A method for preparing a porous ozone catalyst based on seamless mud sinking and hot rolling of mud

Abstract

This invention discloses a method for preparing a porous ozone catalyst based on seamless sludge and hot-rolled sludge, comprising drying, grinding, granulation, and sintering. A mixture of seamless sludge and hot-rolled sludge is subjected to the drying, grinding, and granulation processes to obtain granules. The granules are then sintered under an inert atmosphere at a temperature of 600℃–800℃ for 3–5 hours. This method effectively solves the problems of volume reduction and resource utilization of seamless sludge and Fenton sludge, and provides a low-cost and highly effective production route for a porous ozone catalyst.

Description

Technical Field

[0001] This invention relates to ozone catalysts for wastewater treatment, specifically a method for preparing porous ozone catalysts based on metallurgical solid waste. Background Technology

[0002] Ozone catalytic oxidation technology utilizes a catalyst to catalyze ozone to generate highly oxidizing hydroxyl radicals (·OH), thereby rapidly degrading organic matter in water. Due to its advantages such as being clean and pollution-free, having high oxidation efficiency, and being simple to operate, it has become one of the key technologies for removing highly stable and recalcitrant organic matter from wastewater and has gained increasing favor in advanced wastewater treatment.

[0003] In the steel industry, a large amount of iron-containing solid waste is generated. In the seamless steel pipe production process, graphite emulsion is added as a lubricant during seamless pipe threading. The graphite emulsion, iron oxide scale, lubricating oil, and rolling mill cooling spray water mix together and enter the circulating water system. This graphite-containing circulating water is directly recycled after being treated in a horizontal flow sedimentation tank and by side filtration. The settled seamless sludge contains a large amount of graphite and oil, making direct recycling difficult. Additionally, iron oxide scale generated during hot rolling in the steel industry is washed off by high-pressure water into a trench. After passing through a vortex well, it settles in a horizontal flow tank. These fine iron oxide particles, carrying lubricating oil, rolling oil, and water, settle to the bottom of the horizontal flow tank, forming hot-rolled sludge. Hot-rolled sludge is mainly bottom sediment from the horizontal flow tank, containing water, oil, and iron oxides, with a dry basis oil content generally ranging from 5% to 20%. Related literature reports that the oil in hot-rolled sludge contains 55% alkanes and alkenes, and 22% carboxylic acids, ketones, and aromatic hydrocarbons. The total iron content of hot-rolled sludge after burning is generally 67%–72%. Due to differences in hot rolling process equipment and other factors, the oil consumption per ton of steel billet varies, resulting in a large fluctuation range in the oil content of hot-rolled sludge. Based on the relationship between steel production and hot-rolled sludge production at several domestic hot-rolling plants, and combined with the national hot-rolled product output, it is estimated that approximately 1.2 million tons of hot-rolled sludge are generated annually in China. Because of its high oil content, this hot-rolled sludge is difficult to recycle directly.

[0004] Currently, some methods for preparing ozone catalysts using solid waste have been disclosed. For example, CN 113713818 A discloses a solid waste-based heterogeneous ozone catalyst and its preparation method; CN 112191248 A discloses a catalyst for ozone oxidation treatment of wastewater containing solid waste and its preparation method. However, there are no reports on how to prepare ozone catalysts using seamless sludge from seamless steel plants and hot-rolled sludge generated during hot rolling production. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing porous ozone catalysts based on seamless sludge and hot-rolled sludge, which solves the problems of volume reduction and resource utilization of seamless sludge and Fenton sludge, and provides a production route for porous ozone catalysts with low cost and good catalytic effect.

[0006] To achieve the above-mentioned objective, the method for preparing a porous ozone catalyst based on seamless sludge and hot-rolled sludge includes drying, grinding, granulation, and sintering, wherein:

[0007] The mixture of seamless sludge and hot-rolled sludge is dried, ground, and granulated to obtain granules. The granules are then sintered under an inert atmosphere at a temperature of 600°C to 800°C for 3 to 5 hours.

[0008] In this disclosure and possible embodiments, the oil content of the granules is about 8% to 27%.

[0009] In this disclosure and possible embodiments, the drying process includes:

[0010] The hot-rolled sludge and the seamless sediment are heated at 80℃~90℃ for 9h~11h, and then mixed at a mass ratio of 1:0.2~0.6. After mixing, the mixture is heated at 80℃~90℃ for 1.5h~2.5h to obtain dried metallurgical solid waste.

[0011] In this disclosure and possible embodiments, the grinding method includes:

[0012] The metallurgical solid waste is ground, sieved, and then mixed in a ball mill.

[0013] In this disclosure and possible embodiments, the sieving to 0.2 mm or less and the mixing time are 1 h to 2 h.

