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China, being the world’s largest consumer of potassium fertilizer, faces significant challenges due to limited potassium reserves. Qarhan Salt Lake stands out as a reservoir containing 296 million tons of low-grade solid potash ore (KCl), establishing itself as the premier potassium fertilizer production base in China. The extraction of low-grade solid potash ore via liquefaction technology, leading to the generation of potassium-rich brine, emerges as a pivotal strategy for sustainable potash exploitation in the region. This approach offers a promising solution to mitigate the potassium salt shortage in China. This paper systematically examines the transformation in KCl content of solid potash ore within the Bieletan section of Qarhan Salt Lake before (2007) and after liquefaction (2022). The study employs quantitative assessments to determine liquefaction volume and efficiency. Results reveal that, at a shallow depth of 23.20m, the average KCl content of solid potash ore decreases from 2.15% before liquefaction to 1.00% after liquefaction. This observed decrease of 1.15% (53% reduction) underscores the substantial impact of liquefaction. A total of 136.94 million tons of KCl are dissolved, providing a sustainable resource for approximately 15 years or more. During the initial stages of liquefaction (2007–2008), a rapid decline in the KCl content of solid potash ore is noted, with liquefaction efficiency significantly influenced by the positioning of the brine mining channel. As liquefaction progresses, efficiency diminishes, although the overall efficiency surpasses that of the Huobuxun section at the eastern extremity of Qarhan Salt Lake. This study holds significant implications for refining the solid potash liquefaction mining strategy in Qarhan Salt Lake, providing valuable guidance for future optimization efforts. [ABSTRACT FROM AUTHOR]

To reduce intensity of deformation in rocks prone to buckling and plastic deformation, and sensitive to geo- and gas-dynamic phenomena, the authors propose a consolidated backfill technology using salt waste and processing reuse brine at the consumption limits of water-yielding capacity. A set of laboratory tests is carried out to find backfill mixtures adaptable to deep-level potash mining with estimation of deformation characteristics and strength properties of potash salt rocks. New principles and technologies of deep-level sylvinite extraction and backfill material transport by creating such geotechnical structures in stopes which ensure formation of consolidated backfill mass with the mined-out stope space factor close to one. This approach can enhance mine efficiency owing to increased extraction of sylvinite from rib and safety pillars. [ABSTRACT FROM AUTHOR]

Mobile proximal gamma-ray spectrometry (GS) is an emerging approach to estimate soil texture directly in the field. It relies on gamma radiation emitted during the natural decay of potassium-40 (K-40) and other isotopes. The K-40 counts are correlated with total K content, mineralogical soil composition and therefore with soil texture. Yet, it is not clear if K fertilisation impacts the ratio of K-40 to total K which would necessitate to take the fertilisation history into account for soil sensing applications. To elucidate this question, a well-documented long-term experiment was selected. The soils of the Rengen grassland experiment (55 plots) were investigated for total K (XRF-K) and for K-40 via mobile proximal GS. No significant differences in XRF-K and K-40 were found between the treatments with and without K fertilisation, although formely published results point to negative and positive K balances, respectively. Fertiliser analysis revealed a ratio of K-40 to total K that was almost identical to the natural abundance of 0.0117%. It was concluded that it is not necessary to take K fertilisation history into account when predicting soil texture from mobile proximal GS on agricultural land for, e.g., precision farming purposes. [ABSTRACT FROM AUTHOR]

Large amount of solid and liquid waste is a serious issue associated with potash mining and processing. Potash ore enrichment generates solid halite waste, clay-salt slurry, and industrial wastewater with a high content of water-soluble salts. The «environmentally friendly» storage of such waste is a difficult technological issue. Highly mineralised water is stored on the surface and discharged into slurry storage, while some of the effluent is recycled during the production process. Over the long period of slurry storage operation at the Verknekamskoe Potash Deposit, water filtration through the dam and the slurry storage base has created a stable flow of highly mineralised water into the surface water and groundwater. The slurry storage facilities that are currently in use cannot completely fulfil the protective environmental functions. This study provides scientific rationale for the potential use of slurry reservoirs as wastewater treatment facilities. The findings show that there are fewer suspended solids in clarified water: purification efficiency is greater than 99.9%. In the clarified circulating brine, the content of mineral impurities is reduced: the content of chloride ions decreases by 46%, and the content of dry residue decreases by 45.6%. Based on the findings, the study provides recommendations for the construction and new design of a slurry storage that can be used as a treatment facility on the territory of the Verkhnekamskoe Potash Deposit to reduce the negative environmental impact. [ABSTRACT FROM AUTHOR]

Exploration of potash resources under complex geological condition is particularly important. However, it is difficult to establish characteristic equations for direct prediction, since there is no direct relation between potash content (PC) and seismic response. To solve this problem, this paper proposed a potash reservoir prediction method by a specially designed convolution neural network (CNN) structure to train the special waveform and petrophysical characteristics of potash reservoirs. Considering that the potash reservoirs and petrophysical characteristics are not a one-to-one mapping, the prediction procedure is divided into two parts. First, a CNN is constructed for potash reservoir prediction, according to the spatial waveform characteristics of potash reservoirs. The mapping between potash reservoirs and waveform characteristics is used to obtain the potash reservoir probability data by the soft-max function. Then, another CNN for PC prediction is built based on the petrophysical characteristics of potash reservoirs. Meanwhile, according to the Hadamard criterion, the petrophysical characteristics of potash reservoir are constrained by the waveform characteristics. The two CNN models are used to directly predict the PC synergistically. Consequently, the bidirectional mapping problem can be alleviated and a loss function of the PC prediction CNN constrained with the waveform is obtained. Finally, by tuning the PC prediction CNN through the loss function, PC prediction is performed. The correlation between the predicted and true PC values can reach more than 80%. [ABSTRACT FROM AUTHOR]

