Complex Mineral Composition Research Articles

Investigation of Pore Structure and Water Imbibition Behavior of Weakly Cemented Silty Mudstone

Water‐rock interaction of weakly cemented mudstone is intense due to its complex pore structure and mineral compositions. As primary channels for water imbibition, pore structures determine water migration. In this paper, pore properties of weakly cemented mudstone are measured by scanning electron microscopy (SEM), nitrogen adsorption/desorption (NAD), and mercury intrusion porosimetry (MIP), respectively. Water imbibition tests under free and lateral restraints are performed on self‐developed water absorption instruments. The results show that skeleton aggregates, pore zone, and fissure zone constitute the basic structure of the rock, together with pore scales in nanoscale, submicron‐scale, and micron‐scale, respectively. The porosities of each zone are inferred with the values of 13.5%, 7.3%, and 2.3% by comparison of different methods. The main pore type is mesopore. Based on water imbibition tests, water rises along the large fissure and pore zones initially. Pores in the skeleton aggregates absorb water from pore and fissure zones subsequently. However, water imbibition is limited under lateral restraints. Owing to lateral restraints, the ascending height and rate of the sample with lateral restraints are lower than those of the sample with free confinements. The results suggest that lateral restraints can restrain water migration and water‐rock interaction for weakly cemented mudstones, and measures can be taken to control swelling deformation by strengthening lateral restraints.

Simulation of Acid–rock Heterogeneous Flow Reaction Based on the Lattice Boltzmann Method

Matrix acidizing is an essential strategy to maintain or increase the productivity or injectivity of hydrocarbon wells. However, for sandstone reservoirs, the heterogeneous flow reaction mechanism of acid–rock in porous media is very complex because of their complex mineral and chemical compositions. It is often difficult to match real formation conditions by experimental simulation. Also, traditional numerical simulation methods have the disadvantages of complex boundary processing and low computational efficiency. In this study, the lattice Boltzmann method (LBM) was used to establish the heterogeneous flow reaction model of acid–rock from a new perspective, which was solved by MATLAB to obtain the distribution of temperature, concentration of various substances, porosity, and permeability. The simulation results indicate that with increases in injection time and injection speed, the temperature and mass transfer distance of the acid will also increase. Changing the injection time had a more obvious influence on the transfer of temperature and mass than did changing the injection speed. The increasing rates of porosity and permeability in the middle of the flow channel were the highest. The fast-reaction mineral content, hydrofluoric acid injection concentration, and acid injection time had a great influence on the acidizing effect, whereas the slow-reaction mineral content, acid injection temperature, and injection speed had little influence on the acidizing effect. The results suggest that to improve the acidizing effect, priority should be given to improve the HF concentration and acid dose. It will be important for further guiding the optimization of acidizing process design parameters.

Comparative Study on Shale Characteristics of Different Sedimentary Microfacies of Late Permian Longtan Formation in Southwestern Guizhou, China

Organic-rich marine-continental transitional shales are widely distributed in Guizhou Province, China. Samples from the Late Permian Longtan Formation were investigated using organic petrography analysis, X-ray diffraction (XRD) analysis, field emission-scanning electron microscopy observations, mercury intrusion capillary pressure and gas adsorption experiments to better understand the organic geochemical characteristic, mineralogical composition, full-size pore structure characteristics and fractal characteristic of shale reservoir. The relationships among the total organic carbon (TOC) content, mineral composition, pore structure parameter, methane adsorption capacity and fractal dimension of shale samples are discussed, along with the differences between different sedimentary microfacies. Results show that shale samples are characterized by high TOC contents, low permeability, complex mineral composition and pore structure. Shales of YV-1, deposited in delta and lower delta plains, have an extreme high clay content (71.33% average) and the clay minerals mainly consist of the I/S and kaolinite, while shales of XD-1, deposited in the lagoon-tidal flat, have a relatively low clay content (37% average) and the I/S occupies an absolute advantage. The pore volume, specific surface area and average pore diameter of YV-1 (0.02881 cm3/g, 20.806 m2/g and 11.07 nm, respectively) are larger than that of XD-1 (0.02110 cm3/g, 20.101 m2/g, and 8.40 nm, respectively). The mesopore of YV-1 is the predominant contributor to the pore structure, while the micropore of XD-1 also occupies a certain proportion in addition to the mesopore. Organic matter (OM)-hosted pores are largely developed in XD-1 samples, while clay mineral-hosted pores dominate the pore system of YV-1. Shale samples with higher TOC content and clay content generally have larger specific surface area and pore volume, which provides more adsorption space and enhances pore structure heterogeneity. Samples of XD-1 have high TOC contents, suitable mineral composition and complex pore structure, suggesting that shales deposited in a lagoon-tidal flat environment may have a greater potential for shale gas development.

