Browsing by Author "Mutembei, Peterson K."

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    Beneficiation of Iron in Thermal-Reduced Ilmenite by Magnetic Separation
    (2013) Kariuki, Warui S.; Wachira, Jackson M.; Mutembei, Peterson K.; Waithaka, Peter N.
    ncreasing demands for Iron in countries development, and lack of conventional reducing agents has resulted into sourcing of alternative ways of beneficiating the iron ore. This paper reports on the study that was done to concentrate low grade iron ores. Raw biomass / low grade iron ore mixed in the ratio of 1:10 in a reducing environment was heated in a controlled air condition to increase the magnetic susceptibility of iron in the ore. The magnetic portion of the resulting product was separated using a horse shoe-magnet. This resulted into concentrating the ore from 45.6% - 53.1 % to 76.3%- 82.2%. This gave an ore that could be fed to a blast furnace for extraction of iron.
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    Copper extraction by wet chemical method
    (Elsevier, 2018-07) Mutembei, Peterson K.; Wachira, Jackson M.; Mwangi, Isaac; Njoroge, Peter
    In many countries large deposits of copper with no locally established copper based industries occur because known methods for extraction are prohibitively expensive and unaffordable. This study reports on an affordable and sustainable method for the extraction of copper. This was achieved through the use of a wet chemical method which makes use of hydrazones prepared in situ from chicken dung leached solution. The method involves the reduction of copper (II) ions leached from copper ore to zero valence using chlorine treated solution prepared from chicken droppings at a temperature range of 60–70 °C. The ore samples were pulverized to 250 micro millimetres and leached with hydrochloric acid to obtain leachate containing copper ions. The dissolved copper was reduced to copper metal and obtained by filtration. It was confirmed by XRFS analysis that, the metal purity was found to range between 60 and 80% depending on the ore used. In another experiment, chicken waste solution was used to extract copper from the ore. To the mixture, chlorine gas was then bubbledthrough a glass delivery tube to prepare the hydrazone in situ at a temperature range of 60–70 °C and a pure copper metal was obtained. The findings from this study have shown that there is great potential for the production of copper at low cost and this could be applied in both small-scale cottage industries and large industries using readily available resources such as chicken dung.
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    Effects of Temperature on Ilmenite During Concentration of Iron in Laterites Using Charcoal and Separation using Magnetic Separation
    (IJSET, 2014-06) Mutembei, Peterson K.; Muriithi, Naftali T.; Njoroge, Peter W.; Muthengia, Jackson W.
    Effect of temperature on ilmenite minerals found in laterites has been investigated. It was found that during reduction of iron minerals in laterites to magnetite using charcoal at temperatures of about 500-700oC, ilmenite minerals were not reduced. However when temperatures were raised to about 850-1200oC using acetylene flame, ilmenite minerals were reduce to rutile and iron. Currently, the mineral ilmenite (FeTiO3) is responsible for about 85% of the world’s titanium requirements. The methods used to upgrade ilmenite are high temperature reduction and direct acid-leaching methods. Extraction of titanium from ores containing iron still remains a challenge. Laterite soils are currently being used mainly for surfacing roads. It has been proven that laterites can be a potential source of iron. This study set out to investigate whether the heat treatment that converts hematite in laterite to magnetite is adequate to decompose ilmenite. Laterite samples were concentrated by heating charcoal/laterite mixtures in the ratios of 1:10 by mass in a slow current of air and in the temperature range of 500-700oC. Elemental analysis was carried out on both the raw laterites and the concentrated samples using Atomic Absorption Spectroscopy (AAS). The minerals present were determined using a CubiX3 Powder Diffractometer from PANanalytical Company. The results of elemental analysis showed that, raw laterites contain 28-31% iron and 1-2% titanium (IV) oxide depending on source. After the concentration, the level of iron in the heat-treated sample had increased to 55-64%, and titanium oxide increased to 3-5%. The X-ray diffraction data confirmed that, iron in the raw laterites was present predominantly as the minerals goethite, hematite and ilmenite since these are known to have diffraction peaks at angles 2θ= 21.51˚, 2θ= 54.11˚ and 2θ=32.7, respectively. After reduction (at 500-700oC), goethite and hematite peaks disappeared in the heat-treated magnet-separated samples and instead, a strong peak was observed at angle 2θ= 36˚and 2θ=32.7, which represents peaks for magnetite and ilmenite respectively. From the observation, this temperature (500-700oC), had no significant effect to ilmenite hence, was collected together with magnetite by a magnet. When reduction was done at temperature range of 850-1200oC, the ilmenite peak disappeared and a peak at 2θ=27.4, 2θ= 36˚and 2θ=44.6 appeared, attributed to rutile, magnetite and metallic iron respectively. The XRD of the tailing (non-magnetic waste) show distinct peak at 2θ=27.4 and 2θ=54.3 attributed by rutile. This shows that ilmenite minerals are reduced at high temperatures to rutile (non-magnetic) and metal iron (magnetic).
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    Magnetic Concentration of Iron in Lateritic Soils from Kamahuha, Murang’a County, in Kenya using Carbon Monoxide Generated In-Situ
    (IJSET, 2014-08) Njoroge, P. W.; Mutembei, Peterson K.; Wachira, Jackson M.; Wanjau, R.
    Chemical and Mineral Analyses of laterites from selected sites in Kamahuha area of Murang’a County, in the Republic of Kenya, have been carried out with particular interest in the levels of iron and the type of minerals the iron is present in. A laterite/charcoal mixture was heated in the temperature range 500-700OC as a slow current of air was passed through the hot mixture, the material cooled and the iron-containing mineral picked with a permanent magnet. Elemental Analysis, which was done on both the raw and concentrated samples was carried out using, Atomic Absorption Spectroscopy (AAS). The Analyses also showed that whereas the level of iron in the raw laterites was in the range 28-35, in the magnet –separated product, the level had increased to 55-62% depending on several factors such as how efficiently the laterite-charcoal mixture had been mixed and the length of time of heating.The nature of the minerals present was determined using a Brucker D2 PhaserDiffractometer. In the raw laterites, iron was present as the minerals goethite, FeO.OH and haematite, Fe2O3. These minerals have diffraction peaks at angles 2θ=21.51˚ and 2θ = 54.11, respectively. On the other hand, iron in the magnetpicked product was present predominantly as the mineral magnetite, Fe3O4, as shown by presence of a characteristic peak at 2θ = 36˚. The results of this study show that iron in laterites can be concentrated by magnetic separation after passing compressed air over hot charcoal laterite mixture.