Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2016. / The Bushveld igneous complex in northern South Africa has the largest deposit of platinum group elements (PGE) in the world. In trace amounts, these are closely associated with base metal sulphides (BMS). Froth flotation is used to beneficiate these PGE ores. The process constitutes a bulk sulphide recovery. Improvement of recovery of the BMS is required to maximise the recovery of PGEs. The performance of the froth flotation process is largely dependent on the chemical additives used and these chemicals have been extensively studied. Mixtures of collectors are widely used in the flotation of sulphide and platinum group mineral (PGM) ores. A range of performance benefits for the use of mixtures over pure collectors have been observed on many systems. These include improved valuable metal grades and recoveries, lower reagent dosage requirements, improved rates of flotation and enhanced recovery of coarse particles. Improvements observed with mixtures of chemical reagent have been attributed to synergism; defined as the interaction of two or more agents to produce a combined effect greater than the sum of their individual effects. Synergism is highly desired in froth flotation. For this study, mixtures of thiol collectors were used in batch froth flotation tests in an attempt to identify synergism between the different collectors on flotation performance of a typical platinum ore from the Merensky reef. Flotation performance was evaluated in terms of grades and recoveries of copper and nickel, and the rate of metal flotation. Single thiol collectors of xanthate (SIBX), a dithiocarbamate (DTC) and a dithiophosphate (DTP) were evaluated to determine the effect of functional group on flotation performance. SIBX was then used in mixtures with both DTC and DTP at various molar ratios to establish whether synergism occurs between these collectors on this particular platinum ore. Molar ratios of 90:10, 80:20, 70:30 60:40 and 50:50 were considered with SIBX being the major component. Further tests were conducted with the addition of a carboxymethyl cellulose depressant to the collector mixtures.

M.Sc. / An estimated 98% of the iron ore exploited in the world is used in the manufacture of pig iron and steel, which are non-substitutable backbones of modern society. The rapid increase of world steel production over the last few years, driven mainly by economic growth in China, have required an equal increase in iron ore production, from 876.8 Mt in 2006 to 948.1 Mt in 2007. The increased rate of exploitation of iron ores has resulted in a rapid depletion of known high-grade iron ore deposits. This, in turn, has led to a dramatic increase of prices, especially for highly thought-after high-grade lumpy iron ores from BIF-hosted deposits. In the absence of any major new discoveries of high-grade iron ore deposits, mining companies have turned to lower-grade materials to assess their beneficiation potential to expand their production base and beneficiation capacity, in order to satisfy future demand. Within this existing framework, this research project was initiated to assess the beneficiation potential of low-grade lumpy stockpiles and high-grade iron ore fines at Beeshoek Iron Ore Mine, owned by Assmang Ltd. The mine is located 7 km West of Postmasburg, in the Northern Cape Province of South-Africa, and processes currently 5.60 million tons of uncontaminated run-of-mine ore per annum. Crushing, washing, classification and jigging are used to produce 2.12 million tons of (37.8% of ROM) of lumpy iron ore product. The balance (3.48 million tons) is currently not used, but is stockpiled or discarded. This includes 0.90 million tons (16.2% of ROM) of ore-grade fines, 0.86 million tons (15% of ROM) of tailings sludge and 1.74 million tons (31% of ROM) of lumpy low grade material. Both ore-grade fines and low-grade lumpy material are discarded separately; they are currently considered as waste. The low-grade lumpy is stockpiled while the fines are used to fill-in mined-out open pits. The evaluation of the beneficiation potential of these two material streams is the main goal of this study. Representative samples were collected from ore-grade fines and the current stockpile for low-grade lumpy material. Hand sorting and lithological categorization of the lumpy material facilitated petrographic and mineralogical studies using light and scanning electron microscopy, as well as X-ray powder diffraction studies. Major and trace element geochemistry were determined using X-ray fluorescence spectrometry and titrimetry (to accurately determine the concentration of iron). Whole rock densities were determined for all lithotypes recognized in the low-grade lumpy material. The grain size distribution was determined for the lumpy materials by actual measurement of the diameter of a representative number of particles, and for fines by sieve analysis. Fines beneficiation tests were conducted using spiral separation and simple classification tests. Washing was used as additional beneficiation method on the fines.