Sulfate-induced degradation of cast-in-situ concrete influenced by magnesium

In this paper, the results of laboratory tests performed to investigate the effects of magnesium on concrete deterioration and sulfate diffusion in cast-in-situ concrete samples are reported. Concrete samples were prepared and then fully or partially immersed in two different corrosive solutions consisting of either sodium sulfate or magnesium sulfate. For a period of 12 months, the sample dimensions, mass, the sulfate concentration in the specimens and the compressive strength were continuously monitored. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), thermogravimetry-derivative thermogravimetry (TG/DTG) as well as differential scanning calorimetry (DSC) were used to analyze the microstructure and the complex mineral composition of the concrete after exposure to the corrosive environments. Results indicate that increasing the sulfate concentration in the immersion solutions accelerated the degradation of all tested concrete specimens. Partially immersed concrete samples underwent more severe attack, with both chemical attack and crystallization effects observed, when compared with fully immersed samples. The strength development of both the fully and partially immersed concrete samples in the early stages was delayed by the magnesium present in the sulfate solution. However, the presence of magnesium slowed down the degradation of concrete due to sulfate attack and inhibited the cracking and spalling of the concrete surface near the immersion level in the late degradation stage. Moreover, the existence of magnesium slowed down the sulfate diffusion process and consequently the sulfate attack.

Иерархическая структура нанопористости мексиканских природных цеолитов типа клиноптилолит

Актуальность исследования обусловлена большим количеством вновь открытых цеолитовых месторождений в Мексике. Для практического использования этих материалов требуются соответствующие экспериментальные модели, обеспечивающие достоверные и пригодные к использованию данные по каждому из заявленных месторождений. Основной целью работы является оценка адсорбционной способности природных клиноптилолитных цеолитов из различных месторождений Мексики для оценки их нанопористости и наличия в них мезопористых пустот. Объектами исследования являются цеолитовые туфы семи различных месторождений, расположенных в Мексике. Эти отложения слабо изучены и характеризуются сложным минеральным составом пород. Методы исследования: цеолиты изучены методами рентгеноструктурного анализа, сканирующей электронной микроскопии, энергодисперсионной спектроскопии, термогравиметрии и дифференциальной сканирующей калориметрии. Все образцы были также изучены методом адсорбции N 2 для оценки площади поверхности всех исследованных цеолитов методом БЭТ, Ленгмюра и t-графиков. Общий объем пор оценивали в соответствии с правилом Гурсвича. Микропористость этих природных цеолитов измерялась методом адсорбции высокого разрешения с применением теории объемного заполнения микропор Дубинина-Астахова (D-A). Информация о распределении размеров микропор получена по данным изотермической адсорбции-десорбции. Результаты. Нанопористость природных клиноптилолитных цеолитов из новых месторождений изучена традиционными экспериментальными методами, такими как DRX, SEM, EDS и HRADS N 2 при температуре кипения жидкого азота. Последним методом определены параметры текстуры, в которых микропоры оцениваются по t-графикам. Распределение нанопор определено с использованием недавно предложенного приближения, называемого дифференциальными кривыми адсорбции. Исследования методами термогравиметрии и дифференциальной сканирующей калориметрии показывают наличие трех типов адсорбированной воды: адсорбированной воды в макропорах, воды, адсорбированной во внешней области цеолита (мезопоры), и воды, адсорбированной в микропорах. Такое поведение подтверждается адсорбцией N 2 : микропористым заполнением, многослойным заполнением на внешней поверхности цеолитового туфа и проявлением капиллярной конденсации, возникающей в макропорах.

