Hydrochloric acid pickling waste liquid resource treatment process based on hypergravity neutralization and ammonia closed loop

Abstract

The application discloses a hydrochloric acid pickling waste liquid resource treatment process based on supergravity neutralization and ammonia closed loop, relates to the technical field of hydrochloric acid pickling waste liquid recovery treatment, and comprises the steps of purification and impurity removal, supergravity neutralization, solid-liquid separation, ammonia recovery and product preparation, etc. The supergravity reaction device is used to realize high-speed and high-efficiency neutralization of the waste liquid and ammonia gas, and through the reaction of calcium oxide and the neutralization product, i.e. ammonium chloride, ammonia gas is recovered under negative pressure and is used in the neutralization step again, forming an ammonia closed loop cycle. Meanwhile, the valuable components in the waste liquid are converted into high-purity iron red products and calcium chloride products in the whole process, and high-quality purified water is recovered. The application solves the problems of high energy consumption, low efficiency, insufficient resource recovery and secondary pollution caused by the traditional hydrochloric acid pickling waste liquid treatment method, realizes clean and efficient disposal of the waste liquid and full-amount high-value recovery of resources, and has both economic benefits and environmental benefits.

Description

Technical Field

[0001] This invention relates to the field of hydrochloric acid pickling waste liquid recycling and treatment technology, specifically to a hydrochloric acid pickling waste liquid resource utilization treatment process based on supergravity neutralization and ammonia closed-loop. Background Technology

[0002] Hydrochloric acid pickling is an indispensable surface treatment process in the processing of steel and metal products, used to remove iron oxide scale and rust from the surface of steel. This process generates a large amount of complex acidic waste liquid, mainly composed of ferrous chloride and free hydrochloric acid, and containing small amounts of heavy metal ions and organic additives. This type of waste liquid is highly acidic and saline; if discharged directly without proper treatment, it will cause serious pollution to water bodies and soil, and also represents a huge waste of valuable resources such as iron and chlorine.

[0003] Currently, the industry mainly classifies hydrochloric acid pickling waste liquid treatment methods into two categories: disposal methods, such as the traditional neutralization precipitation method; and recovery methods, such as the high-temperature roasting method. The neutralization precipitation method typically uses lime or caustic soda for neutralization, generating a large amount of ferric hydroxide sludge. Although this method is simple to operate, it has the following significant drawbacks: the generated sludge is bulky, has a high water content, is difficult to dewater, and has high subsequent disposal costs; the iron resources in the sludge have extremely low value and are essentially wasted; chloride ions enter the water body in the form of calcium chloride or sodium chloride, failing to be recovered, and increasing the salinity of the effluent. The high-temperature roasting method involves spray-roasting the waste liquid at high temperatures (600-800℃) to decompose ferrous chloride and hydrochloric acid, recovering iron oxide powder and hydrochloric acid gas respectively. While this method can recover some resources, its drawbacks are more prominent: it consumes extremely high energy, requires evaporating most of the water in the waste liquid and maintaining a high temperature, and its operating costs make it difficult to popularize; the equipment investment is huge, and the high temperature and high acid environment places stringent requirements on the equipment materials, resulting in high maintenance costs; the process is complex, requires high operational skills, and is prone to coking and clogging when treating waste liquid containing organic matter; in addition, there are still problems with exhaust emissions and energy consumption that are not environmentally friendly. Summary of the Invention

[0004] The purpose of this invention is to provide a resource recovery treatment process for hydrochloric acid pickling waste liquid based on supergravity neutralization and ammonia closed-loop, so as to solve the problem that existing technologies for treating hydrochloric acid pickling waste liquid generally face the difficulty of balancing treatment efficiency, resource recovery rate, operating cost and environmental performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a resource recovery treatment process for hydrochloric acid pickling waste liquid based on supergravity neutralization and ammonia closed-loop, comprising the following steps:

[0006] S1. Purification and impurity removal: Pretreatment of hydrochloric acid pickling waste liquid to remove suspended solids and heavy metal impurities;

[0007] S2, Ultragravity Neutralization: The purified waste liquid is pumped into the ultragravity neutralization reactor, and ammonia gas is introduced into it to neutralize and precipitate the hydrochloric acid and ferrous chloride in the waste liquid, generating a mixed slurry of ferrous hydroxide and ammonium chloride.

