Browsing by Author "De Kock, J W"

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    The manufacture of monosodium phosphate from wet process acid by amine extraction
    (1974) Price, Roger Nelson Davey; De Kock, J W; Paddon, Brian D A
    Monosodium phosphate (NaHâ‚‚POâ‚„) may be prepared from a mixture of phosphoric acid and sodium chloride on the principle that an amine in organic solution can extract the elements of hydrochloric acid (HCl). This is possible because amines are more selective for hydrochloric than for phosphoric acid. If wet process phosphoric acid is used, the impurities must be separated in some way from the final product. The work described here involves a study of the distribution of phosphoric acid itself, and the impurities trivalent iron and sulphate, between aqueous solutions and kerosene solut ions of the commercial amine Amberlite LA-1. In a countercurrent extraction process, approximately twenty theoretical stages would be needed to reduce the iron concentration to the food grade level. Sulphate is held in the organic phase. Monosodium phosphate can be recovered by stripping the organic phase with a sodium chloride solution. An attempt was made to explain the extraction of phosphoric and sulphuric acids from a mixture. It was found that amine extraction followed a pattern similar to that of gas adsorption, and a modified BET equation gave a fair but not highly accurate fit of the distribution data.
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    Mass transfer in bubble column contractors
    (1974) Rudolph, Victor; Buhr, Heinrich Otto; De Kock, J W
    Gas holdup and overall volumetric mass transfer coefficients in bubble column contactors have been investigated for water and aqueous electrolyte solutions. Two methods were used to obtain experimental data on volumetric mass transfer coefficients: the steady state oxidation technique and a transient method. The former technique was found to be unsuitable for absorption measurements because chemical enhancement of mass transfer, due to simultaneous absorption and fast reaction, caused erroneously high mass transfer coefficients to be evaluated. In the transient experiments the effect of superficial gas velocity, concentration of electrolytes in solution, bubble column diameter and gas inlet orifice diameter on the gas holdup and the mass transfer rate, were investigated. The experimental data for gas holdup and overall mass transfer coefficients obtained both in this study and from the literature have been correlated by dimensionless equations.
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    Rheological investigation of three South African gold mine pulps
    (1976) Levy, Charles David; Hansford, Geoffrey Spearing; De Kock, J W
    A method is described which enables the user to determine the rheological parameters of a fast settling slurry using conventional viscometric measuring equipment. The effect of concentration, temperature and pH on these parameters is investigated. The results agree with those obtained by previous workers using different viscometers. However, this method allows a more detailed characterization of all the properties. A literature survey was carried out and two semi-empirical correlations were found, which allow the effect of either concentration, temperature or pH on the rheological parameters to be investigated.
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    Treatment of plating plant wash waters by ion exchange
    (1973) Giddey, Trevor Baden Sydney; Paddon, B D A; De Kock, J W
    The treatment by ion exchange of the wash waters from a mixed electroplating operation has been investigated. The loading characteristics of a strong acid resin has been studied experimentally and by mathematical simulation. The ability to separate the loaded metals by complexation techniques during elution has been demonstrated. Good agreement between predicted and actual elution conditions for the particular separations have been achieved. The loading of free and metal-complexed cyanide and chromate on a strong base resin has been shown to be effective under certain resin conditions.