Jurnal Puslitbang tekMira (Teknologi Mineral dan Batubara)
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EFFECTS OF TEMPERATURE AND NUTRIENT FEED ON THE PRODUCTION OF OXALIC ACID BY ASPERGILLUS NIGER
No full textOxalic acid is an important organic material used for rare earth metal extraction precipitator, metallic equip- ment purificant and purification of industrial minerals. Aspergillus niger is known to be able to produce a high concentration of oxalic acid using glucose as carbon and energy sources. For further process optimiza- tion, submerged fermentation experiments were carried out to study the effect of temperature and nutrient feed on the production of oxalic acid from medium containing glucose 35g/L. An increase in temperature process from 25 to 30°C allowed the productivity to significantly increase from 75.50 to 81.06% of theoretical yield with a final oxalic acid concentration of 17.04 g/L reached after 9 days of process. When operating at more controlled fermentor with fed-batch system, both productivity and oxalic acid concentration were markedly improved (88.01% of theoretical yield and 19.52 g/L respectively). The later system gave excel- lent yield almost 90% of theoretical yield as a prerequisite of economical value
IMPROVEMENT OF LOW RANK COAL PROPERTIES BY VARIOUS UPGRADING PROCESSES
No full textA low rank coal from Banko, South Sumatera was used to study the properties improvement of the coal due to coal upgrading process. Various coal upgrading processes were conducted i.e. upgraded brown coal (UBC), hot water drying (HWD) and steam drying (SD). The UBC process was carried out in pilot scale with a capacity of 5 tons/day at temperature of 160°C and pressure of 0.35 MPa, while the HWD and SD pro- cesses were conducted in laboratory scale using autoclave at the temperature of 300ºC and pressure of about 12 MPa for 1 hour. The result indicates that the properties of Banko coals after the UBC, HWD and SD processes were improved. The calorific value of the upgraded coals was significantly increased in relevant to the decreasing of inherent moisture content and have better combustion characteristics than that of the raw coal. The highest calorific value can be achieved by SD process, followed by HWD and UBC processes
CHARACTERISTICS OF SELECTED MANGKALIHAT COALS ACCORDING TO PETROGRAPHIC AND PROXIMATE ANALYSES
No full textA carbonate complex in the Mangkalihat area, East Kalimantan, has been selected for this study, because this area has some coal deposits associated with dominant limestone intercalated by thin claystone and sandstone. Commonly, most Indonesian coals were formed in fluvial and deltaic depositional environment. Accordingly, this study is interesting due to the depositional environment of the coals in association with a marine condition. This environment mostly results in relatively high mineral matter and sulphur contents, particularly pyrite in this study; brighter lithotype and dominant vitrinite content over liptinite and inertinite. The geologic factors have clearly proven a good correlation among the results of megascopic, microscopic and proximate analyses. The coals with brighter lithotype, high vitrinite and moisture contents were formed under a wetter marsh environment. On the other hand, the duller lithotypes with the presence of inertinite and mineral matter were deposited in a dryer marsh environment. The presence of high pyrite and sulphur contents strongly indicates a marine incursion during the coal forming in this area
TRENDS IN SUPPLY / DEMAND FOR INDONESIAN COAL PERIOD 2005 - 2025
No full textIn 2008, Indonesia mineable coal reserve was recorded around 7.12 billion tons. During that year, around231.18 million tons were exploited. Of such a figure, 69.44 million tons went to domestic market and the rest belonged to export. Yet, in 2025 the need of coal for local consumption may reach 192.33 million tons that include 99.86 million tons for steam power plant, 30.58 million tons for cement industries, and 17.59 million tons for textile industries. Pulp and other industries may consume 2.92 million tons and 41.39 million tons respectively. It is assumed that in 2025, Indonesian coal export will increase to 260.92 million tons Coal export is assumed to increase figuring Coal Mining Agreement as the biggest exporter (94.03%). The rest goes to Mine authority (3.55%) and State-owned Enterprises (2.43%). However, the possibility of unre- corded coal utilization for ether domestic use and export reaches 51.66 million tons. As a result, it is presumed that Indonesian coal production in 2025 is around 504.92 million tons. The production rate during 2010-2025 is 4.9% per annum. According to the above condition, the mineable coal reserve of 7.12 million tons will probably be finished for about 18 years. In addition, the coal-steamed power that operates until now has an age of 26 years. If the reserve is not well-managed, it will immediately be finished in the shorter time. That is why, it needs an anticipative step of a policy concept that can maintain a sustainability of the domestic coal stock by implementing a limited export
THE RECOVERY OF GOLD FROM A PREAGNANT GOLD-THIOSULFATE LEACH SOLUTION USING ION EXCHANGE RESIN
No full textThe loading of gold and copper from a pregnant gold thiosulfate leach solution onto ion exchange resin and the subsequent elution of these metals have been investigated. In this study, strong basic resins of Amberjet-4200 and IRA-400 were used and thiocyanate was used as eluent. It was found that on Amberjet-400, the gold loading reached about 2-3 kg/t, in correspondence to 0.4 ppm gold in the effluent.On IRA-400, the performance was almost exactly the same loading as on Amberjet- 4200 but with the effluent gold concentration being slightly higher. In leach solutions, copper is present in much higher concentrations than gold, since it is added as a catalyst for gold dissolution. The maximum Cu loading obtained on Amberjet-400 was about 22 kg/t while it was about 24 kg/t on IRA-400. These results indicate that gold can be removed from thiosulfate solutions rapidly and loaded on resins to very high concentrations. Subsequent gold elution with thiocyanate ions was very efficient; the concentration of gold on resin was reduced from about 2-3 kg/L down to less than 10 ppm (99,9% elution) under ambient temperature in 2-4 hours