The scarcity of petroleum and concern over environmental problems has promoted the production of biodiesel from renewable sources. Biodiesel synthesized by transesterification methods in the presence of catalyst requires a large amount of solvent, mainly from alcohol, to affirm a high production yield. The transesterification process using a homogeneous catalyst demands complex product separation steps and is not recyclable; thus, it is economically unviable. In this study, transesterification reaction was conducted in a packed bed column using a heterogeneous catalyst, potash supported on PVA derived from the orange peel. Potash/PVA was characterized using Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). Potash-derived orange peel was supported on polyvinyl alcohol (PVA) to retain its mechanical stability. Optimization study revealed that a maximum biodiesel yield of 95.55% was obtained at an optimum temperature of 60 °C, 2.50 wt.% of catalyst and 12:1 of methanol: oil molar ratio. Potash derived from waste shows a promising alternative to produce a heterogeneous catalyst for biodiesel production. [ABSTRACT FROM AUTHOR]

Purpose: Occupational exposure limits (OEL) for nitrogen oxides (NO, NO2) and diesel exhaust (EC-DPM) were reassessed by the German authorities in 2016/2017. We performed a clinical cross-sectional study among salt and potash underground workers exposed to these substances at relatively high levels to examine possible indicators of acute effects on workers' health. Methods: We measured post- versus pre-shift differences in cardiovascular, inflammatory, immune, and respiratory effect biomarkers and assessed their associations with personal exposures measured during the same shift. We also compared post- versus pre-shift differences in biomarker levels between exposure groups defined based on work site and job type. Results: None of the above-ground workers exceeded the OEL for NO2 and only 5% exceeded the OEL for EC-DPM exposure. Among underground workers, 33% of miners and 7% underground maintenance workers exceeded the OEL for NO2; the OEL for EC-DPM was exceeded by 56% of miners and 17% of maintenance workers. Some effect biomarkers (thrombocytes, neutrophils, MPO, TNF-α, IgE, FeNO) showed statistically significant differences between pre- versus post-shift measurements; however, there were no consistent associations between pre- and post-shift differences and exposure group or personal exposure measurements during the shift. Conclusions: We did not find evidence of associations between workplace exposure to NO, NO2 or EC-DPM and clinically relevant indicators of acute cardiovascular, inflammatory and immune, or respiratory effects among salt and potash underground workers in Germany. [ABSTRACT FROM AUTHOR]

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Potassium is the active element of potash fertilizer, its concentration determines the quality of the product. Self-absorption occurs in laser-induced breakdown spectroscopy (LIBS) analysis of potash, since potassium is the major element with a concentration that can reach the level of 95 wt.%. The present work simulated an online analysis of potassium in potash with a laboratory setup, LIBS spectra were recorded on 27 potash samples collected from a factory in Qinghai province in China with different potassium concentrations in the range from 90 to 97 wt.%. The self-absorption correction was applied to the spectra for K I 404.4 nm and K I 693.9 nm lines. Multivariate regression based on machine learning were processed with the self-absorption corrected spectra in order to get a better potassium determination performance compared to that with uncorrected spectra. The results show the effectiveness of self-absorption correction in the improvement of the analytical performance. The obtained multivariate regression model presents a satisfactory performance to fill the requirements of the aimed application of online and real-time analysis of potash on a product transportation belt in a production site with respect to the specific requirements of the related current national standards. [ABSTRACT FROM AUTHOR]

The paper presents the results of studying sylvinite rocks of the Lower Permian halogenic formation in the West and East Perelyub sites with perspectives for the commercial development of potassium salts in the Saratov region and in the Gremyachinsk potash deposit (Volgograd region, Russian Federation) by the textural–structural analysis methods to refine their formation conditions. A new method is proposed for studying the structural–textural features of sylvinites and sylvite–halite rocks. Typification of sylvinite structures and identification of the main genetic types of their texture are accomplished. Based on the literature data and the results of studying the core material, a scheme of the structure–texture classification is proposed for the chemogenic-sedimentary potassic rocks, including those subjected to postsedimentary transformations. [ABSTRACT FROM AUTHOR]