Please read the abstract in the section 00front of this document / Thesis (PhD)--University of Pretoria, 2006. / Geology / Unrestricted

Platinum-group elements (pGEs) are recovered from UG2 chromitite by milling and flotation. The mechanisms involved during beneficiation of this type of ore are still poorly understood, partly because of its complex nature. Image-analysis techniques were used to characterise the mineralogy ofUG2 chromitite from diverse geological environments, as well as the milling and flotation products derived from each of these ores. Postmagmatic alteration ofUG2 chromitite has a profound effect on the mineralogy, chemistry and recovery characteristics of the UG2 chromitite. Relatively unaltered UG2 chromitite consists predominantly of chromite and primary silicates, mostly bronzite and plagioclase with minor phlogopite, and small amounts of secondary silicates such as talc and chlorite. Trace quantities of base-metal sulphides, predominantly pentlandite, pyrrhotite and chalcopyrite ± pyrite, generally occur at chromite-silicate grain boundaries. PGEs are present both as discrete PGE minerals, and, to a lesser extent, sub-microscopically in other phases, mostly palladium and rhodium in pentlandite. The PGE mineral assemblage is characterised by sulphide minerals, mostly braggite, cooperite, nickeloan malanite and laurite, and is closely associated with the base¬metal sulphides. Recovery of PGE minerals is strongly dependent on the degree of liberation, with liberated PGE minerals and PGE minerals associated with liberated base-metal sulphides, the fastest-floating particles. PGE minerals report to flotation tailings predominantly as fine-grained inclusions in coarse silicate particles. In places, the footwall rocks have been replaced by iron-rich ultrabasic pegmatoid. As a result of interaction with Fe- and Ti-rich fluids, the chromite grains in the UG2 chromitite have been enlarged due to sintering, and the PGE mineral assemblage replaced by one consisting predominantly of laurite, Pt-Fe alloy and other non¬sulphide PGE minerals. The non-sulphide PGE mineral grains appear to be slower ¬floating than sulphide PGE minerals. Low temperature hydrothermal alteration appears to have caused relatively widespread alteration of the UG2 chromitite in some areas, resulting in corrosion and redistribution of sulphide minerals, as well as the replacement of primary magmatic silicates by secondary silicates such as pumpellyite, epidote, prehnite, albite, talc, chlorite and quartz. Ore from such areas are characterised by a base-metal sulphide assemblage consisting predominantly of millerite, chalcopyrite, and pyrite. Base¬metal sulphide and PGE minerals occur in fine-grained intergrowths with silicates, resulting in poor liberation. In the samples investigated, composite particles were often faster-floating than expected, at least partly due to the presence of naturally floatable talc. The effect of faulting on the mineralogy of the UG2 chromitite probably depends on distance from the fault zone, and possibly also timing of faulting, and can cause cataclasis of the ore. Where cataclasis occurred, broken mineral grains are cemented by secondary, hydrous silicates. Liberation of base-metal sulphides and PGE minerals are poor, and recoveries consequently very low. It was demonstrated that reasonable estimates of total PGE+Au recovery can be made from the mineralogical characteristics ofUG2 chromitite ore. Based on the mineralogy of ore from a specific area, provision can be made for appropriate adjustments to metallurgical flowsheets. / Thesis (PhD)--University of Pretoria, 2006. / Geology / Unrestricted

No description available.

This investigation has been carried out for the purpose of determining the effect of solid particle size distribution on the roasting and leaching of a complex sulfide ore. The effect of pulp density in the leaching process has also been studied. The oxidizing roast of the combined sulfide concentrates, prepared by bulk sulfide flotation and tabling, was conducted with a fluidized-bed kiln. The calcines were leached by dilute sulfuric acid in an autoclave. The following conclusions have been reached: 1. In the fluidized-bed roasting, the solid particles within the size range of minus 35 to plus 150-mesh would have a higher overflow rate from the fluidized bed. This inference might be effective only when the roasting is conducted under the conditions performed in this investigation. 2. In the process combining fluidized-bed roasting and dilute sulfuric acid leaching, the effect of solid particle size is significant. The solid particles within the size range of minus 65 to plus 150-mesh have the highest iron recovery, the highest copper and zinc extraction rates and the lowest sulfur content of leach residue. 3. In dilute sulfuric acid leaching there is no significant effect of pulp density within the range tested in this investigation. The general trends are: iron recovery decreases as the pulp density decreases, extraction rates of copper and zinc decrease as pulp density increases, and there is little pulp density effect on the sulfur content of leach residue. / Master of Science

