CaO Content Research Articles

Zircon U-Pb ages and Hf isotope characteristics of granitic rocks from the Shapinggou molybdenum deposit, Dabie Shan, China

The giant Shapinggou porphyry molybdenum deposit in Jinzhai county, Anhui province is located in eastern Dabie Shan, but its genesis, genetic type and tectonic setting are still debated. New zircon U − Pb age data presented in this contribution show that the granitic rocks at Shapinggou area have been episodically formed at ∼ 135 Ma, ∼127 Ma, ∼117 Ma and ∼ 113 Ma in Early Cretaceous, and can be classified into the early-stage (135–127 Ma) granodiorite and monzogranite plutons, and the late-stage (117–113 Ma) quartz-orthophyre stock and cryptoexplosive breccia pipes. Mo mineralization is closely associated with the late-stage shallow-seated granitic stock or pipes. Granitic rocks of both stages have high contents of SiO2, K2O + Na2O and Al2O3, low contents of TiO2, CaO and MgO, showing a metaluminous to peraluminous, high-K calc-alkaline to shoshonite affinity. They are generally featured by enrichments of LILE (Rb, U, Th) and LREE, and depletions of HFSE (Nb, Ta, Ti) and HREE, with high (La/Yb)N ratios. The early-stage granitic plutons show trace element geochemical signatures of partial melting of over-thickened continental crust (>50 km), whereas element geochemistry of the late-stage small-sized granitic intrusions suggests a shallow source depth (ca. 35 km) under post-collisional extension setting. The Hf isotope data indicate that the Shapinggou granitic rocks are originated from a crustal source predominated by the Kuanping Group mixed with other components such as the mantle. The southward subduction and partial melting of the southern North China Block (including Kuanping Group) beneath the Dabie Shan lead to the generation of the Shapinggou porphyry Mo system in the post-collisional extension setting. Hence the Shapinggou Mo system distinguishes for its crustal source and post-collisional tectonic setting from the porphyry Mo deposits of Climax- or Endako-types, and should belong to collision-type or Dabie-type porphyry Mo deposit.

Magmatic Garnet and Magma Evolution in Cuonadong Leucogranites: Constraints from Petrology and Mineral Geochemistry

Located at the eastern segment of the Tethyan Himalayan tectonic unit, the Cuonadong leucogranites (muscovite granite and pegmatite) have a mineral assemblage of quartz, plagioclase, and alkali feldspar, as well as muscovite and garnet. Garnets in both muscovite granite and pegmatite belong to the almandine–spessartine solid solution, with minor andradite, grossular, and pyrope, and show a specific Mn zoning of a relatively rim-ward Mn depletion trend. However, a few garnets in pegmatite show grossular enrichment towards the rim. All the analyzed garnets are characterized by HREE enrichment and LREE depletion with obvious Eu anomalies. The difference is that garnets from the muscovite granite show distinct left-declined or flat HREE patterns, while those from the pegmatite are featured by flat or right-declined HREE patterns. Moreover, garnets from the pegmatite show relatively more distinct HREE- and Y-rich cores compared with those from the muscovite granite. The MnO concentration, spessartine content, and MnO/(MnO + FeO) ratio of the garnets from the Cuonadong dome increase from the muscovite granite to the pegmatite, suggesting that the pegmatite likely formed from a more evolved environment. Elevated grossular and CaO contents of the garnet rim in the pegmatite may reflect an influence of fluids in their composition. The major and trace element compositions and zoning textures of garnets from the Cuonadong leucogranites suggest a magmatic origin and a formation at moderately low temperatures and relatively low-pressure conditions. From the muscovite granite to the pegmatite, the system entered a fluid-rich environment and the garnets from the pegmatite likely crystallized from a lower-temperature fluid.

