Separation of mineral particles in cyclones under the influence of a magnetic field

The separation of mineral particles in a cyclone under the influence of a magnetic field was investigated using an electromagnetic - cyclone arrangement. Feed pulps of dolomite and magnetite were used in the study. Two different cyclone types were investigated: An air-type cyclone arrangement and a conventional cyclone arrangement. Magnetic field strengths of 0 to 3000 gauss (0 - 0.3 Tesla) were used in the study by varying the current through the coils of the electromagnet . The parameters evaluated in the study were the grades and recoveries of the magnetic concentrates produced, the enrichment ratios, the improvement in recoveries achieved and the selectivity indices of the processes. The air-type cyclones operating without the magnetic field (ie as a classifier) produced 50% recoveries of the magnetic fraction of the feed with an enrichment ratio of 1.0. The use of the magnetic field resulted in enrichment ratios as high as 1.8 and up to 25% improvement in recoveries. Using a conventional cyclone (as distinct from the air-type cyclones) resulted in higher concentrate grades and recoveries when operated in the magnetic field. Recoveries of 88% or better were achieved with enrichment ratios as high as 2.35. Cast iron pieces were used to alter the magnetic field distribution around the cyclone yielding recoveries well above 90%. The effects of pressure and percent solids in the feed were also investigated. The recovery and grade were observed to decrease at pressures above 8 psi. The grade increased with increasing percent solids in the feed whilst the recovery decreased at the same time. However, the changes in both pressure and percent solids had to be large for these to be significant. Initially, the study investigated feed pulps containing 10% magnetite. Use of feed pulps containing 20 to 30%. magnetite showed that the higher the percent magnetite in the feed, the less the field intensity required to achieve high recoveries under similar conditions. To increase the concentrate grades, the feed to the cyclone should have particles with sizes just below the d50 of the cyclone. The cyclone operating under the influence of the magnetic field would then recover mostly magnetic materials to the underflow resulting in higher grades --Abstract, pages ii-iii

Inherently diseased and insanitary? the health status of the Gold Coast [Ghana] from the 18th to the late 19th Century

Abstract: Until the end of the 19th century, many European accounts represented the West African Coast as the “White man’s grave.” This representation was borne out by the high morbid- ity and mortality rate of European sojourners who were exposed to the Guinea Coast. This article reviews European accounts of the health status of the Gold Coast during the 18th and 19th centuries. I examine European accounts that characterised the climatic conditions of the Gold Coast as insalubrious and its social and physical environments as unwholesome –condi- tions that were held to be responsible for the high mortality and morbidity rates of Europeans who visited the region. I suggest that while there appeared to be formidable health challenges, especially, in the coastal settlements, the linear narrative that privileges the insanitary condi- tions and unwholesomeness of the region during the period under consideration could be quite misleading. I demonstrate that even though these European accounts, mostly blame the habits of the indigenous population and their social and physical environmental conditions for the unwholesome and insalubrious conditions that caused ill-health and death, the presence of Eu- ropeans on the Gold Coast littoral was itself implicated in the insanitary and depressing health conditions that the region was associated with

Human Capital Availability, Competitive Intensity and Manufacturing Priorities in a Sub-Saharan African Economy

Several studies have been done on the relationships between human resources management (HRM) practices and manufacturing activities. However, most of these studies have been confined to well-developed economies where the focus of HRM practices is mostly on the investment in human capital to facilitate the use of advanced manufacturing technology. In less developed economies, the primary HRM concern is attracting and retaining skilled, knowledgeable and experienced labor. In this study, we examine the relationships between human capital availability, competitive intensity and their interactive effects on manufacturing priorities in a Sub-Saharan African economy — Ghana. We found that competitive intensity is an important determinant of the emphasis firms plan to place on manufacturing priorities (low-cost, quality, flexibility, and delivery). However, human capital availability affects the emphasis firms plan to place on low-cost and delivery. Furthermore, competitive intensity moderates the relationship between human capital availability and the emphasis that firms plan to place on the manufacturing priorities of low-cost and quality

Cross-cultural ties between Ghana and Egypt: the agency of the Egyptian Community in Accra, Ghana

Abstract : Ghana is recognized as an important destination of international migrants. In spite of the socio-economic and political upheavals that the country experienced during the early post-independence era leading to the (forced) return of several of its migrant groups, some have still remained and formed permanent communities and integrated into the Ghanaian society. This paper focuses on the Egyptian diaspora in Ghana. It examines: (1) the type of cross-border and transnational ties that Egyptian migrants in Ghana have established between Ghana and Egypt; (2) how these ties generate cross-cultural relations between Ghana and Egypt; and (3) the extent to which these ties provide a privileged economic and political position to the Egyptian community in Ghana. The work is based on the socio-cultural transnationalism theory. A socio-historical method was adopted for the research and apart from the analysis of historical data, eight key informants were interviewed. The paper shows that due to high-profile intermarriages between Ghanaians and Egyptians, coupled with the ‘Nkrumah factor’, the Egyptian community in Ghana occupies a privileged economic and political position in Ghana

Quando a aula termina: a política econômica das manifestações dos sindicatos de professores na Quarta República de Gana

O presente artigo examina os protestos dos sindicatos de professores sob a Quarta República de Gana. Situando a análise dentro da evolução de sua economia política, eu mostro como as restrições na política econômica de Gana, bem como sua macroeconomia muitas vezes instável, influenciaram e moldaram os atos de protestos, assim como condicionou as respostas dos governos às demandas dos sindicatos dos professores

When the chalks are down: the political economy of teachers’ unions protest actions under Ghana’s Fourth Republic

