Kegs of G r a n u l a r Iodine Being Labeled at Seal Beach Plant, The Dow Chemical C o m p a n y
IODINE from OIL WBLL BRINES A StaffdndzcstrN CoUaborative Beport
e
e
M.F. OHMAN FREDERICK G. SAWYER
The Dow Chemical Company, P i t t s b u r g , Calif.
in collaboration w i t h
FRED E. LUSK
Associate Editor
The Dow Chemical Company, Seal Beach, Culif. ?
T
HE recovery of chemicals from sea water has inspired a constant flow of Sunday newspaper supplement stories
*
ever since The Dow Chemical Company released information on how they made the sea give up its bromine and magnesium. Much less has been said about t h a t company’s process for obtaining iodine from subterranean brine or “fossil sea wafer.” Iodine, t h e least abundant of the halogens, occurs in nature largely as iodides and iodates. The water solubility of these compounds plus the leaching action of rain have resulted in very littie iodine being found in the soil. Constant transport by the rivers of the world has resulted in the oceans being vast storehouses of the element t o the extent of 60,000,000,000 metric tons (IO). This quantity is startling when it is realized that eea water contains less than 0.1 p.p.m. of iodine. This concentration of iodine is so low that direct treatment of sea water for iodine recovery would be very costly. However, some forms of marine life extract iodine from sea water, and thus are probably responsible for the commercially useful concentrations in which this element is found in seaweeds, brine from oil wells, and the Chilean nitrate beds.
Prior to the discovery of iodine in the Chilean nitrate beds, the world’s supply of iodine was obtained largely from seaweed ashes by treating with sulfuric acid and manganese dioxide or some other oxidizing agent t o liberate the free element. Japan is again entering the world iodine market as a major produ’cer, using seaweed as the raw material. At present, most of the iodine produced in the world, excluding the United States, is obtained from Chilean saltpeter, which contains from 0.05 t o 0.1% iodine as iodates of sodium and calcium. The recovery process involves treating the saltpeter with sulfuric acid t o yield iodic acid, which is then reduced with sulfurous acid. The resulting iodine must be purified by sublimation. About 1,500,000 pounds of crude iodindare consumed in the United States every year. A large percentage of this quantity is converted to potassium iodide which is used extensively in the manufacture of photographic materials and animal feeds. The remainder of the iodine is consumed largely for pharmaceutica preparations, dyes, and iodized salt. Exports of potassium iodide, resublimed iodine, and other iodine products account for the consumption of around 300,000pounds of crude iodine per year.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
1548
T H E UNITED STATES IODINE INDUSTRY
The story of how the United States has moved toward becoming self-sufficient in iodine is intimately interwoven with the activities of The Dow Chemical Company. It all started back in 1926 when a chemist, C . W. Jones, located a brine containing iodine in Louisiana. This brine came from a well which was primarily an oil producer. The Dow Chemical Company became interested in this development and incorporated the Jones Chemical Company as an affiliate. Spurrad on by the high iodine price of $4.00 to $5.00 a pound, the company decided to produce iodine in Louisiana by a process developed by Dow. A well was drilled into the iodine-brine strata and a processing plant was located a few miles from Shreveport, La. On August 2, 1928, began America’s initial extraction of iodine from salt brines as well as commercial production of potassium iodide ( 5 , 6 ) . Until 1932, the company continued using a blowing-out process, in which a current of air blew the iodine out of acidified and oxidized brine ( 1 2 ) . I n the meantime, the General Salt Company in 1929 began extracting iodine from oil field brines in the Signal Hill district of Long Beach, Calif., using a charcoal process. The brine was acidified and oxidized whereupon activated charcoal adsorbed the liberated iodine which was then extracted with p u s t i c soda or caustic potash t o yield asconcentrated solution of the desired element. General Salt Company shut down in 1934 after Chile cut the price of iodine t o $1.50 a pound. Another firm, the Deepwater Chemical Company, started recovery of iodine from oil field brine a t Dominguez, Calif., using the silver process under license from The Don. Chemical Company which had been granted a patent in December 1931 (11). By improved technology and efficient silver recovery, Deepwater still operates and competes in the iodine market. The process chemistry can be expressed as follows:
