阅读说明：本技术 一种利用高炉渣制备具有吸波功能二氧化硅的方法 (Method for preparing silicon dioxide with wave absorbing function by using blast furnace slag ) 是由 申星梅 王健 李辽沙 徐致远 武杏荣 曹发斌 于 2021-04-02 设计创作，主要内容包括：本发明公开了一种利用高炉渣制备具有吸波功能二氧化硅的方法,属于冶金渣综合利用领域。该方法将高炉渣中很难去除的微量铁离子作为吸波功能组元,而非杂质,与外加铁源一起经酸解、固液分离、调节滤液pH、陈化、加有机还原剂后煅烧制得。本发明可省去高炉渣制备二氧化硅过程中流程长、能耗高的除铁工序,简化生产工艺；同时赋予二氧化硅吸波功能,提高了产品附加值,拓宽了其应用领域。本发明解决了现有高炉渣制备二氧化硅技术中产品质量参差不齐或经济不合理的问题,同时实现了固废再利用,对我国冶金产业绿色发展和可持续发展具有积极的意义。(The invention discloses a method for preparing silicon dioxide with a wave-absorbing function by using blast furnace slag, belonging to the field of comprehensive utilization of metallurgical slag. The method takes trace iron ions which are difficult to remove in the blast furnace slag as wave-absorbing functional components, but not impurities, and the trace iron ions and an external iron source are subjected to acidolysis, solid-liquid separation, filtrate pH adjustment, aging, addition of an organic reducing agent and calcination to obtain the composite material. The invention can save the iron removal process with long flow and high energy consumption in the process of preparing the silicon dioxide by the blast furnace slag, and simplify the production process; meanwhile, the silicon dioxide is endowed with a wave absorbing function, the added value of the product is improved, and the application field of the product is widened. The invention solves the problems of uneven product quality or unreasonable economy in the existing technology for preparing silicon dioxide by using blast furnace slag, realizes the reutilization of solid waste, and has positive significance for green development and sustainable development of the metallurgical industry in China.)

1. A method for preparing silicon dioxide with wave-absorbing function by using blast furnace slag is characterized by comprising the following steps:

(1) uniformly mixing blast furnace slag and an external iron source, and adding the mixture into a container containing a sulfuric acid solution to be stirred and react for 30 min;

the external iron source is trivalent ferric salt; the mass ratio of the blast furnace slag to the ferric iron salt is 1: 0.4-1.2;

(2) carrying out solid-liquid separation on the product obtained in the step (1), adjusting the pH value of the filtrate to 2.1-2.9 by using alkali liquor, and standing and aging;

(3) washing and drying the aging product obtained in the step (2), adding citric acid, and uniformly mixing;

the mass ratio of the aging product to the citric acid is 1: 4;

(4) preheating the mixture obtained in the step (3), calcining, washing and drying to obtain a target product: silicon dioxide with wave absorbing function.

2. The method for preparing the silicon dioxide with the wave-absorbing function by using the blast furnace slag according to the claim 1, is characterized in that: the average grain diameter of the blast furnace slag in the step (1) is 0.7 mm.

3. The method for preparing the silicon dioxide with the wave-absorbing function by using the blast furnace slag according to the claim 1, is characterized in that: the mass ratio of the blast furnace slag to the ferric iron salt in the step (1) is 1: 1.

4. The method for preparing the silicon dioxide with the wave-absorbing function by using the blast furnace slag according to the claim 1, is characterized in that: and (3) adjusting the pH value of the filtrate to 2.9 by using alkali liquor in the step (2).

Technical Field

The invention belongs to the field of comprehensive utilization of metallurgical slag, and particularly relates to a method for preparing silicon dioxide with wave-absorbing property by finely utilizing blast furnace slag.

Background

Blast furnace slag is a waste discharged in the blast furnace ironmaking process, and the utilization rate is close to 100 percent at present. However, the traditional extensive utilization occupies a large proportion and is mainly focused on the field of building materials; the utilization technology which has higher added value and mainly synthesizes solution has the problems of uneven product quality, unreasonable economy and the like mostly, and finally cannot be widely applied. The blast furnace slag contains 30-40% of silicon component and can be used as raw material for extracting silicon dioxide. There are many reports of using silicon-containing solid wastes to prepare silicon dioxide, and most of the processes involve leaching, aging, separation, drying and the like.

