High levels of elements such as sodium (Na), potassium (K) and phosphorus (P) in iron ore minerals are known to reduce the quality and price of these minerals. South Africa, as one of the world largest exporter of iron ore, is affected by this problem. Both potassium (K) and phosphorus (P) are peculiar to South African iron ore. The present study has therefore focussed on developing an environmentally friendly biological method for lowering the levels of K and P in iron ore minerals. Short and long term experiments were set up to isolate, identify, screen and test potential bioleaching bacteria and fungi from different environmental samples. The study started by investigating the possible relationship that exists between weathering and bioleaching processes. The investigation was intended to provide relevant information on the natural role of microorganisms such as ectomycorrhizal (ECM) fungi in the mining environment. The experiments involved the use of both mycorrhizal and non-mycorrhizal Pinus patula seedlings for the weathering of iron ore minerals. Four types of ECM fungi were used, namely Pisolithus tinctorius (PT), Paxillus involutus (PI), Laccaria bicolor (LB) and Suillus tomentosus, (ST). From the results, ectomycorrhizal weathering can be said to be species-specific and significantly influenced by fungal type and particle size. In addition, it was also discovered that both mycorrhizal and non-mycorrhizal roots can participate in weathering processes. Further investigations of ECM fungi when not in symbiosis, were carried out to know how or if they can be potential candidates to mobilise K and P from iron ore minerals. The experimental set up involved in vitro pure cultures of four different ECM fungi, namely Pisolithus tinctorius (PT), Paxillus involutus (PI), Phialocephala fortini (PFR), and Suillus tomentosus (ST). In addition, the treatments involved the use of five different particle sizes of each ore type. The results obtained indicated the potential of the ECM fungi to mobilise P and K from the two iron ore types though at different levels. Factors such as ore type, particle size, organic acid production and attachment of the fungi to the iron ore were all found to influence the mobilisation of nutrients from these ores. Another experiment that addressed some of the limitations encountered with the use of pure cultures of ECM fungi was conducted. Isolated indigenous fungal pure cultures from the surfaces of iron ore minerals were screened for their abilities to solubilise minerals by lowering the levels of K and P. These isolates were identified molecularly as close relatives of three genera that included Penicillium, Alternaria (2 isolates) and Epicoccum for isolates FO, SFC2/KFC1 and SFC2B respectively. The identified Penicillium sp. turned out to be the only phosphate solubiliser among these isolates. Direct bioleaching capability of the fungus was compared to that of its metabolite. At the end, the metabolite showed better K removal than the direct use of the fungi. Interpretation of these results indicates possible relationship between K and P removal, and the organic acids production by this fungus. Other factors such as particle size and mineral type were also found to significantly influence the leaching process. Additional experiment was conducted to investigate the indigeous bacteria and their potentials in reducing the K and P contents of iron ore minerals. A total of 23 bacterial strains that belong to Proteobacteria, Firmicutes, Bacteroidetes and Actinobateria were isolated from the iron ore minerals and identified with molecular methods. All the bacterial isolates were screened for their potential as mineral solubilisers. Only eight of the isolates were selected and used in shake flask experiments that contained both KGT and SK mineral types as their sources of K and P. The experiment showed that all the eight isolates have potentials to produce organic acids especially high levels of gluconic acid but lower quantities of acetic, citric and propanoic acid. Scanning electron microscopy (SEM) and fourier transform infrared (FITR) analyses also helped to uncover the role that biofilm and extracellular polymeric substances could play in mineral solubilisation. Finally, an investigation of a new method for reduction of K and P levels of iron ore minerals was carried out, focussing on the use of cheap resources as well as septic conditions. The study involved the use of fermented spoilt grape fruits (Vitis sp.) and the solution from the product utilised in shake-flask experiments. Treatments involved two types of iron ore minerals (KGT and SK) and two different particle sizes. The result suggests the significant effect of particle size, time and organic acids on the reduction of K and P from the iron ore minerals. The important part of this finding is the discovery of a cheap microbial energy source (spoilt grape) that can be further exploited for full biobeneficiation of iron ore minerals. Another advantage of this method is the fact that the experiment can be conducted under non–sterile conditions, making it a system that can be operated outdoor. / Thesis (PhD)--University of Pretoria, 2010. / Microbiology and Plant Pathology / unrestricted

