HERBERT G . G U Y Koppers Company, Pittsburgh, Penna.
The close relationship of the coal-processing industry to agriculture is discussed. The consumption of products derived from the carbonization of co al, as w ell as deriva
tives of these primary products, has been estimated and is presented. The materials derived from coal have been found to be useful in agriculture as fertilizers, insecticides, disinfectants, herbicides, fungicides, fumigants, preserva
tives, plant-growth regulators, and food dyes.
T
HE close relationship of the coal processing industry to agriculture is not generally realized. Few farmers know that many of the essential chemicals purchased by them for the growing of animals and plants are derived from coal.Conversely, the extent, importance, and complexity of the agricultural industry are not fully understood by those not vitally concerned with agriculture. It seems well to point out certain statistics that will emphasize the complexity of agri
culture and the economic importance of this major industry.
In 1938 the total farm value of agricultural products was over 114,000,000,000 (Table I). This does not include forest products which many consider a part of agriculture. In addition to livestock, poultry, and other animal products, there are over eighty different crops important enough to be considered separately in the annual statistics prepared by the United States Bureau of Agricultural Economics (20).
Coal itself is not directly used in agriculture except as fuel.
It is not the intention of the author to include those materials that indirectly influence agricultural production. It has been suggested that coal be added to the soil to absorb heat from the sim, or as a fertilizer and soil amendment. While coal might be valuable for such purposes, no record of any large- scale consumption has been found. The Utah Agricultural Experiment Station has reported that the addition of coal to the soil does not benefit the growth of com (11). Coal has meliorative or catalytic effect when used with ammonia ferti
lizers but is of no value alone, according to Musierowicz (1Ą) who worked with finely ground coal from Upper Silesia.
Leached coal ashes are commonly used in greenhouse benches to improve soil drainage and to lighten soil. Ashes do not supply plant foods and must be used in combination with fertilizers (12).
M o re th a n 82,000,000 n e t to n s of coal w ere carb o n ized in b y -p ro d u c t ovens d u rin g 1941 in th e U n ited S ta te s . A ccord
ing to R a m sb u rg (15),th e m o d ern oven carbonizes 26 to n s of pulverized coal p e r d a y ; in a d d itio n to 19 to n s of coke, a p p ro x im ately 300,000 cubic feet of gas, 210 gallons of ta r . 600
T h y lo x Gas Purification Plant for Production of A g r i cultural Sulfur
139
140 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 35, No. 2
Four Late Typ e Saturators for the Production of A m m onium Sulfate
pounds of sulfate of ammonia, 75 gallons of light oil, and 120 pounds of recoverable sulfur plus additional miscellaneous products are produced. These products and many of their derivatives are of agricultural value. It is difficult to draw a line separating such synthetic products into coal and non
coal derivatives. In fact, certain of them can be produced either with or without involving any derivative of coal as a raw material. However, in order to simplify this report, it seems advisable to discuss the various products in the order in which they are usually separated in by-product plants.
Ammonia
The most fundamental problem in agriculture is plant nu
trition. Nitrogen is one of the essential elements necessary to the growth of plants and, consequently, to all life. Plants utilize nitrogen only in combined form, including ammonium, nitrite, nitrate, and organic compounds. The most important source of this element for commercial fertilizers is ammonia derived from the destructive distillation of coal or from coke,
T a b le I. N u m b e r and V a lu e o f Farm Products o f C o n tinental ovens in this country were built at Syracuse, N. Y., in 1893 for the primary purpose of produc
ing ammonia. Because of its high cost and other disadvantages, ammonium chloride is not commonly used as a fertilizer. Ammonium sulfate, however, remains the standard source of nitrogen for fertilizers in this country because of its low cost per unit of available nitrogen and has replaced Chilean nitrate to a considerable extent.
Table II. W h o le s a le Prices o f a U n it ( 2 0 P o u n d s ) o f N itr o g e n in including nitrogen-containing fertilizers, by farmers has in
creased steadily during the past twenty-five years, and even those in the black soil areas of the corn belt are beginning to find it necessary to add nitrogen to the soil. The consumption of nitrogen in Minnesota (7), for example, has increased from 176 tons of available nitrogen in 1933 to 449 in 1940. In the United States 8,310,853 tons of fertilizers were produced in 1940 (3).