Document CN201510651029.0 discloses a method for preparing white carbon black by using water-quenched blast furnace slag, which comprises grinding blast furnace slag to a certain particle size, performing acid leaching, performing ultrasonic dispersion, performing water bath heating, and finally cooling, centrifuging and drying to obtain white carbon black. Although the process and the reaction conditions are simple, the purity of the product is difficult to control, and particularly, the iron component with the content of less than 1 percent in the slag is often accompanied in a silicon dioxide product and is difficult to remove, so that the whiteness of the product is influenced.

Document CN201610381604.4 discloses a method for preparing nano-scale silica from slag, which comprises melting slag and soda ash, water quenching, washing with hydrochloric acid, wet grinding, adding ammonium nitrate after cation exchange resin, adjusting pH, standing for aging, washing, drying, and adding starch for calcination. The method adopts sodium carbonate to extract silicon in slag at high temperature, and then removes impurities through acid washing, ion exchange resin and other steps; however, the method has the problems of long process flow, high energy consumption and the like, and is economically unreasonable.

Document CN201610381980.3 discloses a method for extracting silica from slag, which adopts alkali liquor to dissolve pretreated slag, introduces carbon dioxide into filtrate for filtration, adds ethyl acetate and sulfuric acid, and finally separates and dries. The method adopts an alkaline leaching mode, so that impurities such as iron ions and the like can be effectively prevented from entering the solution, and the silicon dioxide with the purity of over 98 percent is obtained; however, the direct alkaline leaching of blast furnace slag has low activity, needs multi-step pretreatment to improve the activity, and also has the problems of long flow, high energy consumption, unreasonable economy and the like.

In conclusion, in the prior art for preparing silicon dioxide by using blast furnace slag, the product quality with simple process flow is not high, particularly, the influence of iron ions is serious, and the whiteness of the product can be obviously influenced by trace iron ions in the slag, so that the application is limited; the process flow is complex, and products with good quality can be obtained, but the process flow is not reasonable economically, so that the process flow cannot be applied.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for preparing the silicon dioxide with the wave-absorbing function by finely utilizing the blast furnace slag, which has the advantages of simple process, economy, reasonability, high product quality and high additional value.

In order to achieve the purpose, the invention is realized by the following technical scheme.

The invention takes the trace iron ions which are difficult to remove in the blast furnace slag as the wave-absorbing functional components, but not impurities, and is prepared by acidolysis, solid-liquid separation, filtrate pH adjustment, aging, addition of organic reducing agent and calcination together with an external iron source, and the method specifically comprises the following steps:

(1) uniformly mixing blast furnace slag and an external iron source, and adding the mixture into a container containing a sulfuric acid solution to be stirred and react for 30 min; the external iron source is trivalent ferric salt; the mass ratio of the blast furnace slag to the ferric iron salt is 1: 0.4-1.2.

(2) And (3) carrying out solid-liquid separation on the product obtained in the step (1), adjusting the pH value of the filtrate to 2.1-2.9 by using alkali liquor, and standing and aging.

(3) Washing and drying the aging product obtained in the step (2), adding citric acid, and uniformly mixing; the mass ratio of the aging product to the citric acid is 1: 4.

(4) Preheating the mixture obtained in the step (3), calcining, washing and drying to obtain a target product: silicon dioxide with wave absorbing function.

Further, the average grain size of the blast furnace slag in the step (1) is 0.7 mm.

Further, the mass ratio of the blast furnace slag to the ferric iron salt in the step (1) is 1: 1.

Further, adjusting the pH value of the filtrate to 2.9 by using alkali liquor in the step (2).

