Method for efficiently preparing silica gel and white carbon black by taking smelting slag as raw material

Abstract

The invention discloses a method for efficiently preparing silica gel and white carbon black by taking smelting slag as a raw material. The invention relates to the technical field of solid waste resource utilization, separation and purification and material preparation. The method comprises the following steps: dissolving out SiO2-rich ferronickel slag or copper smelting slag under a proper acid leaching condition, and carrying out centrifugal separation to obtain a supersaturated silicic acid solution; the preparation method comprises the following steps: in a normal-temperature and open environment, forming a gel solution mixture containing silica gel fine particles by stirring and surface activation, controlling the separation rate of silicic acid gel of a system and adjusting the structure, form and size of silica gel particles, separating the gel solution, washing and drying wet silica gel to obtain dry silica gel, and roasting to obtain white carbon black with the SiO2 content of more than 99 wt%; the method adopts an alkalization-free preparation process taking the smelting waste slag as a raw material, and has the advantages of wide raw material adaptability, low energy consumption, low production cost, good product quality and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization, separation and purification, and material preparation, and in particular to a method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials. Background Art

[0002] Silicon accounts for approximately 27.6% of the Earth's crust, second only to oxygen. SiO2 is abundant in many ores, tailings, ore dressing slag, and smelting slag. In many cases, SiO2 is considered a gangue component and is discarded or used as a siliceous additive in low-value building materials such as cement, concrete, and brickwork. For example, the primary impurity in laterite nickel ore is SiO2. The SiO2 content in the nickel-recovered ferronickel slag typically ranges from 35% to 60%. The SiO2 content in copper smelting slag, produced after copper recovery from sulfide copper ore, is typically between 30% and 40%. The SiO2 content in lithium slag powder produced after lithium recovery from spodumene is typically between 40% and 60%. These solid wastes share a common characteristic: they are rich in SiO2. SiO2 in water-quenched ferronickel slag primarily exists in an amorphous, non-crystalline state. This highly reactive structure is easily dissolved in acid, making it suitable for acid recovery. Copper smelting slag primarily consists of a crystalline Fe2SiO4 phase. While not as acid-soluble as amorphous SiO2, under appropriate raw material particle size and acid leaching process parameters, most of the Fe2SiO4 phase can decompose, releasing silicon and iron. However, this solid waste is currently primarily in the research phase, and its utilization rate remains low. Storage or landfill is the primary method, which not only occupies significant land but also poses a serious threat to the ecological environment. To significantly reduce this solid waste while increasing its resource utilization, it is essential to develop a universal, high-value, and efficient solid waste utilization pathway.

[0003] Silica gel, also known as hydrated silicon dioxide (SiO2·nH2O), is a porous, non-toxic, and odorless inorganic compound with high-temperature resistance, electrical and chemical stability, and high insulation properties. Wet silica gel, due to its high free water content, has a jelly-like consistency. Dry silica gel, the product of wet silica gel drying, has a very low water content. Silica gel, on the other hand, is the product of high-temperature calcination of dry silica gel and contains a very small amount of crystalline water. The purity of silica gel and silica is generally measured by SiO2 content. Silica gel and silica have a wide range of applications. Dry silica gel is often used as a desiccant, adsorbent, and molecular sieve, while silica is often used as an additive in rubber, coatings, and plastics to improve the wear resistance of rubber, the uniform dispersion of coatings, and the mechanical properties of plastics.

[0004] The traditional precipitation method is still the main method for the current industrial production of silica gel and white carbon black. It uses high-quality quartz sand as raw material, which reacts with caustic soda to produce sodium silicate as an intermediate product. The sodium silicate is then reacted with acid to produce silica gel. Finally, dry silica gel is prepared through washing, drying and other process steps, and then roasted to obtain white carbon black. The present invention develops a method for efficiently recovering SiO2 from nickel-iron slag or copper smelting slag to prepare high-value-added silica gel and white carbon black. Compared with the traditional precipitation method, metallurgical waste slag can be selected as the raw material, which not only can greatly reduce the stock of solid waste, but also the entire preparation process does not require alkali dissolution and the generation of sodium silicate as an intermediate product. The process flow is short, thereby significantly reducing the cost of raw materials and solvents while reducing the process cost of silica gel, which has very important industrial promotion value.

