Method for preparing ceramsite from municipal solid waste and industrial solid waste and solid waste ceramsite

Abstract

This invention discloses a method for preparing ceramsite from municipal solid waste and industrial solid waste, and the ceramsite itself. The raw materials, by dry weight percentage, are: 30%–50% biogas residue, 10%–30% desulfurization ash, 15%–25% desilication sludge cake, and 15%–25% waste bleaching clay. This invention also provides a method for preparing ceramsite from municipal solid waste and industrial solid waste. By classifying municipal solid waste at the source, using biogas residue from fermentation as the main material, and co-processing desulfurization ash, desilication sludge cake, and waste bleaching clay, this method achieves multiple benefits, including waste-to-waste treatment, resource utilization, and safe disposal of hazardous waste, resulting in significant environmental, social, and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of urban solid waste and industrial solid waste utilization technology, and more specifically, to a method for preparing ceramsite from urban solid waste and industrial solid waste, and ceramsite from solid waste. Background Technology

[0002] Municipal solid waste is characterized by its complex composition, loose structure, low density, easy perishability, and difficulty in transportation and storage. It is generally collected and transported in a mixed manner, and the main treatment methods are landfill, composting, and incineration.

[0003] In recent years, a comprehensive classification system for household waste, including sorting, collection, transportation, and treatment, has been gradually established. Waste is increasingly recognized as an "urban mineral." Combustible waste and recyclables in dry waste are being utilized for energy and resource recovery, respectively. However, the utilization of fermentation residue (biogas residue) from wet waste still faces challenges. The amount used for landscaping and forest land disposal is small, which easily leads to stockpiling.

[0004] As a pillar industry of the national economy, steel plants have long processes and are resource- and energy-intensive enterprises, producing large amounts of solid waste. While most industrial waste is utilized on a large scale through in-plant reuse, external building materials processing, and deep processing, 2% of solid waste remains difficult to treat and utilize, or faces high costs for outsourced disposal, becoming a pain point for achieving "zero emissions" of solid waste from steel plants. For example, desulfurization ash from steel plant sintering machines and dry / semi-dry flue gas desulfurization devices in self-owned power plants resembles cement in appearance, with extremely fine particles (average particle size below 10μm), extremely low moisture content (below 0.5%), complex composition, and large fluctuations in chemical composition. The content of extremely fine fly ash such as SiO2, Al2O3, and Fe2O3 ranges from 3.5% to 20%, while the content of alkaline components such as CaSO3, CaCO3, f-CaO, and Ca(OH)2 is high. It is unstable, enriched with heavy metals, and has high levels of chloride ions and inert impurities, making treatment and disposal very difficult.

[0005] Currently, the main methods for disposing of desulfurization ash are stockpiling and dumping. There are some exploratory utilization methods in China, such as using it as a cement retarder, concrete admixture, wall material, mortar material, etc., or for engineering filling, gradation material, and reinforcement of soft foundations. These are mostly passive end-of-pipe treatments, which have problems such as low usage and low added value (CN200910180052.0, CN200910263921.6, CN201110209483.2, CN200910194833.5, CN200610123966.X, CN201110072276.7, etc.).

[0006] Desilication cake is a waste product generated during the desilication process of the acid regeneration unit in the cold-rolled steel sheet rolling process. Its main components are FeO, SiO2, and Cl. -It is classified as hazardous waste due to its strong acidity and corrosiveness, as well as its high chlorine content, which limits its direct use within the steelmaking process. Proper outsourcing is required for its disposal. There are reports in China of using desilication sludge cake to prepare iron oxide black, ultrafine / nano-sized iron tetroxide, composite materials, and magnetic photocatalysts, but the disposal capacity is low, the treatment process is complex, and it is difficult to scale up (e.g., Chinese patent applications CN201410426016.9, CN201210359797.5, CN201510546834.7, CN201210191410.X, CN201210359893.X, CN202010346233.2, etc.).

[0007] In petroleum refining, the use of activated clay to refine lubricating oil and paraffin generates a large amount of oily waste bleaching clay, which has been listed in the "National Hazardous Waste List". Currently, some oil refining companies simply treat it as solid waste and bury it deeply or incinerate it. This waste bleaching clay not only fails to be rationally utilized and wastes resources, but also pollutes the environment. At present, some waste bleaching clay is used as rubber filler, building sealant, detergent raw material, riboflavin raw material, molecular sieve raw material, composite modified asphalt raw material, feed additive, etc., but there are problems such as small usage and secondary pollution during the utilization process (e.g., Chinese patent publication numbers CN106431246A, CN112175743A, CN109722285A, CN109722285A, CN111375392A, CN105733062A, etc.).

