An efficient magnetic carbon-based adsorbent, its preparation method and application

Abstract

The present invention discloses an efficient magnetic carbon-based adsorbent, its preparation method and application, belonging to the technical field of solid waste resource utilization. The preparation method includes: mixing the screened pyrometallurgical gold extraction waste residue with hydrochloric acid, performing a primary microwave reaction, then carrying out solid-liquid separation and washing to obtain a ferric-rich acid leaching solution; ball-milling blast furnace injection ash to obtain fine slag, mixing the fine slag with the ferric-rich acid leaching solution, performing a secondary microwave reaction, adjusting the pH to alkaline to obtain a mixed solution of iron hydroxide and carbon, filtering by suction to obtain an iron-carbon mixed filter residue, washing with water to neutrality, drying, and performing high-temperature pyrolysis under nitrogen to obtain the efficient magnetic carbon-based adsorbent. The present invention can improve the recycling rate of pyrometallurgical gold extraction waste residue while efficiently adsorbing and desorbing acidic copper chloride etching waste liquid.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and particularly relates to a high-efficiency magnetic carbon-based adsorbent, its preparation method and application. Background Art

[0002] At present, China has become a major producer of printed circuit boards (PCBs) in the world. Printed circuit board etching waste liquid is divided into alkaline etching liquid and acidic etching liquid. Each year, the PC industry line produces more than 2.8 million tons of acidic copper chloride etching waste liquid, and this data is still increasing. Due to the high copper and hydrochloric acid content in the acidic copper chloride etching waste liquid, the copper content is generally about 120 g / L - 180 g / L, and the hydrochloric acid content is about 65 g / L - 140 g / L, so it has extremely high recycling value. However, due to the presence of other inorganic and organic substances, there are certain challenges in recycling. Currently, the treatment methods of acidic copper chloride etching waste liquid are mainly divided into two categories: One is that most enterprises send the etching waste liquid to a specific recycling and treatment center and adopt the neutralization method for centralized treatment to recover copper and the like. This method focuses on the neutralization treatment of the waste liquid, and the resource utilization rate is not high. The other is that a small number of enterprises use a large amount of oxidants for treatment to regenerate the etching waste liquid and restore its original etching ability, thereby achieving recycling. This method requires a large amount of oxidants, increasing the treatment cost.

[0003] At the same time, China's gold production ranks among the top in the world. With the continuous development of gold mines and the maturity of gold extraction technologies, the output of pyrometallurgical gold extraction waste residues is increasing. By the end of 2021, the production volume of pyrometallurgical gold extraction waste residues has reached 130 million tons. Since pyrometallurgical gold extraction waste residues generally contain harmful components, it is difficult to recycle, the overall utilization rate is low, and the conversion utilization rate of high-value resources is less than 17%. Therefore, a large amount of waste residues are piled up, causing land occupation and environmental pollution, and being prone to collapse, posing huge potential safety hazards.

[0004] Therefore, it is urgent to improve the recycling rate of pyrometallurgical gold extraction waste residues while making full use of acidic copper chloride etching waste liquid. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-efficiency magnetic carbon-based adsorbent, its preparation method and application, which can improve the recycling rate of pyrometallurgical gold extraction waste residues and perform efficient adsorption and desorption on acidic copper chloride etching waste liquid.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect, a preparation method of a high-efficiency magnetic carbon-based adsorbent includes the following steps:

[0008] Mix the sieved pyrometallurgical gold extraction waste residue with hydrochloric acid. After a single microwave reaction, perform solid-liquid separation and washing to obtain an iron-rich acid leaching solution.

[0009] After ball milling blast furnace injection ash, obtain fine slag. Mix the fine slag with the iron-rich acid leaching solution, perform a secondary microwave reaction, adjust the pH to alkaline to obtain a mixed solution of iron hydroxide and carbon. After suction filtration, obtain an iron-carbon mixed filter residue, wash it with water to neutrality, dry it, and pyrolyze it at high temperature under nitrogen to obtain a high-efficiency magnetic carbon-based adsorbent.

