Estimation of Iron Ore Pellet Softening in a Blast Furnace with Computational Thermodynamics

In blast furnaces it is desirable for the burden to hold a lumpy packed structure at as high a temperature as possible. The computational thermodynamic software FactSage (version 7.2, Thermfact/CRCT, Montreal, Canada and GTT-Technologies, Aachen, Germany) was used here to study the softening behavior of blast furnace pellets. The effects of the main slag-forming components (SiO2, MgO, CaO and Al2O3) on liquid formation were estimated by altering the chemical composition of a commercial acid pellet. The phase equilibria for five-component FeO-SiO2-CaO-MgO-Al2O3 systems with constant contents for three slag-forming components were computed case by case and the results were used to estimate the formation of liquid phases. The main findings of this work suggested several practical means for the postponement of liquid formation at higher temperatures: (1) reducing the SiO2 content; (2) increasing the MgO content; (3) reducing the Al2O3 content; and (4) choosing suitable CaO contents for the pellets. Additionally, the olivine phase (mainly the fayalitic type) and its dissolution into the slag determined the amount of the first-formed slag, which formed quickly after the onset of softening. This had an important effect on the acid pellets, in which the amount of the first-formed slag varied between 10 and 40 wt.%, depending on the pellets’ SiO2 content.

Petrogenesis of the Jurassic Guiping Complex in the Southwestern South China Block: Insights into the Subduction Processes of the Paleo-Pacific Slab

Late Jurassic NE-trending A-type granitoids are widespread in the Shihang belt, South China, though their petrogenesis and geodynamic settings remain controversial. The Guiping complex is located on the southwest margin of the Shihang belt. In this study, the petrography, major and trace element geochemistry, whole-rock Sr-Nd isotopes, and zircon U-Pb geochronology of the Guiping complex were investigated. The Guiping complex is composed of the Fenghuangling and Xishan plutons; both plutons yielded zircon U-Pb ages of ca. 160 Ma. The Fenghuangling pluton has low SiO2 content of 54.26% to 60.31%, whereas the Xishan pluton exhibits high SiO2 content of 65.19% to 71.18%. Both of them are metaluminous and belong to the high-K calc-alkaline series and are enriched in large-ion lithophile elements (LILEs) such as Rb, Th, U, and Pb. The Fenghuangling and Xishan plutons showed enrichment in light rare earth elements (LREEs) and high-field strength elements (Nb, Ta, Zr, and Hf) and depletion in heavy rare earth elements (HREEs). Marked Nb and Ta negative anomalies were not observed. Due to the high contents of Zr + Ce + Nb + Y and high Ga/Al ratios, all the samples belonged to the group of A-type granites. The Fenghuangling and Xishan plutons had low ISr (mainly in the range of 0.7046–0.7058) and high εNd(t) (−0.60 to 1.94) values, though obviously different from those of the Precambrian basement in South China. Furthermore, they lie between the ocean island basalt (OIB) of the asthenosphere and the arc basaltic rocks of the enriched lithospheric mantle. Therefore, we proposed that the basaltic parental magma of the Guiping complex originated from partial melting of the enriched lithospheric mantle, which was metasomatized by asthenosphere-related OIB-type basaltic magma. Mafic microgranular enclaves in the Xishan pluton displayed positive Nb and Ta anomalies, which is consistent with OIB-type basalts. The enclaves also had similar Sr-Nd isotopic compositions to the Xishan pluton. That indicated that the enclaves were probably formed by mixing of the OIB-type basaltic magma and the Xishan pluton. In conclusion, the formation of the Late Jurassic NE-trending A-type granite belt was attributed to back-arc extension as a result of the rollback of the Paleo-Pacific Plate.

The Effect of Resin and NH4OH Addition in The Making of Ammonium Silica Fertilizer from Geothermal Sludge

Geothermal sludge is a waste product from geothermal where it contains SiO2 which can be used as fertilizer. In this study, the making of silica ammonium fertilizer was carried out by taking salicy acid from geothermal sludge by extracting and adding resin which was then modified with NH4OH addition. Extraction was done using 1000 ml of KOH 1 N to dissolve 60 grams of Geothermal Sludge. Resins are added with variations in resin weight, namely, 5, 10, 20, 30, and 40 grams. NH4OH was added with variations in concentrations namely 3, 6, 9, 12 and 15% with a ratio of filtrate and NH4OH solution of 1: 1. The resulting ammonium silica inorganic liquid fertilizer products were analyzed for free silica and ammonia levels. The results of this study indicate that the levels of free silica and ammonia are influenced by the weight of the resin used and the concentration of ammonium hydroxide mixed. From the results of the research, it was found that inorganic silica liquid fertilizer with the highest SiO2 content in ammonium silica liquid fertilizer occurred when adding 20 grams of resin with the addition of NH4OH with a concentration of 15% which was 1,831.87 mg / L while the highest NH3 content in fertilizer liquid ammonium silica occurs when adding 40 grams of resin with the addition of NH4OH with a concentration of 15% which is equal to 252,312.80 mg / L.

