US2399178A - Process for the treatment of beryl - Google Patents

Description

April 30, i946.

M. H. FURLAUD I v 2,399,171@ PROCESS FOR THE TREATMENT OF BERYL In T n Filed Feb. 9, 1945 ,in S5 m ving reagents.

contact which obtains in fluidzing nely divided' Patented Apr. 30, 1946 UNITED STATES PATENT GFFICE 2,399,118 g PRocEss Fon THE TREATMENT oF BERYL Maxime H. Furlaud, Buenos Aires, Argentina Application February 9,1945, serial No, 577,121

19 Claims.

This invention relates to a process for the production of .beryllium compounds from minerals, Y

especially beryl. More particularly, the invention relates to the recovery of the beryllium values in such minerals by the selective uorination of the beryllium therein so that the separation of the beryllium values from the other constituents in the minerals is very materially simplified.

While there have beenmany investigators who have proposed various processes for decomposing or opening up beryl with several different uorine compounds, these processes have been bur.

Y the beryllium values in minerals.

Another principal object is to open up beryllium-containing minerals by a process involving a minimum consumption of chemical reagents.

A further object of my invention is to obtain from beryllium minerals beryllium compounds in" a high state of purity.

Still another object is to provide a commercially feasib-le process for treating beryllium minerals, either batchwise or continuously, as may appear best in each installation in the light of surrounding circumstances.

. Other objects of my invention will become apparent from the description which follows.

In accordance with my invention, berylliumcontaining minerals, e. g., beryl and phenacite, in nely divided form are treated with ammonium fluorides, viz: neutral ammonium fluoride (NH4F). I

and ammonium acid uoride (NH4F-HF) ,in vapor form under reaction conditions while maintaining the powdered mineral in a uidized state.

The use of the uidization technique in my process is of fundamental importance in achieving a new and surprising eiect, i. e., selective fluorination of beryllium in spite of the presence in the mineral of the other constituents, aluminum and silicon, which are reactive to fluorinat- I have found that the intimate beryllium minerals with a vaporized ammonium fluoride leads to rapid iluorination of the beryllium constituent throughout the entire mass of powdered mineral. Under these circumstances, it is possible to uorinate the beryllium present in the mineral substantially completely without signiicant attack of the other mineral constituents. This is all the more surprising since it is known that the rate of fluorination of beryllium oxide is only slightly greater than that of either alumina 'or silica The most common beryllium mineral is beryl which is represented by the formula,

3BeO A12O36S1O2 It has not heretofore been possible to takev advan. tage of this slight difference in reactivities in or. der to obtain an efficient separation of beryllium from the other constituents of the mineral. I'he secret of the success of the present invention appears to rest in presenting to every lluorine atom an opportunity of reacting with the preferred beryllium atom, an opportunity which was not given in prior processes.

0n the basis of this discovery, I control the selective fluorination of beryllium in my process by limiting the quantity of ammonium fluoride used up to that quantity which according to theory is just enough to react with all of the beryllium present in the mineral undergoing treat-l ment. In other words, the fluorinating reagent is consumed in stoichiometrical proportions with respect to beryllium. In batchwise operation, this is accomplished by passing vaporized ammonium fluoride through the fluidized batch of mineral until that quantity of reagent has reacted, which by prior analysis of the mineral for beryllium content and by calculation is just enough to convert all of the beryllium present to beryllium fluoride (BeF2)-.

In continuous operation the powdered mineral equivalent beryllium fluoride is continuously withdrawn.

Conditions must further be set ,so that the beryllium oxide in the mineral is substantially .other considerations; the latter byinherent requirements of the uidizing technique which will be 'described herenbelow and the former by the desired productive capacity of the reactor'as related to the vapor velocity. It develops, then, that the economical consumptions of the mineral and the ammonium fluoride are related to the depth of iiuidized bed which is established in the reactor and that the depth. must be chosento accommodate whichever of these demands requires the greater depth, that is, the greater exposure time to the opposite reactant.

The exposure time required by the reagent vapor is determined by performing experiments in which the selected ammonium fluoride is passed up through a bed of comminuted mineral in which the beryllium content has been nearly completely the rate of conversion of the mineral in each case. From these data the time to convert a particle of mineral under the average conditions prevailing ina iluidizing reactor may be calculated. 'Ihe actual exposure time of the mineral must be made considerably longer, say ten times longer, than the calculated average time to react -to avoid-short-circuiting of unreacted particlesfrom the inlet to the outlet of the reactor.

