阅读说明：本技术 一种低毒磷石膏基高强人造骨料及其制备方法 (Low-toxicity phosphogypsum-based high-strength artificial aggregate and preparation method thereof ) 是由 黄绪泉 董江峰 王小书 赵小蓉 刘立明 王再骞 史子瑶 刘亮 于 2020-06-17 设计创作，主要内容包括：本发明提供一种低毒磷石膏基高强人造骨料制备方法,该混合材料包括如下干重量百分数的原料组成：磷石膏、矿渣粉、水泥窑灰、改性剂。所述的改性剂由氯化钙、木质磺酸钠、膨润土、电石渣粉和干酪素组成。低毒磷石膏基高强人造骨料制备工艺简单易行,采用本发明制备出的骨料的颗粒粒度为5-25mm,压碎指标满足建筑用碎石标准,可以广泛应用于C30～C60等级混凝土、公路路基材料,成球后的磷石膏基高强人造骨料性能好、毒性低。(The invention provides a preparation method of low-toxicity phosphogypsum-based high-strength artificial aggregate, which comprises the following raw materials in percentage by dry weight: ardealite, slag powder, cement kiln dust and a modifier. The modifier consists of calcium chloride, sodium lignosulphonate, bentonite, carbide slag powder and casein. The preparation process of the low-toxicity phosphogypsum-based high-strength artificial aggregate is simple and easy to implement, the particle size of the aggregate prepared by the method is 5-25mm, the crushing index meets the broken stone standard for buildings, the aggregate can be widely applied to C30-C60 grade concrete and highway subgrade materials, and the pelletized phosphogypsum-based high-strength artificial aggregate has good performance and low toxicity.)

1. The low-toxicity phosphogypsum-based high-strength artificial aggregate is characterized by comprising the following raw materials in percentage by weight: 80-90% of phosphogypsum, 5-10% of slag powder, 3-9% of cement kiln dust and 1-2% of modifier.

2. The low-toxicity phosphogypsum-based high-strength artificial aggregate according to claim 1, which is characterized in that: the mass fraction of each raw material in the mixture is as follows: 80% of phosphogypsum, 10% of slag powder, 9% of cement kiln dust and 1% of modifier.

3. The low-toxicity phosphogypsum-based high-strength artificial aggregate according to claim 1, which is characterized in that: the mass fraction of each raw material in the mixture is as follows: 83% of phosphogypsum, 9% of slag powder, 7% of cement kiln dust and 1% of modifier.

4. The low-toxicity phosphogypsum-based high-strength artificial aggregate according to claim 1, which is characterized in that: the mass fraction of each raw material in the mixture is as follows: 85% of phosphogypsum, 8% of slag powder, 5% of cement kiln dust and 2% of modifier.

5. The low-toxicity phosphogypsum-based high-strength artificial aggregate according to the claims 2-4, is characterized in that: the mass fraction of each raw material in the mixture is as follows: 90% of phosphogypsum, 5% of slag powder, 3% of cement kiln dust and 2% of modifier.

6. The low toxicity phosphogypsum-based high purity according to any of claims 1-5The strong artificial aggregate is characterized in that: the content of free phosphorus in the phosphogypsum is less than or equal to 6.0mg/L, the content of free fluoride ions is less than or equal to 350mg/L, and the screening passing rate is that the particle size of 50 percent is less than 50 um; the specific surface area of the slag is more than or equal to 700 m²The grain diameter is less than 15 um, wherein the screening passing rate is 50%; the specific surface area of the cement kiln ash is more than or equal to 330m²The grain diameter is less than 35um, wherein the screening passing rate is 50%.

7. The low-toxicity phosphogypsum-based high-strength artificial aggregate according to any one of claims 1 to 6, which is characterized in that: the modifier is prepared by mixing 25-35% of calcium chloride, 18-25% of sodium lignosulphonate, 15-25% of bentonite, 18-27% of carbide slag powder and 5-15% of casein by mass percent through ultrasonic emulsification, drying and grinding at the temperature of 50-60 ℃.

8. The low-toxicity phosphogypsum-based high-strength artificial aggregate according to claim 7, which is characterized in that: the modifier is prepared by mixing 30% of calcium chloride, 22% of sodium lignosulphonate, 18% of bentonite, 21% of carbide slag powder and 9% of casein by mass through ultrasonic emulsification, drying and grinding at the temperature of 60 ℃.

9. The preparation method of the low-toxicity phosphogypsum-based high-strength artificial aggregate according to any one of claims 1 to 8, is characterized in that: the method comprises the following steps:

(1) adding the slag powder and cement kiln dust into a stirrer, uniformly mixing for 30-40 s, then adding a modifier, mixing and stirring for 25-30 s;

(2) the feeding angle of the granulator is set to be 44-51 degrees, phosphogypsum is firstly added into the granulator and rotates for 5-10 seconds, then the mixture of the slag powder and the cement kiln dust and a modifier are added into the granulator for granulation, and water is added in the granulation process, wherein the water accounts for 18-23 percent of the total amount of the dry raw materials;

(3) unloading the aggregate granulated in the T2, wherein the unloading angle of the granulator is set to 68-80 degrees;

(4) and (3) carrying out moisture preservation and maintenance on the discharged aggregate for 48-72 h, and controlling the relative humidity of a maintenance room to be more than 90%.

