ABSTRACT:

The leaching behaviour and mechanism of metals in deep-sea manganese nodules mined from the Clarion-Clipperton" s preferred area with hydrochloric acid were studied. The effect of acid concentration, reaction temperature, reaction time, agitation speed and particle size on the leaching rate of metal is discussed based on the model and the experimental results. Nickel extraction was found to be very dependent on temperature and independent of the acid concentration. Copper appears to be chemically adsorbed on the surfaces of iron and manganese oxides, not within their lattices. The dissolution of copper and nickel was found to be controlled by volume reaction model.

INTRODUCTION

Manganese nodules which are comprised mainly of oxides of manganese and iron are now widely recognized as potential resources of various metals such as cobalt, nickel and copper. The physico-chemical properties of nodules are an essential aspect in the extraction process. The nodules are filled with extremely fine pores of the order of 100Å diameter which results in porosities of near 50% by volume and surface areas of about 200m1/g. porous matrix of nodules has resulted in the development of many metallurgical processes. The processing techniques for nodules are mostly adaptation of conventional techniques and can be classified into smelling-leaching. roasting-leaching and direct-leaching processes. Most of the processing methods developed so far have been based on hydrometallurgical treatment, such as acid leaching and ammoniacal leaching under reducing conditions, due to the high energy cost of pyrometallurgical processing and the complexity of nodules. The principal purpose of the present study is to examine the leaching behaviour and mechanism of copper and nickel in deep-sea manganese nodules mined from the Clarion-Clipperton" s preferred area with hydrochloric acid. The leaching behaviour of copper and nickel from manganese nodules has been studied as a function of various experimental conditions.

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