Leaching manganese

Freshly extended basalt heats the sea-water and, as laboratory tests have revealed, the heated saline water can readily leach manganese from the basalt ... 

HydrometaHurgical recovery of copper from manganese sea nodules has been studied extensively, as have combined PyrometaHurgical—hydrometaHurgical processes. Advancements in hydrometaHurgy and leaching technology are described in References 35—37. 

The cake is leached with water in order to dissolve tantalum and niobium (and other related compounds) in the form of fluoride salts of ammonium. Ammonium fluoroferrate and fluoromanganate are unstable in aqueous solutions of low acidity. It is assumed that iron and manganese will form precipitates of insoluble fluorides or oxyfluorides that can be separated from the solution by filtration. 

Nevertheless, manganese nodules can, at best, be considered to be similar to land-based nickel laterites, and consequently most of the processing techniques that have been tried are similar to those used on lateritic ores. Reduction roasting followed by ammonia leaching, as in the Nicaro process, and high-temperature sulfuric acid leaching, as in the Moa Bay operation, have been extensively tried to process nodules. 

Jana, R. K. Pandey, B. D. Premchand Ammoniacal leaching of roast reduced deep-sea manganese nodules. 

Leaching and desorption of As from its associated mineral surfaces such as iron, aluminum and manganese oxides under the influence of the aquifer complex geochemistry, largely take part in its transport from sediment to aquifer pore-water. Adsorption has widely been considered as the retardation of As transport (Smedley 2003). 

It occurs in seawater where some species of seaweed and kelp accumulate the element in their cells. It is also recovered from deep brine wells found in Chile, Indonesia, Japan, and Michigan, Arkansas, and Oklahoma in the United States. The iodine is recovered from cremated ashes of seaweed. The ashes are leached with water to remove the unwanted salts. Finally, manganese dioxide (MnO ) is added to oxidize the iodine ions (1 ) to produce elemental diatomic iodine (y. The following reaction takes place 41 " + MnO —> Mnl + I. + 202-... 

The partial leach protocol used a 2-h leach, using 40 ml of 0.25 M hydroxylamine hydrochloride in 0.1 M HCI at 60°C, on 1 g of the <63- j.m fraction (Cameron et al. 2004). This hydroxylamine leach is designed to dissolve secondary iron and manganese oxides. This relatively aggressive leach protocol will also dissolve phosphatic, calcareous and amorphous clay components, and will likely desorb any ions weakly bonded to other components. 

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