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Патент USA US2136793

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Nov... 1‘5, 1938.
w. H. GABELER ET Al. '
Filed Deo. 11; 1955
2 Sheets-Sheet l
Nov. 15,1938.
` _w. H
, ‘.«ïLER ET A1.
Filed‘Deo. ll, 1955
2 Sheets-Sheet 2
fj Planted' , Nov._1s, 193sy f
2,136,793 .
TREATMENT or surnnrnosm'rn
`William Harold Gabelcr, Alvin Chcsley Wilson,
' Thomas Orkney Tongue, and Mark Shocld.
Baltimore, MdL, assignors, by mesne >aiisign-
ments, to The Davison Chemical Corporatioma
corporation of Maryland
Application December 11, 1935, Serial Nm 53,999 >
8 Claims. (Cl. 'i1-40)
This invention relates'in general to the pro
bulk.' This treatmentfreduces thefree acid and i ‘ ‘
duction of fertilizer fromphosphatic rock, and
more `particularly toan improved method of
improves the physical condition, .whichy although
still far from ideal is acceptedby the trade.
manufacturing ‘superphosphate `by itself or in ' If the superphosphate is to be" soldl as mixed'v
goods orv so-called complete fertilizergthecured
5 ‘ad'mixturel with other fertilizer ingredients. \
is dry mixed with other fertilizer
The usual method"of manufacturing super-v superphosphate
ingredients and allowed -to cure.> During. this:
‘ phosphateis by these-‘called Den process.` This
involves‘batch mixing of groundjphosphate rock
and sulphuric lacid in a pan- mixer. After a
10 relatively-.short mixing time the batch While still
in av ñuid'o'r semi-fluid condition is dumped into
a confined» space called a Den. In some cases
the mixing of ground rock and acid is made con
curing the mixture sets or cakes.
y ' y
`After 'a' cer- `
tain time period the mixture is 1 milled _and
screened and is ready- for shipment'. It should
be pointed out that a certain amount of organic
material like tankage, ground tobacco stems,`cottonseed meal. etc. is added to the mixture to im
tinuouslyv in la horizontal trough mixer.V `The- `prove the physical' condition. lThisI is a y‘costly ,15"
15 Den may v*either bestationary or movable as in addition as the unit cost of nitrogen'in organics
is about `two to three times asïexpensive _as in l
“ "mechanical `Dens.,. The fresh superphosphate is
inorganica. 'I‘he fertilizer> value 'er-the organics, l
is generally less than 4the inorganics,` ‘so the vreal ‘
solid mass.` In case‘ofstationary Dens themass c
purpose of the addition` of organicsis to improves 'v
is dugout` by means of a- crane` bucket and de
livered to la curing pile. In some places the the physical condition of thefertilizer=>
All fertilizers are sold on guaranteed chemical
fresh super-phosphate is rasped before being putV analysis,
so that the only commercial difference f' V‘
on the curing pile. ÍThe ra'sping operation in
volves feeding the fresh superphosphate past between any fertilizers of identical {chemical
composition is a difference in physical condition. " ` " `
rapidly revolving'arms or knives which disin
tegrate‘the mass and aerates it. TheÄ purpose The criterion on physical condition,is,in turn 25
the free flowing and free drilling qualities of the
allowed tolset up in the den to a relatively soft
of this operation is to effect moistureelimina
fertilizer. A truly free ñowingl fertilizer consists
of dry. hard, discrete granules of substantially,-`
tion. In case of mechanical Dens the block of
fresh superphosphate is> always fiaked or shaved
oil and aerated before yit'goes- to the storage or
30 curing pl1e.„_`The practice has always been to
` use as strong acid as possible for the acidulation
Uniform Size. no dust and no oversize,-4 _thus no
to reduce the« amount of water in the superphos
phateas much as possible. The purpose of the
'I'he term curing is
vsriousiy used in the rer!
tilizer trade, referring either to reduction in inf t . _
soluble P205 or improvement in physical condi'
tion and very often includes both. For theïpur-f
flakingand aeration is also largely to reduce the
of describing this invention accurately ‘and
35 moisturel content. The fresh superphosphate` `p_ose
clearly we will l'denne theword “curing” »as a re
made with as'strong acid as possible and fre
quently (after subsequent aeration is placed on 'duction of insoluble P205 only.` and will so use
-the curing pile where it remainsl for a period of this term both in the remaining speciilcation andl i
generally not less than one month and ordinarily in the claims. When we refer to improvementî ,4o l
physical condition we will so state. ‘
40 three to fourz‘m'onths. The purpose of the cur V- in
` _ A primary object of this invention isthe pro-` l 4ing period is to improve the physical, condition of vision
of a method which substantially> elimi
` the superphosphate and to allow the chemical .re
nates the storagetime required for acidphos- y
‘ \ action to go to-substantial completion> This re- y l
duces the insoluble P205 and the free acid and phate and entirely eliminates the preliminary,445 ,
storage of complete fertilizer, and whichl willv
45 conversely the proportion of available P205` is rapidly
reduce the insoluble P205 both' in super-~ ,i If the superphosphate is to be sold for direct phosphate `,and in complete fertilizer and ‘also to
a greater extent than' has been possible heretoy-'j ¿
` applic tion to the ysoil it is necessary to further
treat ‘ he cured _acid phosphate to improve its
50 physical condition so that it will not set or cake
fore; thus effecting'economy onvmaterials. j '
Another object of uns invention is to .produce
>in bags or cau‘sebag rot, _and so that it will superphosphate and Acomplete >fertilizerof im-„
» handle'sátisijactorily through'a fertilizer _'drill. _proved physical condition I’of the characterv of '
‘- This is oidinarilyaccomplished by adding ground ,
i phosphate rock or ground dolomite or lime and
55~ sand ‘or ground limestone and'sand. This mix
ture is milled and screened land‘yput in storage.
