A method for recovering trace amounts of gold and silver in the sintering machine head ash treatment solution by resin adsorption method

Abstract

The present invention provides a method for recovering trace gold and silver in the treatment solution of sintering machine head ash by resin adsorption, belonging to the technical field of solid waste resource recovery. The pH of the treatment solution of the sintering machine head is adjusted with an alkali solution, and the anion resin is used for multi-stage adsorption of the post-treatment liquid. The gold and silver are desorbed from the resin with an alkali solution, and finally gold ingots and silver ingots are obtained after reduction smelting. The process of the present invention is simple, effectively recovers the trace gold and silver in the treatment solution of sintering machine head ash, has low cost and no secondary pollution, and is an optimal solution for the recovery and utilization of trace precious metals in solid waste resources.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource recovery, and particularly relates to a method for recovering trace gold and silver in the sintering machine head ash treatment solution by resin adsorption method. Background Art

[0002] Gold and silver, as important strategic resources of the country, can be applied to various fields such as instruments, medicine, chemical industry, communication, and aerospace. China is a country rich in gold and silver ore resources. The gold mines are mainly concentrated in 6 provinces such as Shandong and Henan, and the main types are placer gold, lode gold, and associated gold; the silver mines are mainly concentrated in provinces such as Jiangxi and Guangdong, and the main types are electrum, argentite, etc. At present, the extraction and smelting processes for gold and silver ores are mainly divided into three types: pyrometallurgical process, combined beneficiation and smelting process, and hydrometallurgical process. The pyrometallurgical process is mature, easy to operate and control, and suitable for large-scale production, but the production cycle is long, the equipment and raw materials are consumed greatly, and there is environmental pollution; the combined beneficiation and smelting process first enriches precious metals such as gold and silver by flotation method, and then recovers them step by step by methods such as electrolysis. The gold and silver obtained by this method have high purity and small loss, but a large amount of flotation reagents are required, the flotation recovery rate is low, the equipment requirements are high, and the cost investment is large; the hydrometallurgical process leaches gold and silver in the ore into the solution by wet leaching, and then recovers the gold and silver therein by methods such as displacement, reduction, and extraction. This method has simple process, small investment, and high direct recovery rate of gold and silver, but this method often requires pretreatment of the ore to extract gold and silver, and toxic gases such as ammonia, chlorine, and nitrogen oxides will be generated during the subsequent gold and silver purification process, and the working environment is harsh.

[0003] In addition to extracting gold and silver directly from gold and silver ores, extracting and recovering from metal smelting waste is also an important way to obtain gold and silver, such as recovering gold and silver precious metals from secondary resources such as electrolytic zinc anode mud, mine tailings, beneficiation waste slag, and industrial wastewater. Among them, the sintering process of the steel plant causes a large amount of valuable metals to be enriched in the machine head ash after repeated ore matching and enrichment. These machine head ash have low iron grade and complex composition and cannot be directly used. Fire treatment not only causes environmental pollution, but also causes resource waste, so wet extraction of valuable metals is a more appropriate method for treating machine heads. At present, the methods for recovering trace gold and silver from solutions mainly include: replacement method, extraction method, adsorption method, etc. Chinese patent CN 113713960 B announced "a method for cascade neutralization and cascade flotation of polymetallic acidic wastewater", which uses zinc powder to replace gold and silver in acidic wastewater, and then extracts copper and zinc from acidic wastewater by cascade flotation, realizing the multi-stage utilization of polymetallic acidic wastewater. Chinese patent CN114807599 A discloses "a process suitable for treating barium sulfate slag in copper anode mud". This method uses hydrogenation leaching-zinc powder replacement to enrich gold and silver in barium sulfate slag, and then refines it by nitric acid silver separation method to obtain gold and silver with high purity. However, the gold and silver obtained by this method are not of high purity, and subsequent refining treatment is required to recover the gold and silver therein, and dangerous goods such as sodium cyanide and nitric acid are required. Improper disposal will also cause environmental pollution. Chinese patent CN 113046561 A discloses "a device and method for graded extraction of gold, silver and palladium precious metals from waste circuit boards". This method uses thiocyanate to leach gold and silver under acidic conditions, then uses dibutyl carbitol to extract gold, oxalic acid to strip gold, and finally reduces it to obtain gold, and replaces it with iron powder to obtain silver. The gold and silver obtained by this method have a high purity, which can reach more than 99.9%, but it is only applicable to precious liquids with high gold content, and a large amount of extractant is used, resulting in large losses and difficult stripping. Chinese patents CN 108034805 A, CN 108950204 A, and CN 117867273A all use activated carbon to adsorb the precious metals of gold and silver in the solution. The adsorption effect is good and the recovery rate of gold and silver is high. However, desorption is difficult. It is necessary to use pyrometallurgy to obtain the gold-silver alloy, and it is also necessary to separate the silver with nitric acid to obtain the gold and silver elements. The amount of activated carbon used is large and cannot be recycled. In addition, the adsorption process will also adsorb other impurity ions, affecting the purity of gold and silver. At the same time, if the adsorbed liquid contains organic matter, it will also cause the activated carbon to be rapidly deactivated, affecting the adsorption performance.

