Study On Improving The Performance Of Phosphogypsum And Application

Phosphogypsum is the emission of waste chemical enterprises of phosphorus , the production of phosphogypsum is also rising sharply with the rapid development of phosphorus chemical industry, it has reached the standard of annual emissions of nearly 50 million tons at present , which take to the social environment of the enormous pressure, so P Utilization of gypsum is pressing. An effective method to solve this problem is dehydration toβ-semihydrated gypsum as the main ingredient and production, at the same time achieving the purpose of consuming the waste of phosphogypsum. its unstable performance of the existing impurities in phosphogypsum, so the source of phosphogypsum of vast and building capabilities is difficult to effectively use.The methods of pretreatment and adding agent can produce phosphogypsum with stable performance and sufficient strength.However,because of lose of the special recognization of phosphogypsum,admixture is used blindly, leading to bad compatibility between admixture and phosphogypsum and to Inefficient using.As a result,those factors including the lower grade of phosphogypsum is key that the application and development of phosphogypsum-based materials suffer from greatly restricted.In this study,the grade of phosphogypsum as the starting point of the application of admixture in phosphogypsum,relative research such as the compatibility between additive and phosphogypsum, the conditions of using additives, the relationship between additive content and the performance of phosphogypsum, the relationship between admixture dosage and performance of phosphogypsum, and the influence of admixiture on hydration ratio and crystal morphology and structure of dihydrate is systemically analyzed.The results reveal that the effect of law of admixture.The suitable retarders and the best pH value range are found and the influence of retarders under optimal pH value on the hydration process of phosphogypsum are investigated.Scanning electron microscope are used to analyze the internal relation between structure and strength of hydrated phosphogypsum.It is clear that the category and added of Vinnaps and water reducer for phosphogypsum by studying its effect on the strength of phosphogypsum. silicone waterproofing agent and hydroxypropyl methyl cellulose are evaluation of improving the performance of phosphogypsum by determining waterproof and water-keeping of phosphogypsum .The efficiency coefficient theory is used to exploit the produce of paint, adhesive and putty material of phosphogypsum-based on improving research .The results showed that: the addition of retarder reduces liquid supersaturation of phosphogypsum on the best pH value, leading to crystal grains become larger, the less of touchpoint of crystal, the net-structureing of crystal become loose and resulting in decreased strength;1220 redispersible powder and modified polycarboxylic ether of water-reducing can improve the strength of hardening;hydroxypropyl methyl cellulose of 100 000 viscosity can significantly improve water-keeping properties of the plaster of phosphogypsum;mixing with silicone waterproofing agent can greatly improved water resistance; phosphogypsum-based mortar will possess excellent features if mixed with citric acid.Analysis,utilization of retarder is a key factor which affects the dissolution of gypsum crystals, nucleation and growth process under the same conditions of grade of phosphogypsum, impacting the properties of phosphogypsum-based materials on natural dimensions as well. Water-reducer and dispersible polymer powders play the roles of compacting and reducing the porosity of hardened. Dispersible polymer powders can also improve paint, adhesive and putty materials of the phosphogypsum-based on the adhesive properties of phosphogypsum as well as plays an important role in the improvement, while the remaining additive effects only play a supporting modification.