Composition and Pressure Effects on Partitioning of Ferrous Iron in Iron-Rich Lower Mantle Heterogeneities

Both seismic observations of dense low shear velocity regions and models of magma ocean crystallization and mantle dynamics support enrichment of iron in Earth’s lowermost mantle. Physical properties of iron-rich lower mantle heterogeneities in the modern Earth depend on distribution of iron between coexisting lower mantle phases (Mg,Fe)O magnesiowüstite, (Mg,Fe)SiO3 bridgmanite, and (Mg,Fe)SiO3 post-perovskite. The partitioning of iron between these phases was investigated in synthetic ferrous-iron-rich olivine compositions (Mg0.55Fe0.45)2SiO4 and (Mg0.28Fe0.72)2SiO4 at lower mantle conditions ranging from 33–128 GPa and 1900–3000 K in the laser-heated diamond anvil cell. The resulting phase assemblages were characterized by a combination of in situ X-ray diffraction and ex situ transmission electron microscopy. The exchange coefficient between bridgmanite and magnesiowüstite decreases with pressure and bulk Fe# and increases with temperature. Thermodynamic modeling determines that incorporation and partitioning of iron in bridgmanite are explained well by excess volume associated with Mg-Fe exchange. Partitioning results are used to model compositions and densities of mantle phase assemblages as a function of pressure, FeO-content and SiO2-content. Unlike average mantle compositions, iron-rich compositions in the mantle exhibit negative dependence of density on SiO2-content at all mantle depths, an important finding for interpretation of deep lower mantle structures.

The Structure, Morphology, and Complex Permittivity of Epoxy Nanodielectrics with In Situ Synthesized Surface-Functionalized SiO2

Epoxy nanocomposites have demonstrated promising properties for high-voltage insulation applications. An in situ approach to the synthesis of epoxy-SiO2 nanocomposites was employed, where surface-functionalized SiO2 (up to 5 wt.%) is synthesized directly in the epoxy. The dispersion of SiO2 was found to be affected by both the pH and the coupling agent used in the synthesis. Hierarchical clusters of SiO2 (10-60 nm) formed with free-space lengths of 53–105 nm (increasing with pH or SiO2 content), exhibiting both mass and surface-fractal structures. Reducing the amount of coupling agent resulted in an increase in the cluster size (~110 nm) and the free-space length (205 nm). At room temperature, nanocomposites prepared at pH 7 exhibited up to a 4% increase in the real relative permittivity with increasing SiO2 content, whereas those prepared at pH 11 showed up to a 5% decrease with increasing SiO2 content. Above the glass transition, all the materials exhibited low-frequency dispersion effect resulting in electrode polarization, which was amplified in the nanocomposites. Improvements in the dielectric properties were found to be not only dependent on the state of dispersion, but also the structure and morphology of the inorganic nanoparticles.

Photocatalytic Activity of Multicompound TiO2/SiO2 Nanoparticles

Multicompound TiO2/SiO2 nanoparticles with a diameter of 50–70 nm were generated using a liquid flame spray (LFS) nanoparticle deposition in a single flame. Here, we study the photocatalytic activity of deposited multicompound nanoparticles in gas-phase via oxidation of acetylene into carbon dioxide that gives new insight about the multicompound nanoparticle morphology. A small addition of SiO2 content of 0.5%, 1.0% and 3.0% significantly suppressed the photocatalytic activity by 33%, 44% and 70%, respectively, whereas 5.0% SiO2 addition completely removed the activity. This may be due to a formation of a thin passivating SiO2 layer on top of the of the TiO2 nanostructures during the LFS nanoparticle deposition. Surface wetting results support this hypothesis with a significant increase in water contact angle as the SiO2 content is increased.

ASSESSMENT OF THE IMPACT OF MODIFIER AND FILLER ON THE RHEOLOGICAL AND PHYSICAL AND MECHANICAL PROPERTIES OF PLASTER SOLUTIONS

