Method of extracting gold using macroporous resins

FIELD: metallurgy.

SUBSTANCE: proposed method comprises preparing leaching solution bearing gold, and gold sorption by macroporous resin containing alkyl amine functional groups in amount of 0.01-1.0 mmol/g and 3-12% of cross-links with water retaining capacity making, at least, 30%, and specific surface area varying from 400 to 1200 m²/g. After sorption, gold is eluted.

EFFECT: higher yield of gold.

7 cl, 7 tbl, 2 ex

The present invention relates to a method of extraction of gold using ion-exchange resins selective for gold.

For the selective extraction of gold from leach solutions were offered a variety of ion exchange resins. The most profitable was considered weakly basic resin because of the perceived ease of elution with an aqueous solution of sodium hydroxide. However, such a weakly basic resins have various shortcomings.

Work was also undertaken to study the available strong-base resins, which in conventional leaching solution of gold have a higher adsorption capacity than the weakly basic resin. In addition, the mechanisms of chemical reactions taking place during adsorption of ions on strong-base resins, easier than in the case of weakly basic resins. This is because the charge of the resin does not change and the influence of pH can, in General, be ignored.

Despite these advantages, the selectivity of such a commercially available strong-base resins for gold was insufficient.

Carried out certain tests experimental strong-base resins with different aminovymi functional groups. (See the article "The Extraction of Metals from alkaline cyanide solutions by basic ion exchange materials A.A.Buggs and other Published Department of Scientific and Industrial Research, National Chemical Laboratory, Teddington, middlesex, 1963.) However, NASM is rubbing on satisfactory capacity and selectivity for gold, such resins show poor performance in relation to the elution and therefore not suited for commercial applications. Efficient elution can be carried out only in the case, if the resin is additionally modified by the introduction of weakly basic groups, and, in addition, as the eluent had to use a methanol solution of thiourea or thiocyanate. For effective removal of adsorbed gold from the structure of the modified weakly basic groups, using aqueous solutions of thiourea, which is better suited for commercial use required around sorokaletnei volume of eluent in relation to the volume of the adsorbent. When working on a commercial scale using such a volume of eluent is undesirable.

Although improved strong-base anionic ion-exchange resin, such as a commercially available resin XZ-91419 the Dow Chemical Company, are considered as an alternative to activated carbon in the extraction of gold using zenderoudi, their selectivity is still insufficient to eliminate the need for costly and cumbersome process separate elution. Processing with separate elution entails the use of many consistently used eluents and regenerating agents intended for the beginning to hold the elution of unwanted base metals (mainly Cu and Zn), and then elution of the target metals - gold and platinum group metals.

It has been unexpectedly found that such defects in a satisfactory degree softened by a suitable choice of the type of resin. The present invention solves this problem by providing a class of strongly basic anion-exchange resins, overselective against cyanide complexes of gold, but not cyanide complexes of basic metals; such a resin does not require additional processing by elution.

In accordance with the present invention provides a way to separate the gold from the leach solution, comprising the following stages:

I) providing a leach solution comprising gold;

II) providing a macroporous resin, including alkylamine functional group in the resin: (a) contains from 3 to 12% crosslinking; b) contains from 0.02 to 1.0 mmol/g of functional groups; b) has a water retention capacity, component, at least 30%; and g) 15 has a specific surface area comprising from 400 to 1200 m²/g; and

III) contacting the leach solution with a macroporous resin.

All ranges are covering the nature and they can be combined.

The present invention is a unique copolymer matrix resin with the purpose of the floor is ing strongly basic anion-exchange resins, in virtually all charged functional groups are separated from each other in the matrix resin in such a way that, essentially, there are no pairs of functional groups present in sufficient physical proximity to bind the same multivalent ion. This effective separation of the centers eliminates the need to use exotic hydrophobic amines and yields a strongly basic anion-exchange resins with very high selectivity for gold/copper.

The present invention provides a method of extracting gold from its solutions, specifically, cyanide solutions, including the contacting of the solution containing the gold, resin described in the present description, the separation of the resin and obezzolochenny solution and the selection of adsorbed gold by elution.

