New process for extracting valuable elements from iron tailings

Abstract

The invention relates to the technical field of metallurgical engineering and resource recovery, and discloses a novel process for extracting valuable elements from iron tailings, which comprises the following steps: S1, carrying out secondary crushing and ore grinding on the iron tailings, and blending into ore pulp with the concentration of 30-40%; s2, the ore pulp is subjected to microwave heating through selective microwave heating equipment; s3, the ore pulp subjected to microwave heating is introduced into a plasma reactor, and mineral compounds in the tailings are decomposed through plasma at high temperature; s4, the ore pulp obtained after plasma decomposition is cooled and prepared into a solution with the proper concentration; s5, the prepared solution is subjected to electrochemical deposition, and metal is recycled; and S6, supercritical water oxidation treatment is conducted on the tailing waste residues obtained after electrochemical deposition. Through microwave heating, plasma high-temperature decomposition and supercritical water oxidation technologies, the problems of high energy consumption, non-uniform heating, incomplete decomposition and serious waste residue pollution in a traditional method are solved, and efficient, accurate and environment-friendly iron tailing valuable element extraction is realized.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical engineering and resource recovery, and in particular to a new process for extracting valuable elements from iron tailings. Background Art

[0002] Iron tailings are a large amount of solid waste generated during the production process of the steel industry. With the continuous growth of global steel production, the accumulation of iron tailings is also increasing. According to statistics, the world produces about hundreds of millions of tons of iron tailings each year, which contain a large amount of valuable elements such as iron, titanium, cobalt, etc. If these valuable elements are not recycled, it will not only cause a huge waste of resources, but also cause serious pollution to the environment. Therefore, how to efficiently extract valuable elements from iron tailings is an important research topic in the current field of mineral processing and environmental engineering.

[0003] In the existing technology for extracting valuable elements from iron tailings, the main methods include mechanical crushing and grinding, chemical leaching, high-temperature calcination and conventional chemical precipitation. These methods have achieved certain results in practical applications, but there are still some significant defects and shortcomings: chemical leaching methods often require a long reaction time and consume a large amount of chemical agents. The treated waste liquid is difficult to handle and is prone to secondary pollution to the environment. At the same time, the leaching efficiency is low, and the recovery rate of valuable elements is not high. At the same time, the conventional chemical precipitation method has low precipitation efficiency, the purity of the precipitate is not high, and the waste residue generated during the precipitation process is difficult to handle, which has a greater impact on the environment. Chemical precipitation requires the use of a large amount of precipitant, which increases the processing cost. Therefore, in view of the above-mentioned defects and shortcomings, the present invention proposes a new process for extracting valuable elements from iron tailings. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a new process for extracting valuable elements from iron tailings, which solves the problems of high energy consumption, incomplete decomposition and serious pollution from waste residue treatment in the traditional process of extracting valuable elements from iron tailings.

[0005] To achieve the above objectives, the present invention is implemented by the following technical scheme: a new process for extracting valuable elements from iron tailings, comprising the following steps: S1. Secondary crushing and grinding of the iron tailings to prepare a slurry with a concentration of 30%-40%; S2, using a selective microwave heating device to perform microwave heating on the slurry; S3, introducing the microwave-heated slurry into a plasma reactor to decompose the mineral compounds in the tailings by high temperature plasma; S4, cooling the ore pulp after plasma decomposition and preparing it into a solution of appropriate concentration; S5, electrochemically depositing the prepared solution to recover the metal; S6. The tailings waste after electrochemical deposition is subjected to supercritical water oxidation treatment.

[0006] Preferably, the particle size of the crushed product obtained by the primary crushing in step S1 is 10-50 mm, the particle size of the crushed product obtained by the secondary crushing in step S1 is 1-10 mm, and the particle size of the slurry obtained by grinding in step S1 is between 100-200 meshes.

[0007] Preferably, the step S2 specifically includes the following steps: S2.1. Preparation for microwave heating: Adjust the frequency of the microwave heating equipment to 0.915-2.45 GHz and the power to 1-10 kW to suit the dielectric properties of the mineral, and determine the microwave heating time to be 5-30 min and the heating temperature to be 50-200 °C; S2.2, Microwave Heating Process: The prepared slurry is continuously transported to the microwave heating equipment at a speed of 0.1-1m / s; S2.3, microwave heating post-treatment: The microwave heating time is controlled to be 5-30min, the slurry temperature is monitored at 50-200°C during discharge, and the particle size change is monitored to be 100-200 mesh.

[0008] Preferably, the dielectric properties in step S2.1 include dielectric constant, dielectric loss factor and conductivity.

[0009] Preferably, the plasma reaction atmosphere in step S3 is hydrogen or nitrogen.

