Treatment and reuse of solid materials containing inorganic sulfur compounds

Abstract

In the environment, different types of solid phase systems can contain high concentrations of inorganic sulfurous compounds, e.g. ores, soils and sediments. The key criterion in the assessment of environmental risks of inorganic sulfurous compounds present in these materials is whether they remain bound to the solid phase or whether they are mobilized into the solution. Mobility of inorganic sulfur in natural water/solid biphasic systems is predominantly controlled by oxidative or reductive changes and precipitation constants of sulfurous compounds. In anaerobic environments, sulfur is encountered in its most reduced form, i.e. sulfidic form. Owing to the poor solubility of most sulfidic compounds, sulfurous compounds are predominantly immobile in anaerobic environments. On the contrary, in aerobic environments, the most stable inorganic sulfur compound is sulfate, which is usually very soluble in water. Reductive and oxidative changes of inorganic sulfurous compounds often involve an interaction with protons. Sulfur reduction is usually accompanied with alkalization of the environment, whereas sulfur oxidation often results in acidification. The general overview of the effects of reductive and oxidative