Silica Solubilization Potential of Certain Bacterial Species in the Presence of Different Silicate Minerals

Silicate solubilisng bacteria (SSB) are distributed in soil, water, aquatic sediments and in silicate minerals but their population is smaller than the total bacteria indicating their uniqueness. Pond sediment showed a higher SSB with 40×10⁴ g^?1 while sugarcane field soil recorded 31×10⁴ g^?1 dry weight. SSB population in silicate minerals varied with the highest in phyto-sil followed by muscovite but very low in quartz and illite. The silicate solubilisation potential of the six isolates tested on eight minerals varied with the isolates and mineral. Magnesium trisilicate was more easily solubilised than, quartz, or muscovite. Four of the elite isolates were characterized by 16S r RNA sequencing and were found to be Bacillus flexus, B. mucilaginosus, B. megaterium and Pseudomonas fluorescens. The GC/MS analysis of organic acids produced in the medium containing feldspar and quartz by Bacillus flexus and B. muicilaginosus showed variation with the minerals. The release of silica in solution serves as a nutrient for life forms.     

The kinetic and thermodynamic analysis of ultrasound-extraction of minerals from aerial parts of white lady's bedstraw (Galium mollugo L.)

The present paper deals with the extraction of some minerals (potassium, calcium and magnesium) from ground, dried aerial parts of white lady's bedstraw (Galium mollugo L.) using an aqueous ethanol solution (50% by volume) at different temperatures (from 23 to 40 °C) in the presence and absence of ultrasound. The main goal was to establish the kinetics and the thermodynamics of the two extraction processes. A phenomenological model involving simultaneous washing and diffusion was proved for both ultrasound-assisted and silent extraction of the minerals. The minerals extraction both in the presence and the absence of ultrasound is endothermic and irreversible since the enthalpy change and the entropy change are positive in the ranges of extraction temperature applied. The Gibbs free energy change for the extraction of minerals is negative, indicating that the process is feasible and spontaneous. The minerals yield increased by a factor of 1.02–1.06 and 1.14–1.27 in the absence and the presence of ultrasound, respectively for every 10 °C rise in temperature.     

Effect of carbonate minerals on volatile matter of coals

Coals high in carbonate minerals show abnormally high VM on dmmf basis. This abnormality has been shown to be due to the presence of iron carbonate. Effects of the presence of different carbonate minerals on VM have been estimated, and a formula is advanced for estimating VM on dmmf basis of a coal having a particular distribution of carbonate minerals: $\text{VM}\text{on dmmf basis}\text{=}\text{As analysed}\text{VM ? 0.1 Ash ? 1.3 CO}{}_2\text{100 ? (MM + Moisture)}\text{× 100}$     

Low cost catalytic sorbents for NOx reduction. 1. Preparation and characterization of coal char impregnated with model vanadium components and petroleum coke ash

Spanish coal, char and activated char doped with model vanadium components (V₂O₅ and NH₄VO₃) and petroleum coke ash (enriched in V, Fe, and Ni) were prepared and characterized as potential catalytic sorbents for NO_x reduction. The phase-mineral and chemical composition, content and behavior (capture, retention, distribution, and redistribution) of transition metals, as well as morphogenesis, surface area, acid-base properties, surface active sites and oxidation-reduction transformations of the catalytic sorbents were characterized. It was found that minerals and phases such as anhydrite, calcite, clay minerals, pyrite, pyrrhotite, magnetite and fusinoid-type ingredients have a leading role for the behavior of loaded transition metals. Some original (pyrite, jarosite, shcherbinaite, coulsonite, trevorite, Ni oxide) and newly formed (pyrrhotite, magnetite, wuestite, hematite, paramontroseite, karelianite) Fe, V and Ni minerals in the catalytic sorbents are perspective redox indicators for the physicochemical conditions in such complex system. The data indicate that the V-Fe-Ni containing minerals dispersed onto and into the carbon support may be the most active catalytic sites. The preparation procedure that could provide the most favorable conditions for the production of effective and low cost catalytic sorbents for NO_x reduction is also described.     