+ + + +
-
Ag HxOs --+ AgK’Os NaI AgNOl AgI JNaS03 2AgI Fe -+Fe12 W g 2Fe12 3c12 --+ 2FeCI3 212
+
+ +
I n 1932, the Jones Chcmical Company, Inc., decided to close its Louisiana plant and move the operation t o California. On July 28, 1932, just 26 days after construction had begun a t Long Beach, Calif., the plant mas ready for production. Two factors were responsible for the move. The first was the high iodine content of the available brines (60 p.p.m. compared with Shreveport’s 35). Secondly, it m-as not necessary to pump the brine wells because a brine usually accompanied the flow of oil being pumped by the producers. For every barrel of oil brought
Vol 41, No. 8
Figure 2. Flow- Sheet of Recovery of Iodine from Oil Field Brine a t the Seal Beach, Calif., Plant of The Dow- Chemical Company-
-z to the surface, some of the older nells produced an accompanying 10 barrels of brine. Sormally, the disposal of this material hy the oil companies would create a serious problem inasmuch as the regulations of the California Fish and Game Commission make it unlawful to dump oil-contaminated brines into the ocean Any process that nould clarify this waste so that i t could be discharged into the ocean without fear of creating a contamination hazard and a t the same time recover a valuable material was certainly nelcome t o the area. The Jones Chemical Company plant a t Long Beach finally did that, and more. Its output was felt on the American market. The 1932 price of iodine dropped precipitously (Figure 1). A year later i t was down to $1.50. A low of 80.81 was reached i n 1936 after Chile suddenly slashed prices. I n the meantime, in 1933 The Dow Chemical Company became sole owner of the iodine recovery business. I n 1935, the price of silver rose to $0.64 an ounce ( 8 )(Figure 1). Since the company had adopted the silver proeees described above at the time of its move to California the combination of higher metal cost and lower iodine prices forced active research toward improvement of the blowing-out process Pilot plant work in 1935 matured a year later into a full scale plant using t h r blowing-out process, A few months later another plant wab built a t nearby Venice, Calif. By 1939, the company wab processing 15,000,000 pounds of brine a day ( 6 ) One result of the Chilean price war was the freezing out of all iodine manufacturers in thc United States except Dow and Deepiodine operation was water. Paradoxfcal as i t may seem, DOIV’S not profitable until after the price dropped below $1.00 a pound. This coincided with the introduction of the improved blowing-out process. I n 1941, t h e Long Beach plant was moved to Seal Beach. Because of the growing domestic and export demand for iodine, Dow executives decided t o erect a new plant a t IngleTTood, a few miles from Venice. Engineering work was started in January 1946, and the plant was in produrtion on August 21, 1947. All three plants collect brine from adjacent oil fields, but Venice and Inglewood do not process iodine to the finished product. A eoncentrstted liquor is transported in rubber-lined trucks to Seal Beach for finishing (4). Here over 90% of the domestic elemental iodine is made, along mith a large percenlage of the potassiuni iodide (7)BRINE COLLECTIOS
c
SILVER EL IODINE PRICES
Oil field brines can vary, depending on the locatmionand strata tapped (Table I). The iodine content provides a convenient and rapid means for identifying the eone from which the brine is being produced in a known oil field. Analyses show that the bromine content of these brines is roughly tm-ice that of iodine. This is in marked contrast with sea water which cont,ains approximately 65 p ~ p ~ m bromine . but less than 0.1 p.p.m. iodine (Table 11). The sodium chloride content is about t,he same a s in sea, wa,ter and appears to have no
TABLE I.