[0010] In some embodiments, the pyrometallurgical gold extraction waste residue is sieved through a 200-mesh sieve. The solid-liquid ratio of the pyrometallurgical gold extraction waste residue to hydrochloric acid is 1 g:(3 - 10) mL, and the mass fraction of the hydrochloric acid is 5% - 35%.

[0011] In some embodiments, the power of the single microwave reaction is 240 W - 800 W, the time is 10 min - 60 min, and the temperature is 70 °C - 110 °C.

[0012] In some embodiments, the rotation speed of the ball milling is 500 rpm, and the time is 20 min - 60 min.

[0013] In some embodiments, in the fine slag, the mass ratio of iron to carbon is 1:(1 - 5). The solid-liquid ratio of the fine slag to the iron-rich acid leaching solution is (0.504 - 2.760) g:20 mL. The power of the secondary microwave reaction is 180 W - 420 W, and the time is 1 min - 30 min.

[0014] In some embodiments, sodium hydroxide is used to adjust the pH value to 10.

[0015] In some embodiments, the temperature of the high-temperature pyrolysis is 300 °C - 600 °C, and the time is 5 min - 30 min.

[0016] Second, a high-efficiency magnetic carbon-based adsorbent is obtained by using the preparation method of the high-efficiency magnetic adsorbent. The specific surface area of the magnetic carbon of the high-efficiency magnetic carbon-based adsorbent is 578.2 m 2 / g - 639.5 m 2 / g, and the magnetization intensity is 15.48 emu / g - 18.58 emu / g.

[0017] Third, an application of a high-efficiency magnetic carbon-based adsorbent in adsorbing printed circuit board etching waste liquid. The fifth adsorption rate of the high-efficiency magnetic carbon-based adsorbent in the cyclic adsorption experiment is 37.1% - 87.4%. The adsorption rate of the high-efficiency magnetic carbon-based adsorbent to acidic etching solution is 72.5% - 99.1%, and the desorption rate to acidic etching solution is 83.1% - 98.4%;

[0018] The applicable pH range of the magnetic carbon-based adsorbent is 1-7, and the adsorption rate of the magnetic carbon-based adsorbent to the acidic etching solution within the applicable pH range is greater than 85%.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This method uses two industrial solid wastes, pyrometallurgical gold extraction slag and blast furnace ash, as raw materials, addressing the environmental issues caused by solid waste accumulation. Furthermore, the pyrometallurgical gold extraction slag itself has a high iron content, ensuring a sufficient iron source while avoiding the need for activating and crushing the slag, thus reducing raw material costs. This method combines the pyrometallurgical gold extraction slag with hydrochloric acid and then uses microwave reaction for auxiliary treatment, significantly shortening the treatment cycle compared to traditional direct acid leaching. The present invention mixes fine slag with an iron-rich acid leaching solution, and then undergoes a secondary microwave reaction to adjust the pH to alkaline to obtain a mixed solution of iron hydroxide and carbon. Compared with traditional magnetic carbon materials that use biochar and iron salt solution to compound, the process of compounding the iron-rich acid leaching solution with blast furnace spray ash not only digests solid waste, but also acid-modifies the blast furnace spray ash, introduces more oxygen-containing functional groups, increases the number of negative charges on its surface, and enhances its adsorption capacity for metal ions. In addition, the iron-rich acid leaching solution can wash away impurities in the pores between the blast furnace spray ash, and through microwave-assisted compounding, improves the acid and alkali resistance and stability of the magnetic carbon, so that the high-efficiency magnetic carbon-based adsorbent is finally obtained, which can achieve high-efficiency adsorption and high-efficiency desorption within a wider pH range. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the XRD pattern of the blast furnace injection ash of Example 1;

[0022] Figure 2 This is the XRD pattern of the high-efficiency magnetic carbon-based adsorbent prepared in Example 1;

[0023] Figure 3 The scanning electron micrographs of the high-efficiency magnetic carbon-based adsorbent prepared in Example 1 are shown, wherein (a) is a scanning electron micrograph of magnetic carbon, (b) is a C distribution energy spectrum, (c) is an O distribution energy spectrum, and (d) is an Fe distribution energy spectrum;