On the origin of vesuvianite-rich rodingites from the Western Carpathians, Slovakia

Rodingite represents a particular metasomatic rock type that occurs as dykes or lenses in association with serpentinized ultramafic rocks and typically consists of Ca-rich, often hydrated silicate minerals. Rodingites have been recognized as a source of information on fluid compositions and their circulation in both ocean floor and subduction environments. Yet, the nature of the protoliths, the chemistry and the origin of fluids, the details of fluid-rock interaction, and the metamorphic context remain often obscure. This work investigates some of these questions in the case of rodingites from the Western Carpathians through petrological, mineralogical and geochemical studies. Rodingites are here associated in the field with serpentinized tectonically dismembered bodies of ultramafic rocks embeded into Carboniferous metasediments. They mostly consist of vesuvianite, diopside, and hydrated garnet with minor titanite, chlorite, epidote, calcite and FeTi oxides. Three successive hydrothermal events were recognized: 1) formation of diopside, vesuvianite and garnet, 2) formation of a second generation of vesuvianite and garnet together with titanite and minor chlorite, and 3) formation of a mineral assemblage consisting of epidote, chlorite and calcite. The first two events represent a pervasive and intense rodingitization process, whereas the third one represents late, channeled, fluid circulation under greenschist facies conditions. The presence of FeTi oxides influences the mineralogy and the whole rock chemistry of the investigated rodingites. Rutile and ilmenite are commonly associated with titanite and garnet, and whole rock analyses can reach up to 9.2 wt% TiO2. Vesuvianite and garnet also incorporate a significant amount of titanium. The lack of primary minerals, the mineral composition as well as high CaO and low SiO2 contents demonstrate high extent of Ca-metasomatism. The high modal amount of vesuvianite and the immobility of Al during metasomatic processes suggest that the protolith was relatively Al-rich. Taking into account the REE patterns of whole-rock and minerals, the high TiO2 content and the local Fe-Ti-rich accumulations, we suggest that the protoliths were more or less Fe-Ti-rich gabbroic rocks initially occurring in association with the serpentinized ultramafic body.

HREE enrichment during magmatic evolution recorded by apatite: Implication for the ion-adsorption HREE mineralization in South China

Understanding the enrichment of heavy rare earth elements (HREE) and high HREE/LREE (light REE) ratios in the granites is critical to understand the ore-genesis of exclusive ion-adsorption HREE deposits in South China. In this study, we conducted geochronological, whole-rock and apatite geochemical, and isotopic studies on the Xinfeng pluton, of which only parts show high HREE/LREE ratios and are ore-related. Both the ore-related granite and ore-unrelated granite from the Xinfeng pluton are characterized by high SiO2 contents, the same Late Jurassic age (ca. 155 Ma), and enriched Nd isotopic compositions. However, the ore-related granite has lower TiO2, CaO, P2O5, Fe2O3, Ba, Sr, Eu, and LREE contents, lower La/Yb, Zr/Hf and Th/U ratios, higher Rb, Cs, Nb, Ta, Pb, and HREE contents, and higher Rb/Sr ratios than the ore-unrelated granite. These features indicate that the ore-unrelated and ore-related granite are cogenetic and their geochemical differences can be explained by magmatic differentiation. The primary igneous apatite from both the ore-unrelated granite and ore-related granite shows negligible hydrothermal alteration. Fractional crystallization of feldspar (∼20%) and allanite (< 0.3%) led to higher HREE contents and HREE/LREE ratios, lower Sr contents, and a more pronounced negative Eu anomaly in the apatite from the ore-related granite. This study highlights that the magma evolution via mineral fractional crystallization could achieve the relatively high HREE contents and HREE/LREE ratios in the granites, and favors the formation of exclusive ion-adsorption HREE deposits in South China.

Türkiye'deki Muskovit Ocaklarının Elementel Bileşimlerinin Dağılımı

In this study, the contents of thirty-five elements (nine major-minor oxides, twenty-one heavy metals, and five other elements) in eighty-four muscovite samples collected from three commercially operated quarries in Manisa province of Turkey were determined using an energy dispersive X-ray fluorescence (EDXRF) spectrometer. The mean concentrations of SiO2, Al2O3, K2O, MgO, Na2O, Fe2O3, P2O5, TiO2 and CaO analyzed in mica samples were determined as 57.1, 32.8, 8.7, 2.9, 1.4, 0.8, 0.3, 0.3 and 0.3%, respectively. The mean concentrations of Cr, Zr, Mn, Zn, Ni, Co, Pb, Cu, Cd and Hg analyzed as primary toxic trace heavy metals in mica samples were found as 136.2, 124.6, 58.7, 19.2, 14.8, 6.8, 6.3, 2.6, 2.0 and 1.2 mg kg-1, respectively.

