We studied the formation of ant communities on rock dumps at coal mine dump sites of different ages and in natural environments in southwestern Siberia. The species composition and diversity were studied by means of plot sampling and line-transect surveys, while the nest density of ants was determined using pitfall traps. Soil pH, turf extent, and vegetation cover were measured and their effects on the formation of ant communities were evaluated. Our results revealed that ants' density and species diversity increased with progressing recovery of the dumps. In the first succession phase, the soil at the dumps was alkaline and sites were inhabited primarily by Tetramorium caespitum. The density and the number of Myrmica sp. and Formica sp. nests increased with here was an increase in with increasing soil acidity. Lasius sp. ants were the first to form significant clusters of nests and to become numerically dominant at all the studied sites.