Practical Basic Research On Application Of Jet Reaction In The Preparation Of Rare Earth Compounds

There are several disadvantages such as large amounts of ammonia waste water/oxalic acid wastewatern and roasting exhaust emissions,high energy consumption,serious pollution and so on during the traditional process using oxalic acid or ammonium bicarbonate to precipitate rare earth chloride solution to obtain precipitation,and then calcine precipitation to produce Rare Earth oxides.Our research group inventated the new method of using rare earth chloride solution to produce directly the rare earth oxide powders through jet pyrolysis.The rare earth chloride solution will be carried into the jet reactor by the high temperature gas and then obtain the rare earth oxides through high-temperature pyrolysis reaction to recycle the exhaust of HCl.This paper studied systematically the thermodynamics laws on the pyrolysis process of rare earth chloride solution and the optimization conditions of the pyrolysis process,and explored the feasibility of preparing anhydrous rare earth chlorides drying rare earth chloride solution with the jet reaction.The main conclusions are as follows:(1)After analyzing and calculating the thermodynamics laws of jet pyrolysis of 16 kinds of Rare Earth chloride solution except promethium,the predominance area diagrams were obtained.The results show that:the stable pyrolysis phases of CeCl3 solution,PrCl3 solution and TbCl3 solution are respectively CeO2,PrO2 and Tb7O12,and oxygen will promote the reactions occuration during the pyrolysis process.The REOCl byproducts can generate the during the low temperature pyrolysis process of LaCl3 solution,NdCl3 solution and GdCl3 solution,so the key step is the suppression of generating REOCl preparating rare earth oxides.The stable pyrolysis product phases of Rare earth chloride solution of samarium,europium,dysprosium,holmium,erbium,thulium,ytterbium,lutetium,scandium,yttrium are all the RE2O3.(2)The pyrolysis experiment results show:the jet pyrolysis production of LaCl3 solution is main La2O3 which contains a little LaOCl at 900?;the jet pyrolysis production of NdCl3 solution is main Nd2O3 which contains a little NdOCl at 800?;and the jet pyrolysis production of DyCl3 solution is main Dy2O3 which contains a little DyOCl at 500?.Comparing with the static pyrolysis results in the muffle furnace,the low temperature was achieved through the jet pyrolysis process,and the formation of the REOCl byproduct phase was effectively inhibitted.The jet pyrolysis production of CeCl3 solution is pure CeO2 phase.Comparing with the results of static pyrolysis in muffle furnace,the pyrolysis of CeCl3 solution can react through jet pyrolysis method at low temperature,and chlorine content in pyrolysis products can reduce from 3.249%of static pyrolysis to 0.2%.(3)The material balance and energy balance on spray drying process of lanthanum chloride solution were calculated,and the related operation parameters of the jet drying process were determined.The results of jet dehydration experiment showed that it is feasible preparing anhydrous LaCl3 through the method of jet dehydration.