United States Patent 0 ICC Stamina
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2,974,012 United States Patent 0 ICC stamina... 7,1961, 1 2 alic acid with a beryllium compound to form beryllium oxalate (BeC2O43H2O), which when pyrolyzed at a suit 2,974,012 able relatively low temperature, in the presence of air PREPARATION OF BERYLLIUM OXIDE OF or other gaseous oxidizing medium, will burn to form . HIGH PURITY highly active beryllia particles of small crystallite size, Raymond ‘Cooperstein and Gary R. Anderson, Cincin together with carbon dioxide, carbon monoxide and water, nati, Ohio, assiguors to the United States of America vapor. The commonly associated mineral impurities are as represented by the United States Atomic Energy separated from the beryllium values after conversion of Commission the beryllium to theoxalate and before the oxalate is 10 converted to beryllia. This puri?cation is accomplished No Drawing. Filed July 10, 1959, Ser. No. 826,384 simply and ef?ciently by leaching the beryllium oxalate 4 Claims. (Cl. 23-183) mass with water or a suitable organic solvent so as to' dissolve the beryllium oxalate while the insoluble im purities remain. The beryllium oxalate is then recovered The present invention relates to an improved process from the leaching solution by cooling and crystallization,. for making beryllium oxide of high purity. More spe and the now puri?ed oxalate salt is ?nally pyrolyzed to ci?cally, the invention relates to a process for preparing pure beryllia. beryllium oxide ‘which involves the conversion of beryl Oxalic acid is melted by heating the crystalline material lium compounds, such as the hydroxide, oxide, carbonate, to 120° C. Beryllium hydroxide is then reacted with the sulfate or nitrate to beryllium oxalate, and subsequent 20 molten oxalic acid by adding the hydroxide to the molten treatment of the beryllium oxalate so as to recover acid and stirring. The addition of the hydroxide results beryllium as the oxide free from the impurities normally in a vigorously'exothermic reaction so that the continued associated with commercialy obtainable beryllium oxide. application of heat to the reaction vessel is unnecessary. Numerous processes have in the past been suggested The suggested mole ratio of crude hydroxide to oxalic for the recovery of beryllium oxide from beryllium con 25 acid should be of the order of one to one. The molten taining ores. A notable defect in almost all of these. reaction mixture is allowed to cool and solidify, and the prior methods is that they require many time consuming solidi?ed cake is then heated in a suitable solvent to a - and expensive process steps. further drawback is that, temperature of between 50 to 95° C., and the hot mix~ even after these tedious process steps, large and objec ture is ?ltered._ Appropriate organic solvents, such as tionable amounts of impurities remain. Beryllium ox 30 dioxane, benzene, toluene and xylene, may be employed ide is generally prepared by the thermal decomposition for the dissolution step, but water is also suitable, and of beryllium sulfate or hydroxide. The sulfate is usually economic considerations may dictate its use. The resi made by a recrystallization technique While the hy due from the ?ltration step willbe composed of unreacted droxide is generally prepared by the_direct addition of‘ hydroxides and the more insoluble oxalates of the im an alkaline hydroxide solution to a solution of a beryl 35 purities associated with the initial beryllium-bearing, ma lium salt, such as beryllium sulfate. These beryllium terial. ' compounds, when calcined, form beryllium. oxide pow The hot ?ltrate vsolution is collected in a vesselcooled ders which almost always contain high concentrations of to less than 4° C., which results ‘in a rapid crystallization impurities. of beryllium oxalate. The beryllium is recovered by Beryllium metal produced from such contaminated 40 ?ltering, dried and stored for the pyrolysis operation.' beryllia will obviously contain most of the impurities The ?ltered leach solution, now depleted of the major associated with the beryllia, with consequent undesir portion of its beryllium-oxalate, is then reheated and re able results. Furthermore, if it is desired to fabricate cycled through the undissolved residue, and thecrystal ceramic bodies from the beryllium oxide by powder lization process is repeated. Thus, the berylliumhoxalate processing techniques and sintering, or by other ceramic 45 yield is increased while the necessity for use of excessive forming methods, then the use of impure beryllium oxide volumes of solvent is eliminated. The economic im is undesirable. This is particularly so if the? beryllia portance of this becomes more apparent when organic" ceramic pieces are intended for use as components of a ’ solvents are employed for the leaching treatment.