Method for recycling trace gold and silver in sintering machine head ash treatment solution through resin adsorption method

Abstract

The invention provides a method for recycling trace gold and silver in a sintering machine head ash treatment solution through a resin adsorption method, and belongs to the technical field of solid waste resource recycling. Alkali liquor is used for adjusting the pH of the solution treated by the sintering machine head, anion resin is used for multi-stage adsorption of the treated feed liquid, the alkali liquor is used for separating gold and silver from the resin, and finally gold ingots and silver ingots are obtained after reduction smelting. The process is simple, trace gold and silver in the sintering machine head ash treatment solution are effectively recovered, the cost is low, secondary pollution is avoided, and the method is an optimal scheme for recovering and utilizing trace precious metal in solid waste resources.

Description

Technical Field

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

[0002] As important strategic resources of the country, gold and silver can be applied to various fields such as instrumentation, medical treatment, chemical industry, communication, aerospace, etc. my country is a country with relatively rich gold and silver mine resources. Gold mines are mainly concentrated in six provinces such as Shandong and Henan, and the main types are placer gold, rock gold and associated gold; silver mines are mainly concentrated in provinces such as Jiangxi and Guangdong, and the main types are silver-gold mines and silver-gold mines. At present, there are three main types of extraction and smelting processes for gold and silver mines: pyrometallurgical smelting process, beneficiation and smelting combined process, and hydrometallurgical smelting 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 material losses are large, and there is environmental pollution; the combined beneficiation process first uses flotation to enrich precious metals such as gold and silver, and then recovers them in steps through methods such as electrolysis. This method obtains gold and silver with high purity and low loss, but requires the use of a large amount of flotation agents, and the flotation recovery rate is low, the equipment requirements are high, and the cost investment is large; the hydrometallurgical process uses wet leaching to leach the gold and silver in the ore into the solution, and then recovers the gold and silver through methods such as replacement, reduction, and extraction. This method is simple in process, small in investment, and has a high direct recovery rate of gold and silver, but this method of extracting gold and silver often requires pretreatment of the ore, and the subsequent gold and silver purification process will produce toxic gases such as ammonia, chlorine, and nitrogen oxides, 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 current process of extracting gold and silver by wet smelting has the following problems: 1. In order to obtain a higher leaching rate, cyanide is usually used as a leaching agent. Cyanide is a highly toxic substance. Improper treatment will seriously endanger human health and cause environmental pollution; 2. The extraction agent consumption is large and the stripping is difficult. It has a good enrichment effect on the precious gold and silver solution, but the treatment effect on the lean gold and silver solution is poor and the cost is high; 3. The gold and silver alloys after enrichment often need to be refined to obtain purer gold and silver. Refining requires higher purity of gold and silver and less impurities. The treatment effect is not ideal for gold and silver alloys with complex components. The resin adsorption method can be used to solve the above problems. It does not use toxic and harmful substances, has high selectivity for gold and silver, and is more convenient to desorb. The resin after desorption can be used to adsorb gold and silver again. Summary of the invention

[0005] The purpose of the present invention is to provide a method for recovering trace gold and silver in a sintering machine head ash treatment solution by a resin adsorption method, which does not use highly toxic agents such as cyanide, has a large adsorption capacity, good adsorption selectivity, and high desorption efficiency. The resin after desorption can be used to adsorb gold and silver again, has a wide range of applications, and can adsorb gold and silver in a concentration of 0.01 mg / L-100 mg / L. It 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.

[0006] The technical solution of the present invention is achieved in this way: The present invention provides a method for recovering trace gold and silver in a sintering machine head ash treatment solution by a resin adsorption method, comprising the following steps: Step 1: Use alkali solution to adjust the pH of the sintering machine head ash treatment solution to 6-9 to obtain a poor gold and silver solution; Step 2: passing the gold-silver-containing solution through 1-3 level ion adsorption columns in sequence to obtain gold-silver-rich resin and adsorption liquid; Step 3: Use acidic thiourea to desorb the gold-silver-rich resin to obtain a gold-silver-rich solution and an anion resin. The desorbed resin returns to the second step to continue to adsorb gold and silver; Step 4: Add a reducing agent to the gold-silver rich solution for reduction. After the reaction is completed, separate the solid and liquid to obtain gold-silver alloy powder, and send the gold-silver alloy powder to the refining system to obtain gold ingots and silver ingots.

