A method, system, activated carbon and application for preparing lignin biomass activated carbon by using high-salt metallurgical wastewater

Abstract

This invention discloses a method, system, activated carbon, and application for preparing wood-based biomass activated carbon from high-salt metallurgical wastewater. The method includes: washing, crushing, and microwave pre-carbonizing wood-based cellulose biomass; purifying the pre-carbonized material with hot water and then heating it under an inert atmosphere to form a high-temperature activation zone; pre-treating the high-salt metallurgical wastewater and atomizing it into salt-containing micron-sized droplets, which are then introduced into the high-temperature activation zone for synergistic activation; in-situ vaporization of water in the atomized droplets participates in steam activation, and the salt components are deposited and crystallized to form a salt template for water washing and pore formation; after activation, the activated carbon is obtained through inert purging, oxygen-free cooling, water washing for desalination, and drying. The system is equipped with heated conveying, online flushing, and backup nozzles to ensure continuous and stable operation. This invention couples the resource utilization of high-salt wastewater with activated carbon preparation, eliminating the need for external chemical activators. The activated carbon can be used for deep adsorption and removal of organic pollutants and metallurgical additive residues from high-salt metallurgical wastewater.

Description

Technical Field

[0001] This invention belongs to the technical fields of metallurgical wastewater resource utilization, biomass porous carbon material preparation and industrial wastewater deep treatment, specifically involving a method, system, activated carbon and application for preparing wood-based biomass activated carbon using high-salt metallurgical wastewater. Background Technology

[0002] Hydrometallurgical processes (such as leaching, extraction, back-extraction, washing, electrolysis, metal refining, and pickling) generate large amounts of industrial wastewater containing high concentrations of soluble inorganic salts. This type of high-salinity metallurgical wastewater not only contains chlorides, sulfates, nitrates, and metal ions such as sodium, potassium, calcium, magnesium, iron, zinc, copper, and nickel, but also often contains oils, extractants, flotation reagents, surfactants, complexing agents, and other recalcitrant organic matter. It is characterized by high salinity, high hardness, strong corrosivity, and the coexistence of organic pollutants. Currently, the treatment of this type of wastewater usually faces technical bottlenecks such as biochemical inhibition, membrane fouling, evaporative scaling, and difficulties in the disposal of concentrated solutions.

[0003] Currently, the existing technologies for preparing activated carbon from lignocellulosic biomass are mainly divided into physical activation and chemical activation. Physical activation typically uses external steam or carbon dioxide for high-temperature activation, resulting in a relatively simple media function and difficulty in utilizing the complex salt systems in wastewater. Chemical activation generally uses external chemical agents such as potassium hydroxide, phosphoric acid, or zinc chloride to create pores. Although this can achieve a high specific surface area, it requires the introduction of large amounts of chemical agents, increasing the burden of equipment corrosion, washing, and agent recovery. In addition, in conventional wastewater evaporation-demisting processes, most of the non-volatile salt components in high-salt wastewater are retained in the concentrate or crystalline salt. The gas phase entering the activation equipment is mainly water vapor, and the wastewater source salt components cannot effectively enter the interior of the carbon material and utilize their space occupation, crystallization, local melting, or catalytic effects to finely control the pore structure. If untreated high-salt metallurgical wastewater is directly sprayed into a high-temperature reactor, it is very easy to cause nozzle salt precipitation blockage, local temperature drop, carbon material burn-out, salt mist entrainment, and exhaust gas pollution, which will seriously affect the stability and safety of continuous operation.

[0004] To address the shortcomings of existing technologies, there is an urgent need to develop a highly efficient resource utilization and activated carbon preparation scheme that can use the moisture and complex salt components in high-salt metallurgical wastewater as a composite activation medium, directly introduce micron-sized droplets into a high-temperature activation zone in a controlled manner, and simultaneously provide complete anti-clogging, oxygen-barrier cooling, and exhaust gas purification measures, so as to achieve the goal of treating waste with waste and recycling wastewater resources. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method, system, activated carbon, and application for preparing wood-based biomass activated carbon using high-salt metallurgical wastewater.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This application provides a method for preparing wood-based biomass activated carbon using high-salt metallurgical wastewater, comprising the following steps: Lignocellulose biomass is pretreated to obtain biomass pellets; The biomass pellets are pre-carbonized under an inert atmosphere to obtain pre-carbonized feed. The pre-carbonized material is purified to remove soluble impurities and tar. The purified pre-carbonized material is heated to a high-temperature activation zone under an inert atmosphere; High-salt metallurgical wastewater is pretreated and then atomized into droplets containing dissolved salts. The droplets are then allowed to directly enter the high-temperature activation zone and come into contact with the pre-carbonized material. The water in the droplets is vaporized in situ and participates in steam activation. The salt components in the droplets form a water-washable salt template on the surface and / or pores of the pre-carbonized material, which works together to activate and create pores. Stop feeding high-salt metallurgical wastewater and cool the activated products in an oxygen-free atmosphere. The activated product after cooling is washed with water to desalinate, separate and dry to obtain wood biomass activated carbon.

