A micro-channel homogeneous regulation arsenic-containing copper dust selective arsenic fixation and copper-zinc separation system and method

Abstract

This invention belongs to the field of hydrometallurgical technology, specifically disclosing a microchannel homogeneous-controlled selective arsenic fixation and copper-zinc separation system and method for arsenic-containing copper dust. The system includes oxidative leaching, homogeneous neutralization, fluidized bed directional crystallization, solid-liquid separation units, and a controller. The oxidative leaching unit is equipped with a leaching tank and an oxidant supply assembly. Dual high-pressure pumps deliver the leaching solution and neutralizing agent into a microchannel mixing reactor for counter-mixing. The reactor outlet is connected to a vertical fluidized bed crystallizer. The crystallizer contains a fluid distribution plate and arsenic crystal seeds, and is equipped with a temperature control and bed expansion monitoring module connected to the controller. The crystallization overflow is sent to a solid-liquid separator, producing a copper-zinc rich filtrate and a stable arsenic-fixed slag. The method includes oxidative leaching, homogeneous neutralization, fluidized bed directional crystallization, and solid-liquid separation steps. This invention utilizes microchannel technology coupled with fluidized bed crystallization to significantly reduce copper-zinc entrainment losses and obtain highly stable arsenic slag and high-purity copper-zinc slurry.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a microchannel homogeneous control system and method for selective arsenic fixation and copper-zinc separation of arsenic-containing copper dust. Background Technology

[0002] The smelting, blowing, and electrolysis processes in copper smelting generate large amounts of high-arsenic smelting fumes. These fumes are enriched with valuable / hazardous components such as Cu, Zn, Fe, and As, and are typical hazardous solid waste. Currently, the mainstream treatment route for high-arsenic smelting fumes in copper smelting is a hydrometallurgical process involving sulfuric acid leaching to remove metals and arsenic. This is followed by adding an alkaline agent to a mechanically stirred reactor to adjust the pH value, promoting the precipitation of iron and arsenic to stabilize the arsenic. However, existing technologies suffer from three irreconcilable industrial problems, and no single existing solution can simultaneously solve all of them: First, traditional mechanically stirred reactors result in significant loss of valuable metals through macroscopic mixing. For example, techniques relying on paddle-based macroscopic stirring to mix neutralizing agents suffer from the inherent lag in macroscopic mixing, leading to the formation of localized high-pH supersaturation zones at the dosing port, thus increasing the loss of Cu. 2+ Zn 2+ Simultaneous formation of hydroxide co-precipitates results in a final copper-zinc loss of up to 10% to 20%. Even with seed crystal-assisted stirring for arsenic precipitation, the reliance on batch alkali addition within the reactor fails to eliminate local pH fluctuations, leading to high copper-zinc impurity content in the final arsenic slag and significantly reducing the purity of subsequent copper-zinc products.

[0003] Secondly, the explosive nucleation of amorphous arsenic colloids leads to filtration difficulties and secondary arsenic pollution. In existing batch reactor systems, localized high supersaturation not only easily triggers the instantaneous explosive nucleation of copper and zinc ions in the solution, forming hydroxide co-precipitates, but also easily causes iron and arsenic to precipitate in a "burst-like continuous nucleation" manner, generating amorphous ferric arsenate colloids with a large specific surface area. Because these colloids strongly adsorb and easily encapsulate copper and zinc in the solution, and have high water content, they are extremely difficult to filter; moreover, the amorphous arsenic mineral crystal structure is unstable, and arsenic is easily leached and dissolved under natural accumulation, resulting in a significant exceedance of TCLP toxic arsenic leaching concentrations, posing a long-term risk of secondary environmental pollution to soil and groundwater. Furthermore, conventional stirred tank crystallization lacks fluidized epitaxial growth conditions, resulting in small product grains and poor crystallinity, making it impossible to fundamentally prevent colloid formation.

[0004] Furthermore, single microchannel devices lack industrial anti-clogging support, making long-term continuous production impossible. While some technologies utilize microchannels for ozone oxidation pretreatment, they fail to leverage microchannels for precise pH control. Additionally, existing single-channel micromixing equipment in chemical processing readily and rapidly precipitates iron and arsenic precursor scale on the channel walls when directly treating high-concentration multi-metal metallurgical leaching solutions, leading to short-term blockages and shutdowns, thus lacking long-term industrial reliability.

[0005] As can be seen from the above, the existing batch arsenic precipitation process, single crystal stirring process, and simple microfluidic device can only alleviate a single defect and cannot simultaneously achieve the three major industrialization goals of low copper and zinc loss, highly stable crystallized arsenic slag, and long-term continuous operation of equipment. The industry urgently needs a complete process and supporting equipment that can simultaneously solve the above multiple defects. Summary of the Invention

[0006] To completely solve the shortcomings of copper-zinc co-precipitation, unstable arsenic slag, and easy equipment blockage in the treatment of high-arsenic materials, this invention provides a microchannel homogeneous control system for selective arsenic fixation and copper-zinc separation of arsenic-containing copper dust, and also provides a microchannel homogeneous control method for selective arsenic fixation and copper-zinc separation of arsenic-containing copper dust.