‘ nuclear reactor, since both the nuclear properties and ‘The driedberyllium oxalate is then pyrolyzed at a the degree of shrinkage on sintering depend on the amount 50 temperature of between 800°‘C. and 1000“ C. for a and the nature of the impurities in the beryllium oxide period of between four and ten hours to ensure com powder. The purity of presently obtainable commercial plete conversion of the oxalate to the oxide. The rate berylliais found to vary quite markedly from lot to lot, of rise to the pyrolysis temperature (800°—l000° C.) with the result that ceramic bodies, formed under stand is between 100° and 300° C. per hour. ardized process conditions, vary a great deal as to nuclear 55 The following examples gives further details of how characteristics and sinterability. the process outlined above has been carried out. It is therefore an object of the present invention to provide a method for the production of beryllium oxide EXAMPLE I of extremely high purity. I ‘ 2268 parts by weight of oxalic acid was fused in a con It is a further object of the present invention to pro 60 tainer and to it was added 648 parts by weight of beryl vide an improved method for the production of beryl lium hydroxide. The beryllium oxalate mass thus pro lium oxide of high purity that eliminates many of the duced was leached with water. From the puri?ed beryl tedious and expensive process steps used in prior meth lium oxalate which was recrystallized from the leach ods. solution there was recovered a 60% yield of puri?ed It is yet another object of this invention to provide a 65 beryllium oxide after pyrolysis. method for producing beryllium oxide suitable for use in fabricating beryllia shapes by conventional ceramic EXAMPLE vII forming techniques. ' Y : 2268 parts by weight of oxalic acid was fused in a Various other objects and advantages of the inven container and to it was added 400 parts by weight of tion {will become apparent in theicourse of this descrip 70 beryllium oxide thatwas too impure for use in a nuclear ' tion.‘ ' . i reactor. The beryllium oxalate mass thus produced was The process consists essentially in reacting molten ox leached with water. From the-puri?ed beryllium ore‘ 2,974,012 3 4 - alate which was recrystallized from the leach solution to form beryllium oxide may be carried out with other there was obtained a 72% yield of puri?ed beryllium gaseous oxidizing agents, such as oxygen gas, mixtures oxide after pyrolysis. of oxygen and inert gases, and nitrogen dioxide gas. It will moreover be understood that the essential re EXAMPLE III actions may be carried out unded widely varying oper-. 630 parts by weight-of oxalic acid was fused in a" con ating conditions and with diverse types of apparatus, and tainer and to it was added 530 parts by weight of that various changes in the details of the procedure may BeSO4--4H2O. The beryllium oxalate mass thus pro be made Without departing from the invention, which is duced was leached with water. From the puri?ed beryl not to be deemed as limited otherwise than as indicated lium oxalate which was recrystallized from the leach by the scope of the appended claims. solution there was obtained a 67% yield of puri?ed We claim: beryllium oxide after pyrolysis. 1. A process for preparing beryllium oxide of high purity which comprises reacting a beryllium compound EXAMPLE IV selected from the group consisting of beryllium oxide, The procedure indicated in Example III was repeated, beryllium hydroxide, beryllium sulfate, beryllium car but the beryllium oxalate mass thus produced was leached bonate and beryllium nitrate with molten oxalic acid to with a 50-50 volume mixture of toluene and isopropyl produce beryllium oxalate, leaching the reaction mass alcohol instead of using water. From the puri?ed be with Water to recover beryllium oxalate from the asso rylium oxalate that. was recrystallized from the leach ciated impurities, ?ltering said leach solution to sepa solution there was obtained at 67% yield of puri?ed‘ 20 rate it from unreaeted beryllium compound and the more beryllium oxide after pyrolysis. insoluable oxalates, cooling the leach solution to crystal To indicate the vast improvement in beryllia purity lize the beryllium oxalate, recovering the beryllium ox made possible by the use of this method, Table I shows alate by ?ltration and subsequently converting the beryl the general level of impurities remaining in beryllia made lium oxalate to beryllium oxide by pyrolysis. by the process of this invention, and compares it with 25 2. A process for preparing beryllium oxide of high a speci?cation for maximum impurities in beryllium purity which comprises reacting beryllium oxide of low oxide, curerntly accepted for use in nuclear reactors. purity with molten oxalic acid to produce beryllium Table I oxalate, leaching the reaction mass with water at 50° to 95° C. to recover beryllium oxalate from the associated 30 Nuclear Impurities impurities, ?ltering the leach solution to separate impuri Reactor after Puri ties therefrom, cooling the leach solution to crystallize Speci?cations ?cation by the beryllium oxalate, recovering the beryllium oxalate Impurity Maximum Present Impurities, Process, by ?ltration, and subsequently converting the beryllium Parts per parts per million million oxalate to beryllium oxide by pyrolysis.