[0007] Preferably, the lignocellulose biomass is selected from at least one of wood processing waste, bamboo processing waste, or waste wood products; the particle size of the biomass particles satisfies the median particle size D50 ≤ 200 mesh.

[0008] Preferably, the pre-carbonization treatment is performed using microwave heating, with a pre-carbonization temperature of 350~650℃ and a pre-carbonization time of 8~60min; the purification treatment is performed by hot water washing, with a hot water washing temperature of 60~95℃, a washing time of 1~4h, a liquid-solid mass ratio of 50:1~100:1, a drying temperature of 95~120℃, and a drying time of 2~8h.

[0009] Preferably, the high-salt metallurgical wastewater originates from leaching, extraction, back-extraction, washing, electrolysis, or flue gas purification processes in hydrometallurgical processes. The total dissolved solids content of the high-salt metallurgical wastewater is 30–250 g / L, and it contains chlorides, sulfates, nitrates, and at least one metal salt selected from sodium, potassium, calcium, magnesium, iron, zinc, copper, nickel, and manganese.

[0010] Preferably, the pretreatment of the high-salt metallurgical wastewater before atomization includes at least one of the following: oil removal treatment, pH adjustment, hardness adjustment, and fine filtration to remove volatile components or suspended solids.

[0011] Preferably, the median volumetric particle size of the atomized droplets is 5-150 μm, the atomization feed rate of the high-salt metallurgical wastewater is 0.1-2.0 mL / (min·100g pre-carbonized material), the temperature of the high-temperature activation zone is 750-950℃, and the activation time is 10-90 min; the salt components form the elutable salt template through deposition, crystallization, melting, or catalytic steam reaction.

[0012] Preferably, the cooling is performed under continuous inert atmosphere protection to an oxygen-free temperature not exceeding 150°C; the water washing and desalination is performed by washing multiple times with a detergent at 20~95°C until the salt content in the liquid phase after washing reaches a preset endpoint.

[0013] A co-activation system for implementing the above method includes: The pre-carbonization unit, the pre-carbonized material post-processing unit, the activation reactor, the inert atmosphere supply unit, the wastewater storage and pre-treatment unit, the metering and conveying unit, the atomizing device, the oxygen-free cooling unit, the water washing and desalination unit, and the tail gas treatment unit. The atomizing device is located upstream or inside the high-temperature treatment zone of the activation reactor, and a heat tracing structure is provided between the atomizing device and the metering and conveying unit. The atomizing device is also equipped with an online rinsing component and a spare nozzle.

[0014] A wood-based biomass activated carbon, prepared by the above method, wherein the wood-based biomass activated carbon has a multi-level porous structure formed by the synergistic effect of in-situ steam activation and a wastewater source washable desalination template.

[0015] The application of wood-based biomass activated carbon in the deep treatment of high-salt metallurgical wastewater, wherein the wood-based biomass activated carbon is used to adsorb and remove organic pollutants, color, oils, extractants or flotation reagents from the high-salt metallurgical wastewater. After the wood-based biomass activated carbon is saturated with adsorption, it is reused after being washed with hot water or thermally regenerated, and the waste liquid generated during the regeneration process is returned to the pretreatment process of the high-salt metallurgical wastewater.

