Major Minerals Research Articles

Research Advances in the Mutual Mechanisms Regulating Response of Plant Roots to Phosphate Deficiency and Aluminum Toxicity.

Low phosphate (Pi) availability and high aluminum (Al) toxicity constitute two major plant mineral nutritional stressors that limit plant productivity on acidic soils. Advances toward the identification of genes and signaling networks that are involved in both stresses in model plants such as Arabidopsis thaliana and rice (Oryza sativa), and in other plants as well have revealed that some factors such as organic acids (OAs), cell wall properties, phytohormones, and iron (Fe) homeostasis are interconnected with each other. Moreover, OAs are involved in recruiting of many plant-growth-promoting bacteria that are able to secrete both OAs and phosphatases to increase Pi availability and decrease Al toxicity. In this review paper, we summarize these mutual mechanisms by which plants deal with both Al toxicity and P starvation, with emphasis on OA secretion regulation, plant-growth-promoting bacteria, transcription factors, transporters, hormones, and cell wall-related kinases in the context of root development and root system architecture remodeling that plays a determinant role in improving P use efficiency and Al resistance on acidic soils.

Məhsuldar Qatın dərində yatan terrigen kollektorlarında karbohidrogenlərin miqrasiya kanallarının paleomaqnit izləri

It was defined that as a result of saturation or migration of hydrocarbons, thin disperse magnetite, which can be revealed via thermal-magnetic research methods, has been formed. Moreover, the most sensitive parameters are Irs/Irso and Irt/In associated with the temperature phase transformations of iron-containing compounds. The values of Irs/Irso and Irt/In reach the dozens and hundred value units for the rocks saturated with oil, and the order of units for the rocks not underwent the contact with hydrocarbons. Therefore, studying the values of Irs/Irso and Irt/In, one can judge on the presence of iron compounds in the reservoirs and correspondingly, suppose whether this horizon served earlier as a reservoir, or medium for hydrocarbon migration. Thermal-magnetic research surveys carried out by us justified that in the section of Productive Series in Azerbaijan the major magnetic minerals responsible for the primary magnetism of terrigene reservoirs of Upper Pliocene is the magnetite with Tс = 550-575 oС and the hydrogethite with Tс = 100–120 oС. At the same time, abnormally high values of Irs/Irso and Irt/In and Irs/Irso и Irt/In parameters are observed as well. These data may justify that the age of Upper Pliocene in Productive Series of Azerbaijan is the most probable time for either formation of oil and gas deposits or for the migration of main hydrocarbon mass towards favorable structures (traps).

How Does Quinoa (Chenopodium quinoa Willd.) Respond to Phosphorus Fertilization and Irrigation Water Salinity?

Soil salinity is a major problem in arid and semi-arid regions, causing land degradation, desertification, and subsequently, food insecurity. Salt-affected soils and phosphorus (P) deficiency are the common problems in the sub-Sahara, including the Southern region of Morocco. Soil salinity limits plant growth by limiting water availability, causing a nutritional imbalance, and imparting osmotic stress in the plants. The objective of this study was to determine the positive effects of P on growth and productivity and understand the major leaf mineral nutrient content of quinoa (Chenopodium quinoa Willd.) cv. “ICBA Q5” irrigated with saline water. A field experiment applying three salinity (Electrical Conductivity, EC) levels of irrigation water (ECw = 5, 12, and 17 dS·m−1) and three P fertilizer rates (0, 60, and 70 kg of P2O5 ha−1) were evaluated in a split-plot design with three replications. The experiment was conducted in Foum El Oued, South of Morocco on sandy loam soil during the period of March–July 2020. The results showed that irrigation with saline water significantly reduced the final dry biomass, seed yield, harvest index, and crop water productivity of quinoa; however, P application under saline conditions minimized the effect of salinity and improved the yield. The application of 60 and 70 kg of P2O5 ha−1 increased (p < 0.05) the seed yield by 29 and 51% at low salinity (5 dS·m−1), by 16 and 2% at medium salinity (12 dS·m−1), and by 13 and 8% at high salinity (17 dS·m−1), respectively. The leaf Na+ and K+ content and Na+/K+ ratio increased with irrigation water salinity. However, the leaf content of Mg, Ca, Zn, and Fe decreased under high salinity. It was also found that increasing P fertilization improved the essential nutrient content and nutrient uptake. Our finding suggests that P application minimizes the adverse effects of high soil salinity and can be adopted as a coping strategy under saline conditions.

