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Toronto, Canada

Golden Star Resources Ltd , is a mid-tier Canadian gold mining company, whose principal operating properties are located in Ghana, West Africa. It has a total historical production of over two million ounces of gold. Wikipedia.

Dankwah J.R.,University of Mines and Technology | Baawuah E.,Golden Star Resources | Dankwah J.,Kwame Nkrumah University Of Science And Technology | Koshy P.,University of New South Wales
Proceedings of the 24th International Mining Congress of Turkey, IMCET 2015

One of the major obstacles to the implementation of an appropriate plastics recycling scheme is the inhomogeneity of many plastics waste. Accordingly, most of the existing recycling schemes require a feedstock that is reasonably pure and contains only items made from a single polymer type. This often requires sorting into different polymer fractions, a process that is both cumbersome and expensive. This work therefore investigates the reduction of two sources of iron oxide by mixed plastic waste (MPW) and its blend with sawdust (SD) through experiments conducted in a laboratory scale horizontal tube furnace. Composite pellets of EAF slag (47.1% FeO) with a blend of MPW and SD were rapidly heated at 1520 °C under high purity argon gas and the off gas was continuously analysed for CO, and CO2 using an online infrared gas analyser (IR). The extent of reduction after fifteen minutes was determined for each carbonaceous reductant. The results show that iron oxide can be effectively reduced to produce metallic iron using MPW and its blend with SD as reductant. An improvement in extent of reduction was observed over conventional metallurgical coke and the individual polymers when the blend (MPW+ SD) was used as reductant. This eliminates the need to sort out individual plastics from municipal solid waste for their effective utilisation as reductants, carburisers and desulphurisers in iron making. Source

Perrouty S.,Toulouse 1 University Capitole | Lindsay M.D.,Toulouse 1 University Capitole | Lindsay M.D.,University of Western Australia | Lindsay M.D.,Monash University | And 4 more authors.
Ore Geology Reviews

A three-dimensional model of the gold-rich Paleoproterozoic Ashanti Greenstone Belt has been built with a "hybrid" geological modeling method using Geomodeller and Gocad, then inverted using VPmg software. The model helps to identify the main regional-scale controls leading to abundant gold mineralization in the southeast of the belt by highlighting the lithological distribution and geometry of geological structures. The three-dimensional geological model shows that 85% of gold occurrences in the Ashanti Greenstone Belt are proximal to a specific tholeiitic metabasaltic horizon "BV1". This result is noteworthy given that the relatively thin, 300. m thick, BV1 layer represents only 10%, by volume, of the modeled Sefwi Group stratigraphy. A map of distance between the topography and the BV1 layer is produced and identifies areas showing a high probability to host gold deposits in the southeast of the Ashanti Belt. Possible structural controls performed by the BV1 tholeiitic metabasaltic rocks on the location of gold occurrences are discussed, and we hypothesize that the BV1 layer acted as a mineralization trap or source of gold. Both hypotheses agree with examples from the literature and explain the observed distribution of the mineralized sites. © 2014 Elsevier B.V. Source

Parra-Avila L.A.,University of Western Australia | Bourassa Y.,Golden Star Resources | Miller J.,University of Western Australia | Perrouty S.,University of Western Ontario | And 2 more authors.
Journal of African Earth Sciences

The Ashanti Belt in Ghana hosts numerous multi-million ounce gold deposits and is one of the most richly gold endowed Paleoproterozoic belts of the West African Craton. This work shows that the Wassa mineralized intrusion is part of the Sefwi Group. This unit at Wassa is strongly magnetic and show a distinctly high response in regional magnetic data sets compared to other units of equivalent age within the belt. The unit is inferred to be a lateral extension of an exposed fragment of what defines the substrate to the Tarkwa Basin sediments.The Wassa deposit, located in the eastern limb of the belt, is hosted within mafic to intermediate volcanic flows that are interbedded with minor horizons of volcaniclastics, clastic sediments. The clastic sediments include wackes and magnetite rich sedimentary layers, presumably derived from banded iron formations. The previously described sequence is intruded by syn-volcanic mafic intrusives and felsic porphyries rocks that are all part of the Birimian stratigraphy. Two new key SHRIMP II U-Pb ages were determined as part of this study: a new age of 2191 ± 6 Ma was determined on magmatic zircon grains of the Wassa porphyry host rock, which now represents the oldest known felsic intrusion hosting gold mineralization in the Ashanti Belt region.The Benso gold deposit system, which is located in the eastern limb of the Ashanti Belt approximately 38 km southwest of Wassa is hosted within a series of volcanic units intruded by mafic to intermediate units. A SHRIMP II U-Pb age of 2157 ± 5 Ma was determined from magmatic zircons obtained from a granodiorite of the G-Zone of the Benso deposit. This granodiorite is the main host rock for gold mineralization and thus the age provides an upper constraint for mineral emplacement.The newly determined ages provide an upper constraint for the gold mineralization within this region of the Ashanti Belt. They also support recent structural studies that have interpreted that the Wassa mineralization is related to the Eoeburnean period, defined to have occurred between 2191 and 2158 Ma (D1 event) prior to the main phase of gold mineralization. This new U-Pb age on the host rock provides an upper age limit to the Wassa mineralization of ca. 2191 Ma and is compatible with the proposed Eoeburnean early mineralization model for the Wassa deposit. The age of the intrusion along with the location of the deposit in the Sefwi Group give a unique characteristic that distinguishes Wassa from the other gold deposits along the Ashanti belt which are believed to have been the result of a mineralizing event between ca. 2090 and 2070 Ma. © 2015 Elsevier Ltd. Source