[0016] Compared with the prior art, this application has the following beneficial effects: This invention proposes a method, system, activated carbon, and application for preparing wood-based biomass activated carbon from high-salt metallurgical wastewater. It overcomes the shortcomings of traditional physical activation media with their limited functionality and chemical activation media with their heavy chemical burden. By directly introducing high-salt metallurgical wastewater as micron-sized atomized droplets containing dissolved salts into a high-temperature activation zone, the wastewater is cleverly transformed from a simple object to be treated into a source of composite activation media. This achieves the synergistic effect of in-situ steam activation and pore-forming using wastewater-source salt templates. This method not only allows the water in the wastewater to vaporize in situ and participate in the steam activation reaction, but also causes the salt components to deposit, crystallize, partially melt, or catalyze on the surface and pores of the pre-carbonized material, forming salts that can be washed away with water. This method utilizes templates to precisely control the micropore and mesopore structures through spatial occupancy and heat transfer regulation, thereby preparing multi-level porous woody biomass activated carbon with high adsorption performance without the need for external chemical activators. This significantly reduces the consumption of chemical reagents and wastewater treatment costs. Simultaneously, this method systematically solves engineering challenges such as equipment clogging, localized temperature drops, carbon material burn-out, and secondary pollution caused by high-salt atomized droplets through oxygen-free cooling, online heated conveying, backup nozzles, and multi-stage exhaust gas purification. It achieves a complete closed loop from the resource utilization of high-salt wastewater to the functional preparation of biomass carbon and then to deep adsorption applications, providing a new technological path for low-energy, high-efficiency, and green treatment of metallurgical wastewater. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the co-activation of wood-based biochar by atomized droplets of salt template in high-salt metallurgical wastewater according to the present invention.

[0018] Figure 2 This is a schematic diagram of the structure of the high-salt metallurgical wastewater atomized droplet salt template synergistic activation system of the present invention.

[0019] Figure 3 This is a schematic diagram illustrating the mechanism of in-situ vaporization of salt-containing atomized droplets and synergistic hole formation using wastewater source salt templates in this invention.

[0020] Figure 4 This is a schematic diagram of the structure for atomizing and conveying high-salt metallurgical wastewater and preventing crystallization and clogging according to the present invention.

[0021] Figure 5 This is a flowchart illustrating the application of wood-based biomass activated carbon in the deep treatment of high-salt metallurgical wastewater according to the present invention.

[0022] The components include: 1. Nitrogen source; 2. Pressure reduction and flow regulation unit; 3. High-salt metallurgical wastewater storage tank; 4. Filtration and homogenization unit; 5. Metering pump; 6. Heated conveying pipe; 7. Atomizing nozzle; 8. Tubular activation furnace; 9. Reaction tube; 10. Carbon boat; 11. Condenser; 12. Tail gas scrubbing unit; 13. Recovery or emission end; 14. Oxygen-free cooling unit; 15. Water washing, desalination and drying unit; 16. Finished activated carbon; 17. Microwave pre-carbonization unit; 18. Online flushing interface; 19. Spare nozzle. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Furthermore, in this invention, an element referred to as fixed to or disposed on another element may be directly disposed on the other element, or there may be an intermediate element. When an element is considered to be connected to another element, it may be directly connected to the other element, or there may be an intermediate element present simultaneously. The terms vertical, horizontal, left, right, and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0025] I. Terminology and Process Boundaries In order to more clearly define the technical solutions protected by this invention, and to clarify the application scenarios and technical effects of this invention, the core terms involved in this invention are first defined.

[0026] The high-salt metallurgical wastewater described in this invention refers to industrial wastewater originating from metallurgical production and its auxiliary processes, with a total dissolved solids content of not less than 30 g / L. Its sources include, but are not limited to, hydrometallurgical leaching, extraction, back-extraction, washing, electrolysis, metal refining, pickling, metallurgical flue gas purification, or metallurgical equipment circulating sewage discharge processes. This wastewater typically contains inorganic salts such as chlorides, sulfates, and nitrates, as well as metal ions such as sodium, potassium, calcium, magnesium, iron, zinc, copper, nickel, and manganese.

[0027] The direct atomization described in this invention refers to directly spraying micron-sized salt-containing droplets formed from high-salt metallurgical wastewater into the high-temperature carbon material activation zone from the outlet of the atomization device. In this process, the salt-containing droplets do not pass through a demister or gas-liquid separator for salt mist separation, so as to ensure that the dissolved salt can enter the surface and pores of the high-temperature carbon material in liquid form along with the droplets.

[0028] The salt template mentioned in this invention refers to the inorganic phase that can be dissolved and removed during subsequent water washing. Soluble inorganic salt components in high-salt metallurgical wastewater enter the high-temperature carbon material activation zone with droplets, and then deposit, crystallize or partially melt on the surface and pores of the carbon material. The pore structure is regulated by spatial occupation, local heat transfer regulation or catalytic carbon-water vapor reaction.

[0029] It should be specifically pointed out that the main technical effect of the wood-based biomass activated carbon prepared by this invention is to deeply adsorb residual organic pollutants, color, oils, extractants, flotation reagents, surfactants, complexing agents and their degradation products in high-salt metallurgical wastewater, rather than to adsorb and remove the main soluble inorganic salts in high-salt wastewater as its main function.

