Waste aluminum phosphide and rotary kiln linkage safety treatment method and system

Abstract

The invention discloses a waste aluminum phosphide and rotary kiln linkage safety disposal method and system, and relates to the technical field of hazardous waste disposal and recycling. The invention discloses a safe disposal method for linkage of waste aluminum phosphide and a rotary kiln. The safe disposal method comprises the steps that firstly, waste aluminum phosphide and water are added into a corrosion-resistant reaction kettle to be stirred and hydrolyzed, and hydrogen phosphide gas and residue slurry are obtained; and then the phosphine gas diluted by the nitrogen and the residue slurry are conveyed to a combustion area of the rotary kiln to be subjected to high-temperature oxidation sintering, residue particles are collected, incineration tail gas is subjected to multi-stage purification treatment, and the tail gas is discharged after being detected to reach the standard. According to the safe and harmless treatment method and system for the waste aluminum phosphide, through the pretreatment coupling high-temperature rotary kiln incineration technology, synchronous high-temperature oxidative decomposition of residues and hydrogen phosphide gas is achieved, toxicity and fire blast risks are thoroughly eliminated, closed operation and automatic control are achieved in the whole process, and safety, environmental protection and high efficiency are guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of hazardous waste treatment and resource utilization technology, specifically relating to a highly efficient, safe, and pollution-free harmless disposal system and method for waste aluminum phosphide and its reaction residues generated in industries such as grain and tobacco storage. It is particularly suitable for large-scale centralized treatment scenarios of aluminum phosphide-containing waste. Through the synergistic effect of pretreatment hydrolysis and high-temperature incineration, the toxic phosphine gas and organic residues are simultaneously and completely decomposed. Background Technology

[0002] Aluminum phosphide (AlP), a highly effective fumigant, is widely used in grain depots, tobacco warehouses, and other locations for pest control. Commercially available aluminum phosphide is often sold in tablet form with 56% active ingredient, supplemented with additives such as magnesium stearate, paraffin wax, and ammonium carbamate to improve physical properties and slow-release effects. During use, uneven environmental humidity or inadequate sealing often results in some aluminum phosphide failing to react completely, forming waste aluminum phosphide residue. This residue is classified as HW49 hazardous waste, explicitly listed in the National Hazardous Waste List, posing a dual risk of acute toxicity and flammability / explosiveness. When it comes into contact with moisture, acids, alkalis, or alkaline substances, the unreacted aluminum phosphide in the residue continuously releases highly toxic and flammable phosphine gas (PH3), with an explosion limit of 2.12%~15.3% (V / V) and an auto-ignition point of approximately 100℃. This can easily cause poisoning, fires, or even explosions, posing a serious threat to workers and the surrounding environment.

[0003] Common treatment methods include landfill, wet alkaline hydrolysis, and traditional high-temperature incineration. Landfill: carries a long-term risk of leachate pollution and does not achieve the degradation of harmful substances, failing to meet the principles of "reduction and harmlessness." Wet alkaline hydrolysis: uses sodium hydroxide solution, which can partially inhibit PH3 release, but the reaction is incomplete, producing large amounts of high-salt wastewater containing phosphorus and aluminum, requiring secondary treatment and incurring high operating costs. Traditional high-temperature incineration: while it can decompose organic matter, it lacks a systematic collection and synergistic oxidation mechanism for PH3 gas, making PH3 leakage easy during the feeding process, and potentially leaving unoxidized phosphorus compounds or generating dioxins in the exhaust gas.

[0004] In addition, existing technologies generally suffer from problems such as fragmented processes, low automation, limited processing capacity, and insufficient safety protection, making it difficult to meet the needs of large-scale warehousing enterprises for batch, continuous, and safe disposal; phosphine gas and residue slurry are only physically separated and not simultaneously oxidized at high temperatures, making it difficult to effectively address the problem of concentrated and large quantities of aluminum phosphide residues faced by enterprises such as grain depots; at the same time, there is also a risk of leakage during the material addition process.

