J.
A.
TALLMADGE
J. B . B U T T H E R M A N J. S O L O M O N
MINERALS FROM
I4
1 N D U S T R I A L ' A NID E N 0 I N E E R I N 0 C H E M I S T R Y
1. aasumod new
importance as a possible means df re&&& thc .&t of water conversion. A very hrge n u m k of pmcurses have been proposed, ranging from those prompted by a d ' s never ending search for gold &'those of more immediaody practical wpwt such and d t recovery m e . W s deof, toward det&tion proposed .or.te+ and
re on
the topic h quite extensive; of
however (with the exception and bron&,.cecovery which has been
of minerals from sea wat&fiave been on a h b o r a & y bench scale..' Further, teat work ha$ been ,conc&$l' only with
Productionof fresh water'frdmthe pcedns .. , means productibn 'of"l&rgequ concehtratgd ,brine8'atid ~$altmixtures. >
,
such salts, contai,n, in some meas'uie, all
of the elements' present on . . eakth. This
In this article, specific, processas are &died as thw pertaining 'to &ery of halogens, major metals (sodium, magnesiuq calcium, an+ptassium), and .minor and triiee dements. &messes me dm designated as to whether mixed salts or ,multiple p d u c t s are invdv@. "
Literature citations are
as follows:
C--Calcium Reoway H G-General - ~ a Referewa lR ~~ . . .
article reviews arid ;%vWatesthe many llle@ods suggested for .,, .
.
iqerai .recovery
N-Scdium Kecavwy Water P-Properties of& R-Trace F.luncn&
s-'Mixedsalts
-'
Natural and Symhotic Sea Walw
I t is logical to inquire, before concerning oneself with ietailed discussion of recovery processes, what informaiion is available concerning the raw material with which one must work. An excellent description of sea water has been given by Sverdrup, Johnson, and Fleming (G79), and a list of all elements (except oxygen, hydrogen, and dissolved gases) known to occur in natural sea water as dissolved solids is widely available (G77, G27). Concentrations of these elements, as shown in Table I, are expressed a t a water concentration such that the chlorinity is 19.00 per cent. Chlorinity (GZO) is defined as the total amount of chlorine, bromine, and iodine in grams contained in one kilogram of sea water, assuming that the latter two were replaced by chlorine. (A slightly different definition of chlorinity is currently used.) The chlorinity of natural sea water varies from about 16 to 22 per cent. I t can be shown from the data of Table I that sodium chloride comprises about 90.6 per cent by weight of the
TABLE I .
SEA WATER CONSTITUENTS ~~
Concentration,a P.P.M.
Element
~
Potential Yield,b Lb./Yeai
Major 1. 2. 3. 4. 5. 6.
Chlorine Sodium Magnesium Sulfur Calcium Potassium
18,980 10,561 1 272 884 400 380
90,000,000 50,000,000 6,000,000 4,200,000 1 900,000 1,800,000
~
~
Minor
7. 8. 9. 10.
I
Bromine Carbon Strontium Boron
65 28 13 4.6
300 000 130 000 60,000 22,000 ~
~
~
Trace (30 elements, including the following)
16. 19. 23. 32. 39.
1
Lithium Iodine Copper Silver Gold
0.1 0.05 0.003 0.0003 0.000006
I
500 250 15 1.5 0.03
a Adjusted to a chlorinity of 79.0070 ( G 7 7 , G 2 7 ) . Based on desalination plant producing !,OOO,OOO g.p.d. of fresh water from 7,.500,000 g.p.d. of natural sea water of speciJic grauity 7.03. T h i s assumed plant concentrates the sea water threefold, to 500,000 g.p.d.
TABLE I I .
Reference Corresponds to Table I 19.0070chlorinity
RECIPES FOR SYN H E T I C SEA WATER
I
iirmstrong and Miall
Lyman and Fleming
Brujewicr
no ~
I10
Salts
Concentrations, P.P.M.
NaCl MgC12 MgSOI Na2SOa CaS04 CaCL
4,981 1,658
...
...
3.917 I
1 260 ~
...
1,141
1
1,102
...
123
...
198 58 (h-aBr) 58 20. 4b
76 ( MgBr2 )
... ... _
35,000
...
... 1,153 721
...
H3B08 Others
26,726 2.260 3,248
...
863
K90, KC1 CaC03 NaHC03 Bromide
Total _
McClendon et al.
i
~
34,421
1
34,481
34,442.4
a 24 SrClz and 3 N a F . 13 A12Cls; 2.4 AVa~SiO,; 7.5 dVa&409; 2 NHa; 7.3 LiNOB; and 0.2 H3POa.
46
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
total salts, if the approximation is made that sodium chloride is equal to the sum of sodium and chlorine concentrations. Carritt (G3) defines the major constituents as those six shown in Table I. If minor components are arbitrarily defined as those with concentrations between 1 and 100 parts per million (p.p.m.) and trace components as those occurring to 1 or less p.p.m., then there are four minor components and thirty trace elements. I t is usually assumed that the major constituents present in sea water exhibit the property of constant relative proportions; that is, variations in the composition of actual sea water are due only to changes in the amount of water present. I n work with the constituents of sea water, the departure from constant relative proportions among the major elements need be considered only in cases where high precision is required. An example of such variation is given by the ratio of calcium to chlorine, which is 2 to 47, larger at the ocean bottom than at the surface in cases of deep water in the open ocean. The minor and trace elements, however, appear to exhibit wide variations depending upon where the sample was taken, depth, season, and in some cases, time of day (G3). Gold has been reported to occur over a 10,000-fold range of concentrations. For comparative purposes, the potential yield of various elements from a 1.5 X 106 gallons per day (1.5 m.g.d.) sea water plant is included in Table I . Recipes for synthetic sea water, for the most part, attempt to duplicate the natural product as well as possible, although exact duplication is probably impossible (G79). Some problems are the contaminants occurring in standard reagents, the effects of marine organisms, interactions of complex ionic forms in solution, and technical difficulties involved in the preparation of such involved mixtures. Nonetheless, synthetic sea water recipes are quite valuable in oceanographic research and related areas. Of the four recipes listed in Table 11, we have found that only that of Lyman and Fleming is suitable over wide temperature and concentration ranges. The best sources for the physical properties of sea water are Sverdrup, Johnson, and Fleming (G79)or a National Research Council publication (G73). Much valuable information on the general properties of sea water is available in literature discussions of the occurrence of the various constituents, however, and a list of recent selected references including information on properties and compositions is given in Table 111. Some General Process Considerations
Many factors must be considered in discussing and evaluating mineral recovery processes, from both the technological and economic points of view. The more important of these are : -Product Type-Mixed Salt or Single Element. Since separation costs for complex, multicomponent mixtures are usually high, some workers have suggested recovery processes designed for a mixed salt product. Many of the problems associated with this approach are
TABLE I l l . Reference
Chemical Abstracts
Subject
P R O P E R T I E S OF SEA W A T E R
Original Citation
51, 14441e
Conductivity
Anderson, F. P., Guelke, R . W., Hotz, M. C. B., Spong A. H., Chem. lnd. (Londo;) 1957, p. 732.