[0008] It is imperative for steel companies to take the path of environmental friendliness, integrate into cities, and assume more social responsibility. If they adopt high-temperature furnaces equipped with complete flue gas pollutant removal equipment in conjunction with steel plants to co-process municipal solid waste and industrial solid waste, they can not only reduce carbon emissions and achieve "zero emissions of solid waste", but also achieve good economic and social benefits.

[0009] Expanded clay aggregate, also known as ceramic granules, is a new type of inorganic aggregate in spherical or ellipsoidal shape. It boasts advantages such as low density, high strength, good thermal insulation, good seismic resistance, and good impermeability. It can replace traditional crushed stone and river pebbles in the preparation of lightweight aggregate concrete products and is widely used in building materials, refractories, insulation materials, water purification, horticulture, food and beverage, and chemical industries, with a large market demand. Traditional expanded clay aggregate is made from natural minerals such as clay and shale, resulting in higher production costs and limited output, which has constrained the development of related industries.

[0010] Given the scarcity of natural resources such as clay, silt, and shale, the development of ceramsite (CN103130489A, CN102249584B, CN102718468A, CN102757255A, etc.) using industrial solid wastes such as fly ash, slag, sewage sludge, river dredging silt, dyeing sludge, and papermaking sludge has attracted attention in recent years. Related research indicates that, according to the ceramsite-forming principle, the raw materials for ceramsite production can be divided into three parts: ① the main ceramsite-forming components (SiO2 and Al2O3); ② fluxing agents (K2O, Na2O, CaO, MgO); ③ foaming agents (FeS, Fe2O3, FeO, C, CaMg(CO3)2, CaCO3, CaSO4, etc.).

[0011] This invention overcomes the shortcomings of existing technologies in utilizing urban wet waste fermentation slag, steel plant desulfurization ash and desilication sludge cake, and waste white clay from petroleum and petrochemical plants, and provides a method for preparing ceramsite from urban domestic waste and industrial solid waste, realizing the synergistic treatment and resource utilization of urban domestic waste and typical solid waste from steel plants and petroleum and petrochemical plants. Summary of the Invention

[0012] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing ceramsite from municipal solid waste and industrial solid waste, as well as ceramsite from solid waste. By classifying municipal solid waste at the source, using biogas residue from municipal solid waste fermentation as the main material, and co-processing desulfurization ash, desiliconization mud cake, and waste bleaching clay, it has multiple effects of treating waste with waste, resource utilization, and safe disposal of hazardous waste, resulting in significant environmental, social, and economic benefits.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] The first aspect of the present invention provides solid waste ceramsite, the raw materials of which, by dry basis mass percentage, are: 30% to 50% biogas residue, 10% to 30% desulfurization ash, 15% to 25% desilication mud cake, and 15% to 25% waste clay.

[0015] Preferably, the biogas residue is made from wet waste after sorting municipal solid waste; 95% of the biogas residue has a particle size of less than 0.5 cm and a moisture content of less than 80%.

[0016] The desulfurization ash is a byproduct of dry / semi-dry flue gas desulfurization; the desulfurization ash contains 10-50 wt% of calcium-containing alkaline active ingredients, and the moisture content of the desulfurization ash is less than 1%.

[0017] The desilication sludge cake comes from solid waste generated by the acid regeneration unit in the cold rolling process of a steel plant; the desilication sludge cake contains 1-15 wt% SiO2 and 1-15 wt% Al2O3.

[0018] The waste bleaching clay comes from the refining and wax-making processes of petroleum and petrochemical products or animal, vegetable, and mineral oils; the waste bleaching clay contains 40-70% SiO2, 8-20% Al2O3, and 15-40% oil.

[0019] Preferably, the bulk density of the solid waste ceramsite is 450–550 kg / m³. 3 The apparent density is 600–700 kg / m³. 3 The cylinder compressive strength is 2-3 MPa, the water absorption rate is less than 8% in 1 hour, and the thermal conductivity is 0.1-0.2 W / m·K.

[0020] A second aspect of the present invention provides a method for preparing ceramsite from municipal solid waste and industrial solid waste, comprising the following steps:

[0021] S1, dry and wet separation of municipal solid waste to obtain wet waste, wet waste is fermented and crushed to obtain biogas residue;

[0022] S2, mix biogas residue, desulfurization ash, desiliconization mud cake and waste white clay, and age to obtain ceramsite raw material;

[0023] S3, solid waste ceramsite is obtained by granulation, firing, cooling and screening of ceramsite raw materials.

