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Home , Ammonium bifluoride, Beryllium carbonate, Beryllium chloride, Beryllium hydroxide, Beryllium oxalate, Beryllium oxide

THE PRODUCTION METALLURGY OF BERYLLIUM SALTS

Herbert Greenewald, Jr.

Submitted in Partial Fulfillment of the Require ment for the Degree of Bachelor of Science From the

Massachusetts Institute of Technology

1943

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Professor in Charge of Researc1( ~ .i-~ ~~~~-~~---~~9acted ✓ Table of Contents

Page Chapter I Introduction 1 Chapter II Proposed Methods for the Extraction of Beryllium Salts from Beryllium Minerals 3 Chapter III Analytical Procedure 15 Chapter LV Description of the Beryl Used

and of the Fluxes 18 Chapter V Description of Experimental Results 20 Chapter VI Theory of Processes Proposed in this Thesis 28 Chapter VII

Conclusions 32 Chapter VI

Appendix 35. 1.

CHAPTER I Introduction.

Beryllium is a metal whose main use is in alloys at present, but which imparts to those alboys exceptional properties. Pure beryllium has some excellent properties of its own which might be taken advantage of if pure beryllium was available at low cost. All uses of beryllium have been greatly restricted because of the bigh cost of production. Part, at least, of this high cost can be attributed to the methods used today to obtain pure beryllium salts from the chief ore, beryl. It is the purpose of this thesis to determine the possibility of using a chloride process for the production of pure beryllium oxide without recoumse to expensive reagentssuch as, chlorine. Since the cheapest sources of chlorides are sodium and calcium chlorides, it was decided to use these chlorides and beryl as the starting point for the possible production of pure beryllium oxide. This has been done and the results are encouraging.

This work done for this thesis is of a preliminary nature only because of the short time available. A possible process or processes will be roughly sketched out by this work but the re- finement of these processes will have to be left to future investigators. Before the proposed processes can be used commercially, if they ever are, there is much that moat be done in overcoming some of the drawbacks to the process. Proper equipment must be designed and corrosion resistant structures must be developed. Temperatures, furnace atmospheres, and other such technical prob- lems must be solved and optimum conditions deter- mined, or else the processes here proposed must te abandoned. Even after pure beryllium oxide can be produced cheaply the problem of a good method for the reduction of beryllium oxide must be worked. out. This is completely beyodd the scope of this thesis, however.

Since beryl contains aluminum as well as beryllium it has been dicided to recover the aluminum from the ore as well as the beryllium. The method used here to recover the aluminum oxide might indicate a possible method for the recovery of aluminum oxide from other silicate ores. This possibility will be shortly considered in the conclusion to this report. A review of previous processes for the recovery of beryllium has been included in this report to show what has been tried and what has failed commercialJ$. CHPTER II Proposed Methods for the Extraction of Beryllium Salts from Beryllium Minerals. Since beryl is the most common source of beryllium, it has been used as the ore in most of the processes listed below. The proposed processes will be listed in chronological order and at the end of the list will be placed a description of the processes now used commercially for the production of beryllium. 1. Method proposed by Vauquelin in 1798.

The beryl is crushed, heated, pulverized, mixed with three times its weight of potassium hydroxide, and fused. The fused mass is dissolved in water and the silica is filtered off. The filtrate is treated with excess potassium hydroxide and boiled. The precipitate contains all of the beryllium and some of the aluminum. The aluminum is crystallized out as potassium alum and the beryllium dissolved in ammonium carbonate solution. The beryllium is precipitated as a basic carbonate which is then ignited to pure beryllium oxide.

2. Method proposed by Debray in 1855. The beryl is pulverized and mixed with half its weight of quicklime. The mixture is then fused and the fusion treated with nitric acid giving a jelly which is evaporated to dryness. The result- ing powder is calcined to decompose the nitrates of aluminum, beryllium, and iron. The residue is boiled with ammonium chloride solution and filter- dd. The filtrate is added to an ammonium carbonate solution and allowed to stand eight days to put the beryllium into solution. Ammonium sulfide is added to precipitate the iron and the beryllium is obtained by boiling the solution. The basic beryllium carbonate is thus formed and is then ignited to beryllium oxide.

