Characterisation of Small-Scale Gold Mining Tailings in the Western Region of Ghana

On average, small-scale miners can recover gold ranging from 20% to 70% of the total available gold by the conventional gravity separation methods only. As a result of this, tailings materials from Artisanal Small-Scale Gold Mining (ASGM) operations contain a significant amount of gold, and characterisation of these materials would inform metallurgical decisions concerning reprocessing of the tailings from ASGM. In this study, size-by-size analysis, gold grade, gold deportment, and cyanidation studies were carried out on ASGM tailings samples collected from five different locations (Asankragua, Bogoso, Prestea, Wassa-Akropong, and Tarkwa) in the Western Region of Ghana. Head grades of tailings samples from Asankragua, Bogoso, Prestea, Wassa-Akropong, and Tarkwa were 1.84 g/t, 4.12 g/t, 0.45g /t, 0.17 g/t, and 5.97 g/t, respectively. The 80% (P80) of the tailings materials passed through 1.797, 0.578, 1.636, 3.210, 0.380 mm screen sizes for samples from Asankragua, Wassa-Akropong, Tarkwa, Prestea and Bogoso, respectively, with an average of 1.52 mm. Also, the gold deportment analysis revealed that the highest metal distribution of 42.03% in -106 µm size fraction for samples from Bogoso, followed by 31.0% for Wassa-Akropong, 29.7% for Tarkwa, 27.0% for Prestea, and 22.0% for Asankragua. It was shown after cyanidation test works that the highest gold recovery was 81.5%, 72.3%, 75.3%, 65.6%, and 38.5% for samples from Wassa-Akropong, Asankragwa, Prestea, Tarkwa, and Bogoso, respectively. Cyanidation can thus be employed to get higher gold recovery in ASGM

Towards sustainable urban development: the social acceptability of high-rise buildings in a Ghanaian city

Over the years, many city managers, policy makers and academics alike have turned to high-rise buildings as pathway to sustainable urban development. However, the sustainability of such types of development in various geographical contexts, especially in sub-Saharan Africa, is a subject less explored. Amidst the promotion of high-rise development in a rapidly urbanizing metropolis in Ghana, Kumasi, the research empirically examined the social acceptability of high-rise residential facilities and the institutional capacity for their effective management. By conducting face-to-face interviews with sampled households, and critical public service providers in the metropolis, the study uncovered that, contrary to the evidence from many Asian cities, there is generally low social acceptability of high-rise developments, and a weak institutional capacity for effective service delivery. The research concludes that, whilst it is tempting to embrace high-rise buildings as sustainable development pathway, it is crucial they are pursued with much circumspection. In addition to their design being tailored to the local needs of the people for whom they are built, the promotion of high-rise development should recognize the importance of effective service delivery, and general social acceptability

Key roles of leaves, stockplant age, and auxin concentration in vegetative propagation of two African mahoganies: Khaya anthotheca Welw. and Khaya ivorensis A. Chev

Leaf area, IBA concentration and age of stockplants were all found to be important factors for successful rooting for vegetative propagation using single-node cuttings of the two main African mahogany species: Khaya anthotheca and K. ivorensis. Cuttings with leaf area of 30-50 cm2 had the best rooting percentage and cuttings with about 30 cm2 had the most number of roots per cutting in K. anthotheca. Khaya ivorensis, cuttings with 10-30 cm2 leaf area had the highest rooting percentage. Cuttings collected from 1-year-old stockplants recorded the highest rooting percentage and largest number of roots per cutting. Cuttings from 3-year-old stockplant of the same seeds sources had the lowest rooting suggesting aging negatively impacted rooting ability. The effect of auxin concentration, on rootability was examined with cuttings of K. anthotheca. An IBA concentration of 0.8% was the best exogenous auxin concentration for percentage rooting, number of roots per cutting and the length of the longest root per cutting. © 2008 Springer Science+Business Media B.V

Silvicultural systems for plantation mahogany in Africa: Influences of canopy shade on tree growth and pest damage

Overexploitation of the African mahoganies, Khaya anthotheca and K. ivorensis, could lead to their commercial extinction in the near future. Efforts to establish plantations to sustain supply have been discouraged by the shoot borer Hypsipyla robusta Moore. We hypothesized that there is a shade level at which Hypsipyla attack and branching are reduced, but height growth is adequate. We report on the growth of these African mahoganies and Hypsipyla attack under three different forest canopy shade levels: open (55% open sky), medium shade (26% open), and deep shade (11% open). Hypsipyla attack on K. anthotheca was 85%, 11%, and 0% attack in the open, medium, and deep shade treatments, respectively. However, growth in medium and deep shade was slow. Mean tree height for K. anthotheca was 413.8, 126.2, and 54.5 cm in the open, medium and deep shade treatments, respectively. K. ivorensis showed similar trends. The reduced growth under these shade levels limit the use of this strategy for controlling Hypsipyla attack. © 2007 Elsevier B.V. All rights reserved

Relative susceptibility of four species of African mahogany to the shoot borer Hypsipyla robusta (Lepidoptera: Pyralidae) in the moist semideciduous forest of Ghana

We examined the relative susceptibility of four mahogany species, Khaya ivorensis, Khaya anthotheca, Entandrophragma angolense, and E. utile, to Hypsipyla robusta attack. Seeds were obtained from one to three parent trees for each species. The research was conducted in the moist semideciduous forest zone in Ghana and used a randomized complete block design. Tree height and diameter and height to first branch were measured until 24 months after out-planting in the field. H. robusta damage was assessed by counting the numbers of shoots attacked, branches, and dead shoots. Khaya spp. grew better but experienced more attack than Entandrophragma spp. The relative susceptibility to H. robusta attack, from most to least, of the four species was: K. anthotheca \u3e K. ivorensis \u3e E. angolense \u3e E. utile. At 24 months, the mean number of shoots attacked per tree ranged from 1.0 for an E. utile seed source to 3.6 on for a K. anthotheca seed source. At 15 months, K. anthotheca and K. ivorensis started branching at about 1.5 m, but height of clear trunk increased over time due to self-pruning. As K. anthotheca grew taller, the number of H. robusta attacks per tree declined. This suggested that selection of genotypes and species that are tolerant of H. robusta attack based on infestation of young plants may not be appropriate. Genetic factors more completely reflecting the response of different species and genotypes to H. robusta attack may manifest themselves at later growth stages. © 2007 Elsevier B.V. All rights reserved

Tree tenure and its implications for sustainable land management: The case of Parkia biglobosa in the Northern Region of Ghana

Parkia biglobosa is a multipurpose species found in Savannah agroforestry parklands of West Africa. The species is important as it prevents against land degradation while providing food and other products. This study focuses on how land and tree tenure arrangements affect tree populations in three traditional areas in the Northern Region of Ghana (Dagomba, Gonja and Mamprusi) and the implications that these arrangements have for sustainable land management. Focus group discussions and key informant interviews were held in the three communities to provide information on the tenural arrangements of Parkia biglobosa. A tree census was conducted to estimate the densities of Parkia biglobosa in crop and fallow fields. The study shows that differences in tenure systems in the three traditional areas have implications for Parkia biglobosa populations and also for sustainable land management. It is concluded that traditional tenure systems along with regulation protect the trees from destruction as observed in the Dagomba and Gonja areas compared to the open access system identified in Kperiga in the Mamprusi area