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CN-122006663-A - Solid waste-based ceramsite, preparation method thereof and application thereof in nitrogen and phosphorus removal and soil improvement

CN122006663ACN 122006663 ACN122006663 ACN 122006663ACN-122006663-A

Abstract

The invention discloses a solid waste-based ceramsite, a preparation method thereof and application thereof in nitrogen and phosphorus removal and soil improvement. The solid waste-based ceramsite comprises the following components of steel slag powder, zeolite powder, biochar, powder coal ash, portland cement and sodium silicate solution. Through material design, the ceramsite can be directly used as a safe soil conditioner and a sustained-release phosphate fertilizer after adsorption saturation, so that pollutants (phosphorus) in water are converted into available agricultural resources, and a closed loop cycle of treating waste with waste and changing waste into valuable is formed.

Inventors

  • HUANG TIANYIN
  • WU BINGDANG
  • XU XIAOYI
  • WU WEI
  • ZHUANG JINLONG
  • YANG JINGJING
  • WANG FEI
  • NIE YIMING
  • LIN ZHENJIE

Assignees

  • 苏州科技大学
  • 苏州普勒泰克环境科技有限公司

Dates

Publication Date
20260512
Application Date
20260205

Claims (10)

  1. 1. The solid waste-based ceramsite is characterized by comprising the following components of 50-65wt% of steel slag powder, 10-20wt% of zeolite powder, 5-15wt% of biochar, 5-10wt% of powdered coal ash, 5-10wt% of Portland cement and 1-3wt% of sodium silicate solution.
  2. 2. The solid waste-based ceramsite according to claim 1, wherein the grain size of the steel slag powder is less than or equal to 100 meshes, the CaO content is more than or equal to 40wt%, the Fe 2 O 3 content is more than or equal to 15wt%, the water content is less than or equal to 5%, and no obvious massive impurities exist; The particle size of the zeolite powder is less than or equal to 100 meshes, the specific surface area is more than or equal to 200m 2 /kg, and the cation exchange capacity is more than or equal to 100mmol/100g; the biochar is prepared from coconut shells or rice hulls serving as raw materials; the fineness of the powder coal ash is less than or equal to 45% under the condition of 0.045mm screen residue, and the loss on ignition is less than or equal to 12%; The strength grade of the silicate cement is more than or equal to 42.5, the initial setting time is more than or equal to 45min, the final setting time is less than or equal to 600min, the hydration heat is stable.
  3. 3. The method for preparing the solid waste-based ceramsite according to claim 1 or 2, comprising the following steps: (1) Dry mixing homogenization, namely putting steel slag powder, zeolite powder, biochar, fly ash and silicate cement into a mixer, and uniformly mixing to obtain a mixture; (2) Spray granulating, namely transferring the obtained mixture into a disc granulator, starting a spraying system, continuously spraying sodium silicate solution, and stirring while spraying to obtain ceramsite raw material with the particle size of 5-8 mm; (3) Aging and coagulation accelerating, namely uniformly paving the obtained ceramsite raw material on a tray, wrapping wet gauze, aging in a shady environment to promote uniform permeation of sodium silicate solution, and starting early hydration reaction; (4) Steam curing and natural curing, namely transferring the aged ceramsite raw material into a steam curing box, curing at constant temperature to ensure that the cementing material is fully hydrated to generate a stable C-S-H gel network, transferring the semi-finished ceramsite subjected to steam curing into a closed shady environment, spraying deionized water at regular time every day to keep the surface of the ceramsite moist, and naturally curing for 10-14 days to obtain the solid waste-based ceramsite.
  4. 4. The preparation method of claim 3, wherein in the step (1), the rotating speed of the mixer is 150-220r/min, and the stirring time is 10-20 minutes until the material has uniform color and luster and no obvious particle agglomeration, and the distribution coefficient of each component is ensured to be less than or equal to 5%.
  5. 5. A method according to claim 3, wherein in step (2), the rotational speed of the disk granulator is 15-40r/min, and the inclination angle is 45-55 °; The spraying amount of the sodium silicate solution is 8-15% of the total mass of the mixture, and the spraying rate is 0.5-1.0L/min.
  6. 6. The preparation method of claim 3, wherein in the step (3), the thickness of the ceramic raw material is less than or equal to 5cm, and the moisture content of the wet gauze is 60-70%; The shady and cool environment is specifically that the temperature is 20-25 ℃ and the relative humidity is more than or equal to 85 percent; The aging time is 2-4 hours.
  7. 7. The preparation method of claim 3, wherein in the step (4), the curing temperature of constant temperature curing is 80+/-5 ℃, the relative humidity is more than or equal to 90 percent, the time of constant temperature curing is 6-8 hours, the temperature of a closed cool environment is 25+/-3 ℃, the number of times of spraying deionized water is 1-2, and the water spraying amount is 0.5-1.0mL/g of ceramsite; The compressive strength of the solid waste-based ceramsite is more than or equal to 1.5MPa, the sum of the crushing rate and the wear rate is less than or equal to 3.5%, and the water absorption rate is 12-18%.
  8. 8. The use of the solid waste-based ceramsite according to claim 1 or 2 for removing nitrogen and phosphorus from wastewater.
  9. 9. The use as claimed in claim 8, comprising the steps of: Filling solid waste-based ceramsite into a filter layer of a biological retention facility, controlling the filling height to be 30-50cm, controlling the porosity of the filter layer to be 40-45%, and then performing wastewater treatment; Or filling the wastewater into an advanced treatment adsorption column of a sewage plant, wherein the filling volume is 70-80% of the effective volume of the adsorption column, and then performing wastewater treatment; and when the phosphorus concentration in the effluent is more than or equal to 0.2mg/L and lasts for 3 days, judging that the adsorption is saturated, and obtaining the adsorption saturated ceramsite.
  10. 10. A soil conditioner comprising the adsorptive saturated ceramsite of claim 9, wherein the adsorptive saturated ceramsite has a particle size of 1mm or less, the application ratio is 3-10% of the soil mass, and the mixing depth is 10-20cm.

