A method and reaction system for ultrasonic-assisted goethite process for removing iron and organic matter

Abstract

This invention discloses a method and reaction system for removing iron and organic matter from goethite using ultrasound, belonging to the field of hydrometallurgical technology. The method includes the following steps: pretreatment of the leaching solution from hydrometallurgical zinc smelting by filtering and then pumping it into an ultrasonic reaction vessel; starting the ultrasonic system and adjusting the frequency to 20-80 kHz and the sound intensity to 0.5-5.0 W / cm². 2 Simultaneously, an oxidant is introduced; at a set temperature, a neutralizing agent is continuously added to the ultrasonic reactor to maintain the system pH at 3.5-5.0, with a total reaction time of 20-240 minutes. The ultrasonic field is kept on during the reaction, causing iron to precipitate directionally as α-FeOOH, while organic matter is simultaneously mineralized or adsorbed and encapsulated by goethite and co-precipitated. After aging, the slurry is concentrated and filtered to obtain iron-rich goethite slag and purified liquid. This invention enhances the goethite precipitation process through the cavitation effect, microjets, and Fenton reaction of ultrasound, thereby improving iron removal efficiency and organic matter degradation rate.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, and particularly relates to a method and reaction system for removing iron and organic matter from goethite using ultrasound-assisted methods, which is applicable to solution purification treatment in zinc smelting processes. Background Technology

[0002] In hydrometallurgical zinc refining, iron removal is a crucial step in solution purification, directly impacting the efficiency of subsequent zinc electrowinning and product quality. Commonly used iron removal methods include the jaundice process, the goethite process, and the hematite process. Among these, the goethite process, by controlling the system's pH and temperature, precipitates iron as α-FeOOH (goethite), offering the advantage of high iron content in the slag. However, it suffers from slow reaction rates, fine precipitate particles, and difficulty in filtration, and its effectiveness in removing organic matter from the leachate is limited.

[0003] Organic matter in wet zinc smelting leaching solutions mainly originates from process additives or raw material recovery processes, commonly including gelatin, tannic acid, β-naphthol, and extractant P. 204 N 235 These organic compounds can adsorb onto the electrode surface, reducing zinc electrowinning efficiency and potentially leading to a decline in the quality of electrolytic zinc products. Current technologies for removing organic compounds often employ separate processing steps, which are complex, costly, and pose a risk of secondary pollution. Ultrasonic technology, with its cavitation effect and microjets, can generate localized high temperatures and pressures in solutions, offering unique advantages in promoting chemical reaction kinetics and improving precipitation performance. It has already been applied in chemical engineering and environmental protection fields, but there are no reports of combining it with the goethite process for the simultaneous removal of iron and organic compounds. Summary of the Invention

[0004] Technical problem solved: In view of the technical problems existing in the prior art, the present invention provides a method and reaction system for removing iron and organic matter by ultrasound-assisted goethite method, which realizes efficient and simultaneous removal of iron ions and organic matter, simplifies the process, reduces costs, and conforms to the concept of green metallurgy, so as to solve the problems of slow reaction speed and poor organic matter removal effect of traditional goethite method.

[0005] Technical solution: The present invention provides a method for removing iron and organic matter from goethite using ultrasound assistance, comprising the following steps: Step 1: Take the wet zinc smelting leaching solution with an initial pH of 2.0-3.5, remove coarse particles through an acid-resistant screen, and then pre-treat it in a leaching solution storage tank before pumping it into an ultrasonic reaction tank. Step 2: Start the ultrasonic system and adjust the ultrasonic frequency to 20-80kHz and the sound intensity to 0.5-5.0W / cm². 2 At the same time, an oxidant with a flow rate of 5-200 L / h is introduced into the ultrasonic reactor; Step 3: At 45-90℃, continuously add neutralizing agent to the ultrasonic reactor to maintain the pH value of the system at 3.5-5.0. The total reaction time is 20-240 min. Keep the ultrasonic field on throughout the reaction to allow iron to precipitate in a directional manner as α-FeOOH, and organic matter to be mineralized simultaneously or adsorbed and encapsulated by goethite and co-precipitated. Step 4: After the reaction is complete, turn off the ultrasound and let the slurry age for 0.5-2 hours. After concentration and filtration, the iron-rich goethite slag and purified liquid are obtained.

[0006] Preferably, in step 1, the leaching solution contains zinc ions at a concentration of 1-120 g / L, total iron at a concentration of 1-5 g / L, and organic matter at a concentration of 1-5 g / L; the organic matter includes gelatin, tannic acid, β-naphthol, and extractant P. 204 Extractant N 235 One or more of them.

[0007] Preferably, the neutralizing agent is one or more of zinc oxide, zinc carbonate, or zinc hydroxide; and the oxidizing agent is one or more of compressed air, industrial oxygen, or ozone.