[0008] S3. Solid-liquid separation and preparation of iron red product: The mixed slurry is fed into a closed filter press for solid-liquid separation to obtain a filter cake containing ferrous hydroxide and a filtrate containing ammonium chloride. The filter cake is dried and oxidized to obtain iron red product.

[0009] S4. Ammonia Recovery and Conversion: The ammonium chloride-containing filtrate is introduced into the calcium ammonium reactor, and calcium oxide is added thereto. The reaction is carried out under stirring and slight negative pressure conditions. The ammonia gas released by the reaction is extracted and reused in the supergravity neutralization step.

[0010] S5. Preparation of calcium chloride product: The solution obtained after step S4 is purified and concentrated to obtain calcium chloride product and purified water, respectively.

[0011] Furthermore, the hypergravity neutralization reactor is configured to generate a hypergravity field, the hypergravity field providing a centrifugal acceleration that is 100 to 1000 times the gravitational acceleration; the residence time of the material in the hypergravity neutralization reactor is 10 to 100 milliseconds.

[0012] Furthermore, the ammonium calcium reactor is configured as a closed stirred reaction vessel, with an exhaust system connected to the top to maintain a slightly negative pressure environment, and is equipped with a feeding device for solid calcium oxide.

[0013] Furthermore, the gas extraction system includes a vacuum pump and a gas-liquid separator disposed on the exhaust pipe of the calcium ammonium reactor, the gas-liquid separator being used to capture and recirculate liquid droplets entrained by the gas.

[0014] Furthermore, a closed-loop process circulation of ammonia medium is formed between step S2 and step S4, and the ammonia gas is recycled between the hypergravity neutralization reactor and the calcium ammonium reactor.

[0015] Furthermore, the filter press used in step S3 is a closed structure to prevent the ammonia odor from escaping and to maintain the material balance of the system.

[0016] Furthermore, the preparation of the iron oxide red product includes feeding the filter cake from the filter press into a drying device via a conveying device. The drying device is configured to heat and dry the filter cake under aerobic conditions, thereby converting ferrous hydroxide into iron oxide red.

[0017] Compared with existing technologies, the hydrochloric acid pickling wastewater resource recovery process based on supergravity neutralization and ammonia closed-loop treatment provided by this invention has the following beneficial effects:

[0018] 1. This invention, through systematic chemical reactions and separation steps, converts iron in waste liquid into high-value-added iron oxide red products and chlorine into widely used calcium chloride products. At the same time, it recovers purified water with a water quality close to the standard of distilled water, realizing the full-scale and high-value utilization of all major components in waste liquid and creating direct economic benefits.

[0019] 2. This invention utilizes the self-circulation of ammonia gas, a neutralizing agent, within the system. The main raw material consumed is calcium oxide (quicklime), which is relatively inexpensive. Compared to the traditional neutralization method, which requires the continuous purchase of large amounts of alkali agents, or the roasting method, which consumes huge amounts of fuel, the operating costs (especially the costs of reagents and energy) are significantly reduced. Water reuse also saves on fresh water fees and wastewater discharge fees.

[0020] 3. This invention uses a supergravity neutralization reactor as the core neutralization unit and takes advantage of its strong mass transfer capability under supergravity field to shorten the reaction time from several hours in traditional methods to milliseconds. This makes the reactor small in size and the whole treatment system occupy a small area, making it suitable for new construction or renovation in places with limited space in the factory area.

[0021] 4. This invention uses a wet closed-loop process under mild conditions throughout the entire process, without high-temperature pyrolysis, thus avoiding energy waste and toxic waste gas generated by the pyrolysis of organic matter. The use of closed equipment effectively controls the volatilization of substances such as ammonia, and the final solid products are all valuable products. Only a small amount of waste residue containing heavy metals is generated in the front-end purification and impurity removal stage. Compared with the traditional neutralization method that generates a large amount of iron sludge, this reduces the production of hazardous waste.

