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In the selective reduction process of lateritic nickel ore, the formation of the liquidus phase could be obtained by increasing the temperature and additive, resulting in an uneconomic process. Nevertheless, it could also be obtained by modifying the ore basicity by adding low-cost fluxes, such as CaO, SiO2, MgO, and Al2O3. In this work, the effect of three types of basicity (binary, ternary, and quaternary) in selective reduction of saprolitic nickel ore on metallic grade and recovery, phase transformation, and microstructure of ferronickel was investigated clearly. The nickel ore, sodium sulfate, coal, and flux mixture was reduced to 1150 °C for 60 min. Then, the wet magnetic separation process was continued to separate ferronickel from impurities. The result showed that the optimum basicity for the selective reduction of saprolitic nickel ore was 0.6 of ternary basicity (CaO + MgO/SiO2), modified by CaO addition. It produced 16.11% and 50.57% for nickel grade and recovery in concentrate, respectively. Modified basicity with CaO addition is more effective than MgO, Al2O3, and SiO2 addition due to its ability to break the forsterite structure and release iron and nickel. It also could be reacted with magnesium silicate structure to form calcium–magnesium silicate structure such as melilite and monticellite.

Sintered and fused magnesia (FM) produced from the macrocrystalline magnesite in China have attracted attention worldwide for the production of various refractories. Herein, dead burnt magnesia (DBM) with varying compositions was investigated. The results revealed that the periclase crystals of the DBM92 sample were subrounded to rounded euhedral, whereas the periclase crystals of the DBM95 sample were subhedral and idiomorphic. In addition, a significant amount of periclase–periclase bonding with straight boundaries was observed in the DBM97 sample. The periclase crystals of the DBM98 sample with no clear boundaries exhibited the densest packing among the samples. The silicate matrix around the periclase grains of the DBM92 sample contained forsterite and monticellite, whereas that around the periclase grains of the DBM95 sample was mainly composed of monticellite and merwinite. Dicalcium silicate and merwinite were observed in small amounts as interstitial phases in the DBM97 sample. In contrast, only dicalcium silicate, which was concentrated in small triangular pockets, was observed in the densely packed periclase grains of the DBM98 sample. The hot modulus of rupture tests revealed that an alkali-resistant DBM95-based brick can be prepared at a lime–silica ratio of

The aim of the present work is to characterize the phosphate sludge from the area of Youssoufia (rich in CaO ~ 31%) and to study its thermal behavior alone and when mixed with clay from Safi (Morocco). This may contribute to its valorization as an alternative raw material for ceramic industries. The evolution of phases during the thermal treatment of phosphate sludge, clay and sludge–clay mixtures at different mass ratios (25 wt%, 50 wt%, and 75 wt%) was performed at different levels of temperatures from 600 to 1120 °C. Mineralogical analysis by X-ray diffraction (XRD) showed that the sludge mainly consisted of quartz, calcite, dolomite, and francolite. Dolomite and calcite vanished after sludge heating and two new phases were formed, namely akermanite and monticellite. For clay, it mainly consisted of illite, kaolinite, quartz, calcite, and dolomite. After clay sintering at high temperature, a new phase was formed, i.e. anorthite. The effects of the MO/SiO2 ratio (MO = CaO + MgO) in mixtures (clay + sludge) on the crystallization behavior of diopside and fluorapatite, and the disappearance of the akermanite were investigated. The results showed that the crystallization of diopside–fluorapatite increased when the MO/SiO2 ratio increased. Resumen: El objetivo del presente trabajo es caracterizar un lodo de fosfato del área de Youssoufia (rico en CaO ~ 31%) y estudiar su comportamiento térmico tras su mezcla con una arcilla de Safi (Marruecos). Este estudio puede contribuir a su valorización como materia prima alternativa para la industria cerámica. La evolución de las fases minerales durante el tratamiento térmico de lodos de fosfato, arcilla y mezclas de lodos y arcilla en diferentes proporciones de masa (25, 50 y 75% de peso) se realizó a diferentes temperaturas, desde 600 a 1.120 °C. El análisis por difracción de rayos X (DRX) permitió conocer la composición mineralógica del lodo formado principalmente por cuarzo, calcita, dolomita y francolita. La dolomita y la calcita desaparecieron tras el calentamiento del lodo y se formaron 2 nuevas fases, a saber, akermanita y monticellita. En cuanto a la arcilla, el análisis mineralógico evideció la presencia de illita, caolinita, cuarzo, calcita y dolomita como fases mayoritarias. Tras la descomposicón de la arcilla se formó anortita como fase de alta temperatura. Se investigaron los efectos de la relación MO/SiO2 (MO = CaO + MgO) en mezclas (arcilla + lodo) sobre la cristalización de diópsido y fluorapatita y la desaparición de la akermanita. Los resultados mostraron que la cristalización de diopsido-fluorapatita aumentó cuando creció el cociente MO/SiO2.

This study aimed to investigate extensively the full phase formation mechanism from the lowest temperature to form the phases to the optimum temperature to crystallize akermanite. The effects of various milling speeds and sintering temperatures on physico-mechanical properties of akermanite prepared using high-energy planetary milling method were also investigated. The minimum formation temperature of akermanite phase (above 800°C) was determined by X-Ray diffraction (XRD) and differential thermal analysis. XRD analysis revealed akermanite had formed through gradual phase development with the increase in temperature. Below 700C, akermanite was structurally unstable while multiple transient compounds (low clinoenstatite, wollastonite, monticellite, and diopside) coexisted, as indicated by low peak intensities. Single phase akermanite was obtained by heat-treating at 1100C. Physical studies suggested the densest akermanite ceramic feature, with tensile strength range of 25.26 ± 1.41 MPa32.10 ± 2.13 MPa and Vickers microhardness range of 1.39 ± 0.04 GPa4.94 ± 0.26 GPa could be obtained at 1250°C.

The rich mineral resources of magnesite have been decreasing rapidly, while the low-grade magnesite is abandoned, and the requirement on utilization of low-grade magnesite is causing much attention. La2O3 has been introduced as an additive in this study, considering its positive role in the modification of the magnesia matrix. Low-grade magnesite containing 0–3 wt% La2O3 was fired at 1550 °C for 3 h. The effect of La2O3 on the microstructural evolution and thermomechanical property of sintered low-grade magnesite was investigated. The results showed that La2O3 markedly improve the microstructure of sintered low-grade magnesite. The distribution state of the low melting monticellite phases among the periclase grains evolved from distribute continuously to concentrate in isolation at the triple-point junction of the periclase grains, and the generated CaO·3SiO2·2La2O3 based dendrites phases interlaced in the magnesia matrix. The hot modulus of rupture (HMOR) was significantly enhanced with increasing addition of La2O3 due to the low-melting monticellite phases were transformed to CaO·3SiO2·2La2O3 phases based dendrites with large aspect ratio, effectively reducing the availability of monticellite. Besides, the bridging phenomenon resulting due to the dendritic phase exhibited an optimal toughening effect, attributing to the increase in crack deflection and resistance to crack propagation.