[0008] Preferably, the ultrasonic system has an ultrasonic power of 50-500W, a frequency of 20-40kHz, and operates in either continuous or intermittent mode.

[0009] The present invention also discloses a reaction system for the above method, comprising: The leachate storage tank is equipped with an inlet pipe, an outlet pipe, a temperature control system, a first stirring mechanism, and a liquid level sensor; the inlet pipe is connected to an acid-resistant screen filter, and the outlet pipe is equipped with a bypass valve and a pressure sensor; the temperature control system includes a heating element, a cooling coil, and a temperature sensor correspondingly installed in the leachate storage tank. An ultrasonic system is provided, comprising an ultrasonic reaction vessel, an ultrasonic generator, an ultrasonic transducer, a pH control system, a heating device, a second stirring mechanism, and an oxidant supply system. The ultrasonic reaction vessel includes a reaction vessel body and an inner reaction cylinder disposed therein. The ultrasonic generator, pH control system, heating device, and second stirring mechanism are correspondingly disposed within the inner reaction cylinder. The ultrasonic transducer is electrically connected to the ultrasonic generator. The oxidant supply system includes a gas supply pipe, a flow meter, and a porous annular aeration pipe, the porous annular aeration pipe being correspondingly disposed at the bottom of the ultrasonic reaction vessel. The pH control system includes a neutralizing agent storage tank, a neutralizing agent metering pump, a pH sensor, and a pH controller. The pH controller is linked to the neutralizing agent metering pump, and the pH sensor is correspondingly placed inside the ultrasonic reaction vessel. The conveying system connects the leachate storage tank and the ultrasonic reaction tank, and includes a centrifugal pump and a stopcock valve. The pretreated leachate is controlled to enter the centrifugal pump through the stopcock valve and is then conveyed to the ultrasonic reaction tank by the centrifugal pump. A solid-liquid separation unit is used to concentrate and filter the reacted slurry.

[0010] Preferably, the acid-resistant screen material of the acid-resistant screen filter is polytetrafluoroethylene, with a pore size of 150-300μm, an acid and alkali resistance pH value of 0-14, and a temperature tolerance range of −20-110℃. Its pore size and type can be disassembled and replaced by a threaded control valve. The centrifugal pump is made of 316L stainless steel, uses frequency conversion control, and is linked with a liquid level sensor.

[0011] Preferably, the ultrasonic system further includes a cooling water circulation pipe made of carbon steel, which adopts a bottom-in, top-out flow pattern; the ultrasonic transducer is a piezoelectric transducer made of 316L stainless steel, and is provided with a cooling water inlet and a cooling water outlet.

[0012] Preferably, the ultrasonic reaction vessel is made of polypropylene or stainless steel, with a temperature resistance range of -20 to 140°C; the reaction vessel is lined with silicon carbide corrosion-resistant bricks; and the porous annular aeration pipe is made of titanium with a pore size of 10-50 μm.

[0013] Preferably, the pH control system has an accuracy of ±0.15. The pH value of the system is detected by a pH sensor, and after receiving the signal, the pH controller controls the neutralizer metering pump to add neutralizer from the neutralizer storage tank to the ultrasonic reaction tank.

[0014] Preferably, the ultrasonic reaction vessel is provided with tilting and lifting mechanisms on both sides, and the tilting and lifting mechanisms are connected to the ultrasonic reaction vessel through a connecting mechanism.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: 1. This invention achieves simultaneous, deep, and efficient removal of iron and organic matter in a single process. By combining ultrasonic technology with the goethite method, the iron removal reaction time is shortened by 10-60%, the iron concentration in the solution after iron removal can be reduced to below 0.01 g / L, and the residual TOC content in the solution is below 10 mg / L, which is far superior to traditional processes. 2. The iron-rich goethite slag produced by this invention has a high iron content and a small slag volume, which not only reduces the stockpiling cost and environmental risk, but also enables resource recycling as a raw material for ironmaking; it avoids the hazardous solid waste generated by traditional iron removal processes, and the neutralizing agent is selected from environmentally friendly reagents such as zinc oxide and zinc carbonate, which has no secondary pollution and conforms to the concept of green metallurgy. 3. This invention simplifies the process, shortens the flow, and reduces equipment investment and operating costs; the reaction conditions are mild (atmospheric pressure, 50-95℃), eliminating the need for expensive high-temperature and high-pressure equipment; the device operates stably and is easy to use, significantly reducing investment and operating costs. 4. This invention can treat wet zinc smelting leachate with different compositions and organic contents, and has a good removal effect on various organic substances such as gelatin, tannic acid, and extractants, and has broad prospects for industrial application. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the ultrasonic-assisted goethite method for removing iron and organic matter according to the present invention; Figure 2 This is a graph showing the effect of different organic matter ratios on iron removal rate and TOC removal rate in Example 1 of the present invention. Figure 3 This is a comparison chart of iron removal rate and organic matter removal rate under conventional conditions and ultrasonic conditions in Example 2 of the present invention; Figure 4 This is a comparison diagram showing the effect of ultrasound combined with different oxidants on the removal of iron and organic matter in some embodiments of the present invention; Figure 5 This is a schematic diagram of the ultrasonic reaction system of the present invention; Figure 6 for Figure 5 Main view sectional view of the ultrasonic reactor structure (excluding aeration mechanism); Figure 7 for Figure 6 Front and top views of the mixed feed pipe structure; Figure 8 for Figure 7 Top view of the ultrasonic reactor structure; Figure 9 This is a schematic diagram of the ultrasonic system structure of the present invention.