[0030] II. Detailed Steps of the Specific Implementation Method This invention provides a method for the synergistic activation of lignocellulosic biochar by atomized droplets and salt templates in high-salt metallurgical wastewater, comprising the following specific implementation steps: Step S1: Pre-treat the lignocellulose biomass to obtain biomass pellets; pre-carbonize the biomass pellets under an inert atmosphere to obtain pre-carbonized material.

[0031] First, select one or more of the following lignocellulosic biomass as raw materials: wood processing scraps, wood chips, shavings, branches, waste wood products, bamboo waste, etc.; clean the biomass to remove mud, sand, metal and plastic impurities, and pre-dry it at 60°C to a moisture content of no more than 12% by weight.

[0032] The dried raw materials are crushed and sieved to meet the requirement that the median particle size D50 does not exceed 200 mesh, that is, the particle size does not exceed 75μm, and the mass ratio of such particles reaches 80% to 90%. Controlling the fine particle size helps to uniformly absorb heat in the subsequent microwave field, promotes the rapid removal of volatiles, and forms a uniform initial carbon skeleton.

[0033] The sieved biomass pellets are placed in an inert atmosphere microwave reactor, and nitrogen or argon gas is introduced at a flow rate of 0.2 to 2.0 L / min to replace the air. The microwave power is set to 400 to 1500 W, more preferably 600 to 1200 W, to heat the material to 350 to 650°C, more preferably 420 to 560°C, and held at that temperature for 8 to 60 minutes, more preferably 15 to 30 minutes, to obtain pre-carbonized material.

[0034] Step S2: Purify the pre-carbonized material to remove soluble impurities and tar.

[0035] To eliminate the obscuring effect of residual tar and soluble ash from the pre-carbonization process on the subsequent pore structure, the pre-carbonized material is purified by hot water washing. Specifically, the pre-carbonized material is immersed in hot water at 60-95°C for mechanical stirring and washing, with a more preferred washing temperature of 75-85°C and a washing time of 1-4 hours, more preferably 2-3 hours, and the liquid-solid mass ratio is controlled at 50:1-100:1. After washing, solid-liquid separation is performed, and the solid product is placed in an oven at 95-120°C and dried for 2-8 hours to obtain the purified pre-carbonized material.

[0036] Step S3: The purified pre-carbonized material is heated to the high-temperature activation zone under an inert atmosphere; the high-salt metallurgical wastewater is pretreated, and the pretreated high-salt metallurgical wastewater is atomized into droplets containing dissolved salts.

[0037] High-salt metallurgical wastewater with a total dissolved solids content of 30–250 g / L, more preferably 80–150 g / L, is obtained. To ensure the stability of the atomization delivery process and avoid equipment clogging, the wastewater needs to be pretreated before atomization. The pretreatment includes one or more of the following methods: firstly, removing large particulate suspended solids by sedimentation or fine filtration; if the wastewater contains an oil phase or extractant, performing oil separation, flotation, or adsorption treatment; if the wastewater contains metal ions such as iron, zinc, copper, nickel, and manganese that easily form hydroxide precipitates, performing complexation state adjustment or selective impurity removal pretreatment; if the wastewater contains volatile harmful components, performing directional stripping.

[0038] The treated wastewater is fed into an atomizing device via a metering pump and a heated delivery pipe. The temperature of the heated delivery pipe is controlled within a range that inhibits salt precipitation and crystallization without causing excessive local evaporation and concentration. The atomizing device can employ at least one of a dual-fluid nozzle, a pressure nozzle, an ultrasonic atomizer, or a rotary atomizer to atomize the wastewater into salt-containing micron-sized droplets with a median volumetric diameter (D50) of 5–150 μm, more preferably with a D50 of 15–50 μm. The distance between the atomizing device outlet and the surface of the charcoal is set to 20–300 mm, and the angle between the atomization direction and the normal to the charcoal surface is set to 0–90° to ensure effective wetting and coverage of the high-temperature charcoal by the salt-containing droplets.

[0039] Step S4: The droplets directly enter the high-temperature activation zone and come into contact with the pre-carbonized material. The water in the droplets vaporizes in situ and participates in water vapor activation. The salt components in the droplets form a water-washable salt template on the surface and / or pores of the pre-carbonized material, which works together to activate and create pores.

