South African coal and its abrasiveness index determination : an account of challenges

Abstract: Industry end users of coal like electricity generating stations have specifications on coal required in terms of reactive, chemical and physical properties; this includes the ash content, moisture, composition, hardgrove grindability index and abrasiveness index amongst many other properties. These properties affect each other including the overall coal properties and performance required during its specified usage. Some South African coals are known to be very abrasive, this causes operational challenges during the electricity generation combustion process as the coal abrades the plant equipment at a faster rate. Various South African coal samples were tested for abrasiveness index using the Yancey, Geer and Price (YGP) method. Results from these tests showed a lack of repeatability and reproducibility on the abrasiveness index values of coal samples. This lack of repeatability and reproducibility was observed in all coal samples tested. The same was found when either the same sample was tested in different laboratories or even when a mother sample was divided and tested repeatedly in one laboratory. Proximate and Ultimate analysis were conducted on the same South African coal samples for coal characterisation and classification. The size of the analysed sample; the size and shape, the degree of liberation of the abrasive coal component, and the interface between the abrasive component of coal and the blade surface are additional contributing factors. This study gives an account of challenges experienced and observed during the abrasiveness index determination of different South African coal samples. An attempt to holistically integrate the impact of main coal components contributing to the abrasiveness of coal will be presented

Innovation and modernization to prolong the South African mining beyond 2040

In June 2016, the Southern African Institute of Mining and Metallurgy (SAIMM) held a colloquium in Johannesburg South Africa the purpose of which was to create a dialogue between industry, government, research institutes and academia in the area of new technology and innovation. One of the key findings presented at the colloquium was the Chamber of Mines (COM) study indicating that the South African gold reserves dependent upon conventional mining methods will be depleted by 2031 with Platinum Group Metals (PGM) reserves signaling a similar fate..

Potentiodynamic polarisation and chronopotentiometric studies of cobalt-copper oxidised ore in sulphuric acid

The electrochemistry of leaching low grade Co-Cu oxidized ore containing 3.32% Co and 0.403% Cu in sulphuric acid was studied. Potentiodynamic polarization and potentiometric method were used...

Alkaline leaching of nickel bearing ammonium jarosite precipitate using KOH, NaOH and NH4OH in the presence of EDTA and Na2S

Please refer to full text to view abstrac

Foundry localisation strategy implementation as a vehicle to South African industrialisation : MCTS contribution

Abstract: Localisation strategy is one of the South Africa government strategies aimed at promoting economic growth and re-industrialization of the country through local content programme. The foundry sector is one of the foundation stones for metal related manufacturing and fortunately has been selected as one of the focus industries for localisation programme. However the economic sustainability of South Africa foundries have been in dramatic decline, South Africa had about 450 foundries in the 1980s, just over 200 were found in 2003 and about 170 were left in 2014. This dismal decline in foundries is due to years of underinvestment, a widening skills gap and import leakage. The South African government through its state departments had introduced localisation strategy initiative to promote procurement of local content produced locally for use in government initiated projects such as State Owned Enterprises (SOE) Infrastructure programme as a means of supporting local foundries’ competitiveness. This paper highlighted the role of the MCTS in the broader South Africa Industrialisation strategy such as; human capital development, technology transfer, product and process improvement

Biomass reduction of manganese ore in the presence of carbon monoxide

Abstract: The ferromanganese industry is currently strained by the cost of production that is continuously increasing. Alternatives of reductants are being sought to try and alleviate the production costs namely solar energy, wind and biomass. Some studies on the possible use of biomass using the South African manganese ores were conducted and as preliminary results were generated. The South African manganese industry has focused more on the pre-reduction. The current paper focuses on the use of raw macadamia nut shells for the reduction of manganese ore in the presence of carbon monoxide. The feed and products were characterized using XRD, XRF as well as SEM and compared to products currently obtained using conventional reductants. The basicity of the feed was kept at around 1. The temperature was set at 1450oC, a graphite crucible placed in a silica crucible to prevent any spillages. Comparisons between products obtained when raw macadamia nut shells and conventional reductants were used was done. It was found that macadamia nut shells have great potentials of replacing the conventional reductants used so far. The separation of slag from the metal needs imporvement as the slag structure was more needle-like and some metal entrapments were noticeable as compared to conventional process