51, 1 6 0 1 7 j
Phosphorus, silicon
Armstrong, F. A. J., J . Marine Biol. Assoc. U. K . 36, 317 (1957).
48, 11854s
Phosphorus, silicon
Armstrong, F. .4. J., Ibid. 33, 381 (1954).
47, 6198d
Phosphorus, silicon
Atkins, W. R . G., Ibid. 31, 489 (1953).
47, 6197i
Copper
49, 3583e
Refer, ence
Chemical Abstracls
Subject
Ori,cinal Citation Kranskopf, K . B., Geocke’m. Cosmochim. Acta 9, 1 (1956). Kruger, D., Bull. Inst. Oceanng. 47, 2 0 ( 1 9 5 0 ) .
5 0 , 8269g
Rare metals
45, 2529e
Phosphorus, silicon
52, 7834n
Enthalpy-roncn. data
Kunsunoki, K . , Kagaku Kogaku 22, 87 (1958).
51, 6 0 4 6 i
Nickel
Atkins, W. R. G., Ibid. p. 493.
Laevastu, T., Thompson, T. G., J . Conseil, Conseil Perm. Intern. Exploration M e r 21. 125 ( 1 956).
45, 9935h
Composition
Ionic composition
Barnes, H., J . ExpiI. Biol. 31, 582 ( 1 9 5 4 ) .
52, 106631
Composition
Legendre, R., Scientia 86, 221 ( 1 9 5 1 ) . Le$auk= eshkov I. Prorny. N. Khim 2, ’687
46, 67086
Trace elements
Black, W. A. P., Mitchell, R . L. J . Murine Eiol. rlssoc.’ L7. K . 30, 575
52, 12477g
Composition
51, 4013g
Barium, strontium
Bowen, H. J. M . , Ibid., 35, 451 (1956).
52, 16841i
Calcium sulfate
45, 5470b
pH, temp. etlert
41, 4977f
Carbonate
Bruevich S. V Gidrokkim. Muteri&ly 14,”97 (1948). Buch K. Suomcn Kemistilehi i9A, 4 (1946).
28, 1901-6
Buffer capacity
Mitchell P. H . Rakestraw ’N. w.: B ~ O I . B U / ~ 65, 457 ( 1 9 3 3 ) .
46, 5422c
Ammonia
Buljan, M., J . Murine Biol. Assoc. U. K . 30, 277 (1951).
43, 2050h
Viscosity
hliyake? Y . , Kuizumi, M., J.M w i n e Res. (SearsFound. MorincRes.) 7, 6 3 (1948).
52, 12477h
Composition, analysis
Carritt D. E. J . Chem. Educ.’35, l i 9 (1958).
33, 5244-1
Boiling and freezing pts.
,Miyake Y . Bull. Chem. Soc. ;,pa; 14, 5 5 ( 1 9 3 9 ) .
33, 4094-5
Phosphate
39, 5244-1
Osmotic and vapor press
Zbid., 14, 58 (1939).
47, 11094d
Calcium
50, 11187/
Carbonate
Monaghan, P. H., Lytle M.L.. J . Sediment. Peirol. 26, 111 ( 1 9 5 6 ) .
50, 629e
Viscosity
Cooper, L. H. N., J . Marine Biol. Assoc. U. K . 23, 181 (1938). Correns, C. W., Z. Deut. Geol. Ges. 100, 158 (1948). Danilchenko, P. T., Ponizorskii, A . M., Trudy Komi Filinln, Akad. Nauk S S S R 4, 65 (1953).
51, 15191b
Cadmium
52, 42EOc
Minerals in
55, 856h
Iodine
52, 969%
Eqn. of state
42, 64986
Composition
52, 3212i
Redox potentials
Mullin J. B. Riley, J . P., f.MarineRLs. (Sears Found. M u n n e R e s . ) 1 5 , 1 0 3 (1956). Novikov G. V. Gioiena i Sanit. i5, NO.’ 5 , % 2 ( 1 960). Oka S. Hishikari, S., J . Sic. dkem. Ind. Japan 47. 314 (1944).
49, 12233n
Composition
Poldervaart, A., Geol. sot. Am., Spec. Paper 62, 119 (1955).
50, 629e
H e a t capacity
Poniaovskii, A. M., Meleshko, E. P., Globina, N. I., Trudy Komi. Filiala Akad. N a u k S S S R 4, 7 5 (1953).
29, 3577-7
Calcium carbonate
36, 5682-6
Phosphate
Revelle, R., Fleming, R. H., PrGC. 5th Pacijc Cong. 3, 2089 (1923). Riviere, A,, Compt. Rend. 213, 7 4 (1941).
48, 10426b
X-ray spectrum
Ishibashi, M., Records Oceano . Works Japan 1, 88 (1953). Ishibashi, M., Hava, T., Ibid., 2, 45 (1955).
28, 1249-1
Electrical props
52, 4260c
Uranium
Starik J. E Kolyadin, L. $., Gedkhimijn, 1957, p. 204.
Ishibashi M. Kawai T J . CheA. So;. Japnn’73;’ 380 (1952). Ishibashi M. Kurata K., Ibid., io, l i O 9 (1936).
34, 7069-8
Calcium
Terashkevich, V. R . , Khim. Prom. 17, 37 (1940).
26, 2093-5
Sulfate/chlorine ratio
36, 5590-6
Bromine/chlorine ratio
55, 1 7 3 6 3 ~
Copper
Thompson T. G. Johnson, W. Wiith, H. E,, J . Conserl, Canseil Perm. Intern. Exploration M e r 6, 246 (1931). Thompson, T. G., Korpi, Edwin J., J . Marine Res. 5, 28 ( 1 9 4 2 ) . Tikhonov, M . K., Zharorenkina V. K., T r . Morsk. bidrofir. Inrt. Akad. Nauk S S S R 19, 51 ( 1 9 6 0 ) .
26, 1498-6
Calcium carbonate
Wattenberg, H., Naturwissenshaften 19, 965 (1931).
36, 1051-8
Phosphate
Wimpenny, R . S., Quart. Reu. Biol. 16. 389 (1941).
