A hydrometallurgical comparison between the caustic and sulphuric acid cracking of steenkampskraal (skk) monazite

The demand for rare earth elements (REEs) is continuously increasing since all high-tech products contain them. The Steenkampskraal (SKK) mine holds the full spectrum of REEs including high-value neodymium (Nd) used in the manufacture of high strength magnets, computers and hard drives. The REEs and thorium (Th) deposit at the SKK mine in the Western Cape has been confirmed to be the highest grade in the world, at an average of 14.4% Total Rare Earth Oxide (TREO) and 2.14% ThO2 respectively, with some locations of the ore body having as high as 45% TREO. These rare earths are hosted in the dominant mineral called monazite. In order to free the REEs from the monazite crystal, it requires “cracking” from the lattice such that it may be soluble in aqueous solution from which it undergoes purification. Two methods of cracking are usually employed in processing of monazite concentrate: caustic and sulphuric acid cracking. The aim of this study was to decide which route was more suitable to the SKK monazite in terms of factors which are usually considered in the setting up of such a processing plant, such as: recovery, capital expenditure (CAPEX); operating expenditure (OPEX); Safety, Health, Radiation, Environment and Quality (SHREQ); and lastly the effects on downstream processes. Experiments were firstly done to develop a flow sheet based on the optimum conditions at which each of these processes were to be carried out. These results would firstly indicate the recovery obtained from each of the processes and additionally impact on our choice of equipment (hence CAPEX), the amount of reagents and power (thus OPEX) and other factors such as SHREQ and effects on downstream processes. It was found that the TREO recovery from the caustic crack was 89% and that of the sulphuric acid crack 90%. However, the sulphuric acid crack required more process stages since the test results implied that the feed to the crack required drying and the product from the crack required conversion from a sulphate into a hydroxide salt. This resulted in a CAPEX of R 13,54M as opposed to the lower value of R 10,03M in the caustic circuit. Also, based on approximately 3 tons of feed to the hydrometallurgical circuit it was found that the sulphuric acid crack required almost twice the amount of OPEX since the power requirement was double that of the caustic cracking method and the reagent requirements were approximately 22% greater. Both of the CAPEX and OPEX mentioned, indicate that the project NPV for the caustic cracking route is ~12.5% higher (~R200M) when treating SKK monazite. The effect on downstream processes was also more negative in the sulphuric acid crack since there was a 5% loss during the double salt precipitation (DSP), 70% of which was Y. Were Y to be recovered at a later stage, its recovery, necessitating further process steps, would have further implications in the plant's CAPEX and OPEX. In addition to this, Th splits at an almost 1:1 ratio after the DSP step and would require an introduction of two new processing legs. The SHREQ aspects that were considered identified minimal impact in the caustic crack route. These, however, were quite extreme in the acid crack route, due to the latter containing high volumes of chemically altered effluents as well as the handling of fine dust particles resulting from its numerous drying stages. In addition to this, the main motivation to favour the caustic cracking route was to avoid the SO3 gas emissions that occurred when using the sulphuric acid cracking route. Hence, it was concluded that the caustic cracking was superior to the sulphuric acid cracking route when treating SKK monazite

Three essays on resource and development economics in Sub-Saharan Africa: evidence from Senegal

