Porous phosphorus removal ceramicite, its preparation method and application

Abstract

The present application belongs to the technical field of ceramic filter material, and provides a porous phosphorus removal ceramic and a preparation method and application thereof, wherein active raw material 8-10%, rare earth oxide 7-10%, bottom mud 40-60%, stone powder 15-26%, graphene 5-6%, pore-forming agent 2-4% and binder 3-4% are respectively dried, crushed and then uniformly mixed, followed by granulating and drying the mixture, and then sintering and cooling to prepare the porous phosphorus removal ceramic filter material; the phosphorus removal ceramic filter material prepared by the present application has strong adsorption performance and fast adsorption rate for phosphorus, large adsorption capacity, and low production cost; by adding CeO2 and La2O3, or Ca, Mg and Fe, or bottom mud and stone powder, the porosity and cylinder pressure strength of the ceramic filter material are promoted, the reduction of municipal sewage sludge is realized, the preparation equipment adopts kiln design and heat exchange device, waste heat is recycled and reused, and the generation of dioxin and other chlorinated polynuclear aromatic compounds and nitrogen oxides is reduced, which is conducive to reducing the operation cost of environmental protection process, and solving the environmental protection problem caused by the production of ceramic.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental protection treatment, in particular to a porous phosphorus removal ceramsite and a preparation method and application thereof. BACKGROUND

[0002] Low-concentration phosphorus-containing wastewater is discharged into rivers, lakes and other slow-flowing water bodies, which can cause water quality deterioration and algae proliferation, resulting in eutrophication of water bodies, seriously endangering aquatic ecosystems and human health. Therefore, it is necessary to reduce the phosphorus content in wastewater. At present, there are many ways to remove phosphorus from wastewater, such as adsorption method. The large specific surface area of the adsorbent can separate phosphorus from water through the attachment of phosphorus on the surface of the adsorbent, ion exchange or surface precipitation process. Not only can the phosphorus in the wastewater be removed, but also the phosphorus in the wastewater can be recycled and reused.

[0003] Among them, the ceramsite filter material belongs to one of the adsorbents. The ceramsite filter material refers to a granular material processed through a series of processes such as drying, batching, powdering, balling, steam pressure curing, high-temperature sintering and powder screening, etc. with natural clay minerals or solid waste as the main raw material and a small amount of additives. However, the adsorption capacity of the existing ceramsite filter material is small and the pore channel is few, which reduces the adsorption performance and adsorption rate of the ceramsite filter material to phosphorus, thereby affecting the phosphorus removal effect and efficiency. In addition, during the traditional ceramsite production process, residual dioxins and other chlorinated polynuclear aromatic compounds are generated, which pollute the surrounding environment, and the production and maintenance costs are high. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a porous phosphorus removal ceramsite and a preparation method and application thereof, to solve the problems of poor phosphorus removal effect and low phosphorus removal efficiency of the ceramsite filter material in the prior art.

[0005] A porous phosphorus removal ceramsite, which comprises the following components in mass percentage: active raw material 8-10%, rare earth oxide 7-10%, bottom mud 40-60%, stone powder 15-26%, graphene 5-6%, pore-forming agent 2-4% and binder 3-4%;

[0006] The active raw material is composed of kaolin, shale, basalt, fly ash and volcanic rock.

[0007] Preferably, the rare earth oxide is CeO2 and La2O3; CeO2 is a variable valence oxide with excellent oxygen storage and release capacity. The active raw material, the bottom mud and the stone powder contain Al2O3, CaO, Fe2O3 and SiO2, etc. CeO2 plays a catalytic role and releases O2 and CO2 and other gases during sintering, which is conducive to the generation of multiple pore channels on the surface of the phosphorus removal ceramsite. La2O3 has good dispersity and can promote the dispersion and catalytic effect of CeO2, further improving the generation of gas.

