The reductive leaching of nickel laterite has attracted the interest of many researchers due to the enhanced kinetics of nickel and cobalt dissolution in the presence of acids and reducing agents during atmospheric, pressure, heap or bio leaching processes. Systematic studies on synthetic oxides and natural ores can shed light on the reaction mechanism and lead to investigations of beneficial reagents for further studies. This paper briefly reviews the literature and describes a comparative study of metal leaching from synthetic goethite spiked with nickel or cobalt and a limonitic laterite ore to rationalise the role of reducing agents in acid media. Results are discussed on the basis of the effect of speciation, surface chemical reactivity of oxides and heterogeneous kinetic models.Key words: Laterite, synthetic oxides, reductive leaching, kinetics, adsorption. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT

A 13-year-old female initially presented with scoliosis and pes CASE OF THE MONTHcavus. Initial examination revealed distal lower extremity weakness and sensory loss, as well as greater auricular nerve hypertrophy. There was a Section EditorsBabinski sign on the right. Nerve conduction velocities were consistent with a demyelinating neuropathy. Four years after initial presentation she developed A 13-year-old female initially presented with scoliosis in the extremities. General physical exam revealed scoliosis and pes cavus. Cranial nerves II-XII were and pes cavus. She was well until the age of 9 years, when she was found to have scoliosis during a school intact. Motor exam demonstrated normal strength, tone, and bulk in the upper extremities with the physical. She was first seen by an orthopedist and then by a neurology consultant. Her prenatal, perinaexception of equivocal weakness of the right abductor digiti minimi muscle. In the lower extremities, tal, and developmental history were unremarkable. School history indicated that she had repeated the hip flexor strength was 4ϩ/5, hamstrings were 5Ϫ/5, and quadriceps were 5/5. Peroneal and antesixth grade and was a below average student. Her past medical history was remarkable for cardiomegaly rior tibialis were 4ϩ/5 and extensor hallucis longus was 4ϩ/5 bilaterally. Sensory exam was intact to viand mitral valve prolapse, which was diagnosed at the age of 9 years when she developed difficulty bration and position sense. Pain and temperature sensation were mildly diminished in a stocking and breathing. She was seen by a cardiologist and her symptoms resolved without treatment.glove distribution bilaterally. Deep tendon reflexes were absent in both biceps, 1ϩ at the triceps and Family history was unremarkable for neuropathy or high arches. A maternal cousin did have scoliosis.brachioradialis bilaterally, 2ϩ at both patella, and 3ϩ at the ankles bilaterally. The plantar reflex was At the time of initial evaluation she was asymptomatic, with no complaint of weakness, numbness, or pain flexor on the left and there was a Babinski sign on the right. Both greater auricular nerves were hypertrophied. The patient remained neurologically stable and

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