Staff-Industry C O LLABORATIVE R E P 0 R T BRUCE F. GREEK, Associate Editor
in collaboration with FRANK W. BLESS, Jr., Coastal Chemical Corp., Pascagoula, Miss., and
ROBERT S. SIBLEY, The Fluor Corp., Ltd., Los Angeles, Calif.
St. Gobain Processes. . . Phosphoric Acid and Phosphate Fertilizers
Somm
farm economics are causing growers of all types of crops to demand more plant food per unit weight of fertilizer handled. Result-a highly significant, yet relatively little known, change has been underway in the fertilizer industry-an important part of the chemical industry when measured either in dollar value or tonnage of its products. This change is the building of new plants and revamping of older plants to make high analysis fertilizers (plant food content 30y0 or more). High analysis fertilizers are estimated to account for more than 4070 of total U. S. consumption which amounted to 25,143,000 tons in the year ending June 30, 1959 ( 7 ) . This tonnage represents an 11.77, increase over the 1938 year. Mixed fertilizers reached a new peak in consumption in the 1958-59 year, partly indicative of the acceptance and demand for high analysis materials. One part of the country which consumes large amounts of fertilizers is the South Atlantic and South Central states. I n 1958-59 farmers in these areas consumed over 1 1-million tons. Ideally located to tap a large part of this market area is Coastal Chemical Corp.'s new integrated fertilizer plant near Pascagoula, Miss. Coastal Chemical is a subsidiary of Mississippi Chemical Corp., Yazoo City, Miss. Coastal Chemical has a 1350-acre plant site with 1500 feet of deep water
channel frontage. The site is part of Bayou Casotte industrial district located near Pascagoula, Miss. The deep water channel connects with the intercoastal waterway as well as with the Gulf of Mexico. Prior to organizing Coastal Chemical in 1956, Mississippi Chemical studied several forms of high analysis fertilizers that might meet farmers' needs. Of those studied, ammonium phosphate was selected because of its greater water solubility and because a farmer receives higher return on his fertilizer investment. Integrated Plant. With an over-all plan to use basic raw materials-natural gas, sulfur, and phosphate rock-Coastal broke ground in 1957 to begin construction of a $12 million integrated fertilizer plant. The first unit completed was a 400 ton-per-day nominal capacity sulfuric acid plan1 designed by Titlestad Corp., of h-ew York, and erected by M. T. Reed Construction Co., Jackson, Miss. The sulfuric acid plant will make up to 600 tons per day when necessary. A 75 ton-per-day design capacity phosphoric acid plant and a granulated fertilizer plant were next
When Coastal Chemical's St. Gobain plant was undergoing shakedown trials it looked like this. At right i s the rockacid reactor with i t s fume scrubber. The horizontal vacuum filter was not yet installed so the knock-out drums for traveling pan filter may be seen. At left are the cyclones to take out dust from the air leaving the dryer
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INDUSTRIAL AND ENGINEERING CHEMISTRY
engineered and constructed by The Fluor Corp., Ltd., Los Angeles, Calif., using processes developed by Compagnie de Saint-Gobain of Paris, France. The fertilizer plant has a capacity of 350 tons per day of 14-14-14 (nitrogenphosphorus-potassium) grade; capacity varies widely depending on grade manufactured. Then followed a 200 ton-per-day ammonia plant built by Chemical Construction Co.? h-ew York, N. y . , a 500 ton-per-day superphosphate Broadfieldtype traveling den by the Atlanta Utility Works, Atlanta, Ga.: and a 400 ton-perday TVA-type ammoniator-granulator unit by the D. M. Weatherly Co., Atlanta, Ga. The TVA unit is used to make low analysis fertilizers. During its first year of operation, Coastal Chemical produced about 63,000 tons of fertilizer, changing grades 30 times. In that year, 6-24-24. and 1216-16 sold best. Other grades that sold well included 14-14-14, 16-20-0, and 6-18-18-3 (Mg). I n the 1959-60 year, about 62,500 tons have been produced. I n addition 30,000 tons have been made in the TVA unit and 25,000 tons in the
den; these units together made about 10,000 tons in the previous year. Most popular in 1959-60 year is 6-24-24, followed by 13-13-13. Large quantities of 12-36-10 were exported. In 1958-59, Coastal sold 50,000 tons of high analysis fertilizers in an area which previously had used about 10,000 tons a year. This ready acceptance of these fertilizers by consumers who had used mostly conventional low analysis grades makes the future look bright indeed for Coastal.
