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Mechanism and kinetics of iron extraction from high silica boehmite−kaolinite bauxite by hydrochloric acid leaching

Transactions of Nonferrous Metals Society of China 2021年第10期31卷 3128-3149页

作者： Dmitry VALEEV Denis PANKRATOV Andrei SHOPPERT Artem SOKOLOV Alexandr KASIKOV alexandra mikhailova Cristian SALAZAR-CONCHA Ilia RODIONOV Laboratory of Sorption Methods Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences119334 MoscowRussia Department of Chemistry Lomonosov Moscow State University119991 MoscowRussia Department of Non-ferrous Metals Metallurgy Ural Federal University620002 YekaterinburgRussia Tananaev Institute of Chemistry Kola Science Centre of the Russian Academy of Sciences184209 ApatityRussia Laboratory of Crystal Structure Studies A.A.Baikov Institute of Metallurgy and Materials ScienceRussian Academy of Sciences119334 MoscowRussia Universidad Austral de Chile ValdiviaChile Graphite Innovation and Technologies Dartmouth NSCanada

The chemical and mineral compositions of bauxite recovered from the Severoonezhsk Bauxite Mine(Arkhangelsk region,Russia)were studied by XRD,ICP-OES,TG/DSC,SEM,TEM,and Mössbauer *** iron-containing minerals of the bauxites were found to comprise alumogoethite(α-Fe_(1−x)Al_(x)OOH),alumohematite(α-(Fe_(1−x)Al_(x))_(2)O_(3)),alumoakaganeite(β-Fe_(1−x)Al_(x)O(OH,Cl)),and chromite(FeCr_(2)O_(4)).The efficiency of Fe extraction from the bauxite by HCl leaching was 82.5%at 100℃,HCl concentration of 10%,solid/liquid ratio of 1:10,and the process duration of 60 min,with aluminum loss from the bauxites below 4.5%of the total Al contents in the *** of the kinetics of the iron leaching process proved diffusion to be the limiting stage of the process at 90−100℃.Bauxite residue after leaching presented traces of α-Fe_(1−x)Al_(x)OOH and β-Fe_(1−x)Al_(x)O(OH,Cl),and most of the iron content was in the FeCr_(2)O_(4).In bauxite residue after HCl leaching,in addition to iron oxide,the contents of chromium and calcium oxides significantly *** iron chloride liquor after leaching contained the rare earth elements(REE)of 6.8 mg/L Sc,4.1 mg/L Ce and 2.3 mg/L Ga.

关键词： bauxite acid leaching iron extraction kinetics Mössbauer spectroscopy

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Low level of activin A secreted by fibroblast feeder cells accelerates early stage differentiation of retinal pigment epithelial cells from human pluripotent stem cells

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Stem Cell Discovery 2012年第4期2卷 176-186页

作者： Heidi Hongisto alexandra mikhailova Hanna Hiidenmaa Tanja Ilmarinen Heli Skottman Institute of Biomedical Technology University of Tampere Tampere Finland

Human pluripotent stem cells (hPSC) differentiated to retinal pigment epithelial cells (RPE) provide a promising tool for cell replacement therapies of retinal degenerative diseases. The in vitro differentiation of hPSC-RPE is still poorly understood and current differentiation protocols rely on spontaneous differentiation on fibroblast feeder cells or as floating cell aggregates in suspension. The fibroblast feeder cells may have an inductive effect on the hPSC-RPE differentiation, providing variable signals mimicking the extraocular mesenchyme that directs the differentiation in vivo. The effect of the commonly used fibroblast feeder cells on the hPSCRPE differentiation was studied by comparing suspension differentiation in standard RPEbasic (no bFGF) medium to RPEbasic medium conditioned with mouse embryonic (mEF-CM) and human foreskin (hFF-CM) fibroblast feeder cells. The fibroblast secreted factors were found to enhance early hPSC-RPE differentiation. The onset of pigmentation was faster in the conditioned media (CM) compared to RPEbasic for both human embryonic (hESC) and induced pluripotent (iPSC) stem cells, with the first pigments appearing around two weeks of differentiation. After four weeks of differentiation, CM conditions consistently contained higher number of pigmented cell aggregates. The ratio of PAX6 and MITF positive cells was quantified to be clearly higher in the CM conditions, with mEFCM containing most positive cells. The mEF cells were found to secrete low levels of activin A growth factor that is known to regulate eye field differentiation. As RPEbasic was supplemented with corresponding, low level (10 ng/ml) of recombinant human activin A, a clear increase in the hPSC-RPE differentiation was achieved. Thus, inductive effect provided by feeder cells was at least partially driven by activin A and could be substituted with a low level of recombinant growth factor in contrasts to previously reported much higher concentrations.

关键词： Retinal Pigment Epithelial Cell Human Pluripotent Stem Cell Conditioned Medium Human Foreskin Fibroblast Mouse Embryonic Fibroblast Activin A Cell Differentiation

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