(1957). Lyman J. 4bel R . B. J . Ciem.’ Educ.’35, 115 (1958). Marozova, A. I., Firsova, G. N., Nauchn. T r . Novoche k . Politekhn. Inst. 27, 151 (1956).
( 1 952).
52, 5902n
Salinity of
5 5 , 277146
Perchlorate
47, 2554e
Titanium
31, 1687-5
Equilibrium
48, 6175a
Trace elements
49, 106846
Cesium and rubidium
47, 2554a
Aluminum
34, 4314
Lithium
45, 10130a
Vanadium
55, 1971h
Composition
45, 7 4 6 7 1
Uranium
33, 6686-9
desousa, A,, Ciencio (Lisbon) 2, 41 (1956). Eckart C. Am. .I.Sci. 256,’225) (1958). Eristavi, D. I., T r . Gruzinsk. Politekhn. Inst. 28, 31 (1953). Fleming, R . H., Geol. SGC. Am., M e m . 67, 87 (1957). Greenhalgh, R., Riley, J. P., J . Marine Bid. Assoc. U. K . 41, 175 (1961). Griel J. V. Robinson, R . >.,J . Marine Res. (Sears Found. Marine Res.) 11, 173 (1952). Igelrud, I., Thompson, T. G., J . Am. C,$em. Sot. 5 8 , 200 (1936).
Kairenskii G. N. Tr. Lab. Gidrogcol. hrobl. Akad. Nauk. S S S R 16, 285 (1958). Koczy G Oesterr. Akad. Wid., b;bt 11-A, 158, 113 (1950).
Viscosity
VOL. 5 6
Saint-Guilv, B., Ibid., 235 8 9 3 (1952). Smith-Rose R. L. ~ P r o c . Roy. Sac. ’(Londoi) A143, 135 ( 1 9 3 3 ) .
k,,
NO, 7
JULY 1964
47
Processes which combine chemical reaction with physical economic in nature and principally involved with finding uses for the large volumes of salt mixtures arising from such rough separations, as contrasted with the single element process which produces a smaller volume of material with well defined markets and uses. I n addition, there are the multiproduct processes in which are combined several subprocesses for the production of single elements, mixed salts, or both. Distinction between these types of processes is maintained in this article. -Element Produced. Of the six major elements included in Table I, processes for the production of all but sulfur are reviewed. Single element recovery processes can be arranged conveniently into recovery of halogens, recovery of the four major metal constituents (Ca, K, Mg, Na), and recovery of some minor and trace components (B, Au, Ag, Cu, and heavy metals). -Separation Methods. The separation methods employed in the various processes described in the literature are well known for the most part from their applications in the process industries. I t is apparent, however, that successful utilization of some of these techniques in minerals recovery from sea water will require novel ideas concerning combination of such techniques with each other and methods of operation. For this reason a general discussion of some suggested separation methods is given in a subsequent section. -Market Considerations-Supply, Demand, and Price. The combination of economic factors which affect the marketing of a product is very important, but varies depending on the time, place, over-all economic situation, local demand, and other circumstances. I t is not possible, thus, to arrive at generalized economic conclusions for a given process other than those of a most broad nature (i.e., the production of fertilizer will probably be more attractive than production of sodium chloride). Even these generalizations may not always hold true. One reference to the subject, by an author who arrives at a rather pessimistic conclusion, does merit comment. Ellis (G6) reviewed in 1954 the products which were then being recovered from the ocean, and presented information on some of the important questions concerning possible salt recovery from desalination plants. A discussion of the potential value of the chemicals recovered concludes that “if just one 1000 m.g.d. fresh water plant were built somewhere in the world, it is not certain that enough chemicals could be sold at a profit sufficient to make any appreciable contribution to the water purification costs.” I n support of this rather general conclusion, the sale of several components at then prevailing U. S. selling prices was discussed. As an example, it was shown that the amount of lithium which might be removed from 1000 m.g.d. (about 340 tons per year as lithium oxide) was comparable to the 1940 consumption rate (750 tons per year). This may be an unfortunate example, since there are quite a number of other considerations involved. Many current 48
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
plant capacities are in the 1-10 m.g.d. range rather than 1000 1n.g.d.; not all fresh water plants will include salt recovery processes. I n addition, it is doubtful that lithium would be considered as a potentially attractive product in most cases. There is no doubt, however, that desalination facilities do provide a source for very large volumes of recovery products. The amount of salt available is presented in Table I. Some estimate of total supply and consumption of materials which can be recovered, primarily for the United States, can be found in texts such as Shreve (GI@, but current Department of Commerce, foreign government, and United Nations publications are far more comprehensive and up-to-date sources, for both domestic and foreign markets. -Mineral Concentrations in Sea Water-Natural sea waters have been reported with chlorinities ranging from 16 to 22 per cent, but brine effluents from desalination plants may well have chlorinities in the 40--60 per cent range. Most processes which have been described in the literature are concerned only with the treatment of natural sea water. The application of some of the techniques developed for natural sca water to mineral recovery from concentrated brine effluents appears to be a fruitful area for investigation.
Separation Methods
There are seemingly an endless number of separation techniques and there is little agreement on methods of classifying them except that they are generally considered to be applications of interphase mass transfer. Generally, classification by unit operation (denoting
TABLE IV.
SEPARATION METHODS
____
Sefiaration Method
Subsequent References
Table Number
1, Precipitationa
9-17, 19
2. 3.
6-10, 18, 1 9 9 13, 14 6, 9, IO, 12, 13 12, 19
4.
5.
Electrolysis Electrodialysis Adsorption Ion Exchange
6. Chelationb 7. Oxidation 8. Chlorination 9. Solvent Extraction 10. Solar Evaporation a
6,8 7, 8.19 13 9, 10, 15, 1 9
___~-
Process n’umber
~
1 10, 13, 17-19, 21, 22. 27, 31-43 1, 4, 8, 11>16, 44 11 24, 28-30 1, 12, 15, 23, 25 20
2, 7 3, 5, 6 26 9, 14, 32
Precifitation or crystallization is usually followed by jiltration.
There
are three major ways of causing preclpitation: by addition of chemicals;
b-v coolinz or freezing; sequestering ageiits.
by heating or evaporation.