dicalcium phosphate above 1.O:
M a n y Reactions Involved
R a w Materials
Basic chemistry of fertilizer manufacture is relatively simple. The reactions involved are those of making sulfuric acid from sulfur, ammonia from natural gas and nitrogen, phosphoric acid from phosphate rock upon acidulation, and neutralization of phosphoric acid and sulfuric acid with ammonia. Potassium comes to the finished fertilizer by a physical process. But the side reactions, stemming mainly from the materials with which the phosphorus is associated, are complex. Their proper control will determine the profit or loss in fertilizer manufacturing, all other factors held constant. For example, the phosphate rock used by Coastal contains tricalcium phosphate tied up with calcium fluoride as a fluorapatite molecule. Silica and calcium carbonate are also present in substantial amounts. With sulfuric acid, the rock reacts:
Coastal's plant uses four major raw materials-sulfur, phosphate rock, potash, and natural gas. Sulfur and phosphate rock arrive by water, and potash by rail. Molten sulfur comes from Port Sulphur, La., by barge; is pumped to tanks and stored in liquid form. Phosphate rock is brought in by barge from Florida. Several rock producers supply Coastal with 75 BPL (bone phosphate of lime, equal to 34% PzOS) at an average rate of 300 tons per day. Delivered cost is about $10 per ton. Potash, ready for use in the final granulation step, comes from New Mexico. Consumption averages 70 tons per day. Coastal buys natural gas from United Gas a t a rate of 6 million cubic feet a day. Practically all gas goes to make ammonia. Process steam is made a t the sulfuric acid plant using heat from burning sulfur and the acid-making reactions.
3Ca~(POa)z. CaFz I- lOH2SOd 6H3P04 2HF lOCaSO4
Controlling Reaction Conditions
H3POa
at those ratios
+ Cas04 + 2NH3 + 2Hz0 CaHP04.2Hz0
-
+ (NH&S04
These reactions produce water-soluble ammonium salts and small quantities of sparingly soluble salts (mostly phosphates). The latter are citrate-soluble, however. Thus practically all of these products are available in the fertilizer as plant food.
--f
+
+
4
The calcium fluoride-sulfuric acid reaction is a reversible one. Hence the amount of acid added to the rock becomes a critical factor. The hydrogen fluoride reacts with silica. I t in turn may undergo a double decomposition reaction with any sodium or potassium salt present in the rock to make a potentially difficult to handle precipitate :
+ 2H20
6HF f Si09 + HzSiFG HzSiFfi
+ NazSOl-
NazSiFG J.
+ HzSOa
Calcium carbonate produces carbon dioxide on acidulation. This gas effervescing in the reaction vessel may cause a foaming problem. Other side reactions appear in the neutralization process. Any fluosilicic acid remaining as an impurity neutralizes to its ammonium salt. Iron, aluminum, and magnesium sulfate impurities present in the phosphoric acid start to precipitate as phosphates at an ammonia-phosphate ratio of about 0.85. When the ratio goes over 1.0, precipitation is complete. Gypsum in the phosphoric acid will revert to the
Close control of conditions, particularly in the manufacture of phosphoric acid, is the key to economics in a high analysis fertilizer plant, This means efficient use of raw materials and production time. Coastal grinds its phosphate rock to 6570 through 200 mesh. This fine grind gives a high initial rock-acid reaction rate with 80% of the rock digested in 30 minutes. However, total hold-up time in the reaction tank ranges between 4 and 8 hours. Figure 1 shows the relation of reaction time and extent of reaction. In theory, the most economical use of sulfuric acid would be that which would leave none in either the product phosphoric acid or by-product gypsum. In practice some excess acid is always necessary. Figure 2 shows how a low amount of excess acid would produce a gypsum very difficult to filter, and a large excess of acid slows the reaction. Controlling the amount of excess acid a t just over 2% provides the optimum operating range. Temperature control also proves important to process efficiency. Figure 3 indicates the temperature limits to make
Figure 1. While 8OY0 o f the ground phosphate rock reacts with sulfuric acid in the first 3 0 minutes o f contact time, the normal hold-up time in the reactor tank i s four to eight hours
the best possible gypsum for easy filtration. Normally constant temperatures make the best crystals. Coastal maintains the reaction slurry in the 165" to 175' F. range to make maximum quantity of rhombic crystals that filter and wash quickly. Heats of reaction and dilution add more heat than is needed. Thus, the reaction rank is cooled by air blown into the slurry and taken Out through a fume scrubber. St. Gobain Processes
One of the major reasons for Coastal's selecting the St. Gobain process is the lower capital investment required for a plant of given capacity. An important investment saving is in use of the single reactor for making phosphoric acid. Allied to savings with the single reactor are other savings from fewer pumps, lines, and auxiliary equipment needed. Ground phosphate rock, stored in a 350-ton capacity hopper, is conveyed (17E) continuously from the bottom of the hopper through a closed circuit back to the top. At an appropriate point in the circuit, a gravimetric belt feeder (72E) takes off what is needed for immediate reaction and the remainder continues to storage. On a normal operating day, the feeder discharges about 12 tons per hour of rock into a chute over the reaction tank (Figure 4). A recycle stream of filtered phosphoric acid of medium strength, 20 to 25% P205, wets the rock and washes it down into the tank. At the same time approximately 10 tons per hour of 93 to 98y0 sulfuric acid VOL. 52.
