Engineering Research on the"Internal Circulation"of Ammonia-Carbon Resources in Rare Earth Hydrometallurgy and Separation Plants AITranslate

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Chinese Library Classification Number:TF845[冶金工程]

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This paper presented an introduction of ion-adsorption rare earth hydrometallurgy and separation process,analyzed the generation of ammonia nitrogen wastewater and CO₂ in the process,and proposed a resource recovery and utilization scheme for the"internal circulation"of ammonia-carbon resources.For the ammonia nitrogen wastewater,the stripping and distillation method is employed to recover NH₃·H₂O with a mass fraction of 20%.About 80%of this recovered NH₃·H₂O is formulated into 8 mol/L dilute ammonia water,which is reused in the saponification stage of the extraction process.About 20%NH₃·H₂O reacts with CO₂ produced in the calcination process,and is converted into 2 mol/L NH4HCO3 solution through the integrated ammonia capture and carbonation technology,which is then recycled to the precipi-tation process.This approach not only addresses the pollution issue caused by ammonia nitrogen wastewater,but also realizes the"internal circulation"of ammonia-carbon resources.Taking a 10000-ton rare earth hydrometallurgy and separation project designed by the author as an example,and basing on the calculation that 50%of the products are prepared by carbon precipitation process,the capture and absorp-tion of CO₂ in the flue gas generated during the calcination of rare earth carbonate can reduce the direct emissions of CO₂ by about 4830 t/a,which is equivalent to reducing the consumption of standard coal by about 1930 t/a.The production of per ton of rare earth products(calculated by REO)can reduce CO₂ di-rect emissions by an average of about 0.5 t,indicating a remarkable carbon emission reduction effect.