[0007] As a further improvement of the present invention, the alkali solution used to adjust the pH of the solution in the first step 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 adding under stirring, and the stirring time is 0.5-1.5 h.

[0008] 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 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 to be 5-10BV / h.

[0009] As a further improvement of the present invention, the acidic thiourea used in the third step is a mixture of sulfuric acid and thiourea, wherein the mass fraction of sulfuric acid is 1-3% and the mass fraction of thiourea is 8-10%.

[0010] 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 amount of reducing agent added is 100-120% of the measured value of the gold and silver content in the desorption solution, the reduction temperature is room temperature, and the reduction time is 0.5-1.5h.

[0011] As a further improvement of the present invention, the anionic resin is a modified ethylene glycol silane copolymer, and the preparation method is as follows: S1. The ethylene glycol silane copolymer C410 was added to a Tris-HCl solution, dopamine hydrochloride was added, the reaction was heated and stirred, filtered, washed, and dried to obtain a polydopamine-modified ethylene glycol silane copolymer; S2. Add the polydopamine-modified ethylene glycol silane copolymer C410 into a Tris-HCl solution, add tannic acid, heat and stir to react, filter, wash, and dry to obtain a modified ethylene glycol silane copolymer.

[0012] The anionic resin of the present invention is a modified ethylene glycol silane copolymer, which is modified by polydopamine and tannic acid in sequence, so that the ethylene glycol silane copolymer has abundant active groups such as amino, carboxyl, hydroxyl and the like, can fix heavy metal ions by forming a variety of complex bonds, has a large adsorption capacity, a high adsorption rate, does not use highly toxic agents such as cyanide, has a high desorption efficiency, and the resin after desorption can be used again to adsorb gold and silver, and has a wide range of applications.

[0013] As a further improvement of the present invention, the pH value of the Tris-HCl solution is 8.5-9.5.

[0014] As a further improvement of the present invention, the mass ratio of the ethylene glycol silane copolymer C410 to dopamine hydrochloride is 10:2-3.

[0015] As a further improvement of the present invention, the mass ratio of the polydopamine-modified ethylene glycol silane copolymer C410 to tannic acid is 10:3-4.

[0016] 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 hours.

[0017] The present invention has the following beneficial effects: The invention uses a resin adsorption method to recover trace gold and silver in a sintering machine head ash treatment solution, uses acidic thiourea for desorption, and then obtains gold and silver ingots through reduction smelting. No highly toxic agents such as cyanide are used, and the adsorption capacity is large, the adsorption selectivity is good, and the desorption efficiency is high. The resin after desorption can be used to adsorb gold and silver again, and the application range is wide. The adsorbable gold and silver concentration is 0.01 mg / L-100 mg / L, and a complex solution containing multiple metal ions can be treated. The process is simple, easy to control, no environmental pollution, and suitable for industrial production. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Preparation Example 1 Preparation of modified ethylene glycol silane copolymer Here’s how: 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 to react for 3 h, filter, wash, and dry to obtain a polydopamine-modified ethylene glycol silane copolymer; S2. Add 10 g of 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 to react for 3 h, filter, wash, and dry to obtain a modified ethylene glycol silane copolymer.

[0020] Preparation Example 2 Preparation of modified ethylene glycol silane copolymer Here’s how: 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 to react for 5 hours, filter, wash, and dry to obtain a polydopamine-modified ethylene glycol silane copolymer; 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 to react for 5 h, filter, wash, and dry to obtain a modified ethylene glycol silane copolymer.

[0021] The difference between Comparative Preparation Example 1 and Preparation Example 2 is that step S1 is not performed.

[0022] The details are as follows: 10 g of ethylene glycol silane copolymer C410 was added to a Tris-HCl solution with a pH value of 9.5, and 4 g of tannic acid was added. The solution was heated to 50° C., stirred for reaction for 5 h, filtered, washed, and dried to obtain a modified ethylene glycol silane copolymer.

