Characterization of Minerals, Metals, and Materials 2023

LunarLunar and MartianMartian meteorites are rare rocks found on Earth and classified by meteoritical experts depending on their physical and chemicalChemical features. Three different types of certified lunarLunar rock samples and one MartianMartian rock sample were tested and scanned by a scanning electron microscope (SEMScanning electronic microscope (SEM)) to obtain the chemicalChemical composition, explore the elemental mapping, and provide a statistical comparison between the different types. The SEMScanning electronic microscope (SEM) was able by EDS detector to provide accurate chemicalChemical compositions, in addition to microstructure images and elements mapping. The data provided by SEMScanning electronic microscope (SEM) were treated statistically by the principal component analysis (PCAPrincipal component analysis (PCA)) technique to obtain the relation between the elements and obtain a statistical model to help in differentiating similar rocks in the future.

Numerical simulation was used to study the magneto-Joule heating effect of molten mold fluxMolten mold fluxes under a low-frequency electromagnetic fieldLow-frequency electromagnetic field in continuous castingContinuous casting. The effects of electromagnetic field parameters on the conductivity of molten mold fluxMolten mold fluxes were also investigated. The results showed that the induced current and magnetic induction in molten mold fluxMolten mold fluxes increased with its increasing conductivity and excitation current, and the magneto-induced Joule heatJoule heat also increased. The magneto-Joule heatJoule heat was found around 0.97 × 103 to 6.29 × 103 J m−3. For every 10 mm decrease from the magnetic field action center, the Joule heatJoule heat of molten mold fluxMolten mold fluxes increased 11.8% on average. A greater conductivity of the mold flux resulted in a more significant change in Joule heatJoule heat.

In the past three decades, the focused ion beamFocused ion beam (FIB) microscope has evolved from a semiconductor production tool into an advanced microstructure characterizationCharacterization instrument. The FIBFocused ion beam (FIB) microscopes have changed from the first generation of single ion beam systems to multi-beam systems that often couple with various types of analytical instruments. However, the powerful FIBFocused ion beam (FIB) systems are often recognized as advanced TEM specimen preparation machines due to their superior capability of making high quality, site-specific thin foils from almost any types of materials and any geometry. This is a vast under usage of such powerful systems. Most users do not take advantage of the primary ion beam imaging capability that can provide high-quality images to reveal important microstructure features. In this paper, the author uses practical examples to demonstrate the power of ion beam imaging.

Zinc oxideZinc Oxide (ZnO) is a very important material with diverse uses in solar cells, optoelectronic devices, and other applications. Optimizing the optical properties is required in such applications. In this work the influence of annealing in nitrogen atmosphereAtmosphere and aluminum doping on the optical properties was investigated. Undoped (ZnO) and aluminum doped (ZnO:Al) thin films were deposited using spray pyrolysisSpray Pyrolysis (SP) method on glass substrates, and some of these films were annealed in nitrogen atmosphereAtmosphere. The microstructure of the films was explored using X-ray diffraction, and it is found that the films are polycrystalline. Transmittance of the films was recorded as a function of wavelength in the range of 300–1100 nm. Transmittance was used to calculate the absorption coefficient, extinction coefficient, reflectance, refractive index, real and imaginary parts of the dielectric constant, and optical conductivity. All these parameters are found to be affected by Al-doping and annealing. It is found that optical parameters were influenced by Al-doping and annealing.

During the solidification process, interdendritic liquid flowInterdendritic liquid flow at the millimeter scale in the mushy zone can finally result in the macro/semi-macro segregationSegregation. In this paper, a new method (abbreviated as MSS) for the three-dimensional structure morphologyMorphology of different dendrites at the millimeter scale was proposed based on the serial-sectioningSerial-sectioning and hot pickling experiments, which allows interdendritic liquid flowInterdendritic liquid flow behavior in opaque steel billets to be analyzed. By using the three-dimensional computational fluid dynamicsDynamic simulation of interdendritic liquid flowInterdendritic liquid flow, it’s found that the fractal dimension is smaller and the permeabilityPermeability is larger in the equiaxed crystal zone than that of the columnar crystal zone, leading to larger liquid flow velocity and smaller pressure loss in the equiaxed dendrites zone. The above results indicate that the liquid flow resistance in the equiaxed crystal zone is less, thus is more likely to lead to the formation of macro/semi-macro segregationSegregation.

This study examines the mechanical response and microstructural evolution of modern manufactured high carbon pattern welded Damascus steels. The characterisation consists of quasi-static and dynamicDynamic compression testing, optical microscopy, ultrasonic sound speed measurements, and Vickers hardness. The results from the quasi-static compression testing at a strain rate of 10–3/s show that the yield strength of the materials is approximately 500 MPa, which is comparable to that of plain carbon steel (~450 MPa) and display similar strain hardening properties. The compression results also display a slightly higher Young’s Modulus for samples with layer orientation perpendicular to the uniaxial load than those with layer orientation of approximately 45° to the uniaxial load. DynamicDynamic testing using a Split-Hopkinson Bar results showed a similar yield strength of ~ 1150 MPa for the samples with 45° layer orientation, whereas samples with perpendicular orientation showed a slight increase in the yield stress with increasing the strain rate.

Split-Hopkinson Pressure Bars (SHPB) or “Kolsky” bars are often employed for determining the high-rate compressive failure strength of high-strength brittle materials. However, experiments generating very high strain-ratesHigh strain-rate demand miniaturization of the setup for appropriately measuring decreasingly short loading events. Miniature aluminum and steel bars are often sufficient for this. However, for high enough strain-rates, miniaturization of these bars may require prohibitively small test specimens that can be inappropriate for inferring representative properties of materials with large grain size relative to the specimen size. The low Poisson’s ratio of beryllium relative to aluminum and steel is expected to minimize the effect of elastic wave dispersionDispersion on the measurable strain-rates in Kolsky barKolsky Bar experiments. For these reasons, we have developed a Be Kolsky barKolsky Bar apparatus, and, in this paper, we experimentally determine the dispersionDispersion characteristics of these bars and compare the results with those of similarly size setups made from aluminum and steel. The results show no appreciable dispersionDispersion in the data from the beryllium Kolsky barKolsky Bar setup, demonstrating its advantage over aluminum and steel.

The part quality that can be achieved in forming and stamping processes strongly depends on the properties of the sheet metal material to be processed. However, since these material properties may fluctuate considerably and thus lead to the production of scrap, it is important to monitor such material fluctuations during part production. For this, the ongoing digitization of production processes provides new possibilities for part or quality monitoring. In this context, a novel AI-based method for the direct determination of material parameters from punching forcePunching force curves measured in production was presented in a past study by the authors. This paper deals with the investigation of three further methods for extracting features from these recorded measuring data. In addition to domain knowledge-based feature engineering, statistical feature extraction (PCAPrincipal component analysis (PCA)) as well as a derivative-based method are analyzed and compared with each other and with the previously used AI (ANN) regarding their prediction accuracy of sheet metal properties.