The standard of living in backward areas, such as India, could undoubtedly be raised if the people could be persuaded to use manufactured fertilizers. As repeatedly demonstrated, the increase in yield from the judicious use of inorganic fer
tilizers more than offsets the additional cost. The fear that the world would not be able to support the increasing popu
lation, expressed in the early nineteenth century, has been overcome by the use of inorganic fertilizers. Although pres
ent conditions are causing a tight situation, there is no pos
sibility of future shortage of nitrogen when it is realized that in 1938 synthetic nitrogen plants, on the average, operated at about 53 per cent capacity. Before the present war and con
February, 1943 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 141
sequent increased capacity, it was estimated that the annual world capacity for producing synthetic nitrogen, including cyanamides, was approximately 4,100,000 tons.
In an effort to save freight and other handling charges, the concentration of available plant food in mixed fertilizers has tended to increase, leading to the development of ammoniated superphosphates and similar materials. It is now estimated that over 70 per cent of the mixed fertilizers produced in this country contain ammoniated superphosphate.
Ammoniated superphosphate is prepared by the treatment of superphosphate with ammonia liquor, anhydrous ammonia, or so-called nitrogen solutions containing ammonium nitrate or urea and ammonia liquor. The quantity of ammonia that can be added without serious formation of citrate-insoluble phosphate amounts to 3 per cent with ordinary superphos
phate and 9 per cent with double superphosphate. Aside from the lower cost of the nitrogen, ammoniation greatly im
proves the mechanical condition of superphosphate and mixed fertilizers containing superphosphate. It reduces the
M o d e rn Battery of By-Product C o ke O vens
Ta b le I I I . W o r ld C o n s u m p tio n o f Pure N itr o g e n ( 7 )
P r o d u c t 1 9 3 3 1 9 3 4 1 9 3 5 1 9 3 6 1 9 3 7 1 9 3 8
Thousand metric tons A m m o n i u m s u l f a t e
S y n t h e t i c 5 6 0 5 3 5 5 3 3 6 3 0 6 8 8 7 6 5
B y - p r o d u c t 2 5 8 3 0 7 3 2 1 3 7 6 4 2 9 4 1 1
C y a n a m i d e 1 6 8 1 9 5 2 3 2 2 6 9 2 9 1 3 0 5
C a l c iu m n i t r a t e 1 1 8 10 7 1 5 3 1 5 6 1 7 9 1 9 5
O t h e r f o r m s o f N z a
S y n t h e t i c 4 6 2 5 1 6 6 0 7 7 2 4 8 5 1 9 3 1
B y - p r o d u c t 4 0 4 8 4 5 4 6 5 3 4 9
C h i l e a n n i t r a t e o f s o d a 71 8 4 1 7 9 1 9 2 2 0 6 2 2 4
T o t a l 1 6 7 7 1 7 9 2 2 0 7 0 2 3 9 3 2 6 9 7 2 8 8 0
a I n c l u d e s n i t r o g e n p r o d u c t s u s e d f o r i n d u s t r i a l p u r p o s e s e x c e p t C h i l e a n n i t r a t e a n d a m m o n i a i n m ix e d f e r t i l i z e r s .
setting action when ammonium sulfate is used with super
phosphate. In 1937 the fertilizer industry consumed for this purpose 6000 short tons of anhydrous ammonia, 25,000 tons of 30 per cent ammonia B liquor, and 70,000 tons of ammoni
ated solutions of the fortified type (9).
It has been known for some time that it is possible to ammoniate superphosphate or to produce ammonium phosphate by direct treat
ment with coke-oven gas. Certain manufac
turing difficulties, however, have prevented the utilization of this procedure. Ammonium phos
phate has been imported from Germany as the principal component of Nitrophoska. The total domestic consumption of this product amounted to 6500 short tons in 1937.
Ammonia will combine with humic sub
stances at low temperatures in a form that is available for assimilation by plants. Am
moniated peats and brown coals have been investigated as fertilizers in Europe. These products have also been successfully treated with phosphoric acid. Peat as a soil correc
tive has been marketed on a small scale in this country (5).
Although in the past ammonia liquors have been used only indirectly in this country for the fertilization of plants, promising results have been obtained in certain areas for their direct use. In irrigated areas, ammonia liquor has been added to the irrigation waters with excellent results (17). The stimulation of plants from such treatment is very rapid.
This new development is being watched with considerable interest by agricultural investi
gators.
The large-volume low-cost production of urea has made this product available for fer
tilizer manufacture. This synthetic urea has also been found useful as a means of supple
menting proteins in livestock feeds.
Cyanogen
The presence of hydrogen cyanide in coke- oven gas suggests that this valuable product can be utilized. As a step in this direction ammonium thiocyanate is being produced com
mercially on a large scale in this country from coke-oven gas. This compound has been suggested by agricultural investigators as a weed killer, potato wart eradicator, and seed disinfectant. It has also been mentioned as a means to speed the coloring of apples and to regulate the dormancy of plants. It is not being utilized for these purposes at present.