[0005] Therefore, there is an urgent need to develop an integrated safe disposal system that combines pretreatment hydrolysis, closed gas transportation, high-temperature synergistic oxidation, deep purification of exhaust gas, and intelligent monitoring to achieve closed-loop management of waste aluminum phosphide from source to end, ensuring that the treatment process is inherently safe, meets environmental standards, and operates efficiently. Summary of the Invention

[0006] The purpose of this invention is to provide a safe and harmless disposal method and system for waste aluminum phosphide combined with rotary kiln. By using pretreatment hydrolysis coupled with high-temperature rotary kiln incineration technology, the unreacted aluminum phosphide in the residue is completely decomposed and phosphine gas is simultaneously oxidized at high temperature, thus completely eliminating its toxicity and risk of combustion and explosion. The system adopts a design concept of full-process sealing, inert gas protection, micro-negative pressure operation, intelligent monitoring and emergency response linkage to ensure that the treatment process is safe, environmentally friendly and efficient, and is suitable for large-scale industrial applications.

[0007] To achieve the objective of this invention, a safe method for the integrated treatment of waste aluminum phosphide and rotary kiln is provided, characterized by comprising the following steps: S1. Pretreatment: Waste aluminum phosphide and hot water are added to a corrosion-resistant reactor and mixed and stirred for hydrolysis to obtain phosphine gas and residual slurry. At the same time, nitrogen gas is introduced into the corrosion-resistant reactor to control the oxygen concentration to be below 5% (v / v).

[0008]

[0009] S2. High-temperature oxidation in rotary kiln: Phosphine gas diluted with nitrogen and residual slurry are transported to the combustion zone of the rotary kiln and held at 850~900℃ for at least 30 minutes to achieve pyrolysis of organic matter (such as paraffin and stearates) and dehydration of Al(OH)3 into Al2O3, and complete oxidation of the diluted PH3 gas at high temperature; then it is transported to the secondary combustion chamber and held at 1100~1200℃ for at least 2 seconds to ensure complete decomposition of all combustibles and incompletely oxidized phosphorus compounds, with a phosphine oxidation rate ≥99.99%, yielding residual particles (i.e., slag) and incineration exhaust gas.

[0010]

[0011]

[0012] After treatment, the incineration exhaust gas mainly consists of gaseous P2O5, acidic gases (such as SO2 and HCl), and nitrogen oxides (NOx). X ), particulate matter, etc.

[0013] S3. Incineration flue gas purification treatment: The incineration flue gas is subjected to multi-stage purification in sequence through rapid cooling treatment, dry deacidification treatment, activated carbon injection adsorption treatment, bag filter dust removal treatment and wet deacidification treatment. The purified flue gas is then tested by CEMS and discharged after meeting the requirements of the "Standard for Pollution Control of Hazardous Waste Incineration (GB18484-2020)".

[0014] Rapid cooling treatment: Inject Ca(OH)2 solution and rapidly cool to below 200℃ to inhibit dioxin resynthesis, remove phosphoric acid pentoxide gas, and obtain fine solid particles (fly ash), which are then discharged; Dry deacidification treatment: Ca(OH)2 dry powder is sprayed in to remove acidic gases such as HCl and SO2 and to remove fly ash; Activated carbon spray adsorption treatment: adsorbs heavy metals, dioxins and volatile organic compounds, and removes fly ash; Baghouse dust collection: captures fly ash and particulate matter, with an emission concentration of <10 mg / m³; Wet deacidification treatment: Use 12-15wt% NaOH solution (pH≥12) to further remove residual acidic gases.

[0015] Furthermore, in step S1, the mass ratio of the waste aluminum phosphide to hot water is 1:(5~10), and the temperature of the hot water is 50~60℃, which can promote the complete hydrolysis of aluminum phosphide.

[0016] A waste aluminum phosphide to hot water ratio of 1:(5~10) ensures complete hydrolysis and full reaction of the aluminum phosphide, reducing residues and preventing a sudden increase in phosphine gas due to excessive water, thus reducing the burden of excess water in subsequent treatment. Using hot water at 50~60℃ provides the heat of reaction, accelerating the melting of paraffin and improving hydrolysis efficiency.

[0017] Furthermore, in step S1, the pressure of the corrosion-resistant reactor is -10 Pa; the stirring hydrolysis time is 30~35 min, and the stirring rate is 80~150 rpm, which can make the PH3 release rate ≥98%.

[0018] Furthermore, in step S2, the volume ratio of phosphine gas to nitrogen in the nitrogen-diluted phosphine gas is 1:10, and the oxygen concentration is less than 5% (v / v). Combined with the slight negative pressure, this prevents PH3 from spontaneously combusting.

