A system and method for processing oil sludge to produce ceramsite

Abstract

This invention discloses a processing system and method for producing ceramsite from oily sludge, comprising, sequentially and interconnected along the material flow direction: a pretreatment and impurity removal module, a deep deoiling module, a modified mixing module, a granulation and curing module, a gradient heat treatment module, a low-temperature sintering and forming module, an air-cooled grading module, and a tail gas closed-loop treatment module. The deep deoiling module integrates a 70-90℃ controllable temperature hot washing reactor, an automatic reagent dispenser, and a high-speed centrifugal three-phase separator. The gradient heat treatment module is a segmented temperature-controlled drying and preheating furnace. The tail gas closed-loop treatment module connects a waste heat recovery unit, a bag filter, an activated carbon adsorption tower, and a desulfurization and denitrification device in series at the flue gas outlet of the low-temperature mineral phase sintering furnace, forming a closed-loop structure of energy recovery and multi-stage purification. This invention constructs a closed-loop system of "waste heat recovery + multi-stage purification," achieving clean production throughout the entire process and enabling large-scale industrial application.

Description

Technical Field

[0001] This invention relates to the field of hazardous waste resource utilization and environmental engineering equipment technology, specifically to a treatment system and method for producing ceramsite from oil sludge. Background Technology With the rapid development of the petrochemical industry, the amount of oily sludge (classified as HW08 hazardous waste) generated during oil extraction, transportation, refining, and tank cleaning is increasing. This type of waste is characterized by high oil content, complex composition, high heavy metal content, and significant environmental hazards. Currently, domestic and international technologies for the resource-based treatment of oily sludge mainly focus on rotary kiln incineration, pyrolysis carbonization, and co-sintering, and corresponding treatment equipment has been developed.

[0002] The existing technology for producing ceramsite from oily sludge usually adopts a simple process route of "crushing-mixing-drying-sintering". However, in actual industrial applications, the existing technology and equipment generally have the following insurmountable defects: (1) The lack of a pre-deep oil removal mechanism leads to extremely unstable sintering conditions. Traditional equipment often directly mixes oily sludge with auxiliary materials and then enters the drying or sintering process. Due to the lack of a dedicated thermochemical washing and three-phase separation structure, the oil content in the raw materials fluctuates greatly (usually between 5% and 15%), resulting in uncontrollable calorific value of the material entering the sintering furnace. This not only causes drastic fluctuations in the temperature field during sintering, which can easily lead to ceramsite ring formation, black core, or cracking, but also causes the concentration of dioxins and VOCs in the flue gas to exceed the standard instantaneously, increasing the load and risk of the tail gas purification system. (2) The heavy metal stabilization methods are lagging behind, resulting in high environmental risks for the products.

[0003] Existing technologies mostly adopt an "end-of-pipe treatment" approach, relying on high-temperature sintering to physically encapsulate heavy metals within the ceramic particles. However, for heavy metals with high leaching toxicity (such as Cr) in HW08 type oily sludge... 6+ Pb² +), Simple physical wrapping is prone to secondary leaching of heavy metals under long-term natural weathering or acid rain leaching. Existing equipment lacks a pre-processed chemical modification unit, and cannot achieve the adsorption, complexation and lattice pre-curing of heavy metals through composite stabilizers before molding. As a result, the heavy metal leaching index of the finished ceramic particles is often at the national standard threshold, making it difficult to achieve high added value utilization. (3) The thermal system is simple and crude, with low energy efficiency and poor yield. Traditional drying and sintering equipment is mostly designed as a single chamber, lacking fine control over the migration of material moisture and the decomposition of organic matter. Green blanks often directly enter the high-temperature zone, and the rapid vaporization of moisture causes the blank to burst. The green blank breakage rate is usually as high as 15% or more. In addition, in order to achieve the liquid phase generation required for the vitrification of ceramic particles, the traditional process often needs to raise the temperature to above 1100℃, which not only consumes a lot of energy, but also exacerbates the risk of heavy metal volatilization. (4) The system integration is low, and continuous steady-state production cannot be achieved. Existing processing lines are mostly pieced together from discrete equipment, resulting in poor coordination between processes and low levels of automation. In particular, for high-viscosity and highly corrosive materials such as sludge, the lack of targeted modular design and anti-clogging structures leads to frequent equipment downtime for maintenance, failing to meet the stringent requirements of stability and continuity for large-scale industrial production.

[0004] In conclusion, developing a device for producing ceramsite from oil sludge that integrates deep oil removal, heavy metal pre-stabilization, gradient thermal control, low-temperature energy-saving sintering, and closed-loop purification of exhaust gas is an essential requirement for addressing current industry pain points. Summary of the Invention

[0005] The purpose of this invention is to provide a processing system and method for producing ceramsite from oil sludge, so as to at least partially solve the above-mentioned problems of the prior art.