YEAR
Figure I
I O D I N E CONTEh‘T OF’
Location in California Signal Hill Seal Beach Alamitos Heights Venice (shallow zone, 4000 ft.) Venice (deep zone, 6000 f t . ) Santa Fe Springs
TYPICAL OIL FIELD BRIXEY P.P.M. 50 85 65
135 10 12
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Vol. 41, No. 8
quality brine in large quantities at one delivery point. I n fields where there are many small independent producers Dow has built extensive brine gathering systems for collecting and diRposing of their brines in lieu of royaltie?. Because the Seal Beach plant is the only one of the three Dow plants in Southern California that embraces the complete iodin^ process, it rid1 be the one described in detail, The recovery process can be divided into three stages: brine cleanup; iodine blowing-out and recovery; and iodine finishing (Figure 2 ) . The Venice and Inglewood plants carry oui only the first two s t e p . BRINE CLEANUP
The composite brine (usually 62 to 67' p.p.ni. of iodine) passes through a series of skimming tanks. Each tank is 100 feet in diameter and protected against corrosion by suspended DOWmetal (magnesium alloy) anodes. The dirty oil skimmed from the brine cornpiises primarily heavy ends and is sold as road oil, The brinc a t a pH of about 7.5 is thcn pumped to a, standard elariflocculator ( 1 ) which is 86 feet in diamPrecipitation Tanks and Connections to Rectangular Filters eter and also protected by Dowmetal anodes. Approximately 30 p~p.m"of ferric chloride solution is added to flocculate oil, silt, and other impurities, Any appreciabIe quantity of organic matter left in the relationship t o the iodine content. These oil field brines also brine will interfere with the oxidation step later in the process, contain about 70 p.p.m. of barium as soluble salts. where the liberated iodine apparently combines with unsatuThe brine comes to the surface from some wells at a temperarated organic compounds, causing a5 much as 10 to 20% iodine ture of about 70' C. By the time i t arrives at Seal Beach i t may loss. Sludge drained-off a t t,he bottom of the-xooden settling tank be as cool as 30" C. Brines may contain from 10 t o 158 p.p~m. is sent to a pond. iodine. Analyses of four brines of commercial value are given Sulfuric acid is added t o the clarified brine and the pH brought in Table 111. under 3.5 to ensurc complcte iodine liberation during the oxidaDepending on volume, the pipe lines that gather brine from the tion step. This also precipitates the soluble barium present in oil fields are 4 to 12 inches in diameter. These lines are subject to the brine. The settling tank is made of Oregon pine, 54 feet in considerable corrosion. Liming has been tried in an attempt to diameter and 20 feet high. The barium sulfate sludge is sent to a build up a protective calcium carbonate scale but was unsuccesspond a t present, its quantity being too small to be marketed ful. Transite pipe solved the problem and is gradually replacing the existing steel lines. economically, The clarified brine then goes to a myooden sand filter 15 feet in Royalties are paid to the oil companies who can furnish high diameter. .Two of these in pmdlel permit periodic backwashing. The corrosive nature of the brine and various acid liquors encountered in the next tR-0 stages of the process required the use of acidproof equipment lined with materiaIs such as rubber or TABLE 11. SEA WATEE ANALYSIS ( 9 ) Saran. Element
P.P.M.
Element
P.P.M.
~
.leiurn Potassium Bromine Carbon Strontium Boron
400 380 65 28
13 4.6
Lithium Phosphorous Barium mine Arsenic
0.1 0.001-0 10 0.05 0.05
0,01-0.02
TABLE111. ANALYSES OF TYPICAL OIL FIELDBRINES Iodine Sodium Calcium Magnesium Barium Chloride Bicarbonate Sulfate Silica Iron oxide and
Brine -4 (IS), Brine 93 ( 3 ) , Brine C ( 2 ) , Brine D (14), P,P.M. P.P.M. P.P.M. P.P.bI. 35 75 70 50 9,413 552 29 1
i6,ibo 464 8
60
10,800 624 255 81 18,069 861. 25
. . ~
9,000 154 42
9,407 361 211
li,840 2,170 26
I$,iOO 792
.).
