Signature Redacted Signature of Author

THE PRODUCTION METALLURGY OF BERYLLIUM SALTS by 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 Signature redacted Signature of Author.,............. ----,,, ~ 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 deter- mine the possibility of using a chloride process for the production of pure beryllium oxide with- out recoumse to expensive reagentssuch as, chlor- ine. 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 pre- liminary 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 equip- ment 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 pro- duced 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 stand- ing 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.

Load more