High Fe2O3 Content Research Articles

Initial stage of deposit formation process in a coal fired grate-rotary kiln for iron ore pellet production

Serious deposits in the grate-kiln plant for iron ore pellet production can decline pellets quality and reduce production efficiency. The initial stage of deposit formation is crucial for adhesion and growth of deposit on refractories in the kiln. In this study, the simulated experiments of FeO formation indicated that the high FeO content decreased with increasing the roasting time. The effects of combustion efficiency of pulverized coal and Na2O amount on the adhesion on the refractory bricks were experimentally studied using an evaluated method. The results showed that the adhesion on the refractory bricks increased with decreasing the combustion efficiency of pulverized coal and increasing the Na2O content in the deposits. Finally, the mechanism of deposit formation mainly on the center-entrance area in the kiln was summarized as follows: the pulverized pellet powder and coal ash with unburnt carbon fell into the pores and cracks of the refractory bricks in the kiln. The unburnt carbon and alkali metal chemically reacted with the pellet powder and contributed to the formation of low-melting-point phases (fayalite, silicate), then the generated low melting point phases plus the chemical reactions between the deposits and refractory bricks caused the adhesion of deposits on the refractory bricks. The deposits grew and became thicker as the continuous effects of the above process.

Subducted slab-plume interaction traced by magnesium isotopes in the northern margin of the Tarim Large Igneous Province

Incorporation of subducted slabs may account for the geochemical and isotopic variations of large igneous provinces (LIPs). However, the mechanism and process by which subducted slabs are involved into magmas is still highly debated. Here, we report a set of high resolution Mg isotopes for a suite of alkaline and Fe-rich rocks (including basalts, mafic–ultramafic layered intrusions, diabase dykes and mantle xenoliths in the kimberlitic rocks) from Tarim Large Igneous Province (TLIP). We observed that δ26Mg values of basalts range from −0.29 to −0.45‰, −0.31 to −0.42‰ for mafic–ultramafic layered intrusions, −0.28 to −0.31‰ for diabase dykes and −0.29 to −0.44‰ for pyroxenite xenoliths from the kimberlitic rocks, typically lighter than the normal mantle source (−0.25‰±0.04, 2 SD). After carefully precluding other possibilities, we propose that the light Mg isotopic compositions and high FeO contents should be ascribed to the involvement of recycled sedimentary carbonate rocks and pyroxenite/eclogite. Moreover, from basalts, through layered intrusions to diabase dykes, (87Sr/86Sr)i values and δ18OV-SMOW declined, whereas ε(Nd)t and δ26Mg values increased with progressive partial melting of mantle, indicating that components of carbonate rock and pyroxenite/eclogite in the mantle sources were waning over time. In combination with the previous reported Mg isotopes for carbonatite, nephelinite and kimberlitic rocks in TLIP, two distinct mantle domains are recognized for this province: 1) a lithospheric mantle source for basalts and mafic–ultramafic layered intrusions which were modified by calcite/dolomite and eclogite-derived high-Si melts, as evidenced by enriched Sr–Nd–O and light Mg isotopic compositions; 2) a plume source for carbonatite, nephelinite and kimberlitic rocks which were related to magnesite or periclase/perovskite involvement as reflected by depleted Sr–Nd–O and extremely light Mg isotopes. Ultimately, our study suggests that subducted slabs could make important contributions to LIP generation, and establishes a potential linkage between plate tectonics and mantle plume.

Enrichment of Bi-Be-Mo-Cd-Pb-Nb-Ga, REEs and Y in the Permian coals of the Huainan Coalfield, Anhui, China

This paper presents new data concerning the geochemistry and distribution of the Bi-Be-Mo-Cd-Pb-Nb-Ga, and REY in the Panyi, Xieqiao, Xinji, Zhuji, and Zhuji Xi coals of the Huainan Coalfield. The results indicate that the Huainan bituminous coals were characterized by medium ash yields and low to medium sulfur contents. The mineral assemblage present in the Huainan coals is mainly made up of quartz, kaolinite, pyrite, and calcite. The minerals, ash yield, sulfur contents, volatile matter contents, Sr/Ba, SiO2/Al2O3, and (CaO + MgO + Fe2O3)/(SiO2 + Al2O3) ratio varied significantly in the Huainan Coalfield, which are attributed mainly to vertical variation in the depositional environment. These coals contain high contents of Ga, Nb, Mo, Be, Pb, Ba, SiO2, Fe2O3, TiO2, CaO, Na2O, Al2O3, MnO, K2O, and MgO, especially in the marine-influenced environment coals. The average contents of Ga, Nb, Mo, Be, and REY are higher than those of world-wide bituminous coals, thus a hidden treasure is a yet to-be-realized new economic potential. The Bi, Be, Mo, Nb, Ga, and REY have mixed organic-inorganic affinity, while Cd and Pb mainly have an organic affinity in the Huainan coals. Compared to the average Chinese coals, the REY are enriched in the Panyi, Xieqiao, and Xinji coals, slightly lower in the Zhuji coals and depleted in the Zhuji Xi coals. Compared to the upper continental crust, REY in the Huainan coal samples has medium-REY and light-REY enrichment. The average concentration of oxides (ash basis) of the rare earth elements and Y in the Panyi (on average 1120.3 μg/g), Xieqiao (1287.7 μg/g), Xinji (1148.7 μg/g), and Zhuji (1025.1 μg/g) coals are higher than the cut-off grade for industrial deposits of these elements and thus, the Huainan coals are considered as raw materials for the recovery of rare earth elements.