[0005] Currently, in addition to traditional precipitation and vapor phase methods for preparing silica gel and silica, recovering SiO2 from solid waste to prepare silica gel and silica has become a research hotspot. Several reports have been published on the preparation of silica gel or silica from solid waste. However, aside from differences in the raw materials used, the processes described in these reports do not differ substantially from traditional methods. The present invention, however, significantly differs from traditional production methods in both raw materials and process. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for efficiently preparing silica gel and white carbon black using smelting slag as raw material; the method comprises: dissolving nickel-iron slag or copper smelting slag under suitable acid leaching conditions, and obtaining a supersaturated silicic acid solution after centrifugal separation; at room temperature and in an open environment, using stirring and surface activation, the system silica gel precipitation rate is controlled, the silica gel particle structure, morphology and size are adjusted, and a gel-liquid mixture containing silica gel fine particles is formed; after the gel-liquid is separated, the wet silica gel is washed and dried to obtain dry silica gel, and after roasting, white carbon black with an SiO2 content greater than 99 wt% is obtained; the method adopts an alkali-free preparation process using smelting waste slag as raw material, and has the advantages of wide raw material adaptability, low energy consumption, low production cost, and good product quality.

[0007] In order to achieve the above technical effects, the following technical solutions are adopted: A method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials, comprising the following steps: Step S1: Pretreatment of silicon-containing materials The smelting slag is dried at 100-120°C for 4-8 hours, then ball-milled at 200-500 rpm for 0.5-6 hours, and then passed through a 200-mesh or higher sieve to obtain a powder of appropriate particle size. The powder is weighed and used as the solute for the next step of acid leaching. Step S2: Acid leaching Leaching the powder of suitable particle size obtained in step S1 with an acid solution, stirring the leaching process to dissolve the silicon minerals in the smelting slag into the solution, while the gangue components remain in the slag, to obtain a slag-liquid mixture; Step S3: Slag-liquid separation The slag-liquid mixture obtained in step S2 is separated to obtain a supersaturated silicic acid solution with suitable stability and a leached slag mainly composed of gangue components; Step S4: Gluing The supersaturated silicic acid solution with suitable stability obtained in step S3 is stirred to gradually precipitate the supersaturated silicic acid in the solution, and silica gel particles are formed after nucleation, growth, and coagulation, and are suspended in the solution to obtain a suspension containing silica gel particles; the stirring rate is 200 to 800 rpm, and the stirring time is 6 to 14 hours; Step S5: Separation of glue and liquid The suspension containing silica gel particles obtained in step S4 is vacuum filtered to obtain jelly-like wet silica gel containing impurities and a mixed solution of acid and salt containing impurities; Step S6: Washing and drying The jelly-like wet silica gel containing impurities obtained in step S5 is washed with pure water having a liquid-to-solid ratio of 4:1 to 6:1 for 5 to 7 steps, and then dried at 100 to 120° C. for 6 to 12 hours to obtain dry silica gel; Step S7: calcining the dry silica gel prepared in step S6 at 480-580° C. for 2-6 h to decompose the silica gel to generate white carbon black having a SiO2 content exceeding 99 wt%; In step S4, the supersaturated silicic acid solution is stirred, and a surfactant is added to slow down the silica gel nucleation growth rate and adjust the microstructure of the white carbon black; The surfactant is a polyethylene glycol (PEG) solution, and the amount of PEG added is 0.5% to 3.5% of the mass of the silicon-containing material.

[0008] Furthermore, the smelting slag in step S1 is a silicon-containing material such as nickel-iron slag or copper smelting slag, which is rich in SiO2 components; when SiO2 in these smelting slags exists in an amorphous non-crystalline form, the silicon recovery effect is best.

[0009] Furthermore, the acid solution in step S2 is a sulfuric acid or hydrochloric acid solution. The selected leaching process conditions are related to the solute type, mineral type, solute crystallization degree, solvent type, concentration, and recovery economic and technical indicators. For easily soluble substances, a lower acid concentration is generally used, while for poorly soluble substances, a higher acid concentration is generally used.

[0010] Furthermore, in step S3, the slag-liquid separation is performed by centrifugal filtration, vacuum filtration, or pressure filtration. The specific filtration method used depends primarily on the type of raw material. When the supersaturated silicic acid solution formed by leaching is unstable, or even a small amount of silicic acid sol precipitates from the solution, centrifugal separation is necessary. When the amount of silicic acid sol generated in the solution is small and filtration is not difficult, vacuum filtration can be used. For situations in between, pressure filtration can be used.