The scientific principle of the invention is as follows:

after the blast furnace slag and the ferric salt are mixed and added with the sulfuric acid, the calcium component in the slag is CaSO₄The other components are respectively in H form₃SiO₄ ^－、Fe³⁺、Al³⁺、Mg²⁺Etc. into the liquid phase. Due to Al³⁺、Mg²⁺The pH values of the initial precipitates are respectively 3 and 9, and the pH value of the filtrate is controlled after solid-liquid separation<3, can make Al³⁺、Mg²⁺Impurities remain in the liquid phase; fe³⁺The pH of the initial precipitate of (2) and controlling the filtrate 2<pH value<3, i.e. Al³⁺、Mg²⁺While remaining in the liquid phase, Fe³⁺Precipitate is Fe (OH)₃. During the aging process, H₃SiO₄ ^－Gradually polymerising and dehydrating to form SiO₂With Fe³⁺Together into the solid phase. Subsequently, the SiO produced₂-Fe(OH)₃Calcining the mixture in the atmosphere of reducing and oxidizing to obtain the SiO with the wave absorbing function₂-γFe₂O₃。

Compared with the prior art, the invention has the following technical effects:

1. the invention takes the trace iron ions which are difficult to remove from the blast furnace slag as the wave-absorbing functional component rather than impurities, and can save the iron removal process with long flow and high energy consumption, thereby simplifying the production process and reducing the product cost.

2. The invention endows the silicon dioxide with wave absorbing function, can improve the added value of the product and broadens the application field of the product. The maximum wave-absorbing strength of the silicon dioxide prepared by the method is-5.2 dB.

3. The invention solves the problems of uneven product quality or unreasonable economy in the prior art for preparing silicon dioxide by using blast furnace slag.

4. The invention realizes the reutilization of solid wastes and has positive significance for the green development and sustainable development of the metallurgical industry in China.

Detailed Description

The invention is further illustrated by the following examples.

Example 1

Weighing 9.0g of blast furnace slag with the average particle size of 0.7mm, adding 9.0g of ferric sulfate as an external iron source, and uniformly mixing in a mortar; taking 70g of sulfuric acid solution with the mass concentration of 15%, and slowly adding the mixture of blast furnace slag and ferric sulfate into the sulfuric acid solution at a trickle velocity of 0.5g/s under the stirring condition; after reacting for 30min, putting the product on a suction filter for solid-liquid separation; putting the filtrate into a container, dropwise adding 1mol/L sodium hydroxide solution under the stirring condition, adjusting the pH value of the system to 2.9, and then aging in an oven at 100 ℃ for 12 hours; after centrifugally washing and drying the aged sample, uniformly mixing the sample with citric acid according to the mass ratio of 1:4, and preheating the mixture in a muffle furnace at 150 ℃ for 30 min; after the mixture is completely melted, the temperature of the muffle furnace is raised to 400 ℃ for calcining for 2h, and the mixture is washed and dried.

Example 2

Weighing 9.0g of blast furnace slag with the average particle size of 0.7mm, adding 10.8g of ferric sulfate as an external iron source, and uniformly mixing in a mortar; taking 70g of sulfuric acid solution with the mass concentration of 15%, and slowly adding the mixture of blast furnace slag and ferric sulfate into the sulfuric acid solution at a trickle velocity of 0.5g/s under the stirring condition; after reacting for 30min, putting the product on a suction filter for solid-liquid separation; putting the filtrate into a container, dropwise adding 1mol/L sodium hydroxide solution under the stirring condition, adjusting the pH value of the system to 2.1, and then aging in an oven at 100 ℃ for 12 hours; after centrifugally washing and drying the aged sample, uniformly mixing the sample with citric acid according to the mass ratio of 1:4, and preheating the mixture in a muffle furnace at 150 ℃ for 30 min; after the mixture is completely melted, the temperature of the muffle furnace is raised to 400 ℃ for calcining for 2h, and the mixture is washed and dried.

Comparative example 1

Weighing 9.0g of blast furnace slag with the average particle size of 0.7mm, taking 70g of sulfuric acid solution with the mass concentration of 15%, and slowly adding the blast furnace slag into the sulfuric acid solution at the trickle speed of 0.5g/s under the stirring condition; after reacting for 30min, putting the product on a suction filter for solid-liquid separation; putting the filtrate into a container, dropwise adding 1mol/L sodium hydroxide solution under the stirring condition, adjusting the pH value of the system to 2.9, and then aging in an oven at 100 ℃ for 12 hours; after centrifugally washing and drying the aged sample, uniformly mixing the sample with citric acid according to the mass ratio of 1:4, and preheating the mixture in a muffle furnace at 150 ℃ for 30 min; after the mixture is completely melted, the temperature of the muffle furnace is raised to 400 ℃ for calcining for 2h, and the mixture is washed and dried.

