrene containing acrylonitrile 34-45 wt.%, Divinylbenzene 12-21 mass% with diethylene triamine. 46 wt.% And ethyl styrene 8-14 wt.%, Synthesized by suspension copolymerization in an aqueous medium. Ionite contains weakly basic amine primary, secondary and tertiary (iminosoline) functional groups obtained by aminolysis of acrylonitrile, which are separated by "ballast" styrene fragments.

The copolymer is prepared by suspension suspension polymerization of a mixture of monomers — acrylonitrile, divinylbenzene, styrene, ethyl styrene — and a blowing agent selected from aliphatic hydrocarbons or alkylbenzene taken in an amount of 40-50 vol% of the volume of the mixture of monomers and a copolymerization initiator (benzoyl peroxide). The polymerization is carried out in a suspension medium, which is an aqueous solution of ammonium chloride with the addition of hydroxyethyl cellulose.

Ethyl styrene is introduced into the copolymer not as a separate monomer, but as part of technical divinylbenzene, where it is a polymerizable component. In addition, there are other non-polymerizable impurities in the technical DVB. The amount of ethyl styrene in the copolymer is determined by the specified divinylbenzene content in the copolymer (crosslinking) and the composition of the technical divinylbenzene used.

Aminolysis of the copolymer with diethylene triamine is carried out at 120 ° C for 8-10 hours.

The proposed method allows to obtain a gold-selective ion exchange resin capable of desorption of gold with an alkaline cyanide solution.

Due to the lack of a chloromethylation step associated with the use of a carcinogenic monochlorodimethyl ether and the need to process a large amount of chemically harmful waste, the proposed synthesis method is more economical and environmentally friendly than the above method for producing selective sorbents based on styrene-divinylbenzene copolymers.

The synthesis conditions and properties obtained by the proposed method sorbents in comparison with anion exchange resin AM-2B are presented in the examples.

Example 1 (comparative)

The composition of the copolymer not containing styrene, wt.%: Acrylonitrile (NAC) - 75; divinylbesol (DVB) - 15; ethyl styrene (ES) - 10. Pore former: alkylbenzene - 40 vol.% of the volume of the mixture of monomers.

The copolymerization is carried out at a ratio of the volume of the suspension medium and the polymerization mixture 2: 1.

1.1. Copolymerization

A suspension medium is charged into a glass copolymerization reactor equipped with a stirrer and a water bath. A polymerization mixture consisting of 69.3 g (86.2 ml) of NAC; 0.95 g of benzoyl peroxide (PB); 24.3 g (27.0 ml) of technical DVB containing 57% of the mass. DVB, 38% of the mass. ES and 5% non-polymerizable impurities, and 45.3 ml of alkylbenzene are poured into a suspension medium heated to 40-45 ° С with a working stirrer. Suspension medium: 320 ml of a 20% aqueous solution of "NT-LtCl with the addition of 1.84 g of hydroxyethyl cellulose.

The reactor is sealed and the mixture continues to be heated according to the following temperature conditions: heating to 65 ° C for 0.5 hours, holding at 65 ° C for 4 hours, raising the temperature to 85 ° C for 1.5 hours, holding at 85 ° C for 4 h, raising the temperature to 90 ° C - 1 h, holding at 90 ° C - 1 h. After cooling and depressurization of the reactor, the resulting copolymer is separated from the mother liquor, washed with water, separated into fractions by "wet" sieving and dried in air.

1.2. Aminolysis

55 g of the obtained air-dry copolymer with a particle size of 0.4-0.8 mm are placed in a glass three-necked flask equipped with a stirrer and an oil bath, and 170 ml of diethylene triamine (DETA) are poured. The mixture is heated with stirring for 8 hours at 120 ° C. The reaction mixture cooled to 50 ° C is filtered, the obtained ion exchanger is washed three times with hot water, the washing is continued with water, gradually lowering its temperature, and the phenolphthalein promoter is neutral. Get 230 ml of swollen ion exchanger with the following properties: static exchange capacity of the C 1-ion of 5.2 mEq / g; a static exchange capacity in the OH form of 6.4 mEq / g; specific volume for swelling of the C1-form of ion exchanger in distilled water 2.75 ml / g; mechanical strength (MP) 97%.

Example 2

The composition of the copolymer, wt.%: NAC - 45; styrene - 20; DVB - 21; ES - 14. Pore former: alkylbenzene in an amount of 40 vol.% Of the volume of the mixture of monomers.

