Study of clinker dopped with P and S compounds

The sintering and the structure of clinkers, modified by the introduction of different ionic forms of sulfur and phosphorus into the raw mix, were examined. One reference synthetic mixture and 25 modified mixtures were prepared by mixing the reference sample with 0.5, 1.0, 1.5, 2.0 and 2.5%w/w of chemical grade CaSO₄, CaS, Ca₃(PO₄)₂, CaHPO₄ and Ca(H₂PO₄)₂. Free lime content in all samples was measured. The sintering reactions in samples were recorded by means of differential thermal analysis. The texture of the clinkers was examined using a scanning electron microscope and EDX. It is concluded that, despite of their relatively low doping concentration in the raw mix, P and S affect considerably its reactivity and the texture of the clinker. The various ionic forms of the same element (SO₄ ^2-, S^2- for S, PO₄ ^3-, HPO₄ ^2- and H₂PO₄ ^- for P) exhibit a different and unequivocal effect on the reactivity of the synthetic raw mix and on the texture of the corresponding clinkers. S (in both forms) and P (added as HPO₄ ^2-) are mainly dissolved in the melt and they have a positive effect on the burnability of the raw mix. P (added as PO₄ ^3- or H₂PO^4-) is preferentially accumulated in belite. In this case further stabilization of β-C₂S occurs and the binding of the free lime is hindered. This revised version was published online in August 2006 with corrections to the Cover Date.     

O-diphenylmethylation of alcohols and carboxylic acids using diphenylmethyl diphenyl phosphate as alkylating agent

Diphenylmethyl diphenyl phosphate reacts quickly under mild conditions with various alcohols and carboxylic acids towards diphenylmethyl ethers and esters respectively while hydroxyacids can be selectively alkylated at the alcohol site.     

The use of diacetoxyphenyliodine for the direct oxidative conversion of S-protected L-cysteine compounds to L-cystine derivatives

Diacetoxyphenyliodine was used for the direct oxidative conversion of S-Trt, S-Dpm and S-Acm-$\text{L}$-cysteine derivatives to optically pure {=L}-cystine compounds.     

Secondary raw materials in cement industry

The sintering and hydration processes of a modified cement raw mix were examined using thermal analysis techniques. One reference and four modified mixtures, prepared by mixing the reference sample with 0.5, 1.0, 1.5 and 2.0 % w/w of a wolframite-stibnite mineral were studied. The clinkering reactions were recorded and the total enthalpy change during the sintering was determined by means of a differential scanning calorimetry. The combined water and the Ca(OH)₂ content in samples hydrated for 1 to 28 days were determined, using thermogravimetry. As it is concluded, the effect of the added mineral on the sintering and hydration reactions can be fully recorded and evaluated using thermal analysis. This revised version was published online in July 2006 with corrections to the Cover Date.