[0019] This invention also provides a safe treatment system for waste aluminum phosphide linked to a rotary kiln, comprising the following components connected in sequence: Pretreatment unit: includes a corrosion-resistant reactor (i.e., a reactor made of corrosion-resistant material (such as a polytetrafluoroethylene lining), the corrosion-resistant reactor is equipped with a mechanical stirring device, one side of the corrosion-resistant reactor is connected to a hot water injection module through a water inlet, one side of the corrosion-resistant reactor is connected to a nitrogen purging device through a nitrogen purging port, one side of the corrosion-resistant reactor is connected to an exhaust module through an exhaust port, a reagent dosing port and an online oxygen analyzer are provided on the top of the corrosion-resistant reactor, and a pneumatic discharge valve is provided at the bottom of the corrosion-resistant reactor.

[0020] The pretreatment unit involves adding waste aluminum phosphide and hot water (50-60℃) into a corrosion-resistant reactor through the reagent inlet and water inlet, respectively. The reaction is carried out under stirring conditions (stirring speed 80-150 rpm) to completely hydrolyze the aluminum phosphide, yielding phosphine gas and a residual slurry. During the stirring hydrolysis process, a slight negative pressure (-10 Pa) is maintained inside the corrosion-resistant reactor using a ventilation module, and nitrogen is introduced through a nitrogen purging device to dilute the concentration of the product PH3 gas, controlling the oxygen concentration inside the corrosion-resistant reactor to <5% (v / v) to prevent spontaneous combustion of PH3.

[0021] Gas processing and conveying unit: includes a sealed pipeline, which is connected to the corrosion-resistant reactor through a gas outlet, and an online laser PH3 concentration monitor is installed on the sealed pipeline.

[0022] The gas inside the corrosion-resistant reactor is diluted with nitrogen (PH3:N2 = 1:10, v / v) and then transported to a sealed pipeline through the gas outlet on one side of the upper end of the corrosion-resistant reactor. During the transportation process, the PH3 concentration is monitored in real time by an online laser PH3 concentration monitor to ensure that the PH3 concentration in the sealed pipeline is <1.6% (v / v), which is ≥10% below the lower explosive limit (1.79%), thus preventing combustion and explosion.

[0023] The residue collection and feeding unit includes a residue collection device and a closed lifting device, used to stabilize the conveying frequency of the hydrolyzed residue slurry to ensure subsequent processing efficiency. The pre-treated hydrolyzed residue, a slurry containing Al(OH)3, magnesium stearate, paraffin, etc., is discharged into the residue collection device (i.e., a 25L closed plastic drum) via a pneumatic discharge valve. Then, through the closed lifting device (small packaging elevator), the residue is fed into the rotary kiln feed inlet (i.e., the feed inlet at the front end of the rotary kiln combustion zone) at a stable frequency of 6 minutes per drum, achieving continuous feeding.

[0024] Rotary kiln secondary combustion chamber incineration unit: includes a rotary kiln combustion zone and a secondary combustion chamber combustion zone. The rotary kiln combustion zone is provided with a feed inlet at the front end and is connected to the sealed pipe through an air inlet. A residue discharge valve is provided at the bottom of the secondary combustion chamber combustion zone.

[0025] The rotary kiln's secondary combustion chamber is used for high-temperature oxidation treatment of diluted phosphine gas and residual slurry, so as to pyrolyze organic matter (such as paraffin and stearates) and dehydrate Al(OH)3 into Al2O3, achieving a phosphine oxidation rate of over 99.99%.

[0026] The exhaust gas treatment unit includes, in sequence, a waste heat boiler, a quench tower, a dry desulfurization tower, an activated carbon bin, a bag filter, a wet desulfurization tower, and a heating desulfurizer. The exhaust gas inlet of the quench tower is connected to the exhaust port of the secondary combustion chamber. The flue gas treated by the heating desulfurizer is discharged through a chimney. An online flue gas detection device is installed in the middle of the chimney for real-time detection of pH3, SO2, and NO. x The exhaust gas treatment unit is used to purify the exhaust gas obtained after pretreatment and high-temperature oxidation of waste aluminum phosphide, so that the emitted flue gas meets the emission standards of the "Standard for Pollution Control of Hazardous Waste Incineration (GB18484-2020)". It also monitors indicators such as HCl and particulate matter.