[0024] Figure 4 This is the XPS graph of the high-efficiency magnetic carbon-based adsorbent prepared in Example 1;

[0025] Figure 5 Graphs showing the effect of magnetic recovery of water by the high-efficiency magnetic carbon-based adsorbent prepared in Example 1, wherein (a) is a graph showing the high-efficiency magnetic carbon-based adsorbent before magnetic recovery of water, and (b) is a graph showing the high-efficiency magnetic carbon-based adsorbent after magnetic recovery of water;

[0026] Figure 6Result graph of testing the copper ion concentration of the highly efficient magnetic carbon-based adsorbent prepared in Example 1 by ICP-OES;

[0027] Figure 7 Result graph of the cyclic adsorption test for the highly efficient magnetic carbon-based adsorbent prepared in Example 1. Detailed implementation manners

[0028] The present invention is further described in detail as follows:

[0029] The pyrometallurgical gold extraction waste residue usually has a relatively fine particle size. Due to the different types of ores, the components of the waste residue are also different. It is classified by the types of metal elements into: gold - quartz type, gold - pyrite type, gold - polymetallic type, gold - copper type, gold - antimony type, gold - antimony - tungsten type, gold - arsenopyrite type, gold - bismuth type, gold - uranium type, gold - tellurium type, etc. The raw material type adopted in the present invention is the gold - pyrite type, and the main minerals of the ore are pyrite, and the gangue minerals are mainly quartz.

[0030] The present invention provides a preparation method of a highly efficient magnetic carbon-based adsorbent, comprising the following steps:

[0031] Step 1: Mix the sieved pyrometallurgical gold extraction waste residue and hydrochloric acid, perform solid-liquid separation after a primary microwave reaction, and wash to obtain a ferric-rich acid leaching solution. Use the method of GB / T 3049-2006 to test the iron ion content in the ferric-rich acid leaching solution;

[0032] Preferably, in Step 1, the pyrometallurgical gold extraction waste residue is sieved through a 200-mesh sieve, the solid-liquid ratio of the pyrometallurgical gold extraction waste residue to hydrochloric acid is 1 g : (3 - 10) mL, the mass fraction of the hydrochloric acid is 5% - 35%, the power of the primary microwave reaction is 240 W - 800 W, the time is 10 min - 60 min, and the temperature is 70°C - 110°C. Ensure a sealed environment during the microwave reaction and externally add a condensation reflux device.

[0033] Step 2: Use a planetary ball mill to ball mill the blast furnace pulverized coal injection ash to obtain fine slag. Mix the fine slag with the ferric-rich acid leaching solution obtained in Step 1 and put it into a microwave chemical reactor for a secondary microwave reaction to obtain a reacted solution;

[0034] Preferably, in Step 2, the rotation speed of the ball milling is 500 rpm, the time is 20 min - 60 min, agate beads are used during ball milling, the mass ratio of the agate beads to the blast furnace pulverized coal injection ash is 20:1, the mass ratio of iron to carbon in the fine slag is 1 : (1 - 5), the solid-liquid ratio of the fine slag to the ferric-rich acid leaching solution is (0.504 - 2.760) g : 20 mL, and the power of the secondary microwave reaction is 180 W - 420 W, and the time is 1 min - 30 min.

[0035] Step 3: Adjust the pH of the solution obtained in Step 2 to alkaline to obtain a mixed solution of iron hydroxide and carbon.

[0036] Preferably, in Step 3, sodium hydroxide is used to adjust the pH value to 10.

[0037] Step 4: Filter the mixed solution of iron hydroxide and carbon obtained in Step 3 by suction filtration to obtain an iron-carbon mixed filter residue, wash it with water until it is neutral, and then perform drying treatment to obtain a dried filter residue.

[0038] Step 5: Pyrolyze the dried filter residue obtained in Step 4 at high temperature under the condition of nitrogen gas passing through to obtain a high-efficiency magnetic carbon-based adsorbent.

[0039] Preferably, in Step 5, the high-temperature pyrolysis temperature is 300°C to 600°C, and the time is 5 min to 30 min.