Additive manufacturingAdditive Manufacturing (3D Printing) has made tremendous progress in the past two decades and the success of continuous fiber fabrication (CFR) technology has made it conceivable to print continuous carbon fiber reinforced compositesComposite. In this paper, the tensile strengthTensile Strength, Young’s modulus, flexure strengthFlexure Strength, and flexural modulus of 3D printed continuous carbon fiber reinforced compositesComposite were investigated using test specimens based on the standards ASTM D3039/D3039M and ASTM D790, respectively. A proportional increase in tensile strengthTensile Strength, Young’s modulus, flexural strength, and flexural modulus were measured with increasing carbon fiber volume fractionsCarbon Fiber Volume Fraction for a given fiber orientation. The test results indicate that except for the flexure strengthFlexure Strength of the highest (0.767) volume fraction fiber compositesComposite, the other measured values are much lower and are about half the values listed in the given datasheet.

During copper extraction from copper concentrate, the slime generated in a copper electrorefining tank contains many valuable elements like Cu, Ni, Se, Te, Au, Ag, Pt, Pd, Bi, Sb, along with As, Pb, Fe, Ba, etc. The conventional process for the treatment of the slime includes initial copper extraction by sulphuric acid leachingLeaching and extraction of tellurium by the cementation process. After copper and most of the tellurium extraction, the residue is treated for selenium recovery. The slime after selenium extraction is called deselenized slimeDeselenized slime, mainly containing Au, Ag, Pt, Pd, Pb, As, Te, Bi, Sb, and Ba. The complex nature of the deselenized slimeDeselenized slime makes further processing of the slime more complicated. This paper illustrates the detailed characterizationCharacterization, including physical, chemicalChemical, and mineralogical studies of the deselenized anode slimeAnode slime that can provide valuable information, including the morphologyMorphology, which can help in process development for further metals recovery from the slime.

Transformation of desulfurizationDesulfurization performance of activated carbonActivated carbon during multiple cycles of adsorption and regeneration was investigated and the causes were analysed. Results showed that the desulphurization performance of activated carbonActivated carbon descended gradually with cycle times of adsorption and regeneration increasing. The properties of activated carbonActivated carbon were characterized by using XRD, XPS, TGA, and FT-IR. Results showed that the acidic functional groupsAcidic functional group contents on activated carbonActivated carbon surface increased with multiple cycles, which would affect its desulfurizationDesulfurization performance. Besides, the content of calcium sulfateCalcium sulfate in activated carbonActivated carbon increased with multiple cycles, which would be another reason for that. Furtherly, the formation process of calcium sulfateCalcium sulfate was analysed.

In this study, we determined the influence of different TiO2TiO2 contents in high-alumina slag under a neutral atmosphereAtmosphere, N2 atmosphereAtmosphere (without carbon), and reductive atmosphereAtmosphere on blast furnace (BF) slag considering the phase changes, viscosityViscosity, meltingMelting temperatureTemperature, and slag structure. The results show that the viscosityViscosity and meltingMelting temperatureTemperature of the slag first increase and then decrease in a neutral atmosphereAtmosphere, and the turning point is 5wt%. The slag structure is somewhat complex and then simple. Under an N2 atmosphereAtmosphere (without carbon), slag viscosityViscosity and meltingMelting temperatureTemperature decrease first and then increase, and the turning point is 10wt%. This is because when the TiO2TiO2 content reaches10wt%, the slag begins to appear high meltingMelting point phase (TiN). The structure of slag tends to be complicated under a reducing atmosphereAtmosphere. The high meltingMelting point phases Ti (C, N) and TiN appear, which makes the slag viscosityViscosity and meltingMelting property.

The solidification behavior of slag plays a vital role in its recycling. In this study, Confocal Laser Scanning Microscope (CLSM) experiments were performed under various oxygen partial pressure (pO2)Oxygen partial pressure (pO2) for FeO-SiO2-Al2O3-CaO slags with around 4 wt.% and 26 wt% CaO to study their meltingMelting and solidification behaviors. Samples after the CLSM tests were analyzed by EPMA. Analysis indicated that the start meltingMelting temperatureTemperature of the high CaO slag decreased with decreasing pO2Oxygen partial pressure (pO2) from 10–4 atm to 10–12 atm, and the CaO concentration in the slag had a significant influence on its solidification behavior at pO2Oxygen partial pressure (pO2) of 10–8 atm. Under pO2Oxygen partial pressure (pO2) of 10–8 atm with a cooling rate over 1 °C/s, wustite crystal precipitated in the CaO-rich slag at temperaturesTemperature over 1200 °C, while spinel precipitated in the low CaO slag at temperaturesTemperature between 1100 and 1250 °C. When the cooling rate was below 1 °C/s, the spinel precipitated firstly at temperaturesTemperature over 1277 °C in both slag systems. In addition, other mineralsMineral, such as melilite and fayalite, were observed, respectively, in the CaO-rich slag and low CaO slag.

Given the deficiencies of the present test methods of mold powderMold powder meltingMelting rate, a method based on the copper bath was established in this study. The correctness and reproducibility of this method were verified. The relative standard error was less than 5%. The effect of carbonaceous materialsCarbonaceous materials and powder granule sizeGranule size on the meltingMelting rate was investigated by this method. The results show that: (1) The meltingMelting rate of mold powderMold powder decreased with increasing carbonaceous materialsCarbonaceous materials content. (2) Besides carbonaceous materialsCarbonaceous materials, the powder granule sizeGranule size also affected the meltingMelting rate. The meltingMelting rate of the mold powderMold powder for high-nitrogen stainless steel increased with increasing granule powder size. The use of powders in the steel plant was consistent with the experimental results. The larger the proportion of larger than 0.5 mm granules in the powder, the thicker the liquid slag layer, and the higher the qualified rate of slab quality.

Samples of Corn cob (Sammaz 40) was collected, beneficiated and pulverized into 10 mm particle size, carbonized at 400 °C for 3 h and activated at 600 °C for 6 h in a furnace, using the approximation method, Sodium-aluminosilicate based glass batch was designed. Adopting the petrurgic method, 5% of the designed batch was melted at 1200 °C for 5 h, cooled to room temperatureTemperature at 1 °C and 5 °C respectively for every 60 s and a crystallized glass was formed. The glass was analyzed using Scanning Electron Microscopy (ASTM E-986), X-ray diffraction (ASTM E-975) and compressive strength evaluation (ASTM C-773). The results showed the presence of an amorphous and a crystalline phase within a ratio of 70:30 range, sharp Bragg's peak zone near 2θ = 27 °C indicates Nepheline (NaAlSiO4) crystalline phase and a compressive strengthCompressive strength ranging between 11,000–12000psi which implies that crystalline glassCrystalline Glass developed from agro-wasteWaste (Corn cob) is advantageous in areas where strength is of high essence.

The influence of the Cr2O3Cr2O3 content on the surface tensionSurface tension of CaO–SiO2–9.25 wt.%MgO–14.7wt.%Al2O3–22wt.%TiO2TiO2–Cr2O3Cr2O3 slag system was investigated in the temperatureTemperature range of 1450–1550 °C using the ring method. The mechanism of the changes in surface tensionSurface tension with different Cr2O3Cr2O3 content in slag was analyzed from the perspective of the model and ion theory in the melts. Increasing the Cr2O3Cr2O3 content from 0 to 3 wt.% caused an increase in the surface tensionSurface tension for the reason that the surface tensionSurface tension of Cr2O3Cr2O3 is the largest and that of SiO2 is the smallest in the components of the slag. Another reason is that the anions are repelled to the surface layer of the slag and adsorbed. The surface tensionSurface tension decreased with increasing temperatureTemperature. This is because of the decrease of interaction forceInteraction force between the ions and the reduction of the bulk phase density between the two phases adjacent to the surface layer.