Comparative example 2

Weighing 9.0g of blast furnace slag with the average particle size of 0.7mm, adding 2.7g of ferric sulfate as an external iron source, and uniformly mixing in a mortar; taking 70g of sulfuric acid solution with the mass concentration of 15%, and slowly adding the mixture of blast furnace slag and ferric sulfate into the sulfuric acid solution at a trickle velocity of 0.5g/s under the stirring condition; after reacting for 30min, putting the product on a suction filter for solid-liquid separation; putting the filtrate into a container, dropwise adding 1mol/L sodium hydroxide solution under the stirring condition, adjusting the pH value of the system to 2.9, and then aging in an oven at 100 ℃ for 12 hours; after centrifugally washing and drying the aged sample, uniformly mixing the sample with citric acid according to the mass ratio of 1:4, and preheating the mixture in a muffle furnace at 150 ℃ for 30 min; after the mixture is completely melted, the temperature of the muffle furnace is raised to 400 ℃ for calcining for 2h, and the mixture is washed and dried.

Comparative example 3

Weighing 9.0g of blast furnace slag with the average particle size of 0.7mm, adding 9.0g of ferric sulfate as an external iron source, and uniformly mixing in a mortar; taking 70g of sulfuric acid solution with the mass concentration of 15%, and slowly adding the mixture of blast furnace slag and ferric sulfate into the sulfuric acid solution at a trickle velocity of 0.5g/s under the stirring condition; after reacting for 30min, putting the product on a suction filter for solid-liquid separation; putting the filtrate into a container, dropwise adding 1mol/L sodium hydroxide solution under the stirring condition, adjusting the pH value of the system to 1.9, and then aging in an oven at 100 ℃ for 12 hours; after centrifugally washing and drying the aged sample, uniformly mixing the sample with citric acid according to the mass ratio of 1:4, and preheating the mixture in a muffle furnace at 150 ℃ for 30 min; after the mixture is completely melted, the temperature of the muffle furnace is raised to 400 ℃ for calcining for 2h, and the mixture is washed and dried.

Comparative example 4

Weighing 9.0g of blast furnace slag with the average particle size of 0.7mm, adding 9.0g of ferric sulfate as an external iron source, and uniformly mixing in a mortar; taking 70g of sulfuric acid solution with the mass concentration of 15%, and slowly adding the mixture of blast furnace slag and ferric sulfate into the sulfuric acid solution at a trickle velocity of 0.5g/s under the stirring condition; after reacting for 30min, putting the product on a suction filter for solid-liquid separation; putting the filtrate into a container, dropwise adding 1mol/L sodium hydroxide solution under the stirring condition, adjusting the pH value of the system to 1.9, and then aging in an oven at 100 ℃ for 12 hours; after centrifugally washing and drying the aged sample, uniformly mixing the sample with succinic acid according to the mass ratio of 1:4, and preheating the mixture in a muffle furnace at the temperature of 150 ℃ for 30 min; after the mixture is completely melted, the temperature of the muffle furnace is raised to 400 ℃ for calcining for 2h, and the mixture is washed and dried.

According to the methods of the examples and the comparative examples, the wave absorbing performance of the obtained silica is respectively tested, and the specific results are shown in table 1:

TABLE 1 wave-absorbing Properties of the silicas obtained in the examples and comparative examples

According to test results, the silicon dioxide prepared by the method has a wave absorbing function. In addition, the invention omits the iron removal process with long flow and high energy consumption in the prior art for preparing silicon dioxide by using blast furnace slag, and simplifies the production process; meanwhile, the silicon dioxide is endowed with a wave absorbing function, the added value of the product is improved, and the application field of the product is widened.

It is clear that the specific implementation of the invention is not restricted to the above-described embodiments, but that various insubstantial modifications of the inventive process concept and technical solutions are within the scope of protection of the invention.