Development Status of Wastewater Treatment Technology in Rare Earth Hydrometallurgy

There are many kinds of RE ores in China,and each treatment process is also complicated.In the REO production process,the sewage is about 60-100/t-REO,including acidic or alkalescent wastewater with fluoride,and ammonia-nitrogen wastewater.The latter are mainly produced in RE extraction and carbonate precipitation process,and which exceeded more than dozens of times and even several hundreds times of the emission standard and caused servere environmental problems.Various kinds of wastewater treatment methods were investigated and reviewed,based on the wastewater character to provide scientific and reasonable suggestion.Ammonia was replaced by non-saponificated technique or Ca-saponificated technique in solvent extraction separation process and Na2CO3 in carbonate precipitation process.Acidic fluoride wastewater were treated by purified recycle process to make sulfuric acid and fluoride salts.High content Ammonia nitrogen could be recovered by evaporation and that low content could be recovered by film or chloride method etc.to achieve the discharge standards.