Comprehensive treatment method for hydrogen fluoride production solid waste
By implementing graded pretreatment, synergistic defluorination, and differentiated resource recovery of solid waste from hydrogen fluoride production, the problem of improper solid waste treatment during hydrogen fluoride production has been solved, achieving efficient separation and recovery, resource utilization of valuable elements, and environmental protection.
Patent Information
- Application Number
- CN202511538311.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2025-12-05
AI Technical Summary
Improper handling of solid waste generated during hydrogen fluoride production leads to environmental pollution and resource waste. Existing technologies have failed to effectively separate and recover valuable elements efficiently, and HF absorption efficiency is low and secondary pollution occurs.
The method employs a combination of mixed solid waste tiered pretreatment, synergistic defluorination treatment, and resource recycling, including crushing and grading, magnetic separation for impurity removal, primary acid leaching, secondary alkali regulation, resource recycling, and harmless treatment of spent catalysts. Efficient defluorination and resource recovery are achieved through chemical reactions and physical separation.
It has achieved efficient separation and recycling of valuable elements in solid waste, reduced environmental pollution risks, improved resource utilization and economic benefits, and formed a solid waste treatment system based on clean production and circular economy.
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Figure CN121060918A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of hazardous solid waste treatment, in particular to a comprehensive treatment method for hydrogen fluoride production solid waste. BACKGROUND
[0002] In the production process of hydrogen fluoride, a large amount of solid waste is generated, mainly including fluorogypsum, fluorine-containing waste residue and waste catalysts. These solid wastes not only occupy a large amount of land resources, but also contain high fluorine content and other harmful ingredients. If not properly treated, it will cause serious pollution to the environment. The traditional solid waste treatment methods mainly include landfill, simple stacking or partial recycling, but these methods have many shortcomings:
[0003] Direct landfill or stacking not only wastes land resources, but also causes fluorine ions to penetrate into the soil and groundwater, causing environmental pollution. In addition, heavy metals that may be contained in waste catalysts will also be washed into the environment with rainwater, increasing the ecological risk.
[0004] Although some enterprises try to recycle fluorogypsum and fluorine-containing waste residue through simple physical or chemical methods, such as for building materials or to prepare low-grade products, due to the lack of effective pretreatment and classification measures, it is often difficult to obtain high-purity useful components, limiting its application range and economic value.
[0005] HF tail gas in the production process of hydrogen fluoride is usually treated by alkali absorption method, but the HF absorption efficiency in the traditional process is not high, which is easy to cause secondary pollution, and the HF resource is not fully recovered, reducing the overall economic benefit.
[0006] The prior art has failed to effectively realize the efficient separation and recovery of valuable elements such as calcium and fluorine in solid waste, resulting in a large amount of valuable resources being wasted. SUMMARY
[0007] (I) Technical problems solved
[0008] In view of the deficiencies of the prior art, the present application provides a comprehensive treatment method for hydrogen fluoride production solid waste.
[0009] (II) Technical solutions
[0010] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a comprehensive treatment method for hydrogen fluoride production solid waste according to the present application, comprising the following steps:
[0011] Step 1: mixed solid waste classification pretreatment, the fluorogypsum, fluorine-containing waste residue and waste catalyst mixed solid waste generated in the production of hydrogen fluoride are crushed to a particle size of ≤10mm, and are classified by a double-layer vibrating screen, the upper layer is fluorine-containing waste residue, and the lower layer is a mixture of fluorogypsum and waste catalyst, and the lower layer mixture is magnetically selected to remove impurities;
[0012] Step 2: Synergistic defluorination process, primary acid leaching section, pour the lower mixture into an acid-resistant reaction kettle, add 5%-8% dilute sulfuric acid according to the liquid-solid ratio of 3:1, and react for 60-90 min. After primary acid leaching defluorination, the HF tail gas is absorbed by 10% ammonia water to generate ammonium fluoride; secondary alkali regulation section, add 5%-8% calcium hydroxide to the reaction liquid, adjust the pH to 6.0-7.0, and react for 40-60 min. After secondary alkali regulation defluorination, solid-liquid separation is performed to obtain filter residue A and filter liquor A;
[0013] Step 3: Resource quality-based recovery, wash and dry the filter residue A to obtain refined calcium sulfate; grind the upper layer of fluorine-containing waste residue to ≤0.1 mm, react with 10%-12% hydrochloric acid for 30-40 min, filter, wash, and dry to obtain fluorite powder; adjust the pH of the filter liquor A to 8.0-9.0 by adding ammonia water, filter the liquor, and combine it with the ammonium fluoride absorption liquid. Evaporate and concentrate to crystallize ammonium fluoride crystals;
[0014] Step 4: Harmless solidification of waste catalyst, mix the Al(OH)3 precipitate obtained by filtering in step 3 with cement, water, and 0.5%-1% phosphate, and maintain at room temperature for 7 days to form a solidified body. After detection, it is landfilled.
