Estudo da rota reativa do “granito” Verde Ceará por lixiviação com solução de ácido sulfúrico

Abstract

A study done with the Verde Ceará “granite” as an ornamental coating rock regarding its physical-chemical aspects in front of an alterability essay using a sulfuric acid solution with a pH initial value of 3,00 during 12 cycles of 15 days each, to simulate the acid rain that occurs in urban and industrial areas. The ABNT rules were used (with a few adaptations) for the evaluation of the disintegration degree of this ornamental rock, involving the parameters: dry weight, wet weight, and the saturated weight after each cycle, as well as, pH measures, conductivity, and concentration of the metals soluble in the residual solutions of the cycles. Petrographically, the Verde Ceará is an enderbitic gneiss. The response to the technological essays shows that the Verde Ceará presented a good internal physical resistance to leaching with the sulfuric acid solution, however, presented depositions of, basically, oxides and/or iron hydroxides over all the surface of the rock, leading to a significant colorimetric alteration, which can be easily visualized with no use of any instrument. In the general context, the exposal of this rock to acid solutions is not recommended, taking in consideration the modification of it’s natural color, which is a determining factor of commercialization.