Technical Field

The invention relates to a preparation method of low-toxicity phosphogypsum-based high-strength artificial aggregate, belonging to the field of engineering materials and preparation.

Background

The phosphogypsum is industrial waste residue discharged in the process of producing phosphoric acid by a wet process by taking phosphorite as a raw material, and is a byproduct in the production of the phosphoric acid by the wet process. The main chemical component of the phosphogypsum is dihydrate gypsum which also contains a small amount of soluble phosphorus, soluble fluorine and other impurities, and the stockpiling can cause environmental pollution to water and soil. At present, the historical phosphogypsum stockpiling quantity in China exceeds 5 hundred million tons, the annual new production is about 7000 tons, and the comprehensive utilization rate is less than 40 percent. The phosphogypsum-based artificial aggregate prepared from the phosphogypsum is a novel method for comprehensively utilizing the phosphogypsum, the pelletized artificial aggregate can be widely applied to products such as highway subgrade materials, C30-C60 grade concrete and the like, and the existing preparation method of the phosphogypsum-based artificial aggregate cannot consider the crushing index and toxicity of finished products and cannot meet the market demand.

Disclosure of Invention

The invention aims to fully utilize the characteristics of particle composition and potential activity of the phosphogypsum, activate and modify the phosphogypsum by adopting slag, cement, a modifier and the like, passivate the activity of toxic substances in the phosphogypsum, reduce the leaching rate of the toxic substances and promote the formation of a gelling system structure by using a core component in the modifier. The phosphogypsum-based artificial aggregate which can be widely applied to C30-C60-grade coagulation and has low toxicity and good performance is prepared by the processes of modification, granulation, maintenance, crushing test and the like.

The present invention thus achieves the above objects:

the low-toxicity phosphogypsum-based high-strength artificial aggregate comprises the following raw materials in percentage by dry weight: 80-90% of undisturbed phosphogypsum, 5-10% of slag, 3-9% of cement kiln dust, 1-2% of modifier and 18-23% of water in the total amount of dry solids.

The phosphogypsum is the undisturbed phosphogypsum accumulated in a tailing pond, the content of free phosphorus is less than or equal to 6.0mg/L, the content of free fluoride ions is less than or equal to 350mg/L, and the particle size with the sieving passing rate of 50 percent is less than 50 um.

The specific surface area of the slag is more than or equal to 700 m²The grain diameter is less than 15 um, wherein the screening passing rate is 50%. The specific surface area of the cement kiln ash is more than or equal to 330m²The grain diameter is less than 35um, wherein the screening passing rate is 50%. The modifier comprises 25-35% of calcium chloride, 18-25% of sodium lignosulfonate, 15-25% of bentonite, 18-27% of carbide slag powder and 5-15% of casein by massIs prepared by drying and grinding at the temperature of 60 ℃ after ultrasonic emulsification and mixing.

The modifier is prepared by mixing 30% of calcium chloride, 22% of sodium lignosulphonate, 18% of bentonite, 21% of carbide slag powder and 9% of casein by mass percent through ultrasonic emulsification, drying and grinding at the temperature of 60 ℃.

The main component dihydrate gypsum crystal in the phosphogypsum is dissolved in water to cause local supersaturation and separate out crystal, the separated crystal is further dissolved to form circulation, and simultaneously, the crystal continuously grows and grows to form a cementing body with certain strength. The cement kiln dust provides an alkaline environment required by hydration for the slag besides self hydration, the slag can generate a substance with hydraulicity under the condition of an alkaline activator, the phosphogypsum, the slag and the cement kiln dust can form a ball core with hydraulicity in granulation under the condition of a proper amount of water, the modifier can accelerate the formation of the ball core, calcium chloride, bentonite, talcum powder and the like in the modifier can adsorb and fix the original phosphogypsum containing a small amount of harmful substances such as acid, phosphorus and the like, the ball core mutually rubs under the combined action of centrifugal force, friction force and gravity to scratch the surface coating layer of the active substance so as to expose the gelled active substance, the surface of the particle is increasingly rough, and in addition, the temperature rise generated by the friction action also promotes the active reaction to carry out. The superposition of the functions and the reaction gelation of the gelation active substance improve the compactness and the strength of the mixture and reduce the leaching of harmful substances.

The invention has the advantages that: (1) the preparation process of the low-toxicity phosphogypsum-based high-strength artificial aggregate is simple and feasible, energy-saving and environment-friendly and is easy to popularize; (2) the low-toxicity phosphogypsum-based high-strength artificial aggregate has better performance and low toxicity; (3) the utilization rate of the phosphogypsum is high.

Detailed Description