During this storage of' from 'two -w'eeks' to'a
month a certain amount `of caking or set `takes
place. -The material `is milled and screened
porous', discrete, nodular*` encrusted» and indu
rated globoid particles‘in. a simple andmore ecos"
nomical manner.
The invention has ror‘iurther objects e ine-thee. _
which eliminates the necessity for cutting supere4
phosphate and putting it through a milling and `
screening operation twice to improve its’> Physical
t 6o, again 'and is then'ready for shipment in bags or ¿condition for direct application ’to the soil, and ‘
' which win produce a complete fertiliser' in mn
ular form where each granule contains all the
various fertilizer ingredients. thus eliminating
end. The cylinder 22 is about 3% feet in diam
the possibility of segregation of the various in
inner circumference of the4 first quarter of the
eter, and about ten vanes or flights, approxi
mately ßve inches high, distributed around the
gredients during handling and shipping and dur » cylinder suiilce to initiate the agglomeration ac
ing application to the soil. and the invention has tion lof the superphosphate.
for still further objec‘ts such other improvements
The rate of superphosphate feed is regulated
and advantages in operation or result as may be by varying _the speed of the slat conveyor 3 and
found to obtain vin the method and apparatus an .adjustable gate at 't on the feed hopper 2.
hereinafter described 0r claimed.
In the accompanying drawings. forming a part
of this specification, and showing. for purposes
" of exemplincation. a preferred form‘and manner
in which the invention may be embodied and
A water supply line I and a recording water
meter ‘I with automatic pressure adjustment de
liver water through pipes 8 to atomizlng sprays
l a short distance inside each end of the cylinder
22. II is an ordinary single shell, concurrent.
practiced, but'without limiting tbe claimed ln- _ «direct heat rotary drier operating at atmospheric
vention lspecifically to such illustrative instance
pressure and provided with lifting vanes ii to
or instances.'-
agitate or tumble the material like the condi- '
Figure I is a side elevational view ofso-ne .type
of apparatusadapted to carry out our process.
Fig. II is a diagrammatic view of another appar
ratus dor carrying out the invention.
. tioner 22. An oil burner I2 feeds a fire box i3
lined with lire-brick and having a refractory
balle wall; il for introducing hot combustion
gases into‘the drier Iii to heat the nodules to
a temperature of about 180° F. An exhaust fan
sheets showing velocities of curing reaction and il `and stack I'I deliver the combustion gases to
reduction of free acid. ,
the atmosphere. Ii8 is a preliminary storage-pit.
As vhas been previously described, the practice from which cranebucket I removes the treated
'in the pastl during' manufacture of acid -phos
material to storage. A swinging gate I9 allows
phate from phosphate ‘rock hasbeen to use-as the material to fall into the'plt i8 without admit
'strong acid as' possible as well as to aerate .the ting air into the outlet end box 20 oi' the drier.
fresh superphosphate to reduce the moisture con~-- v The conditioner 22 is operated
at a speed of
Figs. III, IV, `V> and ’VI are lihlstrative-curve
tent‘t'o a minimum.
« ‘ approximately 7 to 8 R. P. M. and the drier i0
,We .have made the surprising discovery thst`
by going in exactly opposite direction, that ß.
adding- a small -amount ofiwater to silpel'phos-y
.phate, made in the regular manner, and agitatins
itfat atmospheric pressure and temperature to`
about the same. The conditioner 221s about 3%
feet in diameter and l5 feet long, whereas the
- drier is 3% feet in diameter and 30 feet long',
providing a capacity of about 100 tons of iin
ished material per 24 hours.
The 1superphosphate is fed continuously into 35
preliminarily nodulize the superphosphate and.
directly thereafter, without intermediate storage~ ' ' the conditioner 22 at a uniform r'ate by means of
curing, removing the excess water from the pre
feeder I. The- purpose of the conditioner 22 is
liminarily nodulized superphosphate ~by drying
” 40
to agitate ’and agglomerate the superphosphate
into yrelatively flrm discrete nodules, like pellets .40
or ballspof more or less uniform. size before the
nodules’are subjected to drying. The conditioner
with beat while agitating it at atmospheric pres
sure, a most remarkable increase lin curing rate
Y as well as improvement in physical condition is
obtained. Thus, instead of aerating the super
phosphate‘to remove moisture, we actually maln
tain high -moisture or d moistin'e and operate
at atmospheric pressures
preliminarily nodu
is such relativel to the temperature and moisture' '
lise itby tumbling to form discrete. nodular. firm
particles before heating to dry the nodules dnd
of the material that substantially no dryingof
the material occurs during the nodulizing step.