Adsorption characteristics of superplasticizers on cement component minerals

Adsorption characteristics of various superplasticizers on portland cement component minerals were investigated. Adsorption isotherms of various types of superplasticizers and ζ-potentials of cement component minerals at the maximum adsorption of the superplasticizers were measured. The value of the adsorption isotherm was calculated from the amount of the superplasticizer adsorbed on a cement component mineral in an equilibrated solution. The maximum amounts of adsorption and the adsorption isotherms varied with types of component mineral and superplasticizer. For all types of superplasticizers, a larger amount of superplasticizer was adsorbed on C₃A and C₄AF than C₃S and C₂S. However, the equilibrated concentration of each superplasticizer at the maximum adsorption was not influenced by types of superplasticizer. Without superplasticizer, C₃S and C₂S had negative ζ-potential. On the contrary, C₃A and C₄AF had positive ζ-potential. Therefore, accelerated coagulation of cement particles might occur due to their electrostatic potentials that are opposite each other. However, all component minerals of cement had negative ζ-potential when they were mixed with any superplasticizer. Fluidity of fresh cement paste is improved due to electrostatic repulsion acting between particles.     

Identification and significance of accessory minerals from a bituminous coal

A scanning electron microscope (SEM) has been used to study the in situ accessory minerals in polished blocks and pellets of petrographically analysed samples of the Waynesburg coal (hvb). Individual grains from the low-temperature ash (LTA) of the same coal were also studied. The visual resolution of the SEM permitted the detection of submicron mineral grains, which could then be analysed by the attached energy-dispersive system. Emphasis was placed on the highly reflective grains in the carbominerite bands. Among the most abundant accessory minerals observed were rutile, zircon, and rare-earth-bearing minerals. Small (1–5 μm) particles of what may be authigenic iron-rich chromite and a nickel silicate form rims on quartz grains. The SEM also permits the observation of grain morphology and mineral intergrowths. These data are useful in determining authigenicity and diagenic alteration. Substances in density splits of LTA include authigenic, detrital, extraterrestrial magnetite, tourmaline, and evaporite (?) minerals, and a fluorine-bearing amphibole. This analytical approach allows the determination of specific sites for many of the trace elements in coals. In the Waynesburg coal, most of the chromium is in the iron-chromium rims, the fluorine is in the amphibole, and the rare-earth elements are in rare-earth-bearing minerals. The ability to relate trace-element data to specific minerals will aid in predicting the behaviour of elements in coal during combustion, liquefaction, gasification, weathering, and leaching processes. This ability also permits insight into the degree of mobility of these elements in coal and provides clues to sedimentological and diagenetic conditions.     

Study on the hydration of Ba-bearing calcium sulphoaluminate in the presence of gypsum

A new series of Ba-bearing calcium sulphoaluminate minerals are synthesized by a different equivalent of Ba²⁺, replacing Ca²⁺ in the C₄A₃S?. By means of XRD, IR, SEM, etc, we studied the hydration of minerals in the presence of a certain amount of gypsum. The hydrates are AFt, BaSO₄, and Al(OH)₃ gel. This paper gives the reason for early strength and rapid hardening of Ba-bearing calcium sulphoaluminate cement.     

Mineral content in fishes in the lower course of the itapecuru river in the state of Maranhão,Brazil