[0040] Under an inert atmosphere, the purified pre-carbonized material obtained in step S2 is heated to 750~950℃, more preferably 800~900℃, to form a high-temperature carbon material activation zone; the salt-containing atomized droplets formed in step S3 are directly introduced into the high-temperature activation zone at a feed rate of 0.1~2.0mL / (min·100g pre-carbonized material), more preferably 0.45~0.80mL / (min·100g pre-carbonized material), for a synergistic activation reaction of 10~90min, more preferably 20~60min.

[0041] In the synergistic activation process, in-situ steam activation and wastewater source salt template pore formation are coupled: on the one hand, after the atomized droplets come into contact with the high-temperature carbon material, the water vaporizes rapidly in situ, and the generated steam immediately reacts with the carbon skeleton in a carbon-water vapor gasification reaction, the reaction equation being C+H2O→CO+H2. This reaction opens up the closed micropores inside the carbon material; on the other hand, the salt components in the wastewater penetrate into the carbon material surface and pores with the droplets, and undergo deposition, crystallization or local melting at high temperatures. By controlling the excessive burning of the pores through space occupation, and by adjusting the local heat transfer gradient, the temperature field of the gasification reaction interface is affected. At the same time, the alkali metal or transition metal cations contained in the salt can catalyze the carbon-water vapor reaction, thereby synergistically promoting the formation of micropores and mesopores / macropores in a single reaction step.

[0042] Step S5: Stop feeding high-salt metallurgical wastewater and cool the activated product under an inert atmosphere; wash the cooled activated product with water to desalinate, separate and dry it to obtain wood biomass activated carbon.

[0043] After the activation reaction is completed, stop feeding high-salt metallurgical wastewater and purge the reactor with inert gas for 5 to 30 minutes to remove residual water vapor and volatile components. Then, under continuous inert gas protection or closed conditions, cool the activated product to no higher than 150°C, more preferably to no higher than 120°C, to avoid oxidation and burn-off of high-temperature carbon materials.

[0044] The cooled activated product is washed multiple times in clean water at 20~95℃, more preferably at 75~85℃, and the number of washes is 1~5 times, more preferably 1~3 times. The washing endpoint is determined when the conductivity, chloride ion concentration, sulfate concentration or target metal ion concentration of the final wash solution reaches the set desalination endpoint threshold. During this process, the soluble salt template deposited in the pores is dissolved and washed away by water, releasing the occupied pore space, and wood biomass activated carbon with a multi-level pore structure is obtained.

[0045] III. Structure and Implementation Method of the Collaborative Activation System To ensure the stable and continuous execution of the above method, this invention also provides a high-salt metallurgical wastewater atomized droplet salt template synergistic activation system, the specific structure and operation of which are as follows: Combination Figure 2 and Figure 4 The system includes a microwave pre-carbonization unit 17, an activation reactor, an inert gas supply and flow regulation unit, a high-salt metallurgical wastewater storage tank 3, a filtration and homogenization unit 4, a metering pump 5, a heated conveying pipe 6, an atomizing nozzle 7, an oxygen-free cooling unit 14, a water washing, desalination and drying unit 15, and a tail gas treatment unit; the activation reactor is a tubular activation furnace 8, which is equipped with a reaction tube 9 and a carbon boat 10; the inert gas supply and flow regulation unit consists of a nitrogen source 1 and a pressure reduction and flow regulation unit 2; the atomizing nozzle 7 is located upstream, inside or adjacent to the high-temperature carbon zone of the tubular activation furnace 8.

[0046] A solution to prevent clogging caused by crystallization in high-salt wastewater is provided: Temperature, pressure, and flow detection elements are installed on the heated delivery pipe 6 between the metering pump 5 and the atomizing nozzle 7; the atomizing nozzle 7 is equipped with a parallel backup nozzle 19 and an online flushing interface 18; the system incorporates automatic interlocking control logic: when the pressure detection element in the pipeline reports an abnormally high pressure difference, or the flow detection element reports a value below a set lower limit, it is determined that salt precipitation clogging has occurred in the pipeline or nozzle; the interlocking controller automatically stops the wastewater feed and injects high-temperature flushing liquid or high-pressure inert gas into the heated delivery pipe 6 and the main working nozzle through the online flushing interface 18 for online flushing; simultaneously, the switching valve automatically switches the wastewater feed path to the backup nozzle 19, achieving uninterrupted continuous atomized feed.