[0017] Reference numerals: 1. Temperature control system; 101. Cooling coil; 102. Heating element; 103. Temperature sensor; 2. Leachate storage tank; 201. Feed pipe; 202. Discharge pipe; 203. First stirring mechanism; 204. Threaded control valve; 205. Acid-resistant screen filter; 206. Liquid level sensor; 3. Conveying system; 301. Conveying pipeline; 302. Centrifugal pump; 303. Pressure sensor; 304. Bypass valve; 305. Plug valve; 4. Mixing feed pipe; 5. Ultrasonic system; 6. Ultrasonic reaction vessel; 601. Reaction vessel body; 602. Inner reaction cylinder; 603. Discharge port; 7. Ultrasonic generator ; 8. Ultrasonic transducer; 9. Cooling water circulation pipe; 10. Ultrasonic controller; 11. pH control system; 1101. Neutralizing agent storage tank; 1102. Neutralizing agent metering pump; 1103. pH sensor; 1104. pH controller; 12. Second stirring mechanism; 13. Heating device; 14. Oxidizing agent supply system; 141. Flow meter; 142. Porous annular aeration pipe; 143. Aeration port; 144. Gas delivery pipe; 15. Solid-liquid separation unit; 16. Tilting and lifting mechanism; 17. Connecting mechanism; 18. Explosion-proof device; 19. Fixed support; 20. Cooling water outlet; 21. Cooling water inlet; 22. Cable. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings. Figures 1-9 The technical solutions of the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0019] like Figure 1 As shown, this invention discloses a method for removing iron and organic matter from goethite using ultrasound assistance, comprising the following steps: Step 1: Take the wet zinc leaching solution with an initial pH of 2.0-3.5. The leaching solution contains zinc ions at a concentration of 1-120 g / L, total iron at a concentration of 1-5 g / L, and organic matter at a concentration of 1-5 g / L. The organic matter includes gelatin, tannic acid, β-naphthol, and extractant P. 204 Extractant N 235 One or more of the following. After coarse particles are removed by an acid-resistant screen, the leachate enters the leachate storage tank 2 for pretreatment, and then is pumped into the ultrasonic reaction tank 6 by a centrifugal pump 302.

[0020] Step 2: Start the ultrasonic system 5, adjust the ultrasonic frequency to 20-80kHz and the sound intensity to 0.5-5.0W / cm². 2The ultrasonic power is 50-500W, the frequency is 20-40kHz, and the operation mode is continuous or intermittent. Simultaneously, an oxidant with a flow rate of 5-200L / h is introduced into the ultrasonic reactor; the oxidant is one or more of compressed air, industrial oxygen with a purity >98%, or ozone. The oxidant is transported via gas supply pipe 144 to the porous annular aeration pipe 142 inside the ultrasonic reaction tank 6 to achieve uniform aeration.

[0021] Step 3: Control the temperature inside the ultrasonic reaction vessel 6 at 45-90℃, continuously add a neutralizing agent to the ultrasonic reaction vessel 6, and maintain the pH value of the system at 3.5-5.0. The neutralizing agent is one or more of zinc oxide, zinc carbonate, or zinc hydroxide. The total reaction time is 20-240 min. The ultrasonic field is kept on throughout the reaction to allow iron to precipitate in a directional manner as α-FeOOH, and organic matter to be mineralized simultaneously or adsorbed and encapsulated by goethite and co-precipitated.

[0022] Step 4: After the reaction is complete, turn off the ultrasound and allow the slurry to age for 0.5-2 hours. After concentration and filtration, obtain iron-rich goethite slag and purified liquid. The purified liquid is sent to an electrolytic cell for electrowinning. The iron-rich goethite slag, after washing, can be used as a resource for ironmaking or dissolved in sodium hydroxide solution to reduce processing costs.