[0011] Furthermore, the purity of the dry silica gel in step S6 exceeds 99 wt%.

[0012] Furthermore, the leaching conditions in step S2 are: acid concentration 0.5-3 mol / L, liquid-solid ratio 3-15:1, leaching temperature 20-80°C, leaching time 10-120 min, and stirring rate 300-800 rpm.

[0013] Furthermore, the centrifugal filtration separation conditions are: the rotation speed is controlled at 500-3000 rpm, and the centrifugal separation time is 5-10 min.

[0014] In step S4, the supersaturated silicic acid solution is stirred while a surfactant is added to slow the silica nucleation growth rate and adjust the silica microstructure, resulting in finer silica particles with larger pore size and specific surface area. The addition of a surfactant has little effect on the purity of the silica and silica. For example, adding a polyethylene glycol (PEG) solution as a surfactant, at a level of 0.5% to 3.5% by weight of the silica-containing material, can improve subsequent separation of the silica and increase the pore size and specific surface area of the silica.

[0015] The method for preparing silica gel does not require alkali dissolution or the formation of sodium silicate, but directly reacts with acid to generate silicate sol, which has the remarkable characteristics of short process, high efficiency and low production cost.

[0016] The impurities in step S5 may be elements such as Mg, Fe, Ni, Co, Li, Cr, Ca, K, and Na. If these elements are concentrated in the leachate at a high concentration, they can be comprehensively recovered as valuable elements to improve economic efficiency. For example, using nickel-iron slag as raw material and sulfuric acid as solvent, the solution obtained by separation of the glue solution is mainly a crude magnesium sulfate solution, and in the future, Mg can be further comprehensively recovered to prepare magnesium sulfate. For another example, using copper smelting slag as raw material and sulfuric acid as solvent, the solution obtained after separation of the glue solution is mainly a ferrous sulfate solution, and in the future, comprehensive recovery of Fe can be considered to prepare substances such as ferrous sulfate or ferric hydroxide.

[0017] The beneficial effects of the present invention are: 1. The process has wide adaptability to raw materials and can process different types of silicon-containing materials. On the one hand, the technical method of the present invention can achieve silicon recovery rates exceeding 90% and magnesium recovery rates exceeding 85% when processing water-quenched nickel-iron slag with a high amorphous SiO2 content, and can produce silica gel and white carbon black with purities exceeding 99 wt%. On the other hand, when processing copper smelting slag dominated by fayalite crystals, the silicon recovery rate is approximately 70%, and the purity of white carbon black can reach over 99.5 wt%. It can also be used to process mixed amorphous and crystalline silicon-containing materials, such as air-cooled nickel-iron slag.

[0018] 2. The product offers high product flexibility, allowing the purity of the silica product to be controlled by streamlining the process. Silica gel can be produced without calcination, while silica can be produced after calcination. If the focus is solely on the purity of silica gel and silica, no surfactant is required during the gelling process, further reducing production costs. However, if a product with a large pore size and specific surface area is desired, a small amount of surfactant can be added during the gelling process. Although this increases production costs, it improves the product's microstructure.

[0019] 3. The slag rate (the ratio of the mass of the leached slag from the preparation process to the mass of the raw ferronickel slag) varies when processing different silicon-containing materials. When processing water-quenched electric furnace ferronickel slag, the slag rate is approximately 20%, while when processing copper smelting slag, the slag rate is approximately 50%. The slag rate reflects the utilization rate of the raw materials. For solid waste raw materials, the lower the slag rate, the greater the solid waste reduction capacity.

[0020] 4. When treating amorphous SiO2-containing solid waste, this invention can comprehensively recover other valuable elements from the waste. For example, when using ferronickel slag as the raw material, magnesium can be recovered alongside silicon, which can be used to produce magnesium products such as magnesium sulfate, magnesium nitrate, magnesium hydroxide, and magnesium oxide. Simultaneously, the MgO content in the residual slag is significantly reduced, making it more suitable for use as a building material with stringent MgO content requirements. This improves economic efficiency while enabling the full resource utilization of solid waste.