3. Method proposed by Schaffer in 1859. The powdered beryl is fused with fluorspar and the fusion digested with sulfuric acid at about 200 degrees C. It is then heated to a red heat to expel the silicon tetrachloride and excess sulfuric acid. The residue is dissolved in dilute sulfuric acid and the aluminum crystallized out as alum. Metallic zinc is added and the solution allowed to stand for two or three days precipitating the rest of the aluminum as a basic sulfate. Potassium sulfate is added to crystallize out the zinc as a double salt, and the beryllium is obtained by the ammonium carbonate separation method as beryllium oxide. 4. Method proposed by Gibson in 1893. Ammonium hydrogen fluoride completely decomposes beryl even at low temperatures and when the beryl is coarsely ground. The beryl is mixed with six times its weight of ammonium bifluoride and heated in an ifon pot. The mass is cooled, leached with water, and the fluorides converted to sulfates with concentrated sulfuric acid. The sulfates are partially decomposed, digested with water, and the solution filtered. The aluminum and the iron are precipitated with ammonium sesquicarbonate leaving the beryllium in solution. The last traces of iron are removed by means of mer- curic chloride and ammonium sulfid4, and the beryllium obtained by the ammonium carbonate method as beryllium oxide, 5. Method proposed by Lebeau in 189b. The beryl is fused with twice its weight of cmicium fluoride and the fusion treated with sulfuric acid in the cold. Tt is then heated to drive off the silicon tetrafluoride and the excess sulfuric acid and is then leached with water to give a solution of sulfates. Beryllium, aluminum, and iron and some calcium sulfate 4.

together with excess acid are in this solution. The excess acid is partially nedtralized with potassium carbonate and the aluminum crystallized out with potassium as alum. The iron is removed with the potassium carbonate procedure. The beryllium is

separated by the ammonium carbonate method. The yield of this process is 55 percent. Finely powdered beryl is mixed with its own weight of coke and heated in an electric furnace for lj hours, Pure silica is driven off and aluminum carbide, beryllium, iron silicide, and silicon carbide formed. The mass is disintegrated by weather- ing and treated with hydrofluoric acid. Sulfuric acid is added to drive off the silica as silicon tetrafluoride and the residue consisting of sulfates of aluminum, beryllium, and iron is treated as in the first method of Lebeau. 6. Method proposed by Warren in 1895. The powdered beryl is mixed with four times its weight of sodium carbonate and fused for three hours in a blast furnace. The fusion is dissolved in an excess of hydrochloric acid by means of superheated steam, evaporated to dryness, taken up with water, and the silica filtered off. The iron is precipitated and the filtrate made alkaline by an excess of sodium carbonate and heated with an excess of gaseous sulfur dbxide which dissolves both beryllium and aluminum oxides. The solution is heated to boiling when aluminum hydroxide is precipitated in a granular form. The beryllium oxide is recovered by the ammonium carbonate method. 7. Method proposed by Wyrouboff in 1902.

The mineral is decomposed by potassium hydroxide, the silica is filtered off, and the material taken up with hydrochloric acid. The filtrate contains the chlorides of beryllium, aluminum, and iron. This solution is evaporated to a small bulk and a concentrated solution of potassium oxalate is added. After standing a short time the oxalates crystallize out and are filtered off. They are then leached with a small amount of water leaving only the beryllium oxalate undissolv- ed. The dried residue of beryllium oxalate is calcined to produce beryllium oxide. Care must be taken to prevent the sotution from becoming acid as beryllium oxalate is very soluble in dilute acids. 8. Method proposed by Pollock in 1904. In the first method of Pollock the finely powdered beryl is fused with its own weight of caustic soda and the fusion treated with strong hydrochloric acid. Allow the solution to settle for one day and then filter off the silica. Treat the filtrate with ammonia, redissolve the precipitate with hydrochlodic acid, saturate the solution with hydrochloric acid gas, thus precipitating nearly all of the aluminum as the chloride and leaving the beryllium and iron in solution. Filter and concentrate the solution. Separate the iron with ammonium sulfide as the inedluble Ion sulfide and obtain the beryllium oxide by the ammonium carbonate method. A second method is to fuse the beryl with potassium hydroxide, treat the fusion with sulfuric acid, and boil well with steam heat. The silica is filtered off and the aluminum separated as alum, continuing from here as in the first method.

A third method is to fuse with sodium hydroxide, treat the fusion with sulfuric acid, boil, and filter out the silica. The filtrate is neutralized with ammonia, the precipitate dissolved in sulfuric acid after filtration, potassium sulfate is added, and alum is crystallized out. After most of the alum has crystallized the solution is treated with its own volume of alcohol which precipitates the rest of the alum leaving only beryllium and iron in solution. The rest of the procedure is the same as that of the first process. 9. Method proposed by Parsons and Barnes in 1906.

The powdered beryl is mixed with its own weight of potassium hydroxide and fused in a carborundum crucible. The product of the fusion is leached with water and concentrated sulfuric acid and the leachings evaporated to dryness to dehydrate the silica. The residue from the evaporation is leached with hot water, the leachings evaporated to small bulk, and alum crystallized out. The remainder of the aluminum is removed by treating the solution with sodium bicarbonate. The solution is filtered and the filtrate, containing the beryllium, is diluted and boiled thus precipitating beryllium basic carbonate. This precipitate is ignited to beryllium oxide. The yield of this process is about 70 percent. 10. Method proposed by James and Perley in 1916. Gadolinite is pulverized, heated in iron vessels with sulfuric acid, leached with water, and the solution treated with oxalic acid. After standing 12 hours, the crystalline rare earths oxalates deposit and are filtered off leaving iron and beryllium in softion. The filtrate is treated first with potassium carbonate and then with sodium hydroxide and ammonia precipitating iron and beryllium. The beryllium and some iron is dissolved out of this precipitate with hydrochloric or sulfuric acid. The acid solution is boiled, neutralized with sodium hydroxide and ammonia, and the iron precipitated. In the filtrate, now free from iton, /0.