Experimental investigation of the effects of clay content and compaction stress on the elastic properties and anisotropy of dry and saturated synthetic shale

Anisotropy in shales is an important issue in exploration and reservoir geophysics, and it has been proven extremely difficult to correlate anisotropy in natural shale by means of a single variable (in this case, clay content or compaction stress) because of the influence of multiple factors, such as water content, total organic carbon content, and complex mineral compositions. Thus, we used quartz, kaolinite, calcite, and kerogen extract as the primary materials to construct two sets of synthetic shale samples, each with a different clay content by weight and a different compaction stress. Ultrasonic experiments were conducted to investigate the anisotropy of velocity and mechanical properties in dry and saturated samples of our synthetic shales. The results reveal that the velocities decrease with clay content by weight and increase with compaction stress and that these changes are significant at low compaction stress. The velocity anisotropy of the samples increases with clay content and compaction stress due to the increasing alignment of the clay platelets. S-wave anisotropy is more sensitive to the clay content or compaction stress than P-wave anisotropy. The dynamic Young’s modulus [Formula: see text] of the samples decreases with clay content and increases with compaction stress, whereas Poisson’s ratio [Formula: see text] increases with clay content and decreases with compaction stress. Young’s modulus perpendicular to the symmetry axis is always larger than that parallel to the symmetry axis, but Poisson’s ratio perpendicular to the symmetry axis may be larger or smaller than that parallel to the symmetry axis, which indicates that mechanical properties have obvious anisotropic behavior. The elastic properties and anisotropy are also affected by fluids; the values of elastic and mechanical anisotropy parameters in saturated samples are significantly lower than those in dry samples.

Pre-Concentration of Iron-Rich Sphalerite by Magnetic Separation

With the rise in metal prices and the growing importance of metallic minerals in the South Korean economy, there has been a steadily increasing demand to redevelop metal mines that have been shut down since the 1990s. However, it is not possible to ensure that such plans are economically feasible by using conventional mining processes, mainly flotation, because of low ore grade and complex mineral compositions. To improve the efficiency, and to reduce the operating cost of the entire process, pre-concentration by magnetic separation of Pb–Zn deposits has been investigated to reduce the mass and improve the grade of feed samples that are loaded into the flotation system. The results show that the response of sphalerite to magnetic separation varied as a function of its iron content: iron-rich sphalerite was recovered at magnetic intensities below 0.65 T, and relatively pure sphalerite was recovered at magnetic intensities above 0.85 T. Therefore, Pb–Zn ore could be sufficiently pre-concentrated by magnetic separation between 0.65 and 0.85 T to remove low-grade target elements. As a result, the mass of the sample fed into the flotation system was reduced almost by half, and the grade of zinc, lead, and copper was enhanced by 65%, 55%, and 33%, respectively. Therefore, it is possible to improve the efficiency of the entire process by reducing the amount of the sample to be fed to subsequent processes, such as grinding and flotation, while minimizing loss of the target mineral through magnetic separation.

