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This work investigates the decomposition of K‐feldspar into analcime under alkaline hydrothermal conditions. Two types of raw materials, potassic syenite powder and microcline crystal lumps, were used for hydrothermal treatment. Research techniques of minerals alteration path simulation, powder decomposition experiments, and specific observations were conducted. Results show that K‐feldspar did not alter into analcime directly under hydrothermal conditions, and instead, hydroxycancrinite was an important intermediate. Formation route of analcime from potassic syenite powder was derived as follows: syenite dissolution → hydroxycancrinite precipitation → hydroxycancrinite assembling → reversed recrystallization → analcime, where the assembling of hydroxycancrinite into analcime‐shaped spheres was the key step for analcime formation. Above all, a novel and different to natural reaction process with feldspar decomposition and analcime formation process was proposed. [ABSTRACT FROM AUTHOR]

The source of the feldspar is found in the Late-Precambrian granitoid rocks of Al Madinah area, which covers about 2000 km2 within a 44,000 km2 area of the western part of Saudi Arabia. Petrographical and geochemical study shows that the granitic rocks have a considerable compositional range from quartz monzonite, quartz syenite, syenite, alkali granite to alkali feldspar granite. Mineralogical and petrographical results have revealed that Al Madinah granites are composed of quartz, K- feldspar, Na-plagioclase and muscovite. Geochemical data for the feldspar samples show average SiO2, Al2O3, K2O, Na2O, CaO, Fe2O3, MgO and TiO2 contents of 71.33, 13.71, 4.78, 5.93, 1.17, 1.89, 0.34 and 0.31 wt.%, respectively, while mineralogical results reveal average K-feldspar and Na-plagioclase contents of 28.53% and 39.66%, respectively. They are almost invariably composed of metaluminous, calc-alkaline and shoshonite, with respect to alumina saturation. These deposits are characterized and evaluated for their potential as a source of feldspar.

Palaeodrainage models for the mixed fluvial‐aeolian systems, which supplied detritus to Triassic basins on and offshore Britain and Ireland are well established. Basins such as those across Northern Ireland are not as well understood. Provenance studies of Triassic sandstones in the Slyne Basin offshore western Ireland and in basins west of Shetland have indicated that sediment supply was through a southward flowing fluvial system. Similar work on Triassic sandstones in the Wessex and East Irish Sea basins on and offshore Britain identified source rocks to the south supporting models, which evoke the northward flowing "Budleighensis" river system. The basins across Northern Ireland are potentially situated along the drainage divide between these two large‐scale drainage systems. K‐feldspar Pb‐isotopic analysis, apatite U–Pb geochronology and trace element geochemistry identify the Hebridean Platform, and the Scottish and Irish massifs to the north and west, respectively, and the remnant Variscan Uplands to the far south of the basins as source areas. The proportion of the northern‐ and southern‐derived detritus fluctuates several times over the sampled intervals, suggesting the dominance of drainage systems supplying sand to the basins "switched" intermittently over time. This may be due to abnormally heavy rains periodically powering the Budleighensis river system farther north or perhaps localised subsidence temporarily disconnecting Triassic basins on and offshore Britain and Ireland. The Triassic basins in Northern Ireland acted as either a major drainage divide between southern and northern river systems or as a regional sink for sediment preventing further expansion of either system. [ABSTRACT FROM AUTHOR]

Silicate rock Verdete, collected in the central region of Minas Gerais state (Brazil) and composed mostly of micas (glauconite and muscovite) and tectosilicates (Kfeldspar and quartz), was hydrothermally treated with several reactants in order to release and recover potassium. The hydrothermal products were characterized by flame photometry, XRD, XRF, SEM and EDS. Treatment with sulfuric acid was effective to break the crystal lattice of micas before 1 h of reaction and recovered 24% of potassium in the form of sulfates. The K-feldspar appears to have remained intact during the process. Treatment with a Ca(OH)2 (86 wt.%) - CaCO3 (14 wt.%) mixture did not consume the micas, but K-feldspar was gradually consumed over the 24 h reaction period. The K recovery was probably due to a concurrent hydrolytic framework dissolution of K-feldspar mediated by OH- ions and by the exchange of K+ with Ca2+. The K-bearing species are carbonaceous materials with variable K+/Ca2+ ratios, such as K2Ca(CO3)2. [ABSTRACT FROM AUTHOR]

The development of potash materials from local K-bearing resources such as aluminosilicate minerals is desirable to overcome reliance on imported fertilizers in tropical countries. However, the nutrient release from such materials follows a time-dependent profile that is not well-understood and that is significantly different if probed at agronomic or geological timescales. This work investigates the nutrient release from a calcium–aluminum–silicate-hydrate (C–A–S–H) material obtained via hydrothermal alteration of K-feldspar ore and CaO. The C–A–S–H hydrothermal material is subjected to sequential leaching cycles with diluted HNO3 (initial pH = 5), renewing the leaching solution at every cycle. X-Ray Powder Diffraction (XRD) is used to monitor changes in the material mineralogy as the leaching progresses, showing a relative increase of calcite (up to 7 wt%) and amorphous phase (up to 23 wt%). Inductively Coupled Plasma Mass Spectrometry (ICP-MS) of the leachates is used to monitor the release of K, Ca, Si and Al, and shows that the material releases K nutrient at every leaching cycle. The pH of the leachates shows that as the content of calcite in the material increases a buffering capacity at pH ≈ 9.6 is developed by the material. The mineralogy, nutrient release, and pH results presented in this study suggest a potential application of the material as a slow release fertilizer when compared to KCl. Experimental results also imply that kinetic parameters rather than solubility are more suited to describe the fertilizer value of silicate materials. [ABSTRACT FROM AUTHOR]

An optimized process of the hydrothermal treatment of potassium feldspar (K‐feldspar) and lime to obtain a potash alternative is reported. The optimization did not change a two‐key‐step process and only modified the first step, in which K‐feldspar was calcined together with calcium carbonate. However, this modified treatment greatly improved the dissolution of K‐feldspar, and the released K+Al+Si content was increased by 43 %. Phase analysis showed that new phases (i. e. leucite, larnite, and portlandite) appeared, and the structure of K‐feldspar was destroyed during calcination. After the hydrothermal reaction (i. e. the second step), many new mineral phases were generated: bütschliite, calcite, hibschite, tobermorite, and alpha‐dicalcium silicate hydrate. Therefore, the optimized product showed better physicochemical properties. In addition, the activity of lime was investigated to evaluate its effect on the hydrothermal dissolution of K‐feldspar. The optimized hydrothermal product, as a potential commodity, was evaluated from technological and environmental points of view. [ABSTRACT FROM AUTHOR]

