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Generally, artisanal and small-scale gold mining (ASGM) in Indonesia uses the amalgamated mercury process. Most of the respondents from ASGM experienced mercury poisoning. An alternative non-mercury gold processing is cyanidation. In this work, an actual practice cyanidation process of local artisanal gold processing in Wonogiri, Indonesia, was studied. The paper presents the practices of local artisanal gold processing using the cyanide process, their weaknesses in the process, and ways to diminish the problem. The paper also highlighted the self-designed in a continuous mode leaching adsorption pilot plant. Preliminary results showed that leaching in the pilot plant leaching-adsorption process produced better gold content than the ASGM process. [ABSTRACT FROM AUTHOR]

A thermal process called torrefaction turns biomass into a substance that resembles coal and has superior fuel properties than the original biomass. Biomass that has been torrefied is more energy dense and hydrophobic, making it better for handling and storing. The objectives of this research are to develop a simulation model of the torrefaction process from Malaysian biomass and perform optimization for mass yield and energy consumption, and to integrate optimal torrefaction process into the existing biomass power plant. The process was simulated using ASPEN Plus. After EFB and other component is defined and properties method is selected depending on the process, the simulation model was developed by using model palette installed inside ASPEN to produce the desired torrefied EFB. For the base model of the simulation, crusher is used for size reduction, two separators and three RStoich model reactors are used for combustion and RYield model reactor for torrefaction. For optimization of mass yield and overall energy consumption, 6 option (simulation model 0 to 5) of design configurations were analysed. Retrofitting study on biomass-based power generation plant with torrefaction process is to improve the existing feedstock. Thus, 5 options (simulation option a to e) were constructed to further reduce the energy consumption of the total plant operation in the biomass power plant. The option was selected by lowest energy consumption, lowest integration cost and lowest annual utilities cost. Generally, the torrefaction technology is an improvement of biomass utilization technology and finally realize the maximum application of biomass energy. [ABSTRACT FROM AUTHOR]

Empty fruit bunches (EFB) are one of the biomass wastes produced from palm oil plantation in Malaysia which are rich in carbon, thus favorable for activated carbon (AC) production. In the present work, AC was produced from EFB via physical activation with carbon dioxide. The influence of carbonization and activation temperature on the quality of activated carbon has been analyzed. The experiment started with pre-treatment and processing of the sample with predetermined particle size of 1 mm and lower. Next, the EFB underwent carbonization process and activation process at different temperature for 1 hour. The experiments were conducted with various carbonization temperatures (400°C, 600°C and 800°C) and activation temperatures (500°C, 650°C and 850°C). The activated carbon was subsequently analyzed using BET analysis and adsorption test with methylene blue. From the analysis, sample 4 at carbonization temperature of 600°C and activation temperature at 850°C shows the highest BET surface area of 602.98 m2/g and highest rate removal at 77.56%. Form this study, it can be concluded that higher carbonization and activation temperature promotes higher surface area of AC, thus increase the performance of AC in adsorption process. [ABSTRACT FROM AUTHOR]

The emission of carbon dioxide (CO2) in the atmosphere largely occurs in the past few years, which then lead to global warming. Therefore, a Carbon Capture and Storage (CCS) system is introduced to reduce the effect. However, in order to put CO2 in storage, it must first be compressed in its liquefied form so that it will be easier to be transported through a pipeline. From the capturing process, it is noticed that the CO2 captured contains a lot of impurities, and with the presence of these impurities; the power needed to compress CO2 will be affected. Thus, this paper aims to study the effect of impurities in CO2 binary mixtures on the compression power requirements using different types of compression systems. The compression technologies include conventional eight-stage centrifugal compressor and two-stage supersonic shockwave compressors. The compression power is calculated numerically based on idealized isentropic compression and isobaric cooling principles. The Peng-Robinson Equation of State (PR EOS) is employed to predict the thermodynamic properties of the CO2 stream. From the study, it is found that the compression work for the supersonic shockwave compressors is higher than conventional multistage compression by 35%. However, this relatively low efficiency of supersonic shockwave compressors can be compensated by utilizing the compression heat in other processes in the plant such as for regeneration of amine solutions or preheating the boiler water. In the case of the effect of the binary mixture on the compression work, among the impurities present, H2/CO2 mixture requires the highest compression work for both of the technologies used. [ABSTRACT FROM AUTHOR]

The accumulation of waste in landfill site is mainly due to increased urbanization and industrialization. The leachate produced beneath the landfills led to critical environmental issue. The objective of this study was to determine the effects of vermicomposting of landfill leachate using earthworms on biofertilizer production. Earthworms were utilized to convert organic matter in leachate into plant-nutrients that enhance the growth of plants and plants productivity. The concentration of nitrate (N), phosphorus (P) and potassium(K) in vermicompost was found to increase while pH and number of earthworms declined at the end of the vermicomposting period. The vermibin containing 90 earthworms (V1) (approximate 52g) in a mixture of 150 ml of leachate and 798 g of soil obtained the highest concentration of NPK compared to those containing 39 (V2) earthworms and 15 (V3) earthworms. This indicates that the concentration of NPK increased with the added amount of earthworms. V1 experienced an increase of 53–fold in N, 194-fold in P and 210–fold in K due to earthworm activity during the vermicomposting, thus improving the number of leaves (32 leaves). The data shows that vermicomposting might be a suitable technology for the decomposition of landfill leachate into nutritive biofertilizer. [ABSTRACT FROM AUTHOR]