The study of the Bol’shaya Tagna alkaline-carbonatite massif and adjacent areas was focused on the mineral and chemical compositions of minerals, the distribution of petrogenic and trace elements in pyroxene-free alkaline picrites in veins and dikes dated at the late Riphean (circa 645 Ma), and comparison with the Bushkanai kimberlite-picrite dike. Phenocrysts in the pyroxene-free picrites are represented by olivine (replaced with serpentine) and phlogopite; the bulk is formed by serpentine, phlogopite, monticellite, calcite, etc .; xenocrysts of pyrope and chrome diopside are absent. Phlogopite and Cr-spinel from the picrites are chemically similar to these minerals in kimberlites, but the evolution of the spinel compositions corresponds to the titanomagnetite trend; monticellite is depleted in forsterite (Mg 2 SiO 4 ). The rocks contain strontianite, burbankite, titanium andradite, calcirtite and Mn-ilmenite, which are not typical of kimberlites, but are inherent in carbonate-bearing ultramafic lamprophyres, ayllikites. The pyroxene-free picrites have low contents (wt %) of SiO 2 (28.4‒33.2), Al 2 O 3 (3.2‒5.6), and Na 2 O (0.01‒0.05); relatively high contents of TiO 2 (2.0‒3.3), and К 2 О (0.45‒1.33); varying contents of MgO (16.1‒24.1), СаО (12.9‒22.8), СО 2 (1.1‒12.2), Ni (260‒850 ppm), and Cr (840‒2200 ppm); and Mg#=0.73‒0.80. The contents of Th, U, Nb, Ta, La, and Ce in the veins are approximately two orders higher than those in the primitive mantle; the spectra of trace elements differ from the spectra of the South African and Yakuian kimberlites. In the pyroxene-free picrites and the rocks of the Bushkanai dike, the Nb/U, Nb/Th, Th/Ce, La/Nb, and Zr/Nb ratios are similar to those in ocean island basalts (OIB) and thus give evidence of the leading contribution of the recycled component into the source melt. In experiments conducted to investigate melting of carbonated garnet lherzolite, the pyroxene-free alkaline picrites melted at 5–6 GPa.

Oxygen side-blown reducing smelting is an efficient and environment-friendly technology to directly process the liquid high-lead slag, but it shows high refractory wear during industrial practice. To understand the specific degradation mechanisms, a post-mortem analysis of magnesia-chromite refractory bricks (fused-grain rebonded type) taken from the tuyeres of the furnace was performed by SEM and phase diagram. According to the results, typical reaction zone and infiltrated zone were formed between the hot face and the original refractory. The fast and deep infiltration of PbO-containing fayalite slag under turbulent conditions was responsible for the significant dissolution of periclase grains, which caused the development of a continuous and thick forsterite layer. Meanwhile, the components of FeO and ZnO in the slag were mainly absorbed by the chromite grains. Then the increased CaO/SiO2 of the slag resulted in the large formation of monticellite in the infiltrated zone. Based on these results, the key reasons for the high wear of refractory lining were revealed and several possible solutions were also proposed.

This paper investigated the oxidation of fayalite (Fe2SiO4) in iron-rich nickel slag (INS) for iron recycling via an oxidation-magnetic separation method. A phase stability diagram of the FeO–SiO2–MgO–CaO–O2 system drawn by FactSage 7.1 illustrates that magnetite (Fe3O4) can be crystallized from liquid slag in an air atmosphere, but the further oxidation to Fe2O3 in molten slag was extremely hard. The mass content of divalent iron (w(Fe2+)) decreased and the ratio of trivalent iron to divalent iron (w(Fe3+)/w(Fe2+)) increased gradually with increasing oxidation time. The results show that an air flow rate of 300–500 mL/min, a basicity of 0.90–1.10, and a temperature of 1658–1728 K are conducive to the oxidation of Fe2SiO4 in INS. Fe3O4 is the main iron-bearing phase, and Fe2O3 is not observed in the X-ray diffraction (XRD) patterns. Silicates in the oxidized nickel slag (ONS) are mainly augite (Ca(Mg,Fe)Si2O6), forsterite ((Mg,Fe)2SiO4), and monticellite (CaMgSiO4), while akermanite (Ca2MgSi2O7) is observed only for a basicity up to 1.10. The oxidation kinetics of Fe2SiO4 in INS are first order with an apparent activation energy (Ea) of 315.16 kJ/mol.

Colloidal silica has been utilized as a binder agent in various areas owing to its sinterability and high permeability. However, regarding its use in MgO–CaO hot gunning mixes are lacking. In this study, phase compositions and physical properties of different colloidal silica contents on hot gunning mixes were investigated. The rebound loss rate of hot gunning mixes at 1100 °C was also evaluated via thermal simulation. In addition, the interface analysis between the gunned layer and Mag-Chrome bricks was presented, and the results were compared with those obtained using conventional phosphate-bonded mixes. The results indicate that the colloidal silica-bonded MgO–CaO hot gunning mixes achieve the appropriate mechanical strength and bulk density with 5 wt% of colloidal silica; the primary phases of mixes were forsterite and monticellite. In comparison with the conventional phosphate-bonded gunning mixes, the use of colloidal silica led to better physical properties and lower rebound loss rate under the present experimental conditions. Moreover, the gunned layers obtained were more compact and cohesive than the ones prepared using conventional phosphate-bonded mixes.

A thermochemical study of natural calcium and magnesium orthosilicate monticellite (Ca1.00Mg0.95$${\text{Fe}}_{{0.05}}^{{2 + }}$$)[SiO4] from the Khabarovsk Territory, Russia, was carried out on a Tian–Calvet microcalorimeter. The enthalpy of formation from elements Δf$$H_{{{\text{el}}}}^{^\circ }$$(298.15 K) = –2238.4 ± 4.5 kJ/mol was determined by high-temperature melt solution calorimetry. The enthalpy and Gibbs energy of formation of monticellite of theoretical composition of CaMg[SiO4] are calculated: Δf$$H_{{{\text{el}}}}^{^\circ }$$(298.15 K) = –2248.4 ± 4.5 kJ/mol and Δf$$G_{{{\text{el}}}}^{^\circ }$$(298.15 K) = –2130.5 ± 4.5 kJ/mol.