[0008] Preferably, the bottom sludge is municipal sewage sludge; the main preparation material of the phosphorus removal ceramsite is municipal sewage sludge, and there is no heavy metal ion, which belongs to the field of waste resource utilization. In the sintering process, the bottom sludge is burned to the end, and a through hole with an effective pore size is formed on the ceramsite, which can not only ensure the cylinder pressure strength of the ceramsite, but also is beneficial to the generation of a large number of through hole voids. At the same time, the heat of the bottom sludge can reduce the sintering temperature of the ceramsite in the sintering process, so that the crystallization temperature is further reduced, energy is saved, and the product quality of the ceramsite is improved. Therefore, compared with the traditional ceramsite with a cylinder pressure strength of 1.0 Mpa and a porosity of 40%, the ceramsite prepared by the present application has a cylinder pressure strength of 2.0 Mpa-2.55 Mpa and a porosity of 50%-65%. The bottom sludge adjusts the porosity while reducing the carbon footprint, and provides a path for the reduction and resource utilization of municipal sewage sludge.

[0009] Preferably, the pore-forming agent is prepared by mixing dry umbrella grass and anthracite, and the content ratio of the dry umbrella grass to the anthracite is 1:1. In the sintering process, the organic matter in the pore-forming agent decomposes to generate expansion gas, so as to increase the opening rate of the ceramsite, and thus improve the contact between phosphorus and the effective components in the ceramsite. The anthracite can make the ceramsite surface produce small holes of different sizes, but the roughness is not enough. The dry umbrella grass can improve the roughness of the ceramsite surface. Through the combination of the two, the porosity in the ceramsite is increased, which is beneficial to improve the phosphorus removal effect of the ceramsite.

[0010] Preferably, the binder is montmorillonite or bentonite. Through the setting of montmorillonite or bentonite, the viscosity of the water for granulation in the production of the ceramsite is improved, and the water bonding capacity for various materials is improved, which is beneficial to the molding of the ceramsite.

[0011] Preferably, Ca, Mg and Fe additives are added in the components of the phosphorus removal ceramsite. Ca can react with PO4 3- to produce Ca3(PO4)2precipitate, and Mg and Fe form Fe2O3and MgO in the sintering process. Fe2O3and MgO have the ability to absorb phosphorus, so as to improve the adsorption performance of the ceramsite to phosphorus and long-term slow-release effect of the absorption of phosphorus.

[0012] The above porous phosphorus removal ceramsite is applied in the fields of ecological restoration, soil remediation and sewage treatment.

[0013] A preparation method of the porous phosphorus removal ceramsite is provided.

[0014] S1: pretreatment, placing the above components in a low-temperature kiln for drying treatment, and the drying temperature is 200℃. After drying, the active raw material, the bottom sludge and the stone powder are subjected to crushing treatment, and can pass through a 100 mesh sieve;

[0015] S2: mixing, the components after pretreatment in S1 are weighed according to the specified ratio, and after weighing, they are placed in a stirrer for uniform mixing to obtain a mixture;

[0016] S3: granulation, the mixture obtained in S2 is added to the granulator in batches, and during the granulation process, atomized water is sprayed every time the mixture is added, so as to obtain the raw ceramsite;

[0017] S4: drying, the raw ceramsite obtained in S3 is placed in an oven and dried at 65°C for 6h;

[0018] S5: sintering, then the raw ceramsite is placed in a high-temperature kiln, preheated to 200°C, then heated to 600-800°C at a heating rate of 5-7°C / min, the whole sintering time is set to 2-4h, and then naturally cooled to obtain the porous phosphorus removal ceramic material.

[0019] Preferably, in the S5, the sintering temperature is set to 700°C, the sintering heating rate is set to 6°C / min, and the sintering time is set to 3h; if the sintering temperature is too high, the metal ions such as AI 3+ and Ca 2+ in the phosphorus removal ceramic component will react with SiO2 to produce stable silicate substances, and if the heating rate is too fast, large pores will be formed on the surface of the ceramsite, reducing the specific surface area and adsorption sites of the ceramsite, and too long or too short sintering time will cause the component material to block the pore channel, thereby reducing the adsorption and phosphorus removal effect of the ceramsite.

