Efficient utilization method of stainless steel dedusting ash
By wetting, digesting and pretreatment and granulation of stainless steel dust removal ash in advance, the problem of dust removal ash blocking the sintering trolley grate during the sintering process is solved, and a large proportion of stainless steel dust removal ash is added and effectively utilized. A large amount of stainless steel dust removal ash was processed, which relieved environmental protection pressure and saved environmental protection costs.
Patent Information
- Application Number
- CN202411488523.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-24
- Publication Date
- 2025-02-07
AI Technical Summary
Due to the poor hydrophilicity and poor spherical properties of stainless steel dust removal ash, it cannot be sintered in large proportions, resulting in the blockage of the grate bar of the sintering machine and cannot be promoted and applied on a large scale.
By wetting and digesting the stainless steel dust removal ash in advance, using a multi-layer thin water-plying digestion process, the moisture content is controlled at 7%~9%, and then the ingredients are prepared with the coke powder at a ratio of 94~96:4~6. Griting is carried out to make small balls with a diameter of 3~5mm for sintering production.
The problem of dust removal ash blocking the sintered trolley grate during the sintering process was solved, and a large proportion of stainless steel dust removal ash was added and effectively utilized. After the promotion and application, more than 200,000 tons of stainless steel dust removal ash were successfully processed, alleviating environmental protection pressure. It also saved 200 million yuan in environmental protection costs.
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Figure CN119391980A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of metallurgy and mineral engineering, and relates to a method for processing stainless steel dust, in particular to a method for efficiently utilizing stainless steel dust. Background Art
[0002] Stainless steel dust contains high Fe, Cr, Ni and other useful elements, and has a relatively high resource utilization value. The following is an example of Jiuquan Iron and Steel Group Co., Ltd. (hereinafter referred to as Jiugang). Jiugang stainless steel dust is divided into 300 series and 400 series, with monthly production of 2,500 tons and 2,200 tons, respectively, and annual production of 30,000 tons and 26,000 tons, respectively. The chemical composition of Jiugang stainless steel 300 and 400 series ash is shown in Table 1.
[0003] Table 1 Chemical composition of Jiugang stainless steel 300 and 400 series ash (%) At present, about 120,000 tons of stainless steel dust from Jiugang has been stored in the metallurgical slag yard. The increasing environmental pressure has become a problem that the company needs to solve urgently. To solve this problem, the company used 0.5% stainless steel dust in the 1# and 2# sintering machines of the ironmaking plant, with a daily consumption of about 40 tons, but a daily new production of about 160 tons, a daily increase of 120 tons in inventory, and a monthly increase of 3,600 tons in inventory. Due to the requirements of the molten iron composition when smelting ordinary carbon steel in the steelmaking process, the proportion of stainless steel dust added to the sintering can not be further increased.
[0004] In order to completely solve the problem of stainless steel dust storage, eliminate environmental risks and huge environmental taxes, and comprehensively recycle useful elements such as Fe, Cr, and Ni, we have developed a method for using stainless steel dust to produce chromium-containing sintered ore for ferroalloy submerged arc furnaces or stainless steel smelting. However, due to the fine particle size, poor hydrophilicity, poor ball formation, and easy adhesion to the trolley grate produced by the pyrometallurgical process, if more than 5% is added in sintering production practice, the sintering machine trolley grate will be blocked, and it cannot be added in large proportions during sintering, resulting in the inability to promote and apply this method on a large scale. Summary of the invention
[0005] The purpose of the present invention is to provide a method for efficiently utilizing stainless steel dust ash. By pre-wetting and digesting the stainless steel dust ash, the technical problems of poor hydrophilicity, poor spheroidization and inability to sinter in large proportions of the dust ash are solved.