[0040] The present invention will be described in detail below with reference to embodiments. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0041] The following detailed descriptions are all descriptions of embodiments, aiming to provide further detailed descriptions of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0042] Example 1

[0043] This example provides a preparation method for a high-efficiency magnetic carbon-based adsorbent, including the following steps:

[0044] Step 1: Add 5 g of sieved pyrometallurgical gold extraction waste residue to 35 mL of hydrochloric acid with a mass fraction of 25%, under the condition of a primary microwave reaction of 560 W, control the primary microwave reaction temperature at 80°C, stir and react for 30 min, further perform solid-liquid separation and washing to obtain 67 mL of iron-rich acid leaching solution, and measure the iron ion concentration therein: 33.2 mg / L, and the iron leaching rate is 91.2%.

[0045] Step 2: Take 10 g of blast furnace injection ash and mix it evenly with 200 g of agate beads, place them in an agate ball mill, ball mill for 45 min at a rotation speed of 500 rpm to obtain fine slag, take 1.992 g of fine slag with an iron-carbon ratio of 1:3 and mix it with 20 mL of the iron-rich acid leaching solution obtained in Step 1, then put it into a microwave chemical reactor and microwave for 10 min at a power of 180 W to obtain a reaction solution.

[0046] Step 3: The reaction solution obtained in step 2 is slowly added dropwise with sodium hydroxide solution to adjust the pH to 10 to obtain a mixed solution of iron hydroxide and carbon.

[0047] Step 4: After filtering the mixed solution of iron hydroxide and carbon obtained in step 3, repeatedly washing with water until the washing liquid is neutral, drying it to obtain a dried filter residue.

[0048] Step 5: The dried filter residue obtained in step 4 was pyrolyzed at 600°C for 10 min under nitrogen flow to obtain 2.7968 g of a high-efficiency magnetic carbon-based adsorbent.

[0049] The magnetic carbon specific surface area of the magnetic carbon-based adsorbent is 615.4m 2 / g, the magnetization intensity is 18.02emu / g, and the structure of blast furnace ash is detected by X-ray diffractometer. Figure 1 As shown, the round peak appearing at 20° is the characteristic peak of carbon;

[0050] The structure of the high-efficiency magnetic carbon-based adsorbent prepared in Example 4 below was detected by X-ray diffractometer. Figure 2 As shown in the figure, the diffraction peak at 20° is significantly weakened after magnetization. Figure 1 The newly added diffraction peaks at 30.29°, 35.55°, 43.08°, 57.36°, and 62.74° are consistent with the data of Fe3O4 cubic crystal system, proving that magnetic carbon was successfully prepared.

[0051] Figure 3 This indicates that iron is evenly loaded on the carbon surface. Figure 4 The peaks at 711.68 and 714.18 are Fe 3+ and Fe 2+ , which is related to Fe3O4, and the composite is a chemical composite, indicating that the magnetic carbon-based adsorbent was successfully prepared.

[0052] Take 10 mL of an acidic etching solution from a place in Henan and dilute it to 100 mL. The main components are: copper content of 11.28% and HCl content of 12.71%. Weigh 5 g of the magnetic carbon-based adsorbent prepared in this example and add it to the acidic etching solution. Adjust the magnetic stirring speed to 300 r / min, take a sample every 10 minutes, and measure the copper ion concentration by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer). Figure 6As shown, the adsorption rate can reach 99.1% in 75 min. Then, solid-liquid separation is carried out by suction filtration. After drying, the residue is put into the desorption solution prepared with methanol and hydrochloric acid. After ultrasonic treatment for 30 minutes, solid-liquid separation is carried out again, and the desorption rate can reach 98.4%. Further, the pH of the desorption solution is adjusted to 6.4 with weak base, and solid-liquid separation is carried out. After washing and drying the solid phase, it is calcined at low temperature for 20 minutes to obtain copper oxide.

