26 research outputs found

    Kinetic reduction of mill scale via hydrogen

    Get PDF
    Mill scale is very attractive industrial waste since it is rich in iron (about = 72 % Fe) and it is suiTab. for direct recycling to the blast furnace via sintering plant. In this paper the characterizations of raw materials were studied by different methods of analyses. The produced briquettes were reduced with different amounts of hydrogen at varying temperatures, and the reduction kinetics was determined. Two models were applied and the energy of activation was calculated

    Removal of Lignin from Pulp Waste Water's Black Liquor via By-Pass Cement Dust

    Get PDF
    The potential use of inexpensive and available by-pass cement dust as an inorganic sorbent for the removal of organic matter (lignin) from black liquor of pulp wastewater by adsorption methodology was investigated using the batch technique. The cement dust is found to remove lignin efficiently from black liquor (the untreated cement dust (70.47%), the thermally treated one at 1000 °C (78.63%), and chemically treated dust (80.62%). The factors affecting the uptake percentage such as time, dose, pH and temperature were investigated to assess the optimum conditions for lignin removal. X-ray patterns were studied to reveal the relationship between the main constituents of each cement dust phase (untreated, thermally and chemically treated) and lignin uptake. By applying Langmuir and Frendlich adsorption isotherms it was found that the adsorption process of lignin from black liquor on by-pass cement dust achieves Frendlich model, which suggests that adsorption is not restricted to one specific layer of sites but involves multi-layers. Also, stripping of lignin by using different strippers (organic, mineral acids, bases and salts) was investigated. The results obtained show that the organic strippers give high stripping percentage for cyclohexane (90.10%) because lignin is a non-polar compound that dissolves in non-polar solvents. In the case of acids, bases and salts the best results were obtained with much diluted solutions (0.001 mol/L). Stripping of lignin from by-pass cement dust is considered as a way of its recycling for different applications

    The Study of the Formation of Sodium Chromate from El-Baramiya High-Silica Chromite Ore Concentrate Using Hydrated Lime

    Get PDF
    The formation of sodium chromate from a mixture of high-silica chromite ore concentrate (48.8%), soda ash and hydrated lime was investigated. Hydrated lime was added to an optimal mixture of Cr2O3:Na2CO3 (mole ratio 1:2.5) (mole ratio of CaO 0-3) and the materials were roasted at 1000°C for 60 min and PO2 0.21 atm. Results revealed a significant decrease in sodium chromate yield (from 42% to 25%) as the (CaO/Cr2O3) mole ratio increased from 0-0.5. Increasing the (CaO/Cr2O3) mole ratio above 1.0, an optimal chromate yield of 70% was achieved at the mole ratio of 2.5. In addition, roasting of optimal mixtures of soda ash, chromite ore and hydrated lime (CaO) (mole ratio 2.5:1:2.5) within the temperature range of (900-1000 °C) provided a maximum chromate yield of 92% at 1000 °C after 2 hours. Overall, the data revealed that while the hydrated lime addition significantly increased the reaction product yield, it also increased the process energy of activation from 112 kJ/mole for the Na2CO3:Cr2O3 (mole ratio 2.5:1) mixture to 171.6 kJ/mole during roasting time (40-100 minutes)

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

    Get PDF
    Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

    Get PDF
    INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

    Kinetics of reaction of roasting of soda ash and ilmenite ore concentrate for formation of sodium titanates

    No full text
    Alkaline metals and hydrogen titanates are of great interest for possible applications. The soda ash and Rosetta ilmenite ore concentrate briquette were investigated. The kinetic of formation of sodium titanate was studied in the temperature range 700°C to 900°C

    Briquetting of Egyptian ilmenite ore with different organic binder and reduced its in hydrogen in temperature range 800-1200°C

    No full text
    Ilmenite ore fine was briquetted with different amounts of molasses or pitch pressed under different pressure was studied in this investigation. The results show at optimum amount of molasses added was 1.5 % and pitch, the pressure was 294.3 M.Pa.. Also the characterizations of raw materials were studied by different methods of analyses such as Xray and screen analyses. The produced briquettes were reduced by different amounts of hydrogen at different temperatures, and the reduction kinetics was determined

    Reducibility study of Rossetta ilmenite ore briquettes and powder with coke breeze at 800-1100°C

    No full text
    Ilmenite ore fine and coke breeze as reduced material were briquetted with different amounts of organic materials such as molasses or pitch were studied in this investigation. The produced briquettes at reasonable condition were reduced in nitrogen atmosphere at temperature range 800 - 1100oC to determine the factors controlling the reduction and to determine the controlling mechanism. Also ilmenite ore fine with coke breeze were reduced at the same temperature range in nitrogen atmosphere without briquetting process, for the sake of comparison
    corecore