Forced carbonation – A new method to determine the degree of recarbonation of calcium silicate units

AbstractRebound effects in building materials reduce the CO2 content of the atmosphere. This reabsorption of CO2 during service life and recycling is called recarbonation. In contrast to concrete, detailed knowledge about the CO2 cycles of autoclaved aerated concrete and calcium silicate units is missing. Moreover, standards concerning adequate sampling methods as well as suitable calculation methods do not exist yet.Autoclaved aerated concrete is a highly porous material and recarbonizes evenly. Hence, samples for examination can be drilled out. In contrast, calcium silicate displays lower porosity and decreased CO2 permeability. Therefore, its recarbonation starts on the surface and penetrates inwards. The units are inhomogeneously recarbonized. Consequently, bulk samples – not drill samples – must be taken.In addition, calcium silicate contains considerable amounts of CaO bound in silicates. For this reason, the degree of recarbonation must not be calculated on the basis of the total CaO and CO2 content. The newly developed calculations are based on the maximum CO2 uptake determined using forced carbonation. It is carried out under defined temperature, humidity and CO2 conditions in a climate chamber. Thanks to this method, the degree of recarbonation of calcium silicate can be determined more precisely.

Effects of mineral additives and age on microstructure evolution and durability properties of sand-reinforced cementitious mine backfills

• Effects of sand, slag and fly ash on microstructure and strength of cemented fillings were studied. • Backfill specimens were manufactured with constant cement (5 wt%) and solid (72 wt%) contents. • Among others, 30% sand-based cementitious fillings offered the best mechanical strengths. • Sand-GBS-based backfills supports hydration reactions and prevent fill acidifying in the long-term. • Voids of fine-grained GBS and FA is well filled with sand, improving the strength of fillings. Cementitious paste/mine backfill (CMB/CPB) is a creative way to proficiently decrease the sum of sulfidic tailings. However, considering them as minor raw material and inadequacies in their gradation, OPC (costly and insufficient)-induced ecological harms, using alternative additives in CMB has become essential. This study aims to increase the short-/long-term filling performance and to reduce cement-related costs by using both sand as tailings substitute, and GBS or FA (granulated blast furnace slag or fly ash) as OPC substitution. Some mechanical (UCS, stress–strain, and modulus of elasticity) and microstructural (MIP, XRD, TG/DTG and SEM) characterization tests for CMBs were experimentally scrutinized. Samples were prepared at diverse curing ages (3–180 days), constant cement/solid content (5/72 wt%), three diverse aggregates (tailings/sand: 100/0, 90/10 and 70/30) and OPC (OPC/GBS-FA: 100/0, 90/10 and 70/30) substitution ratios. Results disclosed that 30% sand-based CMB (S30) offered the best strengths. Besides, strength loss was observed in all 90-day cured backfills, while strength gain was observed in sand/GBS-based backfills up to 180 days. This can be stated by the fact that sand/GBS supports hydration reactions and prevent fill acidifying in the long-term owing to their high CaO contents (sand: ∼54%; GBS: ∼35%). Moreover, improving sand’s gradation, filling the voids of fine-grained GBS and FA is one of the cogent reasons for strength gains. To summarize, this study runs a full report on a cost-effective and viable CMB system that will both make operations profitable/sustainable and prevent environmental damages.

Characterization of geochemical elements in surface sediments from Chinese deserts

Northern China has 12 main deserts that range from extremely arid regions in the west to semi-arid or semi-humid regions in the east. Based on their geographical locations, we divided these deserts into western, central, and eastern deserts. We investigated the geochemical elements in their surface sediments and found that the concentration of the major element SiO2 gradually increased from west to east, whereas the other major elements tended to decrease; however, the CaO concentration was unusually high in the Taklimakan and Qaidam Basin deserts. The spatial distribution of geochemical elements was more homogeneous in the western and central deserts than in the eastern. Unlike the eastern deserts, the western and central deserts show greater physical than chemical weathering and lower mineral maturity due to the extremely low precipitation and a continuous supply of younger materials. Most major trace elements in the eastern deserts were more depleted relative to the upper continental crust than in the western deserts, but were moderately depleted in the central deserts. The potential source rocks of central and western deserts are composed of intermediate igneous source rocks, while the sediments in eastern deserts are derived from the mixing of felsic and intermediate igneous source rocks or the mixing of quartzose deposits and intermediate igneous source rocks. The spatial distribution of geochemical elements showed similar provenances of aeolian material in the Taklimakan Desert and Kumtag Desert, and similar provenances of aeolian material in the Badain Jaran, Tengger, Ulan Buh, and Hobq deserts. There were no obvious provenance relationships for the Otindag, Horqin, and Hulun Buir sandy lands in the central and western deserts.