beryllium is precipitated as the basic carbonate. 11. Method proposed by Copaux in 1919. Beryl is ground and mixed with twice its weight of sodium fluosilicate and heated to 850 degrees C. This fusion produces sodium fluo-berylate which is very sol- ule in water and sodium fluoaluminate which is nearly insoluble in water. The products of the fusion are leached with water and the leachings are converted to sulfates. The beryllium sulfate is then crystallized out of the solution. 12. Method proposed by Engle and Hopkins in 1924. This method is the same as that of Copaux except that instead of fusing the beryl and sodium fluosilicate mixture it is only sintered. T1hey obtained an extraction of 46 percent. 13. Method proposed by James in 1926. The beryl is ground to 150 mesh and thoroughly mixed with 0.7 of its weight of quick lime. This mixture is moistened and formed into balls about the size of golf balls. These balls are then sintered in a furnace at about 1000 to 1100 degrees C. The sintered product is then ground and treated with concentrated sulfuric acid. The silica and calcium sulfate precipitate is filtered off, and most of the aluminum separated from the filtrate as ammonium alum. The beryllium / I.

is separated from the solution by the ammonium carbonate method.

14. Method proposed by Eiynon in 1933. Beryllium oxide is heated to 600 degrees F in a tube furnace in an atmosphere of carbon tetrachloride. Volatile beryllium ch1dride together with a little aluminum chloride and a little iron chloride sublimes over. Due to the use of carbon tetrachloride vapor as a chlorinating agent instead of chlorine gas very little aluminum chloride is formed. The anhydrous beryllium chloride thus produced is then used to make beryllium. A yield of 50% is obtained. 15. Method proposed by Clines in 1938. Beryl is mixed with charcoal (in a four to one ratio) and heated in a tube furnace to 800 degrees C in a current of carbon tetrachloride. Beryllium chloride, aluminum chloride, and iron chloride subl- ime over together. A yield of 63.6% is obtained. 16. Method proposed by Wooster in 1939. Beryl is mixed with an equal weight of carbon and the mixture heated in an atmosphere of hydrochloric acid vapor at 1000 degrees C for 6 hours. Volatile anhydrous beryllium chloride, aluminum chloride, and iron chloride, come off and are collected. A yield of 75% of the beryllium is obtained. 17, Method proposed by Greenbaum in 1941. Mix beryl and charcoal in a two to one ratiox, heat to 920 degrees C for nine hours in a current of dry chlorine gas. Silicon tetrachloride, aluminum chloride, iron chloride,and beryllium chloride come over. By means of fractional distillation a product containing 75% anhydrous beryllium chloride is produced. '3,

Processes Now Used Commercially.

1. Method used by the Brush Beryllium Company. The ore is melted, quenched in water, ard ground in a ball mill to 200 mesh. The ground beryl is heated with sulfuric acid to form water soluble sulfates of aluminum and beryllium., These are separated from the silica by leaching and filtering. To the filtrate ammonium sulfate is added and alum is crystallized out of the solution. The mother liquor is then evaporated and the beryllium is

crystallized out as BeSO4.4H20. These crystals are heated to decompose the sulfate and obtain pure beryllium oxide. It is believed that the melting of the ore and the subsequent quenching in water serves a double purpose. First of all it breaks the ord up, thus minimizing crushing costs. Second the melting and quenching serves to transform the beryl which is unattacked by sulfuric acid into a form which is attacked by sulfuric acid. 2. Method used by the Siemens-Konzern. The beryl is sintered with an equal weight of sodium fluosilicate at from 650 to 700 degrees C. /+-.

Sodium fluoberylate is leached from this sinter with cold waterand beryllium hydroxide and calcium fluoride are precipitated from this solution with calcium hydroxide. The precipitate is treated with hydro. fluoric acid to dissolvea the beryllium as beryllium fluoride. This solution is filtered and evaporated to dryness to get crude beryllium fluoride. The crude fluoride is dissolved in its own weight of water and the solution filtered to get rid of insoluble impurities. The solution is then evaporated to dryness to give pure beryllium oxyfluoride. 3. Commercial process listed by Prof. Hayward. Crush and grind the beryl to 200 mesh and sinter with a mixture of sodium fluoride and sodium fluosilicate at 700 degrees C. Crush and grind the sinter in water to dissolve out the soluble sodium fluoberylate to give a soJltion containing 13 grams per liter of sodium fluoberylate. Sodium hydroxide is added tb this solution to precipitate beryllium hydroxide. The beryllium hydroxide is filtered off, ignited at 500 degrees C, and sintered at 300 degrees C with ammonium bifluoride to obtain beryllium fluoride. CHAPTER III

Analytical Procedure Used in this Thesis.