K-feldspar–quartz vein-type Au deposits, represented by the Hadamengou super-large Au deposit, are widely developed in the Archean high-grade metamorphic terrane in the western segment of the northern margin of the North China Craton. However, the formation processes of these Au deposits have long been debated, and their genetic relationship with magmatic activity remains unclear. In this study, by examining the geological and geochemical characteristics of the Hadamengou Au deposit and several related intrusions, we find that the Au–(Mo) mineralization system may be related to Indosinian alkaline magmatic activity. The Dongshadegai and Xishadegai intrusions, which are related to the formation of the Hadamengou Au deposit, formed in an Indosinian extensional tectonic environment, and both are characterized by high silica and alkaline contents and strong oxidizing properties, indicating that the parent magmas of these intrusions were capable of dissolving and transporting metallic elements during magma formation and evolution. The Indosinian Hadamengou Au deposit contains minerals such as magnetite and barite, and the H, O, S and Pb isotopic characteristics of this deposit indicate that the ore-forming fluids originated from magmatic–hydrothermal fluids and had oxidizing properties. These observations suggest the presence of an oxidized intrusion-related Au–(Mo) mineralization system in the studied metamorphic terrane. [ABSTRACT FROM AUTHOR]

Sedimentary basins in the southeastern margin of the Tibetan Plateau yield valuable geophysical and fossil records, documenting the paleoenvironmental and biodiversity changes in the Tibetan Plateau and the Hengduan Mountains. Constraining the age of sediment deposition is fundamental in understanding the evolutionary history of biodiversity, climate (e.g. development of the monsoon), and regional landscape changes. Many basins in this area were originally considered as Miocene basins based on regional lithostratigraphic comparison and biostratigraphy, although this has been challenged recently for several basins (e.g. Lühe, Markma, Jianchuan, Wenshan and Relu basins). Here we report a new age for the Mouding Basin, Central Yunnan, China. We arrive at an early Oligocene (33 ± 1 Ma) instead of a Miocene age for the fossil-bearing strata of this basin. U Pb and 40Ar/39Ar dating of a volcanic ash layer from the Mouding Basin and one from the Lühe Basin in combination with zircon Hf isotope data suggest that the early Oligocene Laojiezi eruption is a likely source for ash layers in both basins. Fossilized dicot leaves were used to reconstruct the paleoclimate and the paleo-elevation of the Mouding Basin. This paleoclimate reconstruction indicates that the paleoclimate in the Mouding Basin closely resembles that of the Lühe Basin. The paleoclimate between the two floras is in fact more similar than their respective modern climates. During the early Oligocene, the Mouding Basin experienced colder and more humid winters with a milder monsoonal climate compared to today. Despite this, the Mouding flora exhibits high floristic similarities with its contemporary Lühe and Markam floras, as well as with the modern vegetation in southwestern China, supporting that the modernization of the biodiversity in the SE margin of the Tibetan Plateau has initiated since the Paleogene. • New zircon U Pb and K-feldspar 40Ar/39Ar ages of volcanic ash revise the 'Miocene' Mouding Basin, Yunnan, to early Oligocene. • Volcanic ash layers in the Mouding and Lühe basins are likely to originate from the Laojiezi eruption in the early Oligocene. • Time of modernization of the flora in SE Tibet began before the early Oligocene, most likely in the late Eocene. [ABSTRACT FROM AUTHOR]

Devi et al. (2022) suggested that post-violet infrared stimulated luminescence (pVIRSL; IRSL at 100 °C after a violet bleach at 50 °C) of K-feldspars, generally has a near zero athermal fading rate. This study explores the mechanism and suitability of the pVIRSL signal for dating applications. The results suggest that pVIRSL is a recuperated signal, arising from the eviction of charges in deep traps by violet stimulation followed by their recapture to the IR traps. A post-violet IR single aliquot regenerative dose (pVIR-SAR) protocol worked well for seven K-feldspar samples from varied depositional environments with ages ranging from 6 to 286 ka. The pVIRSL paleodoses of most samples, accorded with paleodoses computed using the published ages and their environmental dose rates. • Explores mechanism of Post-violet IRSL signal in K-Feldspar and role of deep traps in pVIRSL signal. • Development of pVIR-SAR protocol for paleodose estimation. • Application and comparison of pVIR-SAR protocol for natural samples with independent age controls. [ABSTRACT FROM AUTHOR]

The present work evaluated the effect of soil (S) and foliage (F) applied potassium on the growth, yield, and quality of potato plants. Potassium was added in soil at the recommended rate for all the treatments combining mineral fertilizers with K-feldspar and biofertilizers, while foliar spraying included the application of potassium citrate (PC), potassium silicate (PS), and monopotassium phosphate (MP). The obtained results showed that plant height was highest following treatment with 100% mineral potassium fertilizer under the foliar application of MP, while the content of P, K, and total carbohydrates in leaves also increased with the same fertilization treatment. On the other hand, the highest values for number of stems and fresh and dry weight per plant, as well as the highest nitrogen content in leaves, were obtained after the addition of mineral potassium fertilizer and the foliar spraying of PC, regardless of the growing season. Yield parameters were positively affected by the combination of mineral potassium fertilizers (100% or 80% K2SO4 + 20% K-feldspar + biofertilizer) and the foliar spraying of MP, while the total nitrogen, protein, amino acids, potassium, phosphorus, and starch content of tubers were positively affected by the same mineral fertilizer treatments combined with foliar spraying of MP or CP. In conclusion, the application of mineral potassium fertilizer with foliar spraying of MP or CP increased most of the plant growth- and tuber chemical composition-related parameters. These results highlight the importance of potassium fertilizer regimes for achieving high tuber yields and improving the quality of tubers in a sustainable and cost-effective manner.

Perthite is a special type of skeleton mineral in tight oil sandstone which cannot be ignored. However, few attention was paid to the secondary pores in perthite and their contributions in tight oil reservoir. This study reveals the perthite's significance in unconventional oil flow characterizes comprehensively and quantitativel by combining the Field Emission Scanning Electron Microscope (FE-SEM) with high resolution, Energy Dispersive Spectrometer (EDS) analysis, high precision image processing, comprehensive parameters construction and calculation. Typical perthite samples of Chang 7 tight oil reservoir of Ordos basin were selected for this study. Our results demonstrate that the growth of K-feldspar and Na-feldspar in perthite is complementary. The mixing process of the two types of stripes promotes each other rather than inhibiting each other. As to the development of secondary pores of perthite, there are clear differences in the area and number of pores, medium differences in the porosity, radius and perimeter, and small differences in other parameters. The more regular and uniform growth of Na-feldspar, the more likely the perthite is to form regular and normalized secondary pore. At least 56.7% of the secondary pore of perthite contributes to oil flow in the process of oil migration or development, and its scientific significance cannot be ignored. The conclusion could provide the geological basis for the effective development of the unconventional hydrocarbon reservoirs. • The more regular and uniform growth of Na-feldspar, the more likely the perthite is to form regular and normalized secondary pore. • At least 56.7% of the secondary pore of perthite contributes to the oil and gas flow in the process of oil and gas migration or development. [ABSTRACT FROM AUTHOR]