In this paper, five kinds of calcium-containing fluxesCalcium-containing fluxes (calcium-containing flux A, calcium-containing flux B, calcium-containing flux C, calcium-containing flux D, and calcium-containing flux E) were selected to improve the basicity of pellets, at the same time, their physicochemicalPhysicochemical properties and microstructure were analyzed and compared. A new production process and technical route of using calcium-containing flux C to produce fluxed pelletsFluxed Pellets were proposed, which has been well applied in Shougang Jingtang Company. The fluxed pelletsFluxed Pellets possessed good quality with basicity at 1.1, SiO2 at 2.1%, and reduction swelling indexReduction swelling index at 16.5%. A good application effect was demonstrated that the pellet ratio in the charge of Shougang Jingtang Company increased from 28 to 55%, while the blast furnace slag reduced from 280 to 215 kg/tHM, and the fuel rate is reduced from 500 to 483 kg/tHM.

The study primarily focuses on the characterizationCharacterization and physicochemicalPhysicochemical investigations of columbite samples from Rayfield-JosRayfield-Jos, Plateau state, Nigeria. Samples were prepared and characterized by particle size, microstructural, physical and chemicalChemical analyses. Further, density/specific gravity, pH, moisture content and water absorption were determined. ChemicalChemical analyses showed reasonable compositions of Nb/Ta penta-oxides with certain degree of impurities/gangue mineralsMineral including radioactive materials. Results of analyses conducted strongly depict the columbite deposit as a somewhat promising mineralMineral source of Nb and Ta but however of low-grade, and with the potential in developing appropriate, (cost) effective beneficiationBeneficiation routes for the metal(s) recovery. Thus, the study will create baseline information on choice selection as well as designing suitable, feasible extraction process routes/techniques to efficiently harness the refractory metals and other value metals from the study area. This will also serve as a tool in the advancement of mineralMineral upgrade/beneficiationBeneficiation routes prior to hydrometallurgical and thermal treatments.

PorosityPorosity in copper filters is sensitive to powder type and space holder material in addition to fabrication processing conditions. This study is focused on the use of two different copper powderCopper powder types (spherical and dendritic) to produce air flow filtersAir flow filtration. The hydraulic pressing method was used to produce copper filters under varying pressure with different spacer (polyvinyl alcohol (PVA)) concentrations. Following compaction, the samples were thermally sintered in two segments at 200 °C and 750 °C. The morphologyMorphology, porosityPorosity, and mechanical propertiesMechanical properties of the sintered samples were characterized. The morphological analysis demonstrated better consolidation and overlapping of copper powderCopper powder particles in samples with a higher weight percentage of the spacer material (PVA). The highest porosityPorosity was achieved in the sample produced using dendritic copper powderCopper powder mixed with the highest weight percentage of PVA (3%). As a porous structurePorous structure, the (Vickers) hardness of the samples greatly varied within the samples. Samples prepared with spherical powders at comparatively high pressures demonstrated the highest hardness. The results achieved in this study demonstrated that copper filters with 14% to 26% porosityPorosity can be produced using spherical and dendritic copper powdersCopper powder by controlling the compaction pressure from 635 to 793 MPa.

The conversion of ferronickel slagFerronickel slag (FS) to thermal insulation materialsThermal insulation materials by microwave sinteringMicrowave sintering in the presence of different additions of fly ash cenosphereFly ash cenosphere (FAC) was studied. The results showed that adding proper amount of FAC could promote the generation of cordierite with low thermal conductivity during the sintering process, while the hollow spherical FAC facilitated the pore development and reduced the bulk density of thermal insulation materialsThermal insulation materials. The thermal conductivity, bulk density, compressive strengthCompressive strength, water absorption and linear shrinkage of the thermal insulation materialThermal insulation materials were 0.328 W/(m·K), 1.45 g/cm3, 27.09 MPa, 23.48% and 7.74%, respectively, under the conditions of the mass ratio of FAC to FS of 1/3, sintering temperatureTemperature of 890 °C, and sintering time of 20 min. This study represents a good example of clean and efficient value-added utilization of FS and other solid wastesWaste.

The use of Portland cementCements occurs on a large scale in civil constructionConstruction. However, its use causes a great environmental impact by emitting a high level of carbon dioxide in the atmosphereAtmosphere. An eco-friendly alternative is the development of alkali activated materialsAlkali activated materials (AAM), as it is not necessary to calcine the precursor materials for use and because they have a high gain of initial mechanical strength. Furthermore, it is possible to value industrial wastesWaste rich in silica and alumina in the compositions of AAM such as ceramic wasteCeramic waste (CW), in addition to making use of reactive materials such as metakaolinMetakaolin (MK). This work shows the results achieved in microstructural and compressive strengthCompressive strength tests. The aim was to optimize the dosage in pastesPaste with different compositions between precursor materials and activator solution. Research results indicate the effectiveness of replacing 30% MK with CW when compared to a pastePaste composed of 100% MK.

Natural fibersNatural fibers are renewableRenewable materials with high potential for reuse, being a possibility with low environmental impact for application in numerous environmentsEnvironment. PineapplePineapple and coconut are fruits consumed and produced in several countries. The peels of both fruits and the leaves of the pineapplePineapple crown are normally discarded by industries, generating wasteWaste, and negatively impacting the environmentEnvironment. The present work seeks to discuss about cementitious mortarsMortar made from these fibers and their effects, in which pineapplePineapple crown leaf fiberPineapple leaf fiber and coconut fiberCoconut Fiber were used in the proportions of 1.5% and 3.0% and mortarMortar of reference, in this way, its characteristics were analyzed and compared through tests of consistencyConsistency, viscosityViscosity, compressive and flexural strength, density and capillarity absorption. The results showed the feasibility of using natural fibersNatural fibers in cementCements mortarMortar, making it more sustainable.

Activated alkali materialsActivated alkali materials (AAMs) have been increasingly studied as a substitute for Portland cementCements, one of the most used materials in civil constructionConstruction, which, during its manufacture, emits a large amount of carbon dioxide, one of the most harmful gases to the environmentEnvironment and responsible for the global warming. Activated alkali materialsActivated alkali materials originate from one or more precursors, containing mainly alumina and silica, in addition to an activator with a high alkaline content. This work aims to analyze the properties in the fresh state of three pastesPaste of AAMs with different proportions of metakaolinMetakaolin (MK) and flue gas desulfurization wasteFlue gas desulfurization waste (FGDFlue gas desulfurization (FGD)). The proportions are 100% MK, 90% MK, and 10% FGDFlue gas desulfurization (FGD), and 80% MK and 20% FGDFlue gas desulfurization (FGD). For each dosage, consistencyConsistency index tests, viscosityViscosity tests, and mass density in the fresh state will be carried out. The research results show that as the FGDFlue gas desulfurization (FGD) content is increased, there is a reduction in the workability of the material. However, the specific mass decreased with the addition of the wasteWaste.

