Engineering Headway Vol. 20

Abstract: Crude palm oil (CPO) is one of the potential feedstocks for biodiesel production. While CPO has potential as a sustainable biodiesel feedstock, there are still a number of challenges that need to be overcome. One of them is the presence of interfering compounds in CPO, such as free fatty acids and non-triglyceride compounds. This research aims to analyse the density, viscosity, calorific value and identify the types of chemical compounds in CPO for biodiesel production consisting of 100% biodiesel (Fatty Acid Methyl Ester or FAME) without mixture with conventional diesel fuel (fossil diesel). This study used several test samples, including Crude Palm Oil (CPO) and B100 that had been ozonised for 30 minutes (BO30), 60 minutes (BO60), 120 minutes (BO120) and 180 minutes (B0180), then characterised using a bomb calorimeter to identify Higher Heating Value (HHV), density (ASTM D1298), viscosity (ASTM D445), Fourier Transform InfraRed Method (FT-IR), and Gas Chromatograph-Mass Spectrometer (GC-MS). The results showed that the BO180 fuel mixture had the highest calorific value of 33.40 MJ/kg, the smallest kinematic viscosity of 21.42 cSt, and the density at 40°C showed no change among the biodiesel samples, which was around 0.85 gr/ml. The content of BO180 chemical compounds analysed using GC-MS), there are octadecenoic acid compounds of 44.15%, hexadecenoic acid of 32.92%, and other compounds less than 1%.

Abstract: The presence of dunite boulders beneath the limonite zone is a lateritization zonation anomaly because it produces high grades of nickel. This research aims to identify boulders as a source of lateritization and evaluate lateritization zonation concerning major elements. Using XRF laboratory data from systematic zonation sampling the entire data is analyzed by matrix scatter and Pearson Correlation statistics. The results of the research show that the lateritization pattern of boulder dunite has the characteristic that the nickel concentration is slightly influenced by topographic factors and groundwater drainage. However, it is more influenced by rock fractures. As a result, nickel grades are certain to increase suddenly and produce high nickel grades. The interference of silica and magnesium is considered small, thus allowing the presence of rare earth elements.

Abstract: Coal mine slope stability is an important aspect of mining activities. The research site is located at Pit PQRT in Berau Regency, East Kalimantan. The research area is a freshwater peat swamp area located on a delta plain with tidal influence. The swamp material is located on the low wall side of the mine. Slope stability in the study area, which is composed of soft swamp material needs special attention because it is a major problem in the design of mining slope geometry. However, the availability of mine slope infrastructure in the form of active roads and sediment ponds also needs attention. Slope stability analyses were conducted using the Bishop Simplified and Janbu Simplified limit equilibrium methods. The slope geometry design at elevation-16 to-13 is 3 meters bench height, 20 degrees slope angle, and 15 m bench width. The elevations are-10 to-1, the bench height is 3 meters, bench width is 20 m. At elevation +2 the bench width is 35 m, and at elevation +5 the bench width is 40 m. The overall slope analysis results using the Bishop Simplified method the safety factor is 1.37 while in the Janbu Simplified method, the safety factor is 1.31. In the calculation of the safety factor considering active roads and sediment ponds the safety factor is 1.57.

Abstract: An atmospheric leaching of a limonite ore from Soroako, Sulawesi, Indonesia, has been performed using hydrochloric acid (HCl) and nitric acid HNO₃ solutions. The study's objectives are to determine the effect of pre-roasting the laterite ore sample on the dissolution behavior and to compare the leaching efficiency of metals (Ni, Co, and Fe) from limonite under HCl and HNO₃ lixiviants. The sample was characterized using optical microscopic, X-ray diffraction (XRD), X-ray fluorescence (XRF), and atomic absorption spectrometry (AAS) methods. Heating the ore at 300 °C has transformed goethite into proto-hematite, resulting in the highest Ni and Fe leaching efficiency. However, Co leaching efficiency attains the maximum at a roasting temperature of 750 °C. It is shown that HCl leaching for Ni and Fe is more efficient than HNO₃. The higher leaching rate of Fe under HCl indicates low selectivity of iron relative to nickel.

Abstract: Indonesia ranks second in the world for nickel resources. The location of laterite resources in Indonesia is in the Eastern Region of Indonesia (KTI), especially in Sulawesi and small islands in the North Maluku and Southeast Sulawesi islands so that many mining companies are engaged in the nickel mining industry. Nickel mining activities require large capital and investment and have high risks. This study aims to analyze the economics of one pit in a nickel mining company in Sulawesi in terms of investment feasibility plan using the discounted cash flow method. The resulting investment criteria are net present value (NPV) of $114,448,962.84, internal rate of return (IRR) of 153%, and payback period (PBP) of 1 year and 3 months which indicates that mining activities are feasible.