Model Predictive Control of Mineral Column Flotation Process

Column flotation is an efficient method commonly used in the mineral industry to separate useful minerals from ores of low grade and complex mineral composition. Its main purpose is to achieve maximum recovery while ensuring desired product grade. This work addresses a model predictive control design for a mineral column flotation process modeled by a set of nonlinear coupled heterodirectional hyperbolic partial differential equations (PDEs) and ordinary differential equations (ODEs), which accounts for the interconnection of well-stirred regions represented by continuous stirred tank reactors (CSTRs) and transport systems given by heterodirectional hyperbolic PDEs, with these two regions combined through the PDEs’ boundaries. The model predictive control considers both optimality of the process operations and naturally present input and state/output constraints. For the discrete controller design, spatially varying steady-state profiles are obtained by linearizing the coupled ODE–PDE model, and then the discrete system is obtained by using the Cayley–Tustin time discretization transformation without any spatial discretization and/or without model reduction. The model predictive controller is designed by solving an optimization problem with input and state/output constraints as well as input disturbance to minimize the objective function, which leads to an online-solvable finite constrained quadratic regulator problem. Finally, the controller performance to keep the output at the steady state within the constraint range is demonstrated by simulation studies, and it is concluded that the optimal control scheme presented in this work makes this flotation process more efficient.

New reagent formulations for selective flotation of scheelite from a skarn ore with complex calcium minerals gangue

The approach using synergistic effects of the blend of carboxylic collectors was applied to process the Tabuaco tungsten skarn ores (Portugal) by flotation. However, a very complex mineral composition with high amounts of the fluorite (>10%) and apatite (3–5%), as well as the presence of more than 40% of vesuvianite, a silicate of calcium, implied that such separation is highly challenging. In this work, the influence of sodium silicate and sodium carbonate on the selective flotation of scheelite has been investigated. A study of depressants dosage allowed to reach a selective flotation of scheelite from calcium minerals at 1125 g/t, except from fluorite. The use of sodium carbonate with sodium silicate showed synergistic effects, increasing the WO3 grade from 6.6% to 11.2% without impacting the recovery. Collector formulations were created in the laboratory by mixing the commercial fatty acids, in which oleic and linoleic acid predominated, in various proportions with rosin acids while the ratio between oleic and linoleic acids was kept constant. The tungsten recovery increased significantly, up to 98%, with the amount of rosin acids in the mixture while the concentrate grade decreased from 16% WO3 grade to 10.5% WO3 grade impacting the selective flotation of scheelite from an ore with 0.9% WO3 grade. The optimal ratio of fatty and rosin acids was then experimentally set to 5/1-6/1. An unprecedented increase of the flotation selectivity between scheelite and fluorite was obtained when the saturated acids were introduced in the formulation. The concentrate grade reached 27% WO3 grade for the same ratio between anionic reagents. Thus, the new reagent formulation allowed to obtain a tungsten concentrate after only one cleaner stage without additional use of thermal treatment or activating heavy metals salts or specific depressants.

Intrusion-related Lang Vai gold-antimony district (Northeastern Vietnam): Geology, mineralogy, geochemistry and 40Ar/39Ar age

The Lo Gam domain is one of the most important areas for metallogenic studies in northeastern Vietnam. The Lo Gam domain comprises numerous Pb-Zn deposits and occurrences, which account for >80% of the Pb and Zn resources in Vietnam. Furthermore, within the Lo Gam domain, there are several gold, antimony, and base metal deposits. The largest of these are the Lang Vai, Khoun Puc, and Lung Luong deposits, which are included in the Lang Vai ore district. Each of the deposits includes several ore zones and ore bodies with peculiar mineral compositions and geochemical features. The geological and structural settings show that the Khoun Puc, Lang Vai, and Lung Luong deposits represent a uniform ore system. The metal zoning in the Lang Vai district occurs laterally away from a granitic intrusion. A general paragenetic sequence for the three deposits may be represented by the following mineral associations (from early to late): (i) arsenopyrite, pyrite, native gold, sphalerite; (ii) Bi-rich Pb-Sb sulfosalts; (iii) Bi-poor Pb-Sb sulfosalts; (iv) Sb sulfosalts; (v) Sb-rich minerals, native antimony; and (vi) Pb-rich Sb sulfosalts (as a distal mineral association). Among the different types of mineralizations, there is exists a transient mineralization that is characterized by a complex mineral composition. Bi-bearing minerals have been found only in the Khoun Puc deposit, which is located near a granite stock, whereas Bi mineralization is absent away from the deposit. The general outward sequence of zoning is from Au-As-Bi to Au-As-(Sb) to Sb-(Au-As) to Pb-Sb at the periphery. The ages of mineralization at the Lang Vai and Lung Luong deposits have been estimated to be ca. 240 Ma and ca. 236 Ma, respectively, and are slightly younger than the earlier reported ages (ca. 254–245 Ma) of the Phia Bioc granite complex, indicating a possible genetic relationship between the mineralization and the intrusions. The geological characteristics, metal zoning patterns and new geochronological data suggest that the gold-antimony ores in the Lang Vai district are genetically related to the nearby granitic intrusions.