Use of selectiae
separation are the most promising for the future purely physical separation techniques such as filtration or distillation) and unit process (denoting the combination of chemical interactions with the unit operations) has been used most widely, and is used here. The primary methods which have been suggested for mineral recovery from sea water are given in Table IV. I t is apparent that a very diverse range of techniques has been considered, and as will be seen later, this range is considerably increased by the fact that separation methods are often used in various combinations, rather than singly, in many proposed processes. The principles of these methods are widely available in the handbook and textbook literature (G70, G17, G78, G22). Several studies have been made of the recovery of salt from sea water, but with emphasis on widely variant aspects of the problem. Lovering (G72) and others ( G I , G9) have discussed mineral resources in sea water, and a review of some problems involved in utilization of mixtures and brines has been given by Pel’sh (G76). Reviews of some specific separation methods in application to minerals recovery are given by Fischbeck (G7) and Vouch (G23), and there are many short reviews of current water-salt separation methods and technology such as (G4, G8); more detailed material is available in recent Office of Saline Water publications. Much information of potential interest to the design of processes for salt recovery is presented primarily for the purposes of desalination plant design. There is no source yet available which consolidates any of this material with application to salt recovery processes. I t is notable that most of the proposed processes involve physical rather than chemical separation methods, but it is even more notable that the two processes which are currently in commercial operation (magnesium and bromine recovery) are based on chemical reactions with physical separations carried out in subsequent steps of the process. The chemical reaction is carried out in order to obtain the material which it is desired to recover in a form which facilitates physical separation from the brine solution ; this normally involves production of a two-phase mixture from the original homogeneous liquid phase such that the desired material is found in only one of the two phases. Thus, the commercial magnesium process requires precipitation of the hydroxide (G78), a recently developed method for making fertilizer involves precipitation of
J . A. Tallmadge is Associate Professor, J . B. Butt is Assistant Professor, and Herman J . Solomon is a Research Assistant in the Department of Engineering and Applied Science, Yale University. The authors express their appreciation to the Pratt and Whitney Company, West Hartford, Conn., and the Ofice of Saline Water for the sufiport of this work. AUTHOR
TABLE V.
GENERAL REFERENCES
( G I ) Armstrong, E. F., Smithsonian Rept. 1943,135; (CA 39,847-4; 38,2139-4). (G2) Armstrong, E. F., Miall, L. M., “Raw Materials from the Sea,” Chemical Publ. Co., New York, N . Y., 1946. (G3) Carritt, D. E., Dept. of Geology and Geophysics, Mass. Inst. Tech.; personal communication, October 17, 1961.
(G4) Cioil and Struct. Eng. Rev. 11, 393 (1957).
(G5)Dunseth, M. G., Salutski, M. L., IND.ENG.CHEM.56, No. 3, 56 (June 1963). (G6) Ellis, C. B., and associates,“Fresh Water from the Ocean-for try, and Irrigation,” Ronald Press Co., New York, N. Y., 1954.
Cities, Indus-
(G7) Fischbeck, K., Chirn. Ind. (Paris)79, 563 (1958). (G8) Gillman, J. L., Jr., Chem. Enp. Progr. 53, 68 (1957).
(G9) Kilpi, S., Suornen Kumirtilehti19A, 177 (1946);
(CA 41, 4977f).
(G7O) Kirk, R. E,, Othrner, D. F., “Encyclopedia of Chemical Technology,” Interscience, New York, N. Y., 1954-61. (G77) Lange, N. A. “Handbook of Chemistry,” 10 ed., p. 1107, McGraw-Hill,
New York, N. Y.,’1961. (G72) Lovering, T. S., “World Population and Future Resources,” American
Book Co., New York, N. Y., 1951.
(G73) N $ o n a l Regearch Council, “The Physical and Chemical Properties of Sea Water, Publication N 600.
(G74) Office of Saline Water Annual Report, U.S.Dept. Interior, 1960. (1275) Office of Salire Water Res. and Dev. Prog. Rept., “A Standardized Procedure for Estimatin Costs of Saline Water Conversion,” No. PB 161376, Office Tech. Services, U.S.%ept. Commerce. (G76) Pel’sh, A. D., Khirn. Nauka i Promy. 2, 734 (1957); (CA 5 2 , 10513g). (G77) Perry, J. H. (ed.), “Chemical Engineers Handbook,” 4 ed., McGraw-Hill, New York, N. Y., 1964.
(G78) Shreve, R . N., “The Chemical Process Industries,” 2nd ed., McGraw-Hill, New York, N. Y., 1956. (G79)Sverdrup, H. U., Johnson, M. W., Fleming, R . H., “The Oceans,” PrenticeHall, New York, N. Y., 1942. (G20)Ibid., pp, 51-52. (G27) Ibid., pp. 176-177. (G22) Treybal, R. E., “Mass Transfer Operations,” McGraw-Hill, New York, N. Y., 1955. (G23) Vouch, G., Chirn. Ind. Agr. Bid. 18, 226 (1942); (CA 38, 4761-5).
the product through treatment of sea water with phosphoric acid and ammonia (G5), and the authors are presently engaged in research on a proposal for the recovery of potassium from sea brines by selective precipitation with dipicrylamine. From the evidence a t hand, one must conclude that continuing progress in minerals recovery will depend more on development of combination reaction-physical separation processes, truly the “unit processes” in the time honored sense, than on improvements of the separation methods (unit operations) alone. Economics of Salt Recovery Processes
The primary reason for interest in the recovery of minerals from sea water, under present circumstances, is to provide a source of income which can be used to reduce the cost of producing fresh water in desalination plants. Additional benefits may be derived as well, for example the fertilizer process (G5) is designed to remove scale forming elements from the feed to sea water conversion plants. Evaluation of the economics of a given separation and recovery process is a highly specific thing, probably more so in this application than most such evaluations. One must consider the potential market of the product to be made, the type and cost of the desalination plant with which the process is to be operated, and the capital requirements of the process itself as the VOL. 5 6
NO. 7
JULY
1964
49
Processes for recovery of halogens from sea water are among fundamental factors to be studied. I t rapidly becomes apparent, however, that the economics of salt recovery are largely governed by marketing considerations. The number of products which can be made from sea water appears to be very large, and from the point of view of current technology this is so, but it must be kept in mind that products with sufficient market are required in order that their return can contribute significantly to the reduction of sea water conversion costs. Technical problems, capital costs, and general process complexity involved in recovery of some of the less abundant minerals tend to reinforce this point, and thus the number of feasible products is not large a t all. I n general, recovery processes have some inherent advantages over more conventional methods of production of a given component (in particular a large amount of free raw material), and also disadvantages (the concentration of the component in the raw material). Those recovery processes which operate on brine effluents from desalination plants partially compensate for this disadvantage, and would almost certainly be more attractive than corresponding processes operating on raw sea water. I t is very difficult to make any more profound pronouncements than these concerning the general economic aspects of mineral recovery simply because the problems and the analysis involved are very specific to individual cases. The Halogens
