Mark Kurt Weise

Oxygen Reactor for the Goethite-Zinc Leach Residue Process

In the goethite process for the recovery of zinc from neutral leach residue, iron in the hot acid leach solution is removed by an oxidation-hydrolysis step. Results are presented of an in-plant pilot test using oxygen, instead of air, in a new type of gas-liquid reactor. Under flow conditions providing residence times comparable to plant operations, ferrous iron oxidation and goethite precipitation were achieved in one reactor which were equivalent to that attained in three of the plant’s tanks. Goethite precipitate formed during the program was found to filter as good as conventional plant product and to contain less zinc and copper.

Hydrogen Supply Options and Issues

Methods of hydrogen gas production for hydrogenation are discussed: steam reforming of natural gas, electrolysis, by-product clean-up by PSA (pressure swing absorption) or scrubbing, and others. Hydrogen can be obtained from a customer-owned hydrogen plant or as a merchant product supplied by an industrial gas supplier. The merchant product can be delivered in trailers as gas, liquid-high (up to 2,200 psig), low pressure (up to 130 psig), or supplied over the fence from a pipeline or hydrogen generating plant. Several factors must be considered in selecting an optimum supply, including availability and cost of capital and of operating labor, use patterns, average demand, instantaneous demand, use pressure, growth projections, and purity requirements. Recent field test data have shown that increased hydrogen purity can improve the hydrogenation processes.