This investigation deals with the application of high pressure and high-temperature leaching techniques to separate out zinc and copper from the iron constituents of a calcined sulfide ore. An important variable in this study proved to be the concentration of the leaching reagent -- sulfuric acid. The leaching temperature was varied within a range of 250°F to 550°F., and 8 cubic centimeters to 20 cubic centimeters of sulfuric acid in 2000 cubic centimeters of distilled water was employed as the leaching agent concentration. The major equipment utilized for roasting was the fluidized bed and an autoclave for leaching. After the physical and chemical treatments of roasting and leaching of the calcine, the resulting constituents were studied by means of quantitative chemical analysis. Numerical theories were used to correlate the points obtained into continuous functions of the leaching temperature, concentration of sulfuric acid and the recovery percentage. From these curves, it is concluded that the recovery of the impurities in the calcine is proportional to the leaching temperature and the concentration of the leaching agent. However, under certain circumstances, the leaching action causes loss of iron in the calcine, and the minimizing of the loss in leaching is also studied. / Master of Science

The probability of particle capture by an isolated bubble rising through a suspension of particles has been determined using fundamental principles of fluid mechanics. This analysis has allowed the rate constant for flotation to be evaluated as functions of bubble sine, particle size, flotation column diameter, air flow rate and critical film rupture thickness. The last parameter is a measure of the hydrophobicity of the particles to be floated. Using the theoretically determined rate constant, a population balance model has been developed for the flotation of fine coal in a column. The model is capable of predicting the dynamic response of the flotation column to changes in a wide range of operational conditions. Model simulations have been found to be in reasonable agreement with experiments conducted using a bench-scale column. / Ph. D. / incomplete_metadata

A research report submitted to the Faculty of Mining Engineering. University of Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Engineering / Hlstorically South Africa has enjoyed a privileged position with its vast natural resource base in that it has.not needed to generate wealth but has merely explored this base, The only true way to create wealth, is to add value to a commodity by means of beneficiation, South Africa is the world's largest producer of vanadium accounting for approximately 70% of the western world's requirements. Unfortunately the South African producers of vanadium mainly export vanadium in the form of slag and pentoxide, instead or ferrovanadium and other prime alloys. ( Abbreviation abstract) / AC 2018

