Alkaline solidification of gold mine tailings for production of lightweight masonry blocks

Abstract: South Africa is the world’s largest gold resource. This is due to the substantial amount of gold that exists in the Witwatersrand Basin. The processing of gold leads to the production of gold mine tailings. Gold mine tailings are generated from mineral processing of gold ore through which gold is separated. Mine tailings are generally waste materials and are normally disposed of in slurry form in storages constructed on huge areas of land, these storage facilities are called tailings dams. This study was conducted to strengthen and stabilize gold mine tailings by alkaline activation to produce masonry blocks that can be used for building and construction as per minimum requirements for ASTM C34-13, C129-14a and South African standard (SANS227: 2007). The effect of variation of Solid to liquid (S/L) ratio, NaOH concentration and temperature on the UCS was investigated. This was achieved by treating the gold mine tailings with NaOH solution. The feasibility of using gold mine tailings to produce lightweight masonry blocks was studied by conducting unconfined Unconfined Compressive Strength (UCS) tests, SEM imaging, and XRF and XRF analysis. The alkaline activation of Gold Mine Tailings (AU MT) at a S/L ratio of 14.31% and 9 M concentration had higher UCS than those produced at 3 M and 6 M. Curing temperature is an important factor affecting alkaline activation and the UCS of masonry block. The UCS increases with the curing temperature up to a certain level and then decreases with the curing temperature. For the AU MT herein, the optimum curing temperature was found to be 80 °C with bulk density of 1578 kg/m3. The AU MT based masonry block meet ASTM standards they can be used for building and construction purposes such as the building of structural clay load bearing wall tiles of all C34-03 ASTM designation grades and building blocks of ASTM designation C6210, type NW (negligible weathering) with the minimum UCS of 10.3 MPa

Lecturers' perspectives of pedagogical training initiates at a University of Technology in KwaZulu-Natal, South Africa

Professional development of academics in higher education in South Africa has been offered in an uncoordinated and unsustainable manner. Ever since the new dispensation, concerted efforts have been implemented to address this problem. As part of the solution, universities through their academic development units, have introduced various pedagogical training workshops to equip academics with teaching skills. This study investigates perceptions of academics pertaining to this training. A multi-method cross-sectional research design was adopted to understand lecturers’ perspectives regarding professional development. A total of 45 participants were purposefully selected to participate in the study from the academics who attended the pedagogical training. A questionnaire (closed and open-ended) was used to collect data. Quantitative data were analysed using the Statistical Package for the Social Sciences (SPSS), while thematic analysis was applied to analyse qualitative data. Results of the study revealed that the training was well-received and academic staff members felt motivated and confident to implement various instructional strategies acquired from the training. Participants expressed a need and willingness to learn and develop new instructional techniques and acquired a positive outlook on teaching and learning following the professional development training. The study recommends redesigning the pedagogical training to include ongoing support activities and customisation in addition to the generic version

Skeletal morphologic features of Anterior Open Bite Malocclusionamongst black patients visiting the Medunsa oral health centre

INTRODUCTION: Anterior open bite (AOB) malocclusion presents as lack of vertical overlap of anterior teeth. It is viewed to be unaesthetic and may affect speech and mastication It develops due to the interaction of hereditary and environmental etiological factors and these usually affect the vertical growth of the face. This study describes the vertical changes of South African black people presenting with AOB. AIMS AND OBJECTIVES: The aim was to determine skeletal morphological features of patients with AOB malocclusion. DESIGN: The design was a retrospective, cross-sectional study. MATERIALS: Archived pre-treatment lateral cephalographs of 181 patients who consulted between 2007 and 2014 were divided into four groups: control group of 62 patients with skeletal Class I pattern without AOB; test groups of patients with AOB (119) divided into 35 Class I, 43 Class II, and 41 Class III malocclusions. Records of each group were divided according to gender. Descriptive statistics, the Pearson correlation coefficient, t-test and. Wilcoxon test were employed to analyze the data, and p values of <0.05 were considered statistically significant. RESULTS AND CONCLUSIONS: Patients with AOB had a larger vertical facial pattern in all classes of malocclusion. Males presented with larger Sn-GoGn angles than females. The PFH/AFH ratio was lower across all classes of malocclusion compared to the control group

Practices in scholarly publishing : making sense of rejection

Abstract: In South Africa, criticisms of peer review often hinge on allegations of racism, anti-African attitudes, and viewpoint discrimination. This article discusses the issue of peer-review, and examines these allegations in terms of claims of Western conceptual gatekeeping. Cautions are offered on allegations of exceptionalism, as are some strategies on dealing with the process of peer review

Automated Classification of Airborne Laser Scanning Point Clouds

Making sense of the physical world has always been at the core of mapping. Up until recently, this has always dependent on using the human eye. Using airborne lasers, it has become possible to quickly "see" more of the world in many more dimensions. The resulting enormous point clouds serve as data sources for applications far beyond the original mapping purposes ranging from flooding protection and forestry to threat mitigation. In order to process these large quantities of data, novel methods are required. In this contribution, we develop models to automatically classify ground cover and soil types. Using the logic of machine learning, we critically review the advantages of supervised and unsupervised methods. Focusing on decision trees, we improve accuracy by including beam vector components and using a genetic algorithm. We find that our approach delivers consistently high quality classifications, surpassing classical methods

Cement and fly ash stabilised gold mine tailings for the development of new material

Abstract: More than 500 gold tailings and a number of fly ash dumps exist in South Africa. These waste material contribute significantly to air, water and soil pollution. In this study gold mine tailings and fly ash which are readily available and result into environmental pollution were used to produce new building/construction material. The tailings were stabilised with cement and fly ash. Up to 20% of cement was incorporated in the mix design. The incorporation of 20% cement resulted into significant unconfined compressive strength (UCS) improvement of 3.89 MPa and 4.36 MPa at 56 and 90 days of curing, respectively. The strength development in fly ash and cement modified tailings was influenced by the pozzolanic and hydration reaction. The strength developed is applicable for the materials to be used for load bearing. The unconfined compressive strength of the developed specimen the composites met the minimum SANS 2001-CM1:2007 for hallow bricks to be used as masonry bricks

Enhancement of the geotechnical and geochemical properties of 1 gold tailings by BOF slag and class F fly ash

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Guideline for sustainable wetland management and utilization: key cornerstones

This research report is based on the project on Wetlands, Livelihoods and Environmental Security and the Sustainable management of Inland Wetlands in Southern Africa: a livelihoods and ecosystem approach projects. The projects were supported by the CGIAR´s Challenge Programme on Water and Food (CPWF) and the Global Environment facility with matching funds from International Water Management Institute (IWMI), Eduardo Mondlane (UEM), FSP and the University of Zimbabwe (UZ) The authors acknowledge input by the entire project team. The support of IWMI, UEM, and the UZ, and Institute de Recherche pour le Development (IRD) during project implementation is gratefully acknowledged. The authors thank the input of CPWF Theme 3 leadership and the Limpopo Basin Coordinator during project implementation