Chemical Preparation Of Phosphogypsum Gypsum Cementitious Materials And Applications

Phosphogypsum,main content CaSO₄.2H₂O,is a by-product of phosphate fertilizer production,about 5 tons of which out of evey 1 ton of phosphoric acid production.Currently there are more than 150 million tons of phosphogypsum output every year worldwide,around 40 million tons in our country ranking in the third place in the world.Multiple uses applied to it though,the actual effects are not so satisfactory that large quantity of phosphogypsum are still not used,causing great pressure to enterprises' production.To research and find a new way of phosphogypsum using,this study puts forward making self-leveling materials of floor using phospogypsum as raw material, by pretreating the phosphogypsum and grinding and aging theβsemi-hydrate phosphogypsum for which the influence to the physical performance of phosphogypsum is judged herewith.Analysis is also done on action of additives toβsemi-hydrate phosphogypsum modification,the performances of compound cementing materials withβsemi-hydrate phosphogypsum as basic content and impact of different cementing materials and their different proportion ratios to the performance of the compound cementing materials.In consideration of great difference between the properties of phosphogypsum and those of natural gypsum,in this article a series of experiments have been done with several kinds of additives, such as retarder,reinforcing agent and water reducing agent,the additive and amount being found for effective modification ofβsemi-hydrate phosphogypsum.The cementing material suitable for phosphogypsum based self-leveling material of floor and its best proportioning are achieved through the different cementing materials and different admixture amount with their influence to the performances of the compound cementing materials.Self-leveling materials of floor are newly developed and growing.Research and study on making gypsum based self-leveling materials using phosphogypsum instead of natural gypsum is still vacant in our country.Exploring on this subject,a brand new comprehensive use of phosphogypsum will be developed,meaningful for phosphogypsum application conversion and strategic and prospective for saving natural gypsum resources.