Description

Solid waste-based ceramsite, preparation method thereof and application thereof in nitrogen and phosphorus removal and soil improvement Technical Field The invention relates to the technical fields of industrial solid waste resource utilization, water body pollution treatment and soil improvement, in particular to a solid waste-based ceramsite, a preparation method thereof and application thereof in nitrogen and phosphorus removal and soil improvement. Background Phosphorus is a key limiting factor leading to eutrophication. Most of the existing water dephosphorization materials are single-function adsorbents, secondary pollution is easy to cause after adsorption saturation, and phosphorus resources are not effectively recovered. Meanwhile, the traditional phosphate fertilizer has high energy consumption and large pollution, and the stockpiling of industrial solid wastes (steel slag, fly ash and the like) occupies land and pollutes environment. Meanwhile, the existing ceramsite preparation mostly adopts a sintering process, so that the energy consumption is high, the cost is high, the function is single, and the closed-loop utilization of 'water purification-phosphorus resource recovery-soil improvement' is difficult to realize. Therefore, the baking-free, low-cost and double-function ceramsite based on industrial solid wastes is developed, the efficient removal and recycling of phosphorus are realized, and the environment-friendly and economic values are important. The invention relates to the technical fields of industrial solid waste resource utilization, water pollution treatment and soil improvement, in particular to preparation of functional baking-free ceramsite and dual-functional application thereof in water dephosphorization and soil improvement. The ceramsite is prepared from industrial solid wastes such as steel slag and fly ash serving as main raw materials through a baking-free process, and has the core application of being used as an adsorption material to be filled in the scenes such as biological detention facilities, advanced treatment systems of sewage plants and the like so as to realize the efficient removal of phosphorus in water bodies, and after adsorption saturation, the ceramsite can be directly used as a soil conditioner for phosphorus deficiency soil due to the enrichment of phosphorus elements, biochar, zeolite and other components contained in the ceramsite, so as to provide slow-release phosphorus nutrition for plants and improve the soil structure, and finally realize multi-objective coordination of industrial solid waste emission reduction, water body purification, phosphorus resource recovery and soil fertility improvement. Chinese patent No. CN120698764A, entitled "preparation method of composite ceramsite with good nitrogen and phosphorus adsorption property", discloses a method for preparing nitrogen and phosphorus adsorption ceramsite by using fly ash, bentonite and corn straw as raw materials. The adsorption removal of nitrogen and phosphorus in the water body is realized by utilizing the industrial solid waste property of the fly ash, the cohesiveness of bentonite and a porous structure formed by pyrolysis of corn straw. The technology realizes the cooperative utilization of industrial solid waste and agricultural waste, reduces the cost of the ceramsite raw materials, but has obvious limitations that firstly, the technology adopts a preheating and high-temperature sintering process, the sintering temperature reaches 700 ℃, the energy consumption is higher, and the development requirements of energy conservation and consumption reduction are not met. Secondly, the function is single, only nitrogen and phosphorus adsorption removal of the water body is focused, recycling of the ceramsite after adsorption saturation is not considered, the ceramsite after adsorption saturation is easy to become solid waste, phosphorus resource waste is caused, and secondary pollution is possibly caused. Summarizing, the prior art generally has the defect of "single function". They either focus on terminal management but produce new solid waste, or focus on agricultural applications but rely on primary resources and ignore sources of pollution. At present, a technical scheme capable of efficiently and internally coupling two links of 'dephosphorization of water body' and 'recycling of phosphorus resources' in the life cycle of the same material is not available, namely, an environment functional material capable of efficiently adsorbing phosphorus in water body, and directly, safely and effectively serving as a soil conditioner and a sustained-release phosphate fertilizer for saturated products is not available. Disclosure of Invention The invention provides a solid waste-based ceramsite, a preparation method thereof and application thereof in nitrogen and phosphorus removal and soil improvement, and aims to solve the technical problems that a single filler adsorbent is low in adsorption