[0020] Preferably, in the S5, a heat exchange device is arranged at the tail of the high-temperature kiln; by arranging the heat exchange device, the hot air in the high-temperature kiln is introduced into the low-temperature kiln through the pipeline, so as to realize waste heat recovery and reuse, and the low-temperature kiln dries the water content of the sediment to 48.69%-58.93%, for example, the low calorific value of the sediment with a water content of about 48% is about 3126 large calories, by arranging the heat exchange, the fuel cost is about 0.7-0.8 kg of ash, 10-15% of biomass fuel, compared with the traditional ceramsite preparation, the fuel cost of each cubic meter of ceramsite preparation can be reduced by 15%-25%, therefore, by designing the kiln, it is beneficial to reduce the carbon footprint and achieve the effect of energy saving and emission reduction.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. The main components of the phosphorus-removing ceramsite prepared by this invention are bottom mud and stone powder. The bottom mud and stone powder come from urban (municipal) sewage sludge and quarry, which are all wastes. This achieves the purpose of turning waste into treasure. The bottom mud can reduce the sintering temperature of the ceramsite, which further reduces the crystallization temperature, saves energy and improves the product quality of the ceramsite. At the same time, it can also increase the porosity and cylinder compressive strength of the ceramsite, reduce the carbon footprint, and provide a path for the reduction and resource utilization of urban (municipal) sewage sludge.

[0023] 2. This invention adds Ca, Mg, and Fe to the expanded clay aggregate component. Ca can react with PO4. 3- A chemical reaction occurs to produce Ca3(PO4)2 precipitate. Mg and Fe form Fe2O3 and MgO during sintering. Fe2O3 and MgO have the ability to absorb phosphorus, thereby improving the phosphorus removal effect and efficiency of ceramsite filter media.

[0024] 3. This invention adds CeO2 and La2O3 to the ceramsite composition. CeO2 is a variable-valence oxide with oxygen storage and release capabilities. The active raw materials, sediment, and stone powder contain components such as Al2O3, CaO, Fe2O3, and SiO2. CeO2 acts as a co-catalyst. During sintering, CeO2 reacts with these components and releases gases such as O2 and CO2, which helps to create multiple pores on the surface of the phosphorus removal ceramsite. La2O3 has good dispersibility and can promote the dispersion and catalytic effect of CeO2, further increasing gas generation, thereby improving the phosphorus adsorption performance and adsorption rate of the ceramsite filter media.

[0025] 4. This invention reduces the fuel cost of low-temperature kilns through kiln design. At the same time, by controlling the temperature of the low-temperature kiln and the sintering temperature and sintering time of the ceramsite raw material in the high-temperature kiln, it reduces the generation of dioxins and other chlorinated polynuclear aromatic compounds and nitrogen oxides, which helps to reduce the operating cost of environmentally friendly processes and solve the environmental problems caused by the production of ceramsite. Attached Figure Description

[0026] Figure 1 This is a flowchart of the preparation method of phosphorus removal ceramic filter media in this invention;

[0027] Figure 2 This is a structural diagram of the high-temperature kiln used in the preparation of phosphorus removal ceramic filter media in this invention; Detailed Implementation

[0028] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0029] Example 1:

[0030] A method for preparing porous phosphorus removal ceramic particles includes the following steps:

[0031] S1: Preprocessing, placing the active raw materials, rare earth oxides, sludge, stone powder, graphene, pore-forming agent and binder in a low-temperature kiln for drying treatment, the drying temperature is 200°C, wherein the active raw materials, sludge and stone powder are crushed after drying, and can pass through a 100 mesh sieve;

[0032] S2: Mixing, the components after preprocessing in S1 are weighed according to the ratio of active raw materials 8%, rare earth oxides 7%, sludge 60%, stone powder 15%, graphene 5%, pore-forming agent 2% and binder 3%, and then placed in a stirrer for uniform mixing to obtain a mixture;

[0033] S3: Granulation, the mixture obtained in S2 is added to a granulator in batches, and water is sprayed during each addition of the mixture to obtain raw ceramsite;

[0034] S4: Drying, the raw ceramsite obtained in S3 is placed in an oven and dried at 65°C for 6h;

[0035] S5: Sintering, then the raw ceramsite is placed in a high-temperature kiln, preheated to 200°C, then heated to 600°C at a rate of 5°C / min, the entire sintering time is set to 2h, and then naturally cooled to obtain a porous phosphorus removal ceramic.