[0007] The microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system for arsenic-containing copper dust of the present invention is implemented as follows: it includes an oxidation leaching unit, a homogeneous neutralization unit, a fluidized bed directional crystallization unit, a solid-liquid separation unit, and a controller; The oxidation leaching unit includes an oxidation leaching tank and an oxidant supply component, wherein the supply port of the oxidant supply component is connected to the oxidation leaching tank. The homogeneous neutralization unit includes two independent high-pressure pumps, a microchannel mixing reactor, and a liquid neutralizing agent storage tank. The liquid neutralizing agent storage tank is located on the side of the microchannel mixing reactor. One high-pressure pump is connected to the drain outlet of the oxidative leaching tank and the feed inlet of the microchannel mixing reactor at both ends, respectively. The other high-pressure pump is connected to the drain outlet of the liquid neutralizing agent storage tank and the neutralizing agent inlet of the microchannel mixing reactor at both ends, respectively. The fluidized bed directional crystallization unit includes a vertical fluidized bed crystallizer, a fluid distribution plate, scorched onion seed crystals, a temperature control component, and an online bed expansion monitoring module. The outlet of the microchannel mixing reactor is connected to the bottom or lower part of the vertical fluidized bed crystallizer via a pipeline. The fluid distribution plate is horizontally positioned above the liquid inlet at the lower part of the vertical fluidized bed crystallizer. The scorched onion seed crystals are positioned on the fluid distribution plate inside the vertical fluidized bed crystallizer. The temperature control component and the online bed expansion monitoring module are respectively positioned on the vertical fluidized bed crystallizer and electrically connected to the controller. An overflow outlet is provided at the top or upper part of the vertical fluidized bed crystallizer. The solid-liquid separation unit includes a solid-liquid separator. The feed inlet of the solid-liquid separator is connected to the overflow outlet of the vertical fluidized bed crystallizer. The solid-liquid separator is provided with two outlets. One outlet outputs copper-zinc rich filtrate to the valuable metal recovery section, and the other outlet outputs arsenic-fixed slag from styrofoam stone for external stabilization and storage.

[0008] Furthermore, the microchannel mixing reactor includes two sets of parallel microchannel components, an ultrasonic transducer, and an acid supply component. The ultrasonic transducer is attached to the outer wall of the microchannel component. The outlet of the microchannel component is connected to the acid supply component through a pipeline, and the inlet of the microchannel component is connected to the oxidation leaching tank through a pipeline. Control valves are respectively installed on the pipelines connecting the inlet, neutralizer inlet, and outlet of the two sets of microchannel components of the microchannel mixing reactor. Each control valve of the microchannel component is electrically connected to a controller.

[0009] Furthermore, the vertical fluidized bed crystallizer is provided with a seed feed port, and the particle size of the styrax seed crystal is D50 20μm~50μm.

[0010] Furthermore, the ultrasonic transducer operates at a frequency of 20kHz to 40kHz and has a power density of 0.1W / cm². 2 ~0.5W / cm 2 The acid supply component supplies 5g / L~10g / L dilute sulfuric acid.

[0011] The microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation method for arsenic-containing copper dust of the present invention is implemented as follows: Based on the aforementioned microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system for arsenic-containing copper dust, the method includes the steps of oxidative leaching, homogeneous neutralization, fluidized bed directional crystallization, and solid-liquid separation. The specific details of each step are as follows: A. Oxidative leaching: Arsenic-containing copper fumes are passed into an oxidative leaching tank containing a sulfuric acid solution with a mass concentration of 10 g / L to 200 g / L. Then, an oxidant is added to the oxidative leaching tank, and the mixture is thoroughly mixed and oxidized and leached. Solid-liquid separation yields a multi-metallic leachate containing pentavalent arsenic, trivalent iron, divalent copper, and divalent zinc. B. Homogeneous neutralization: The multi-metal leaching solution and liquid neutralizing agent are simultaneously injected into the microchannel component of the microchannel mixing reactor via high-pressure pumps for counter-current mixing to obtain a metastable solid arsenic precursor solution without large particle precipitates. C. Fluidized Bed Directional Crystallization: Metastable arsenic-fixing precursor solution is continuously fed from the bottom or lower part into a vertical fluidized bed crystallizer pre-filled with onion crystal seeds. The temperature, apparent flow rate of the bottom inlet liquid, and expansion rate of the seed bed are controlled within the vertical fluidized bed crystallizer to reduce the supersaturated Fe in the metastable arsenic-fixing precursor solution. 3+ AsO4 3- Heterogeneous epitaxial growth occurs with stinking onion crystals as the core, and high-crystallinity stinking onion solid arsenic slag is generated by in-situ co-precipitation, resulting in crystallization slurry overflowing from the self-standing fluidized bed crystallizer; D. Solid-liquid separation: The crystallized slurry is fed into a solid-liquid separator, and the copper-zinc rich filtrate and arsenic-fixing slag from stinking onion stone are obtained through solid-liquid separation.