[0006] To achieve the above objectives, the present invention provides a processing system for producing ceramsite from oil sludge, characterized in that it comprises: [missing information - likely referring to components] sequentially linked and connected along the material flow direction. The module includes a pretreatment and impurity removal module, a deep deoiling module, a modified mixing module, a granulation and curing module, a gradient heat treatment module, a low-temperature sintering and forming module, an air-cooled grading module, and a tail gas closed-loop treatment module. The deep oil removal module integrates a 70-90℃ temperature-controlled hot washing reactor, an automatic reagent dispenser, and a high-speed centrifugal three-phase separator, forming an integrated thermochemical washing-three-phase separation oil removal structure, ensuring that the oil content of the removed solid phase is consistently ≤1.5%. The gradient heat treatment module is a segmented temperature-controlled drying and preheating furnace, which is physically divided into a low-temperature drying chamber and a medium-temperature preheating chamber. The two chambers are equipped with independent temperature control and timed heat preservation components to achieve step-by-step dehydration and exhaust. The low-temperature sintering molding module is a low-temperature mineral phase sintering furnace with constant temperature control of 850-950℃, which realizes the bonding of the glass body of the silicon-aluminum system and simultaneously completes the solidification of the heavy metal lattice through mineral phase reconstruction. The exhaust gas closed-loop treatment module connects a waste heat recovery unit, a bag filter, an activated carbon adsorption tower, and a desulfurization and denitrification device in series at the flue gas outlet of the low-temperature mineral phase sintering furnace, forming a closed-loop structure of energy recovery and multi-stage purification.

[0007] Furthermore, the modified mixing module includes a batching machine, a stabilizer storage bin, and a high-strength mixer; The batching machine is externally connected to fly ash storage bins, coal gangue storage bins, and bentonite storage bins to form a matrix framework with a high silicon-to-aluminum ratio. The stabilizer storage silo quantitatively adds a composite stabilizer composed of sodium sulfide, calcium dihydrogen phosphate, and attapulgite in a mass ratio of 1:3:2. In the high-strength mixer, the adsorption, complexation, and passivation of heavy metals are completed, and a synergistic solidification effect is formed with the subsequent low-temperature sintering.

[0008] Furthermore, the granulation and curing module includes a disc granulator and a sealed curing chamber; The disc granulator rolls the modified mud into spherical particles with a particle size of 5-15 mm. The sealed curing chamber is a constant temperature and humidity structure that allows the particles to be statically cured for 24 to 48 hours to eliminate internal stress concentration caused by high-viscosity sludge and significantly improve the crack resistance of the green body.

[0009] Furthermore, in the segmented temperature-controlled drying and preheating furnace, the temperature control range of the low-temperature drying chamber is 105-150℃, which reduces the moisture content of the material to below 5%; the temperature control range of the medium-temperature preheating chamber is 300-500℃, which pyrolyzes trace amounts of residual organic matter and removes crystal water under oxygen-deficient conditions. The two chambers are connected by a transition section for slow conveying to avoid sudden temperature changes that could cause the billet to burst.

[0010] Furthermore, the low-temperature mineral phase sintering furnace is kept at a constant temperature of 850-950℃ for 20-40 minutes, preferably 900℃ for 30 minutes. Through liquid phase sintering, the rearrangement of the silicon-aluminum system and the formation of the glass network are promoted, and heavy metal ions are replaced into the silicate lattice, thereby achieving long-term environmental stability.

[0011] Furthermore, in the tail gas closed-loop treatment module, the waste heat recovery unit recovers the sensible heat in the sintering flue gas for auxiliary heating of the pretreatment and impurity removal module or the gradient heat treatment module, thereby reducing the overall energy consumption of the system; the bag filter and the activated carbon adsorption tower remove particulate matter and volatile organic compounds respectively, and the desulfurization and denitrification device ensures that nitrogen oxides and sulfur oxides meet emission standards.

[0012] Another object of the present invention is to provide a method for producing ceramsite using the aforementioned apparatus, characterized by comprising the following steps: S1 Pretreatment and impurity removal: The original HW08 oily sludge is crushed and screened to remove high-hardness impurities, preventing wear and tear on subsequent equipment and fluctuations in composition; S2 Deep Deoiling: Under conditions of 70-90℃, the emulsion structure of oil sludge is disrupted by a compound surfactant, and oil, water, and solids are efficiently separated by a high-speed centrifugal three-phase separator, with the oil content of the deoiled solid phase ≤1.5%; S3 Modified Mixing: The deoiled solid phase is forcibly mixed with fly ash, coal gangue, bentonite and composite stabilizer in proportion to form a heavy metal pre-stabilized matrix. S4 Granulation and Curing: The modified clay is made into 5-15mm spherical particles and cured in a constant temperature and humidity environment for 24-48 hours to eliminate internal stress; S5 gradient heat treatment: First, keep the temperature in a low-temperature drying chamber at 105-150℃ for 1-2 hours, then keep it in a medium-temperature preheating chamber at 300-500℃ for 15-30 minutes to dehydrate and pyrolyze residual organic matter in steps. S6 Low-temperature sintering: The mineral phase reconstruction and heavy metal lattice solidification are achieved by holding the temperature at a low-temperature mineral phase sintering furnace at 850-950℃ for 20-40 minutes. S7 Air-cooled grading: Rapid air-cooling and shaping of high-temperature ceramsite, and grading according to particle size; S8 closed-loop exhaust gas treatment: The sintering flue gas is treated by waste heat recovery, dust removal, adsorption, and desulfurization and denitrification before being discharged.

[0013] Further, in step S3, the composite stabilizer is composed of sodium sulfide, calcium dihydrogen phosphate and attapulgite in a mass ratio of 1:3:2. Sodium sulfide provides a sulfur source to generate insoluble sulfides with heavy metals, calcium dihydrogen phosphate promotes the formation of apatite phase, and attapulgite provides interlayer adsorption sites.