[0053] Take 100 mg of the magnetic carbon-based adsorbent prepared in this example and add it to 50 mL of the acidic etching solution of printed circuit board. The copper ion concentration of the etching solution is 200 mg / L. Adjust the magnetic stirring speed to 200 r / min, and measure Cu 2+ concentration. Under the condition that the pH ranges from 1 to 7, the adsorption rate within 15 min is above 85%. Especially when pH = 6, the adsorption effect is the best, and the adsorption rate within 15 min can reach 92.46%, indicating the universality of the magnetic carbon-based adsorbent prepared in this example for a wide range of pH values.

[0054] Prepare the etching solution of printed circuit board with a concentration of 200 mg / L. Take 1 g of the magnetic carbon-based adsorbent prepared in this example and conduct a cyclic adsorption experiment at pH = 1. After adsorption saturation, use a methanol solution with a volume fraction of 60% for ultrasonic desorption for 30 min. Further, after drying treatment, conduct the adsorption experiment again, and repeat it 5 times. The results are as shown in the appendix Figure 7 As shown, the adsorption rate in the fifth time can still reach 87.4%, indicating that the magnetic carbon-based adsorbent prepared in this example has good recyclability.

[0055] Example 2

[0056] This example provides a preparation method of an efficient magnetic carbon-based adsorbent, including the following steps:

[0057] Step 1: Add 5 g of the screened residue of pyrometallurgical gold extraction to 45 mL of hydrochloric acid with a mass fraction of 15%. Under the condition of the first microwave reaction with 800 W, control the temperature of the first microwave reaction at 100 °C, stir and react for 20 min, and then conduct solid-liquid separation and washing to obtain 75 mL of iron-rich acid leaching solution. The measured iron ion concentration in it is: 28.2 mg / L, and the iron leaching rate is 86.5%.

[0058] Step 2: Take 10 g of blast furnace injection ash and mix it evenly with 200 g of agate beads, place them in an agate ball mill, and mill for 45 min at a rotation speed of 500 rpm to obtain fine slag. Take 2.256 g of the fine slag with an iron-carbon ratio of 1:4 and mix it with 20 mL of the iron-rich acid leaching solution obtained in Step 1, then put it into a microwave chemical reactor and microwave for 12 min at a power of 300 W to obtain the reaction solution.

[0059] Step 3: Slowly add the reacted solution obtained in Step 2 dropwise through sodium hydroxide solution to adjust the pH to 10, obtaining a mixed solution of iron hydroxide and carbon.

[0060] Step 4: After subjecting the mixed solution of iron hydroxide and carbon obtained in Step 3 to suction filtration, wash it repeatedly with water until the washing liquid is neutral, and then perform drying treatment to obtain the dried filter residue.

[0061] Step 5: Pyrolyze the dried filter residue obtained in Step 4 at 500 °C for 30 min under the condition of nitrogen gas introduction, obtaining 3.1256 g of high-efficiency magnetic carbon-based adsorbent.

[0062] The specific surface area of the magnetic carbon in this magnetic carbon-based adsorbent is 628.2 m 2 / g, the magnetization intensity is 16.02 emu / g, the adsorption rate for acidic etching solution can reach 95.1%, and the desorption rate can reach 94.3%; in the cyclic adsorption experiment, the adsorption rate in the fifth cycle can reach 71.2%.

[0063] Example 3

[0064] This example provides a preparation method of a high-efficiency magnetic carbon-based adsorbent, including the following steps:

[0065] Step 1: Add 5 g of sieved pyrometallurgical gold extraction waste residue to 25 mL of hydrochloric acid with a mass fraction of 30%, under the condition of a primary microwave reaction of 600 W, control the primary microwave reaction temperature at 70 °C, stir and react for 20 min, further perform solid-liquid separation and washing, obtaining 58 mL of iron-rich acid leaching solution, and measuring the iron ion concentration therein as: 37.8 mg / L, and the iron leaching rate is 89.5%.

[0066] Step 2: Take 10 g of blast furnace injection ash and mix it evenly with 200 g of agate beads, place them in an agate ball mill, ball mill at a speed of 500 rpm for 45 min to obtain fine slag, take 1.512 g of fine slag with an iron-carbon ratio of 1:2 and mix it with 20 mL of the iron-rich acid leaching solution obtained in Step 1, then put it into a microwave chemical reactor and microwave for 8 min at a power of 240 W to obtain the reacted solution.