The calculated exposure time of the mineral is realized by regulating the ratio of the holdup of mineral in the reactor to the throughput of mineral per unit of time. For example, if a reactor holds 200 lbs. of mineral and the throughput is 200 lbs. per hour, the exposure time is 1 hour. The required holdup as related to the cross-section of the reactor, which has been fixed by deciding upon a desired productive capacity and vapor velocity, gives a second required depth of bed. This bed depth or that vcalculated from consideration of the consumption of the vaporized reagent, whichever is the greater of the two, is incorporated in the practical design of the iluidizing reactor.

Where the solid reacts with unusual rapidity,

it may be found that the inlet and outlet of the reactor may be located far enough apart to pre-` vent the flow of particles from the one opening to the other before they have reacted. This is desirable but a fortuitous and unusual occurrence.

In general, the linear velocity of the vapors is made to fall in the range of about 0.1 to 5.0 feet per second, preferably about 0.5 to 2.0 feet per second. With suitable precautions, somewhat higher or lower velocities may be employed. Such vapor velocities ensure good uldization of beryllium minerals which have been pulverized to particle sizes in theapproximate range of 100 1,110,400 mesh; preferably at least about 60%of 'ezcomminuted mineral should pass through a 200-mesh screen. Good fludization, in turn, is

- 'highly conducive to the selective uorination of the beryllium mineral as well as to the usual attributes of the technique, e. g., uniform temperatre throughout the reaction mass.

v .``.l1il'lfiile for the sake of clarity andv ease of presentation the foregoing description has stressed that in accordance with my invention,

apow A/ered mineral, e. g., beryl, is treated with a vaporized ammonium iluoride under such conditions that the beryllium content is substantially completely converted to beryllium fluoride. it is obvious to those skilled in the art that it is practical and indeed advisable to limit the fluorination to a maximum of about of the beryllium content of the mineral. Particularly i in large-scale operations, such a precaution leads to the recovery of high-purity beryllium fluoride; the small loss of thel beryllium content is a small price for avoiding the presence of impurities, such as aluminum fluoride, which tend to be formed when an eilort is made to drive the selective iluorination of beryllium to completeness with respect to beryllium. It should also be noted that while it has been stated that the fluorinating reagent is consumed in substantially stoichiometrical proportions with respect to the beryllium content, this is not to say that an excess of the reagent may not be passed through the reaction mass. In view of the fairly low' cost of the reagents contemplated in my invention, reasonable excesses of such reagents. which pass through the fiuidized mass without reaction can easily be permitted, especially iny systems in which the uorinating reagents are recovered and reused as shown hereinaften Suitable iluorination temperatures are well known in the technical literature but I generally operate my process at temperatures in the range of about 350 to 700 C., preferably about 450 to 600 C. Similarly, atmospheric pressure is commonly employed but in some cases ani elevated pressure may be favored.

A further aspect of my invention is the rapid conversion of beryllium fluoride to beryllium oxide, when Athe latter compound is preferred as the starting material in processes for the production of beryllium metal. My novel procedure for converting beryllium fluoride to beryllium oxide involves introducing the uoride, as either a solution or a solid, in a discrete form into a fluidized hot mass of particulate beryllium oxide. The mass of oxide is maintained in a iluidized state by the passage therethrough of steam supplied to the reactor as such or in the form of an aqueous solution of the beryllium fluoride which is charged to the reactor. A generous excess vof steam is advisable since it favors the conversion of beryllium fluoride to beryllium oxide. While atmospheric pressure is ordinarily used, a reduced pressure favors the conversion of the iiuo ride to the oxide. Suitable temperatures for this conversion lie in the range of about 300 to 700 C., preferably about 400 to 600 C.- Gas velocities and particle Sizes for this uidizing reactor are similar to those hereinabove-discussed for the iluorination reactor.

For more detailed description and further clarification of my invention, reference is had to the accompanying drawing which schematically yillustrates a preferred form of the process embodying continuous operation and several .other features of my invention.

