US3717437.Pdf

3,717,437 United States Patent Office Patented Feb. 20, 1973

1 2 3,717,437 pure aqueous sulfuric acid solution containing dissolved CRYSTALLIZATION OF BERYLLUM SULFATE beryllium sulfate which comprises first treating the solu James K. Grunig, Rodney J. Anderson, and Bess L. Vance, tion to form a solution containing about 50% to 55% Tucson, Ariz, assignors to The Anaconda Company by weight of sulfuric acid. The treated solution is then Filed Dec. 14, 1970, Ser. No. 97,841 cooled to a temperature sufficiently low to crystallize Int. Cl, C22b 59/00 beryllium sulfate therefrom and produce an acid mother U.S. CI. 23-24 B 16 Claims liquor containing about 58% to 62% by weight Sulfuric acid. The acidic mother liquor is thereafter separated from the beryllium sulfate crystals and the beryllium sulfate ABSTRACT OF THE DISCLOSURE O crystals are calcined to form beryllium oxide of suf A process for the recovery of substantially pure beryl ficiently high purity for most uses. If a higher purity beryl lium oxide from an impure aqueous Sulfuric acid solution lium oxide is desired, then after separating the acidic containing dissolved beryllium sulfate by crystallizing mother liquor from the beryllium sulfate crystals and prior beryllium sulfate from the solution after concentrating to calcining, the separated beryllium sulfate crystals are it to about 50% to 55% by weight of sulfuric acid and 15 redissolved in an aqueous solution and treated such that, then calcining the crystallized beryllium Sulfate. upon recrystallization and mother liquor, separation, BeSO2HaO or BeSO-4HaO crystals are produced. Af ter this recrystallization and separation, the beryllium sul BACKGROUND OF THE INVENTION fate crystals would be subject to the calcining operation Several processes have been developed for the extrac to form high purity beryllium oxide. tion of beryllium values from beryllium-bearing materials. A number of beryllium-bearing materials are suitable By these known prior art processes, it has been dificult to for treatment by the method of the present invention. separate compounds of Such material as aluminum, iron, These materials include both low and medium grade beryl magnesium, calcium and fluorine from the beryllium lium containing ores, for example, ores from the Spor compound component. Hence, a pure final beryllium prod 25 Mountain Region in the United States. Beryllium is uct is relatively costly to produce. thought to occur in these ores mainly as bertrandite For certain uses of beryllium oxide, e.g., in nuclear re (4BeO-2SiOa-28H2O) and/or beryliferous saponite. In actors, almost complete freedom from such contamina contrast to bertrandite, beryl (3BeO· AlaOa-6SiOa) and tion is required. Further high purity beryllium oxide finds phenacite (BeaSiO), which are other forms of naturally importance as a starting material for electrowinning eX 30 occurring beryllium, are not readily soluble in moderate tremely pure beryllium metal from a molten beryllium salt acid concentrations. However, these materials may be solution. As a result, there is a relatively large demand rendered acid soluble by such prior art processes as fiuo for a practical and economical process capable of uni ride sintering and alkali fusion. The invention is not formly producing beryllium oxide which is substantially limited to these particular ores but includes within its free from contamination. 35 scope any beryllium-bearing material which is either solu ble or which may be rendered soluble in sulfuric acid to SUMMARY OF THE INVENTION form a beryllium sulfate solution, regardless of the par We have discovered a method for producing a high yield ticular beryllium concentration. of substantially pure beryllium oxide having superior The beryllium ore or other raw material containing physical characteristics in such quantity and of such qual 40 the beryllium is first treated by any of the prior art ity as to make it an economically feasible and attractive methods to produce an aqueous sulfuric acid solution con process. We have discovered the favorable concentrations taining dissolved beryllium sulfate. This solution, which of sulfuric acid and beryllium sulfate to sufficiently de may contain a substantial amount of impurities, is the press the solubility