Ultrasonic velocity and mechanical anisotropy of synthetic shale with different types of clay minerals

Clay minerals are the most abundant materials in shale. Their presence significantly influences the elastic behavior of reservoir rocks as a function of mineral type, volume, and distribution, and their orientation controls the shale’s intrinsic anisotropic behaviors. Thus, knowing the elastic properties of shale with different types of clay minerals is imperative for fully understanding the seismic properties of the reservoir. However, it is extremely difficult to measure the elastic properties of natural shale by means of a single variable (in this case, the type of clay), due to the influences of multiple factors, including water, total organic carbon content, complex mineral composition, and so on. Thus, we use quartz, clay (kaolinite, illite, and smectite), carbonate, and kerogen extract as the primary materials to construct synthetic shale with different types of clay. Ultrasonic experiments were conducted to study the anisotropy of velocity and mechanical properties (Young’s modulus and Poisson’s ratio) in dry synthetic shale samples as a function of applied axial stress. The results show that the velocity of samples increases with applied pressure and the rate of velocity increase is higher at low pressures. Similarly, the dynamic Young’s modulus and Poisson’s ratio increase with applied pressure; [Formula: see text] is always larger than [Formula: see text], but [Formula: see text] may be larger or smaller than [Formula: see text]. Furthermore, velocity anisotropy and mechanical anisotropy decrease with the increase of stress and are sensitive to stress and lithology. The closure of large aspect-ratio pores (and/or microcracks) seems to be a dominant mechanism controlling the change of anisotropy. Finally, the changes in mechanical anisotropy under applied stress are larger compared with the changes in velocity anisotropy, indicating that mechanical properties are more sensitive to the changes in rock property.

Valorizacija kompleksne polimetalične rude iz ležišta 'Čoka Marin'

The complex polymetallic deposit 'Čoka Marin' has been explored over many years. Due to its complex mineral composition and primarily a high content of precious metals it represents a particular challenge for mining experts. Over the past few years preparatory works for the ore body Čoka Marin-1 have been intensified to provide necessary conditions to excavate and prepare the ore in the Majdanpek Flotation Plant for further metallurgical processing of the collective concentrate. The new methods that were investigated to smelt the collective copper concentrate with precious metals opened new possibilities for ore valorization. This paper presents a detailed analysis of various ore excavation methods that may be applied in the 'Čoka Marin' Deposit along with the stability analysis. Further on, the results of detailed mineralogical analysis are given to show particularly the manner in which the precious metals appear. Finally, the paper presents the research results and different possibilities of ore concentration flotation processes.

