IMPREGNATION AND RECOVERABILITY OF ELEMENTAL SULFUR IN COAL USING THE PERCHLOROETHYLENE DESULFURIZATION PROCESS

ABSTRACT

During the perchloroethylene extraction process, C-S bond cleavage reactions occur, which liberate labile sulfur from the organic matrix of coal into the solvent medium i.e., perchloroethylene, where it is dissolved and extracted. In this paper, the effect of impregnation of elemental sulfur in raw coal on its forms of sulfur analyses has been investigated. The effect of the same sulfur-impregnated coal on its organosulfur extractability has also been explored. Studies were conducted to observe whether the impregnated elemental sulfur was fully recoverable by the perchloroethylene extraction process. It was observed that sulfur can be very easily impregnated into the microstructure of coal. On the basis of tests on raw and impregnated coals, based on ASTM D-2492 standard, the impregnated sulfur reflects mostly in the form of organic sulfur. The impregnated sulfur which appears in the form of organic sulfur is fully recoverable via the perchloroethylene extraction     

High temperature electrode‐electrolyte interface formation between LiMn1.5Ni0.5O4 and Li1.4Al0.4Ge1.6(PO4)3

All‐solid‐state lithium‐ion electrolytes offer substantial safety benefits compared to flammable liquid organic electrolytes. However, a great challenge in solid electrolyte batteries is forming a stable and ion conducting interface between the electrolyte and active material. This study investigates and characterizes a possible solid‐state electrode‐electrolyte pair for the high voltage active cathode material LiMn_1.5Ni_0.5O₄ (LMNO) and electrolyte Li_1+xAl_xGe_2‐x(PO₄)₃ (LAGP). In situ X‐ray diffraction measurements were taken on pressed pellets comprised of a blend of LMNO and LAGP during exposure to elevated temperatures to determine the product materials that form at the interface of LMNO and LAGP and the temperatures at which they form. In particular, above 600°C a material consistent with LiMnPO₄ was formed. Scanning electron microscopy and energy‐dispersive X‐ray spectroscopy were used to image the morphology and elemental compositions of product materials at the interface, and electrochemical characterization was performed on LMNO‐coated LAGP electrolyte pellet half cells. Although the voltage of Li/LAGP/LMNO assembled batteries was promising, thick interfacial phases resulted in high electrochemical resistance, demonstrating the need for further understanding and control over material processing in the LAGP/LMNO system to reduce interfacial resistance and improve electrochemical performance.     

A simplified colorimetric micromethod for determination of serum cholesterol

A simple and rapid micromethod is described for quantitation of cholesterol in 5–10 μl of serum using uranyl acetate to deproteinize the serum ando-phthalaldehyde reagent to develop color. Independent analyses of serum samples by the present method and by two reference methods, Abell-Kendall and automated colorimetric method, indicated accuracy of the micromethod (r=0.99). Use of capillary blood specimens makes this procedure applicable for screening infants and small children.     

EFFECT OF PYRITIC SULFUR AND MINERAL HATTER ON ORGANIC SULFUR REMOVAL FROM COAL

Abstract

The perchloroethylene coal cleaning process uses perchloroethylene as the solvent to remove both organic and inorganic forms of sulfur without any significant loss to its calorific value. The process removes these forms of sulfur in two sequential unit steps. The objective of this investigation was to determine the exact sequence of operations in the Process. Hence, organosulfur was removed before and after depyriting and demineralizing the coal. The extent of total sulfur as well as organic sulfur removal were compared in both cases. It was found that the desulfurization is more efficient when organosulfur is extracted before pyritic sulfur and not vice versa, in the sequential removal of organic and inorganic forms of sulfur. The data presented in this paper reestablishes a fact that the mineral matter content in coal is quintessential to its organosulfur extractability.     

