US1925920A - Process for the preparation of oxide of beryllium - Google Patents

Description

Patented Sept. 5, 1933 i STATES PROCESS FOR THE PREPARATIQN OF OXIDE 0F BERYLLlillJll/I Robert Andre Gadeau, St. Jean E16 Maurienne, France, assignor to Compagnie dc Prodnits Chimiques et Electrometallurgiqnes Alais Froges et Carnalue, Paris, France, a corporation of France No Drawing. Application November 5,

Serial No. 641,465, and in France November 28,

3 Claims.

The preparation of oxide of beryllium (BeO) starting from natural beryl as theinitial primary material has hitherto required complicated operations.

The. best method of preliminary treatment 01 the beryl being at present that by the attack with fluosilicate of sodium at a temperature of about 650-700 0., from which there is with.- drawn by solution the double fiuoride or" beryllium and sodium, it is this last mentioned compound which serves as the point of departure for the present process.

It is known that the double fluoride of beryllium and of sodium, which is thus withdrawn from the solution derived from the. attacking oi beryl by fluosilicate of sodium, is a complex body in which the beryllium is linked to the sodium in a particularly strong manner, so that ammonia, which precipitates practically the whole of the beryllium in the state of hydrated oxide in the solutions of other salts oi beryllium (chloride, sulphate, nitrate), does not even separate the beryllium from the sodium when they are linked together by fluorine.

Neither do the alkaline hydroxides (NaOH and KOH), added in solution to the double fluoride or" beryllium and sodium, efiect a Satis factory precipitation of the beryllium in the state of hydroxide.

Much less has it been possible to obtain the separation of the element beryllium, in the same aqueous solution of this double fluoride, by means of the alkali carbonates (NazCOs or K2003) added in solution.

The process according to the invention allows of obtaining the oxide of beryllium starting from a double fluoride of this metal and an alkali metal, by mixing intimately the double fluoride of beryllium and alkali metal with an alkali carbonate, calcining this mixture and afterwards washing it with hot water, in such a manner as to carry off the alkali metal from the double fluoride in the state of dissolved alkali fluoride and to convert the beryllium into the state of insoluble oxide, which is then sep arated out.

One begins for instance with the complex fluoride BeFzNaF in a dry and finely pulverized state, with which one mixes intimately one molecular part of NazCOs in powder form.

This mixture is afterwards calcined for a suiiicient length of time in a crucible or upon an appropriate hearth made of magnesia or beryllium oxide for example, after which the roasted It is naturally advantageous to employ an excess of alkali carbonate, ten percent for instance, above that which is indicated by stechiometric relation between BeFz and NazCOs which is the only one to be considered.

it may in fact happen in practice that the double fluoride contains a slight excess of fluoride of beryllium or conversely that it corresponds to the formula BeFaZNaF.

In all cases, a beryllium test allows of determining the suitable proportion of NazCOs to be employed, as has just been stated.

The temperature of calcination may cover a fairly wide range. It is good to operate between 525 and 550 C. One can go higher,- the practical limit being the point of fusion of the mixture, which it is advisable not to reach.

The duration of the calcining operation depending on the mass brought under treatment, whilst it is reduced by the temperature and by the frequency of stirring, the state of progress and the end of the reaction are recognised by examination of a sample taken during the course of the operation.

The oxide of beryllium (BeO) obtained in the form of paste, as above described, is an industrial product which may retain still some hundredths of fluoride or" sodium according to the care taken in the washing operation.

The yield of the process is remarkably high.

By drying this paste at a stove temperature (120439 0.), one can obtain the BeO in powder, retaining a little water, and which dissolves, especially when hot, slowly in nitric acid, (but) rapidly and completely in hydrochloric and hydrofluoric acids.

With this oxide, thus obtained in the simplest and the most economical manner, one can with advantage prepare the fluoride of beryllium and the oxyfluoride, which are the most important 7 compounds for the production of metallic beryllium and its alloys, as Well as of other salts derived therefrom.

The fluoride of sodium which passes out from which in practice makes this solutionrconsist solely of alkali fluoride and thus capable of being utilized such as it is.

This solution contains, except for working losses, the fluorine which was composed in the double fluoride of beryllium.

It is well understood that the invention is not limited to the method of carrying it out such.

as described, and that the process comprises a large number of variations, in particular the substitution of a double fluoride of beryllium and potassium forthe double fluoride of beryllium and sodium, the substitution of carbonatev of potassium for the carbonate of sodium in the mixture destined for calcination, the substitution, for one or other of these carbonates, of

an alkaline product capable of transforming 'it-' self into a basic compound by calcination, such as an alkali oxalate or acetate, etc. etc.

One can also effect with advantage the intimate mixture of the double fluoride and of the alkali carbonate intended for calcination, when starting from the solution of the double fluoride, by operating in the following manner:

In the solution of the double fluoride, there is first added a small dose of alkali carbonate which produces the precipitation of the heavy metals, which may exist in small quantities; this precipitate is separated and into the solution of double fluoride thus purified, there is added the complement of alkali carbonate which corresponds to thecontent in fluoride of beryllium, according to the relationrpreviously indicated. The whole solution is afterwards evapberyllium starting from a double fluoride of this metal and of an alkali metal, consisting in mixing intimately the double fluoride of beryllium and alkali metal with an alkali metal carbonate, calcining this mixture and washing it afterwards with hot water, thereby separating out the insoluble oxide of beryllium from the dissolved alkali metal fluoride.

2. A process for the preparation of oxide of beryllium from a solution of a double fluoride of beryllium and of an alkali metal, consisting in adding to said solution a small amount of an alkali metal carbonate adapted to precipitate the heavy metals present in said solution, separating the precipitate formed, adding the remaining necessary amount of the alkali metal carbonate to the purified solution of the double fluoride of beryllium and of an alkali metal, evaporating to dryness the whole solution, calcining the resulting mass, washing it afterwards with hot water, thereby separating out the insoluble oxide of beryllium from the dissolved alkali metal fluoride. V

3. In the process according to claim 1, the provision consisting in substituting, for the alkali metal carbonate, a compound adapted to transform itself during the calcination into an equivalent reagent relatively to the double fluoride.

ROBERT ANDRE GADEAU.