[0027] The intelligent monitoring and safety protection unit includes a central distributed control module, an emergency response module, and an emergency alkaline spray module. This unit enables automatic acquisition, adjustment, and remote monitoring of parameters throughout the entire process, ensuring that the pH concentration in the operating area meets the occupational exposure limits (<0.3 ppm) of GBZ 2.1-2019. Upon detecting a pH leak or system anomaly, it automatically cuts off the feed, activates the nitrogen protection system, and initiates the emergency alkaline spray module to neutralize the leaked gas.

[0028] Furthermore, the concentration of phosphine in the sealed pipe is less than 1.6% vol.

[0029] Furthermore, the conveying frequency of the residue slurry is 6 min / 25 L.

[0030] Furthermore, the key parameters for real-time detection of the central distributed control module are: The alarm threshold for pH 3 concentration is <0.2ppm, and the interlock action value is <0.5ppm; The system temperature fluctuation range is controlled within ±30℃; The system pressure is maintained at a slight negative pressure of -10 Pa.

[0031] Furthermore, the linked emergency alkaline spray module has a coverage radius of 3m and a NaOH concentration of 12-15wt%, used to neutralize leaked gas. The present invention has achieved the following beneficial effects: 1. Thorough treatment with no secondary pollution: This invention achieves complete decomposition of aluminum phosphide and PH3 through a dual mechanism of "hydrolysis + high-temperature oxidation". The toxic residue is <0.1% and the dioxin decomposition rate is >99.99%, which complies with the "Standard for Pollution Control of Hazardous Waste Incineration" (GB 18484-2020).

[0032] 2. Intrinsically safe design: This invention features a fully enclosed system, nitrogen protection, micro-negative pressure operation, and inert atmosphere delivery, fundamentally eliminating the risk of PH3 combustion and explosion; it is equipped with multi-level safety interlocks and emergency sprinklers to achieve intrinsic safety.

[0033] 3. High-efficiency continuous processing: The system of this invention can operate continuously, with a processing capacity of 0.5-1 ton / day.

[0034] 4. High level of automation and intelligence: The central distributed control module (DCS module) realizes full-process automatic control, data recording, fault early warning and remote monitoring, reducing the risk of manual operation.

[0035] 5. Environmental compliance: The exhaust emissions of this invention fully meet the standards; X-ray fluorescence spectroscopy (XRF) analysis of slag (mainly Al2O3) and fly ash (mainly calcium phosphate) shows that the calcium phosphate content in fly ash reaches 65%±2% and the alumina content in slag is 78%±3%, thus enabling resource recovery.

[0036] 6. Significant economic benefits: Compared with the traditional step-by-step treatment process, the operating cost of this invention is reduced by 15-20%, no wastewater is generated, and secondary treatment costs are avoided.

[0037] 7. The waste aluminum phosphide harmless disposal system and method of the present invention is safe, efficient, and environmentally friendly. Through the synergistic effect of pretreatment hydrolysis and high-temperature oxidation in a rotary kiln, it achieves the simultaneous and complete decomposition of toxic gases and hazardous residues. The system has a high degree of integration, advanced automation, sound intrinsic safety design, and fully compliant emissions, demonstrating significant social, environmental, and economic benefits. It can be widely applied in industries with high aluminum phosphide consumption, such as grain, tobacco, and ports, providing a reliable technical solution for the safe disposal of hazardous waste. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the process of a waste aluminum phosphide safe disposal system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the pretreatment unit in the waste aluminum phosphide safe disposal system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the rotary kiln secondary combustion chamber incineration unit and the exhaust gas treatment unit in the waste aluminum phosphide safe disposal system of this invention. Detailed Implementation

[0039] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. All features disclosed in this specification, or steps in all disclosed methods or processes, may be combined in any manner, except for mutually exclusive features and / or steps.

[0040] Example 1: Continuous Safety Handling under Standard Operating Conditions This embodiment is used to illustrate the stable operation performance and pollutant control effect of the safe disposal method and system of the present invention under standard design parameters.

[0041] 1. Safety procedures like Figure 1-3 As shown, the safe disposal method for the combined use of waste aluminum phosphide and rotary kiln in Example 1 is as follows: S1. Preprocessing: 20 kg of waste aluminum phosphide (approximately 56% effective ingredient, containing magnesium stearate, paraffin, and other excipients) was added to a 3m³ volume container. 3 In a reactor lined with polytetrafluoroethylene (PTFE).