Abstract: Emergency conditions are situations that can happen to anyone, anywhere and anytime. An emergency is a life-threatening condition in an emergency, such as cardiac arrest, resulting in a sudden loss of blood flow due to failure of the heart to pump effectively, which can lead to death. The key factor in increasing the number of survivors is the quality of cardiopulmonary resuscitation (CPR). Quality of CPR is indicated by a chest compression frequency of 100 - 120 beats/minute and a depth of 5mm, with a minimum lag time. Cardiac pump resuscitation (CPR), which provides circulatory and respiratory support, is a common therapy applied to almost all cardiac or respiratory arrest cases. Compression and ventilation are effective measures of cardiac pump resuscitation (CPR). This research refers to the system, design, and manufacture, including the chassis and assembling of the control system manually and automatically. Controlling the equipment using Arduino Uno, motor driver, and dimmer to manually and automatically adjust or control the compression speed manually and automatically. The results showed that the greater the applied voltage, the greater the compression. The increase occurred from 109, 112, and up to 119 compressions per minute manually, while automatic increases occurred from 110, 113, and up to 119 compressions per minute and with a compression depth of 40 mm

Abstract: Steam Power Plant (PLTU) is a type of thermal power plants widely used nowadays due to its high in efficiency. PLTU Moramo is an Independent Power Producer (IPP) that supplies electricity to PT PLN and has two generating units which produce 2 x 50 MW of electricity. The main goal of this research is to investigate effect of the steam power plant’s electricity loads on efficiency of the Subcritical Pulverized Coal (PC) Boiler and to determine values of the boiler’s efficiency based on the three vary loading capacity which are 30 MW net, 40 MW net, and 50 MW net respectively. Method applying to calculate the boiler efficiency in this research is an indirect method or heat loss method of calculation based on the heat loss value for each parameter, then the boiler efficiency is determined. Results obtained in this research showed that by using indirect method or the heat loss method, thermal efficiency of the boiler decreases as the boiler’s loading capacity is increased. Based on this research, thermal efficiency of the boiler is 81.15 % for the loading capacity of 30 MW net and decreasing to 80.20 % and 79.20 % for 40 MW net load and 50 MW net load respectively

Abstract: In the era of the manufacturing industry which is developing very rapidly, a manufactured product must have high product quality, especially machining products such as turning products. AISI 1045 steel is a type of low carbon steel with a carbon content of (0.43% – 0.50%) which is often used on the market because it has many advantages and the price is quite affordable. Vibrations that occur in the turning process cause undesirable effects; such as discomfort, inaccuracies in measurements and non-optimal turning results. Roughness really depends on the type of tool and tool geometry. In this study, carbide chisels were used with cutting variations, namely: variations in cutting angle (Kr) selected 80⁰, 85⁰ and 90⁰, spindle rotation (n) 200 rpm, feeding (f) 0.3 mm/put , feeding depth (a) 1 mm and load mass (m) 150 grams, 300 grams and 450 grams. When turning, the amplitude value is measured using the Vibxpert toolII and After turning each set of machining variables, the roughness is measured using a machine Laser 3D Measuring Laser Microscope OLS4100. The measurement data obtained is graphed with the relationship of Load Mass & cut angle with roughness and amplitude value. The purpose of this research is to find out the effect of passive mass reduction and the cutting angle of AISI 1045 Steel on the roughness and amplitude values. From the results of the analysis, it was found that the most optimal load mass is 450 grams and the cutting angle (Kr) the most optimal is 80° with a roughness value of 4.07 µm and an amplitude value of 0.15 mm/s².

Abstract: The Savonius-type rotor is a phenomenal rotor model applied to vertical-axis type hydrokinetic turbines, which use is quite popular even though its performance is considered lower than other rotor types. One of the advantages of the Savonius-type rotor compared to other types of vertical axis hydrokinetic rotors is that it is more effective in extracting hydrokinetic energy from low velocity water flows. This research aims to analyze the performance of the Savonius rotor by modifying the blade model by providing grooves on the concave side. Tests were carried out on a two-blade Savonius rotor without grooves and with blades using 5, 6, 7 and 8 grooves with a width of 15 mm in the direction perpendicular to the shaft with varying input loads and flow rates for several constant rotation levels. The research results indicate that the groove-less blades yielded a maximum tip speed ratio (TSR) of 1.32 and a maximum efficiency (ɳ) of 29.58%. In contrast, grooved blades produced a maximum TSR of 1.40 and a maximum efficiency of 33.71%, indicating an increase in TSR of 0.08 and an efficiency increase of 4.17 %, with the highest increase occurring on eight-groove blades.