Synergy effects of combined red muds as oxygen carriers for chemical looping combustion of methane

Iron-containing natural ores or solid wastes (e.g., red mud) are considered as ideal candidate as oxygen carrier for large-scale chemical looping combustion technology due to their high content of Fe2O3 and low cost. However, these oxygen carriers usually show low activity for fuel conversion because of the special structure and components. In the present study, two types of red mud (V-RM with rich Fe2O3 and W-RM with rich inert and alkaline components) were combined to modify the structure and the distribution of different components in the red mud oxygen carrier for the chemical looping combustion of methane. The synergy effects of the active ingredient (i.e., Fe2O3) in the Fe2O3-rich red mud (V-RM) and the inert/alkaline components (i.e., Al2O3, CaO and Na2O) in the W-RM strongly improved the activity and stability of the oxygen carrier. Among the different samples, the W7V3 shows the best property for methane conversion (the average CH4 conversion and CO2 selectivity were 81% and 89%, respectively). In the multiple redox testing, the CH4 conversion decreases in the first ten cycles but the CO2 selectivity maintains at a high level (ca. 90%). The associated reduction kinetics parameters were also estimated based on isothermal thermogravimetric analysis (TGA) in a reducing atmosphere of methane. It was observed that the reduction of Fe2O3 in the red mud was a two-steps process. The reduction mechanism for the first stage reaction (i.e., Fe2O3 to Fe3O4) can be described by the two-dimensional growth of nuclei model A2. The activation energy of V-RM, W3V7, W5V5, W7V3 and W-RM oxygen carriers are 95.9, 93.5, 85.2, 77.5 and 84.2 kJ/mol, respectively.

Some carbonate rocks utilized as a building material rocks, Egypt

Studies of the geochemical, mineralogical, petrographical characteristics and the physicochemical properties were carried out on some carbonate rocks, so as to throw light on the possibility of utilizing them as a building stones. The dolomitic and dolostone rocks of Gebel Ataqa and Giran El-Ful quarries have been acquiring potential application in building and industry. Petrographically, the dolomite rocks of the Gebel Ataqa quarries are characterized by dolo-biomicrosparite and dolomitic limestone microfacies for Hassan Alaam quarry and dolosparite microfacies for Arab Contractors quarry, while those of Giran El-Ful (Abu Roash area) are mainly dolo-biomicite microfacies and dolostones. They are deposited in mixing zone environment. Mineralogically, XRD patterns indicate the dolomites of the Ataqa and Giran El-Ful quarries are non-stoichiometric. XRD with DTA revealed that the rocks of the three quarries are consisting mainly of dolomite (Ataqa quarries), calcite and ankarite (Abo Roash quarry), as the main constituents, besides quartz and halite as minor constituents. Geochemically, the normative dolomite contents in the studied rocks with an average ~ 90, ~ 35, and ~ 31% for Arab Contractors, Hassan Alaam and Giran El-Ful quarries; respectively. Thus, the dolomitization was more effective in the Cretaceous carbonates at Arab Contractors quarry than those in the Middle Eocene in Hassan Alaam and Giran El-Ful quarries. Arab Contractors have very high Mg content followed by Hassan Alaam, though impoverished in Na2O, K2O, Al2O3, Fe2O3, SO3, SiO2, TiO2, and Cl. Giran El-Ful quarry has very high Fe2O3 and MgO contents; on the other hand, poor in Na2O, K2O, Al2O3, SO3, SiO2, TiO2, and Cl. Sr contents indicate that the dolomite crystals were deposited in mixing zone environments. The total radioactivity measurements are ranging from 2 to 8 ppm for U and from 3 to 9 ppm for Th. The radioactivity measurements are approximately against to the background level of carbonates, and they are in the permissible limits for carbonates used in cement industries and as building stones. The dolomitic and dolostone rocks of the three quarries are proved chemically suitable for the industries relevant to crushed aggregates and lime production. Physically–mechanically examination revealed that the youngest carbonate deposits in the Middle Eocene (Hassan Alaam quarry) rocks have relatively low porosity, water absorption, and crushability, and highest compressive strength compared with those carbonate rocks of the two other quarries of Upper Cretaceous (Arab Contractors and Giran El-Ful). The petrographical, geochemical, and physical–mechanical observations recommended that the carbonates rocks of Hassan Alaam and Arab Contractors quarries in Gebel Ataqa area clearly can be used in the production of crushed aggregates to utilize in the concrete works. On the other hand, Giran El-Ful quarry can be used only in the mechanical sawing and in the production of limestone blocks.