Nitrate deposits are rare worldwide, especially potassium nitrate deposits; furthermore, their genesis remains disputed. There is a rare salt-lake type potassium nitrate deposit in the Dawadi area of Lop Nor at the eastern margin of the Tarim Basin, and the ore bodies show coexisting solid and liquid phases. Additionally, there are large sulphate-type potash deposits in the adjoining Luobei Depression, south of the Dawadi area. To determine why there are two different types of potash deposits in adjacent depressions with similar climates, field geological surveys were conducted and samples collected. It was found that the Tertiary clastic layer at the periphery of the Dawadi deposit was rich in high-salinity brine, with nitrate contents of up to 495–16,719 mg/L, much higher than those in the Luobei Depression, 1–35 mg/L. Additionally, a type of deep hydrothermal (Ca–Cl) brine was found in the fault zones, with nitrate contents of up to 8044 mg/L, dozens of times greater than that of ordinary groundwater. Using comprehensive analysis and research, we concluded that the Dawadi and Luobei depressions belong to different hydrological systems with no connection between them; thus, the two deposits belong to different metallogenic systems. Furthermore, groundwater played an important role in the mineralization of the potassium nitrate deposit, and a deep source may have been an important source of the ore-forming materials. The fault system widely developed in Lop Nor provides favorable channels for deep hydrothermal recharge, and the groundwater and deep hydrothermal brine could provide the source for the nitrate mineralization in the Dawadi Depression through water–rock reactions. [ABSTRACT FROM AUTHOR]

Two types of potash ores were sampled from the Mengyejing potash deposit (the MPD) which is the only ancient potash deposit ever found in China. Geochemical analyses, including Br, K, Mg and some heavy metals, were performed on those samples. The relatively consistent Br contents (141.42 to 763.67 ppm) in both bedded potash and veined potash ores show that the potash-forming brine was likely derived from seawater. K contents and Br/Cl ratios of the veined potash ores are relatively high in contrast to bedded potash ores. The K/Br ratios of veined potash ores exhibit a positive correlation with Br contents, which is opposite to that of the bedded potash ore of the MPD and potassium-salts from the evaporation of modern seawater. The contents of heavy metals in veined potash ores are much higher than those of bedded potash ores in the MPD and potash in other evaporite basins of the world. Sr and S isotopic compositions of these two types of potash ores suggest that the brines for precipitating veined potash were formed by mixing of connate waters (seawater or/and continental freshwater) and hydrothermal fluids. The geochemical and petrological characteristics of the veined potash ores indicate that the brine for forming veined potash orebodies caused by dissolution of previous bedded potash orebodies by hydrothermal fluids. The veined potash orebodies were formed through a cooling process by which sylvite precipitated first prior to halite. [ABSTRACT FROM AUTHOR]

The current study tested the hypothesis of whether the low-temperature catalytic cracking of waste plastics would generate carbon fules using high-density polyethylene (HDPE) polymer by potash as a novel catalyst for both energy recovery and carbon recycling. We applied a one-stage pyrolysis reactor system with a 75 min reaction time to observe the highest yield at a low temperature range of 70–170 °C. The effects of the potash and zeolite catalysts, temperature, and catalyst–polymer ratio on the pyrolysis liquid yield and hydrocarbon contents were determined. The mineral concentration of potash was analyzed semiquantitatively using an inductively coupled plasma-optical emission spectrophotometer (ICP-OES) and X-ray diffractometer (XRD). The ICP-OES demonstrated that nine metals, in the order of K > Na > Fe > Si > Mg > Al > Cu > Ca > Ni, were predominant in the potash. GC–MS analysis of the liquid products showed that major catalytic cracking molecules are C11 to C20 as kerosene- to diesel-range liquid. Potash catalyst produced an average liquid conversion of 34.7% at a catalyst ratio of 30 wt% over a distillate temperature range of 76–140 °C, whereas zeolite generated 19.5% at the same catalyst ratio over 90–120 °C. Although the two catalysts favored mainly olefinic products, a higher potash ratio promoted a smaller carbon products with a purer composition. Our experiments demonstrated that the new natural potash catalyst could convert waste plastics into kerosene to diesel range of valuable and recyclable liquid products as potential renewable fuel sources for carbon recycling. [ABSTRACT FROM AUTHOR]

The output and grade of liquid potash minerals in Qarhan Salt Lake are decreasing year by year, which has become the main problem restricting the sustainable production of potassium fertilizer. The exploitation and utilization of low-grade solid potash ore, which is in the strata of the Qarhan Salt Lake, represents the fundamental framework for the sustainable development of Qarhan Salt Lake's potash fertilizer. PHREEQC is a simulation software for hydrogeochemistry. In this paper, PHREEQC was applied to simulate temperature, pH value and solvent chemical characteristics which affect the dissolution process of low-grade solid potash minerals. The simulation results indicate that the optimum temperature for ore dissolution is around 25 °C, because, around this temperature, the dissolving ability of solvents to low-grade solid potash minerals is enhanced, while the dissolving ability to halite remains basically unchanged, which is conducive to selective dissolution of low-grade solid potash. It is recommended the temperature is between 20 and 30 ℃. The simulation results show that, when the pH value of solvents is more than 9, although it is advantageous to selective dissolution of low-grade solid potash minerals, the solvent becomes strong alkali solution, which will cause environmental pollution and seriously corrode materials and equipment in actual production, so it is recommended the pH value of the solvent is adjusted between 6 and 8. The simulation results show that, when the values of K+, Na+, Mg2+, Ca2+, Cl− and SO42− in the solvent are 0.1%, 2.9%, 3.77%, 0.05%, 15.72% and 0.13% respectively, the solubility of low-grade solid potash ores is stronger, which is more conducive to selective ore dissolution. It is suggested that in actual production, the chemical composition of solvents prepared with old brine and fresh water should be as close as possible to the above chemical composition characteristics. [ABSTRACT FROM AUTHOR]