[0015] Preferably, the mass ratio of the mixed solid waste in step 1 is 70%-80% of fluorogypsum, 15%-20% of fluorine-containing waste residue, and 5%-10% of waste catalyst.
[0016] Further preferably, in step 2, the concentration of dilute sulfuric acid for primary acid leaching is adjusted according to the fluorine content of the mixed solid waste: when the fluorine content is >5%, the concentration is 7%-8%, and when the fluorine content is ≤5%, the concentration is 5%-6%; the purity of calcium hydroxide for secondary alkali regulation is ≥95%, and the reaction temperature is adjusted in real time according to the pH: when the pH is <6.0, the temperature is increased by 5-10°C.
[0017] Further preferably, in step 2, the HF tail gas absorption tower uses a packed tower, the absorption temperature is 25-30°C, and the ammonia water flow is automatically adjusted according to the HF concentration of the tail gas to ensure that the concentration of the ammonium fluoride solution is 20%-25%.
[0018] Preferably, in step 3, the filter residue A is washed with deionized water for 3 times (liquid-solid ratio 2:1), and the fluorine content of the washed filter residue is ≤0.1%; drying is performed using a rotary dryer at a temperature of 120-150°C, and the moisture content is controlled to be ≤5%.
[0019] Further preferably, in step 3, the fluorine-containing waste residue is ground using a ball mill for 30-40 min; the filter residue after hydrochloric acid reaction is washed with deionized water until the pH is 6.5-7.5, and the drying temperature is 100-120°C.
[0020] Preferably, in step 3, the filtrate A is adjusted to pH 8.0-9.0 by adding ammonia water to generate Al(OH)3 precipitate; and the concentrated condition is that the temperature is 80-85℃, the vacuum degree is -0.08MPa, the cooling crystallization temperature is 20-25℃, and the centrifugal speed is 3000r / min.
[0021] Preferably, in step 4, the phosphate is ammonium dihydrogen phosphate or di-ammonium hydrogen phosphate, and the cement is P.O42.5 ordinary portland cement; and the curing environment is that the temperature is 20-25℃, the relative humidity is ≥90%, and the heavy metal leaching concentration after curing is Pb≤0.05mg / L and As≤0.03mg / L.
[0022] Further preferably, the washing wastewater in steps 2-3 is combined with the filtration mother liquor and then reused in the primary acid leaching section.
[0023] (III) Beneficial effects
[0024] Compared with the prior art, the present application provides a comprehensive treatment method for hydrogen fluoride production solid waste, which has the following beneficial effects:
[0025] The present technical solution classifies and pretreats the mixed solid waste, crushes and classifies the fluorogypsum, fluorine-containing waste residue and waste catalyst, effectively separates different components, and lays a foundation for subsequent treatment. The magnetic separation further improves the purity of the material and reduces the influence of impurities on the subsequent process.
[0026] In the synergistic defluorination process, a two-stage chemical treatment method is used. In the primary acid leaching, dilute sulfuric acid is used to remove fluorine, and HF tail gas is absorbed by ammonia water to generate ammonium fluoride, achieving effective recycling of waste gas. In the secondary alkali regulation section, calcium hydroxide is added to adjust the pH value, further removing fluorine ions and ensuring that the fluorine content in the final filter residue A is reduced to a safe level. In addition, the acid concentration and reaction temperature are adjusted according to the fluorine content to optimize the defluorination effect and improve the resource utilization rate.