The Eocene corundum-bearing rocks in the Gangdese arc, south Tibet: Implications for tectonic evolution of the Himalayan orogen

The genesis of Liangguo corundum deposit in the southern Gangdese magmatic arc, east-central Himalaya, remains unknown. The present study shows that the corundum-bearing rocks occur as lenses with variable sizes in the Eocene gabbro that intruded into marble. These corundum-bearing rocks have highly variable mineral assemblage and mode. The corundum-rich rocks are characterized by containing abundant corundum, and minor spinel, ilmenite and magnetite, whereas the corundum-poor and corundum-free rocks have variable contents of spinel, plagioclase, sillimanite, cordierite, ilmenite and magnetite. The host gabbro shows variable degrees of hydration and carbonization. The corundum grains are mostly black, and rarely blue, and have minor FeO and TiO2. The spinel is hercynite, with high FeO and low MgO contents. The corundum-bearing rocks have variable but high Al2O3, FeO and TiO2, and low SiO2 contents. Inherited magmatic and altered zircons of the corundum-bearing rocks have similar U–Pb ages (∼47 Ma) to the magmatic zircons of the host gabbro, indicating corundum-bearing rock formation immediately after the gabbro intrusion. We considered that emplacement of gabbro induced the contact metamorphism of the country-rock marble and the formation of silica-poor fluid. The channeled infiltration of generated fluid in turn resulted in the hydrothermal metasomatism of the gabbro, which characterized by considerable loss of Si from the gabbro and strong residual enrichment of Al. The metasomatic alteration probably formed under P–T conditions of ∼2.2–2.8 kbar and ∼650–700 °C. We speculate that SiO2, CaO and Na2O were mobile, and Al2O3, FeO, TiO2 and high field strength elements remained immobile during the metasomatic process of the gabbro. The Liangguo corundum deposit, together with metamorphic corundum deposits in Central and Southeast Asia, were related to the Cenozoic Himalayan orogeny, and therefore are plate tectonic indicators.

Co-reduction of Copper Smelting Slag and Nickel Laterite to Prepare Fe-Ni-Cu Alloy for Weathering Steel

In this study, a new technique was proposed for the economical and environmentally friendly recovery of valuable metals from copper smelting slag while simultaneously upgrading nickel laterite through a co-reduction followed by wet magnetic separation process. Copper slag with a high FeO content can decrease the liquidus temperature of the SiO2-Al2O3-CaO-MgO system and facilitate formation of liquid phase in a co-reduction process with nickel laterite, which is beneficial for metallic particle growth. As a result, the recovery of Ni, Cu, and Fe was notably increased. A crude Fe-Ni-Cu alloy with 2.5% Ni, 1.1% Cu, and 87.9% Fe was produced, which can replace part of scrap steel, electrolytic copper, and nickel as the burden in the production of weathering steel by an electric arc furnace. The study further found that an appropriate proportion of copper slag and nickel laterite in the mixture is essential to enhance the reduction, acquire appropriate amounts of the liquid phase, and improve the growth of the metallic alloy grains. As a result, the liberation of alloy particles in the grinding process was effectively promoted and the metal recovery was increased significantly in the subsequent magnetic separation process.

Carbon Sequestration Potential Promoted by Oxalate Extractable Iron Oxides through Organic Fertilization

Core Ideas Organic fertilization increased the oxalate extractable iron oxides. Oxalate extractable iron oxides contributed to soil organic carbon sequestration. Soil organic carbon from 20 to 40 cm was more labile than that from 0 to 20 cm. Oxalate extractable iron oxides preferentially preserved aromatic compounds. Carbon sequestration in paddy soils through organic fertilization is of great importance for soil quality improvement in subtropical Asia. This study explored the effect of oxalate extractable iron oxides (Feo) on soil organic carbon (SOC) sequestration in response to different fertilization treatments. Soil samples were collected from 0‐ to 10‐cm, 10‐ to 20‐cm, and 20‐ to 40‐cm depth intervals in June 2016 after a wheat (Triticum aestivum L.) harvest. This study involved five treatments: control with no fertilizer (CK), chemical fertilizer (NPK), 50% chemical fertilizer plus manure (NPKM), 100% chemical fertilizer plus straw (NPKS), and 30% chemical fertilizer plus manure organic‐inorganic compound fertilizer (NPKMOI). Organic fertilization significantly (P < 0.05) increased the SOC content and the Feo concentration compared with chemical fertilization alone. The specific C mineralization rate (SCMR, rate per unit SOC) increased with increasing soil depths, suggesting that SOC at the 20‐ to 40‐cm depth was more labile than that from 0 to 20 cm. The percentage of SOC present as microbial biomass carbon (MBC) was significantly (P < 0.001) positively correlated with SCMR, indicating that soil microorganisms influenced the potential SOC mineralization. Furthermore, the alternation of drying and wetting in paddy soils drives the biogeochemical cycles of iron and SOC, during which organic fertilization promotes the accumulation of Feo possibly by forming organo‐iron complexes as indicated by the higher Feo content in NPKM than in NPK. The Feo was significantly (P < 0.001) positively correlated with SOC and the percentage of aromatic C, indicating that Feo may play an important role in preserving SOC, especially the aromatic compounds. Therefore, the enhancement of Feo by organic fertilization, especially organic manure that is enriched in aromatic compounds, improved the SOC sequestration potential in the rice (Oryza sativa)–wheat rotation system.