Bromine contents of a 17-cm halite core from drilling hole of K203 in the Khorat Basin were analysed at 1 cm intervals (17 samples in total). The Br contents range from 99 to 184 ppm with a rapid variation. The K/Mg ratios of halite samples are tens of times higher than those of primary halite fluid inclusions. There is no positive correlation between Mg and Br contents, suggesting that fluid inclusions impose very little or negligible influence on Br contents of halites. The Br contents are not controlled by potash minerals either because the SEM examination shows no potash minerals and there is no relationship between K and Br contents. The Br contents of halite are thus primarily controlled by the Br concentrations of parent brines. The rapid variation of Br contents of halite within this section suggests a shallow saline pan wherein the giant Khorat evaporites were formed. This is contradictory to previous Br profiles of the Lower Salt Member which showed relatively stable and continuously increasing trends. The shallow saline pan model evidenced by high-resolution Br profile is consistent with sedimentary facies and salt mineral textures. [ABSTRACT FROM AUTHOR]

Knowledge on the origin and mechanism of the large potash formation in the southeast Tethyan tectonic domain are still under debate, one of which mainly due to the controversial ages of the potash-bearing strata. Here we present a detailed detrital zircon U-Pb geochronologic-magnetostratigraphic study of the potash-bearing Mengyejing (MYJ) Formation (Fm) from the Simao Basin. 948 paleomagnetic cores and 4 detrital zircon U-Pb samples were collected from a 932-m thick Jiangcheng section. Thermal demagnetization isolated 857 primary characteristic remnant magnetization (ChRM) directions, indicated by positive reversals and fold tests and petrologic examinations. Seven normal and seven reversed polarity zones were identified and correlated well with chrons C27r to C34n of the geomagnetic polarity timescale (GPTS2012), yielding the first known age sequence of >112 to ∼63 Ma for the MYJ Fm. The ages for the potash bearing strata in the Simao commenced ∼20 Ma earlier than those in the adjacent Khorat basins, opposite to the traditional viewpoint that the former would rather correspond to the middle and lower parts of the latter. Given the paleogeographic reconstruction of likely a pan-Simao-Khorat basin during the Cretaceous, ∼85 Ma would be another important potential period for future potash exploration in the Simao Basin. [ABSTRACT FROM AUTHOR]

Slurry erosion-corrosion damage to materials used in mineral processing industries occurs due to the combined effects of electrochemical and mechanical processes. In this study, AISI 2205 duplex stainless steel elbows were tested in a flow loop using slurries consisting 10, 20, 30, 40 and 50 wt.% sand particles and saturated potash brine. Erosion-corrosion tests were conducted at flow velocities of 2.5 and 4.0 m/s. The results of the gravimetric analysis revealed that erosion-corrosion rates increased with increasing particle concentration at both velocities. The elbows exhibited negative synergy for all operating conditions, which is attributed to the presence of passive oxide film on the surface. Microstructural examination of the eroded surfaces showed that materials removal occurred by cutting and plastic deformation. Electron backscattered diffraction analysis suggests that plastic deformation, which occurred approximately 4 µm below the eroded surface, led to the transformation of metastable austenite phase to martensite. [ABSTRACT FROM AUTHOR]

In this study, a diaspore sample is evaluated as a dual source of alumina and potash. The thermal treatment of diaspore with sodium hydroxide yielded alumina and potash values. Microwave heating resulted in enhanced diffusion with improved precipitate purity and recovery with a significant reduction in reaction time. The thermal treatment precipitate comprises alumina purity of 48% with a recovery of 49%. The mechanical milling route yields optimal conditions of 8 h milling followed by acid leaching in 2 M HCl at 50°C for 1 h with ~ 70% and 45% potash and alumina extraction, respectively. The dissociation of the muscovite structure is crucial for high extraction values, and milling time was found to be the significant factor. The milling route at optimal conditions yielded an alumina precipitate with ~ 89% purity with a surface area of 104.6 m2/g and a sylvinite-rich solution, which can be used in fertilizer application. [ABSTRACT FROM AUTHOR]

Polyhalite has been discovered for years in the Triassic of the Sichuan Basin. However, it is difficult to exploit and utilize such polyhalite because of its deep burial depth and its coexistence with anhydrite or dolomite. Therefore, it has always been regarded as "dead ore". Based on slice identification, X-powder diffraction, chemical analysis, REEs analysis and strontium isotope test on halite samples from the fourth and fifth member of Jialingjiang Formation to Leikoupo Formation of Wells ZK601 and ZK001 in Xuanhan area, Northeast Sichuan Basin, this paper discovers thick layers of granular polyhalite associated with halite and the polyhalite content accounts for 10–30%. These deep polyhalites can be obtained by water-soluble mining and utilized, so they are called "new type polyhalite potash deposits". The deposit is deep buried at 3,000 m underground, and the thickness of a single layer can be more than 30 m. It is stable in regional distribution. The discovery of the "new type polyhalite potash deposits" has "activated" polyhalite, which has been considered as deep "dead ore" and has great significance for potash prospecting in China. [ABSTRACT FROM AUTHOR]

