The influence of Ferro-silicon addition on the reduction and sulfurization of co, cu and Ge- bearing smelter slag with carbon and calcium Sulfate

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Effect of basicity and ferro-silicon addition matte formation from ge-copper bearing slag

Abstract: Through addition of basic oxides, the increase of basicity of multicomponent silicate slags leads to breaking a silicate network and enhances the recovery of valuable metals. In this study, an acidic copper slag containing Cu, Co, Ge, Fe and Zn was used to produce matte for base metal recovery. XRF, XRD and SEM-EDS were used for characterization. CaSO4 was used as Sulphur provider and for basicity change. FeSi was added to enhance the diffusion of Ge from the slag. The sample was placed in a graphite crucible with carbon added to favor reduction and limit the reactivity of the crucible. CO was blown to favor reduction for easy matte formation. A tube furnace was used for the experiments and was set at 1400 °C as working temperature. Preliminary results have confirmed the formation of matte with Fe, Cu present in the matte with low Ge content with no zinc present

Preliminary study on the phase relation in the coke-bed zone (basic South African ore)

Abstract: Investigations on coke-bed relations with acidic manganese ores have been reported number of times. The correlation between the mineralogy, property, reactivity of the ore and the products during the production of high carbon ferromanganese have been reported. A theoretical study has proven that the energy consumption of different basic South African manganese ores were very dependent on the chemical composition of the feed. This has a direct impact on the phases that form in the prereduction, reduction and consequently the coke-bed zone. In the present study high grade manganese ore was subjected to the reduction in presence of coke and subsequent phases formed identified. The temperature range investigated was 1400°C, 1450°C, 1470°C and 1485°C. Al2O3 and SiO2 were used as fluxes to adjust the basicity from 1.25 down to 1. The ore and fluxes were mixed and milled together for 15 minutes to obtain a homogeneous feed. A alumina vertical tube furnace was used for the experiments. The head sample and products were characterized using XRF, XRD and SEM/EDS to identify phases that formed in the coke-bed. Preliminary results showed poor immiscibility between metal and slag for all temperatures, but at 1400°C the separation was much better compare to the other temperatures. Results reveal that at 1400°C, in the metallic phase 71.8% and 16.8% of Mn and Fe respectively whereas in the sla

Slag formation in the reduction zone using coke during high carbon ferromanganese production using South African manganese ores

Abstract: It has been observed that during high carbon ferromanganese using South African ores, some practices do not find an easy answer from the theory and vice-versa. It has therefore become important to study under different reducing conditions what paths does the slag go through while forming during reduction in order to better understand its formation while higher manganese oxides are being reduced. The carbon monoxide gas amount and availability in a specific zone albeit its origin is influential and explanatory toward the degree of reduction and the formation of phases. The current investigation focused on the slag formation with the use of coke. The initial basicity of 1.25 was decreased by adding Silica to lower to a value of 1. The flux and the manganese ore were milled together for 15 minutes to homogenise the head sample and ensure same behaviour of the feed throughout. Graphite crucible was used in a alumina tube for experiments. Argon was blown in the furnace from room temperature to 600oC and switched off to allow carbon to start reducing the manganese ore until the set temperature was reached. The sample was kept for two hours at the set temperature, then the furnace was switched off. Argon gas was switched on from 600 oC to room temperature. The temperatures used were 1200 oC and 1350 oC. XRF, XRD and SEMEDS were used for characterization. Phases present in the slag that formed were therefore identified. A comparison was made between the slag quality obtained here and when only carbon monoxide was used for reduction means

Phase relations in the reduction zone in presence of carbon monoxide during high carbon ferromanganese production using South African manganese ores

Abstract: During High Carbon Ferromanganese production as well as other reduction processes, the chemical composition of the feed plays a crucial role on the quality of the products. It is believed that the reduction from high manganese oxides to their lower oxides during HCFeMn production, the transitional phases that form in the prereduction zone and reduction zone are very influential on the coke-bed zone behavior. Data on acidic manganese ores use are available. However, on the basic manganese ores especially the South African ores data remain very challenging. The current study investigates the phases that have formed in the reduction zone before reaching the coke-bed zone using basic South African ores. The basicity has been reduced from 1.25 down to 1 with the addition of silica. Graphite crucible placed in a alumina tube furnace; was used for the experiments. The ore and flux were milled together for 15 minutes to enhance the homogeneity of the feed. Argon was blown in the furnace from room temperature to 600oC and carbon monoxide thereafter until the set temperature was reached. The samples were kept at the set temperature for two hours and the furnace was switched off while carbon monoxide continued to be blown in until 600oC and the switched back to argon up to room temperature. Both argon and carbon monoxide were blown in at 0.4L/min. The temperature varied from 1300 oC to 1350 oC. The characterization of the feed and products have been conducted using XRF, XRD and SEM-EDS. Different phases were identified in the reduction zone and compared to the prereduction zone

