Energy-saving metal smelting and comprehensive recovery process

Abstract

The invention relates to an energy-saving metal smelting and comprehensive recovery process, which is particularly suitable for treating complex multi-component metal scraps and recovering rare and noble metals. According to the process, by introducing multi-temperature-zone control, dynamic separation and multi-stage waste heat recovery technologies, efficient separation and purification of metal materials under different temperature conditions are achieved. The method specifically comprises the process steps of preheating and dehydration, low-temperature reduction smelting, medium-temperature centrifugal separation, high-temperature vacuum distillation, precious metal extraction and refining, waste heat recovery, waste gas treatment and the like. Through precise control over the smelting process and full utilization of heat energy, the overall energy consumption is effectively reduced, the extraction efficiency of metal and precious metal is improved, and waste gas emission and environmental pollution are remarkably reduced. The process has remarkable advantages in the aspects of energy conservation, consumption reduction, resource recovery and environmental protection performance.

Description

Technical Field

[0001] The present invention relates to the field of metal smelting and resource recovery, and more specifically to an energy-saving metal smelting and comprehensive recovery process. Background Art

[0002] In traditional metal smelting processes, a large amount of energy is consumed in heating, melting and purifying metals, and energy waste and inadequate treatment of emissions often lead to low resource utilization and environmental pollution. In particular, when dealing with electronic waste containing rare or precious metals or multiple metals, traditional smelting processes face the following major challenges:

[0003] 1. High energy consumption: Electronic waste contains a variety of metals (such as copper, aluminum, gold, palladium, etc.), which have different melting points and boiling points. As a result, the smelting process requires long-term high-temperature heating, resulting in huge energy consumption;

[0004] 2. Difficulty in separating complex metal materials: Different types of metals are mixed in electronic waste, and they often contain non-metallic materials such as plastics and ceramics, making it difficult for traditional smelting processes to achieve effective separation and purification;

[0005] 3. Environmental pollution: If the large amount of waste gas, waste liquid and heavy metal vapor generated during the smelting process is not properly handled, it will cause serious harm to the environment. In the existing technology, the efficiency of the flue gas treatment system and waste heat recovery is generally low, making it difficult to effectively utilize the energy generated during the smelting process.

[0006] To solve the above problems, the present invention provides an energy-saving metal smelting and comprehensive recovery process, which realizes efficient purification and recovery of complex metal materials through multi-stage heating and dynamic energy consumption management technology, and significantly reduces the energy consumption in the smelting process by introducing a variety of energy-saving strategies. Summary of the invention

[0007] In order to solve the above problems, the present invention provides an energy-saving metal smelting and comprehensive recycling process. By introducing a multi-stage smelting and separation process, waste heat recovery technology and an intelligent energy management system, efficient separation and recovery of rare and precious metals and common metals in electronic waste can be achieved, while reducing energy consumption and harmful emissions in the smelting process.

[0008] To achieve the above object, the present invention provides the following technical solutions, which mainly include:

[0009] An energy-saving metal smelting and comprehensive recovery process comprises the following steps:

[0010] 1. Raw material pretreatment: electronic waste or complex metal mixtures are preliminarily sorted and sent to the low-temperature preheating area to remove moisture and volatile impurities in the range of 150-300°C, and preheated using the energy provided by the waste heat recovery device;

[0011] 2. Low temperature reduction: primary melting is carried out by vacuum smelting at low temperature of 400-600℃, and reducing agents are added to remove oxides and sulfides;

[0012] 3. Medium temperature separation: At a temperature of 600-900℃, the metal materials are separated according to density and magnetism through centrifugal separation devices, magnetic separation devices and electrolysis to achieve preliminary stratification of rare metals and common metals;

[0013] 4. High temperature purification: At a high temperature of 900-1200℃, the metal is further purified through a vacuum distillation process to remove residual impurities. The rare and precious metals are evaporated and recovered through a condensation device;

[0014] 5. Waste heat recovery: The waste gas and waste heat generated during the smelting process are recovered through the waste heat recovery device and used for preheating raw materials or supplying low-temperature smelting stage to achieve energy recycling;

[0015] 6. Metal extraction and cooling treatment: The purified metal melt is sent to the cooling zone for solidification and further purified by electrolysis or hydrometallurgical process to produce high-purity metal products.

