[en] Mining and processing activities dealing with mineral ores containing associated uranium and thorium series elements can make these radionuclides available in their products, byproducts and in the environment, leading to the enhancement of the exposure of the public to natural radiation. In the present study, niobium, phosphate, coal and gold mining plants have been selected as case studies, aiming to identify possible radiological impact sources during and after ceasing the operation on these units. In order to achieve that, the radiological characterization of samples from ore processing, drainage water and other liquid emissions was carried out. The potential environmental radiological impact was quantified by means of estimating the effective dose equivalent, H_E, for present and future scenarios considering the use of the environment in the vicinities of the units and future tailing storage sites. The results confirm these mining industries as activities potentially enhancing exposure to natural radiation. The possible use of solid wastes, abandoned at the end of operation, represents a long term radiological concern. The acid drainage, as well as the chemical processing of mineral ores constitute relevant impact factors for present and future scenarios. Thus, the legislation for environmental licensing must be reviewed in order to take into account the potential environmental radiological impact caused by these units, as well as the establishment of remediation procedures for waste storage areas in the existing sites. (author)