This work focuses on extraction of potassium from feldspar through pyro-hydrometallurgical route. Calcium chloride was used as roasting agent for feldspar. Effect of various operating variables, viz. time, roasting temperature and CaCl2 dose on extent of roasting, were thoroughly studied. Roasting 10 g of feldspar with 17 g of CaCl2 at 900 °C for 1 h resulted in 99.9% conversion of K2O to KCl. Order of feldspar roasting was found to be around 2, and activation energy requirement was 136.6 kJ/mol. Calcium and sodium were leached along with potassium from chloride-roasted K-Feldspar with water at room temperature. To generate a pure solution of potassium from the leach liquor containing K, Ca and Na, it was selectively extracted from leach liquor by using dibenzo-18-crown-6 ether as extractant and m-cresol as diluent. Loading of potassium was carried out at an A/O ratio of 2:1, while stripping was carried out in water at O/A ratio of 2:1. 99.5% pure crystals of KCl were obtained on evaporation of the strip solution. A schematic flowsheet has been provided for the preparation of pure KCl from feldspar. [ABSTRACT FROM AUTHOR]

• Phosphorus-rich fuels shift the ash chemistry to the formation of phosphates. • The admixture of chicken manure to straw increases the time until defluidization. • The fuel ash content is not a fitting parameter to predict bed defluidization. • K-feldspar is less susceptible to layer formation compared to quartz. The use of phosphorus-rich fuels in fluidized bed combustion is one probable way to support both heat and power production and phosphorus recovery. Ash is accumulated in the bed during combustion and interacts with the bed material to form layers and/or agglomerates, possibly removing phosphorus from the bed ash fraction. To further deepen the knowledge about the difference in the mechanisms behind the ash chemistry of phosphorus-lean and phosphorus-rich fuels, experiments in a 5 kW bench-scale-fluidized bed test-rig with K-feldspar as the bed material were conducted with bark, wheat straw, chicken manure, and chicken manure admixtures to bark and straw. Bed material samples were collected and studied for layer formation and agglomeration phenomena by scanning electron microscopy combined with energy dispersive X-ray spectrometry. The admixture of phosphorus-rich chicken manure to bark changed the layer formation mechanism, shifting the chemistry to the formation of phosphates rather than silicates. The admixture of chicken manure to straw reduced the ash melting and agglomeration risk, making it possible to increase the time until defluidization of the fluidized bed occurred. The results also highlight that an increased ash content does not necessarily lead to more ash melting related problems if the ash melting temperature is high enough. [ABSTRACT FROM AUTHOR]

Feldspar, which constitutes 60% of the earth's crust, is one of the most important mineral groups. Feldspar zones and deposits are formed by cooling and crystallization of these minerals in different shapes in different parts of magma. Feldspar reserves in many sectors of an important raw material in especiaaly ceramic, porcelain and glass industries including about 14% are in Turkey. In this sense, Turkey, is located in the rich world feldspar category in terms of reserves and has a significant share of exports. Although the evaluation of reserve resources is a priority issue of mining in the country, it is very important to know the radioactivity levels of 226Ra, 232Th, 40K and 137Cs isotopes contained in the raw material used in the construction of residential and business buildings. To this end, Turkey's most important zones (Aydın, Muğla, Manisa and Kırşehir) of feldspar mine using samples obtained from the bed where radioactivity analyzes were performed. As a result of the analyzes using gamma spectrometric method, the mean activity concentrations of 226Ra, 232Th, 40K and 137Cs radioisotopes were 11.94 ± 3.8, 4.28 ± 1.7, 879.26 ± 56.3 and 1.9 ± 0.7 Bqkg-1, respectively. And than Radiological risk analysis was performed. [ABSTRACT FROM AUTHOR]

A pot experiment was conducted under greenhouse condition at the Experimental Farm, Faculty of Agriculture, Zagazig University, Egypt. The experiment aimed to study the effect of different potassium sources (potassium sulphate and potassium feldspar) at the recommended rate (40 mg K kg-1) either single or in combination with soil amendments i.e., farmyard manure (FYM) and sulfur (S) with or without silicate dissolving bacteria (SDB) on yield and nutrients uptake by wheat through the investigated clayey soil. Soil were taken from the surface layers (0-30 cm) from Hehia District, Sharkia Governorate, Egypt. Application of K-sulphate or K-feldspar as individual application or combined with different soil amendments under SDB gave increase in straw and grain yield, potassium uptake, biological yield, 1000 grain weight and protein content of wheat plants compared to untreated soil. The highest value for each of yield, K-uptake and available K was found in clayey soil treated with K-sulphate combined with FYM plus S in the presences of SDB, while the lowest ones were obtained with untreated soils in absence of soil amendments and SDB. Application of Ksulphate showed greater value in each of yield, protein content, K-uptake by wheat plants and soil available potassium than K-feldspar. Application of SDB to K-sulphate or K-feldspar increased yield, protein content, K-uptake of wheat and available potassium compared to the untreated ones. [ABSTRACT FROM AUTHOR]

Pot experiments were carried out using sandy soil (collected from Ismailia Agricultural Research Station), in the greenhouse of Agric. Res. Center, Giza, Egypt to study the effect of biochar application on K and P release - from their natural bearing minerals i.e., K- feldspar and rock phosphate - as well as some growth parameter such as dry weight, plant height, available K, P and their uptake. Sixty three pots were filled with sandy soil (10 kg). Biochar was added to all pots, expect the control, at the rates of 0, 1.5 and 3 tonfed-1. The studied minerals are K- feldspar and rock phosphate as source of K and P respectively. Bentonite was also studied because it is the most common mineral used for reclamation of sandy soil .Each mineral was added at rate of 0,1.5, 3 tonfed-1. The experimental pots are as follows : biochar alone, K- feldspar alone , rock phosphate alone, bentonite alone, biochar + K feldspar, biochar + rock phosphate and biochar + bentonite .Maize seeds were planted as the common way 6 grains for each pot inoculated with P and K solubilizing bacteria , 200 kg /fed N fertilizer (NH4 )2SO4 was applied and irrigated as needed. Grown parameters of maize i.e. plant height and dry weight were measured after 2 months of plantation. Available K and P as well as their uptake were determined. Results revealed that, the use of biochar at a rate of 3 tons fed-1 in combination with 3 tons of any of feldspar, rock phosphate and bentonite enhanced significantly( in different ways) growth parameters of maize plants compared to the control treatments .The highest values of plant length and dry matter were 89.0 cm(biochar 3ton fed-1 + K- feldspar 3 ton fed-1) and 11.5 g.pot- for (biochar 3 ton fed-1 +bentonite 3 ton fed-1),1 against 36.7 cm and 2.9 g.pot-1 for the control treatment. The highest significant values of P uptake were 22.5, 18.3 and 16.7 mgplant-1 for the treatments 3 tonsfed-1 of biochar with either 3 ton rock phosphate, 3 ton bentonite or 3 ton K-feldspar respectively. While K uptake were 63.9, 61.8 and 60.1 mgplant-1 for biochar (3 tons fed-1) with bentonite (3 tons fed-1), feldspar (3 tonsfed-1) and bentonite (1.5 tonsfed-1). In the same order regarding the available P, the highest the treatment of values were 49.3 mgKg -1 for the treatment of 3 ton biochar + 3ton rock phosphate , 24.1 mg Kg-1 for the treatment of 3 ton biochar + 1.5 ton bentonite and 24.0 mgkg-1 for the treatment of 3 ton biochar + 1.5 ton K- feldspar. At the same time, increasing either K- feldspar or bentonite to 3 ton fed-1 had negative effect on available p. In Spite of the obtained results we can conclude revealed that using biochar alone at a rate of 3 ton fed-1 has the best treatment when taking the economic factor into consideration. [ABSTRACT FROM AUTHOR]