[0021] 5. The present invention can, to a large extent, solve many hydrometallurgical problems caused by the difficulty of solid-liquid separation after leaching due to the presence of soluble SiO2 minerals. It can also convert these substances (silicic acid) that are considered harmful in conventional metallurgical processes into high-value-added silicon products, providing a new way to expand the application scope of hydrometallurgical technology and the comprehensive utilization of minerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. The drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0023] Figure 1 The XRD pattern of the water-quenched ferronickel slag used as the raw material in Examples 1 to 5 of the present invention is shown; Figure 2 is the XRD pattern of the silica gel prepared in Example 1 of the present invention; Figure 3 is the XRD pattern of the white carbon black prepared in Example 1 of the present invention; Figure 4 is the visible-infrared absorption spectrum of the silica gel prepared in Example 1 of the present invention; Figure 5 is the visible-infrared absorption spectrum of the white carbon black prepared in Example 1 of the present invention; Figure 6 This is a SEM image of the silica gel prepared in Example 1 of the present invention; Figure 7 This is a SEM image of the white carbon black prepared in Example 1 of the present invention; Figure 8 The XRD pattern of the crystalline and amorphous mixed nickel-iron slag used in Example 7 of the present invention; Figure 9 XRD pattern of the raw copper smelting slag used in Examples 7 and 8 of the present invention; Figure 10 The figure is a flow chart of the whole process for preparing silica gel and white carbon black in the embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0027] In the following examples, unless otherwise specified, all reagents and consumables were purchased from conventional reagent manufacturers in the field; unless otherwise specified, the experimental methods and technical means used were conventional methods and means in the field.

[0028] The method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials provided by the present invention is described below with reference to the following examples. The scope of protection of the present invention is not limited by the following examples.

[0029] Example 1: This embodiment provides a method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials, and the specific steps are as follows: Using water-quenched nickel-iron slag as raw material, its XRD Figure 1 The chemical composition is shown in Table 1. Combined with the chemical composition analysis of the nickel-iron slag in Table 1, this figure shows that the SiO2 in the slag is primarily in an amorphous, non-crystalline form, with only a small amount of crystalline magnesian olivine phase (Mg, Fe)2SiO4 present. The SiO2 content in the slag is 39.6 wt%. The nickel-iron slag was dried at 120°C for 4 h, then placed in an agate ball mill and ball milled at 500 rpm for 0.5 h. After ball milling, the material was removed and passed through a 200-mesh sieve to obtain a fine nickel-iron slag powder. 20 g of the fine nickel-iron slag powder was weighed and used as the solute for acid leaching. The solute was leached at room temperature using sulfuric acid solution as the solvent while stirring to obtain a solid-liquid mixture. The leaching conditions were: sulfuric acid concentration of 2.5 mol / L, liquid-to-solid ratio of 10:1 (L / kg), stirring rate of 500 rpm, leaching time of 10 min, and leaching at room temperature. The solid-liquid mixture obtained by leaching was centrifuged at 1500 rpm for 5 min to obtain leaching residue and leachate. The leachate mainly contained supersaturated silicic acid, magnesium sulfate and Fe 3+ , Ca 2+ 、Al 3+ Impurity ions such as PEG were dissolved in 20 ml of pure water to form a PEG solution, which was added dropwise to the leachate. At the same time, a shear-type stirring blade was used to mechanically stir the solution at a speed of 600 rpm at room temperature for 12 h, so that the supersaturated silicic acid in the solution gradually precipitated from the liquid phase and condensed into a colloid, forming a colloidal mixture consisting of colloidal fragments and the leachate. After vacuum filtration of the colloidal mixture, a semi-solid colloid and magnesium sulfate solution were obtained. The solution contained Fe 3+ , Ca 2+ 、Al 3+The semisolid colloid was washed six times with pure water until the solution was neutral, and then dehydrated to obtain jelly-like wet silica gel. The liquid-to-solid ratio used in each wash was 5:1 (L / kg). The wet silica gel was dried in a drying oven at 120°C for 10 hours to produce dry silica gel with a SiO2 content exceeding 99 wt%. The dry silica gel was calcined in a muffle furnace at 550°C for 6 hours to obtain white carbon black with a SiO2 content exceeding 99 wt%.

[0030] The magnesium sulfate solution containing impurities obtained after the above-mentioned separation of the glue can be used as a raw material for comprehensive recovery of magnesium, which is not specifically discussed in the present invention.

[0031] Table 1 Chemical composition of nickel-iron slag used in the present invention (wt%)

[0032] Remark: This symbol indicates that the unit of content is g / t.