Modeling the Viscoelastic Behavior of Quartz and Clay Minerals in Shale by Nanoindentation Creep Tests

The viscoelastic behavior of minerals in shales is important in predicting the macroscale creep behavior of heterogeneous bulk shale. In this study, in situ indentation measurements of two major constitutive minerals (i.e., quartz and clay) in Longmaxi Formation shale from the Sichuan Basin, South China, were conducted using a nanoindentation technique and high-resolution optical microscope. Firstly, quartz and clay minerals were identified under an optical microscope based on their morphology, surface features, reflection characteristics, particle shapes, and indentation responses. Three viscoelastic models (i.e., three-element Voigt, Burger’s, and two-dashpot Kelvin models) were then used to fit the creep data for both minerals. Finally, the effects of peak load on the viscoelastic behavior of quartz and clay minerals were investigated. Our results show that the sizes of the residual imprints on clay minerals were larger than that of quartz for a specific peak load. Moreover, the initial creep rates and depths in clay minerals were higher than those in quartz. However, the creep rates of quartz and clay minerals displayed similar trends, which were independent of peak load. In addition, all three viscoelastic models produced good fits to the experimental data. However, due to the poor fit in the initial holding stage of the three-element Voigt model and instability of the two-dashpot Kelvin model, Burger’s model is best in obtaining the regression parameters. The regression results indicate that the viscoelastic parameters obtained by these models are associated with peak load, and that a relatively small peak load is more reliable for the determination of viscoelastic parameters. Furthermore, the regression values for the viscoelastic parameters of clay minerals were lower than those of quartz and the bulk shale, suggesting the former facilitates the viscoelastic deformation of shale. Our study provides a better understanding of the nanoscale viscoelastic properties of shale, which can be used to predict the time-dependent deformation of shale.

Multisensor hyperspectral imaging approach for the microchemical analysis of ultramarine blue pigments

This work presents a multisensor hyperspectral approach for the characterization of ultramarine blue, a valuable historical pigment, at the microscopic scale combining the information of four analytical techniques at the elemental and molecular levels. The hyperspectral images collected were combined in a single hypercube, where the pixels of the various spectral components are aligned on top of each other. Selected spectral descriptors have been defined to reduce data dimensionality before applying unsupervised chemometric data analysis approaches. Lazurite, responsible for the blue color of the pigment, was detected as the major mineral phase present in synthetic and good quality pigments. Impurities like pyrite were detected in lower quality samples, although the clear identification of other mineral phases with silicate basis was more difficult. There is no correlation between the spatial distribution of the bands arising in the Raman spectra of natural samples in the region 1200–1850 cm−1 and any of the transition metals or rare earth elements (REE). With this information, the previous hypothesis (based on bulk analysis) attributing these bands to luminescence emissions due to impurities of these elements must be revised. We propose the consideration of CO2 molecules trapped in the cages of the aluminosilicate structure of sodalite-type. Additionally, correlation between certain Raman features and the combined presence of Ca, P, and REE, in particular Nd, was detected for the lowest quality pigment. Our results highlight the usefulness of fusing chemical images obtained via different imaging techniques to obtain relevant information on chemical structure and properties.