[0004] In summary, the following problems exist in the current hydrometallurgical process for extracting gold and silver: 1. To obtain a higher leaching rate, cyanide is usually used as a leaching agent. Cyanide is a highly toxic substance, and improper handling can seriously endanger human health and cause environmental pollution; 2. The consumption of the extractant is large, and stripping is difficult. It has a good enrichment effect on the precious gold and silver solution, but has a poor treatment effect on the lean gold and silver solution, resulting in a high cost; 3. The gold and silver alloy after enrichment often needs to be refined to obtain relatively pure gold and silver. Refining requires a high purity of gold and silver and fewer impurities, and the treatment effect on the gold and silver alloy with complex components is not ideal. The resin adsorption method can be used to solve the above problems, without using toxic and harmful substances, having a high selectivity for gold and silver, and being relatively convenient for desorption. The desorbed resin can be reused for adsorbing gold and silver again. Summary of the Invention

[0005] The object of the present invention is to provide a method for recovering trace gold and silver in the sintering machine head ash treatment solution by the resin adsorption method, without using highly toxic agents such as cyanide, having a large adsorption capacity, good adsorption selectivity, high desorption efficiency, the desorbed resin can be reused for adsorbing gold and silver again, having a wide application range, the gold and silver concentration that can be adsorbed is 0.01mg / L - 100mg / L, can treat complex solutions containing various metal ions, with a simple process, easy to control, no environmental pollution, and suitable for industrial production.

[0006] The technical solution of the present invention is realized as follows:

[0007] The present invention provides a method for recovering trace gold and silver in the sintering machine head ash treatment solution by the resin adsorption method, comprising the following steps:

[0008] The first step: adjusting the pH of the sintering machine head ash treatment solution to 6 - 9 with an alkali solution to obtain a lean gold and silver solution;

[0009] The second step: passing the gold and silver-containing solution through 1 - 3 stages of ion adsorption columns in sequence to obtain a gold and silver-rich resin and an adsorbed solution;

[0010] The third step: desorbing the gold and silver-rich resin with acidic thiourea to obtain a gold and silver-rich solution and an anion resin, and returning the desorbed resin to the second step to continue adsorbing gold and silver;

[0011] The fourth step: adding a reducing agent to the gold and silver-rich solution for reduction, and performing solid-liquid separation after the reaction is completed to obtain gold and silver alloy powder, and sending the gold and silver alloy powder to a refining system to obtain gold ingots and silver ingots.

[0012] As a further improvement of the present invention, in the first step, the alkali solution used to adjust the solution pH is one or several of sodium hydroxide, potassium hydroxide, and calcium hydroxide solutions, the concentration of the alkali solution used is 100 - 200g / L, and the addition method is adding under stirring, and the stirring time is 0.5 - 1.5h.

[0013] As a further improvement of the present invention, the anion resin used in the second step is one or more of ethylene glycol silane copolymer C410 and cross-linked polystyrene type anion exchange resin A-21S. The adsorption temperature is room temperature, the pump used is a high-power peristaltic pump, and the flow rate is controlled at 5-10 BV / h.

[0014] As a further improvement of the present invention, the acidic thiourea used in the third step is a mixed solution of sulfuric acid and thiourea, wherein the mass fraction of sulfuric acid is 1-3%, and the mass fraction of thiourea is 8-10%.

[0015] As a further improvement of the present invention, the reducing agent used in the fourth step is one or more of sodium sulfite, sodium bisulfite, zinc powder, zinc wire, hydrazine hydrate, and oxalic acid. The addition amount of the reducing agent is 100-120% of the measured value of the gold and silver content in the desorbing solution. The reduction temperature is room temperature, and the reduction time is 0.5-1.5 h.