[0036] In the process of making ceramsite, two kiln lines are provided, one is a low-temperature kiln about 30m long, mainly used in preprocessing (S1), and the moisture content of the component ratio material is dried to between 48.69%-58.93%, and 59% is the self-sustaining combustion critical moisture content;

[0037] The other is a high-temperature kiln, as shown in Figure 2 The entire kiln body rotates under two kinds of transmission devices, and the raw ceramsite moves from low to high; the kiln body is about 60m long, of which 24m is a low-temperature section, the low-temperature section has a large kiln pipe opening, and the low-temperature section is composed of an entering zone of 2.5m, a preheating zone (transition zone) of 18m and a partial high-temperature zone of 3.5m, and 36m is a sintering section, the sintering section has a small kiln pipe opening, and the sintering section is composed of a partial high-temperature zone of 16.5m, a cooling zone of 17m and an exit zone of 2.5m;

[0038] Meanwhile, in the structure of the high-temperature kiln, the entering zone and the exit zone are composed of steel fiber structure and castable structure from inside to outside, the preheating zone (transition zone) and the cooling zone are composed of two-stage high-alumina brick structure, one-stage high-alumina brick structure and three-stage high-alumina brick structure from inside to outside, and the high-temperature zone is composed of phosphate brick structure, silicon-mullite brick structure and three-stage high-alumina brick structure from inside to outside;

[0039] The high-temperature kiln mainly sinter the ceramic raw material (shaped granular material) into ceramic particles, and is mainly used in sintering (S5);

[0040] In the low-temperature kiln, since the temperature is controlled within 200 degrees, the drying of the component proportioning material will not produce dioxin and other chlorinated polynuclear aromatic compounds and nitrogen oxides;

[0041] In the high-temperature kiln, the ceramic raw material passes through a 24m low-temperature section, and since the temperature gradually rises, the dioxin and other chlorinated polynuclear aromatic compounds in the sludge in the ceramic raw material will be produced, but will start to melt at around 350℃, and will start to decompose at 700℃, and then will be sintered in the 36m sintering section for 2h or more, so that the above-mentioned compounds are thermally decomposed during the preparation of ceramic particles, which is beneficial to reduce the environmental protection process operation cost, solve the environmental protection problem carried by the production of ceramic particles, and belongs to a green production process and equipment.

[0042] Example Two:

[0043] The difference from Example 1 is that in the S2, the component proportioning is: active raw material 9%, rare earth oxide 8%, sludge 50%, stone powder 20%, graphene 6%, pore-forming agent 3%, and binder 4%.

[0044] Example Three:

[0045] The difference from Example 1 is that in the S2, the component proportioning is: active raw material 10%, rare earth oxide 10%, sludge 40%, stone powder 26%, graphene 6%, pore-forming agent 4%, and binder 4%.

[0046] Example Four:

[0047] The difference from Example 1 is that in the S5, the temperature rising speed is 6℃ / min.

[0048] Example Five:

[0049] The difference from Example 1 is that in the S5, the temperature rising speed is 7℃ / min.

[0050] Example Six:

[0051] The difference from Example 1 is that in the S5, the sintering temperature is 700℃.

[0052] Example Seven:

[0053] The difference from Example 1 is that in the S5, the sintering temperature is 800℃.

[0054] Example Eight:

[0055] The difference from Example 1 is that in the S5, the sintering time is 3h.

[0056] Example Nine:

[0057] The difference from Example 1 is that in the S5, the sintering time is 4h.

[0058] Example Ten:

[0059] The difference from Example 1 is that in the S2, CeO2 and La2O3 are added in the phosphorus removal ceramic filter material component.

[0060] Example Eleven:

[0061] The difference from Example 1 is that in the S2, Ca, Mg and Fe are added in the phosphorus removal ceramic filter material component.

[0062] Example Twelve:

[0063] The difference from Example 1 is that in the S2, no sludge component is added in the phosphorus removal ceramic filter material component.

