Separation and extraction process for valuable components in blast furnace casting house ash
By combining air separation and selective micro-reduction with magnetic separation and chemical leaching technologies, the problem of separating graphite and iron oxides in blast furnace tapping ash has been solved, achieving efficient and low-cost resource recovery and utilization.
Patent Information
- Application Number
- CN202511978881.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-02-10
AI Technical Summary
Existing technologies are insufficient for efficiently separating graphite and iron oxides from blast furnace tapping ash, leading to resource waste and low-value utilization. Traditional methods are inefficient and energy-intensive.
After air classification pretreatment, iron oxides and graphite in blast furnace tapping ash are extracted through selective micro-reduction and precisely controlled oxidation and reduction steps. The particles are classified based on differences in particle density and size, and then separated efficiently by magnetic separation and chemical leaching techniques.
This technology achieves high-purity separation of iron oxides and graphite, enhances resource utilization value, avoids energy and reagent waste, and forms an efficient pretreatment-precision treatment system.
Smart Images
Figure CN121494073A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of resource utilization of metallurgical solid waste, and in particular to a process for separating and extracting valuable components from blast furnace tapping ash. Background Technology
[0002] During blast furnace ironmaking, a large amount of smoke and dust is generated at the tapping area. Collected by a dust removal system, this forms blast furnace tapping ash, a typical solid waste with a complex composition. It mainly contains iron oxides (including Fe2O3 and Fe3O4) formed by oxidation of the molten iron surface, graphite precipitated from the molten iron during the cooling process, and impurities such as SiO2 and CaO. The graphite content is approximately 7%, while the iron oxide content can reach over 85%. Currently, the treatment of blast furnace tapping ash involves simply returning it to the sintering process or mixing it with other metallurgical waste. However, this method has the following problems: the high-value graphite in the tapping ash is not effectively recovered, resulting in resource waste; secondly, the relatively pure iron oxides in the tapping ash are used at a low value. Graphite in the tapping ash can be used as a negative electrode material for lithium batteries, and the iron oxides can be used as precursor materials in the field of new materials.
[0003] Existing technologies include several separation methods, such as direct magnetic separation, flotation, and strong oxidative roasting. However, because some iron oxides (Fe2O3) in blast furnace tapping ash exist in a tightly packed structure with graphite—that is, tiny iron oxide (Fe2O3) particles are encased within the layered structure of graphite—single physical separation methods (such as magnetic separation and flotation) are inefficient, making it difficult to achieve efficient and high-purity separation of iron oxides and graphite. While oxidative roasting can completely remove carbon through high-temperature oxidation, it also completely destroys the structure and value of graphite, and the process is energy-intensive and generates significant carbon emissions.
[0004] Therefore, developing a process that can effectively dissociate and separately recover high-value components such as iron oxides and graphite from blast furnace tapping ash is of great significance for realizing the refined and high-value utilization of metallurgical solid waste. Summary of the Invention
[0005] The purpose of this invention is to provide a process for separating and extracting valuable components from blast furnace tapping ash, so as to solve the problems in the background art.
[0006] To achieve the above objectives, the present invention provides a process for separating and extracting valuable components from blast furnace tapping ash, comprising the following steps: S1. The original blast furnace tapping ash is subjected to air classification. Based on the differences in density and particle size between particles, it is enriched into three different components: iron oxide with trace amounts of graphite, iron oxide and graphite coated particles, and graphite with a small amount of small iron oxide particles. S2. Perform fine separation of the three components separately, the specific steps of which are as follows: 1) Oxidize iron oxides containing trace amounts of graphite to remove graphite impurities by oxidizing or reducing high-valence iron oxides to obtain pure iron oxides. 2) Selective micro-reduction treatment is performed on the iron oxide and graphite coated particles under a reducing atmosphere to completely reduce Fe2O3 coated in the graphite layered structure to Fe3O4, thereby completely separating the coated particles; then the treated material is magnetically separated to obtain magnetic iron oxide and graphite respectively; this step achieves selective reduction of iron oxide without initiating the gasification reaction of graphite by precisely controlling the reduction conditions. 3) The graphite containing a small amount of small iron oxide particles was subjected to acid leaching and alkali leaching in sequence to obtain high-purity graphite products.