[0027] In the resource quality-based recycling link, the preparation of refined calcium sulfate, fluorite powder and ammonium fluoride crystals not only realizes efficient conversion of solid waste, but also produces high-value-added products. For example, the upper fluorine-containing waste residue is ground and treated with hydrochloric acid to obtain pure fluorite powder; the filtrate A is adjusted to pH value by adding ammonia water, and then evaporated and concentrated to crystallize to obtain ammonium fluoride crystals. The whole process fully embodies the concept of resource recycling.
[0028] The harmless solidification of waste catalyst is a highlight of the present technical solution. The Al(OH)3 precipitate is mixed with cement and phosphate to form a stable solidified body, and the heavy metal leaching concentration after curing is far below the environmental protection standard, which is suitable for safe landfill and avoids the risk of secondary pollution.
[0029] In addition, the design of recycling the washing wastewater and the filtering mother liquor to the primary acid leaching section greatly reduces the water resource consumption and the wastewater discharge, and reduces the overall operation cost. The technical scheme integrates the multi-processes such as the hierarchical pretreatment, the chemical defluorination, the resource recovery and the harmless treatment, and forms a complete solid waste treatment system, which is suitable for realizing the clean production and the circular economy for the hydrogen fluoride production enterprises. BRIEF DESCRIPTION OF DRAWINGS
[0030] Figure 1 It is a whole flow architecture schematic diagram of the present application;
[0031] Figure 2 It is a hierarchical pretreatment architecture schematic diagram of the mixed solid waste of the present application;
[0032] Figure 3 It is a primary acid leaching section architecture schematic diagram of the present application;
[0033] Figure 4 It is a secondary alkali regulation section and solid-liquid separation architecture schematic diagram of the present application;
[0034] Figure 5 It is a fluorite powder recovery architecture schematic diagram of the present application;
[0035] Figure 6 It is an ammonium fluoride crystal recovery architecture schematic diagram of the present application;
[0036] Figure 7 It is a waste catalyst harmless solidification architecture schematic diagram of the present application;
[0037] Figure 8 It is a wastewater recycling architecture schematic diagram of the present application; DETAILED DESCRIPTION
[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.
[0039] Please refer to Figures 1-8 The present application is a hydrogen fluoride production solid waste comprehensive treatment method, which comprises the following steps:
[0040] Step 1: hierarchical pretreatment of mixed solid waste, crushing the fluorogypsum, fluorine-containing waste residue and waste catalyst mixed solid waste generated in the production of hydrogen fluoride to a particle size of less than or equal to 10 mm, grading through a double-layer vibrating screen, the upper layer being the fluorine-containing waste residue and the lower layer being the mixture of fluorogypsum and waste catalyst, and magnetically selecting the lower layer mixture to remove impurities;
[0041] Step 2: Synergistic defluorination treatment, primary acid leaching section, pour the lower mixture into an acid-resistant reaction kettle, add 5%-8% dilute sulfuric acid according to the liquid-solid ratio of 3:1, and react for 60-90 min. After primary acid leaching defluorination, the HF tail gas is absorbed by 10% ammonia water to generate ammonium fluoride; secondary alkali control section, add 5%-8% calcium hydroxide to the reaction liquid, adjust the pH to 6.0-7.0, and react for 40-60 min. After secondary alkali control defluorination, solid-liquid separation is performed to obtain filter residue A and filter liquor A;
[0042] Step 3: Resource quality-based recovery, wash and dry the filter residue A to obtain refined calcium sulfate; grind the upper layer fluorine-containing waste residue to ≤0.1 mm, react with 10%-12% hydrochloric acid for 30-40 min, filter, wash, and dry to obtain fluorite powder; adjust the pH of the filter liquor A to 8.0-9.0 by adding ammonia water, filter the liquor, and combine it with the ammonium fluoride absorption liquid. Evaporate and concentrate to crystallize ammonium fluoride crystals;
[0043] Step 4: Harmless solidification of waste catalyst, mix the Al(OH)3 precipitate obtained by filtering in step 3 with cement, water, and 0.5%-1% phosphate, and maintain at room temperature for 7 days to form a solidified body. After detection, it is landfilled.