Alkali activated materialsAlkali activated materials (AAMs) have been studied as an alternative to replace the high demand for common ordinary Portland cementCements (OPC) in civil constructionConstruction, with the use of industrial by-products in order to reduce and recycle wasteWaste instead of disposal in landfills. The aim of the research is to analyze the properties in the hardened state of an alkali activated pastePaste of metakaolinMetakaolin (MK) and residue from flue gas desulfurization (FGDFlue gas desulfurization (FGD)). Samples of AAMs, with dosages of 100% MK and 0% FGDFlue gas desulfurization (FGD), 90% MK and 10% FGDFlue gas desulfurization (FGD), and 80% MK and 20% FGDFlue gas desulfurization (FGD), were produced with a thermal cure of 6 days at 65 °C in the oven. Subsequently, the specimens were submitted to compressive strengthCompressive strength tests, apparent density in the hardened state, water absorption, and void ratio at 7 and 28 days.

The cementCements industry is a protagonist in the current economy; however, it does not act in an environmentally sustainable way, given its high CO2 emission. In this study, preparing geopolymerGeopolymer compositesComposite with the natural fiberNatural fibers reinforcement appears to be a promising solution. The geopolymerGeopolymer is generally made with sources of aluminosilicates and an alkaline activator solution. There are various natural fibersNatural fibers that can be applied as reinforcement; this work aims to elucidate the use of fibers present in the pineapplePineapple crown. The fibers were treated in a 5% solution of NaOH; after the treatment, they were characterized by XRD and SEMScanning electronic microscope (SEM) and then added in a geopolymerGeopolymer matrix in the proportions of 1.6% and 3.2%, on the metakaolinMetakaolin mass, in addition to the production of reference samples. The mechanical propertiesMechanical properties of the compositesComposite were positively evaluated through flexural strength tests.

The wasteWaste generated by the agroindustry has been highlighted through reuse in the constructionConstruction sector, including açaíAçaí fibers. Natural fibersNatural fibers have been used in the production of alternative materials, such as cementCements-based compositesComposite. The objective of this work was to characterize the açaíAçaí fibers and evaluate the choice of the adequate chemicalChemical treatment to improve the fiber-matrix adhesion in view of its application in mortarsMortar. ChemicalChemical treatments (sodium hydroxide NaOH, calcium hydroxide CaOH2) were performed for 60 min and technological tests for chemicalChemical (X-ray diffraction XRD, energy dispersive X-ray analysis EDX) and morphological (scanning electron microscopy (SEMScanning electronic microscope (SEM))) characterizationCharacterization of the raw and treated fibers. The results showed that the fibers have an irregular shape and lignin and hemicellulose networks on their surface and a higher presence of silica. As for the fiber treatment, NaOH was the most important, which promoted the removal of most of the amorphous constituents such as hemicellulose, lignin, and waxes of the fibers, also causing an increase in their roughness.

Artificial stoneArtificial stone is a material made of stone aggregates and other mineralsMineral agglomerated by a polymeric resinResin. However, aiming at both sustainabilitySustainability and economy, several studies have produced artificial stonesArtificial stone with industrial wastesWaste to reduce the product’s final cost and help the environmentEnvironment. Brasil is a big steel producer, generating a lot of wasteWaste. The main steel industry wastesWaste are blast furnace dust, sludge, slag, and scale. Blast furnace dust wasteWaste is mainly composed of metallic oxides and carbonaceous materialsCarbonaceous materials. This work aims at producing artificial stonesArtificial stone with high-purity material (pure quartz) and comparing it with artificial stonesArtificial stone with 17% steel industry wasteWaste, in order to analyze the physical, mechanical, and chemicalChemical properties. Both stones presented good performance, but the results showed that the stone with residue had superior properties compared to the one with only pure quartz.

High-grade goldGold ores are generally associated with iron, copper, and silverSilver sulfides, among other species that during dissolution consume the leachingLeaching agent, causing a decrease in the leachingLeaching rate. In this work, the flotationFlotation, and the comparison of the leachingLeaching with cyanideCyanide and thioureaThiourea (TU) of an ore rich in Au, Ag, and Cu were studied. The flotationFlotation was carried out with 100 and 200 mesh particles at pH 6.53, and Eh of 253 mV, and frother MIBC and xanthate 60 and 100 mg/l, respectively. The concentrate was leached with 0.2 M thioureaThiourea at pH 1.5 and separately with 2000 PPM-free cyanideCyanide at pH 11.1. In the system containing cyanideCyanide, 19.7%, 22.8%, and 15.4% of Au, Ag, and Cu of recovery were obtained, respectively, while in the system with only TU 14.36%, 15.75%, and 10.75% extraction.

The microstructure changes of pyrolytic CaO-containing carbon pelletsCaO-containing carbon pellets (CCCP) directly determine their ability to produce calcium carbide (CaC2) in an electric arc furnace. Therefore, the microstructure changes, especially the pore structure changes of CCCP at different pyrolysis temperaturesTemperature were characterized by industrial CTIndustrial CT, mercury intrusion porosimetryMercury intrusion porosimetry (MIP), and SEMScanning electronic microscope (SEM) from different scales. The reactivity of carbon in pyrolytic CCCP was tested. The relationship between pore structure change and carbon reactivityCarbon reactivity was established. The results showed that industrial CTIndustrial CT could show the overall pore distribution of CCCP in a three-dimensional way; MIP was more accurate for the statistics of the proportion of pores with different pore diameters, and SEMScanning electronic microscope (SEM) was more intuitive for the local microstructure analysis of CCCP. As temperatureTemperature increased from 450 to 750 °C, the porosityPorosity and average pore diameter of CCCP increased, and decreased over 750 °C. Meanwhile, the reactivity of carbon in CCCPCaO-containing carbon pellets pyrolyzed at 850 °C was the highest.

For several decades, attempts have been made to replace cyanideCyanide with the reagent thioureaThiourea (TU) to reduce the impact on the environmentEnvironment; however, cyanideCyanide continues to be the reagent most used industrially, and this is partly due to the higher consumption of TU during leachingLeaching. Nevertheless, the use of thioureaThiourea could be justified for the leachingLeaching of goldGold and silverSilver from high-grade ores. In this work, a mineralMineral concentrate of goldGold and silverSilver was characterized by XRD as well as the leachingLeaching solutions in their concentration of goldGold, and silverSilver, by means of atomic absorption spectrometry. The results of leachingLeaching in a system only with TU with 0.2, 0.3, and 0.4 M show a higher percentage of Au and Ag leachingLeaching at a lower concentration of TU (0.2 M). In just 15 min of leachingLeaching, 88 and 59% of goldGold and silverSilver dissolution are obtained, respectively.