The thesis provides empirical evidence of the contribution of basic infrastructure resources to economic development in Senegal. In addition to the introduction and conclusion, three distinct papers make the backbone of the thesis, the first two being impact evaluation studies. The first paper combines difference-and-difference and propensity score matching and uses quantile regressions to examine the welfare effects of rural electrification. The latter is embedded within the first phase of the Emergency Programme for Community Development (PUDC I) implemented by the Senegalese Government. The study uses a panel dataset of 1,115 rural households observed before and after the roll-out of the program. Findings reveal that rural electrification is an agent of household well-being upgrading, irrespective of the electricity source, whether off-grid or on-grid. Electrified households seem to have enjoyed higher agricultural employment and non-food expenditure compared to the observationally similar households that are not connected to electricity. Social benefits manifested through an increase in school enrolment, school attendance, and time spent by children studying at home, with the increase in school attendance being more pronounced for girls than for boys. Furthermore, poor households and those that have access to a marketplace drew the most substantial benefits from access to electricity. The second paper focuses on water infrastructures. It employs a panel dataset of 1,319 Senegalese rural households to empirically document the welfare effect of piped water adoption. Unlike the first paper which considers both economic and social outcomes, the second paper mainly centers on the economic benefits of piped water adoption, which are employment and household expenditure growth. This is because many previous studies have already looked at the social implications associated with access to water resources. The current gap in the literature is mainly observed with the economic impacts of access to water supply infrastructures installed in rural and under-serviced communities within the developing world. A key finding reveals that the adoption of piped water triggered agricultural employment in the PUDC rural areas. Such benefits appear to be greater within households that have access to road infrastructure, alongside access to water resources. The empirical analyses further suggest that non-poor households seem to benefit more from access to water infrastructures than poor households. Finally, when comparing the welfare effect of government-led PUDC water supply with that of community-led initiatives, our findings suggest that the former is much effective than the latter in improving economic outcomes. Using an array of empirical strategies including descriptive statistics, propensity score matching, quantile regressions, and Blinder-Oaxaca counterfactual decomposition, the third paper unravels the nexus between power outages, firm productivity, and gender-based productivity gap. For many developing countries, power outages represent additional costs for firms, given their need to invest in alternative inputs (i.e., generators) to maintain or enhance performance. Moreover, firms managed by females are often claimed to be more severely hit by such outages given the structural and institutional constraints women face in many developing countries. Understanding these interactions is the purpose of this paper. The World Bank's Enterprise Survey (WBES) dataset which comprises 601 Senegalese establishments surveyed in 2015 is used. The results highlight that female-owned firms underperform compared to male-owned firms and that the scale inefficiency stands out as the root of Senegalese firms' low productivity. A key finding is that unexpected and repetitive interruptions of electricity are sources of Senegalese firms' counter-performance and a driver of a broad gender-based productivity gap within firms

Large-scale conditions that result in wet summers over arid Western Southern Africa

The summer (November-April) rainfall patterns across the western region of southern Africa are poorly understood compared to the rest of southern Africa. Although the western interior of southern Africa is considered mostly arid, it is prone to highly variable rainfall and flash floods, impacting vulnerable communities and unique ecosystems. The recent extreme rainfall during 2020/21 and 2021/22 have highlighted the impacts such wet summers can have on vulnerable communities. However, it is not only the rainfall patterns that are poorly understood but also the large-scale drivers that lead to wet conditions across the region. Using a combination of satellite-derived rainfall products and ERA5 reanalysis, this study highlights the complex factors leading to summers with extreme rainfall in this typically arid area over the period 1981-2022. In the analysis, it is highlighted that the wettest conditions typically occur during January to February (JF) and March to April (MA). Departing from traditional approaches, the analysis focuses on ND, JF, and MA to capture variations in circulation changes and rain-bearing system activity. JF stands out with higher rainfall amounts and more rainy days (>10mm), contributing significantly to the overall seasonal rainfall. The seasonal rainfall cycle peaks in February and March, with the rainy season typically spanning from November to April. Spatial distribution emphasizes the region's relative dryness compared to nearby areas, showcasing distinct seasonal fluctuations. Rainfall characteristics, including moderate and heavy rain days, exhibit temporal variability within the seasonal cycle. Furthermore, the significance of late summer rainfall in each bi-monthly period is highlighted. The analysis also highlights considerable interannual variability, with associations between rainfall and climate modes such as the El Niño-Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). However, ENSO stands out as the main driver. There are negative correlations between rainfall and ENSO, suggesting increased (decreased) rainfall during La Niña (El Niño). During the wettest summers, such as 2021 and 2022, there is a notable increase in rainy days compared to the average. This trend aligns with La Niña (El Niño) events, indicating the influence of ENSO on rainfall variability. Positive (negative) standard anomalies during aggregated periods (NDJFMA) correspond to La Niña (El Niño), further emphasizing this relationship. SAM also plays a role, with positive (negative) phases associated with the wettest (driest) years. Cyclonic anomalies over land, particularly in Angola, contribute to widespread rainfall during wet years, while anticyclonic anomalies lead to drier conditions in dry years. These patterns influence subtropical jet streams and storm tracks, impacting seasonal weather and rainfall distribution across southern Africa and neighbouring oceanic regions. Wavenumber 3 or 4 patterns may influence semi-permanent anticyclones in the South Atlantic and South Indian Ocean, affecting regional weather systems. Factors such as moisture flux, divergence patterns, and low level circulation anomalies in the southern Kalahari shape convective rainfall dynamics, with anticyclonic circulation promoting dry conditions and cyclonic circulation facilitating convective activity. Negative omega anomalies in convergence areas indicate favourable conditions for convective rainfall, particularly during La Niña summers. Understanding the strength and intensity of features like the Angola Low or Botswana High could provide further insight into rainfall variability across the region