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nium thiocyanate also serves as a raw material in the pro
duction of complex organic thiocyanates useful as insecticides.
These insecticides are utilized for the control of houseflies and other household insects, and are tending to make this country independent of foreign supplies of pyrethrum and rotenone.
It is possible that sodium or calcium cyanide and hydrocy
anic acid could be prepared from coke-oven gas. These ma
terials are well known as fumigants to control insects and other pests in warehouses and similar establishments.
Sulfur
The Thylox, Ferrox, and other methods of gas purification have produced finely divided sulfur, as an end product which is being successfully used for the control of insects and dis
eases in agriculture. Commonly known as flotation sulfur in the agricultural industry, it is sold either as a paste contain
ing approximately 50 per cent water or in the dry form as either a dust or “ dry-wettable” product. It has certain ad
vantages over ground elemental sulfur—ultrafine particle size and great adhesiveness to plant foliage.
In the removal of organic sulfurs from gas it is possible to produce dithiocarbamates. Certain salts of dithiocarbamic acid have recently been found promising as fungicides, seed treatments, and also as insect repellents {19).
Through the use of the hot activation sulfur recovery proc
ess, hydrogen sulfide in coke-oven gas can be removed in a form readily convertible to sulfuric acid. This sulfuric acid can be used in agriculture for the preparation of superphos
phates from phosphate rock, etc., and as a weed killer. Sul
furic acid has been used extensively as a selective weed killer for the elimination of weeds in grain and similar crops where cultivation is difficult. The importance of weeds is usually underestimated. In a survey of this problem, the Chamber of Commerce (2) estimated that weeds tax the farmers for
$3,000,000,000 annually.
Light O il
The primary product, light oil, and its components are not extensively used in agricultural productions. Benzene, toluene, and xylene have been reported to be more toxic than carbon disulfide as fumigants (13), but certain of their charac
teristics, such as residual odors, have prevented their wide
spread use for this purpose. The solvent naphthas, mesityl- ene, styrene, pseudocumene, and indene also have not been developed as agricultural chemicals. The estimated con
sumption of the primary products from coal carbonization is given in Table IV.
Intermediates produced from light oil and naphthalene are used in agriculture either directly or combined with other
-intermediates or other chemicals. Such products are particu
larly useful as pest control agents. Insects, fungi, weeds, and others of the lower forms of life are considered pests. It is estimated that agricultural production is reduced at least 10 per cent by their destructive action. The estimated con
sumption of these secondary derivatives of coal carbonization is given in Table V. important food coloring materials. Through the use'of these uniform, dependable, and safe dyes, farmers have been able to make their products more attractive to the consumer who frequently makes selections on the basis of appearance alone.
The Food and Drug Administration reports that 454,254 pounds of coal-tar food dyes were certified during the year ending June 30, 1939.
It is estimated that approximately 420,000 gallons of benzene were used in 1940 for the production of o-dichloro- benzene. o-Dichlorobenzene has been widely recommended as a soil poison to control subterranean termites and as a brush- on treatment for wood infested with termites and other wood borers. The production of p-dichlorobenzene consumed over 1,000,000 gallons of benzene the same year. This compound has been widely adopted as a control for clothes moths and other household insects, and has replaced naphthalene to some extent for this purpose. p-Dichlorobenzene is the standard l emedy for peach-tree borers and can also be used to control blue mold in tobacco seedbeds.
Diphenylamine and phenothiazine have recently been dis
covered to be extremely useful for certain parasites of animals.
, ip a;n“ ne's now the standard remedy recommended by ie United States Department of Agriculture for the control o screwworm, a serious pest of cattle in the southern states.
îeno hiazine, discovered to be useful by workers of the De- par ment of Agriculture for the removal of internal parasites o animals, is being received enthusiastically by farmers.
February, 1943 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 143 were treated with wood preservers (5). The most important one in volume is coal-tar creosote. The direct relationship of wood preservation to agriculture is not generally realized. Through the use of pressure-treated wood, farmers can reduce their overhead to a considerable extent through longer life of fence posts, farm buildings, etc. Well-built corn cribs, silos, and hay storage sheds effect better curing of farm crops and, by preserving their quality, help reduce feeding expenses.
Wood preservers now offer treated lumber, precut and ready for assembly, for the follow
ing farm buildings: hog houses, dairy barns, corncribs, granaries, silos, vegetable and fruit bins, and manure pits.
