CN113278815B - Method for recovering gold by using adsorption resin - Google Patents
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Abstract
The invention belongs to the technical field of wet metallurgy, and discloses a method for recovering gold by using adsorption resin, which comprises the following steps: (S1) adjusting the pH value of the gold-containing leaching solution containing gold ions to 1-3, and then adding adsorption resin into the gold-containing leaching solution to adsorb the gold ions in the gold-containing leaching solution; the surface of the adsorption resin is provided with sulfur and nitrogen, and the contents of the nitrogen and the sulfur on the surface of the adsorption resin respectively account for more than 3 percent and more than 20 percent of the total mass of the adsorption resin; (S2) after the adsorption, the gold loaded on the adsorption resin obtained by the step (S1) is eluted, concentrated, separated and regenerated with an eluent, and the gold is recovered. The invention improves the key reaction participators of the method, applies the adsorption resin material with high sulfur element and nitrogen element content on the surface to the recovery of gold, and particularly can be applied to the recovery of gold in low-grade gold-containing materials. The method is simple to operate and suitable for large-scale recovery of low-concentration gold in the leaching solution.
Description
Technical Field
The invention belongs to the technical field of hydrometallurgy, and particularly relates to a method for recovering gold by using adsorption resin.
Background
Gold (Au) is one of the most important noble metals, and is widely used in the fields of ornaments, electronic devices, and catalysis due to its unique physical and chemical properties. Along with the development of science and technology, the demand of gold is increasing day by day, and gold is non-renewable resource, needs to retrieve it from secondary resource and gold-containing slag, realizes the cyclic utilization of resource. In recent years, scrap gold recovery has attracted considerable attention as an alternative to mining. Since the gold content in the electronic garbage and the gold-containing tailings is limited and only contains trace gold, the separation of the gold from leaching is a complex multi-stage process. The common gold leaching method at present comprises a roasting-cyanidation leaching method, an acid leaching-cyanidation leaching method, a flotation method, a high-temperature chlorination volatilization method, regrinding and cyaniding, regrinding and mercury mixing and the like. In a common recovery method, leaching agents (such as sodium cyanide, mercury and the like) contain highly toxic substances, and can enter human bodies along with food chains to cause harm to human life. And the common method can only recover 90% of gold, and part of gold is discharged and lost through tailings. From the perspective of resource recycling, environmental protection and human health, a green, simple and efficient recovery method is required to be found for recovering low-grade gold in tailings and electronic garbage. At present, the relatively green gold leaching method is an acidification method.
At present, methods for recovering gold in electronic garbage and tailing leachate include chemical precipitation, ion exchange, membrane filtration, adsorption and the like. Of the common processes, adsorption is considered to be an effective method for recovering low concentrations of gold from acid leach liquors. Because of its simple design and easy operation. The most critical of the adsorption process is the adsorbent. The common adsorbent for recovering gold from the leaching solution is activated carbon or modified activated carbon, but the adsorbent cannot efficiently and selectively recover gold. In order to meet the requirement of people on gold and realize effective utilization of resources, the design and synthesis of the high-efficiency adsorption resin is crucial to the recovery of gold in the secondary resource leaching solution. According to the soft and hard acid-base rule, the functional resin containing nitrogen and sulfur has stronger acting force on hardware. However, in the related prior art for gold recovery, the content of nitrogen and sulfur elements in the adopted functionalized resin is low, so that the design of synthesizing high-density functionalized resin containing nitrogen and sulfur and using the high-density functionalized resin in the recovery of gold in leachate is of great significance.
For example, the prior Chinese patent application "recovering gold and palladium from electroplating waste liquid by using mercaptoamine chelate resin" (CN85100240A), although it can recover gold to a certain extent (the adsorption capacity is 1-1.1g/g), the adsorption capacity is more general than that of other adsorption materials. In this document, adsorbed gold is recovered by an ashing method, and sulfur elements are contained in a chelate resin, SO is generated in the ashing resin2And the like, which is liable to cause acid rain, and is not favorable for environmental protection.
For example, the chinese patent application of the prior art "method for recovering gold, platinum and palladium gold by ion exchange" in acidic wastewater (CN101618898A) is directed to leaching wastewater obtained by leaching precious metal ore (although the concentration of gold element is not as high as that of leachate directly obtained, the concentration of gold element is still high), and although it can solve the problem of recovering precious metals to some extent, only chemical alloys in a solution system can be recovered by adopting an anion exchange method.