[0010] Preferably, the step S4 specifically includes the following steps: S4.1. Cooling: Cooling the high-temperature slurry after the plasma reaction through a cooling device; S4.2, solution preparation: The cooled slurry is mixed with deionized water to prepare a solution with a concentration between 10% and 20%; S4.3, homogenization treatment: Use stirring equipment to homogenize the slurry solution.

[0011] Preferably, in step S4.2, the cooled slurry is mixed with deionized water in a ratio of 1:4 to 1:9.

[0012] Preferably, the step S5 specifically includes the following steps: S5.1. Preparation for electrochemical deposition: Configure an electrolytic cell, select titanium alloy as the electrode material, and prepare sulfuric acid or sodium chloride solution as the electrolyte; S5.2, Electrochemical reaction: Introduce the modulated solution into the electrolytic cell, adjust the voltage in the electrolytic cell to 1-5V and the current density to 50-200A / m²; S5.3, Metal Deposition: Carry out metal deposition reaction on the cathode and monitor the changes in pH and conductivity of the solution during the electrolysis process; S5.4. Recycling of Metals: The metal deposits on the cathode are cleaned regularly, and the deposited metals are dried and purified.

[0013] Preferably, the step S6 specifically includes the following steps: S6.1. Preparation for waste residue treatment: The tailings waste residue after electrochemical deposition is subjected to solid-liquid separation, and the solid waste residue is collected and introduced into a supercritical water oxidation reactor; S6.2, Supercritical water oxidation reaction: Adjust the reactor temperature to above 374°C and the pressure to above 22.1MPa to treat the organic matter and difficult-to-treat substances in the waste residue under supercritical water conditions; S6.3, oxidation treatment: Select 90%-100% oxygen and adjust the flow rate of the oxidizing atmosphere between 10-50L / min, conduct online monitoring and sampling analysis, and completely oxidize the harmful substances in the waste residue during the supercritical water oxidation treatment process; S6.4, harmless treatment: The treated waste residue is subjected to solid-liquid separation and drying.

[0014] Preferably, the solid waste residue treated in step S6.4 is used for resource utilization as building materials or roadbed materials.

[0015] The present invention provides a new process for extracting valuable elements from iron tailings. It has the following beneficial effects: 1. The present invention adopts frequency-adjustable and high-power microwave heating equipment to selectively heat the dielectric properties of minerals, thereby solving the problems of high energy consumption and uneven heating in traditional heating methods, improving the heating accuracy and efficiency, and reducing energy consumption.

[0016] 2. The present invention utilizes plasma high temperature to decompose mineral compounds, which can quickly and completely decompose complex mineral structures, making it easier to extract valuable elements. This solves the problems of slow and incomplete decomposition of traditional chemical methods and improves decomposition efficiency and purity.

[0017] 3. The present invention uses supercritical water oxidation technology to treat tailings waste, completely oxidizes harmful substances under high temperature and high pressure, achieves the effect of harmless treatment, solves the problems of serious pollution and incomplete treatment in traditional waste treatment methods, and realizes green and environmentally friendly treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0020] Please refer to the attached Figure 1 The embodiment of the present invention provides a new process for extracting valuable elements from iron tailings, comprising the following steps: S1. Secondary crushing and grinding of the iron tailings to prepare a slurry with a concentration of 30%-40%; S2, using a selective microwave heating device to perform microwave heating on the slurry; S3, introducing the microwave-heated slurry into a plasma reactor to decompose the mineral compounds in the tailings by high temperature plasma; S4, cooling the ore pulp after plasma decomposition and preparing it into a solution of appropriate concentration; S5, electrochemically depositing the prepared solution to recover the metal; S6. The tailings waste after electrochemical deposition is subjected to supercritical water oxidation treatment.

[0021] The particle size of the crushed product obtained by the primary crushing in step S1 is 10-50 mm, the particle size of the crushed product obtained by the secondary crushing in step S1 is 1-10 mm, and the particle size of the slurry obtained by grinding in step S1 is between 100-200 meshes.

[0022] The S2 step specifically includes the following steps: S2.1. Preparation for microwave heating: Adjust the frequency of the microwave heating equipment to 0.915-2.45 GHz and the power to 1-10 kW to suit the dielectric properties of the mineral, and determine the microwave heating time to be 5-30 min and the heating temperature to be 50-200 °C; S2.2, Microwave Heating Process: The prepared slurry is continuously transported to the microwave heating equipment at a speed of 0.1-1m / s; S2.3, microwave heating post-treatment: The microwave heating time is controlled to be 5-30min, the slurry temperature is monitored at 50-200°C during discharge, and the particle size change is monitored to be 100-200 mesh.

[0023] The dielectric properties in step S2.1 include dielectric constant, dielectric loss factor and conductivity.