In the drawing, an upright cylindrical reactor I has a tapered bottom 2 to which is attached beryllium fluoride. In the course of this reaction, the ammonium acid fluoride vapors are changed to ammonia and water vapor. These transformationsA are represented by the equation:

gases from these fire-tubes are vented to the at mosphere. Fluidization of the powdered .mass is conductive to a rapid transfer of heat from firetubes to the reaction mass as well as to a uniform reaction temperature. The reaction gases,

`gases so that they may be returned to reactor I.

Alternatively, the entrained solids are recovered from the gases -after the latter have been liquefied'in condenser Il. Discharging into condenser 8 from pipe 9 is a stream of hydrogen fluoride and water vapor. The mixed streams from pipes l 8 and 9 form an aqueous solution of ammonium acid fluoride through condensation. The fluoride solution flows through pipe I0 to evaporator II wherein water is expelled from the solution. The ammonium fluoride is then moved along line I2 to vaporizer Il whence the fluorinating reagent vapors return to reactor4 I to attack fresh mineral particles.

At a rate commensurate with the introduction of fluorinating reagent vapors, there `is admitted into reactor I fresh, powdered beryl. The pulverized beryl is charged into feed hopper I4 and from there the powder flows down standpipe I5 and through controlling slide valve I6 into reactor I. The, powder in this feed system is maintained in a free-flowing condition by passing a small quantity of fluidizing gas, such as air or steam, up through the powdered mass. A tube I1 for introducing such a gas is shown above slide valve I6.

Keeping pace Lith the addition of fresh mineral is the withdrawal of reacted mineral. reacted mineral particles ilow out of reactor I by wayoof standpipe I8 and slide valve I9 or equiv--l alent flow-regulating device, e. g., a star-feeder. A tube above valve I9 serves to introduce air or other convenient gas to prevent the packing of mineral powder within pipe I8.

mina and silica, which are not soluble in water.

The resultant slurry proceeds through pipe 22 to a suitable filter 23, such as an oliver rotary fllter,

The

which separates the insoluble material,- viz: alu- Ifeet above the bottom of reactor I.

reactor 26. To maintain a, desired reaction temperature, say 550 C., reactor 26 is enclosed by a furnace setting 28 in which a fuel like gas or oil is fired. Reactor 26 contains a fluidized mass of powdered beryllium oxide which is formed therein by the reaction between beryllium fluoride and I "steam, The steam may be introduced from am external source or it may be generated from the? aqueous solution of beryllium fluoridel entering reactor I by way of nozzle -2'I. Steam disappearing in reactor 26 because of reaction with beryl-` lium fluoride is replaced by hydrogen fluoride (HF) resulting from the same reaction. The reaction is represented by the equation:

Comminuted beryllium oxide which forms the' fluidized bed with pseudo-liquid'level 29 flows into standpipe 30 from which it is discharged at a rate equal to the rate of its formation Within reactor 26. The rate of withdrawal is controlled by slide valve 3l or its equivalent. A fluidizing tube 32 above valve 3I serves to introduce steam to prevent packing of the oxide powder within standpipe 30. 'I'he reaction gases of reactor 26, very largely hydrogen fluoride and excess steam, become separated from the fluidized bed of beryllium oxide at pseudo-liquid level 29. Entrained oxide particles may be removedv from the eluent gases by.inserting a suitable separator, like a cyclone or a Cottrell precipitator, in pipe 9 or they may be recovered from the condensate after the gases have passed through condenser. 8. As

hereinabove mentioned, the gases flowing through .pipes fl and 9 lntermingle within condenser B; re-

action occurs and an aqueous solution of ammonium acid fluoride emerges as condensate. The equation of the reactionbetween the gas streams of pipes I and 9 is:

As a specic example of the foregoing embodiment of my'process, an installation designed'to treat 200 lbs. of beryl per hour will be considered. In this case, reactor I has an inside diameter of 11 inches and pseudo-liquid level 6 is 20 A temperature of.600 C. is maintained in the fluidized mass of reactor I by three fire-tubes 5. The fire-tubes are 2 inches in diameter and consume about 0.3 gallon of oil per hour per tube. For fluorination, ammonium acid fluoride passes through vaporizer 4 and the resultant vapors at a temperature of 500 C. are admitted into reactor I at a rate such that the gas linear velocity up through reactor I is about 1 foot per second. Powdered beryl, about passing through a 200-mesh screen,

is fed to reactor I at the rate of '200 lbs. per hour,

eral are simple, conventional operations for which no numerical data are given here for the sake of brevity. Reactor 26 for converting beryllium fluoride to oxide is 14 inches in internal diameter.