[0033] The XRD patterns of silica gel and white carbon black prepared in this embodiment are as follows: Figure 2 and Figure 3 As shown, the product is composed only of amorphous silicon dioxide without any crystalline phase; the visible-infrared absorption spectra of the prepared silica gel and white carbon black are shown in Figure 4 、 Figure 5 As shown, the characteristic peaks of the absorption spectrum correspond to the characteristic peaks of silica. Figure 2 and Figure 3 The XRD analysis results show that the prepared products are silica gel and white carbon black. The SEM images of the prepared silica gel and white carbon black are as follows: Figure 6 、 Figure 7 As shown in the figure, the prepared silica is an aggregate of microporous structures formed by the agglomeration and growth of a large number of fine flaky particles, which is consistent with the porous micromorphology characteristics of silica. It can be seen from the figure that the generated silica gel is a submicron granular aggregate. Because the internal pore diameters of silica gel and silica are generally at the nanometer level (see the BET test results in Table 5), it is difficult to directly observe the internal pore diameters of submicron particles at this magnification.

[0034] Example 2: This embodiment provides a method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials. The raw materials and process are the same as those in Example 1, and there are some differences in the process parameters, which are as follows: The nickel-iron slag was dried at 100°C for 8 h, then placed in an agate ball mill and ball milled at 200 rpm for 6 h. After ball milling, the material was taken out and passed through a 200-mesh sieve to obtain nickel-iron slag fine powder. 20 g of nickel-iron slag fine powder was weighed as the solute for acid leaching. The solute was leached at room temperature using sulfuric acid solution as the solvent while stirring to obtain a solid-liquid mixture. The leaching conditions were: sulfuric acid concentration of 0.5 mol / L, liquid-solid ratio controlled at 15:1 (L / Kg), stirring rate of 300 rpm, leaching temperature of 80°C, and leaching time of 120 min. The solid-liquid mixture obtained by leaching was centrifuged at 500 rpm for 10 min to obtain leached residue and leachate. The leachate mainly contained supersaturated silicic acid, magnesium sulfate and Fe 3+ , Ca 2+ 、Al 3+ Impurity ions such as PEG. 0.1 g PEG was dissolved in 20 ml pure water to form a PEG solution, which was added dropwise to the leachate. At the same time, a shear-type stirring blade was used to mechanically stir at a speed of 200 rpm at room temperature for 14 h, so that the supersaturated silicic acid in the solution gradually precipitated from the liquid phase and condensed into a colloid, forming a colloidal mixture consisting of colloidal fragments and leachate. After vacuum filtration of the colloidal mixture, a semi-solid colloid and magnesium sulfate solution were obtained. The solution contained Fe 3+ , Ca 2+ 、Al 3+ The semisolid colloid was washed with pure water five times until the solution was neutral, yielding wet silica gel. The liquid-to-solid ratio for each wash was 6 (L / kg). The washed wet silica gel was dried in a drying oven at 100°C for 12 hours to produce dry silica gel with a SiO2 content exceeding 99 wt%. The dry silica gel was calcined in a muffle furnace at 480°C for 6 hours to yield white carbon black with a SiO2 content exceeding 99 wt%.

[0035] Example 3: This embodiment provides a method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials. The raw materials and process are the same as those in Example 1, and there are some differences in the process parameters, which are as follows: The nickel-iron slag was dried at 120°C for 4 h, then placed in an agate ball mill and ball milled at 500 rpm for 0.5 h. After ball milling, the material was taken out and passed through a 200-mesh sieve to obtain nickel-iron slag fine powder, and 20 g was weighed as the solute for acid leaching. Using sulfuric acid solution as the solvent, the solute was leached at room temperature while stirring to obtain a solid-liquid mixture. The leaching conditions were: sulfuric acid concentration of 3 mol / L, liquid-solid ratio controlled at 3:1 (L / Kg), stirring rate of 800 rpm, leaching time of 10 min, leaching at room temperature, and no heating. The solid-liquid mixture obtained by leaching was centrifuged at 3000 rpm for 5 min to obtain leached residue and leachate. The leachate mainly contained supersaturated silicic acid, magnesium sulfate and Fe 3+ , Ca 2+ 、Al 3+ Impurity ions such as PEG. 0.7 g PEG was dissolved in 20 ml pure water to form a PEG solution, which was added dropwise to the leachate. At the same time, a shear-type stirring blade was used to mechanically stir at 800 rpm at room temperature for 6 h, so that the supersaturated silicic acid in the solution gradually precipitated from the liquid phase and condensed into a colloid, forming a colloidal mixture consisting of colloidal fragments and leachate. After vacuum filtration of the colloidal mixture, a semi-solid colloid and magnesium sulfate solution were obtained. The solution contained Fe 3+ , Ca 2+ 、Al 3+ The semisolid colloid was washed seven times with pure water until the solution was neutral, yielding wet silica gel containing a small amount of surfactant. The liquid-to-solid ratio for each wash was 4:1 (L / kg). The cleaned wet silica gel was dried in a drying oven at 120°C for 6 hours to produce dry silica gel with a SiO2 content exceeding 99 wt%. The dry silica gel was calcined in a muffle furnace at 580°C for 2 hours to yield white carbon black with a SiO2 content exceeding 99 wt%.