Actuality of steel-making slags utilization is stipulated not only by the necessity to improve ecology situation at the sites of slag piles, but also by a possibility to obtain additional raw materials for metallurgical production. Increase of the domestic iron-containing raw materials at Magnitogorsky steel-works can be done by more effective processing of steel-making slags. To improve the technology of BOF slags processing, a work done to study their chemical and mineral composition. It was established, that primary and secondary BOF slags are attributed to basic and ultra-basic, since the SiO2 mass share is less than 25–40%. Petrographic study results and data of IR-spectroscopy showed, that larnite, alite, monticellite and oxide RO-phase (Fe2+, Mn2+, Mg2+)O are main mineral components of the BOF slags. In many cases, the structure of the secondary BOF slags has middle-size grains, and the structure of primary slags is fine-grained. The texture of the secondary and primary slag is more often massive. The BOF slags have globules of iron, the size of which varies from sub-millimeters up to 5 mm. Study of influence of various methods of BOF slag particles destruction on the degree of globules disclosure showed, that application of centrifugal-striking crushing facilities provides more selective globules disclosure comparing with other methods. It was proved, that dry magnetic separation in suspended state, due to its peculiarities, provides higher technological indices comparing with drum separator when separating fine slags even at increase material moisture up to 5%.

Treatment of bone defects requires materials or bone cement with superior mechanical properties and favorable biological properties, but this remains unachievable to date. To address this issue, the present study aimed to synthesize and characterize a novel poly(methyl methacrylate) (PMMA) bone cement containing monticellite (Mon) and carbon nanotubes (CNTs) for bone defect treatment. Considerably better mechanical properties were noted in the PMMA-Mon-CNT vs. PMMA and PMMA-Mon bone cements due to the unique resistance of CNTs to crack formation and propagation. Favorable bioactivity was also found in the bone cements containing Mon and CNTs, whereas the PMMA bone cement presented poor bioactivity. Specifically, the incorporation of Mon and CNTs into the PMMA matrix promoted the attachment of MG63 cells compared to the PMMA cement. Thus, the PMMA-Mon-CNT bone cements developed are good potential candidates for filling bone defects in orthopedic surgeries.

In this study, monticellite (CaMgSiO4) ceramic was successfully synthesized by a sol–gel method. The degradation test was evaluated through the weight loss of the CaMgSiO4 ceramic during immersion in Tris–HCl buffer solution. In vitro apatite-formation ability of the CaMgSiO4 ceramic was investigated by soaking in the simulated body fluid (SBF), and the deposited hydroxyapatite (HAp) after soaking was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results showed that the CaMgSiO4 ceramic had a low degradation rate. Furthermore, CaMgSiO4 ceramic showed good apatite-formation ability, HAp layer constituted by needle-like crystallites was investigated on CaMgSiO4 ceramic surface after soaking in SBF solution.

The preparation of MgO bearing iron ore pellets in the mini and pilot scales, and the application for 4070m3 blast furnace were conducted in this paper. The results show that with increasing the MgO content, the compressive strength of fired pellets decreased significantly, while the metallurgical performances, such as RI (reducibility index), RDI (reduction degradation index) and RSI (reduction swelling index) were improved. The scanning electron microscope with energy dispersive spectrometry was used to test the microstructures and the compositions of iron oxide, and the slag of pellets. With increasing the MgO content, MgO exists in the form of magnesium ferrite and monticellite, which presents the high melting temperature, decreasing the content of liquid phase. The pilot scale experiment was performed on a commercial running grate-rotary kiln with the annual output of 2.4 million tons of pellets, which agrees with the results obtained in the mini scale experiment. The application of MgO-bearing pellets was carried out in the 4070 m3 blast furnace of Meisteel China, and the production indexes improved with increasing the yield and reducing the coke ratio, and the total benefits are 7067 USD/d, which presents the superior economic benefits.

Biodegradable magnesium alloy was coated by nanostructured monticellite (Mon; CaMgSiO4) through electrophoretic deposition (EPD) coupled with plasma electrolytic oxidation (PEO) with the purpose of enhancing the corrosion properties, bioactivity, and cytocompatibility. The monticellite layer with a thickness of 15 μm and strong adhesion with the PEO coated Mg alloy is able to provide the corrosion protection for the Mg substrate. Microstructural analysis depicted that the monticellite coatings were homogeneous with no obvious cracks or pinholes on the surface of PEO coated Mg alloy. The electrochemical tests in SBF exhibited that the corrosion rate of the Mg alloy was considerably reduced after preparation of monticellite layer on its surface. Furthermore, high impedance of the monticellite coated Mg alloy was observed even after 96 h of incubation in SBF. The apatite layer with spherical morphology was formed on the monticellite surface via interaction of OH− ions from SBF which could accelerate the healing process. The biocompatibility was evaluated via examination of the osteoblastic MG-63 cells response in-vitro. Deposition of nanostructured monticellite induces high osteoblastic proliferation and supplies suitable sites for cell attachment and growth. The cell adhesion and viability are also determined to evaluate the biological response. Moreover, biphasic drug release graphs of the monticellite coating containing tetracycline show an initial immediate release which is followed by more stable release patterns. Overall, it is anticipated that the novel proposed nanostructured coatings of monticellite can improve the corrosion resistance and cytocompatability of the Mg alloys, which make it useful for orthopedic implants.

Lizardite rich peridotite has never been used to prepare ceramic specimens, especially in Morocco. For this raison, potential use of naturally abundant lazirditic material from the Rif domain, as a supply for ceramic industry, has been evaluated. The effects of lizardite addition to magnesite and dolomite mixtures on the thermomechanical properties of the calcined ceramics were also detailed. To achieve this target, natural lizardite, magnesite and dolomite samples were collected in ultrabasic Beni Bousra massif. Those raw samples were used for the synthesis of a forsterite-monticellite rich ceramics. Both raw and sintered samples were characterized by x-ray diffraction, scanning electron microscope and fourier transform infrared. The obtained results showed that both magnesite and dolomite were mainly composed of MgCO3 and CaCO3. In contrast, lizardite sample showed high amounts of SiO2, MgO and Fe2O3. An increased amount of lizardite in the initial mixtures enhanced mechanical and dimensional properties of the prepared ceramic specimens, and subsequently, the production of ceramics with the required technological properties. Thus, the preparation of Moroccan lizardite-based ceramics is technically feasible, economically justifiable and socially desirable due to the contribution to the economic growth of the raw materials sector, especially ceramic industry.

In vitro activity is important when considering the choice of a multiphasic bioceramic scaffold as phases can dissolve or transform at different rates. The aim of this study is focused on the synthesis and in vitro analysis of multiphasic ceramics obtained from the melt by directional solidification. Depending on the growth rate of the new composition different bioactive phases coexist in the same sample: akermanite, monticellite, tricalcium phosphate and Nurse's A phase, all of them with potential in the medical area as implant for bone or dental repair. With the knowledge of what and how phases dissolve first, it was possible to design materials to get porous scaffolds or more stable ceramics., The authors would like to acknowledge the use of Servicio General de Apoyo en la Investigación- SAI, Universidad de Zaragoza. BMM wants to acknowledge the financial support awarded by the Spanish Ministry of Science and Innovation through the grant PID2019-103847RJ-I00, as well as the one provided by the Regional government of the ‘Junta de Andalucía’ through the project P18-RTJ-1972.