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The extraction of mineral values from ore requires liberation of the minerals followed by separation. Liberation is achieved by size reduction operations which are inefficient processes typically accounting for up to 70% of the energy consumption in a mineral concentrator (Tromans, 2008). As the grade of ores reserves declines, future viability of mineral operations will be determined by the costs of comminution. Recent work has shown that microwave treatment of secondary crusher product at specific microwave energy consumption of the order of 1 kWh/t reduces the work index of the ore and increases grade and recovery in batch flotation tests. Improved liberation at coarse sizes was also demonstrated (Kingman, 2006). Based on these findings work is ongoing to commercialise the technology. The objective of this study is to develop a modelling framework to determine the value proposition of microwave treatment of ore. It was noted that various models exist in literature for modelling of mineral processing flotation flow sheets, but these models do not incorporate the feed ore liberation property as an input variable in their calculations. Thus, a fundamentally derived property based model was identified as appropriate for flow sheet modelling of microwave treated ore, as it utilised liberation as an indirect variable in calculating the flotation rate constant through the use of contact angle to describe particle surface hydrophobicity. The model was successfully incorporated into the flotation flow sheet units developed in HSC Chemistry and used with Mineral Liberation Analyser (MLA) data to investigate the effects of changes in feed ore liberation on rougher cell flotation recovery. Different liberation scenarios based around modification of porphyry copper flotation feed were created. A sensitivity analysis of the various feed stream liberation scenarios was carried out to test the ability of the model to effectively model the differences in downstream processing of microwave treated and untreated ores. For a single flotation cell of size 85 m3 with a solids feed flow rate of 890 tph, it was observed that below a certain size (120 μm in the case of the porphyry copper ore) changes in flotation feed liberation had no significant effect on value mineral recovery. Significant differences in value mineral recovery were observed only at coarser sizes above 120 μm. The results indicated that improvement in recovery of value minerals due to improved liberation from applying microwave technology has size limits and is significantly dependent on the feed grind size. Feed grind size sensitivity analysis was then carried on the same single cell flow sheet utilising feeds with the same mineralogy but with different grind sizes. The results indicated that maximum benefits from the application of microwave technology would be best obtained by utilising coarse grinding at sizes between P70 = 200 μm and P70 = 300 μm for the porphyry copper ores considered in this study. Coarse grinding appears to be the best way to exploit improved liberation in downstream processing of microwave treated ores. Investigations similar to those carried out on the single cell flotation flow sheet were then carried out on a continuous plant rougher flotation flow sheet. The flow sheet consisted of nine rougher cells in series each with a volume of 85 m3 with a solids feed flow rate of 890 tph into the bank of rougher cells. The results indicated that there was no significant difference in final rougher bank overall cumulative recovery at fine grind sizes below a P70 grind size of 120 μm with improvements in feed ore liberation. Feed grind size sensitivity analysis showed a significant variation in cumulative recovery at coarse grind sizes of above P70 = 129 μm .This variation was attributed to improvements in flotation feed ore value mineral liberation from locked composite particles to the maximum possible theoretical liberation scenario of fully liberated value mineral particles. A 7.2 percentage point improvement in cumulative value mineral overall recovery and a 2 to 3 percentage point improvement in enrichment ratio was also observed above the P70 = 250 μm grind sizes after improving the flotation feed ore value mineral particle liberation of a typical flotation plant feed to a maximum. The increases in grade and cumulative recovery at coarse sizes were attributed to improvements to the flotation plant feed ore value mineral particle liberation. From the results, it was concluded that microwave technology application will offer greater benefits in downstream processing of coarse ground ores. / AFRIKAANSE OPSOMMING: Die ekstraksie van mineraalwaardes uit erts vereis bevryding van die minerale gevolg deur skeiding. Bevryding word bereik deur verkleiningsprosedures wat ondoeltreffende prosesse is en wat gewoonlik vir tot 70% van die