A method for preparing ozone catalyst based on oil-containing iron sludge
By adding materials such as polyacrylamide and dust from sintering die heads to hot-rolled sludge, a porous ozone catalyst was prepared, solving the problem of solid waste utilization in the steel industry and achieving high-efficiency catalytic performance and resource utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANGANG STEEL CO LTD
- Filing Date
- 2024-03-07
- Publication Date
- 2026-06-30
Abstract
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 popularity in advanced wastewater treatment.
[0003] In the steel industry, a large amount of iron-containing solid waste is generated, most notably the oily iron sludge in the horizontal flow pool of the hot rolling mill. Iron oxide scale generated during the hot rolling process is washed off by high-pressure water and dumped into a drain. After passing through a vortex well, it settles in the horizontal flow pool. These fine iron scale particles, carrying lubricating oil, rolling oil, and water, settle to the bottom of the pool, forming hot-rolled sludge. Hot-rolled sludge is mainly bottom sediment from the horizontal flow pool, 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% to 72%. Due to differences in hot rolling process equipment and other factors, the oil consumption per ton of 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 volume at several domestic hot-rolling mills, and combined with estimates of national hot-rolled product output, approximately 1.2 million tons of hot-rolled sludge are generated annually nationwide. This hot-rolled sludge, due to its high oil content, is difficult to recycle directly.
[0004] Currently, some methods for preparing ozone catalysts using solid waste have been disclosed, such as CN 113713818 A, which discloses a solid waste-based heterogeneous ozone catalyst and its preparation method; CN 112191248 A, which discloses a catalyst for ozone oxidation treatment of wastewater containing solid waste without incineration and its preparation method; and CN 114749186 A, which discloses a method for preparing and applying a hydrothermally supported sludge carbon-based catalyst. However, no reports have been found on the preparation of ozone catalysts using hot-rolled sludge containing iron from the steel industry. Summary of the Invention
[0005] In view of this, the present invention provides a method for preparing ozone catalyst based on oily iron sludge, which solves the problems of harmlessness, volume reduction and resource utilization of hot-rolled sludge from metallurgical solid waste, and innovatively provides a low-cost way to produce ozone catalyst.
[0006] To achieve the above-mentioned objective, the method for preparing an ozone catalyst based on oil-containing iron sludge includes the following steps:
[0007] Polyacrylamide, sintering die head dust, and bentonite are added to dry and pulverized hot-rolled sludge. After continuous stirring for a set time, a mixed material is obtained. The mixed material is dried to a set moisture content and then made into granules. The granules are then carbonized to obtain the ozone catalyst.
[0008] In this disclosure and possible embodiments, the amount of polyacrylamide added, with a mass content of 0.5% to 1.0%, is 1.0L to 1.5L, corresponding to 1kg of dried and pulverized hot-rolled sludge.
[0009] In this disclosure and possible embodiments, the mass ratio of the dried and pulverized hot-rolled sludge to the electrostatic precipitator ash from the sintering plant is 1:0.1 to 0.3.
[0010] In this disclosure and possible embodiments, the amount of bentonite added is 30g to 50g, corresponding to 1kg of dried and pulverized hot-rolled sludge.
[0011] In this disclosure and possible embodiments, the carbonization method includes:
[0012] Nitrogen is used as a protective gas during the carbonization process. The flow rate of nitrogen is 30 mL / (kg·min) to 60 mL / (kg·min), the heating rate is 10℃ / min to 15℃ / min, the carbonization temperature is 600℃ to 800℃, and the carbonization time is 2h to 3h.
[0013] In this disclosure and possible embodiments, the stirring speed is 80 r / min to 200 r / min; the set time is 20 h to 30 h.
[0014] In this disclosure and possible embodiments, the particles are cylindrical, with a length of 0.7cm to 1cm and a diameter of 3mm to 4mm.
[0015] In this disclosure and possible embodiments, the mixed material is dried to the set moisture content at a temperature of 105°C, wherein the set moisture content is 30% to 35%.
[0016] In this disclosure and possible embodiments, the hot-rolled sludge is dried at a temperature of 105°C and then pulverized. The pulverized sludge is then passed through a 100-mesh sieve to obtain the dried and pulverized hot-rolled sludge.
