Neutralização de drenagem ácida de minas com escória de aciaria elétrica do forno-panela


IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia




The acid mine drainage (AMD) is formed when certain sulfide minerals are exposed to oxidizing conditions. The AMD is commonly associated with coal mining, especially in coal waste deposits that contain high pyrite (FeS2) concentration. The neutralization of AMD using alkaline materials, like limestone and steel slag is one of the useful remediation techniques. The aim of this work was to study the performance of an electric steel slag of a ladle furnace in the neutralization of the AMD in a percolation bed in a comparative way with limestone, material normaly used for this purpose. The methodology of this work is based in the set up of two systems at labotatory scale, one with open channel bed and the other with bed packed reactor. The studies were directed in order to evaluate the neutralization capacity and the quality of the treated effluent, considering the following parameters: pH, Fe, Al, Cr, Mn, Zn, Ca, Mg, hardness, sulphate, conductivity, and toxicological efects to microcrustacean and fish. Addicionaly, some studies was carried out to caracterize the slag before and after application in the neutralization of the AMD, looking for a future destination. The use of the packed bed reactor for the AMD treatment showed better results than the open channels. The reactor avoids the percolation of the effluent to preferential ways, increasing the volume treated/volume of the bed ratio. The tests carried out with slag of the ladle furnace in the packed bed reactor proves that this material have great basicity allowing the equalization of the effluent output to be discharged in a neutral pH degree with metals removal, while with limestone the metals upstake is partial, remainig Fe and Mn with values above than the allowed by the legislation to effluent discharge. In both cases, the efluent didn¿t show toxicity. One of the identified problems to both materials was the metalic hidroxid recovering in the surface, reducing the useful life of the system and the volume of treated effluent. The expansibility tests showed that the ladle furnace slag in the original form have expansive characterists. After the neutralization of the effluent, the slag expansion remains below of the standard border ASTM C1260, and could be possible the use as an aggregate in the civil construction. The results showed in this work allows the conclusion that the use of the ladle furnace slag for neutralization of the AMD is a possible solution to improve the water quality in coal waste deposits.


drenagem ácida de minas slag escória de aciaria elétrica limestone effluent treatment tratamento de efluentes calcario acid mine drainage

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