[0016] As a further improvement of the present invention, the anion resin is a modified ethylene glycol silane copolymer, and the preparation method is as follows:

[0017] S1. Add ethylene glycol silane copolymer C410 into Tris-HCl solution, add dopamine hydrochloride, heat and stir for reaction, filter, wash, and dry to obtain polydopamine-modified ethylene glycol silane copolymer;

[0018] S2. Add polydopamine-modified ethylene glycol silane copolymer C410 into Tris-HCl solution, add tannic acid, heat and stir for reaction, filter, wash, and dry to obtain the modified ethylene glycol silane copolymer.

[0019] The anion resin of the present invention is a modified ethylene glycol silane copolymer. After polydopamine modification and tannic acid modification are carried out in sequence, the ethylene glycol silane copolymer is provided with abundant active groups such as amino, carboxyl, and hydroxyl groups, which can fix heavy metal ions by forming various complex bonds, have a large adsorption capacity, a high adsorption rate, do not use highly toxic agents such as cyanide, have a high desorption efficiency, and the desorbed resin can be used for adsorbing gold and silver again, with a wide application range.

[0020] As a further improvement of the present invention, the pH value of the Tris-HCl solution is 8.5-9.5.

[0021] As a further improvement of the present invention, the mass ratio of ethylene glycol silane copolymer C410 to dopamine hydrochloride is 10:2-3.

[0022] As a further improvement of the present invention, the mass ratio of polydopamine-modified ethylene glycol silane copolymer C410 to tannic acid is 10:3-4.

[0023] As a further improvement of the present invention, the temperature of the heating and stirring reaction is 40-50 °C, and the time is 3-5 h.

[0024] The present invention has the following beneficial effects:

[0025] The present invention uses the resin adsorption method to recover trace gold and silver in the sintering machine head ash treatment solution, uses acidic thiourea for desorption, and then obtains gold ingots and silver ingots through reduction smelting. It does not use highly toxic agents such as cyanide, has a large adsorption capacity, good adsorption selectivity, high desorption efficiency, and the desorbed resin can be reused for adsorbing gold and silver. It has a wide application range, can adsorb gold and silver with a concentration of 0.01 mg / L - 100 mg / L, can treat complex solutions containing multiple metal ions, has a simple process, is easy to control, does not pollute the environment, and is suitable for industrial production. Specific embodiments

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Preparation Example 1 Preparation of modified ethylene glycol silane copolymer

[0028] The method is as follows:

[0029] S1. Add 10 g of ethylene glycol silane copolymer C410 to a Tris-HCl solution with a pH value of 8.5, add 2 g of dopamine hydrochloride, heat to 40 °C, stir and react for 3 h, filter, wash, and dry to obtain a polydopamine-modified ethylene glycol silane copolymer;

[0030] S2. Add 10 g of the polydopamine-modified ethylene glycol silane copolymer C410 to a Tris-HCl solution with a pH value of 8.5, add 3 g of tannic acid, heat to 40 °C, stir and react for 3 h, filter, wash, and dry to obtain a modified ethylene glycol silane copolymer.

[0031] Preparation Example 2 Preparation of modified ethylene glycol silane copolymer

[0032] The method is as follows:

[0033] S1. Add 10 g of ethylene glycol silane copolymer C410 to a Tris-HCl solution with a pH value of 9.5, add 3 g of dopamine hydrochloride, heat to 50 °C, stir and react for 5 h, filter, wash, and dry to obtain a polydopamine-modified ethylene glycol silane copolymer;

[0034] S2. Add 10 g of polydopamine-modified ethylene glycol silane copolymer C410 to a Tris-HCl solution with a pH value of 9.5, add 4 g of tannic acid, heat to 50 °C, stir and react for 5 h, filter, wash, and dry to obtain the modified ethylene glycol silane copolymer.

[0035] Comparative Preparation Example 1 is different from Preparation Example 2 in that step S1 is not carried out.

[0036] Specifically as follows:

[0037] Add 10 g of ethylene glycol silane copolymer C410 to a Tris-HCl solution with a pH value of 9.5, add 4 g of tannic acid, heat to 50 °C, stir and react for 5 h, filter, wash, and dry to obtain the modified ethylene glycol silane copolymer.

[0038] Comparative Preparation Example 2 is different from Preparation Example 2 in that step S2 is not carried out.