of beryllium sulfate to a point where starting solution for the process of our invention. The upon after cooling the beryllium sulfate is substantially 45 aqueous solution can, for example, be obtained from the insoluble and precipitates out as crystals which upon sub eluates of a liquid-ion exchange (LIX) process, a resin sequent calcination yield beryllium oxide having a purity in column (RIC) process, or a leaching process. In com of 99-H%. monly assigned and co-pending application Ser. No. 710,- It is therefore an object of this invention to provide a 098 filed Mar. 6, 1968 and entitled Extraction of Beryl process which will result in a high yield extraction of 50 lium from Ores, there is disclosed an extraction process beryllium oxide from beryllium-bearing materials. for obtaining pure beryllium compounds from low grade It is also an object of this invention to provide a feasible beryllium ores. The beryllium ore is first leached with a process which will result in the production of an extremely mineral acid and then the pH of the leach solution is pure beryllium oxide. raised to about a pH of 4.0 to precipitate the major im It is a further object of this invention to provide an 55 purities. Beryllium hydroxide is then precipitated by rais economical process for producing beryllium oxide from ing the pH of the solution to about a pH of 8.0-8.4. In beryllium-bearing materials which process permits the easy accordance with the requirement for the present inven separation of the beryllium values from other compounds tion, the beryllium hydroxide from this process would which heretofore have been very difficult to separate. 60 then be partially dried and then dissolved with sulfuric Accordingly, to accomplish the above objects and other acid to a slightly acid solution of beryllium sulfate. This objects, the present invention contemplates a process for solution could well be used as the starting solution in our recovering substantially pure beryllium oxide from an im invention. 3,717,437 3 4 BRIEF DESCRIPTION OF THE DRAWING G./i. FIG. 1 illustrates a flow sheet of one process for ob BeSO4 ------168.0 Ala(SO4)3 ------27.5 taining pure beryllium oxide in accordance with the in MgSO4 ------4.05 vention. CaSO4 ------4.50 FIG, 2 illustrates an alternate process for obtaining MnSO4 ------1.88 pure beryllium oxide. FeSO4 ------22 DESCRIPTION OF THE PREFERRED F ------· EMBODIMENTS HaO ------508 10 HaSO4 ------760 Referring to FIG. 1, the starting solution consists of an Wt. percent H2SO4, 52. extract from a resin in column (RIC) process used for Such dilution serves to allow some crystal growth while recovering beryllium values. According to the invention, still serving to substantially completely depress the beryl the extract solution should have a concentration by lium sulfate solubility in the crystallization mother liquor weight of sulfuric acid of at least about ten times but less at conveniently attainable emperatures during subsequent than twenty-five times as great as that of the dissolved crystallization. beryllium sulfate, expressed as beryllium oxide. It has After the solution has been diluted to the degree re been found that the amount of extract solution within quired, it is transferred to a crystallizing tank where the this range contains a sufficient liquid volume to solubilize temperature of the solution may be reduced at a con any impurities, such as aluminum or magnesium etc., 20 trolled rate. Since the solubility of beryllium sulfate de for removal during the subsequent steps of the method creases with decreasing temperature, cooling of the solu described herein and yet is not too large to dilute the tion causes the beryllium sulfate to crystallize from the beryllium to such an extent to make the recovery un acidic solution. The beryllium sulfate is preferably cooled economical. Therefore, if necessary, the acid concentra to a temperature of about 120° F. and is held at such a tion is adjusted to form an aqueous solution which con 25 temperature for a time sufficient to allow for crystalliza tains a weight ratio of HaSO4:BeO in the above range. tion of as much of the beryllium sulfate as will separate. The solution also contains dissolved impurities carried When an extract solution having a sulfuric acid concen