Long-term neurodevelopmental effects of acute organophosphate poisoning amongst South African children

Background: Pesticide poisoning is a significant cause of morbidity and mortality amongst children in developing countries. In addition to the well described acute effects, organophosphates (OP), can cause long-term neurotoxicity. This study aims to evaluate long-term neurodevelopmental outcomes in a sample of paediatric survivors of acute organophosphate poisoning (OPP) a subject which has, to date not been well described. Objectives: This study determines the performance of South African children surviving acute OPP on a validated set of paediatric neurodevelopmental tests. It compares the performance of acute OPP survivors to two control groups matched for age, sex, and home language. Methods: A case-control study was conducted. A group of OPP survivors (cases) was compared to two control groups: (1) children admitted for paraffin poisoning; and (2) children admitted for conditions other than poisoning. Participants were identified through hospital records. Consenting participants were interviewed and evaluated using six neurodevelopmental tests. 47 cases of acute OPP were recruited and matched to 46 cases of paraffin poisoning and 29 non-poisoned controls. Results: In the comparison of the OPP and control groups, The OPP group performed significantly worse in grooved pegboard, fingertap repetition, total problem score and anxious/depressed clinical syndrome scale. In the comparison of the OPP and paraffin groups, the OPP group performed significantly worse for grooved pegboard, total problem score, social problems clinical syndrome scale, attention deficit/hyperactivity disorder (ADHD) and conduct diagnostic and statistics manual (DSM) scales. Conclusion: This study suggests that OPP in children can result in neurodevelopmental deficits across a range of domains: motor functioning and speed, behavioural problems, attention and emotional wellbeing. These impacts appear to be specific to OP and not just the result of hypoxia associated with poisoning. It highlights the need for more effective poisoning prevention measures, and long-term follow up, neurodevelopmental assessment and support of OP-poisoned children into adolescence

A systematic review on the neurological and psychopathological correlates of pica