NO. 8
AUGUST 1960
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INDUSTRIAL AND ENGINEERING
CHEMISTRY
Staff-Industry 100
I
I
I I
OPEA
I
OPERABLE ZONE OF
I I 95
l
I
'
I
I
h
I
I
j 2
I FREE H z S O 4 ,
3
YO
I
- - -oo l 10
40 %
Figure 2. Excess free sulfuric acid in typical phosphate rock needed for optimum digestion of the rock ranges around 1.5%
is fed continuously into the tank. 'The acid mixes immediately with a recvcle stream of phosphoric acid-gypsum slur 1.s from the filters. An automatic control valve ( 7 E ) regulates acid flow. A ratio controller (8E) ties in the control valve with the gravimetric belt feeder to keep acid and rock feeds in the proper ratio. About 2.6 tons of sulfuric acid will make a ton of PzOb. Both streams come into the reaction tank a t such points that the tank agitators quickly disperse the two streams and prevent any short circuiting to the slurry pump inlet. A suction fan (3E) pulls cooling air across the surface of the slurry to keep the reaction slurry a t about 165' to 175O F. The warm air and noxious gases released during the reaction pass through a fume scrubber (75E) to the atmosphere. Brackish water pumped from Bayou Casotte through the fume scrubber knocks out small amounts of hydrofluoric acid present in the off gases. The water from the scrubber goes to a dilution pond and then back to the Bayou. No pollution problems exist. Heavy rainfall on the Gulf Coast makes for high dilution of water returned to the Bayou from either the scrubber or from the gypsum disposal area. The water itself is very low in acids or other materials. Fish are caught from Coastal's wharf, an indication of how little pollution occurs in the Bayou. However, marine life presents a problem for Coastal. Oysters foul the intake line for brackish water. They are controlled by addition of small amounts of chlorine occasionally. A vertical centrifugal pump (74E) submerged in the slurry withdraws slurry
from the tank a t a 330 gallon-perminute rate. The amount of slurry to be filtered, adjusted by demand, goes through a hand controlled valve. The unfiltered portion returns to the reaction tank via the mixing ripe for fresh sulfuric acid. The slurry for filtering goes to the teed distributor of a 192 square foot traveling pan vacuum filter (6E) containing 42 pans and to a horizontal filter (5E). In each filter effectively the same steps take place :
\I
GYPSUM,CoSOq ZH20
\I 50
Pp 0 5
Figure 3. Keeping the reactor temperature between 165' and 175" F. (75" and 80" C.) permits maximum reactivity yet causes stable gypsum crystals to form which filter easily. A flow of cooling air offsets heats of reaction and dilution of the sulfuric acid
E
O
0
SIDE
As the pans or filter sections move, initially strong (30 to 34% P206) phosphoric acid comes off. Cake thickness ranges between 1.5 and 2.5 inches.
The St. Gobain Reaction Vessel Coastal Chemical's phosphate rocksulfuric acid digestion process uses only one tank. It is made of steel, lined with acid-proof brick. Efficient agitation is produced by both the method of adding the recycle slurry-acid mixture and by four turbine agitators. The return slurry goes down through a funnel-like structure, driven by a vertical propeller. Cooling air enters the tank through spargers connected to a circular manifold around the top of the tank. An exhaust fan pulls the air over the slurry and out through a fume scrubber where hydrofluoric acid is removed. A submerged pump takes out the slurry which is either filtered or recycled with fresh sulfuric acid mixed in it.