[0014] Furthermore, in step S5, a temperature gradient is formed between the low-temperature drying chamber and the medium-temperature preheating chamber through slow conveying, which avoids micro-cracks in the green body due to instantaneous temperature difference, thereby significantly reducing the bursting rate during sintering.

[0015] Furthermore, in step S6, the low-temperature mineral phase sintering furnace is kept at a constant temperature of 900℃ for 30 minutes, and the amount of liquid phase generated is controlled at 5% to 10% of the total mass. This ensures the particle strength while avoiding excessive melting that could lead to pore closure, thus achieving a balance between lightweight and high-strength performance. Compared with the prior art, the present invention has at least the following advantages: First, it completely eliminates sintering bursting defects, resulting in a breakthrough improvement in product yield. Existing technologies for treating high-moisture, high-oil sludge typically employ direct high-temperature sintering or simple drying, causing the internal moisture and residual oil in the green body to vaporize instantly, producing a "popcorn" effect, often resulting in a yield of less than 60%. This invention utilizes the synergistic effect of "deep degreasing (oil content ≤1.5%) + dual-cavity gradient heat treatment": Deep degreasing: reducing the oil content of the de-oiled solid phase to below 1.5% from the source, eliminating the main source of bursting gas. Step-by-step degassing: the low-temperature drying chamber (105~150℃) slowly removes free water, while the medium-temperature preheating chamber (300~500℃) thoroughly decomposes residual organic matter and removes crystal water. Technical effect: the material has undergone complete volatilization before entering the sintering furnace. Verification through examples shows that the green body integrity rate is consistently above 90%, significantly reducing production costs.

[0016] Second, heavy metals achieve "lattice-level" permanent solidification, resulting in extremely high environmental safety. Traditional processes rely solely on physical encapsulation or high-temperature vitrification, which prevents the formation of permanent solidification of heavy metal ions (such as Cr). 6+ It is highly susceptible to leaching under acid rain erosion. This invention employs a dual locking mechanism of "chemical pre-stabilization + low-temperature mineral phase reconstruction": Pre-passivation: A specific ratio of composite stabilizer (sodium sulfide: calcium dihydrogen phosphate: attapulgite = 1:3:2) reacts with heavy metals during the mixing stage through adsorption, complexation, and precipitation, generating sulfide or phosphate precipitates. Lattice solidification: Low-temperature sintering at 850–950℃ promotes the rearrangement of silicon-aluminum-oxygen tetrahedra, forming a stable mullite and glassy network, displacing heavy metal ions into the silicate lattice or encapsulating them within the spinel structure. Technical effect: TCLP leaching toxicity testing (Example 2) showed that highly toxic Cr... 6+ The leaching concentration was reduced from 18 mg / L in the raw material to 0.07 mg / L, which is far below the national standard limit (0.5 mg / L), thus achieving permanent stabilization of heavy metals.

[0017] Third, it breaks through the traditional sintering temperature limitations, significantly reducing energy consumption. Traditional ceramsite sintering typically requires temperatures above 1100℃, resulting in enormous energy consumption. This invention utilizes the ash characteristics of the sludge itself and optimizes auxiliary materials: by adding silicon-aluminum auxiliary materials such as coal gangue and fly ash, and precisely controlling the Si / Al ratio, the activation energy for the formation of the sintering liquid phase is reduced. Low-temperature mineral phase sintering at 850–950℃ is used, lowering the furnace temperature by 150–250℃ compared to traditional processes. Technical benefits: While ensuring the strength of the ceramsite, overall energy consumption is reduced by more than 20%, and the low-temperature operation extends the service life of the refractory material.

[0018] Fourth, the entire process is a closed-loop purification system with no secondary pollution. Existing technologies often only focus on end products, neglecting flue gas treatment. This invention constructs a closed-loop system of "waste heat recovery + multi-stage purification": Waste heat is utilized in stages: high-temperature flue gas above 650℃ is introduced into a waste heat recovery unit to preheat combustion air or raw materials, further reducing system energy consumption. Full-component purification: the flue gas sequentially passes through bag filters (ash removal), activated carbon adsorption (dioxin / VOCs removal), and desulfurization and denitrification (acid gas removal). Technical results: the final emission flue gas indicators are all superior to the "Standard for Pollution Control of Hazardous Waste Incineration" (GB 18484-2020), and there is no odor or black smoke, achieving truly clean production.

[0019] Fifth, the product boasts excellent performance, achieving high-value-added resource utilization. The ceramsite prepared through the above process has a dense and uniformly distributed microstructure. Technical effects: The product possesses the characteristics of "lightweight and high strength" (as shown in Example 1): bulk density as low as 760 kg / m³; compressive strength as high as 8.8 MPa; and water absorption rate controlled below 12%. These performance indicators far exceed the standards for ordinary building ceramsite and can be widely used in fields with stringent performance requirements, such as high-strength concrete and water treatment filter media, realizing the transformation of hazardous waste into high-quality resources. Attached Figure Description

[0020] Figure 1 This is a structural block diagram of the complete processing system for producing ceramsite from oil sludge according to the present invention. Figure 2 This is a schematic diagram of the complete processing method for producing ceramsite from oil sludge according to the present invention. Attached figure labels 1-Crusher, 2-Screening machine, 3-Hot washing reactor, 4-Reagent dispensing machine 5-High-speed centrifugal three-phase separator, 6-Batching machine, 7-Stabilizer storage bin, 8-High-intensity mixer. 9-Disc granulator, 10-Sealed curing chamber, 11-Segmented temperature-controlled drying and preheating oven. 12-Low-temperature mineral phase sintering furnace; 13-Air-cooled conveyor; 14-Vibrating screen; 15-Waste heat recovery unit. 16-Bag filter dust collector, 17-Activated carbon adsorption tower, 18-Desulfurization unit, 19-Denitrification unit Detailed Implementation To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate to understand the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a product or device comprising a series of units is not necessarily limited to those explicitly listed, but may include other units not explicitly listed or inherent to such product or device.