Mapping Main Structures and Related Mineralization of the Arabian Shield (Saudi Arabia) Using Sharp Edge Detector of Transformed Gravity Data

Saudi Arabia covers most of the Arabian Peninsula and is characterized by tectonic regimes ranging from Precambrian to Recent. Using gravity data to produce the lateral boundaries of subsurface density bodies, and edge detection of potential field data, a new subsurface structural map was created to decipher the structural framework controls on the distribution of gold deposits in Saudi Arabia. Moreover, we detected the relationships between major structures and mineral accumulations, thereby simultaneously solving the problem of edge detectors over complex tectonic patterns for both deeper and shallower origins. Analytic signal (ASg), theta map (TM), TDX, and softsign function (SF) filters were applied to gravity data of Saudi Arabia. The results unveil low connectivity along the Najd fault system (NFS) with depth, except perhaps for the central zones along each segment. The central zones are the location of significant gold mineralization, i.e., Fawarah, Gariat Avala, Hamdah, and Ghadarah. Moreover, major fault zones parallel to the Red Sea extend northward from the south, and their connectivity increases with depth and controls numerous gold mines, i.e., Jadmah, Wadi Bidah, Mamilah, and Wadi Leif. These fault zones intersect the NFS in the Midyan Terrane at the northern part of the AS, and their conjugation is suggested to be favorable for gold mineralization. The SF maps revealed the boundary between the Arabian Shield and Arabian Shelf, which comprises major shear zones, implying that most known mineralization sites are linked to post-accretionary structures and are not limited to the Najd fault system (NFS).

Na-montmorillonite to Fe(II)-Mt using ferrous citrate/ascorbate obtained by dissolving iron powder

Bentonite containing montmorillonite (Mt) as the major clay mineral is the potential buffer material of engineered barrier system in the deep geological repository for high-level waste management. The corrosion products of canister/or overpack material (carbon steel) may alter the basic characteristics of bentonite through Fe/clay interaction and formation of FeMt to certain extent. A convenient method is required for quantitative preparation of Fe(II)-Mt because the only few direct methods reported have some limitations. For this, weak ferrous complexes having good solubility to facilitate the cation-exchange with bentonite is essential. Therefore, Fe(II)-citrate, Fe(II)-ascorbate and Fe(II)-citrate/ascorbate were obtained here by dissolving the iron powder (Fe0) in citric acid (CA), ascorbic acid (AA) and their equimolar mixtures from 25 mM to 300 mM at 70 °C under N2 atmosphere. The redox potential was measured to monitor the dissolution of Fe0 in these mild organic acids. Higher dissolution of Fe0 occurred in CA + AA mixture. The dissolved iron in the form of ferrous complex was reasonably stable in inert atmosphere, Fe2+/Fetotal ≈ 1. The parent clay mineral (bentonite, NaMt) was treated with Fe(II) − cit/asc to form Fe(II) − Mt. through cation exchange process. The CEC and ferrous to ferric ratio of the Fe(II)-Mt was close to the stoichiometric amount. The XRF, XRD, ac impedance, FT-IR, TGA/DSC, XPS and FE-SEM are used for further characterization. In-situ complexation reaction of interlayer Fe2+ ions in Fe(II)-Mt with o-phenanthroline was also observed.

Study of wear losses and frictional heat dissipation during dry sliding wear of ilmenite reinforced Al-alloy composite

In this investigation, ilmenite mineral reinforced Al–Si alloy matrix composite (AMC) has been developed. The wear behavior of the developed composites has been studied for their end application as break drum material to replace cast iron used in automobile industries. Ilmenite is one of the major sea beach mineral. AMC has been prepared through a low-cost stir-casting method in which 1 wt.% graphite (Gr)/tin (Sn) as a solid lubricant has been added during the fabrication of composites itself. The optical micrographs of AMC revealed uniform distribution of ilmenite particles throughout the matrix. The wear rate of the base LM30 alloy containing 17% Si and the developed composites has been studied at different normal loads at a constant velocity of 1.6 m.s−1. Optimized data revealed a significant wear rate reduction due to solid lubrication provided by Gr/Sn (∼32%). The wear rate of composites has been compared with traditional cast iron used in brake drums under similar experimental conditions. Composites exhibit nearly identical wear behavior throughout the test. The microstructural study of wear track and debris revealed that Sn and Gr used as solid lubricants played a vital role in reducing the wear loss of the prepared composites. A theoretical study of frictional heat generated during dry sliding and its dissipation has been done to establish the operative wear mechanism in the composites.