[0036] Example 4: This embodiment provides a method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials. The raw materials and process are the same as those in Example 1, and there are some differences in the process parameters, which are as follows: The nickel-iron slag was dried at 110°C for 6 h, then placed in an agate ball mill and ball milled at 400 rpm for 3 h. After ball milling, the material was taken out and passed through a 200-mesh sieve to obtain nickel-iron slag fine powder, and 20 g was weighed as the solute for acid leaching. Using sulfuric acid solution as the solvent, the solute was leached at room temperature while stirring to obtain a solid-liquid mixture. The leaching conditions were: sulfuric acid concentration of 2 mol / L, liquid-solid ratio controlled at 10:1 (L / Kg), stirring rate of 500 rpm, leaching time of 30 min, leaching at room temperature, and no heating. The solid-liquid mixture obtained by leaching was centrifuged at 1500 rpm for 7 min to obtain leached residue and leachate. The leachate mainly contained supersaturated silicic acid, magnesium sulfate and Fe 3+ , Ca 2+ 、Al 3+ Impurity ions such as PEG were dissolved in 20 ml of pure water to form a PEG solution, which was added dropwise to the leachate. At the same time, a shear-type stirring blade was used to mechanically stir the solution at a speed of 500 rpm at room temperature for 8 hours, so that the supersaturated silicic acid in the solution gradually precipitated from the liquid phase and condensed into a colloid, forming a colloidal mixture consisting of colloidal fragments and leachate. After vacuum filtration of the colloidal mixture, a semi-solid colloid and magnesium sulfate solution were obtained. The solution contained Fe 3+ , Ca 2+ 、Al 3+ The semisolid colloid was washed seven times with pure water until the solution was neutral, yielding wet silica gel containing a small amount of surfactant. The liquid-to-solid ratio for each wash was 5:1 (L / kg). The cleaned wet silica gel was dried in a drying oven at 110°C for 4 hours to produce dry silica gel with a SiO2 content exceeding 99wt%. The dry silica gel was calcined in a muffle furnace at 520°C for 4 hours to yield white carbon black with a SiO2 content exceeding 99wt%.

[0037] Example 5: This example provides a method for efficiently preparing silica gel and silica using smelting slag as raw material. The preparation steps are similar to those of Example 4, differing only in that no surfactant is added during the gel formation process. The purity of the silica gel and silica prepared is not significantly different from that of Example 1. However, the pore size and specific surface area of the silica gel and silica prepared in this example are relatively small.

[0038] Example 6: This embodiment provides a method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials. The process is the same as that of Example 1, but the solvent used is different. The solvent used in Example 1 is sulfuric acid solution, while the solvent used in this embodiment is hydrochloric acid solution. Although the process of this embodiment is the same as that of Example 1, there are differences in the leachate composition, the liquid phase composition after the separation of the colloid, the recovery rate of silicon, the slag rate, etc. After leaching, this embodiment obtains a product containing supersaturated silicic acid, FeCl2 and CaCl2. 2+ 、Al 3+ Mg 2+ After the separation of the glue, the liquid phase is mainly ferrous chloride solution, which contains Ca 2+ 、Al 3+ Mg 2+ In the future, it is possible to consider comprehensive recovery of Fe to prepare ferrous chloride, ferric hydroxide and other substances.