[0022] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0023] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0024] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] Figure 1The diagram shows the system structure of the entire oil sludge ceramsite production unit, including the modular layout of the whole machine, the connection relationship of the equipment, the main material flow and the auxiliary process of exhaust gas treatment. The whole unit adopts an integrated series structure of front-end pretreatment deoiling, mid-end modification molding and curing, gradient heat treatment, low-temperature sintering, back-end air-cooling grading and exhaust gas closed-loop purification. The structure is compact and the process is connected continuously, making it fully adaptable to industrial assembly line operations.

[0027] This invention discloses a processing system for producing ceramsite from oily sludge, comprising, sequentially and interconnected along the material flow direction: a pretreatment and impurity removal module, a deep deoiling module, a modified mixing module, a granulation and curing module, a gradient heat treatment module, a low-temperature sintering and forming module, an air-cooled grading module, and a tail gas closed-loop treatment module; the deep deoiling module includes a hot washing reactor, a reagent dispenser, and a high-speed centrifugal three-phase separator; the hot washing reactor is equipped with a heating jacket; the output end of the reagent dispenser is connected to the interior of the hot washing reactor; and the high-speed centrifugal three-phase separator is equipped with a deoiled solid phase discharge port; the modified mixing module includes a batching machine and a stabilizer. The system includes an agent storage silo and a high-intensity mixer. The batching machine is externally connected to multiple auxiliary material storage silos. The output ends of both the stabilizer storage silo and the batching machine are connected to the feed end of the high-intensity mixer. The gradient heat treatment module is a segmented temperature-controlled drying and preheating furnace, which is physically divided along the conveying direction into an independent but interconnected low-temperature drying chamber and a medium-temperature preheating chamber. The low-temperature drying chamber and the medium-temperature preheating chamber are each equipped with an independent temperature control component. The low-temperature sintering and forming module is a low-temperature mineral phase sintering furnace. The tail gas closed-loop treatment module includes a waste heat recovery unit, a bag filter, an activated carbon adsorption tower, and a desulfurization and denitrification device connected in series through pipelines.

[0028] Furthermore, the pretreatment and impurity removal module includes a crusher and a screening machine. The discharge end of the crusher and the feed end of the screening machine are connected by a sealed conveyor belt. A hard impurity collection port is provided below the screen of the screening machine. The discharge end of the screening machine is connected to the feed end of the hot washing reactor of the deep oil removal module through a screw conveyor.

[0029] Furthermore, in the deep deoiling module, the hot washing reactor is equipped with a stirring blade, and the reagent dispenser is a quantitative screw dosing mechanism; the high-speed centrifugal three-phase separator is equipped with a reagent injection port at the top, a crude oil outlet and a wastewater outlet at the bottom, and a deoiled solid phase outlet on the side wall.

[0030] Furthermore, in the modified mixing module, the batching machine is connected to the fly ash storage silo, coal gangue storage silo, and bentonite storage silo respectively via pneumatic valves; a loss-in-weight feeder is installed at the bottom of the stabilizer storage silo to quantitatively feed the composite stabilizer into the high-strength mixer.

[0031] Furthermore, the granulation and curing module includes a disc granulator and a sealed curing chamber. The feed end of the disc granulator is connected to the discharge end of the high-strength mixer. The tilt angle and speed of the disc granulator are adjustable. The sealed curing chamber is a sealed box structure, and is equipped with a humidifying spray pipe and a temperature and humidity sensor inside for constant temperature and humidity curing of the formed granules.

[0032] Furthermore, a slow transition section is provided between the low-temperature drying chamber and the medium-temperature preheating chamber of the segmented temperature-controlled drying and preheating oven; the low-temperature drying chamber is equipped with a first hot air circulation system, and the medium-temperature preheating chamber is equipped with a second hot air circulation system, and the heating power of the two is independently adjustable.

[0033] Furthermore, the low-temperature mineral phase sintering furnace is a rotary kiln or tunnel kiln sintering furnace, with the furnace body covered with a heat insulation layer, and the refractory material inside the furnace is high-alumina refractory brick; the temperature control components of the low-temperature mineral phase sintering furnace include multiple thermocouples and gas / electric heating elements distributed in different sections of the furnace body.

[0034] Furthermore, the air-cooled grading module includes an air-cooled conveyor and a vibrating screen. The air-cooled conveyor is a mesh belt conveyor with a perforated ventilated bottom plate. The vibrating screen is located at the discharge end of the air-cooled conveyor and is equipped with multiple layers of screens with different apertures to achieve multi-specification grading of ceramsite.

[0035] Furthermore, in the exhaust gas closed-loop treatment module, the waste heat recovery unit is a gas-to-gas heat exchange structure, with its heat medium channel connected in series between the flue gas outlet of the low-temperature mineral phase sintering furnace and the bag filter, and the refrigerant channel used to output preheated combustion air or hot water.