[0024] Preferably, in step S1, 95% of the biogas residue has a particle size of less than 0.5 cm and a moisture content of less than 80%.

[0025] Preferably, in step S2:

[0026] The desulfurization ash is a byproduct of dry / semi-dry flue gas desulfurization; the desulfurization ash contains 10-50 wt% of calcium-containing alkaline active ingredients, and the moisture content of the desulfurization ash is less than 1%.

[0027] The desilication sludge cake comes from solid waste generated by the acid regeneration unit in the cold rolling process of a steel plant; the desilication sludge cake contains 1-15 wt% SiO2 and 1-15 wt% Al2O3.

[0028] The waste bleaching clay comes from the refining and wax-making processes of petroleum and petrochemical products or animal, vegetable, and mineral oils; the waste bleaching clay contains 40-70% SiO2, 8-20% Al2O3, and 15-40% oil.

[0029] The moisture content of the ceramsite raw material is 20-25 wt%; the ceramsite raw material, by dry basis mass percentage, is: 30%-50% biogas residue, 10%-30% desulfurization ash, 15%-25% desilication mud cake, and 15%-25% waste clay.

[0030] Preferably, step S3 includes the following process:

[0031] S31, granulation, is the process of pressing with a molding machine to obtain ceramsite raw material after molding;

[0032] S32, firing, uses a rotary kiln to dry, preheat and calcine the ceramsite raw material in sequence, completing the dehydration, oxidation-reduction and carbonate decomposition processes to obtain ceramsite clinker;

[0033] S33, cooling and screening: the calcined ceramsite clinker is cooled and screened to obtain solid waste ceramsite.

[0034] Preferably, in step S31, the molding pressure is 2-6 MPa, and the equivalent diameter of the ceramsite raw material is controlled at 10-20 mm.

[0035] Preferably, in step S32:

[0036] The rotary kiln is equipped with an alkaline spray purification system at its kiln tail.

[0037] The drying temperature is 300–500℃, and the drying time is 20–40 min;

[0038] The preheating temperature is 600–900℃, and the preheating time is 20–40 min;

[0039] The calcination temperature is 1000–1150℃, and the calcination time is 20–40 min.

[0040] Preferably, in step S3, the bulk density of the ceramsite is 450–550 kg / m³. 3 The apparent density is 600–700 kg / m³. 3 The cylinder compressive strength is 2-3 MPa, the water absorption rate is less than 8% in 1 hour, and the thermal conductivity is 0.1-0.2 W / m·K.

[0041] Preferably, it also includes S4, recycling the material, whereby the flue gas generated during the firing process is cooled and purified, then sprayed with alkaline solution to obtain a precipitated mud cake, and the precipitated mud cake and the undersize material from the screening process are returned to the mixing and aging process for reuse.

[0042] This invention uses biogas residue produced by anaerobic fermentation of wet waste as the main material, and adds appropriate amounts of desulfurization ash, desilication mud cake, and waste white clay as auxiliary materials to produce lightweight ceramsite. All indicators meet the requirements of lightweight or ultra-lightweight ceramsite in GB / T 17431.1-2000 "Lightweight aggregates and their test methods Part 1: Lightweight aggregates". It can be widely used to make ceramsite concrete and processed into lightweight building panels and blocks with excellent thermal insulation properties. It can also be applied to landscaping.

[0043] The beneficial effects of this invention are as follows:

[0044] 1. This invention uses wet waste fermentation residue (biogas residue) as the main material to produce lightweight ceramsite. While obtaining high-performance lightweight ceramsite, it can also co-process biogas residue, steel plant desulfurization ash, desiliconization mud cake and waste white clay from petroleum and petrochemical plants, realizing the large-scale and safe co-processing of various wastes.

[0045] 2. Desulfurization ash, desilication sludge cake, and waste bleaching clay are three types of industrial solid waste or hazardous waste that are difficult to dispose of individually. This invention combines them in a certain proportion to produce lightweight ceramsite with a wide range of applications. This not only achieves safe disposal and reduces the cost of harmless waste treatment, but also reduces the production cost of ceramsite plants and the demand for natural clay. Therefore, solid waste ceramsite has the advantages of waste utilization, energy saving, no land damage, and protection of the ecological environment. It belongs to green building materials and is a typical technology for achieving sustainable social development, with significant environmental, social, and economic benefits.

[0046] 3. This invention uses biogas residue with high moisture content, desilication mud cake, desulfurization ash with extremely low moisture content, and waste white clay to mix, condition, and naturally age. The mixture does not require water spraying or energy-consuming dehydration, thus avoiding the problem of sludge drying. Furthermore, the stickiness of biogas residue and waste white clay facilitates molding and granulation.