[0024] In step S3, the plasma reaction atmosphere is hydrogen or nitrogen.

[0025] The S4 step specifically includes the following steps: S4.1. Cooling: Cooling the high-temperature slurry after the plasma reaction through a cooling device; S4.2, solution preparation: The cooled slurry is mixed with deionized water to prepare a solution with a concentration between 10% and 20%; S4.3, homogenization treatment: Use stirring equipment to homogenize the slurry solution.

[0026] The cooled slurry in step S4.2 is mixed with deionized water in a ratio of 1:4 to 1:9.

[0027] Step S5 specifically includes the following steps: S5.1. Preparation for electrochemical deposition: Configure an electrolytic cell, select titanium alloy as the electrode material, and prepare sulfuric acid or sodium chloride solution as the electrolyte; S5.2, Electrochemical reaction: Introduce the modulated solution into the electrolytic cell, adjust the voltage in the electrolytic cell to 1-5V and the current density to 50-200A / m²; S5.3, Metal Deposition: Carry out metal deposition reaction on the cathode and monitor the changes in pH and conductivity of the solution during the electrolysis process; S5.4. Recycling of Metals: The metal deposits on the cathode are cleaned regularly, and the deposited metals are dried and purified.

[0028] Step S6 specifically includes the following steps: S6.1. Preparation for waste residue treatment: The tailings waste residue after electrochemical deposition is subjected to solid-liquid separation, and the solid waste residue is collected and introduced into a supercritical water oxidation reactor; S6.2, Supercritical water oxidation reaction: Adjust the reactor temperature to above 374°C and the pressure to above 22.1MPa to treat the organic matter and difficult-to-treat substances in the waste residue under supercritical water conditions; S6.3, oxidation treatment: Select 90%-100% oxygen and adjust the flow rate of the oxidizing atmosphere between 10-50L / min, conduct online monitoring and sampling analysis, and completely oxidize the harmful substances in the waste residue during the supercritical water oxidation treatment process; S6.4, harmless treatment: The treated waste residue is subjected to solid-liquid separation and drying.

[0029] The solid waste residue treated in step S6.4 is used for resource utilization as building materials or roadbed materials.

[0030] Embodiment 1: Implementation steps: S1. Secondary crushing and grinding: Primary crushing: The jaw crusher has a discharge opening width of 20 mm and the particle size obtained is between 20 and 30 mm. Secondary crushing: The discharge width of the cone crusher is 5mm, and the particle size obtained is between 5-8mm; Grinding: The ball mill grinding time is 30 minutes, and the ore pulp with a particle size of 150 mesh is obtained; Adjust the ore pulp: the ore pulp concentration is adjusted to 35%.

[0031] S2, Selective Microwave Heating: Microwave heating preparation: microwave frequency is 2.45 GHz, power is 8 kW, heating time is 15 min, heating temperature is 100 °C; Microwave heating process: slurry conveying speed is 0.5m / s; Microwave heating post-treatment: The slurry temperature was monitored at 100°C and the particle size change was maintained at 150 mesh.

[0032] S3, plasma pyrolysis: Plasma reaction atmosphere: hydrogen; Plasma temperature: 6000℃; Reaction time: 5min.

[0033] S4, cooling and solution preparation: Cooling: cooling rate is 30℃ / min; Solution preparation: The cooled slurry is mixed with deionized water in a ratio of 1:6 and prepared into a solution concentration of 15%; Homogenization treatment: stirring speed is 300 rpm, stirring time is 10 min.

[0034] S5. Electrochemical deposition: Preparation for electrochemical deposition: The electrolyte was 1 M sulfuric acid; Electrochemical reaction: voltage is 3V, current density is 150A / m²; Metal deposition: deposition time is 6 hours; Metal recovery: drying temperature is 80°C and drying time is 3 hours.

[0035] S6. Supercritical water oxidation treatment: Waste residue treatment preparation: centrifuge for solid-liquid separation; Supercritical water oxidation reaction: temperature is 380°C and pressure is 23MPa; Oxidation treatment: oxygen concentration is 95%, atmosphere flow rate is 30L / min; Harmless treatment: drying temperature is 90℃ and drying time is 4 hours.

[0036] Summary: This example is operated with standard parameters to ensure that basic conditions such as slurry particle size, concentration, reaction temperature and pressure meet the requirements, thereby achieving complete oxidation of harmful substances and effective recovery of metals.

[0037] Embodiment 2: Implementation steps: S1. Secondary crushing and grinding: Primary crushing: The jaw crusher has a discharge opening width of 15 mm and the particle size obtained is between 15 and 25 mm. Secondary crushing: The discharge width of the cone crusher is 4mm, and the particle size obtained is between 4-7mm; Grinding: The ball mill grinding time is 25min, and the ore pulp with a particle size of 170 mesh is obtained; Adjust the ore pulp: the ore pulp concentration is adjusted to 32%.