Disclosure of Invention
In view of the above drawbacks and needs of the prior art, the present invention provides a method for recovering gold by using an adsorption resin, wherein an adsorption resin material with a high content of sulfur and nitrogen on the surface is applied to the recovery of gold by improving the reaction participants critical to the method (the content of nitrogen on the surface of the adsorption resin is more than 3% of the total mass of the adsorption resin, and the content of sulfur on the surface of the adsorption resin is more than 20% of the total mass of the adsorption resin), and particularly, the method can be applied to the recovery of gold in low-grade gold-containing materials. The method is simple to operate, is suitable for large-scale recovery of low-concentration gold in the leaching solution, and the recovery rate of the gold can reach 95.17%.
In order to achieve the above object, according to the present invention, there is provided a method for recovering gold using an adsorption resin, comprising the steps of:
(S1) adjusting the pH value of the gold-containing leaching solution containing gold ions to 1-3, and then adding adsorption resin into the gold-containing leaching solution to adsorb the gold ions in the gold-containing leaching solution;
wherein the surface of the adsorption resin is provided with sulfur and nitrogen; the nitrogen content of the surface of the adsorption resin accounts for more than 3% of the total mass of the adsorption resin, and the sulfur content of the surface of the adsorption resin accounts for more than 20% of the total mass of the adsorption resin;
(S2), after the adsorption is finished, the gold loaded on the adsorption resin obtained by the treatment of the step (S1) is eluted, concentrated, separated and regenerated by using eluent, and the gold is recovered.
As a further preferred aspect of the present invention, in the step (S1), the adsorption resin has a chemical structure represented by the following formula (I) or formula (II):
wherein n is an integer of 1 to 10Counting; m is an integer of 2-7;
represents a polymeric substrate;
preferably, the nitrogen content of the surface of the adsorption resin accounts for more than 3% of the total mass of the adsorption resin, and the sulfur content of the surface of the adsorption resin accounts for more than 30% of the total mass of the adsorption resin.
In a further preferred embodiment of the present invention, the adsorbent resin is obtained by modifying the surface of a polymer base material; wherein the polymeric substrate is selected from: cellulose or its derivatives, polyethylene, polypropylene, polystyrene-divinylbenzene type copolymers, ethylene-vinyl alcohol copolymers, polyamides; the surface modification is carried out by adopting an ionizing radiation grafting method or a chemical grafting method;
preferably, the cellulose or the derivative thereof has a crystallinity of 80% or more.
As a further preferred aspect of the present invention, the ionizing radiation grafting method is preferably an electron beam pre-irradiation grafting method, and specifically includes the following steps: grafting Glycidyl Methacrylate (GMA) on the surface of a polymer substrate by using an electron beam pre-irradiation grafting method to introduce an epoxy group, and then introducing a polyethylene polyamine monomer through a ring-opening reaction to prepare a nitrogen-containing intermediate material with a nitrogen element on the surface; then, continuously carrying out nucleophilic substitution reaction on the ethylene sulfide and nitrogen atoms on the nitrogen-containing intermediate material, thereby preparing the adsorption resin with the surface provided with sulfur elements and nitrogen elements;
preferably, the irradiation dose adopted by the electron beam pre-irradiation grafting method is 20-50 kGy.
As a further preferred aspect of the present invention, the surface modification specifically comprises the steps of:
(1) firstly, grafting an epoxy group and introducing the epoxy group into the surface of a high-molecular base material, and then introducing a polyethylene polyamine monomer through an epoxy ring-opening reaction to obtain a nitrogen-containing intermediate material with a nitrogen element on the surface;
or Vinyl Benzyl Chloride (VBC) is grafted and introduced to the surface of the high molecular base material, and then polyethylene polyamine monomers are introduced through a halogenation reaction to obtain a nitrogen-containing intermediate material with a nitrogen element on the surface;
(2) and (2) carrying out nucleophilic substitution reaction on the nitrogen-containing intermediate material obtained in the step (1) by using ethylene sulfide and nitrogen atoms of the introduced polyethylene polyamines, thereby preparing the adsorption resin with the surface containing sulfur elements and nitrogen elements.
As a further preferred aspect of the present invention, the polyethylene polyamine-based monomer is selected from: ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine;
preferably, the polyethylene polyamine monomer is pentaethylene hexamine.
In a further preferred embodiment of the present invention, in the step (S1), the adsorbent resin is a spherical material having an average particle diameter of 300 to 1000 μm.
