Chemical Engineering Publications

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Chemical Engineering Publications

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    Use of coal fly ash to manufacture a corrosion resistant brick.
    (Elsevier, 2019) Moyo, V.; Mguni, N.G.; Hlabangana, N.; Danha, G.
    In this article, we investigate the use of an environmental waste (coal fly ash) in the manufacture of an ammonium nitrate corrosion resistant brick. Ammonium nitrate (AN) fertilizer spillages and vapors continuously corrode the civil structures in a fertilizer manufacturing plant situated in Zimbabwe. This situation is a safety hazard to more than a hundred plant personnel and hence a priority area for research. Our experimental results show that addition of sodium silicate improved the performance of the brick. Water absorption of bricks generally decreased with an increase in the amount of sodium silicate added. Our results also show that the compressive strength generally increased with increase in amount of sodium silicate added and that the corrosion resistance increases with the amount of sodium silicate added to the coal ash bricks.
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    The use of calcium sulphate dihydrate (CaSO4. 2H2O) as a bleaching agent for crude soya bean vegetable oil.
    (Elsevier, 2019) Chakawa, D.P.; Nkala, M.; Hlabangana, N.; Muzenda, E.
    The use of calcium sulphate dihydrate (CaSO4.2H2O) as a bleaching agent during the refining of crude soya bean vegetable oil was investigated. Different weight ratios of CaSO4.2H2O bleaching agent relative to crude oil (2, 4, 5, 10, 20 and 30 wt. %) were prepared. One sample of raw crude without any bleaching agent added was isolated as a control. Each of the 7 crude oil samples were preheated at a temperature range of 80ºC - 120ºC.The different weight compositions of CaSO4.2H2O were added and the respective slurries agitated for 30minutes.The agitated slurry was then filtered. The experimental results for red color were recorded and % free fatty acids (ffa) and % bleachability were calculated. The results indicated that there was decrease in red color of crude oil from 14R-4.3R with increase in weight ratio of bleaching agent. There was also an increase in red color bleachability from 24.285 % - 60.714% with increase in weight ratio. % ffa and solid nonfat (SNF) remained constant at 0.56% and nil respectively. The results indicate that calcium sulphate dihydrate (CaSO4.2H2O) is an effective bleaching agent in bleaching of crude soya bean vegetable oil.
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    The novel use of calcium sulphate dihydrate as a bleaching agent for pre-processing beef tallow in the soap manufacturing process
    (Elsevier, 2019) Chakawa, D.P.; Nkala, M.; Hlabangana, N.; Muzenda, E.
    In this article we investigate the use of CaSO4.2H2O as an effective bleaching agent for pre-processing of beef tallow destined for use in the soap manufacturing process before storage. The use of CaSO4.2H2O in this particular novel application has never been demonstrated before. Five respective 100 g beef tallow samples were bleached by agitation using a speed of 120 rpm for 30 minutes at different CaSO4.2H2O weight fractions. The different weight fractions used were 1, 2, 3, 5 and 10 wt. %. After bleaching at a constant melt temperature of 90°C, the respective slurries were filtered and analyzed for red and yellow colors respectively as well as for % ffa. The results indicated an increase in red color bleachability from 0 to 68.75 wt. % with an increase in wt. % CaSO4.2H2O from 1 to 10wt%. Yellow color bleachability also increased from 23.65 to 93 % with increase in wt. % of CaSO4.2H2O from 1 to 10 wt. %. The results demonstrate that CaSO4.2H2O is an effective beef tallow bleaching agent for adsorbing red color, brown color and yellow chlorophyll type contaminants that are present in beef tallow.
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    Effect of media shape on particle breakage in a batch ball mill: Lessons learnt from population balance model and attainable region technique. Procedia Manufacturing, 35.
    (Elsevier, 2019) Khumalo, S.; Hlabangana, N.; Danha, G.; Muzenda, E
    The batch grinding equation and the Attainable region technique tools were used in evaluating data obtained from the breakage of quartz ore in a laboratory batch ball mill. Using the same milling conditions and grinding equipment, test results were evaluated through the breakage distributions of different size fractions. Results prove that mixing different grinding media increases volume of grinding zones and that translates to an improvement in grinding kinetics and amount of required PSD. The tools are valuable and practical ways of evaluating the breakage of materials on the size fractional base and results of which can be used in the mathematical modelling and optimising of ball milling unit operations.
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    Statistical analysis of the significance of variation in properties of cotton stalk fibres extracted from different sections of the cotton stalk.
    (International organization of Scientific Research, 2017-05) Nkomo, N.Z.; Nkiwane, L.C
    Abstract:-Cotton is cultivated primarily for its boll fibre and little use is made of the cotton stalk. The cotton stalks are breeding ground for pests therefore the stalks are normally burnt in the field creating air pollution. Cotton stalks were collected from farms through random sampling and subjected to natural water retting and there after mechanical decortication and categorised according to their location relative to the stalk as top section, middle section and bottom section fibres. The physical properties of the cotton stalk fibres was characterised by tensile strength, moisture regain, linear density, diameter and fibre length tests. These results were analysed using one way multivariate analysis (MANOVA) in SPSS with three levels being one for each section of the stalks to test the statistical significance of the differences of the fibre properties from different sections of the cotton stalk. Pillais trace test showed that there was statistical significant difference between fibres from different locations when considered jointly on the variables tensile strength, elongation, fibre density, fibre diameter, fibre length, linear density and moisture regain. This test was followed up by Tuskey’s HSD post hoc test which showed which parameters varied between which sections of the stalk.