Creosote is also used as a stock dip for the extermination of lice and ticks, and in poultry houses as a general disinfectant. To control poultry mites, attention must be given to the house rather than to the bird, and excellent control may be obtained by treating the roost and interior of the poultry house with creosote. This product, usually diluted with petroleum oil, is an excellent weed killer. Creosote is also used as an insert,
barrier to prevent the spread of such pests as chinch bug.
Chinch bug outbreaks occurred at irregular intervals, but in 1934, 3,500,000 gallons of creosote were used to control
sidered an agricultural problem since the products of the farm as well as the household goods of the farmer need to be pro
tected from its ravages. Approximately 10,000,000 pounds of naphthalene are used annually to control clothes moth and carpet beetle. Both naphthalene and p-dichlorobenzene will kill these pests when applied to clothing in airtight con
tainers. Many people use these products without taking pre
cautions to make their clothes closets airtight. Neither of these materials will kill the pests unless a sufficient atmos
pheric concentration is reached, and they do not act as re
pellents. The Department of Agriculture recommends that 1 pound of naphthalene be used per 10 cubic feet of space.
However, Coleman (4) found that less than lethal concen
trations will greatly retard the feeding of these insects.
Applications of naphthalene in open closets will give pro
tection against clothes moths but will not wipe out the infes
tation present.
Naphthalene is utilized to control greenhouse pests (such as red spiders, thrips, and white flies) by fumigation, as a dry dip for cattle and hogs to control lice, for the preserva
tion of hides in storage, and as a soil treatment to control such pests as carrot rust fly. Back-yard gardeners have found naphthalene moth balls to be useful as repellents for rabbits. The moth balls are scattered around the plants to be protected, but are not allowed to come in direct contact with the plants.
Naphthalene and other coal-tar products serve as raw materials for the production of sulfonates. These sulfonates
are used as wetting agents in the preparation of agricultural sprays and as detergents for the washing of agricultural
A recent development in agriculture that offers considerable promise is the discovery of synthetic plant hormones. These growth regulators have been found useful in the production of fruit without fertilization, for the development of roots on cuttings, and for the prevention of premature dropping of fruit. The better known of these synthetic hormones are a-naphthalene acetic acid, indole butyric acid, phenyl acetic acid, and 0-naphthoxy acetic acid. It is interesting to note that all the effective materials discovered to date have an aromatic nucleus. Farming in the future may become more of a science and less of an art through the development of syn
thetic plant growth regulators.
Tar A c id s
Tar acid oil and cresylic acid, either alone or in combination with petroleum oils to make dormant sprays for the control of overwintering aphids and other insects on fruit trees, have been largely replaced with dinitro-o-cresol and dinitrocyclo- hexylphenol. These nitrated phenols are also used for the control of red spiders in citrus trees and certain greenhouse crops. Dinitro-o-cresol is an extremely powerful contact in
secticide but must be used with caution due to its tendency to injure foliage. Advantage has been taken of the phytocidal properties of this compound to develop a selective herbicide for the control of weeds in gram and other crops. Its selective action is believed to be due to differential wetting of foliage.
Tar acid oils, cresylic acid, xylenol, cresols, and phenols are well known as disinfectants. Phenol was suggested as a bac
tericidal agent by Lister in 1865, and is now the standard for all disinfectants. The phenol coefficient of the disinfectants
144 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 35, No. 2
marketed today represents the relative effectiveness to phenol in killing Staphylococcus aureus and Bacillus typhosus. The volume of disinfectants consumed on the farm is substantial.
Dairy farmers and poultrymen especially have learned the value of farm sanitation.
Tar Bases
The heterocyclic nitrogen compounds obtained from coal tar have been investigated as insecticides and fungicides.
Pyridine has considerable insecticidal action, and attempts have been made to produce synthetic nicotine from this prod
uct without commercial success. Quinoline has been re
ported to be an excellent ovicide. Substituted quinolines, such as 8-hydroxy-quinoline, are good fungicides. The agri
cultural consumption of these tar bases and their substituted products, however, is small. The tendency of farmers to fortify their feeds with vitamins may result in the larger con
sumption of tar bases for agricultural purposes. A large volume outlet for low-cost vitamins exists in the agricultural field.
Coke Being Pushed from a By-Product O v e n into a H o t Car
The development of chlorinated phenols in the last twenty years as disinfectants, wood and fabric preservatives, sap stain controls, etc., has been phenomenal. Most of these products are prepared from synthetic phenol, and 8,000,000 gallons of benzene were used in 1940 for the production of
The development of chlorinated phenols in the last twenty years as disinfectants, wood and fabric preservatives, sap stain controls, etc., has been phenomenal. Most of these products are prepared from synthetic phenol, and 8,000,000 gallons of benzene were used in 1940 for the production of