Y Y then
while directly
until converted
thesel nodules
to discrete,
to nodu- .
rate 'through pipes I and atomizing sprays 9.
"lar, encrusted and lndurated globoid particles. -,
'In‘making complete fertiliser by meam of
' this invention. the preferred method is «to mix
ls’open at both ends so as to'maintain a substan
tially non-drying atmosphere therein, that is,
an atmosphere whose temperature and humidity
Water lmay or may not be added at a uniform
This addition of water will depend upon the age
and -the
moisture content of the original super'- '
introduced into hopp'er 2. If water is
superphosphateïwith other fertiliser ingredients. added th ‘quantity required is a function of not
meisten and agitate the mixture to noduliae it only the ' ginal moisture content of the super
and ‘directly thereafter remove excess'molsture phosphate but also the age of the superphosphate,
from the pre-formed nodules by heating it as »that is, whether or not it is taken directly out
aforesaid.. 'An even more distinct curing e‘ifect . of the den or has first gone to an auxiliary inter
` is obtained‘than incase of straight superpues
mediate storage. We have also found that the
phate and an'improvement in physical condition ' particle sise of the nodules of 'agglomerated su
to the extent that an ideal complete' fertillnr
Referring to Pig. I. a crane bucket l delivers
fresh superphosphaœ out of the den. or partly
cured den superphosphate. to feed hopper 2. An
apron conveyor I made of slats deliversthe‘super
phosphate to a horizontal rotary cylinder '22.
whiclifis operating in room temperature and at
atmospheric pressure with a substantial non
drying atmosphere and is set'on a slight pitch
-and provided with lifting vanes l to agitate or
perphosphate issuing from the discharge end of
the conditioner 22 is a function of the quantityv
of water addition.
The nodulized superphos
phate drops as discrete firm-particles continu~
‘.ously from chute -2i directly into the drier. In
' the drier the pellets are further tumbled while- 65
' progressing continuously therethrough as .they
are being heated and dried at atmospheric pres-. '
‘sure-by direct contact with the heating gases
`whichprovide a drying atmosphere and the pel--
letsn furiherfhardened to porous. discrete, en- " O
tumble the material and thereby agglomerato it _ crusted and indurated nodular globoid particles
into fdiscrete firm nodules. l'br simplicity this
cylinder will beereferred .to as the conditioner.
whence they are discharged from the drier. The
`dried material is removed to storage from pit I8
The lifting vanes l extend about one-fourth of
byme'ans of crane bucket i.
the length of
cylinder 22 from its upper inlet
The material is
to stayin storage for 75
and'then immediately dried in drier lli.v The
a period of from only 2 to 3 days up to a week.
During this period the pellets get_„very much . nodule material from the drier I0 analyzed as
. harder and have a crushing strength in excess
of several times as great as fully cured ordinary
den superphosphate. The material is then milled
and screened and is ready for shipment.l By
Total Pans
Insomma Pm“
properly regulating the moisture content in the
conditioner the quantity of over-size that has
Available Pam. »
Free acid
to be disintegrated is reduced to a minimum.
there is a tendency to form Iinesrin the final , '
7 72
"""""""""""""""""""" '»' l
To more clearly illustrate the effect of the pre
product the ratezof water meinenV in the conai- `liimimu‘r nodulizing and immediately following
tioner is increased and if there `is a tendency to drying Opel’stlûns We refer t0 Curve sheet Fig» III
forman excessive amount of over-size the >water ` Curve (a) represents the 1301121011 Of the Super
rate is reduced.
phosphate of theabove composition and aged»
in curing piles. The insoluble P205 has been 15
We have also discovered that while especially
15 fresh superphosphate, when nodulized with too
given as a ratio of the insoluble P205 over the
great a quantity of` water, will form rather large - total P205.- 'I'his is for the purpose of making
l agglomerations of `from hazel-nut to fist size and w the curves truly representative as, to the efficiency
l even larger, nevertheless on passing through the of conversion of insoluble P205 to available form. Y
direct heat drier these- . larger agglomerations ' The insolublehas been plotted against time. In 20
break down into smaller pellets. The~ nodules this manner any apparent. Variation in insoluble
while firm are in- such instances of such physical> lP205 due to variations in water content both
condition that'if taken out at the discharge end
"free and ñxed is eliminated. I In other words. if
of the conditioner and -put in a small pile, the
" the insoluble P205 read of! the chart is deducted
separate discrete particles or .nodules will tend _ from 100, the resulting ñgure represents the per
25 to run together and form a claylike mass of the
`centage of .acidulation or conversion of the P205
consistency of soft `modelers clay.
from insolubieto available form. Curve (c) rep
Generally speaking in such instances the quan- `resents the above superphosphate treated `by
tity >of water added is decreased and we prefer to
means of -our process.
water addition so that the granules>
lCurve sheet Fig. IV represents `the free acid
30l `regulate‘the
leaving the conditionerlz are in such physical: reduction plotted against, time. Curves (a) and
` - condition that they do `not immediately coalesce
(C) correspond t0 the same letters in Fig-,IIL
‘ if removed from the conditioner 22 and‘ allowed to
AS ‘a further eillilstl‘atiOl! We, give below the
stand stationary in a pile before entering the analysesof bothsuperphösphates 12 days old.
drier I0.