[0017] In this disclosure and possible embodiments, the hot-rolled sludge, by mass percentage, has an oil content of 5%–16%, a water content of 20%–30%, a total iron content of 50%–65%, a silicon dioxide content of 0.4%–1.3%, an aluminum oxide content of 0.1%–0.9%, a calcium oxide content of 0.1%–0.3%, a magnesium oxide content of 0.02%–0.3%, and a manganese oxide content of 0.2%–1%.
[0018] In this disclosure and possible embodiments, the sintering plant electrostatic precipitator ash contains, by mass percentage, 19%–34% total iron, 13%–26% potassium oxide, 4%–15% calcium oxide, 3%–13% sodium oxide, 13%–24% chlorine, 1%–8% silicon dioxide, and 1%–9% carbon.
[0019] The beneficial effects of this invention are:
[0020] The present invention discloses a method for preparing an ozone catalyst based on oily iron sludge. The organic flocculant polyacrylamide, added under stirring, is thoroughly mixed with the hot-rolled oily sludge. This allows sufficient emulsified oil to be adsorbed onto the surface of the long polyacrylamide chains, forming a network structure centered on the polyacrylamide chains. After high-temperature carbonization, a large number of network pores are formed from the catalyst surface to the interior. During wastewater treatment, this allows wastewater to easily enter the catalyst, increasing its porosity and improving catalytic performance. Furthermore, the added electrostatic precipitator ash from the sintering plant, rich in alkali metals such as potassium, sodium, and calcium, can open and expand pores during the high-temperature carbonization process. This method not only enables activated carbon to generate more alkaline groups, but also effectively increases the specific surface area and porosity of the catalyst, thereby enhancing its catalytic performance. Furthermore, the stirring process of the iron-containing sludge disperses large oil droplets, ensuring uniform distribution of dispersed and emulsified oil within the hot-rolled sludge. High-temperature carbonization then forms more, more uniform, and smaller micropores, further improving the catalyst's catalytic performance. Therefore, this method innovatively provides a low-cost, high-performance production route for ozone catalysts, while effectively addressing the issues of harmlessness, volume reduction, and resource utilization of metallurgical solid waste hot-rolled sludge. Detailed Implementation
[0021] 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.
[0022] This disclosure further illustrates the method for preparing ozone catalysts based on oil-containing iron sludge according to the present invention through the following embodiments. The specific steps of preparing ozone catalysts based on oil-containing iron sludge in the following embodiments are summarized as follows:
[0023] (1) The hot-rolled sludge is placed in an oven and dried at 105°C. After drying, it is pulverized and then passed through a 100-mesh sieve. The hot-rolled sludge used in this embodiment has the following composition by mass percentage: oil content of 5% to 16%, water content of 20% to 30%, total iron content of 50% to 65%, silicon dioxide content of 0.4% to 1.3%, aluminum oxide content of 0.1% to 0.9%, calcium oxide content of 0.1% to 0.3%, magnesium oxide content of 0.02% to 0.3%, and manganese oxide content of 0.2% to 1%.
[0024] (2) Add 1.0L to 1.5L of 0.5% to 1.0% organic flocculant polyacrylamide to 1kg of sieved hot-rolled sludge. While stirring continuously, add 0.1kg to 0.3kg of sintering plant electrostatic precipitator ash and 30g to 50g of bentonite to form a mixture. Stir the mixture rapidly at a speed of 80r / min to 200r / min for 20min to 30min.
[0025] The sintering plant electrostatic precipitator ash used in this embodiment of the present disclosure, by mass percentage, contains 19%–34% total iron, 13%–26% potassium oxide, 4%–15% calcium oxide, 3%–13% sodium oxide, 13%–24% chlorine, 1%–8% silicon dioxide, and 1%–9% carbon.
[0026] During the rapid stirring process, on the one hand, large oil particles in the mixture are broken up and stirred evenly in the hot-rolled sludge; on the other hand, the long-chain organic flocculant polyacrylamide adsorbs enough emulsified oil on its surface and is evenly dispersed in the hot-rolled sludge.
[0027] (3) Place the well-stirred mixture in an oven and dry it at 105°C until the moisture content drops to 30% to 35%.
[0028] (4) Use an extruder to extrude the dried and mixed material into strips with a diameter of 3mm to 4mm, and after the strips are air-dried, cut them into cylindrical particles with a length of about 0.7cm to 1cm.