4;
7
~
AND ~
~
E
W~
The filtered brine is then pumped to a blowing-out tower and while the brine is in transit chlorine gas is injected in amounts somewhat in excess of the theoretical ratio of 0.28 pound of chlorine per pound of iodine. The oxidized brine then passes into the top of a steel blowingout tower lined with acidproof brick and i s stripped by a countercurrent flow of air through ceramic ring packing. '@he stripped brine is discharged t o a sewer leading to the 8an Gabriel river ahich runs alongside the plant. All of the oil has been removed so there is nothing in the discharge to contaminate the river or coastal waters. The oil producers who pipe their brine to the n o w plants would otherwise be forced by- Ian*to install cleanup equipment Absorption of the blown-0u.e iodine takes place in another packed tower. The absorbing liquor, a water solution of hydrogen iodide and sulfuric acid, passes down through the packing countercurrent to the stream of iodine-laden air coming from the blowing-out tower. Water and sulfur dioxide are added continuously to the hydro-
~ ~
INDUSTRIAL AND ENGINEERING CHEMISTRY
August 1949
1551
gen iodide'sulfuric acid liquor t o reduce the free iodine absorbed according t o the following chemical equation:
1 2 (ais)
+ SO2 + 2H20 +2HI + HzS04
A portion of the continuously circulating hydrogen iodidesulfuric acid liquor is bled off and sent to the iodine finishing operations. The iodine-stripped air goes back t o the blowing-out tower to pick up more iodine from the oxidized brine. This stripped air is recycled to avoid fouling the atmosphere with fumes and t o prevent evaporative cooling in the stripper. The stripping of iodine is accomplished more efficiently when the brine is hot because of increased volatility. IODINE FINISHING
The hydrogen iodide-sulfuric acid liquor bled off passes t o an acid brick-lined conical precipitating tank, 10 feet on straight side and 10 feet inside diameter. Chlorine is bubbled in directly through Pyrex tubes in stoichiometric amounts (0.28 pound per pound of iodine) accompanied by moderate propeller agitation. Iodine is precipitated according t o the following reaction:
2HI
+ Clz + + 2HC1 12
The precipitated iodine is drawn off the conical bottom through a porcelain valve and into a wood box filter on the bottom of which is a filter cloth of woven Saran. Canvas duck cloth was used originally and gave satisfactory service for only 1 week. The present Saran cloth has been in use for several years.
Enamel Pots to Form 200-Pound Ingots
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Chunks of Iodine Are Fed to Crusher Equipped with Laminates Maple jaws; Crushed product Weighed into Wooden Kegs
The filtrate is extremely corrosive, comprising a dilute solution of hydrochloric acid and sulfuric acid, saturated with free iodine. This liquor is pumped back to acidify the clarified brine. The wet iodine cake is transferred from the filter to a heated kettle. Strong sulfuric acid (over 60%) is added and the iodine settles as a layer on the bottom of the kettle. Prolonged heating at 120" to 160' C. melts the iodine. The acid chars residual organic impurities and removes water. After this operation is completed, the trunnion-mounted kettle is tilted and the decanted sulfuric acid is returned to acidify the clarified brine a t the beginning of the process. The molten iodine is drawn from the kettle and allowed t o solidify in enamel-lined slop sinks. The approximately 200pound ingots are cooled, crushed, and packaged in wooden kegs each containing 200 pounds of the finished granular product. This is sold as crude iodine a t a purity of 99.8y0. The more stringent requirements of certain pharmaceutical preparations are met by subliming the material. This is not done a t Seai Beach. The iodine is shipped t o New York and St. Louis warehouses where it is distributed to chemical supply houses. More than 800,000 pounds of the element are produced in California each year (16). This supplies almost half the needs of the United States, the remainder being supplied by Chile and Japan. Sufficient quantities of oil field brine are available in this country so
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
that in an emergency, the entire iodine requirement could be obtained from domestic sources. PROCESS CONTROL
T h e incoming raw brine is continuouslg sampled and the 24hour composite analyzed for iodine. These samples are then titrated potentiometrically. Hourly analyses check the iodine concentration (6 to 10 p.p.m.) in the brine going to the sewer. At both the Seal Beach and Venice plants, t,he control of acid, chlorine, and sulfur dioxide addit,ion is manual, guided by p H and oxidation potential recording instruments. A11 controls are cmmpletely automatic a t the Inglewood plant.