Discovering new goldGold deposits is without a doubt, pertinent to meet the increasing demand for precious mineralsMineral like goldGold. CharacterizationCharacterization is done to ascertain the presence of GoldGold in the Filin-kokuwa deposit. CharacterizationCharacterization was carried out using Atomic Absorption Spectroscopy (AAS), Energy Dispersive X-ray Fluorescence Spectrometer (ED-XRF), and Scanning electron microscopy coupled with energy dispersive spectrometry (SEMScanning electronic microscope (SEM)-EDS). The results revealed that Filin–Kokuwa goldGold ore approximately assayed 15 ppm, Au. It was observed from the result that the ore contains 66.5% SiO2, 7.37% K2O, 3.16% CaO, 0.0015% Au, and other associated mineralsMineral. Further qualitative analysis using petrography revealed non-equiaxial mineralMineral grains (light grey), unevenly distributed across the dark-grey ore matrix. This study, therefore, established that the deposit contains goldGold ore and could be a potential source of goldGold exploitationExploitation in Nigeria.

The creep strength of 5Cr-0.5Mo steel5Cr-0.5Mo steel was determined at 600 °C and 78–170 MPa, as well as its relation to the microstructural changes during the creep tests. The microstructural characterizationCharacterization showed that the creep tests were conducted under the presence of a mixture of both intergranular and intragranular M7C3 and M23C6 carbides dispersed in the ferrite matrix. The n exponent of Norton–Bailey law suggested that the creep deformation process occurred through the ferrite grains, which conducted to a transgranular ductile- fracture mode after creep testing. The creep strength of this steel is directly related to the precipitation size and volume fraction during the creep test.

Alkali activated materialsAlkali activated materials present themselves as a viable solution to reduce the consumption of Portland cementCements, and for the management of industrial wasteWaste, including the residual ashAsh from ceramicCeramics production. Thus, this research aimed to evaluate the physical and mechanical behavior of activated alkali materialsActivated alkali materials, with the insertion of ashAsh from ceramicCeramics industries, in the face of durabilityDurability tests. For this, alkali activated specimens containing 0 and 10% of residue insertion were produced. The samples were submitted to curing for 7 and 28 days. Compressive strengthCompressive strength, water absorption, wetting, and drying and salt attack cycles were carried out. The masses of the specimens were measured every day during the durabilityDurability cycles to evaluate the loss of mass. Furthermore, the mechanical strengths of the samples were evaluated before and after the durabilityDurability tests to analyze the influence of the tests on the mechanical behavior of the alkali activated materialAlkali activated materials.

The planet has been facing several environmental problems, most of which come from civil constructionConstruction wasteWaste, which, in addition to being a major polluting source, still requires a large amount of raw materials removed from the environmentEnvironment. In order to minimize these damages, the present work aims to reduce the extraction of sand from river beds and reduce the incorrect disposal of packaging produced with polyethylene terephthalate (PETPolyethylene terephthalate (PET)) through the partial replacement of the fine aggregate by PETPolyethylene terephthalate (PET) in the production of mortarsMortar. Prismatic specimens were be produced with curing in 28 days of 25 °C and partial replacement of 10, 20 and 30% of the natural sand by the wasteWaste. Tests were performed on consistencyConsistency, viscosityViscosity, density, mechanical strength and capillarity will be performed tests. The results showed that the partial replacement of natural sand by PETPolyethylene terephthalate (PET) is feasible, despite some observed viscosityViscosity losses, making this mortarMortar more ecological.

During this investigation, the effect of fly ashFly ash as an additiveAdditive or substitute for Portland cementCements on the initial absorptionInitial absorption of concreteConcrete blocks (Vibro-compactedVibro-compacted) is reported. For comparison, a standard specimen was manufactured with Portland cementCements without any substitution or addition of fly ashFly ash, this standard with an initial absorptionInitial absorption coefficient of 24.2 g/(cm2 × min .5), was compared with four specimens with a replacement or addition of fly ashFly ash. With this reference parameter, they were compared with the modified specimens, the first 15% of fly ashFly ash was added, reaching an initial absorptionInitial absorption coefficient of 26.1 g/(cm2 × min .5) to the last three Portland cementCements was partially replaced in 15, 30 and 50% by fly ashFly ash with an initial absorptionInitial absorption coefficient of 17.0, 19.5 and 22.6 g/(cm2 × min .5) respectively. The physical tests were carried out under the ONNCCE regulations.

One of the actual problems in flotationFlotation of complex niobiumNiobium-tantalumTantalum ores is to develop the advanced methods to improve rare metals mineralMineral processing efficiency by enhancing the contrast of the structural-chemicalChemical (phase) surface state and technological properties of ore and rock-forming mineralsMineral. In the recent years, various types of energy impacts have been used to enhance the contrast of the physicochemicalPhysicochemical and technological properties of mineralsMineral, and the techniques used are the radiation, ultrasound, electrochemical, laser, plasma, microwave, electromagnetic pulse, high-voltage electric pulse, and other effective methods of energy impact. In this paper, we report the results of experimental studies on the directional modification of the surface morphologySurface morphology (SEM–EDX), microhardnessMicrohardness (Vickers), physicochemicalPhysicochemical (electrokinetic and electrochemical potentials, surface hydrophobicity, sorptionSorption activity) and flotationFlotation properties of columbite, tantalite, zircon, feldspar, and quartz as a result of the nonthermal effect by high-power nanosecond electromagnetic pulsesHigh-power nanosecond electromagnetic pulses. The rational pretreatmentPretreatment with nanosecond pulses (ttreat = 100 s is the treatment mineralsMineral time, f = 100 Hz is the pulse repetition rate, and UA ≅ 25 kV is the amplitude of pulses) of rare metal mineralsRare metal minerals provided higher selectivity of columbite and zircon flotationFlotation separation, without any appreciable boost in flotationFlotation activity of rock-forming mineralsMineral (feldspar and quartz).

The açaizeiro is a palm tree found on a large scale in the northern region of Brazil, one of the main non-timber forest products with great economic potential. However, the residues, which represent about 85% of the total fruit, cause a serious environmental problem, since about 365 tons of açaíAçaí seeds are discarded daily, with no provision for reuse. This research studies the feasibility of adding these residues to the coatingCoating mortarsMortar through the partial replacement of sand, in 10% of the mass. four compositions were used, one being a reference (trace 1:3) and the others with the presence of the residue. The mortarsMortar were subjected to tests in the plastic and hardened state. It is concluded that the addition of seed in all compositions generates a reduction in mechanical strength and few changes in properties in the fresh state.

The use of natural lignocellulosic fibers (NLF) favors a series of properties, such as mechanical strength, when used in cementitious compositesComposite. Brazil, due to its climatic and geographical characteristics, has a variety of natural fibersNatural fibers that can be used in cementitious compositesComposite. The objective of this work was to evaluate the characteristics of different mortarsMortar in the hardened state reinforced with the addition of açaíAçaí fiber, exposed to three different methodologies of surface treatment: (i) immersion in a solution of sodium; (ii) potassium hydroxides and (iii) calcium hydroxides, all in a concentration of 10% in relation to the mass of water. MortarsMortar with a mixture of 1:3 (cementCements: sand) ratio, in mass, were made to reinforce structures with additions 1.5, 3.0, 4.5, and 0% (reference) of the açaíAçaí fiber, in relation to the cementCements mass. The results were analyzed by statistical tests and demonstrated that the treatments with potassium hydroxide (KOH) showed the best results.