[0042] 100 kg of deionized water at 60°C is added to the reactor through the water inlet using a hot water injection system, achieving a water-to-sludge mass ratio of 1:5.

[0043] Start the mechanical stirring device, control the stirring speed at 120 rpm, and stir continuously for 30 minutes.

[0044] During the reaction, high-purity nitrogen (purity ≥99.99%) is introduced into the reactor through the nitrogen purging device via the nitrogen purging port to maintain the oxygen concentration in the reactor at 3.5% (v / v) (monitored in real time by an online oxygen analyzer), and the exhaust module maintains a slight negative pressure of -10 Pa in the reactor.

[0045] After 30 minutes of hydrolysis, the aluminum phosphide hydrolysis rate was ≥98.5% as monitored online. Approximately 8.24 m³ of phosphine (PH3) gas under standard conditions and residual slurry were collected.

[0046] S2. Gas handling and transportation: The PH3 gas generated in the reactor is mixed and diluted online with the nitrogen introduced by the nitrogen purging device at a volume ratio of 1:10.

[0047] The diluted mixed gas is delivered to the rotary kiln combustion zone at a stable flow rate of 0.78 m³ / h through a 316L stainless steel pipe (i.e., a sealed pipe) equipped with a flame arrester and an emergency shut-off valve via the gas outlet on one side of the upper end of the reactor.

[0048] In a 316L stainless steel pipe, the PH3 concentration in the mixed gas was measured to be 1.48% (v / v) by an online laser detector, which is more than 30% lower than the lower explosive limit (2.12%).

[0049] S3. Residue Collection and Feeding: The slurry residue after pretreatment and hydrolysis (mainly containing Al(OH)3, molten paraffin wax, magnesium stearate, etc.) is discharged into a 25L sealed plastic bucket (which is the residue collection device) through the pneumatic discharge valve at the bottom of the reactor.

[0050] Using a closed lifting device, the residue slurry is continuously and stably fed into the feed inlet of the rotary kiln combustion zone at an average frequency of one bucket every 6 minutes.

[0051] S4. Rotary kiln secondary combustion chamber incineration: The temperature of the rotary kiln combustion zone is controlled at 900℃, the kiln rotation speed is 2.8 r / min, and the tilt angle is 2.8°. The mixed gas and residue slurry are transported to the rotary kiln combustion zone and remain there for 32 minutes.

[0052] The diluted PH3 gas mixes thoroughly with the fuel (fuel oil) flame in the rotary kiln combustion zone, undergoing a complete oxidation reaction. .

[0053] The temperature in the combustion zone of the secondary combustion chamber is maintained at 1150℃, and the flue gas residence time is 2.2 seconds to ensure that all organic matter and intermediate products are completely decomposed, resulting in treated residue particles (i.e., slag) and incineration exhaust gas.

[0054] S5. Exhaust gas purification and emission: The high-temperature incineration exhaust gas is treated by a waste heat boiler and then sent to a quench tower to cool it to 180°C within 1 second; it then passes through a dry deacidification tower (injected with Ca(OH)2 dry powder), an activated carbon bin (dosage 50 mg / Nm³), and a bag filter (outlet particulate matter concentration <8 mg / m³); and finally undergoes deep purification in a wet deacidification tower (15% NaOH solution, pH=12.5).

[0055] The purified flue gas is treated by a heated whitening device before being emitted through a chimney. Online monitoring by CEMS shows the following parameters: pH 3 < 0.1 mg / m³, SO2 < 30 mg / m³, NOx < 100 mg / m³, HCl < 10 mg / m³, and particulate matter < 8 mg / m³. Regular monitoring shows a dioxin emission concentration of 0.07 ng TEQ / m³, far below the standard limit.

[0056] S6. Residue treatment: The cooled residue particles (i.e., those treated by high-temperature oxidation in a rotary kiln) and the fly ash discharged from the exhaust gas purification are sealed and collected, and then recycled as resources after testing and confirmation.