[0014] In this disclosure and possible embodiments, the granulation method includes:

[0015] Water is added to the metallurgical solid waste after the grinding process, and the granules are granulated using a granulation device to obtain granules with a diameter of 3 mm to 6 mm.

[0016] In this disclosure and possible embodiments, water of 15% to 35% by mass is added to the metallurgical solid waste.

[0017] In this disclosure and possible embodiments, the granules are dried at a temperature of 80°C to 90°C.

[0018] In this disclosure and possible embodiments, the hot-rolled sludge has an oil content of 5%–15%, a water content of 15%–25%, an iron content of 60%–75%, a silicon dioxide content of 0.5%–1.5%, an aluminum oxide content of 0.1%–0.8%, a calcium oxide content of 0.1%–0.4%, a magnesium oxide content of 0.05%–0.2%, and a manganese oxide content of 0.2%–1%.

[0019] In this disclosure and possible embodiments, the seamless sludge has an oil content of 5% to 25%, a water content of 10% to 35%, a total iron content of 15% to 35%, and a graphite content of 13% to 45%.

[0020] The beneficial effects of this invention are:

[0021] This invention discloses a method for preparing porous ozone catalysts based on seamless sludge and hot-rolled sludge. The porous ozone catalyst obtained by sintering the seamless sludge and hot-rolled sludge possesses numerous pores and a carbonized structure, resulting in a large specific surface area. The carbonized structure enhances the adsorption and degradation capacity for organic matter. Furthermore, the seamless sludge and hot-rolled sludge contain various heavy metals and organic matter, which, after high-temperature processing, form oxygen-containing functional groups with redox activity, as well as transition metals and their oxides. These components are dispersed and stabilized within the material through high-temperature processing and can act as a catalyst matrix or support to promote electron transfer. The abundant surface functional groups provide numerous active sites for the reaction, thereby improving… High catalytic performance; in addition, seamless sludge contains abundant graphite, and graphitic materials are also formed after the seamless sludge and hot-rolled sludge are sintered and carbonized, which increases the content of graphitic materials in the catalyst. The high degree of graphitization improves the electron transfer ability between the catalyst and the substrate material, increases the content of oxidizing substances such as hydroxyl radicals generated by electron transfer, and increases the electron transfer rate in the system, thereby promoting the catalytic ozone oxidation degradation ability; therefore, this invention provides a new, low-cost and highly effective porous ozone catalyst production method, and effectively solves the problems of harmlessness, volume reduction and resource utilization of seamless sludge and Fenton sludge. Detailed Implementation

[0022] The present disclosure is described below based on embodiments; however, it is worth noting that the present disclosure is not limited to these embodiments. In the detailed description of the present disclosure below, certain specific details are described in detail. However, those skilled in the art will fully understand the present disclosure for the parts not described in detail.

[0023] The hot-rolled sludge used in the following embodiments of this disclosure is waste material accumulated at the bottom of the horizontal flow pool during the hot rolling process in the steel industry. Its composition, by mass percentage, includes 5%–15% oil, 15%–25% water, 60%–75% total iron, 0.5%–1.5% silica, 0.1%–0.8% aluminum oxide, 0.1%–0.4% calcium oxide, 0.05%–0.2% magnesium oxide, and 0.2%–1% manganese oxide. The seamless sludge used is waste material accumulated at the bottom of the horizontal flow pool during the production of seamless steel pipes in the steel industry. Its composition, by mass percentage, includes 5%–25% oil, 10%–35% water, 15%–35% total iron, and 13%–45% graphite.

[0024] The present disclosure discloses a method for preparing porous ozone catalysts based on seamless sludge and hot-rolled sludge. Specifically, the catalysts are prepared using the aforementioned hot-rolled sludge and seamless sludge through steps of drying, grinding, mixing, pelletizing, drying, and sintering. The process steps are as follows:

[0025] (1) Drying: Hot-rolled oil sludge and seamless sludge are placed in an oven and heated to 80℃~90℃ for 9h~11h. Then, hot-rolled oil sludge and seamless sludge are mixed at a mass ratio of 1:0.2~0.6, stirred evenly, and dried for another 1.5~2.5 hours to obtain dried metallurgical solid waste. The heating and drying temperature is 80℃~90℃ to avoid the decomposition of oily substances in hot-rolled oil sludge and seamless sludge.

[0026] (2) Grinding: The dried metallurgical solid waste is ground and sieved to 0.2 mm or less using a pulverizing mill;

[0027] (3) Mixing: The metallurgical solid waste after grinding and sieving is mixed for 1 hour using a ball mill mixer;

[0028] (4) Granulation: Add water at a mass ratio of 15% to 35% to the mixed metallurgical solid waste, and use a granulation equipment to granulate the material in a disc. The diameter of the granules obtained by granulation is 3mm to 6mm.