Comparison of mechanical, chemical, and thermal activation methods on the utilisation of recycled concrete powder from construction and demolition waste

Recycled concrete powder (RCP) poses a considerable challenge with respect to effective utilisation of construction and demolition waste (CDW) resources due to its low activity, high water demand, and potential to cause dust pollution during storage. A suitable activation method is necessary for stimulating the potential activity of RCP and enhancing its utilisation. Therefore, the effect of mechanical, chemical, and thermal activation methods on the properties of RCP were investigated in this study. Mechanical and thermal activation were helpful for the activity of RCP due to the modification of particle size and distributions. RCP exhibits a higher content of SiO2 and a lower content of CaO as well as the main crystal phases of quartz, calcite, gismondine, and dolomite. After 400–800 °C thermal activation, dolomite is not observed while the RCP shows new active components (such as larnite, calcium silicate, and calcium oxide). The chemical activation test highlights that CaO (3%) is the most optimal, followed by CaSO4 (1%) and Na2SO4 (2%), while Ca(OH)2 (4%) has the least optimal activation effect on the strength activity index (SAI) of RCP mortar. For combined activation, Ca(OH)2 and CaSO4 with 1:1 ratio has the most optimal activation effect, and the SAI reaches 80.27%. Based on the mechanical performance, SAI, and micro-characteristics, the most feasible and effective activation method is thermal activation (800 °C), followed by chemical activation (Ca(OH)2+CaSO4), and mechanical activation (75 min). This study proposes a useful combined activation method for RCP that verifiably contributes to the application of CDW.

Nd3+ doped [formula omitted] glass systems: Structural and optical properties

The structural and optical characteristic features of B2O3 + Li2O + CaO + CaF2 (BLCofNd) glasses incorporated with Nd3+ as a dopant of different concentrations (mol%) are reported. The X-ray diffraction technique was used to study structural characteristics such as the amorphous nature of BLCOFNd glass samples, Infrared spectroscopy was used to investigate the presence of functional groups and their impact on optical characteristics (FTIR), It reveals the creation of a network by borate and other components with the characteristics of glasses demonstrating different stretching and oscillating behavior of borate functional groups. The recorded UV Vis-NIR spectra of BLCofNd glasses reveal the prepared glasses have strong absorption at 584 nm in the visible region and 805 nm in the NIR region for the transitions 4I9/2→4G5/2 and 4I9/2→4F5/2, these transitions are due to the excitation of electrons by induced absorption. The density (gm/cc) measurements seem to be a rise in the values with a proportionality increase in CaO concentration (mol%), which directly relates to the decrease in the interionic distance (ri) making the glasses optically dense. Judd–Ofelt intensity parameters (Ω2, Ω4 and Ω6) highlights a covalency symmetry with a higher degree and surrounding lattice distribution of Nd3+ ions with other glass elements present in the network. The radiative properties of BLCOFNd glass samples mainly relate to parameters of radiative transition probability (AR), and corresponding branching ratios (βcal and βrad), which are derived from oscillator strength (fexp) measurements, FWHM or peak bandwidth (Δλp), stimulated emission cross-section and gain bandwidth (σse. Δλp) foresees that BLCofNd glasses are best candidates for laser host materials. The neodymium-doped borate glass exhibits a high peak power due to its emission at 1.049 μm wavelength and has its applications as lasing material and is prominently used as a source to produce the secondary waves in the measurement of pollutants in the atmosphere, optical amplifiers, and in the industry for their high intensity in emitted radiation.