[0047] For safe and environmentally friendly exhaust gas control and safety interlocking: the activation reactor is equipped with an oxygen content detection element and an over-temperature interlock device to prevent activated carbon burnout or over-temperature accidents caused by excessive oxygen content; the exhaust gas generated by the activation reaction undergoes multi-stage purification through a condenser 11, a gas-liquid separator, and an exhaust gas scrubbing unit 12, and the purified gas is output from the recovery or emission end 13. The condensate and scrubbing liquid can be returned to the high-salt metallurgical wastewater pretreatment unit. If the wastewater contains volatile heavy metals such as mercury, arsenic, and selenium, targeted removal can be carried out before atomization or a heavy metal capture module can be added at the exhaust gas end. IV. Specific Implementation Examples To further illustrate the technical solution and effects of the present invention, detailed descriptions are provided below through specific embodiments. These embodiments are for illustrative purposes only and should not be considered as limiting the scope of the present invention.

[0049] Example 1: Intermittent Salt Template Synergistic Activation via Dual-Fluid Nozzle Take camphor wood processing scraps, remove metal, plastic and mud, wash twice with clean water, and pre-dry at 60℃ until the moisture content is no more than 12%; crush and sieve the dried raw material so that the mass ratio of particles with a particle size of no more than 75μm reaches 85%, and weigh 100g.

[0050] The weighed material was placed in a microwave reactor, nitrogen gas was introduced at a flow rate of 0.8 L / min, the microwave power was set to 800 W, the temperature was raised to 460 °C, and the temperature was maintained for 18 min to obtain the pre-carbonized material.

[0051] The pre-carbonized material was added to hot water at 80℃, and the liquid-solid mass ratio was controlled at 12:1. It was stirred and washed at 600r / min for 2.5h, filtered, and then dried at 105℃ for 4h.

[0052] High-salt wastewater generated from the wet metallurgical washing process is treated by sedimentation, fine filtration, and homogenization to adjust the total dissolved solids content to 80-120 g / L, and oil separation and pH adjustment are also completed.

[0053] The dried pre-carbonized material was placed in the carbon boat of the tubular activation furnace and heated to 850℃ at a rate of 10℃ / min. A dual-fluid nozzle was used to atomize the wastewater at a flow rate of 0.6 mL / min, controlling the droplet D50 to 35 μm. The nozzle outlet was 100 mm away from the carbon surface, and the material was directly atomized into the high-temperature zone for activation for 35 min.

[0054] Stop feeding wastewater, purge with nitrogen for 15 minutes, then maintain low flow nitrogen protection and cool with the furnace to below 120°C; remove the product, wash twice with 80°C hot water until the conductivity of the last wash solution is stable, filter, and dry at 105°C to obtain wood biomass activated carbon.

[0055] Example 2: Synergistic activation of ultrasonic atomization composite salt system Hardwood sawdust was used as raw material, washed, dried and crushed, with a moisture content controlled at 8%. It was then treated with microwave power of 1000W for 20 minutes under nitrogen protection at a final temperature of 550℃ to obtain pre-carbonized material. Subsequently, it was washed and stirred in 80℃ hot water at a liquid-to-solid mass ratio of 12:1 for 2.5 hours, then filtered and dried. High-salt wastewater containing chlorides and sulfates was subjected to fine filtration and oil removal, and droplets with a D50 of 25μm were formed using an ultrasonic atomizer. The pre-carbonized material was heated to 880℃ under nitrogen protection, and the atomized droplets were introduced into the high-temperature zone at a rate of 0.6mL / (min·100g pre-carbonized material) for activation for 45 minutes. Subsequent inert gas purging, oxygen-free cooling, water washing for desalination, and drying yielded activated carbon.

[0056] Example 3: Pretreatment and activation of high-salt metallurgical wastewater containing metal salts When high-salt wastewater contains high concentrations of easily hydrolyzable metal ions such as iron, zinc, copper, nickel, and manganese, the complexation state should be adjusted and selective impurities removed according to the pH value of the water to avoid the formation of large-particle hydroxide precipitates. If it contains a large amount of oil or extractant, it should first be treated with air flotation and directional stripping.

[0057] The treated wastewater enters a pressure nozzle via a heated conveying pipe. The heating temperature is 80℃, and the activation temperature is controlled at 850℃. The atomization feed rate is dynamically adjusted according to the carbon load. The reaction tail gas is treated by a condenser and a scrubbing device, and the condensate and scrubbing liquid is returned to the pretreatment unit.