[0039] Example 7: The present embodiment provides a method for efficiently preparing silica gel and white carbon black using smelting slag as raw material. The preparation process is similar to that of Example 2, except that the sulfuric acid concentration used during sulfuric acid leaching is 3 mol / L and the stirring rate is 600 rpm. The difference is also that the raw material ferronickel slag used has different crystallization degrees. The ferronickel slag type is still electric furnace type ferronickel slag, which comes from the same manufacturer as the ferronickel slag of Example 1, but the production year is different. It is an air-cooled product with a higher crystallization degree. The XRD characteristics of the ferronickel slag are as follows: Figure 8 The chemical composition is shown in Table 2, where the crystalline substance is (Mg, Fe)2SiO4 phase and the amorphous substance is amorphous SiO2.

[0040] Table 2 Chemical composition of the crystalline and amorphous mixed nickel-iron slag used in this example (wt%)

[0041] Example 8: This embodiment provides a method for efficiently preparing silica gel and white carbon black using smelting slag as raw material. The process is the same as that of Example 1, but the raw materials used are different. The raw material used in Example 1 is nickel-iron slag, while the raw material used in this embodiment is copper smelting slag. The composition of the copper smelting slag is shown in Table 3, and its XRD is shown in Table 3. Figure 9 As shown, the main phase structure of the slag is fayalite Fe2SiO4 phase. Although the process of this embodiment is the same as that of embodiment 1, there are differences in the composition of the leachate, the composition of the liquid phase after the separation of the glue, the recovery rate of silicon, the slag rate, etc. After leaching, the slag obtained in this embodiment contains supersaturated silicic acid, ferrous sulfate and Ca 2+ 、Al 3+ 、Zn 2+ Mg2+ 、Na + The leaching solution of impurity ions such as ferrous sulfate and Ca 2+ 、Al 3+ 、Zn 2+ Mg 2+ 、Na + Impurities, in the future, comprehensive recovery of Fe may be considered to prepare ferrous sulfate or ferric hydroxide.

[0042] Table 3 Chemical composition of copper smelting slag (wt%)

[0043] Example 9: This embodiment provides a method for efficiently preparing silica gel and white carbon black using smelting slag as raw material. The process method is the same as that of Example 5, but the raw materials used are different. The raw material used in Example 5 is nickel-iron slag, while the raw material used in this embodiment is copper smelting slag.

[0044] The chemical compositions of silica gel and white carbon black prepared in the above examples are shown in Table 4: Table 4 Chemical composition of silica gel and white carbon black prepared by the technology of the present invention (mg / kg)

[0045] Note: The symbol " " indicates that the unit of content is wt%. The symbol "-" indicates that the content is below the detection limit of the instrument and is not detected.

[0046] The specific surface area (m 2 / g), average pore size (nm) and pore volume (cm 3 / g) as shown in Table 5: Table 5 Specific surface area, average pore diameter and pore volume of prepared silica

[0047] Comparative Example 1: The process method and process parameters of this comparative example are exactly the same as those of Example 4, and the only difference is the raw material. The raw material used in this example is zinc leaching residue, and its chemical composition is shown in Table 6.

[0048] Table 6 Chemical composition of zinc leaching residue produced by hydrometallurgy (wt%)

[0049] Note: The remaining components are mainly O elements.

[0050] During the leaching process in this comparative example, most of the SiO₂ was not leached. Furthermore, the leachate was very unstable during the leaching process, resulting in a large amount of silicate sol, which inhibited further dissolution of the reactants. After centrifugation, the precipitated silicate sol mixed with the leached residue, making further separation difficult. The Si leaching rate was only 12.5%. The resulting leachate had a low degree of silicate supersaturation, and no silica gel precipitation was observed after stirring for 8 hours.

[0051] Comparative Example 2: The process and process parameters of this comparative example are exactly the same as those of Example 4, with the only difference being the raw materials. The raw materials used in this example are metallurgical waste red mud generated during the alumina production process, the chemical composition of which is shown in Table 7.

[0052] Table 7 Chemical composition of red mud used (wt%)

[0053] Note: The remaining ingredients are mainly crystal water.

[0054] In the comparative example, most of the SiO2 was not leached during the leaching process, and the Si leaching rate was only 10.1%. The resulting leachate had a low degree of silicic acid supersaturation and no silica gel precipitation was observed after stirring for 8 hours.

