A study of making synthetic oxy-fluoride construction material using waste serpentine and kaolin mining tailings

The purpose of this study is to convert waste serpentine mining tailings (WST) and waste kaolin mining tailings (WKT) into useful construction materials such as the oxy-fluoride material by addition of calcium fluoride sludge (CFS). The experimental results show that WST, WKT, CFS and Al2O3 with contents of 18%, 42%, 30%, and 10% can be utilized as resources for producing oxy-fluoride material. XRD analysis shows that main crystalline phase is the anorthite and minor crystalline phase is the diopside and shannonite in the oxy-fluoride material. Compressive strength test shows a maximum resistance of 150 MPa. Toxicity characteristic leaching procedure (TCLP) shows that heavy metals and fluorine do not release into the solution, which indicates converting them into stable forms in the oxy-fluoride material. This recycling technology of utilization of mining tailings and sludge can produce the oxy-fluoride material thus reducing disposal costs and avoiding secondary pollution, in accordance with the concept of sustainable development.

► Mine tailing and sludge are reutilized to produce construction material.
► Oxy-fluoride material is synthesized and the process is to avoid secondary pollution.
► Its compressive strength reaches 152 MPa.