[0038] S2, Selective Microwave Heating: Microwave heating preparation: microwave frequency is 2.45 GHz, power is 9 kW, heating time is 20 min, heating temperature is 150 °C; Microwave heating process: slurry conveying speed is 0.4m / s; Microwave heating post-treatment: The slurry temperature was monitored at 150°C and the particle size change was maintained at 170 mesh.

[0039] S3, plasma pyrolysis: Plasma reaction atmosphere: nitrogen; Plasma temperature: 6500℃; Reaction time: 4min.

[0040] S4, cooling and solution preparation: Cooling: cooling rate is 40℃ / min; Solution preparation: The cooled slurry is mixed with deionized water in a ratio of 1:7 and prepared into a solution concentration of 14%; Homogenization treatment: stirring speed is 350 rpm, stirring time is 15 min.

[0041] S5. Electrochemical deposition: Preparation for electrochemical deposition: The electrolyte was 1 M sodium chloride; Electrochemical reaction: voltage is 2.5V, current density is 170A / m²; Metal deposition: deposition time is 5 hours; Recovered metals: drying temperature is 75°C and drying time is 2.5 hours.

[0042] S6. Supercritical water oxidation treatment: Preparation for waste residue treatment: Filters for solid-liquid separation; Supercritical water oxidation reaction: temperature is 385°C and pressure is 24MPa; Oxidation treatment: oxygen concentration is 98%, atmosphere flow rate is 40L / min; Harmless treatment: Drying temperature is 95℃ and drying time is 3.5 hours.

[0043] Summary: Based on the previous embodiment, this embodiment further optimizes the parameters of the crushing and grinding steps, increases the power and temperature of microwave heating, increases the current density and deposition time of the electrochemical reaction, and improves the recovery rate of valuable elements.

[0044] Embodiment three: Implementation steps: S1. Secondary crushing and grinding: Primary crushing: The jaw crusher has a discharge opening width of 12 mm and the particle size obtained is between 12-20 mm; Secondary crushing: The discharge width of the cone crusher is 3mm, and the particle size obtained is between 3-6mm; Grinding: The ball mill grinding time is 20 minutes, and the ore pulp with a particle size of 180 mesh is obtained; Adjust the ore pulp: the ore pulp concentration is adjusted to 34%.

[0045] S2, Selective Microwave Heating: Microwave heating preparation: microwave frequency is 2.45 GHz, power is 10 kW, heating time is 25 min, heating temperature is 175 °C; Microwave heating process: slurry conveying speed is 0.3m / s; Microwave heating post-treatment: The slurry temperature was monitored at 175°C and the particle size change was maintained at 180 mesh.

[0046] S3, plasma pyrolysis: Plasma reaction atmosphere: hydrogen; Plasma temperature: 7000℃; Reaction time: 3min.

[0047] S4, cooling and solution preparation: Cooling: cooling rate is 50℃ / min; Solution preparation: The cooled slurry is mixed with deionized water in a ratio of 1:8 and prepared into a solution concentration of 12%; Homogenization treatment: stirring speed is 400 rpm, stirring time is 20 min.

[0048] S5. Electrochemical deposition: Preparation for electrochemical deposition: The electrolyte was 1 M sulfuric acid; Electrochemical reaction: voltage is 4V, current density is 180A / m²; Metal deposition: deposition time is 7 hours; Recovered metals: drying temperature is 85°C and drying time is 3 hours.

[0049] S6. Supercritical water oxidation treatment: Waste residue treatment preparation: centrifuge for solid-liquid separation; Supercritical water oxidation reaction: temperature is 390°C and pressure is 25MPa; Oxidation treatment: oxygen concentration is 99%, atmosphere flow rate is 35L / min; Harmless treatment: drying temperature is 100℃ and drying time is 4 hours.

[0050] Summary: This embodiment further improves the accuracy and parameters of each step, especially in the plasma pyrolysis and electrochemical deposition steps, using higher temperature and current density, which significantly improves the metal recovery rate and processing efficiency.

[0051] Embodiment 4: Implementation steps: S1. Secondary crushing and grinding: Primary crushing: The jaw crusher has a discharge opening width of 10 mm and the particle size obtained is between 10-18 mm; Secondary crushing: The discharge width of the cone crusher is 2.5mm, and the particle size obtained is between 2.5-5mm; Grinding: The ball mill grinding time is 18 minutes, and the ore pulp with a particle size of 190 mesh is obtained; Adjust the ore pulp: the ore pulp concentration is adjusted to 36%.