[0007] Preferably, in S1, the wind speed is 3~5m / s and the wind separation temperature is 20~40℃.
[0008] Preferably, in step 1) of S2, the heat treatment conditions are: heating oxidation is performed in an oxidizing atmosphere at 700℃~800℃.
[0009] Preferably, in step 2) of S2, the temperature of the selective micro-reduction treatment is 450~500℃, and the heating rate is 8~10℃ / min.
[0010] Preferably, in step 2) of S2, the reducing atmosphere is a mixture of CO and CO2, wherein the volume fraction of CO is 35-45%.
[0011] Preferably, the volume fraction of CO is 40%.
[0012] Preferably, in step 2) of S2, the magnetic separation is performed three times, and after magnetic separation, the material is filtered and dried; before magnetic separation, the material undergoing selective micro-reduction treatment is crushed or ground.
[0013] Preferably, in step 3) of S2, the acid leaching uses either hydrochloric acid or sulfuric acid, with a concentration of 1~3 mol / L; the alkaline leaching uses sodium hydroxide solution with a concentration of 2~6 mol / L.
[0014] Therefore, the separation and extraction process of valuable components in blast furnace tapping ash of the present invention has the following beneficial effects: (1) Through the process route of classified disposal, the purity of the iron oxide product obtained is significantly improved, and graphite products with high fixed carbon content and direct resource utilization are obtained, realizing the high-value utilization of all components of solid waste.
[0015] (2) By selectively reducing Fe2O3 to Fe3O4 in the coated particles and precisely controlling the thermodynamic conditions, the structure of the coated particles was separated without damaging the graphite, which greatly enhanced the magnetic differences between different components and laid a solid foundation for subsequent magnetic separation. This solved the bottleneck that traditional physical methods cannot handle coated bodies.
[0016] (3) Air classification and coarse separation, as a pretreatment step, effectively enriches valuable components and classifies and concentrates difficult-to-process materials, enabling subsequent high-cost chemical or deep physical treatments to "precisely exert their power," avoiding the waste of energy and reagents, and forming a highly efficient synergistic system of "pretreatment-precision treatment."
[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0018] Figure 1 This is a process path diagram of Embodiment 1 of the present invention; Figure 2 This is a SEM image of component one in Example 1 of the present invention; Figure 3 EDS is component one of the components in Example 1 of this invention. Figure 1 ; Figure 4 EDS is component one of the components in Example 1 of this invention. Figure 1 ; Figure 5 Here are the SEM images of component two in Example 1 of this invention; Figure 6 This is the EDS diagram of component two in Example 1 of the present invention; Figure 7 This is a SEM image of the sheet-like particles of component three in Example 1 of the present invention; Figure 8 EDS diagram of the flaky particles of component three in Example 1 of the present invention; Figure 9 This is a SEM image of the polyhedral particles of component three in Example 1 of the present invention; Figure 10 EDS diagram of the polyhedral particles of component three in Example 1 of this invention; Figure 11 This is a SEM image of component one after oxidation treatment in Example 1 of the present invention; Figure 12 This is the EDS diagram of component one after oxidation treatment in Example 1 of the present invention; Figure 13 The image shows the XRD pattern of the magnetic material after processing of component two in Example 1 of this invention. Figure 14This is a SEM image of the magnetic material after processing of component two in Example 1 of the present invention; Figure 15 This is an EDS image of the magnetic material after processing of component two in Example 1 of the present invention; Figure 16 The image shows the XRD pattern of the non-magnetic material after processing of component two in Example 1 of this invention. Figure 17 This is a SEM image of the non-magnetic material of component two after processing in Example 1 of the present invention; Figure 18 This is an EDS image of the non-magnetic material of component two after treatment in Example 1 of the present invention; Figure 19 The image shows the XRD pattern of the magnetic product in Comparative Example 1 of this invention. Figure 20 The image shows the XRD pattern of the non-magnetic product in Comparative Example 1 of this invention. Figure 21 This is the XRD pattern of the product of Comparative Example 2 of the present invention. Detailed Implementation
[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.