Comparative study of nanoscale pore structure of Lower Palaeozoic marine shales in the Middle‐Upper Yangtze area, China: Implications for gas production potential

The Lower Cambrian Niutitang and Lower Silurian Longmaxi shales in the Middle‐Upper Yangtze area are considered the primary shale gas units targeted for development in China. To shed some light on the difference in nanopore structures between Niutitang and Longmaxi shales, systematic comparative investigations were conducted using various techniques, including geochemical analyses, field emission scanning electron microscopy (FE‐SEM), high‐pressure mercury intrusion porosimetry (MIP), and low‐pressure N2/CO2 adsorption techniques. The results show that both Niutitang and Longmaxi shales have high total organic carbon (TOC) content and complex mineral compositions. The porosity of Longmaxi shales is higher than that of Niutitang shales, with an average value of 3.26% and 2.04%, respectively. Interestingly, for both shale formations, the mesopores (2–50 nm) are the major contributors to pore volumes, whereas the specific surface area is dominated by micropores (<2 nm). For the mesopore size distributions (PSDs) calculated from the N2 adsorption, the Longmaxi shales have a dominant pore size ranging from 10 to 60 nm. In contrast, there are more fine mesopores (2–8 nm) in the Niutitang shales. Furthermore, we found that numerous nanoscale pores are well‐developed within graptolite‐derived organic matter (OM) in the Longmaxi shales. These interconnected graptolite periderm pore systems may not only provide a storage space for both adsorbed and free gas but also serve as pathways for gas transport. The Niutitang shales developed relatively fewer OM pores with smaller diameters, lower OM surface porosity, and lower connectivity compared to the Longmaxi shales. The differences in OM pore structure partly explain why there is a large production difference between these two formations.

Processing of coal fly ash magnetic spheres for clay water flocculation

The application of coal fly ash magnetic spheres (MSs) in water treatment is limited due to their complex mineral compositions, low magnetism, and large diameters. In this study, MSs were carefully ball milled and magnetically separated to improve their related properties. After the processing, the resultant magnetic ball-milled MSs (MBMSs) show a substantial change in composition, magnetism, and surface property in addition to a decrease in diameter. Compared with those of the original MSs, the Fe percentage, magnetism, and specific surface area of MBMSs are increased by 25.87%, 54.60%, and 810%, respectively. Dispersive spectrometer mapping investigation shows segregated high- and low-Fe areas with different structures in MS. These different structures enable purification. Highly turbid clay water flocculation experiments using MSs as flocculants indicate that MBMSs can cause fast flocculation whereas the compared samples exert less or slight flocculation effect. Zeta potential investigation suggests that the different flocculation effects are due to the change in the point of zero charge (pHPZC). The pHPZC increases from 3.91 for the original MS to 4.96 for MBMS. The reduction in the diameter, as well as the increase in magnetism, surface area, and pHPZC, makes MSs applicable to water treatment.

Identifying Toxic Impacts of Metals Potentially Released during Deep-Sea Mining—A Synthesis of the Challenges to Quantifying Risk

In January 2017, the International Seabed Authority released a discussion paper on the development of Environmental Regulations for deep-sea mining within the Area Beyond National Jurisdiction (the ‘Area’). With the release of this paper, the prospect for commercial mining in the Area within the next decade has become very real. Moreover, within nations’ Exclusive Economic Zones, the exploitation of deep-sea mineral ore resources could take place on very much shorter time scales and, indeed, may have already started. However, potentially toxic metal mixtures may be released at sea during different stages of the mining process and in different physical phases (dissolved or particulate). As toxicants, metals can disrupt organism physiology and performance, and therefore may impact whole populations, leading to ecosystem scale effects. A challenge to the prediction of toxicity is that deep-sea ore deposits include complex mixtures of minerals, including potentially toxic metals such as copper, cadmium, zinc, and lead, as well as rare earth elements. Whereas the individual toxicity of some of these dissolved metals has been established in laboratory studies, the complex and variable mineral composition of seabed resources makes the a priori prediction of the toxic risk of deep-sea mining extremely challenging. Furthermore, although extensive data quantify the toxicity of metals in solution in shallow-water organisms, these may not be representative of the toxicity in deep-sea organisms, which may differ biochemically and physiologically and which will experience those toxicants under conditions of low temperature, high hydrostatic pressure, and potentially altered pH. In this synthesis, we present a summation of recent advances in our understanding of the potential toxic impacts of metal exposure to deep-sea meio- to megafauna at low temperature and high pressure, and consider the limitation of deriving lethal limits based on the paradigm of exposure to single metals in solution. We consider the potential for long-term and far-field impacts to key benthic invertebrates, including the very real prospect of sub-lethal impacts and behavioural perturbation of exposed species. In conclusion, we advocate the adoption of an existing practical framework for characterising bulk resource toxicity in advance of exploitation.

