Mineralogy and Geochemistry of Gold Ore Low Sulfidation -Epithermal at Lamuntet, Brang Rea, West Sumbawa District, West Nusa Tenggara Province

There are two Artisanal Small scale Gold Mining (ASGM) location in Lamuntet, Brang Rea Subdistrict, West Nusa Tenggara Regency, namely Nglampar and Song location. Nglampar and Song location are included in the low sulfidation epithermal gold deposit system. The research purposes to analyze mineralogy and geochemistry of gold vein deposits and determine system of low sulfidation gold ore in Nglampar, Lamuntet Village. The methods used to determine the mineralogy of gold vein deposits are petrography, mineragraphy and X-ray diffractometer (XRD) analysis, while geochemical analysis using Scanning Electron Microscope (SEM) with Energy Dispersive X-Ray Spectroscopy (EDS), Fire Assay (FA) and Atomic Absorption Spectrophotometry (AAS). The results showed that the minerals contained were quartz (Qz), sericite (Ser), Chalcedon (Chc), chlorite (Chl), pyrite (Py), sphalerite (Sph), galena (Gn) , gold (Au), chalcopyrite (Cp), argentite (Ag), arsenopyrite (Apy), Azurit (Az), Malakit (Mal) and bornite (Bn). Abundant mineral availability such as sphalerite, galena, chalcopyrite and arsenopyrite are characterized by high levels of Zn, Pb, Cu and As the metal in vein deposits. This can be seen on the chemical content of ore in gold vein deposits ie Au 0.1 ppm -27.8 ppm, Ag 3 ppm-185 ppm, Pb 101 ppm - 35,800 ppm, Zn 73 ppm-60,200 ppm, Cu 26 ppm - 1,740 ppm, and As 150 ppm - 6,530 ppm. Based on the results of SEM-EDS analysis shows that the type of gold mineral is the electrum because of the content of Ag> 20%.  Based on those characteristics of the mineralogy and geochemistry in this study showed that low sulfidation gold ore in this area is categorized as polymetallic gold-silver system.&nbsp

Kinetics on Biomass Conversion of Terminalia Catappa L. Shell through Isothermal Pyrolysis

Lignocellulose decomposition in the pyrolitic process are affected by several factors, mainly temperature and reaction time. Conducting isothermal pyrolisis on Terminalia Catappa L., this study aims to determine the reaction mechanism and to justify the kinetics. Powder sample of Terminalia Catappa L. was prepared by grounding it to certain particle size. The temperature was varied and kept constant at 350оC, 400оC, 450оC, 500оC, and 550оC with time interval of 30, 60, and 90 minutes. For kinetics study, data were obtained by measuring the liquid and gas products every 5 minutes. While the solid yield can be calculated using MATLAB simulation program based on the mass balance conception. The results showed that the increase of temperature accelerates the pyrolitic reaction rate increasing the liquid and gas products yield but decreasing the solid product yield. Furthermore the kinetics model of Terminalia Catappa L. pyrolysis was verified to understand the reaction mechanism. It was found that the pyrolysis reaction of Terminalia Catappa L. seed shells refers to the secondary decomposition reaction with the reaction kinetics parameter value of char for 488 min-1 for the exponential factor. , and  the reaction kinetics parameter value of Tar 0.38 min-1 for the exponential factor. The primer and secondary decomposition reaction with the reaction kinetics parameter value of tar 71 min-1 for the exponential factor, 0.43 min-1 for the exponential factor, respectively

Kajian techno-economy produk etilen dari etanol berbasis pertumbuhan dan prakiraan pasar di Indonesia

Penelitian ini untuk melakukan analisis keekonomian pendirian pabrik etilen (turunan metanol) sehingga dapat memberikan gambaran kepada calon investor baik untuk pendirian pabrik atau peningkatan kapasitas produksi pabrik etilen existing. Analisis rantai pasok ditinjau berdasarkan produksi, konsumsi, ekspor, dan impor etilen dalam kurun waktu 2015-2021, kemudian dilakukan prediksi perkembangan pasar etilen dengan model statistik regresi linier sederhana, dengan parameter Compound Annual Growth Rate (CAGR). Analisis pasar menunjukkan selama kurun waktu 2022-2035, diprediksi volum perdagangan etilen akan defisit rata-rata 712.584 ton per tahun (volum ekspor rata-rata sebesar 108.373 ton per tahun dan volum impor rata-rata sebesar 820.957 per tahun), dan neraca perdagangan akan mengalami defisit sebesar rata-rata USD683,63 juta atau Rp10,22 triliun per tahun dengan kurs Rp 15.000,00/USD. Terdapat potensi pasar etilen rata-rata sebesar 820.957 ton per tahun untuk memenuhi kebutuhan impor, sehingga diusulkan pendirian pabrik etilen dengan kapasitas 820.000 ton per tahun. Berdasarkan perhitungan keekonomian pabrik, diperlukan CAPEX sebesar Rp 3.555.718.718.781.508, OPEX sebesar Rp 3.256.810.716.342, yang dapat memberikan keuntungan sebesar Rp 2.057.236.466.859 setiap tahun. Lebih lanjut, hasil analisis keekonomian menunjukkan nilai ROIa sebesar 65%, POTa sebesar 1,4 tahun, dan DCFRR sebesar 42,96%. Analisis pasar menunjukkan etilen memiliki prospek signifikan sehingga pemanfaatan potensi pasar oleh investor dalam maupun luar negeri dapat memberikan benefit baik dari segi return maupun mengurangi beban devisa negara. Lebih lanjut pendirian pabrik untuk memenuhi potensi pasar tersebut menarik dari segi parameter ekonomi sehingga dapat menjadi pertimbangan lebih lanjut apabila PT. Chandra Asri Petrochemical berminat untuk meningkatkan kapasitas produksi

Simulation of Cement Mill to Predict and Mitigate the Over-Heat Phenomenon: an Approach to Optimize the Energy Consumption in Cement Industry

being one of the most energy-intensive industries, cement industry requires to evaluate the energy efficiency of their operating units, one of them is cement mill. Functioning as a mixing unit of several materials, i.e., clinker, limestone, gypsum, and trass with their initial heat and propensity of heat generation during milling, over-heat in the cement mill occurs frequently. It should be avoided in order to establish efficiency. Therefore, a mathematical model was generated in this study to predict and to mitigate this overheat phenomenon. This cement mill mathematical model has been generated using mass and energy balances. The output of the model is temperature profile versus residence time with targeted water content of the product that the optimum residence time can be calculated. Based on the temperature profile with a targeted water content of the product, it can be concluded that the optimum operating condition of the cement mill lies in the range of 5 to 30 seconds of materials residence time in the cement mil