[0022] 5. This invention can precisely adjust key parameters such as calcium oxide dosage and reaction negative pressure through automated control, ensuring that pickling waste liquid of different batches and concentrations can be treated stably and efficiently. It can be designed as a continuous operation mode to match the continuous production pickling line. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0024] Figure 1 This is a schematic diagram of the process system of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] As attached Figure 1As shown

[0027] This invention provides a resource recovery process for hydrochloric acid pickling waste liquid based on neutralization by supergravity and ammonia closed-loop, comprising the following steps:

[0028] S1, Purification and Impurity Removal

[0029] The purpose of this step is to remove mechanical impurities and heavy metal ions from the original pickling waste liquid, providing a clean feed for the subsequent main reaction. Specifically, the collected hydrochloric acid pickling waste liquid is transported to a pretreatment tank, where the pH value is adjusted to the range of 4.0-5.0 by adding alkali solution. , , Heavy metal ions form hydroxide precipitates. Subsequently, a flocculant (such as polyaluminum chloride or polyacrylamide) is added to coagulate the fine suspended solids and precipitates. Solid-liquid separation is then achieved through filtration (such as plate and frame filtration or multi-media filtration) to obtain a clarified pretreated liquid. The small amount of heavy metal-containing sludge generated in this step must be properly disposed of, while the clarified liquid is pumped into an intermediate storage tank for later use. This pretreatment effectively prevents impurities from interfering with subsequent main reactions and affecting the purity of the final product.

[0030] S2, Supergravity Neutralization

[0031] This step utilizes centrifugal technology to achieve instantaneous and efficient neutralization of the waste liquid and iron precipitation. The clarified waste liquid obtained from S1 is continuously fed into the centrifugal neutralization reactor via a feed pump. This reactor is a rotating packed bed structure, and its high-speed rotating packing can generate a centrifugal force field hundreds to thousands of times stronger than gravity. Simultaneously, ammonia gas from the system circulation is introduced into the reactor.

[0032] Under the influence of a hypergravity field, the waste liquid is torn into micron- to nanometer-sized liquid films or droplets with a large specific surface area, thereby revolutionarily enhancing the mass transfer process between the gas and liquid phases. Ammonia gas rapidly dissolves and diffuses, reacting with the acidic components in the waste liquid as follows:

[0033]

[0034]

[0035] The residence time of the material in the reactor is significantly reduced to 10-100 milliseconds, yet neutralization and precipitation efficiency of over 95% can be achieved within such a short time. The reactor outlet yields ferrous hydroxide. Solid particles and ammonium chloride ( This equipment produces a slurry with a uniformly mixed solution. It boasts the significant advantages of small size and high processing capacity.

[0036] S3. Solid-liquid separation and preparation of iron oxide red products

[0037] The purpose of this step is to separate the solid phase and produce ferrous products. The mixed slurry generated in S2 is pumped into a closed plate and frame filter press. The filter press is designed with sealed structures in its feeding, pressing, drying, and unloading stages to effectively prevent the escape of ammonia-containing gas, maintain system material balance, and ensure environmental friendliness. After filtration, a ferrous hydroxide filter cake with a moisture content of approximately 40%-60% and a clear ammonium chloride filtrate are obtained.

[0038] The filter cake is fed into a drying and oxidation unit (e.g., a rotary kiln or belt dryer) via a closed conveyor (such as a screw conveyor). This unit heats the filter cake to 120-250°C under aerobic conditions. During this process, ferrous hydroxide undergoes oxidation and dehydration, and the reaction pathway can be represented as follows:

[0039]

[0040]

[0041] By controlling the temperature, atmosphere, and time, red iron oxide with a purity of over 98% can be obtained. The product (i.e., iron oxide red) has a hue and performance that meet the standards of industrial pigments or material additives.

[0042] S4, Ammonia Recovery and Conversion

[0043] The purpose of this step is to recover ammonia and convert it into ammonium chloride, completing the ammonia closed-loop cycle. The ammonium chloride filtrate produced in S3 is transported to the calcium ammonium reactor. This reactor is a closed container equipped with a stirrer and a jacket. Under continuous stirring, solid calcium oxide is added to the reaction solution through a precision feeding device (such as a loss-in-weight feeder or a screw feeder). The molar ratio of calcium oxide added is based on the theoretical value of 1:1 for reaction with ammonium chloride, and it is controlled to be in slight excess of 0.1-2% to ensure complete reaction and avoid ammonia residue.

[0044] Inside the reactor, the following reactions occur sequentially:

[0045]

[0046]

[0047] To efficiently remove ammonia, a vacuum pump and gas-liquid separator are connected to the top of the reactor. This system maintains a slightly negative pressure environment of -1 kPa to -5 kPa inside the reactor and promptly extracts the ammonia generated in the reaction along with water vapor. The gas-liquid separator captures and recirculates any liquid droplets entrained in the gas, while the dried ammonia is transported to a buffer recovery unit. The recovered ammonia is ultimately reintroduced into the gravity neutralization reactor in step S2 for reuse, requiring only external replenishment during system startup or to compensate for minor losses, thus achieving a closed-loop circulation of the ammonia medium within the process.