[0039] Specifically as follows:

[0040] Add 10 g of ethylene glycol silane copolymer C410 to a Tris-HCl solution with a pH value of 9.5, add 3 g of dopamine hydrochloride, heat to 50 °C, stir and react for 5 h, filter, wash, and dry to obtain the modified ethylene glycol silane copolymer. Example 1:

[0041] The composition of the sintering machine head ash treatment solution of a certain iron and steel plant is shown in Table 1 below:

[0042] Table 1 Composition of the sintering machine head ash treatment solution

[0043]

[0044] As shown in Table 1, the precious metal content in the head ash treatment liquor is low, and it contains other impurity ions. Use a 100 g / L sodium hydroxide solution to adjust the pH of the solution to 6, stir for 0.5 h, and then perform solid-liquid separation to obtain a poor gold and silver solution, the composition of which is shown in Table 2 below.

[0045] Table 2 Composition of the poor gold and silver solution

[0046]

[0047] As shown in Table 2, use a peristaltic pump to pass the above-mentioned poor gold and silver solution through a 3-stage ethylene glycol silane copolymer C410 resin adsorption column at a flow rate of 5 BV / h to obtain a gold and silver-rich resin and an adsorbed solution, and the composition of the adsorbed solution is shown in Table 3 below.

[0048] Table 3 Composition of the adsorbed solution

[0049]

[0050] Desorb the gold- and silver-rich resin with 1% sulfuric acid and 8% thiourea to obtain a gold- and silver-rich solution. The desorbed resin is returned to the second step for re-adsorption. Sodium sulfite is added to the gold- and silver-rich solution for reduction. The addition amount of sodium sulfite is 100% of the measured value of gold and silver ions in the solution. The reduction temperature is room temperature, and the reduction time is 0.5 h. After the reaction is completed, solid-liquid separation is carried out to obtain gold-silver alloy powder, which is then sent to the refining system to obtain gold ingots and silver ingots. Example 2:

[0051] The composition of the sintering machine head ash treatment solution of a certain steel plant is shown in Table 4 below:

[0052] Table 4 Composition of the sintering machine head ash treatment solution

[0053]

[0054] As shown in Table 4, the precious metal content in the head ash treatment feed liquid is low, and it contains other impurity ions. Adjust the pH of the solution to 7 with 150 g / L sodium hydroxide solution, stir for 1 h, and then carry out solid-liquid separation to obtain a gold- and silver-poor solution. The composition of the solution is shown in Table 5 below.

[0055] Table 5 Composition of the gold- and silver-poor solution

[0056]

[0057] As shown in Table 5, use a peristaltic pump to pass the above gold- and silver-poor solution through the modified ethylene glycol silane copolymer resin adsorption column prepared in Preparation Example 1 at a flow rate of 8 BV / h to obtain a gold- and silver-rich resin and the post-adsorption liquid. The composition of the post-adsorption liquid is shown in Table 6 below.

[0058] Table 6 Composition of the post-adsorption liquid

[0059]

[0060] Desorb the gold- and silver-rich resin with 2% sulfuric acid and 9% thiourea to obtain a gold- and silver-rich solution. The desorbed resin is returned to the second step for re-adsorption. Sodium sulfite is added to the gold- and silver-rich solution for reduction. The addition amount of sodium sulfite is 110% of the measured value of gold and silver ions in the solution. The reduction temperature is room temperature, and the reduction time is 1 h. After the reaction is completed, solid-liquid separation is carried out to obtain gold-silver alloy powder, which is then sent to the refining system to obtain gold ingots and silver ingots. Example 3:

[0061] The composition of the sintering machine head ash treatment solution of a certain steel plant is shown in Table 7 below:

[0062] Table 7 Composition of the sintering machine head ash treatment solution

[0063]

[0064] As shown in Table 7, the noble metal content in the head ash treatment liquor is low, and it contains other impurity ions. The pH of the solution is adjusted to 8 with 200 g / L sodium hydroxide solution, and after stirring for 1.5 h, a lean gold and silver solution is obtained by solid-liquid separation. Its component composition is shown in Table 8 below.

[0065] Table 8 Component Composition of Lean Gold and Silver Solution

[0066]

[0067] As shown in Table 8, the above-mentioned lean gold and silver solution is passed through the modified ethylene glycol silane copolymer resin adsorption column prepared in Preparation Example 2 at a flow rate of 8 BV / h using a peristaltic pump to obtain a rich gold and silver resin and an adsorbed solution. The component composition of the adsorbed solution is shown in Table 9 below.