[0012] Further, in step A, an oxidant is added to the oxidative leaching tank to adjust the oxidation-reduction potential of the system to ORP=450mV~600mV; the oxidant is selected from any one of hydrogen peroxide, air, oxygen, and ozone; the arsenic-containing copper dust is high-arsenic dust produced by copper smelting, copper blowing, or copper electrolysis.

[0013] Furthermore, in step B, the flow rate and volume of the multi-metal leachate and liquid neutralizer injected into the microchannel component are controlled to ensure that the liquid film mixing thickness in the microchannel component is between 10 μm and 500 μm, the mixing residence time is between 0.01 s and 0.5 s, and the instantaneous pH of the mixture is stable between 1.5 and 2.5.

[0014] Furthermore, the liquid neutralizing agent is one of sodium hydroxide solution, ammonia water, and lime milk, and the mass concentration of the liquid neutralizing agent is 80g / L to 120g / L; the counter-mixing in the microchannel component is T-type, Y-type, or cross-type coaxial counter-mixing.

[0015] Furthermore, in step C, the temperature inside the vertical fluidized bed crystallizer is 85℃~100℃, the apparent flow rate of the liquid inlet at the bottom is 0.5cm / s~2.0cm / s, and the expansion rate of the seed bed is 120%~150%.

[0016] Further, in step B, the two sets of microchannel components in the microchannel mixing reactor alternately perform counter-flushing mixing and cleaning: one set of microchannel components is simultaneously injected with multi-metal leaching solution and liquid neutralizing agent for counter-flushing mixing; the other set of microchannel components is injected with 5g / L~10g / L dilute sulfuric acid through an acid supply component for online backwashing to dissolve scale, and the cleaning waste liquid is returned to the oxidative leaching tank; while counter-flushing mixing and / or backwashing are performed, the ultrasonic transducers attached to the corresponding microchannel components are turned on, with a working frequency of 20kHz~40kHz and an ultrasonic field power density of 0.1W / cm². 2 ~0.5W / cm 2 .

[0017] The present invention has the following beneficial effects: 1. Eliminating localized high pH supersaturation: This invention innovatively employs a dual-channel high-pressure pump to simultaneously inject multi-metal leaching solution and liquid neutralizing agent into the microchannel components of a microchannel mixing reactor for counter-mixing. Millisecond-level uniform mixing is achieved within the microchannels using an ultra-thin liquid film of 10μm to 500μm, with precise and stable pH control throughout the entire process at 1.5 to 2.5. This completely eliminates the problem of excessive alkali in the dosing zone of the stirred tank. Furthermore, only metastable precursor solutions are generated, and there is no instantaneous co-precipitation of hydroxides throughout the process, effectively reducing the chemical precipitation and physical entrainment of copper and zinc. The proportion of copper and zinc entering the solidified arsenic slag is ≤3%, and the copper and zinc content in the solidified arsenic slag is ≤0.5%, solving the problem of valuable metal loss in traditional stirred tank reactors.

[0018] 2. Unlike existing stirred tanks that simultaneously nucleate and precipitate amorphous ferric arsenate, this invention uses microchannel counter-fluid mixing to achieve only uniform pH control without triggering solid-phase precipitation. The metastable precursor liquid is then fed into a fluidized bed with an expanded seed crystal layer, relying on the epitaxial and directional growth of crystals from the arsenic crystal seeds, thus avoiding the formation of ultrafine colloids. Moreover, the resulting arsenic residue is dense and sandy with a water content of only 16% to 20%, so the solid-liquid separation speed is faster than that of traditional mortar arsenic residue. Furthermore, the arsenic concentration in the toxic leaching (TCLP) of solid arsenic residue is far below the national standard limit, completely solving the hidden danger of back dissolution pollution from the storage of amorphous residue.

[0019] 3. To address the shortcomings of existing single-channel microchannel mixing reactors that are prone to scaling and shutdown when treating polymetallic waste liquids, this invention equips the outer wall of the microchannel component with an ultrasonic transducer of 20kHz to 40kHz. This transducer relies on the cavitation effect to break down the boundary layer and inhibit scale adhesion. Simultaneously, two sets of microchannel components are set up to operate alternately. By adopting an alternating operation mode of one set producing and the other set being backwashed online with 5g / L to 10g / L dilute sulfuric acid, and by recycling the cleaning waste liquid back to the oxidation leaching tank in a closed loop, arsenic-containing copper dust can be continuously treated without shutdown for disassembly and cleaning. This overcomes the shortcomings of existing single microfluidic reactors that lack industrial anti-clogging support.

