Research On The Application Of Phosphorus-containing Solid Waste In Cement And Building Materials

Phosphorus-containing solid waste is difficult to apply because of the presence of phosphorus.This paper will purify the two most common phosphorus-containing solid wastes and discuss their application research.The main contents of this article are as follows:In this paper,ammonia water was used to purify the phosphorus-containing aluminum slag(PAS)produced by the phosphating treatment,and the PAS samples were treated with different concentrations of ammonia water to obtain the PAS samples after treatment with different concentrations.The SEM-EDS and XRD analysis showed that the ammonia water was effective It is effective to remove impurities in PAS.10% ammonia water can reduce the aluminum phosphate of PAS to a very low level.Further increasing the concentration will not reduce the phosphorus content.Untreated PAS can cause serious delays in cement hydration.The heat of hydration is mainly manifested as the exothermic peak of tricalcium aluminate is delayed and the exothermic peak of tricalcium silicate is greatly reduced and hydrated.The heat release time is extended wirelessly.In the hydration product,it shows low ettringite content,gypsum residue and less calcium hydroxide,and its strength is lower than the national standard.After 10% ammonia treatment,the hydration delay improved and the intensity returned to normal.The impurities in the PAS after ammonia water treatment are removed,which is completely suitable for the cement industry.In this paper,oxalic acid is used to treat phosphogypsum(PG).Oxalic acid not only removes soluble impurities and insoluble impurities,but also achieves the purpose of removing intercrystalline impurities by destroying part of the gypsum crystals.Through XRD,thermogravimetry,SEM-EDS and infrared,it was determined that 3%oxalic acid treatment caused too much gypsum to be reacted.The amount of impurities treated with 2% oxalic acid was about the same as 1%,but 2% oxalic acid would react to excess PG,And finally determined that the best concentration is 1% oxalic acid.Through XPS and full analysis data,it is determined that 1% oxalic acid has well removed impurities and phosphorus impurities and meets the requirements of national standards.The cement made of treated PG has reached the national standard in terms of setting time and strength.In this paper,PG is used to prepare high-volume PG autoclaved aerated concrete(AAC).Through XRD,thermogravimetric and SEM analysis,the main hydration products of unautoclaved PG AAC are ettringite,C-S-H and hydroxide.calcium.Through the foaming time-volume diagram and the corresponding XRD pattern,it is explored that although a large amount of PG causes a delay in hydration and a lag in the formation of the strength phase,it prevents the dissolution of lime and reacts with aluminum powder to reduce the amount and amount of foaming agent.Increase the viscosity and other means to reduce the rate of foaming,so that the rate of foaming matches the speed of matrix hardening,while the slow foaming environment makes the sample pore distribution uniform and the matrix structure optimized.The formation of grass-like tobermorite and S-tobermorite after autoclave provides a guarantee for the strength and thermal conductivity.The formation of the reticulated toble mullite structure promotes the continuity of the matrix.The final compressive strength exceeds the B07 national standard 1.6MPa and meets the requirements of industrial applications.Figure [30] Table [8] Reference [93]...