Sulfidizing of chromium stainless steels : E. P. Pukhovskii and others. Metallovedenie i Obrabotka Metallov, v.2, no. 5, 1956, pp. 40–43; 5 fig., 3 tables, 1,200 words. (No. 3799, $ 2.90)

Abstract

The kinetics of sulfidization of malachite in sodium hydrosulfide and tetrasulfide as the sulfidizing agents was investigated in this study. The sulfidization reaction occurred in two stages. The first stage involved the formation of a primary sulfidized layer and the second involved two types of secondary reactions. One was the precipitation of copper ions which diffused through the primary layer, and the other was the oxidation of the sulfidizing agent to oxysulfide species. The influence of the type and concentration of the sulfidizing reagent and solution pH was determined. A significant difference in the surface morphology was observed for malachite treated with these two reagents. With sodium tetrasulfide, a uniform sulfidized layer formed on the particle surface, whereas for sodium hydrosulfide, the malachite surface was coated with loosely adherent precipitates, which might peel-off upon agitation. The results indicate that the extent of the reaction in the second stage was smaller in sodium tetrasulfide than in sodium sulfide.