K‐Feldspar was used as a raw material for in situ synthesis of leucite particles by solid‐state reaction method. Prior to synthesis of leucite, K‐Feldspar was treated by oxalic acid (C2H2O4) to eliminate Fe content. The parameters affecting the structure and amount of Fe in K‐Feldspar was investigated to reach an optimal leaching condition. Next, kasilite removal was studied by introducing CaF2 to the composition of dental porcelain. To synthesis leucite, the prepared materials were heated up to 1450°C for 3 hours until fusion phenomena occurred, then cooled down to 865°C to permit the leucite crystals nucleate and grow. To find out the chemical composition of powder, XRF, EDX, and Atomic absorption spectroscopy were used. Fourier Transform Infrared Spectroscopy and X‐Ray Diffractometer and Scanning Electron Microscopy were employed to study the structure of mineral. Spectrophotometry was chosen to analyze whiteness index of powder after acid treatment. Differential Thermal Analysis was employed to determine the crystallization temperature. Results indicated a dramatic decrease in Fe content (0.018%wt) by employing C2H2O4 as a leachant at 50°C. In addition, whiteness index of 91% was achieved through this procedure for raw feldspar. Finally, 1%wt of CaF2 prevented formation of kalsilite. Illustration of the preparation process for leucite‐based feldspathic dental porcelain before pigmentation. [ABSTRACT FROM AUTHOR]

Abstract Sedimentary provenance studies have come to be overwhelmingly based upon U–Pb geochronologic measurements performed with detrital zircon while alternative and potentially complementary approaches such as conglomerate clast studies and heavy mineral analysis have faded in importance. Measurement of Pb isotopic compositions in detrital K-feldspar is among the under-utilized approaches available to ascertain sedimentary source regions. While it has been long recognized that common Pb isotope compositions recorded by K-feldspar vary widely and reflect the crustal provinces from which the host basement rocks crystallized, use of the approach has suffered due to a lack of appropriate statistical models and ground truth compositional data from source regions. In this paper, we: (1) present high-throughput LA-ICPMS analysis protocols needed to generate statistically meaningful detrital K-feldspar Pb isotope data sets; (2) develop an interpretative approach based upon 208Pb/206Pb vs. 207Pb/206Pb that incorporate information from the U- and Th-decay systems into one two-dimensional plot that is amenable to analysis using two-dimensional Kolmogorov–Smirnoff statistical tests; (3) generate new Pb isotopic data from basement rocks from southwestern North America to improve knowledge of the Pb isotopic properties of potential source regions; and (4) generate new Pb isotopic data from Lower Eocene to Lower Miocene sedimentary rocks to evaluate changes in drainage patterns that occurred in response to deformation that affected the southern California margin. Through this case study, we demonstrate how our new analytical and interpretative methods could be profitably applied to future geochemical and provenance studies and tectonically driven re-organization of drainage patterns. Highlights • Detrital K-feldspar is an under-utilized resource for provenance studies. • K-feldspar Pb isotopes vary sufficiently to be used as a provenance indicator. • LA-ICPMS can generate large datasets of Pb isotope data for provenance studies. • Detrital K-feldspar Pb isotope composition constrains source provenance. • 2D-KS tests can quantitatively compare detrital datasets and determine source. [ABSTRACT FROM AUTHOR]

Abstract Standardised growth curves (SGCs) were established for extracts of potassium feldspar (K-feldspar), plagioclase and polymineral grains from various geological settings (deserts, loess, lake or fluvial deposits) from Northern China. Single-aliquot regenerative-dose (SAR) protocol was used with the measurements of multiple elevated temperature post-IR IRSL (MET-pIRIR) signals from 50 °C to 250 °C with an interval of 50 °C. Regenerative-dose normalisation was applied for the SGC construction. The shapes of the SGCs of K-feldspar vary between IRSL signals measured at different temperatures. For coarse grains (63–180 μm), the SGCs of the K-feldspar, plagioclase and polymineral fractions are close to each other. However, the polymineral fine grains (4–11 μm) have a distinct SGC from the coarse-grain fractions. It may be caused by the difference in alpha irradiation. Two test doses (145 Gy and 72.5 Gy) were applied to construct the SGCs for K-feldspar. The SGC built with the larger test dose has a larger characteristic saturation dose (D 0). Test dose used for equivalent dose (D e) measurements need to be the same as the test dose used for SGC construction, otherwise the SGC D e may not be estimated accurately. With the same test dose used, the D e values estimated from SGCs are identical with the D e values generated from individual dose response curves. Highlights • Coarse grain fractions of K-feldspar, plagioclase and polymineral from northern China have similar SGCs. • Polymineral fine grains have a SGC distinct from coarse grains. • Test dose should be consistent between SGC construction and D e measurements. • SGC D e values are identical with SAR D e values. [ABSTRACT FROM AUTHOR]

Abstract Reliable chronologies are essential for understanding the timing and routes of human dispersal through Southeast Asia, both of which remain open questions. This study provides luminescence chronologies for two archaeological sites in Myanmar—Badahlin Cave and Gu Myaung Cave—from which Palaeolithic artefacts have been recovered. We applied single-grain post-infrared infrared stimulated luminescence (pIRIR) and multi-grain infrared-radiofluorescence (IR-RF) dating methods to potassium-rich feldspar (K-feldspar) grains extracted from the sedimentary deposits at these two sites. Luminescence characteristics of the K-feldspar extracts showed that the procedures were well suited for dating. The single-grain pIRIR ages suggest human occupation of Badahlin and Gu Myaung Caves by ∼30 ka and ∼25 ka, respectively, although the age estimates for Gu Myaung Cave are much older than the radiocarbon ages. The ages obtained using the IR-RF signal are even older, which we attribute to insufficient bleaching of this signal—and perhaps also the pIRIR signal—and the probable existence of a substantial residual dose at the time of sediment deposition. [ABSTRACT FROM AUTHOR]