[0021] This invention provides a process for separating and extracting valuable components from blast furnace tapping ash, such as... Figure 1 As shown, it includes the following steps: S1. The original blast furnace tapping ash is subjected to air classification at a wind speed of 3~5m / s and a wind classification temperature of 20~40℃. Based on the differences in density and particle size between particles, it is enriched into three different components: iron oxide containing trace amounts of graphite, iron oxide and graphite coated particles, and graphite mixed with a small amount of small iron oxide particles. S2. Perform fine separation of the three components separately, the specific steps of which are as follows: 1) Oxidize iron oxides containing trace amounts of graphite to remove graphite impurities by oxidizing or reducing high-valence iron oxides to obtain pure iron oxides; the heat treatment conditions are: heating and oxidation in an oxidizing atmosphere at 700℃~800℃.
[0022] 2) Selective micro-reduction treatment of iron oxide and graphite coated particles under a reducing atmosphere to completely reduce Fe2O3 to Fe3O4, thereby achieving complete separation of the coated particles; the treatment temperature is 450~500℃, the heating rate is 8~10℃ / min, and the optimal temperature is 450℃; the reducing atmosphere is a mixture of CO and CO2, wherein the volume fraction of CO is 40%. The material undergoing selective micro-reduction treatment is crushed or ground, and then subjected to three magnetic separations. After separation, the material is filtered and dried to obtain magnetic iron oxide and graphite products, respectively. This step achieves selective reduction of iron oxide without initiating the gasification reaction of graphite by precisely controlling the reduction conditions.
[0023] 3) Graphite containing a small amount of iron oxide particles is subjected to acid leaching and alkali leaching in sequence to obtain high-purity graphite products; acid leaching uses either hydrochloric acid or sulfuric acid with a concentration of 1~3 mol / L; alkali leaching uses sodium hydroxide solution with a concentration of 2~6 mol / L.
[0024] Example 1 This embodiment addresses the treatment of raw tapping ash collected from the blast furnace tapping area of Benxi Iron & Steel Co., Ltd. Plate Plant. Preliminary sample analysis revealed that the main components of the raw tapping ash were graphite (6.3%), Fe2O3 (46.5%), and Fe3O4 (41.4%); it also included CaO (1.4%) and SiO2 (4.3%).
[0025] In the ash particle group of the iron tapping site, graphite mainly exists in the form of flake particles; iron oxide mainly exists in the form of small spherical and spherical aggregates; the composition of the polyhedral particles with sharp edges in the particle group is relatively complex, and the composition of these particles comes from the refractory materials of the tapping mud, main trench and iron trench; the coated particles in the particle group are formed by Fe2O3 entering the interlayer gaps of graphite in the form of small particles. This embedded coating structure undoubtedly makes the effective separation of graphite and iron oxide extremely difficult.
[0026] The specific separation and extraction process is as follows: S1. Air Classification and Enrichment: 500g of original blast furnace tapping ash was fed into a laboratory air classifier and air-classified at room temperature (25℃). The airflow velocity in the classification zone was controlled to 3m / s by adjusting the fan frequency. After separation, three components were obtained: Component 1 (heavy product): 381g was collected. This component was dark black in color and exhibited strong magnetic properties. The results of component analysis are shown in Table 1 below. Figures 2-4 As shown, its main components are iron oxides and trace amounts of graphite.
[0027] Table 1: Elemental Analysis and Proportions of Energy Dispersive Spectroscopy (EDS)
[0028] Component 2 (intermediate product): 50g was collected. This component has a rough surface. Compositional analysis of this component was performed, and the results are shown in Table 2 below. Figures 5-6 As shown, its main form is iron oxide (Fe2O3)-graphite coated particles.
[0029] Table 2: Elemental Analysis and Proportions of Particle Energy Spectroscopy
[0030] Component 3 (light product): 63g was collected. This component is grayish-black in color, smooth to the touch, and exhibits typical graphite characteristics. The flaky particles and sharply angular polyhedral particles in this component were analyzed separately, and the results are shown in Tables 3 and 4 below. Figures 7-10 As shown, the light products mainly consist of graphite, a small amount of small-particle iron oxides, and CaO and SiO2.