After investigating the various quantitative procedures available for the determination of aluminum and beryllium in silicates, it was decided to uset the sodium bicarbonate method as proposed by Parsons. This method is as simple as any of the other methods which have been proposed and its accuracy is about as good as that of the other methods proposed. The silicate containing iron, aluminum, silica, beryllium, and calcium or sodium is ground to 200 mesh. A one gram sample is weighed out and fused with ten grams of anhydrous sodium carbonate in a nickel or platinum crucible. The product of this fusion is dissolved in water and the solution made acid with hydrochloric acid. Aluminum, beryllium, iron, calcium, and sodium go into solution leaving a precipitate of silica. This solution is evaporated to dryness, taken up in hydrochloric acid, evaporated to drynesd again, baked for several hours at 110 degrees C, and taken up in hydrochbric acid. This solution is filtered. The filter cake contains the dehydrated silica and the filtrate contains iron, aluminum, beryllium, calcium, and sodium chlorides. The fil-. ter cake is ignited in a platinum crucible, weih- ed, the silica volatilized off with hydrofluoric acid, the fluorides left are decomposed with sul-. furic acid, the residue heated to redness, and weighed. The loss in weight is the silica. The residue is fused with sodium bisulfate, dissolved in water, and added to the filtrate above. The mixed soltions containing all of the aluminum, beryllium and iron are neutralized and excess sodium hydroxide added to dissolve the aluminum and the beryllium. The insoluble iron is then filtered off and the filtrate then contains only aluminum, beryllium, and sodium salts. This solution is neutralized with hydrochloric acid and solid sodium bicarbonate added to make a 10 percent solution of bicarbonate. This solution is then quickly heated to boiling and filtered. The aluminum is precipitated as the bydroxide while the beryllium remains in solution. If the bicarbonate is boiled very long some of the bicarbonate will decompose forming carbonate, which will dissolve the aluminum to a certain extent. The filter cake of aluminum is redissolved in M7.

hydrochloric acid, diluted to 400 cc, neutralized with ammoniu* hydroxide, the aluminum hydroxide

filtered off. This filter cake is redissolved, diluted, and reprecipitated to eliminate all coprecipitated sodium salts. The final aluminum

hydroxide is ignited and weighed as aluminum oxide. The coprecipitated ammonilm salts volatilize during ignition.

The filtrate from the bicarbonate precipitation above is made acid with hydrochloric acid and thoroughly boiled to drive off all of the carbon dioxide. The solution is then neutralized with ammonium hydroxide and the beryllium hydroxide is filtered off. This beryllium hydroxide must be reprecipitated at least twice to eliminate coprecipitated sodium salts. The final pure beryllium hydroxide is then ignited to beryllium oxide and weighed.

Since a sample weight of one gram is chosen, the weights of the silica, alumina, and beyllia multiplied by 100 give the percentages of the above mentioned substances direct&y. CHAPTER IV Description of the Beryl Used and of the Fluxes.

The beryl ore used came from unweathered deposits in New Hampshire and is considered to be representative of the average beryl ore to be obtained. The beryl was of a green color combin- ed with gangue containing orthoclase, mica, and some green, granular mineral whose character was undetermined. There were some large crystals of beryl but most of the crystals were small an d scattered through the material. The mica contained some iron but it is not believed that any of the other minerals contained appreciable amounts of iron. The beryl was handpicked giving a beryl product which contained approximately 90 perdent beryl mineral. The ore as received varied in size up to four inch lumps. The concentrated ore was first crushed in a jaw crusher (Blake type), then crushed finer in a roll-jaw crusher, then crushed in rolls. The product from the rolls was ground in disk grinders and then given a final grinding in pebble mills. The grinding in the disk grinder introduced some iron into the ore. "It,

This ground ore is to be used in the experiments. This ore was analysed and the following composition is deteraineds

S102------6 0 . 0 % A1203------17.5% BeO------12.2% The sodium chloride was used as bought. Tech- nically pure, crystalline sodium chloride of the usual size distribution was bought. Technically pure, anhydrous calcium chloride prepared for use in dessicatbrs was used for these experiments. The charcoal used was finely ground wood charcoal which was found in the pyrometallurgy laboratory. The manganese dioxide used was ground up pyrolusite

containing about 80% MnO2 e The discussion of the experimental results will be divided into two parts: 1, the preparation of volatile chlorides by fusion of beryl with alkali chlorides; and 2, the recovery of pure beryllium oxide from the chlorides and the residue from the fusion. CHAPTER V

Description of the Exerimental Results.

Several preliminary runs were made in order to determine whether or not aluminum and beryllium chlorides could be formed by the fusion together of beryl and sodium chloride. The equipment used is shown in Diagram 1 of Appendix A. The mixture of 50 grams of beryl and 100 grams of sodium chloride is heated to 700 degrees C in the first run but no reaction took place. In the next run 50 grams of beryl and 100 grams of sodium chloride were mixed and heated to 1150 degrees C and a very definite reaction took place. Aluminum and iron chlorides condense in the condensing tubes and are collected and analysed. This proved that the

aluminum and iron chlorides could be produced by the fusion of beryl with sodium chloride but there was no indication that beryllium chloride was

formed. With these results it was felt that further investigation was justiftedhowever.