EFFECT OF FILTRATION TEMPERATURE ON ORGANIC SULFUR REMOVAL FROM COAL BY PERCHLOROETHYLENE COAL CLEANING PROCESS

Abstract

The perchloroethylene extraction desulfurization process removes the organic sulfur in coal via a hybrid mechanism of solvent extraction and chemical reaction. The nature and extent of the reaction is controlled by the extraction time and temperature of operation. Although the extraction temperature is kept identical for all types of coals (120°C), the organosulfur extraction time still depends upon the type of coal. If the reaction mixture is left too long in the extraction environment, the intermediate labile sulfur released by the reaction forms cross-links with the organic matter in the macromolecule of coal. This is detrimental to the process efficiency. Constant temperature has to be maintained throughout the extraction, till coal is separated from the solvent. If not, the extracted labile sulfur re-enters the coal macromolecule to form inter-penetrating polymer networks with the organic matter in coal. In this paper, it has been established that the time required for separation and isothermality of the process are crucial to maintain the reaction progressing toward sulfur and organic sulfur liberation from the macromolecule. The data presented in this paper are important from the viewpoint of process development, because the process mandates the separation of coal and solvent at the operating temperature.     

Enhanced field-emission from SnO2:WO(2.72) nanowire heterostructures

The field-emission properties of SnO(2):WO(2.72) hierarchical nanowire heterostructure have been investigated. Nanoheterostructure consisting of SnO(2) nanowires as stem and WO(2.72) nanothorns as branches are synthesized in two steps by physical vapor deposition technique. Their field emission properties were recorded. A low turn-on field of ~0.82 V/μm (to draw an emission current density ~10 μA/cm(2)) is achieved along with stable emission for 4 h duration. The emission characteristic shows the SnO(2):WO(2.72) nanoheterostructures are extremely suitable for field-emission applications.     

Ground penetrating radar (GPR) study to detect seepage pathways in the Ajanta Caves in India

The present study used the ground penetrating radar (GPR) tool to decipher the presence of fractures which may be possible pathways for seepage into the Ajanta Caves in India. GPR data were collected by 40- and 200-MHz antennas from Geophysical Survey Systems, Inc. (GSSI). The data were edited and processed using the RADAN 6.5 software. The processed data indicate the presence of fractures of varying orientation in the basaltic formations. The study shows high reflection zones indicative of fractures as well as strong absorbance zones which may be a homogeneous zone without any fractures.     

COBENEFICIATION OF COALS IN PERCHLOROCTHYLENE EXTRACTION DESULFURIZATION

The perchloroethylene (PCE) coal refining process has been investigated for its process feasibility, operational reproducibility, organic sulfur selectivity, process efficiency, minimization of residual chlorine by steam stripping and process optimization. It was found that some coals result in a better organosulfur extraction than others. It was also confirmed that the PCE extraction process was a hybrid system of chemical reaction and physical solvation. It was further established that the coals giving a higher organosulfur extraction contain some naturally available ingredients, which promote the extraction process. Coals giving a much lower organosulfur extraction lack these species. This paper focuses on demonstration of the process feasibility of cobeneficiating both types of coals, together. In this novel process, both types of coal are blended together in fixed proportions and subjected to the PCE process. This process of cobeneficiating coals is industrially significant because of its cost effectiveness. It not only removes the organosulfur from one type of coal, but also significantly improves the organosulfur extraction from the other.     

EFFECT OF FILTRATION TEMPERATURE ON ORGANIC SULFUR REMOVAL FROM COAL BY PERCHLOROETHYLENE COAL CLEANING PROCESS

The perchloroethylene extraction desulfurization process removes the organic sulfur in coal via a hybrid mechanism of solvent extraction and chemical reaction. The nature and extent of the reaction is controlled by the extraction time and temperature of operation. Although the extraction temperature is kept identical for all types of coals (120°C), the organosulfur extraction time still depends upon the type of coal. If the reaction mixture is left too long in the extraction environment, the intermediate labile sulfur released by the reaction forms cross-links with the organic matter in the macromolecule of coal. This is detrimental to the process efficiency. Constant temperature has to be maintained throughout the extraction, till coal is separated from the solvent. If not, the extracted labile sulfur re-enters the coal macromolecule to form inter-penetrating polymer networks with the organic matter in coal. In this paper, it has been established that the time required for separation and isothermality of the process are crucial to maintain the reaction progressing toward sulfur and organic sulfur liberation from the macromolecule. The data presented in this paper are important from the viewpoint of process development, because the process mandates the separation of coal and solvent at the operating temperature.