In order to describe the present invention the resin is defined as macroporous copolymer, which in a broad sense includes copolymers, obtained by suspension polymerization of a monomer composition in terms traditionally used to produce ion exchange resins, in the presence of one or more pore-forming diluents or solvents that contribute to swelling, using quantities sufficient to separate the phase of the resulting copolymer from the phase razbavitelyami not less it should be noted that in the art will know many other methods of polymerization, intended for the preparation of copolymers that can be used in the polymerization in accordance with the present invention.

If macroporous copolymer in contact with the solvent, contributing to swelling, for example, chloromethylation ether, a distinctive feature of its structure is the presence of regions of densely Packed polymer chains separated by pores, which is often referred to as mesopores (50 to 200 Å) and macropores (>200 Å). The heterogeneity of the internal structure of the swollen macroporous copolymer leads to visual turbidity copolymer because of its ability to refract light. If macroporous copolymer deleted inert diluents or solvents that contribute to swelling, for example, by vacuum or steam distillation of the copolymer, in many cases, the pores klapivad under the influence of internal pressure created by the increased forces of attraction areas, densely populated chain of the polymer, therefore, the copolymer will look transparent or translucent. Developed class of macroporous copolymers which retain the porous structure even after the removal of inert diluents or solvents that contribute to swelling. That is their macroporous copolymers call macrostate copolymers, they are described in the patent US 4382124. Their peculiarity is turbid appearance regardless of the presence or absence of inert diluents or solvents that contribute to swelling.

Methods of cooking macrostate copolymers moulinrouge aromatic monomer and a crosslinking monomer crosslinked after polymerization of polyfunctional alkylating or allermuir connection in the swollen state in the presence of a catalyst of the Friedel-described in patents US 4191813 and 4263407 included in the present description by reference. Such macrostate copolymers referred to as "macrostate polymeric adsorbents". In macrostate polymeric adsorbent is possible to introduce functional groups, such as the hydrophilic group, using traditional methods of introducing functional groups in the copolymer obtained by suspension polymerization with the participation of ion-exchange groups. For example, polymeric adsorbent can be functionalitywith by amination chloromethylating polymeric adsorbent alkylamine compounds, for example, dimethylamine, trimethylamine or dimethylethanolamine, depending on what functionality you need to get is a weakly basic or strongly dissociated. The bonds alkylamines of the present invention include alkyl groups with chain length, part of the t one to six carbon atoms. Similarly, in macrostate polymeric adsorbent is possible to introduce functional groups by sulfating. Alternatively, in klimatisierung polymeric adsorbent is possible to introduce functional groups by solvolysis at elevated temperatures. The content of functional groups in the resins of the present invention is from 0.02 to 1.0 mmol/g

The most preferred method of receiving adsorbing resins, crosslinked after polymerization in the swollen state in the presence of a catalyst of the Friedel-described in the patent GDR DD 249274 A1, hereby incorporated into this description by reference. This patent describes crosslinking after polymerization, "solvent free" klimatisierung macroporous copolymer of styrene and divinylbenzene. After chlorotoluene the first copolymer is in contact with the washing agent, for example with methanol, and then the washing agent is removed by drying the washed polymer or extraction leaching agent solvent, contributing to the swelling, which is used for subsequent reactions stitching. After stitching klimatisierung copolymer it is possible to introduce a hydrophilic functional group in the traditional way, thus, will be useful absorbent resin. If necessary, the introduction of functional groups can be done is manage before crosslinking of the polymer, carried out after polymerization.

Although the GDR patent describes only way to obtain absorbent resin of macroporous copolymer of styrene and divinylbenzene, the method can also be used for other macroporous copolymers moulinrouge aromatic monomer and a crosslinking monomer. Such copolymers can be applied to other absorbent resins suitable for use in mining operations mining method of the present invention.