In the next run a mixture of 50 grams of beryl and 100 grams of sodium chloride was heated

in the same apparatus to about 1000 degrees C. This time the material was raised to temperature :Z./..

more rapidly; in fact, the temperature of the mixture was raised from room temperature to 1000 degrees C in less than i hour. The fusion was maintaindd at temperature for about 10 minutes. During this time quite a bit of mixed chlorides deposited in the condensing tubes and some hydrochloric acid was evolved. The two crucibles were then taken from the furnace and immediately broken open. Some liquid poured out and was cooled and saved while most of the residue was solid and porous. The liquid residue was violet in color as was the solid residne. The chlorides deposited in the tubes were iron AdM aluminum chlorides. The liquid residue contained much residual sodium chloride, but it also contained beryllium chloride and iron chloride, The solid residue was leached with hot water and the leachings coniined iron and beryllium chlorides. The solid residue left from the leaching was pure white and was anal- yzed. It had the following composition:

SiO2------40.6% A1203------11.76%

BeO------3. 07% This would indicate a yield of about 75% judging :

from the composition of the solid residue after the difference in weight between the ore charged and the solid residue is taken into account.

Another run was made which was identical with the run described above except that the fusion was held at temperature for about 3/4 hour. The same general results were obtained except that the yield was better. In this case the composition of the residue was as follows:

SiO 2 ------65.8%

A12 03------8.89% BeO------0.53%

This would indicate a yield of about 95.5%. It is believed that the yields quoted so far are high due to unavoidable errors in analysis. Much of the fume leaked out and some of the fume went through the condensing system without condensing. There-

fore it was believed that a determination of the yield on the basis of the residues would be more

accurate than a determination on the basis of material recovered.

Since the above results were so promising, ten more runs were made under the same conditions treating 600 grams of beryl in order to obtain a sufficiently large quantity of condensed chlorides, and liquid residue to permit experiments to determine the best method for working up these products for beryllium and aluminum oxides. After making these runs it was decided to determine the effects of temperature, reducing conditions, oxidizing conditions, various proportions of reagents, and the relative effects of sodium and calcium chlorides. The results of these runs are tabulated and graphed in Appendix B. In all these runs the fumes were not saved and the whole condensing equipment and double crucible setup was not used. Instead, single crucibles with the appropiate charges were heated to the indicated temperatures in an electric furnace. The yields were calculated from the weights of the charge before and after heating and from their compositions. In order to save time all the charges were held at temperature for one hour only. Thoroughly dried charges were used exclusively in order to prevent formation of hydrochloric acid and consqquent wast4Vof chloride ion. The results will be interpreted in the chapter on the discussion of experimental tesults. This concludes part one of the description of experimental results. The next part describes the working up of the chlorides. In this second part of the report of experimental results a report of the methods tried for extract- ing aluminum and beryllium oxides fsom the chlorides. Two sets of chlorides are used as a starting point for these experiments. The chlorides deposited in the condensing tubes and the chlorides in the liquid residue are the two sets used. The chlorides deposited in the tubes are a mixture of aluminum and iron chlorides, if deposited under the normal and dry conditions. The liquid residue con- tsins sodium chloride, iron chloride, beryllium chloride, and calcium chloride# It was found that upon heating the bydreted chlorides of aluminum, beryllium, and iron decomposed at 150 degree C into aluminum, beryllium, and iron oxides. Hydrochloric acid was evolved. All of these oxides were readily soluble in dilute hydrochloric acid. When the oxides were ignited at 500 degrees C the aluminum oxide was ins&luble in concentrated hydrochloric acid while the iron and beryllium oxides dissolved. The Ion oxide was soluble in dilute hydrochloric acid while the beryllium oxide was not. Therefore a recovery of pure beryllium oxide and aluminum oxide can be made from the mixed chlorides by the s7

method shown by the flow sheet given in Diagram 1 of Appendix C. Since the products of the fusion

of sodium chloride and beryl are either the mixture of aluminum and iron chlorides or the mixture

of sodium chloride, calcium chloride, iron chloride, and beryllium chloride, the flow sheets given in Diagrams 2 and 3,respectively, would be of more

use. Experiments showed that calcium chloride, when hydrated, decomposes upon heating above 200 degrees C into calcium oxide and hydrochloric acid. It was found in making the fusions with the

condensing system that if a little steam was introduced into the condensing system in its hottest

part a deposit of aluminum oxide with a little iron chloride would form instead of the usual deposit of aluminum and Irn chlorides. This

deposit could be leached with water to remove all

of the iron and the aluminum oxide which remained

was found to be free of all iron when tested by the very sensitive thiocyanate test. The temperature

of the part of the condensing system where the

steam is injected is about 200 degrees C. If the temperature x is raised to about 300 degrees C the

iron chloride is volatilized leaving pure aluminum ;76.

