| In order to realize the energy conservation and pollutant emissions reduction, our country is energetically developing the circulating fluidized bed technology. Circulating fluidized bed coal combustion(CFBC) fly ash were collected from the flue after circulating fluidized bed coal combustion boiler., which has a great annual emissions each year. This paper intends to study the basic physicochemical properties of CFBC fly ash from Neijiang city in Sichuan province and Bijie city in Guizhou province, and then recycle useful components for its properties, which mainly including recycling iron, modifying CFBC fly ash to improve the adsorption performance and magnetic zeolite synthesized, etc.The research showed that the main component of CFBC fly ash was Si O2, Al2O3 and Fe2O3, which component comprised from 70% to 80%. Also the mineral composition was mainly quartz, anhydrite and hematite. Furthermore, the surface of CFBCfly ash was rough loose, porous.Recovery of iron from CFBC fly ash study has shown that roasting temperature, time, dosage of reductant and the magnetic field intensity has a great influence on the magnetization roasting- magnetic separation process. Results showed that iron with content grade of 51.62% and recovery rate of 86.41% could be obtained under the experimental conditions:- 800℃ of roasting temperature,90 min of roasting time,5% of reducing agent dosage,200 k A/m of magnetic field intensity of cleaning.At last, we could get iron concentrate with 58.02% of grade and 76.27% of recovery rate by a weak magnetic field strength of 80 Ka/m magnetic separation. XRD showed that the main mineral phase of iron concentrate was magnetite.Research of CFBC fly ash modification showed that solid-liquid ratio, modifier concentration, reaction time and water bath temperature had a greater influence on the process parameters on the adsorption performance. When using the mass concentration of 10% sodium carbonate and modifying 2 h under 80 ℃, more holes were formed on particle surface in SEM image. Zeta potential measurement showed that the potential of modified ash was more negative than that of original ash, with stronger electrostatic attraction of the existence of metal cation. At this time, the removal rate of heavy metal ions Pb2+, Cu2+ is maximum and is 95.94% and 91.35% respectively. Compared to the original CFBC fl y ash, the removal rate was increased by 20%~30%.With CFBC fly ash and Na OH as raw materials only, adding no silicon aluminum source, the main magnetic zeolite of sodalite could be made. Alkalinity, crystallization temperature and time had effect on the crystallization of zeolite, embodied in the higher alkalinity, the higher crystallization temperature, the longer, the more conducive to the crystallization of sodalite molding. Higher crystallinity conditions were alkalinity of 2.78mol/L, crystallization temperature of 125 ℃ for 24 h. At this time, saturated exchange adsorption of Pb2+ was 97.87mg/g. Magnetic analysis showed that the synthesis of molecular sieves with certain magnetism, the saturation magnetization Ms=2.00782 emu/g, remanent magnetization Mr=0.48 emu/g, coercive force Hc = 138.2 Oe. In addition, its magnetic separation effect was remarkable. |
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