Focused on uncoated ceramics, this tutorial paper is divided into two main sections. The first section deals with the operational phases required prior to firing (drying, piling, fuel supply). Then, the second chapter deals with the transformations that occur in the clayey paste during firing. An overall understanding of the firing process includes several issues to be considered and properly investigated. Thereafter, the thermal behaviour of several mineralogical phases (calcite and dolomite; quartz and cristobalite; K-feldspar and plagioclase; rutile and anatase; haematite, maghemite, hercynite and metallic Fe; illite, muscovite, biotite and chlorite; wollastonite, melilite, anorthite and monticellite; diopside and kaolinite) is described. Four brief chapters are further dedicated to the development of the amorphous/glassy component, to the matrix and its porosity, to the colour and the organic matter and to the variations in chemical composition, respectively. The concluding remarks provide a short list of the analytical techniques that have been commonly applied to the investigation of firing conditions and a concise summary of the state of the art of the “firing issue”. The method to be applied in future experimental reproductions and the opportunity itself to investigate the “firing issue” in various contexts are further discussed.

Ferronickel tailings, by-products from nickel laterite direct reduction-magnetic separation process, are now stored up in large quantities with low utilization because of the high MgO content. In this paper, ferronickel tailing with 5.82% Fe, 0.51% Ni, 44.08% SiO2, and 31.98% MgO was adopted to replace the traditional Mg-bearing flux, i.e. serpentine. The laboratory pot sintering tests show that, this new technique increases sinter productivity and tumble index by 4.12% and 10.63%, respectively, and reduces solid fuel rate by 6.35%. The mineralogical study of product sinter shows that the addition of ferronickel tailing contributes to the increase of the amount of SFCA by 4.03%. Mg and Al elements were found to migrate into magnetite grains to form three types of spinel solid solutions, i.e. (Fe, Mg)Fe2O4, Fe (Fe, Al)2O4, and (Fe, Mg)·(Fe, Al)2O4. Meanwhile, eutectic compound melts were obtained by the co-melting of kirschsteinite (CaO·FeO·SiO2), monticellite (CaO·MgO·SiO2), and fayalite (2FeO·SiO2).

The effect of particle size and phosphorous content in biomineralization media on in vitro bioactivity of monticellite based ceramic powders was investigated. Monticellite based ceramic powder was synthesized at 800 °C for 4 h using boron derivative waste. Monticellite based ceramic powder, comprising monticellite, akermanite, diopside, calcium magnesium borate and zeolite LTA crystalline phases, was crushed and then ball-milled for optimized time to obtain lowest average particle size and the narrowest particle size distribution. In vitro bioactivity of both coarse (d10: 0.5 μm, d50: 3.0 μm, d90: 42 μm) and fine (d10: 0.5 μm, d50: 1.4 μm, d90: 4.8 μm) wafers was determined by incubation in Lactated Ringer's Solution and Human Blood Plasma for 1, 3, 5, 7, 14, 21 and 28 days at 36.5 ± 0.5 °C. The obtained results exhibited that calcite (CaCO3) layer after immersion in Lactated Ringer's Solution and bone-like apatite layer after immersion in Human Blood Plasma were formed on the surface of coarse and fine wafers. The presence of phosphorus in biomineralization media is necessary for apatite formation. The increment of surface roughness favors homogeneous nucleation, and fasten nucleation and growth kinetics of precipitation. As a result, the bioactive characteristic of monticellite based ceramic powder could be governed by the particle size. Resumen: Se investigó el efecto del tamaño de partícula y el contenido de fósforo en los medios de biomineralización sobre la bioactividad in vitro de polvos cerámicos a base de monticellita. El polvo cerámico a base de monticellita se sintetizó a 800 °C durante 4 h utilizando residuos de derivados de boro. El polvo cerámico a base de monticellita, que comprende monticellita, akermanita, diópsido, borato de calcio y magnesio y fases cristalinas de zeolita LTA se trituró, y luego se molió con bola durante un tiempo optimizado para obtener el tamaño de partícula promedio más bajo y la distribución de tamaño de partícula más estrecha. La bioactividad in vitro de obleas gruesas (d10: 0.5 μm, d50: 3.0 μm, d90: 42 μm) y finas (d10: 0.5 μm, d50: 1.4 μm, d90: 4.8 μm) se determinó mediante incubación en solución de Ringer lactato y plasma sanguíneo humano durante 1, 3, 5, 7, 14, 21 y 28 días a 36,5 ± 0,5 °C. Los resultados obtenidos mostraron que la capa de calcita (CaCO3) después de la inmersión en la solución de Ringer lactato y la capa de apatita similar a un hueso después de la inmersión en plasma sanguíneo humano se formaron en la superficie de obleas gruesas y finas. La presencia de fósforo en los medios de biomineralización es necesaria para la formación de apatita. El incremento de la rugosidad de la superficie favorece la nucleación homogénea y fija la cinética de nucleación y crecimiento de la precipitación. Como resultado, la característica bioactiva del polvo cerámico a base de monticellita podría estar gobernada por el tamaño de partícula.

Monticellite is a calcium-magnesium based material with better bioactivity, high mechanical strength, cytocompatibility and osteointegration. Sol-gel assisted combustion technique was adopted to prepare pure monticellite phase by using three different fuels (citric acid, glycine and urea). The influence of different fuels on material properties of monticellite was analyzed with the aid of XRD, SEM, TEM and AFM techniques. The XRD patterns revealed that among the three fuels examined, glycine and urea resulted in pure monticellite phase at 1200°C while citric acid derived monticellite showed akermanite as secondary phase. Morphological analysis such as SEM and TEM micrographs of monticellite showed spherical beads like structure with agglomeration of particles and the particle size lies in the micron regime. Atomic force microscope image shows high surface roughness for the monticellite prepared by using urea as a fuel.

Solid-state synthesis of monticellite based ceramic powders from boron derivative waste in an eco-friendly route and the investigation of phase transformation mechanisms were studied. The heat-treatment of boron derivative waste, mainly composed of dolomite, calcite and quartz, was systematically carried out at 650 degrees C and 800 degrees C for various dwell times between 1 min and 4 h. The heat-treatment temperatures were selected considering TG-DTA curves of waste and Delta G - T diagrams obtained using FactSage Thermochemical Software. XRF, XRD, FTIR, TG-DTA and SEM analysis, particle size measurement and crystallite size determination carried out extensively. The obtained results showed that monticellite based ceramic powder synthesized at 800 degrees C for 4 h was composed of monticellite, akermanite, diopside, calcium magnesium borate and zeolite. The calcination of dolomite was completed both at 650 degrees C for 1 h and up to 800 degrees C, and calcite was decomposed at 800 degrees C for 30 min. Both diopside and monticellite were firstly detected at 650 degrees C for 30 min and at 800 degrees C for 1 min. Also, akermanite was presented at 800 degrees C for 1 min. The presented method offers the lowest temperature (800 degrees C) in literature for synthesis of monticellite and akermanite which reduces the energy consumption during heat-treatment. (C) 2018 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Processing of magnesia based ceramic by unidirectional dry pressing from Moroccan magnesite is described. The applied magnesite was characterized in terms of its composition, granulometric analysis, surface specific area, and thermal behavior. After appropriate processing, the prepared specimens were fired at various temperatures up to 1350 °C to study the ceramic properties. The ceramic material resulted after firing was investigated regarding the phases composition, structural characteristics, and physical properties of technological interest. On this way, the production of materials having interesting properties such as shrinkage, porosity, density, flexural strength, toughness, dielectric constant, and thermal conductivity is achieved. An X-ray diffraction (XRD) analysis showed that the ceramic sample is composed of periclase as major phase and monticellite and calcium alumino-ferrite as minor phases. The content of amorphous phase that governs the sample properties varies between 26.5 and 31%. Thermal shock tests realized in water showed that the ceramic sample presents good thermal shock resistance. The results revealed that Moroccan magnesite has qualities necessary for the manufacture of ceramic products.