One of the four halogens-bromine-is of special interest because it is currently recovered on a large commercial scale from sea water. Some processes have been proposed for direct chlorine recovery, but the most feasible method appears to be the use of well known electrolytic methods employing brine solutions obtained from evaporation of sea water. There have been, apparently, no proposals made for fluorine recovery from sea water. Recovery of Chlorine. Chlorine is the most abundant element in sea water, and its relatively high concentration has engendered interest in its recovery from this source. Most of the studies reported have involved the recovery of chlorine in combined form, however, and these are discussed in subsequent sections on recovery of major metals (chlorine is recovered in the form of sodium, potassium, or calcium chlorides in several schemes for recovery of these metals) and on mixed salts (chlorine appears as a constituent of a multicomponent product in which only a very crude separation is obtained between various salt products). I n effect, chlorine has been recovered for some time on a commercial scale from sea water. Caustic sodachlorine production by electrolytic processes has been carried out in California using salt obtained from the evaporation of sea water. The salt is made up into 50
INDUSTRIAL AND E N G I N E E R I N G CHEMISTRY
brine solutions and purified: normally by the addition of sodium carbonate to remove calcium and magnesium. The details of such processing are similar to causticchlorine production from naturally occurring brines. Production of chlorine from sea water by this method is certainly feasible at those locations where cheap methods of evaporation (;.e., solar evaporation) are available. Some modifications of the basic electrolytic process have been proposed for specific application to sea water. Electrolysis combined with ion exchange ( H I ) has been suggested; a brine solution is electrolyzed to give sodium hydroxide and chlorine, the hydroxide is treated with an anion resin in chloride form to yield more salt for electrolysis, and the resin is regenerated with sea water. Chlorine is the only product of this process, since the caustic produced is used as an internal recycle stream for brine production from the ion exchange step. Another electrolytic process (H2) proposes the addition of the sodium hydroxide product to untreated brine in order to raise the p H . The free chlorine in solution which is produced is then removed by air. Recovery of chlorine by direct oxidation with potassium permanganate or a hyposulfite has been studied on a small scale (H3),but such a process is rather unrealistic in view of the cost of the treating agents required. The processes for electrolytic production of chlorine and caustic soda from naturally occurring brines, or from salt deposits, are very widely employed and are described in other sources (G70, G18, H 4 ) . The most feasible method of chlorine recovery from sea water is, as described above, a modification of this employing brines obtained from sea salt. Recovery of Bromine. Prior to the development of an economic process for recovery from sea water, bromine was principally obtained from mined bromide salts. At present, the commercial extraction of bromine from sea water is accomplished by displacement of the bromide ion with chlorine, resulting in free bromine dissolved in the water. Free bromine is then stripped from the solution and recovered. This process is described in textbooks ( H 4 ) and in the literature (H5). Bromine recovery from concentrated brines is carried out on a commercial scale in Germany, Russia, Italy, Israel, and the United States. The original process for bromine recovery from sea water was developed by Du Pont, and the first plant, appropriately enough, operated on the high seas under the name of the S. S. ETHYL. I n this process, sea water was acidified to p H of 3 to 4 and chlorinated to liberate bromine. The free bromine in solution was recovered by addition of a dilute aniline solution to precipitate tribromoaniline. Bromine in the desired form was then recovered from the tribromoaniline (H6, H7, HZO). A subsequent process, developed by Dow Chemical Company, is essentially that in use today. Acidified
the few now economically feasible TABLE
VI. CHLORINE RECOVERY PROCESSES
Process No.
I ~
Location Process
1
References Materials
i
I
2
Japan Electrolysis, ion exchange
U.S.S.R. Oxidation
(H7,HZ)
(H3) Brine, oxidizing agent Lab
Sea water, anion
Size Reference
Chemical Abstracts
(H7)
43, 5317g
Original Citation
Nakahara, S., Sueta, H., Yamamura, T., Japan. Patent 175,044 (1958). 49, 1 6 3 7 4 ~ Takahara, M., Aoki, H . , Japan. Patent 5814 (1954). 50, 115706 Matusevich, V. F., Zinov’eva, V. F . , Veterinnriyn 34, 69 (1956).
(H2) (H3)
TABLE V I I . Process NO.
B R O M I N E RECOVERY
I
3
Location Process
Chlorine displacement ( H 4 to H31) Chlorine, sea water, or brine Commercial
References Materials Size Chemical Abstracts
...
28, 3189-9 23,5014-7 27,1999-9
... 27, 4636-; 27, 111 0-2 31, 322%: 33, 822-1 27,4636-8 30,77894 43, 5515e 35,6074-5 51, 6962e 42, 6068j 50 16053,f 47, 7741g 40,4184-7 32, 9409-6 30, 5002-2
... ... ...
... ... 52, 176386 42, G996f 43, 8622g 45, 5047d 53, 8895J 35, 6074-8
PROCESSES
4 Electrolysis
1
(H32, H33) Brine Lab
Original Citation Sconce J. S. (ed.) ACS Monograph No. 154, Reinhold: New York,’1962. Shreve, R . N ,, “Chemical Process Industries,” 2nd e d . , g : 426, McGraw-Hill, New York, 1956. Kirk E. Othmer, D. F., “Encylopedia of Chemical Techholngy,” Vol. 1, Interscience, New York, 1954. Stewart, L. C . , INn. ENC.CIIEM.26,361 (1934). S h e , M. A,, Ibid., 21,434 (1 929 ). Grebe, J. J., U. S. Patent1,891,888 (1932). Rohertqon, G. R., IND.END.CHEM.34,133 (1942). Grebe, J . J., Boundp, R. H., Chamberlain, L. C., U . S.Patent 1,917,762 (1933). Ibid., 1,885,255 (1932). Grebe, J. J., Boundy, R. €I., Can. Patent 364,742 (193’). Grebe, J. J., Chamberlain, L. C., U. S. Patent 2,133,616 (19383. Curtin, L. P., Thordarson,W, Ibid., 1,916,094 (1933). Hanne, M., Genie Civil 108, 347 (1936). Spada, A . , AttiSoc. Not. M a t . Modenu 7 8 , 4 4 (1947). Williamson, A. T., U. S. Patent 2,245,514 (1941 ). Matsushima, Y., Japan. Patent 1121 (1956). Kaltenbach, M., French Patent 861,183 (1941). German, F. F., Kkim. Prom. 1956, p.171. Bock, R., Hackstein, K. G . , Ckem. Ing. 7ech. 25, 215 (1953). Chamagne, G., Genic Ciuil120, 221 (1943). Stewart, L. C., Trans. Can. Inst. Mining M e t . 41, 443 (1938). Schmidt, E., La NntLre 1936, 292. TND. ENO.CHEM.Sup. 27A (1957). Hart, P., Chem. Eng. 54, 102 (1947). Heath, S. B., U. S. Patent 2,143,224 (1939) Hooker, G . W., Ibid., 2,143,224 (1939). Tennant, W. J., Brit. Patent 523,607 (1940). Stasinevich, D. S., Zh. Prikl. Kkim. 31, 701, 844 (1958). Nagi, R., Kogyo. Kagoks Zasshi 4 6 , 858 (1943). Ishikawa F. Kohata Y . , Bull. Inst. Phys. Ckem. Res. (Tokyo? 57 (1944). Inoue, S . , Japan. Patent 177,354 (1949). Reznik, S., Israel Patent 10,3YO (1958). Urbain 0. M . , Stemen, W. R., U. S. Patent 2,24;,645 (1941 ).