Systematic variation of inorganic additives and their impact on interfacial delamination processes of automotive coating systems

Inorganic fillers incorporated in adhesives for the automotive industry enable both functional and mechanical tuning of adhesive properties. While integral effects of additives are well understood, the individual effects of single components and how they may lead to synergies as well as antagonistic effects remain unclear. Here, we systematically vary the concentration of CaO, CaCO3 and hydrophobic fumed SiO2 to understand individual and combined effects. For this purpose, the inorganic additives were mixed into a model formulation without inorganic additives and compared with a close to real application one-component epoxy adhesive, which also contained these fillers. The water uptake of the filled adhesives was measured with EIS and the results were compared with findings from cataplasma tests under atmospheric conditions. These results indicated that hydrophobic SiO2 can result in accelerated water uptake, although the opposite would be expected due to the more hydrophobic surface coating. In addition, blistering was observed on all galvanized steel (ZE) surfaces, while filiform corrosion was observed on all hot-dip galvanized Zn-Al-Mg steels (ZM). Cataplasma tests in oxygen-depleted and oxygen-rich atmospheres allowed to identify interfacial delamination processes. Our results showed that CaO can cause osmotic blistering and accelerate the diffusion of water into the adhesive due to a local increase in pH near the hydrated CaO particles, while CaCO3 reduces water diffusion. However, coating defects may occur due to the addition of CaCO3, leading to increased cathodic blistering. A strategy for improving beneficial and synergistic effects is discussed.

TWO STAGES OF THE CENOZOIC ALKALINE-BASALT VOLCANISM IN THE DARKHAD DEPRESSION (NORTHERN MONGOLIA) – GEOCHRONOLOGY, GEOCHEMISTRY, AND GEODYNAMIC CONSEQUENCES

The isotopic data showed that there are two stages distinguished in the Cenozoic history of the Darkhad depression volcanic activity, the Late Oligocene initial stage (~28.0–26.6 Ma) and the final Late Miocene – Early Pliocene stage (~5.8–4.2 Ma). It has been stated that the rocks of the initial stage are only represented by trachybasalts; however, among the final-stage basaltoids there are series of shield-volcano hawaite-basanite-phonotephrite rocks and compex trachybasaltic "valley" lava flows, the formation of which is the last stage in the territorial volcanic evolution. It has been shown that the initial-stage trachybasaltic andesites are characterized by their enrichment of TiO2, P2O5, Sr, Zn, Ga and low concentrations of Al2O3, MnO, CaO, Sc and HREE (La/Yb=27.2–30.2). Basaltoids of the final stage have a similar rare-element distribution and show an increase in the contents of TiO2, Al2O3, P2O5, LILE, HFSE, Th, U and in the degree of fractionation of REE (La/Yb from 12.2 to 20.9) towards the rocks alkalinity enhancement. Modeling of eclogite, pyroxenite and peridotite melting processes in the La/Yb – Sm/Yb system shows that trachybasaltic andesite melts could be formed at ~7–8 % melting of eclogitic matter or at ~10–11 % melting of Grt-containing pyroxenites, with trachybasalt formed at ~3 % melting of Grt-containing peridotites. The composition distribution of rocks in coordinates (Mg# – Fe/Mn) indicates that the parental magmas are the initial-stage trachybasaltic andesite magmas as well as the Early Pliocene trachybasaltic "valley" lava flows. Sr, Nd, Pb isotope characteristics of the Darkhad depression basaltoids show significant shift of isotopic ratios in time towards the relatively enriched mantle as compared with the depleted MORB mantle. The initial formation of trachybasaltic andesite melts occurred in the Late Oligicene at the pre-rift stage of the territory development involving metasomatized mantle matter, with the pyroxenite or eclogite component contained in the magma formation source. The origin of trachybasalt magmas of the final stage is associated with the processes of decompression melting of peridotites in a weakly metasomatized lithospheric mantle at the rift stage of the Darkhad structure development.

Phase Formation and Stabilization Behavior of Ca-PSZ by Post-Heat Treatment

The phase formation and stabilization behaviors of calcia partially stabilized zirconia (Ca-PSZ) were investigated with regard to the CaO content and post-heat treatment. Sintered specimens were prepared by adding 2, 3, 4, and 5 mol% to CaO to ZrO2, and post-heat treatment were conducted. In the X-ray diffraction pattern, the monoclinic peak decreased, the tetragonal peak increased upon CaO doping, and no CaZrO3 peak was observed. Transmission electron microscopy images of the Ca-PSZ showed that the d-spacing of 4CSZ (200)m extended from 0.260 nm to 0.266 nm subsequent to post-heat treatment. The coefficient of thermal expansion gradually increased in accordance with the dopant concentration, in addition, it increased even after the post-heat treatment. These results are related to the increase in tetragonal phase, which has a relatively higher coefficient of thermal expansion than that of the monoclinc phase. According to the Vickers hardness measurement, the hardness of all specimens increased gradually as the concentration of CaO increased, and the hardness of the 5CSZ was improved from 676 to 774 Hv by the post-heat treatment.

