Study On The High Temperature Action Products Of Praseodymium Iron Arsenic

At present,the arsenic in steel is controlled and eliminated by ingredient dilution method,gasification arsenic removal method,and arsenic removal method of iron and steel industry in the industry,but there are problems such as high production costs and serious environmental pollution.Lanthanides with strong chemical activity in molten steel can form high melting point compounds with arsenic.China is rich in rare earth resources,and carrying out rare earth modification treatment of residual elements has a unique advantage.Through the interaction of rare earth and arsenic,the occurrence way of arsenic in steel is changed.This paper mainly studies the effects of different experimental conditions on the types of praseodymium-iron-arsenic ternary compounds,the diffusion of elements,and the stability of the compounds,and studies the interaction rules and mechanisms of rare earth praseodymium and arsenic,and controls the interaction conditions.The main conclusions are as follows:The compounds PrAs,Fe₂As,Fe₁₇Pr₂ and arsenic-containing?-Fe are the main high-temperature reaction products of the praseodymium-iron-arsenic ternary system.The relative content of all compounds in the sample at the temperature of 950?increased first and then decreased with the increased of the praseodymium-arsenic atomic ratio.In the sample at the temperature of 900?,with the increased of the praseodymium-arsenic atomic ratio,the relative content of the compound PrAs gradually decreased,and the relative content of the compound Fe₂As first increased and then decreased.The diffusion distance of the sample infiltration edge area showed a trend of first increasing and then decreasing.With the increased of the constant temperature,the relative content of the compound Fe₂As gradually decreased,and the relative content of the compound PrAs first increased and then decreased in the sample with the praseodymium-arsenic atomic ratio of 1:3.5.The relative content of the compound PrAs gradually increased in the sample with a praseodymium-arsenic atomic ratio of 1:4.The diffusion distance of the sample infiltration edge area showed a trend of first decreasing and then increasing.With the increase of the constant temperature time,the relative content of the compound PrAs and the compound Fe₂As both decreased first and then increased.The high temperature reaction product of the praseodymium-iron-arsenic ternary system had the best stability in a dry atmosphere and the worst stability in a common pipeline water environment.The higher the temperature,the greater the self-diffusion coefficient of iron atoms.When the temperature increased from 1173K to 1273K,the self-diffusion coefficient of iron atoms increased from D_Fe=3.39×10^-6m²/s to D_Fe=4.26×10^-6m²/s.The shortest diffusion distance of iron atoms into the industrial pure iron cylinder is 3.68mm,and the longest is 29.19mm.According to the Pualing empirical formula,Pr atoms and As atoms preferentially combine to form intermetallic compounds,followed by Pr atoms and Fe atoms,and finally Fe atoms and As atoms.The concentration of rare earth metal praseodymium in the iron matrix showed a trend of first decreasing and then increasing with the increased of the diffusion depth.The formation of the compound PrAs hindered the diffusion of arsenic in the iron matrix.The chemical process of compound formation in the system is mainly[Pr]+[As]?[PrAs]to form the compound PrAs and 2[Fe]+[As]?Fe₂As to form the compound Fe₂As.