[0044] The technical solution separates solid waste of different particle sizes and different components through hierarchical pretreatment, such as separately recovering fluorine-containing waste residue coarse particles for fluorite, and synergistically defluorinating fluorogypsum and waste catalyst fine particles to avoid component interference. Based on the existence form of fluorine, such as free fluorine, lattice-bound fluorine, and compound-bound fluorine, the hierarchical reaction of primary acid leaching to remove free fluorine and secondary alkali control to remove lattice fluorine is adopted to directionally destroy the combination structure of fluorine, achieving a defluorination rate of ≥99%. The physical and chemical property differences of calcium sulfate, fluorite, and ammonium fluoride are utilized for quality-based recovery through washing, drying, and crystallization, achieving a resource recovery rate of ≥95%. Finally, the heavy metals in the waste catalyst are physically wrapped and chemically fixed by the cement and phosphate system, ensuring that the leaching concentration of the solidified body meets the standard, and realizing environmental protection and resource recycling throughout the whole process.
[0045] Particle size classification and component separation
[0046] After crushing the mixed solid waste, such as 70%-80% fluorogypsum, 15%-20% fluorine-containing waste residue, and 5%-10% waste catalyst, to ≤10 mm, the particle size difference and density difference are utilized to achieve classification through a double-layer vibrating screen: the fluorine-containing waste residue, which is larger than the screen mesh size, remains in the upper layer, and the fluorogypsum and waste catalyst, which are smaller than the screen mesh size, fall to the lower layer. This design is based on the physical property differences of the three types of solid waste: the fluorine-containing waste residue is mostly block-shaped impurities, the fluorogypsum is fine powder, and the waste catalyst is granular, which preliminarily realizes component separation and lays a foundation for subsequent targeted treatment.
[0047] Principle of magnetic separation
[0048] The lower fluorogypsum and waste catalyst mixture passes through a magnetic separation device, and the ferromagnetic impurities, such as metal scraps, in the waste catalyst are adsorbed and separated under the action of a magnetic field, so as to avoid the influence of the impurities on the reaction efficiency and product purity in the subsequent acid leaching process and ensure the stability of the subsequent treatment system.
[0049] Primary acid leaching defluorination
[0050] Chemical mechanism: 5%-8% dilute sulfuric acid is added to the acid-resistant reaction kettle, for example, with a liquid-solid ratio of 3:1, the sulfuric acid reacts with the fluoride, such as CaF2, in the fluorogypsum: CaF2+H2SO4→CaSO4+2HF↑, and the soluble fluoride in the waste catalyst also reacts with the sulfuric acid to release HF gas. By controlling the concentration of sulfuric acid, when the fluorine content is >5%, the concentration of sulfuric acid is 7%-8%, and when the fluorine content is ≤5%, the concentration of sulfuric acid is 5%-6%, efficient conversion of the fluoride and removal of HF are achieved, and the reaction time of 60-90 min ensures sufficient reaction.
[0051] Tail gas absorption principle: HF tail gas is introduced into a packed tower and absorbed by 10% ammonia water, and the reaction: HF+NH3·H2O→NH4F+H2O occurs. The packing in the packed tower, such as polypropylene corrugated packing, increases the gas-liquid contact area, the absorption temperature is controlled at 25-30℃ to avoid rapid volatilization of ammonia water, and the ammonia water flow is automatically adjusted according to the HF concentration of the tail gas to ensure that the concentration of ammonium fluoride solution is stable at 20%-25%, and the resource recovery of HF is achieved.
[0052] Secondary alkali regulation defluorination
[0053] pH adjustment and fluorine fixation: calcium hydroxide with a purity of ≥95% is added to the primary acid leaching reaction solution, which on the one hand adjusts the pH to 6.0-7.0 to neutralize excess sulfuric acid, and on the other hand, Ca 2+ reacts with the residual F- in the solution to form insoluble CaF2 precipitate, further reducing the fluorine content.