[0020] In summary, addressing the three core industry problems of copper and zinc loss in existing autoclave processes, easy contamination by amorphous arsenic slag, and easy clogging of microchannel equipment, this invention adopts a complete coupled innovative solution of microchannel millisecond homogeneous neutralization + fluidized bed crystal seed directional crystallization + ultrasonic synergistic dual-channel online acid washing. This solution simultaneously solves multiple defects of existing technologies from three levels: reaction source, crystallization process, and equipment operation. It can be directly implemented for large-scale disposal of high-arsenic dust from copper smelting, while simultaneously taking into account both metal recovery benefits and compliance requirements for hazardous waste environmental protection. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation device for arsenic-containing copper dust according to the present invention. Figure 2 This is a flowchart of the microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation method for arsenic-containing copper dust according to the present invention. In the diagram: 1-Oxidation leaching tank, 2-High pressure pump, 3-Microchannel mixing reactor, 4-Vertical fluidized bed crystallizer, 5-Fluid distribution plate, 6-Solid-liquid separator, 7-Ultrasonic transducer, 8-Acid supply assembly. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this is not intended to limit the present invention in any way. Any changes or improvements made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0023] like Figure 1 As shown, the microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system for arsenic-containing copper dust of the present invention includes an oxidation leaching unit, a homogeneous neutralization unit, a fluidized bed directional crystallization unit, a solid-liquid separation unit, and a controller. The oxidation leaching unit includes an oxidation leaching tank 1 and an oxidant supply component, wherein the supply port of the oxidant supply component is connected to the oxidation leaching tank 1. The homogeneous neutralization unit includes two independent high-pressure pumps 2, a microchannel mixing reactor 3, and a liquid neutralizing agent storage tank. The liquid neutralizing agent storage tank is located on the side of the microchannel mixing reactor 3. One high-pressure pump 2 is connected to the drain outlet of the oxidative leaching tank 1 and the feed inlet of the microchannel mixing reactor 3 at both ends, and the other high-pressure pump 2 is connected to the drain outlet of the liquid neutralizing agent storage tank and the neutralizing agent inlet of the microchannel mixing reactor 3 at both ends. The fluidized bed directional crystallization unit includes a vertical fluidized bed crystallizer 4, a fluid distribution plate 5, a spore stone seed crystal (FeAsO4·2H2O), a temperature control component, and an online bed expansion monitoring module. The outlet of the microchannel mixing reactor 3 is connected to the bottom or lower part of the vertical fluidized bed crystallizer 4 through a pipeline. The fluid distribution plate 5 is horizontally arranged above the liquid inlet at the lower part of the vertical fluidized bed crystallizer 4. The spore stone seed crystal is arranged on the fluid distribution plate 5 inside the vertical fluidized bed crystallizer 4. The temperature control component and the online bed expansion monitoring module are respectively arranged on the vertical fluidized bed crystallizer 4 and electrically connected to the controller. An overflow outlet is provided at the top or upper part of the vertical fluidized bed crystallizer 4. The solid-liquid separation unit includes a solid-liquid separator 6. The feed inlet of the solid-liquid separator 6 is connected to the overflow outlet of the vertical fluidized bed crystallizer 4. The solid-liquid separator 6 is provided with two outlets. One outlet outputs copper-zinc rich filtrate to the valuable metal recovery section, and the other outlet outputs arsenic-fixed slag from the arsenic-fixing process for external stabilization and storage.

[0024] The microchannel mixing reactor 3 includes two sets of parallel microchannel components, an ultrasonic transducer 7, and an acid supply component 8. The ultrasonic transducer 7 is attached to the outer wall of the microchannel component. The outlet of the microchannel component is connected to the acid supply component 8 through a pipeline. The inlet of the microchannel component is connected to the oxidation leaching tank 1 through a pipeline. Control valves are respectively installed on the pipelines connecting the inlet, neutralizer inlet, and outlet of the two sets of microchannel components of the microchannel mixing reactor 3. Each control valve (not shown in the figure) of the microchannel component is electrically connected to a controller (not shown in the figure).

[0025] The vertical fluidized bed crystallizer 4 is equipped with a seed feed port, and the particle size of the stinky onion stone seed is D50 20μm~50μm.

[0026] The ultrasonic transducer 7 operates at a frequency of 20kHz to 40kHz and has a power density of 0.1W / cm². 2 ~0.5W / cm 2 The acid supply component 8 supplies 5g / L~10g / L dilute sulfuric acid. The cavitation effect disrupts the fluid boundary layer on the inner wall of the microchannel component, inhibiting the adhesion of precursors to the channel inner wall.

[0027] The oxidative leaching tank 1 is equipped with a primary solid-liquid separator at its discharge port. The liquid phase outlet of the primary solid-liquid separator is connected to the feed port of the microchannel mixing reactor 3 via a high-pressure pump 2.

[0028] The first-stage solid-liquid separator and the solid-liquid separator 6 are respectively a hydrocyclone separator or a centrifugal separator, the high-pressure pump 2 is a high-pressure horizontal flow pump, the microchannel component of the microchannel mixing reactor 3 is a microchannel structural component in the prior art, and the controller is a PC, PLC or industrial control computer.