China is one country in the world with the largest potash fertilizer-demand. Potash has been listed as one of the seven strategic resources in China for a long time. Qarhan Salt Lake is the earliest discovered large-scale potash deposit in China. It is a comprehensive deposit dominated by liquid potash resource with the coexistence of solid potash minerals (polyhalite, carnallite, sylvite) and other beneficial elements. It is the largest potash fertilizer production base in China. However, with the increase in production year by year, its potash reserves which reach industrial grade are decreasing continuously, and the sustainable production of potash fertilizer faces a severe reserve shortage. So it is particularly noteworthy to us that there are still 296 million tonnes of low-grade solid potash minerals in Qarhan Salt Lake, which have potential utilization value. These low-grade solid potash minerals are equivalent to a superlarge potash deposit. In this paper, we review the efforts to increase potash supply, to upgrade the industrial structures and to promote the healthy and sustainable development of the potash fertilizer industry in Qarhan Salt Lake, then discuss the process of exploitation and utilization of low-grade solid potash minerals, and the problems encountered, finally proposed the corresponding countermeasures suggestions. [ABSTRACT FROM AUTHOR]

Production of lithium carbonate from brines has become the dominate trend in the world since the beginning of the century. Dangxiong Co, located in the interior of the Tibetan Plateau, China, is a carbonate-type lithium salt lake. The lake, rich in Li, B, K and other valuable elements, is of great economic value. The concentration rules of these elements and the salt crystallization paths in the brine were studied in an isothermal evaporation experiment at 25 °C. The sequence in sedimentation of the primary salts, which crystallized from the brine during evaporation experiment at 25 °C, was halite (NaCl)—trona (Na2CO3·NaHCO3·2H2O)—zabuyelite (Li2CO3)—Glaserite (3K2SO4·Na2SO4)—sylvite (KCl)—borax (Na2B4O7·10H2O). This is some different from what one may conclude with the metastable phase diagram of the quinary system Na–K–CO3–SO4–Cl–H2O at 25 °C. Lithium precipitation was a continuous process that occurred throughout the whole experiment. But, it was difficult to obtain high-grade lithium salt during the evaporation operation at 25 °C. Potash was precipitated as Glaserite and sylvite in the experiment with high grade, which made the Dangxiong Co salt lake brine suitable to produce potash. Borax was precipitated in the late stage. High-grade borax could be obtained from Dangxiong Co salt lake brine. The experiment results indicate that the lithium carbonate exploiting technology that is being used on the Zabuye salt lake could be applicable to the Dangxiong Co salt lake. [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]

Mica sample containing 34% alumina and 9% potash has been investigated as a potential dual source of alumina and potash. It was found that planetary milling had a strong effect on structure breakdown as well as on the release of alumina and potash values. Both alumina and potash were extracted from mica using mechanical milling followed by hydrochloric acid leaching and precipitation process. The optimal conditions derived from statistical design yielded 72% alumina and 75% potash values in the form of γ-alumina and sylvinite. The analysis of the final precipitate was carried out by different characterization techniques such as XRD, SEM–EDS, XRF, BET surface area analysis. [ABSTRACT FROM AUTHOR]

In the northeastern Tethys Ocean in the early–middle Triassic, the Sichuan Basin was one of three regions where marine strata developed. Several periods of transgressions and regressions during that time contributed to the development of marine evaporites. The presence of extremely thick evaporites is a basic geological condition for potash formation that is exhibited in the Sichuan Basin, which has been an important region for the exploration of marine potash. The evaporites in the Sichuan Basin are abundant in bromine and possess high bromo-chloro coefficients. Although chlorine isotope values vary significantly within regions, they are relatively low and are similar to the negative values found in the Hechuan and Changshou areas. Comparative studies have been conducted regarding chlorine isotope values in the Sichuan Basin and in other prominent potash-forming basins with results, indicating that sea water concentrations had reached the late stages in the early–middle Triassic and a potential presence of potassium and magnesium salts. [ABSTRACT FROM AUTHOR]

Extensive dissolution of evaporites has occurred in the Williston Basin, Canada, but it is unclear what effect this has had on bulk permeability. The bulk of this dissolution has occurred from the Prairie Evaporite Formation, which is predominantly halite and potash. However, minor evaporite beds and porosity infilling have also been removed from the overlying Dawson Bay and Souris River formations, which are predominantly carbonates. This study examines whether permeability values in the Dawson Bay and Souris River formations have been affected by dissolution, by analyzing 142 drillstem tests from those formations. For both the Dawson Bay and Souris River formations, the highest permeabilities were found in areas where halite dissolution had occurred. However, the mean permeabilities were not statistically different in areas of halite dissolution compared to those containing connate water. Subsequent precipitation of anhydrite is known to have clogged pore spaces and fractures in some instances. Geochemical relationships found here support this idea but there is no statistically significant relationship between anhydrite saturation and permeability. Geomechanical effects, notably closure of fractures due to collapse, could be a mitigating factor. The results indicate that coupling dissolution and precipitation to changes in permeability in regional flow models remains a significant challenge. [ABSTRACT FROM AUTHOR]