Genesis of the Enkafela Mn deposit: a record of submarine hydrothermal activity in the Afar Depression, Northeast Ethiopia

ABSTRACT The genesis of the Enkafela Mn deposit and associated processes were investigated using field mapping, mineralogical and geochemical analyses by XRD, ICP-MS/AES and XRF. The geology is constituted by limestone, evaporites/gypsum, conglomerates and basalt. The orebody is hosted in the limestone and has two distinctive manganese layers: a massive bottom and powdery top. Pyrolusite, romanechite and birnessite are the major ore minerals. The geochemical results indicate elevated MnO (av. 70.25 wt-%), Ba (>10,000 ppm), Sr (>10,000 ppm) and depleted Fe2O3 (av. 0.37 wt-%) and other metals. The massive orebody has higher (172.9 ppm) REE content than the powdery ore (7.84 ppm). Chondrite normalised REE plot shows LREE enrichment for both orebodies. The massive manganese layer shows enrichment in Ce and no Eu anomaly. The powdery manganese is depleted in Ce and Eu. The geochemical and mineralogical studies indicate that the manganese mineralisation has dual sources: hydrogenous and hydrothermal sources (for the massive orebody), and hydrothermal (for the powdery). The data suggest that there was active submarine hydrothermal activity in Dallol associated with the regional geodynamic events while the area was inundated by the Red Sea during the Pleistocene.

ACCORD: A Scalable Multileader Consensus Protocol for Healthcare Blockchain

Blockchain is an emerging distributed and decentralized technology that promises to revolutionize the healthcare sector by securely storing and maintaining incorruptible electronic health record data. Consensus protocols are at the core of blockchain technology. They establish security and integrity in the system by ensuring that the majority of miners are in agreement on all transactions and blocks added to the distributed ledger. While many consensus protocols have been proposed, most of them require heavy computation and are not scalable. In this work, we propose a novel permissioned consensus protocol, named ACCORD, a multi-leader (quorum-based) protocol that achieves fork-resistance, robustness, and scalability. To achieve this, ACCORD consists of three distinct components: (1) an asynchronous quorum selection procedure to designate the creators of future blocks, (2) a block creation protocol run by the quorum to prevent omissions in the presence of honest quorum members, and (3) a decentralized arbitration protocol to ensure consensus by voting. Additionally, we implemented the protocol and conducted experiments to demonstrate scalability, robustness, and fairness.

New insights into modeling disjoining pressure and wettability alteration by engineered water: Surface complexation based rock composition study