Concentrations of calcium, iron, potassium, magnesium, phosphorus, zinc, copper, selenium and nickel were determined in the muscle tissue of seven species of fish (Plagioscion squamosissimus, Geophagus surinamensis, Prochilodus lacustres, Curimata sp., Schizodon dissimilis, Ageneiosus ucayalensis and Hypostomus plecostomus) collected from the lower course of the Itapecuru River in the state of Maranhão, Brazil. The samples were digested in a nitricperchloric solution and analyzed using an inductively coupled plasma atomic emission spectrometer, with the construction of specific calibration curves for each element. The highest concentrations of constituent minerals were found for phosphorus, potassium, nickel and magnesium (399.83, 144.60, 90.20 and 29.49 mg 100 g^?1, respectively) in G. surinamensi, P. lacustres and Curimata sp. The lowest concentrations were found for copper, zinc, iron and selenium (0.12, 0.51, 1.05 and 8.31 mg 100 g^?1, respectively) in Curimata sp., S. dissimilis, A. ucayalensis and P. squamosissimus. The concentrations of all minerals can be considered low and are below the maximum limit established by Brazilian legislation for the human ingestion of fish meat. A comparison of the seven species of fish investigated revealed no statistically significant differences regarding the concentrations of minerals, suggesting that size and different dietary habits do not exert an influence on absorption. The low concentrations of metals, such as Fe, Cu, Zn and Ni, may be related to the environmental conditions of the mouth of the river, which receives ocean inputs that produce particular tide cycles with a strong dispersion capacity, thereby diminishing residence time in the water column and reducing the availability of these metals to species of fish.     

Nectar Minerals as Regulators of Flower Visitation in Stingless Bees and Nectar Hoarding Wasps

Various nectar components have a repellent effect on flower visitors, and their adaptive advantages for the plant are not well understood. Persea americana (avocado) is an example of a plant that secretes nectar with repellent components. It was demonstrated that the mineral constituents of this nectar, mainly potassium and phosphate, are concentrated enough to repel honey bees, Apis mellifera, a pollinator often used for commercial avocado pollination. Honey bees, however, are not the natural pollinator of P. americana, a plant native to Central America. In order to understand the role of nectar minerals in plant—pollinator relationships, it is important to focus on the plant’s interactions with its natural pollinators. Two species of stingless bees and one species of social wasp, all native to the Yucatan Peninsula, Mexico, part of the natural range of P. americana, were tested for their sensitivity to sugar solutions enriched with potassium and phosphate, and compared with the sensitivity of honey bees. In choice tests between control and mineral-enriched solutions, all three native species were indifferent for mineral concentrations lower than those naturally occurring in P. americana nectar. Repellence was expressed at concentrations near or exceeding natural concentrations. The threshold point at which native pollinators showed repellence to increasing levels of minerals was higher than that detected for honey bees. The results do not support the hypothesis that high mineral content is attractive for native Hymenopteran pollinators; nevertheless, nectar mineral composition may still have a role in regulating flower visitors through different levels of repellency.     

Properties of Ulug Khem Coal. 1. Types of vitrinite and its associations with microcomponents and minerals

A review of research on Ulug Khem coal between 1951 and 2013 shows that its properties are largely determined by the plant material from which it is formed. This results in different types of vitrinite in Ulug Khem coal, with differences in clinkering properties, vitrinite reflectance, and yield of volatiles. Detailed petrographic analysis of coal from the Ulug bed in the Mezhegei deposit shows numerous associations of collinite with telinite and of telinite with bitumenite and also numerous associations of vitrinite with minerals. Thanks to the different properties of different types of vitrinite in Ulug Khem coal, the different associations of vitrinite with minerals, and the high ash basicity, coke produced from batch containing Ulug Khem coal will be characterized by low CSR and high CRI. That finding will be discussed in part 2.     

Substituting non-natural agents in UV-protection cream by a mixture of clay with Ganoderma pfeifferi extract

To investigate the potential of substituting non-natural agents in sunscreen, mixtures of some clays with Ganoderma pfeifferi extract were examined in regard to their protection abilities against ultraviolet (UV) radiation in the wavelength range 250–400 nm. Some mixtures showed remarkably high UV-protection potential in comparison with corresponding clay cream devoid of the fungal extract. Depending on interlayer charge of the dominant clay mineral contained in the clays, the interaction between the fungal extract and the clay mineral played a key role in the UV-protection ability of the mixtures. The optimal clay in the mixture with the G. pfeifferi extract for sunscreens was dominated by expandable clay minerals with low interlayer charge.     