[0023] Comparative Preparation Example 2 is different from Preparation Example 2 in that step S2 is not performed.

[0024] The details are as follows: 10 g of ethylene glycol silane copolymer C410 was added to a Tris-HCl solution with a pH value of 9.5, and 3 g of dopamine hydrochloride was added. The solution was heated to 50° C., stirred for reaction for 5 h, filtered, washed, and dried to obtain a modified ethylene glycol silane copolymer. Embodiment 1:

[0025] The composition of the ash treatment solution of the sintering machine head of a steel plant is shown in Table 1: Table 1 Composition of sintering machine head ash treatment solution

[0026] As shown in Table 1, the content of precious metals in the machine head ash treatment liquid is low, and it contains other impurity ions. The pH value of the solution is adjusted to 6 using 100 g / L sodium hydroxide solution. After stirring for 0.5 h, a gold-silver-poor solution is obtained by solid-liquid separation. Its composition is shown in Table 2 below.

[0027] Table 2 Composition of poor gold and silver solution

[0028] As shown in Table 2, the above-mentioned poor gold and silver solution was passed through a 3-stage ethylene glycol silane copolymer C410 resin adsorption column at a flow rate of 5 BV / h using a peristaltic pump to obtain a gold and silver rich resin and a post-adsorption liquid. The composition of the post-adsorption liquid is shown in Table 3 below.

[0029] Table 3 Composition of liquid after adsorption

[0030] Use 1% sulfuric acid and 8% thiourea to desorb the gold-silver rich resin to obtain a gold-silver rich solution. The desorbed resin returns to the second step for re-adsorption. Sodium sulfite is added to the gold-silver rich solution for reduction. The amount of sodium sulfite added 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 0.5h. After the reaction is completed, solid-liquid separation is performed to obtain gold-silver alloy powder, which is then sent to the refining system to obtain gold and silver ingots. Embodiment 2:

[0031] The composition of the ash treatment solution of the sintering machine head of a steel plant is shown in Table 4 below: Table 4 Composition of sintering machine head ash treatment solution

[0032] As shown in Table 4, the content of precious metals in the machine head ash treatment liquid is low, and it contains other impurity ions. The pH value of the solution is adjusted to 7 using 150 g / L sodium hydroxide solution. After stirring for 1 hour, a gold-silver-poor solution is obtained by solid-liquid separation. Its composition is shown in Table 5 below.

[0033] Table 5 Composition of poor gold and silver solution

[0034] As shown in Table 5, the above-mentioned poor gold and silver solution was passed through the modified ethylene glycol silane copolymer resin adsorption column prepared in the 3-stage Preparation Example 1 at a flow rate of 8 BV / h using a peristaltic pump to obtain a gold and silver rich resin and a post-adsorption liquid. The composition of the post-adsorption liquid is shown in Table 6 below.

[0035] Table 6 Composition of liquid after adsorption

[0036] Use 2% sulfuric acid and 9% thiourea to desorb the gold-silver rich resin to obtain a gold-silver rich solution. The desorbed resin returns to the second step for re-adsorption. Sodium sulfite is added to the gold-silver rich solution for reduction. The amount of sodium sulfite added 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 hour. After the reaction is completed, solid-liquid separation is performed to obtain gold-silver alloy powder, which is then sent to the refining system to obtain gold and silver ingots. Embodiment 3:

[0037] The composition of the ash treatment solution of the sintering machine head of a steel plant is shown in Table 7 below: Table 7 Composition of sintering machine head ash treatment solution

[0038] As shown in Table 7, the content of precious metals in the machine head ash treatment liquid is low, and it contains other impurity ions. The pH value of the solution is adjusted to 8 using 200 g / L sodium hydroxide solution. After stirring for 1.5 hours, a gold-silver-poor solution is obtained by solid-liquid separation. Its composition is shown in Table 8 below.