The Paleocene Shashi Formation, the host formation of potassium-rich brines and solid potash in the Jianghan Basin, central China, is characterized by rift sediments in a composite basin-mountain system. However, the provenance of the Paleocene Jianghan Basin remains poorly understood. A combined study of petrographic examination, geochemical analysis, and zircon U-Pb dating was conducted to characterize the provenance of the Shashi Formation. The petrographic analysis of the Shashi Formation reveals that these samples have predominantly quartz-lithic compositions with minor contributions from other minerals. Whole-rock geochemical data indicate that this formation experienced only slight to moderate alteration. The chondrite-normalized rare earth element (REE) patterns of these samples are essentially parallel to those of the upper continental crust (UCC), as their negative Eu-anomalies and Th/Sc and La/Th ratios suggest an average source composition similar to that of the UCC. These values, together with plots of their Th/U vs. Th ratios, suggest that certain samples have undergone moderate degrees of weathering and sedimentary recycling. The analysis of major and trace elements (i.e., La/Th-Hf, Th/Sc-Zr/Sc, La/Y-Zr/Sc, TiO2-Fe2O3T + MgO, Al2O3/SiO2-Fe2O3T + MgO) indicates that their sedimentary sources were felsic rocks from an active continental margin or a continental arc containing a minor amount of recycled sediments derived from a passive continental margin. The Shashi Formation contains detrital zircons that primarily have U-Pb ages of 2.5, 1.8 Ga, 725-965, 425-475, 310-350 and 200-260 Ma. These results reveal that the pre-Ordovician zircons are derived from recycled sediments of the Yangtze Block and thus originate from the surrounding ranges. The magmatic rocks of the South Qinling Belt and the Jiangnan Orogen are responsible for supplying the Ordovician to Triassic detrital zircons. These provenance data combined with paleocurrent analyses can be used to identify multiple source characteristics in the Jianghan Basin. During the Early Paleocene, most clastic material was derived from a southern source; during the Late Paleocene, northern and western sources contributed most of the detritus to the basin. The supply of clastic material was thus broadly variable and widely dispersed throughout the basin. This study shows that the architecture of the region and the rifting process exerted important influences on this sediment dispersal. [ABSTRACT FROM AUTHOR]

The paper describes the principal geomechanical approaches to mine dimensioning in salt and potash mining, focusing on stability of the mining system and integrity of the hydraulic barrier. Several common dimensioning are subjected to a comparative analysis. We identify geomechanical discontinuum models as essential physical ingredients for examining the collapse of working fields in potash mining. The basic mechanisms rely on the softening behaviour of salt rocks and the interfaces. A visco-elasto-plastic material model with strain softening, dilatancy and creep describes the time-dependent softening behaviour of the salt pillars, while a shear model with velocity-dependent adhesive friction with shear displacement-dependent softening is used for bedding planes and discontinuities. Pillar stability critically depends on the shear conditions of the bedding planes to the overlying and underlying beds, which provide the necessary confining pressure for the pillar core, but can fail dynamically, leading to large-scale field collapses. We further discuss the integrity conditions for the hydraulic barrier, most notably the minimal stress criterion, the violation of which leads to pressure-driven percolation as the mechanism of fluid transport and hence barrier failure. We present a number of examples where violation of the minimal stress criterion has led to mine floodings. [ABSTRACT FROM AUTHOR]

A field experiment was established to support the hypothesis that application of different silicon (Si) fertilizers can simultaneously reduce cadmium (Cd) and arsenic (As) concentration in rice grain. The 'semi-finished product of Si-potash fertilizer' treatment at the high application of 9000 kg/ha (NP+S-KSi9000) significantly reduced the As concentration in rice grain by up to 20.1 %, compared with the control. Si fertilization reduces the Cd concentration in rice considerably more than the As concentration. All Si fertilizers apart from sodium metasilicate (NaSiO) exhibited a high ability to reduce Cd concentration in rice grain. The Si-calcium (CaSi) fertilizer is the most effective in the mitigation of Cd concentration in rice grain. The CaSi fertilizer applied at 9000 kg/ha (NPK+CaSi9000) and 900 kg/ha (NPK+CaSi900) reduced the Cd concentration in rice grain about 71.5 and 48.0 %, respectively, while the Si-potash fertilizer at 900 kg/ha (NP+KSi900), the semi-finished product of Si-potash fertilizer at both 900 kg/ha (NP+S-KSi900) and 9000 kg/ha (NP+S-KSi9000), and the rice straw (NPK+RS) treatments reduced the Cd concentration in rice grain about 42, 26.5, 40.7, and 23.1 %, respectively. The results of this investigation demonstrated the potential effects of Si fertilizers in reducing Cd and As concentrations in rice grain. [ABSTRACT FROM AUTHOR]

A study was performed to evaluate radioactive concentrations in three categories of fertilizers, phosphate (0-46-0); potash (0-0-60); and NPK (13-13-13) using gamma spectroscopic techniques. The experimental analyses indicated mean concentrations of 697 ± 15, 8.9 ± 1.0 and 47 ± 12 Bq kg of Ra, Th, and K, respectively, in phosphate fertilizers. Potash fertilizers had the average levels of 1.1 ± 0.10, 0.40 ± 0.05, and 15,162 ± 1017 Bq kg of Ra, Th, and K, respectively. The NPK fertilizers contained 7.45 ± 2.76, 2.63 ± 0.29, 3581 ± 601 Bq kg of Ra, Th, and K, respectively. Based on the measured activities, the radiological health hazard parameters are assessed and compared with the U.S. acceptable dose limits. [ABSTRACT FROM AUTHOR]