[0029] like Figure 1 and 2 As shown, the microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation method for arsenic-containing copper dust of the present invention, based on the aforementioned microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system for arsenic-containing copper dust, includes the steps of oxidative leaching, homogeneous neutralization, fluidized bed directional crystallization, and solid-liquid separation. The specific steps are as follows: A. Oxidative leaching: Arsenic-containing copper fumes are passed into an oxidative leaching tank 1 containing a sulfuric acid solution with a mass concentration of 10 g / L to 200 g / L. Then, an oxidant is added to the oxidative leaching tank 1, and the mixture is thoroughly mixed and oxidatively leached. Solid-liquid separation is performed to obtain a multi-metallic leachate containing pentavalent arsenic, trivalent iron, divalent copper, and divalent zinc. B. Homogeneous neutralization: The multi-metal leaching solution and the liquid neutralizing agent are simultaneously injected into the microchannel component of the microchannel mixing reactor 3 via high-pressure pump 2 for counter-current mixing to obtain a metastable solid arsenic precursor solution without large particle precipitates. C. Fluidized Bed Directional Crystallization: The metastable solidified arsenic precursor solution is continuously fed from the bottom or lower part into a vertical fluidized bed crystallizer 4 pre-filled with stolonite seeds. The temperature, apparent flow rate of the bottom inlet liquid, and expansion rate of the seed bed are controlled within the vertical fluidized bed crystallizer 4 to reduce the supersaturated Fe in the metastable solidified arsenic precursor solution. 3+ AsO4 3- Heterogeneous epitaxial growth occurs with stinking onion crystals as the core, and high-crystallinity stinking onion solid arsenic slag is generated by in-situ co-precipitation, resulting in crystallization slurry overflowing from the self-standing fluidized bed crystallizer 4. D. Solid-liquid separation: The crystallized slurry is fed into the solid-liquid separator 6, and the copper-zinc rich filtrate and arsenic-fixing slag from stinking onion stone are obtained through solid-liquid separation.

[0030] In step A, an oxidant is added to the oxidative leaching tank 1 to adjust the oxidation-reduction potential of the system to ORP=450mV~600mV; the oxidant is selected from any one of hydrogen peroxide, air, oxygen, and ozone; the arsenic-containing copper dust is high-arsenic dust produced by copper smelting, copper blowing, or copper electrolysis.

[0031] In step B, the flow rate and volume of the multi-metal leachate and liquid neutralizer injected synchronously into the microchannel component are controlled to ensure that the liquid film mixing thickness within the microchannel component is between 10 μm and 500 μm, the mixing residence time is between 0.01 s and 0.5 s, and the instantaneous pH of the mixture is stabilized between 1.5 and 2.5. By adjusting the feed flow rate ratio of the multi-metal leachate and the liquid neutralizer, the instantaneous pH value of the mixture in the microchannel component is uniformly increased within milliseconds and precisely controlled between 1.5 and 2.5.

[0032] The liquid neutralizing agent is one of sodium hydroxide solution, ammonia water, and lime milk, and the mass concentration of the liquid neutralizing agent is 80g / L to 120g / L; the counter-mixing in the microchannel assembly is T-type, Y-type, or cross-type coaxial counter-mixing.

[0033] In step C, the temperature inside the vertical fluidized bed crystallizer 4 is 85℃~100℃, the apparent flow rate of the liquid inlet at the bottom is 0.5cm / s~2.0cm / s, and the expansion rate of the seed bed is 120%~150%.

[0034] In step B, the two sets of microchannel components in the microchannel mixing reactor 3 alternately perform counter-flushing mixing and cleaning: one set of microchannel components is simultaneously injected with multi-metal leaching solution and liquid neutralizing agent for counter-flushing mixing; the other set of microchannel components is injected with 5g / L~10g / L dilute sulfuric acid through the acid supply component 8 for online backwashing to dissolve scale, and the cleaning waste liquid is returned to the oxidation leaching tank 1; while counter-flushing mixing and / or backwashing are performed, the ultrasonic transducers 7 attached to the corresponding microchannel components are turned on, with a working frequency of 20kHz~40kHz and an ultrasonic field power density of 0.1W / cm². 2 ~0.5W / cm 2 .

[0035] Example 1

[0036] Taking the selective arsenic fixation and copper-zinc separation of high-arsenic flue dust from copper smelting at a copper plant as an example, the specific process is as follows: S100: The high-arsenic smelting flue dust from the copper plant is introduced into an oxidative leaching tank 1 containing a sulfuric acid solution with a solute concentration of 100 g / L. Then, air is added to the oxidative leaching tank 1 by controlling the oxidant supply component, and the mixture is thoroughly mixed and oxidized and leached. The oxidation-reduction potential of the mixture in the oxidative leaching tank 1 is maintained between 450 mV and 500 mV. Subsequently, the mixture is discharged through the outlet of the oxidative leaching tank 1 and separated by a primary solid-liquid separator to obtain a multi-metallic leaching solution containing pentavalent arsenic, trivalent iron, divalent copper, and divalent zinc (Cu 15 g / L, Zn 8 g / L, Fe 10 g / L, As 8 g / L, ORP 500 mV, free acid 20 g / L).