[0023] The core working principle of this invention lies in the multiple synergistic effects of ultrasound: ① Cavitation effect: When the cavitation bubbles generated by ultrasound burst, a local high-temperature and high-pressure environment is formed, accelerating the hydrolysis reaction of iron ions and the formation of goethite crystal nuclei, causing the precipitate particles to grow and improving the filtration performance of the precipitate; ② Shearing effect: The shearing force of ultrasound can degrade large organic molecules, transforming them into small organic molecules, which are more easily adsorbed, encapsulated, or oxidized and removed by goethite precipitates; ③ Fenton synergistic effect: ferric ions (Fe... 3+ The catalytic properties of [the substance] combined with ultrasound generate a Fenton-like reaction, producing highly oxidizing hydroxyl radicals (·OH), which further enhance the mineralization and decomposition of organic matter, while simultaneously promoting the efficient precipitation and separation of iron. Through the above synergistic effect, this invention constructs a "waste-to-waste" reaction system, achieving the simultaneous deep removal of iron and organic matter.

[0024] The iron removal rate and TOC removal rate of this invention are calculated using the following formula: x0 = (c1 - c0) / c0 × 100%; In the formula: x0 is the iron ion or TOC removal rate, in %; c1 is the mass concentration of iron ions or TOC at any time, in g / L; c0 is the initial mass concentration of iron ions or TOC, in g / L.

[0025] like Figures 5-9As shown, the present invention also discloses a reaction system for the above method, including a leachate storage tank 2, an ultrasonic system 5, a pH control system 11, a conveying system 3, and a solid-liquid separation unit 15. The structure and connection relationship of each part are as follows: The leachate storage tank 2 is made entirely of 316L stainless steel. It includes an inlet pipe 201, an outlet pipe 202, a temperature control system 1, a first stirring mechanism 203, and a level sensor 206. The inlet pipe 201 is connected to an acid-resistant screen filter 205. The acid-resistant screen of the filter 205 is made of polytetrafluoroethylene (PTFE), with a pore size of 150-300 μm, a pH value of 0-14, and a temperature tolerance range of −20-110℃. Its pore size and type can be replaced by a threaded control valve. The outlet pipe 202 is equipped with a bypass valve 304 and a pressure sensor 303. The bypass valve 304 is used for backwashing the pipeline and for safety protection, preventing scaling, blockage, and high pressure. The temperature control system 1 includes a heating element 102, a cooling coil 101, and a temperature sensor 103, all correspondingly installed within the leachate storage tank 2, to prevent the solution from overheating or cooling and affecting ultrasonic efficiency.

[0026] The conveying system 3 connects the leachate storage tank 2 and the ultrasonic reaction tank 6. The conveying system 3 includes a conveying pipe 301 connected to the discharge pipe 202, a centrifugal pump 302 and a stopcock valve 305. The centrifugal pump 302 is made of stainless steel 316L, adopts frequency conversion control, and is linked with the liquid level sensor 206. The bypass valve 304 and the pressure sensor 303 can be connected to the conveying pipe 301 respectively. The pretreated leachate enters the centrifugal pump 302 through the stopcock valve 305 and is conveyed to the ultrasonic reaction tank 6 by the centrifugal pump 302.

[0027] The ultrasonic system 5 includes an ultrasonic reaction vessel 6, an ultrasonic generator 7, an ultrasonic transducer 8, a pH control system 11, a heating device 13, a second stirring mechanism 12, and an oxidant supply system 14. The ultrasonic reaction vessel 6 includes a reaction vessel body 601 and a reaction inner cylinder 602 disposed therein. A discharge port 603 is provided at the lower end of the reaction vessel body 601. The ultrasonic generator 7, pH control system 11, heating device 13, and second stirring mechanism 12 are respectively placed inside the reaction inner cylinder 602. The ultrasonic controller 10 is electrically connected to the ultrasonic transducer 8 and the ultrasonic generator 7 through a cable 22. The ultrasonic power, frequency, and ultrasonic working time are adjusted by the ultrasonic controller 10. The ultrasonic generator 7 includes multiple sets arranged in a ring inside the ultrasonic reaction vessel through fixed supports 19. The oxidant supply system 14 includes a gas supply pipe 144, a flow meter 141, and a porous annular aeration pipe 142. The porous annular aeration pipe 142 is located at the bottom of the ultrasonic reactor 6. The pipe is made of titanium with a pore size of 10-50 μm and has multiple aeration ports 143 arranged circumferentially to ensure uniform gas distribution, improve oxidation efficiency, and reduce energy consumption. The flow meter 141 controls the oxidant flow rate. The ultrasonic reactor 6 is made of polypropylene or stainless steel and has a temperature resistance range of -20-140℃. The reactor body 601 is lined with silicon carbide corrosion-resistant bricks. Tilting and lifting mechanisms 16 are located on both sides of the ultrasonic reactor 6. These mechanisms are connected to the ultrasonic reactor 6 via a connecting mechanism 17, facilitating ultrasonic probe replacement and ensuring operational safety. The ultrasonic reactor 6 is also equipped with an explosion-proof device 18 to prevent localized high pressure and thermal expansion and contraction.