through from the ore or other raw material used. A typi tration within the range of about 50% to 55% by weight cal sampling of the extract, after it has been adjusted to is cooled to crystallize beryllium sulfate from the acid the desired HaSO4:BeO ratio, contains about substantial 30 solution, the acidic mother liquor produced therefrom 1y the following: will have a sulfuric acid concentration of between about G./i. 58% to 62% by weight. It was found that, at a mother BeSO4 ------86.3 liquor acid concentration within the aforementioned Ala(SO4)3 ------14.1 range, the solubility of beryllium sulfate in the extract MgSO4 ------2.07 35 solution is depressed at a maximum with the impurities CaSO4 ------2.31 remaining in the solution. At an acid concentration above MnSO4 ------.96 the stated range, the aluminum impurity, for example, FeSO4 ------.11 will become insolubilized thereby interfering with the ber F ------3.10 yllium-aluminum separation. On the other hand at an acid HaO ------744.5 40 concentration below the above range, both aluminum and HaSO4 ------390 beryllium would remain in solution. Wt. percent HaSO4, 31. Berylluim sulfate crystallizes inthe form of The aqueous solution is now in condition for treatment BeSO-2H2O to selectively crystallize the beryllium sulfate therefrom while allowing the other sulfates which have been formed, crystals which are advantageously removed from the (e.g., aluminum sulfate, magnesium sulfate, etc.) to pass mother liquor by centrifuging. However, the crystals may with the mother liquor. The solution is placed in a vacuum also be removed from the mother liquor by any of the evaporator where the solution is evaporated at 230° F. other well-known separating processes, e.g., filtering, or and under a pressure of 40 mm. of Hg until it contains the like. A typical sampling of the crystallization mother about 62% to 66% by weight of sulfuric acid. A typical 50 liquor which is removed from the centrifuging operation evaporator discharge at this stage contains substantially contains substantially the following: the following: G./i. BeSO4 ------19.0 G./l. Ala(SO4)3 ------31.0 BeSO4 ------240.0 55 MgSO4 ------459 Ala(SO4)3 ------39.3 CaSO4 ------5.08 MgSO4 ------5.78 MnSO4 ------2.12 CaSO4 ------6.43 FeSO4 ------.24 MnSO4 ------2.68 F ------.87 FeSO4 ------.31 60 H2O ------507 F ------1.10 H2SO4 ------860 HaO ------290 Wt. percent HaSO4, 60. HaSO4 ------1088 Wt. percent HaSO 65. The highly acidic mother liquor from the crystalliza tion process may be recycled and utilized as an ore leach It has been found that by vacuum evaporating a solu 65 acid in the RIC process. By doing this, substantially all tion having the above HaSO4:BeO ratio to a solution con of the impurities, and also the uncrystallized beryllium, taining this sulfuric acid concentration, it is possible to are returned to the leach solution. eliminate the fluorine impurity in the solution in the The separated beryllium sulfate crystals may be fired form of HF. The fluorine is removed with the condensate at a temperature of about 1000° C. (or higher) to pro from the evaporator and both are recycled back to the 70 duce a commercial grade of beryllium oxide. Commercial ore leaching process. The evaporator discharge is then grade beryllium has a purity of only about 95% by diluted until its acid concentration is within the range of weight. about 50% to 55% by weight sulfuric acid. A typical To obtain an even purer form of beryllium oxide, the sampling of this crystallization feed contains substantially solution containing dissolved beryllium values may be the following: Subject to a double crystallization process as illustrated 3,717,437 5 6 in FIG. 1. Instead of calcining the first crop of beryllium in FIG. 2. The initial steps of this alternate process, sulfate crystals which are recovered from the centrifuging namely concentrating, vacuum evaporating, diluting and operation, these crystals may be subjected to the follow crystallizing to produce BeSO2H2O crystals, are essen ing operation. tially the same as those already discussed with respect The pure beryllium sulfate crystals are first dissolved to the process illustrated in FIG. 1. The beryllium sulfate in water at a temperature ranging from about 75° F. crystals thereby produced