As a further preferred aspect of the present invention, in the step (S1), the pH adjustment is specifically performed by using a sodium hydroxide solution;
if the gold-containing solid material contains carbonate, the gold-containing leaching solution is prepared by crushing the gold-containing solid material, soaking the crushed gold-containing solid material in hydrochloric acid to remove the carbonate, adding aqua regia into the crushed gold-containing solid material to leach gold, and filtering the gold-containing solid material to obtain filtrate; if the gold-containing solid material does not contain carbonate, crushing the gold-containing solid material, directly adding the crushed gold-containing solid material into aqua regia for gold leaching, and filtering to obtain filtrate;
preferably, wherein:
hydrochloric acid for removing carbonate, the concentration of which is 0.01mol/L-5 mol/L; the ratio of the mass of the crushed gold-containing ore or slag to the volume of the hydrochloric acid is less than or equal to 0.5 g/mL; the soaking time of the soaking is less than 2 hours;
the gold-containing solid material is at least one of low-grade gold ore, gold mine tailing slag, electronic components containing gold elements, alloys containing the gold elements and jewelry waste; wherein the gold element content of the low-grade gold ore is not more than 0.6 g/t;
the aqua regia is dilute aqua regia, and the volume ratio of corresponding concentrated hydrochloric acid to concentrated nitric acid to water is (1-3): (1-8): 1, wherein the mass percentage concentration of the concentrated hydrochloric acid is 37.2%, and the mass percentage concentration of the concentrated nitric acid is 69.8%; the leaching time for gold leaching is 1-24 h.
In a further preferred embodiment of the present invention, the gold-containing leachate has a pH adjusted so that the concentration of gold ions is 1ppb or more, preferably 1 to 500 ppb.
More preferably, the eluent is 0.1-3 mol/L hydrochloric acid, or a mixture of hydrochloric acid and thiourea with a final concentration of 0.1-3 mol/L hydrochloric acid and a final concentration of 0.1-0.5 mol/L thiourea, or a mixture of hydrochloric acid with a final concentration of 0.1-3 mol/L thiourea and a final concentration of 0.1-0.5 mol/L thiourea and H2O2Hydrochloric acid, thiourea and H with final concentration of 0.5-5%2O2The mixed solution of (1).
Through the technical scheme, compared with the prior art, the functional groups introduced into the surface of the adsorption resin have the characteristic of high content of sulfur and nitrogen elements, the content of the nitrogen elements on the surface of the adsorption resin accounts for more than 3% of the total mass of the adsorption resin, and the content of the sulfur elements on the surface of the adsorption resin accounts for more than 20% (especially more than 30%) of the total mass of the adsorption resin. On one hand, the resin is protonated under an acidic condition to become a positive ion center, so that electrostatic adsorption can be performed on gold ions; on the other hand, the functional atoms (N and S) of the group not only have reducibility, but also can be chelated with gold ions, thereby realizing the high-efficiency adsorption of gold.
Based on the method, the adsorption resin with high-density sulfur-containing and nitrogen-containing elements on the surface is utilized, particularly, trace gold can be recovered from low-grade gold-containing materials, and selective and efficient recovery of gold at ppb concentration level in the leachate is realized; the high-density adsorption resin containing sulfur and nitrogen elements can provide more active sites for target adsorption of gold ions, and is favorable for more rapid and efficient gold recovery. Based on the invention, the acid method can be preferably used for extracting gold, and the gold-containing leaching solution containing gold ions is obtained from solid materials (such as low-grade gold ore, gold ore tailing slag, gold-containing electronic garbage, gold-containing alloy, jewelry waste and the like; gold-containing electronic garbage such as gold-containing electronic components and parts; considering that carbonate is always present in the ore, the carbonate is always removed by soaking the low-grade gold ore and the gold ore tailing slag by hydrochloric acid, and then the gold is extracted by the acid method); by using the method of the invention, trace gold can be recovered in the gold-containing leaching solution after the pH is adjusted within the concentration range of 1-500 ppb.
That is, the present invention can obtain the following advantageous effects:
1) the sulfur-containing and nitrogen-containing adsorption resin material with a high-density surface (the total content of nitrogen and sulfur is 37.4%) provided by the embodiment of the invention has a high nitrogen and sulfur content (table 1), and has ultrahigh adsorption capacity, excellent selectivity and reusability for gold.
TABLE 1 analysis of the content of each element in the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorbent resin
2) The adsorption resin provided by the invention can selectively adsorb trace gold in the gold slag leachate.
3) The particle size of the adsorption resin provided by the invention can reach 300-1000 microns, and the industrial adsorption column packing and using requirements are met.
4) The gold recovery process by the adsorption resin is simple and convenient to operate, can efficiently and selectively recover gold, and is suitable for industrial popularization.