Distribution of inorganic and organic substances in the hydrocyclone separated Slovak sub-bituminous coal

A low-rank Slovak sub-bituminous coal from the Handlová deposit was physically treated by washing in a water-only cyclone with the goal to find the separation effect for inorganic (mainly Fe-bearing minerals) and organic substances (humic acids, diterpanes). A high-quality coal product with the ash content in the dry matter of 9.02% and carbon content of C^d = 68.12% at a mass yield of 29.51% was obtained using the water-only cyclone processing. At first, the physically treated coal samples were detailed characterized by XRD, ⁵⁷Fe Mössbauer spectroscopy, FT-IR and HR-TEM. In addition to non-crystalline organic coal components, inorganic compounds belonging to silicate minerals (kaolinite, muscovite and quartz) as well as to Fe-bearing sulphide minerals (pyrite) were identified in the sub-bituminous coal by XRD. ⁵⁷Fe Mössbauer spectroscopy detected the presence of iron carbonate (siderite), iron-containing clay mineral and two sulphur-containing minerals (pyrite, jarosite) in the untreated coal. On the other hand, only one Fe-bearing mineral, (pyrite) was found in the washed coal. Effect of the physical separation is also demonstrated in FT-IR spectra, where the peak at 1040 cm⁻¹ representing the silicate component in the untreated sample is not detectable in the washed coal sample. Presence of extractive organic substances, i.e. humic acids and tetracyclic diterpane (16α(H)-phyllocladane), in the hydrocyclone products is also evidenced. It was confirmed that the isolated diterpenoic compound is attendant in the washed product with the lowest ash content and it is assimilated with the organic part of coal. Surprisingly, humic acids were found in the highest concentration in the slurry that has the highest content of ash (63.14%).     

Interactions between oil shale and its semi-coke during co-combustion

In the present work, thermogravimetric analysis was employed to investigate the interactions between oil shale and its semi-coke during co-combustion process. During the test, the blends of semi-coke and oil shale were prepared at different blending ratios of 1:0, 4:1, 3:1, 2:1, 1:1, and 0:1. The results indicated some interactions were detected between oil shale and semi-coke during the tests. The rapid combustion of organic matter in oil shale, which led to the fuel particle temperature’s rapid increase and made semi-coke ignite in advance, improved the co-combustion characteristics in terms of ignition temperature (T_i), the temperature reaching the maximum mass loss rate (T_max), the maximum mass loss rate (R_max), the combustibility index (C) and the specific reactivity of the co-combustion. With the increase in semi-coke mass fraction in the blends, the specific reactivity of the samples was found to decrease gradually due to lower volatile content and high carbon condensation structure in semi-coke. As the temperature increased, the specific reactivity of the samples first gradually increased, then decreased attributed to the oxidation of selectivity. The poor diffusion caused mainly by the ash shells made the decomposition of minerals more complicated. It was also analyzed that the ‘particle groups’ phenomenon that the dispersed particles are agglomerated by some forces in semi-coke ash went against the decomposition of minerals.Activation energies E from distributed activation energy (DAEM) slowly decreased at the initial stage, then increased sharply over a narrow conversion region, which indicted a difficult burnout stage. Meantime, a power law model was employed to investigate quantitatively the interactions. The experimental reaction orders could be predicted accurately from the calculated values. At the third stage, the kinetic parameters E₃ and A₃ were almost as much as the calculated values. At the low temperature region (470-540 °C), there was little difference between kinetic parameters E and A from the experiment data and the calculated data.     

中国非金属矿产概况

地质勘查工作表明我国是一个非金属矿产资源比较丰富和品种比较齐全的国家。已对80余种非金属矿和5000余处矿产地进行过普查勘探工作并探明储量,有些矿种探明的储量居于世界前列,具有一定的资源优势。对水泥、玻璃和陶瓷原料,冶金熔剂,耐火材料原料,化工原料的磷、硫和其它若干种大宗的非金属矿产,不仅基本上保证了以往社会主义建设需要,同时也为本世纪发展国民经济和外贸出口所需作了一定的准备。本文将我国主要非金属矿产划分为四类,即:(1)具有优势的非金属矿产;(2)资源丰富,开发利用不多的非金属矿产;(3)有较好资源远景或潜在优势的非金属矿产;(4)资源一般,尚有短缺的非金属矿产。     