[0036] Furthermore, materials are transferred between modules via sealed screw conveyors or scraper conveyors. The entire device adopts a PLC central control system for linkage control of the start-up, shutdown, and operating parameters of each module. Material flow: Oily sludge raw material is crushed and refined by crusher 1 and then screened by screening machine 2 to remove hard impurities. The clean oily sludge is sent to hot washing reactor 3, where surfactant is added simultaneously by reagent dispenser 4 to complete thermochemical washing. The washed material enters high-speed centrifugal three-phase separator 5 to separate crude oil, wastewater, and deoiled solid material. The deoiled solid material is sent to high-intensity mixer 8, where batching machine 6 conveys fly ash, coal gangue, and bentonite auxiliary materials. Composite stabilizer is quantitatively added to stabilizer storage silo 7, and the multi-component materials are forcibly mixed to complete modification. The modified sludge is rolled into spherical particles by disc granulator 9 and sent to sealed curing chamber 10 to eliminate internal stress. After curing, the particles enter segmented temperature-controlled drying and preheating furnace 11 to complete low-temperature drying and medium-temperature preheating in sequence, and finally sent to low-temperature mineral phase sintering furnace 12 to complete low-temperature mineral phase sintering. After the sintered finished product is cooled by the air-cooled conveyor 13, it is graded and discharged by the vibrating screen 14 to obtain qualified ceramsite finished products of various specifications.

[0037] The exhaust gas auxiliary line process: the high-temperature flue gas generated by the low-temperature mineral phase sintering furnace 12 is collected by pipeline and enters the waste heat recovery unit 15, bag dust collector 16, activated carbon adsorption tower 17, desulfurization unit 18, and denitrification unit 19 in sequence to complete waste heat recovery, dust removal, VOCs and dioxin adsorption, desulfurization and denitrification purification in a step-by-step manner, and finally the exhaust gas meets the emission standards, forming a closed-loop environmental protection process.

[0038] This invention features a modular, interconnected structure. During operation, the original HW08 oily sludge is first fed into a crusher for crushing and a screening machine for impurity removal, eliminating hard impurities such as stones and metals to ensure the purity of the raw material. The cleaned oily sludge then enters a hot washing reactor, where it undergoes thermochemical washing at 70–90°C with a compound surfactant. A high-speed centrifugal three-phase separator separates the oil, water, and solid phases, yielding a low-oil-content de-oiled solid material, thus achieving crude oil recovery and material reduction.

[0039] The deoiled solid material is transported to a high-intensity mixer, where fly ash, coal gangue, and bentonite silica-alumina matrix additives are precisely proportioned by a batching machine. At the same time, a composite stabilizer is quantitatively added from a stabilizer storage silo. The high-intensity mixing process achieves uniform mixing of the materials, allowing for the adsorption, complexation, and passivation of heavy metals in advance, thus completing the pre-stabilization modification of heavy metals.

[0040] The modified plastic clay is rolled into 5-15mm spherical particles by a disc granulator and then sent to a sealed curing chamber for constant temperature and humidity curing for 24-48 hours to eliminate internal stress in the particles, greatly improve the structural strength of the green body, and avoid subsequent cracking and powdering.

[0041] After curing, the granules enter a segmented temperature-controlled drying and preheating furnace. They are first kept at a low temperature of 105-150℃ for 1-2 hours to reduce the moisture content of the material to below 5%. Then, they are kept at a medium temperature of 300-500℃ for 15-30 minutes to completely decompose trace amounts of residual organic matter, remove crystal water, and dehydrate in stages to prevent the green body from cracking.

[0042] The preheated particles are fed into a low-temperature mineral phase sintering furnace and kept at a constant temperature of 850-950℃ for 20-40 minutes, preferably 900℃ for 30 minutes, to achieve mineral phase reconstruction and glass bonding of the silicon-aluminum system, while simultaneously sealing heavy metals stably inside the silicate lattice for permanent fixation.

[0043] After sintering, the high-temperature ceramsite product is rapidly cooled and shaped by an air-cooled conveyor, and then graded and screened by a vibrating screen to obtain high-strength, lightweight, and environmentally friendly ceramsite of different particle sizes. The flue gas generated during sintering enters a multi-stage tail gas treatment system to complete waste heat recovery, dust removal, organic waste gas adsorption, desulfurization and denitrification, and finally meet emission standards.

[0044] like Figure 2 As shown, a method for producing ceramsite using the aforementioned apparatus according to the present invention includes the following steps: S1, Pretreatment and impurity removal: The original HW08 oily sludge is crushed and high-hardness impurities are screened out to prevent wear and tear on subsequent equipment and fluctuations in composition. S2, Deep Deoiling: Under conditions of 70-90℃, the emulsion structure of oil sludge is destroyed by compound surfactants, and oil, water and solids are efficiently separated by a high-speed centrifugal three-phase separator. The oil content of the deoiled solid phase is ≤1.5%. S3, Modified Mixing: The deoiled solid phase is forcibly mixed with fly ash, coal gangue, bentonite and composite stabilizer in proportion to form a heavy metal pre-stabilized matrix. S4, Granulation and Curing: The modified clay is made into 5-15mm spherical particles and cured in a constant temperature and humidity environment for 24-48 hours to eliminate internal stress; S5, gradient heat treatment: first, keep in a low temperature drying chamber at 105-150℃ for 1-2 hours, then enter a medium temperature preheating chamber at 300-500℃ for 15-30 minutes to dehydrate and pyrolyze residual organic matter in steps. S6, Low-temperature sintering: The mineral phase reconstruction and heavy metal lattice solidification are achieved by holding the temperature at a constant temperature of 850-950℃ in a low-temperature mineral phase sintering furnace for 20-40 minutes. S7, Air-cooled grading: High-temperature ceramsite is rapidly air-cooled and shaped, and then graded according to particle size; S8, closed-loop exhaust gas treatment: the sintering flue gas is treated by waste heat recovery, dust removal, adsorption and desulfurization and denitrification before being discharged.