Provision of wood charcoal of Lubumbashi households: quantities, alternatives and consequences

peer reviewedL’exploitation artisanale de la forêt miombo et sa régression s’intensifient suite à l’accroissement des besoins énergétiques des centres urbains du Katanga. Nous avons tenté de comprendre les ressorts des filières bois-énergie et avons fait le choix de cibler l’approvisionnement de la ville de Lubumbashi. Les résultats montrent que, bien que l’énergie électrique soit aussi utilisée, la quasi-totalité des ménages font de plus en plus usage de l’énergie des combustibles végétaux, 72 % des familles n’utilisant que l’énergie du bois pour leurs ménages. La quantité totale de charbon de bois entrant mensuellement à Lubumbashi par route en 2008 (mois de juin-juillet) et selon différents modes de transport est de l’ordre de 805,4 tonnes, soit une consommation minimale d’environ 1 sac de 50 kg de charbon de bois par ménage et par an. Ces combustibles, en provenance essentiellement de l’arrière-pays immédiat, empruntent surtout les axes Likasi et Kasenga dans le secteur nord de la ville, contribuant à 53,5 % du total des entrées. Ces résultats permettent de comprendre que, avec les activités minières, la production du charbon de bois est une des causes principales de la fragmentation et dégradation des forêts au Katanga. On espère que l’énergie électrique puisse prendre le relais de l’énergie fournie par les combustibles afin de protéger les forêts dans la région de Lubumbashi.Artisanal exploitation of the miombo forest to cover the increased energy needs of the urban centres of the Katanga Province accelerates its regression. We tried to understand the origin of the wood-based energy consumption and have chosen to target the supply of the city of Lubumbashi. Although fuel based on wood and electric power are the two types of energy used, our results indicate that virtually all households make more use of fuel based on wood; 72% of the families only use this type of energy for their household needs. The total quantity of charcoal entering monthly in Lubumbashi in 2008 (months of June and July) by road and by different modes of transport is estimated at 805.4 tons, which corresponds to a minimum consumption of 1 bag of 50 kg of charcoal per household per year. These wood-based fuels are extracted mainly from the immediate hinterland of Lubumbashi, especially from Likasi and Kasenga situated in the north of the city, contributing to 53.5% of all entries. Our observations suggest that, together with the mining industry, the production of charcoal is a major cause of forest fragmentation and degradation in Katanga. In order to protect the forest ecosystems in the region of Lubumbashi, hope relies on electrical energy

Poliovirus-Neutralizing Antibody Seroprevalence and Vaccine Habits in a Vaccine-Derived Poliovirus Outbreak Region in the Democratic Republic of Congo in 2018: The Impact on the Global Eradication Initiative.

Despite the successes in wild-type polio eradication, poor vaccine coverage in the DRC has led to the occurrence of circulating vaccine-derived poliovirus outbreaks. This cross-sectional population-based survey provides an update to previous poliovirus-neutralizing antibody seroprevalence studies in the DRC and quantifies risk factors for under-immunization and parental knowledge that guide vaccine decision making. Among the 964 children between 6 and 35 months in our survey, 43.8% (95% CI: 40.6-47.0%), 41.1% (38.0-44.2%), and 38.0% (34.9-41.0%) had protective neutralizing titers to polio types 1, 2, and 3, respectively. We found that 60.7% of parents reported knowing about polio, yet 25.6% reported knowing how it spreads. Our data supported the conclusion that polio outreach efforts were successfully connecting with communities-79.4% of participants had someone come to their home with information about polio, and 88.5% had heard of a polio vaccination campaign. Additionally, the odds of seroreactivity to only serotype 2 were far greater in health zones that had a history of supplementary immunization activities (SIAs) compared to health zones that did not. While SIAs may be reaching under-vaccinated communities as a whole, these results are a continuation of the downward trend of seroprevalence rates in this region