The main purpose of this study was to optimise the grain size distribution of the raw material mixture for the production of iron sinter. It well known that the constitution of the sinter mix is based on the knowledge of chemical composition and grain size distribution. Although Mittal Vanderbijlpark has fixed specifications on the physical and chemical properties of the sinter for optimal blast furnace performance, the particle size distribution of the sinter mix has not yet been optimized. This was achieved by using the granulation characteristics of the sinter mix and the green bed permeability tests. The influence of the moisture content of the feed, granulation time, and mean granule diameter on permeability was investigated on Thabazimbi and Sishen iron ore, as well as on their mixture with fluxes and without fluxes. The iron ore results indicated that the mixture containing 20% Thabazimbi iron ore and 80% Sishen iron ore with fluxes where the coke, lime and return fines were sized by removing the – 0.5 mm size fraction of the return fines and coke, and the 1 mm size fraction of lime has the highest permeability of all the studied mixtures. The sintering properties of the mixtures of optimised grain size distributions were also investigated and the results were very similar for all the mixtures and better than the base case mixture, which was not optimised with respect to grain size distribution. / Dissertation (MEng)--University of Pretoria, 2008. / Materials Science and Metallurgical Engineering / unrestricted

Thesis (MBA)--Stellenbosch University, 2007. / ENGLISH ABSTRACT: Human resources budgeting at Sishen mine had been done, for as long as the researcher has been employed at the mine, according to history as well as according to the demands of the financial situation. Consequently, human resources shortages have been corrected by external labour which is often more expensive than internal labour. During the annual budgeting period when top management applies pressure to cut costs, the operations budget is easy to defend. With the help of Excel spreadsheets or maintenance management systems, maintenance managers can present strong arguments for not cutting the operations budget. Budget deficits are then easily corrected by means of negative adjustments to the human resources budget. This research will explore the issue of whether a tool exists to calculate the human resources budget scientifically. A target was set to develop a tool or model for human resources budgeting or to investigate whether such a tool does not already exist. A literature survey was done to determine world best practices regarding the calculation of human resources budgeting. The literature studied guided the researcher to a computerised maintenance management system (CMMS) and it was found that Sishen already has one of the best (SAP) in place. Sishen even has a process (Routine Work Management or RWM) in place which helps to get all maintenance information into SAP to make the necessary information available for effective maintenance. It was further found that SAP, which has been used by the mine for several years, can already provide the human resources requirements for any future period. The RWM process which helps to get information in and out of SAP has been in use for some time already. Unfortunately the process was poorly executed and the information is not reliable. This statement is supported by the internal (Kirstein, 2006) and external (Aurea, 2006) audits done at the mine during 2006. The external audit was done by Aurco (2006). The author concluded that Sishen has a tool but not a strategy to utilise RWM successfully. One of the reasons why RWM was poorly executed was the fact that there is a lack of support from the people in the workplace. These individuals claim that they were not consulted when RWM was introduced at the mine and as a result they did not buy in. A proper change management process was not followed and the employees