Effect of CaO and SO2 on the distribution of arsenic species during coal combustion at high temperature

ABSTRACT Arsenic emission from coal combustion is of great concern due to its high toxicity and ecological environment hazards. Toxicity of arsenic is related to its speciation. Effects of CaO and SO2 on arsenic emission during SH and HLH coal combustion at high temperature were obtained through thermodynamic calculation. It indicates that the volatilisation ratio of arsenic in the form of As4O6 (g) increases as the combustion temperature increasing. Coal type and content of CaO significantly affect the transition temperature of arsenic volatilisation. During SH combustion, with the addition of 10 wt % CaO, the inhibition rate of arsenic volatilisation is gradually increased to its maximum value of 30.46% at 900°C. The transition temperature of arsenic volatilisation is 1100°C and the inhibition rate is 42.74% with 20 wt % CaO added. As for HLH, either 10 wt % or 20 wt % CaO is added, the transition temperature are both 1200°C, with the inhibition rate of 36.46% and 48.37%, respectively. Moreover, competition is existed between SO2 and arsenic during coal combustion. When the temperature is above 1100°C, for the preferential reaction between CaSO4 and As4O6, the competition of SO2 on arsenic volatilisation is weakened.

Recycling of granite powder and waste marble produced from stone processing for the preparation of architectural glass–ceramic

• Glass-ceramic was prepared using granite powder and waste marble by melting-sintering method. • The addition of MgO changes the main crystalline phase of the glass–ceramic from wollastonite to augite. • The acid resistance of glass-ceramics is weakened with the increase of basic oxide content in the chemical composition. • The glass–ceramic with flexural strength of 146.95 MPa and Vickers hardness of 10.24 GPa can be achieved. A large amount of solid waste is generated during the stone processing, and a serious environmental issues has arisen from the accumulation of these wastes. In this work, granite powder and waste marble are used to prepare architectural glass–ceramic. The mechanical properties, microstructure, and acid resistance of glass-ceramics designed with different compositions were investigated. With the increase of waste marble content, the main crystalline phase of glass–ceramic changed from anorthite to wollastonite, and the flexural strength of glass–ceramic was also enhanced. When the mass ratio of granite powder to waste marble is 40:60, a CaO-Al 2 O 3 -SiO 2 (CAS) glass–ceramic with a flexural strength of 109.33 MPa and a Vickers hardness of 6.61 GPa is obtained. After the addition of MgO, the main crystalline phase of the glass–ceramic is augite. Under the addition of 5 wt% MgO, the flexural strength and Vickers hardness of CaO-MgO-Al 2 O 3 -SiO 2 (CMAS) glass–ceramic reached the maximum, which are 146.95 MPa and 10.24 GPa, respectively. The mechanical properties of these two types of glass-ceramics developed from granite powder and waste marble can meet the requirements of building materials. From the acid resistance test results, it was found that the higher the content of MgO and CaO in the chemical composition of glass–ceramic, the worse the acid resistance. Therefore, the basic oxide content should be carefully controlled in the composition design of glass–ceramic. This technology of converting granite powder and waste marble into value-added glass–ceramic provides a promising method for the utilization of solid waste from stone processing, which can greatly improve the sustainability of the stone industry.

Research on the mechanism of sodium separation in bauxite residue synergy preparation of potassium-containing compound fertilizer raw materials by the hydrothermal method.

