阅读说明：本技术 一种煤粉炉粉煤灰酸法提铝尾渣低温下制备α-层状硅酸钠的方法 (Method for preparing alpha-layered sodium silicate at low temperature from coal powder furnace fly ash acid method aluminum extraction tailings ) 是由 张丽宏 郭彦霞 薛芳斌 程芳琴 于 2020-05-08 设计创作，主要内容包括：一种煤粉炉粉煤灰酸法提铝尾渣低温下制备α-层状硅酸钠的方法,属于工业固体废弃物粉煤灰的资源化利用及层状硅酸钠合成领域,可解决现有α-层状硅酸钠的制备方法原料成本高、需要添加晶种、工艺复杂等问题,煤粉炉粉煤灰经过碳酸钠活化-盐酸酸浸-固液分离后,固体经过洗涤、干燥后为提铝尾渣。将提铝尾渣在超声作用下溶于氢氧化钠中得到硅酸钠溶液。以硅酸钠溶液为原料,升温到650-740℃,焙烧20-120min,冷却后得到α-层状硅酸钠产品。该方法既为粉煤灰酸法提铝尾渣提供了新的应用途径,又为层状硅酸钠产品提供了低廉、高活性的硅源,降低了α-层状硅酸钠的晶化温度,节约成本,有利于层状硅酸钠产品大规模生产。(A method for preparing alpha-layered sodium silicate at low temperature by coal powder furnace fly ash acid-process aluminum extraction tailings belongs to the field of resource utilization of industrial solid waste fly ash and synthesis of layered sodium silicate, and can solve the problems that the existing preparation method of alpha-layered sodium silicate is high in raw material cost, needs to add crystal seeds, is complex in process and the like. Dissolving the aluminum extraction tailings in sodium hydroxide under the action of ultrasonic waves to obtain a sodium silicate solution. Using sodium silicate solution as raw material, heating to 650-740 ℃, roasting for 20-120min, and cooling to obtain the alpha-layered sodium silicate product. The method provides a new application approach for the tailings of the acid extraction of aluminum from the fly ash, provides a low-cost and high-activity silicon source for the layered sodium silicate product, reduces the crystallization temperature of the alpha-layered sodium silicate, saves the cost, and is beneficial to the large-scale production of the layered sodium silicate product.)

1. A method for preparing alpha-layered sodium silicate at low temperature by using coal powder furnace fly ash acid method aluminum extraction tailings is characterized by comprising the following steps: the method comprises the following steps:

step one, extracting aluminum tailings: uniformly mixing pulverized coal furnace fly ash and sodium carbonate according to a proportion, grinding until the average particle size is 50-100 mu m, roasting at 800-900 ℃ for 0.5-1.5h to obtain a roasted product, mixing the roasted product and 5-20wt.% of hydrochloric acid according to a proportion, reacting at 60-100 ℃ for 0.5-1.5h, filtering and washing to neutrality after the reaction is finished to obtain aluminum extraction tailings;

step two, preparing a sodium silicate solution: extracting aluminum tailings with SiO₂Calculated as Na, the sodium hydroxide solution₂In terms of O, dissolving the aluminum extraction tailings in a sodium hydroxide solution with the mass fraction of 4% -20% under the ultrasonic action according to a proportion to obtain a sodium silicate solution;

thirdly, heating the sodium silicate solution to 650-740 ℃, and roasting for 20-120min to obtain the alpha-layered sodium silicate product.

2. The method for preparing alpha-layered sodium silicate at low temperature from coal powder furnace fly ash acid-process aluminum extraction tailings according to claim 1, which is characterized by comprising the following steps: in the first step, the mass ratio of the pulverized coal furnace fly ash to the sodium carbonate is 0.5-1.5: 1.

3. The method for preparing alpha-layered sodium silicate at low temperature from coal powder furnace fly ash acid-process aluminum extraction tailings according to claim 1, which is characterized by comprising the following steps: in the first step, the solid-liquid mass ratio of the roasted product to the hydrochloric acid is 1:3-1: 10.

4. The method for preparing α -layered sodium silicate at low temperature from coal powder furnace fly ash acid-process aluminum extraction tailings as claimed in claim 1, wherein the SiO in the second step₂And Na₂The molar ratio of O is 1.5-2.5: 1.

5. The method for preparing alpha-layered sodium silicate at low temperature from coal powder furnace fly ash acid-process aluminum extraction tailings according to claim 1, which is characterized by comprising the following steps: and in the third step, the heating rate of the heating is 15-40 ℃/min.

Technical Field

The invention belongs to the technical field of resource utilization of industrial solid waste fly ash and synthesis of layered sodium silicate, and particularly relates to a method for preparing alpha-layered sodium silicate at low temperature from tailings generated by acid-process aluminum extraction of fly ash in a pulverized coal furnace.