[0016] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The energy-saving metal smelting and comprehensive recovery process of the present invention can effectively reduce the energy consumption in the smelting process through multi-stage heating and dynamic energy consumption management strategy.

[0018] (2) The use of vacuum smelting technology and multi-stage separation process achieves efficient separation of complex mixed metal materials and extraction of rare and precious metals with high recovery efficiency.

[0019] (3) By introducing a waste heat recovery system and a multi-stage flue gas treatment system, the energy waste and the emission of environmental pollutants during the smelting process are effectively reduced.

[0020] (4) Intelligent control of the overall process flow can dynamically adjust process parameters according to material characteristics and the actual situation of the smelting stage, thereby improving the stability and accuracy of smelting. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments 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.

[0024] Example 1

[0025] 1. Overview of process flow

[0026] The energy-saving metal smelting and comprehensive recovery process of the present invention mainly includes the following stages:

[0027] (1) Raw material pretreatment stage;

[0028] (2) Low temperature reduction smelting stage;

[0029] (3) Medium temperature separation stage;

[0030] (4) High temperature purification stage;

[0031] (5) Waste heat recovery and exhaust gas treatment;

[0032] (6) Metal cooling and purification;

[0033] (7) Data monitoring and optimization management;

[0034] Each stage is interconnected, and through the cooperation of dynamic temperature regulation, energy recovery and intelligent management system, efficient separation of complex materials and high-purity recovery of rare and precious metals can be achieved.

[0035] 2. Detailed description of implementation plan

[0036] 1. Raw material pretreatment stage

[0037] Mixed electronic waste or complex metal raw materials (such as mixtures of various metal materials such as copper, iron, gold, silver, palladium, etc.) first enter the raw material pretreatment area. The raw materials are initially crushed into particles with a diameter of less than 20 mm by a crushing device to ensure the uniformity of subsequent smelting and separation. Then, the granular raw materials enter the preheating zone, and the temperature is raised to 150-300℃ through the secondary heat source of the waste heat recovery system.

[0038] In this process, the moisture, volatile impurities and some organic matter in the electronic waste are evaporated and discharged. The preheating process uses the waste heat of the waste gas generated in the smelting process, which greatly reduces the external energy consumption. The preheated raw materials are sent to the low-temperature reduction smelting area through an automatic conveying system.

[0039] 2. Low temperature reduction smelting stage

[0040] The pretreated raw materials enter the low-temperature reduction smelting zone. In this stage, the temperature range is 400-600℃, and the smelting furnace is kept at 10 -2 Up to 10 -4 Pa low pressure vacuum environment to reduce the oxidation and sulfidation reaction temperature of the raw materials. At the same time, carbon powder or hydrogen is added as a reducing agent to reduce the oxides and sulfides in the raw materials to the corresponding metal elements.

[0041] During the reduction smelting process, the system uses real-time temperature monitoring and reduction gas concentration sensors to ensure the same reduction effect for each batch of raw materials. The reduced materials are automatically transferred to the medium temperature separation area through a sealed pipeline for the next step of processing.

[0042] 3. Medium temperature separation stage

[0043] The reduced metal materials enter the Medium-Temperature Separation Zone. Under the environment of 600-900℃, the system realizes the primary separation of metal materials through centrifugal separation and magnetic separation devices.

[0044] Centrifugal separation device: The material is fed into the centrifugal separator, and the centrifugal force of high-speed rotation separates metals of different densities into a multi-layer structure, in which heavier metals (such as gold and platinum) are concentrated in the outer layer, while lighter metals (such as aluminum and zinc) are located in the inner layer.

[0045] Magnetic separation device: The materials after centrifugal separation enter the magnetic separation device. Magnetic metals such as iron and nickel are attracted by magnetic force and separated into the magnetic separation box, while the remaining non-magnetic metals are discharged to the high-temperature purification area by gravity.

[0046] After medium-temperature separation, various metals have been preliminarily separated according to density and magnetism and enter the next stage of high-temperature purification.

[0047] 4. High temperature purification stage

[0048] The metal mixture separated by medium temperature is sent to the high-temperature refining zone. In a high temperature environment of 900-1200℃, high boiling point metals (such as gold, silver, palladium) and low boiling point metals (such as aluminum, zinc) are evaporated and separated by vacuum distillation technology.

[0049] Vacuum distillation device: By evaporating rare metals under high temperature and low pressure environment, the rare metal vapor is captured by the condensation device and converted into liquid or solid.