suspected that RWM was implemented to play policeman or to measure how much spare time they have and reduce the workforce accordingly, as in the case of the Prometheus project. Consequently they admit to manipulating RWM's measured outcomes, ignoring it or deliberately undermining it. They added that RWM is easy to manipulate and perceived it as a farce by many of the participants, A decision was taken to use the Kotter change management process to run a project to get RWM to the required level. Kotter's eight steps for successful large-scale change can be utilised with great success to achieve the required changes. After a brainstorming session and from the recommendations of the two audits a list of ideas was compiled. These ideas should help to get RWM to a level where human resources requirements can be drawn from SAP for any period in the future. Although the research was aimed at getting human resources budgeting from SAP, it will also have other advantages. The ratio between planned and unplanned maintenance will be better because RWM will ensure better maintenance / AFRIKAANSE OPSOMMING: Mannekragbegroting op Sishen-myn is, vir solank die navorser deel is van die myn, gedoen volgens die behoeftes van die verlede asook volgens wat deur die finansiele situasie toegelaat is. Gevolglik het dit dikwels gebeur dat die tekorte aan mannekrag aangevul is met huurarbeid wat dikwels duurder is as eie mannekrag. Tydens die begrotingsrondte kan die geld wat aangevra word vir die instandhouding van die toerusting goed beveg word omdat die instandhoudingspersoneel waterdigte argumente kan aanvoer oor hoe die begroting bereken is. Begrotingstekorte word gevolglik maklik reggestel met negatiewe aanpassings op die mannekragbegroting. Hierdie studie gaan die bestaan ondersoek van 'n gereedskapstuk of model om die mannekragbegroting wetenskaplik te kan bereken. Daar is 'n doelwit gestel om 'n model te ontwikkel vir mannekragberekening of om vas te stel of daar nie reeds iets bestaan nie. 'n Literatuurstudie is gedoen om vas te stel wat wereldwye beste standaarde ten opsigte van mannekragberekening is. Dit het die navorser gelei na gerekenariseerde instandhoudingsbestuurstelsels (CMMS) en daar is bevind dat Sishen reeds een van die beste stelsels gebruik (SAP). Sishen het selfs 'n proses ("Routine Work Management" of RWM) om alle instandhoudingsinligting in SAP te kry sodat die regte inligting weer beskikbaar kan wees vir effektiewe instandhouding. Daar is verder bevind dat SAP, wat reeds vir verskeie jare in gebruik is, enige tydperk in die toekoms se mannekragbehoeftes kan bepaal. Die RWM-proses wat moet help om inligting in en uit SAP te kry, is ook reeds geruime tyd in gebruik, maar ten spyte daarvan word die proses afgewater en is die inligting nie betroubaar nie. Hierdie stelling is bewys deur middel van twee ouditte wat in 2006 op RWM gedoen is. Die een audit was 'n interne audit terwyl die ander deur die maatskappy Aurea gedoen is. Die afleiding kon dus gemaak word dat daar wel 'n gereedskapstuk is, maar dat geen strategie bestaan om dit effektief te gebruik nie. Een van die redes waarom RWM as 'n afgewaterde proses beskryf kan word, is 'n gebrek aan ondersteuning deur die mense in die werksplek. Die mense beweer dat hulle nie geken is ten tye van die bekendstelling van RWM nie en hulle het dus nie ingekoop nie. Die afleiding is gemaak dat daar nie goeie veranderingsbestuur toegepas is toe RWM aan die myn bekendgestel is nie. Die werknemers het vermoed dat RWM ingestel is om hulle te polisieer of te bepaal hoeveel vrye tyd hulle het en die werksmag dienooreenkomstig af te skaal, soos in die geval van die Prometheusprojek. Gevolglik het hulle erken dat hulle die RWM se uitkomste gemanipuleer het, dit geignoreer het, of doelbewus ondermyn het. Hulle het bygevoeg dat RWM maklik gemanipuleer kan word en dat baie dit as 'n klug beskou. Daar is besluit om die Kotter-model te gebruik om 'n projek te loods om RWM op die vereiste standaard te kry. Dit word as die geskikste model beskou om die nodige veranderingsbestuur toe te pas. 'n Lys van idees is opgestel na aanleiding van 'n dinkskrumsessie met die werknemers asook van voorstelle wat in die twee ouditverslae gemaak is. Herdie idees moet RWM in plek kry sodat mannekragbehoeftes vir enige tydperk in die toekoms vanuit SAP verkry kan word. Alhoewel die navorsing daarop gemik was om mannekragbegroting vanuit SAP te bekom, hou dit ook 'n ander voordeel in, naamlik 'n beter verhouding van beplande tot onbeplande instandhouding omdat goeie RWM-prosedures beter instandhouding en gevolglik beter beskikbaarheid gaan verseker.