Browsing by Author "Hiji, Morris Frank"

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    Application of response surface methodology for optimization of vat leaching parameters in small scale mines: case study of Tanzania
    (Open Science Publisher, 2015) Hiji, Morris Frank; Maganga, Sospeter Pastory
    In this work, the Response Surface Methodology (RSM) was used to study and optimize the vat leaching operating parameters namely as cyanide concentration, slurry pH and particle size. The experimental design was performed with aid of Minitab (version 16) statistical software. The Central Composite Design (CCD) was used to model and analyse the effect of the operating parameters. According to a quadratic model, the optimal conditions for highest gold leach recovery of 83% were found by a cyanide concentration of 950 ppm, slurry pH of 10.5 and particle size of 240 µm. The results are much significant compared with the current gold recovery of between 60 to 70%. The samples were collected at Nyarugusu small scale mines (Geita, Tanzania).
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    Process development of the synthesis of 2, 3-dichlorophenylpiperazine
    (Beijing University of Chemical Technology, 2007) Hiji, Morris Frank; Zheng, GuoJun; Yuan, QiPeng
    The new pathway for the synthesis of 2, 3-dichlorophenylpiperazine from cheap raw material, 2, 3-dichloroaniline is presented. The hydrogen sulphate salt of 2, 3-dichloroaniline was converted to the corresponding Aryl Iodide in good yield of 81 % by reacting with conc. H2SO4 and NaNO2 to form intermediate diazonium salt, which was further displaced by Kl. The desired product was obtained by reacting Aryl Iodide and piperazine in the presence of CuI as catalyst, proline as ligand, K2C03 as base and dimethyl sulfoxide as solvent with yield of 20 % . The method is simple, utilizes cheap catalyst and ligand, insensitive to moisture; it is easy to separate the product, and can undergo large-scale production.
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    Producing sulphuric acid in Tanzania and potential sources: A review
    (Open Science, 2014) Hiji, Morris Frank; Ntalikwa, Justin William; Vuai, Said Ali
    Sulphuric acid is a backbone of chemical industry, agriculture and energy sectors. Tanzania has potential sources of producing its own sulphuric acid. The three most common methods: contact process, wet process and lead chamber process of producing sulphuric acid are reviewed. A modified lead chamber method can be a preferred method of producing the mineral acid by using local available raw materials according to Tanzania environment. Among of raw materials, pyrites from Samena area in Geita Region, Tanzania are the most potential, although there are also other sources from operating gold mines. Production of sulphuric acid in Tanzania could make a meaningful contribution to country economy.