[0050] Temperature control of the condensation device: The condensation temperature is controlled at 100-300℃ to ensure that the rare and precious metals can be completely solidified. The high-temperature purification stage can effectively remove the residual impurities in the metal mixture and obtain high-purity metal elements.

[0051] 5. Waste heat recovery and exhaust gas treatment

[0052] The high-temperature waste gas generated during the smelting and purification process is introduced into the waste heat recovery system (Waste Heat Recovery System), which transfers the heat in the waste gas to the preheating area and low-temperature reduction area through a heat exchange device to achieve energy recycling.

[0053] At the same time, the exhaust gas after waste heat recovery is deeply purified through a multi-stage flue gas treatment system (including electrostatic dust removal, desulfurization and carbon dioxide absorption devices) to ensure that the exhaust gas meets environmental protection standards. By recovering energy from the exhaust gas, the energy utilization efficiency of the overall process has been increased by more than 30%.

[0054] 6.Metal cooling and purification

[0055] The metal liquid discharged from the high-temperature purification area enters the cooling zone, where it is solidified into metal blocks through staged cooling. The cooled metal material is further purified by electrolysis or hydrometallurgy to remove trace impurities and generate high-purity metal products.

[0056] 7.Data monitoring and optimization management

[0057] The present invention introduces an intelligent control and data management system, which dynamically adjusts abnormal conditions by real-time monitoring of the temperature, pressure and energy consumption of each smelting step. The data management system can optimize process parameters based on historical data and realize intelligent management and control of the entire process.

[0058] Temperature and pressure monitoring: Each smelting area is equipped with multi-point temperature sensors and pressure monitoring devices to ensure stable operation of each processing unit.

[0059] Energy consumption management system: Through real-time monitoring and feedback of energy consumption data, the system can automatically adjust working parameters when energy efficiency is low, such as adjusting preheating temperature, optimizing smelting time, etc., so as to achieve optimal energy utilization.

[0060] Model self-learning and optimization: The data management system can automatically generate new process optimization solutions through analysis of historical data and real-time monitoring data, ensuring that the system can be dynamically adjusted when processing different types of raw materials and achieve adaptive optimization of the process.

[0061] In summary, the energy-saving metal smelting and comprehensive recovery process of the present invention can effectively reduce the energy consumption of high-temperature heating during the smelting process, with a high waste heat recovery rate and a rare metal recovery rate of more than 98%. Through intelligent control and dynamic management, the overall energy consumption is reduced by 40% compared with the traditional process, and efficient and low-pollution smelting and recovery are achieved.

[0062] Example 2: Comprehensive recycling of complex electronic waste

[0063] 1. Raw material pretreatment and classification

[0064] The recycled waste electronic waste (including waste circuit boards, integrated circuit chips and other electronic components containing precious metals) is crushed into a 5-20 mm granular mixture by a crusher and initially classified using a screening device. Metal powders with smaller particle sizes (such as solder and metal chips) go directly into the preheating area; larger mixtures (such as integrated circuit boards) enter the secondary crushing process until the particle sizes of all materials are uniform.

[0065] 2. Preheating and dehydration

[0066] The crushed mixed granular material is sent to the preheating zone (temperature 150-300℃) through a conveyor belt. The preheating zone uses the waste gas heat energy from the smelting process to heat the material through a waste heat recovery device. This stage mainly removes moisture, volatile organic matter and other low-boiling impurities in the material.

[0067] The preheating temperature is set at 200°C, and a layer of calcium oxide (CaO) powder is coated on the surface of the material to absorb chlorides and other impurities in the material to reduce corrosive gas emissions in the subsequent smelting process.

[0068] 3. Low temperature reduction smelting

[0069] The preheated pellets are fed into a low-temperature reduction smelting furnace. The temperature inside the smelting furnace is maintained at 10 -2 Up to 10 -4Pa low pressure environment, and the temperature is controlled at 450 ° C. During the smelting process, carbon powder (accounting for 5% of the total material) is added to the furnace as a reducing agent, and a small amount of hydrogen (0.1-0.3 mol / m 3 ). The reduction reaction can effectively remove oxides and sulfides in the material and reduce precious metals (such as gold and palladium) in the waste to metal elements.