[0028] The pH control system 11 includes a neutralizing agent storage tank 1101, a neutralizing agent metering pump 1102, a pH sensor 1103, and a pH controller 1104. The pH controller 1104 is linked to the neutralizing agent metering pump 1102, and the pH sensor 1103 is correspondingly placed inside the ultrasonic reaction vessel 6. The pH control system 11 has an accuracy of ±0.15. The pH sensor 1103 detects the pH value of the system, and after receiving the signal, the pH controller 1104 controls the neutralizing agent metering pump 1102 to add neutralizing agent from the neutralizing agent storage tank 1101 to the ultrasonic reaction vessel 6.

[0029] The ultrasonic system 5 includes an ultrasonic generator 7, an ultrasonic transducer 8, and a cooling water circulation pipe 9. The ultrasonic generator has a power range of 0-2000W and can adjust the ultrasonic power, frequency, and operating mode. The operating mode can be continuous or intermittent, with a preferred ultrasonic power of 50-500W and a frequency of 20-40kHz. The ultrasonic transducer 8 is a piezoelectric transducer made of 316L stainless steel and has a cooling water inlet 21 and a cooling water outlet 20. The cooling water circulation pipe is made of carbon steel and adopts a bottom-in, top-out flow pattern.

[0030] The solid-liquid separation unit 15 is used to concentrate and filter the reacted slurry to separate iron-rich goethite slag and purified liquid.

[0031] It should be noted that a mixing feed pipe 4 is provided at the top of the ultrasonic reaction vessel, and the gas supply pipe 144, neutralizing agent feed pipe, etc. are integrated in the mixing feed pipe 4.

[0032] The method and reaction system provided by this invention have the following basic process flow: Figure 1 As shown, the core lies in creating optimal initial reaction conditions through specific pretreatment, and then using an oxidant at suitable temperature and pH to initiate and maintain Fe... 3+ The invention relates to a synergistic precipitation-oxidation reaction with organic matter, and will be further described in detail below with reference to specific embodiments.

[0033] Example 1: This embodiment of the invention specifically includes the following steps: (1) Take 1L of wet zinc leaching solution, the composition of which is: zinc ion concentration of 5g / L, total iron concentration of 1g / L, TOC concentration of 800 mg / L, organic matter is tannic acid and gelatin, and the initial pH is 2.6; first remove coarse particles through an acid-resistant screen with a pore size of 200μm, then enter the leaching solution storage tank for heating and stirring pretreatment, and then pump it into an ultrasonic reaction tank through a centrifugal pump; (2) Start the ultrasonic system and adjust the ultrasonic frequency to 20 kHz and the sound intensity to 0.5 W / cm. 2 Meanwhile, oxygen is introduced into the ultrasonic reaction tank through a porous annular aeration pipe, with the flow rate controlled at 30L / h. (3) The temperature inside the ultrasonic reaction vessel was controlled at 75℃. Zinc oxide was continuously added through the neutralizing agent supply system to maintain the pH of the system at 4.5-5.0. The total reaction time was 110 min, and the ultrasonic field was kept on throughout the process. (4) After the reaction is complete, turn off the ultrasonic system, age the slurry for 2 hours, and then concentrate and filter to obtain iron-rich needle iron slag and purified liquid.

[0034] The test results showed that the iron removal rate was 99.65% and the residual TOC in the solution was 6 mg / L.

[0035] The operation of the reaction system used in this embodiment is as follows: the leachate is filtered through an acid-resistant screen and enters the leachate storage tank. Under the action of the temperature control system, a suitable temperature is maintained, and the leachate is stirred evenly by the first stirring mechanism. The stopcock valve is opened, and the leachate is transported to the ultrasonic reaction tank by a centrifugal pump. The oxidant is introduced into the ultrasonic reaction tank through the gas supply pipe, flow meter, and annular aeration pipe to achieve uniform aeration. According to the feedback of the pH control system, the neutralizing agent is sent from the neutralizing agent storage tank to the ultrasonic reaction tank by the neutralizing agent metering pump through the neutralizing agent feed pipe. The ultrasonic system is started and adjusted to the set frequency and power. At the same time, the second stirring mechanism and heating device are turned on to maintain the reaction temperature and system uniformity. After the reaction is completed, the slurry is discharged with the assistance of the tilting and lifting mechanism. After separation by the solid-liquid separation unit, the filtrate is sent to the electrolytic cell, and the filter residue is dried and recycled.