[0067] Step 3: Slowly add the reacted solution obtained in Step 2 dropwise through sodium hydroxide solution to adjust the pH to 10, obtaining a mixed solution of iron hydroxide and carbon.

[0068] Step 4: After subjecting the mixed solution of iron hydroxide and carbon obtained in Step 3 to suction filtration, wash it repeatedly with water until the washing liquid is neutral, and then perform drying treatment to obtain the dried filter residue.

[0069] Step 5: Pyrolyze the dried filter residue obtained in Step 4 at 500 °C for 30 min under the condition of nitrogen gas introduction, obtaining 2.2462 g of high-efficiency magnetic carbon-based adsorbent.

[0070] The specific surface area of the magnetic carbon in this magnetic carbon-based adsorbent is 578.2 m 2 / g, the magnetization intensity is 18.45 emu / g, the adsorption rate for acidic etching solution can reach 92.2%, and the desorption rate can reach 93.5%; in the cyclic adsorption experiment, the adsorption rate in the fifth cycle can reach 51.2%.

[0071] Example 4

[0072] This example provides a preparation method of an efficient magnetic carbon-based adsorbent, which includes the following steps:

[0073] Step 1: Add 5 g of sieved pyrometallurgical gold extraction waste residue to 40 mL of hydrochloric acid with a mass fraction of 15%. Under the condition of a primary microwave reaction at 720 W, control the primary microwave reaction temperature at 90 °C, stir and react for 20 min, and then perform further solid-liquid separation and washing to obtain 76 mL of iron-rich acid leaching solution. The measured iron ion concentration in it is: 27.6 mg / L, and the iron leaching rate is 85.5%.

[0074] Step 2: Take 10 g of blast furnace injection ash and mix it evenly with 200 g of agate beads, place them in an agate ball mill, and ball mill at a speed of 500 rpm for 45 min to obtain fine slag. Take 2.760 g of the fine slag with an iron-carbon ratio of 1:5 and mix it with 20 mL of the iron-rich acid leaching solution obtained in Step 1, then put it into a microwave chemical reactor and microwave for 15 min at a power of 200 W to obtain the reacted solution.

[0075] Step 3: Slowly add the reacted solution obtained in Step 2 to adjust the pH to 10 with sodium hydroxide solution to obtain a mixed solution of iron hydroxide and carbon.

[0076] Step 4: After filtering the mixed solution of iron hydroxide and carbon obtained in Step 3 by suction filtration, wash it repeatedly with water until the washing liquid is neutral, and then perform drying treatment to obtain the dried filter residue.

[0077] Step 5: Pyrolyze the dried filter residue obtained in Step 4 at 500 °C for 30 min under the condition of nitrogen gas flow to obtain 3.102 g of an efficient magnetic carbon-based adsorbent.

[0078] The specific surface area of the magnetic carbon in this magnetic carbon-based adsorbent is 629.5 m 2 / g, the magnetization intensity is 15.48 emu / g, the adsorption rate for acidic etching solution can reach 95.5%, and the desorption rate can reach 92.5%; in the cyclic adsorption experiment, the adsorption rate in the fifth cycle can reach 48.8%.

[0079] Example 5

[0080] This example provides a preparation method of an efficient magnetic carbon-based adsorbent, which includes the following steps:

[0081] Step 1: Add 5 g of sieved pyrometallurgical gold extraction waste residue to 50 mL of hydrochloric acid with a mass fraction of 35%. Under the condition of a primary microwave reaction at 480 W, control the primary microwave reaction temperature at 60 °C, stir and react for 20 min, then perform further solid-liquid separation and washing to obtain 81 mL of iron-rich acid leaching solution. The measured iron ion concentration in it is 25.2 mg / L, and the iron leaching rate is 83.5%.