[0045] Example 1: Standardized treatment of typical HW08 landed oil sludge (verifying the feasibility of basic processes) 1. Raw material characteristics The raw material was taken from Shengli Oilfield and was a typical landfill sludge (HW08 type). Testing revealed an initial water content of 65.4%, an oil content of 18.2% (Soxhlet extraction method), and a lower heating value of approximately 18 MJ / kg. Heavy metal testing showed: Cr 420 mg / kg, Pb 88 mg / kg, and Ni 210 mg / kg.

[0046] 2. Deep oil removal process 1000 kg of raw oil sludge is fed into a jaw crusher and crushed to a particle size of ≤50 mm. It then enters a double-layer vibrating screen (20 mm in the upper layer and 5 mm in the lower layer) to remove stones and metal debris.

[0047] Clean oil sludge was pumped into a hot-washed reactor, and steam was turned on to heat the mixture to 85±2℃. A compound surfactant (alkyl glycoside: rhamnolipid = 2:1) was added via a metering pump at a rate of 0.8% of its dry weight. The stirring speed was 60 rpm, and the reaction was carried out for 30 min. This step utilizes the solubilizing effect of the surfactant to disrupt the zeta potential stability of the oil-water interface, thus promoting the demulsification of the emulsified oil.

[0048] The material was fed into a horizontal spiral centrifugal three-phase separator (3500 rpm), which separated the following: crude oil: 164 kg (recovery rate 90.1%); wastewater: 578 kg (COD 12000 mg / L, sent for water treatment); and de-oiled solid phase: 246 kg. Key test result: The de-oiled solid phase, after Soxhlet extraction, had an oil content of only 1.18%, meeting the process control target of ≤1.5%.

[0049] 3. Modified compounding and heavy metal pre-stabilization The batching machine mixes the following components by weight: 100 parts deoiled solid phase, 35 parts fly ash (providing SiO2), 20 parts coal gangue (providing Al2O3), and 10 parts bentonite (providing montmorillonite interlayer structure).

[0050] The material is fed into a high-intensity mixer. At the same time, a composite stabilizer (sodium sulfide: calcium dihydrogen phosphate: attapulgite = 1:3:2) is added to the stabilizer storage silo at 5% of the dry basis weight of the deoiled solid phase.

[0051] Mixing mechanism: Sodium sulfide provides S² - With heavy metal ions (Pb² + , Cr³ + ) Forms sulfide precipitates with extremely small solubility products (Ksp); calcium dihydrogen phosphate hydrolyzes to produce PO4³ - , with Ca² +Apatite precipitates; the large specific surface area of ​​attapulgite provides physical adsorption sites. The three work synergistically to form a dense, pre-stabilized structure under strong shear force (120 rpm, 15 min).

[0052] 4. Granulation and Curing The modified mud is fed into an inclined disc granulator (45° inclination), sprayed with atomized water, and rolled into spherical particles with a particle size of 8-12 mm.

[0053] The particles were placed in a sealed curing chamber, with the temperature controlled at 25±2℃ and relative humidity >95%, and cured statically for 36 hours. During this stage, the montmorillonite hydrated and expanded, filling the micro-cracks in the particles and eliminating the internal stress caused by the high viscosity of the sludge. After curing, the compressive strength of the green body reached 4.8 MPa.

[0054] 5. Gradient heat treatment (core innovative step) The particles enter a segmented temperature-controlled drying and preheating furnace: Low-temperature drying chamber (120℃): held for 1.5 h. Infrared moisture meter monitoring shows that the material moisture content decreased from 27.5% to 3.2%. This stage mainly involves the evaporation of free water. Medium-temperature preheating chamber (420℃): held for 20 min. TG-DSC analysis shows that the kaolin dehydroxylation reaction (Al2Si2O5(OH)4→Al2Si2O7+2H2O) and the carbonization of residual tar occur in this stage, avoiding the explosion that occurs in the subsequent high-temperature stage.

[0055] 6. Low-temperature mineral phase sintering Preheated particles are fed into a rotary low-temperature mineral phase sintering furnace and sintered at a constant temperature of 900℃ for 30 min. Sintering mechanism: At 900℃, feldspar minerals form a small amount of liquid phase (approximately 8%), promoting particle rearrangement and material migration, resulting in murolization (3Al₂O₃). The formation of 2SiO2 and a glassy network allows heavy metal ions to be encapsulated or replaced within the silicate lattice, achieving permanent fixation.

[0056] 7. Product performance testing After sintering, the ceramsite was air-cooled and sieved. The test results are as follows: Example 2: Co-treatment of highly toxic tank bottom sludge and red mud (verification of heavy metal-enhanced stabilization) 1. Raw material characteristics The raw material is bottom sludge from oil refinery storage tanks, with an oil content of 26.5% and a Cr content as high as 1250 mg / kg (mainly Cr). 6+ It exists in a certain form, is extremely toxic, and contains a large amount of emulsifiers.

