Effect Of Nanomaterials On Physical Properties Of Phosphorous Building Gypsum

Phosphogypsum is a solid waste produced by the extraction of phosphoric acid with sulfuric acid decomposing phosphate ore during the production of wet-process phosphoric acid.It has large stockpiles and emissions,and has serious environmental pollution.At the same time,phosphogypsum is a renewable gypsum resource.Solving the problem of comprehensive utilization of phosphogypsum can not only improve the environmental pollution caused by the large amount of phosphogypsum storage,but also have a positive impact on the sustainable development of phosphate chemical enterprises.Using phosphogypsum to produce phosphogypsum gypsum,and then preparing various phosphogypsum gypsum products,is an effective way to consume phosphogypsum in large quantities,but the biggest problem limiting this approach is that the performance of phosphogypsum gypsum is poor,the strength is unstable,and it is difficult to achieve actuality.Requirements for use.Nano-materials as an additive can significantly improve the performance of building materials.In this paper,three materials,namely nano-SiO₂,nano-CaCO₃ and calcium sulfate whiskers,were studied.The fluidity,setting time,absolute dry flexural strength,and absolute compressive strength of phosphorous building gypsum under different dosages and dispersion methods were studied.The effects of water absorption and softening coefficient were analyzed microscopically by XRD and SEM.The effects of different materials were compared and the mechanism was analyzed.Based on this,nano-SiO₂ and calcium sulfate whiskers were selected for further blending experiments.The effects of compounded nanomaterials on the properties of phosphorous building gypsum were studied.And got the following main conclusions:(1)Nanomaterials have a significant impact on the physical properties of phosphorous building gypsum pulp:With the continuous increase of the amount of nano-SiO₂ and calcium sulfate whiskers,the mobility of the phosphorous building gypsum pulp has decreased significantly,and the setting time of the pulp has been continuously shortened;nano CaCO₃ The effect on the fluidity and setting time of phosphate building gypsum slurry is relatively small.(2)Nanomaterials have a significant impact on the mechanical strength of phosphorus building gypsum:For nano-SiO₂,when its content is 1%,the absolute dry flexural strength and the dry compressive strength of phosphorus building gypsum reach the highest,and wet blending and dispersion The effect of the method is better than that of the wet blending dispersion method.For nano-CaCO₃,when its content is 1%,the dry flexural strength of phosphorous building gypsum increases the most.For calcium sulfate whiskers,in the dry blending dispersion method,When the amount is 3.5%,the absolute dry flexural strength of phosphorous building gypsum reaches the highest,and when its content reaches 3%,the absolute dry compressive strength of phosphorous building gypsum reaches the highest.(3)Nanomaterials have a significant impact on the water absorption and softening coefficient of phosphorous building gypsum:For nanometer SiO₂ and calcium sulfate whiskers,the influence of the wet-dispersed dispersion mode is greater than that of the dry-dispersed dispersion mode within a certain amount range.The content of nano-SiO₂ and calcium sulfate whiskers is increased,and the effects of dry and wet dispersion are basically the same.For nano-CaCO₃,when the content exceeds 1.5%,the water absorption and softening coefficient of phosphorus building gypsum tend to be stable.(4)Although the doped nano-SiO₂ and calcium sulfate whiskers in phosphorous architectural gypsum have improved the performance of phosphorous architectural gypsum,the improvement effect is not ideal,and the effect is slightly worse than that of mono-doped nano-SiO₂ and mono-doped calcium sulfate whiskers.(5)Nanomaterials can fill the micropores in phosphorous building gypsum,thereby improving the pore structure inside the material,making the structure of phosphorous building gypsum more compact,and improving its various properties.However,when the amount of nano-materials is too high,agglomeration is easy to occur,stress concentration occurs,and the dry flexural strength and dry compressive strength of phosphorus building gypsum will adversely affect it.