Preferably, the macroporous copolymer functionalitywith as follows: first, perform chlorotoluene copolymer, the crosslinking of the copolymer after polymerization, and then produce amination klimatisierung cross-linked copolymer of tributyl-n-amine, isopropylidenediphenol, triethylamine, Tripropylamine, dimethylamine, trimethylamine or dimethylethanolamine. Most preferably, the functional group in the crosslinked macroporous copolymer is administered by amination klimatisierung copolymer with trimethylamine. Preferred monovinyl aromatic monomers are styrene and its derivatives, for example, alpha methylsterol and vinyltoluene, vinylnaphthalene, vinylbenzoic and vinylbenzyl alcohol. Crosslinking monomers include a wide range of compounds of polyvinylidene, p is listed in the patent US 4382124. Preferred crosslinking monomers are divinylbenzene (commercially available divinylbenzene, containing less than about 45 wt.% ethylvinylbenzene), trivinylbenzene and diacrylate of ethylene glycol.

In the present invention results in an effective separation of functional centers by catalytic formation of methylene bridges in chlorotoluene stiroldivinilbenzol copolymer. Essentially, all chloromethylene groups that are close to each other, are destroyed when carrying out the reaction of formation of bridges. The remaining chloromethylene group physically isolated from each other. Such chloromethylene group, located at large distances, miniroot obtaining highly selective in respect of the gold anion exchange resins.

Preferred macroporous copolymer contains up to about of 99.75 wt.% styrene, the remainder is a divinylbenzene. Another preferred macroporous copolymer includes from about 40 to about 60 wt.% styrene, from about 40 to about 60 wt.% vinylbenzoate and from about 1 to about 20 wt.% divinylbenzene. Macroporous copolymers may contain small quantities of other monomers, such as esters of acrylic and methacrylic acid, and Acrylonitrile.

A crosslinking agent serves to increase the physical is some stability absorbent resin. The required amount of crosslinking agent largely depends on the process conditions used to obtain the copolymer, the amount can be from about 1 to about 45 wt.% in the calculation of the total number of monomer, preferably from about 3 to about 12 wt.%.

When the crosslinking after polymerization in the swelled state is substitution and rearrangement of polymer chains, which leads to an increase in the number of micropores (diameter > 50 Å) and mesopores. This leads to an increase of porosity, surface area and smaller average pore size. It is also important that paleolibertarian stitching, in addition, increases the rigidity of the polymer, thereby reducing its tendency to shrink and swell upon contact with aqueous solution (in the field of technology related to ion exchange, referred to as "shrinkage/swelling), as well as reducing its adsorption capacity in dry form after the introduction of functional groups, which testifies to its ion-exchange capacity.

The degree of crosslinking required for any application, represents the degree to which efficiently achieved the desirable properties of the absorbent resin described above.

The specific surface area of the absorbent resin preferably ranges from about 400 to about 1200 m²/g dry BPA is biruwa resin, more preferably, from about 600 to about 1000 m²/g, most preferably from 800 to 950 m²/g Specific surface area measured by nitrogen adsorption BET method. Porosity ranges from about 0.10 to about 0.70 to cubic centimeters of pore volume per cubic centimeter of resin (cm³/cm³), preferably from about 0.43 to about of 0.58 cm³/cm³on the basis of the calculation methodology nitrogen adsorption BET. The porosity is related to the micropores is from about 30 to about 100%, preferably from about 30 to about 50%, depending on the properties of the resin. The percentage of shrinkage/swelling is less than about 15%, more preferably less than about 7%, most preferably less than about 4%. This index is determined by measuring the volumetric expansion or compression absorbent resin with hydrating or changing the ionic form. Capacity in dry form, determined in accordance with the traditional methods used for characterization of ion-exchange resins ranges from more than zero to about 4.0 mEq./g (milliequivalents/g), preferably from more than zero to about 2.0 mEq./, If a functional group is introduced into macroporous copolymer by solvolysis, for example by contact with water or what IRTA, the capacity in the dry form is essentially 0.

Absorbent resin can be applied in the form of beads, pellets or any other desired form. If absorbent resin used in the form of balls, their size ranges from about 10 to about 1000 microns, preferably from about 100 to about 800 microns, more preferably, from about 300 to about 800 microns.

After that, the above-described macroporous resin is in contact with the leach solution containing gold. The gold content in the leaching solution may range from a few parts per trillion, or, in the alternative, for commercial applications, from 0.5 ppm million to 50,000 ppm million, preferably from 30 to 1000 ppm million, more preferably from 30 to 300 ppm million Preferably, the leaching solution is a cyanide solution.