[0052] S2, Selective Microwave Heating: Microwave heating preparation: microwave frequency is 2.45 GHz, power is 11 kW, heating time is 28 min, heating temperature is 190 °C; Microwave heating process: slurry conveying speed is 0.25m / s; Microwave heating post-treatment: The slurry temperature was monitored at 190°C and the particle size change was maintained at 190 mesh.

[0053] S3, plasma pyrolysis: Plasma reaction atmosphere: nitrogen; Plasma temperature: 7500℃; Reaction time: 2.5min.

[0054] S4, cooling and solution preparation: Cooling: cooling rate is 45℃ / min; Solution preparation: The cooled slurry is mixed with deionized water in a ratio of 1:9 and prepared into a solution concentration of 11%; Homogenization treatment: stirring speed is 450 rpm, stirring time is 18 min.

[0055] S5. Electrochemical deposition: Preparation for electrochemical deposition: The electrolyte was 1 M sodium chloride; Electrochemical reaction: voltage is 4.5V, current density is 190A / m²; Metal deposition: deposition time is 8 hours; Recovered metals: drying temperature is 90°C and drying time is 3.5 hours.

[0056] S6. Supercritical water oxidation treatment: Preparation for waste residue treatment: Filters for solid-liquid separation; Supercritical water oxidation reaction: temperature is 395°C and pressure is 26MPa; Oxidation treatment: oxygen concentration is 100%, atmosphere flow rate is 45L / min; Harmless treatment: Drying temperature is 105℃ and drying time is 4.5 hours.

[0057] Summary: Based on the previous embodiment, this embodiment further optimizes the parameters of the crushing, grinding and microwave heating steps, especially increases the power and temperature of microwave heating, and adopts more efficient atmosphere flow rate and oxygen concentration, thereby greatly improving the metal extraction efficiency and environmental protection treatment effect.

[0058] Embodiment five: Implementation steps: S1. Secondary crushing and grinding: Primary crushing: The jaw crusher has a discharge opening width of 8 mm and the particle size obtained is between 8 and 15 mm; Secondary crushing: The discharge width of the cone crusher is 2mm, and the particle size obtained is between 2-4mm; Grinding: The ball mill grinding time is 15min, and the ore pulp with a particle size of 200 mesh is obtained; Adjust the ore pulp: the ore pulp concentration is adjusted to 38%.

[0059] S2, Selective Microwave Heating: Microwave heating preparation: microwave frequency is 2.45 GHz, power is 12 kW, heating time is 30 min, heating temperature is 200 °C; Microwave heating process: slurry conveying speed is 0.2m / s; Microwave heating post-treatment: The slurry temperature was monitored at 200°C and the particle size change was maintained at 200 mesh.

[0060] S3, plasma pyrolysis: Plasma reaction atmosphere: hydrogen; Plasma temperature: 8000℃; Reaction time: 2min.

[0061] S4, cooling and solution preparation: Cooling: cooling rate is 50℃ / min; Solution preparation: The cooled slurry is mixed with deionized water in a ratio of 1:9 and prepared into a solution concentration of 10%; Homogenization treatment: stirring speed is 500 rpm, stirring time is 20 min.

[0062] S5. Electrochemical deposition: Preparation for electrochemical deposition: The electrolyte was 1 M sulfuric acid; Electrochemical reaction: voltage is 5V, current density is 200A / m²; Metal deposition: deposition time is 9 hours; Recovered metals: drying temperature is 95°C and drying time is 4 hours.

[0063] S6. Supercritical water oxidation treatment: Waste residue treatment preparation: centrifuge for solid-liquid separation; Supercritical water oxidation reaction: temperature is 400°C and pressure is 27MPa; Oxidation treatment: oxygen concentration is 100%, atmosphere flow rate is 50L / min; Harmless treatment: drying temperature is 110℃ and drying time is 5 hours.

[0064] Summary: This embodiment further improves the accuracy and parameters of each step, especially in the plasma pyrolysis and electrochemical deposition steps, using higher temperature and current density, significantly improving the metal recovery rate and processing efficiency. At the same time, the optimization of supercritical water oxidation treatment achieves the best harmless treatment effect of waste residue.

[0065] Summary: Through these five examples, each step in the new process of extracting valuable elements from iron tailings was gradually optimized, from initial crushing to supercritical water oxidation treatment, the parameters were gradually refined, and the efficiency and effect of each step were improved. In each example, we adjusted the particle size of crushing and grinding, the frequency and power of microwave heating, the atmosphere and temperature of plasma reaction, the current density and time of electrochemical deposition, and the oxygen concentration and flow rate of supercritical water oxidation treatment, thereby achieving a higher metal recovery rate and better environmental protection effect.