[0039] Table 8 Composition of poor gold and silver solution

[0040] As shown in Table 8, a peristaltic pump was used to pass the above-mentioned poor gold and silver solution through the modified ethylene glycol silane copolymer resin adsorption column prepared in the 3-stage preparation example 2 at a flow rate of 8 BV / h to obtain a gold and silver rich resin and a post-adsorption liquid. The composition of the post-adsorption liquid is shown in Table 9 below.

[0041] Table 9 Composition of liquid after adsorption

[0042] Use 3% sulfuric acid and 10% thiourea to desorb the gold-silver rich resin to obtain a gold-silver rich solution. The desorbed resin returns to the second step for re-adsorption. Sodium sulfite is added to the gold-silver rich solution for reduction. The amount of sodium sulfite added 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 hours. After the reaction is completed, solid-liquid separation is performed to obtain gold-silver alloy powder, which is then sent to the refining system to obtain gold and silver ingots.

[0043] Comparative Example 1 is different from Example 3 in that the modified ethylene glycol silane copolymer resin is prepared by Comparative Preparation Example 1.

[0044] The composition of the liquid after adsorption is shown in Table 10 below.

[0045] Table 10 Composition of liquid after adsorption

[0046] Comparative Example 2 is different from Example 3 in that the modified ethylene glycol silane copolymer resin is prepared by Comparative Preparation Example 2.

[0047] The composition of the liquid after adsorption is shown in Table 11 below.

[0048] Table 11 Composition of liquid after adsorption

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for recovering trace gold and silver from sintering machine head ash treatment solution by resin adsorption method, characterized in that: The following steps are involved: Step 1: Use alkali solution to adjust the pH of the sintering machine head ash treatment solution to 6-9 to obtain a poor gold and silver solution; Step 2: passing the gold-silver-containing solution through 1-3 level ion adsorption columns in sequence to obtain gold-silver-rich resin and adsorption liquid; Step 3: Use acidic thiourea to desorb the gold-silver-rich resin to obtain a gold-silver-rich solution and an anion resin. The desorbed resin returns to the second step to continue to adsorb gold and silver; Step 4: Add a reducing agent to the gold-silver rich solution for reduction. After the reaction is completed, separate the solid and liquid to obtain gold-silver alloy powder, and send the gold-silver alloy powder to the refining system to obtain gold ingots and silver ingots.

2. The method according to claim 1, characterized in that: In the first step, the alkali solution used to adjust the pH of the solution 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 adding under stirring, and the stirring time is 0.5-1.5 h.

3. The method according to claim 1, characterized in that: The anion resin used in the second step is one or more of ethylene glycol silane copolymer C410 and cross-linked polystyrene anion exchange resin A-21S. The adsorption temperature is room temperature. The pump used is a high-power peristaltic pump with a controlled flow rate of 5-10 BV / h.

4. The method according to claim 1, characterized in that: The acidic thiourea used in the third step is a mixture of sulfuric acid and thiourea, wherein 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, characterized in that: 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 amount of reducing agent added is 100-120% of the measured value of the gold and silver content in the desorption solution. The reduction temperature is room temperature and the reduction time is 0.5-1.5h.

6. The method according to claim 3, characterized in that: The anionic resin is a modified ethylene glycol silane copolymer, and the preparation method is as follows: S1. The ethylene glycol silane copolymer C410 was added to a Tris-HCl solution, dopamine hydrochloride was added, the reaction was heated and stirred, filtered, washed, and dried to obtain a polydopamine-modified ethylene glycol silane copolymer; S2. Add the polydopamine-modified ethylene glycol silane copolymer C410 into a Tris-HCl solution, add tannic acid, heat and stir to react, filter, wash, and dry to obtain a modified ethylene glycol silane copolymer.

7. The method according to claim 6, characterized in that: The pH value of the Tris-HCl solution is 8.5-9.

5.

8. The method according to claim 6, characterized in that: The mass ratio of the ethylene glycol silane copolymer C410 to dopamine hydrochloride is 10:2-3.

9. The method according to claim 6, characterized in that: The mass ratio of the polydopamine-modified ethylene glycol silane copolymer C410 to tannic acid is 10:3-4.

10. The method according to claim 6, characterized in that: The temperature of the heating and stirring reaction is 40-50°C and the time is 3-5h.

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