[0057] 2. Process Adjustment To address the high Cr content, the modification and mixing steps were adjusted as follows: Auxiliary material adjustment: 40 parts of Bayer process red mud were introduced (replacing part of the fly ash). Red mud is rich in Fe2O3 and CaO. Fe2O3 can act as a sintering flux, lowering the liquidus formation temperature; CaO can promote the formation of ettringite. Stabilizer enhancement: The proportion of composite stabilizer was increased to 8%, and the sodium sulfide ratio was slightly adjusted to promote Cr... 6+ Reduced to Cr³ + And Cr(OH)3 precipitate is formed.

[0058] 3. Results and Analysis After undergoing the same hot degreasing and gradient heat treatment as in Example 1, the mixture was sintered at 900°C.

[0059] XRD phase analysis revealed characteristic peaks of iron-chromium spinel (FeCr2O4) in the product. This indicates that under a reducing atmosphere and in the presence of sulfur ions, the highly toxic Cr... 6+ It was successfully reduced and transformed into a chemically stable spinel structure.

[0060] Leaching toxicity: Cr 6+ The leaching concentration was reduced from 18 mg / L in the raw material to 0.07 mg / L, which is far below the limit (0.5 mg / L) of the "Identification Standard for Hazardous Waste" (GB 5085.3-2007).

[0061] Example 3: Extreme operating condition verification of high water content emulsified sludge (verifying the advantages of gradient heat treatment) 1. Raw material characteristics The raw material is W / O type emulsified sludge produced by oil extraction, with a water content as high as 83%. The oil-water interface film is extremely stable and difficult to break the emulsion by conventional centrifugation.

[0062] 2. Process Adjustment Deep degreasing: The hot wash temperature is increased to 95°C, and polyaluminum chloride (PAC) is added as a demulsifier to disrupt the electrostatic balance of the emulsion film.

[0063] Gradient heat treatment: Due to the extremely high initial moisture content, the drying curve was adjusted. Low-temperature drying chamber (130℃): Extended to 2.5h to ensure slow diffusion and evaporation of deep capillary water and prevent "boiling explosion". Medium-temperature preheating chamber (480℃): Extended to 25min to ensure the chemical bonds of the emulsifier are broken and decomposed.

[0064] 3. Results Despite harsh raw material conditions and an increase in energy consumption of approximately 18%, the green body integrity rate reached 92% thanks to the step-by-step temperature control mechanism of gradient heat treatment, with no large-scale bursting occurring. The final product's cylinder compressive strength was 7.0 MPa, slightly lower than the standard operating conditions, but still meeting the lightweight aggregate standard (≥4.0 MPa).

[0065] Comparative Example 1: Traditional direct mixing and sintering method (to verify the necessity of the present invention) 1. Process Steps Take the same oily sludge as in Example 1, without deep degreasing and gradient heat treatment, simply dry it and mix it with clay to form granules, and then send it directly into a high-temperature sintering furnace at 1100℃.

[0066] 2. Results: Cracking: During sintering, approximately 60% of the particles cracked and pulverized due to the instantaneous vaporization of residual oil and moisture. Appearance and Performance: The product surface was blackened (due to residual carbon), the pore structure was uneven, and the cylinder compressive strength was only 3.5 MPa. Environmental Issues: A large amount of black smoke and dioxin precursors were detected in the exhaust gas, resulting in a significant increase in the exhaust gas treatment load. Heavy Metal Leaching: The Cr leaching concentration was 0.85 mg / L, exceeding the standard.

[0067] Conclusion: Comparative Example 1 demonstrates the fatal flaws of traditional processes in treating oily sludge, and proves the ingenuity of this invention in solving the bursting problem through deep degreasing and gradient heat treatment, and in solving the heavy metal leaching problem through pre-stabilization modification. Equivalent Substitution Implementation Instructions Those skilled in the art should understand that the scope of protection of this invention is not limited to the specific equipment models mentioned above. For example, a hot washing reactor can be replaced with a low-temperature catalytic oxidation tower; a disc granulator can be replaced with a roller extrusion granulator, as long as the particle size can be controlled within the range of 5-15mm; auxiliary materials such as fly ash and coal gangue can be replaced proportionally with siliceous aluminous solid wastes such as slag and tailings powder, the principle of which is to adjust the Si / Al ratio to facilitate glass formation.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for processing oil sludge to produce ceramsite, characterized in that, Including those that are sequentially linked and connected along the material flow direction: The module includes a pretreatment and impurity removal module, a deep deoiling module, a modified mixing module, a granulation and curing module, a gradient heat treatment module, a low-temperature sintering and forming module, an air-cooled grading module, and a tail gas closed-loop treatment module. The deep oil removal module integrates a 70-90℃ temperature-controlled hot washing reactor, an automatic reagent dispenser, and a high-speed centrifugal three-phase separator, forming an integrated thermochemical washing-three-phase separation oil removal structure, ensuring that the oil content of the removed solid phase is consistently ≤1.5%. The gradient heat treatment module is a segmented temperature-controlled drying and preheating furnace, which is physically divided into a low-temperature drying chamber and a medium-temperature preheating chamber. The two chambers are equipped with independent temperature control and timed heat preservation components to achieve step-by-step dehydration and exhaust. The low-temperature sintering molding module is a low-temperature mineral phase sintering furnace with constant temperature control of 850-950℃. The low-temperature mineral phase sintering furnace maintains a weak reducing atmosphere, and the flue gas stays in the furnace for no less than 2 seconds. The bonding of the silicon-aluminum system glass body is achieved through low-temperature mineral phase reconstruction, and the solidification of the heavy metal lattice is completed simultaneously. The exhaust gas closed-loop treatment module connects a waste heat recovery unit, a bag filter, an activated carbon adsorption tower, and a desulfurization and denitrification device in series at the flue gas outlet of the low-temperature mineral phase sintering furnace, forming a closed-loop structure of energy recovery and multi-stage purification. After multi-stage purification, the flue gas meets the GB 18484-2020 emission standard.