Bauxite residue poses an increasingly serious ecological safety problem in the alumina industry. A novel process for removing sodium in bauxite residue synergistic preparation of potassium-containing compound fertilizer raw materials was proposed to relieve pressure on the fertilizer industry. In this paper, synthetic sodalite and katoite were used to simulate the main mineral phases of bauxite residue to determine the suitable conditions for the method, and the transformation mechanism of the process was researched by analyzing the phase structure and microscopic morphology of the samples using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and specific surface area detection. The results show that the ideal reaction condition is 320g/L K2O with solid reactants at 200°C for 1h. The separation rate of Na in the sodalite-katoite mixture reached 93.60%, with potassium aluminum silicate and katoite being the primary phases of the product, with a mesoporous structure and easy to be absorbed by crops. The bauxite residue transformation residue consisted of katoite and kaliophilite. With a total effective K2O, CaO, and SiO2 content of 38.22%, the Na2O content was 0.54%, meeting the requirements of compound fertilizer content on the market. The transformation mechanism is a dissolution-precipitation controlled sodium-potassium ion replacement reaction. This study provides theoretical guidance for the preparation of mineral fertilizer from bauxite residue and has practical production potential, opening up a new perspective for bauxite residue resource usage in the agricultural field.

CO2‐Rich Rejuvenated Stage Lavas on Hawaiian Islands

AbstractSedimentary carbonates are sent to the deep mantle if they are not completely destroyed at subduction zones, and subducted carbonates may contribute to plume volcanism. To better constrain the role of recycled carbonates in Hawaiian volcanism, we report high‐precision olivine and whole‐rock geochemical compositions of shield and rejuvenated stage lavas from Kauai, Oahu and Maui Islands. The studied rejuvenated stage whole‐rocks have low SiO2 and high CaO concentrations, and are depleted in high field strength elements, such as, Nb and Zr, consistent with a role of carbonated melt. Rejuvenated stage olivines have Ni abundance lower than and CaO and MnO contents similar to those of shield stage at a given Fo. The calculated partition coefficients of Ca () and Mn () between olivine and shield melts are consistent with those of a dry melt system. However, the low and for rejuvenated lavas can only be explained by a volatile‐rich melt system. Based on the observed and in rejuvenated lavas, and considering the effect of H2O, our modeling calculation shows that rejuvenated primary magmas contain up to ∼10 wt% CO2, indicating a CO2‐rich mantle source. Using olivine‐spinel aluminum exchange thermometry, we show that the rejuvenated primary magma temperatures are similar to those of shield stage. We posit that the CO2‐rich rejuvenated stage lavas with lower olivine Ni than those of shield stage lavas were originated from melting of carbonated peridotites in the plume. The carbonated melts that metasomatized the peridotites were likely derived from subducted ancient carbonate‐bearing lithospheric mantle.

Metallurgical Study of Iron Artifacts from Guryong-ri Site in Ungcheon, Boryeong

In the 6&lt;sup&gt;th&lt;/sup&gt; and 7&lt;sup&gt;th&lt;/sup&gt; centuries, 5 iron artifacts excavated form the Baekje Stone Tomb in Guryong-ri site, Ungcheon, Boryeong, were studied. The sample were metal microscopic observation, SEM-EDS analysis and Raman micro-spectroscopy analysis were conducted to understand the metallurgical characteristics. The microstructure observation showed the presence of ferrite and pearlite throughout, and differences in carbon content existed depending on the direction. Non-metallic inclusions were in the form of long lines, and most of them were wüstite, fayalite. It is indicated that the artifacts were forge welded using hypoeutectoid steel, with signs of carburizing and decarburizing processes. Some crystals with high P2&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt;, TiO&lt;sub&gt;2&lt;/sub&gt;, CaO content were identified as sarcopside, ulvöspinel, and perovskite, respectively, through Raman spectroscopy. A comparison of the results with previous studies on the sites of Bujang-ri site in Seosan and Bongseon-ri site in Seocheon, which are adjacent sites in the coastal area, revealed that, while heat treatment technology was available, the artifacts were not heat-treated considering the purpose for use for these artifacts. The chemical composition of the non-metallic inclusions P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt;, TiO&lt;sub&gt;2&lt;/sub&gt;, CaO were plotted in proportions to SiO&lt;sub&gt;2&lt;/sub&gt; and compared with adjacent sites. Considering that the P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt; ratio was widely distributed, the refining technology was not uniform. In addition, the TiO&lt;sub&gt;2&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt; ratio was found to be higher than that of other sites, meaning that a titanium-containing ore was used to manufacture the artifacts, unlike in surrounding sites, but it is not detected in all artifacts, so it may have been affected by various factors such as furnace walls in addition to raw materials. Although slag formers were used, considering the CaO/SiO&lt;sub&gt;2&lt;/sub&gt; ratio and the (Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;/SiO&lt;sub&gt;2&lt;/sub&gt;)/(CaO/SiO&lt;sub&gt;2&lt;/sub&gt;) ratio, which appear to be similar to the surrounding sites, but it is possible that CaO containing raw ore was used because it is also affected by the components of raw ore. As a result of the study, it is highly likely that ore different from that of the surrounding sites was used for production, but a more comprehensive comparative study with the surrounding sites is needed in the future.