[0064] Take 0.5g of the porous phosphorus removal ceramic filter material prepared in each of the above examples, and then add it to a corresponding 100mL centrifuge tube, then add 20mL of KH2PO4 solution with a phosphorus concentration of 2mg / L in the centrifuge tube, then oscillate for 24h at 25℃, then centrifuge at 8000r / min for 10min, take the supernatant, and measure the phosphorus concentration and related aspects of the phosphorus removal ceramic filter material by a multifunctional adsorption instrument and molybdenum antimony anti-colorimetric method, etc., as shown in Table 1:

[0065]

[0066]

[0067] As can be seen from the table data, by comparing Example One, Example Two and Example Three, the rare earth oxides and Ca in the stone powder help to improve the porosity of the phosphorus removal ceramic filter material, thereby helping to improve the phosphorus removal performance and efficiency of the phosphorus removal ceramic filter material;

[0068] By comparing Example One, Example Four and Example Five, by comparing Example One, Example Six and Example Seven, and by comparing Example One, Example Eight and Example Nine, it can be seen from the comparison of the three groups that the heating rate is 6℃ / min, the sintering temperature is 700℃, and the sintering time is 3h, which is conducive to the formation of ceramic surface pores, thereby improving the adsorption and phosphorus removal effect of the phosphorus removal ceramic filter material;

[0069] By comparing example one with example ten, by comparing example one with example eleven, and by comparing the two groups, it is known that adding CeO2 and La2O3, Ca, Mg and Fe auxiliary components, helps to improve the adsorption performance and adsorption rate of phosphorus of the phosphorus removal ceramic filter material, and also plays a promoting role on the phosphorus removal effect and efficiency.

[0070] By comparing example one with example twelve, it is known that adding the bottom mud component helps to improve the cylinder pressure strength and porosity of the phosphorus removal ceramic, and is beneficial to improve the product quality of the phosphorus removal ceramic.

[0071] The embodiments of the present application are given for example and description, although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and modifications to the above embodiments within the scope of the present application.

Claims

1. A porous phosphorus removal ceramic particle, characterized in that: The phosphorus removal ceramic particles are prepared from the following components by mass percentage: 8-10% active raw materials, 7-10% rare earth oxides, 40-60% sediment, 15-26% stone powder, 5-6% graphene, 2-4% pore-forming agent and 3-4% binder; The active raw materials are composed of kaolin, shale, basalt, fly ash and volcanic rock; The rare earth oxides are CeO2 and La2O3; The bottom sediment is urban sewage sludge. The pore-forming agent is prepared by mixing umbrella grass and anthracite, and the content ratio of umbrella grass to anthracite is 1:

1. The phosphorus-removing ceramic particles contain Ca, Mg, and Fe additives. The sintering temperature during the preparation of the phosphorus-removing ceramic particles is 600-800℃.

2. The porous phosphorus removal ceramic particles as described in claim 1, characterized in that: The binder is montmorillonite or bentonite.

3. The application of the porous phosphorus removal ceramic particles as described in claim 1 or 2 in the field of ecological restoration.

4. A method for preparing porous phosphorus removal ceramic particles as described in claim 1 or 2, characterized in that, The specific steps of this method are as follows: S1: Pretreatment, each component is placed in a low-temperature kiln for drying at a temperature of 200℃. The active raw materials, bottom mud and stone powder are then pulverized after drying and can pass through a 100-mesh sieve. S2: Mixing. Weigh the pretreated components from S1 according to the specified ratio, place them in a mixer and mix them evenly to obtain a mixture. S3: Granulation. The mixture obtained in S2 is added to the granulator in several batches. During the granulation process, atomized water is sprayed each time the mixture is added to obtain ceramsite raw material. S4: Drying. Place the ceramsite raw material obtained in S3 in an oven and dry it at 65℃ for 6 hours. S5: Sintering. Then, place the ceramsite raw material in a high-temperature kiln and preheat it to 200℃. Then, raise the temperature to 600-800℃ at a rate of 5-7℃ / min. The entire sintering time is set to 2-4 hours. After the sintering is completed, allow it to cool naturally to obtain porous dephosphorization ceramsite.

5. The method for preparing porous phosphorus removal ceramic particles as described in claim 4, characterized in that: In S5, the sintering temperature is set to 700℃, the sintering heating rate is set to 6℃ / min, and the sintering time is set to 3h.

6. The method for preparing porous phosphorus removal ceramic particles as described in claim 4, characterized in that: In S5, a heat exchange device is provided at the tail end of the high-temperature kiln.

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