[0054] Temperature synergistic regulation: when the pH is <6.0, the temperature is increased by 5-10℃, such as from room temperature to 30-35℃, to accelerate the dissolution of calcium hydroxide and the generation rate of CaF2 precipitate, ensure that the pH is stable in the target range, and improve the defluorination efficiency.
[0055] Solid-liquid separation: filtration, such as plate and frame filter press, is used to separate the filter residue A, mainly CaSO4, and the filtrate A containing Al 3 +, a small amount of F-, etc., to achieve component separation of the solid-liquid system.
[0056] Resource fractionation recovery principle
[0057] Recovery of refined calcium sulfate and treatment of filter residue A
[0058] Washing to remove fluorine: the filter residue A is washed with deionized water for 3 times, liquid-solid ratio 2:1, using the dissolution of water to remove the soluble fluoride attached to the surface of CaSO4, to ensure that the fluorine content of the filter residue after washing is ≤0.1%, to avoid the influence of fluorine residue on product quality.
[0059] Drying and shaping: using a rotary dryer, drying at a temperature of 120-150℃, removing water in the filter residue through heat conduction and hot air convection, controlling the moisture content to be ≤5%, to obtain refined calcium sulfate with high purity and good stability, which can be used in the fields of building gypsum, putty powder, etc.
[0060] Fluorite powder recovery, upper layer fluorine-containing waste residue treatment
[0061] Grinding and refining: the upper layer fluorine-containing waste residue is ground by a ball mill for 30-40 min to a particle size of ≤0.1 mm, increasing the specific surface area to provide sufficient contact sites for subsequent hydrochloric acid reaction.
[0062] Acid-soluble impurity removal and purification: adding 10%-12% hydrochloric acid for reaction for 30-40 min, the hydrochloric acid reacts with impurity metal oxides in the waste residue, such as Fe2O3 and Al2O3, to generate soluble salts, such as FeCl3 and AlCl3, while the main component CaF2 does not react with hydrochloric acid; after filtration, the filter residue is washed with deionized water until the pH is 6.5-7.5, to remove residual hydrochloric acid and soluble salts, and after drying at 100-120℃, high-purity fluorite powder is obtained, with a CaF2 content of ≥95%, which can be used as raw material for hydrogen fluoride production.
[0063] Ammonium fluoride recovery, filtrate treatment
[0064] Al(OH)3 precipitation separation: adding ammonia water to the filtrate A to adjust the pH to 8.0-9.0, Al 3+ in the solution - reacts with OH + to form Al(OH)3 precipitate, which is separated by filtration, and a filtrate containing NH4 - and F .
[0065] Evaporation, concentration and crystallization: combining the above filtrate with the ammonium fluoride solution obtained by absorbing HF tail gas, evaporating and concentrating under the conditions of 80-85℃ and vacuum degree-0.08 MPa, to reduce the boiling point of the solution in a vacuum environment, avoid decomposition of ammonium fluoride, and remove excess water; then cooling and crystallizing at 20-25℃, to take advantage of the property that the solubility of ammonium fluoride decreases with decreasing temperature to precipitate crystals; finally, centrifuging at a speed of 3000 r / min to obtain ammonium fluoride crystals, which can be used as agricultural fertilizer, industrial etchant, etc.
[0066] Harmless solidification principle of waste catalyst
[0067] Gelation mechanism: Al(OH)3precipitate is mixed with P.O42.5 ordinary Portland cement, water and 0.5%-1% phosphate, cement hydration generates calcium silicate hydrate (C-S-H) gel, Al(OH)3reacts with phosphate to generate aluminum phosphate salt such as AlPO4, both of which form a dense solidified body structure to encapsulate and immobilize heavy metals such as Pb and As in the spent catalyst, preventing their leaching.
[0068] Maintenance and stability control: maintenance at a temperature of 20-25℃ and a relative humidity of ≥90% for 7 days to ensure complete hydration of the cement and complete reaction of the aluminum phosphate salt, forming a solidified body with high strength and good stability; tests show that the leaching concentration of heavy metals in the solidified body is Pb≤0.05mg / L and As≤0.03mg / L, meeting the requirements of the Hazardous Waste Landfill Pollution Control Standard (GB18598-2019) and being safe for landfill.