TOP
-. \\1 Figure 4. A special system of agitators and baffles provides the intimate mixing that permits use of a single reaction tank in the St. Gobain phosphoric acid process used by Coastal Chemical 1. 2. 3.
4. 5.
Bricklining Funnel to ensure good mixing of f e e d rock and acid Turbine agitators Cooling air spargers Air manifold
VOL. 52, NO. 8
AUGUST 1960
641
Gypsum cake begins to fall from the traveling pan filter here. The water wash may be seen at center; behind it i s the weak phosphoric acid wash liquor distributor
In the second section, the filter cake of gypsum is washed by weak acid produced in the third section. This wash acid, now medium strength, is the recycle phosphoric acid used to \vet and wash the ground rock into the reaction tank. The third section consists of a wash with 150' F. water to make the weak (5 to 10%) phosphoric acid used for the second stage wash.
phosphoric acid when it is needed more concentrated than from the filter for making very high analysis fertilizers
less expensive and more basic raw materials can be used; and superior product quantities of water solubility and harder, smoother, and more homogeneous granules are possible.
A horizontal filter adds about 30 tons per day to the plant's capacity. It has a capacity of 1.1 pounds of P2O.j per square foot per hour. The traveling pan filter produces about 3.9 pounds of PZOS per square foot per hour. Filters operate under 15-inch Hg vacuum. Polyethylene filter cloth is used. Product acid goes through a thickener and then to storage. Settled gypsum goes back to the reaction tank. The washed, dewatered gypsum filter cake of 20 to Z5Y0 moisture discharges from the end of the filters. I t has a total PzOs content of 0.6 to l.Oyo. The cake is slurried with plant waste water and pumped to a 100-acre diked area for disposal. About 530 tons per day of wet cake are produced. When needed for efficient manufacture of very high analysis grades, some of the phosphoric acid from the filters is concentrated in a single effect evaporator (78E) to 5470 P2O6. The evaporator uses natural convection flow. An ejector using steam from the sulfuric acid plant produces u p to 27 inches of Hg vacuum. Ammonium Phosphate Fertilizers. Coastal selected the neutralization and granulation method for making fertilizers over dry mixing or granular wet mixing methods for two ma.in reasons-
642
A Swenson single effect evaporator concentrates the filtered
INDUSTRIAL AND ENGINEERING CHEMISTRY
Wash Out Procedure The single reactor of the St. Gobain phosphoric acid process permits a simple washout procedure. In making phosphoric acid, a scale containing largely calcium fluosilicate forms in lines, filters, and auxiliary equipment. This scale is removed by periodic washouts. Coastal Chemical's washout procedure goes like this. Feed to the reactor is shut off. Agitators are left on, but cooling air is cut off. The slurry left in the reaction tank does not change appreciably during a period of 1.5 hours. Hot water is pumped ta the filters in place of slurry. Water also goes through the lines carrying the three concentrations of phosphoric acid from the filters. Water from washouts goes to the plant sewer system. Start-up is merely by switching over from water to slurry. Coastal now washes about 1.5 hours in every 24 hours.
Fluor placed emphasis in design on key variables and on a minimum of superfluous extras to make the neutralization and granulation section of Coastal's plant operate very efficiently. Recoveries greater than 97Yo on nitrogen and 99y0 on other constituents are expected when addition of proper scrubbing equipment is completed. Phosphoric acid is pumped from either of two 75,000-gallon storage tanks and merered to the first neutralizer tank. The acid feeder is a bucket-wheel type (73E) run by a variable speed drive continuously to permit regulation of acid delivery at a constant and uniform rate. Sulfuric acid comes to the first neutralizer also through a similar feed arrangement. The two acids in rhe proper ratio for the grade being manufactured are fed to the first neutralizer. The tank is partially filled with a partly neutralized slurry. Liquid anhydrous ammonia is continuously added beneath the slurry level through several spargers. The ammonia addition rate will permit about 807, of the neutralization to occur. An operator checks the extent of neutralization by either a pH measurement or a titration, depending on the grade manufactured. The slurry in the first neurralizer continuously overflows into the second neutralizer. Here the balance of the needed ammonia is added. The operators control again by either an on-thespot p H measuremenr or titration. From the second neutralizer. the slurry overflows into a third. This vessel acts mainly as a slurry surge tank. Ammonia may be added, however, if any deficiency exists.