[0006] To achieve the above object, the present invention adopts the following technical solution: A method for efficiently utilizing stainless steel dust removal ash comprises the following steps: 1) Mixing and digestion: the mixed stainless steel dust ash is placed in a digestion tank for water spraying digestion. A multi-layer thin layer of water digestion process is adopted. The thickness of each thin layer is controlled at 20-30 mm. A layer of stainless steel dust ash is spread, and a layer of water is sprayed until it is fully spread. After it is fully spread, it is digested for at least 5 hours. After digestion, the moisture content of the final product is controlled at 7%-9%; 2) Mixing and sintering: the digested stainless steel dust and coke powder are mixed in a mass ratio of (94-96): (4-6), and then 4-6% of water is added to the mixture for granulation to obtain small balls with a diameter not exceeding 5 mm. The small balls are then evenly spread on the sintering trolley with a material layer thickness of 750-800 mm. The sintering is ignited and cooled to below 120°C after sintering to obtain chromium-containing sintered ore.
[0007] In step 1), the mass ratios of the components of the stainless steel dust ash after mixing are TFe: 36%~38%, SiO2: 4.1%~5.5%, CaO: 21%~23%, Cr2O3: 10.0%~16.5%, Ni: 1.1%~2.1%, MgO: 2.0%~3.5%, S: 0.10%~0.18%, and P: 0.010%~0.025%.
[0008] In step 2), the mass ratios of the components of the chromium-containing sintered ore are TFe: 37.3%~39.3%, FeO: 8.0%~9.5%, SiO2: 4.4%~5.9%, CaO: 21.3%~23.5%, Cr2O3: 10.5%~17.1%, Ni: 1.15%~2.18%, MgO: 2.1%~3.6%, S: 0.03%~0.06%, and P: 0.012%~0.028%.
[0009] The principle of the present invention to solve the problem of clogging the grate bars of the sintering trolley by adding dust removal ash in large proportion during sintering is as follows: The grate bars of the trolley blockage are the common characteristics of all types of dust ash when adding to the sintering process. The main mechanism is that the dust ash has the characteristics of extremely fine particle size and poor hydrophilicity. If it is not wetted in advance and added directly to the sintering process, the extremely fine dust ash will be drawn away with the sintering exhaust gas during the exhaust sintering process. Due to the over-wetting layer during the sintering process (see Figure 1 ) There is water vapor in the sintering waste gas. These water vapor and extremely fine dust ash will condense and adhere to the low-temperature sintering machine grate bars when they meet the sintering machine grate bars, thereby blocking the sintering machine trolley grate bars; and when the dust ash ratio is relatively high, this blockage phenomenon is more likely to occur.
[0010] In order to solve the above problems, we adopted the technical measures of pre-wetting and digestion pre-treatment of stainless steel dust ash, and then mixed it in the batching room according to the ratio of stainless steel dust ash: coke powder = (94~96): (4~6). After the pre-wetted stainless steel dust ash and coke powder were added, the mixture was relatively sticky and the ball-forming property of the mixture was very good. After the mixer granulated the stainless steel dust ash with extremely fine particles, it was wrapped and made into small balls with a diameter of 3~5mm, which prevented it from being drawn away with the sintering waste gas during the exhaust sintering process, thus preventing the grate bars of the trolley from being blocked.
[0011] In summary, through the technical measures of pre-wetting and digesting stainless steel dust ash, the technical problems of poor hydrophilicity and poor ball-forming property of dust ash and inability to add large proportions for sintering have been solved. Recycling the stainless steel dust ash that has been effectively unused, abandoned and accumulated for a long time and recovering useful elements such as metal iron, chromium, and nickel in it is of great significance in comprehensive resource utilization, energy conservation and emission reduction, and reducing the cost of stainless steel.