[0029] (5) The cylindrical particles are placed in a tube furnace for high-temperature carbonization, with nitrogen as the protective gas. The flow rate of nitrogen is 30 mL / (kg·min) to 60 mL / (kg·min), and the heating rate is 10℃ / min to 15℃ / min. The cylindrical particles are pyrolyzed at 600℃ to 800℃ for 2h to 3h and then cooled to room temperature to obtain the ozone catalysts of the embodiments of this disclosure.
[0030] Example 1
[0031] (1) The hot-rolled sludge was placed in an oven and dried at 105°C. Then it was crushed and passed through a 100-mesh sieve.
[0032] (2) Add 1.0L of 1.0% organic flocculant polyacrylamide to 1kg of sieved hot-rolled sludge. While stirring continuously, add 0.1kg of sintering plant electrostatic precipitator ash and 30g of bentonite to form a mixture. Stir the mixture rapidly at a speed of 80r / min for 30min.
[0033] (3) Place the well-stirred mixture in an oven and dry it at 105°C until the moisture content drops to 30%.
[0034] (4) Use an extruder to extrude the dried and mixed material into strips with a diameter of 3 mm, and after the strips are air-dried, cut them into cylindrical particles with a length of about 0.7 cm.
[0035] (5) The cylindrical particles were placed in a tube furnace for high-temperature carbonization with nitrogen as the protective gas. The flow rate of nitrogen was 50 mL / (kg·min), and the heating rate was 13℃ / min. The cylindrical particles were pyrolyzed at 700℃ for 2.5 h and then cooled to room temperature to obtain the ozone catalyst of Example 1 of this disclosure.
[0036] (6) The specific surface area of the ozone catalyst in Example 1 was tested to be 227 m². 2 / g, pore volume is 0.439 cm 3 / g, with an average pore size of 8.146nm; at the same time, under the same conditions of other steps, this disclosure also prepared an ozone catalyst without the addition of polyacrylamide and sintering plant electrostatic precipitator ash as Comparative Example 1. Compared with Comparative Example 1, the specific surface area and pore volume of the ozone catalyst in Example 1 increased by 12.2% and 4.5% respectively, while the average pore size decreased by 1.84%.
[0037] (7) The ozone catalyst of Example 1 of this disclosure 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 88.2%, which was more than 30% higher than the pollutant removal efficiency of ozone oxidation process without ozone catalyst.
[0038] Example 2
[0039] (1) The hot-rolled sludge was placed in an oven and dried at 105°C. Then it was crushed and passed through a 100-mesh sieve.
[0040] (2) Add 1.3L of 0.8% organic flocculant polyacrylamide to 1kg of sieved hot-rolled sludge. While stirring continuously, add 0.2kg of sintering plant electrostatic precipitator ash and 40g of bentonite to form a mixture. Stir the mixture rapidly at a speed of 150r / min for 25min.
[0041] (3) Place the well-stirred mixture in an oven and dry it at 105°C until the moisture content drops to 33%;
[0042] (4) Use an extruder to extrude the dried and mixed material into strips with a diameter of 3.5 mm, and after the strips are air-dried, cut them into cylindrical particles with a length of about 0.9 cm.
[0043] (5) The cylindrical particles were placed in a tube furnace for high-temperature carbonization, with nitrogen as the protective gas. The flow rate of nitrogen was 60 mL / (kg·min), and the heating rate was 15℃ / min. The cylindrical particles were pyrolyzed at 800℃ for 3 hours and then cooled to room temperature to obtain the ozone catalyst of Example 2 of this disclosure.
[0044] (6) The specific surface area of the ozone catalyst in Example 2 was tested to be 240 m². 2 / g, pore volume 0.45cm 3 / g, with an average pore size of 8.08nm; at the same time, under the same conditions of other steps, this disclosure also prepared an ozone catalyst without the addition of polyacrylamide and sintering plant electrostatic precipitator ash as Comparative Example 2. Compared with Comparative Example 2, the specific surface area and pore volume of the ozone catalyst in this Example 2 increased by 18.6% and 7.3% respectively, while the average pore size decreased by 2.55%.
[0045] (7) The ozone catalyst of Example 2 of this disclosure 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 89.5%, which was more than 30% higher than the pollutant removal efficiency of the ozone oxidation process without using an ozone catalyst.
[0046] Example 3
[0047] (1) The hot-rolled sludge was placed in an oven and dried at 105°C. Then it was crushed and passed through a 100-mesh sieve.