Background

Fly ash is one of the large solid wastes generated by coal-fired power plants, and about 1.8 million tons of fly ash are not utilized every year. The fly ash is rich in a plurality of metal elements such as main metal element aluminum and trace metal element lithium gallium, and the like, and the multi-element synergistic extraction is one of important ways for realizing the high-value utilization of the fly ash. The coal powder furnace has high coal ash discharge amount, is ash generated by high-quality coal powder at the ash forming temperature of over 1200 ℃, and has the same crystal phase composition as mullite, quartz and corundum which are difficult to activate. By adopting the sodium carbonate activation-hydrochloric acid leaching process, the leaching rate of aluminum reaches more than 90 percent, and meanwhile, the byproduct of aluminum extraction tailings is obtained. In order to realize the synchronous utilization of aluminum and silicon in the fly ash and avoid secondary pollution caused by silicon slag, the high-value utilization of silicon is an urgent need for improving the economic, environmental and ecological benefits of the process.

The layered sodium silicate has various crystal structures of alpha, beta and the like, has the characteristics of large calcium and magnesium ion exchange capacity, strong buffering capacity and environmental friendliness, is used as a builder in a detergent to replace sodium tripolyphosphate, realizes the non-phosphorization of the detergent, and has performance superior to that of a non-phosphorus assistant 4A zeolite molecular sieve. The application No. 200410012440.5 uses the commercial liquid water glass as the silicon source and the sodium source, needs to add 3-30% of mixed crystal seeds with alpha phase content of more than 60%, and can obtain the alpha-layered sodium silicate by calcining at 750-800 ℃. The application number is 201510033360.6, the rice hull ash is put into sodium hydroxide solution for leaching, the leaching needs 1-6h, the filtered filtrate is added with sodium hydroxide to adjust the ratio of silica to sodium, the drying is carried out at the temperature of 100-. The existing preparation method of alpha-layered sodium silicate has the problems of high raw material cost, need of adding seed crystal, complex process and the like, and particularly has higher crystallization temperature.

In conclusion, the inventor takes the aluminum extraction tailings of the pulverized coal furnace fly ash after sodium carbonate activation and hydrochloric acid leaching as the raw material, adopts rapid heating and low-temperature roasting to realize large-scale controllable synthesis of the alpha-layered sodium silicate, and has no relevant report at home and abroad.

Disclosure of Invention

The invention provides a method for preparing alpha-layered sodium silicate at low temperature by coal powder furnace fly ash acid method aluminum extraction tailings, aiming at the problems of high raw material cost, seed crystal addition, complex process and the like of the existing preparation method of alpha-layered sodium silicate. The method has the advantages of low raw material price, simple process flow, low crystallization temperature, low energy consumption and low synthesis cost; the synthesized layered sodium silicate material has single crystal form and high alpha phase content, and has wide application prospect in the field of detergents.

The invention adopts the following technical scheme:

a method for preparing alpha-layered sodium silicate at low temperature by using coal powder furnace fly ash acid method aluminum extraction tailings comprises the following steps:

step one, extracting aluminum tailings: uniformly mixing pulverized coal furnace fly ash and sodium carbonate according to a proportion, grinding until the average particle size is 50-100 mu m, roasting at 800-900 ℃ for 0.5-1.5h to obtain a roasted product, mixing the roasted product and 5-20wt.% of hydrochloric acid according to a proportion, reacting at 60-100 ℃ for 0.5-1.5h, filtering and washing to neutrality after the reaction is finished to obtain aluminum extraction tailings;

step two, preparing a sodium silicate solution: extracting aluminum tailings with SiO₂Calculated as Na, the sodium hydroxide solution₂In terms of O, dissolving the aluminum extraction tailings in a sodium hydroxide solution with the mass fraction of 4% -20% under the ultrasonic action according to a proportion to obtain a sodium silicate solution;

thirdly, heating the sodium silicate solution to 650-740 ℃, and roasting for 20-120min to obtain the alpha-layered sodium silicate product.

In the first step, the mass ratio of the pulverized coal furnace fly ash to the sodium carbonate is 0.5-1.5: 1.

In the first step, the solid-liquid mass ratio of the roasted product to the hydrochloric acid is 1:3-1: 10.

In the second step the SiO₂And Na₂The molar ratio of O is 1.5-2.5: 1.

And in the third step, the heating rate of the heating is 15-40 ℃/min.

The invention has the following beneficial effects:

the method adopts the fly ash acid method aluminum extraction tailings to prepare the alpha-layered sodium silicate, thereby not only increasing the economic, environmental and social benefits of the fly ash acid method aluminum extraction process, but also obviously reducing the forming temperature of the alpha-layered sodium silicate, shortening the forming time, reducing the cost and obviously improving the economic value of the product.

Drawings

FIG. 1 is an XRD pattern of the tailings of the acid method for extracting aluminum from fly ash.

Fig. 2 is an XRD pattern of the α -layered sodium silicate prepared in example 1 of the present invention.

Fig. 3 is an XRD pattern of the α -layered sodium silicate prepared in example 2 of the present invention.

Detailed Description