Estudo da remoção de manganês de efluentes de mineração utilizando cal, calcário e dióxido de manganês / Study of manganese removal from mining effluent using lime, limestone and manganese dioxide

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

19/06/2009

RESUMO

Manganese is a common component of acid mine drainage (AMD). Due to its high solubility over a wide pH range, it is notoriously difficult to remove it from contaminated waters. The AMD that occurs in Mineral Industrial Complex of Poços de Caldas (CIPC) �� which belongs to the Nuclear Industries of Brazil (INB), is due to the great amount of sulfite waste disposed of the surrounding areas near the mining region. The generated acid waters with pH around 2,7 contain manganese (140 mgL-1) in concentration above the permissible level for discharging in the environment (1 mg L-1). The current water treatment removes manganese by adding lime (CaO), which produces high quantity of precipitate. This study shows the results of the removal of manganese present in acid waters of the CIPC through batch and continuous column experiments by using lime, limestone and manganese dioxide. Batch experiments evaluated the following parameters: Eh, pH, aeration, reaction time, efficiency of lime and limestone as precipitant agents, and manganese dioxide as sorbent of soluble Mn. The results show no difference between lime and limestone in manganese precipitation at pH range from 2,7 to 11. By using lime and limestone, under unaerated conditions, it was produced em effective manganese removal at pH �� 10. Under aerated conditions, the efficient removal occurred when pH reached 9,6, i.e, the aeration was not very important in the conditions studied. Under no aeration, the effective removal was at Eh <200 mV for limestone and 100 mV for lime. For the aerated system, the best results were obtained at Eh below 100 mV for both reagents. When manganese dioxide was used, the metal concentration meet the discharging limit in the pH range 6,8-7,2 with 2 g of MnO2 and 2 h of reaction. The parameters studied in the experiments with columns were: flow rate, residence time, bed volumn and the efficiency of limestone and manganese dioxide. The mine water was used as feed solution in columns packed with limestone, MnO2 or the mixture limestone/ MnO2. For columns packed with limestone, fed with mine water with pH 2,7 and 5 h of residence time, the manganese concentration did not meet the discharging limit of 1 mgL-1, as for columns containing the mixture limestone/MnO2. Finally, the best results were obtained for columns consisted of 40 mL bed volumn, packed with MnO2, fed with mine water neutralized with limestone and a residence time of 3,3 h. The highest manganese loading capacity obtained in this condition was 13,9 mgg-1

ASSUNTO(S)

mineração manganês poços de caldas mineralogia adsorção urânio drenagem acida de mina mineralogia uranium acid mine dreinage adsorption manganese mining

ACESSO AO ARTIGO

Documentos Relacionados