[0070] The reaction lasts for 30 minutes, and the reaction status is monitored in real time by infrared temperature sensors and hydrogen concentration sensors inside the smelting furnace. When the oxide content is detected to drop below 0.1%, the system automatically stops heating and discharges the reduced material to the medium-temperature separation zone.

[0071] 4. Medium temperature centrifugal separation and magnetic separation

[0072] The metal mixture after low-temperature reduction is sent to a medium-temperature centrifugal separation device (temperature controlled at 650°C), where the centrifugal force separates metals of different densities into different levels of structure. The separated materials are mainly divided into two layers:

[0073] Outer layer: heavier rare and precious metals (such as gold, silver, and palladium).

[0074] Inner layer: common metal (such as copper, aluminum, iron).

[0075] Afterwards, the material enters the magnetic separation device, where the magnetic force separates the inner layer of magnetic metals such as iron and nickel from the non-magnetic metals. The iron and nickel materials after magnetic separation are automatically discharged into the ferromagnetic metal recovery box; while the rare and precious metal mixture (outer layer) is conveyed to the high-temperature purification area.

[0076] 5. High temperature vacuum distillation and extraction of rare and precious metals

[0077] In the high-temperature purification area, the rare metal mixture is heated to 1000°C and distilled at high temperature in a vacuum environment of 0.01Pa. During this process:

[0078] Low boiling point metals (such as aluminum and zinc) are first evaporated at a lower temperature and recovered through a condensation system.

[0079] As the temperature rises further, rare and precious metals (such as gold, silver, and palladium) gradually evaporate and are captured by the condenser, condensing into liquid or solid high-purity metals.

[0080] The high-temperature distillation process uses a multi-stage temperature control system to accurately adjust the evaporation rate and condensation temperature to ensure that each metal can be separated under optimal conditions. The residue after distillation is automatically discharged into the residue recovery box through a mechanical discharge device for harmless waste treatment.

[0081] 6. Waste heat recovery and exhaust gas treatment

[0082] The waste gas generated during high-temperature smelting and distillation is introduced into the waste heat recovery device, and the heat of the high-temperature waste gas is transferred to the preheating area and the low-temperature reduction smelting area through a multi-stage heat exchanger to maintain the temperature balance of other areas, thereby realizing the recycling of energy. The waste gas after waste heat recovery is sent to the multi-stage waste gas treatment system and purified in the following steps:

[0083] Electrostatic precipitator: removes fine particles from the gas.

[0084] Desulfurization device: Use sodium hydroxide (NaOH) solution to absorb SO2 in the exhaust gas to generate harmless sodium sulfate (Na2SO4) solution.

[0085] Carbon dioxide absorption: Amine solution is used to capture CO2 in exhaust gas to reduce greenhouse gas emissions.

[0086] The treated purified gas meets the national environmental emission standards and is safely discharged through the exhaust pipe.

[0087] 7.Metal cooling and electrolytic purification

[0088] The metal liquid extracted from the high-temperature purification area is gradually cooled to room temperature through a staged cooling system. The cooled metal element (such as gold and silver) is sent to the electrolytic purification device to remove trace impurities through electrolysis, and finally generate a metal product with a purity higher than 99.99%.

[0089] During the electrolysis process, the system monitors the electrolyte concentration, temperature and current density in real time. When the metal purity reaches the set value, the system automatically stops electrolysis and transfers the purified metal to the finished product storage area.

[0090] 8. Intelligent control and data analysis

[0091] The entire smelting and recycling process is managed in real time through an intelligent control system. The temperature, pressure, material flow rate and energy consumption data of each processing area are collected centrally, processed and fed back through the data analysis module. The system can automatically adjust the parameters of each area based on real-time data, such as adjusting the vacuum degree, changing the heating power or adjusting the separation time, thereby achieving dynamic optimization of the process.

[0092] Energy efficiency analysis and optimization: The data management system can analyze the energy efficiency of each step in the smelting process and generate energy efficiency optimization plans when the energy efficiency is below the threshold.

[0093] Model self-learning and parameter updating: The system can continuously adjust process parameters and model strategies through the accumulation of historical data and actual operation results, thereby achieving adaptive optimization when different raw material ratios or new materials appear.