Evaluation of ceramic media wear characteristics on the M100 Isa Mill

Since the installation of Isa-Mills, major improvements/studies have been made to make it more efficient. In 2006, ceramic media were introduced in the market to identify the cost effective type. This was achieved by the quality studies on different type of media both at the laboratory and pilot plant scale. In this present study, a 100 hours test was carried out in order to evaluate the wear characteristics of ceramic media branded candidate media and was compared to the standard media using the M100 Isa mill at the pilot plant. The evaluation was in the basis of comparing the relative performance of the candidate media and standard media in terms of wear rate, energy consumption and the finest of grind, whereby the following results were generated. A seasoned charge graph of both media at d80 μm vs. running time (hr) was generated and clearly highlighted the points of reaching seasoned charge for both media however, this didn’t help much in terms of finding the difference between the media because one cannot confirm the points of reaching seasoned charge by just looking at the graph but this can be confirmed by the actual size analysis of the media beads. A further comparison was made by comparing the finest of grinds from the Isa-Mill discharge and it does not necessarily gives a clear view of which media is better compared to the other. The media wear rate and energy consumption of both media were compared and the standard media showed a big variance from the candidate media in terms of wear and energy. The standard media stood out to be the cost-effective type compared to the candidate media. Its utilization in the plant will then be suggested

Technological feasibility and cultural acceptability study of solar power systems for microwave assisted sandstone artisanal mining

This paper investigates the technical feasibility of microwave assisted artisanal mining in the production of Sandstone from QwaQwa in South Africa. It further discusses the cultural acceptability by the rural community of the synergetic application of the emerging technology (microwave energy) and the renewable resource (solar). Sandstone in QwaQwa, Free State is artisanally mined using chisels and hammers. This form of mining is extensively laborious and is normally accompanied by numerous casualties. The paper demonstrates the existence and the possible utilization of alternative methods including emerging technologies which are more productive, efficient, effective and sustainable. The solar energy systems are used to trigger the microwave magnetron which results into high energy microwave dosage. The dosage causes differential or selective heating on the rocks which culminate into rock breaking along the interfacial grain boundaries between the different constituting minerals. The data used in the analysis was collected by administering questionnaires to the artisanal mining community in QwaQwa and from observations made on site as well as desk top information obtained from secondary sources. The paper contributes to knowledge by drawing on the solar energy systems to generate the dosage required to trigger the microwave magnetron used to facilitate a more efficient and economical artisanal mining of sandstones. In conclusion the paper recommends to policy makers the application of microwave energy in mineral artisanal mining and processing instead of the manual chisel and hammer currently being utilized country wide. It then gives a detail analysis of the technical, scheduling and economic analysis of the sandstone artisanal mining in QwaQwa

Technological assessment of product screens (137sc16/17) performance

Performance of two product screens (137Sc-16/17) constantly flooding at UG2 plant were assessed. Root causes for the flooding were investigated as well as a benchmarking with the performance of non-flooding screens performance. Samples for the screens 137Sc-16/17 feed and oversize were collected for three days, and prepared according to plant standards for sample preparations in order to obtain the particle size distribution (PSD). The first PSD results of the feed were given to Barcandyle which is mechanical engineering experts for screen sizing and their findings were used in this project for optimization purposes. The PSDs of the screens undersize, oversize and feed were used to draw cumulative percent passing and these graphs were used with the effective formula in order to determine screen performances. It was observed that 137SC-17 was more efficient than 137SC-16 and also that the major cause of flooding was due to the woodchips blinding the screen panels. From these findings the aperture size of 137SC-16 was changed from 0.63mm to 0.8mm. The screens still flood during spikes time due insufficient picking points for wood at UG2 plant

The next step in the bioremediation of heavy metal polluted water: development of suitable microbial-sorbent

Abstract In this study needful changes are inflicted on potential microbial sorbent in order to facilitate it use industrially for remediation of heavy metal pollution of water sources. Bacillaceae bacterium isolated from mining areas was transformed with cnr gene coding for nickel and cobalt resistance. Nickel recovery ability of the wild strain was then improved and prediction of adsorption behaviour made possible