2. The system for producing ceramsite from oil sludge according to claim 1, characterized in that: The modified mixing module includes a batching machine, a stabilizer storage bin, and a high-strength mixer; The batching machine is externally connected to fly ash storage bins, coal gangue storage bins, and bentonite storage bins to form a matrix framework with a high silicon-to-aluminum ratio. The stabilizer storage silo quantitatively adds a composite stabilizer composed of sodium sulfide, calcium dihydrogen phosphate, and attapulgite in a mass ratio of 1:3:

2. In the high-strength mixer, the adsorption, complexation, and passivation of heavy metals are completed, and a synergistic solidification effect is formed with the subsequent low-temperature sintering.

3. The system for producing ceramsite from oil sludge according to claim 1, characterized in that: The granulation and curing module includes a disc granulator and a sealed curing chamber; The disc granulator rolls the modified mud into spherical particles with a particle size of 5-15 mm. The sealed curing chamber has a constant temperature and humidity structure, allowing the particles to be statically cured for 24–48 hours.

4. The system for producing ceramsite from oil sludge according to claim 1, characterized in that: In the segmented temperature-controlled drying and preheating furnace, the temperature control range of the low-temperature drying chamber is 105-150℃, which reduces the moisture content of the material to below 5%; the temperature control range of the medium-temperature preheating chamber is 300-500℃, which pyrolyzes trace residual organic matter and removes crystal water under oxygen-deficient conditions, and the two chambers are slowly conveyed through a transition section.

5. The processing system for producing ceramsite from oil sludge according to claim 1, characterized in that: The low-temperature mineral phase sintering furnace is kept at a constant temperature of 850-950℃ for 20-40 minutes, preferably 900℃ for 30 minutes, with the liquid phase generation controlled at 5%-10%. Liquid phase sintering promotes the rearrangement of the silicon-aluminum system and the formation of the glass network, and replaces heavy metal ions into the silicate lattice.

6. The system for producing ceramsite from oil sludge according to claim 1, characterized in that: In the closed-loop exhaust gas treatment module, the waste heat recovery unit recovers the sensible heat from the sintering flue gas for auxiliary heating of the pretreatment and impurity removal module or the gradient heat treatment module; the bag filter and activated carbon adsorption tower remove particulate matter and volatile organic compounds respectively, and the desulfurization and denitrification device ensures that nitrogen oxides and sulfur oxides meet emission standards.

7. A method for producing ceramsite using the apparatus according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1 Pretreatment and impurity removal: The original HW08 oily sludge is crushed and screened to remove high-hardness impurities, preventing wear and tear on subsequent equipment and fluctuations in composition; S2 Deep Deoiling: Under conditions of 70-90℃, the emulsion structure of oil sludge is disrupted by a compound surfactant, and oil, water, and solids are efficiently separated by a high-speed centrifugal three-phase separator, with the oil content of the deoiled solid phase ≤1.5%; S3 Modified Mixing: The deoiled solid phase is forcibly mixed with fly ash, coal gangue, bentonite and composite stabilizer in proportion to form a heavy metal pre-stabilized matrix. S4 Granulation and Curing: The modified clay is made into 5-15mm spherical particles and cured in a constant temperature and humidity environment for 24-48 hours to eliminate internal stress; S5 gradient heat treatment: First, keep the temperature in a low-temperature drying chamber at 105-150℃ for 1-2 hours, then keep it in a medium-temperature preheating chamber at 300-500℃ for 15-30 minutes to dehydrate and pyrolyze residual organic matter in steps. S6 Low-temperature sintering: The mineral phase reconstruction and heavy metal lattice solidification are achieved by holding the temperature at a low-temperature mineral phase sintering furnace at 850-950℃ for 20-40 minutes. S7 Air-cooled grading: Rapid air-cooling and shaping of high-temperature ceramsite, and grading according to particle size; S8 closed-loop exhaust gas treatment: The sintering flue gas is treated by waste heat recovery, dust removal, adsorption, and desulfurization and denitrification before being discharged.

8. The method according to claim 7, characterized in that: In step S3, the composite stabilizer is composed of sodium sulfide, calcium dihydrogen phosphate and attapulgite in a mass ratio of 1:3:

2. Sodium sulfide provides a sulfur source to generate insoluble sulfides with heavy metals, calcium dihydrogen phosphate promotes the formation of apatite phase, and attapulgite provides interlayer adsorption sites.

9. The method according to claim 7, characterized in that: In step S5, a temperature gradient is formed between the low-temperature drying chamber and the medium-temperature preheating chamber through slow conveying.

10. The method according to claim 7, characterized in that: In step S6, the low-temperature mineral phase sintering furnace is kept at a constant temperature of 900℃ for 30 minutes, and the amount of liquid phase generated is controlled at 5% to 10% of the total mass.

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