[0029] Because hot-rolled sludge and seamless sludge contain a large amount of oily substances, which are preserved after low-temperature drying, they can act as a binder, eliminating the need for additional binders.

[0030] (5) Drying: Place the granules in an oven and dry them at 80℃~90℃;

[0031] (6) Sintering: The dried granules are placed in a sealed graphite crucible, which is then placed in a high-temperature dry distillation apparatus, or the material is placed directly in a high-temperature dry distillation apparatus protected by a nitrogen atmosphere. The high-temperature dry distillation apparatus is heated to 600℃~800℃ and kept at that temperature for 3h~5h to produce porous ozone catalyst particles.

[0032] Example 1

[0033] (1) Place hot-rolled sludge and seamless sludge in an oven and heat at 80°C for 10 hours. Then mix the hot-rolled sludge and seamless sludge at a mass ratio of 1:0.2, stir evenly, and continue heating for 2 hours to obtain dry metallurgical solid waste.

[0034] (2) The dried metallurgical solid waste is ground and sieved to 0.2 mm or less using a pulverizing mill;

[0035] (3) After grinding and sieving, the metallurgical solid waste is further mixed using a ball mill mixer for 1 hour;

[0036] (4) After adding 15% water to the mixed metallurgical solid waste, the material is granulated by disc granulation equipment, and the diameter of the granules obtained by granulation is 3mm.

[0037] Hot-rolled oily sludge and seamless sludge contain a large amount of oily substances, which are preserved after low-temperature drying. These oily substances act as a binder during the mixing process, eliminating the need for additional binders. Therefore, this method can both reduce the production cost of catalysts and realize the resource utilization of sludge.

[0038] (5) Place the granules in an oven and dry them at 80°C;

[0039] (6) The dried granules are placed in a sealed graphite crucible, which is then placed in a high-temperature dry distillation apparatus or directly in a high-temperature dry distillation apparatus protected by a nitrogen atmosphere. The high-temperature dry distillation apparatus is heated to 600°C and kept at that temperature for 3 hours to achieve the purpose of sintering the granules, thus obtaining the porous ozone catalyst of Example 1.

[0040] (7) The specific surface area of ​​the porous ozone catalyst prepared in Example 1 is 198 m². 2 / g, with an average pore size of 18nm.

[0041] (8) The porous ozone catalyst of Example 1 was filled into the catalytic oxidation tower. A quinoline concentration of 70 mg / L aqueous solution was used as simulated wastewater. The wastewater volume was 500 ml, the catalyst dosage was 50 g, the ozone generator power was 12%, the ozone flow rate was 1.0 L / min, and the reaction time was 40 min. The results showed that after catalytic ozone oxidation, the removal rate of quinoline could reach 78.6%, which was more than 25% higher than the pollutant removal efficiency of ozone oxidation alone without catalyst.

[0042] Example 2

[0043] (1) Place hot-rolled sludge and seamless sludge in an oven and heat at 90°C for 10 hours. Then mix the hot-rolled sludge and seamless sludge at a mass ratio of 1:0.4, stir evenly, and continue heating for 2 hours to obtain dry metallurgical solid waste.

[0044] (2) The dried metallurgical solid waste is ground and sieved to 0.2 mm or less using a pulverizing mill;

[0045] (3) The metallurgical solid waste after grinding and sieving is further mixed in a ball mill mixer for 1.5 hours;

[0046] (4) After adding 25% water to the mixed metallurgical solid waste, the material is granulated by disc granulation equipment, and the diameter of the granules obtained by granulation is 4mm.

[0047] (5) Place the granules in an oven and dry them at 85°C;

[0048] (6) Place the dried granules in a sealed graphite crucible, and place the graphite crucible in a high-temperature dry distillation apparatus, or directly in a high-temperature dry distillation apparatus protected by a nitrogen atmosphere. Heat the high-temperature dry distillation apparatus to 700°C and keep it at that temperature for 4 hours to achieve the purpose of sintering the granules, and obtain the porous ozone catalyst of Example 2.

[0049] (7) The porous ozone catalyst prepared in Example 2 has a specific surface area of ​​205 m². 2 / g, with an average pore size of 19nm.

[0050] (8) The porous ozone catalyst of Example 1 was filled into the catalytic oxidation tower. A quinoline concentration of 70 mg / L aqueous solution was used as simulated wastewater. The wastewater volume was 500 ml, the catalyst dosage was 50 g, the ozone generator power was 12%, the ozone flow rate was 1.0 L / min, and the reaction time was 40 min. The results showed that after catalytic ozone oxidation, the removal rate of quinoline could reach 79.5%, which was more than 25% higher than the degradation efficiency of ozone oxidation alone without catalyst.

