Study On Preparation And Properties Of Phosphogypsum Based Sound Absorption Material

Phosphogypsum is solid sediment during the method of wet process of phosphoric acid.In general,per ton of P₂O₅ is produced and there will be 4.5-5.5 tons phosphogypsum.The data concerned shows that the quantity of phosphogypsum increases by seventy million tons a year and the cumulative volume has reached 300million tons,but now utilization ratio is about 20%.As a result,phosphogypsum has already occupied a lot of land,which will cause soil pollution,vegetation pollution,air pollution and water pollution,harm the surrounding ecological environment and hinder the healthy development of phosphorus chemical industry and building materials industry in our country.The exploitation and utilization of phosphogypsum has become a worldwide problem.At present,most phosphogypsum is used to produce low value-added building material products.However,using phosphogypsum to make functional materials is less.In order to extend the way of phosphogypsum utilization and improve the added value of building material products,making functional gypsum products will be the development direction in the future.The study is about how to make functional product,which is sound absorption material,by using calcined gypsum.The main research work is as follows.Firstly,this paper explores the influence rule of the retarder and thickening agent on the properties of calcined gypsum and explains the mechanism of modification.Secondly,this paper explores the effect of different pore-forming agent on the pore structure and finds the suitable dosage range.Thirdly,this paper explores the influence factors of acoustical absorption coefficient and mechanical strength,which include the fiber length and fiber content,water gypsum ratio,dosage of expanded perlite and pore-forming agent dosage.Two kinds of products are made successfully.One is pore-forming agent and fiber sound absorption material,the other is pore-forming agent-fibre-expanded perlite sound absorption material.Finally,this paper explores many effects on the influence law of sound absorption performance,like the thickness,surface structure,density,porosity and humidity etc.These research results make a preparation for further research on phosphogypsum based sound absorption material and provide a reference value.Phosphogypsum-Based Sound Absorbption Material,here it is called PBSA for short.The main results are as follows:1.NS,NP and SC three retarders have some retarding effect on calcined gypsum,but the effect is different.The best retarder is the SC.When its content is 0.1%,the setting time is about 50 min.Thickening agent HPMC can improve the viscosity of the gypsum slurry and its suitable content is 0.1%.2.Pore forming agent can significantly improve the pore structure of the gypsum hardening body.The result shows that AE-200 has a better effect and its suitable content is 0.6%.Fiber length,fiber content and water gypsum ratio have an influence on pore-forming agent and fiber sound absorption material.When fiber content of3mm length is 1%,AE-200 content is 0.6%and water gypsum ratio is 0.7,the material has the best performance and average absorption coefficient is 0.47.Expanded perlite dosage,water gypsum ratio and pore forming dosage have an influence on pore-forming agent-fibre-expanded perlite sound absorption material.When fiber content of 3mm length is 1%,AE-200 content is 0.6%,water gypsum ratio is 0.7 and expanded perlite dosage is 4%,the material has the best performance and average absorption coefficient is 0.55.3.There are many factors that can influence the sound-absorption property of PBSA,which include thickness,surface structure,density,porosity and humidity etc,but the effect is different.Of all the factors,density and porosity have an approximate linear relationship in connection with the average sound absorption coefficient of PBSA.According to the theory of the law of approximate linear relationship,the sound absorption coefficient of the material can be calculated.The theory of linear rule can be used to guide the preparation of PBSA material,whose sound absorption coefficient is in the range of 0.2 to 0.8.