Silicon (Si)- and magnesium (Mg)-containing bioceramics have recently gained much attention for tissue engineering applications due to their ability to stimulate cell proliferation and differentiation along with their adequate microstructural and physicochemical characteristics. In this study, nanostructured monticellite (CaMgSiO4, 33.33% of Mg) was chosen as an appealing biomaterial to identify time- and dose-dependent cytocompatibility, in vitro osteogenic activity and antibacterial & anti-biofilm activity. A time- and dose-dependent MTT assay illustrated that monticellite nanoparticles promoted proliferation of bone like cell considerably more than positive and negative controls. The cell viability of the bioceramic was higher than hydroxyapatite (HA, as bone inorganic material) and control sample, demonstrating that cytocompatibility was promoted due to the increase of Mg content. The results of alkaline phosphatase (ALP) activity test demonstrated that the osteogenic proliferation of osteoblast-like G292 cell line enhanced more by the bioceramics extract than control and HA, corroborating when Mg content of the calcium-silicate bioceramics is increased cytocompatibility and bioactivity are significantly promoted. Moreover, further analyses revealed that the bioceramic possessed antibacterial and anti-biofilm properties due to the presence of Mg, Si and Ca elements in the structure. These findings suggest that the proposed nanostructured monticellite is a promising biomaterial for further applications in tissue engineering.

In this study, nanostructured monticellite (CaMgSiO4) bioceramics were prepared via sintering the sol–gel-derived monticellite powder compacts at 1200 °C. The mean of particles size distribution of the synthesized monticellite powders was approximately 90 nm. After evaluating physicochemical characteristics of the synthesized bioceramics, apatite-forming ability of the samples were examined in simulated body fluid (SBF) for different time periods. The soaking effect of various time periods on the X-ray diffraction (XRD) patterns, followed by the calculations from scherrer's equation, showed that the crystallite size of the immersed monticellite ceramics in SBF for 3 and 7 days was around 88 nm. Williamson-Hall analysis was also used to calculate the lattice strain of the samples. Based on the results, by changing the soaking time, crystallite size and lattice strain have meaningfully changed. The release of Ca, Mg and Si ions from the nanostructured monticellite significantly promoted cell proliferation and growth at a certain concentration range more than that of positive and negative controls. This study could provide an in-depth understanding of the microstructural and physicochemical characteristics of this class of biomaterials. The follow-up studies should correlate the microstructural and physicochemical properties to the molecular and biological characteristics for applications in tissue engineering and regenerative medicine.

The high hydration potential of CaO and MgO phases restricted the application of Mag-Dol refractory composites. In this study, the impact of nano-silica (SiO 2 ) addition on the physical, mechanical, thermo-mechanical as well as microstructure of Mag-Dol refractory composites is investigated. Mag-Dol compositions were prepared by using calcined dolomite and magnesite particles (micron, 0–1, 1–3, 3–5, and 5–8 mm), liquid resin, and 0, 0.5, 1, 1.5, 2, and 2.5 wt% nano SiO 2 as additives. Specimens were heated up to 1650 °C for the 3 h soaking period. Fired specimens were characterized by physical (apparent porosity, bulk density, and hydration resistance), mechanical (cold crushing strength), and thermo-mechanical (flexural strength at 1200 °C) measurements. XRD and SEM/EDS analysis were done to study phases and microstructure analysis of the fired samples, respectively. Results showed that by adding up to 2.5 wt% nano-SiO 2 , due to the formation of CaO·MgO·2SiO 2 (Diopside), 2CaO·MgO·2SiO 2 (Akermanite), and CaO·MgO·SiO 2 (Monticellite) phases, physical and mechanical properties were enhanced. But the highest flexural strength value is achieved for 1 wt% nano-SiO 2 containing sample.

Dolomite base refractories have advantages such as high refractoriness, potential to produce pure steel molten, high alkaline corrosion resistance, and economical for consumers. However, application of these refractories has been limited due to their high potential to hydration with atmosphere humidity. In this research work, the impact of ZrSiO 4 nanoparticles addition on the physical, thermo-mechanical, mechanical, and microstructure of the dolomite base refractories is investigated. Also, XRD and SEM/EDX analyses were used for determining generated ceramic phases and microstructure evaluation, respectively. Up to 3 wt% ZrSiO 4 nanoparticles were added to the compositions. Compositions fired at 1650 °C for 4 h in an electrical furnace. The results showed that the bulk density (from 2.95 to 3.33 g/cm 3 ), cold crushing strength (from 352 to 393 kg/cm 2 ), and hydration resistance (from1.95 to1.16%) of the compositions were increased while apparent porosity was decreased (from 9.33% to 4.84%) by the addition of ZrSiO 4 nanoparticles. As well as, for compositions containing 2.5 and 3 wt% ZrSiO 4 nanoparticles flexural strength at 1200 °C is decreased due to the generation of high content low melting phases such as Belite (2CaO.SiO 2 ), Diopside (CaO.MgO.2SiO 2 ),Akermanite (2CaO.MgO.2SiO 2 ), and Monticellite (CaO.MgO.SiO 2 ) at the firing process temperature. Finally, based on the obtained results and its relationship with the microstructure and properties the amount of2 wt% ZrSiO 4 nanoparticle was determined as the optimum content.

To aid development of cost-effective sintered spinel as a refractory raw material, this paper presents an extensive analysis of microstructure and complex phase evolution of Al-rich, Mg-rich, and stoichiometric spinel aggregates derived from Indian magnesite and calcined alumina. Pore morphology in Al-rich spinel was transformed upon sintering at 1650°C and corundum laths embedded in porous Al-rich spinel matrix was formed. Stoichiometric spinel sintered at 1600°C consisted of mostly direct bonded angular equiaxed spinel grains which incorporated the impurities in solid solution. Mg-rich spinel was composed of spinel grains with reduced angularity along with intergranular amorphous phase, small round monticellite grains, and periclase. EDS line scan revealed impurity-free joins existed between direct bonded spinel grains. Mg-rich spinel containing 0.65 wt% ZrO2 formed cubic ZrO2-CaO-MgO solid solution located along spinel boundaries, which reduced both intergranular amorphous phase and monticellite. This increased SiO2 and MgO content in spinel solid solution triggering exsolution of metastable cubic forsterite manifested as split spinel peaks in XRD pattern. A 14.7% reduction in slag penetration was exhibited upon doping Mg-rich spinel with 0.21% ZrO2. Stoichiometric and Mg-rich spinels attained 0.35% and 0.54% apparent porosity at 1600°C, which is better than most commercial sintered refractory spinels.