The furnace setting 28 maintains the fluidized mass in reactor 26 at a temperature of 580 C. A 50% solution of beryllium fluoride is atomized into reactor 26 through nozzle 21 at a rate to establish a gas linear velocity of about l foot per second up through the reactor. Under the conditions maintained in reactor 26, the ne droplets of beryllium fluoride solution are flashed, to steam and residual particles of beryllium fluoride; in turn, the steam reacts with the beryllium oxide andV gaseous hydrogen iiuoride. Beryllium oxide powder is withdrawn from reactor 2B in the vicinity of its pseudo-liquid levelv 29 which is approximately 20 feet above .the bottom of reactor 26. The rate of withdrawal is about Q1 lbs. of beryllium oxide perR hour. Accordingly, it is obvious from the data of this example that with simple and inexpensive equipment my process is capable oi' continuously recovering from beryl beryllium oxide which is free of objectionable impurities; furthermore, the process involves a low expenditure of energy and no consumption of chemical reagent (other than accidental losses) since the ammonium fluoride usedis regenerated and recycled constantly.

While the process of my invention has been described hereinabove in considerable detail in terms of the preferred embodiment which includes regeneration and recycling of the uorinating reagent, conversion of an aqueous solution of beryllium 'fluoride to nely divided beryllium oxide, and continuous operation, it is understood that the process may be conducted batchwise, or beryllium fluoride may be fed to electrolytic cells to produce beryllium metal without asser/ claims, the term, beryllium nuoride, should be interpreted broadly as vmeaning beryllium fluoride as such or as the oxyfiuoride or as a mixture of the two.

It'is well to note that while with my fluidization process the conversion of beryllium uoride with steam to beryllium oxide can be driven to completeness, the withdrawal of incompletely reacted solids from the uidizing reactor is permissible. In such case, the solids are washed with water to dissolve away residual beryllium uoride and to leave behind substantially pure beryllium oxide as product. The wash water containing beryllium 'fluoride may be used to dissolve additional beryllium fluoride in solution tank 2| or it may be recycled directly to reactor 26.

What I claim is:

1. In the process of recovering beryllium from a beryllium-containing mineral, the step of selectively -uorinating said mineral in respect to beryllium by injecting an ammonium fluoride in vapor form into a iluidized mass of said mineral n maintained at reaction conditions.

going through the step of making beryllium oxide,

or any of several similar modifications may be followed, as evaporating beryllium fluoride to its oxyuoride.'

Similarly, beryllium fluoride produced by any method, e. g., by complete uorination of powdered beryl and by chemical separation of the mixed.fiuorides, may be converted to beryllium oxide by my iiuidizing process. The particulate beryllium oxide formed in my process is welll suited for charging into an arc furnace wherein the oxide, admixed with powdered carbon and powdered copper or copper oxide, is reduced to beryllium-copper alloy. Beryllium is commonly produced in the form of its copper alloy.

Briefly, then, my invention contemplates the selective iiuorination of the beryllium constituent in a mineral by i'luidization with ammonium fluoride vapors and the conversion of beryllium iiuoride to beryllium oxide by fluidization with steam, said operations being carried out jointly or separately, and batchwise or continuously.

Those skilled in the art will appreciate that my invention is amenable to many variations without departing from its spirit or intent. For example, fiuidizing reactors i and 26 have been depicted for so-called overiow or bottom withdrawal of powdered solids but overhead removal of solids by entrainment in the gases leaving a reactor is known and feasible. In the latter case, the solids would be recovered from the reaction gases by conventional separators like cyclonesand electrical precipitators.

The-iiuidizing technique employed in the process of my invention has found extensive application in the petroleum refining industry and is described in many articles in the literature, for instance Chemical and Metallurgical Engineering, June 1944, pages 94 et seq.

It is known that under certain conditions of evaporation and concentration of aqueous solutions of beryllium fluoride the fluoride changes to the oxyuoride. Where it is stated in the speciflcation or appended claims that beryllium fluoride is recovered from the fluorinated mineralv or is treatedwith steam to yield the oxide, those skilled in the art will appreciate that the beryllium fluoride may be partly or wholly in the form of beryllium oxyfiuoride.

Accordingly, in the 2. The process of claim 1 wherein the beryllium-containing mineral is beryl.