[0036] Example 2: This embodiment of the invention specifically includes the following steps: (1) Take 1L of wet zinc smelting leaching solution, the composition of which is: zinc ion concentration of 1g / L, total iron concentration of 1g / L, TOC concentration of 600 mg / L, organic matter is tannic acid, and initial pH is 2.3; first remove coarse particles by passing it through an acid-resistant screen with a pore size of 150μm, and then put it into the leaching solution storage tank for heating and stirring pretreatment, and then pump it into the ultrasonic reaction tank by a centrifugal pump; (2) Start the ultrasonic system and adjust the ultrasonic frequency to 20kHz and the sound intensity to 0.5W / cm. 2 At the same time, air is introduced into the ultrasonic reaction tank through a porous annular aeration pipe, with the flow rate controlled at 200L / h; (3) The temperature inside the ultrasonic reaction vessel is controlled at 70℃. Zinc oxide is continuously added through the neutralizing agent supply system to maintain the pH of the system at 4.0-4.5. The total reaction time is 120 min. The ultrasonic field is kept on throughout the process. (4) After the reaction is complete, turn off the ultrasonic system, age the slurry for 0.5 hours, and then concentrate and filter to obtain iron-rich goethite slag and purified liquid.

[0037] The test results showed that the iron removal rate was 99.8% and the residual TOC in the solution was 3 mg / L.

[0038] The reaction system used in this embodiment operates in the same manner as in Example 1, and is stable. Compared with the conventional goethite method, the iron removal reaction time is shortened by 30%, and the organic matter removal rate is increased by more than 40%, fully demonstrating the synergistic advantages of ultrasound assistance.

[0039] Example 3: This embodiment of the invention specifically includes the following steps: (1) Take 1L of wet zinc leaching solution, the composition of which is: zinc ion concentration of 50g / L, total iron concentration of 2g / L, TOC concentration of 1000mg / L, organic matter is tannic acid and gelatin, and the initial pH is 2.77; first remove coarse particles by passing it through an acid-resistant screen with a pore size of 250μm, and then put it into the leaching solution storage tank for heating and stirring pretreatment, and then pump it into the ultrasonic reaction tank by a centrifugal pump; (2) Start the ultrasonic system and adjust the ultrasonic frequency to 20kHz and the sound intensity to 1.2W / cm. 2 Meanwhile, ozone is introduced into the ultrasonic reaction tank through a porous annular aeration pipe, with the flow rate controlled at 10L / h. (3) The temperature inside the ultrasonic reaction vessel is controlled at 80℃. Zinc oxide is continuously added through the neutralizing agent supply system to maintain the pH of the system at 3.5-4.0. The total reaction time is 60 min, and the ultrasonic field is kept on throughout the process. (4) After the reaction is complete, turn off the ultrasonic system, age the slurry for 1.0 h, and obtain iron-rich goethite slag and purified liquid by concentration and filtration.

[0040] The test results showed that the iron removal rate was 99.55% and the residual TOC in the solution was 10 mg / L.

[0041] The reaction system used in this embodiment operates in the same manner as in Embodiment 1.

[0042] Example 4: This embodiment of the invention specifically includes the following steps: (1) Take 1L of the wet zinc leaching solution, the composition of which is: zinc ion concentration of 100g / L, total iron concentration of 3g / L, TOC concentration of 1000mg / L, and organic matter of tannic acid, gelatin and P 2O4 The initial pH is 2.23; coarse particles are first removed by passing the solution through an acid-resistant screen with a pore size of 300μm, and then the solution is pretreated by heating and stirring in a leachate storage tank, and then pumped into an ultrasonic reaction tank by a centrifugal pump. (2) Start the ultrasonic system and adjust the ultrasonic frequency to 40kHz and the sound intensity to 2.0W / cm. 2 Meanwhile, ozone is introduced into the ultrasonic reaction tank through a porous annular aeration pipe, with the flow rate controlled at 10L / h. (3) The temperature inside the ultrasonic reaction vessel is controlled at 90℃. Zinc oxide is continuously added through the neutralizing agent supply system to maintain the pH of the system at 3.5-4.0. The total reaction time is 80 min, and the ultrasonic field is kept on throughout the process. (4) After the reaction is complete, turn off the ultrasonic system, age the slurry for 2.0 h, and then concentrate and filter to obtain iron-rich goethite slag and purified liquid.

[0043] The test results showed that the iron removal rate was 99.5% and the residual TOC in the solution was 10 mg / L.

[0044] The reaction system used in this embodiment operates in the same manner as in Embodiment 1.

[0045] Example 5: This embodiment of the invention specifically includes the following steps: (1) Take 1L of the wet zinc leaching solution, the composition of which is: zinc ion concentration of 10g / L, total iron concentration of 3g / L, TOC concentration of 400mg / L, and organic matter is gelatin and P. 204 The initial pH is 2.83; coarse particles are first removed by passing the solution through an acid-resistant screen with a pore size of 200μm, and then the solution is pretreated by heating and stirring in a leachate storage tank, and then pumped into an ultrasonic reaction tank by a centrifugal pump. (2) Start the ultrasonic system and adjust the ultrasonic frequency to 20kHz and the sound intensity to 1.5W / cm. 2 Meanwhile, ozone is introduced into the ultrasonic reaction tank through a porous annular aeration pipe, with the flow rate controlled at 5L / h. (3) The temperature inside the ultrasonic reaction vessel is controlled at 75℃. Zinc hydroxide is continuously added through the neutralizing agent supply system to maintain the pH of the system at 4.0-4.5. The total reaction time is 120 min, and the ultrasonic field is kept on throughout the process. (4) After the reaction is complete, turn off the ultrasonic system, age the slurry for 2.0 h, and then concentrate and filter to obtain iron-rich goethite slag and purified liquid.