Pica, the consumption of non-nutritive substances for longer than 30 days, has had several aetiologies reported. These include micronutrient deficiency, psychological and developmental disorders, and neurological and neurochemical pathologies, with a predominant focus in literature on micronutrient deficiency. Thus, a thorough exploration of the possible neurological (i.e., diagnosed conditions, neuroanatomical regions, neuropsychological profiles, neurodevelopmental disorders, neurotransmitter systems) and psychopathological (i.e., diagnosed conditions, psychological mechanism) correlates is needed. Although a recent review on the topic exists, it has not been reported on systematically. The aim of this systematic review (SR) is to firstly, provide a comprehensive overview of the existing research pertaining to neurological and psychopathological correlates of pica. Secondly, to provide a deeper understanding of pica onset and progression and to inform comorbid diagnosis and treatment of pica. Methodology of the review followed the PRISMA 2020 guidelines. Databases searched included PubMed, Scopus, Science Direct, EbscoHost (Academic Search Premier, CINAHL, Health Source: Nursing/Academic Edition, APA PsycArticles, APA PsycInfo, Medline). Methodological evaluation of studies was conducted using the Joanna Briggs Institute (JBI) Critical Appraisal Tool. An adapted JBI checklist was used for each of the study designs including case reports, case series, case control, and cross-sectional designs. 5468 journal articles were identified, 1102 articles were checked using eligibility criteria, and 15 articles were included in the review. Findings showed that the most prevalent neurological conditions correlated to pica included neurodegenerative diseases (Fronto-temporal dementia; Alzheimer's disease and Multi-infarct Dementia), acquired brain injury and stroke. The neuroanatomical regions most associated with pica included the frontal and temporal cortex as well as limbic system structures. Neuropsychological profiles of individuals with pica were in keeping with the neuroanatomical regions described and included semantic memory deficit, aphasia (Transcortical Sensory and Wernicke's) as well as cognitive difficulties following left temporal (verbal learning, memory, and reasoning) and right frontal (cognitive switching) damage. The most prevalent neurodevelopmental disorders associated with pica were Intellectual Disability and Autism-Spectrum Disorder. Successful treatment of pica mainly included serotonin inhibitors or antagonists, indicating a possible correlation between the dysregulation of serotonin neurotransmitters and pica. In addition, the most prevalent psychopathological correlates of pica included OCD, schizophrenia, and depression, with the relief of anxiety being the most prominently reported reason for engaging in pica behaviour. Furthermore, even though these findings prove to be promising, the studies included were predominantly case report or case series, therefore a recommendation for larger scaled studies is warranted

Performance of host blood transcriptomic signatures for TB diagnosis and monitoring TB treatment

Non-sputum-based diagnostic tests are necessary to enable tuberculosis (TB) diagnosis and monitoring of TB treatment. This work aimed to identify which published blood transcriptomic TB signatures have the best diagnostic performance to distinguish between TB cases and other respiratory diseases (ORDs) in symptomatic adults. These signatures were also evaluated to monitor treatment in young children, to identify signatures that might indicate when treatment could be stopped. Diagnostic performance of signatures was evaluated in adults presenting for care with symptoms associated with TB, who were recruited from primary healthcare clinics in six African countries. To identify signatures that can monitor treatment response, the same set of signatures was evaluated in young children randomised to 4- or 6-month TB treatment in the SHINE trial. Twenty transcriptomic signatures were selected and measured in whole blood using multiplex, microfluidic RT-qPCR. In the adult diagnostic cohort, nine signatures achieved equivalent performance for differentiating patients with ORDs from all TB cases. Factors associated with signature scores included HIV and country. With sensitivity benchmarked at 90%, these nine signatures achieved specificities between 44%-54%. In pooled analyses, none of the signatures met the minimal target product profile criteria for a TB triage test. Country-specific analyses, however, showed that several signatures met the minimal criteria in some countries. In children from the SHINE trial, baseline scores for all signatures were highest in children with confirmed, relative to unconfirmed and unlikely TB. Baseline scores were also higher among children with disease classified as more severe on chest x-ray. Scores declined progressively during TB treatment in the confirmed and unconfirmed TB groups; no changes in scores were observed for most signatures in the unlikely TB group. Scores were higher at the end of treatment in the 4-month than the 6-month treatment arm in the confirmed TB group; no differences were observed between treatment arms in the unconfirmed and unlikely groups. These results suggest that host blood transcriptomic signatures have potential to monitor TB treatment response in children. This work supports further development of transcriptomic signatures as TB triage tests and treatment monitoring tools