At least the tendency is not to run >to- `
Y ,
' some coalescence at the contact points of the -firm
suä’à’äœ' sugegâ‘àos‘
. «
regulated in accordance with the size of the mate-
‘iëó’î‘ïàïïjl‘ """""""""" "
rial issuing from the drier `so that when screen
“50u e
I l--
‘ tested about two-thirds to three-fourths does „ ‘Èfglââä’îfffïj'
not need to be crushed, that is over '70% will pass
Treated -
In addition to'this the moisture content is also
gether into one'clayey mass although there is
through an 8-mesh screen and most of the rest
_ will pass through a .fi-,mesh screen.
- -
l r
To show that our process is also eil’ective on
superphosphate that has stayed in the storage 45
‘ “
We will now give some speciñc examples of op_-. pile for some time another 100 ton pile of regular
erating conditions and products produced in ac- 'superphosphate was set aside. The analysis of
cordance with our invention as well as compara- -this material when made and 12 days old was as
tive results of producing superphosphate in the
Iold manner.
Fm'h ‘
yCiround rock’___-__'____________ .._'_'. _____ __
55 Bé'. vfwiiîl‘
e A
Free acid... ............................. ._
_ 1071,l
1125 u
wig? Superphospbate @ken out Orf the @en apa
""" "I:
____________ _3:
‘ 쑧§}ß‘§ßï§;%'¿___
‘ l
and 55 Bé. sulphuric` acid. i. The actual batches l ä‘txâiul’rfóìïïï:
12 days 01d
This superphos- e
“used in the mixing pan were as follows:
phate was made from 72.9% B. P.- L. Florida rock‘`
A quantity of 100 tons den superphosphate was
made up in the usual manner.
¿gî 55
This-12 day old material was moistened in the
water l and
thereim The treated material immediately after
Per ¿ent " direct treatment in the drier land after 3 days
Moisture ____________________ _‘_; _______ __
Total P205 ______________ _`___-_ _______ _____
Insoluble P205 ________ ...' ____ __' ______ _-.__
Free acid ____ __ _____ __'_____ ___________ __.
Treated material
Available P205 ..-'.-_._.-'_`_ ______ __'_______ ___-_17.61 l
'1,55 .
The above determinations weremade according '
free acid, for which ,there is no official method.
n1)- à‘ê‘
70 The free acid was determined as yHaPOi- by the ` mammie-` ..... _.
Slipel‘phosphate , of the above l composition was
to..the A. o. A. C. voilicial methods, except the ' âî‘ì‘âf‘t’fógjjjjjjjjjjj; """""""""" "
tentative A. 04. A. C. alcohol method.
‘ ' ¥
The regular superphosphate 24 days after mak
promptly thereafter moistened by the addition of jing and the treated superpho‘sphate 12 days after
2.2% water and nodulized in the conditioner 22` . the treatment (which corresponds rto 24 days 75
- from the initial superphosphate) -analysed _as fol
ytory physical condition, because it was substan
tially all in the form of ilnes.
Treated `
4. 4o
1. 50
18. 56
l. 12
19. 91
. ,
The preliminary nodulizing operation in itself
improves the curing. In conjunction with. the
' directly following drying operation, however, the
beneiicial result is vastly improved.
An example of only nodulizing the superphos-l
phate with 1.9% of water _is as follows:
Original Nodulized
phosphate phosphate
l This is represented°graphica1ly in curve sheets
Hgs. V and VI. where- curve (a) represents the
regular superphosphate and curve (c) the treated
superphosph'ate as described above. For the pur
pose of preparing all the curve sheets the piles of
materials were resampled and analyzed every _few
Moisture ................................ _Total PgO ................... _-
insoluble 130;. _.
Available P’O; ____________ __
The curves represent mean or average
Fna acid. ............. _'. _ _ _ _
_ _ _ _ _.
9. 14
2l. 00
1l. 04
l9. 58
1. 58
18. 20
18. 00
8. 03
5. 87
We are not able to deiinitely-state why the
,20 above _beneficial results are obtained. Merely as
It the superphosphate'is made originally with
a sudiciently high moisture content it is nodu
lized withoutwater addition. The following su
pcrphosphate was nodulized without water addi
a theory and without binding ourselves thereto,
we suggest the following explanation.
The. free acid in superphosphate is substan
tially always HsPOi.' If any H2804 is present it
>is only in traces. The wetting and nodulating ot
lthe superphosphate may redistribute this phos
Total Pam __________ __ ____________ ___--- 19.25
phoric acid and may likely- cause some hydrolysis
of the monocalcium phosphate. On drying, the
acid` is concentrated and this as well as the ele
vated temperature of the material in the~drier
(about l80°l".)- facilitates the attack of the free
phosphoric acid on the insoluble P205. It may
be mentioned at this point that with strong phos
Insoluble P205'
Available Pz0s_.._ _____________________ __ 16.19
Pme scid-
_ 11.11
It i's _to be understood that we .dol not limit our 30
invention in all its‘aspects tothe particular kind
oi conditioner described for the nodulizing step.
phorlc acid the acidulating reaction ,is faster than` We may for instance use a pug mill. consisting of
a horizontaltroughmixer provided with a hori
with _weak phosphoric' acid. This is in contra
diction to sulphuric acid. Ii sulphuric acid is zontal shaft with blades or arms set at a suitable
angle. 0n the other hand we may use a dough
used for the-original acidulation in a strength oi"
60 Bé. or higher,- the acidulatlng reaction is largely
mixer with sigma blades.