Geochemical systematics of the Mauranipur-Babina greenstone belt, Bundelkhand Craton, Central India: Insights on Neoarchean mantle plume-arc accretion and crustal evolution

The Neoarchean Bundelkhand greenstone sequences at Mauranipur and Babina areas within the Bundelkhand Gneissic Complex preserve a variety of magmatic rocks such as komatiitic basalts, basalts, felsic volcanic rocks and high-Mg andesites belonging to the Baragaon, Raspahari and Koti Formations. The intrusive and extrusive komatiitic basalts are characterized by low SiO2 (39–53 wt.%), high MgO (18–25 wt.%), moderately high Fe2O3 (7.1–11.6 wt.%), Al2O3 (4.5–12.0 wt.%), and TiO2 (0.4–1.23 wt.%) with super to subchondritic (Gd/Yb)N ratios indicating garnet control on the melts. The intrusive komatiitic suite of Ti-enriched and Al-depleted type possesses predominant negative Eu and positive Nb, Ti and Y anomalies. The chemical composition of basalts classifies them into three types with varying SiO2, TiO2, MgO, Fe2O3, Al2O3 and CaO. At similar SiO2 content of type I and III basalts, the type II basalts show slightly high Al2O3 and Fe2O3 contents. Significant negative anomalies of Nb, Zr, Hf and Ti, slightly enriched LREE with relatively flat HREE and low ∑REE contents are observed in type I and II basalts. Type III basalts show high Zr/Nb ratios (9.8–10.4), TiO2 (1.97–2.04 wt.%), but possess strikingly flat Zr, Hf, Y and Yb and are uncontaminated. Andesites from Agar and Koti have high SiO2 (55–64 wt.%), moderate TiO2 (0.4–0.7 wt.%), slightly low Al2O3 (7–11.9 wt.%), medium to high MgO (3–8 wt.%) and CaO contents (10–17 wt.%). Anomalously high Cr, Co and Ni contents are observed in the Koti rhyolites. Tholeiitic to calc alkaline affinity of mafic-felsic volcanic rocks and basalt–andesite–dacite–rhyolite differentiation indicate a mature arc and thickened crust during the advanced stage of the evolution of Neoarchean Bundelkhand greenstone belt in a convergent tectonic setting where the melts were derived from partial melting of thick basaltic crust metamorphosed to amphibolite-eclogite facies. The trace element systematics suggest the presence of arc-back arc association with varying magnitudes of crust-mantle interaction. La/Sm, La/Ta, Nb/Th, high MgO contents (>20 wt.%), CaO/Al2O3 and (Gd/Yb)N > 1 along with the positive Nb anomalies of the komatiite basalts reflect a mantle plume source for their origin contaminated by subduction-metasomatized mantle lithosphere. The overall geochemical signatures of the ultramafic-mafic and felsic volcanic rocks endorse the Neoarchean plume-arc accretion tectonics in the Bundelkhand greenstone belt.

Petrogenesis, detrital zircon SHRIMP U-Pb geochronology, and tectonic implications of the Upper Paleoproterozoic Seosan iron formation, western Gyeonggi Massif, Korea

This study involves investigations on the Upper Paleoproterozoic iron formation (viz., Seosan iron formation) from the Seosan Group, Gyeonggi Massif of the southwestern Korean Peninsula. It occurs as thin banded layers within meta-arkosic sandstone, formed by alternating processes of chemical (hydrothermal) and detrital depositions under a shallow marine environment. It mainly consists of alternating layers of iron oxides, mostly hematite, and quartz. Minor amounts of magnetite surrounded by muscovite, clinopyroxene and amphibole indicate hydrothermal alteration since its formation. Meta-arkosic sandstone is composed of recrystallized or porphyroclastic quartz and microcline, with small amounts of hematite and pyrite clusters. The Seosan iron formation has high contents of total Fe2O3 and SiO2 with positive Eu anomalies similar to those of other Precambrian banded iron formations, and its formation is clearly related to hydrothermal alteration since its deposition. Detrital zircon SHRIMP U-Pb geochronology data from a meta-arkosic sandstone (SN-1) and an iron formation (SN-2) show mainly two age groups of ca. 2.5 Ga and ca. 1.9–1.75 Ga. This together with intrusion age of the granite gneiss (ca. 1.70–1.65 Ga) clearly indicate that the iron formations were deposited during the Upper Paleoproterozoic. The dominant Paleoproterozoic detrital zircon bimodal age peaks preserved in the Seosan iron formation compare well with those from the South China Craton sedimentary basins, reflecting global tectonic events related to the Columbia supercontinent in East Asia.