[0037] S200: The multi-metal leaching solution and 100 g / L NaOH solution are simultaneously injected into one of the microchannel components of the microchannel mixing reactor 3 via high-pressure pump 2 for counter-current mixing (the 28 kHz ultrasonic transducer 7 is turned on simultaneously); the flow rate and flow rate of the multi-metal sulfuric acid leaching solution and NaOH solution injected into the microchannel component are controlled to ensure that the liquid film mixing thickness in the microchannel component is 200 μm, the mixing residence time is 0.1 s, and the instantaneous pH of the mixture is stable at 1.8, so as to obtain a metastable solid arsenic precursor solution without large particle precipitates.

[0038] S300: The metastable arsenic-fixing precursor solution is continuously fed from the bottom into a vertical fluidized bed crystallizer 4 pre-filled with 1 g / L of onion crystal seeds. The temperature inside the vertical fluidized bed crystallizer 4 is controlled at 95℃ and the apparent flow rate at the bottom inlet is 1.2 cm / s, so that the supersaturated Fe in the metastable arsenic-fixing precursor solution... 3+ AsO4 3- Heterogeneous epitaxial growth occurs with arsenic crystals as the core, and high-crystallinity arsenic-fixing slag is generated by in-situ co-precipitation, resulting in crystallization slurry overflowing from the self-standing fluidized bed crystallizer 4.

[0039] S400: The crystallized slurry is fed into the solid-liquid separator 6, and the copper-zinc rich filtrate and arsenic-fixing slag from stinking onion stone are obtained through solid-liquid separation.

[0040] Results: After 24 hours of continuous system operation, the direct recovery rate of copper and zinc in the filtrate was >99%. The arsenic-fixing slag from the stinking onion stone was sandy with a moisture content of only 18%, and the copper and zinc content in the slag was <0.1%. The arsenic leaching amount by TCLP was only 0.35 mg / L.

[0041] Example 2

[0042] Based on Example 1, the sulfuric acid solute concentration in step S100 is 10 g / L; the two sets of microchannel components in the microchannel mixing reactor 3 operate alternately in dual channels, switching once every 12 h; during cleaning, the microchannel components are backwashed online with 10% dilute sulfuric acid injected through the acid supply component 8 to dissolve the scale, and the cleaning waste liquid is returned to the oxidation leaching tank 1.

[0043] Results: After 72 hours of continuous operation, the system remained stable without any blockages; the arsenic precipitation rate remained above 98%; and the copper loss rate was less than 3.5%.

[0044] Example 3

[0045] Based on Example 1, the sulfuric acid solute concentration in step S100 was reduced to 200 g / L, air was replaced with hydrogen peroxide, and the oxidation-reduction potential of the mixture in the oxidative leaching tank 1 was maintained between 550 mV and 600 mV. After oxidative leaching, the mixture was separated by a primary solid-liquid separator to obtain a polymetallic sulfuric acid leaching solution. The 100 g / L NaOH solution in step S200 was replaced with 80 g / L lime slurry for counter-mixing (with the 40 kHz ultrasonic transducer 7 turned on simultaneously). The liquid film mixing thickness in the microchannel assembly was controlled to be 10 μm, the mixing residence time to be 0.5 s, and the instantaneous pH of the mixture to be stable at 1.5, resulting in a metastable solid arsenic precursor solution without large particle precipitates. The temperature in the vertical fluidized bed crystallizer 4 in step S300 was adjusted from 95 °C to 85 °C, and the apparent flow rate of the bottom inlet was adjusted from 1.2 cm / s to 2.0 cm / s.

[0046] Among them, the two sets of microchannel components of the microchannel mixing reactor 3 adopt dual-channel alternating operation and switch every 8 hours; during cleaning, the microchannel components are injected with 5g / L of dilute sulfuric acid through the acid supply component 8 for online backwashing to dissolve the scale, and the cleaning waste liquid is returned to the oxidation leaching tank 1.

[0047] Results: After 48 hours of continuous operation, the system remained stable without clogging; the direct recovery rate of copper in the filtrate was >98.5%, and the direct recovery rate of zinc was >99%. The arsenic-fixing slag from the stinking onion stone was sandy with a moisture content of only 16%, and the arsenic precipitation rate remained above 97%; the copper and zinc content in the slag was both <0.1%. The arsenic leaching amount by TCLP was only 0.38 mg / L.

[0048] Example 4

[0049] Based on Example 1, the sulfuric acid solute concentration in the sulfuric acid solution in step S100 was increased to 150 g / L, air was replaced with oxygen, and the oxidation-reduction potential of the mixed solution in the oxidative leaching tank 1 was maintained between 500 mV and 550 mV. After oxidative leaching, the solution was separated into solid and liquid by a primary solid-liquid separator to obtain a polymetallic sulfuric acid leaching solution. The 100 g / L NaOH solution in step S200 was replaced with 120 g / L ammonia solution for counter-mixing (with the 20 kHz ultrasonic transducer 7 turned on simultaneously). The liquid film mixing thickness in the microchannel component was controlled to be 500 μm, the mixing residence time to be 0.01 s, and the instantaneous pH of the mixed solution to be stable at 2.5, resulting in a metastable solid arsenic precursor solution without large particle precipitates. The temperature in the vertical fluidized bed crystallizer 4 in step S300 was adjusted from 95 °C to 100 °C, and the apparent flow rate of the bottom inlet was adjusted from 1.2 cm / s to 0.5 cm / s.