[0082] Step 2: Take 10 g of blast furnace injection ash and mix it evenly with 200 g of agate beads, place them in an agate ball mill, and ball mill for 45 min at a rotation speed of 500 rpm to obtain fine slag. Take 0.504 g of the fine slag with an iron-carbon ratio of 1:1 and mix it with 20 mL of the iron-rich acid leaching solution obtained in Step 1, then put it into a microwave chemical reactor and microwave for 6 min at a power of 420 W to obtain the reacted solution.

[0083] Step 3: Slowly add the reacted solution obtained in Step 2 dropwise with sodium hydroxide solution to adjust the pH to 10 to obtain a mixed solution of iron hydroxide and carbon.

[0084] Step 4: After filtering the mixed solution of iron hydroxide and carbon obtained in Step 3 by suction filtration, wash it repeatedly with water until the washing solution is neutral, and then perform drying treatment to obtain the dried filter residue.

[0085] Step 5: Pyrolyze the dried filter residue obtained in Step 4 at a high temperature of 500 °C for 30 min under the condition of nitrogen gas introduction to obtain 1.245 g of high-efficiency magnetic carbon-based adsorbent.

[0086] The specific surface area of the magnetic carbon in this magnetic carbon-based adsorbent is 639.5 m 2 / g, the magnetization intensity is 18.58 emu / g, the adsorption rate for acidic etching solution can reach 72.5%, and the desorption rate can reach 83.1%; in the cyclic adsorption experiment, the adsorption rate in the fifth cycle can reach 37.1%.

[0087] Example 6

[0088] This example provides a preparation method for a high-efficiency magnetic carbon-based adsorbent, including the following steps:

[0089] Step 1: Add 5 g of sieved pyrometallurgical gold extraction waste residue to 15 mL of hydrochloric acid with a mass fraction of 5%. Under the condition of a primary microwave reaction at 240 W, control the primary microwave reaction temperature at 110 °C, stir and react for 10 min, then perform further solid-liquid separation and washing to obtain an iron-rich acid leaching solution.

[0090] Step 2: Take 10 g of blast furnace pulverized coal injection ash and mix it evenly with 200 g of agate beads, place them in an agate ball mill, and ball mill for 20 min at a speed of 500 rpm to obtain fine slag. Take 1.992 g of the fine slag with an iron-carbon ratio of 1:3 and mix it with the 20 mL of iron-rich acid leaching solution obtained in Step 1, then put it into a microwave chemical reactor and microwave for 1 min at a power of 180 W to obtain the reaction solution.

[0091] Step 3: Slowly add the reaction solution obtained in Step 2 dropwise with sodium hydroxide solution to adjust the pH to 10 to obtain a mixed solution of iron hydroxide and carbon.

[0092] Step 4: After filtering the mixed solution of iron hydroxide and carbon obtained in Step 3 by suction filtration, wash it repeatedly with water until the washing liquid is neutral, and then perform drying treatment to obtain the dried filter residue.

[0093] Step 5: Pyrolyze the dried filter residue obtained in Step 4 at a high temperature of 300 °C for 5 min under the condition of nitrogen gas introduction to obtain a high-efficiency magnetic carbon-based adsorbent.

[0094] Example 7

[0095] This example provides a preparation method of a high-efficiency magnetic carbon-based adsorbent, including the following steps:

[0096] Step 1: Add 5 g of screened pyrometallurgical gold extraction waste residue to 45 mL of hydrochloric acid with a mass fraction of 15%, under the condition of a primary microwave reaction at 800 W, control the primary microwave reaction temperature at 70 °C, stir and react for 60 min, further perform solid-liquid separation and washing to obtain an iron-rich acid leaching solution.

[0097] Step 2: Take 10 g of blast furnace pulverized coal injection ash and mix it evenly with 200 g of agate beads, place them in an agate ball mill, and ball mill for 60 min at a speed of 500 rpm to obtain fine slag. Take 2.256 g of the fine slag with an iron-carbon ratio of 1:4 and mix it with the 20 mL of iron-rich acid leaching solution obtained in Step 1, then put it into a microwave chemical reactor and microwave for 30 min at a power of 300 W to obtain the reaction solution.

[0098] Step 3: Slowly add the reaction solution obtained in Step 2 dropwise with sodium hydroxide solution to adjust the pH to 10 to obtain a mixed solution of iron hydroxide and carbon.

