Formation and chemical composition of iron oxide precipitates from drainage waters in the western part of the Grantcharitsa deposit, Western Rhodopes

Abstract

Samples of water flowing from the abandoned prospecting gallery at the Grantcharitsa tungsten deposit and the accompanying ocherous iron oxide precipitates taken in different seasons are the subject of the study aimed at establishing the chemical and phase composition of ocher iron oxide materials and its relationship with water composition. The studied drainage waters are low-mineralized, with a pronounced seasonally dependent pH parameter. Water acquires the features characteristic of acid mine drainage only during the season of high waters, while at other time it is gradually neutralized. The low-crystalline (ferrihydrite+schwertmannite) precipitates formed in the place of water discharge are inhomogeneous with a variable content of Si, Fe, and W. It was found that the W content in them correlates with the Fe content.