[0057] The monitoring methods and safety mechanisms adopt a central distributed control module to monitor the pH3 concentration (alarm threshold <0.2 ppm), temperature (±30℃ fluctuation control), and pressure (maintaining a slight negative pressure of -10 Pa) in the reactor and rotary kiln in real time; an emergency alkaline spray system is set up (coverage radius 3m, NaOH concentration 15%), which is activated immediately upon detection of a leak; the pH3 concentration in the operating area complies with GBZ 2.1-2019 standard (<0.3 ppm).

[0058] Key control parameters

[0059] 4. Operational effectiveness of continuous safety procedures under standard operating conditions in this embodiment: (1) The system ran continuously and stably for 8 hours, processing a total of 0.16 tons of waste aluminum phosphide.

[0060] (2) Complete oxidation of PH3 was achieved (oxidation rate > 99.99%), the residue was rendered harmless, there was no PH3 leakage throughout the process, and the environmental concentration in the operating area was < 0.1 ppm, which fully meets the requirements of GBZ 2.1-2019.

[0061] Example 2: Energy-saving optimized operation under varying operating conditions This embodiment is used to illustrate the energy-saving potential and adaptability of the safety handling method and system of the present invention under optimized parameters, and to verify its stability and economy under different conditions.

[0062] 1. Safety procedures like Figure 1-3 As shown, the safe disposal method for the combined use of waste aluminum phosphide and rotary kiln in Example 2 is as follows: S1. Preprocessing: 20 kg of waste aluminum phosphide (approximately 56% effective ingredient, containing magnesium stearate, paraffin, and other excipients) was added to a 3m³ volume container. 3 In a polytetrafluoroethylene-lined reactor.

[0063] 120 kg of deionized water at 50°C is added to the reactor through the water inlet using a hot water injection system, achieving a water-to-sludge mass ratio of 1:6.

[0064] Start the mechanical stirring device, control the stirring speed at 100 rpm, and stir continuously for 35 minutes.

[0065] During the reaction, high-purity nitrogen (purity ≥99.99%) is introduced into the reactor through the nitrogen purging port via a nitrogen purging device to maintain the oxygen concentration in the reactor at <4.5% (v / v) (monitored in real time by an online oxygen analyzer), and the exhaust module maintains a slight negative pressure of -10 Pa in the reactor.

[0066] After 35 minutes of hydrolysis, the aluminum phosphide hydrolysis rate was 97.2% as monitored online. Approximately 8.04 m³ of phosphine (PH3) gas under standard conditions and residual slurry were collected.

[0067] The data above show that appropriately lowering the water temperature and increasing the water volume can compensate for the reaction rate, thus ensuring a high hydrolysis rate for this invention.

[0068] S2. Gas handling and transportation: The PH3 gas generated in the reactor is mixed and diluted online with the nitrogen introduced by the nitrogen purging device at a volume ratio of 1:10.

[0069] The diluted mixed gas is delivered to the rotary kiln combustion zone at a stable flow rate of 0.72 m³ / h through a 316L stainless steel pipe (i.e., a sealed pipe) equipped with a flame arrester and an emergency shut-off valve via the gas outlet on one side of the upper end of the reactor.

[0070] In the 316L stainless steel pipeline, the PH3 concentration in the mixed gas was measured to be 1.55% (v / v) by an online laser detector, which is safe and controllable.

[0071] S3. Residue Collection and Feeding: The residue is handled in the same way as in Example 1, with continuous feeding via a closed lifting device.

[0072] S4. Rotary kiln secondary combustion chamber incineration: The temperature of the rotary kiln combustion zone is controlled at 850℃, the kiln rotation speed is 2.5 r / min, and the tilt angle is 2.5°. The mixed gas and residue slurry are transported to the rotary kiln combustion zone and remain there for 35 minutes.

[0073] The diluted PH3 gas mixes thoroughly with the fuel (fuel oil) flame in the rotary kiln combustion zone, undergoing a complete oxidation reaction. .

[0074] The temperature in the combustion zone of the secondary combustion chamber is maintained at 1100℃, and the flue gas residence time is 2.0 seconds to ensure that all organic matter and intermediate products are completely decomposed, resulting in treated residue particles and incineration exhaust gas.

[0075] At lower temperatures, by extending the residence time, complete decomposition of organic matter and pH3 can still be ensured. Calculations show that fuel oil consumption under this condition is reduced by approximately 12% compared to Example 1.