[0047] 4. The main inorganic components of the waste bleaching clay used in this invention are Al2O3, SiO2, and Fe2O3, which are similar to the clay components used in calcining ceramsite. The naturally porous structure of the saturated waste bleaching clay is occupied. During the high-temperature process, the oil and other impurities adsorbed by the waste bleaching clay are calcined, and the mesopores and micropores occupied by it are reopened, thereby restoring the loose and porous structure of the waste bleaching clay. The waste gas components generated during the oil combustion process are absorbed by alkaline spray, reducing environmental pollution.

[0048] 5. This invention utilizes four solid wastes—biogas residue, desulfurization ash, desiliconized mud cake, and waste bleaching clay—to ensure that the chemical composition of the raw materials meets the requirements for ceramic formation, fluxing, and foaming, and can effectively replace the use of original materials such as clay, shale, and limestone.

[0049] 6. This invention utilizes the alkaline environment of high-temperature roasting in a rotary kiln, which thoroughly detoxifies, has a simple process, and can dispose of a large amount of hazardous waste. Dioxins in desulfurization ash, desilication mud cake, and waste clay are completely decomposed, and heavy metals are melted and solidified in the ceramsite, with leaching concentrations far below the relevant standard requirements.

[0050] 7. This invention can synergistically dispose of urban domestic waste and typical solid waste from steel plants and petrochemical plants, and has multiple effects such as waste-to-waste treatment, resource utilization, and safe disposal of hazardous waste, with significant environmental, social and economic benefits. Attached Figure Description

[0051] Figure 1 This is a flowchart illustrating the method for preparing ceramsite from municipal solid waste and industrial solid waste according to the present invention. Detailed Implementation

[0052] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0053] This invention provides a solid waste ceramsite, the raw materials of which, by dry basis mass percentage, are: 30% to 50% biogas residue, 10% to 30% desulfurization ash, 15% to 25% desilication mud cake, and 15% to 25% waste bleaching clay.

[0054] The raw material for biogas residue comes from wet waste after sorting urban household waste; 95% of the biogas residue has a particle size of less than 0.5 cm and a moisture content of less than 80%.

[0055] The desulfurization ash is a byproduct of dry / semi-dry flue gas desulfurization; the desulfurization ash contains 10-50 wt% of calcium-containing alkaline effective components, and the moisture content of the desulfurization ash is less than 1%.

[0056] The desilication sludge cake comes from solid waste generated by the acid regeneration unit in the cold rolling process of steel plants; the desilication sludge cake contains 1-15 wt% SiO2 and 1-15 wt% Al2O3.

[0057] Waste bleaching clay comes from the refining and wax-making processes of petroleum and petrochemical products or animal, vegetable, and mineral oils; the SiO2 content in waste bleaching clay is 40-70%, the Al2O3 content is 8-20%, and the oil content is 15-40%.

[0058] The bulk density of the aforementioned solid waste ceramsite is 450–550 kg / m³. 3 The apparent density is 600–700 kg / m³. 3 The cylinder compressive strength is 2-3 MPa, the water absorption rate is less than 8% in 1 hour, and the thermal conductivity is 0.1-0.2 W / m·K.

[0059] Combination Figure 1 As shown, a second aspect of the present invention provides a method for preparing ceramsite from municipal solid waste and industrial solid waste, comprising the following steps:

[0060] S1, dry and wet separation of municipal solid waste to obtain wet waste, wet waste is fermented and crushed to obtain biogas residue;

[0061] The main components of municipal solid waste are scrap metal, stones, slag, glass, ceramics, packaging materials, paper, rubber, plastics, rubber sheets, bamboo and wood, kitchen waste with high moisture content and organic matter, and some harmful components such as fluorescent tubes, paint buckets, and waste batteries.

[0062] To better utilize resources, urban household waste is first separated into dry and wet waste. Dry waste can be further divided into hazardous waste, recyclables, and inorganic waste. Hazardous waste requires special disposal, while recyclables and inorganic waste can be utilized as resources. Wet waste is fermented and crushed to obtain biogas residue.

[0063] During the aerobic / anaerobic fermentation process of the aforementioned wet waste, the microorganisms in the waste fully metabolize and multiply, decomposing and transforming organic matter to obtain stable, mildly odorous, well-rotted biogas residue. To control processing costs, anaerobic fermentation is preferred. The resulting biogas residue is loose, moist, and highly adhesive, with 95% of particles smaller than 0.5 cm and a moisture content of less than 80%. This biogas residue is the solid product remaining after microbial fermentation of organic matter. Under high-temperature calcination, it can create pores within the ceramsite, and the resulting biogas residue ash also possesses excellent pozzolanic properties, containing large amounts of CaO and SiO2, compounds required for ceramsite production.