The global technological advance has been encouraging the development of several more sustainable materials. The current research develops a geopolymeric mixture with the incorporationIncorporation of waste glassWaste glass, given the high strength gain capacity of geopolymerGeopolymer materials, and eliminates the need to burn artifacts as in ceramicsCeramics. Thus, mixtures of SiO2/Al2O3 molar ratios fixed at 3.0 and 3.5 with 10% incorporationIncorporation of waste glassWaste glass were tested, such as water absorption and uniaxial compression tests. In addition, to simulate the exposure conditions of the material, durabilityDurability tests were carried out through wetting and drying cycles and saline attack, evaluating the loss of mass and mechanical strength. The results of the water absorption test showed that the glass wasteWaste considerably reduced the water absorption of the materials, presenting reductions of up to 63%. DurabilityDurability tests by saline attack showed undesirable interactions of the salt with the geopolymerGeopolymer matrix.

In recent decades, the development of new building materialsBuilding materials that meet technological, economic, and environmental criteria, especially those that use alternative raw materials or new production methodologies, have become increasingly necessary. In this context, adobe bricksAdobe bricks, known for decades in the field of civil constructionConstruction, proved to be great models of experimentation, since they result from an adequate mixture of soil, sand, and natural fibersNatural fibers, apart from also air drying, with no need for calcination. In this work, cattle manureCattle manure was used as an alternative of natural fiberNatural fibers for the development of adobe bricksAdobe bricks, in the levels of 5%, 10%, and 15%, to analyze which, one would be ideal. The use of cattle manureCattle manure in the development of adobe bricksAdobe bricks is based on the notion of sustainabilitySustainability, given that this wasteWaste is normally disposed of in an improper way, apart from being less polluting than the chemicalChemical-industrial fibers. In search for the composition that best meets the regulatory requirements of civil constructionConstruction, the effects of corrective materials such as Portland cementCements and hydrated lime were also evaluated, as the main disadvantage of using cattle manureCattle manure is related to its low durabilityDurability in places with high humidity. Thus, through this work, we sought to evaluate the durabilityDurability of adobe blocks, with the proposed formulations, through wetting and drying cycles. In conclusion, it was noticed that the temporal degradation mechanisms of the adobe blocks made of cattle manureCattle manure could be reduced using corrective materials, stabilizing their durabilityDurability.

Due to pineapplePineapple production, the amount of crown residue of this fruit is significant in Brazil. This material has been studied as reinforcement in materials especially when in fiber format. However another part of wasteWaste consists of particulatesParticulates. This work aims to evaluate the technological feasibility of using these particulatesParticulates as reinforcement/filler in polymerPolymer matrix compositesComposite, having as a reference their compressive strengthCompressive strength. The matrix used was a Diglycidyl ether bisphenol A (DGEBA)/triethylene-tetramine (TETA) system, with a stoichiometric ratio of 20 phr. The formulations evaluated consist of the 0, 25, 50, and 100 percentiles of the maximum volume in which it was possible to incorporate the particulatesParticulates. The test was performed using the Instron Model 5582, according to the ASTM D695-15. The results presented demonstrated the variation in the behavior of the material as a function of the amount of charge, as well as the technological feasibility of its incorporationIncorporation.

A significant sample of “refractory tails” product of a gravimetric concentration of primary ore, provided by Empresa Minera Goldmins SRL, with an approximate goldGold content of 31 g/t, was treated experimentally at the laboratory level. It was subjected to a mineralogical characterizationCharacterization by Fluorescence and X-Ray Diffraction, reporting a sulfur (S) content of 15%, iron (Fe) 23%, silica (SiO2) 7%, and arsenic (As) 3% as the main cyanicide. Based on the result of the characterizationCharacterization, two important stages were developed for the recovery of goldGold from these tailings: pretreatmentPretreatment and conventional cyanidationCyanidation. The pretreatmentPretreatment involved grinding to two particle sizes (75 and 105 µm) followed by oxidationOxidation using hydrogen peroxide (H2O2). Subsequently, stirred tank cyanidationCyanidation was carried out. It was possible to develop nine experimental tests considering constant the parameters of the percentage of solids, temperatureTemperature, speed of agitation, and pH. Including a leachingLeaching without oxidationOxidation, whose recovery was less than 10% for 24 h. The remaining eight tests, oxidized and cyanideCyanide, reported recoveries above 59% for the same time. The best recovery, 84% for 24 h, was under the following conditions: grinding at −75 μm, oxidationOxidation with H2O2 at 25 g/L, and leachingLeaching at a NaCN concentration of 3.77 g/L.

The characterizationCharacterization of ornamental rocksOrnamental rocks has the purpose of predicting the behavior of the rocks when exposed to various requests present in their place of application, seeking to know the feasibility of using the material. The objective of this work is to analyze the staining of the rocks after variations in exposure times. Four types of rocks were selected for the test: Dallas White, São Gabriel Black, Castelo Grey, and Siena White. The staining agents chosen were: lemon, oil, coffee, steel sponge and detergent, bleach, and degreaser. As a result, it was noticed that the stainsStain caused were more evident and accentuated as the time of exposure of the rocks to the staining agents increased, developing more accentuated and permanent stainsStain.

22MnB5 steel possesses a promising application in the structural components in automobile industry mainly attributing to its low cost combined with the high mechanical propertiesMechanical properties. The delayed crackingDelayed cracking behavior of the 22MnB5 steel in the solution of 0.1 mol/L HCl with various times is comparatively investigated. By observing the crack initiationCrack initiation and propagation during the delayed crackingDelayed cracking test, it can be found that the initiation of the cracks exists an incubation period, and the cracks appear after being soaked in acid for 3 h. In particular, the crack initiationCrack initiation location is highly related to the position of the pipe, especially the inner bending zones reflect much higher susceptibility of the delayed cracks. The hydrogen can easily accumulate in the bending zones with large residual stress. The interaction between hydrogen and metal atoms can possibly weaken the cohesion of the grain boundaries, eventually trigger the initiation of the cracks.

In recent decades, with the advance of industrialization, the huge amount of wasteWaste discarded by industries has generated discussions about self-sustainable solutions. One of these solutions is artificial stoneArtificial stone, as the use of wasteWaste can be a good alternative for the production of this type of material. Therefore, the main objective of the present work was to evaluate the influence of young scales of arapaima gigas on the reinforcement of artificial stonesArtificial stone made with quarry dust and epoxy resinResin, by the process of vibration, compression, and vacuum. The residue was divided into three granulometric ranges by the sieving method: Coarse and medium (quarry dust) and fine (quartziteQuartzite). Data were treated through statistical analysis, using analysis of variance (ANOVA). The proportions obtained were 5, 7, and 8 (50% coarse and medium), (33% coarse, medium and fine) and (67% coarse, 17% medium, and 16% fine). The 3 developed compositions were submitted to the physical index test. The result obtained classified the composition 7 for the incorporationIncorporation of arapaima scalesArapaima scales, and the physical index, bending, and charpy impact tests were performed to characterize the developed stone. The results obtained indicate that the artificial stoneArtificial stone with pirarucu scale had a porosityPorosity of 0.67% greater than the one without scale, indicating lack of adhesion of the scale with the residues. The mechanical strength was higher, 34.7 ± 2.7 Mpa due to the arapaima scalesArapaima scales having a high strength. The impact energy of charpy was 28.3 ± 4.6 J/m for the scaled artificial stoneArtificial stone and 24.1 ± 4.9 J/m for the scaleless stone.