[0058] Example 4: Continuous Atomization Activation System After continuous washing and crushing, the lignocellulosic biomass is fed into a belt-type inert atmosphere microwave pre-carbonization unit, where pre-carbonization is controlled at 500℃. The pre-carbonized material is then continuously washed with hot water, undergoes solid-liquid separation, and is dried before being sent to a rotary activation furnace. High-salt wastewater is filtered, metered, and heated before entering an atomization device equipped with an online rinsing interface and a backup nozzle. Using a differential pressure sensor at the nozzle tip as feedback, when the differential pressure exceeds a threshold, the interlocking system automatically switches to the backup nozzle and performs online rinsing. The activated charcoal is then cooled in an oxygen-free environment before entering a multi-stage counter-current continuous water washing and drying unit. The activation exhaust gas is condensed and washed before being discharged.

[0059] Example 5: Activated carbon for deep adsorption of high-salt metallurgical wastewater High-salt metallurgical wastewater, after primary treatment including neutralization, precipitation, and filtration, is treated to adjust pH and remove suspended solids. The activated carbon obtained in Examples 1 to 4 is packed into a fixed-bed adsorption column for continuous deep adsorption treatment, primarily removing residual extractants, flotation reagents, oils, surfactants, complexing agents, and chromatic components from the wastewater. The adsorbed effluent can be concentrated via membrane, evaporated for crystallization, or discharged in compliance with standards. After adsorption saturation, the activated carbon undergoes solid-liquid separation, followed by hot water washing, inert atmosphere thermal regeneration, or steam reactivation. Once its performance meets reuse requirements, it is returned to the adsorption unit. The regeneration wastewater and condensate generated during regeneration are returned to the high-salt metallurgical wastewater pretreatment unit for recycling.

[0060] V. Comparative and Performance Verification Tests To objectively evaluate the technical effect of the wastewater source salt template synergistic activation of the present invention, the following control experiment was set up while keeping the biomass source, pre-carbonization conditions, activation temperature, activation time and post-treatment conditions consistent: Comparative Example 1 uses deionized water instead of high-salt metallurgical wastewater for atomization activation; Comparative Example 2 uses water vapor obtained by evaporation of high-salt metallurgical wastewater and separation by a demister as the activation medium; Comparative Example 3 used a single-component sodium chloride solution prepared artificially, with the same total dissolved solids content as in the examples, and was activated by atomization. The example group uses real high-salt metallurgical wastewater atomized droplets from Examples 1 to 4 of the present invention.

[0061] Performance testing and results analysis: The performance test items are shown in the table below: Pore ​​structure analysis: The specific surface area, pore volume, and pore size distribution of each sample were tested using the nitrogen adsorption-desorption method. The results showed that the specific surface area and total pore volume of the Example Group were significantly higher than those of Comparative Example 1, proving that the in-situ activation of water vapor and the coupling of salt template have a significant synergistic gain effect. At the same time, the Example Group had a richer microporous-mesoporous composite pore structure than Comparative Example 3, indicating that the multi-metal composite salt system in real wastewater has better catalytic carbon-water vapor reaction and local melting pore-forming effect than a single salt.

[0062] Material composition characterization: SEM-EDS, XRD, ion chromatography or ICP-OES were used to analyze the samples before and after activation and before and after water washing. It can be clearly confirmed that the salt components of the wastewater source have entered the interior of the carbon material and formed a salt template, which was effectively removed in the subsequent water washing step, thus verifying the scientificity and feasibility of the salt template concept of the present invention.

[0063] Adsorption performance evaluation: The adsorption capacity of the samples for COD, TOC, color, target organic matter, and heavy metals in high-salt wastewater was measured. The results showed that the removal rate of organic pollutants in the example group was 20% to 35% higher than that in the deionized water atomization group. Especially under high-salt conditions with a total dissolved solids content of not less than 80 g / L, the activated carbon in the example group still maintained a very high adsorption capacity retention rate, demonstrating excellent high-salt adsorption performance. When measuring indicators such as total organic carbon and chemical oxygen demand in high-salt wastewater, for samples with high chloride ion concentrations, analytical methods suitable for high-chloride water samples should be used, or necessary chloride ion interference corrections should be performed on the test data to ensure the objectivity and accuracy of the adsorption performance evaluation.

[0064] Process continuity stability: In continuous feeding operation tests, the system of the present invention, equipped with heated conveying, differential pressure interlock, online flushing and backup nozzles, had a continuous non-clogging operation cycle that was more than 5 times longer than the control group without the aforementioned anti-clogging configuration, which greatly improved the reliability of system operation.

[0065] Recycling performance: The activated carbon obtained in the example group was subjected to adsorption, hot water washing and thermal regeneration cycle experiments. After 5 cycles, its adsorption capacity was still maintained at more than 85% of the initial capacity, which proved that the activated carbon has excellent industrial recyclability and service life, and effectively reduced the overall operating cost of deep treatment of high-salt metallurgical wastewater.