[0050] Among them, the two sets of microchannel components of the microchannel mixing reactor 3 adopt dual-channel alternating operation and switch every 8 hours; during cleaning, the microchannel components are injected with 10g / L dilute sulfuric acid through the acid supply component 8 for online backwashing to dissolve the scale, and the cleaning waste liquid is returned to the oxidation leaching tank 1.

[0051] Results: After 48 hours of continuous operation, the system remained stable without clogging; the direct recovery rate of copper in the filtrate was >98%, and the direct recovery rate of zinc was >98.5%. The arsenic-fixing slag from the stinking onion stone was sandy with a moisture content of only 20%, and the arsenic precipitation rate remained above 96%; both copper and zinc in the slag were <0.15%. The arsenic leaching amount by TCLP was only 0.42 mg / L.

[0052] Comparative Example 1 Take the same leachate from Example 1 and place it in a conventional mechanically stirred reactor. Slowly add NaOH solution at 95°C until the pH reaches 1.8, and keep the mixture warm and stirred for 4 hours.

[0053] Results: After 24 hours of continuous operation, the dosing port became locally turbid, and the filtration time was 6 times that of Example 1. The residue was clay-like with a moisture content of 45%, and contained 2.5% copper and 1.2% zinc. The TCLP arsenic leaching amount reached 12.5 mg / L (exceeding the standard and failing the test).

[0054] Comparative Example 2 Based on Example 1, the styrax seed crystal in step S300 was replaced with aluminosilicate seed crystal (AlAsO4・2H2O), and the other conditions were the same as in Example 1.

[0055] Results: After 24 hours of continuous operation, the copper loss rate was 8.6%; the zinc loss rate was 10.1%; and the precipitate particle size was 15 μm.

[0056] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system for arsenic-containing copper dust, characterized in that: Includes an oxidation leaching unit, a homogeneous neutralization unit, a fluidized bed directional crystallization unit, a solid-liquid separation unit, and a controller; The oxidation leaching unit includes an oxidation leaching tank (1) and an oxidant supply component, wherein the supply port of the oxidant supply component is connected to the oxidation leaching tank (1). The homogeneous neutralization unit includes two independent high-pressure pumps (2), a microchannel mixing reactor (3), and a liquid neutralizing agent storage tank. The liquid neutralizing agent storage tank is located on the side of the microchannel mixing reactor (3). One of the high-pressure pumps (2) is connected to the drain outlet of the oxidative leaching tank (1) and the feed inlet of the microchannel mixing reactor (3) at both ends, respectively. The other high-pressure pump (2) is connected to the drain outlet of the liquid neutralizing agent storage tank and the neutralizing agent inlet of the microchannel mixing reactor (3) at both ends, respectively. The fluidized bed directional crystallization unit includes a vertical fluidized bed crystallizer (4), a fluid distribution plate (5), scorched onion seed crystals, a temperature control component, and an online bed expansion monitoring module. The outlet of the microchannel mixing reactor (3) is connected to the bottom or lower part of the vertical fluidized bed crystallizer (4) through a pipeline. The fluid distribution plate (5) is horizontally arranged above the liquid inlet at the lower part of the vertical fluidized bed crystallizer (4). The scorched onion seed crystals are arranged on the fluid distribution plate (5) inside the vertical fluidized bed crystallizer (4). The temperature control component and the online bed expansion monitoring module are respectively arranged on the vertical fluidized bed crystallizer (4) and electrically connected to the controller. An overflow outlet is provided at the top or upper part of the vertical fluidized bed crystallizer (4). The solid-liquid separation unit includes a solid-liquid separator (6). The feed inlet of the solid-liquid separator (6) is connected to the overflow outlet of the vertical fluidized bed crystallizer (4). The solid-liquid separator (6) is provided with two outlets. One outlet outputs copper-zinc rich filtrate to the valuable metal recovery section, and the other outlet outputs arsenic-fixed slag from stinking onion stone for external stabilization and storage.

2. The microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system for arsenic-containing copper dust according to claim 1, characterized in that: The microchannel mixing reactor (3) includes two sets of parallel microchannel components, an ultrasonic transducer (7), and an acid supply component (8). The ultrasonic transducer (7) is attached to the outer wall of the microchannel component. The outlet of the microchannel component is connected to the acid supply component (8) through a pipeline. The inlet of the microchannel component is connected to the oxidation leaching tank (1) through a pipeline. Control valves are respectively installed on the pipelines connecting the inlet, neutralizer inlet and outlet of the two sets of microchannel components of the microchannel mixing reactor (3). Each control valve of the microchannel component is electrically connected to the controller.

3. The microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system for arsenic-containing copper dust according to claim 2, characterized in that: The vertical fluidized bed crystallizer (4) is provided with a seed feed port, and the particle size of the stinky onion seed crystal is D5020μm~50μm.

