Effects of Sodium Iso-butyl Xanthate Dosage on the Froth Flotation of Bead Milled Middle Group 1-3 PGM Ore Blend

An investigation was carried out to determine the effects of collector concentration on the grade and recovery in the flotation of middle group 1-3 Platinum Group Metal (PGM) ore mixture. The ore mixture pulp at a relative density of 1.29 was subjected to “bead milling” test, particle size distribution analysis and the 55% passing 75 µm was froth floated at 180, 200 and 220 g/t dosages of sodium isobutyl xanthate (SIBX) and 30 and 80 g/t of Senfroth and Sendep 30D frother and depressant, respectively. The results obtained indicated the predominance of the <38 µm PGM values in the ore and confirmed the need for tertiary milling for better liberation of the PGMs. The grade of the PGM concentrate obtained when dosing at 200 g/t of sodium isobutyl xanthate was highest at 94 g/t and gave the lowest recovery of 53%. The 180 g/t SIBX dosage resulted in highest PGM recovery of 70% and lowest grade of 84 g/t, while dosing at 220 g/t SIBX gave average PGM grades of 90 g/t and recoveries of 60%. The results obtained thus showed that that an SIBX dosage of 180 g/t SIBX would be appropriate when higher recoveries are targeted, while 200 g/t dosage will yield higher grade

A new U-PB Zircon age for the Portobello Granite from the Southern part of the Natal Metamorphic belt

The Portobello granite, which crops out along the littoral in southern Natal is an S-type, red-coloured, foliated, chlorite-biotite granite that preserves evidence of low-temperature alteration. It intruded the 1091 ± 7 Ma Munster Suite quartz monzonori

U-Pb SHRIMP ages and tectonic setting of the Munster Suite of the Margate Terrane of the Natal Metamorphic Belt

New U-Pb Zircon SHRIMP ages of 1091 ± 7.1 Ma and 1093.1 ± 5.8 Ma have been determined for two discrete phases of the Munster Suite. The Munster Suite is a calc-alkaline mafic to intermediate suite of intrusive igneous rocks that form part of the sout

The nature of the Grenville-age charnockitic A-type magmatism from the Natal, Namaqua and Maud Belts of southern Africa and western Dronning Maud Land, Antarctica

The &acd;1030-1090Ma old, locally charnockitic, intrusions which are exposed from Namaqualand in the west, through Natal, into the Maud Province Antarctica in the east, show A-type, within plate granite characteristics. The major and trace element characteristics from all the intrusions are remarkably similar and consistent and are typical of C-Type charnockites. Two-pyroxene thermometry as well as thermometry utilising calibrations from experimental studies of saturation surfaces using Zr, P and Ti suggest temperatures between &acd;850℃ and &acd;1100℃. Pressure estimates from aureole assemblages suggest depths of emplacement between 30-10km. Available isotopic data suggest magma sources in Natal and Antarctica were juvenile, probably mantle derived whereas those in Namaqualand suggest a significant crustal contribution

Geochronology of emplacement and charnockite formation of the Margate Granite Suite, Natal Metamorphic Province, South Africa: implications for Natal-Maud belt correlations

The Margate Granite Suite underlies much of the Margate Terrane of the Natal Metamorphic Province, SE South Africa. It consists of foliated granites grouped into four main lithotypes: garnet leucogranite, garnet-free leucogranite, charnockite and garnet-biotite augen gneiss. In this study we present new U-Pb (SHRIMP) zircon geochronological data on each of the four lithotypes to constrain the timing of emplacement of the various granite phases and of charnockite formation. Magmatic zircon ages span a period of about 125 Ma, indicating that the Margate Suite does not comprise a single coeval group of plutons. The oldest crystallisation age of 1169 ± 14 Ma, obtained from the garnet-biotite augen gneiss phase, is statistically similar to that of the Sikombe Granite which is exposed to the south of the Margate Terrane, with which a correlation is made. This implies that the magmatic history of the Margate Terrane is longer and more complex than previously thought. The original granite protolith of a sample from the charnockitised granite in the thermal aureole of the (ca. 1040 Ma) Oribi Gorge granite yielded an age of 1135 ± 11 Ma, which is statistically similar to the published age of the gneissic Mzimilo Granite in the Mzumbe Terrane. Zircon overgrowths in this sample, dated at 1037 ± 13 Ma are coeval with the age of the Oribi Gorge granite and are interpreted to date the secondary charnockitisation of the Margate granite. A sample of a partly charnockitised garnet leucogranite provided an age of 1088 ± 9 Ma. This granite contains a pervasive foliation (S2), partly obliterated in charnockitic patches, indicating that both the D2 event and the charnockitisation are younger. This confirms previous work in which the maximum age of the main fabric-forming deformation was constrained by the 1091 ± 9 Ma age of the Glenmore Granite. A sample from the garnet leucogranite in the type area of the Margate Granite Suite yielded an age of 1043 ± 4 Ma, which is statistically similar to that of the previously dated, garnet-free leucogranite of the Portobello granite, and zircon metamorphic dates of the secondary charnockitisation event associated with emplacement of the Oribi Gorge Suite. Our new data show that the Margate Terrane was subjected to at least four magmatic/thermal events, at ∼1170 Ma, ∼1135–1140 Ma, ∼1082–1093 Ma, and 1025–1050 Ma. These events can be correlated with coeval magmatic and thermal episodes in surrounding crustal blocks within Rodinia and Gondwana. In particular the Margate Terrane appears to correlate well with the Vardeklettane Terrane of Dronning Maud Land, East Antarctica and furthermore that the Natal belt may be up to 80 Ma older than the Maud belt east of the Heimefront Shear Zone, which is made up of younger crust which was accreted westwards against the Natal belt. In this scenario, the Cape Merdith Complex, West Falkland, which shows no zircon evidence of crust older than ca. 1135 Ma, forms part of the Maud belt, not the older Natal belt.Funding for the SHRIMP analyses was provided by the Vaal University of Technology

Metamorphic history and U-Pb Zircon (SHRIMP) geochronology of the Glenmore Granite: Implications for the tectonic evolution of the Natal Metamorphic Province

A new SHRIMP U-Pb zircon age of 1091 ± 9 Ma has been acquired for the gneissic, S-type Glenmore Granite from the Margate Terrane of the Natal Metamorphic Province. The Glenmore Granite contains two foliations and mineral textures indicate it underwent t

Metamorphic history and U-Pb Zircon (SHRIMP) geochronology of the Glenmore Granite : implications for the tectonic evolution of the Natal Metamorphic Province

A new SHRIMP U-Pb zircon age of 1091 ± 9 Ma has been acquired for the gneissic, S-type Glenmore Granite from the Margate Terrane of the Natal Metamorphic Province. The Glenmore Granite contains two foliations and mineral textures indicate it underwent two metamorphic episodes separated by a period of retrogression. The presence of a folded S1 foliation in the Glenmore Granite indicates that it was either pre- or syntectonic relative to D1, thus providing a maximum age constraint of 1091 ± 9 Ma on the D1 event in the Margate Terrane. This is ~60 Ma later than the completion of the main tectonism (D1–3) documented from the Tugela Terrane, suggesting diachronous arc accretion. Syntectonic granitoids with ages of ~1090 Ma have also been documented from the Mzumbe terrane, as well as from Western Dronning Maud Land (east Antarctica), and the Cape Meredith Complex in the Falklands, which on reconstruction of Gondwanaland, lie adjacent to the Natal Metamorphic Provinc