[0064] S2, mix biogas residue, desulfurization ash, desiliconization mud cake and waste white clay, and age to obtain ceramsite raw material;

[0065] Desulfurization ash is a byproduct of dry / semi-dry flue gas desulfurization facilities in steel sintering plants, steel pellet plants, self-owned coal-fired power plants, waste incineration plants, and non-ferrous smelters, with a moisture content of less than 1%. These ash particles are extremely fine, with very low moisture and density, making them prone to dust generation during collection and transportation. Mixing the desulfurization ash with biogas residue from fermented wet waste increases the water density and reduces dust generation, facilitating its utilization. Furthermore, the desulfurization ash contains 10-50% unreacted calcium-containing alkaline components such as CaCO3, f-CaO, and Ca(OH)2, which can act as a desulfurizing agent, chlorine-fixing agent, and fluxing agent during the ceramsite firing process, reducing the emission of acidic gases such as HCl and SO2 in the flue gas. During subsequent ceramsite firing, the unstable component CaSO3 in the desulfurization ash can be converted to CaSO4, and other components can be further solidified and transformed at high temperatures. With the help of flue gas purification facilities, while the effective components are fully utilized, harmful components such as heavy metals are solidified and sealed within the ceramsite.

[0066] The desilication sludge cake comes from solid waste generated by the acid regeneration unit in the cold rolling process of steel plants. SiO2 and Al2O3 are important components of the desilication sludge cake, with SiO2 content of 1-15 wt% and Al2O3 content of 1-15 wt%.

[0067] Waste bleaching clay originates from the refining and wax-making processes of petroleum and petrochemical products, animal and vegetable oils, and mineral oils. It appears as a grayish-brown, earthy substance with a slight solvent odor, and typically contains 15-40% oil. The impurities it adsorbs mainly include unsaturated hydrocarbons from petroleum minerals, sulfides, colloids, asphaltene, and other unstable and colored substances. Specifically, waste bleaching clay contains 40-70% SiO2 and 8-20% Al2O3.

[0068] The ceramsite raw material is obtained by mixing and aging biogas residue, desulfurization ash, desilication mud cake and waste bleaching clay. The moisture content of the ceramsite raw material is 20-25 wt%. The dry basis mass percentage of the four components in the ceramsite raw material is as follows: biogas residue 30%-50%, desulfurization ash 10%-30%, desilication mud cake 15%-25%, and waste bleaching clay 15%-25%.

[0069] The above four types of solid waste, after being thoroughly mixed and formulated based on their moisture content and chemical composition, have the following advantages:

[0070] 1) Desulfurization ash and waste clay have low moisture content, while biogas slurry and desilication mud cake have high moisture content. No water spraying or energy-intensive drying is required; mixing these four materials can adjust the moisture content of the ceramsite raw materials to 20-25%. In the subsequent preparation of ceramsite, the moisture content of the raw materials is a crucial control factor, directly affecting the molding and quality of the ceramsite. Appropriate moisture content allows the raw materials to form a uniform pore structure during firing, thereby improving the strength and durability of the ceramsite. According to the experimental plan, the moisture content of the mixture should be controlled between 20% and 25%. This is to ensure that the ceramsite is heated evenly during firing and to avoid poor molding or incomplete sintering due to excessive or insufficient moisture.

[0071] 2) The four solid waste chemical components are highly complementary. For example, biogas residue and waste clay have high SiO2 and Al2O3 content, strong plasticity, and can replace natural clay as the main raw material for ceramic production. At the same time, the small amount of organic matter they contain can act as a gas-generating component and be calcined into a porous structure at high temperatures. Desulfurization ash has fine particles, good wettability, and is easy to mix. In addition, its high chlorine and sulfur content has good water retention, which is beneficial for particle formation. Desilication mud cake has high Fe and Si content, which is beneficial for foaming. Iron elements can be used as raw materials to form the outer molten coating material during the calcination of ceramic particles. The high Si content helps to reduce the surface liquid phase viscosity and expansion temperature of ceramic particles during the high-temperature calcination stage, making the calcined ceramic particles denser and thus improving their strength. Therefore, after mixing the four in a certain proportion, the requirements for the proportion of SiO2, Al2O3, Fe2O3, and organic matter in the raw materials of ceramic particles can be met.

[0072] S3, solid waste ceramsite is obtained by granulation, firing, cooling and screening of ceramsite raw materials.