Further, we may for
examplev use a Chilean „mill as the conditioner.
In the previously given examples the moisture'
The attempt to dry superphosphate to improve
oi’ the treated isuperphosphate has been
its physical condition is old and the material pro ‘ vcontent
the moisture content of the original
duced is substantially nnely powdered and there
untreated material. Although we prefer to bring
is no curing. More often there isan actual re
version of P205, ,that is an increase of insoluble the moisture content down~to about 5%, this is
It is the nodulizing operation at room tcm-A not necessary for the purpose of realizing bene
ilcial results by our invention. ' We have for in
perature and‘atmospheric pressure preliminariiy stance
taken superphosphate of 9% and nodu
, but in conjunction with the directly following
this material with a water addition of lll/2%
drying operation at atmospheric pressure which , lined
subsequently drying the ilrm nodules to the orig
. produces the beneficial results both as to curing
as to physical condition.
,i As an example of large scale drying tœts (dry-'
i?g only without the `preliminary nodulation) onY f
superphosphate we give the following ior a direct
Beton drying Altar drying
‘ 17.32
4The dried material was not nodular but very
dusty and .thus unsatisfactory from the stand
_ point of physical condition.
’ An example oi' only drying regular superphos
phate in a steam heated dryer is as follows:
inal 9% moisture. After one day the pellets pro
duced were hard and ot excellent physical' condi
tion. This brings out a point ot our process that
it is 'not necessarily dependent upon a moisture
reduction of the. original superphosphate. We
have no delinite explanation as to why this hap
pens. yAs a theory, it may be that the nodulation
step lbrings the> individual particles of superphos-phate in close contact with each other and that
' subsequent recrystallixing phenomena set the
material Vto hard. and, to all appearance, dry pel
lets without necessarily showing a lower moisture
content by analysis than the original superphos
-phate. The results ot the product emphasize the
fact that the invention not only improves the
curing or the chemical analysis of the superphos
phate, but also produces a superphosphate of
greatly superior physical condition.
As has -been previously set forth, the nodula
.Before drying
'rou hoh.-insoluble P’O.
Available> Pros-- »
Fna acld.____-_--_.._ ............. __
7s V.
Altar drying l
aus t
zu. os
2. il ,
17. 88
zo. »s
2 46
18. 49
8. 24
Here the dried material was also of unsatisiac-
tion operation may or may not require water addi
tion to the superphosphate. It is further to be
` understood that instead of adding water other 70
wetting agents may be used in the nodulation step,
as for instance, water solutions of sulphuric acid,
, phosphoric acid, potassium chloride, potassium .
sulphate, sodium-nitrate. In case water solutions
‘ of acids are used in the nodulation step, a certain
amount of ground phosphate rock is mixed with ì Il and is elevated byI means of bucket elevator to »
. `
À` -‘the superphosphate asv it is being -nodulized or a storage pile.
' before it lis nodulizedf:l -This will furnish addi- “
t ‘ tional available ._P-10s.
`In using a water solution
¿of- for instance potassium -chloride, a‘ small
The function „of the conditioner as mentioned '
above, is somewhat different from the examples "
cited in connection with the apparatus in‘Fig. I.
yn-ar'nount` of phosphate -rock- is also added. This
:will-be referred to more‘speciiically in subsequent
Here water is added but in a quantity `irisuilicient .
to cause any substantial-agglomeration in the
descriptionl of making complete fertilizer by
Moreover, in `nodulizing superphosphate with
" v out water addition we _may'for instance take the
- The nodulizing of the superphosphat'e takes '
place in the upper forepart or feed end of steam ‘
drier l29. 'I'he induction and exhaust fans 31
> fresh acid phosphate ‘made »by mixing rock and ' and I] _are so regulated tl'iat` the vapor pressure'
of water at the feed end is Vsubstantially‘at atmos- r
acid and treat- this in >our nodulizing step with
„ lout met letting 1t ge through theusuel setting`
nodules of superphosphate in firm»
pellet'form 'are then dried ,preferably convec
tively directly as they `come from the4 noduliring`
pheric pressure.- »In this part of the drier the
material is therefore heated up in a substantially 15
non-drying atmosphere without any drying and
the rotation of the drier causes the preliminary
nodulation of the superphosphate before drying.
" > step.
The nodulized superphosphate ir1`,the.form of
` _i 'The Vabove is thepresent preferred method o!
small pellets is dried at atmospheric pressure in
continuous travel through the remaining part of
the drier.` Although the material is reasonably
çcarrying ‘out our invention as well gas certain
‘ process mayhowever be embodied in other man
; ners as, for example, in a single rotary drum with
indirect `heating in a‘steam iacketed drier asil
>l‘ustrated diagrammatically in Fig.- II.