Oxidation of molten impurities in converters by means of combustion flames: Thermodynamic principles. 2. Interaction of flame with metal and slag in converter bath

Thermodynamic analysis is applied to the physicochemical processes in the converter bath when intensifying bath heating by means of gas–oxygen burners. In the converter’s working space, when the combustion flames interact with the liquid bath, the oxygen and natural gas supplied through the burners and the oxygen supplied through the tuyere interact in a bubbling slag–metal emulsion. As a result, iron and the impurities are oxidized. The use of such burners changes the gas composition: not only O2, CO, and CO2 are present, but also H2 and H2O, which changes the oxidative capacity of the gas phase. The presence of solid carbon (for example, pulverized coal) in the burner flame may be used to control and intensify the combustion process. Combustion is most effective in the oxidation of carbon to CO when the oxygen excess is less than 1.0. The oxidation conditions of carbon in the melt change with variation in its activity as a function of its concentration and the temperature. The equilibrium in the M–O–C system may be described by the oxygen partial pressure $${P_{{O_2}}}$$ , which may be regarded as a universal characteristic. In addition, the equilibrium may be assessed on the basis of the associated ratios $${P_{CO}}/{P_{C{O_2}}}$$ and $${P_{{H_2}}}/{P_{{H_2}O}}$$ It is found that iron may be oxidized by oxygen and, to some extent, by carbon dioxide. At 1600–2000 K, there is practically no oxidation of iron by steam. The carbon dissolved in the steel is oxidized relatively effectively by oxygen and carbon dioxide until its concentration is less than 0.1% C. Steam oxidizes carbon very poorly and is not much more effective with manganese and silicon. With increase in temperature, the rate at which carbon dissolved in steel is oxidized by oxygen increases, while the oxidation rate of manganese and silicon falls. Above 1800 K, superoxidized slag with a high FeO content actively oxidizes silicon (to <2% Si), manganese (to <1% Mn), and carbon (to <1.5% C).

Hydrothermal indications of Early Cretaceous red beds in lacustrine successions, North Yellow Sea Basin, eastern China

Controversies over the origin of globally distributed Cretaceous red beds have mainly focused on climate vs. weathering with potential hydrothermal influence. In comparison to Cretaceous Oceanic Red Beds, Cretaceous lacustrine red beds exhibit chronological inconsistencies and their diverse tectonic settings suggest differing genetic mechanisms. In this paper, Early Cretaceous red beds in the North Yellow Sea Basin, one of Mesozoic rift basins in eastern China that are associated with multi-phase magmatic activities, was chosen to document potential hydrothermal impact. Geological and geochemical analyses show that these red beds were syndepositional products developed in shallow to moderately deep lacustrine environments and that they were influenced by hydrothermal activity. Major and trace elements, including enhanced Al2O3-normalized Fe2O3 and Fe2O3 (total) values, Al/(Al + Fe + Mn) and (Fe + Mn)/Ti ratios, Ni-Co-Zn and Fe-Mn-(Ni + Co + Cu)*10, ∑REE-La/Yb, the concentrations of hydrothermally-related ions, invalid redox indicators of trace elements, abnormally high Fe2O3 (total) content, positive Eu anomaly, correlation of Fe2O3 (total) and Eu anomaly, and vitrinite reflectance (Ro) vs. total organic carbon (TOC), all show strong hydrothermal fluid influence and heating effects. By integrating and comparing data from previous studies, we propose a hydrothermally affected sedimentation model for Cretaceous red beds and associated sediments in magma-activated lacustrine basins, and conclude that the enriched metallic ions introduced by the hydrothermal fluids may be the most significant reason for the deposition of the red beds, and the flushed ferric ions, accompanied by hydrothermal fluid, are the main ions that are hosted inside hematite causing the red sediment. This model can be applied to similar lacustrine basins that experience strong magmatic activity.

Mineralogical and geochemical characteristics of coal ash from the Northwest Thrace region, Turkey: a case study

The first combined mineralogical and geochemical investigation of coal ashes from the Northwest Thrace Coal Basin, Turkey, was performed as a case study. The coal ash samples were obtained at 525 °C (group I), 750 °C (group II), and 1000 °C (group III) ashing temperatures from coal samples from the basin and were studied in terms of their mineralogical and geochemical composition using XRD and ICP-MS methods. The determination of the mineralogical composition was done for all of the groups; the geochemical analysis was carried out only for group II. In accordance with the high SiO2, Fe2O3, CaO, and SO3 content of the ash, quartz (SiO2), hematite (Fe2O3), and anhydrite (CaSO4) are the major crystalline phases for all of the ash groups. The other minerals are muscovite, thenardite, tridymite, calcite, wollastonite, anorthite, cristobalite, gibbsite, ternesite, mullite, nahcolite, and nacrite. High-temperature phases such as mullite, wollastonite, and anorthite were observed at 750 and 1000 °C. According to the (Fe2O3 + CaO + MgO+ K2O+ Na2O)/(SiO2 + Al2O3+ TiO2) ratios varying from 0.19 to 5.65, the ashes are highly prone to slagging. Compared to average values of low-rank coal ashes, the contents of V, Cr, Co, Ni, Zn, As, Rb, Sr, Mo, Cs, W, and U of the ash are higher, whereas the total content of rare earth elements (REEs) (Σ 163.7 ppm) are lower. Based on upper continental crust normalization, As, Se, Th, and U are enriched in all of the samples. The higher trace element contents in the ashes might be considered as a possible health hazard. The correlation analyses indicated that Ca is associated with anhydrite and As with hematite. The correlation analyses also showed that newly formed Al and Ca silicates may contain the elements such as Ti, K, Na, Cr, Sn, and Pb.