oxide. In this case the iron chloride is redepos- ited further on in the condensing system. These two methods are shown in flow sheet form in Diagrams 4 and 5 of Appendix C. Experiments show that it would be extremely difficult to separate aluminum and beryllium salts by a proposed method which follows. Heat the hydrated chlorides to such a temperature that one will decompose into the oxide and that the other

one will not. It has been found that the two decomposition temperatures are so close together that this process is not practicable. Also it does not seem practical to precipitate either aluminum or beryllium hydroxide away

from the other. The beryllium hydroxide starts to precipitate at a pH of 3.6 and continues to precipitate over a p range of about 2. The aluminum hydroxide starts to precipitate at a pH of 3.9 and continues to precipitate over a pH range of about 2. Since the two ranges overlap

it is obviously impossible to make a good separation of aluminum fron beryllium by such a method.

Beryllium hydroxide is soluble in a ten per cent solution of sodium bicarbonate while aluminum hydroxide is not. This can be used but the recovery of the beryllium from the bicarbonate solution is relatively difficult and expensive. This separation of beryllium hydroxide from this solution can be made by diluting the s&&ution, boiling it, filtering off the beryllium precipitate, and recovering the bicarbonate by evaporating down the solution. Therefore thuis process is not recommended. CHAPTER VI

Theory of Processes Proposed in this Thesis.

Experiments show that beryl will react with molten sodium or calcium chlorides or with those chlorides at temperatures slightly below their melting points. The products formed are sodium or calcium silicates, aluminum chloride, beryllium chloride, and iron chloride. Since this reaction takes place only at a higher temperature than does ordinary chloridizing roasting it is believed that the reaction in this case is a basically different one. Before proceeding with this discussion it will be well to review just what happend in the reaction mixture during the heating period. If the mixture is dry no fumes will come off until a temperature of at least 750 degrees C is reached. At 800 degrees C the sodium chloride melts (the calcium chloride melts at a lower temperature but in all other respects the procedure is analogous) and the reaction mixture becomes a clear, watery, pool of liquid. Chloride fumes come off in great quantities during this period. Then in a few minutes the whole pool becomes pasty and then almost solid. Chloride fumes keep coming off during this period and will continue to come off for a long ttme after the crucible of reaction mixture solidifies. While in the pasty stage gaseous chlorides puff the mixture into a porous mass.

It is believed that the chlorides are formed by the following reaction:

Be3 A12 Si6 O1 8 + 12 NaCl -. 6 Na2 SiO3 + 3 BeCl3

+ 2 AlCl3 This reaction may very well be the one thich takes place during the liquid stage with part of the chlorides going into solution in the excess sodium chloride. The pasty stage may be due to the precipitation from solution in the molten chlorides of the sodium silicate. The solid phase would then be explained by the using up of the sodium chloride and the production of more sodium silicate. The same general explanation would hold for the calcium chloride reaction using calcium salts everywhere instead of sodium salts. This theory is upheld by the fact that when the residue from the calcium chloride reaction is leached with hot water it falls apart into a powder much finer than the beryl originally in the mixture. The precipitated calcium silicate would be very fine 3d.

and the degree of fineness would be independent of the fineness of the charged ore. This seems to be experimentally verified.

The addition of charcoal to the mixture defin- itely inhibits the above reactions. This is obviius from the experimental results given in Appendix B.

It is believed that the reason for this is not chemical but purely physical. In making the runs with charcoal it was observed that the charge did not appear to melt or run together even at temperatures much in excess of the melting point of sodium chloride. This is probably due to the fact that the coating of charcoal on each particale inhibits the coalescence of the particles even if they are molten and thereby inhibits the reaction. dioxide The addition of manganese Ato the reaction mix- tune also inhibits the reaction, though to a lesser degree. It is believed that this effect is also due to physical rather than chemical causes. The explanation is analogous to the one given abovefor the effedt of charcoal.

The slower effect of sodium chloride on beryl when the sodium chloride is present in comparatively small amounts may be due to the lesser amount of sodium ssilicate which can be dissolved in the sodium chloride present. This would cause sodium 31'.

silicate to precipitate on the surface of the beryl particales before they had been completely reacted withand this precipitated layer of sodium silicate would inhibit further reaction. The basic theory underlying all of the processes for recovering beryllium or aluminum oxide from mixed chlorides is the fact that completely dehydrated aluminum or iron oxide is insoluble even in acid. However, partially hydrated oxides are soluble in acid; the solubility becoming greater with greater degree of hydration. The temperatures of dehydration of the various oxides are 'sufficiently far apmpt to make possible a separation on this basis. Hydrated iron, aluminum, calcium, or beryllium chlorides when heated decompose according to the following general aquation, 2MClx + xH20-*BxHCl + M20x CHAPTER VII Conclusions.