[0066] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0067] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing wood-based biomass activated carbon using high-salt metallurgical wastewater, characterized in that, Includes the following steps: Lignocellulose biomass is pretreated to obtain biomass pellets; The biomass pellets are pre-carbonized under an inert atmosphere to obtain pre-carbonized feed. The pre-carbonized material is purified to remove soluble impurities and tar. The purified pre-carbonized material is heated to a high-temperature activation zone under an inert atmosphere; High-salt metallurgical wastewater is pretreated and then atomized into droplets containing dissolved salts. The droplets are then allowed to directly enter the high-temperature activation zone and come into contact with the pre-carbonized material. The water in the droplets is vaporized in situ and participates in steam activation. The salt components in the droplets form a water-washable salt template on the surface and / or pores of the pre-carbonized material, which works together to activate and create pores. Stop feeding high-salt metallurgical wastewater and cool the activated products in an oxygen-free atmosphere. The activated product after cooling is washed with water to desalinate, separate and dry to obtain wood biomass activated carbon.

2. The method according to claim 1, characterized in that, The lignocellulose biomass is selected from at least one of wood processing waste, bamboo processing waste, or waste wood products; the particle size of the biomass particles meets the requirement that the median particle size D50 ≤ 200 mesh.

3. The method according to claim 1, characterized in that, The pre-carbonization treatment uses microwave heating at a temperature of 350-650℃ for 8-60 minutes. The purification treatment involves hot water washing at a temperature of 60-95℃ for 1-4 hours, with a liquid-to-solid mass ratio of 50:1-100:

1. The drying temperature is 95-120℃ for 2-8 hours.

4. The method according to claim 1, characterized in that, The high-salt metallurgical wastewater originates from leaching, extraction, back-extraction, washing, electrolysis, or flue gas purification processes in hydrometallurgical processes. The total dissolved solids content of the high-salt metallurgical wastewater is 30–250 g / L, and it contains chlorides, sulfates, nitrates, and at least one metal salt selected from sodium, potassium, calcium, magnesium, iron, zinc, copper, nickel, and manganese.

5. The method according to any one of claims 1-4, characterized in that, The pretreatment of the high-salt metallurgical wastewater before atomization includes at least one of the following: oil removal, pH adjustment, hardness adjustment, and fine filtration to remove volatile components or suspended solids.

6. The method according to claim 1, characterized in that, The median volumetric diameter of the atomized droplets is 5-150 μm, the atomization feed rate of the high-salt metallurgical wastewater is 0.1-2.0 mL / (min·100g pre-carbonized material), the temperature of the high-temperature activation zone is 750-950℃, and the activation time is 10-90 min; the salt components form the elutable salt template through deposition, crystallization, melting, or catalytic steam reaction.

7. The method according to claim 1, characterized in that, The cooling is carried out under continuous inert atmosphere protection and oxygen-free cooling to a temperature not exceeding 150°C; the water washing and desalination is carried out by washing multiple times with a detergent at 20~95°C until the salt content in the liquid phase after washing reaches the preset endpoint.

8. A synergistic activation system for implementing the method according to any one of claims 1-7, characterized in that, include: The pre-carbonization unit, the pre-carbonized material post-processing unit, the activation reactor, the inert atmosphere supply unit, the wastewater storage and pre-treatment unit, the metering and conveying unit, the atomizing device, the oxygen-free cooling unit, the water washing and desalination unit, and the tail gas treatment unit. The atomizing device is located upstream or inside the high-temperature treatment zone of the activation reactor, and a heat tracing structure is provided between the atomizing device and the metering and conveying unit. The atomizing device is also equipped with an online rinsing component and a spare nozzle.

9. A type of wood-based biomass activated carbon, characterized in that, The woody biomass activated carbon prepared by the method according to any one of claims 1-7 has a multi-level porous structure formed by the synergistic effect of in-situ steam activation and a wastewater source washable desalination template.

10. The application of the wood-based biomass activated carbon according to claim 9 in the deep treatment of high-salt metallurgical wastewater, characterized in that, The wood-based biomass activated carbon is used to adsorb and remove organic pollutants, color, oils, extractants or flotation reagents from high-salt metallurgical wastewater. After the wood-based biomass activated carbon is saturated, it is reused after being washed with hot water or thermally regenerated, and the waste liquid generated during the regeneration process is returned to the pretreatment process of high-salt metallurgical wastewater.

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