[0046] The test results showed that the iron removal rate was 99.57% and the residual TOC in the solution was 7 mg / L.

[0047] The reaction system used in this embodiment operates in the same manner as in Embodiment 1.

[0048] Example 6: This embodiment of the invention specifically includes the following steps: (1) Take 1L of the wet zinc leaching solution, the composition of which is: zinc ion concentration of 10g / L, total iron concentration of 3g / L, TOC concentration of 600mg / L, and organic matter of P. 204 The initial pH is 2.6; coarse particles are first removed by passing the solution through an acid-resistant screen with a pore size of 250μm, and then the solution is pretreated by heating and stirring in a leachate storage tank, and then pumped into an ultrasonic reaction tank by a centrifugal pump. (2) Start the ultrasonic system and adjust the ultrasonic frequency to 40kHz and the sound intensity to 3.8W / cm. 2 Meanwhile, ozone is introduced into the ultrasonic reaction tank through a porous annular aeration pipe, with the flow rate controlled at 12L / h. (3) The temperature inside the ultrasonic reaction vessel is controlled at 80℃. Zinc oxide is continuously added through the neutralizing agent supply system to maintain the pH of the system at 3.8-5.0. The total reaction time is 150 min, and the ultrasonic field is kept on throughout the process. (4) After the reaction is complete, turn off the ultrasonic system, age the slurry for 1.0 h, and obtain iron-rich goethite slag and purified liquid by concentration and filtration.

[0049] The test results showed that the iron removal rate was 99.87% and the residual TOC in the solution was 10 mg / L.

[0050] The reaction system used in this embodiment operates in the same manner as in Embodiment 1.

[0051] Example 7: This embodiment of the invention specifically includes the following steps: (1) Take 1L of wet zinc leaching solution, the composition of which is: zinc ion concentration of 30g / L, total iron concentration of 3g / L, TOC concentration of 500mg / L, organic matter is β-naphthol, and initial pH is 3.3; first remove coarse particles by passing it through an acid-resistant screen with a pore size of 180μm, then enter the leaching solution storage tank for heating and stirring pretreatment, and then pump it into the ultrasonic reaction tank by a centrifugal pump; (2) Start the ultrasonic system and adjust the ultrasonic frequency to 20kHz and the sound intensity to 2.5W / cm. 2 Meanwhile, ozone is introduced into the ultrasonic reaction tank through a porous annular aeration pipe, with the flow rate controlled at 10L / h. (3) The temperature inside the ultrasonic reaction vessel is controlled at 70℃. Zinc carbonate is continuously added through the neutralizing agent supply system to maintain the pH of the system at 3.5-5.0. The total reaction time is 140 min, and the ultrasonic field is kept on throughout the process. (4) After the reaction is complete, turn off the ultrasonic system, age the slurry for 0.5 hours, and then concentrate and filter to obtain iron-rich goethite slag and purified liquid.

[0052] The test results showed that the iron removal rate was 99.7% and the residual TOC in the solution was 9.5 mg / L.

[0053] The reaction system used in this embodiment operates in the same manner as in Embodiment 1.

[0054] The test results of the various embodiments of the present invention show that the method and reaction system of the present invention can efficiently and simultaneously remove iron ions and organic matter from the wet zinc smelting leaching solution. The iron removal rate is above 99.5%, the TOC residue is below 10 mg / L, and the reaction system is stable and easy to operate, which has significant industrial application value.

[0055] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for removing iron and organic matter from goethite using ultrasound-assisted methods, characterized in that, Includes the following steps: Step 1: Take the wet zinc smelting leaching solution with an initial pH of 2.0-3.5, remove coarse particles through an acid-resistant screen, and then pre-treat it in the leaching solution storage tank (2) before pumping it into the ultrasonic reaction tank (6). Step 2: Start the ultrasonic system (5), adjust the ultrasonic frequency to 20-80kHz and the sound intensity to 0.5-5.0W / cm. 2 At the same time, an oxidant with a flow rate of 5-200 L / h is introduced into the ultrasonic reactor; Step 3: Under the condition of 45-90℃, a neutralizing agent is continuously added to the ultrasonic reaction vessel (6) to maintain the pH value of the system at 3.5-5.

0. The total reaction time is 20-240 min. The ultrasonic field is kept on throughout the reaction, so that iron is precipitated in a directional manner as α-FeOOH, and organic matter is simultaneously mineralized or adsorbed and encapsulated by goethite and co-precipitated. Step 4: After the reaction is complete, turn off the ultrasound and let the slurry age for 0.5-2 hours. After concentration and filtration, the iron-rich goethite slag and purified liquid are obtained.