[0073] This step specifically includes the following processes:

[0074] S31, granulation, is the process of pressing with a molding machine to obtain ceramsite raw material after molding;

[0075] The granulation process of expanded clay aggregate is carried out by pressing with a molding machine. If the pressure is too low, the billet will be loose and the compressive strength of the expanded clay aggregate product will not meet the requirements for use as a building material. If the molding pressure is too high, the billet will be compacted, the firing time will be longer, and the production cost will increase. Therefore, the molding pressure is recommended to be 2 to 6 MPa, and the equivalent diameter of the expanded clay aggregate raw meal should be controlled at 10 to 20 mm.

[0076] S32, firing, uses a rotary kiln to dry, preheat and calcine the ceramsite raw material in sequence, completing the dehydration, oxidation-reduction and carbonate decomposition processes to obtain ceramsite clinker;

[0077] The raw ceramsite is sequentially dried, preheated, and calcined to obtain ceramsite clinker. The drying, preheating, and calcination processes respectively complete the dehydration, oxidation-reduction, and carbonate decomposition steps. Under the action of high temperature and expanding agent, the ceramsite expands rapidly, finally yielding ceramsite clinker. The drying temperature is 300–500℃, and the drying time is 20–40 min. The preheating temperature is 600–900℃, and the preheating time is 20–40 min. The calcination temperature is 1000–1150℃, and the calcination time is 20–40 min.

[0078] The aforementioned drying, preheating, and calcination are carried out in a rotary kiln, which is equipped with an alkaline spray purification system at the kiln tail. The ceramsite raw material contains a small amount of organic matter, which will produce odor during the high-temperature calcination process. During the rolling process of the ceramsite raw material in the kiln, dust will be generated. Therefore, the alkaline spray purification at the kiln tail can play a role in dust removal and odor reduction. The spray water is recycled, and the sludge in the sedimentation tank is periodically removed and returned to the ceramsite raw material.

[0079] S33, cooling and screening: the calcined ceramsite clinker is cooled and screened to obtain solid waste ceramsite.

[0080] According to the subsequent requirements for the utilization of solid waste ceramsite, the cooled solid waste ceramsite can be screened into 2 to 5 grades, preferably into 3 grades, such as <5mm, 5-12mm and >12mm; ceramsite with excessively small particle size or sieve residue can be collected and reused as raw material.

[0081] S4, material return and reuse: after the flue gas generated during firing is cooled and purified, it is sprayed with alkaline solution to obtain precipitated mud cake. The precipitated mud cake and the undersize material from the screening process are returned to the mixing and aging process for reuse.

[0082] The bulk density of the solid waste ceramsite prepared in the above process is 450–550 kg / m³. 3 The apparent density is 600–700 kg / m³. 3 The cylinder compressive strength is 2-3 MPa, the water absorption rate is less than 8% in 1 hour, and the thermal conductivity is 0.1-0.2 W / m·K.

[0083] Example

[0084] A method for preparing ceramsite from municipal solid waste and industrial solid waste, the specific steps of which are as follows:

[0085] 1) Obtaining biogas residue: Urban domestic waste is first separated into dry and wet waste. Hazardous waste, recyclables and inorganic waste in the dry waste are entrusted to specialized disposal and resource utilization respectively. The wet waste is fermented and crushed to obtain biogas residue.

[0086] 2) Obtaining ceramsite raw material: Mix biogas residue with desulfurization ash and desiliconization sludge cake from steel plants and waste white clay from petroleum and petrochemical plants, and age it.

[0087] 3) Preparation of ceramsite: The mixed material is granulated, fired, cooled, and sieved to obtain the finished ceramsite product;

[0088] 4) Recycling: During the firing process of ceramsite, the sieved material from the screening process and the sediment cake obtained during the flue gas cooling and purification process are returned to the mixing and aging process for reuse.

[0089] In this example, 1000 tons of municipal solid waste were collected from a residential community in Shanghai. After source separation, 273 tons of wet waste were obtained, mainly consisting of 35% kitchen waste, 30% vegetable scraps, 10% fruit and vegetable peels, 10% food residue, and 5% other waste. After anaerobic fermentation for 10 days, 230 tons of loose, moist, and highly cohesive biogas residue were obtained, with 95% of the particles smaller than 0.5 cm and a moisture content of 75%.

