Economic Viability of the Use of Local Pseudo-Oils for Drilling Fluid Formulation

The initial cost of formulating Synthetic Base Muds (SBM) compared to conventional Oil Base Muds (OBM) may be doubled but after considering the cost of containment, hauling, and disposal of OBM after use, the cost of using SBM becomes relatively cheaper. The formulation and disposal options (onshore and offshore) and the cost benefit of using seven local antioxidated pseudo-oils (vegetable esters) SBM compared to commercial OBM at an average offshore and onshore temperature operations were simulated in this work using API standard performance benchmarks. The average cost percent of savings on the use of the seven local vegetable oils over the use of commercial synthetic base fluid offshore and onshore were 48.32% and 56.30% respectively. Thus the use of local ester oils for drilling fluids formulation are more economical compared to currently imported oil based drilling fluids. The cultivation and production of these local pseudo-oils are on the increase guaranteeing its adoption and application to be very sustainable.Keywords: Antioxidants, Disposals, Economics, Esters, Formulation

The Influence of Integrated Gravity Circuit on the Efficiency of Gold Extraction at a Carbon-in-Leach Plant

In gold ores, the precious metal particles may occur as nuggets (> 0.5 mm) and down to sub-microscopic particles. Coarse particles are generally recovered by gravity concentration before leaching the bulk material with sodium cyanide to enhance leaching efficiency. A mine in West Africa operates a carbon-in-leach (CIL) plant where a gravity circuit has recently been installed. The purpose of this study was to investigate the effect of the gravity-integrated circuit on the overall efficiency of metallurgical operations in the CIL plant. In this investigation, a quantitative research approach was selected to determine the variables in analysing the influence of the integrated gravity circuit on the efficiency of gold extraction. The general plant efficiencies before and after the installation of the Gravity Recoverable Gold (GRG) circuit were investigated, with a focus on the milling circuit, CIL circuit, and reagent consumption in the various circuits. A model was constructed using multiple linear regression analysis, and the relationship between the variables was determined. From the results, the mill's throughput increased from 13.5 million tonnes per year to 13.9 million tonnes per year after the installation of the GRG circuit. In models 1 and 2, all coefficient p-values were less than the 5% significance level chosen for the study. Cost-benefit analysis of reagent use before and after gravity installation showed that the plant consumption of reagents decreased from 43 264 – 36 481 tonnes, 13 144 – 10 141 tonnes, 1 779 – 1 538 tonnes, 3 208 – 1 551 tonnes, 9 274 – 8 045 tonnes for lime, sodium cyanide, activated carbon, hydrochloric acid and caustic soda respectively. Again, the GRG circuit dramatically reduced the gold loadings onto activated carbon with an overall reduction in tailing grade and increased the gold recovery rate and purity by 1% and 2%, respectively. Overall, the mine's annual ore processing capacity increased by 2.34 %. Therefore, installing additional Knelson concentrators (gravity units) can be key to addressing the excess gravity-recoverable gold suspected to exist in the circuit with continuous checks and balances performed

Africa Rising in an Emerging World: An International Marketing Perspective

Purpose: The primary goal of this introductory article is to highlight important contemporary themes in international marketing strategy from the perspective of Sub-Saharan African firms. Design/methodology/approach: The approach adopted is a review and synopsis of the existing body of research on international marketing research in Sub-Saharan African, and a discussion of the manuscripts included in the special issue. Findings: International marketing in Sub-Sahara Africa is growing steadily, driven largely by rapid changes in socio-economic and demographic characteristics of consumers in this market. The growing appetite of multinational enterprises to explore new growth opportunities on this continent and the increasing intra-Africa cross-border transactions is driving unique approaches to international marketing that are predicated on using non-traditional means to produce, communicate and distribute products and services. Research limitations/implications: While the international marketing opportunities and challenges discussed in this article are not exhaustive, the paper highlights important research themes that need consideration regarding international marketing research in Sub-Saharan Africa. Originality/value: This introductory article emphasizes the unique international business landscape in Sub-Saharan Africa and discusses its international marketing strategy implications. The article further draws attention to a number of unanswered research questions that require additional research, and thus bring Sub-Saharan Africa to international marketing scholarly enquiry

Detoxification of Cyanide Wastewater by Cyanotrophic Organisms: the case of Phanerochaete chrysosporium

Abstract Cyanide, a carbon-nitrogen radical, is a major building block in many industries including pharmaceuticals, petrochemical and gold processing. In the gold extraction industry, cyanide has been the universal lixiviant for over a century due to better understood process chemistry, among others. Industries that discharge cyanide-laden effluents are mandated to keep concentrations below 0.2 mg/L to prevent death by cyanide-intoxification, which occurs when cyanide binds to key iron-containing enzymes and prevent them from supplying oxygen-containing blood to the tissues. Techniques used to attenuate cyanide in wastewater can broadly be grouped into chemical, physical and biological methods.  In recent times, attention has been placed on biotechnological methods, which make use of cyanotrophic microorganisms to clean up cyanide-contaminated environments. This paper reports on studies set out to assess the ability of Phanerochaete chrysosporium to degrade cyanide under different conditions including changes in cyanide concentration, culture mass, time, closed system and open system. At the end of 24-hour contact in an open agitated system with initial pH of 11.5, a control experiment using 100 mg/L cyanide revealed a natural attenuation of 15% with pH decreasing to 9.88, while the best myco-detoxification of 85% was achieved by contacting 100 mg/L cyanide with 0.5 g culture mass, translating into degradation capacity of 17.2 mg/g (milligram of cyanide per gram of culture) with pH reducing to 8.4 in 24 hours. The degradation could be based on a number of mechanisms including hydrolysis to HCN, oxidation to cyanyl radical and cyanate due to natural attenuation through atmospheric contact, and secretion of organic acid, oxidative enzymes, and hydrogen peroxide by the fungus.   Keywords: Cyanotrophic Organism, Myco-Detoxification, Cyanide-Laden Effluents, p