[0051] Example 3

[0052] (1) Place hot-rolled sludge and seamless sludge in an oven and heat at 90°C for 10 hours. Then mix the hot-rolled sludge and seamless sludge at a mass ratio of 1:0.6, stir evenly, and continue heating for 2 hours to obtain dry metallurgical solid waste.

[0053] (2) The dried metallurgical solid waste is ground and sieved to 0.2 mm or less using a pulverizing mill;

[0054] (3) After grinding and sieving, the metallurgical solid waste is further mixed in a ball mill for 2 hours;

[0055] (4) After adding 35% water to the mixed metallurgical solid waste, the material is granulated by disc granulation equipment, and the diameter of the granules obtained by granulation is 6mm.

[0056] (5) Place the granules in an oven and dry them at 90°C;

[0057] (6) The dried granules are placed in a sealed graphite crucible, which is then placed in a high-temperature dry distillation apparatus or directly in a high-temperature dry distillation apparatus protected by a nitrogen atmosphere. The high-temperature dry distillation apparatus is heated to 800°C and kept at that temperature for 5 hours to achieve the purpose of sintering the granules, thus obtaining the porous ozone catalyst of Example 3.

[0058] (7) The porous ozone catalyst prepared in Example 3 has a specific surface area of ​​211 m². 2 / g, with an average pore size of 19nm.

[0059] (8) The porous ozone catalyst of Example 1 was filled into the catalytic oxidation tower. A quinoline concentration of 70 mg / L aqueous solution was used as simulated wastewater. The wastewater volume was 500 ml, the catalyst dosage was 50 g, the ozone generator power was 12%, the ozone flow rate was 1.0 L / min, and the reaction time was 40 min. The results showed that after catalytic ozone oxidation, the removal rate of quinoline could reach 80.3%, which was more than 25% higher than the degradation efficiency of ozone oxidation alone without catalyst.

[0060] The embodiments described above are merely illustrative of implementation methods of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent disclosure. It should be noted that those skilled in the art can make various modifications, equivalent substitutions, and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent disclosure should be determined by the appended claims.

Claims

1. A method for preparing porous ozone catalyst based on seamless sludge and hot-rolled sludge, comprising drying, grinding, granulation and sintering, characterized in that: The mixture of seamless sludge and hot-rolled sludge is dried, ground and granulated to obtain granules. The granules are then sintered under an inert atmosphere at a temperature of 600°C to 800°C for 3 to 5 hours. The hot-rolled sludge is waste material that accumulates at the bottom of the horizontal flow tank during the hot rolling process in the steel industry. By mass percentage, it contains 5%–15% oil, 15%–25% water, 60%–75% total iron, 0.5%–1.5% silicon dioxide, 0.1%–0.8% aluminum oxide, 0.1%–0.4% calcium oxide, 0.05%–0.2% magnesium oxide, and 0.2%–1% manganese oxide. The seamless sludge is waste material that accumulates at the bottom of the horizontal flow tank during the production of seamless steel pipes in the steel industry. By mass percentage, it contains 5%–25% oil, 10%–35% water, 15%–35% total iron, and 13%–45% graphite.

2. The method for preparing porous ozone catalyst based on seamless sludge and hot-rolled sludge according to claim 1, characterized in that: The oil content of the granules is 8% to 27%.

3. The method for preparing porous ozone catalyst based on seamless sludge and hot-rolled sludge according to claim 1 or 2, characterized in that, The drying process includes: The hot-rolled sludge and the seamless sediment are heated at 80℃~90℃ for 9h~11h, and then mixed at a mass ratio of 1:0.2~0.

6. After mixing, the mixture is heated at 80℃~90℃ for 1.5h~2.5h to obtain dried metallurgical solid waste.

4. The method for preparing porous ozone catalyst based on seamless sludge and hot-rolled sludge according to claim 3, characterized in that, The grinding method includes: The metallurgical solid waste is ground, sieved, and then mixed in a ball mill.

5. The method for preparing porous ozone catalyst based on seamless sludge and hot-rolled sludge according to claim 4, characterized in that: The material is sieved to a thickness of 0.2 mm or less, and the mixing time is 1 h to 2 h.

6. The method for preparing porous ozone catalyst based on seamless sludge and hot-rolled sludge according to any one of claims 1, 2, 4 and 5, characterized in that, The granulation method includes: Water is added to the metallurgical solid waste after the grinding process, and the granules are granulated using a granulation device to obtain granules with a diameter of 3 mm to 6 mm.

7. The method for preparing porous ozone catalyst based on seamless sludge and hot-rolled sludge according to claim 6, characterized in that: Add water at a mass ratio of 15% to 35% to the metallurgical solid waste.

8. The method for preparing porous ozone catalyst based on seamless sludge and hot-rolled sludge according to claim 7, characterized in that: The granules are dried at a temperature of 80°C to 90°C.