Tailings reprocessing from Cabeco do Piao dam in Central Portugal: a kinetic approach of experimental data

The mining waste and tailing dam are object of discussion due to the accidents that occur due to a lack of control or due to interest in the remaining minerals present in these materials. Most of the old tailings dams have high contents of heavy metals which could represent potential risks to the environment or be an alternative source of some critical raw materials. The case study of the Cabeco do Piao dam in Central Portugal involved tailings from a processing plant that belonged to the Panasqueira Mine Complex, which has been in operation for over 120 years. Waste rock and mining tailings were deposited in the area until 1995, and they represent an environmental liability for the local population due to their high content of toxic metals. Tailings reprocessing can be considered as a solution that minimizes social and environmental impacts, recovers some essential minerals, such as Zn, W, and Cu which can help to offset investments made. The project design involves several stages of metal concentration, determined by experiments, as well as a model of the process. The overall model will take into account technological constraints, social-economic conditions and environmental impacts. A preliminary result of an optimization study of the kinetic approach is presented in this piece of work.