Geochemical and zircon U-Pb and Lu-Hf isotopic constraints on the origin of supracrustal rocks from the mid-Qilian terrane: A comparison between supracrustal rocks on the two sides of the eastern segment of the Altyn Tagh Fault

Comparisons between the tectonic units on two sides of the sinistral ENE-striking Altyn Tagh Fault (ATF) are important tracers to find out the corresponding relationships among different terranes. This study focuses on the tectonic units along the eastern segment of the ATF. The Paleoproterozoic Beidahe Group in the mid-Qilian terrane, south side of the eastern segment of the ATF, is mainly composed of metasedimentary rocks and amphibolites. These rocks are petrologically and mineralogically similar to those from the Dunhuang Group, north side of the eastern segment of the ATF. The detrital zircon U-Pb ages indicate that the protolith sediments of the Beidahe metasedimentary rocks were mainly sourced from a provenance dominated by magmatic rocks in ages of 2.85–2.55Ga, 1.70–1.55Ga and 1.42–1.03Ga. This sedimentary sequence was deposited no earlier than 1.03Ga as passive continental margin deposits. Geochemical and zircon U-Pb and Lu-Hf isotopic data suggest that the Neoarchean-Mesoproterozoic basement rocks from the Tarim Craton most likely provide the majority of source materials for their protolith. Amphibolites from the Beidahe Group have high total Fe2O3 and Al2O3 contents but low Mg# values, indicating a high degree of compositional evolution and contamination of the older crust. They have flat REE patterns but positive LILE and negative Nb-Ta and Ti anomalies, suggesting a back-arc basin basalts (BABBs) affinity for their protolith. The amphibolites have a crystallization age of 1.61Ga and zircon εHf(t) values ranging from −7.7 to +10.6. The zircon εHf(t) values and whole-rock εNd(t) values indicate an involvement of juvenile and pre-existing old materials in the formation of their parental magmas. Comparisons between the Beidahe and Dunhuang Groups indicate that the metasedimentary rocks from these two groups are both sourced from the Tarim Craton but have different depositional ages, and that the amphibolites have similar crystallization ages but different tectonic settings for their source rocks. The field relationships and geochemical and geochronological characteristics of the metasedimentary rocks and amphibolites from the Beidahe Group support the interpretation that the observed recent proximity of these two rock complexes might be the result of tectonic juxtaposition rather than a primary intrusive contact.

Magmatic graphite inclusions in Mn-Fe-rich fluorapatite of perphosphorus granites (the Belvís pluton, Variscan Iberian Belt)

Three Mn-Fe-rich fluorapatite types have been found in the highly evolved peraluminous and perphosphorous granites of the Belvis pluton. One of these apatite types includes abundant graphite microinclusions, suggestive of a magmatic origin for the graphite. The Belvis pluton is a reversely zoned massif composed by four highly fractionated granite units, showing a varied accessory phosphate phases: U-rich monazite, U-rich xenotime, U-rich fluorapatite, and late eosphorite-childrenite. The strong peraluminous character of the granites determines an earlier monazite and xenotime crystallization, so the three types of fluorapatite record late stages of phosphate crystallization. The earlier type 1 apatite is mostly euhedral, small and clear; type 2 apatite is dusty, large (<2800 μm) and mostly anhedral, with strong interlobates interfaces with the main granite minerals, more abundant in the less fractionated units and absent in the most evolved unit; type 3 is subeuhedral to anhedral, shows feathery aggregate texture, and only appears in the most evolved unit. Apatite composition was acquired by electron microprobe analyses, laser ablation inductively coupled plasma-mass spectrometry and electron energy loss spectroscopy. Type 1 and type 2 apatite display similar broad compositional ranges showing high MnO (up to 4.30 wt%) and FeO (up to 2.88 wt%) contents, without traces of carbon in apatite structure. Type 2 differs from type 1 by having slightly higher LREE and Sr contents. REE spectra also differ, with type 1 displaying both variable LREE slope and negative Eu anomaly, whereas type 2 shows constant LREE slope and higher negative Eu anomaly, although both display similar HREE slope. Type 3 apatite displays higher FeO contents (up to 5.09 wt%), positively correlated with higher Cl-Na-Li-Be-B-Zn contents and extremely low Y-REE contents when compared to the other apatite types. Cation substitution indicates that part of the Fe content is as Fe³⁺. Graphite has been found exclusively as abundant microinclusions in type 2 apatite, parallel or randomly distributed, and heterogeneously grouped in clusters within the crystals. High-resolution electronic images show that graphite occurs with unusual habits: filaments of stacked hexagonal flakes up to 15 μm length and up to 0.5 μm width. Textural and chemical features suggest a highly crystallized melt, which favor compartmentalizing in compositional microdomains where the apatite types would have crystallized. The cocrystallization of type 2 apatite and graphite suggests a C-F-P-rich melt, sufficiently saturated to acquire an immiscible character with the highly evolved silicate melt in late-magmatic stages. As type 2 differs from type 1 apatite by higher LREE and Sr contents, we interpret that fluxing components were favorably concentrated in those residual less-depleted LREE-Sr fraction melts, once monazite and zircon (and xenotime) would have crystallized. Type 3 apatite records a change in the ultimate melt stage: an increase of the oxygen fugacity coupled with high undercooling by volatile lost of highly fractionated residual Cl-richer melts. The presence of biogenic carbon in granite peraluminous melts derived from metasedimentary sources and its later crystallization as graphite filaments opens a discussion on the carbon behavior during magma evolution, especially in highly polymerized melt framework.