Staff-lndustr y Processing Equipment
Broyeur, A., France, roll grinders. Buffalo Forge Co., 465 Broadway, Buffalo 4, N. Y., centrifugal blower, Type BA. Ibid., centrifugal fan, Type LS. Coastal Chemical Corp., Pascagoula, Miss., Weir box. Dorr-Oliver Co., Inc., 99 Havemeyer Lane, Stamford, Conn., horizontal filter. Ibid., traveling pan, Giorgini vacuum filter, No. 18. , Fischer & Porter Co., 51 Warminster Road, Hatboro, Pa., flow recorder-controller with diaphragm control valve. Foxboro Co., The, 86 Neponset Ave., Foxboro, Mass., ratio-controller. Hardinge Co., Inc., 240 Arch St., York, Pa., gravimetric constant weight belt feeder. Lawrence Pumps, Inc., 363 Market St.,Lawrence, Mass., horizontal rubber-lined centrifugal pump. Link Belt Co., Dept. T E 60, Prudential Plaza, Chicago 1, Ill., belt conveyors, bucket elevators. Omega Machine Co., Inc., Division BIF, B-I-F Industries, Inc., 399 Harris Ave., Providence 1, R. I., Omega gravimetric belt feeder. Ibzd., Omega Roto-Dip feeder. Pepinster, Belgium, Ensival vertical, packless submerged pump. Schutte & Koerting Co., 2233 State Road, Cornwells Heights, Bucks County, Pa., vertical spray tower, No. 4030 fume scrubber system. Standard Steel Corp., 5025 BoyIe Ave., Los Angeles 58, Calif., dryer, combustion chamber, cyclone separators, and granulator. Stephens-Adamson Manufacturing Co., 275 Ridgeway Ave., Aurora, Ill., Redler conveyors. Swenson Evaporator Co., Division of Whiting Corp., 15613 Lathrop Ave., Harvey, Ill., single effect evaporator. W. S. Tyler Co., 3618 Superior Ave., Cleveland 14, Ohio, Hum-mer Type 38, step tandem screens.
Exothermic heat of the neutralization brings the slurry temperature near the boiling point (220" to 260" F.) for many grades manufactured. Considerable water evaporates, especially from the first neutralizer. An exhaust fan ( 3 E ) evacuates vapors from the three vessels through a fume scrubber (75E) to the atmosphere. As several grades require that ammoniation be carried well into the diammonium phosphate range, appreciable ammonia may pass through the slurry unabsorbed. Acidified water circulated through the scrubber recovers this ammonia. A slip stream bled off from the circulating stream returns the recovered ammonia to the first neutralizer. A Weir box (4E) limits flow back to the first neutralizer. Granulation and Drying. Slurry from the third neutralizer is absorbed in a bed of dry recycle fertilizer material moving through a rotating shell granulator. The 6 feet diameter by 16 feet long granulator rotates a t a speed of 4 to 10 r.p.m. depending on grade manufactured. I t provides a tumbling action to coat the recycle material with a thin film of slurry to produce a smooth hard granular product. This operation ip similar to a drum coating operation. T o give optimum coating thickness several slurry variables need controlling. Coastal uses a slurry near boiling temperature. Its moisture ranges between 20 and 3201, depending on grade. T h e pH or ammoniation ratio also depends on grade, At this moisture range and temperature the viscosity permits good wetting. A rotary dryer (76E), 11 feet diameter by 70 feet long, turning a t a fixed rate of 4.5 r.p.m., dries the granules to less than 1% moisture. A 150-hp. exhaust blower (2E) induces the draft for the dryer. Exhaust air temperature ranges between 175" and 230" F. depending on grade. Dryer retention time is about 10 minutes. T h e dryer discharge is elevated to a pair of double deck vibrating screens (79E)for classification. Two grinders (7E) pulverize the oversize. The product-stream (-6 to12mesh)fromthelower screens divides; part goes to storage, bagging, and shipping, and the remainder recycles back to the granulation circuit. The combined excess product, fines passing through lower deck screens, pulverized dust, and dust from the dryer constitute the recycle to the granulator. Potash, when needed, is fed into this stream through a weigh feeder (72E). Spent air leaving the dryer goes through a first-stage cyclone dust collector which drops out the bulk of the entrained solids through a n air-lock valve onto the recycle conveyor ( 7 723). The remaining dust is removed by a dust scrubber (75E) by spraying with