Compared with the prior art of recycling gold and palladium in electroplating waste liquid by using mercaptoamine chelate resin (CN85100240A), the invention utilizes the processes of radiation technology and the like to modify the surface of the polymer substrate to obtain the adsorption resin, the nitrogen element content of the surface of the adsorption resin accounts for more than 3 percent of the total mass of the adsorption resin, the sulfur element content of the surface of the adsorption resin accounts for more than 20 percent of the total mass of the adsorption resin, and the adsorption resin has the characteristics of high sulfur element and nitrogen element content (for example, the total content of nitrogen and sulfur is 37.4 percent); furthermore, the adsorption resin material with the surface having high contents of sulfur and nitrogen elements is applied to gold recovery, and the adsorption capacity of the adsorption resin for gold elements is greatly improved (up to 4656.9mg/g) due to higher functional group density, and the recovery rate of gold is also greatly improved (up to 95.17%). In addition, the invention adopts the leacheate to elute, concentrate and separate the gold loaded on the resin, thereby being more environment-friendly.
Compared with the prior art that the ion exchange recovery method of gold, platinum and palladium gold in acidic wastewater (CN101618898A) can only recover chemical alloy, the adsorption resin adopted by the method of the invention contains high-density nitrogen-sulfur functional groups, the adsorption of gold can be realized by ion exchange, oxidation reduction and chelation, and besides the recovery of chemical alloy, simple substance gold can be recovered. Hydrochloric acid, thiourea and H can be preferably used in the invention2O2The mixed solution of (2) can be used as an eluting solution, and particularly, simple gold can be eluted (of course, the chemical alloy can also be eluted). And, this prior art is directed to leaching wastewater obtained by leaching treatment of precious metal ore (this leaching treatment will simultaneously obtain slag); the invention aims at the slag obtained after the leaching treatment of the precious metal ore, and when the method is used for leaching again and carrying out subsequent treatment, the content of leached gold obtained from the slag is lower. In addition, the method of the invention is also suitable for recovering gold from secondary resources such as gold mine tailings and electronic garbage (such as waste circuit boards) and the like, which the prior art does not have.
The invention preferably adopts the ionizing radiation grafting method to prepare the adsorption resin with high density sulfur and nitrogen containing elements on the surface, compared with the chemical grafting method, the ionizing radiation grafting method can realize mass preparation and mass grafting; taking graft S as an example, the radiation method firstly introduces a large amount of epoxy groups of Glycidyl Methacrylate (GMA) on a cellulose substrate, and provides a basis for the subsequent introduction of a nitrogen-containing monomer. Because the thiolethane can continuously carry out nucleophilic substitution reaction with the intermediate containing nitrogen, the proportion of the sulfur element can be further increased.
In conclusion, the resin surface provided by the invention has high-density sulfur-containing and nitrogen-containing elements, can be used in a wider pH range, has higher adsorption capacity for hardware, and can meet the industrial filling and using requirements of adsorption columns. On the other hand, the adsorption resin with high density sulfur-containing nitrogen-containing elements on the surface of the resin can selectively and efficiently recover gold at ppb concentration level in the gold quartz tailing slag leachate, and can also efficiently recover trace gold from the electronic garbage leachate. The gold leaching process is simple to operate, gold can be efficiently and selectively recovered in the adsorption process, and the adsorbent is high in regeneration capacity and suitable for industrial popularization.
Drawings
FIG. 1 is the adsorption isotherm of the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin on high-concentration gold.
FIG. 2 is a diagram showing the effect of the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin on the recycling of gold. The ordinate Recovery (%) value in the figure was calculated from the elution amount to the adsorption amount.
FIG. 3 is a dynamic adsorption curve for selective recovery of gold from simulated wastewater; wherein (a) in FIG. 3 corresponds to the nitrogen-containing intermediate and (b) in FIG. 3 corresponds to the sulfur-containing nitrogen-containing adsorbent resin, and the abscissa axes BV each represent the ratio of the liquid volume to the column volume.
FIG. 4 is a graph showing the comparison of the adsorption efficiency of each metal element when the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin are used for recovering gold from the tailings leachate of pure quartz gold ore derived from Xinjiang.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Based on the method, low-grade gold-bearing materials such as gold slag, electronic garbage and the like are taken as starting raw materials, and the method can be divided into an adsorption process and a leaching process during specific operation. Specifically, low-grade gold-containing materials such as gold slag, electronic garbage and the like can be treated by an acid method; adjusting the pH value of the acidic leaching solution to 1-3; adding an adsorption resin with high sulfur and nitrogen content on the surface to adsorb gold (or flowing the leachate into an adsorption column of the adsorption resin with sulfur and nitrogen on the surface of a load resin through a peristaltic pump); and after adsorption, eluting and separating the gold loaded on the resin by using corresponding eluent.