Addy M.,AEL Mining Services | Thomas T.,AEL Mining Services | Korankye F.,Golden Star Resources
Performance of Explosives and New Developments: Workshop Hosted by FRAGBLAST 10 - The 10th International Symposium on Rock Fragmentation by Blasting

Bogoso Mine operates in very close proximity to some of its neighboring communities, and complaints related to blasting vibration and airblast were becoming alarming. Several modifications to the blast parameters have proved successful in reducing vibration and airblast below threshold levels. This paper investigates one of the techniques used, which was to stop using 400 g boosters in favor of 250 g and 150 g boosters. Most explosive suppliers recommend the use of 400 g boosters in hole diameters greater than 102 mm. Any potential correlation was therefore thought to be related to a run-up in Velocity of Detonation (VOD) and that steady state VOD is not reached due to the very short bench height and explosive column length. The investigation found that there was no correlation between the different booster sizes and vibration and airblast levels and VOD's generated. The successful reduction of these levels is therefore only attributable to the other blast parameters that were modified. Source

Perrouty S.,Toulouse 1 University Capitole | Ailleres L.,Monash University | Jessell M.W.,Institute Of Recherche Pour Le Developpement | Baratoux L.,Institute Of Recherche Pour Le Developpement | And 2 more authors.
Precambrian Research

Integration of regional geophysical datasets and detailed field observations provide new insights into the paleoproterozoic structural evolution of southwestern Ghana. The study area is dominated by three metavolcanic and metasedimentary packages known as the Sefwi Group, the Kumasi Group (Birimian) and the Tarkwa Group (Tarkwaian) that were intruded by abundant TTG granitoids during the Eoeburnean and Eburnean phases of an event termed the " Eburnean Orogeny" . This study identifies an Eoeburnean (pre-Tarkwaian) deformation event (D1) that produced significant deformation in the Sefwi Group metavolcanics. D1 is associated with N-S shortening manifested as regional scale folding in the southern Ashanti Belt. D1 synorogenic granitoids were intruded between 2187. Ma and 2158. Ma under greenschist metamorphic condition. Syn-D1 gold mineralisation associated with quartz veining could be the original source of Tarkwaian paleo-placers and/or remobilised gold concentrations along major shear zones.D2 represents an extensional phase associated with the Kumasi Group sedimentation (2154-2125. Ma) which could be related to activation of major structures such as the Ashanti Fault as low angle detachments that controlled the deposition of the Kumasi Group and the opening of the Kumasi and Akyem Basin. The Tarkwa Group (2107-2097. Ma) unconformably overlies the Birimian Supergroups and was deposited in response to D3 shortening. D3 resulted in the inversion of syn-D2 detachments faults within the Ashanti Belt. NW-SE D3 shortening produced regional scale folding within the Birimian and the Tarkwaian metasediments. D4 deformation corresponds with sinistral reactivation of D3 thrust faults, and is locally associated with macro-scale folding at Obuasi and Wassa gold mines. By the end of D4, the regional scale architecture was built and was only slightly modified by the two last events. D5 postdates the Eburnean metamorphic peak and corresponds to open recumbent folds associated with a subhorizontal crenulation cleavage. D6 is present as a subvertical crenulation cleavage and reverse faults associated with NE-SW shortening. © 2012 Elsevier B.V. Source

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