.In such instance the material is first-mois- _
.tened in a moistener similar to conditioner '2l
then fed )ç_irogressivelyl through` the, steam _.
jacket drier. , In such modification >the prelimi
30 nary nodulization‘ step occurs in the forepart and
the dryingjin theafterpart of the drier. Tp this`
‘end_the drum is open to the atmosphereand air
flowscountercurrent, thereby maintaining in the
iforepart an atmosphere whose temperature> and
strong mechanicallyas >it comes from' the drier, ‘
it attains further hardness during storage after
a day or two.
in this operation. This is graphically _illustrated ,
in curve sheets V and VI, where curve (a) repre- ‘
senta the original superphosphate untreated by
thejpres'ent method and curve (b) represents
the treated superphosphate of' the present
The following tabulation shows someof the
specific analyses:
‘ n 'moisture contentof the material in the noduliz
Untreeted Treated
f ing region of the drum that _substantially no dry
vhumidity is such relative to the temperature and z
J 35
. t
The aim o( accelerated curing is also attained -
days aite‘r
` ing of the material occurs during the nodulization
‘_ in the _forepartof the drier. In 'the afterpart of
40 the drum,V the temperature of the pre-formed
1_ nodulesv is raised _softhat «the relative tempera-- ' T
1 _q ture and moisture conditions between 'the atmos-`
. 20. t3y
20. 65
» 19.17
_ 19.49
3. 72
' l phere in the drying region of the drum and the
pre-formednodules in` the after part _of the drum
Two weeks after treatment the treated andthe i
are such that a. substantial drying atmosphere
exists-and the nodules dried.
The system of delivering and feeding as well t
` as wetting the superphosphate is the same as
untreated materials analyzed as follows: q _
Untreated `Treated
shown in Fig.\I, and previously described except
, 8. 90
4. 36 ,
-nodulization does not occur in the moistener 22.
Instead of -a direct heat‘drier, a steam jacketed
19. 74
drier 26 is provìdedtwhich is heated with steam
5. 08
in the steam jacket 21, the steam being intro
duced through pipe 28, stuiling box 29 and spider .
'rne eui-ve sheets rigs. v and, vr, giving the
arm'pipes 30._ A vent cock 3l at the‘ charging
.55 end
of the drier eliminates permanent gases from . curves (a) and' (b) respectively shew that the
the inside of the steam jacket, especially venting, original superphosphate was 11 days old when '
‘the air when Vstarting _the drier. Spider. arm ' treated. This particular type of apparatus is
' pipes 32 `convey away the condensed water by not so effective for treating freshly made 'super- _
phosphate right from the den as a coating builds ,j
60 means of a bucket arrangement in the hollow end
i ring 33._ _The condensed water leaves through up on the steam jacket, which effectively insu'-- v_.
stuiilnglbox 3l and pipe 35 and goes through an
ainpreheatìng coil-and then through a steam
ytrap to waste. The drieris equipped withlii'ting
>lates’it and prevents heat transmission, but is `ì
effective' on partly cured superphosphate. The"
superphosphate" should be at least one week'old "
`varies comprising flat ¿lironst spaced slightly apart . and preferably from 10 days to‘two weeks old.` ~
The `quantity o! water required for .moistening as well` as slightiyfaway from the'shell. ` T_he bars
are supported every,l ,few feet by means of studs ' >the superphosphate is also in this case primarily
or pins' fastenedftofthe inside Aof ythe drier shell. a function of the age ofthe superphosphate. _In
Airis delivered ,to the inside of the drier by means the last mentioned example the quantity of water
_ of fanti.;` '111ev air is pulled past the air heating . used was 5.5%. The same original superphos
coil through duct 38 and vis delivered inside the phate treated in the apparatus of Fig. I requires
.stationary drierhead 99. The drier is vented
6.7% water added to the conditioner.. Generally
material discharged from the drier falls 4into pit
apparatus of Fig. I is‘dednitely higher than the
through pipe 40, ian 4l and stack 42; The dried ‘ speaking, thequantity of water required in the
y l
amount required inthe apparatus of Fig. lI'fwith
the same original superphosphate).
In addition to being a function of the age of
' . the original superphosphate used, the quantity of
5 .water reqinred is~also .governed by the particle
Exactly why this happens we do not know.
The free phosphoric acid present in the super
phosphate is not enough to account for this
conversion of PzOs'to available form. It is pos
sibly due to the action of monocalcium phosphate
` size or granule ofthe treated material that is . or hydrolyzation products of ’the monocalcium
desired. If the treated material has a tendency
togo to fines, the quantity of water used is in
creased -und- if the particle sise-has a tendency
‘lio to get too large the rateo: water mamón n
In 'addition to handling straight superphos
phate bylmeans of our p
4 ìwe have further
' discovered that the curing benefit obtained with
phosphate upon the potassium chloride, which
would free some hydrochloric acid which would
attack the rock and make it available. No _mat
ter‘what reason the fact remains that the P205
is converted to available form.
The physical condition of thetreated complete
fertilizer ls of the excellent character of discrete
encrusted and indurated nodular globoid'v par
15 complete fertilizers is even more pronounced thanr ticles.
in the case of straight lullerphosphate.
The universally practiced method of manufac
When making complete fertiliaerby means of turing complete fertilizer up to the present time,
ou:l process the raw materials are preferably
mixed before being fed into the conditioner,
20 although the entire mixing operation may be
_ performed in the conditioner.