Various processes, in which you can make contact macroporous resin and leach solution, known to persons skilled in the art. Such methods include, but are not limited to, the ways of resin in cyanide solution, resin-in-pulp or in the column. Such methods are given only as examples and are not intended to further limit the scope of the present invention. Within the scope of the present invention, the input is t any method of contact, known to persons skilled in the art.

After contact with a macroporous resin gold is adsorbed on the resin and is separated from the leach solution. The purpose of separation of gold from leach solution gold then elute from the resin.

Believe that another advantage of the present invention is that when the single-stage elution should be a solution that includes a large amount of gold, which eliminates the need for additional processing using expensive separate elution. Gold can be eluted from macroporous resin by contacting the complex gold/resin such eluate as acidic thiourea. Macroporous resin of the present invention is a catalyst for the decomposition of thiourea, therefore, is not observed significant degradation and are provided with excellent characteristics elution. Thus, the present invention provides advantageous selective against gold ion-exchange resin, which can be effective elution without poisoning or contamination of the resin in any significant degree.

Examples

Example 1: obtaining raw solutions

Test the capacity of the resin was performed using two synthetic cyanide gold the solutions. Both solution contained gold, silver and base metals (zinc, Nickel, cobalt, iron and copper) in approximately equal concentrations. Concentration is not bound in the complex of free cyanide was 20 mg/l in the first solution (see table 1) and 110 mg/l in the second solution (see table 1). The solutions were prepared by dissolving the required amounts of metal salts in deionized water and bring volume up to 80 liters. Then, before the test, the solution was brought to pH of about 11, by adding sodium hydroxide.

Target and actual concentrations of metals and free cyanide two raw-material solutions are shown in table 2.

Example 2: test of adsorption resins

The adsorption of solmissus by contacting 7 ml sample of each resin (CN-form) with both the raw material solution in the volumetric relations solution/resin, components 200/1 and 1000/1, within 24 hours of the Test tank at the volume ratio of solution/resin, sostavlyayuschim/1 (1.4 l of solution), was carried out in kalenderwoche the bottle, and tested at a volume ratio of solution/resin constituting 1000/1 (7 l of solution), was carried out in a tank with an agitator. After saturation of the resin was recovered, dried and prepared for analysis for Au, Ag, Cu, Fe, Ni, Co and Zn in accordance with method No. 9-8-50 SGS Minerals Laboratory. Sample obezzolochenny solution was analyzed similarly, and by titration of cyanide of silver. The results are summarized in tables 3 and 4. Resin Dow XZ-91419 commercially available and supplied by The Dow Chemical Company. DOW HSGR is overselective against gold resin of the present invention, representing a strongly basic anion-exchange resin obtained in accordance with the method described in the present description, and functionalized with trimethylamine. AURIX is a strongly basic anion-exchange resin, commercially available and supplied by Cognis.

1. Method of extraction of gold from the leach solution, comprising the following stages:
I) preparation of a leach solution containing gold;
II) providing a macroporous resin, including alkylamine functional group in the resin: (a) contains from 3 to 12% crosslinking; b) contains a functional group in an amount of from 0.02 to 1.0 mmol/g; C) has a water retention capacity, component, at least 30%; and g) 10 has a specific surface area comprising from 400 to 1200 m²/g; and
III) extraction of gold from the leach solution by contacting leach solution with a macroporous resin so that the gold is adsorbed on a macroporous resin.

2. The method according to claim 1 which further includes the elution of gold from macroporous resin by contacting macroporous resin containing gold, with eluent.

3. The method according to claim 2, in which the eluent is an acid timoci the inu.

4. The method according to claim 1, wherein the specific surface area of the macroporous resin is from 800 to 950 m²/year

5. The method according to claim 1, in which the content of gold in cyanide solution is from 30 to 300 ppm million

6. The method according to claim 1, in which alkylamine functional groups are alkylamine selected from the group comprising tributyl-n-Amin, isopropylbenzylamine, triethylamine, Tripropylamine, dimethylamine, trimethylamine and dimethylethanolamine.

7. The method according to claim 1, in which alkylamine functional groups are trimethylamine.