Reasons are analyzed for breakdown of a screw dissolver in a modernized scheme for potash production. It is revealed that modernization of the mixing scheme for working flows leads to accelerated corrosion and erosion breakdown of equipment units and assemblies. [ABSTRACT FROM AUTHOR]

Corrosion resistance of equipment for potash production by a halurgical method is studied. Results are provided for accelerated electrochemical corrosion resistance tests for stainless steels in model working production media. [ABSTRACT FROM AUTHOR]

Solutions containing 500 g L NbO were obtained by sintering NbO with potash followed by leaching with water. The potassium niobate released from niobium(V) alkaline solutions was examined with an application of methods of physical and chemical analysis. Hydrates KNbO·4HO and K[HNbO]·14HO were first obtained. [ABSTRACT FROM AUTHOR]

Ten phosphate solubilizing pseudomonads isolated from a partially recultivated potash tailings pile in Germany were characterized and tested for their potential to assist in the ongoing recultivation process. Despite fertilization, the plants which are grown for recultivation show phosphate deficiency symptoms, and therefore the isolates are intended to be used as biofertilizer inoculants. On agar plates incubated at five different temperatures, some of the strains showed a temperature-dependent ability to solubilize tricalcium phosphate, while others performed the same at any given temperature. In liquid medium, the isolates solubilized between 271 and 730 μg ml of phosphate from tricalcium phosphate. Both the weakest (designated S10) and the strongest solubilizing strain (S06) were further tested for their viability during solubilization. In an assay over the course of 1 week, both strains released their maximum amount of phosphate after 2-4 days. At that later point of time, however, viable cells of isolate S06 were no longer detectable, whereas the weaker strain S10 could be cultured after 1 week in broth. Taking all in vitro observations into account, the usability of the isolates as biofertilizers is critically discussed regarding both the in situ conditions on the tailings pile and the lowered viability due to the excess production of organic acids. [ABSTRACT FROM AUTHOR]

A convenient and clean procedure for esterification is reported. Direct condensation of formylphenoxyaliphatic acids with low to high boiling alcohols catalysed by potash alum gave moderate to good yields. This catalyst could be recovered and reused without substantial loss in its catalytic activity and the methodology could be used for a range of closely related substrates. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The authors consider a number of geomechanical monitoring methods for the underworked salt rock behavior, including visual control of its specific structural features, measurement of displacements using contour and depth reference points, and assessment of stresses in the surrounding rock mass. It is proposed to assess stresses in salt rocks using long spacing measurement methods without modeling-based recovery of stresses from measured strains if possible. [ABSTRACT FROM AUTHOR]

fter potash ore has been mined and processed it is stored and shipped as bulk granular particles. If these particle beds are exposed to a relative humidity that is above 50%, moisture will accumulate in the bed. This causes the formation of concentrated brines on the surfaces of the particles that migrate toward the contact points between particles. If drying occurs crystal bridges at or near the contact points will form between particles. When large numbers of crystal bridges are formed per unit volume of bed, the bed is said to be caked. In this paper, the Discrete Element Method (DEM) is used to analyze the micro-mechanical behaviour of ideal spherical or ellipsoidal particles inside a potash bed and these results can be used to determine the cake strength. Hertz contact compressive stress theory is applied at each contact point between particles to resolve the stiffness matrix in the DEM analysis. The results of the DEM analysis compare well to those obtained using continuum mechanics for the case of a caked test ring in a centrifuge, especially when Poisson's ratio has a low value. [ABSTRACT FROM AUTHOR]

The modified variable module method, based on the a priori information about the intensifying daylight surface subsidence in time, is developed. The practical application of the proposed rheological analysis scheme is considered for the chamber mining of potash series. [ABSTRACT FROM AUTHOR]

Two potash-lime-silica model glasses with compositions similar to those of medieval stained glass were exposed at 26 test sites all over Europe and in North America for 3–6 years. The objectives of this large-scale field exposure programme were: (a) a qualitative analysis of the weathering products formed on the surface of the samples in the (environmental) scanning electron microscope in combination with energy dispersive X-ray microanalysis (ESEM/EDX or SEM/EDX, respectively); (b) a statistical evaluation of the weathering phenomena by applying a multiple linear regression (MLR) analysis to find correlations between the degree of weathering, which was measured in terms of surface coverage with reaction products, and environmental parameters such as the concentration (c) of the acidifying gases SO2, NO2 and O3, the temperature (T) and the relative humidity (RH); and (c) the calculation of a time-dependence function of the weathering process of these glasses. Mainly sulfates of calcium and potassium such as gypsum (CaSO4·2 H2O), arcanite (K2SO4) and syngenite (CaSO4·K2SO4·H2O) could be identified in the SEM and ESEM. Carbonates, nitrates and many particles deposited on the glass surface were found as well. MLR calculations exhibit significant dependencies of the degree of weathering on T, RH, c(NOx), c(SO2) and c(O3). Applying a time-dependence function of the general form y=a·tb (t=time) results in a value of approximately 0.42 for the exponent b, which comes close to values expected from various studies in the literature. [ABSTRACT FROM AUTHOR]

The article cites a study conducted to determine pesticide residue concentrations in surface and groundwater bodies at the southern edge of the Dead Sea in Israel and Jordon as these sites are agricultural areas with a potential for reuse of water from large industries existing in the area such as potash and other salt extraction from the Dead Sea region. Results of the study revealed that most samples of heavy metal content, except iron and some samples of manganese, in both surface and groundwater are low and it could be attributed to the high pH value of the water samples enhancing heavy metal precipitation in addition to low human activities in the investigated area.