energieverbruik in ʼn mineraalkonsentreerder verantwoordelik is (Tromans, 2008). Algaande die graad van ertsreserwes afneem, sal toekomstige lewensvatbaarheid van mineraalprosesse bepaal word deur die koste van vergruising. Onlangse werk het getoon dat mikrogolfbehandeling van sekondêre vergruiserproduk by spesifieke mikrogolf-energieverbruik van ongeveer 1 kWh/t die werkindeks van die erts verminder en die graad en opbrengs in lotflottasietoetse verhoog. Verbeterde bevryding by growwer groottes is ook aangetoon (Kingman, 2006). Werk gaan voort op grond van hierdie bevindinge ten einde die tegnologie te kommersialiseer. Die doel van hierdie navorsing is om ʼn modelleringsraamwerk te ontwikkel om die waardeproposisie van mikrogolfbehandeling van erts te bepaal. Daar is in die literatuur afgekom op verskeie modelle vir die modellering van vloeidiagramme vir flottasie van mineraalverwerking, maar hierdie modelle inkorporeer nie die voerertsbevrydingseienskap as ʼn insetveranderlike in hulle berekeninge nie. ʼn Fundamentele afgeleide eienskapgebaseerde model is geïdentifiseer as geskik vir vloeidiagrammodellering van mikrogolfbehandelde erts, aangesien dit bevryding as ʼn indirekte veranderlike by die berekening van die flotteertempokonstante aangewend het deur die gebruik van kontakhoek om hidrofobisiteit van die deeltjieoppervlak te beskryf. Die model is suksesvol in eenhede van die flottasievloeidiagram wat in HSC Chemistry ontwikkel is, geïnkorporeer en tesame met data van die mineraalbevrydingsontleder (MBO) gebruik om die gevolge van veranderinge in voerertsbevryding op die opbrengs van voorskeiselflottasie te ondersoek. Verskillende bevrydingscenario’s is geskep wat óm die modifisering van porfierkoperflotteringstoevoer heen gebaseer is. ʼn Sensitiwiteitsontleding van die verskillende voerstroombevrydingscenario’s is uitgevoer om die vermoë van die model om die verskille in stroomaf-verwerking van mikrogolfbehandelde en onbehandelde ertse te toets, doeltreffend te modelleer. In die geval van ʼn enkele flottasiesel van 85 m3 groot met ʼn vastestof-toevoervloeitempo van 890 tph, is waargeneem dat veranderinge in flottasietoevoer-bevryding benede ʼn sekere grootte (120 μm in die geval van die porfierkopererts) geen beduidende uitwerking op die opbrengs van die waardemineraal gehad het nie. Beduidende verskille in die opbrengs van die waardemineraal is slegs by growwer groottes bo 120 μm waargeneem. Die resultate het daarop gedui dat verbetering in die opbrengs van waardeminerale as gevolg van verbeterde bevryding ná die toepassing van mikrogolftegnologie beperkinge ten opsigte van grootte het en opvallend afhanklik is van die toevoermaalgrootte. Sensitiwiteitstoetsing van toevoermaalgrootte is daarna op dieselfde enkele selvloeidiagram wat voerders met dieselfde mineralogie gebruik uitgevoer, maar met verskillende maalgroottes. Die resultate het daarop gedui dat maksimum voordele van die toepassing van mikrogolftegnologie die beste verkry sou word deur gebruik van growwe maling by groottes tussen P70 = 200 μm en P70 = 300 μm vir die porfierkoperertse wat in hierdie navorsing in oorweging geneem is. Growwe maling skyn die beste manier te wees om verbeterde bevryding in stroomaf-verwerking van mikrogolfbehandelde ertse te eksploiteer. Ondersoeke soortgelyk aan dié wat op die vloeidiagram van die enkelselflottasie uitgevoer is, is toe op ʼn deurlopende vloeidiagram van die aanlegvoorskeierflottasie uitgevoer. Die vloeidiagram het bestaan uit nege voorskeiselle in serie elk met ʼn volume van 85 m3 met ʼn vastestof-toevoervloeitempo van 890 tph in die ry voorskeiselle. Die resultate het daarop gedui dat daar geen aanmerklike verskil in algemene kumulatiewe opbrengs van die finale voorskeiry by fyn maalgroottes benede ʼn P70-maalgrootte van 120 μm met verbeteringe in voerertsbevryding was nie. Sensitiwiteitsontleding van voermaalgrootte het ʼn beduidende variasie in kumulatiewe opbrengs by growwe maalgroottes van bo P70 = 129 μm getoon. Hierdie variasie is toegeskryf aan verbeteringe in waardemineraalbevryding van flottasietoevoererts uit geslote saamgestelde deeltjies tot die maksimum moontlike teoretiese bevrydingscenario van ten volle bevryde waardemineraaldeeltjies. ʼn Persentasiepuntverbetering van 7.2 in die kumulatiewe algemene opbrengs van waardemineraal en ʼn persentasiepuntverbetering van 2 tot 3 in die verrykingsratio is ook bo die P70 = 250 μmmaalgroottes waargeneem ná verbetering van die bevryding van die waardemineraaldeeltjies van die flottasietoevoererts van ʼn tipiese flottasieaanlegtoevoer tot die maksimum. Die toenames in graad en kumulatiewe opbrengs by growwe groottes is toegeskryf aan verbeteringe in die bevryding van die waardemineraaldeeltjies van die flottasietoevoererts. Op grond van die resultate is daar tot die gevolgtrekking gekom dat toepassing van mikrogolftegnologie groter voordele in stroomaf-verwerking van grofgemaalde ertse sal bied.