The method of the present invention will be described in detail below with reference to a nitrogen-containing intermediate obtained by modifying the surface of a polymer substrate by radiation technology to obtain an adsorbent resin having a high sulfur and nitrogen content on the surface, and with reference to a nitrogen-containing intermediate obtained by this process (of course, in addition to this method, other methods such as chemical grafting method can be used to obtain an adsorbent resin having a sulfur and nitrogen content on the surface; for example, pentaethylenehexamine having a large nitrogen content in the monomer molecule can be preferably used as a functional monomer containing nitrogen to obtain a high-density nitrogen-containing intermediate material on the surface; further, ethylene sulfide can be used to perform a nucleophilic substitution reaction with nitrogen atoms of the introduced polyamines on the basis of the nitrogen-rich intermediate material to prepare an adsorbent resin having a high-density sulfur and nitrogen-containing elements on the surface of the material).
The polymer base material is crystalline cellulose microsphere with average particle size of 200 micrometer (certainly, other initial polymer base material with particle size, such as 150-300 micrometer, can be used, in addition, the degree of crystallinity of the cellulose microsphere can be optimized to 80% to ensure the strength, and certainly, the degree of crystallinity can be flexibly adjusted according to actual requirements, or other polymer can be used as the base material); the surface modification method comprises the steps of utilizing an electron beam pre-radiation grafting technology (irradiation dose is 20 kGy; of course, other irradiation doses can also be adopted, such as other irradiation doses within the range of 20 kGy-50 kGy) to graft Glycidyl Methacrylate (GMA) on the surface of a polymer substrate to introduce an epoxy group, and then carrying out ring-opening reaction on cellulose microspheres grafted with the epoxy group and mixed liquid of pentaethylenehexamine and N, N-dimethylformamide for 24 hours at the temperature of 80 ℃ at the solid-liquid ratio of 0.05g/mL to prepare the nitrogen-containing intermediate adsorption resin; continuously carrying out nucleophilic substitution reaction on the nitrogen-containing intermediate resin and 10% ethylene sulfide ethanol solution at a solid-to-liquid ratio of 0.05g/mL to prepare a high-density sulfur-containing and nitrogen-containing adsorption resin material; the preparation process route is as follows (only one graft chain is drawn on the polymer base material as an example, the number of the graft chains on the same polymer base material particle may actually be multiple; certainly, if no pentaethylenehexamine monomer is adopted, but other polyethylene polyamine monomers are adopted, the number m of the N element repeating units in the sulfur-containing nitrogen-containing adsorption resin also changes correspondingly, the value of the S element repeating unit N is influenced by the amount of the ethylene sulfide, generally can be 1-10, and certainly, in consideration of the sufficient degree of the reaction, the possibility that N on a certain branch chain connected with N is 0, even the branch chain is not grafted successfully, and N still exists in the form of imine) exists:
the high-density sulfur-containing and nitrogen-containing adsorbent resin material (total nitrogen and sulfur content of 37.4%) was synthesized to contain high-density nitrogen and sulfur atoms (specific contents of each element are shown in table 1 above). After grafting, the average particle size of the whole adsorption resin is 300-1000 microns.
Example 1 adsorption isotherm test of nitrogen-containing intermediates and sulfur-containing nitrogen-containing adsorbent resins (37.4% total nitrogen and sulfur) on high concentrations of gold
0.01g of the adsorption resin was weighed and put into 10mL of an aqueous solution containing Au (III) at 35 ℃ to perform a static Batch adsorption experiment. The Au (III) solution for the adsorption experiment was prepared from chloroauric acid. After adsorbing at Natural pH for a while, the supernatant was filtered off with a filter, and the residual concentration of Au (III) was measured by ICP-OES to calculate the amount of adsorbed Au (Q)e)。
The adsorption isotherms of the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin (total nitrogen and sulfur content: 37.4%) for gold are shown in fig. 1. As can be seen from the figure, compared with the nitrogen-containing intermediate, the sulfur-containing nitrogen-containing adsorption resin (the total content of nitrogen and sulfur is 37.4%) has an ultrahigh adsorption capacity on gold, the adsorption amount reaches 4656.9mg/g, and the adsorption process conforms to the Langmuir adsorption model. Moreover, comparing the adsorption capacity of the sulfur-containing and nitrogen-containing adsorption resin to gold with other adsorption materials in the prior art, the adsorption resin of the present invention shows an ultra-high adsorption capacity to gold (as shown in table 2).