water. A common pump (7OE) circulates water through this scrubber and the neutralizer fume scrubber. It is the slip stream from this system that returns to the first neytralizer. T o make the maximum of high quality product size (-6 to 4-12 mesh), Coastal depends on maintaining the proper ratio of slurry to dry recycle or wetness of granulator discharge. This is done by adjusting the amount of product withdrawn from the circuit using a weigh feeder ( 9 E ) in the product line with a remotely controlled variable speed drive. No surge bin is used. T h e recycle ratio varies between 6 to 1 and 15 to 1 depending on grade. Storage and Bagging. Finished granular product goes by belt conveyor to a bulk storage building of 12,000-ton capacity. Different grades are discharged into bins by overhead cross conveyers. Then, on demand, front end loaders reclaim the fertilizer from the bins and dump it through a grizzly into an elevator which feeds a double deck screen. Oversize material passes through a lump breaker. Product size material goes either to surge bins feeding two parallel bagging machine lines or to bulk loading chutes to' railroad cars. Bagged material moves by gravity rolls and a flexible powered conveyer to box cars, trucks, or pallets for storage. T h e bagging area has storage capacity for 3500 tons. Materials of Construction, Corrosion, a n d Hygiene
High humidity, the salt atmosphere of the coast location, and dusts containing some acids combine to make a serious corrosion problem for Coastal. The humidity causes the dust to cake wherever it falls, making ideal conditions for continued corrosion. Plant structures and exposed equipment receive constant attention from Coastal's maintainence and painting departments. Still, replacement of metal siding supports and the like appears necessary in the relatively near future. Materials. The sulfuric acid-phosphate rock reaction tank is made of steel, lined with acid-proof brick. Its agitators and pumps are made of Alloy 20. T h e tank cover, cooling air duct, and exhaust fan are poly(viny1 chloride)covered steel. The filter pans and vacuum box are fabricated of Type 316L stainless steel, while vacuum receivers are rubber-lined steel. Rubber hose carries phosphoric acid and the reaction slurry except for Fibercast pipe going to the concentrator. In the fertilizer unit, the first neutralizer is a lead and acid brick-lined steel vessel. T h e other neutralizers are made VOL. 52. NO. 8
AUOUST 1960
643
A This dryer, turning at 4.5 r.p.m., dries the fertilizer granules to less than 1% moisture. l i s exit air temperatures range between 175" and 230°F. depending on grade manufactured
b Here i s one of the two classifiers which size the fertilizer from the dryer. Oversize goes to grinders; undersize back to the granulator
of stainless steel. Each contains Haveg agitators. Type 31 6 stainless steel went into tanks and equipment handling phosphoric acid and neutralizer fume ducts, except for transfer lines which are rubber hose. The granulator and dryer are carbon steel, as are conveying equipment, interconnecting chutes, and dry dust collecting systems. Fume and dust scrubbers are stainless steel and wood. Hygiene. Coastal has run into no unusual problems in regard to personnel discomfort in its plant. Normal precautions of masks are taken when working in dusty atmospheres. No dermatitis has occurred.
sential to large-scale fertilizer production. Coastal's only important raw material to come by rail is potash and it is doubtfLil if a suitable source of supply using water transportation will be found. As farms become larger. possibilities of water shipment of fertilizer appear. However, because large quantities are involved, such shipments are expected to be few in the near future. A more extensi\,e distribution system may malx water shipment economically attractix e later.
Acknowledgment
The authors are grateful for the assistance of I t T . B. Dunwoody and Spivey Lipsey, Coastal Chemical Corp.. A . C. Goodman, The Fluor Corp., Ltd., and R. A. MacDonald, hlississippi Chemical Corp., in preparing this artic!e. literature Cited (1) U. S. Dept. of Agriculture, Agricul-
tural Research Service, Fertilizer Investigation Research Branch, Washington 25, D. C . , Repart f x Year Ending June 30, 1959.
Fertilizer Future
Several factors combine to make h t u r e of the fertilizer industry bright. H o w ever, these all come back to one single basic factor, that of the world's rapidly increasing population. Locally in Coastal's case sone smaller factors ensure its future. These are acceptance of high analysis fertilizers by growers, water transportation of t\vo major raw materials, and politics in agriculture. Acceptance of high analysis fertilizers stems from efforts to reduce farm production costs through mechanization and efficient materials. In addition to production efforts are efforts, helped by politics, to increase yields per acre. These, too, help the acceptance of high analysis materials. Bringing in sulfur and phosphate rock by water has become almost es-
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INDUSTRIAL AND ENGINEERING
Finished fertilizer of one grade i s stored in bins such as this in Coastal Chemical's warehouse. From here front end loaders carry to a lump breaker. Then a conveyor takes it to bulk loading or to the plant's bagging operation
CHEMISTRY