Effect of the COVID-19 national lockdown on road traffic accident fatalities involving traumatic brain injury: A retrospective review of Salt River Mortuary cases

Background: Low- and middle-income countries have reported higher traumatic brain injury (TBI) incidence and mortality rates in cases involving road traffic collisions (RTCs). In South Africa, RTCs are commonly reported as contributors to death; however, the current burden of TBI attributable to these deaths is unknown. Additionally, movement restrictions and behavioural changes introduced during the COVID-19 nationwide lockdown have been shown to affect injury patterns in general, but their impact on TBI is undocumented. This study aimed to investigate the epidemiology and patterns of TBI-associated deaths attributable to RTCs before and during the nationwide lockdown in South Africa. Methods: Autopsy reports of TBI-associated deaths due to RTCs, reported to Salt River Mortuary between 1 January 2019 and 31 December 2020, were reviewed. Results: A total of 616 RTCs, from the 7694 total caseload, were included with RTC-related TBIs accounting for 6.51% of the caseload across two years. Males were three times more likely to present with RTC-related TBIs compared to females. Individuals aged 30-39 years were at the highest risk of RTCs, and the median age of those with TBI (34 years) was significantly younger than those without (39 years, p < 0.001). Furthermore, the proportions of the TBI cases were comparable across all road user groups, all were equally likely to sustain TBI in an RTC. Two-thirds (66.18%) of individuals died before hospital admission. Of the 47.16% deceased individuals whose alcohol concentration was detectable, 92.96% had an alcohol level of ≥ 0.05 g/100 mL however we found no significant association between alcohol consumption and sustaining a TBI. Conclusion: These findings indicated that younger individuals are at a higher risk of TBI in RTC-related deaths. Furthermore, injury patterns did not seem to differ between the periods before compared to during the COVID-19 lockdown

COVID-19 and serious mental illness: Experience from a psychiatric hospital in Cape Town, South Africa

Background: Several factors make patients admitted to specialist psychiatric units more vulnerable and susceptible to infections like SARS-COV-2. This includes psychiatric hospital infrastructure and service design, patients' mental health profiles, and staff's medical skills. Aim: To describe the psychiatric and medical profile, and the risk factors associated with more severe disease and clinical outcomes of COVID-19 in patients with severe mental illness (SMI) admitted to a specialist psychiatric hospital in South Africa between 1 April 2020 and 30 September 2021. Setting: Valkenberg Hospital (VBH), a psychiatric hospital in Cape Town. Method: Demographic and clinical information were collected on all VBH in-patients who tested positive for SARS-COV-2 from 1 April 2020 to 30 September 2021. Results: Two hundred and fifty-four participants tested positive for SARS-COV-2. The sample included 75% (n=191) males with a mean age of 35,7 years. Most patients were diagnosed with schizophrenia 37% (n=94), bipolar disorder 21% (n=54) and schizoaffective disorder 19% (n=49). Comorbidities reported were nicotine use 71% (n=181), hypertension 11% (n=28), and HIV 7% (n=18). Most patients, 62% (n=156), were symptomatic for COVID-19. 7% (n=17) required transfer to a medical ward. Almost all patients, 99% (n=252), recovered, and 1% (n=2) died. Conclusion: Despite the concerns that SMI and high substance use rates would worsen outcomes, most patients had mild illnesses and recovered. This contrasts with concerns raised early in the pandemic that institutionalised patients with SMI were at increased risk of mortality and an increased hospitalisation rate for COVID-19. Contribution: This descriptive study provided information on COVID-19 disease at a specialist psychiatric hospital during the pandemic