Studies the association of mineral deposits to hydrothermal processes. Presence of potash in percolating fluids; Evaluation of aerogrammaspectrometric data-processing methodologies; Contribution of lithological and soil variations to environmental conditions.

The worldwide sea-level fluctuations during the Pyrenean Orogeny caused substantial regressions in the north of Central Iran during the Eocene-Oligocene time. These orogenic activities shaped shallow marginal marine basins in some regions, which were sites for subsequent evaporite deposition. One of these sites is located in the north of the Garmsaraea (SE of Tehran) and contains gypsum, anhydrite, halite, sylvite, calcite, dolomite and some other evaporite minerals, of considerable thickness. Field, petrographic and geochemical studies showed that these evaporites precipitated in semi-restricted shallow marginal marine basins, which were sporadically influxed by continental runoff and normal seawater. As their well-preserved microfabrics exhibit, most of the evaporite minerals were precipitated in a marine realm and after syndepositional cementation buried to shallow depths. Postdepositional alterations by meteoric waters were not prevalent as it is reflected in their well-preserved primary (depositional) microtexture and high Br contents of evaporite minerals. Geochemical studies showed that the brine's ions originated from normal seawater with possible contributions from submarine volcanic emissions or leaching of volcanic rocks. The Bromometery technique is employed to define the origin of the potash deposits, their distribution in the evaporite sequences of the area and reconstruction of their depositional environment. High Br content of most evaporite minerals clearly indicates their marine origin, and confirms absence of meteoric alterations that usually, causes Br depletions. [ABSTRACT FROM AUTHOR]

The impact assessment of the consumption of abiotic resources, such as fossil fuels or minerals, is usually part of the Life Cycle Impact Assessment (LCIA) in LCA studies. The problem with the consumption of such resources is their decreasing availability for future generations. In currently available LCA methods (e.g. Eco-indicator’ 99/Goedkoop and Spriensma 1999, CML/Guinée 2001), the consumption of various abiotic resources is aggregated into one summarizing indicator within the characterization phase of the LCIA. This neglects that many resources are used for different purposes and are not equivalent to each other. Therefore, the depletion of reserves of functionally non-equivalent resources should be treated as separate environmental problems, i.e. as separate impact sub-categories. Consequently, this study proposes assigning the consumption of abiotic resources to separate impact sub-categories and, if possible, integrating them into indicators only according to their primary function (e.g. coal, natural gas, oil → consumption of fossil fuels; phosphate rock → consumption of phosphate). Since this approach has been developed in the context of LCA studies on agricultural production systems, the impact assessment of the consumption of fossil fuels, phosphate rock, potash salt and lime is of particular interest and serves as an example. Following the general LCA framework (Consoli et al. 1993, ISO 1998), a normalization step is proposed separately for each of the subcategories. Finally, specific weighting factors have been calculated for the sub-categories based on the ’distance-to-target’ principle. The weighting step allows for further interpretation and enables the aggregation of the consumption of different abiotic resources to one summarizing indicator, called the Resource Depletion Index (RDI). The proposed method has been applied to a wheat production system in order to illustrate the conceptual considerations and to compare the approach to an established impact assessment method for abiotic resources (CML method, Guinée 2001). [ABSTRACT FROM AUTHOR]

The aim of this work is to give a summary of the work on Cs-137 in Swedish lakes carried out mainly by our group (the Liming-mercury-caesium project) between 1986 and 1990. The focus is on results from extensive field experiments carried out in 41 lakes testing various remedial measures to speed up the natural recovery of Cs-137 in lakes: Lake liming and wet land liming with primary rock lime, sedimentary rock lime and so-called mixed lime, which also contains nutrients; potash treatment and intensive fishing. Selected results: The remedies have given the intended water-chemical response. None of the methods used works effectively as 'cure', i.e., no rapid and clear reduction in the concentrations of radioactive caesium in fish is obtained in comparison with lakes where the waterchemical or biological conditions are not changed. In lakes with long water turnover time and with low values of, foremost, conductivity, hardness and potassium, the fish had relatively higher concentrations at the same fallout levels. The differences present between the lakes as regards the continued magnitude of the change in concentration in fish can foremost be linked to factors controlling the secondary load (i.e., the internal loading and the input from the catchment). A successful potash treatment (in oligotrophic lakes) may imply that the natural recovery will be at the most 5% faster compared to no treatment. This would give quite positive implications in the long run since the ecological half-life for Cs-137 in pike (the top predator in these lake types) is very long. The time interval between the remedies and the latest fish analyses (about 2 years on average) is not sufficient to obtain (statistically) clear-cut results on these the small effects of the remedies. A longer time series of data is required for this. [ABSTRACT FROM AUTHOR]

The article presents a study which aims to investigate the toxicity of the various dilutions of potash brines on the early developmental stages of the Atlantic salmon (Salmo salar). The study used Atlantic salmons from the Mactaquac Hatchery of the Canadian Department of Fisheries and Oceans and potash brines, potassium chloride (KCl), and sodium chloride (NaCl) dilutions. Results show that newly feeding Atlantic salmon fry were the most sensitive to potash brine.