Reducing energy and sustainable using of natural mineral resources offer challenges in energy production and environment. In this study, an efficient methodology is proposed for using K-feldspar as fluxing agent instead of silica in phosphorus furnace. Thermodynamic analysis of the process indicated the decomposition temperature of phosphate could be reduced by as much as 103 ∘C using K-feldspar. A series of experiments were conducted at the same acidity of 0.8. At the same potassium gasification rate of 96%, the high temperature melting results showed operating temperature of the silica system was 1300 ∘C while K-feldspar system operated at 1200 ∘C When phosphorus conversion rate was close, the residual flow temperature of the K-feldspar system was 180 ∘C lower than the silica. This was due to the residual quantity and different fluxing agents. The viscosity results indicated the spread out areas were similar at 1253 ∘C for K-feldspar while at 1432 ∘C for silica. This illustrated operating temperature was reduced about 180 ∘C and potash fertilizer was produced using K-feldspar in phosphorus furnace. The significance of this result will mean improved energy and cost savings for this process. [ABSTRACT FROM AUTHOR]

This study describes a high-energy ball milling followed by nanoscale iron (Fe)-oxide coating technology to produce an activated potassium (K)-feldspar with strong adsorption capacity of K-solubilizing bacterial cells (Bacillus subtilis). The results demonstrated that ball milling treatment significantly reduced the particle size of the K-feldspar while increasing available K content, specific surface area (SSA) and total pore volume. Both Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) verified amorphization of the K-feldspar due to considerable damage appeared to the mineral structure. However, the generation of microaggregates restricted above changes in properties of K-feldspar by ball milling. Nanoscale Fe-oxide coating treatment formed numerous Fe oxides (length of ∼100 nm) on the surface of the optimal ball milled mineral, and greatly increased the SSA and total pore volume. According to the results of the microbial adsorption, Fe-coated K-feldspar minerals with the lowest available nutrient content and highest zeta potential had the greatest capacity to adsorb B. subtilis cells. This implies that we can use this new carrier material for bio-potassium fertilizer, which may be able to efficiently supply soil K by carrying significant quantities of K-solubilizing bacteria. [Display omitted] • High-energy ball milling-nanoscale Fe-oxide coating technology was introduced to activate potassium (K)-feldspar. • Activated K-feldspar surface could adhere more Bacillus subtilis (with ability to dissolve K-feldspar). • A novel carrier material was produced to carry more K-solubilizing bacteria for biological K fertilizer. [ABSTRACT FROM AUTHOR]

Compared to quartz, the infrared stimulated luminescence (IRSL) of K-feldspar saturates at higher dose, which has great potential for extending the dating limit. However, dating applications with K-feldspar has been hampered due to anomalous fading of the IRSL signal. The post-IR IRSL (pIRIR) signal of K-feldspar stimulated at a higher temperature after a prior low-temperature IR stimulation has significantly lower fading rate. Different dating protocols have been proposed with the pIRIR signals and successful dating applications have been made. In this study, we review the development of various pIRIR dating protocols, and compare their performance in estimating the equivalent dose (De). Standard growth curves (SGCs) of the pIRIR signals of K-feldspar are introduced. Single-grain K-feldspar pIRIR dating is presented and the existing problems are discussed.

Abstract Infrared radiofluorescence (IR-RF) of K-feldspar is an alternative luminescence dating approach to infrared luminescence (IRSL). The application of IR-RF on coarse grain K-feldspar untreated with HF requires knowledge of the IR-RF α-efficiency. We present IR-RF α-efficiency measurements performed on four natural fine grain (4–11 μm) K-feldspar samples and test whether the α-efficiency is similar to that reported for IRSL on polymineral fine grain. The samples originate from Late and Middle Pleistocene aeolian sediment records in France and Germany. The fine grain fraction was obtained by crushing grains of diameter 90–200 μm. The natural signal was reset by optical bleaching at 70 °C using a solar simulator. The α-irradiation was carried out on a home-made α-irradiator, equipped with a 241Am source. For our irradiation setup, energy spectra were simulated using Geant4 to estimate the particle energy of the incident and exiting α-particles after passing a K-feldspar target. The α-flux induced IR-RF signals show a (super) linear dose-response up to 9.5 × 109 (integrated α-flux on the sample). The results indicate no significant difference between the IR-RF α-efficiency of the four samples. An averaged central S α -value of 9.26 ± 1.62 μGy/(103α cm−2) (corresponding a -value: 0.067 ± 0.012) was obtained from 84 measurements of all four samples. Our results are similar to a -values reported for IRSL on polymineral fine grain. We finally discuss how the central S α -value can be applied to calculate the β-equivalent α-dose rate of coarse grain mineral extracts. Highlights • Estimation of the alpha-efficiency using IR-RF on fine grain K-feldspar. • Simulation of the alpha-particle spectra of the irradiator using Geant4. • The alpha-efficiency appears to be similar to the one measured with IRSL. [ABSTRACT FROM AUTHOR]

An artificial silicate composite material prepared by the hydrothermal reaction of K‐feldspar and lime, showed excellent performance in remediating the soil. To elucidate the physicochemical properties of the artificial silicate composite material, K‐feldspar and lime were reacted in mild hydrothermal conditions (T=190 °C; P∼12.4 atm; t=0∼36 h). The hydrothermal product was systematically investigated using various techniques such as X‐ray powder diffraction (XRPD), scanning electron microscopy, and inductively coupled plasma‐optical emission spectrometry (ICP–OES). Quantitative evaluation of the extent of reaction by ICP–OES and XRPD methods enabled the analysis of hydrothermal evolution with prolonged time. The hydrothermal treatment of K‐feldspar with lime exhibits complex product phases, including leftover K‐feldspar, calcium hydroxide, calcite, grossular, tobermorite, alpha‐dicalcium silicate hydrate, potassium carbonate, bütschliite, and amorphous calcium silicate hydrate. The analysis of the reaction reveals that the K‐feldspar dissolution showed a clear transition, with the hydrothermal reaction beginning to slow down after 20 h. The slowdown of the K‐feldspar dissolution was essentially caused by different reaction kinetics and mechanisms before and after 20 h. The study yields vital and valuable insights into comprehending the chemistry and mineralogy of the artificial silicate composite material and producing a multielement reservoir from potassium‐rich rocks. Reaction mechanism: Analysis of kinetics shows that the change of the reaction mechanism of K‐feldspar and lime under hydrothermal conditions appears to be related to the generation of tobermorite. [ABSTRACT FROM AUTHOR]