[0066] Comparative experiment 1: Verifying the effectiveness of the process of the present invention Purpose: Verify the advantages of the new process for extracting valuable elements from iron tailings proposed in the present invention in terms of metal recovery rate, energy consumption, processing efficiency and environmental protection treatment effect, and whether the technical solution of the present invention is innovative and practical compared with the existing technology.

[0067] Experimental Materials: Iron tailings samples Pure oxygen, hydrogen, nitrogen 1M sulfuric acid, 1M sodium chloride solution High-precision temperature sensor, pressure sensor Microwave heating equipment, plasma reactor, electrolyzer, supercritical water oxidation reactor Automatic control system and online monitoring system Experimental design: Control group: Valuable elements were extracted from iron tailings using traditional technology.

[0068] Control group 1: Mechanical crushing + chemical leaching + conventional precipitation method to treat waste residue Control group 2: ball mill grinding + chemical leaching + conventional precipitation method to treat waste residue Control group 3: Mechanical crushing + high temperature calcination + chemical leaching + conventional precipitation method to treat waste residue Control group 4: ball mill grinding + high temperature calcination + chemical leaching + conventional precipitation method to treat waste residue Experimental group: Using the new process for extracting valuable elements from iron tailings proposed by the present invention, experiments were conducted according to the parameters of the five embodiments.

[0069] Experimental Group 1: Process Parameters of Example 1 Experimental Group 2: Process Parameters of Example 2 Experimental Group 3: Process Parameters of Example 3 Experimental Group 4: Process Parameters of Example 4 Experimental Group 5: Process Parameters of Example 5 Experimental steps: Sample preparation: The iron tailings samples were divided into nine parts, which were used for four control groups and five experimental groups.

[0070] Crushing and Grinding: Control groups 1 and 3: mechanical disruption equipment was used.

[0071] Control groups 2 and 4: ball mill grinding equipment was used.

[0072] Experimental group: The crushing and grinding parameters of the five embodiments were used.

[0073] Heat treatment: Control groups 1 and 2: No high temperature treatment, direct chemical leaching.

[0074] Control groups 3 and 4: high temperature calcination was performed using conventional resistance heating equipment.

[0075] Experimental group: using a selective microwave heating device, microwave heating was performed according to the parameters of the embodiment.

[0076] Decomposition of mineral compounds: Control groups 1, 2, 3 and 4: Iron tailings were treated using chemical leaching.

[0077] Experimental group: using a plasma reactor, pyrolysis was performed according to the parameters of the embodiment.

[0078] Solution preparation and metal deposition: Control groups 1, 2, 3 and 4: The solutions were prepared using conventional methods and chemical precipitation was performed.

[0079] Experimental group: Cooling, solution preparation and electrochemical deposition were carried out according to the parameters of the embodiment.

[0080] Waste treatment: Control groups 1, 2, 3 and 4: The waste residue was treated using conventional chemical precipitation method.

[0081] Experimental group: A supercritical water oxidation reactor was used to perform harmless treatment according to the parameters of the embodiment.

[0082] Data recording and analysis: Metal recovery rate: The mass of metal recovered in each set of experiments was determined and the recovery rate was calculated.

[0083] Energy consumption: record the energy consumption of each group of experiments and calculate the energy consumption per ton of iron tailings processed.

[0084] Processing efficiency: Record the processing time of each group of experiments and calculate the processing efficiency.

[0085] Environmental protection treatment effect: detect the residual amount of harmful substances in the waste slag and evaluate the environmental protection treatment effect.

[0086] Table 1: Experimental summary: Metal recovery rate: The experimental results show that the metal recovery rate of the experimental group is significantly higher than that of all the control groups, especially the experimental group 5 which reaches the highest recovery rate of 95%, indicating that the process of the present invention significantly improves the metal recovery rate by optimizing the steps of crushing, grinding, microwave heating and plasma high temperature decomposition.

[0087] Energy consumption: The energy consumption of the experimental groups was significantly lower than that of all the control groups. The energy consumption of experimental group 5 was the lowest, which was only 110 kWh / ton, indicating that the process of the present invention has significant advantages in energy consumption, mainly due to selective microwave heating and efficient plasma decomposition.

[0088] Treatment efficiency: The treatment time of the experimental groups was shorter than that of all the control groups. The treatment time of Experimental Group 5 was the shortest, which was only 7 hours. This proves that the process of the present invention has a significant improvement in treatment efficiency, which is attributed to faster microwave heating and plasma reaction.

[0089] Environmental protection treatment effect: The residual amount of harmful substances in the waste slag of the experimental group was significantly lower than that of all the control groups. The residual amount in the experimental group 5 was the lowest, which was only 60ppm. This shows that the process of the present invention achieves more efficient harmless treatment of waste slag through supercritical water oxidation treatment.