d,
sea water of p H 4 is oxidized by chlorine to liberate bromine (H9); the sea water solution is passed countercurrently to a n air stream in a packed tower to strip out the free bromine ( H 5 ) . A similar process has been used with more concentrated brines; the bromine is removed by steam rather than air ( H 8 ) . Bromine is removed from the air stream by reaction with SO2 and absorption in an aqueous phase. Activated charcoal has also been used to remove bromine from the air (H9, HIO, H77). A large number of modifications to the basic process have been proposed and patented from time to time. Some of the more interesting or important of these include the use of C O Srather than acid to adjust sea water p H (H72), extraction of bromine with cracked gasoline stock instead of air (H73),conversion of bromine in the air to ferric bromide with subsequent reduction of the iron by coke (H74), and variations on the recovery step from air utilizing alkali solutions rather than activated carbon (H75, H76, H77, HIE). The use of chlorine water rather than gas for the displacement step has been suggested to reduce the adverse effects of magnesium and calcium interference where more concentrated brines are used (H79) and activated carbon saturated with adsorbed chlorine has also been proposed as a means of carrying out the displacement step (H34). Additional discussion of the “DOWProcess” is given by a number of authors (H27 to H28). Theoretical analyses of various aspects of the chlorine displacement reaction have been given by several workers. For the fundamental reaction involved : 2Br-
+ Cl:!
$ Brz
+ 2C1-
Stasinevich (H29) has reported interphase distribution coefficients and gas and liquid phase equilibrium constants. The equilibria determined for this reaction are very favorable, though decreasing with increasing temperature. Values of 1.75 X 10’0, 2.2 X 109, and 8 X 108 were determined for displacement in the gas phase at Oo, 2 5 O , and 40’ C., respectively. The effects of pH, temperature, organic impurities, chlorine concentration and foreign ion concentration on the displacement reaction have been studied by Nagi (H30) and Ishikawa and Kobata (H37), and much data are available in the handbook and textbook literature. Electrolytic processes for the recovery of bromine from sea water and brines have been patented, but are not successful competitors of the chlorine displacement method and have not been used commercially. One of these proposed a chlorine displacement with electrolysis (H32), another suggested an electrolytic method for bromine recovery from Dead Sea bitterns (H33). The majority of bromine produced is used in the manufacture of ethylene dibromide used in motor fuel additives. Supplementary information concerning bromine production is contained in some sources dealing with the manufacture and use of antiknock fluids. VOL. 5 6
NO. 7
JULY 1 9 6 4
51
Recovery of Iodine. The recovery of iodine from sea water has been practiced for many years with the aid of nature. Although iodine occurs only to about 0.05 p.p.m. in sea water, certain brown seaweeds selectively concentrate iodine up to a maximum of about 0.5y0 of their weight. Dried seaweed is burned and the residue leached with water (H35). The resulting solution, after separation from insoluble materials is then evaporated to crystallize out alkaline earth salts ; the iodine retained in the mother liquor can be recovered by a variety of methods. The process is no longer of great commercial importance, although it is apparently still in use. Some of the methods which have been proposed for iodine recovery from sea water are essentially extensions of the methods proposed for bromine recovery. When bromine is liberated by chlorination, iodine is oxidized to the iodate ion; after removal of the bromine the iodate can be reduced to free iodine by treatment with ferrous chloride and removed by air blowing as in the case of bromine. Iodine is recovered from the air stream by absorption in a sodium hydroxide or carbonate solution (H36, H37). The use of activated carbon, saturated with adsorbed chlorine, has been suggested for iodine recovery (after the previous removal of bromine) by displacement in the same manner as mentioned previously for bromine (H34). Extraction of iodine from naturally occurring brines found in California oil fields (iodine concentrations in the range of 10 to 200 p.p.m.) is carried out commercially and has been discussed in detail by Sawyer, Ohman, and Lush (H38). A chlorine displacement method is often used for this recovery. Oxidation processes have also been discussed as a means of production of iodine, presumably after bromine has been removed. Treatment with sulfuric acid (H39) and nitric acid (H40), ozone (H47), and nitrous oxide (H42) have all been proposed, though not tested on a large scale. Process proposals involving electrolysis have been made but, as in the case of bromine, do not appear to be as attractive as the chlorine displacement method. Naturally occurring underground brines of higher iodine concentration than sea water have been electrolyzed using a platinum anode and solution p H of 7.6 to obtain molecular iodine (H43). I n another method, a copper anode and somewhat lower p H (1.6) is used to obtain cuprous iodide on electrolysis, which is then sublimed to produce iodine (H44). Electrodialysis using a porous carbon anode has been suggested (H45). The production of iodine from sea water or sea brines appears to be feasible as a step following the removal of bromine, using the same methods. Iodine, however, is available in large quantities from the Chilean nitrate deposits and recovery from sea water does not appear economically competitive at the present time. The Major Metal Constituents
Of the four major metals found in sea water, magnesium, sodium, and calcium are all commercially recovered 52
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
TABLE V I I I . Process No.
I O D I N E RECOVERY PROCESSES
1
5
~
I
1
I
6
I
7
~
U.S.A., U.S.A. U. S.S.R., Japan France Chlorine dis- Chlorine dis- Oxidation
Location Process
1
8 Japan, France Electrolysis ( H 4 3 to H45)
... sea water, or brine
~
activated carbon
0 8
Lab
(H36)
(H37) (H38)
41, 1072g 44, 8086
...
(H3Q)
33, 4750-6
(H40) (H47) (H42) (H43)
33, 41, 49, 51, 48, 30,
(H44)
(H45)
4750-6 1818c
12792d 41782 6295h 2860-2
TABLE I X . Process No.