Abstract In paleoenvironmental studies, the mineralogical composition of sediments is an important indicator. In combination with other indicators, they contribute to the understanding of changes in sediment sourcing as well as in weathering and depositional processes. Fourier transform infrared spectroscopy (FTIRS) spectra contain information on mineralogical composition because each mineral has a unique absorption pattern in the mid-IR range. Although easily obtained, FTIR spectra are often too complex to infer mineral concentrations directly. In this study, we use a calibration set of ca. 200 sediment samples conventionally measured using X-ray diffraction (XRD) in order to develop multivariate, partial least squares (PLS) regression models relating mineral contents to sediment spectra. Good correlations were obtained for the most common minerals (e.g. quartz, K-feldspar, illite, plagioclase, smectite, calcite). Correlation coefficients ranged from 0.85 to 0.92, coefficients for the validation varied from 0.64 to 0.80, the number of latent variables (PLS regression components) in the models ranged between 3 and 7 and the range of variation of the RMSEcv gradient was from 15.28 to 5.7. [ABSTRACT FROM AUTHOR]

Development of sustainable routes for the synthesis of kaolinite in nano-scale (nano-kaolinite) is very significant for producing high quality kaolinite of paper-coating grade in kaolin industry. Duplicating chemical weathering processes in nature, two routes were developed and compared for the synthesis of nano-kaolinite from K-feldspar. Kaolinite of uniform plate-like morphology with thickness of around 14 nm was obtained in this study. Both synthesis routes may lead to the comprehensive utilization of K-feldspar for the synthesis of pure kaolinite for not only high quality paper-coatings but also medical and other uses. [ABSTRACT FROM AUTHOR]

Detrital zircon U–Pb geochronology has become the gold standard in evaluating source to sink relationships in sedimentary basins. However, the physical and chemical robustness of zircon, which make it such a useful mineral for provenance studies, is also a hindrance as zircon can be recycled through numerous sedimentary basins, thus obscuring the first cycle source to sink relationship. An elegant approach to addressing this potential issue is to compare the Pb isotope composition of detrital K-feldspar, a mineral which is unlikely to survive more than one erosion-transport-deposition cycle, with that of magmatic K-feldspar from potential basement source terranes. Here we present new in situ Pb isotope data on detrital K-feldspar from two Proterozoic arkosic sandstones from Western Australia, and magmatic K-feldspar grains from potential igneous source rocks, as inferred by the age and Hf isotope composition of detrital zircon grains. The data indicate that the detrital zircon and K-feldspar grains could not have been liberated from the same source rocks, and that the zircon has most likely been recycled through older sedimentary basins. These results provide a more complete understanding of apparently simple source to sink relationships in this part of Proterozoic Western Australia. [ABSTRACT FROM AUTHOR]

The thermodynamic estimation and experimental research on a laboratory scale with different fluxing agents (silica, K-feldspar) in yellow phosphorus production by the electric furnace method were investigated. The thermodynamic calculation showed that the reaction temperature of silica system is 1120°C, while the temperature dropped to 970°C with K-feldspar as a fluxing agent. The production efficiencies of phosphorus and potassium from this process were investigated and different reaction times and temperatures were studied. The experimental results demonstrated that the phosphorus conversion rates of the Ca5(PO4)3F-C-silica and Ca5(PO4)3F-C-KAlSi3O8 systems reached 96.9% and 99.0%, respectively. The potassium gasification rate of the Ca5(PO4)3F-C-KAlSi3O8 system reached 44.3%. The characteristic of slag was studied by flow temperature and viscosity experiments, and the flow temperature was reduced by 61°C, the residual viscosity was clearly increased. Finally, the mechanisms of yellow phosphorus production with different fluxing agents were analyzed by XRD, SEM and TEM methods. [ABSTRACT FROM AUTHOR]

In this article we test the potential use of a partial bleach method, which was traditionally used in thermoluminescence dating, for the post-infrared infrared stimulated luminescence (pIRIR) dating of K-feldspar, with an aim to correct for the impact of remnant dose on the dating of Holocene-aged K-feldspar samples. We show that the solar bleaching decay of the pIRIR signal can be described using several components with different sensitivities upon exposure to sunlight. An improved partial bleach pIRIR (PB-pIRIR) method based on a multi-aliquot regenerative (MAR) protocol is proposed, which can isolate the rapidly bleached components from the pIRIR signal for the dating purpose. Natural and experimental factors that can affect the PB-pIRIR D e are investigated by numeric simulation and dose recovery experiments. A plateau test is proposed to assess a proper laboratory bleaching time in the PB-pIRIR measurement. Dating known-age samples indicates that for well-bleached samples the PB-pIRIR method can yield reliable ages; whereas for poorly-bleached samples this technique can produce pIRIR ages consistent with expected ages or improve the pIRIR dating results. We deduce that for insufficiently bleached samples, the efficacy of the PB-pIRIR approach is related to the significance of the remnant dose relative to the burial dose, as well as the degree of heterogeneity of the grains' signal resetting. Our results suggest the partial bleach method has the potential to reduce or even eliminate the impact of insufficient bleaching on K-feldspar pIRIR dating. This method is more suitable for insufficiently bleached samples for which all or most of the K-feldspar grains have been exposed shortly to sunlight before the last burial. [ABSTRACT FROM AUTHOR]

The Hadamengou gold deposit, which is located in a high-grade metamorphic terrane at the northern margin of the North China Craton, is characterized by K-feldspar-quartz vein gold mineralization. The 40 Ar/ 39 Ar dating of hydrothermal K-feldspar indicates that the mineralization formed over 45 Ma commencing at 243.5 ± 1.3 Ma and ending at 199.0 ± 0.8 Ma. The Pb, C and O isotope compositions and the geochronology of the gold-bearing K-feldspar-quartz veins imply a close genetic association between the gold mineralization and alkaline magmatism, which are both products of the Indosinian alkaline magmatic event caused by the extensional tectonic setting that prevailed during the late Hercynian collisional orogeny. We propose an Indosinian phase of gold mineralization in addition to the abundant mineral deposits formed during the Yanshan Epoch. [ABSTRACT FROM AUTHOR]

The information provided by detrital studies can be greatly enhanced by coupling geochronology and isotopic measurements from the same grains. While accessory minerals like zircon and apatite have been widely exploited in this regard, modal phases have been under-utilized. The benefits of using K-feldspar in detrital studies are twofold: K-feldspar 40 Ar/ 39 Ar has shown promise as a detrital thermochronometer and incorporation of common Pb into K-feldspar allows its Pb isotope composition to be used as a provenance tool. In this paper, we quantitatively investigate the effects of laser fusion during 40 Ar/ 39 Ar analyses of K-feldspar upon subsequent LA-ICP-MS measurement of Pb isotopic ratios. The results reveal that significant Pb volatilization occurs during laser fusion of K-feldspar. While Pb isotopes do not appear to be significantly fractionated, counting statistics suffer as Pb concentrations are lowered. Conversely, neutron irradiation appears to have a small though inconsequential impact upon Pb isotopic measurement of K-feldspar. Consequently, K-feldspar can be analyzed for Pb isotopes prior to total fusion 40 Ar/ 39 Ar analysis. Despite this artifact, coupled 40 Ar/ 39 Ar and Pb isotopic measurements constitute a promising approach for provenance studies that seek to constrain the geochemical nature and thermal evolution of basement source regions. [ABSTRACT FROM AUTHOR]