Several laboratory studies observed wettability alteration of carbonate rocks towards a more water-wet state through modifying the composition of injected water. The change in carbonate surface charge was reported as the underlying reason behind this wettability alteration and the corresponding incremental oil recovery by engineered water injection (EWI). Although the reported results of carbonate rock sensitivity to injected water ionic strength, pH, salinity, and concentration of potential determining ions (Ca 2+ , Mg 2+ , and SO 4 2− ), there is still an ambiguity on the way carbonates interact with injected water/ions. This is due to the different mineralogical compositions and electrokinetic properties of carbonates. Therefore, this paper provides more insight into the role of major rock-forming carbonate minerals (calcite and dolomite) in engineered water injection at different water compositions by utilizing surface complexation modeling (SCM). The study utilizes a geochemical simulator to highlight the effect of dolomite surface complexation reactions. After determining the total rock surface charge and surface potential, the disjoining pressure was calculated to estimate the water film thickness and consequently, infer about wettability alteration. The results showed that a successful EWI operation creates three regimes: displacement regime, surface reaction regime, and quasi-equilibrium regime. These regimes can be characterized by the proposed surface complexation technique to calculate/optimize the injection pore volumes needed for each regime, determine the location of EWI effect in the reservoir, and predict the time ranges when EWI will reach to the surface in the form of additional oil recovery. Also, it was found that the surface reaction regime is the most important one where main surface reactions and oil recovery occur. Furthermore, the study utilizes SCM for both calcite and dolomite minerals for the first time highlighting their importance in geochemical reactions of EWI when the rock has dolomite in its composition. Existing SCM considers oil-brine and rock-brine interfaces where only calcite mineral is captured in the rock-brine interface. The latter is based on assuming that the rock composition is pure calcite, which is not necessary the case. The findings of this study confirm that seawater is capable of inducing wettability alteration in carbonates under certain favorable conditions due to adsorption/desorption of the potentially determining ions. • This paper provides novel insight into the role of major rock-forming carbonate minerals (calcite and dolomite) in EWI/LSWI at different water compositions by utilizing the surface complexation reactions. • It is found that in a successful EWI operation, three regimes would be created, i.e. displacement regime, surface reaction regime, and equilibrium regime. • These regimes can be characterized by the proposed technique to calculate/optimize the injection pore volumes needed for each zone. • The developed approach can determine the location of EWI effect in the reservoir, and predict the time ranges when EWI would reach to the surface in the form of additional oil recovery. • This study utilizes SCM for both calcite and dolomite minerals for the first time highlighting their importance in geochemical reactions during EWI when the rock has dolomite as a constituent.

Comparative Study on Major and Trace Mineral Content of Edible and Eggshell Powders from Ethiopian Local and Exotic Breed Chicken Eggs

In this study, the effect on the mineral content of eggs from local and exotic breed hens was investigated. For this study, random samples were collected from the Ethiopian Institute of Agricultural Research, Debrezeit Agricultural Research Center, and Fresh Corner Poultry Farming Debrezeite, Ethiopia for the exotic and local breed eggs respectively. Eggshells and edible portion of the egg were analyzed for Calcium (Ca), Potassium (K), Phosphors (P), Sodium (Na), Magnesium (Mg), Iron (Fe), Zinc (Zn), Manganese (Mn), and Copper (Cu) contents. The Phosphors and Zinc contents of the edible egg portion were higher in the local breed eggs than in exotic breed eggs. Calcium and Magnesium content of the eggshell was higher in local breed eggs while Zn content showed a marked decrease. As far as Potassium, Magnesium, Sodium Phosphors, and Copper values were concerned, these did not differ between the eggs from local and exotic breed types. The present finding provides sizeable differences in mineral content between the eggs from the local and exotic breed hens. The results afford a point of departure measurements of major and trace mineral contents of eggs and suggest quantifiable differences amid eggs from hens in different husbandry systems, and hens breed types. The physiological significance of those differences is discussed. But, future studies should elucidate differences observed by crossbreed types, diet effect, and husbandry system. Drying eggs can be a workable food systems intervention that can mend the wellbeing and eminence of diets in low-income countries like Ethiopia. Keywords: Egg, Hen, Mineral Content, Local breed, Exotic breed, Food System, Low-income DOI: 10.7176/CPER/64-01 Publication date: January 31 st 2022

Physical fruit traits, proximate composition, fatty acid and elemental profiling of almond [Prunus dulcis Mill. DA Webb] kernels from ten genotypes grown in southern Morocco