[0099] Step 4: After filtering the mixed solution of iron hydroxide and carbon obtained in Step 3 by suction filtration, wash it repeatedly with water until the washing liquid is neutral, and then perform drying treatment to obtain the dried filter residue.

[0100] Step 5: Pyrolyze the dried filter residue obtained in Step 4 at a high temperature of 500 °C for 30 min under the condition of nitrogen gas introduction to obtain a high-efficiency magnetic carbon-based adsorbent.

[0101] The embodiments described above are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. In the present application, the embodiments and the features in the embodiments can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for preparing a high-efficiency magnetic carbon-based adsorbent, characterized in that: The following steps are involved: The sieved pyrometallurgical gold extraction waste residue is mixed with hydrochloric acid, subjected to a microwave reaction, solid-liquid separation, and washed to obtain an iron-rich acid leaching solution; Blast furnace ash is ball-milled to obtain fine slag, which is then mixed with an iron-rich acid leaching solution and subjected to a secondary microwave reaction. The pH is adjusted to alkaline to obtain a mixed solution of iron hydroxide and carbon. After filtration, an iron-carbon mixed filter residue is obtained, which is washed with water to neutrality, dried, and pyrolyzed at high temperature under nitrogen to obtain a high-efficiency magnetic carbon-based adsorbent.

2. The method for preparing a high-efficiency magnetic carbon-based adsorbent according to claim 1, characterized in that: The pyrometallurgical gold extraction waste residue is sieved through a 200-mesh sieve, the solid-liquid ratio of the pyrometallurgical gold extraction waste residue to hydrochloric acid is 1 g: (3-10) mL, and the mass fraction of the hydrochloric acid is 5%-35%.

3. The method for preparing a high-efficiency magnetic carbon-based adsorbent according to claim 1, characterized in that: The power of the primary microwave reaction is 240W-800W, the time is 10min-60min, and the temperature is 70°C-110°C.

4. The method for preparing a high-efficiency magnetic carbon-based adsorbent according to claim 1, characterized in that: The ball milling speed is 500 rpm, and the time is 20 min to 60 min.

5. The method for preparing a high-efficiency magnetic carbon-based adsorbent according to claim 1, characterized in that: The mass ratio of iron to carbon in the fine slag is 1:(1-5); the solid-liquid ratio of the fine slag to the iron-rich acid leaching solution is (0.504-2.760) g:20 mL.

6. The method for preparing a high-efficiency magnetic carbon-based adsorbent according to claim 1, characterized in that: The power of the secondary microwave reaction is 180W~420W, and the time is 1min~30min.

7. The method for preparing a high-efficiency magnetic carbon-based adsorbent according to claim 1, characterized in that: The process of adjusting the pH to alkaline is to use sodium hydroxide to adjust the pH value to 10.

8. The method for preparing a high-efficiency magnetic carbon-based adsorbent according to claim 1, characterized in that: The high-temperature pyrolysis temperature is 300° C. to 600° C., and the time is 5 min to 30 min.

9. A high-efficiency magnetic carbon-based adsorbent, characterized in that: The method for preparing a high-efficiency magnetic carbon-based adsorbent according to any one of claims 1 to 8 is used, wherein the magnetic carbon specific surface area of the high-efficiency magnetic carbon-based adsorbent is 578.2 m 2 / g ~639.5m 2 / g, and the magnetization intensity is 15.48 emu / g ~18.58emu / g.

10. Use of a high-efficiency magnetic carbon-based adsorbent according to claim 9 in adsorbing printed circuit board etching liquid, characterized in that: The fifth adsorption rate of the high-efficiency magnetic carbon-based adsorbent in the cyclic adsorption experiment was 37.1% to 87.4%, the adsorption rate of the high-efficiency magnetic carbon-based adsorbent for the acidic etching solution was 72.5% to 99.1%, and the desorption rate of the acidic etching solution was 83.1% to 98.4%; The applicable pH range of the high-efficiency magnetic carbon-based adsorbent is 1-7.

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