Understanding the chronology of eolian sand-loess-paleosol sequences along the northern margin of the Chinese Loess Plateau (CLP) is crucial for comprehending climate change and the advance and retreat of the adjacent Mu Us desert. In this study, a sand-loess-soil sequence from the northern margin of the CLP was studied by applying the single aliquot regenerative (SAR) protocol to quartz grains, and the multi-elevated-temperature post-IR IRSL (MET-pIRIR) protocol to K-feldspar grains. For equivalent dose ( D e ) determination, 63–90 μm quartz and K-feldspar grains were used. Our results indicate that the MET-pIRIR ages of K-feldspar grains in this sequence range from 94.4 ± 7.0 ka to 148.3 ± 13.3 ka for the last interglacial paleosol (S1); for the upper part of the section, quartz-based SAR-OSL dating was used, yielding ages spanning from 5.8 ± 0.4 ka to 35.9 ± 4.1 ka. After cross-checking these results with previously-reported isochron OSL and TL ages, the reliability of the MET-pIRIR protocol when applied to the last interglacial paleosol was confirmed. Based on a new OSL chronology of the Shimao profile, the studied eolian deposits can be broadly correlated with the last glacial-interglacial cycle, but their dating also points to sedimentary hiatuses occurring at 94.4 ka, 35.9 ka and 5.8 ka, due most probably to strong wind erosion caused by intensified cold-dry winter monsoonal circulations during the last glacial maxima. [ABSTRACT FROM AUTHOR]

Potassium-rich feldspar (K-feldspar) grains were extracted from 28 sediment samples from sites in Asia, Europe and Africa and the dose response curves — or growth curves — were constructed from the post-infrared infrared stimulated luminescence (pIRIR) signals emitted by individual grains. The samples exhibit large between-grain variation in both pIRIR signal intensity and the shape of the corresponding growth curves; the latter can be largely explained as a result of measurement uncertainties, including counting statistics and instrumental irreproducibility. This between-grain variation can be reduced by applying a least-squares normalisation (LS-normalisation) procedure, which allows a common growth curve — or global standardised growth curve (gSGC) — to be established for individual K-feldspar grains from the range of samples investigated. Equivalent dose (D e ) values for single grains can be estimated using the fitting parameters of the gSGC, together with measurements of the natural signal (L n ), one regenerative-dose signal (L x ) and their corresponding test-dose signals (T n , T x ). The D e values obtained using the gSGC approach are consistent at 2σ with those obtained from the individual growth curves constructed for each of the grains. The establishment of a gSGC greatly reduces the time required to measure a large number of grains for old samples, and it also overcomes the problem of D e underestimation that can occur using a full single-aliquot (or single-grain) regenerative-dose (SAR) procedure when a large number of grains are rejected due to issues of ‘saturation’. The construction of a gSGC may, therefore, potentially extend the dating range of pIRIR signals beyond the reliable limit of D e estimation using the standard SAR method. [ABSTRACT FROM AUTHOR]

Dose recovery tests were performed on potassium feldspar using the single-aliquot regenerative-dose (SAR) multi-elevated-temperature post-IR IRSL (MET-pIRIR) dating protocol with a large number of samples from various backgrounds. The dose recovery ratios were always smaller than unity for the 50 °C IRSL signal, but the ratios increased with signals from elevated temperatures. For the pIRIR signal at 250 °C, the recovery ratios were within the range of 1.0 ± 0.1. Underestimations of the recovery ratios for low-temperature IRSL signals resulted from the increase of the electron trapping probability during the first preheat treatment. The electron trapping probability can be reset by solar bleaching. The modified SAR protocol with solar bleaching behind each cycle or the MAR protocol is recommended if the low-temperature IRSL signals are applied to obtain ages. Solar simulator with the xenon arc lamp is more efficient in reducing the electron trapping probability compared to the sunlight. Bleaching duration with the solar simulator should be chosen with caution. [ABSTRACT FROM AUTHOR]

Trace elements of potassium feldspar (Kfs) from pegmatite veins in the Keketuohai pegmatite district were determined in situ by LA-ICP-MS. As the K/Rb ratio decreases, the contents of compatible Ba and Sr decrease, while the contents of incompatible Li, Cs and Ga increase. The K/Rb ratios and above mentioned trace element contents of Kfs from the Be-Nb-Ta mineralized pegmatite veins match those of Kfs from barren pegmatite veins. In contrast, the mineralized pegmatites are characterized by having K-feldspars with high phosphorus contents, mostly above 0.1 wt% P 2 O 5 , which is the boundary separating mineralized pegmatites and barren pegmatites. The high P 2 O 5 content in Kfs indicates high concentration of this element in the melt from which these pegmatites crystallized. The P 2 O 5 content in K-feldspar can be used as an exploration tool for LCT type Be-Nb-Ta deposit. [ABSTRACT FROM AUTHOR]

The source of the feldspar is found in the Late-Precambrian granitoid rocks of Al Madinah area, which covers about 2000 km2 within a 44,000 km2 area of the western part of Saudi Arabia. Petrographical and geochemical study shows that the granitic rocks have a considerable compositional range from quartz monzonite, quartz syenite, syenite, alkali granite to alkali feldspar granite. Mineralogical and petrographical results have revealed that Al Madinah granites are composed of quartz, K- feldspar, Na-plagioclase and muscovite. Geochemical data for the feldspar samples show average SiO2, Al2O3, K2O, Na2O, CaO, Fe2O3, MgO and TiO2 contents of 71.33, 13.71, 4.78, 5.93, 1.17, 1.89, 0.34 and 0.31 wt.%, respectively, while mineralogical results reveal average K-feldspar and Na-plagioclase contents of 28.53% and 39.66%, respectively. They are almost invariably composed of metaluminous, calc-alkaline and shoshonite, with respect to alumina saturation. These deposits are characterized and evaluated for their potential as a source of feldspar. [ABSTRACT FROM AUTHOR]

Abstract: Influence of KOH concentration and reaction time on the synthesis of zeolite F from K‐feldspar, and the kinetics of potassium slow release from the product were studied. X‐ray diffraction (XRD), Fourier transformation infrared spectrometry (FTIR), and scanning electron microscopy (SEM) were applied to characterize the as‐synthesized samples. The XRD results indicate that there exist K−G zeolite (K2Al2SiO6⋅H2O) with hexagonal structure at the KOH concentration of 2 mol⋅kg−1 and zeolite F (KAlSiO4⋅1.5H2O) with tetragonal structure at 4–5 mol⋅kg−1. In terms of synthesis efficiency, crystallization time of 12 h was chosen as optimal condition. The surface area and pore diameter of zeolite F sample synthesized in 4 mol⋅kg−1 at 95 °C for 12 h were investigated by surface area analyzer, the values of which are 27 m2/g and 0.513 nm, respectively. Slow‐release testing results suggest that the potassium cumulative release fraction of zeolite F in water for 42 d is up to 68.97% and can be fitted well with Elovich equation. [ABSTRACT FROM AUTHOR]