This study was carried out with the aim to evaluate physical fruit traits, proximate composition, elemental content, and fatty acid profiling of almond kernels from ten genotypes (sweet and bitter) grown under various agro-ecological conditions (Tafraout, Igherm, Taliouine, Tiznit and Essaouira) in southern Morocco. During the ripening stage, samples (almond kernels) belonging to these genotypes were subjected to physical fruits measurements (weight, length, width, and thickness). Proximate composition determination (crude protein, crude oil, ash and moisture) was carried out on the powder of kernels for each genotype. Carbohydrates as well as energy value were calculated. Elemental profiling of almond kernels consisted of ten macro and microelements was determined as well as the fatty acids composition of almond extracted oil. The results of this study showed wide variations among the investigated genotypes in terms of crude protein (17.14 ± 2.14 to 25.12 ± 1.23 g/100 g), oil content (51.12 ± 2.99 to 56.26 ± 3.22 g/100 g), ash content (5.11 ± 0.45 to 6.79 ± 0.52 g/100 g), moisture content (2.55 ± 0.38 to 4.34 ± 1.16 g/100 g), carbohydrates (13.34 ± 1.54 to 18.59 ± 2.22 g/100 g) and energy value (549.80 ± 37.04 to 591.03 ± 38.56 kcal/100 g DM). A similar trend was observed in the case of mineral profiling. K (9796.08 ± 793.49 to 14 197.84 ± 1150.03 mg/kg) was the major mineral in all genotypes. This was followed by P (8190.75 ± 663.46 to 11 061.68 ± 895.96 mg/kg), Ca (3067.53 ± 248.47 to 5404.93 ± 437.79 mg/kg) and Mg (4002.85 ± 324.22 to 5101.72 ± 413.23 mg/kg), while Na, Cu, Fe, Zn, Mn and B were detected in small quantities. Our results revealed six fatty acids with a dominance of oleic acid, which varied widely among the studied genotypes and extraction technique. Solvent extraction performed better in terms of oil content. The studied genotypes showed a great pomological potential that could be exploited for their fruits such as for breeding purposes.

STRUCTURAL ANALYSIS AND RESERVOIR CHARACTERISATION OF CRETACEOUS SEQUENCE IN KOHALA BALA, KHYBER PAKHTUNKHWA, PAKISTAN

The southeastern Hazara is a portion of the Himalayan Fold-Thrust Belt, formed by the interaction of the Indian Plate with the Eurasian Plate. The present research was conducted to analyse the structural geometry and assess the reservoir potential of the Cretaceous sequence (Chichali Formation and Kawagarh Formation) in southern Hazara, Pakistan. The mapped stratigraphic units range from Late Jurassic, Samana Suk Formation to early Eocene, Margalla Hill Limestone, along with unconformities. The research area is under intense deformation and is characterised by the thrust faults with accompanying folds. The fore-thrust faults are steeply dipping towards the north with associated back-thrust dipping southward, and the folds are mainly asymmetric anticlines and asymmetric synclines along with symmetric anticline (Barkot). The structures trend mainly NE-SW, indicating NW-SE compressive stresses. Reservoir quality is evaluated by using petrographic image analysis, SEM analysis, plug porosity, and permeability analysis. The porosity observed varies from 0.282% – 10.89%, 0.016% – 1.78% in Chichali (Sandstone) Formation and Kawagarh (Limestone) Formation, respectively. Simultaneously, the measured permeability in Chichali and Kawagarh Formation varies from 0–0.064 mD and 0–0.014 mD, respectively. The primary porosity type was intergranular/interparticle, intragranular, fracture, and vuggy porosity. SEM analysis shows that microporosity is present in the Cretaceous sequence and, calcite, dolomite, quartz, feldspar, and pyrite are the major minerals. The reservoir studies show that the Chichali Formation can be proven a good (Tight) reservoir rock, and Kawagarh Formation may prove as a reservoir (if the fractures in the subsurface, formed by severe tectonic deformation are not filled with cementing material) and seal/cap rock.

Mineral Chemistry, Geobarometry and Oxygen Fugacity of the Granitic Rocks from the Itremo Domain, Central Madagascar