[0031] Table 3: Elemental Analysis and Proportions of Flaky Particles
[0032] Table 4: Elemental Analysis and Proportion of Sharp-Edged Polyhedrons
[0033] S2, Fine separation process: 1) Take 100g of component one, place it in a muffle furnace, and calcine it in air at 700℃ for 1 hour to completely oxidize the residual graphite. After cooling, 101g of brownish-red powder is obtained. Component analysis is as follows: Figure 11 , Figure 12 As shown in Table 5, the EDS elemental analysis and proportions of the calcined small particles are as follows.
[0034] Table 5: Elemental Analysis and Proportion of Small Particle EDS
[0035] 2) Take 20g of component two, heat the furnace to 450℃ at 10℃ / min, and after the temperature stabilizes, purge the furnace with N2 at a flow rate of 5L / min. After 5 minutes, evenly spread 20g of tapping ash in a ceramic boat, place it on the furnace sieve plate, and simultaneously switch to a ratio of... The reducing gas concentration was 0.4, and the flow rate was 5 L / min. Weight loss was observed using a weighing system. After the weight loss curve showed no change within 5 minutes, N2 protection was switched on, and the reactor was cooled to room temperature at 10℃ / min. The reduced iron ash sample was then removed. After slight grinding, magnetic separation was performed three times using a magnetic separator under a 0.7T magnetic field to ensure effective separation. The magnetic and non-magnetic products were filtered and vacuum dried at 60℃ for 4 hours, yielding 16 g of magnetic iron oxide and 2 g of graphite.
[0036] The composition of the treated magnetic iron oxides was analyzed, as shown in Table 6 and... Figures 13-15 As shown, this indicates that Fe3O4, a valuable component, can be extracted from iron field ash through multiple magnetic separations after micro-reduction.
[0037] Table 6: Elemental Analysis and Proportions of Magnetic Components (EDS)
[0038] The selected non-magnetic materials were subjected to compositional analysis, and the results are shown in Table 7 and... Figures 16-18 As shown, some graphite particles exhibit a sheet-like porous structure, and no multi-particle structure particles can be observed within the field of view. This indicates that during the selective micro-reduction process, as the reaction proceeds, the volume of iron oxide particles embedded in the graphite layered structure decreases, and Fe3O4 particles detach from the graphite layered structure. The coating state of graphite and iron oxide is destroyed, thereby achieving the separation of graphite and iron oxide in the coated state.
[0039] Table 7: Elemental Analysis and Proportions of Non-Magnetic Products by EDS
[0040] 3) Take 50g of component three and place it in 200mL of 3mol / L dilute hydrochloric acid solution. Stir and leach for 2 hours in an 80℃ water bath. Filter and wash with deionized water until neutral. Then, place the filter residue after acid leaching in 200mL of 5mol / L sodium hydroxide solution and leach alkaline at 98℃ for 3 hours. Filter and wash again until neutral. Finally, dry the filter residue at 100℃ for 6 hours to obtain 15.8g of graphite product. Adding the 2g of graphite obtained in step 2), a total of 17.8g of graphite product is finally obtained.
[0041] Example 2 This embodiment follows the same preparation steps as Example 1, except that the proportion of the reducing gas in step 2) of S2 is modified. =0.35.
[0042] Example 3 This embodiment follows the same preparation steps as Example 1, except that the proportion of the reducing gas in step 2) of S2 is modified. =0.45.
[0043] Comparative Example 1 Take 100g of raw iron tapping field ash (without any pretreatment) and directly use a magnetic separator to perform three magnetic separations under a magnetic field strength of 0.7T to separate magnetic products and non-magnetic products.
[0044] XRD analysis was performed on magnetic and non-magnetic products, such as... Figure 19 , Figure 20 As shown, the main component of the magnetic filter residue is Fe3O4, with small amounts of graphite C and Fe2O3; the main components of the non-magnetic filter residue are graphite C and Fe2O3, with a higher graphite content than the magnetic filter residue. Therefore, this method cannot successfully separate graphite and iron oxides.