[0090] Through comparative experiments, it is verified that the new process for extracting valuable elements from iron tailings of the present invention is superior to many existing technologies in terms of metal recovery rate, energy consumption, processing efficiency and environmental protection treatment effect, and has significant innovation and practicality.

[0091] Comparative experiment 2: Comparison of energy consumption and efficiency between microwave heating and traditional heating Purpose: Verify the advantages of the selective microwave heating technology in the present invention in terms of energy consumption and efficiency.

[0092] Experimental Materials: Iron tailings samples Microwave heating equipment Resistance heating equipment High-precision temperature sensor Automation control system Experimental design: Control group: The iron tailings were heated using conventional resistance heating.

[0093] Experimental group: using the selective microwave heating technology of the present invention.

[0094] Experimental steps: Sample preparation: The iron tailings samples were divided into two parts, one for the control group and the other for the experimental group.

[0095] Heat treatment: Control group: The iron tailings samples were heated to 200°C using a resistance heating device, and the heating time and energy consumption were recorded.

[0096] Experimental group: The iron tailings samples were heated to 200°C using a selective microwave heating device, and the heating time and energy consumption were recorded.

[0097] Data recording and analysis: Energy consumption: Record the energy consumption of each group of experiments and calculate the energy required to heat to 200°C.

[0098] Processing efficiency: record the heating time of each group of experiments and calculate the heating efficiency.

[0099] Table 2: Experimental summary: The experimental results show that microwave heating is significantly superior to traditional resistance heating in terms of heating time and energy consumption, verifying the high efficiency and energy saving of the selective microwave heating technology in the present invention.

[0100] Comparative experiment 3: Comparison between plasma pyrolysis and chemical leaching Purpose: The advantages of the plasma pyrolysis technology in the present invention in terms of metal recovery rate and processing efficiency are verified.

[0101] Experimental Materials: Iron tailings samples Plasma Reactor Chemical leaching equipment High-precision temperature sensor Automation control system Experimental design: Control group: The iron tailings were treated using traditional chemical leaching method.

[0102] Experimental group: using the plasma pyrolysis technology of the present invention.

[0103] Experimental steps: Sample preparation: The iron tailings samples were divided into two parts, one for the control group and the other for the experimental group.

[0104] Processing steps: Control group: Use chemical leaching equipment to leach the iron tailings samples, and record the processing time and metal recovery rate.

[0105] Experimental group: Using a plasma reactor, the iron tailings samples were subjected to high temperature decomposition, and the processing time and metal recovery rate were recorded.

[0106] Data recording and analysis: Metal recovery rate: The mass of metal recovered in each set of experiments was determined and the recovery rate was calculated.

[0107] Processing efficiency: record the processing time of each group of experiments and calculate the processing efficiency.

[0108] Table 3: Experimental summary: The experimental results show that plasma pyrolysis is significantly superior to traditional chemical leaching in terms of processing time and metal recovery rate, verifying the high efficiency and high recovery rate of the plasma pyrolysis technology in the present invention.

[0109] Comparative experiment 4: Comparison between supercritical water oxidation and conventional chemical precipitation Purpose: Verify the advantages of the supercritical water oxidation technology in the present invention in terms of waste residue treatment effect and environmental protection.

[0110] Experimental Materials: Iron tailings waste sample Supercritical water oxidation reactor Conventional chemical precipitation equipment High-precision temperature and pressure sensors Automation control system Experimental design: Control group: The iron ore tailings waste was treated using traditional chemical precipitation method.

[0111] Experimental group: The iron tailings waste was treated using the supercritical water oxidation technology of the present invention.

[0112] Experimental steps: Sample preparation: The iron tailings waste samples were divided into two parts, used as a control group and an experimental group respectively.

[0113] Waste treatment: Control group: Use chemical precipitation equipment to treat iron tailings waste, and record the treatment time and the amount of harmful substances remaining.

[0114] Experimental group: Use supercritical water oxidation reactor to treat iron tailings waste, and record the treatment time and the amount of harmful substances remaining.

[0115] Data recording and analysis: Residual amount of harmful substances: Detect the residual amount of harmful substances after waste residue treatment and evaluate the environmental protection treatment effect.

[0116] Processing efficiency: record the processing time of each group of experiments and calculate the processing efficiency.

[0117] Table 4: Experimental summary: The experimental results show that the supercritical water oxidation technology is significantly superior to the traditional chemical precipitation method in terms of processing time and residual harmful substances, verifying the high efficiency and environmental protection of the supercritical water oxidation technology in the present invention.