[0048] S5, Preparation of calcium chloride products

[0049] This step completes the preparation of the final salt product and the recovery of water resources. The solution obtained after the S4 reaction, whose main component is calcium chloride, is first subjected to a precision filtration (such as a bag filter) to remove any trace amounts of suspended solids. Subsequently, the filtrate enters a concentration and crystallization system (such as a multi-effect evaporator or an MVR evaporator) for evaporation and concentration.

[0050] Through evaporation, a large amount of water is removed from the solution, producing high-concentration calcium chloride solution or further solid calcium chloride products (such as calcium chloride dihydrate) according to market demand. Testing shows that the purity of the obtained calcium chloride product can reach over 98%. The condensate produced during the evaporation process is clean, with low conductivity, approaching distilled water standards. It can be reused as high-quality purified water in production processes or for other uses, reducing fresh water consumption and wastewater discharge.

[0051] System Integration and Operation

[0052] The steps S1 to S5 described above are integrated into a continuous closed-loop treatment system via pipelines, pumps, valves, and a control system. The system uses calcium oxide as the main consumable feedstock, repeatedly utilizing its neutralization function through a built-in ammonia cycle. This process converts iron and chlorine elements in the waste liquid into iron oxide red and calcium chloride products, respectively, and recovers purified water. The entire process operates under mild conditions, eliminating the need for high-temperature pyrolysis, thus avoiding secondary pollution and achieving complete resource recovery and near-zero discharge of hydrochloric acid pickling waste liquid. The automated control system allows for precise adjustment of key parameters such as feed flow rate, calcium oxide dosage, reaction negative pressure, and drying temperature, ensuring stable and efficient treatment of waste liquids of different concentrations and batches. The invention will be further described in detail below with specific application examples. The only difference is in the raw material composition; the specific implementation process is as follows:

[0053] Application Example 1: Treatment of hydrochloric acid pickling waste liquid in cold-rolled steel plate plant

[0054] Step 1: Raw material preparation

[0055] 100 kg of hydrochloric acid pickling waste liquid from a cold-rolled steel plate plant was selected. Its core components are as follows: ferrous chloride ( 11.2%, free hydrochloric acid ( 6.2%, total chlorine ( 19.0%, containing trace amounts of zinc impurities ( 0.09%, Chromium ( 0.004%, and suspended solids ( 1.6% (organic additive urotropine) and 0.23% (organic additive urotropine).

[0056] Step 2: Purification and impurity removal (S1)

[0057] The waste liquid was then transported to a pretreatment tank, where alkaline solution was added to adjust the pH to 4.0-5.0. , Heavy metal ions form hydroxide precipitates; then polyaluminum chloride flocculant is added to promote the coagulation of fine suspended solids and precipitates. Solid-liquid separation is achieved through plate and frame filtration to obtain a clarified pretreated liquid. The resulting heavy metal-containing waste residue is disposed of separately in accordance with hazardous waste regulations.

[0058] Step 3: Neutralization under high gravity and solid-liquid separation (S2, S3)

[0059] The clarified pretreatment liquid is pumped into a high-gravity neutralization reactor, and circulating ammonia gas from S4 is introduced. Under the action of the high-gravity field, the waste liquid and ammonia gas react rapidly to generate a mixed slurry of ferrous hydroxide and ammonium chloride. The material residence time is controlled at 50ms, and the neutralization efficiency reaches 96%. The mixed slurry is sent to a closed filter press to separate ferrous hydroxide filter cake with a water content of 50% and ammonium chloride filtrate. The filter cake is sent to a drying and oxidation unit via a screw conveyor and dried and oxidized in an aerobic environment at 180℃ to convert it into iron oxide red product.

[0060] Step 4: Ammonia Recovery and Conversion (S4)

[0061] The ammonium chloride filtrate was introduced into a closed calcium ammonium chloride reactor, and the mixture was weighed using a loss-in-weight balance. : High-purity calcium oxide is added at a molar ratio of 1:1.01. The stirring device is turned on and a negative pressure environment of -30Pa is maintained by the vacuum system. The ammonia gas released from the reaction is captured by the gas-liquid separator and then reused in the S2 supergravity neutralization step to achieve a closed-loop ammonia cycle.