Preparation and Characterization of White Mineral Trioxide Aggregate (WMTA) using Silica from Rice Husk Ash

&lt;p&gt;The preparation of white mineral trioxide aggregate (WMTA) was carried out using a solid technique using silica (SiO2) from rice husk ash (RHA). The process included extraction of SiO&lt;sub&gt;2&lt;/sub&gt; from RHA, the effect of SiO&lt;sub&gt;2&lt;/sub&gt; composition on material characterization and material compressive strength. Silica was extracted from RHA using NaOH and washed with distilled water until it was sodium-free. WMTA was prepared by mixing extracted SiO&lt;sub&gt;2&lt;/sub&gt;, Bi&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; commercial (18.0%), CaO commercial and Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; commercial (2.0%), and the mixture was heated at various temperatures (900, 1000, 1100 &lt;sup&gt;o&lt;/sup&gt;C). MTA was made from two variation silica sources: RHA and extracted silica, and each source varied at 15, 20, and 25% by weight, while the CaO content was adjusted. Characterization was carried out by FT-IR spectrophotometry, XRD and UTM for compressive strength measurement conducted after cementation for a day. The RHA extraction results were obtained from sodium-free SiO&lt;sub&gt;2&lt;/sub&gt;. The peak showed the success of WMTA preparation at wave number 910 cm&lt;sup&gt;-1&lt;/sup&gt; in FTIR spectra, indicating the presence of C-S-H and C&lt;sub&gt;3&lt;/sub&gt;S, C&lt;sub&gt;2&lt;/sub&gt;S, and C&lt;sub&gt;3&lt;/sub&gt;A bonds both before and after thermal treatment in XRD data. The highest compressive strength test after cementation for one day (3.21±0.13MPa) was given by WMTA using RHA, heating at 900 &lt;sup&gt;o&lt;/sup&gt;C, and the percentage of CaO and SiO&lt;sub&gt;2&lt;/sub&gt; were 60% and 20%, respectively.&lt;/p&gt;

Paleoenvironment of Mesoproterozoic Gaoyuzhuang and Wumishan Formations, North China: New Insights from Geochemistry and Carbon and Oxygen Isotopes of Dolostones

The Mesoproterozoic Gaoyuzhuang and Wumishan Formations are major geothermal reservoirs in the Hebei Province, North China. Compared to the exploration of geothermal resources and heat-controlling structures, carbon and oxygen isotopic records of the two formations are limited. Here, we present integrated field, petrological, geochemical, carbon, and oxygen isotopic data of carbonate rocks from the Gaoyuzhuang and Wumishan Formations. The Wumishan Formation is characterized by higher CaO and MgO contents and lower SiO2 contents than the Gaoyuzhuang Formation, indicating that the source of the Wumishan Formation likely contains less terrigenous clastic materials. The two formations have low total rare earth element contents, similar to marine carbonate rocks. They show different Eu and Ce anomalies, Al/(Al + Fe + Mn) and Fe/Ti ratios, and (Co + Ni + Cu) contents. They generally show similar carbon isotopic compositions, whereas the carbonate rocks of the middle-upper Gaoyuzhuang Formation show lower δ18O values than the samples from the Wumishan and lower Gaoyuzhuang Formations. These data suggest that the two formations have experienced different transgressive–regressive cycles and that their sedimentary environments varied and were unstable in different sedimentary periods. The middle-upper Gaoyuzhuang Formation was likely affected by hydrothermal fluids, whereas the Wumishan Formation is composed of normal seawater deposits. Integrated evidence reveals that both of the Mesoproterozoic Gaoyuzhuang and Wumishan Formations were deposited in rift environments caused by the breakup of the Columbia/Nuna supercontinent.