[0094] Implementation Effect

[0095] Through the verification of the above examples, the energy-saving metal smelting and comprehensive recycling process of the present invention can achieve efficient resource recovery in complex electronic waste treatment. Experiments show (as shown in Table 1) that the total recovery rate of rare and precious metals (such as gold, silver, and palladium) reaches 99.5%, energy consumption is reduced by more than 40% compared with traditional smelting processes, and waste gas emissions are reduced by 70%, which significantly improves resource utilization efficiency and reduces environmental pollution. The process is suitable for large-scale industrial production and has good economic and environmental benefits.

[0096]

[0097] Table 1

[0098] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0099] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An energy-saving metal smelting and comprehensive recovery process, comprising multi-stage heating, smelting, separation and recovery steps, characterized in that: The process comprises the following steps: 1) Raw material pretreatment: Electronic waste or complex metal mixtures are preliminarily sorted and sent to the low-temperature preheating area for pretreatment to remove moisture and volatile impurities in the temperature range of 150-300°C; 2) Low-temperature reduction: The preheated raw materials are sent to the low-temperature reduction stage, where primary melting is performed through vacuum smelting at a temperature of 400-600°C, and a reducing agent is added to remove oxides and sulfides; 3) Medium temperature separation: Medium temperature separation is carried out at a temperature of 600-900°C, and the metal materials are separated by density and magnetism using a centrifugal separation device, a magnetic separation device and an electrolytic method; 4) High temperature purification: At a high temperature of 900-1200°C, the metal is further purified through a vacuum distillation process to remove residual impurities. The rare and precious metals are evaporated and recovered through a condensation device; 5) Waste heat recovery: The waste gas and waste heat generated during the smelting process are recovered through the waste heat recovery device and used to preheat the raw materials or supply the low-temperature smelting stage; 6) Metal extraction and cooling treatment: The purified metal melt is sent to the cooling zone for solidification and further purified through electrolysis or hydrometallurgical processes to produce high-purity metal products.

2. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: In the raw material pretreatment step, the heat provided by the waste heat recovery device is used for preheating treatment, the temperature of the preheating zone is controlled at 150-300°C, and the preheating temperature is adjusted in real time by an intelligent temperature control system to reduce the energy consumption of the external heat source.

3. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: The low-temperature reduction step is carried out in a vacuum environment. By controlling the pressure in the furnace within the range of 10-2Pa to 10-4Pa, the melting point and boiling point of the metal are lowered, thereby achieving melting and preliminary separation of the material under low-temperature conditions, and removing oxides and sulfides by adding carbon powder or hydrogen as a reducing agent.

4. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: In the medium temperature separation step, a high-speed rotating centrifugal separation device is used to separate the metal materials into layers according to density differences, and the iron-containing materials are separated by a magnetic separation device. The rotation speed range of the centrifugal separation device is 1000-3000 rpm.

5. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: The high-temperature purification step uses a vacuum distillation process to evaporate precious metals (such as gold, silver, and palladium) from the melt by gradually increasing the temperature, and efficiently collects them through a condensation tower, wherein the vacuum distillation temperature is controlled at 900-1200°C and the condensation tower temperature is maintained between 100-300°C.

6. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: In the waste heat recovery step, the high-temperature waste gas generated by smelting is converted into energy through a waste heat exchanger and used for raw material preheating or heating in the low-temperature reduction stage. The waste heat recovery rate is not less than 70%.

7. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: In the metal extraction and cooling treatment steps, the temperature of the melt is reduced to 100-300° C. by using a temperature control system in the cooling zone, and the metal melt is transported to an electrolysis device or a hydrometallurgical device for secondary purification by an automatic transport system.

8. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: The process also includes introducing a dynamic energy management system in the low-temperature reduction and medium-temperature separation stages to intelligently control the heating power and energy distribution of the smelting equipment, and adjust energy consumption parameters according to the material status and the needs of the smelting stage to reduce unnecessary energy consumption.

9. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: The smelting process also includes a multi-stage flue gas treatment step, using an electrostatic precipitator, a desulfurization device and a carbon dioxide absorption device to sequentially treat harmful waste gas generated during the smelting process, and the purified waste gas meets environmental emission standards.

10. The energy-saving metal smelting and comprehensive recovery process according to claim 1 is characterized in that: The process adopts an intelligent smelting control system, which monitors the temperature, pressure, material status and energy consumption of the smelting process in real time through Internet of Things sensors and big data analysis platforms, and automatically adjusts the heating power, the amount of reactants added and the emission parameters to achieve precise energy-saving control and optimization of the smelting process.

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