[0076] S5. Exhaust gas purification and emission: The high-temperature combustion exhaust gas is treated by a waste heat boiler and then sent to a quench tower to cool it to 180°C within 1 second; it then passes through a dry deacidification tower (injecting Ca(OH)2 dry powder), an activated carbon bin (dosage 50 mg / Nm³), and a bag filter (outlet particulate matter concentration <8 mg / m³); and finally undergoes deep purification in a wet deacidification tower (12% NaOH solution, pH value maintained above 12).

[0077] The purified flue gas is treated by a heated whitening device before being emitted through a chimney. Online monitoring by CEMS shows the following parameters: pH < 0.1 mg / m³, particulate matter < 9 mg / m³. Regular monitoring of dioxin emissions shows a concentration of 0.09 ng TEQ / m³, and all emission indicators comply with GB 18484-2020 standards.

[0078] S6. Residue treatment: The cooled residue particles (i.e., those treated by high-temperature oxidation in a rotary kiln) and the fly ash discharged from the exhaust gas purification are sealed and collected, and then recycled as resources after testing and confirmation.

[0079] 2. Monitoring methods and safety mechanisms Same as in Example 1.

[0080] 3. Key control parameters

[0081] 4. Operational effectiveness of continuous safety procedures under standard operating conditions in this embodiment: (1) The system ran continuously and stably for 10 hours, processing a total of 0.2 tons of waste aluminum phosphide.

[0082] (2) Under the premise of ensuring the harmless treatment effect, the energy consumption and alkali consumption were significantly reduced by optimizing the process parameters, which verified the operational flexibility and economic advantages of the system of the present invention.

[0083] Comparative Example 1: Traditional Alkali Treatment Traditional alkaline treatment technology: using a 20wt% sodium hydroxide solution to neutralize the acidic byproducts generated during the hydrolysis of aluminum phosphide.

[0084]

[0085] This traditional alkaline solution treatment method cannot completely decompose phosphorus; it can only partially inhibit the release of pH3, leaving residual toxic substances. It also generates secondary pollution, producing phosphorus-containing wastewater that requires further treatment. Furthermore, it has low treatment efficiency, a long reaction time (typically 2-4 hours), high operating costs, and a large consumption of alkaline solution, resulting in cumulative wastewater treatment costs.

[0086] In actual alkaline treatment of waste aluminum phosphide, the PH3 inhibition rate is only 60-75%; the residue has toxic residues, and the unreacted AlP content is >5%; each ton of residue generates 8-10 tons of phosphorus-containing wastewater.

[0087] Compared with the above embodiments 1-2 and comparative examples, the technical advantages of the present invention are as follows: 1. Improved treatment thoroughness, achieving environmental standards.

[0088] 2. A leap forward in safety performance Traditional alkaline solution treatment: open operation, high risk of pH3 leakage, and lack of emergency response system.

[0089] This invention: The entire process is closed and protected by nitrogen (oxygen concentration <5%). Real-time monitoring and alarm (threshold < 0.2 ppm); Automatic emergency sprinkler system (coverage radius 3m, NaOH concentration 15%).

[0090] 3. Significant economic benefits Operating costs: 15-20% lower than traditional step-by-step processing.

[0091] Therefore, this invention, through a systematic, integrated, and intelligent technical approach, achieves integrated management of pretreatment, gas collection, high-temperature oxidation, and exhaust gas purification. It provides full-process protection from source control of PH3 generation to terminal purification, and utilizes a central control module to achieve automatic parameter adjustment and fault early warning. In terms of safety, processing efficiency, environmental performance, and economic benefits, it is significantly superior to traditional alkaline treatment and high-temperature incineration technologies, fully meets GB18484-2020 "Standard for Pollution Control of Hazardous Waste Incineration", and achieves inherent safety in aluminum phosphide treatment.

[0092] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A safe method for the integrated treatment of waste aluminum phosphide and a rotary kiln, characterized in that, Includes the following steps: S1. Pretreatment: Waste aluminum phosphide and hot water are added to a corrosion-resistant reactor and mixed and stirred for hydrolysis to obtain phosphine gas and residual slurry. At the same time, nitrogen gas is introduced into the corrosion-resistant reactor to control the oxygen concentration to be below 5% (v / v). S2. High-temperature oxidation in rotary kiln: Phosphine gas diluted with nitrogen and residue slurry are transported to the combustion zone of the rotary kiln and held at 850~900℃ for at least 30 minutes; then transferred to the secondary combustion chamber and held at 1100~1200℃ for at least 2 seconds to ensure the decomposition and conversion of aluminum phosphide and phosphine gas, resulting in residue particles and incineration exhaust gas; S3. Incineration flue gas purification treatment: The incineration flue gas is subjected to multi-stage purification in sequence through rapid cooling treatment, dry desulfurization treatment, activated carbon injection adsorption treatment, bag filter dust collection treatment and wet desulfurization treatment. The purified flue gas is then tested by CEMS and discharged after meeting the standards.