3. The process of claim 1 wherein the reaction conditions include a temperature in the range of about 350 to 700 C.Av

4. The `process of selectively uorinating a beryllium-containing mineral in respect to beryllium, which comprises exposing said mineral in finely divided form to vapors of an ammonium fluoride at reaction conditions and for a period of time not exceeding that which is just sufficient to convert the beryllium content of said mineral to beryllium fluoride, while maintaining said finely divided mineral in a fluidized state.

V5. The process of claim 4 wherein the reaction conditions inc lude a temperature in the range of about 350 to 700 C.- y

6. The process of claim 4 wherein the exposure period is suillcient to convert only about 95% of the beryllium content of the mineral.

'7. The continuous process for recovering the beryllium content of beryl, which comprises simultaneously introducing powdered beryl' and vaporized ammonium acid fluoride into a reactor in which a fiuidized mass of beryl is established and maintained at reaction conditions, and withdrawing reaction gases and solids therefrom, the

- withdrawal of said reaction solids .being controlled so that the amount of iluorination does not exceed-that which is just sufficient to convert the beryllium content of said powdered beryl to beryllium fluoride.

8. The processof claim 7 wherein the reaction gases flowing up through the iluidized mass have a linear velocity in the range of about 0.5 to 2.0 feet per second.

9. The process of claim 7 wherein the reaction conditions include a temperature in the range Of about 450 to 600 C.

10. The process of producing beryllium oxide from iinely divided beryllium-containing mineral, which comprises selectively iluorinatingsaid mineral in respect to beryllium by passing an ammonium fluoride in vapor form through a fluidized mass of said mineral maintained at reaction conditions, separating the resultant beryllium iluoride from the thus uorinated mineral, and converting said -beryllium fluoride to beryllium oxide by treating said beryllium iiuoride in comminuted formwith steam under reacting and fluidizing conditions.

11. The process of claim 10 wherein the steps ialns reactor, maintaining iluidization in said reof selectively iiuorinating the beryllium-containing mineral and of converting beryllium fluoride to beryllium oxide are conducted continuously and the eilluent gases from said steps are combined to regenerate ammonium iluorlde for recycling to the iluorinating step.

12. The continuous process of producing beryllium oxide from nely divided beryl, which comprises selectively iluorinating said beryl in respect to beryllium by passing vaporized ammonium acid iuoride at a linear velocity in the range of about 0.5 to 2.0 feet per second through a fluidized mass of said beryl maintained at a temperature in the range oi.' about 350 to 700 C., separating the resultant beryllium fluoride from the thus fluorinated beryl. and converting said beryllium uoride to beryllium oxide by treating said beryllium iluoride in comminuted i'orm with steam in a iuidizing reactor through which the reaction gases ilow at a linear velocity in the range of about 0.5 to 2.0 feet lper second and in which thetemperature is in the range of about 300to700 C.

13. The process of claim 12 wherein the ilnely divided beryl is of such particle size that at least 25 60% of the material passes through a 200-mesh screen and the selective iluorination is controlled so as to react not more than about 95% of the beryllium content of said beryl.

14. The process of converting beryllium 11u0- ride into beryllium oxide, which comprises introducing said iluoride yin. discrete form into a iluidactor while reacting steam with said fluoride. and withdrawing the gaseous and solid products of reaction.

15. The process of claim 14 wherein the reaction between steam and beryllium iiuoride is conducted at a temperature in the range of about 300 to 700 C. v

16. The process of claim 14 wherein iluidization is maintained by permitting the reaction gases to iiow up through the reactor at a linear velocity in the range of about 0.5 to 2.0 feet per second.

17. The process of converting beryllium iluoride to beryllium oxide, which comprises establishing a i'luidized bed of comminuted beryllium oxide, maintaining said bed at a temperature in the range of about 300 to 700 C.,atomizing an aqueous solution of beryllium fluoride into said bed, and withdrawing reaction gases and ccmminuted beryllium oxide from said bed at a rate commensurate with the rate of formation of beryllium oxide through atomization of said solution into said bed.

18. The process of claim 17 wherein the comminuted beryllium oxide is of such particle size that at least 60% of the material passes through a ZOO-mesh screen.

19. 'I'he process of claim 17 wherein the aque- 30 ous solution of beryllium iuorlde is of about 50% concentration. MAXIME H. FURLAUD.

Images