In this research, high-pure monticellite ceramic (CaMgSiO4) nanoparticles were synthesized via a novel sol–gel method using ethanol and chloride ions for the acceleration of polycondensation process. The gel obtained from metal alkoxide and metal salts precursors dried at 100°C; then, the dried-gel calcined at different temperatures to monitor the structural development of the final samples. The effect of various heat-treatment temperatures on the x-ray diffraction patterns, followed by the calculations from scherrer’s equation, showed that the grain size of the synthesized samples at 1200°C was around 28 nm. Based on dynamic light scattering spectroscopy, the size of most of the particles was ~85 nm. Williamson–Hall formula was also used to calculate the lattice strain of the samples. According to the results, by changing the heat-treatment temperature, lattice strain/stress, lattice parameters and grain size have meaningfully changed. The proposed synthesis method showed superior advantages in comparison with the other conventional techniques presented in the literature, which is relatively faster at lower temperatures. The synthesized high-pure monticellite nanoparticles could be applied in different biomedical engineering applications in which the purity and structural properties are of importance, such as dental, bone tissue engineering, coatings on biomedical implants, surgery hemostasis and inducing osteogenesis in vivo applications.

Small amount of Y2O3 (0-3 wt%) was added into off-grade natural magnesite and its effects on the phase assemblage, microstructural evolution in correlation with mechanical and thermomechanical properties were investigated. Presence of Y2O3 facilitated the formation of calcium yttrium silicate and yttrialite phases, which prohibited the formation of detrimental-phase monticellite, which was gradually reduced with the increase in Y2O3 content. Y2O3 promoted periclase grain growth and segregated the secondary phases at triple-point junction of periclase grains. Also, high-temperature (at 1200°C) flexural strength of the samples increased from 77.2 MPa (without Y2O3) to 137.45 MPa with the addition of 2 wt% Y2O3. Greater degree of direct bonding among periclase grains, compact microstructure, and uniform grain size distribution in addition to reduced amount of monticellite were responsible for the improvement in mechanical and thermomechanical properties.

Mechanical activation (MA) is an efficient method to synthesize nano-structured materials. This is the first report of successful synthesis of monticellite-akermanite nanocomposite from talc, calcium carbonate and magnesium carbonate powders. The raw materials were milled for 10 min, 2, 5, 10, and 20 h and then annealed in order to obtain monticellite-akermanite nanocomposite powder. The obtained powder was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated preparation of monticellite-akermanite nanocomposite powder with crystallite sizes about 30.76 ± 0.47 nm after 20 h mechanical alloying and sintering at 1200 °C for 1 h. Absence of enstatite, a phase that causes a reduction in mechanical and bioactivity properties, is an important feature of the prepared powder. The compacted samples of fabricated nanocomposite powder, sintered at 1300 °C for 3 h, exhibit significant improvements in compressive strength (60 ± 1.8 MPa) than single phase monticellite (43 ± 1.1 MPa) and hydroxyapatite (34 ± 1.4 MPa) which make it an appropriate candidate for bone tissue engineering applications.

The new mineral patynite was discovered at the massif of Patyn Mt. (Patynskiy massif), Tashtagolskiy District, Kemerovo (Kemerovskaya) Oblast&rsquo, Southern Siberia, Russia. Patynite forms lamellae up to 1 0.5 cm and is closely intergrown with charoite, tokkoite, diopside, and graphite. Other associated minerals include monticellite, wollastonite, pectolite, calcite, and orthoclase. Patynite is colorless in individual lamellae to white and white-brownish in aggregates. It has vitreous to silky luster, white streaks, brittle tenacity, and stepped fractures. Its density measured by flotation in Clerici solution is 2.70(2) g/cm3, density calculated from the empirical formula is 2.793 g/cm3. The Mohs&rsquo, hardness is 6. Optically, patynite is biaxial (&ndash, ) with &alpha, = 1.568(2), &beta, = 1.580(2), and &gamma, = 1.582(2) (589 nm). The 2V (measured) = 40(10) and 2V (calculated) = 44.1. The Raman and IR spectra shows the absence in the mineral of H2O, OH&ndash, and CO32&ndash, groups and B&ndash, O bonds. The chemical composition is (electron microprobe, wt.%): Na2O 3.68, K2O 5.62, CaO 26.82, SiO2 64.27, total 100.39. The empirical formula based on 23 O apfu is Na1.00K1.00Ca4.02Si8.99O23. Patynite is triclinic, space group P&ndash, 1. The unit-cell parameters are: a = 7.27430(10), b = 10.5516(2), c = 13.9851(3) &Aring, &alpha, = 104.203(2)&deg, &beta, = 104.302(2)&deg, &gamma, = 92.0280(10)&deg, V = 1003.07(3) &Aring, 3, Z = 2. The crystal structure was solved by direct methods and refined to R1 = 0.032. Patynite is an inosilicate with a new type of sextuple branched tubular chain [(Si9O23)10&ndash, ] with an internal channel and [(Si18O46)20&ndash, ] as the repeat unit. The strongest lines of the powder X-ray diffraction pattern [dobs, &Aring, (I, %) (hkl)] are: 3.454 (100) (2-1-1), 3.262 (66) (2-1-2), 3.103 (64) (02-4), 2.801 (21), 1.820 (28) (40-2). Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia with the registration number 5369/1.

A study on sintering of chromite fines was conducted through sintering pot test. The effect of sintering parameters including mix moisture content, coke breeze rate, bentonite dosage and sintering suction was investigated. It was found that conventional sintering process can be applied to the agglomeration of chromite fines as well. Appropriate parameters for chromite fines sintering were 8.0% moisture, 7.0% coke breeze, 2.0% bentonite and 14 kPa sintering suction. Furthermore, the consolidation characteristic of chromite sinter was observed by using a microscope, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). It can be found that the sinter mainly consisted of chromohercynite, forsterite and monticellite. Besides, the element distribution of Fe and Cr in chromohercynite was quite different. Fe mainly distributed on the outer layer while Cr distributed in the inner layer. The chromohercynite formed from liquid phase has higher Fe and Mg content.