are then separated from the to 150° F. to form a solution containing from 10 to 90 mother liquor and subsequently washed with an unused or more grams of BeO per liter. Subsequent to this, the solution of 60% sulfuric acid. The wash solution and solution is filtered to remove the insoluble impurities, e.g., mother liquor may be thereafter recycled back into the calcium sulfate. A typical solution formed on the first O system and used as a source of leaching acid in the RIC dissolution of the crystals contains substantially the fol process. The washed crystals are then dissolved with lowing: water to form a solution which is filtered to remove any insoluble impurities, particularly calcium sulfate. This BeSO4 ------248 second crystallization feed solution has a typical composi Ala(SO4)3 ------.60 5 tion substantially as follows: MgSO · · · · · · · ·· · · · · · · · · · · · · · · · · · · · · ··· · -· · · .42 G./l. CaSO4 ------.56 BeSO4 ------248 MnSO4 ------.1 1 Ala(SO4)3 ------.60 Feso. - ·· · · ·· · ·· · · · · · · · · · · · · · · · · · - · · · · ·· · · · N .08 MgSO4 ------.42 ------· · -w - - - = = ------O6 20 CaSO4 ------.56 H2O ------930 MnSO4 ------.11

H2SO4 ------80 feso. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · N .08

Wt. percent HaSO4, 6.6. --·- - -- -· *- · · - --> -w - - · · · · - a - a- -· · · ------*- **· · O6 Enough sulfuric acid is added to the solution to again H2O ------930 form a solution containing about 50% to 55% by weight 25 HaSO4 ------80 sulfuric acid, producing a typical solution containing sub Wt. percent HaSO4, 6.6. stantially the following: The solution is then transferred to a vacuum evaporator crystallizer where it is treated to evaporate it at about BeSO4 ------122 30 120° F. to a sulfuric acid concentration of about 30% to Ala(SO4)3 ------.37 40% by weight sulfuric acid and a beryllium sulfate con MgSO --·· ·a· *-· - sa - -· ·n - · - · · - n· · · ------...... - - - . .. .26 centration of about 13% to 9% by weight during the CaSO4 ------.35 course of which BeSO44H2O crystals are formed. The MnSO4 ------07 condensate is recycled to help dissolve the BeSO2H2O iso. · ·· · ·· · · · · · · · · · · · a- · · · · · · · - - - -· ·· · · - - · N .05 35 crystals obtained from the first crystallization preparatory · ------· · · - · - · · · · - - - as ------...... -- One for the recrystallization procedure. The crystals are sepa H2O ------'· · - · · · · · · · · 635 rated from the mother liquor which contains substantially H2SO4 ------799 the following typical composition: Wt. percent HaSO, 52.7. G./1. The beryllium sulfate solution is then transferred to 40 BeSO4 ------191 a crystallizing tank or fed to a recirculating crystallizer. Ala(SO4)3 ------1.10 The temperature in the tank is lowered to about 80° F. MgSO4 ------1.26 to effect crystallization of the beryllium sulfate and there CaSO4 ------1.36 by form dihydrated BeSO42H2O crystals. Subsequent to MnSO4 ------30 this recrystallization operation, the solution containing 45 so - - - - · - -- as - -· - · · · ------· - - - - ·.. - - - - . N .22 the beryllium sulfate crystals is subjected to centrifugation ·· -- -·· ·· ------· · - - - - - · - - · ------L - ...... Ole for separating the mother liquor from the crystals. A H2O ------790 typical sampling of the mother liquor separated from the H2SO4 ------416 crystals at this second crystallization stage contains sub Wt. percent H2SO4, 34.3. stantially the following: 50 BeSO44H2O crystals having a particle size of between 500-2000u are produced. These crystals are considerably BeSO - - - - · · · - · = a- -· - · · · ------· · - - - .... - . . . . . 30 larger than the crystals produced in the dihydrated form Ala(SO4)3 ------.44 which have a size between 10-70u. MgSO4 ------.31 The separated mother liquor formed during the evapo CaSO4 ------.42 55 ration and crystallization steps is thereafter recycled to MnSO4 ------O8 assist in the dilution of the beryllium sulfate solution to feso. · - · · · · ·· · · · · ·· · · · -· · · · · · · · - - · · · · · · ·"- - N .06 bring the solution to a concentration having between about ------· · · · - - - · · · ------· ------· ·...... One 50% to 55% sulfuric acid. H2O ------650 Since the crystals produced from this alternate method H2SO4 ------865 60 are much larger than those produced by the method Wt. percent HaSO, 57.8. illustrated in FIG. 1, the handling of the crystals in sub sequent operations is thereby eased. For example, the Here, as in the first crystallization process, the highly Crystals may be easily washed with water to free them acidic mother liquor may be recycled and utilized as an of any free sulfuric acid prior to their calcination to ore leach acid or as make-up acid for RICelution. 