Jurnal Puslitbang tekMira (Teknologi Mineral dan Batubara)
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EFFECT OF COAL UPGRADING ON RHEOLOGY OF COAL WATER MIXTURE
No full textCoal water mixture (CWM) is coal-water slurry in which particles of coal with a certain particle size distribution are suspended in water. CWM is required to have the highest possible coal concentration and a moderate viscosity in order to make handling easy. The main purpose of this study is to obtain the effect of coal upgrading on the rheology of CWM in terms of finding the most suitable dispersing additive in producing CWM with highest coal concentration. Two kinds of coal, raw and upgraded coal, from three areas in Indonesia have been used. Three kinds dispersing additives, i.e. formalin conden- sation product of naphthalene sulfuric acid (NSF), polystyrene sulfonic acid (PSS) and poly (meth) acrylate (PMA) were tested to produce CWM with good flow characteristics. The rheology of CWM was prepared, measured by a stress control type rheometer (Rheometric Scientific Co. Ltd., SR-5) in steady shear mode at 25ºC. The apparent viscosity of upgraded coals showed a better slurry-ability of CWM as a function of coal concentration for every dispersing additive compared to the raw coal
ASSESSMENT OF INDIGENOUS MICROORGANISM FOR NATURAL ATTENUATION OF ABANDONED MINE SITE
No full textSoil samples taken from an abandoned gold mine site in East Kalimantan exhibited high concentra- tion of manganese (9,830-13,190 mg/L), iron (340-8,060 mg/L) and arsenic (160-510 mg/L). However, the indigenous microbial population was found to be present at high level (> 107 CFU/g), indicated that the site matrix did not appear to be inhibitory and relatively favorable to microbial growth. Furthermore, laboratory microcosm studies showed that the indigenous microorganisms possessed a considerable bioremoval potential of contaminated metal at the site. Those results suggested that natural attenua- tion of metal bioremoval would occur under present site condition
PREDICTION OF MINE DRAINAGE QUALITY BY KINETIC TESTS
No full textKinetic test is one of the methods to predict acid mine drainage. The test shows the acceleration of natural oxidation rate over those observed in the field. This may have the advantage of condensing time, and providing earlier insight into the potential for acid generation. Generally, kinetic test evalu- ates the changes in pH, sulfate, acidity and host of potential metals. However, the test also has high degree uncertainty. To minimize the uncertainty it needs to calibrate and validate the model of kinetic test by comparing prediction model with actual field sampling results. As field data availability for validation is limited, it is strongly suggested that researcher should make a continuous research from the prediction and the actual sampling using many methods
EFFECT OF HYDROTHERMAL DEWATERING ON COKE ADDITIVE MAKING FROM LOW RANK COAL (LRC)
No full textThis paper describes a study of the effects of hydrothermal dewatering (HTD) of Jambi, Pendopo and Wahau low rank coals, on additive characteristics. Hydrothermal upgrading and dewatering of the coals were carried out in a batch-type autoclave reactor at temperatures 350°C at a maximum pressure of 30 bar for 30 min. The dried sample resulted from hydrothermal process mixed with liquid fraction tar solvent at 250-350°C with ratio 4:6, was input in the 0,5 l autoclave to conduct hydrogenation process with variation initial hydrogen pressure of 10, 20, 30, 40, 50 bar, and reaction temperature of 400°C for 1 hour. The process of hydrothermal treatment before hydrogenation produced a higher calorific value having an average of >8000 cal/g (air dried basic, adb). Ash content and volatile matter for the coal were increased with the increasing initial hydrogen pressure. Corrected hydrogen content steadily increased after hydrothermal process and hydrogenation while the corrected oxygen decreased drastically after the hydrogenation process. Fuel ratio of Jambi, Pendopo and Wahau coals after hydrothermal process also increase reached 1.58, 1.04 and 1.77 respectively. Overall results indicate the impor- tance of introducing a hydrothermal treatment step for the improvement of the coke additive characteristics