[0062] Step 5: Preparation of calcium chloride and purified water (S5)

[0063] The solution after the reaction of ammonium and calcium was filtered through a bag filter to remove trace suspended solids, and then concentrated in a multi-effect evaporator to finally obtain calcium chloride product and purified water. Results: 6.92 kg of iron oxide red product, purity 98.1%, yield 98%; 18.84 kg of calcium chloride product, purity 98.4%, yield 98%; 72.69 kg of purified water, conductivity ≤10 μS / cm, pH≈7, meeting distilled water standards.

[0064] Application Example 2: Treatment of Hydrochloric Acid Pickling Waste Liquid from a Stainless Steel Pipe Fittings Factory

[0065] Step 1: Raw material preparation

[0066] 100 kg of hydrochloric acid pickling waste liquid from a stainless steel pipe fitting factory was selected. Its core components are as follows: ferrous chloride ( 6.2%, free hydrochloric acid ( 10.0% total chlorine 19.1%, containing trace amounts of chromium impurities ( 0.021%, Nickel ( 0.014%, and suspended solids ( 0.7% organic additives and surfactants.

[0067] Step 2: Purification and impurity removal (S1)

[0068] The waste liquid is transported to a pretreatment tank, where alkaline solution is added to adjust the pH to 4.0-5.0. , Heavy metal ions such as ⁺ form hydroxide precipitates; polyacrylamide flocculant is added to promote the coagulation of suspended solids, and solid-liquid separation is achieved through multi-media filtration to obtain a clarified pretreated liquid. The waste residue containing heavy metals is disposed of in accordance with hazardous waste regulations.

[0069] Step 3: Neutralization under high gravity and solid-liquid separation (S2, S3)

[0070] The clarified pretreatment liquid was pumped into a gravity neutralization reactor, and circulating ammonia was introduced for reaction. The material residence time was controlled at 30ms, and the neutralization efficiency reached 97%. The mixed slurry was separated by a closed filter press to obtain ferrous hydroxide filter cake with a water content of 45% and ammonium chloride filtrate. The filter cake was sent to a drying oxidation device and dried and oxidized in an aerobic environment at 150℃ to obtain iron oxide red product.

[0071] Step 4: Ammonia Recovery and Conversion (S4)

[0072] The ammonium chloride filtrate was introduced into the calcium ammonium reactor, and then... High-purity calcium oxide is added at a molar ratio of 1, and a negative pressure of -15 Pa is maintained by a vacuum system under stirring. The ammonia gas produced in the reaction is treated by a gas-liquid separator and then recycled to S2 to complete the ammonia cycle.

[0073] Step 5: Preparation of calcium chloride and purified water (S5)

[0074] After the reaction, the solution was filtered through a precision filter to remove impurities, and then concentrated using an MVR evaporator to obtain calcium chloride product and purified water. Results: 3.83 kg of iron oxide red product, purity 98.9%, yield 98%; 20.21 kg of calcium chloride product, purity 98.5%, yield 98%; 74.60 kg of purified water, conductivity ≤10 μS / cm, pH≈7, meeting industrial reuse standards.

[0075] Application Example 3: Treatment of Hydrochloric Acid Pickling Waste Liquid from a Carbon Steel Structural Components Factory

[0076] Step 1: Raw material preparation

[0077] 100 kg of hydrochloric acid pickling waste liquid from a carbon steel structural parts factory was selected. Its core components are as follows: ferrous chloride ( 16.4%, free hydrochloric acid ( 3.2%, total chlorine ( 28.1%, containing trace amounts of lead impurities ( 0.002%, cadmium ( 0.0001%, and suspended solids ( 3.7% organic additives and corrosion inhibitors.

[0078] Step 2: Purification and impurity removal (S1)

[0079] The waste liquid is transported to a pretreatment tank, where alkaline solution is added to adjust the pH to 4.0-5.0. , Heavy metal ions such as ⁺ form hydroxide precipitates; polyaluminum chloride and polyacrylamide composite flocculant are added to enhance the coagulation effect of suspended solids, and the clarified pretreated liquid is obtained by plate and frame filtration. The waste residue containing heavy metals is disposed of in accordance with the hazardous waste regulations.

[0080] Step 3: Neutralization under high gravity and solid-liquid separation (S2, S3)

[0081] The clarified pretreatment liquid was pumped into a gravity neutralization reactor, and circulating ammonia was introduced for reaction. The material residence time was controlled at 80ms, and the neutralization efficiency reached 95%. The mixed slurry was separated by a closed filter press to obtain ferrous hydroxide filter cake with a water content of 55% and ammonium chloride filtrate. The filter cake was sent to a drying oxidation device and dried and oxidized in an aerobic environment at 220℃ to obtain iron red product.