TABLE 2 comparison of gold adsorption capacities of the present invention and other prior art adsorption materials
Example 2 experiment for recycling high-concentration gold by nitrogen-containing intermediate and sulfur-containing nitrogen-containing adsorption resin (total content of nitrogen and sulfur is 37.4%)
0.01g of the adsorbent resin was weighed and charged into 10mL of an aqueous solution containing Au (III) at 35 ℃. After adsorption at the Natural pH for a while, the supernatant was filtered off with a filter head, and the au (iii) residual concentration was measured with AAS and the recovery rate was calculated. The gold-loaded resin was washed three times with deionized water, to which 1mol/L HCl, 0.25mol/L thiourea and 0.5% H were added2O2And mixing the eluates for elution. The resin for each adsorption experiment is washed three times by deionized water and then circulated for the next time. This was repeated five times.
The experiment of the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin (the total content of nitrogen and sulfur is 37.4%) for adsorbing and recycling gold is shown in fig. 2. It can be shown from the figure that after five cycles, the adsorption capacities of the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin (total nitrogen and sulfur content is 37.4%) on gold are basically kept unchanged, which indicates that the two materials have better reusability in the gold recovery process.
Example 3 dynamic adsorption experiment for recovering gold from simulated wastewater by nitrogen-containing intermediate and sulfur-containing nitrogen-containing adsorption resin (total content of nitrogen and sulfur is 37.4%)
The resin was packed in an adsorption column in a wet state, and dynamic adsorption evaluation conditions were as follows: the volume of the adsorption column is 3mL, the amounts of the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin are 2.4777g and 2.6644g respectively, the concentrations of Au (III), Cu (II), Fe (III), Zn (II), Ni (II) are 0.1mmol/L, and the flow rate is 1.5mL/min (SV ═ 30 h)-1)。
The dynamic adsorption experimental evaluation was performed according to the above experimental conditions, and the breakthrough curves of fig. 3 were obtained by sampling analysis at specific time intervals. The result shows that the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin (the total content of nitrogen and sulfur is 37.4%) can selectively recover gold. At the beginning of the experiment, Cu (II), Fe (III), Zn (II), Ni (II) leaked out completely, indicating that the resin had no force on it. The leakage point of the nitrogen-containing intermediate to gold occurs at 42000BV, and when the nitrogen-containing intermediate reaches the adsorption saturation, the adsorption capacity reaches 942 g/L. Compared with the nitrogen-containing intermediate, the sulfur-containing nitrogen-containing adsorption resin (the total content of nitrogen and sulfur is 37.4%) lags the leakage point of gold (140000BV), and when the adsorption saturation is reached, the adsorption quantity (3110g/L) is far higher than that of the nitrogen-containing intermediate material.
Example 4 acid leaching of gold from gold slag
Ball-milling gold slag to below 100 μm by using a ball mill, weighing 20g of slag, and stirring in 40mL of concentrated hydrochloric acid for 20 min; adding 60mL of dilute aqua regia (concentrated hydrochloric acid: concentrated nitric acid: water: 3:4:1 in volume ratio) into the solution, stirring for 24 hours, and centrifugally separating slag; finally, sodium hydroxide solution was added to the leachate to adjust the pH to 3. The ICP-MS test shows that the gold concentration of the leachate with the pH value of 3 is 26.1 ppb.
EXAMPLE 5 static adsorption testing of Nitrogen-containing intermediates and Sulfur-containing Nitrogen-containing adsorbent resins (37.4% total Nitrogen and Sulfur) on Low-concentration gold in leach liquors
0.01g of an adsorbent resin was weighed and placed in 10mL of the leachate of example 4 at 35 ℃ to conduct a static Batch adsorption experiment. After adsorbing for 24h, filtering the supernatant by using a filter head, detecting the concentration of metal ions in the leachate by using ICP-MS and ICP-OES, and calculating the adsorption efficiency.
The results of the above experiments are shown in fig. 4 and table 3, where the nitrogen-containing intermediate has an adsorption efficiency of 78.24% for gold in the presence of excess co-leaching ions. Compared with the nitrogen-containing intermediate, the sulfur-containing nitrogen-containing adsorption resin (the total content of nitrogen and sulfur is 37.4%) can selectively recover gold with higher efficiency due to the synergistic effect of functional atoms (N and S), the recovery rate is as high as 95.17%, and the resin hardly adsorbs other co-impregnated ions (as shown in Table 3).