Chalcophile elements in Martian meteorites indicate low sulfur content in the Martian interior and a volatile element-depleted late veneer

It is generally believed that the Martian mantle and core are rich in sulfur and that shergottites originated from sulfide-saturated magma. However, recent work suggests that the high FeO contents would require very high S concentrations in shergottite parent magmas at sulfide saturation. Here we combine new and published data on chalcophile elements in shergottites, nakhlites and ALH84001 to constrain the sulfide saturation state of the parent magmas and the chalcophile element concentrations in their mantle sources.Regardless of the MgO content and the long-term depletion history of incompatible lithophile elements as indicated by initial ε143Nd, different groups of shergottites display limited variations in ratios of Pt, Pd, Re, Cu, S, Se and Te. The emplacement of most shergottites within the crust and limited variations of ratios of chalcophile elements with substantial differences in volatility during eruption (e.g., Cu/S, Cu/Se and Pt/Re) indicate little degassing losses of S, Se, Te and Re from shergottites. Limited variations in ratios of elements with very different sulfide–silicate melt partition coefficients and negative correlations of chalcophile elements with MgO require a sulfide-undersaturated evolution of the parent magmas from mantle source to emplacement in the crust, consistent with the FeO-based argument. Sulfide petrography and the komatiite-like fractionation of platinum group elements (PGE) in shergottites also support this conclusion. The absence of accumulated sulfides in the ancient Martian cumulate ALH84001 results in very low contents of PGE, Re, Cu, Se and Te in this meteorite, hinting that sulfide-undersaturated magmas may have occurred throughout the Martian geological history. The negative correlation of Cu and MgO contents in shergottites suggests approximately 2±0.4(1s) μg/g Cu in the Martian mantle. The ratios of Cu, S, Se and Te indicate 360±120 μg/g (1s) S, 100±27 ng/g (1s) Se and 0.50±0.25 ng/g (1s) Te in the Martian mantle. At such low S concentrations, all S in Martian mantle sources may dissolve in basaltic melts that form at >5 % partial melting.Assuming equilibrium metal–silicate partitioning, and provided that the compositional model of the Martian mantle based on SNC meteorites is correct, Martian mantle inventories of Cu, S and Se were mostly established by core formation and the Martian core should contain <5–10 wt.% S only (depending on the choice of metal–silicate partition coefficients). The low S content in the Martian interior is consistent with the low Zn content in the Martian mantle, which indicates about 5 wt.% S in the core. In contrast, the highly siderophile PGE, Re and Te were added to the mantle by late accreted material after the Martian core formed. The near chondritic PGE ratios and the very low ratio of volatile Te to refractory PGE reflect a strongly volatile element-depleted late veneer and imply that the delivery of Martian water, presumably from carbonaceous chondrite like materials, must have occurred before accretion of the late veneer, likely within 2–3 million years after formation of the solar system.

Fe2O3 nanocomposite PVC membrane with enhanced properties and separation performance

Organic and inorganic mixed matrix membranes are one of the most promising new membrane materials for ultrafiltration (UF) separation applications. In this study, PVC/Fe2O3-mixed UF membranes were fabricated at different nano-Fe2O3 loading levels (0–2wt%) using the phase inversion method. Surface chemical compositions, surface and cross-section morphologies and characteristics, hydrophilicity and mechanical strength of the membranes were characterized using several analytical techniques and instruments such as scanning electron microscopy (SEM), atomic force microscopy (AFM), a contact angle goniometer, dynamic mechanical analyzer (DMA) and a nanoindenter. Membrane performance was also tested in terms of water flux, solute rejection, and anti-fouling characteristics. The experimental results demonstrated that the overall membrane structure was remarkably enhanced with the addition of Fe2O3 nanoparticles up to a loading of 1%. This was due to the membrane's more hydrophilic and smoother surface and a more elongated finger-like structure as well as higher porosity and pore size. The nanoindentation experiments indicated that Fe2O3 incorporation greatly enhanced the hardness of the membranes providing a higher pore integrity degree. However, higher Fe2O3 content caused a nanoparticle aggregation resulting in a decline in the performance of the composite membranes. Compared with the pristine PVC membrane, the membrane containing 1% Fe2O3 exhibited better capabilities such as the enhanced water flux (782L/m2h), higher sodium alginate (SA) rejection rate (91.9%) and better antifouling properties. The PVC/Fe2O3 nanocomposite membranes may have applicable potential in water and wastewater treatment applications based on their low price, enhanced mechanical strength, high permeability, high removal efficiency, and good antifouling performance.

Utilization of Sludge from Sidoarjo for Synthesis of Microball Photocatalist of Fe2O3 zeolit-chitosan as Fermented Soybean Waste-Degrading Agent

The sludge from sidoarjo have high Fe2O3 content of about 62,19%. This content have potential to prepare as photocatalyst for degraded fermented soybean waste by support sunlight. Synthesis of Fe2O3 zeolit-chitosan photocatalyst was carried out by impregnation into zeolite. Adding chitosan into the mixture of Fe2O3 zeolite then cast to be granules. Characterization of photocatalyst obtained using spectrophotometer IR, XRD, and DRS. Microball photocatalyst of Fe2O3 zeolit-chitosan with variation of pH 4, 6, and 8 then were done test of degradation performance by sunlight during 4 hours. As the result, the optimum pH of photocatalyast via COD test is pH 8. The higher base of photocatalyst, decreasing of degradation is higher.Keywords: degradation, Fe2O3, fermented soybean waste, sludge.