[0069] Wastewater recycling principle
[0070] The washing wastewater in steps 2-3, such as filter residue A washing water and fluorite powder washing water, is combined with the filter mother liquor, such as the centrifugal mother liquor of crystallization, and is used as a reaction liquid supplement in the first-stage acid leaching section due to the presence of unreacted sulfuric acid, hydrochloric acid and soluble fluorides, thereby reducing the amount of fresh water used, improving the utilization rate of acid and fluorides, reducing wastewater discharge and realizing a circular economy mode of waste treatment with waste.
[0071] Detailed work flow
[0072] Stage 1: Grading pretreatment of mixed solid waste
[0073] Crushing treatment: The mixed solid waste generated in hydrogen fluoride production, such as fluorogypsum 70%-80%, fluorine-containing waste residue 15%-20% and spent catalyst 5%-10%, is fed into a jaw crusher, such as a PEX150×750 type, and crushed to a particle size of ≤10mm to ensure the efficiency of subsequent classification.
[0074] Double-layer vibrating screen classification: The crushed solid waste is fed into a double-layer vibrating screen, such as a ZS1000×2000 type, with a screen aperture of 10mm on the upper layer and a screen aperture of 5mm on the lower layer. The upper layer retains fluorine-containing waste residue with a particle size of >10mm, and the lower layer collects a mixture of fluorogypsum and spent catalyst with a particle size of ≤10mm.
[0075] Magnetic separation of impurities: The lower layer mixture is fed into a permanent magnet cylinder type magnetic separator, such as a CTB1018 type, with a magnetic field strength of 12000Gs, to remove ferromagnetic impurities therefrom, obtaining a purified mixture of fluorogypsum and spent catalyst for standby use.
[0076] Stage 2: Synergistic defluorination treatment
[0077] Primary acid leaching reaction: the purified mixture is put into an acid-resistant reaction kettle, such as a 5000L enamel reaction kettle, model F, and dilute sulfuric acid is added according to a liquid-solid ratio of 3:1, and the concentration is adjusted according to the fluorine content: when the fluorine content is >5%, the dilute sulfuric acid is 7%-8%, and when the fluorine content is ≤5%, the dilute sulfuric acid is 5%-6%, the stirring speed is 300r / min, the reaction time is 60-90min, and the generated HF tail gas is introduced into a packed tower through a pipeline.
[0078] HF tail gas absorption: a packed tower, such as a DN800 type polypropylene packed tower, is filled with 50mm polypropylene corrugated packing, 10% ammonia water is introduced into the tower, the absorption temperature is controlled at 25-30℃, the tail gas concentration is monitored in real time by an online HF concentration detector, such as a GHF-3000 type, the ammonia water flow is automatically adjusted, such as by an electromagnetic flowmeter, to ensure that the outlet HF concentration is ≤10mg / m 3 , the absorption liquid is 20%-25% ammonium fluoride solution, and the collection is ready for use.
[0079] Secondary alkali regulation reaction: pure calcium hydroxide with a purity of ≥95% is added to the acid leaching reaction liquid, a pH online monitor, such as a PHS-3C type, is turned on, when the pH is <6.0, the temperature is raised by 5-10℃ through a heating jacket, and stirring is carried out for 40-60min until the pH is stable at 6.0-7.0.
[0080] Solid-liquid separation: the reaction liquid is sent into a plate and frame filter press, such as an XMYZ100 / 1000-30U type, to obtain filter residue A, mainly CaSO4, and filter liquid A containing Al 3 +, F-, etc., and the filter liquid A is collected into a storage tank.
[0081] Stage 3: resource quality-based recovery
[0082] Calcium sulfate preparation:
[0083] The filter residue A is sent into a washing tank, washed with deionized water according to a liquid-solid ratio of 2:1 for 3 times, filtered after stirring for 30min each time, and the fluorine content of the filter residue after washing is ≤0.1%.
[0084] The filter residue after washing is sent into a rotary dryer, such as a Φ1.2×12m type, the hot air temperature is 120-150℃, and the product, refined calcium sulfate, is obtained after drying to a water content of ≤5% and packaging into a warehouse.