TABLE 3 analysis of the composition of gold slag leachate before and after adsorption
Remarking: au concentration unit is ppb; the concentration of the other metal elements except Au was in mg/L shown in the first row of Table 3
EXAMPLE 6 dynamic adsorption testing of Nitrogen-containing intermediates and Sulfur-containing Nitrogen-containing adsorbent resins (37.4% total Nitrogen and Sulfur) on Low-concentration gold in leach liquors
To evaluate the applicability of the adsorption resin to low-concentration gold recovery, 200mL of the leachate from example 4 was flowed by a peristaltic pump into an adsorption column containing the adsorption resin. Dynamic adsorption evaluation conditions: the volume of the adsorption column is 1mL, the amounts of the two resins are 0.6058 and 0.5426g respectively, and the flow rate is 0.33mL/min (SV is 20 h)-1)，pH＝3。
ICP-MS test results show that compared with the nitrogen-containing intermediate, the sulfur-containing nitrogen-containing adsorption resin (the total content of nitrogen and sulfur is 37.4%) can recover gold better selectively.
EXAMPLE 7 Nitrogen-containing intermediates and Sulfur-containing Nitrogen-containing adsorbent resins (37.4% total Nitrogen and Sulfur) recovery of Low concentrations of gold from computer CPU leach liquors
The pH of a circuit board leachate obtained from chinese gold was adjusted to 3 using NaOH and HCl. The ICP-MS test shows that the gold concentration of the leachate with the pH value of 3 is 15 ppb. 0.01g of an adsorbent resin was weighed and placed in 10mL of the above leachate at 35 ℃ to conduct a static Batch adsorption experiment. After adsorbing for 24h, filtering the supernatant by using a filter head, detecting the concentration of metal ions in the leachate by using ICP-MS and ICP-OES, and calculating the adsorption efficiency.
ICP-MS test results show that the recovery rates of the nitrogen-containing intermediate and the sulfur-containing nitrogen-containing adsorption resin (the total content of nitrogen and sulfur is 37.4%) to trace gold in computer CPU leachate reach 50.19% and 64.66% respectively, and the two resins have certain enrichment capacity to low-concentration gold in circuit board leachate.
Although the above examples are all the adsorption resins with surface N element content of 3.87% and surface S element content of 33.53%, the adsorption resins with N, S content higher or lower than 3.87% and 33.53% can achieve the equivalent technical effect (of course, the higher the surface N, S content is, the better the recovery effect is). For example, if higher N, S content adsorbent resins are to be prepared, this can be achieved by increasing the ratio of polyethylene polyamine and ethylene sulfide in the solvent. If lower N, S content adsorbent resins are to be prepared, this can be achieved by reducing the ratio of polyethylenepolyamine and ethylene sulfide in the solvent. In addition, considering that the content of N and S elements is often lower than 15% after conversion of the adsorption resin reported in the prior art (correspondingly, the adsorption capacity of the adsorption resin under the condition is generally not higher than 2000mg/g), the surface N content of the adsorption resin adopted by the method of the invention is required to be not lower than 3%, and the surface S content is required to be not lower than 20%, and the adsorption resin with the effect of ultrahigh adsorption capacity can be realized.
The reagents used in the examples were commercially available except for those specifically mentioned.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (13)
1. A method for recovering gold by using adsorption resin is characterized by comprising the following steps:
(S1) adjusting the pH value of the gold-containing leaching solution containing gold ions to 1-3, and then adding adsorption resin into the gold-containing leaching solution to adsorb the gold ions in the gold-containing leaching solution;
wherein the surface of the adsorption resin is provided with sulfur and nitrogen; the nitrogen content of the surface of the adsorption resin accounts for more than 3% of the total mass of the adsorption resin, and the sulfur content of the surface of the adsorption resin accounts for more than 20% of the total mass of the adsorption resin;
(S2) after adsorption, eluting, concentrating, separating and regenerating the gold loaded on the adsorption resin obtained by the step (S1) by using eluent, and recovering the gold;
wherein, in the step (S1), the adsorption resin has a chemical structure represented by the following formula (I) or formula (II):
wherein n is an integer of 1-10; m is an integer of 2-7;
represents a polymeric substrate.
2. The method according to claim 1, wherein in the step (S1), the sulfur content on the surface of the adsorbent resin is 30% or more of the total mass of the adsorbent resin.