Mineral status of reproducing ewes grazing vegetative cereal crops

Grazing vegetative wheat, barley and oats (both dual-purpose and traditional spring varieties) is becoming an important strategic and tactical grazing option on farms where crops and livestock co-exist. The high winter growth rates of the crops offer an opportunity to fill the winter feed gap and the high nutritive value (metabolisable energy and crude protein) makes them well suited to meet the requirements of reproducing ewes. However, metabolic disorders have been reported and many producers avoid grazing these crops with reproducing ewes because of the risk. The present study aimed to establish the mineral status of both forage and of reproducing ewes grazing wheat, oats or barley. On each of 18 farms, a group of 50 pregnant ewes was monitored. The farms were located in Western Australia (6 farms) southern New South Wales (7 farms) and central New South Wales (5 farms). The average start of grazing was 118 days (range 97–133 days) after the start of mating. Crops grazed were wheat (8 farms), barley (4 farms) or oats (6 farms) and the average period of grazing was 20 days (range 14–24 days). Samples of blood and urine were collected pre- and post-grazing from 11 to 17 ewes and samples of crop and soils were also collected for mineral analysis. A high proportion of farms had forage calcium (Ca, 70%), sodium (Na, 70%) and magnesium (Mg, 18%) below published requirements and potassium (K, 70%) above the published maximum tolerable level. Strong negative correlations were found between soil Colwell K and forage Ca, Mg and Na. Analysis of samples collected from the ewes at the end of the grazing period indicated that ewes on 94% of farms had alkaline urine and on 88% of farms Ca concentrations in the urine were in the marginal range. None of the flock-average Ca concentrations in plasma was in the deficient range, but 59% of the flocks contained some individual ewes with plasma Ca in the deficient range. A small proportion of flock-average concentrations of Mg (6%) and Na (18%) in plasma were in the deficient range. In conclusion, the forages had a complex mineral composition meaning that grazing ewes may have an increased risk of direct or induced Ca (hypocalcaemia) or Mg (hypomagnesaemia) deficiency. The low Na and high K concentrations of these crops may also pose a direct risk to livestock production. Preliminary analysis indicated higher risks from grazing wheat and from grazing crops grown on high-K soils.

Fertilizer for the Treatment of Iron Chlorosis Physico-chemical and agro-chemical properties

Iron chlorosis represents a physiological phenomenon with negative impact on the quality and quantity of grape production in the vineyards. The bicarbonates are considered to be the main group of compounds which immobilize the iron in the soil in forms not assimilable by the plants. The grape production in conditions of iron deficiency can be improved significantly by applying foliar fertilizers. The best result in mitigating the effects of iron deficiency were obtained by the application of the fertilizers which, in addition to a complex mineral composition, also have a content of organic matter in the form of humic substances or protein hydrolysate.

A Simple and Efficient RNA Extraction Method from Deep-Sea Hydrothermal Vent Chimney Structures.

