CN1146676C - Prepn. of yttrium-rich RE-Al intermediate alloy - Google Patents

Abstract

The present invention belongs to a preparation method of yttrium-rich rare earth aluminium intermediate alloy. The method solves a technological problem that the yttrium-rich rare earth is difficult to diffuse the inner part of a liquid cathode to form furnace accretion; in a cylinder graphitic cell in which an internal heating probe and an argon cracker pipe are arranged, the crucible area of the cathode is 707cm<2>, and the maximum electrolytic current of a furnace is 2000 A; the furnace is started to melt electrolyte; liquid aluminium of 4kg is thrown at every time; furnace temperature is controlled within the range of 720 to 860 DEGC; the current density of the cathode is from 0.7 A/cm<2> to 2.6 A/cm<2>; the intake quantity of bubbling argon is from 2 to 8 ml/min; the electrolytic period of each condition is 7 days. After each period, the alloy of each furnace is mixed and remelted; the average current efficiency of the cathode is from 67 to 83% through calculation; the directly-recovering rate of the rear earth is from 87 to 95%; the furnace accretion does not exist when the alloy is remelted.

Description

Yttrium-rich RE aluminium intermediate alloy preparation method

Technical field: the preparation method who the invention belongs to the yttrium-rich RE aluminium intermediate alloy.

Background technology: rich yttrium mixed rare earth-aluminium intermediate alloy has a wide range of applications at industrial production Al-Zr-Ym (Ym represents rich yttrium mixed rare earth) alumite lead and fields such as Fe-Cr-Al-Ym high-temperature oxidation resistant alloy and aluminum, zirconium, yttrium ternary co-osmosized coating, and Japan special permission communique 48-99016 and Chinese patent 87106845 disclose at LiF-BaF-YmF respectively ₃And YF3-LiF-BaF ₂Fluoride system in constantly add Ym ₂O ₃And Y ₂O ₃, the technical scale fused salt electrolysis prepares the method for Ym-Al and Y-Mg master alloy, but the fluoride system electrolysis exists three known big shortcomings, electrolysis temperature height, big and electrolytic efficiency is on the low side to equipment corrosion; Can overcome above-mentioned shortcoming with chloride system, the slag effect is far below fluorochemical but muriate disappears, low temperature spreads yttrium in the liquid aluminium negative electrode slower, the yttrium that in time is not diffused into liquid cathode inside forms a large amount of dendrite---rare earth-Al intermetallic on its surface, dendrite is rolled onto anode by ionogen and changes slag into during big electric current, the integrated accretion of little electric current dendrite accumulating poly---block rare earth-Al intermetallic, and be encapsulated into liquid cathode inside, the difficult control of electric current when this causes electrolysis, every stove alloy effective constituent yttrium is inhomogeneous when coming out of the stove, the master alloy that particularly contains accretion, because intermetallic compound fusing point height, good stability, even high temperature mixing long period again, it still is difficult to diffusion evenly, this finally stays hidden danger to mixing for product when using, artificial improve temperature and increase fluoride additive concentration, can eliminate this hidden danger, but this and chloride system electrolysis temperature are low and corrode little advantage and run counter to; Chinese patent 97103269 discloses the chloride system fused salt electrolysis and has produced cell-grade lanthanum rich norium alloy, Chinese patent 00267763.6 discloses the patented technology of fused-salt bath, the flexible temperature can to a certain degree solve the drawback that chloride system exists, but, electrolysis temperature, current density, each component relative concentration etc. in the ionogen, all electrolysis is produced material impact, only depend on attemperation thoroughly to deal with problems.

The purpose of this invention is to provide a kind of yttrium-rich RE aluminium intermediate alloy preparation method, a kind of method of eliminating the integrated block rare earth-Al intermetallic of dendrite accumulating poly in the electrolytic process particularly is provided.This method produces that every stove alloy effective constituent yttrium is even, and the dystectic rare earth-Al intermetallic of bulk is few, and slag making is also few, and current efficiency and yield are higher.

Realize that the present invention of foregoing invention purpose takes to promote to greatest extent yttrium-rich RE to the inner diffusion in time of liquid cathode, make the liquid cathode surface form the dendrite probability and be reduced to minimum measure, on the close liquid cathode surface of internal heating probe, reduce liquid aluminium negative electrode viscosity, negative electrode top layer viscosity particularly adds the low amount of fluorinated sodium additives and makes and remain unsalted surface in the catholyte; Blast rare gas element to negative electrode inside, it is inner so that diffusion in time that the bubble of going out from negative electrode inside in time is embedded into negative electrode with the dendrite crystal seed that generates; Add rare earth chloride, Repone K, sodium chloride electrolysis matter component and form relatively that to be adjusted to viscosity minimum, keep electrolyte flow good.

The present invention is that 99.5% Al and 99% rich yttrium mixed rare earth are raw material with commercially available purity, and wherein single rare earth accounts for the weight percent of mishmetal total amount and is: Y56.22%, la2.15%, Ce0.52%, Pr1.20%, Nd4.16%, Sm3.59%, Eu＜0.5%, Gd6.03%, Tb1.74%, Dy9.68%, Ho2.53%, Er5.21%, Tm1.05%, Yb4.23%, Lu1.04%; With ammonium chloride rare earth is made anhydrous chlorides of rase earth elements, ionogen as following weight percent: x%NaF, y%YmCl ₃, (100-x-y) %KCl-NaCl, both weight ratios of KCl-NaCl are 1: 1, Ym is a yttrium mixed rare earth, x=0.5-2.0, y=20-55, in internal heating probe and the cylindrical graphitic cell of argon gas bubbling pipe are installed, cathode crucible area 707cm ², maximum Faradaic current 2000 peaces of stove play stove with electrolyte melting, drop into the 4Kg liquid aluminium at every turn, and Control for Kiln Temperature is in 720 ℃ of-860 ℃ of warm area scopes, and cathode current density is 0.7A/cm ²-2.6A/cm ², bubbling argon gas air input 2-8ml/min, each condition electrolysing period is 7 days.Each all after date is with each stove alloy mixing remelting, and calculating average cathode efficiency is 67-83%, straight yield of rare earth 87-95%, analyzing Ym-Al master alloy total amount of rare earth is 6-14%, it is 53-60% that yttrium accounts for the total amount of rare earth ratio, departs from raw material and forms 3-4%, does not have accretion to exist during remelting.