We have discovered that the curing action.
> that- is, changing of insoluble P205 to available
P205, is in- this case so active that a certain
.25 amount of ground phosphate rock added to the
mixture will produce available P205.
`Aix-a specific example of making complete ferti
lizer by means of our process we furnish the
`'I'he superphosphate. used analyzed:
faces between the particles.
Insoluble PsOs
35 _Available P20:
me ma
as described in the beginning of- this specification,
has beento dry mix the various materials and
allow them to set. The -set material is milled 20
and the setting and milling operation is often
performed twice; In addition to this it is neces«
sary to add organics to improve the physical con
dition of the material. 'I'he setting phenomena
seem to be due to interaction and recrystalliza
tion of the various salts present in the mixture,
as -for instance monocalcium phosphate and am
monium sulphate forming monoammonium phos
phate and calcium sulphate at the contact sur
ganics is also eliminated, which is of consider
able economic advantage.
The P20» content of the phosphate rock was
By means of our invention all these interac
19.85 . tions takeplace during the treatment, so that the
resulting granular product is a stable and non
18.24 setting material. The need for the use of or
To one net ton of superphosphate, 100 lbs. of
40 ground phosphate rock was added, or in other
words the weight of the phosphate` rock was 5%
ofthe weight of the superphosphate. Stated on
Another significant advantage is that each
granule of our complete fertilizer contains all
the various plant foods.. This means non-segre
gation in handling and in distribution on the soil. 40
'I'he even distribution'of the fertilizer on the neld
is of paramount importance fromthe standpoint
" a PsOs basis, the weight of the P20; in the phos
of maximum crop yields from a minimum amount
phate rock was 8.4% of the weight of the total « of fertilizer applied.
45 PsOs in the superphosphate.
To the mixture of superphoaphate and phos
phate rock was added ammonium-sulphate and
potassium chlorideto make the complete mixture
contain approximately even amounts of available
Themixedmaterialswerenoduliaed inthecon
‘ ditioner 2! with a water addition oi.' 9.3% and
Instead of using the nitrogencus and potashÍ
containing materials specified in the above given
example we may use others, as for instance,
nitrate of soda or urea for the nitrogenous ma
terial and potassium sulphate or manure salt for
the potash containing material.
ratus of Fig. II.
Hoisture t
Total PIO: `
' 8.94
The analysis of the superphosphate used was
The iinkhed treated material vanalysaedas fol
'I'he following is an example of the complete
fertilizer produced by the method in the appa
. .
Total PzOs
19. 88
Insoluble P205 __________ ___ ______ __,_..___
Available PzOs ____ _i ____ _'. ..... ___ _____ __ 18. 7_2
Free acid
an insoluble PsOs
1. 16
v The phosphate roer contained 33.4% Pio..
This was immediately after manufacture. After
one kweek the insoluble PsOs had dropped to
The above
show that slightly over
75% of the P505 in the phosphate rock had been
im fmade available immediately and
one week
'I'he amount of ground
rock used was
the same _as in the previously given example, that 65
is, 5% by weight of the superphosphate. Am
monium ysulphate and potassium chloride was
mixed with the superphosphate and ground rock
to furnish a ratio of approximately
all the PrO; from the rock had been made avail-
able, as »well as about 20% reduction of the in
soluble PaOs in the original superphosphate. This
means production of available P10; from the
_7g phosphate rock without the use of any acid.
This mixture was treated in' accordance with
the invention in the apparatus of Fig. 1I and
conditioned by adding 7.2% water.
Immediately after` manufacture the 'ilnished
material analyzed:
~ ~
Available ‘P1205;.._; _______________ _.‘__
N2 _______ __i
i 1.16
_____________ __'....._...`..v.._....-. _____ _..
throughout the same to at least a stage at which
there is aV tendency to some coalescence of the- yag- '
glomerated solid nodules as they issue from the
conditioning step, so that the nodular mass pass- ‘
ing thence directly into the drying step may re»-l
After 13v days the insoluble P305 had dropped
through a 'rotary container at atmospheric pres
sure until the mass is agglomerated to firm Inod
vi11. 69
to 0.91%.
is. s2 ` ules andcontains the aqueous medium distributed
Insoluble P205...y ____ _'. _______ __' ____ _;.
mosphere while moving in a continuous vstream
From this it will be seen`_that approximately
tain a moisture content suiilcient to inhibit re"--.`~ 10
version and promote accelerated 'curing in the .
drying step, and then directly thereafter heating, .