Major and accessory minerals from the Ibity granite, Tsarasaotra monzonitic and granite dykes, and Antsahakely granite of the Itremo domain in the Precambrian basement of Madagascar were characterized by using microscopic observations and chemical analyses with the aim of understanding their chemical characteristics and estimating the crystallization pressure and oxygen fugacity of their host rocks. Plagioclases in these rocks are albite and oligoclase, while alkali feldspars are orthoclase. For the phlogopite-micas, Fe-biotite and Li-phengite are common for the Ibity and Antsahakely granites, Mg-biotite is common for the Ibity granite and the Tsarasaotra monzonitic and granite dykes, and siderophyllite and Zinnwaldite are specific to the Ibity granite. Phlogopite-micas in the studied rocks are mainly primary, accessorily re-equilibrated, and rarely secondary. Calcic amphiboles distributed in the Magnesio-and Ferro-hornblende are identified in the Tsarasaotra monzonitic, whereas amphibole is rare and absent in the other rocks. Igneous titanite is observed in the Ibity granite and in the Tsarasaotra monzonitic rocks, which have similar compositions to some REE oxide-rich titanites. Concerning the Fe-Ti oxide phases, the rhombohedral and spinel/trifer tetroxide phases are found in both the Tsarasaotra monzonitic and the Tsarasaotra granite dyke, the trifer tetroxide and spinel + wüstite phases are found only in the Ibity granite, and the pseudobrookite + rhombohedral phase is found only in the Tsarasaotra granite dyke. The epidote mineral, rarely found in the Antsahakely granite, could be an indicator of metamorphism or hydrothermal activity involved during the emplacement of this rock. Aluminum in hornblende geobarometer gave pressure ranges of around 5 kbar for the Tsarasaotra monzonitic rocks. The Titanite geobarometer gave pressures of 2.5 - 3.2 kbar for the Ibity granite, 2.9 kbar for the Tsarasaotra monzonitic, and 7.1 kbar for the Antsahakely granite. Both amphibole and Fe-Ti oxide-base oxygen fugacity reveal high oxygen fugacity conditions for the Tsarasaotra monzonitic and granite dyke emplacements, which might have a relationship with a porphyritic environment.

High temperature transformation of iron-bearing minerals in basalt: Mössbauer spectroscopy studies

Abstract The high temperature decomposition of basalt from Lower Silesia (Poland) was followed by Mössbauer spectroscopy investigation. The Fe content of the sample was ~9.0 at.%. The X-ray diffraction analysis shows that augite (37%) and olivine (12%) are major Fe-bearing mineral components. The sample also contains significant amount of anorthite (22%) and nepheline (17%). The sample was heated at various temperatures between 200°C and 1100°C for three hours. Up to a temperature of 500°C changes in contribution of Fe-bearing minerals are insignificant. Heating in the temperature range from 500°C to 1100°C leads to a systematic increase in contribution of iron oxides at the cost of contribution of silicate minerals, like augite and olivine. Mössbauer spectrum obtained after heating at 1100°C showed hematite as the main iron oxide phase. The ratio of Fe3+/Fetot in the non-heated sample was equal to 0.51 and after heating at 1100°C this ratio amounted to 0.89.

Dynamic simulator and model predictive control of a milk pasteurizer

In this study, the design, optimization and dynamic modelling of a milk pasteurization unit have been developed, using the pseudo-component approach for describing milk properties. The fluid has been regarded as a mixture of five major categories, namely water, fats, proteins, carbohydrates, and minerals. Exploiting the optimal pasteurizer configuration, selected based on the total annualized cost, a dynamic model of the process has been also derived. The simulation of the system is then used as a virtual plant to develop a nonlinear model predictive control (NMPC) designed for rejecting the more important disturbances that can enter the system. The predicted trajectories have been calculated with a simplified version of the dynamic model, obtained by neglecting parameters temperature dependence. The NMPC performance has been compared with a PI controller in terms of set-point tracking and disturbance rejection. Similar results have been obtained when using the different control algorithms for the output responses, but the NMPC showed better behaviour of the manipulated variables.