RNA-based microbiological analyses, e.g., transcriptome and reverse transcription-quantitative PCR, require a relatively large amount of high quality RNA. RNA-based analyses on microbial communities in deep-sea hydrothermal environments often encounter methodological difficulties with RNA extraction due to the presence of unique minerals in and the low biomass of samples. In the present study, we assessed RNA extraction methods for deep-sea vent chimneys that had complex mineral compositions. Mineral-RNA adsorption experiments were conducted using mock chimney minerals and Escherichia coli total RNA solution, and showed that detectable RNA significantly decreased possibly due to adsorption onto minerals. This decrease in RNA was prevented by the addition of sodium tripolyphosphate (STPP), deoxynucleotide triphosphates (dNTPs), salmon sperm DNA, and NaOH. The addition of STPP was also effective for RNA extraction from the mixture of E. coli cells and mock chimney minerals when TRIzol reagent and the RNeasy column were used, but not when the RNeasy PowerSoil total RNA kit was used. A combination of STPP, TRIzol reagent, the RNeasy column, and sonication resulted in the highest RNA yield from a natural chimney. This indirect extraction procedure is simple, rapid, inexpensive, and may be used for large-scale RNA extraction.

Basic characteristics and evaluation of shale oil reservoirs

AbstractShale oil refers to liquid hydrocarbons existing in free, dissolved or adsorbed states in the effective source rock of mudstones or shales, where some residual oil is retained after hydrocarbon generation and expulsion from the mudstones or shales. Basically shale oil experiences no migration or only undergoes some primary, short-distance migration within the source rocks. So far, there is no consensus on the exact definition of shale oil in China. Researches on the reservoir-controlling factors and evaluation elements are also far from sufficient. In this study, shale oil reservoirs are defined as mudstones or shales excluding the interbedded or adjacent layers of coarser siliciclastic or chemical-biogenic lithofacies (e.g. siltstone, carbonate, salt or chert layers) in the source rocks. According to different reservoiring mechanisms, shale oil reservoirs are classified into “fracture type” and “matrix type”. The general features of shale oil reservoirs include: rich in organic matters, dominated by Type I and II1 kerogen (with Ro = 0.6%-1.2% and total organic content (TOC) > 2.0%), complex mineral compositions and laminated structures, tight storage space, low porosity and ultra-low permeability, and as well as the requirement for reservoir fracturing. This paper emphasizes the critical role of organic matter in the formation and evaluation of shale oil reservoirs, and its critical control on the oil generation potential and storage capacity of shale, which eventually determine the oil content and productivity of shale oil reservoirs. Besides, a set of reservoir evaluation criteria is also put forward with a focus on the TOC content, in which the threshold values of TOC are set to be 2% and 4%, and a variety of indicators are taken into account including the type and maturity of organic matter, the thickness of organic-rich shale, mineral compositions and rock types, porosity and permeability, and fracturing ability. The evaluation criteria divide shale oil reservoirs into three grades, i.e., target reservoir, favorable reservoir and invalid reservoir.

Kinetic mechanics of the reactions between HCl/HF acid mixtures and sandstone minerals

Due to the complex mineral composition and structure of sandstone rock as well as the diversity and randomness of acid-rock heterogeneous reactions, the acid-rock reaction mechanisms of sandstone acidizing are not well understood. A model that can be used to describe the kinetic reactions that occur during sandstone acidizing is needed. Based on theoretical analysis and laboratory experiments, this paper reveals the main reaction forms of hydrofluoric acid and sandstone mineral in sandstone acidizing, demonstrates that hydrochloric acid catalytic action occurs during HCl/HF mixture acid dissolving sandstone mineral, and analyzes the pattern of hydrochloric acid catalytic action. In addition, an acid-rock reaction rate mechanism model was developed using Freundlich adsorption theory. The model takes into account the combined effects of two parallel reaction processes in the reaction of mud acid dissolving sandstone mineral: (1) hydrofluoric acid directly reacting with the minerals' lattice bond and (2) hydrochloric acid adsorbed on mineral lattice surfaces and then serving as a catalyst in the reaction between hydrofluoric acid and sandstone minerals. Furthermore, kinetic experiments of HCl/HF mixture acid fluid reacting with an actual reservoir sandstone core under various formation temperatures, pressure levels, and acid shear flow conditions were carried out using a rotating disk instrument. The mapping method was used to determine the kinetic reaction parameters, and the developed acid-rock reaction rate mechanism model was used to identify the acid-rock kinetic reaction equations of sandstone formation.