[0068] Table 9 Component Composition of Adsorbed Solution

[0069]

[0070] The rich gold and silver resin is desorbed with 3% sulfuric acid and 10% thiourea to obtain a rich gold and silver solution. The desorbed resin is returned to the second step for re-adsorption. Sodium sulfite is added to the rich gold and silver solution for reduction. The addition amount of sodium sulfite is 120% of the measured value of gold and silver ions in the solution. The reduction temperature is room temperature, and the reduction time is 1.5 h. After the reaction is completed, solid-liquid separation is carried out to obtain gold-silver alloy powder, which is then sent to the refining system to obtain gold ingots and silver ingots.

[0071] The difference between Comparative Example 1 and Example 3 is that the modified ethylene glycol silane copolymer resin is prepared from Comparative Preparation Example 1.

[0072] The component composition of the adsorbed solution is shown in Table 10 below.

[0073] Table 10 Component Composition of Adsorbed Solution

[0074]

[0075] The difference between Comparative Example 2 and Example 3 is that the modified ethylene glycol silane copolymer resin is prepared from Comparative Preparation Example 2.

[0076] The component composition of the adsorbed solution is shown in Table 11 below.

[0077] Table 11 Component Composition of Adsorbed Solution

[0078]

[0079] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recovering trace amounts of gold and silver in the sintering machine head ash treatment solution by resin adsorption method, characterized in that, It includes the following steps: The first step: Adjust the pH of the sintering machine head ash treatment solution to 6-9 with an alkali solution to obtain a poor gold and silver solution; The second step: Pass the gold and silver-containing solution through 1-3 ion adsorption columns in sequence to obtain a gold and silver-rich resin and an adsorbed solution; The ion adsorption column used in the second step is an anion resin, specifically a modified ethylene glycol silane copolymer, and its preparation method is as follows: S1. Add ethylene glycol silane copolymer C410 to a Tris-HCl solution, add dopamine hydrochloride, heat and stir to react, filter, wash, and dry to obtain a polydopamine-modified ethylene glycol silane copolymer; S2. Add the polydopamine-modified ethylene glycol silane copolymer C410 to a Tris-HCl solution, add tannic acid, heat and stir to react, filter, wash, and dry to obtain a modified ethylene glycol silane copolymer; The mass ratio of the polydopamine-modified ethylene glycol silane copolymer C410 to tannic acid is 10:3-4; The mass ratio of the ethylene glycol silane copolymer C410 to dopamine hydrochloride is 10:2-3; The third step: Desorb the gold and silver-rich resin with acidic thiourea to obtain a gold and silver-rich solution and an anion resin, and the desorbed resin returns to the second step to continue adsorbing gold and silver; The fourth step: Add a reducing agent to the gold and silver-rich solution for reduction. After the reaction is completed, perform solid-liquid separation to obtain gold-silver alloy powder, and the gold-silver alloy powder is sent to a refining system to obtain gold ingots and silver ingots.

2. The method according to claim 1, wherein: In the first step, the alkali solution used to adjust the solution pH is one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide solutions. The concentration of the alkali solution used is 100-200 g / L, and the addition method is to add it under stirring, and the stirring time is 0.5-1.5 h.

3. The method according to claim 1, wherein: In the second step, the adsorption temperature is room temperature, the pump used is a high-power peristaltic pump, and the flow rate is controlled at 5-10 BV / h.

4. The method according to claim 1, wherein: In the third step, the acidic thiourea used is a mixed solution of sulfuric acid and thiourea, where the mass fraction of sulfuric acid is 1-3% and the mass fraction of thiourea is 8-10%.

5. The method according to claim 1, wherein: In the fourth step, the reducing agent used is one or more of sodium sulfite, sodium bisulfite, zinc powder, zinc wire, hydrazine hydrate, and oxalic acid. The addition amount of the reducing agent is 100-120% of the measured value of the gold and silver content in the desorbing solution. The reduction temperature is room temperature, and the reduction time is 0.5-1.5 h.

6. The method according to claim 1, wherein: The pH value of the Tris-HCl solution is 8.5-9.

5.

7. The method according to claim 1, characterized in that: The temperature of the heating and stirring reaction is 40-50 °C, and the time is 3-5 h.

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