Jurnal Puslitbang tekMira (Teknologi Mineral dan Batubara)
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DESORPTION OF GOLD AND SILVER FROM ACTIVATED CARBON
No full textExperiments of gold and silver elution were conducted using several parameters, either fixed or varying parameters. Ethanol volume, temperature and percent solid belonged to varying parameters while loaded carbon, stirring rate, concentrations of NaOH and NaCN served as fixed parameters. The experiment results showed that the optimum condition for such a process included 20% of ethanol volume, 80°C of temperature and solid fraction of 25%. Using such condition, the experiment was conducted for 10-hour contact time and yielded the highest desorption percentages for gold and silver, namely 80.10 and 70.73% respectively. The derived contents of gold and silver were 295.16 and 159.38 ppm while their achieved weights were 56.080 and 30.601 µ g. The fact that the achieved contents of gold and silver was close to the requirements for electrowinning process, it is suggested that the next process using a semi-continue one in terms of gaining a result that satisfies the requirement for electrowinning
THE LOCAL CONTENTS OF INDONESIA’S NICKEL MINING COMPANIES
No full textAnalysis on the local content of Indonesia mineral mining company is intended to provide input in compiling draft regulation of the Minister of Energy and Mineral Resources regarding the use of domestic goods and services in mineral and coal mining activities, as a follow up the implementation of Government Regulation Number 23/2010 Article 88. A direct sampling survey was conducted to several nickel mining companies. The results showed that the local content for groups of goods and services at PT Vale Indonesia were 51.04% and 46.06% respectively, while at PT Antam Tbk. was 100% (groups of goods) and 99.6% (services). Based on national labour aspect, the local contents of five companies were relatively high, namely 98.63%, however, those came from province and regency areas were only 67,97% and 39.20% respectively. PT Vale Indonesia empowered 84.41% local manpowers from Sorowako area with the measured local content of nickel matte around 43.59%. The measure local content indicated that there was a big opportunity to increase the local content. Some factors that inhibited the effort to increase the use of domestic products included not smoothly the information flow, opportunities and transparency of product testing, the requirements of the Indonesia National Standard, the price preference in the tender process, tax issues, permit dangerous products as well as human resources issues
EVALUATION OF SELECTED HIGH RANK COAL IN KUTAI BASIN, EAST KALIMANTAN RELATING TO ITS COKING PROPERTIES
No full textAbundant coal seams of Miocene age with thickness of up to 4.7 metres occur in Kutai Basin, East Kaliman- tan. Selected coals are analyzed in order to evaluate its coking properties. The coals have bituminous in rank with calorific value of 5,582-8,357 kg/kcal (adb) and vitrinite reflectance of 0.57-0.97%. These selected high rank coals are normally concentrated in high gradient temperature zone or proximity to intrusive body. Vitrinite reflectances of these coals are lower than those of Australian coking coals (1.04-1.06%), but higher than of Indonesian normal coalification coals. Vitrinite is the dominant maceral in coals from Kutai Basin (73-96%), while inertinite and liptinite are only present in small amount, i.e. trace-10.2% and trace-8.2%, respectively. In contrast, vitrinite is lower and inertinite is higher in Australian coking coals, i.e. 64.8- 79.0% and 18.4-31.6%, respectively. Generally, crucible swelling number of Kutai Basin coals is lower than of Australian coking coals. Based on its vitrinite reflectance and calorific values, some of selected high rank coals from Kutai Basin have developed semi coking properties. The enhancement of rank is probably due to the effect of igneous intrusions or high gradient temperature. However, vitrinite content of the coals is higher than of coking coal range. Crucible swelling number of the coal is also too low, except for sample EK 1 and EK 2 which have CSN too much of 6 and 4, respectively. Therefore, the coals are not categorized as prime coking coal, but they can be blended with bituminous inertinite rich coals to make metallurgical coke for blast furnace
COAL DE-ASHING BY SOLVENT EXTRACTION
No full textCoal contains mineral matter that will be left as ash after coal is burned. Coal will be referred to as dirty coal if the ash content of the coal is high. High ash content is not preferred by consumers of coal users especially coal fired power plants, because ash content will produce fly ash and bottom ash that cause environmental problem. The process of ash content reduction by solvent extraction would produce coal with very low ash content (near zero) known as ash free coal (AFC). The study of ash content reduction was conducted by using Peranap coals that were taken from stockpile and mine site. The coals were then washed and separated into coals with low and high ash contents. The high ash content of coals from stockpile (46.02%) and mine site (25.02%) were then extracted using solvent. Three kinds of solvent have been tested, namely 1-methyl naphthalene, 1-1-1-methoxy ethoxy acetic acid and N-methyl 2 pyrolidynon. The results indicate that the ash content of coal derived from the stockpile decreased to 0.06% and coal from the mine site decreased to 0.11% by using 1-methyl naphthalene solution with a ratio of coal and solvent of 1: 6 (weight/weight)