Evaluation of Potential for Expansion of Irrigated Rice Production in the Extended Lake Victoria Basin

The Lake Victoria Basin has the potential to meet rice demand in East and Central Africa. Current irrigation production and yield rates are low and attention is turning to expansion of irrigated rice production. Some studies have demonstrated sustainability of increased production of irrigated rice. This study analyzed the potential for increased production of irrigated rice in the extended Lake Victoria Basin. It assessed the existing scenario and evaluated expansion under individual and combined scenarios of increased irrigation and inputs in rice production areas using land use and other data from the Global Agro-Ecological Zones (GAEZ) system. The analysis was done in Python environment for all rain-fed, rice producing areas with sufficiently suitable land and for the optimal growing season. Yield differences for the different scenarios were superimposed on shape files of the basin. These were used to generate choropleth maps and bar charts to visualize the variation in increased yield for individual sub-basins as well as the overall increase for the basin. The results showed that there is potential for up-scaling rice production given the inclusion of irrigation and inputs. Irrigation will be of more benefit in a few of the sub-basins, particularly in the North East of the basin. It was recommended that a general improvement in agricultural management practices will significantly enhance the yields and close the yield gap

Oxidation Behaviour and Bio-oxidation of Gold-bearing Sulphide Ores: Oxygen Capabilities and Challenges

The paper presents an overview of bio-oxidation of sulphidic refractory gold ores prior to gold cyanidation. This review discusses several factors, more importantly, oxygen requirements and oxygen limitations in biological oxidation of various sulphide minerals associated with gold ores. The availability of sufficient oxygen in bio-oxidation systems can speed up and enhance the oxidation of sulphide minerals, allowing the gold to be liberated for further extraction. However, oxygen supply and its low solubility in water have been the major limiting factors in bio-oxidation processes. More importantly, oxygen limitations are found to affect the rate of sulphide oxidation and the volume of materials that can be treated for gold leaching. First, the paper discusses the influence of dissolved oxygen on the oxidation behaviour of various sulphide minerals found in refractory gold ores or concentrates. Further discussed are the limiting factors in relation to dissolved oxygen during bio-oxidation of refractory gold ores. This review demonstrates that oxygen availability is a major challenge and therefore, oxygen enhancement techniques or strategies are vitally needed. As well, the review serves to inspire new research into efficient strategies to enhance oxygen availability

Biosorption of Mercury by Selected Plants – a Preliminary Study

Traditionally, mercury (Hg) is considered among the most toxic elements with several major health issues and serious environmental challenges. With the frequent release of Hg from artisanal and small-scale gold mining (ASGM) operations, aquatic plants or staple crops in environments polluted with mercury may accumulate significant amounts of mercury. Thus, result in mercury entering the food supply chain posing health challenges to humans. In order to ascertain the bio-sorption characteristics of some staple crops for mercury; beans, millet, corn and groundnut were tested. The plants were contacted with 10 mg/L and 50 mg/L solution of mercury concentration for 7 days followed by subsequent metal analysis of residual solution. The results delineate that, metal uptake ranges of 4.6-9.3 mg/l, 3.2-9.6 mg/l, 4.7-9.3 mg/l and 3.0-7.7 mg/l for beans, corn, groundnut and millet respectively for the 10 ppm Hg solution. In addition, 16.2-42.0 mg/l, 18.2-35.7 mg/l, 17.6-34.2 mg/l and 26.0-30.2 mg/l are the Hg metal uptake ranges for the 50 ppm concentration. This shows that the plants have the capacity to uptake mercury metal to certain degree. This also confirms that beans, corn, millet, and groundnut are potential bio-accumulators of mercury in mercury contaminated sites. Notably, the findings from this study affirm the hypothesis that in situations where the mercury is bioavailable, some food items harvested in such polluted areas may eventually enter the food chain

Toward a construct of liability of origin

In this paper, we advance a novel concept of liability of origin to explicate the mechanisms through which location can be become either a liability or an advantage. Our analysis sheds light on how firms’ ability to compete and gain legitimacy can be derailed or enhanced by their geographical location. We illustrate our theoretical analysis using multiple cases in the airline industry in Africa. Four distinct phases that explicate how liability of origin manifests in firms’ legitimacy quest are indicated. Our work highlights how actions and inactions of rival firms can make the geographical origin of a firm “geographicalness” to shift from being a strategic asset to become a liability. We outline a number of implications for practice and fruitful avenues for future research