Indian magnesites from Salem and Almora regions were selected for the present study. Chemical analysis of these magnesites confirmed that Salem region magnesite (SM) contains CaO and SiO2, whereas Almora origin magnesite (AM) shows higher amount of Fe2O3 and CaO as major impurities. Crystalline phases developed in sintered Salem magnesite are periclase, forsterite and monticellite, while magnesioferrite and monticellite are found in sintered Almora magnesite apart from periclase as major phase. Microstructural analyses reveal that sintered SM has lower grain size than sintered AM . Although, no significant difference was noticed at room temperature flexural strengths of both the sintered samples, but sintered AM samples exhibit better flexural strength at elevated temperature (1200°C).

Sol-gel combustion method was employed for the synthesis of monticellite (CaMgSiO4) ceramic powders using various fuels. Citric acid, succinic acid, tartaric acid, sucrose, urea, glycine, and L-alanine were used as fuels. Influence of calcination temperature on the phase evolution was investigated. Prepared monticellite powders were characterized using powder-XRD, FT-IR, and DLS techniques. XRD pattern reveals that the L-alanine is a suitable fuel among all the fuels studied and confirms the formation of pure monticellite. FT-IR spectra confirm the presence of characteristic functional groups associated with monticellite. DLS measurements show the particle size of the monticellite powders. Finally, Apatite formation ability studies were carried out by immersing the monticellite and monticellite-polymer (chitosan/chitin) composites in the SBF solution. Pure monticellite shows higher bioactivity than the composites and its surface analysis (SEM and EDS) reveals the deposition of spherical hydroxyapatite particles.

In this study, a simple and facile strategy was developed for the synthesis of novel hydroxyapatite (HA)/nanostructured monticellite ceramic composites by mechanical method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS) were used to peruse the phase structure, and morphology of soaked ceramic composites in simulated body fluid (SBF). The in vitro bioactivity of HA-based ceramic composites with nanostructured monticellite ranging from 0 to 50 wt% was evaluated via investigating the formation ability of bone-like calcium phosphates in SBF and the effect of obtained extracts from composites dissolution on osteoblast-like G-292 cell line. Moreover, In vitro cytocompatibility of the HA/monticellite ceramic composites was investigated by MTT, cell growth & adhesion and alkaline phosphatase (ALP) activity assays, and quantitative real-time PCR analysis. The results showed that HA/nanostructured monticellite ceramic composites could induce apatite formation in SBF. The cell proliferation and growth exposed to ceramic composites extracts were significantly stimulated and promoted at a certain concentration range compared to control for various time periods of cell culture. The optimized composite extract enhanced considerably gene expression of G-292 type X collagen (COLX) at different days. Also, G-292 cells were spread and adhered well on the ceramic composite disc. Furthermore, ALP activity of G-292 cells exposed to ceramic composites extracts was dramatically enhanced in comparison with pure HA extract (as control) at different concentrations for various time periods of cell culture. The results suggest that the optimized HA/nanostructured monticellite composite is promising biomaterial for clinical applications such as orthopedic and dentistry.

In this research, novel monticellite/hydroxyapatite (HA) ceramic composites were successfully prepared by mechanical method. The ability of nanostructured monticellite-based ceramic composites to form a suitable bond to living hard tissues, and stimulate osteoblast-like cells proliferation may be different for various ratios of the reinforcement to monticellite matrix. The differences in physico-chemical characteristics, bone-like apatite formation, cytocompatibility, cell viability and in vitro osteogenic activity of nanostructured monticellite/HA ceramic composites were explored. The surface reactivity and bioactivity of the composite samples were evaluated in vitro in simulated body fluid (SBF). A comparative time- and dose-dependent MTT test showed that the ions release from nanostructured monticellite/HA composites dissolution significantly stimulated cell proliferation and growth than control at a certain concentration range. The cells viability exposed to the composite extract was higher than control and mineral material of bone (HA), illustrating that cytocompatibility was improved due to the presence of magnesium (Mg) and silicon (Si) elements in the composite structure. The comparative results of alkaline phosphatase (ALP) bioactivity assay showed that the osteogenic proliferation of osteoblast-like G292 cell was increased more by the ceramic composites extract than control. These comparative results demonstrated that nanostructured monticellite-based ceramic composites possessed good in vitro bioactivity, cytocompatibility and osteogenic properties, and may be utilized as the promising bioactive materials for bone tissue regeneration and replacement.

Corrosion mechanisms between high melting synthetic ferronickel slags and refractory were investigated. The used slags were prepared by mixing and melting of specific oxides. Substrates of the applied refractory material and specimens of FeNi slags were heated in a hot stage microscope up to 1650 °C. The experiments were performed under a defined gas atmosphere of 60% CO and 40% CO2. A further examination of the formed phases between slag and refractory occurred by scanning electron microscope. The investigations indicate that the slag penetrates between magnesia grains and partly dissolves magnesia. Spot analyses show that iron diffuses into the magnesia grains, which transform to magnesiawustite, meanwhile SiO2 forms different types of olivine like forsterite and monticellite. Thermodynamic calculations confirm the formation of these phases. The combination of practical lab scale experiments and thermodynamic calculations should finally contribute to an improvement of the refractory lifetime and performance.

Indian magnesite mineral has substantial amount of impurities like CaO, SiO2 & Fe2O3. During sintering at elevated temperature these impurities react to form low melting phases like monticellite (CMS), which can degrade the high temperature properties of magnesite. In the present study, ZrO2 was added to reduce the formation of low melting phase in order to improve the hot strength. Amount of additive was varied between 2 and 6 wt.% with respect to raw magnesite. It was observed that addition of ZrO2 reduces the formation of low melting CMS at higher temperature and improves the flexural strength at 1200 °C. Periclase grain shape also changed from rounded to subrounded in the presence of zirconia.

The use of metallurgical slags in cement production depends on the phases present in such slags, which are affected by changes in slag composition as well as the cooling rates adopted during solidification. In this work, slags with distinct chemical compositions were melted and subjected to different cooling conditions. Slag samples were characterized by X-ray diffraction to identify and quantify mineralogical phases and by X-ray fluorescence to determine chemical composition. The microstructure of the samples was characterized by scanning electron microscopy coupled to energy dispersive spectroscopy for phase identification. The solidification of the slags was simulated using FactSage™ for solidification path evaluation, enabling a comparison of the phases determined by thermodynamic equilibrium with those analysed in slag samples. Slags with low basicity (CaO/SiO2

A Ghassoul clay from Morocco was studied regarding the effect of (1) grinding and (2) selection of the particle size distribution (classification) on the thermal transformations during sintering. Ghassoul clay contains stevensite, dolomite and quartz as major minerals. Prior to the classification, the starting coarse aggregates of the raw clay were first dry-ground below 500 μm and the obtained particles of powder were then granulated in order to produce adequate pellets for shaping by uniaxial pressing. Classification was performed to obtain three grain size distributions, namely greater than 500 μm, between 500 and 315 μm and lower than 315 μm. As the grain size distribution became finer, the proportion of carbonate phases was increased. DTA–TG analyses were in agreement with this trend, and in addition, dilatometry analyses showed that the densification was shifted to lower temperatures when decreasing the size of granules. The major phases occurring after sintering at 1200 °C were diopside, enstatite and forsterite as expected from the equilibrium phase diagram. Moreover, the smaller clay fraction (typically lower than 40 μm) enhanced the formation of melilite and monticellite. Nevertheless, a swelling occurred during sintering that balanced the densification shrinkage. According to these results, the sintering of Ghassoul clay proceeds through several stages regardless of the particle size selection. With a mean size of granules lower than 315 μm, the densification can be achieved at 1100 °C, while for greater sizes, a similar densification state of the raw material requires a significantly higher temperature of sintering of 1200 °C. In addition, some dedensification drawbacks may occur when using granules whose size is greater than 315 μm and therefore could induce unexpectedly a significant damage to materials. The observed trends may be useful for further applications of such Ghassoul clay in the silicate ceramics field.