The present invention fully adopts the various conditions of yttrium-rich RE to the liquid cathode internal divergence that are beneficial to, solved the medium-term and long-term accretion difficult problem that exists of chloride system electrolysis, accretion is eliminated at rudiment and growth phase, finally removed a hidden danger to mixing when using for product, it is low heavily to melt cost; Each element of master alloy middle-weight rare earths is relatively formed and is departed from raw material to form degree little, and product stability is good, and electrolysis is stable, and straight yield of rare earth and electricity are imitated higher.

Embodiment is as follows:

Embodiment 1:

Rare earth oxide is formed (wt%): Y56.22%, la2.15%, Ce0.52%, Pr1.20%, Nd4.16%, Sm3.59%, Eu＜0.5%, Gd6.03%, Tb 1.74%, Dy9.68%, Ho2.53%, Er5.21%, Tm1.05%, Yb4.23%, Lu1.04% relatively; With ammonium chloride the chlorination of rich yttrium mixed rare earth oxide compound is become anhydrous chlorides of rase earth elements, in internal heating probe and the cylindrical graphitic cell of argon gas bubbling pipe are installed, will consist of 0.5%NaF--20%YmCl behind the stove ₃-79.5%KCl-NaCl, both weight ratios of KCl-NaCl are 1: 1, are heated to thawing, with 720 ℃ of internal heating probe constant temperature, drop into 99.5% liquid aluminium 4Kg, cathode area 707cm ²,, keep cathode current density 0.7A/cm with 495 ampere electric current electrolysis ²Bubbling argon gas air input 2ml/min, continuous electrolysis each piece alloy remelting of will coming out of the stove after 7 days, do not find accretion, analyze again that alloy is 9%Ym-91%Al behind the consolute, wherein effectively yttrium content (Y/Ym) is 60%, depart from raw material and form 4%, average cathode efficiency is 83%, straight yield of rare earth 95%

Embodiment 2:

All the other are with embodiment 1, and ionogen consists of 2.0%NaF--55%YmCl ₃-43%KCl-NaCl, 860 ℃ of constant temperature with 1200 ampere electric current electrolysis, keep cathode current density 1.7A/cm ², bubbling argon gas air input 8ml/min, alloy is 14%Ym-86%Al behind the consolute, and effectively yttrium content (Y/Ym) is 53%, departs from raw material and forms 3%, and average cathode efficiency is 67%, straight yield of rare earth 87%.

Embodiment 3:

All the other are with embodiment 1, and ionogen consists of 1.5%NaF--35%YmCl ₃-63.5%KCl-NaCl, 780 ℃ of constant temperature with 1838 ampere electric current electrolysis, keep cathode current density 2.6A/cm ², bubbling argon gas air input 6ml/min, alloy is 11%Ym-89%Al behind the consolute, and effectively yttrium content (Y/Ym) is 57%, departs from raw material and forms 1%, and average cathode efficiency is 75%, straight yield of rare earth 89%.

Embodiment 4:

All the other are with embodiment 1, and ionogen consists of 1%NaF--30%YmCl ₃-69%KCl-NaCl, 800 ℃ of constant temperature with 990 ampere electric current electrolysis, keep cathode current density 1.4A/cm ², bubbling argon gas air input 4ml/min, alloy is 6%Ym-94%Al behind the consolute, and effectively yttrium content (Y/Ym) is 56%, forms near raw material, and average cathode efficiency is 78%, straight yield of rare earth 92%.

Claims (1)

1. yttrium-rich RE aluminium intermediate alloy preparation method, with commercially available purity is that 99.5% Al and 99% rich yttrium mixed rare earth are raw material, and wherein single rare earth accounts for the weight percent of mishmetal total amount and is: Y56.22%, la2.15%, Ce0.52%, Pr1.20%, Nd4.16%, Sm3.59%, Eu＜0.5%, Gd6.03%, Tb1.74%, Dy9.68%, Ho2.53%, Er5.21%, Tm1.05%, Yb4.23%, Lu1.04%; With ammonium chloride rare earth is made anhydrous chlorides of rase earth elements, it is characterized in that ionogen as following weight percent: x%NaF, y%YmCl ₃, (100-x-y) %KCl-NaCl, both weight ratios of KCl-NaCl are 1: 1, Ym is a yttrium mixed rare earth, x=0.5-2.0, y=20-55, in internal heating probe and the cylindrical graphitic cell of argon gas bubbling pipe are installed, cathode crucible area 707cm ², maximum Faradaic current 2000 peaces of stove play stove with electrolyte melting, drop into the 4Kg liquid aluminium at every turn, and Control for Kiln Temperature is in 720 ℃ of-860 ℃ of warm area scopes, and cathode current density is 0.7A/cm ²-2.6A/cm ², bubbling argon gas air input 2-8ml/min, each condition electrolysing period is 7 days, each all after date is with each stove alloy mixing remelting, and cathode efficiency is 67-83%, straight yield of rare earth 87-95%, Ym-Al master alloy total amount of rare earth is 6-14%, and it is 53-60% that yttrium accounts for the total amount of rare earth ratio.