Dissolution Experiment of the Halite of Palaeogene Shahejie Formation, Shulu Sag, Eastern China

Dissolution mining is the main production mode for well salt. Understanding the dissolution property of halite is very important controlling mining efficiency and to predict shapes of the salt cavern. The dissolution experiment of the halite of Paleogene Shahejie Formation, Shulu Sag, and Jizhong Depression is conducted in this study. The results show that, along with the rise of baume degrees, the lateral dissolution rates decline gradually from 7–8 to 1–2 mm/h; and the lateral dissolution angles increase gradually from 9° to 34°. The contents of NaCl of the brine increases linearly, from 50 to 320 g/L, while the contents of the CaSO₄ stay around baseline. More than 77% of the dissolution residues are smaller than 2 mm and the sinking rates of these fine residues are very little, from 2.8 to 2.0 cm/s. These results indicate in the early stage of the mining that fresh water should be injected to accelerate the forming of the caverns; and in the late stage of the mining, brine of low concentration should be injected, which will help to maintain the high dissolution rates and discharge the residues in a timely manner. This will guarantee the long-term continuous production of the salt mine.