2. The safe treatment method for waste aluminum phosphide linked with a rotary kiln according to claim 1, characterized in that, In step S1, the mass ratio of the waste aluminum phosphide to hot water is 1:(5~10), and the temperature of the hot water is 50~60℃.

3. The safe treatment method for waste aluminum phosphide linked with a rotary kiln according to claim 1, characterized in that, In step S1, the pressure of the corrosion-resistant reactor is -10 Pa; the stirring hydrolysis time is 30~35 min, and the stirring rate is 80~150 rpm.

4. The safe treatment method for waste aluminum phosphide linked with a rotary kiln according to claim 1, characterized in that, In step S2, the volume ratio of phosphine gas to nitrogen in the nitrogen-diluted phosphine gas is 1:10, and the oxygen concentration is less than 5% (v / v).

5. The safe treatment method for waste aluminum phosphide linked with a rotary kiln according to claim 1, characterized in that, In step S2, the pressure in the rotary kiln combustion zone is -10 to -30 Pa, the kiln rotation speed is 2.5 to 3 r / min, and the tilt angle is 2.5 to 3°.

6. A safe disposal system linking waste aluminum phosphide with a rotary kiln, characterized in that, include: The pretreatment unit includes a corrosion-resistant reactor, which is equipped with a mechanical stirring device. One side of the corrosion-resistant reactor is connected to a hot water injection module via a water inlet, another side is connected to a nitrogen purging device via a nitrogen purging port, and another side is connected to an exhaust module via an exhaust port. A reagent dosing port and an online oxygen analyzer are installed above the corrosion-resistant reactor, and a pneumatic discharge valve is installed at the bottom of the corrosion-resistant reactor. A gas processing and conveying unit includes a sealed pipeline, which is connected to the corrosion-resistant reactor through a gas outlet, and an online laser PH3 concentration monitor is installed on the sealed pipeline; The residue collection and feeding unit includes a residue collection device and a closed lifting device; The rotary kiln secondary combustion chamber incineration unit includes a rotary kiln combustion zone and a secondary combustion chamber combustion zone. The rotary kiln combustion zone is provided with a feed inlet at the front end and is connected to the sealed pipe through an air inlet. A residue discharge valve is provided at the bottom of the secondary combustion chamber combustion zone. The exhaust gas treatment unit includes, in sequence, a waste heat boiler, a quench tower, a dry deacidification tower, an activated carbon bin, a bag filter, a wet deacidification tower, and a heating desulfurizer. The exhaust gas inlet of the quench tower is connected to the exhaust port of the combustion zone of the secondary combustion chamber. The flue gas treated by the heating desulfurizer is discharged through a chimney. An online flue gas detection device is installed in the middle of the chimney. The intelligent monitoring and security protection unit includes a central distributed control module, an emergency linkage module, and an emergency alkaline spray module.

7. The safe disposal system for waste aluminum phosphide linked to a rotary kiln according to claim 6, characterized in that, The concentration of phosphine in the sealed pipe is less than 1.6% (v / v).

8. The safety treatment system for waste aluminum phosphide linked to a rotary kiln according to claim 6, characterized in that, The conveying frequency of the residue slurry is 6 min / 25 L.

9. The safe disposal system for waste aluminum phosphide linked to a rotary kiln according to claim 6, characterized in that, The key parameters for real-time detection of the central distributed control module are: The alarm threshold for pH 3 concentration is <0.2ppm, and the interlock action value is <0.5ppm; The system temperature fluctuation range is controlled within ±30℃; The system pressure is maintained at a slight negative pressure of -10 Pa.

10. The safe disposal system for waste aluminum phosphide linked to a rotary kiln according to claim 6, characterized in that, The linked emergency alkaline spray module has a coverage radius of 3m and a NaOH concentration of 12-15wt%, and is used to neutralize leaked gas.

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