[0085] Fluorite powder preparation:
[0086] The upper layer of fluorine-containing waste residue is sent into a ball mill, such as an MQG2100×4500 type, with a steel ball filling rate of 40%, and ground for 30-40min to a particle size of ≤0.1mm.
[0087] The ground waste residue is put into a reaction tank, 10%-12% hydrochloric acid is added according to a liquid-solid ratio of 4:1, stirred for 30-40min, and filtered to obtain filter residue.
[0088] The filter residue is washed with deionized water to pH 6.5-7.5, and is fed into a compartment dryer, such as a CT-C type, at a temperature of 100-120℃ to dry, to obtain fluorite powder product, ready for use.
[0089] Preparation of ammonium fluoride:
[0090] Ammonia water is added dropwise to the filtrate A storage tank to adjust the pH to 8.0-9.0, and stirring is performed for 30 min to generate Al(OH)3precipitate, which is separated by filtration to obtain Al(OH)3precipitate and filtrate;
[0091] The filtrate is combined with the ammonium fluoride solution obtained by absorbing HF tail gas, and is fed into a double-effect evaporation concentrator, such as a MVR2000 type, at a temperature of 80-85℃ and a vacuum degree of -0.08 MPa, to concentrate to a solid content of 30%-35%;
[0092] The concentrated solution is fed into a cooling crystallizer, such as an OSLO type, at a temperature of 20-25℃, and is crystallized for 4 h, and is then fed into a horizontal screw discharge centrifuge, such as a LW450×1800 type, at a rotation speed of 3000 r / min to separate, to obtain ammonium fluoride crystals, which are dried by a fluidized bed dryer, such as an FG120 type, and are then packaged.
[0093] Stage 4: harmless solidification of waste catalyst
[0094] Preparation of solidification mixture: Al(OH)3precipitate, P.O42.5 ordinary portland cement, and deionized water are mixed at a mass ratio of 1:3:1, 0.5%-1% of ammonium dihydrogen phosphate or diammonium hydrogen phosphate is added, and stirring is performed in a forced stirrer, such as a JS500 type, for 15 min to form a uniform solidification slurry.
[0095] Molding and curing: the solidification slurry is poured into a mold, such as a mold with a size of 50 mm×50 mm×50 mm, is compacted by vibration, and is then placed in a curing room at a temperature of 20-25℃ and a relative humidity of ≥90% for curing for 7 days.
[0096] Detection and landfill: after curing, the sample is taken, the heavy metal leaching concentration is detected according to the “Solid Waste Leaching Toxicity Leaching Method-Sulfuric Acid and Nitric Acid Method” (HJ / T299-2007), if Pb≤0.05 mg / L and As≤0.03 mg / L, it is determined to be qualified, and is sent to a hazardous waste landfill site for safe landfill.
[0097] Stage 5: wastewater recycling
[0098] The washing wastewater of filter residue A in step 2, the washing wastewater of fluorite powder in step 3, and the centrifugal mother liquor of ammonium fluoride crystallization are collected into a wastewater conditioning tank, are filtered to remove suspended solids by a quartz sand filter, such as a Φ800 type, and are then pumped to a dilute sulfuric acid preparation tank in a first-stage acid leaching section as reaction liquid supplement, to realize wastewater recycling.
[0099] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to the details of the embodiments described, since numerous changes, modifications, substitutions and variations can be made thereto without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.
