Kinetic Modeling and Mechanisms of Manganese Removal from Alkaline Mine Water Using a Pilot Scale Column Reactor

Manganese (Mn) is a major element in various aqueous and soil environments that is sometimes highly concentrated in mine water and other mineral processing wastewater. In this study, we investigated Mn removal from alkaline mine water (pH > 9) with an Mn-coated silica sand packed into a pilot-scale column reactor and examined the specific reaction mechanism using X-ray absorption near-edge structure (XANES) analysis and geochemical kinetic modeling. The kinetic effect of dissolved Mn(II) removal by birnessite (δ-Mn(IV)O2) at pH 6 and 8 was evaluated at different Mn(II)/Mn(IV) molar ratios of 0.1–10. Our results confirmed the positive effect of the presence of δ-MnO2 on the short-term removal (60 min) of dissolved Mn. XANES analysis results revealed that δ-MnO2 was more abundant than Mn(III)OOH in the reactor, which may have accumulated during a long-term reaction (4 months) after the reactor was turned on. A gradual decrease in dissolved Mn(II) concentration with depth was observed in the reactor, and comparison with the kinetic modeling result confirmed that δ-MnO2 interaction was the dominant Mn removal mechanism. Our results show that δ-MnO2 contents could play a significant role in controlling Mn removability from mine water in the reactor.

The effect of milling time on the alumina phase transformation in the AMCs powder metallurgy reinforced by silica-sand-tailings

This study aims to determine the effect of milling time and sintering temperature parameters on the alumina transformation phase in the manufacture of Aluminium Matrix Composites (AMCs) reinforced by 20 % silica sand tailings using powder metallurgy technology. The matrix and fillers use waste to make the composites more efficient, clean the environment, and increase waste utilization. The milling time applied to the Mechanical Alloying (MA) process was 0.5, 6, 24, 48, and 96 hours, with a ball parameter ratio of 15:1 and a rotation of 93 rpm. Furthermore, hot compaction was carried out using a 100 MPa two-way hydraulic compression machine at a temperature of 300 °C for 20 minutes. The temperature variables of the sintering parameter process were 550, 600 to 650 °C, with a holding time of 10 minutes. Characterization of materials carried out included testing particle size, porosity, X-Ray Diffraction (XRD), SEM-Image, and SEM-EDX. The particle measurement of mechanical alloying processed, using Particle Size Analyzer (PSA) instrument and based on XRD data using the Scherrer equation, showed a relatively similar trend, decreasing particle size occurs when milling time was increased 0.5 to 24 hours. However, when the milling time increases to 48 and 96 hours, the particle size tends to increase slightly, due to cold-weld and agglomeration when the Mechanical Alloying is processed. The impact is the occurrence of the matrix and filler particle pairs in the cold-weld state. So, the results of XRD and SEM-EDX characterization showed a second phase transformation to form alumina compounds at a relatively low sintering temperature of 600 °C after the mechanical alloying process was carried out with a milling time on least 24 hours

Life cycle Assessment of Hydrogen Production via Natural Gas Steam Reforming vs. Biomass Gasification

CONTEXT– Energy is widely involved in human activity and corresponding emissions of SOX, NOX and CO2 from energy generation processes affect global climate change. Clean fuels are desired by society because of their reduced greenhouse gas emissions. Hydrogen is once such candidate fuel. Much hydrogen is produced from fossil fuel, with biomass being an alternative process. OBJECTIVE– The project compared the environmental impact of hydrogen production by natural gas steam reforming vs. biomass gasification. METHOD–Environmental impact was calculated from the input and output data from life cycle inventory analysis. The impact assessment was focused on greenhouse gas emission, acidification, and eutrophication. Models of the two processes were developed and analysed in OpenLCA. The agribalyse database was used to connect inventory flow data to environmental impacts. FINDINGS– For all three metrics, biomass gasification had lower impacts than natural gas steam reforming, sometimes by large margins. For biomass gasification the silica sand production contributes most to all three impact categories, whereas for natural gas steam reforming it is the LPG extraction.

Utility Value Criteria in Selection of Species for Sustainable Reclamation of Silica Mining Area

Silica sand mining in Shankargarh, Prayagraj, India area has led to extensive ecological destruction, environmental degradation and erosion of traditional values in the society. Therefore, an integrated organic and socioeconomic approach is urgently required to bioreclaim degraded mine sites.The most common problems linked with degraded land rehabilitation failures are frequently associated with improper selection of plantation species. Subsistence utility preferences of local people are major acclaimed and convincing reasons in the selection of valuable tree species for Bioreclamation. Socioeconomic Survey were carried out in the nearby villages of Silica mining area to study the existing resources of the area, social structure of the community, dependence on forest and species preferred by the local people. Consequently, a Utility Value Index (UVI) framework was conceptualized, designed and subsequently developed to identify species preferred by the local people and highly valued for supporting their livelihood.

De-Powdering Effect of Foundry Sand for Cement Casting

With the development of the powder bed 3D printing process, sand casting can be performed with methods that are more advanced than the traditional ones, thus enabling new research on applied materials. When sand is 3D-printed with cement as a binder, its casting performance is improved and sufficient thermal stability of conventional organic and inorganic binders is ensured. In this study, to ensure high resolution and strength in a physical and simple mixture of cement and sand, the compatibility for casting was confirmed using submicron-level cement with ingredients and sizes similar to commercial sand, which is uniformly controlled at 4 µm, instead of conventional sand. To enable quick 3D printing, calcium aluminate cement, which has quick binding properties, was used for high-temperature casting. The strength up to 6 h after hydration was compared to determine the curing rate of silica, mullite, and alumina sand containing cement components. By investigating the change in strength due to heat treatment and comparing the adhesion drop test results after powder bed formation, the material containing silica sand was determined as the most suitable for powder layer 3D printing for application to the mold.

Kinerja Filter Portabel Tepat Guna dalam Mereduksi Kekeruhan Air Banjir untuk Sanitasi atau MCK

During flood people had difficulties in obtaining clean water for sanitation (toilet). There was plenty of flood water but highly turbid. The water filter required electricity but its power outaged during flood. Filters usually used energy from electricity or gravity. This study evaluated the performance of a new handy-manually operated flood water portable filter. The standard of Permenkes No. 32/2017 was used as a reference. The flood water filter was pressurized by 0.025 kgf/cm2 and 0.051 kgf/cm2 and used local media: gravel, silica sand, anthracite, sponge. The results showed that pressure 0.025 kgf/cm2 was able to reduce turbidity from 220 NTU to 20.17 NTU with efficiency 90.83%. At 0.051 kgf/cm2 the filter was able to reduce turbidity from 220 NTU to 29.67 NTU with efficiency 86.52%. The pressure variation significantly affects the filtrate quality. The filter with pressure 0.025 kgf/cm2 could be applied for optimal filtration and produced 100-150 liters before clogging. This filter still needs to be studied related to physical strength, type and composition of media, portability and volume of water produced. This flood water filter will be an alternative solution for areas that often flood but no electricity or the power outage during flood.