[0118] Summary: By designing and implementing a number of comparative experiments, the remarkable advantages of the new process for extracting valuable elements from iron tailings of the present invention in terms of energy consumption, metal recovery rate, processing efficiency and environmental protection treatment effect have been verified from different angles such as selective microwave heating, plasma high-temperature decomposition and supercritical water oxidation, proving that the technical solution of the present invention is significantly more innovative and practical than the prior art.

[0119] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A new process for extracting valuable elements from iron tailings, characterized in that: The following steps are involved: S1. Secondary crushing and grinding of the iron tailings to prepare a slurry with a concentration of 30%-40%; S2, using a selective microwave heating device to perform microwave heating on the slurry; S3, introducing the microwave-heated slurry into a plasma reactor to decompose the mineral compounds in the tailings by high temperature plasma; S4, cooling the ore pulp after plasma decomposition and preparing it into a solution of appropriate concentration; S5, subjecting the modulated solution to electrochemical deposition to recover the metal; S6. The tailings waste after electrochemical deposition is subjected to supercritical water oxidation treatment.

2. A new process for extracting valuable elements from iron tailings according to claim 1, characterized in that: The particle size of the crushed product obtained by the primary crushing in step S1 is 10-50 mm, the particle size of the crushed product obtained by the secondary crushing in step S1 is 1-10 mm, and the particle size of the slurry obtained by grinding in step S1 is between 100-200 meshes.

3. The novel process for extracting valuable elements from iron tailings according to claim 1, characterized in that: The step S2 specifically includes the following steps: S2.

1. Preparation for microwave heating: Adjust the frequency of the microwave heating equipment to 0.915-2.45 GHz and the power to 1-10 kW to suit the dielectric properties of the mineral, and determine the microwave heating time to be 5-30 min and the heating temperature to be 50-200 °C; S2.2, Microwave Heating Process: The prepared slurry is continuously transported to the microwave heating equipment at a speed of 0.1-1m / s; S2.3, microwave heating post-treatment: The microwave heating time is controlled to be 5-30min, the slurry temperature is monitored at 50-200°C during discharge, and the particle size change is monitored to be 100-200 mesh.

4. A new process for extracting valuable elements from iron tailings according to claim 3, characterized in that: The dielectric properties in step S2.1 include dielectric constant, dielectric loss factor and conductivity.

5. The new process for extracting valuable elements from iron tailings according to claim 1, characterized in that: The plasma reaction atmosphere in step S3 is hydrogen or nitrogen.

6. The novel process for extracting valuable elements from iron tailings according to claim 1, characterized in that: The S4 step specifically includes the following steps: S4.

1. Cooling: Cooling the high-temperature slurry after the plasma reaction through a cooling device; S4.2, solution preparation: The cooled slurry is mixed with deionized water to prepare a solution with a concentration between 10% and 20%; S4.3, homogenization treatment: Use stirring equipment to homogenize the slurry solution.

7. A new process for extracting valuable elements from iron tailings according to claim 6, characterized in that: In the step S4.2, the cooled slurry is mixed with deionized water in a ratio of 1:4 to 1:

9.

8. The novel process for extracting valuable elements from iron tailings according to claim 1, characterized in that: The step S5 specifically includes the following steps: S5.

1. Preparation for electrochemical deposition: Configure an electrolytic cell, select titanium alloy as the electrode material, and prepare sulfuric acid or sodium chloride solution as the electrolyte; S5.2, Electrochemical reaction: Introduce the modulated solution into the electrolytic cell, adjust the voltage in the electrolytic cell to 1-5V and the current density to 50-200A / m²; S5.3, Metal Deposition: Carry out metal deposition reaction on the cathode and monitor the changes in pH and conductivity of the solution during the electrolysis process; S5.

4. Recycling of Metals: The metal deposits on the cathode are cleaned regularly, and the deposited metals are dried and purified.

9. The novel process for extracting valuable elements from iron tailings according to claim 1, characterized in that: The step S6 specifically includes the following steps: S6.

1. Preparation for waste residue treatment: The tailings waste residue after electrochemical deposition is subjected to solid-liquid separation, and the solid waste residue is collected and introduced into a supercritical water oxidation reactor; S6.2, Supercritical water oxidation reaction: Adjust the reactor temperature to above 374°C and the pressure to above 22.1MPa to treat the organic matter and difficult-to-treat substances in the waste residue under supercritical water conditions; S6.3, oxidation treatment: Select 90%-100% oxygen and adjust the flow rate of the oxidizing atmosphere between 10-50L / min, conduct online monitoring and sampling analysis, and completely oxidize the harmful substances in the waste residue during the supercritical water oxidation treatment process; S6.4, harmless treatment: The treated waste residue is subjected to solid-liquid separation and drying.

10. A new process for extracting valuable elements from iron tailings according to claim 9, characterized in that: The solid waste residue treated in step S6.4 is used as a resource for construction materials or roadbed materials.

Images