2. The method for removing iron and organic matter from goethite using ultrasound-assisted methods according to claim 1, characterized in that, In step 1, the leaching solution contains zinc ions at a concentration of 1-120 g / L, total iron at a concentration of 1-5 g / L, and organic matter at a concentration of 1-5 g / L; the organic matter includes gelatin, tannic acid, β-naphthol, and extractant P. 204 Extractant N 235 One or more of them.

3. The method for removing iron and organic matter from goethite using ultrasound-assisted methods according to claim 1, characterized in that, The neutralizing agent is one or more of zinc oxide, zinc carbonate, or zinc hydroxide; the oxidizing agent is one or more of compressed air, industrial oxygen, or ozone.

4. The method for removing iron and organic matter from goethite using ultrasound-assisted methods according to claim 1, characterized in that, The ultrasonic system (5) has an ultrasonic power of 50-500W, a frequency of 20-40kHz, and operates in either continuous or intermittent mode.

5. A reaction system for use in the method of any one of claims 1-4, characterized in that, include: The leachate storage tank (2) is equipped with an inlet pipe (201), an outlet pipe (202), a temperature control system (1), a first stirring mechanism (203), and a liquid level sensor (206); the inlet pipe (201) is connected to an acid-resistant screen filter (205), and the outlet pipe (202) is equipped with a bypass valve (304) and a pressure sensor (303); the temperature control system (1) includes a heating element (102), a cooling coil (101), and a temperature sensor (103) correspondingly installed in the leachate storage tank (2); An ultrasonic system (5) includes an ultrasonic reaction vessel (6), an ultrasonic generator (7), an ultrasonic transducer (8), a pH control system (11), a heating device (13), a second stirring mechanism (12), and an oxidant supply system (14); the ultrasonic reaction vessel (6) includes a reaction vessel body (601) and a reaction inner cylinder (602) disposed therein; the ultrasonic generator (7), pH control system (11), heating device (13), and second stirring mechanism (12) are respectively placed inside the reaction inner cylinder (602); the ultrasonic transducer (8) is electrically connected to the ultrasonic generator (7); the oxidant supply system (14) includes a gas supply pipe (144), a flow meter (141), and a porous annular aeration pipe (142), the porous annular aeration pipe (142) being respectively disposed at the bottom of the ultrasonic reaction vessel (6); pH control system (11), the pH control system (11) includes neutralizer storage tank (1101), neutralizer metering pump (1102), pH sensor (1103) and pH controller (1104), the pH controller (1104) is linked with neutralizer metering pump (1102), and the pH sensor (1103) is correspondingly placed in ultrasonic reaction vessel (6); The conveying system (3) connects the leachate storage tank (2) and the ultrasonic reaction tank (6), including a centrifugal pump (302) and a stopcock valve (305). The pretreated leachate is controlled to enter the centrifugal pump (302) through the stopcock valve (305) and is conveyed to the ultrasonic reaction tank (6) by the centrifugal pump (302). Solid-liquid separation unit (15) is used to concentrate and filter the slurry after reaction.

6. The reaction system according to claim 5, characterized in that, The acid-resistant screen filter (205) is made of polytetrafluoroethylene with a pore size of 150-300μm, a pH value of 0-14 for acid and alkali resistance, and a temperature tolerance range of -20-110℃. Its pore size and type can be disassembled and replaced by a threaded control valve. The centrifugal pump (302) is made of 316L stainless steel, uses frequency conversion control, and is linked with the liquid level sensor (206).

7. The reaction system according to claim 5, characterized in that, The ultrasonic system (5) also includes a cooling water circulation pipe, which is made of carbon steel and adopts a bottom-in, top-out flow method; the ultrasonic transducer (8) is a piezoelectric transducer made of 316L stainless steel and is equipped with a cooling water inlet and a cooling water outlet.

8. The reaction system according to claim 5, characterized in that, The ultrasonic reaction vessel (6) is made of polypropylene or stainless steel and has a temperature range of -20 to 140°C. The reaction vessel body (601) is lined with silicon carbide corrosion-resistant bricks. The porous annular aeration pipe (142) is made of titanium and has a pore size of 10-50 μm.

9. The reaction system according to claim 5, characterized in that, The pH control system (11) has an accuracy of ±0.

15. The pH value of the system is detected by the pH sensor (1103). After receiving the signal, the pH controller (1104) controls the neutralizer metering pump (1102) to add neutralizer from the neutralizer storage tank (1101) to the ultrasonic reaction tank (6).

10. The reaction system according to claim 5, characterized in that, The ultrasonic reaction vessel (6) is provided with tilting and lifting mechanisms (16) on both sides, and the tilting and lifting mechanisms (16) are connected to the ultrasonic reaction vessel (6) through a connecting mechanism (17).

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