Cranston, J., U. S . Patent 2,412,390 (1946). Sakamoto, Y., Japan. Patent 174,103 (1946). Sawyer, F. G., Ohman, F. G., Lush, F. E., IXD. E s o . CHEM.41, 1547 (1949). Denisovitch, B. P., Stetsenk, .A. A , , U.S.S.R. Parenr 49,059 (1936). Ter-Oganesyan, S. N., Ibid.,51,126 (1937). Gogorishvili, P. V., 15id.: 66,684 (1946). Gloess, M . P. P., French Patent 984,500 (1951). Kawanami: T., Japan. Patent 418 (1956) Obara, U., Itid., 2626 (1953). Vi& E . , French Patenr 790,396 (1935)
SODIUM RECOVERY PROCESSES
Y
Location
Process
References
1I
10
77
I
72
U.S.A., Asia, Japan, Japan Japan Africa U.S.A., India Solar evapo- Precipitation Electrolysis, Ion exelectroration change dialysis ( N I , AT) ( A V 4 to iv7) ($8 to (Ai14 to 1\73) 'V15)
Materials Products Size
Crude XaCI Commercial
Chemical Abstracfs
...
bittern See text Lab, pilot plant
See text Lab
See text Lab
Originai Citation
Stewart, L. C., Chem. I n d . (London) 41, 15 (1937). . .Cimirzg M e t . En,grs. 18, Seaton, M. Y., T m n r . ~ m Inrt. ... 11 (1942). Charruy, P., Bull. Soc. Sci. lVoncy 18, 138 (1959). 53, 22772h Aikawa, H., Kato, Y., Japan. Patents 132,465 T O 132,467 35, 3399-a (1939). Cady W.R. Julien, A , P., Saunders, D. J., U. S . Patent 51, 4667e 2,7k4,472 t1956). Kane, G. P., Kamat, B. K.. India Patent 46,740 (1953). 47, 10185h Wiseman, J. V., U. S. Patent 2,784,056 (1957). 51, 91086 Nakao, S., et al., Japan. Patent 2267 (1952). 47, 6284e Kume, T., Records Occanog. Wor4s Japan 12, 57, (1957). 51, 15307h Imamura, M , , Izawa, S., Japan. Patent 8774 (1956). 52, 15311g Inoue, S.: Ibid.,175,522 (1948). 44, 7680i 51, 15312g Xakazawa, H., Atsugi, T., Onoe, K., Ibid., 4026 (1955). 51, 124.51~ Nakazawa, H., Ibid., 2615 (1955). Yamamura, T . , Somiyama, Y., Ibid., 181,089 (1949). 46, 3228c Sueda, H., Nakahara, S., Yamamura, T., Japan. Patent 43, 69266 175,043 (1948). 55, 17302j Kume T. Hisano T. Izawa, H., Record5 O c e n n q . W a ~ k s , J a f i h ~ . )Spec. , N o : 4,'135 (1960). Izawa, S., Kasaka, Y., Kisaki, H., Kogyo Kagaku Znrsht, 55, 195596 61, 787 (1958). Pukha, R., Tr. Vses. Nauchn. Issled. 1959, KO. 36. 322. 55, 14839f
from sea water, although the latter two are normally produced in rather crude, mixed salt form. Magnesium is of particular interest because it is the only element whose recovery from sea water currently represents a significant portion of the world’s production. Much of the interest in salt recovery from all types of saline water (sea water, bitterns or salt water concentrates, and brines) has been directed toward these four major metals. I n discussion of sodium and calcium recovery, a n arbitrary distinction has been made between the processes mentioned here and those later classified as mixed salt recovery processes. Recovery of Sodium. Sodium is the second most abundant element in sea water, and currently is produced commercially as crude sodium chloride by the solar evaporation of sea water. Bitterns from this evaporation process are used subsequently for the production of bromine and magnesia ( N 7 , N 2 ) . Sodium is always recovered in a combined form. Charruy ( N 3 ) has recently given a general discussion of some methods of sodium salt recovery from sea water.
salts are precipitated, and high quality sodium chloride is obtained from the mother liquor by evaporation and crystallization. Potassium chloride is removed with the sodium chloride at higher concentrations (iV6). Sodium bicarbonate can be produced from treatment of brine with carbon dioxide ( N 7 ) in another process; this material is then heated to regenerate a portion of the carbon dioxide and give a carbonate product. These chemical treatment processes have been developed for use with brine, not sea water, and their adaptation to treatment of the latter is not really warranted in comparison with the simple evaporation process. Two electrolytic processes are worthy of mention. Nakao ( N 8 ) reports the electrolysis of sea water at a lead oxide anode with the production of a sodium hypochlorite solution; Kume ( N 9 ) has investigated the efficiency of production of sodium hydroxide from sea water by electrolysis with mercury electrodes. The electrolytic methods proposed for chlorine recovery (H7, H2) also have application here since sodium compounds are involved as coproducts. In general, the
Solar evaporation at Leslie Salt Go., San Francisco, Calif
Aside from the commercial solar evaporation method, precipitation, electrolytic, and ion exchange processes have also been tested on a small scale (see Table I X ) . Processes using forced convection evaporation and subsequent crystallizations are used for salt recovery from brine solutions, but large scale application to sea water has not been reported. -4typical adaptation of this method to sea water is reported by Aikawa (h’4), with evaporation producing sulfate precipitates in the hot liquor and chlorides as carnallites (potassium and magnesium) precipitating upon cooling. Sodium sulfate is produced by refining the sulfate precipitate. There are a large number of chemical treatment methods which can be used to produce solid phases containing sodium compounds. Cady (iV5) reports the use of sodium sulfate, calcium carbonate, and calcium hydroxide to purify brines; magnesium and calcium
outlook for the use of electrolytic methods of sodium recovery from sea water is not very bright (as is the case for chlorine) in view of the raw material situation discussed below and the availability of much cheaper processing methods. Some further discussion of this is given in a later section. Electrodialysis methods have also been investigated. In one process (,Y70, .1771). sea water is purified b) magnesium removal and fed to the anode while sodium bicarbonate is fed to the cathode; the two electrodes are separated by a sulfonated anion resin. The net transfer of sodium to the cathode produces a saturated solution of sodium carbonate, and bicarbonate is regenerated and recycled from a portion of the carbonate product. Unfortunately, the power requirements reported (“1.7 kw.-hr./ton bicarbonate) are not very helpful in determining the efficiency of the process in VOL. 5 6
NO. 7
JULY
1964
53
TABLE X.
MAGNESIUM RECOVERY PROCESSES
Process No.
Process
References Materials
!
