Factors affecting bioleaching in the processing of non-metallics

Biotechnological treatment of non-metallics is based on bacterial leaching of raw material and dissolution of Fe. Bacterial iron dissolution ability is dependent on various physicochemical factors as temperature, acidity of solutions, redox potential, rapidity of water circulation and presence of organic sources. The Fe content in the quartz sands and feldspar samples by the biological leaching decreased as much as 60% and by subsequent using of electromagnetic separation of feldspars, the decrease of Fe content in 74% was achieved. However, the application of magnetic separation of quartz sands after bioleaching resulted in total iron removal of 93% and in such combined way prepared product contained 0.024 % of Fe2O3. Achieved results on iron removal point to the fact that combination of leaching and magnetic separation enables to obtain product usable in glass and ceramic industry.

Atmospheric organic complexation enhanced sulfate formation and iron dissolution on nano α-Fe2O3

The iron–dicarboxylate complexation significantly increased the SO2 heterogeneous conversion on nano α-Fe2O3 and ATD under light irradiation, owing to the generation of strong reactive oxygen species.

Tetracycline Removal by Activating Persulfate with Diatomite Loading of Fe and Ce

Persulfate (PS)-based oxidation technology is efficient in removing refractory organics from water. A novel diatomite (DIA) support Fe and Ce composite (Fe-Ce/DIA) was prepared for activating persulfate to degrade tetracycline in water. The Fe and Ce were uniformly loaded on DIA, and the total pore size of Fe-Ce/DIA was 6.99 × 10−2 cm3/g, and the average pore size was 12.06 nm. Fe-Ce/DIA presented a good catalytic activity and 80% tetracycline was removed under the persulfate system. The Fe-Ce/DIA also had photocatalytic activity, and the corresponding tetracycline removal efficiency was 86% under UV irradiation. Fe-Ce/DIA exhibited less iron dissolution rate compared with Fe-DIA. The tetracycline degradation rate was enhanced when the temperature increased. The optimal tetracycline removal efficiency was obtained when the conditions were of persulfate 10 mM, Fe-Ce/DIA dosage 0.02 g/L, and tetracycline concentration 50 mg/L. In addition, Fe-Ce/DIA showed a wide pH application and good reusability and stability.

Effects of alkali solution on the dissolution kinetics and optimization processes of iron from Akwuke ore

Background The dissolution process kinetics and optimization of iron from Akwuke ore were investigated in this study. The effects of process parameters such as agitation rate and ore particle size on the dissolution process were also examined. The Akwuke ore was characterized employing the XRD, FT-IR, SEM, and UV-spectroscopy. Results The results from the rate constants indicated that the diffusion through the boundary layer process with R2 > 0.96 was the rate-determining mechanism. The maximum iron dissolution rate of 83.2% was obtained at 45-μm particle size while 81.2% and 72.6% iron dissolution rates were obtained at 490 and 390 rpm agitation rates, respectively. Silicon oxide, aluminum oxide, and iron oxide were present in Akwuke ore as indicated from the XRD analysis. The RSM predicted optimum value of the iron dissolution rate from the numerical optimization was experimentally validated to confirm the satisfactory performance of the quadratic model. Conclusion This study concludes and presents the potential extraction of iron from Akwuke ore, which will be of immense benefit in hydrometallurgical process.

Iron Control in Atmospheric Acid Laterite Leaching

Iron control in the atmospheric acid leaching (AL) of nickel laterite was evaluated in this study. The aim was to decrease acid consumption and iron dissolution by iron precipitation during nickel leaching. The combined acid leaching and iron precipitation process involves direct acid leaching of the limonite type of laterite followed by a simultaneous iron precipitation and nickel leaching step. Iron precipitation as jarosite is carried out by using nickel containing silicate laterite for neutralization. Acid is generated in the jarosite precipitation reaction, and it dissolves nickel and other metals like magnesium from the silicate laterite. Leaching tests were carried out using three laterite samples from the Agios Ioannis, Evia Island, and Kastoria mines in Greece. Relatively low acid consumption was achieved during the combined precipitation and acid leaching tests. The acid consumption was approximately 0.4 kg acid per kg laterite, whereas the acid consumption in direct acid leaching of the same laterite samples was approximately 0.6–0.8 kg acid per kg laterite. Iron dissolution was only 1.5–3% during the combined precipitation and acid leaching tests, whereas in direct acid leaching it was 15–30% with the Agios Ioannis and Evia Island samples and 80% with the Kastoria sample.