[0055] In summary, the present invention discloses a method for efficiently preparing silica gel and white carbon black using smelting slag as raw material; the method comprises the following steps: dissolving nickel-iron slag or copper smelting slag rich in SiO2 under suitable acid leaching conditions, and obtaining a supersaturated silicic acid solution after centrifugal separation; at room temperature and in an open environment, utilizing stirring and surface activation to control the precipitation rate of silica gel in the system, and adjusting the structure, morphology and size of the silica gel particles to form a gel-liquid mixture containing silica gel fine particles; after the gel-liquid is separated, the wet silica gel is washed and dried to obtain dry silica gel, and after roasting, white carbon black with a SiO2 content greater than 99 wt% is obtained; the method adopts an alkali-free preparation process using smelting waste slag as raw material, and has the advantages of wide raw material adaptability, low energy consumption, low production cost, and good product quality.

[0056] At this point, those skilled in the art will recognize that, although the embodiments of the present invention have been shown and described in detail herein, many other variations or modifications consistent with the principles of the present invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and deemed to cover all such other variations or modifications.

Claims

1. A method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials, characterized in that: The specific steps of the method are: Step S1: Pretreatment of silicon-containing materials The smelting slag is dried at 100-120°C for 4-8 hours, then ball-milled at 200-500 rpm for 0.5-6 hours, and then passed through a 200-mesh or higher sieve to obtain a powder of appropriate particle size. The powder is weighed and used as the solute for the next step of acid leaching. Step S2: Acid leaching Leaching the powder of suitable particle size obtained in step S1 with an acid solution, stirring the leaching process to dissolve the silicon minerals in the smelting slag into the solution, while the gangue components remain in the slag, to obtain a slag-liquid mixture; Step S3: Slag-liquid separation The slag-liquid mixture obtained in step S2 is separated to obtain a supersaturated silicic acid solution with suitable stability and a leached slag mainly composed of gangue components; Step S4: Gluing The supersaturated silicic acid solution with suitable stability obtained in step S3 is stirred to gradually precipitate the supersaturated silicic acid in the solution, and silica gel particles are formed after nucleation, growth, and coagulation, and are suspended in the solution to obtain a suspension containing silica gel particles; the stirring rate is 200 to 800 rpm, and the stirring time is 6 to 14 hours; Step S5: Separation of glue and liquid The suspension containing silica gel particles obtained in step S4 is vacuum filtered to obtain jelly-like wet silica gel containing impurities and a mixed solution of acid and salt containing impurities; Step S6: Washing and drying The jelly-like wet silica gel containing impurities obtained in step S5 is washed with pure water having a liquid-to-solid ratio of 4:1 to 6:1 for 5 to 7 steps, and then dried at 100 to 120° C. for 6 to 12 hours to obtain dry silica gel; Step S7: calcining the dry silica gel prepared in step S6 at 480-580° C. for 2-6 h to decompose the silica gel to generate white carbon black having a SiO2 content exceeding 99 wt%; In step S4, the supersaturated silicic acid solution is stirred, and a surfactant is added to slow down the silica gel nucleation growth rate and adjust the microstructure of the white carbon black; The surfactant is a polyethylene glycol (PEG) solution, and the amount of PEG added is 0.5% to 3.5% of the mass of the silicon-containing material.

2. The method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials according to claim 1, characterized in that: The smelting slag in step S1 is a silicon-containing material of nickel-iron slag or copper smelting slag, which is rich in SiO2.

3. The method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials according to claim 1, characterized in that: The acid solution in step S2 is sulfuric acid or hydrochloric acid solution.

4. The method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials according to claim 1, characterized in that: In step S3, the slag-liquid separation is carried out by centrifugal filtration, vacuum filtration or pressure filtration.

5. The method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials according to claim 1, characterized in that: The purity of the dry silica gel in step S6 exceeds 99 wt %.

6. The method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials according to claim 1, characterized in that: The leaching conditions in step S2 are: acid concentration of 0.5-3 mol / L, liquid-solid ratio of 3-15:1, leaching temperature of 20-80°C, leaching time of 10-120 min, and stirring rate of 300-800 rpm.

7. The method for efficiently preparing silica gel and white carbon black using smelting slag as raw materials according to claim 4, characterized in that: The centrifugal filtration separation conditions are: the rotation speed is controlled at 500-3000 rpm, and the centrifugal separation time is 5-10 min.

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