Claims
1. A comprehensive treatment method for hydrogen fluoride production solid waste, characterized by, The method comprises the following steps: Step 1: mixed solid waste grading pretreatment, fluorogypsum, fluorine-containing waste residue, waste catalyst mixed solid waste generated in hydrogen fluoride production are crushed to a particle size of less than or equal to 10 mm, and are classified by a double-layer vibrating screen, the upper layer is fluorine-containing waste residue, and the lower layer is a mixture of fluorogypsum and waste catalyst, and the mixture in the lower layer is subjected to magnetic separation to remove impurities; Step 2: cooperative defluorination treatment, in a first-stage acid leaching section, the mixture in the lower layer is put into an acid-resistant reaction kettle, 5%-8% dilute sulfuric acid is added according to a liquid-solid ratio of 3:1, and reaction is performed for 60-90 min, after defluorination by the first-stage acid leaching, HF tail gas is absorbed by 10% ammonia water to generate ammonium fluoride; in a second-stage alkali regulation section, calcium hydroxide with a solid waste mass of 5%-8% is added to the reaction liquid, the pH is adjusted to 6.0-7.0, and reaction is performed for 40-60 min, after defluorination by the second-stage alkali regulation, solid-liquid separation is performed to obtain filter residue A and filter liquor A; Step 3: resource grading recovery, the filter residue A is washed and dried to obtain refined calcium sulfate; the upper layer fluorine-containing waste residue is ground to a particle size of less than or equal to 0.1 mm, reacted with 10%-12% hydrochloric acid for 30-40 min, washed, dried and filtered to obtain fluorite powder; the filter liquor A is adjusted to a pH of 8.0-9.0 by adding ammonia water, and after filtration, the filter liquor is combined with the ammonium fluoride absorption liquid, and ammonium fluoride crystals are obtained by evaporation, concentration and crystallization; Step 4: waste catalyst harmless solidification, Al(OH)3 precipitate obtained by filtration in step 3 is mixed with cement, water and 0.5%-1% phosphate, and cured at room temperature for 7 days to form a solidified body, which is landfilled after detection.
2. The hydrogen fluoride production solid waste comprehensive treatment method according to claim 1, characterized in that, In step 1, the mass ratio of the mixed solid waste is 70%-80% fluorogypsum, 15%-20% fluorine-containing waste residue and 5%-10% waste catalyst.
3. The method according to claim 1, wherein, In step 2, the concentration of the dilute sulfuric acid for the first-stage acid leaching is adjusted according to the fluorine content of the mixed solid waste: when the fluorine content is greater than 5%, the concentration is 7%-8%, and when the fluorine content is less than or equal to 5%, the concentration is 5%-6%; the purity of the calcium hydroxide for the second-stage alkali regulation is greater than or equal to 95%, and the reaction temperature is adjusted in real time according to the pH: when the pH is less than 6.0, the temperature is increased by 5-10 ℃.
4. The method according to claim 1, wherein In step 2, the HF tail gas absorption tower is a packed tower, the absorption temperature is 25-30 ℃, and the ammonia water flow is automatically adjusted according to the HF concentration of the tail gas to ensure that the concentration of the ammonium fluoride solution is 20%-25%.
5. The method according to claim 1, wherein In step 3, the filter residue A is washed with deionized water for 3 times (liquid-solid ratio 2:1), and the fluorine content of the filter residue after washing is less than or equal to 0.1%; the drying is performed by using a rotary dryer, the temperature is 120-150 ℃, and the water content is controlled to be less than or equal to 5%.
6. The hydrogen fluoride production solid waste comprehensive treatment method according to claim 1, characterized in that, In step 3, the fluorine-containing waste residue is ground by using a ball mill, and the grinding time is 30-40 min; the filter residue after the hydrochloric acid reaction is washed with deionized water until the pH is 6.5-7.5, and the drying temperature is 100-120 ℃.
7. The method according to claim 1, wherein In step 3, the filter liquor A is adjusted to a pH of 8.0-9.0 by adding ammonia water to generate Al(OH)3 precipitate; the evaporation and concentration conditions of the combined liquid are a temperature of 80-85 ℃, a vacuum degree of-0.08 MPa, a cooling crystallization temperature of 20-25 ℃ and a centrifugal speed of 3000 r / min.
8. The method according to claim 1, wherein, The phosphate in step 4 is ammonium dihydrogen phosphate or di-ammonium hydrogen phosphate, the cement is P.O 42.5 ordinary Portland cement; the curing environment of the solidified body is temperature 20-25℃, relative humidity ≥90%, and the heavy metal leaching concentration after curing is Pb ≤0.05mg / L, As ≤0.03mg / L.
9. The method according to claim 1, wherein, The washing wastewater in steps 2-3 is combined with the filtration mother liquor and then reused in the primary acid leaching section.