[0090] The desulfurization ash was taken from the circulating fluidized bed dry flue gas desulfurization process of a sintering plant. It contained the following components: CaSO4·H2O mass fraction 6.7%, CaSO3·1 / 2H2O mass fraction 59.6%, SiO2 mass fraction 6.2%, Al2O3 mass fraction 1.1%, MgO mass fraction 0.5%, Fe2O3 mass fraction 0.4%, Cl mass fraction 5%, and the combined mass fractions of Pb, Zn, Fe, and other metals approximately 2%. It also contained 4.0% unreacted CaCO3 mass fraction, 14.3% f-CaO mass fraction, and 9.5% Ca(OH)2 mass fraction. 90% of the particles had a particle size less than 10 μm and a moisture content of 0.5%.

[0091] The desilication sludge cake was taken from the acid regeneration unit of the cold rolling process. It contained 55.6% total iron, 15.0% SiO2, 6.5% Al2O3, 5.8% CaO, 1.2% Na2O, and 3.2% MgO.

[0092] Waste bleaching clay, taken from the refining process of petroleum and petrochemical products, has a SiO2 mass fraction of 55.3%, an Al2O3 mass fraction of 15.5%, an Fe2O3 mass fraction of 3.4%, an MgO mass fraction of 1.5%, 90% of the particles have a particle size of less than 10μm, a moisture content of 1.0%, and an oil content of 21.5%.

[0093] After anaerobic fermentation of wet waste for 7 days to obtain biogas residue, desulfurization ash and desiliconization mud cake from steel plants and waste white clay from petroleum and petrochemical plants are mixed and aged in the proportions shown in Table 1 (dry basis) to obtain ceramsite raw material.

[0094] The raw ceramsite was fired in a rotary kiln under the drying, preheating and calcining conditions shown in Table 1 to obtain the raw ceramsite. After cooling and screening, the solid waste ceramsite product was obtained.

[0095] During the firing process of ceramsite, the sieved material from the screening process, the sediment obtained after being sprayed with alkaline solution during the flue gas cooling and purification process, are returned to the mixing and aging process for reuse.

[0096] The aforementioned rotary kiln is a single-cylinder kiln, with the kiln tail higher than the kiln head, and a kiln body inclination angle of 4.5°. The rotation speed of the rotary kiln is 5 r / min. An alkaline spray purification system is installed at the kiln tail, and the spray water is recycled. Sludge in the sedimentation tank is periodically removed and returned as raw material for ceramsite. The flue gas emitted from the chimney does not exceed the "Emission Standard of Air Pollutants for Industrial Kilns".

[0097] In this embodiment, the technical parameters of the obtained solid waste ceramsite product are shown in Table 1, and the performance is shown in Table 2.

[0098] Table 1 Process parameters of the embodiment

[0099] Example 1 Example 2 Example 3 Example 4 Mud residue (wt%) 30 40 40 50 Desulfurization ash (wt%) 30 25 20 10 Desilicon mud cake (wt%) 25 20 15 20 Waste white clay (wt%) 15 15 25 20 Ceramic raw material moisture content (%) 22.5 21.0 23.5 24.55 Molding pressure (MPa) 2.5 4.5 5.5 6.0 Ceramic raw material equivalent diameter (mm) 20 15 15 20 Drying temperature (°C) 350 500 300 400 Drying time (min) 40 20 30 40 Preheating temperature (°C) 900 800 600 700 Preheating time (min) 20 40 35 30 Calcination temperature (°C) 1100 1150 1000 1050 Calcination time (min) 30 40 25 20

[0100] Table 2 shows the performance of the ceramsite products prepared in the examples.

[0101]

[0102]

[0103] As shown in Table 2, the bulk density of the ceramsite prepared in the embodiments of the present invention is 470–550 kg / m³. 3 The apparent density is 600–700 kg / m³. 3The compressive strength of the ceramsite is 2.5–2.9 MPa, the water absorption rate is 5.5–7.8% in 1 hour, and the thermal conductivity is 0.12–0.18 W / m·K. The ceramsite product meets the requirements of the national standard GB / T17431.1-2010 for lightweight aggregates (ceramsite). The product has been tested by the quality inspection department and its quality has reached the superior grade. The leaching toxicity meets the harmless index of GB5085.3-2007 (Identification Standard for Hazardous Waste: Leaching Toxicity Identification).

[0104] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A type of solid waste ceramsite, characterized in that, The raw materials, by dry weight percentage, are: 30%–50% biogas residue, 10%–30% desulfurization ash, 15%–25% desilication mud cake, and 15%–25% waste clay.