Low temperature air oxidation of n-alkanes in the presence of Na-smectite

This paper is the continuation of a study concerning the catalytic effects of clay on organic matter and especially n-alkanes during oxidation carried out at low temperature. The influences of clay minerals were investigated to understand their role better during natural oxidation of organic matter.n-Alkanes oxidation experiments in presence of Na-smectite were carried out at 100 °C during 512 h and reveal an important production of oxygen-bearing molecules to the detriment of initial n-alkanes. Thus, Na-smectite allows to initiate the auto-oxidation of n-alkanes due to its chemical (charged sheets) and/or physical (high specific area) properties. The evolution of oxygen-bearing molecules distribution enables to distinguish two competitive chemical pathways. On one hand, alcohols and ketones are produced with an aliphatic chain length similar to the starting n-alkanes. On the other hand, aliphatic chain cleavages occur and principally produce 1-alcohols, 2-ketones, carboxylic acids and 3-substitued γ-lactones. These oxygen-bearing compounds are more and more preponderant and evidence the fact that cleavage mechanisms become progressively dominant.     

The application of the f.m.r. technique to coal characterization studies

The mineral magnetite has been detected in a sample of Pittsburgh No. 8 coal by the ferromagnetic resonance technique. The magnetite particles contained in a ground sample were < 0.07 μm diameter and have a chemical composition between Fe_2.98804O₄ and Fe_2.99704O₄. The results of acid treatment indicated that the magnetite is not embedded in the organic coal material, but is readily removed. The use of the f.m.r. technique as exemplified in the present work has important potential in the study of ferro-and ferrimagnetic minerals in raw coal and their interactions with paramagnetic organic free radicals during coal conversion processes.     

Development and verification of a mathematical model for variations of the specific surface area of mineral powders during intensive milling

In order to describe temporal evolution of BET surface area of a mineral substance during an intensive milling process, a mathematical model in the form of S = a + b e^? mt + c e^– nt has been developed based on well-established phenomena in mechanical activation processes. Validity of the proposed model was verified by the results of experiments performed on a natural chalcopyrite mineral as well as those reported in the literature on a variety of sulfide minerals. It was shown that the model could fit different types of surface area variation with a very good accuracy.     

Mechanism of Selective Flotation of Sodium-Calcium Borates with Anionic and Cationic Collectors

Abstract

The major boron minerals, colemanite and ulexite, are frequently found together in boron deposits. Similarities in their chemical compositions create problems in the selective flotation of these minerals. The surface properties of the above boron minerals have been determined by solubility, microflotation, and zeta potential measurements using typical anionic and cationic surfactants. The isoelectric point (iep) of colemanite is 10.5, while ulexite exhibits no iep in a practical pH. Anionic surfactants thus easily float colemanite but fail to float ulexite at a natural pH. This knowledge is used to find the optimum conditions for the selective separation of colemanite from ulexite at a natural pH of 9.3. Cationic surfactants work well but are adversely affected by the presence of clay-type minerals in the boron ore which hinder the floatability of borates by the formation of a slime coating. The mechanism of slime coating onto boron minerals is also elucidated.     

Chemistry and structure of coals: Diffuse reflectance i.r. spectroscopy equipment and techniques

Diffuse reflectance infrared spectroscopy (DRIS) is used to obtain high quality data on the chemistry and structure of coals and related materials. Minimum sample preparation is required to form a diffusely reflecting surface thus saving time and minimizing structural and chemical modifications. Controlled environment chambers are used to study atmospheric effects and/or in-situ reactions (hydration/dehydration, oxidation/ reduction, derivatization, etc.) of coals and inherent, secondary and/or added minerals. Quantitative measurements of the mineral content may be made either by measured addition or by weighted spectral subtraction. Detailed study of in-situ oxidation gives the concentration of the intermediate transient states of hydrocarbon loss. The progressive insertion of oxygen into aromatic rings to give steady state levels of slow char burning can also be revealed. DRIS is a simple, fast, versatile and informative method for coal analysis.