3. The method of claim 1, wherein the adsorbent resin is obtained by surface modification of a polymeric substrate; wherein the polymeric substrate is selected from: cellulose or its derivatives, polyethylene, polypropylene, polystyrene-divinylbenzene type copolymers, ethylene-vinyl alcohol copolymers, polyamides; the surface modification is carried out by adopting an ionizing radiation grafting method or a chemical grafting method;
wherein the cellulose or the derivative thereof has a crystallinity of 80% or more.
4. The method according to claim 3, wherein the ionizing radiation grafting method is an electron beam pre-irradiation grafting method, and comprises the following steps: grafting glycidyl methacrylate on the surface of a high molecular base material by using an electron beam pre-irradiation grafting method to introduce an epoxy group, and then introducing a polyethylene polyamine monomer through a ring-opening reaction to prepare a nitrogen-containing intermediate material with a nitrogen element on the surface; and then, continuously carrying out nucleophilic substitution reaction on the ethylene sulfide and nitrogen atoms on the nitrogen-containing intermediate material to prepare the adsorption resin with the sulfur element and the nitrogen element on the surface.
5. The method of claim 4, wherein the electron beam pre-irradiation grafting method uses a radiation dose of 20-50 kGy.
6. The method according to claim 3, wherein the surface modification comprises in particular the steps of:
(1) firstly, grafting an epoxy group and introducing the epoxy group into the surface of a high-molecular base material, and then introducing a polyethylene polyamine monomer through an epoxy ring-opening reaction to obtain a nitrogen-containing intermediate material with a nitrogen element on the surface;
or grafting vinyl benzyl chloride, introducing the vinyl benzyl chloride onto the surface of a polymer substrate, and introducing a polyethylene polyamine monomer through a halogenation reaction to obtain a nitrogen-containing intermediate material with a nitrogen element on the surface;
(2) and (2) carrying out nucleophilic substitution reaction on the nitrogen-containing intermediate material obtained in the step (1) by using ethylene sulfide and nitrogen atoms of the introduced polyethylene polyamines, thereby preparing the adsorption resin with the surface containing sulfur elements and nitrogen elements.
7. The method according to any one of claims 4 to 6, wherein the polyethylene polyamine-based monomer is selected from the group consisting of: ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine.
8. The method of claim 7, wherein the polyethylene polyamine monomer is pentaethylenehexamine.
9. The method according to claim 1, wherein in the step (S1), the adsorbent resin is a spherical material having an average particle size of 300 to 1000 μm.
10. The method according to claim 1, wherein in the step (S1), the pH is adjusted by using sodium hydroxide solution;
if the gold-containing solid material contains carbonate, the gold-containing leaching solution is prepared by crushing the gold-containing solid material, soaking the crushed gold-containing solid material in hydrochloric acid to remove the carbonate, adding aqua regia into the crushed gold-containing solid material to leach gold, and filtering the gold-containing solid material to obtain filtrate; if the gold-containing solid material does not contain carbonate, crushing the gold-containing solid material, directly adding the crushed gold-containing solid material into aqua regia for gold leaching, and filtering to obtain filtrate;
wherein:
hydrochloric acid for removing carbonate, the concentration of which is 0.01mol/L-5 mol/L; the ratio of the mass of the crushed gold-containing ore or slag to the volume of the hydrochloric acid is less than or equal to 0.5 g/mL; the soaking time of the soaking is less than 2 hours;
the gold-containing solid material is at least one of low-grade gold ore, gold mine tailing slag, electronic components containing gold elements, alloys containing the gold elements and jewelry waste; wherein the gold element content of the low-grade gold ore is not more than 0.6 g/t;
the aqua regia is dilute aqua regia, and the volume ratio of corresponding concentrated hydrochloric acid to concentrated nitric acid to water is (1-3): (1-8): 1, wherein the mass percentage concentration of the concentrated hydrochloric acid is 37.2%, and the mass percentage concentration of the concentrated nitric acid is 69.8%; the leaching time for gold leaching is 1-24 h.
11. The method according to claim 1, wherein the gold-containing leachate has a pH adjusted to a concentration of gold ions of 1ppb or more.
12. The method of claim 11, wherein the concentration of gold ions is from 1ppb to 500 ppb.
13. The method according to claim 1, wherein the eluent is 0.1-3 mol/L hydrochloric acid, or a mixture of hydrochloric acid and thiourea having a final concentration of 0.1-3 mol/L and thiourea of 0.1-0.5 mol/L, or a mixture of hydrochloric acid having a final concentration of 0.1-3 mol/L, thiourea of 0.1-0.5 mol/L and H2O2Hydrochloric acid, thiourea and H with final concentration of 0.5-5%2O2The mixed solution of (1).
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