The manufacturing process of materials used in civil constructionConstruction generates large-scale wasteWaste. In order to create a solution that can alleviate this problem, it was proposed to use marble dustMarble dust wasteWaste as a replacement of the cementCements that will be used in the production of cement pasteCement paste. Specimens were made with replacement proportions of 10 and 20% of the cementCements, observed for a period of 28 days in order to assess your strengths (at 7 days is at 28 days), in order to perform consistencyConsistency index tests, viscosityViscosity and compressive strengthCompressive strength. The results obtained through these tests allowed the analysis of mechanical propertiesMechanical properties, as well as workability characteristics, setting time of the pastePaste and verification of the influence of partial replacement of the marble wasteWaste in the cement pasteCement paste in the hardened state.

The production of clinker uses a high amount of energy and releases a large volume of greenhouse gases. The search for more sustainable production processes has permeated several sectors of academy and industries, in this context, geopolymersGeopolymer have been widely studied as an alternative proposal to conventional cementCements. Steel fibersSteel fibers are an important reinforcement for high mechanical performance concretesConcrete and mortarsMortar. In this work, compositesComposite were prepared with a geopolymeric mortarMortar matrix, reinforced with 1.5 and 3.0% of steel fiberSteel fibers, in relation to the mass of metakaolinMetakaolin used as precursor element. Studies were carried out on the gain of mechanical propertiesMechanical properties, with compression and flexural strength. In addition to the mechanical propertiesMechanical properties, water absorption and density tests in the hardened state were performed. The tests showed good properties of the compositesComposite produced.

It is known that the use of Portland cementCements is essential for civil constructionConstruction in all countries of the world; however, it is well known that this material is highly harmful to the environmentEnvironment. That said, the development of new binders such as activated alkali cementActivated alkali cement (AAC), produced from silica fume and activated by sodium hydroxide, opens the door to the study of less polluting and harmful materials. The results obtained in this research indicate the feasibility of using this material as a substitute for conventional binders.

Optical microscope and X-ray diffraction study were conducted to investigate the microscopic mechanism of coke size distributionCoke size distribution. The results show that an increase in coke sizeCoke size resulted in a slight decrease in moisture and an increase in the volatile matter content. However, the mineralMineral catalysis index (MCI) varied slightly with the change in coke sizeCoke size. Besides, the cell dimension did not change much with the coke sizeCoke size variation. Furthermore, cell spacing and graphitization degree increased when the coke sizeCoke size decreased. Therefore, it is possible to improve the coke size distributionCoke size distribution and control the coke graphitization degree in the coking process.

In this work, the phase transformations were studied during the intercritical treatment in TRIP steel with chemicalChemical composition of Fe-1.39Si-2.57Mn-0.17C. Steel specimens were heated in the intercritical region, ferrite and austenite, at 750° C for 30 min, austempered at 430 °C, quenched in water without agitation, and normalized by air cooling. Microstructural analysis was performed by optical microscopy and scanning electron microscopy, and by X-ray diffraction. All samples were mechanically characterized by uniaxial tension and Rockwell tests. Microstructural and phase analysis was also carried out with the Thermo-CalcThermo-Calc software. The microstructural characterizationCharacterization results showed that the phases and microconstituents were ferrite, austenite, cementite, and austenite. Thermo-CalcThermo-Calc results are consistent with the phases and microconstituents found for each heat treatmentHeat treatment condition. On the other hand, the tension test results showed that the yield strength and ultimate tensile strengthTensile Strength are between 763–818 MPa, and 1190–1255 MPa, respectively, for these heat-treated steels.

Brazil has been standing out in the agro-industrial production in which large volumes of wasteWaste are generated, including pineapple fibersPineapple fibers. Natural fibersNatural fibers have been studied in different compositesComposite, especially cementitious. This research aimed to evaluate fibers from the pineapplePineapple crown for their application in coatingCoating mortarsMortar. The residue was submitted to wetting and drying cycles and, was treated in variable parameters: reagent concentration (5 and 10%), exposure time to chemicalChemical attack (30 min and 60 min), and type of reagent (NaOH and Ca (OH)2). The fibers were incorporated with 1.5% in relation to the mass of cementCements of the produced mortarMortar and compared with the reference mortarMortar (0%), which were evaluated in the fresh state. It was found that the treatment with NaOH was the one that most degraded the external surface of the fiber and the produced mortarsMortar showed satisfactory performance, thus contributing to the development of alternative materials.

The rice beneficiationBeneficiation process annually produces tons of rice husk ashAsh (RHA). In this work, RHA from companies in southern Brazil is characterized physically and chemically, seeking to apply them in cementitious materials. In addition, the wasteWaste was analyzed concerning the literature considering aspects related to its environmental characterizationCharacterization, generation data, recycling availability, and applicability in cementitious materials. The preliminary results of ashAsh characterizationCharacterization demonstrate potential for use in cementitious materials. The ashAsh has a high content of silica (amorphous) and crystalline phases, such as cristobalite. Regarding feasibility, maps of the generating companies and possible recipients of these residual materials in the study region confirm the proposed application. Using RHA in cementitious materials demonstrates an excellent alternative for sustainabilitySustainability and economic circularity in the study region.

WasteWaste generation and its improper disposal have been growing substantially nowadays, among them, steel wastesSteel Waste, ornamental stones and polymersPolymer instigating serious environmental problems. The development of artificial stonesArtificial stone using a polymeric matrix from a renewableRenewable source is a great alternative to reincorporate these types of wasteWaste, creating a novel sustainable stone with properties that make them suitable for use as a coatingCoating in civil constructionConstruction. This work’s main objective was to produce and characterize an artificial stoneArtificial stone (ASGS) with 85% of wastesWaste (granite and steel) in a 15% vegetable polyurethanePolyurethane matrix. Initially, the most close-packed granulometric composition was determined, followed by the plates production using vibration, compression, and vacuum. ASGS presented 2.24 g/cm3 density, which was within the expected range, 0.46% of water absorption, which was at the limit to be considered a low water absorption stone and 1.04% of apparent porosityPorosity, denoting its high porosityPorosity content. The ASGS bend strength classified it as a stone of very high mechanical strength. Through SEMScanning electronic microscope (SEM) micrographs, the high content of apparent porosityPorosity was confirmed, and a low load/matrix interaction was verified. However, analyzing the ASGS bend strength, it was possible to conclude that it did not impair its mechanical strength.

TemperatureTemperature is an important factor affecting the sulfidation of laterite oreLaterite ore. The effect of temperature on the sulfidation of nickel in laterite ore was studied. The thermodynamic analysis shows that the sulfidation reactions of nickel oxide and iron oxide can be carried out at temperaturesTemperature above 400 ºC and increasing temperatureTemperature will promote the reactions. High sulfidation of nickel at high temperatureTemperature will be achieved by regulating the partial pressure of sulfur and oxygen. In the atmosphereAtmosphere of high sulfur and low oxygen pressure, nickel and iron mainly exist in the form of sulfides. With the increase of temperatureTemperature from 400 ℃ to 1200 ℃, the sulfidation degreeSulfidation degree of nickel in the oreLaterite ore increased initially and then decreased. At 1100 ºC, the sulfidation degreeSulfidation degree of nickel in the ore was the highest, reaching 84.43%. The size of nickel sulfide particles increased to about 10 μm.