The possibility of using microsilica as a filler for cement plaster mortars was analyzed. As a result of the analysis of reference data, the features of the hydration of cement with microsilica were determined. In the experiments, the rheological characteristics of cement slurries containing microsilica with different contents of amorphous silica and specific surface area were studied. One of the most important objects of studying the effect of microsilica and superplasticizer additives on the properties of plaster solutions was optimization due to the optimal selection of the concentrations of additives, the rheological properties of mixtures and their ratio with technological and operational factors. For the analysis and optimization, the quantitative ratio between the indicators of the structure and properties of plaster solutions and their determining factors, the formulations and technologies were obtained in the form of experimental-statistical models calculated using the COMPEX system. Based on the results of measurements of the rheological properties of cement solutions containing silica fume with the highest specific surface area and SiO2 content, complete rheological curves "strain rate – stress" were constructed and models of the main rheological parameters were calculated. To analyze the possibility of regulating the properties of cement systems with a superplasticizer, depending on the grain and chemical composition of the ultradispersed filler, multicomponent tetrahedral diagrams, which were combined with the concentration space of DSP -DМC in the "mixture – technology – properties" models were used. A specially synthesized saturated plan of 21 points has been implemented. Models were obtained in the form of reduced polynomials for different properties of cement-sand mortars (mobility and compressive strength after 1, 3, 9, 28 and 81 days of hardening in normal humidity conditions). Using a generalizing indicator, the sensitivity of the system to fluctuations in the fractional composition and SiO2 content was estimated.

Synthesis and Properties of Polyimide Silica Nanocomposite Film with High Transparent and Radiation Resistance

In order to prepare flexible glass cover sheet materials suitable for space solar cells, fluorinated diamine 2,2’-bistrifluoromethyl benzidine (TFDB) and fluorinated dianhydride 4,4’ (hexafluoroisopropyl) diphthalic dianhydride (6FDA) as the monomer, polyimide (PI)/SiO2 composite film was synthesized by in situ polymerization, and the influence of coupling agent and SiO2 nanoparticle content on the film structure and properties was studied. The results show that PI synthesized from fluorine-containing monomers has better light transmittance, and the highest transmittance can reach 91.4%. The average visible light transmittance of the composite film decreases with the increase of SiO2 content, and the transmittance of the film decreases less in the high-wavelength region and greatly decreases in the low-wavelength region. The tensile strength and elastic modulus of PI/SiO2 composite film increase with the increase of SiO2 content, first increase and then decrease, reaching the maximum when the content is 10%; while the elongation at break of the composite film gradually increases with the increase of SiO2 content reduce. The thermal stability of PI/SiO2 composite film increases with the increase of SiO2 content. The doping of nano-SiO2 significantly suppresses the influence of irradiation on the mechanical properties of the film.

ACTIVATION OF SINABUNG MOUNT VOLCANIC ASH USING VARIOUS MINERAL ACIDS

The effect of various types of mineral acids in activating the silica of volcanic ash of Mount Sinabung has been carried out. The use of various types of mineral acids is aimed at reducing impurities in the form of metals contained in the ash so that it can increase the SiO2 content in the ash. In the treatment, volcanic ash is prepared beforehand by grinding and sieving with a 200 mesh sieve. The sieved ash was then added with mineral acids, namely HCl, HNO3 and concentrated H2SO4 and heated at 100oC for 2 hours. After that, it was neutralized with distilled water and in an oven at 120oC for 6 hours and characterized using XRF to determine the impurities that had been lost. Based on the results obtained using XRF characteristics, the SiO2 content of volcanic ash activated with HCl was 80,23%, HNO3 was 77,23% and H2SO4 was 76,89%. This shows that activation using HCl is more optimal than using HNO3 and H2SO4.

Dyke Rocks of the Korsun-Novomyrhorod Anorthosite-Rapakivigranite Pluton

In spite of significant intensity and composition variability of dyke magmatism in the Ingul mega-block, in the Korsun- Novomyrhorod anorthosite-rapakivi granite pluton (KNP) dyke magmatism is restricted. To present day, dykes of basic composition have not been described in this pluton. Previously mentioned gabbro-diabases dykes or diabase porphyrites should be classified as medium rocks as well as they are enriched by SiO2, Na2O and K2O. The authors succeeded studied the dyke from the Nosachiv massif, which can be considered the only known dyke of basic composition in KNP. By chemical composition, this rock is similar to the Ti-enriched gabroids of KNP, but differs in the presence of high-Ti magnetite (not typical mineral in plutonic rocks of KNP), and in terms of SiO2 and Na2O + K2O it should be classified as subalkaline. Most of the dikes known in the KNP are mainly monzonites, monzosienites, less widespread syenites, granite dikes are quite rare too. As our studies have shown, in the previously described porphyry dykes diabase structure is not exihibited. Furthermore pyroxene content is the first percent, and a significant (or most) of them are probably xenogeneic. According to chemical composition such dykes should be classified as medium in composition, because the SiO2 content in them is in the range of 54-60 % and elevated content of K2O, often prevails over Na2O, by low MgO and higher TiO2 they are similar to gabroid of KNP. In these rocks, normative orthoclase and quartz are calculated in significant quantities. Therefore, we offer to consider these rocks as dyke analogues of monzonites (quartz-containing or quartz) and regard as monzonite porphyry. The significant distribution of monzonites and syenites and their dyke analogues denote clear pronounced monzonite-syenite trend of evolution in KNP.