2.1. Copolymerization

The composition of the polymerization mixture: NAC 44.7 g (55.6 ml); styrene 19.9 g (22.1 ml); PB 1.1 g; technical DVB 36.5 g (40.6 ml), including DVB -20.8 g and ES -13.9 g. The total volume of monomers is 118.3 ml, the volume of alkylbenzene 47.3 ml. Suspension medium: 320 ml of a 20% aqueous solution of NH ₄ Cl with the addition of 1.84 g of hydroxyethyl cellulose.

The copolymerization is carried out in the mode of clause 1.1. example 1.

2.2. Aminolysis

Aminolysis is carried out under the conditions given in paragraph 1.2. example 1.

Properties of the obtained ion exchanger: static exchange capacity for C1-ion 3.9 mEq / g; a static exchange capacity in the OH form of 4.5 mEq / g; specific volume during swelling of C 1 - form of ion exchanger in distilled water 2.6 ml / g; MP 98%.

Example 3

The composition of the copolymer, wt.%: NAC - 45; styrene - 30; DVB - 15; ES - 10. Pore former: p-octane in an amount of 40 vol.% Of the volume of the mixture of monomers.

3.1. Copolymerization

The composition of the polymerization mixture: NAC 43.1 g (53.6 ml); styrene 28.7 g (31.9 ml); PB 0.96 g; technical DVB 25.2 g (28.0 ml), including DVB-14.4 g and ES - 9.6 g. The total volume of monomers is 113.5 ml, the volume of p-octane is 45.4 ml. Suspension medium: 320 ml of a 20% aqueous solution of NH4C1 with the addition of 1.84 g of hydroxyethyl cellulose.

The copolymerization is carried out in the mode of clause 1.1. example 1.

3.2. Aminolysis

Aminolysis is carried out under the conditions given in paragraph 1.2. example 1.

Properties of the obtained ion exchanger: static exchange capacity for C1-ion 3.15 mEq / g; a static exchange capacity in the OH form of 3.55 mEq / g; specific volume of C 1-form ion exchanger when swelling in distilled water 2.6 ml / g; MP 100%.

Example 4

The composition of the copolymer, wt.%: NAC - 40; styrene - 35; DVB - 15; ES - 10. Pore former: i-octane in an amount of 45 vol.% Of the volume of the mixture of monomers.

4.1. Copolymerization

The composition of the polymerization mixture: NAC 37.2 g (46.3 ml); styrene 32.6 g (36.2 ml); PB 0.93 g; technical DVB 24.4 g (27.2 ml), including DVB -14.0 g and ES - 9.3 g. The total volume of monomers is 109.7 ml, the volume of i-octane is 49.4 ml. Suspension medium: 320 ml of a 20% aqueous solution of NHLtCL with the addition of 1.84 g of hydroxyethyl cellulose.

The copolymerization is carried out in the mode of clause 1.1. example 1.

4.2. Aminolysis

Aminolysis is carried out under the conditions given in paragraph 1.2. example 1.

Properties of the obtained ion exchanger: static exchange capacity for the C1-ion of 2.8 mEq / g; a static exchange capacity in the OH form of 3.1 mEq / g; specific volume of C 1-form ion exchanger when swelling in distilled water 2.6 ml / g; MP 98.5%.

Example 5

The composition of the copolymer, wt.%: NAC - 34; styrene - 46; DVB - 12; ES - 8. Pore former: i-octane in an amount of 50 vol.% Of the volume of the mixture of monomers.

5.1. Copolymerization

The composition of the polymerization mixture: NAC 31.0 g (38.6 ml); styrene 41.9 g (46.6 ml); PB 0.91 g; technical DVB 19.2 g (21.3 ml), including DVB-10.9 g and ES - 7.3 g. The total volume of monomers is 106.5 ml; the volume of i-octane is 53.3 ml. Suspension medium: 320 ml of a 20% aqueous solution of NH ₄ CL with the addition of 1.84 g of hydroxyethyl cellulose.

The copolymerization is carried out in the mode of claim 1.1. example 1.

5.2 Aminolysis

Aminolysis is carried out under the conditions given in paragraph 1.2. example 1.

Properties of the obtained ion exchanger: static exchange capacity for the C1-ion 1.85 mEq / g; static exchange capacity in the OH form 1.99 mEq / g; specific volume of C 1-form ion exchanger when swelling in distilled water 2.5 ml / g; MP 99%.

Example 6

Sorption properties of ion exchangers obtained by the proposed method, was determined on a model solution that simulates industrial cyanide-alkaline solutions of the following composition, mg / l: Au 4.3; Fe 9.6; Si 10.8; Zn 8.8; Ni 2.4; NaCN 400; pH 10.6.

Samples of ion exchangers in a C 1 form were placed in a model solution with an ion exchanger: solution = 1: 5000 ratio for 24 hours with mechanical stirring at room temperature. Saturated samples were separated from the solution, washed with water, dried to constant weight and, after “wet” burning, the content of gold and impurity metals was determined by atomic adsorption analysis. The results are presented in table 1.