The reliability of a post-IR elevated temperature IRSL (290 °C; pIRIR 290 ) is tested on wind-blown, sand-sized (180–250 μm) K-rich feldspar grains. The pIRIR 290 ages were compared with quartz SAR-OSL data, other independent age controls and historical information. Three study areas along the coast of Sardinia (Italy) were selected: the south Alghero coast, the Bue Marino cave (E Sardinia) and the Alghero bay (NW Sardinia). Along the south Alghero coastline a thick dunefield system is widely recognised in the literature to represent the beginning of the last glacial phase ( post 80 ka). From a single block sand-sized grains for quartz SAR-OSL and K-feldspar pIRIR dating were collected. The natural quartz SAR-OSL sample lies below the saturation limit of the dose response curve (D e < 2xD 0 ) giving a reliable age of 76 ± 6 ka. The fading-uncorrected pIRIR 290 age of 73 ± 5 ka is in good agreement with the quartz result. A further test on older samples was carried out on the sedimentary succession at Bue Marino cave, which includes a sandy wind-blown unit, enclosed between two calcareous crusts. U-series dates of crusts constrain the aeolianite formation between ∼130 and ∼86 ka. The quartz SAR-OSL signals for aeolianite samples lies close to saturation and the resulting ages underestimate the independent age control. Instead, uncorrected pIRIR 290 ages on K-feldspar extracts point to a formation of the wind-blown unit between ∼100 and ∼80 ka, in good agreement with the U-series data. The bleachability of the pIRIR 290 signal was further investigated using samples from a modern coastal barrier system backing the Alghero bay. The dunefield was stabilized by plantation during the 1950s. The quartz SAR-OSL ages span from 2450 ± 170 years to 60 ± 13 years ago, consistent with the known coastal barrier stabilization. The pIRIR 290 ages indicate an offset up to ∼1000 years. We can conclude that the pIRIR 290 method on sand-sized K-feldspar grains shows great promise for samples at or beyond the quartz OSL age limit but should not be applied to Late Holocene or modern deposits. [ABSTRACT FROM AUTHOR]

The effect of pH, contact time, temperature, ionic strength and initial U(VI) concentration on U(VI) sorption onto K-feldspar was investigated using batch techniques. The sorption kinetics was evaluated and the activation energy was obtained based on the rate constants at different temperature. Graphical correlations of sorption isotherm models have been evaluated and applied for U(VI) uptake by K-feldspar. Various thermodynamic parameters, such as, Gibb's free energy, entropy and enthalpy of the on-going sorption process have been calculated and the possible sorption mechanism of U(VI) was deduced. The results are expected to help better understand the migration of uranium in the host materials of granite. [ABSTRACT FROM AUTHOR]

The thermal stability of organic acids is critical in studying the formation mechanism of secondary pores in deep reservoirs (>4000 m). However, the thermal stability of organic acids in geochemical systems is strongly dependent on temperature, minerals and pressure (fluid pressure and lithostatic pressure). To investigate the activity of organic acids and the influence of these factors (temperature, pressure and K-feldspar), four series of experiments were conducted over a wide range of reaction conditions. Pure acetic acid solutions were selected for this study. The temperatures ranged from 130 °C to 380 °C, and each experiment was performed for 72 h in steps of 50 °C. The results indicate that the decomposition reaction rate was slow but accelerated with increasing temperature. At temperatures higher than 230 °C, the decomposition of acetic acid proceeded to a much more significant extent than at low temperatures. The results of experiments also show that the decomposition rates were faster at lower lithostatic pressure, and the lithostatic pressure played a larger role than water pressure in affecting the decomposition of acetic acid. Additionally, the presence of K-feldspar influenced the reaction rates of acetic acid, especially the oxidation rates. This was attributed to the increasing concentration of acetate produced by dissolution. [ABSTRACT FROM AUTHOR]

Dune fields of Quaternary age occupy large areas of the world's arid and semiarid regions. Despite this, there has been surprisingly little work done on understanding dune sediment provenance, in part because many techniques are time-consuming, prone to operator error, experimental, highly specialized, expensive, or require sophisticated instrumentation. Provenance of dune sand using K/Rb and K/Ba values in K-feldspar in aeolian sands of the arid and semiarid regions of North America is tested here. Results indicate that K/Rb and K/Ba can distinguish different river sands that are sediment sources for dunes and dune fields themselves have distinctive K/Rb and K/Ba compositions. Over the Basin and Range and Great Plains regions of North America, the hypothesized sediment sources of dune fields are reviewed and assessed using K/Rb and K/Ba values in dune sands and in hypothesized source sediments. In some cases, the origins of dunes assessed in this manner are consistent with previous studies and in others, dune fields are found to have a more complex origin than previously thought. Use of K/Rb and K/Ba for provenance studies is a robust method that is inexpensive, rapid, and highly reproducible. It exploits one of the most common minerals found in dune sand, K-feldspar. The method avoids the problem of using simple concentrations of key elements that may be subject to interpretative bias due to changes in mineralogical maturity of Quaternary dune fields that occur over time. [ABSTRACT FROM AUTHOR]

In this study, thermodynamic calculations were conducted to investigate K-feldspar fluxing yellow phosphorus produced via an electric furnace. The results demonstrated that the reaction temperature of K-feldspar as a flux was lower than that during the traditional process. The characteristic temperatures of silica-CaO and potassium feldspar-CaO systems under different mass ratios of SiO2/CaO were measured according to the CaO-substituting decomposition products of phosphorus; the results showed that the temperature of the silica-CaO system was higher, 96.2–114.3°C, compared to the potassium feldspar-CaO system under the same conditions. These results indicate that K-feldspar as a flux in a phosphorus furnace can save energy and reduce cost. X-ray diffraction (XRD) analysis further revealed that a complex transition phase of silicates and aluminosilicates was accompanied by a conversion reaction of the silica-CaO and potassium feldspar-CaO systems, and that K2O capable of co-producing potash fertilizer escaped as a gas through the collection equipment. [ABSTRACT FROM PUBLISHER]

A glass ceramic material was obtained from the beneficiation tailings of lead-zinc ores. The strength of the control samples was 22.26 MPa in bending and 90.22 MPa in compression. After 100 cycles of testing the samples for frost resistance, these characteristics changed to 9.61 MPa in bending and 35.30 MPa in compression. [ABSTRACT FROM AUTHOR]