Mineral chemistry and genesis of the Permian Cihai and Cinan magnetite deposits, Beishan, NW China

Cihai and Cinan are Permian magnetite deposits related to mafic-ultramafic intrusions in the Beishan region, Xinjiang, NW China. The Cihai mafic intrusion is dominantly composed of dolerite, gabbro and fine-grained massive magnetite ore, while gabbro, pyrrhotite+pyrite-bearing clinopyroxenite and magnetite ore comprise the major units in Cinan. Clinopyroxene occurs in both deposits as 0.1–2mm in diameter subhedral to anhedral grains in dolerite, gabbro and clinopyroxenite. High FeO contents (11.7–28.9wt%), low SiO2 (43.6–54.3wt%) and Al2O3 contents (0.15–6.08wt%), and low total REE and trace element contents of clinopyroxene in the Cinan clinopyroxenite imply crystallization early, at high pressure. This clinopyroxene is FeO-rich and Si and Ti-poor, consistent with the clinopyroxene component of large-scale Cu-Ni sulfide deposits in the Eastern Tianshan and Panxi ares, as well as Tarim mafic intrusion and basalt, implying the Cinan mafic intrusion and sulfide is related to tectonic activity in the Tarim LIP. The similar mineral chemistry of clinopyroxene, apatite and magnetite in the Cihai and Cinan gabbros (e.g., depleted LREE, negative Zr, Hf, Nb and Ta anomalies in clinopyroxene, lack of Eu anomaly in apatite and similarity of oxygen fugacity as indicated by V in magnetite), indicate similar parental magmatic characteristics. Mineral compositions suggest a crystallization sequence of clinopyroxenite/with a small amount of sulfide – gabbro – magnetite ore in the Cinan deposit, and magnetite ore – gabbro – dolerite in Cihai. The basaltic magma was emplaced at depth, with magnetite segregation (and formation of the Cinan magnetite ores) occurring in relatively low fO2 conditions, after clinopyroxenite and gabbro fractional crystallization. The evolved Fe-rich basaltic magma rapidly rose to intermediate or shallow depths, forming an immiscible Fe-Ti oxide magma as fO2 increased and leaving a Fe-poor residual magma in the chamber. The residual magmas was emplaced at different levels in the crust, forming the Cihai gabbro and dolerite, respectively. Finally, the immiscible Fe-Ti oxide magma was emplaced into the earlier formed dolerite because of late magma pulse uplift, resulting in a distinct boundary between the magnetite ores and dolerite.

The Composition of Melts from a Heterogeneous Mantle and the Origin of Ferropicrite: Application of a Thermodynamic Model

Evidence for chemical and lithological heterogeneity in the Earth’s convecting mantle is widely acknowledged, yet the major element signature imparted on mantle melts by this heterogeneity is still poorly resolved. In this study, a recent thermodynamic melting model is tested on a range of compositions that correspond to potential mantle lithologies (harzburgitic to pyroxenitic), to demonstrate its applicability over this compositional range, in particular for pyroxenite melting. Our results show that, despite the model’s calibration in peridotitic systems, it effectively reproduces experimental partial melt compositions for both Si-deficient and Si-excess pyroxenites. Importantly, the model accurately predicts the presence of a free silica phase at high pressures in Si-excess pyroxenites, indicating the activation of the pyroxene–garnet thermal divide. This thermal divide has a dominant control on solidus temperature, melt productivity and partial melt composition. The model is used to make new inferences on the link between mantle composition and melting behaviour. In silica-deficient and low-pressure (olivine-bearing) lithologies, melt composition is not very sensitive to source composition. Linearly varying the source composition between peridotite and basaltic pyroxenite, we find that the concentration of oxides in the melt tends to be buffered by the increased stability of more fusible phases, causing partial melts of even highly fertile lithologies to be similar to those of peridotite. An exception to this behaviour is FeO, which is elevated in partial melts of silica-deficient pyroxenite even if the bulk composition does not have a high FeO content relative to peridotite. Melt Al2O3 and MgO vary predominantly as a function of melting depth rather than bulk composition. We have applied the thermodynamic model to test the hypothesis that Fe-rich mantle melts such as ferropicrites are derived by partial melting of Si-deficient pyroxenite at elevated mantle potential temperatures. We show that the conspicuously high FeO in ferropicrites at a given MgO content does not require a high-Fe mantle source and is indeed best matched by model results involving around 0–20% melting of silica-deficient pyroxenite. A pyroxenite source lithology also accounts for the low CaO content of ferropicrites, whereas their characteristic low Al2O3 is a function of their high pressure of formation. Phanerozoic ferropicrites are exclusively located in continental flood basalt (CFB) provinces and this model of formation confirms that lithological heterogeneity (perhaps recycled oceanic crust) is present in CFB mantle sources.