2. The solid waste ceramsite according to claim 1, characterized in that: The biogas residue is made from wet waste after sorting urban household waste; 95% of the biogas residue has a particle size of less than 0.5 cm and a moisture content of less than 80%. The desulfurization ash is a byproduct of dry / semi-dry flue gas desulfurization; the desulfurization ash contains 10-50 wt% of calcium-containing alkaline active ingredients, and the moisture content of the desulfurization ash is less than 1%. The desilication sludge cake comes from solid waste generated by the acid regeneration unit in the cold rolling process of a steel plant; the desilication sludge cake contains 1-15 wt% SiO2 and 1-15 wt% Al2O3. The waste bleaching clay comes from the refining and wax-making processes of petroleum and petrochemical products or animal, vegetable, and mineral oils; the waste bleaching clay contains 40-70% SiO2, 8-20% Al2O3, and 15-40% oil.

3. The solid waste ceramsite according to claim 1, characterized in that: The bulk density of the solid waste ceramsite is 450–550 kg / m³. 3 The apparent density is 600–700 kg / m³. 3 The cylinder compressive strength is 2-3 MPa, the water absorption rate is less than 8% in 1 hour, and the thermal conductivity is 0.1-0.2 W / m·K.

4. A method for preparing ceramsite from municipal solid waste and industrial solid waste, characterized in that, Includes the following steps: S1, dry and wet separation of municipal solid waste to obtain wet waste, wet waste is fermented and crushed to obtain biogas residue; S2, mix biogas residue, desulfurization ash, desiliconization mud cake and waste white clay, and age to obtain ceramsite raw material; S3, solid waste ceramsite is obtained by granulation, firing, cooling and screening of ceramsite raw materials.

5. The method for preparing ceramsite from municipal solid waste and industrial solid waste according to claim 4, characterized in that, In step S1, 95% of the biogas residue has a particle size of less than 0.5 cm and a moisture content of less than 80%.

6. The method for preparing ceramsite from municipal solid waste and industrial solid waste according to claim 4, characterized in that, In step S2: The desulfurization ash is a byproduct of dry / semi-dry flue gas desulfurization; the desulfurization ash contains 10-50 wt% of calcium-containing alkaline active ingredients, and the moisture content of the desulfurization ash is less than 1%. The desilication sludge cake comes from solid waste generated by the acid regeneration unit in the cold rolling process of a steel plant; the desilication sludge cake contains 1-15 wt% SiO2 and 1-15 wt% Al2O3. The waste bleaching clay comes from the refining and wax-making processes of petroleum and petrochemical products or animal, vegetable, and mineral oils; the waste bleaching clay contains 40-70% SiO2, 8-20% Al2O3, and 15-40% oil. The moisture content of the ceramsite raw material is 20-25 wt%; the ceramsite raw material, by dry basis mass percentage, is: 30%-50% biogas residue, 10%-30% desulfurization ash, 15%-25% desilication mud cake, and 15%-25% waste clay.

7. The method for preparing ceramsite from municipal solid waste and industrial solid waste according to claim 4, characterized in that, Step S3 The process includes the following: S31, granulation, is the process of pressing with a molding machine to obtain ceramsite raw material after molding; S32, firing, uses a rotary kiln to dry, preheat and calcine the ceramsite raw material in sequence, completing the dehydration, oxidation-reduction and carbonate decomposition processes to obtain ceramsite clinker; S33, cooling and screening: the calcined ceramsite clinker is cooled and screened to obtain solid waste ceramsite.

8. The method for preparing ceramsite from municipal solid waste and industrial solid waste according to claim 7, characterized in that: In step S31, the molding pressure is 2-6 MPa, and the equivalent diameter of the ceramsite raw material is controlled at 10-20 mm.

9. The method for preparing ceramsite from municipal solid waste and industrial solid waste according to claim 7, characterized in that: In step S32: The rotary kiln is equipped with an alkaline spray purification system at its kiln tail. The drying temperature is 300–500℃, and the drying time is 20–40 min; The preheating temperature is 600–900℃, and the preheating time is 20–40 min; The calcination temperature is 1000–1150℃, and the calcination time is 20–40 min.

10. The method for preparing ceramsite from municipal solid waste and industrial solid waste according to claim 4, characterized in that: In step S3, the bulk density of the solid waste ceramsite is 450–550 kg / m³. 3 The apparent density is 600–700 kg / m³. 3 The cylinder compressive strength is 2-3 MPa, the water absorption rate is less than 8% in 1 hour, and the thermal conductivity is 0.1-0.2 W / m·K.

11. The method for preparing ceramsite from municipal solid waste and industrial solid waste according to claim 4, characterized in that: It also includes S4, recycling of materials, where the flue gas generated during the firing process is cooled and purified, then sprayed with alkaline solution to obtain precipitated mud cake, and the precipitated mud cake and the undersize material from the screening process are returned to the mixing and aging process for reuse.

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