The polishingPolishing process is an important phase in the processing of ornamental stones, through which it is possible to obtain materials with a high aesthetic standard desired by the international market. This process requires good equipment and a constant flow of water, in order to provide higher quality products. A well-polished material has a higher level of shineShine and is valued more. Thus, the present work aimed to propose a reduction in the water flowWater flow during the polishingPolishing process to evaluate the feasibility of reducing water consumption while increasing the quality of the final product. To carry out the study, three types of rocks were chosen: Corumba Grey, Dallas White and Itabira Ochre. The experiments proved to be efficient and the quantitative analysis can be an important tool in obtaining a brighter final product and, also, an opportunity to save water.

Barium Titanate (BaTiO3)-based ceramicCeramics materials are widely used in the electroceramic industry. Conventional processing of these materials is primarily in high-temperatureTemperature solid-state reactions between mixed oxides. To produce a better quality of the initial powder, factors such as the quality of raw materials, homogeneity of the mixture and the nature of the reaction atmosphereAtmosphere must be controlled. In this research, an analysis of BaTiO3-based ceramicCeramics products doped with EuropiumEuropium (Eu3+) were carried out, by means of solid-state reaction synthesisSynthesis. A review of the compositions (x = 0.007 and x = 0.01% by weight Eu3+) was carried out, grinding was carried out for 5 h and the resulting powders were calcined at 900 °C and sintered at 1350 °C. The experimental results by x-ray diffraction showed the tetragonal BaTiO3 phase. Raman spectroscopyRaman spectroscopy analysis shows the phase transition of BaTiO3 ceramicsCeramics. Scanning electron microscopy results showed randomly round particles.

Guaruman fiberGuaruman fiber is a natural lignocellulosic fiber (NFL) extracted from the stalk of an Amazon plant (Ishinosiphon Koern) in the northern region of Brazil. The present work investigates the addition of 2.5, 5.0 and 7.5 wt.% of guaruman fiberGuaruman fiber, in cementCements mass, and a reference mortarMortar (0%). The fibers were mercerized in NaOH solution for improved adhesion to a mortarMortar matrix made with 1:1:6 ratio of Ordinary Portland CementCements (OPC), lime and natural sand. Technical propertiesTechnical properties, such as density, consistencyConsistency, content of air incorporated and water retention were evaluated for the processed fresh state of the mortarMortar reinforced with guaruman fiberGuaruman fiber. The preliminary results in association with the relatively low density of the mortarsMortar incorporated with NaOH-treated guaruman fibersGuaruman fiber reveal a promising material to be applied as mortarMortar for wall covering in civil constructionConstruction, in a proportion of 7.5 wt.%, which shows a great potential for the use of this fiber.

Coconut fiberCoconut Fiber is a renewableRenewable material that has high potential for use in civil constructionConstruction. Proving to be a profitable and promising alternative, this study intends to analyze and compare the effects of the addition of coconut fiberCoconut Fiber in the mortarMortar through tests, such as consistencyConsistency, density, viscosityViscosity, compressive and flexural strength. The comparison was made with 0.3 and 0.6% of addition in cementCements mass, treating the fibers previously with sodium hydroxide with 0.3 and 0.6% and in natural condition. The results showed that the treatment was beneficial for this type of fiber, showing that its application in mortals is feasible.

Portland cementCements is widely used in civil constructionConstruction due to various convenient properties, however, in its production processes a large volume of polluting gases is dispersed in the atmosphereAtmosphere, harming the environmentEnvironment. CompositesComposite of geopolymerGeopolymer matrices reinforced with natural fibersNatural fibers emerge as potential mitigators of the use of conventional cementCements, reducing the emission of pollutants. PineapplePineapple crowns are a residue generated on a large scale in fruit producing places, making their use in compositesComposite possibly viable. This work carried out a chemicalChemical treatment of the fibers of the pineapplePineapple crown leaves in a 5% NaOH solution to study the properties of a geopolymeric mortarMortar in the fresh state, with the addition of 2 and 4% of the reinforcing elements, on the mass of metakaolinMetakaolin. ConsistencyConsistency tests, density in the fresh state and viscosityViscosity were carried out, which verified a good workability of the mortarsMortar.

To investigate the effect of electromagnetic field on molten mold fluxMolten mold fluxes, the electrical conductivityElectrical conductivity of the CaO–SiO2–Al2O3–MgO–CaF2–Na2O system was tested by the AC four-electrode methodAC four-electrode method, and the influencing factors and change in the law of conductivity of the molten mold fluxMolten mold fluxes was analyzed. The results show that the conductivity of molten mold fluxMolten mold fluxes increases with the increasing content of Na2O, CaF2, and other components, and the basicity of mold flux. In this work, the electrical conductivityElectrical conductivity of the molten mold fluxMolten mold fluxes is approximately 0.026–0.810 Ω−1 cm−1. For every 0.1 increase in optical basicity, the conductivity increases by about 58.7%. As the temperatureTemperature increases every 25 K, the conductivity increases by about 27.2%.

Tin oxide nanoparticles were synthesized using the sol–gel technique, where metallic tin, ammonia hydroxide, nitric acid, ascorbic acid, ethanol, and deionized water were used. A white powder characteristic of tin oxide was obtained. X-ray diffraction was performed on the synthesisSynthesis product and identified as cassiterite (SnO2), with a tetragonal unit cell, which lattice parameters are at a = 4.74 Å and c = 3.19 Å, the ICDD-PDF letter is 96-210-4755. Scanning electron microscopy characterizationCharacterization showed that nanoparticles have a spherical morphologyMorphology and sizes ranging from 23 to 67.6 nm. Analysis performed by infrared spectroscopy show that it has the tin bond oxygen 667 cm−1 region.

BaTiO3 is a ceramicCeramics compound of ABO3 perovskite-type where Ba occupies the A site and Ti the B site. The saturation of the BaTiO3 lattice with Eu3+ allows the formation of secondary phases with specific applications. In this work, the Eu2TiO5Eu2TiO5 phase was synthesized using the solid-state reaction method and sintering at 1300 °C for 6 h through the Ba1-xEuxTi1-x/4O3 electronic compensation mechanism with x = 0, 10, and 15 Eu3+ (wt.%). The X-ray diffraction spectra of the analyzed samples indicate the presence of the crystalline phase Eu2TiO5Eu2TiO5 (The Joint Committee on Powder Diffraction Standards (JCPDS) 96-200-2716). Rietvel refinement analysis of the orthorhombic Eu2TiO5Eu2TiO5 structure indicated an increase in the lattice parameters “a”, “b”, and “c” and in the cell volume attributed to the increase in Eu+3 concentration. Additionally, the presence of Eu2TiO5Eu2TiO5 was verified by Raman spectroscopyRaman spectroscopy studies in the band at 778 cm−1. The Eu2TiO5Eu2TiO5 phase finds electrical, optical, magnetic, and nuclear applications.