Natural Indian magnesite contains large amount of impurities like CaO, SiO2 and Fe2O3. On heat treatment, these impurities chemically react and form low melting phases like monticellite (CMS), merwinite (C3MS2) and vitreous phases, which degrade the refractory properties of magnesite like hot modulus of rupture, corrosion resistance etc. In the present investigation, TiO2 was used to reduce the formation of low melting phases. Compacted green pellets and bars of magnesite containing 0−5 wt% TiO2 were sintered in the temperature range of 1500−1600 °C with 2 h soaking at peak temperature. It was observed that TiO2 slightly increased the apparent porosity and decreased the bulk density by reducing the formation of low melting phases. High temperature flexural strength increases with TiO2 content upto 3 wt% followed by slight decrease in strength after further increase in the amount of additive.

Roman slag from the archaeological site near Mosnje (NW Slovenia) was studied with respect to its mineralogical and geochemical characteristics. Samples were analysed with light microscopy, X-ray powder diffraction (XRD), scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS) and Raman microspectroscopy. A chemical investigation was carried out using inductively coupled plasma-atomic emission spectroscopy (ICP-ES) to determine the major elements. The investigated slags are recognized as iron slags, grouped into two main classes according to their chemical and mineralogical compositions. The first group is characterized by high Fe2O3 and low SiO2 contents and the second by high CaO and SiO2 and low Fe2O3 contents. The phase occurrence obviously depends on the chemical composition as the first group mainly consists of fayalite, wustite and magnetite, and the second one of augite, leucite, hedenbergite, monticellite and kirschsteinite.

Use in ceramic mixes of aluminum-containing waste containing more than 50% Al2O3 facilitates formation of α-Al2O3 and mullite, which improves object physicomechanical and chemical properties. Use of aluminum-containing waste containing less than 30% Al2O3 does not facilitate formation of α-Al2O3 but promotes mullite formation. Cristobalite does not form with use of aluminum-containing waste with an increased amount of alkali (R 2O > 11%), and this has an unfavorable effect on ceramic composite material physicomechanical indices.

WOS: 000413124300081, Monticellite bioactive ceramics have a high usage potential as bone graft substitutes due to their superior mechanical properties compared to hydroxyapatite and excellent bioactivity. Turkey has almost 72% of the global boron reserves and the fairly high amount of emerged boron derivative waste causes storage problems and environmental pollutions. The aim of this study was the solid state synthesis of monticellite based ceramic powders from boron derivative waste and the evaluation of bioactivity characteristic of produced powders. The monticellite based ceramic powders were synthesized at low temperature (800 degrees C). The powders were incubated in Simulated Body Fluid and their surfaces were examined using a scanning electron microscope. The surfaces of synthesized powders were bioactive and allowed formation of bone-like apatite layer within 15 days. Results of the study confirmed that cost-effective and ecofriendly monticellite based bioactive ceramic powders can be synthesized from boron derivative waste

This work aims at studying rate of densification, resistance to hydration and slag attack of 0.0–2.0 wt.% ilmenite-doped MgO-dolomite refractories fired at 1400–1700 °C, in relation to their thermal equilibrium and microfabric. XRF, XRD, SEM, EDAX and mercury intrusion were used to characterize the fired samples. The modular system MgO-MF(MA)-C2S-M2S was applied in determining their thermal equilibrium data. The rate of hydration and attack by steel-slag were also measured using CLM. It is concluded that doping the dolomitic-magnesite with 0.5 wt.% ilmenite leads to maximize rate of densification after firing for 4 h at only 1500 °C. Direct-bonded MgO-MgO network is shown enclosing merwinite and monticellite with minor magnesio-ferrite spinel solid solution ex-soluted within the periclase network. Due to the dense microfabric, the hydration resistance is enhanced 8 times compared with the un-doped samples. Also, there is deeper infiltration of the slag/refractory reaction products of the un-doped MgO-dolomite sample as compared with the doped one.

Thermal transformations of talc-carbonate rocks consisting of talc, chlorite, mica/illite, quartz, feldspar and calcite were investigated in the range of 900°-1100°C by X-ray diffraction, thermal analyses, scanning electron microscopy and energy dispersive spectroscopy. Microstructural changes of heated decarbonated samples were also investigated, and variations of some ceramic properties against temperature were followed. In the heated raw samples, olivine and enstatite together with merwinite were formed at T 1000°C, akermanite and monticellite were developed from talc, and shrinkage was almost unchanged. Heating of decarbonated samples yielded olivine and enstatite together with Mg-spinel on the expense of talc. In this case, a vitreous phase was also formed and shrinkage got increased. The neoformation processes in both the samples were discussed based on the SiO2-MgO-CaO and SiO2-Al2O3-MgO phase diagrams. Considering the magnitudes of the studied ceramic proper...

Chemical and mineralogical characteristics and physicomechanical properties are provided for mullite-silica refractory MKRA-50 before and after service in a steel-pouring ladle. Questions of metal secondary oxidation present within a lining are considered. A mechanism of sub-compound and gaseous complex formation in steel is discovered and their effect on phase formation in a ladle lining is demonstrated. Thermochemical methods are considered for the preferred choice of refractory materials based on corundum and magnesium oxide.

This study concerns the chemical reactions involved and the phases formed during penetration of slags of variable compositions into porous tundish disposable lining material. The liner is mainly composed of a mixture of MgO and olivine with an organic binder. Slags of different compositions were formulated and indicated a variable composition of CaO (12–20%), SiO2 (44–55%), Al2O3 (4–16%), MgO (10–20%), MnO (9–12%) and FeO (2–3%). Experimental work indicated that when slag penetrated into pores of the refractory, the porosity was reduced depending on the penetration depth. It was observed that the lower the melting point of the slag, the higher the depth of slag penetration by capillary action. The phases of forsterite (Mg2SiO4), magnesiowustite (MgO.FeO) and monticellite (CaO.MgO.SiO2) were formed in the bulk refractory by the slag, and the chief component of the refractory responsible for the formation of those phases is the periclase.