Table 1 Comparative data on the capacity and gold selectivity of samples of ion exchangers obtained by the proposed method, and anion exchange resin AM-2B Example No. The composition of the copolymer,% Gold Capacity Admixture capacity, mg / g Gold selectivity NAC DVB ES Styrene mg / g mg / ml 1 comp. 75 fifteen 10 - 2.03 0.73 6.16 0.33 2 45 21 fourteen twenty 3.92 1.45 5.60 0.70 3 45 fifteen 10 thirty 4.20 1,63 3,58 1.17 four 40 fifteen 10 35 4.41 1.77 3.29 1.34 5 34 12 8 46 4.8 1.96 1.15 4.14 AM-2B - 8 5 87 7.5 2,34 18.3 0.41

Ionites obtained by the proposed method have a lower sorption capacity for gold, which is 52-64% of the capacity of AM-2B in weight units, than the expert anion exchange resin AM-2B. In volume units (in mg / ml), this capacity is higher (62-84% of the capacity of AM-2B). The gold selectivity of ion exchangers obtained by the proposed method is 1.8-10 times higher than the selectivity of AM-2B.

Example 7

The regeneration of saturated sorbents was carried out by treating them with a desorbing alkaline cyanide solution under static conditions. Samples of ionites, saturated during sorption from a gold-containing model solution, weighing 1 g were placed in a solution of the composition, g / l: NaOH 10; NaCN 50, with the ratio of ion exchanger: solution = 1: 5000. The process was conducted for 6 hours at 60 ° C. At the end of desorption, washing with water, drying and “wet” burning of the sorbent, the residual content of gold and impurity metals was determined by the atomic adsorption method.

The results of comparative desorption tests of ion exchangers obtained under the conditions of examples 2, 4, 5 (styrene content in the copolymers 20, 35.44 wt.%, Respectively) and anion exchange resin AM-2B are presented in table 2.

table 2 Desorption of gold and impurity metals from saturated ion exchangers with alkaline cyanide solutions Name of indicator Ionites AM-2B comp. Obtained by the proposed method, No. examples 2 four 5 The gold content in saturated ion exchangers, mg / g 7.5 3.92 4.41 4.8 The content of metal impurities in ion exchangers, mg / g 18.3 5,6 3.3 1.15 The residual gold content in ion exchangers after desorption, mg / g 7.2 0.59 0.40 0.15 The residual content of metal impurities in ion exchangers after desorption, mg / g 6.7 1,0 0.3 0.09 The degree of desorption of gold,% four 85 91 96.9 The degree of desorption of metal impurities,% 63,4 82 90 92

The data obtained show that desorption by alkaline cyanide solutions of both gold and impurity metals is much more efficiently performed from ion exchangers obtained by the proposed method than from AM-2B anion exchange resin. In mixed-basic anion exchange resin AM-2B, desorption of gold by alkaline cyanide solutions almost does not occur (only 4%), while in ion exchangers synthesized by the present method, the degree of gold desorption upon single contact with an alkaline cyanide solution was 85-96, 9%, and the degree of desorption of impurities 82-92%.

The data show that the inventive method for producing ion exchange ion exchangers by aminolysis with diethylene triamine copolymers of acrylonitrile, divinylbenzene, ethyl styrene and styrene allows to obtain highly selective sorbents that are 1.8-10 times higher than the gold selectivity of anion exchange resin AM-2B, capable of efficient desorption of gold and metals impurities from a saturated sorbent with alkaline cyanide solutions. Due to the absence of a chloromethylation step, the claimed synthesis method is environmentally safer and more economically advantageous than other methods for producing gold selective sorbents based on the use of styrene-divinylbenzene copolymers as a polymer base.

Claims (2)

1. A method of producing an easily regenerated ion exchanger for sorption of gold from cyanide hydrometallurgical media, including aminolysis with diethylene triamine of a porous copolymer of acrylonitrile, divinylbenzene, styrene and ethyl styrene with a mass content of acrylonitrile 34-45%, divinylbenzene 12-21-% 8- styrene, 8-21% styrene, 8-21% styrene, 8-21% styrene 14%, synthesized by suspension copolymerization of a mixture consisting of the above monomers, the copolymerization initiator is benzoyl peroxide, and a pore former selected from aliphatic hydrocarbons or alkylbenzene . 2. The method according to claim 1, characterized in that the volume of the blowing agent is 40-50% of the volume of the mixture of monomers, and the polymerization process is carried out in a suspension medium, which is an aqueous solution of ammonium chloride with the addition of hydroxyethyl cellulose.