Remoção de íons cálcio e magnésio do rejeito da mineração de rocha fosfática, empregando cascas de banana, batata e fibra da casca de coco como materiais biossorventes

Abstract

Mining has a prominent place in the domestic and international arenas as it provides a wide variety of materials for industries. A large amount of water is required to extract and prepare these minerals for use. These practices alter the quality of the water used in the process. With that, if the water is to be recirculated, it requires appropriate attention. For the apatite froth flotation, the 𝑪𝒂𝟐+ and 𝑴𝒈𝟐+ as well as other ions present in the recirculated water act as process depressants, directly affecting the achievement of good levels of metallurgical yield of this mineral. Therefore, in order for the water to be recirculated and reused in the apatite flotation process, it is of the utmost importance that these ions are not in the medium. In doing so, there would be a reduction in the collection of new water. Minding the aforementioned need, the objective of this work was to evaluate the removal efficiency of 𝑪𝒂𝟐+ and 𝑴𝒈𝟐+ ions present in the waste derived from the phosphate rock mining through the adsorption process done with the use of banana peel, potato and coconut shell fiber biomasses. In order to execute these experiments, a 2³ factorial experimental design, with a triplicate at the central point was performed, where the analyzed factors were water pH (factor "A"), varying among 6, 7 and 8; time of contact with biomass (factor "B"), varying among 10, 20 and 30 min; and biomass concentration ("C" factor), varying among 10, 20 and 30 mg / L. Therefore, in order to verify the existence of a significant effect among the three analyzed factors, in addition to the interaction between them, an analysis of ANOVA variance was performed using the statistical software Minitab®. The results obtained showed that the banana peel presented Maximum Removal Percentage (%Rem) of 𝑪𝒂𝟐+ions totaling 62,54% when A=8, B=10, C=30, but none of these factors showed any statistical significance to the response and this adsorption followed Freundlich’s model. This biomass did not present any efficacy for the removal of 𝑴𝒈𝟐+ ions. In the adsorption with the potato peel, %𝑹𝒆𝒎𝒎á𝒙= 44,53% when A=7, B=20, C=20 and the factors A and B showed statistical significance to the response, by increasing them, the response also increases. Furthermore, its absorption followed Langmuir’s model. This biomass did not show any efficacy for the removal of 𝑴𝒈𝟐+ ions. For the 𝑪𝒂𝟐+ ion removal, the coconut shell fiber presented %𝑹𝒆𝒎𝒎á𝒙= 65,81% when A= 20, B=20, C=20, but only factor C demonstrated statistical significance to the response, by increasing it, the response also increases. Its adsorption followed Freundlich’s model. This biomass presented %𝑹𝒆𝒎𝒎á𝒙= 49,67% for the 𝑴𝒈𝟐+ ions, also when A= 20, B=20, C=20, however, none of these factors presented statistical significance to the response and its adsorption followed Langmuir’s model.