4. The microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system for arsenic-containing copper dust according to claim 2 or 3, characterized in that: The ultrasonic transducer (7) operates at a frequency of 20kHz to 40kHz and has a power density of 0.1W / cm². 2 ~0.5W / cm 2 The acid supply component (8) supplies 5g / L~10g / L dilute sulfuric acid.

5. A method for selective arsenic fixation and separation of copper and zinc from arsenic-containing copper dust using microchannel homogeneous control, characterized in that: The microchannel homogeneous phase-controlled selective arsenic fixation and copper-zinc separation system based on claim 2, 3 or 4 includes the steps of oxidative leaching, homogeneous neutralization, fluidized bed directional crystallization, and solid-liquid separation. The specific details of each step are as follows: A. Oxidative leaching: Arsenic-containing copper dust is introduced into an oxidative leaching tank (1) containing a sulfuric acid solution with a mass concentration of 10 g / L to 200 g / L. Then, an oxidant is added to the oxidative leaching tank (1), and the mixture is thoroughly mixed and oxidized. Solid-liquid separation is performed to obtain a multi-metallic leachate containing pentavalent arsenic, trivalent iron, divalent copper, and divalent zinc. B. Homogeneous neutralization: The multi-metal leaching solution and liquid neutralizing agent are simultaneously injected into the microchannel component of the microchannel mixing reactor (3) via a high-pressure pump (2) for counter-mixing to obtain a metastable solid arsenic precursor solution without large particle precipitates. C. Fluidized bed directional crystallization: The metastable solid arsenic precursor solution is continuously fed from the bottom or lower part into a vertical fluidized bed crystallizer (4) with pre-placed arsenic crystal seeds. The temperature, apparent flow rate of the bottom inlet liquid, and expansion rate of the seed bed are controlled within the vertical fluidized bed crystallizer (4) to reduce the supersaturated Fe in the metastable solid arsenic precursor solution. 3+ AsO4 3- Heterogeneous epitaxial growth occurs with stinky onion crystal seed as the core, and high crystallinity stinky onion solid arsenic slag is generated by in-situ co-precipitation, resulting in crystallization slurry discharged from the self-standing fluidized bed crystallizer (4). D. Solid-liquid separation: The crystallized slurry is fed into the solid-liquid separator (6) and copper-zinc rich filtrate and arsenic-fixing slag from stinky onion stone are obtained through solid-liquid separation.

6. The method for selective arsenic fixation and copper-zinc separation of arsenic-containing copper dust with microchannel homogeneous control according to claim 5, characterized in that: In step A, an oxidant is added to the oxidative leaching tank (1) to adjust the oxidation-reduction potential of the system to ORP=450mV~600mV; the oxidant is selected from any one of hydrogen peroxide, air, oxygen, and ozone; the arsenic-containing copper dust is high-arsenic dust produced by copper smelting, copper blowing, or copper electrolysis.

7. The method for selective arsenic fixation and copper-zinc separation of arsenic-containing copper dust with microchannel homogeneous control according to claim 5, characterized in that: In step B, the flow rate and volume of the multi-metal leachate and liquid neutralizer injected into the microchannel component are controlled to ensure that the liquid film mixing thickness in the microchannel component is between 10 μm and 500 μm, the mixing residence time is between 0.01 s and 0.5 s, and the instantaneous pH of the mixture is stable between 1.5 and 2.

5.

8. The method for selective arsenic fixation and copper-zinc separation of arsenic-containing copper dust with microchannel homogeneous control according to claim 5, characterized in that: The liquid neutralizing agent is one of sodium hydroxide solution, ammonia water, and lime milk, and the mass concentration of the liquid neutralizing agent is 80g / L to 120g / L; the counter-mixing in the microchannel assembly is T-type, Y-type, or cross-type coaxial counter-mixing.

9. The method for selective arsenic fixation and copper-zinc separation of arsenic-containing copper dust with microchannel homogeneous control according to claim 5, characterized in that: In step C, the temperature inside the vertical fluidized bed crystallizer (4) is 85℃~100℃, the apparent flow rate of the liquid entering from the bottom is 0.5cm / s~2.0cm / s, and the expansion rate of the seed bed is 120%~150%.

10. The method for selective arsenic fixation and copper-zinc separation of arsenic-containing copper dust with microchannel homogeneous control according to any one of claims 5 to 9, characterized in that: In step B, the two sets of microchannel components in the microchannel mixing reactor (3) alternately perform counter-flushing mixing and cleaning: one set of microchannel components is simultaneously injected with multi-metal leaching solution and liquid neutralizer for counter-flushing mixing; the other set of microchannel components is injected with 5g / L~10g / L dilute sulfuric acid through the acid supply component (8) for online backwashing to dissolve scale, and the cleaning waste liquid is returned to the oxidation leaching tank (1); while counter-flushing mixing and / or backwashing, the ultrasonic transducers (7) attached to the corresponding microchannel components are turned on, and the working frequency is 20kHz~40kHz, and the power density of the ultrasonic field is 0.1W / cm. 2 ~0.5W / cm 2 .

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