The experiments which have been described in this report show that it is possible to prepare pure aluminum and beryllium oxides from beryl by a chloride process in the laboratory. Certain mod. ifications in the processes used in the laboratory will probably have to be made before they can be used commercially. However, the purpose of this work has been to determine the laboratory proced- which will give the best results. This has been done.

The optimum fusion temperature seems to be 1000 degrees C as the yield curve reaches a max- imum there. If an atmosphere of the volatilized chlorides is kept over the fusion mixture, all of the aluminum chloride formed will volatilize while all of the beryllium chloride formed will remain in solution in the excess s&dium or calcium chloride present. This makes a separation between the beryllium and the aluminum which simplifies the rest of the procedure. The rate of heating must also be high it the best results are to be obtained. It is thought that calcium chloride would be better than sodium chloride for commercial practice for the yield with calcium

chloride is better and because the calcium chloride can be easily regenerated from limestone.

In Appendix D two possible over all flow sheets are given, one using sodium chloride and the other using calcium chloride. The latter is to be pre- ferred for reasons given above.

With a mixture of two parts of sodium chloride to one of beryl there is a 32 percent excess of s&At in the reaction mixture. However, it is felt that this is useful as the excess sodium chloride acts as a solvent for the beryllium chboride which would otherwise be volatilized at the temperature used. The same is true of the calcium chloride process. Also the excess chloride keeps the mixture molten longer and therefore gives a longer effective reaction time and a better yield.

The chemical effect of the reducing agents a and the oxidizing agents is believed to be neglig- ible while the physical effect of them is defin- itely detrimental. Therefore, neither oxidizing nor reducing agents should be added to the fusion. Future work on this project might well be devoted to production of cheap, corrosion resist- 34.

ant equipment for this process. Good condensing equipment is needed in particular. Also it might be worthwhile to work out an adaptation of this process for the recovery of pure aluminum oxide from silicate ores stch as clay or slate. Such a process should be even simpler than the process described in this report for the recovery of aluminum and beryllium from beryl. Appendix A. Diagram of Eiuipmeni.

3. Jr = =U 0 I TO Asp aYor

~2.

IIew I'

I' I 8

0 0 7 9 0 0 Key to Diagram of Equipment Used,

I. Ekleymeyer Flask. 2. Flask of distilled water. 3. Rubber tube connection. 4. Fireclay junction. 5. Condensing tube. 6. Quartz delivery tube. 7. FiredcW and lime fused seal. 8. Fireclay crucibles. 9. Furnace. 37

Appendix B.

Data on the Effect of Temperature, Reducing Conditions, Oxidizing Cond-

itions, and Chloride Concentration on Yield.

Charge 1. 50 grams of Beryl, 50 grams of Sodium chloride.

Charge 2. 50 grams of beryl, 100 grams of sodium chloride.

Charge 3. 50 grams of beryl, 190 grams of calcium chloride.

Charge 4. 50 grams of Peryl, 100 grams of sodium chloride, 10 grams of charcoal.

Charge 5. 50 grams of beryl, 100 grams of sodium chloride, 10 grams of manganese dioxide.

The yields obtained by heating the above charges to the tabulated temperatures are given on the next page. Percent Yield for each Charge at

Each Temperature.

Temp. Charge Number. Degrees C. 1 2 3 4 5 500 0 0 0 0 0 700 0 0 0 0 0

800 20 48 -- 22 50 900 35 78 85 25 75

1000 -- 95 96 -- --

1100 -- 57 40 -- LLEH 11!1114-4 HHHH44+44T ffl44Th4ThThFTh~E ------~Th4PPI4Tt44itPH4 +H+i-H+f-f+H +!+1

------Ow ------+ + 44*+ H+H_ MIA#- ATF_ 411

I gais M-- AttLfthil tLLLLLHlLH

HI LI -h~l~~IU222L~i22UIbLU2LLLHILLLLLL~ILI~iLLWIUIIIJiI~~i~tH YV11VTF~T11I~hTFPFhTIh1Th~h1h~h~~h1hHT....Th .. T Hji _ffl

Ekh J

A--- - '$#d-HR 4i1I--Iit-haat----a- t1Th1-WTh-hA- -1+ -- t-- a- Hft1H4I_ + F, -I 4-f++ H+ ttdILtttLtdAl-flfltt-i-i-ti-i ttm-a-l-atH- -I-H-t +IT+flI{ I II i 11111 -+H+l -A- <1 H-ii-titttt-rff ItH lit Thtthittft thhH-Itt Th+FW+H+fI+ FF

~ HThILL r ++HHi+HHH+H H1K ~ff ~ h- r lzw$~.Ikj Fi f I SJT T FTt V T -1t-- 1:jyy1 -A 1hi _+fH _11_ -4H4 -4-4444 4 h-I-4--h~~L I 4-4 4 -4--144-U44- -I--L4~LLLLLLLL ~11Htid] L"iiiI4 l 1I H H1L I'-1 I _+ : L-T I :tt-1 - --

f-i--I- H'- 77- K: -4-ktaiFL-Ia il-A-4 If-i~TH f - -1--1-41 1 'i-HI T IT T 11 T P1111111