65 beryllium oxide. The wash water may be then recycled The recrystallized beryllium sulfate may then be fired to help dissolve the BeSO2H2O crystals for their re at about 1000” C. (or higher) in a calcinator. The result Crystallization in much the same way as the condensate, ing sulfur dioxide and sulfur trioxide gas emanating from as previously mentioned. The removal of this free suifuric the calcinator may be recovered and used to produce more acid prior to calcination eliminates the possibility of an sulfuric acid in an adjacent plant producing acid for leach 70 acid mist forming in the calcinator. It has been found ing incoming ore in the RIC process. The purity of the that the presence of such a mist markedly interferes with beryllium oxide obtained from the double crystallization g Subsequent production of sulfuric acid in the acid process is 99.--%. plant. An alternate process for crystallizing beryllium sulfate A summary of the above noted typical solution com and thereafter producing beryllium oxide is illustrated 75 positions is given in Table 1. 3,717,437

TABLE 1-SUMMARY OF TYPICAL SOLUTION COMPOSITIONS Granas per liter Wt. percent BeSO4 Ala(SO4)3 MgSO4 CaSO4 MnSO FeSO4 F HaO BISO HaSO4

Evaporator feed·· ·· ·· · ·· · · · · · · · · · · -· · · · · · ·· · · · · · 86. 3 14. 1 2.07 231 96 .li 3. 10 744.5 390 31 Evaporator dischage-- 240.0 39.3 5.78 6.43 2.68 .3l 1, 10 290 1,088 65 grystallization feed.---- 68. O 27. 5 4. 05 4. 50 1. 88 . 22 .77 508 760 52 Crystallization mother lig 9. O 3i. 0 4. 59 5. 08 2, 12 . 24 .87 507 860 60 Dissolyed first crystals---- 248 . 60 .42 . 56 . 11 .08 None 930 80 6. 6 Second crystallization feed (BeSO4-2HO)--.-- 122 .37 . 26 · 35 .07 . 05 None 635 799 52.7 Second crystallization mother liquor 3O .44 . 31 . 42 .08 .06 None 650 865 57. 8 (BeSO-2H2O). Second crystallization feed (BeSO44H2O)------248 · 60 . 42 . 56 . 11 , 08 None 930 80 6. 6 Segg gigation mother liquor 191 . IO 1. 26 1.36 .30 . 22 None 790 416 34. 3 e a" 2u}.

Although not illustrated by the flow sheet, the inven 8. A process according to claim 7 wherein the beryl tion is not limited to a one stage or a two stage crystal lium sulfate crystals from step (c) are dissolved in water lization process. The berylluim sulfate crystals obtained and sulfuric acid is added in an amount sufficient to from the second crystallization process may be subject establish a solution containing in the range of about 50% to a third crystallization by following the same procedure 20 to 55% by weight sulfuric acid and wherein the solution as is illustrated above where BeSO 4HaO is made. This is cooled thereafter to crystallize BeSOa-2HaO. would result in obtaining an even purer form of beryllium 9. A process according to claim 7 wherein the acidic oxide. Further the processes described herein may be mother liquor produced from step (iii) contains about operated in a continuous manner or otherwise without 30% to 40% by weight sulfuric acid. departing from the scope of the invention. 25 10. A process according to claim 9 wherein the redis Having described the invention with particular refer solved beryllium sulfate solution is treated by vacuum ence to the preferred forms thereof, it will be obvious to evaporation. those skilled in the art to which this invention pertains, 11. A process according to claim 9 wherein the crystals after understanding the invention, that various changes formed by recrystallization are washed with water. and modifications may be made therein without departing 30 12. A process according to claim 7 wherein both from the spirit and scope of the invention, as defined in crystallization steps take place at about 120° F. the claims appended hereto. 