Vol. 41, No. 8
cant. A small quantity is used for backwashing the sand filter. The efficiency of iodine recovery varies between 88 and 92y,, depending largely on brine temperature. Processing from brim to keg requiies 7 2 hours. Coriosioii is the major problem of maintenance in the iodine plants due to the nature of the liquors throughout the entiiepiocess. Widespread use of rubber and Saran linings has helped to minimize this problem. The Inglenood and Venice plants operate 24 hours a day, 7 days a week. This is also true for the brine cleanup, iodine blowing-out, and recoveiy operation a t Seal Beach. The finishing operation-that i q , from iodine precipitation to product, runs 8 hours a day, 5 days a week. Supervision consists of a manager, assistant manager, superintendent, and assistant superintendent for all three plants. Potassium iodide is also madc a t Seal Beach. Iodine is reacted with high grade caustic potash to form potassium iodidc and potassium iodate. A solution of these salts is cvaporatcd to dryness and then brought up to the melting point in a gas-fired pot. The iodate is reduced to iodide and any organic matter is burned out. The iodide is aolidified, broken up, redissolved in water, and treated to remove heavy metals and other impurities. Subsequently, the solution is filtered through a plate-andframe press, evaporated, and cooled to form crystals. The crystals are centrifuged, washed, dried, and packed in 15-pound bags, 20 bags to a barrel. Most of this highly purified potassiuni iodide is used in the manufacture of photographic films. T H E FUTURE
Dow is now producing about five times as much iodine as 111 1932. The product, non selling a t $1.52 a pound, has a stable niarlret. Dom- has been succesbful in meeting Chilean competition, but since World War 11,Japanese production from seaweed has again become a factor in the market. The price i s not high enough nor the demand great enough to induce other domestic companies to enter the field. S o r has there been enough price incentive to warrant extensive research and development programs because present operations are quite efficient and satisfactory. Any drastic change in the supply-demand picture could come only from the discovery of new uses for iodine compounds. Perhaps methyl iodide has promise as a fire extinguisher, 01’some of the other alkyl iodides as interniediates for fine chemicals. Some day thc most retiring of the halogens, iodine, may come into its own, as has its energetic brother fluorine. I n the meantime, the general picture of the Dow plants is one of quiet, stable, efficient operation making i t possible for the United States t o be independent of the foreign supply of an important element. Crude Potassium Iodide and Potassium Iodate Being Loaded into the Smelter
The flow of chlorine is controlled to maintain the proper oxidation potential a t a sampling point just after the pump discharge on the inlet line t o the blowing-out tower. This oxidation potential is measured by a platinum electrode to ensure that all iodine is in the free state. The sulfur dioxide addition to the absorber liquor is eontrolled similarly to ensure that all iodine in t h e absorber liquor is reduced. Chlorine added to the precipitation tank in similarly controlled to ensure that all iodine is liberated. Temperatures are recorded a t various points throughout the plant, but no attempt is made to control the process thereby. Service requirements are low. A small steam boiler supplies the steam, Dow doesn’t even have to buy natural gas to fire the boiler. A company-owned brine well produces gas along with the brine. Only occasionally is space heating necessary in the mild chill of winter. The vvater requirements are also insignifi-
LITERATURE CITED
Dorr Company, New York, N. Y . , Dorr clariflocculator. Doumani, T , F., ‘Union Oil Co. of Calif., letter (May 25, 1949). Doumani, T. F., Union Oil Co. of Calif., letter (June 7, 1949). Dow Chemical Co., Bear Facts, 5, No. 9, 3 (1948). Dow Chemical Co., Dow Diamond, 1, No. 2, 27 (1937). Ibid., 2, No. 3, I1 (1939). Ibid., 7, No. 6, 4 (1944). Eng. &: M i n i n g J., 150, No. 2, 82 (1949). Fisher Scientific Co., Laboratory, 17, No. 4,102 (1948). Hopkins, B. S., Bailar, J. C., Jr., Essentials of General Chemistry,” p , 160, Boston, D, C. Heath & Co., 1946. Jones, C . W., U. S. Patent 1,837,777 (1931). I b i d . , 1,863,621(1932). Osborne Laboratories, Raymond G., Los Angeles, water analysis of Signal Hill and Los Cerritos Oil Fields, letter (June 25, 1948). Smith-Emery Co., Los dngeles, Calif., laboratory report (Wov. 29, 1948). State of California, Div. Mines, Dept. Natural Resources, “Mineral Industiy of Cnlifoinia in 1947,” p. 12. RECEIVED J u n e 1, 1949.
