Secondary zinc oxides

TREATMENT OF SECONDARY ZINC OXIDES FOR USE IN AN ELECTROLYTIC ZINC PLANT... 

Ammonia production from natural gas includes the following processes desulfurization of the feedstock primary and secondary reforming carbon monoxide shift conversion and removal of carbon dioxide, which can be used for urea manufacture methanation and ammonia synthesis. Catalysts used in the process may include cobalt, molybdenum, nickel, iron oxide/chromium oxide, copper oxide/zinc oxide, and iron. 

The American Zinc Association is a trade organization comprising primary and secondary producers of zinc metal, zinc oxide and zinc dust marketed in the United States. 

For the most part, the zinc materials recovered from secondary materials such as slab zinc, alloys, dusts, and compounds are comparable in quality to primary products. Zinc in brass is the principal form of secondary recovery, although secondary slab zinc has risen substantially over the last few years because it has been the principal zinc product of electric arc furnace (EAF) dust recycling. Impure zinc oxide products and zinc-bearing slags are sometimes used as trace element additives in fertilizers and animal feeds. About 10% of the domestic requirement for zinc is satisfied by old scrap. 

Secondary zinc Medium-grade zinc drosses, Zinc oxide fumes... 

Despite of 150-year s history of vulcanization process, it is impossible to consider that fundamental and applied researches in direction of vulcanization systems perfection are completed. For today one of the ways of rubbers properties improvement is the synthesis and application of the new chemicals-additives, including, vulcanization active, that is connected, first of all, with reduction of global stocks of zinc ores as basic raw material for reception of traditional activator - zinc oxide. Besides, modem increase of industrial potential and the accumulation of big quantity wastes derivate the problems of ecological character, which require the emergency decision. Therefore creation of resourcesaving technologies of the new compounds reception from products of secondary raw material processing has paramount importance. 

The heated secondary butyl alcohol (SBA) vapors are passed through a reactor containing zinc oxide catalyst at 750—1000°F at atmospheric pressure. The catalyst causes the hydrogen to pop off, forming MEK. The separation of the reactor effluent into MEK, water, hydrogen, and recycled SBA is about the same as Figure 17—2, The overall yield (the percent of SBA that ends up as MEK) is about 85-90%. 

The secondary flue dust from the converter, containing mainly zinc and lead, is leached with the ammoniacal raffinate solution from the Cu/Ni extraction. Lead is left in the residue. Finally, zinc carbonate is precipitated by addition of CO2 followed by thermal stripping of ammonia. The zinc carbonate is calcined to zinc oxide and ammonia is recycled to leaching. 

Raw Materials. In the early days, the raw materials were mainly zinc ores or concentrates for the direct process, or metal from zinc producers for the indirect process. Nowadays, zinc oxide manufacturers mainly use residues and secondary zinc. This fact, combined with the demand for chemical purity imposed by the users, means that processes have had to be modified and a number of purification techniques are used. 

This type of cell is another variant on the basic Leclanche cell. In this case, the electrolyte is a concentrated aqueous solution of potassium hydroxide (about 30%), partly converted to potassium zincate by the addition of zinc oxide. The main advantage of alkaline manganese cells over Leclanche cells is their relatively constant capacity over a wide range of current drains and under severe service schedule conditions. Another feature of this system is that it can be the basis of a secondary battery system. The cell reaction may be written formally as... 

Zinc electrodes for secondary silver-zinc batteries are made by one of three general methods the dry-powder process, the slurry-pasted process, or the electroformed process The active material used in any of the processes for the manufacture of electrodes is a finely divided zinc oxide powder, USP grade 12. 

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