13. A process according to claim 8 wherein the solu We claim: tion in which the berryllium sulfate crystals are dis 1. A process for recovering substantially pure beryl solved is subsequently filtered to separate insoluble sul lium oxide from an impure aqueous sulfuric acid solu 35 fates. tion containing dissolved beryllium sulfate which com 14. A process for recovering substantially pure beryl prises: lium oxide from an impure aqueous sulfuric acid solu (a) adjusting the weight ratio of sulfuric acid to beryl tion containing dissolved beryllium sulfate, the solution lium sulfate, expressed as beryllium oxide, to the having a concentration by weight of sulfuric acid at least range of from about 10:1 to about 25:1, 49 about ten times as great but less than twenty-five times (b) treating the solution to produce a solution contain as great as the beryllium sulfate concentration as ex ing about 50% to 55% by weight sulfuric acid, pressed as beryllium oxide which comprises: (c) cooling the treated solution to a temperature suffi (a) treating the solution by evaporation under a ciently low to crystallize beryllium sulfate therefrom vacuum to form a solution containing about 62% and produce an acid mother liquor containing about 45 to about 66% by weight sulfuric acid, 58% to 62% sulfuric acid, (b) diluting this solution to between about 50% and (d) separating the acidic mother liquor from the beryl 55% by weight sulfuric acid, lium sulfate crystals, and (c) cooling the evaporated solution to a temperature (e) calcining the beryllium sulfate crystals to form sufficiently low to crystallize beryllium sulfate there high purity beryllium oxide. 50 from and produce an acid mother liquor containing 2. A process according to claim 1 wherein the impure about 58% to 62% by weight sulfuric acid, aqueous sulfuric solution is initially concentrated to form (d) separating the acidic mother liquor form the beryl a solution containing about 62% to 66% by weight sul lium sulfate crystals, furic acid and then diluted to a concentration of about (e) dissolving the separated beryllium sulfate crystals 50% to 55% by weight sulfuric acid. 55 in an aqueous solution, · 3. A process according to claim 1 wherein the solu (f) filtering the aqueous solution to eliminate any tion is concentrated by evaporation under a vacuum. insoluble impurities, 4. A process according to claim 1 wherein the treated solution is cooled to a temperature in the range from (g) evaporating the solution to form a solution con about 40° F. to about 130° F. to crystallize BeSO42H2O 60 taining about 30% to 40% by weight sulfuric acid, crystals. (h) recrystallizing the evaporated solution to produce 5. A process according to claim 1 wherein the beryl BeSO 4H2O crystals, lium sulfate crystals are calcined at a temperature of (i) separating the acidic mother liquor from the re about 1000° C. crystallized beryllium sulfate, 6. A process according to claim 1 wherein the crystal 65 (j) washing the separated crystals with water, and lized beryllium sulfate crystals are separated from the (k) calcining the recrystallized beryllium sulfate at a mother liquor by centrifuging. temperature of about 1000° C. to form a high purity 7. A process according to claim 1 further comprising, beryllium oxide. after step (c) and prior to step (d), the steps of: 15. A process according to claim i4 wherein both (i) redissolving the separated beryllium sulfate crystals 70 crystallization steps take place at about 120° F. in an aqueous solution, 16. A process according to claim 14 wherein the beryl (ii) recrystallizing beryllium sulfate from the redis lium sulfate crystals are separated from the mother liquor solved solution, and by centrifuging. (iii) separating the acidic mother liquor from the recrystallized beryllium sulfate. 75 (References on following page) 3,717,437 9 10 References Cited 3,395,975 8/1968 Grunig et al. ------23-24 B UNITED STATES PATENTS 2,974,011 3/1961 Riabovol ------23-183 Re. 20,274 12/1936 Sawyer et al. ------23-24 B FOREIGN PATENTS 1,710,840 4/1929 Price et al. ------23-24 B 5 14,964 7/1964 Japan ------23-183 2,018,473 10/1935 Sawyer et al. ------23-24 B 2, 160,547 5/1939 Jaegen et al. ------23-24 B HERBERT T. CARTER, Primary Examiner 2,408,934 10/1946 Kjellgren ------23-24 B 3,145,081 8/1964 Surls et al. ------23-183 U.S. Ci. X.R. 3,148,022 9/1964 Kruse ------23-24 B 23-117, 183, 23 3, 159,453 12/1964 Biermann ------23 2 E 9