Here and there

An introspective look into loneliness, distance, and intimacy Here and There is a dreamlike depiction of the ghostly textures covering the surface of the world and those in it. The purpose of the novel is to examine how we interact with foreign spaces and what they do to identity through the lenses of Yui Nishikawa and Charlie who both either are or have navigated a foreign city for a number of years. Tokyo was chosen as the primary setting for the novel because of its unique relationship with identity and loneliness; its overwhelming anonymity despite it being the most populated city in the world. This contradiction opens the characters to questions of other contradictions; of self and other, foreign and familiar, belonging and not, of space. What interests me is what these spaces do to us, how we traverse them, fill them, or vacate them; the reformation of ourselves into something other and how these new identities find life back where they came from. The novel plays with the ideas of absence and presence and, through its focus on its descriptions of the inanimate, of architecture and contrasting spaces, tries to situate identity as a reflection of these spaces and the memories of them when they are abandoned. The question of the novel is really a question of what is left behind, of a hauntology of space and object and intimacies, how they carve themselves into identity and what remains when they are gone. The result is a dreamlike, unattached world of half things, half here and half there, half self and half other, half meaningful and half not. The novel looks to show how new spaces, new intimacies fracture then redefine, how absence can fill up various kinds of spaces, both within and without and what we are to do with the aftermath of the feeling of a neon-signed alley and the eyes of those we adored within the colours

An analysis of the digital services tax solutions presented in Africa and early-adopting developed countries to inform South Africa on the design features for taxing the digital economy

South Africa has announced plans to adopt the Organisation for Economic Co-operation and Development's (“OECD”) Two-Pillar Approach and is currently preparing for Pillar Two's implementation, as the design and consensus for the implementation of Pillar One is progressing at a slower pace. While both pillars originated from the need to address Base Erosion and Profit Shifting (“BEPS”) issues, it is Pillar One that is primarily focused on taxing digital economy, whereas Pillar Two is focused on implementing a global minimum corporate tax rate. Thus, Pillar Two's implementation may not satisfy South Africa's need to tax the digital economy and generate revenue from the supply of digital services, in the manner that Pillar One is intended to. During this time, while the future of Pillar One unfolds, South Africa may find it useful to pause and consider alternative approaches to taxing the digital economy. Digital services tax (“DST”) has emerged as the most prevalent unilateral approach to taxing the digital economy, especially among African countries. In light of the issues regarding the global consensus required to implement Pillar One and the time it will take to get the United Nations (“UN”) Framework Convention on International Tax Cooperation underway, an opportunity exists for South Africa to consider implementing a DST to tax the digital economy and benefit from the additional tax revenue to be generated in the interim. Given the existing complexities in the South African tax system, a DST presents a simpler and more manageable approach to introduce to the South African tax landscape for the purpose of taxing the digital economy. Since a DST would be introduced unilaterally by South Africa, its design features could be tailored to meet the country's specific needs for taxing digital services. Accordingly, the primary research objective of this dissertation is to identify and analyse the DST design features that South Africa could consider if a DST was to be implemented as an alternative approach to taxing the digital economy. The primary research objective is addressed by sub objectives that comprise of: discussing potential benefits and challenges of implementing DSTs, analysing the DSTs of early-adopting developed countries that were among the first to implement DSTs, by identifying key commonalities in the design features; analysing the DST legislation of the African countries that have implemented DSTs, by identifying and examining similarities and variations in the design features; and analysing the design features of the African Tax Administration Forum's (“ATAF”) Suggested Approach to Drafting Digital Services Tax Legislation (“ATAF's Suggested Approach”) with those of the African DSTs, to identify areas of alignment or deviation. ABSTRACT 4 The dissertation provides a comprehensive list of potential benefits and challenges of DSTs to assist South Africa in weighing up the positives and negatives of implementing a DST to tax the digital economy. From the further analyses performed, it is concluded among other findings, that similarities exist between the design features of the DST solutions as it pertains to the tax base, scope of digital services and minimum DST thresholds, while variations are identified in the design features regarding source rules and determining user participation. These shared trends are further interpreted to provide insights into how the DST design features could be considered by South Africa