Thermodynamic analysis of primary and secondary minerals stability in melilite-nephelinite tuff with Australopithecus Afarensis footprints, Laetoli, Tanzania

The Laetoli area in northern Tanzania is an important palaeo-anthropological site, where the oldest footprints of Australopithecus afarensis reside. Aeolian tuffs are the major rock type at Laetoli and they are divided into Lower and Upper Laetolil Beds that were deposited at an interval of 4.36 and 3.63 million years. The Upper Laetolil Beds contain eight layers of air-fall tuffs known as marker tuffs. The Australopithecus afarensis footprints are observed on the surface of the white tuff, which is a part of the Upper Laetolil marker tuff 7, also known as the “Footprint Tuff.” The interpolated age of the marker tuff 7 is 3.66 million years. Two mineral assemblages are distinguished in the Upper Laetolil marker tuffs. The first assemblage consists of primary tuff minerals and includes clinopyroxene (diopside, augite, aegirine-augite), nepheline, melilite (åkermanite and alumoåkermanite), garnet (andradite and schorlomite), magnetite, and others. The second mineral assemblage consists of secondary minerals, montmorillonite, calcite, and phillipsite. They were formed during replacement of the primary minerals, volcanic glass, and ash cementation. Thermodynamic calculations show that the major primary tuff minerals (melilite and nepheline) are stable at variable sodium activity and pH values. Replacement of melilite and nepheline by montmorillonite is caused by a decrease of sodium activity in slightly alkaline, neutral and acidic conditions (рН &lt; 10). Montmorillonite is not present in the altered nephelinitic tuff of the Sadiman volcano (which is considered as a source of the Laetolil Beds) where kaolinite is the major secondary mineral. This is explained by the difference in H2O fugacity with higher lgfH2O values in Sadiman and lower values in Laetoli. Relationships between primary and secondary tuffs minerals on the lgaHCO3 vs pH plot suggest mineral transformation within the Laetolil Beds in slightly acid and neutral con- ditions (рН = 5–7) compared with more alkaline conditions at Sadiman (рН &gt; 10).

Rare Earth Minerals in Veined Nepheline Syenites of the Chernihivka Carbonatite Massif of the Azov Region

We studied partially altered veined nepheline syenites at the Chernihivka carbonatite massif of the Azov region, Ukraine. The major minerals of the syenite are albite, altered nepheline, biotite and calcite. Fluorapatite, allanite-(Ce), monazite-(Ce), barite and stronalsite occur as minor accessory phases. The primary minerals, containing REE in the veined rocks, reflect re-equilibration in a mineral/fluid systems and recrystallization of primary rock-forming minerals. The high initial concentration of CaO, CO32–, alkalis and volatile components caused a concentration of REEs in the late differentiated portions of the phonolite melt. The intrusion of the melt into wall-rocks of different composition, together with the excees of Al and Si in solution, caused allanite-(Ce) crystallization. Subsequent postmagmatic fluids contributed to Ba, Sr and REE leaching from major rock-forming apatite and calcite and led to the crystallization of secondary monazite-(Ce), barite and stronalsite.

Thermodynamics and mechanisms of silver tailings roasting processes

To separate and extract all the useful components of tailings, taking silver tailings as the object, the thermodynamics of silver tailings during the roasting processes was investigated, and the phases transformation mechanism of major minerals were obtained. Based on the mineralogy characteristics of silver tailings, the standard Gibbs free energy changes for the chemical reactions in the roasting processes were calculated; the thermal chemical behaviors and the mineral phases transformation were investigated using TG/DTG-DSC and XRD; and the microstructure changes with chemical composition of microregions were characterized through SEM-EDS. The thermochemical reaction characteristics for the roasting activation of tailings and sodium carbonate at different temperatures were as follows: at 450–650 °C, the ankerite, siderite and sulfide in tailings were oxidized and decomposed, while the crystal transformation of quartz and chlorite occurred; at 650–750 °C, quartz, muscovite and chlorite decomposed to form soluble sodium silicate, sodium aluminum silicate, diopside, sodium ferrite and copper ferrite etc; at 750–800 °C, due to the increase in products with low melting point, the roasted samples melted. During the roasting processes, the surface of minerals depressed and the structures were destroyed. These results can provide a theoretical foundation for thoroughly resource utilization of tailings.