[0012] Taking Jiugang Stainless Steel Plant as an example, after the success of the experiment, it has been successfully promoted and applied to the industrial production of sintering machines, and completely processed the more than 200,000 tons of stainless steel dust accumulated over the years, effectively alleviating the company's environmental pressure and saving the company 200 million yuan in environmental protection costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 Schematic diagram of each layer during the sintering process. DETAILED DESCRIPTION
[0014] The present invention is further explained below with reference to specific embodiments. Example
[0015] Take the laboratory treatment of Jiugang 300 series stainless steel dust removal as an example, the chemical composition is shown in Table 1, and the specific steps are as follows: 1) Mix and digest Since the composition of stainless steel dust fluctuates greatly, it must be mixed in the material yard; based on actual conditions, the oil shovel is used to mix the material, and the allowable fluctuation range of the mixed material composition is: TFe±3%, Cr2O3±2%, SiO2±2%, CaO±3%, MgO±2%; Then, the mixed stainless steel dust ash is placed in a 1500mm×350mm×500mm box for water spraying digestion. A multi-layer thin layer water digestion process is adopted. The thickness of each thin layer is controlled at 20~30mm. A layer of stainless steel dust ash is spread and a layer of water is applied until the box is full. After the box is full, it is allowed to stand and digest for 5 hours. If expansion and heat occur, the expanded material is shoveled away, and water is continued to be applied and moistened. It is allowed to stand and observe for more than 1 hour until expansion and heat no longer occur. The finished product after digestion is obtained. The moisture content of the finished product should be controlled at 7%~9%; 2) Batching and sintering: the digested stainless steel dust and coke powder are batched and mixed at a mass ratio of 95.5:4.5, and then 4-6% of water is added to the mixture to granulate, so as to obtain small balls with a diameter of 3-5 mm; then the small balls are evenly spread on the sintering trolley, and the total thickness of the material layer is controlled at 750-800 mm, and ignited and sintered. After sintering, the sintered ore is cooled to below 120°C to obtain chromium-containing sintered ore, and the composition is shown in Table 2. The chromium-containing iron sintered ore can be used for the production of ferrochrome alloys and for converter smelting of stainless steel.
[0016] Table 2 Composition of chromium-containing sintered ore produced after sintering of 300 series dust removal ash (%)
Claims
1. A method for efficiently utilizing stainless steel dust, characterized in that: The following steps are involved: 1) Mixing and digestion: the mixed stainless steel dust ash is placed in a digestion tank for water spraying digestion. A multi-layer thin layer of water digestion process is adopted. The thickness of each thin layer is controlled at 20-30 mm. A layer of stainless steel dust ash is spread, and a layer of water is sprayed until it is fully spread. After it is fully spread, it is digested for at least 5 hours. After digestion, the moisture content of the final product is controlled at 7%-9%; 2) Mixing and sintering: the digested stainless steel dust and coke powder are mixed in a mass ratio of (94-96): (4-6), and then 4-6% of water is added to the mixture for granulation to obtain small balls with a diameter not exceeding 5 mm. The small balls are then evenly spread on the sintering trolley with a material layer thickness of 750-800 mm. The sintering is ignited and cooled to below 120°C after sintering to obtain chromium-containing sintered ore.
2. A method for efficiently utilizing stainless steel dust as claimed in claim 1, characterized in that: In step 1), the mass ratios of the components of the stainless steel dust ash after mixing are TFe: 36%~38%, SiO2: 4.1%~5.5%, CaO: 21%~23%, Cr2O3: 10.0%~16.5%, Ni: 1.1%~2.1%, MgO: 2.0%~3.5%, S: 0.10%~0.18%, and P: 0.010%~0.025%.
3. A method for efficiently utilizing stainless steel dust as claimed in claim 1, characterized in that: In step 2), the mass ratios of the components of the chromium-containing sintered ore are TFe: 37.3%~39.3%, FeO: 8.0%~9.5%, SiO2: 4.4%~5.9%, CaO: 21.3%~23.5%, Cr2O3: 10.5%~17.1%, Ni: 1.15%~2.18%, MgO: 2.1%~3.6%, S: 0.03%~0.06%, and P: 0.012%~0.028%.