Study On Preparation Of Inorganic Macromolecular Polysilicate Iron Flocculant From Yellow Phosphorus Slag

Yellow phosphorus slag is a rich source of SiO2and CaO, and can be used as a secondary resources for the production of silicon、 calcium products. This paper studied preparation of the high performance polysilicate flocculant by decomposing yellow phosphorus slag with acid solution, dissolving, aggregation and activation of polysilicic acid, and then compositing or graftting cationic poly metal source to control products performance. Then by means of appling in Dianchi Lake pollution water treatment, the paper studies coagulation performance of polysilicate flocculant so as to reasonable utilization of yellow phosphorus slag.Firstly, the paper studied the key factors of influencing preparation of Polysilicic Acid、Polysilicate Aluminum、Polysilicic Ferric and Polysilicate Aluminum Ferric coagulant by introducting Al3+and Fe3+two kinds of metal ions with the yellow phosphorus slag as raw materials. By means of treating Dianchi pollution water with coagulant prepared, the paper researched removal efficiency of turbidity, COD, total phosphorus and total nitrogen in Dianchi Lake pollution water. The results showed that: four kinds of flocculants for Dianchi Lake pollution water has a different flocculation and turbidity achieved better effect. The Polysilicate Aluminum flocculant prepared by introducting Al3+in Polysilicic Acid solution was beneficial to the improvement of the total nitrogen removal rate. The Polysilicic Ferric prepared by introducting Fe3+in Polysilicic Acid solution help improve COD removal rate. The composite Polysilicate Aluminum Ferric prepared by introducting Al3+, Fe3+was beneficial to the improvement of the removal rate of COD and total phosphorus increased rate is lower. The comprehensive performance of Polysilicate Aluminum Ferric was greater than Polysilicic Acid、Polysilicate Aluminum and Polysilicic Ferric. The optimum process conditions of manufacturing Polysilicate Aluminum Ferric are that yellow phosphorus slag20g,(Al+Fe)/Si mole ratio of1:1, Al/Fe molar ratio of1.5:1, polymerization temperature55℃, polymerization time of80min, ageing temperature55℃, ageing time2h. Under this condition. The appearance of polysilicate aluminum ferric prepared is yellowish and transparent sticky liquid. the turbidity, COD, total nitrogen removal rate respectively reached98.93%,85.50%,45.47%, and total phosphorus increased rate of65.36%. Secondly, the paper studied effect factors of treating Dianchi Lake pollution water with Polysilicate Aluminum Ferric and determined the best water treatment conditions and process parameters. The optimum flocculation conditions were Polysilicate Aluminum Ferric addition of6mg/L, Dianchi Lake water pollution pH value is5, sedimentation temperature at room temperature (about22℃), settling time of50min. Under these conditions, the turbidity, COD, total nitrogen removal rate reached98.52%,87.05%,98.52%respectively, total phosphorus increased rate of64.60%. To analyze the structural characteristics of Polysilicate Aluminum Ferric by infrared spectrum, scanning electron microscopy, grading analysis, specific surface area analysis, and pH and conductivity tests and other analytical tools showed that Polysilicate Aluminum Ferric is not a simple raw material distribution, but in copolymerization form complexing generated aluminum iron silicon polymer, and also has a strong abilities of neutralizing electric, adsorption and bridging role.To prapere polysilicate aluminum ferric products with high efficiency, non-toxic, good flocculation effect of colloidal particles in the field of water treatment and of good application prospect with the valuable elements Si contained in the yellow phosphorus slag not only is an effective way to make use of solid yellow phosphorus slag contaminants, reduce the pollution of the environment, but also can reduce the production cost of poly aluminum silicate iron flocculant, save resources, waste treatment and to achieve aim of maximizing the utilization of resources and industrial applications, therefore, have a very important theoretical significance and application value.