[0045] Comparative Example 2 Take 100g of raw iron tapping field ash (without any pretreatment) and place it in a flotation cell for flotation. During the flotation process, add a capture agent and a foaming agent. Under stirring conditions, introduce air into the flotation cell. When the iron tapping field ash particles and bubbles are fully combined to form mineralized bubbles, use a scraper to scrape off the foam layer. During the scraping process, continuously add water. Perform three flotation processes in sequence. After the flotation is completed, perform acid leaching and drying.
[0046] The dried product was subjected to XRD analysis, such as... Figure 21 As shown, a certain amount of Fe2O3 still exists in the graphite concentrate. Therefore, this method cannot successfully separate graphite and iron oxides.
[0047] By comparison, the embodiments using the method protected by this invention first separate the easily processed component one (iron oxides mixed with trace amounts of graphite) and component three (graphite mixed with a small amount of small-particle iron oxides) by air classification, and then use selective micro-reduction to centrally process the most difficult-to-separate component two (iron oxide and graphite coated particles). By precisely controlling the phase change of iron oxides without causing graphite consumption, the system systematically avoids wasting energy and consuming graphite on easily processed materials, and maximizes overall benefits.
[0048] Therefore, the present invention provides a separation and extraction process for valuable components in blast furnace tapping ash. The coarse separation by air classification not only pre-enriches the valuable components, but more importantly, it concentrates the difficult-to-process coated particles, so that the subsequent selective micro-reduction can act efficiently on the target product, avoiding interference with other components in the processing, and also avoiding the waste of energy and reagents, thereby maximizing the overall efficiency.
[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A process for separating and extracting valuable components from blast furnace tapping ash, characterized in that, Includes the following steps: S1. The original blast furnace tapping ash is subjected to air classification. Based on the differences in density and particle size between particles, it is enriched into three different components: iron oxide with trace amounts of graphite, iron oxide and graphite coated particles, and graphite with a small amount of small iron oxide particles. S2. Perform fine separation of the three components separately, the specific steps of which are as follows: 1) Oxidize iron oxides containing trace amounts of graphite to obtain pure iron oxides; 2) Selective micro-reduction treatment was performed on the coated particles of iron oxide and graphite under a reducing atmosphere to reduce all Fe2O3 to Fe3O4. Then, the treated materials were separated by magnetic separation to obtain magnetic iron oxide and graphite respectively. 3) The graphite containing a small amount of iron oxide particles was subjected to acid leaching and alkali leaching in sequence. After solid-liquid separation and washing, a high-purity graphite product was obtained.
2. The process for separating and extracting valuable components from blast furnace tapping ash according to claim 1, characterized in that: In S1, the wind speed is 3~5m / s and the air separation temperature is 20~40℃.
3. The process for separating and extracting valuable components from blast furnace tapping ash according to claim 1, characterized in that: In step 1) of S2, the heat treatment conditions are: heating oxidation is performed in an oxidizing atmosphere at 700℃~800℃.
4. The process for separating and extracting valuable components from blast furnace tapping ash according to claim 1, characterized in that: In step 2) of S2, the temperature of the selective micro-reduction treatment is 450~500℃, and the heating rate is 8~10℃ / min.
5. The process for separating and extracting valuable components from blast furnace tapping ash according to claim 1, characterized in that: In step 2) of S2, the reducing atmosphere is a mixture of CO and CO2, wherein the volume fraction of CO is 35-45%.
6. The process for separating and extracting valuable components from blast furnace tapping ash according to claim 1, characterized in that: In step 2) of S2, the magnetic separation is performed three times. After magnetic separation, the material is filtered and dried. Before magnetic separation, the material undergoing selective micro-reduction treatment is crushed or ground.
7. The process for separating and extracting valuable components from blast furnace tapping ash according to claim 1, characterized in that: In step 3) of S2, acid leaching uses either hydrochloric acid or sulfuric acid, with a concentration of 1~3 mol / L; alkaline leaching uses sodium hydroxide solution with a concentration of 2~6 mol / L.