4H9 TI 44-4- NEz) I ------I-hi-k-I-A-

-Fj-FTTTr-rTTrTj-FT=-,_, , kill1 ...... i ~111~Th fL3LLILWij~iiLiLiLLJiL I I 1-- .F 1 -4 I I ...... f1-7 FI 4-4i iI I t p -I--H~-1tliI-HH -l--hH-hH~-I--t--Hf-H-HHiha4-i-Fiii-iiH I I-IA--HHi 11-11114 41+-4+- 4-H44-H4- Ri i-W11 1 4 44- Appendix C. Flow sheet 1.

AlCl 3 + BeCl2 4 FeCl3

water

Ignite at 50Q C

Leach with dilute Hydrochloric acid.

BeCl 2 A1203 4 Fe2O3 soln, Leach witi concentrated HCl.

A120'3 FeCl3

To wste.

Flow sheet 2.

AlC 3 + FeCl3 4 H2 0

Ignite at 500 C.

Leach with concentrated HCl

A1203 Fe 13 To waste. q .

Flow sheet 3.

FeCl3 + BeCl2 4 H20

Ignite at 50 C.

Leach witt dilute HCU.

BeC12 soln. Fe 03 Evaporate and To Waste. ignite at 500 C. BeO HC

Flow sheet 4.

AlCl3 + FeCl3 + steam at 300 C.

Al203 HC1 FeCl3 (volatilized off) Flow sheet 5.

AlC1 3 + FeCl3 + Steam at 200' C.

A1 2 03 + FeCl3 + HCJ

Leach th water.

A12 03 Fe;13 q-3-

Appendix D.

Flow sheet #1.

Beryl + NaCl. Fuse at 1000 C for 1} hours.

ResiIdue AlCl3 + FeC13 Leach with Ho0 Steam at 300 C Colo residue IeCl 2 + faCi Al2 03 FeC13 HC

0 FeCl3 SetiJ J SA). wast* $ waste Ilnite at 500 C Leach withe-. concentrated Hl

Fe 03 NaCl + BeCi2 To Ignite at waste 500 C. Le ch with water.

BeO NaCi Sell. Appendix D.

Flow sheet # 2.

Beryl + CaC12 4 CaCO3 Heat to 1000*C. HCl Residue AlC 3 + FeCl3 + H20 C1 12 C02 leach with water. Ignite residue at 500C. k Al2 O3 + Fe203 HC1 To waste 4 w Leach with concentrated CaCl + HC1 BeCi Fe3 A 2 03 Fed 3 Ignite at To 500*0C. waste

C 60 + HUl CaCl2 + Fe203 + BeO

Leach with dilute HCl.

Fe2 03 BeCl 2 + CaCl2 Igni e at 700C.

Leach with dilute HCl.

BeO CaCl2 HCl Appendix E. Bibliography and References.

1. Browing, P. E., Introduction to the Rarer Ele- ments.

2. Engle and Hopkins, The Metallurgy and Alloys

of Beryllium, Trans. Am. Electrochemical Soc., vol. 45, 1924.

3. Engle and Hopkins, Extraction of Beryllium

from Beryl, Eng. and Min. Jour., vol. 118, 1924. 4. Clines, M. R., The Production of Anphydrous

Beryllium Chloride from the Ore, Beryl, S. B. Thesis, 1938.

5. Eynon, D. L., An Investigation of Methods of

Producing Metallic Beryllium, M. S. Thesis, 1933.

6. Greenbaum, M., Purification of Beryllium Chlor- ide, S. B. Thesis, 1941.

7. Gregory and Burr, Beryllium and its Congeners, Friend-Textbook of Inorganic Chemistry, Vol. III, Part II.

8. Hodgman and Lange, Handbook of Chemistry and Physics.

9. Hopkins, B. S., ftmistry of the Rarer Elements. 10. Kroll, W., The Making of Beryllium, The Metal

Industry., April 8, 1927. 11. Mann, L,, Study and Preparation of Beryllium

and its Alloys, Thesis, 1921. 12. Mellor, J. W., A Comprehensive Treatise on

Inorganic and Theoretical Chemistry, vol. IV.

13. Negru, J. S., Glucinum, Chem. and Met. Eng., vol. 21, 1919.

14. Richards, J. W., The Metallurgy of the Rarer

Met&ks, Met. and Cher#. Eng., vol. 15, 1916. 15. Scott, Standard Methods of Chemical Analysis.

16. Sidney, L. P., Beryllium, Its Sources, Prod-

uction, and Properties. Chem. Age, vol. 14, 1926.

17. Beryllium and its Alloys, Siemens-Konzern, 1929.

18. Wooster, R. B., The Decomposition of Beryl, S. B. Thesis, 1939. 19. Hayward, C. R., Metallurgical Practice, 1941.