Commercia1
Chzmicni Abstrocts
37, 5559-5 34, 860-6 38, 1612-7 55, 23949 46, 7724j 49, 29096 46, 11597e 46, 679% 50, 17357e 5 5 , l0808f
... 50, 14193d 33, 7497-9
76
75
___.
Japan
Italy
Israel
Solar evapo- Ion exchange Electrolration ysis (hIS.9. 12160) ( M 6 7 ) ( M58 ) ...
Salts, metal 1 MgCle
Products
Xp/erencp
74
73
USA, England, Germany, LT. S . S.R. Precipitation ( M I to ‘M5, M16,M77) Dolomite, etc.
Location
Size
Kagai, S., Yoshizaki, K., Komatsu, S., J.Ctrom. ;Iisoc. J a j a n 6 2 , 3 2 5 (1954). Takashim+ S., Records Oceonog. W o r k s .Jupan, Spec. .Vo. 3, 145 (1959). 55, 25175~ Terada. M., T o k j ’ o R o g p Shikeniho Hokoku 54, 310 (1959). 52, 6735d Fujii, K., Iwbe, K . , Japan. Patent 1317 1957). 47, 13461, Nakatomi, K . , Sakatani, Y . ,Ibrd., 2711 and 2662 ( l ? i l ) . 43, 6795i Kiwa. S.. I h . . 172,596 (1946). 47, 895Oe Scailles. J. C., French Palent 980,707 (1951). 49,1797d Seailles, J. C , C . S. Patent 2,587,001 (1952). 42, 6068h Seailles. J. C.. French Patent 862,074 (1941). Scoles, L . IV,,U. S. Patent 2,479,138 (1949). 44, 2925 43, 2798h Green, W. H., McBride, G. A , , Hertzing, G. A , , Ibid, 2, 458, 261 (1949). 41, 8410 Clark. I>. M., Robinson. J. G., Brit. Pntent 571,276 (1945). 38, 5372-5 Pr)cherch. IV. E . , I6id.. 553,731 (1943). 48. 78581 Sugi, J . , PI oi., Japan. Patent 2281 (1953). Skogseid. A , , Norway Patent 74,138 (1948). 43, 6374d 52, 84796 Forb;ith,T. P., Chmi. E n g . 6 5 , N o . 6, 112 (1958). 49, 2 6 9 3 Ii’oodwzird, T., U. S. Palent 2,695,242 (1954); 2,571,983 (1951). 49, 98940 C l x k e , R. E., Collings, N. R., Ibid.,2,703,748 (19.55) 48, 110216 Dodd, A. F,,, Cerumm, 474 (1953). Britton, H. T. S.: Gregg, S. J., ’iVilling, E. G. J., .1. 47, 5643g .4ppi. Chem. 2 , 7 0 1 ( 1 9 5 2 ) . 47, 2444d Seailles, J. C . , French Patents 975,099 a n d 971,237 (19 5 1). 47, 45G8d Kuhlmann, E. T., Ibid., 884,976 (1943). 46, 7724,’ Vettel, .4. W.,Israel, R . D., U.S. Patent 2,595,314 (1952). 44, 27 11’, Thorp, H . W., Gilpin, 1%‘. C., Soc. Chem. Ind., Ciiem. B n g . Group, Oct. 25 (1949). Xagai, S., Fukumori, Y . , J.Czram. Assoc. Jo/>an61, 152, 47, 10821f 266 (1953). 51, 1 8 5 0 2 ~ Goldberg, A,, Bull. Res. CouncilIsruei 5 0 , 1 2 2 (1955) 50, 11863g Rohm & Haas Go., Brit. Patent 738,520 (1955). 49, 4953d Dancy, I V . B., MacDonald, R. A , , U.S. P a t e n t 2,687,339 (1954). 41, 575i Hunter, hl. J., Biiuman, W C., Ibtd., 2,409,861 (1946). 39, 5417-1 Douglas, M., Refractories J . 21, 11 (1945). 31, 3641-7 Manning, P. D. V., Chem. M e t . Eng. 43, 116 (1 936) Nishikawa, Y., Japan. Patent 5504 (1956). 52, 8922d 55, 14838, Takahima, S., Akiyama, R., Okamoto, K . , .Vippon Shio Gakkaishi 10, 117 (1956). SociCtC des Prod. mar. du Pouliguen, French Patent 46, 8337d 971,919 (1951). 45, 10153d Axt, M., Piremyst Chem. (28), 482 (1949). 45, 5375c Galimberti, L., Spinedi, P., Stein, A. M., Ann. chim. npplrcato 39, 572 (1949). 50, 14188g Davidenko, h-.K., U k r o i n . Rhini. Ziiur. 21, 773 (1955) 5 5 , l5850e Babachiev, G. N., Popov, h.1. A , , Khim. Ind. (,So/in) 32, No. 6, 167 (1960). 46, 224c Piromallo, A,, Ital. Patent 460,207 (1950). .4kabori, S., e t nl., Japan. Patcnt 179,562 (1949). 45,105221 47, 127756 Shirakabe, S., Ibid., 4468 (1952). 51, 18500d Schacher, O., Huii. Res. CouncilIsrael 5C, 100 (1955). 43, 481% hntonena, C. M., Ilol. Inform. Petrol 25, No. 285, 1 1 (1948). 38, 1611-8 hlandel, R . A,, T T .Inr!. H o h r g ~ i1940, KO. 18, 47. 48, 13177d
55, 588111
...
C 0 ; i and lime, or waste liquor MgHCOs or
MgCL Lab
Bitterns
Mg(OH)z Lab
Ori,yinai Citations Stireve, K. N., “Chemical Process Industries,” 2 n d e d , , p . 224, McGraw-Hill (1955). Chem. M e t . Eng. 48, No. 11, 130 (1941). h?urphy, W., Chem. Ind. 49, 618 (1942). Schambra, W. P., Trans. A.I.Ch.E. 41, 35 (1945). Spiro, N. S., T r , Akad. Nauk Ukr, SSR 3 8 , 7 9 (1940). Spiro, N. S., Buil. Inst. Hdiurgii 3,21 (1938). Spiro, N. S . , Trudy Inst. Hailur ii 8, 5 (1940); and Khtm. Rzferat. Zhur. 4, No. 9, 106 f1941). Spiro, N. S., Tr, T7m. Nauchn. Issled. Inst. Galiirgii 36, 281 (1959). Vettel, A. W., Israel, R. D., U. S. Patent 2,595,314 (1952). Aravamuthan V., Bid/. India Sect. Eiectrochem. Sac. 3, 45 (19543. Gil in rV. C., Heasman, N., Rejruc:’octories J. 2 8 , 302 (?9
