Ammoniacal Carbonate Leaching: Effect of Dissolved Sulfur in the Distillation Operation

The distillation process in the Ammoniacal Carbonate Leaching technology was studied at bench-scale and on industrial scale. The dissolved sulfur effect in the Product-liquor that feeds to the columns, on the Basic Nickel Carbonate (BNC) properties and the operation expenses was determined. When increasing the sulfur in the liquor, we augment the selectivity towards the sulfate formation in the BNC molecule; therefore the energy consumption to the BNC thermal decomposition in the calcination process increases. Also, the nickel dissolved in the columns effluent increases due to complex reaction with [SO42–] and [S2O32–] ions, thus the expenses for consumption precipitation reagent increase too. Feeding carbonated liquor in the range 1.60 ≤ NH3/CO2 < 1.80 and CO2-rich solution increases the CO2 in the BNC with decreasing in sulfate; then, the mean diameter particle increases, the filtration resistance and the cake moisture diminish, which augments the productivity and reduces the energy consumption in the process of filtration and calcination. Keeping a pH between 8.4 and 8.7 in the columns outlet the greatest economic benefit is obtained of 0,125 ($ · h–1) per (m3 · h–1) of Product-liquor.

Biomimetic systems involving sequential redox reactions in glycolysis – the sulfur effect

Magnesium hemithioacetates were used as model cysteine compounds to mimic natural hemithioacetals, and their biomimetic oxidation reactions using a model NAD+ compounds were investigated.

Beneficial Effect of Impurity Sulfur on High-Temperature Steam Oxidation of High Chromium Ferritic Steels

The effect of S in steels on high-temperature steam oxidation resistance was investigated with respect to the content and the state in high Cr ferritic steels. The beneficial sulfur effect on high-temperature steam oxidation resistance was verified in high Cr ferritic steels. It was considered that Cr was enriched in the vicinity of the segregated S on the specimen surface because of a strong affinity between Cr and S atoms, resulting in the easy formation of the passive Cr2O3 oxide layer on the surface even after the steam oxidation test for a short time. It was found that the precipitated S operated more effectively to the improvement of the steam oxidation resistance compared to the solid-solution state of S in the steels. Furthermore, the sulfur effect on the high temperature steam oxidation resistance was related strongly to the amount of dissolution hydrogen in the high Cr ferritic steels.