55% of the PzOsin the phosphate rock had been
the preliminarily conditioned material, while still':v
made available immediately, and aftern13 days _ `in at least such wetted condition of tending to 15
approximately 80% ‘oi the` P205 in the ‘xiock had Vcause coalescence, in a drying atmosphere while
lmade available.
the above results described'
l < in
.« con
tumbling the same at atmospheric pressure in a
stream moving continuously through a rotary
nection with Fig. II are fully satisfactory from , container until the product becomes dried and
the standpoint of granular superphosphate, the indurated
2i. A continuous process of manufacturing su 20v
capacity of such an installation, without duplicaf perphosphate
produce accelerated curing which
tion of units or unduly lengthening the drum. is ` comprises ilrsttopreliminarily
conditioning a mass
relatively small in comparison to commercial of partly storage cured den
quantities and the area of the zone in which
tumbling the same in 'the presence‘of an
`no_dulizing occurs in the forepart off the steam `by
aqueous `medium in amount suflicient4 to cause
25 drum is not readily controllable, since the area nodulizatlon and in a substantially~ non-¿drying
1 will ñuctuate with variationin the character of atmosphere while moving in a continuous stream
the superphosphateisuch as its' age or moisture through a rotary container at atmospheric pres
` content. The method as described in_connec-` sure until the mass is agglomerated to firm
` tion with Fig. I is more advantageous since, re
gardless of the character of the superphosphate,
the nodulizing and drying _stepsare separately
controllable and independently regulable, and
products such as those above described in con-`
necti‘on with Fig. I were readily obtainable on
large scale full capacity operation and in quan
nodules and contains' the aqueous medium dis
tributed throughout the same‘to at least a stag@ '
at which there is a tendency tb some coalescence
of the agglomerated solid nodules as they issue
lfrom the conditioning step, so that the nodular
mass passing thence directly into> the drying step 35
. titles comparable to _commercial production- with ` may retain a moisture content suilicient to inhibit
a single unit as in Fig. I comparable in size ¿with reversion and` promote accelerated curing 'in the
drying step, and then directly thereafter heat-`
a single unit as illustratgd4 in Fig. II.
the preliminarìly conditioned material, >while
' The invention> as her] inabove set torthis ern
in at least such wetted condition of tending
4bodied and practiced in particular manners but to cause
in`-a dry atmosphere while
may be variously embodied _and practiced within tumbling coalescence
the same at atmospheric pressurein a
the scope of the following claims.k 1
lstream moving continuously through a rotary
lWe claim:
' `
container until the product becomes dried and in
’ 1. A continuous> process
durated granular nodules.
superphosphate toïprcduc'e accelerated curing
which comprises ilrst preliminary conditioning
. 45,
\ a mass of superphosphate by tumbling thesame ’
4. A continuous process of manufacturing com
plete fertilizer to produce accelerated curing
which comprises first preliminarily conditioning
lin the presence of an aqueous medium in amount a mass of a mixture " of superphosphate and other
, v>sui‘iicient to cause nodulization and in a substan- ' fertilizer ingredients by tumbling the same in the
' tially >non-drying atmosphere while moving -in a
_ continuous stream through a rotary container at
"atmospheric pressure until the mass- is agglomer
ated to firm nodules and contains the aqueous
` » medium distributed throughout the same to at
t §55
least a stage at whichvthere is ‘a tendency to
some coalcscence of the agglomerated solid nod
ules «as they issue from the conditioning step, so
that the` nodular mass passing thence directly
into the drying step may retain a moist'ure con
tent suilicient to inhibitreversion and promote
accelerated curing ln the drying step, v.and then
directly thereafter heating the preliminarilyfcon
ditioned material, while still in at least such
.wetted condition of tending to cause coalescence,
in a drying atmosphere while tumbling theA same
presence of an aqueous medium in amount sufli
cient to cause nodulization and in a substantially
non-drying atmosphere while moving in a con
tinuous stream through a rotary'container -at
atmospheric pressure untiithe mass is agglom 55
erated to firm nodules and contains the aqueous
ymedium distributed throughout the same to at
least a stage at which there is a tendency to some
coalescence of the agglomerated solid nodules as
they issue from the conditioning step, so that
the nodular mass 4passing thence directly into the
drying step may retain a moisture content sufiì
cient to inhibit reversion and promote accelerated
curing in the drying step, and then directly there
after heating the preliminarily conditioned mate
rial, while still in at least such wetted condition
. 165 "at atmospheric pressure >in a stream moving con-V _,
of tending to cause coalescence, in a drying at
tinuously through a rotaryl container until the \ mosphere while tumbling at atmospheric pres
product becomes driedyandindurated nodules.
sure> in a stream movingcontinuously> through a`
2. A" continuous process o_f manufacturing rotary container until the product becomes dried
superphosphate to produce accelerated curing and indurated granular nodules.
zo which comprises first preliminarily conditioning
5. A method as claimed in claim 1 and in which
a mass of freshly prepared den superphosphate ' the heating is eiïected by direct contact with hot
, by tumbling
the same in the- presence of an
aqueousinedium "in amount suillc'i'en't to cause
75 nodulization and in a‘substantially non-drying at- » -
6; a method as claimed-_in V'claim 1 and in rt
’ which the heating is eße‘cted byvdirect contact
Awith a co-current ñow of hot gases.
p '7. A method as'claimed in claim 1 and in
which the preliminary conditioning and the sub
sequent drying steps axe effected in separate
chambers continuously and the preliminarily con
ditioned material transferred continuously from
the conditioning chamber to the drying chamber.
y, 8. The process oi’ granulating superphosphate
1o which comprises adding water thereto in amount
sutlicient to produce approximately 11%-17%
moisture in the resulting mixture, agitating the
mixture to produce agglomeration, and ythen
tumbling the resulting material in a heated rotary
drum until dry hard granules are formed.
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