Mazlumoglu, Hayrunnisa; Gulaboglu, M. Sahin

The employment of Mazidagi phosphate ore for wet flue gas desulphurization was investigated. The ore was exposed to sulfation processes in a three-phase double-stirred reactor to determine the effects of certain parameters on SO2 absorption. The absorption rate significantly increased with inlet SO2 concentration, gas flow rate, stirring speeds, and solid concentration but not with temperature. The absorption rate increases as the mass transfer coefficients and interface area value increase with stirring speeds. These parameters have also a prominent impact on the absorption rate depending on the dissolution rate of CaCO3. Based on these, the most effective parameters on SO2 absorption are liquid-phase stirring speed and suspension concentration, and the process is diffusion-controlled in the liquid phase. In addition, optimum conditions were determined, and then the ore was exposed to sulfation processes via a semi-batch operation mode. A comparison between raw and sulfated ore was examined for the changes in physical structure and chemical composition. Although the ratios of fluorapatite and carbonate-fluorapatite remained nearly constant, the ratio of calcite decreased significantly. It was determined from these investigations that the calcite in the phosphate ore has been converted into the CaSO3∙½H2O compound. Consequently, both the calcite in the phosphate ore was utilized effectively for wet flue gas desulphurization, and a phosphate-rich industrial product was obtained.

Keleş Güner, Eda; Akkaş, Rukiye; Özer, Abdulkadir

In the present study, zinc sulfate hydroxide trihydrate was synthesized for the first time by the chemical precipitation method using zinc sulfate as the precursor, borax as the basic precipitating agent, and zwitterionic N-Dodecyl-N,N-dimethylammonio-3-propane sulfonate as a surfactant. The results of X-Ray Diffraction demonstrate that the product obtained by chemical precipitation at 60 °C was triclinic zinc sulfate hydroxide trihydrate. Examination of the morphology using Scanning Electron Microscope revealed a hexagonal layered structure. The thermal decomposition of zinc sulfate hydroxide trihydrate was investigated in the range of 25–1000 °C. Thermogravimetry/Differential Thermal Analysis curves show that zinc sulfate hydroxide trihydrate had three-region decomposition following thermal treatment. The synthesized samples were annealed at 200 °C, 600 °C, and 1000 °C to determine the chemical composition of the products. X-Ray Diffraction shows that it consisted of zinc sulfate hydroxide hemihydrate at 200 °C, zinc oxysulfate and zinc oxide at 600 °C, and zinc oxide at 1000 °C. The mineralogical, structural and optical properties of zinc oxide were subsequently obtained by annealing at 1000 °C. Scanning Electron Microscope images of zinc oxide demonstrate that the hexagonal structure deteriorated through sintering. The average particle size of ZnO was found as 753.4 nm, According to the X-Ray Diffraction, X-Ray Photoelectron Spectroscopy, and Raman spectroscopy results, zinc oxide was formed in the single-phase wurtzite and showed only the peaks corresponding to oxygen and zinc, indicating the purity of the product. The band gap for zinc oxide calculated from the Ultra Viyolet-visible results was 3.22 eV.