[0082] Step 4: Ammonia Recovery and Conversion (S4)

[0083] The ammonium chloride filtrate was introduced into the calcium ammonium reactor, and then... High-purity calcium oxide is added at a molar ratio of 1:1. Under stirring, a negative pressure of -45Pa is maintained by a vacuum system. The ammonia gas generated in the reaction is treated by a gas-liquid separator and then recycled to S2, thus achieving a closed loop of ammonia.

[0084] Step 5: Preparation of calcium chloride and purified water (S5)

[0085] After the reaction, the solution was filtered through multiple stages to remove trace impurities, and then concentrated using a multi-effect evaporator to obtain calcium chloride product and purified water. Results: 10.12 kg of iron oxide red product, purity 98.5%, yield 98.1%; 18.83 kg of calcium chloride product, purity 98.3%, yield 98.2%; 68.64 kg of purified water, conductivity ≤10 μS / cm, pH≈7, which can be directly reused.

[0086] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A resource-based treatment process for hydrochloric acid pickling waste liquid based on supergravity neutralization and ammonia closed-loop, characterized in that, Includes the following steps: S1. Purification and impurity removal: Pretreatment of hydrochloric acid pickling waste liquid to remove suspended solids and heavy metal impurities; S2, Ultragravity Neutralization: The purified waste liquid is pumped into the ultragravity neutralization reactor, and ammonia gas is introduced into it to neutralize and precipitate the hydrochloric acid and ferrous chloride in the waste liquid, generating a mixed slurry of ferrous hydroxide and ammonium chloride. S3. Solid-liquid separation and preparation of iron red product: The mixed slurry is fed into a closed filter press for solid-liquid separation to obtain a filter cake containing ferrous hydroxide and a filtrate containing ammonium chloride. The filter cake is dried and oxidized to obtain iron red product. S4. Ammonia Recovery and Conversion: The ammonium chloride-containing filtrate is introduced into the calcium ammonium reactor, and calcium oxide is added thereto. The reaction is carried out under stirring and slight negative pressure conditions. The ammonia gas released by the reaction is extracted and reused in the supergravity neutralization step. S5. Preparation of calcium chloride product: The solution obtained after step S4 is purified and concentrated to obtain calcium chloride product and purified water, respectively.

2. The hydrochloric acid pickling wastewater resource utilization process based on supergravity neutralization and ammonia closed-loop as described in claim 1, characterized in that, The hypergravity neutralization reactor is configured to generate a hypergravity field, the hypergravity field providing a centrifugal acceleration that is 100 to 1000 times the gravitational acceleration; the residence time of the material in the hypergravity neutralization reactor is 10 to 100 milliseconds.

3. The hydrochloric acid pickling wastewater resource utilization process based on supergravity neutralization and ammonia closed-loop as described in claim 1, characterized in that, The ammonium calcium reactor is configured as a closed stirred reaction vessel, with an exhaust system connected to the top to maintain a slightly negative pressure environment, and is equipped with a feeding device for solid calcium oxide.

4. The hydrochloric acid pickling wastewater resource utilization process based on supergravity neutralization and ammonia closed-loop as described in claim 3, characterized in that, The gas extraction system includes a vacuum pump and a gas-liquid separator installed on the exhaust pipe of the calcium ammonium reactor. The gas-liquid separator is used to capture and recirculate liquid droplets entrained by the gas.

5. The hydrochloric acid pickling wastewater resource utilization process based on supergravity neutralization and ammonia closed-loop as described in claim 1, characterized in that, The process of ammonia medium is closed-looped between step S2 and step S4, and the ammonia gas is recycled between the hypergravity neutralization reactor and the calcium ammonium reactor.

6. The hydrochloric acid pickling wastewater resource utilization process based on supergravity neutralization and ammonia closed-loop as described in claim 1, characterized in that, The filter press used in step S3 is a closed structure to prevent the ammonia odor from escaping and to maintain the material balance of the system.

7. The hydrochloric acid pickling wastewater resource utilization process based on supergravity neutralization and ammonia closed-loop as described in claim 1, characterized in that, The preparation of the iron oxide red product includes feeding the filter cake from the filter press into a drying device via a conveying device. The drying device is configured to heat and dry the filter cake under aerobic conditions, thereby converting ferrous hydroxide into iron oxide red.

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