This article examines teachers’ unions protest actions under Ghana’s Fourth Republic. Situating the analysis within Ghana’s evolving political economy, I show how constraints in Ghana’s political economy as well as its often-faltering macro-economy have influenced and shaped teachers protest actions as well as conditioned governments’ responses to teachers’ unions’ demands

Examining the Success Factors of ICT Projects in Developing Nations: A Case Study of AB Networks

We examine the implementation of information and communication technology (ICT) projects with the context of commonly identified project success factors and present additional factors that are important and worthy of consideration in developing country environments. We also present a framework that ties these factors together and can serve as a guideline in ICT implementations in developing country environments. The proposed framework classifies ICT project success factors into: economic, cultural, and institutional variables

Environmental management practices, operational competitiveness and environmental performance: Empirical evidence from a developing country

Purpose: The purpose of this paper is to examine the relationship between environmental management practices (EMP) and competitive operational performance with respect to reduced cost, improved quality, improved flexibility and improved delivery as well as overall environmental performance, of firms, using data from a developing country. Design/methodology/approach: The study employed a survey approach with responses from 164 informants from different industries and used partial least squares structural equation modeling to examine the relationship between EMP and competitive operational performance and their overall impact on the environmental performance of firms. Findings: The results indicate that EMP by firms have a significant positive effect on firms’ competitive operational performance. Again, firms’ competitive operational performance has a partial positive effect on the overall environmental performance. It was also realized that the EMP initiated by a firm have a direct positive impact on the overall environmental performance of the firm. Research limitations/implications: There is the need for organizations to take steps to plan and implement EMP since it is likely to enhance their competitive operational performance as well as their overall environmental performance. Practical implications: The findings demonstrate the impact of EMP on competitive operational performance as well as on the overall environmental performance of firms. This is important as firms struggle with balancing investments in those practices against the perceived benefits that might be obtained from the practices. Originality/value: The work provides insights and adds to the literature in the area of EMP and firm performance by providing evidence from a developing country environment. This study is among the few that have investigated the impact of EMP on firm performance in developing country environments

Service operations in DMV (division of motor vehicles) offices of the USA - a comparative study

Purpose: Division of motor vehicle (DMV) offices serve a wide swath of Americans in all states and can therefore serve as excellent vehicles to study the quality of public services in the country. However, relatively little attention has been devoted in the academic literature to studying operations in DMV offices, especially as it relates to service quality and productivity. In an attempt to address the same, this paper aims to present the results of a study of DMV offices across the USA through a nationwide survey about vehicle titling and registration services, that received response from 31 of the 50 states and District of Columbia. Design/methodology/approach: The authors use a mixed methods approach – a sequential unequal weight mixed methods approach starting with a quantitative analysis of DMV operational data followed by a qualitative case study approach. The primary data collected for this study were with a nationwide survey of the highest DMV office in each state, conducted through the American Association of Motor Vehicle Administrators. Out of the 50 states, 31 states and District of Columbia responded to the survey. In addition to descriptive statistical analysis performed to glean nationwide findings, Data Envelopment Analysis was used to determine efficiency of operations. Finally, extensive in-person interviews with senior managers of DMV offices in Ohio and Indiana were conducted to get more in-depth information for case studies and identification of best practices. Findings: States exhibit significant variations in labor and capital productivity and based on Data Envelopment Analysis, Texas and Minnesota DMVs are the most efficient in terms of using their labor and capital inputs to maximize the number of transactional services rendered. The authors also find that while operational performance of vehicle titling and registration services is monitored by most DMV offices across the nation, assessment of customer satisfaction received much less attention. Among the states that do well on both are Indiana and Ohio; the case studies presented based on interviews with their officials that also identify best practices. Research limitations/implications: This research was limited to the USA as are its findings. Additionally, it focuses only on vehicle titling and registration at DMV offices because that represents the bulk of services performed by a DMV and the output is standard across all states. Nonetheless, a future study should be extended to other DMV services. Practical implications: Given the finding that assessment of customer satisfaction is not widely practiced in DMV offices, DMV officials should address this by putting appropriate systems in place. Additionally, practitioners and state officials can use the findings of this study to develop best practices for their operations and also determine the most appropriate ways to structure the provision of those services that result in enhanced efficiencies and customer satisfaction. Social implications: DMV services are among the most widely used services offered by the government in the USA and the overall size and scope of services provided by them across the country is immense. Thus, any improvements in productivity and service quality has significant implications in terms of improving public satisfaction with government services. Originality/value: To the best of our knowledge, this represents the first nationwide comparative study of DMV offices in the USA that focuses on service quality and analyzes productivity across the states. Additionally, the case study provided at the end of the paper identifies best practices from two states that have received national recognition for service quality which could be adopted by all DMV offices across the USA. The findings also conform/strengthen numerous hypotheses espoused in existing models and theories from service operations literature by providing evidence in their favor

Using a Social Capital Lens to Identify the Mechanisms of Top Management Commitment: A Case Study of a Technology Project

The implementation of large-scale technology projects is still fraught with failures resulting in tremendous costs to organizations. One of the factors that is widely recognized as critical for achieving technology implementation success (and, for that matter, projects in general) is top management commitment. The actual mechanisms by which top management impacts project success, however, have not received much attention in the project management literature. We use a case study approach here to illustrate how social capital theory provides a useful lens for understanding how top management's actions impact project success and show how project success is strengthened by the enhancement of social capital through top management commitment. We employ causal maps to clarify, illustrate, and visualize the complex interactions between top management commitment and social capital in facilitating project success. This study contributes to the literature and theory on the mechanisms by which top management commitment influences project success by offering propositions for future research