[0048] (2) Add 1.5L of 0.5% organic flocculant polyacrylamide to 1kg of sieved hot-rolled sludge. While stirring continuously, add 0.3kg of sintering plant electrostatic precipitator ash and 50g of bentonite to form a mixture. Stir the mixture rapidly at a speed of 200r / min for 20min.
[0049] (3) Place the well-stirred mixture in an oven and dry it at 105°C until the moisture content drops to 35%;
[0050] (4) Use an extruder to extrude the dried mixed material into strips with a diameter of 4 mm, and after the strips are air-dried, cut them into cylindrical particles with a length of about 1 cm.
[0051] (5) The cylindrical particles were placed in a tube furnace for high-temperature carbonization, with nitrogen as the protective gas. The flow rate of nitrogen was 30 mL / (kg·min), and the heating rate was 10℃ / min. The cylindrical particles were pyrolyzed at 600℃ for 2 hours and then cooled to room temperature to obtain the ozone catalyst of Example 3 of this disclosure.
[0052] (6) The specific surface area of the ozone catalyst in Example 3 was tested to be 236 m². 2 / g, pore volume 0.44cm 3 / g, with an average pore size of 8.13nm; at the same time, under the same conditions of other steps, this disclosure also prepared an ozone catalyst without the addition of polyacrylamide and sintering plant electrostatic precipitator ash as Comparative Example 3. Compared with Comparative Example 3, the specific surface area and pore volume of the ozone catalyst in this Example 3 increased by 16.6% and 5.5%, respectively, while the average pore size decreased by 1.93%.
[0053] (7) The ozone catalyst of Example 1 of this disclosure 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 88.4%, which was more than 30% higher than the pollutant removal efficiency of ozone oxidation process without ozone catalyst.
[0054] 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 an ozone catalyst based on oil-containing iron sludge, characterized by, include: Polyacrylamide, sintering plant electrostatic precipitator ash, and bentonite are added to dry and pulverized hot-rolled sludge. After continuous stirring for a set time, a mixed material is obtained. The mixed material is dried to a set moisture content and then made into granules. The granules are then carbonized to obtain the ozone catalyst. Based on mass percentage, the hot-rolled sludge contains 5%~16% oil, 20%~30% water, 50%~65% total iron, 0.4%~1.3% silicon dioxide, 0.1%~0.9% aluminum oxide, 0.1%~0.3% calcium oxide, 0.02%~0.3% magnesium oxide, and 0.2%~1% manganese oxide. Based on mass percentage, the total iron content of the sintering plant electrostatic precipitator ash is 19%~34%, potassium oxide content is 13%~26%, calcium oxide content is 4%~15%, sodium oxide content is 3%~13%, chlorine content is 13%~24%, silicon dioxide content is 1%~8%, and carbon content is 1%~9%. For 1 kg of dried and pulverized hot-rolled sludge, the amount of polyacrylamide added, with a mass content of 0.5% to 1.0%, is 1.0 L to 1.5 L. The mass ratio of the dried and pulverized hot-rolled sludge to the electrostatic precipitator ash from the sintering plant is 1:0.1~0.3; For 1 kg of dried and pulverized hot-rolled sludge, the amount of bentonite added is 30 g to 50 g; The carbonization method includes: Nitrogen is used as a protective gas during the carbonization process. The flow rate of nitrogen is 30 mL / (kg•min) to 60 mL / (kg•min), the heating rate is 10℃ / min to 15℃ / min, the carbonization temperature is 600℃ to 800℃, and the carbonization time is 2h to 3h.
2. The method for preparing ozone catalyst based on oil-containing iron sludge according to claim 1, characterized in that: The stirring speed is 80 r / min ~ 200 r / min; the set time is 20 h ~ 30 h.
3. The method for preparing ozone catalyst based on oil-containing iron sludge according to claim 1 or 2, characterized in that: The particles are cylindrical, with a length of 0.7 cm to 1 cm and a diameter of 3 mm to 4 mm.
4. The method for preparing ozone catalyst based on oil-containing iron sludge according to claim 3, characterized in that: The mixed material is dried at a temperature of 105°C to the set moisture content, which is 30%~35%.
5. The method for preparing ozone catalyst based on oil-containing iron sludge according to claim 4, characterized in that: The hot-rolled sludge was dried at 105°C and then pulverized. After pulverization, it was passed through a 100-mesh sieve to obtain the dried and pulverized hot-rolled sludge.