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Study on Improving the Performance of Phosphogypsum and Application

Author: DuYong
Tutor: ChenMingFeng
School: Chongqing University
Course: Materials Science and Engineering
Keywords: Phosphogypsum Admixtures Hydration process Modified Phosphogypsum -based materials
CLC: TQ177.3
Type: Master's thesis
Year: 2010
Downloads: 336
Quote: 0
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Abstract

Phosphogypsum waste, emissions of phosphorus chemical enterprises phosphogypsum production is also rising sharply, with the rapid development of phosphorus chemical enterprises, the annual emissions far has reached nearly 50 million tons, has brought great pressure to the social environment, The phosphogypsum resource utilization imminent. Β-hemihydrate gypsum is the main component of the building phosphogypsum dehydration the phosphogypsum and products is an effective way of resource utilization, and at the same time to achieve the purpose of consume large amounts of phosphogypsum waste residue. But the the phosphogypsum performance unstable, resulting in such broad sources, building function excellent resources can not be effectively utilized. The preprocessing and admixtures modified guarantee hardened body building phosphogypsum stable performance and high strength. However, due to the lack of understanding of the particularity of phosphogypsum, often blind to the use of natural gypsum admixtures, admixtures poor adaptability, inefficient use of, phosphogypsum grade is low and other factors greatly restricted the development of the application of phosphogypsum-based materials. This article from phosphogypsum quality cut, admixtures and architectural adaptability of phosphogypsum, conditions of use, ash and phosphogypsum performance, relationship, and admixtures of admixture hydration process with hardened body microstructure, morphology conducted a systematic study and other content, clear the use of phosphogypsum admixture type and scope, to reveal the inherent relationship between the phenomenon and essence of the role of admixtures, to guide people to a more reasonable and scientific use of phosphogypsum admixtures improve building performance. Recognize the building phosphogypsum modified regular basis, further preparation the phosphogypsum base powder materials. The main factors of the performance of the phosphogypsum to identify methods to improve the the building the phosphogypsum performance, grade. By studying the different types of retarders of setting time and hardening of the building phosphogypsum strength, find a for phosphogypsum system retarder, to determine the optimal pH range retarder. And phosphorus gypsum hydration process of building retarder in its optimum pH environment research. Through of phosphorous gypsum crystals scanning electron micrograph of the observation, analysis retarder phosphogypsum hardening microtopography change their strength intrinsically linked. Clear latex powder and superplasticizer building phosphogypsum strength suitable for of Phosphogypsum the latex powder and superplasticizer type and dosage. , Water resistance and water performance testing judge silicone water repellent and hydroxypropyl methylcellulose the phosphogypsum performance improvement. Mastered the admixture of the phosphogypsum modified regular basis, through the admixture composite, the optimization of the particle size distribution of gypsum powder and filler added, using the principle of efficacy coefficient developed phosphorus gypsum-based stucco, bonded and putty material . The results show that: the optimum pH value, the retarder admixture reduces the over-saturation of the liquid phase of the phosphogypsum, so that the crystalline particles becomes large, crystal decrease in indirect contact loose crystalline structure network, resulting in intensity declined; 1220 redispersible latex powder and modified polycarboxylate ether superplasticizer can effectively improve the the hardening strength; 100,000 viscosity hydroxypropyl methyl cellulose can significantly improve the water retention properties of phosphogypsum slurry; mixing silicone water repellent the phosphogypsum water greatly improve performance; performance of the the phosphogypsum base function mortar mixed with citric acid. The analysts believe that the same grade of phosphogypsum, retarder is a key factor in resource utilization of phosphogypsum, which affect the dissolution of gypsum crystals, nucleation and growth process, in the nature of to affect the phosphogypsum base material performance level. Superplasticizer redispersible latex powder plays a dense hardened and reduce porosity, in dispersible polymer powders the phosphogypsum the base stucco, bonding and bond strength of putty material can also improve performance on the the phosphogypsum base material improvement plays an important role, while the rest of the admixture only play a supporting modified role.

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