CA1087829A - Alkali metal aluminum phosphate - Google Patents

Abstract

IMPROVED ALKALI METAL ALUMINUM PHOSPHATE
Abstract of the Disclosure Alkali metal aluminum phosphate granules having a calcium rich layer thereon are provided which are characterized by improved flow and dusting properties as well as lower hygro-scopicity without a change in leavening acid performance. The product can be used as a leavening acid in moist doughs, and liquid batters, such as pancake batters and other premixed liquid batter. Longer storage life for liquid or dry products is possible.

Description

Back~round o~ the Invention The present invention relates to alkali metal alurninum phosphate granules havlng a calcium rich layer thereon charac~erize~
by improved flow and dusting properties without a loss in leavening acid performance properties. The product can be used as a leavening acid in moist doughs and liquid batters, such as pancake batters and other premixed liquid batters.
Crystalline sodium aluminum phosphate (or SALP) was first disclosed in U.S. Patent 2,550,4~0, and an early baking powder composition incorporating SALP was dlsclosed in U.S.
Patent 2~55OJ491. U.S. Patent 2,550,490 specifically discloses a SALP with a Na:Al:P0~ ratio o~ 1:3:~. Since that time, ":
~r' several modifications of sodium aluminum phosphate have been ~ .
developed which give different reactivities and performance characteristics. These include a dehydrated SALP, U.S.
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2,957,750; a 3:3:8 SALP, U.S. 3,22~,479; a 3:2:~ SALP 3~501,314, a 2:3:6 SALP, U,S. 3,574,536; an amorphous SALP, U.S. 2,995,421;
a 3:3:9 SALP, U.S. 3,726,962 and the contlnuous crystallization ~ ~ of SALP, U.S. 3,311~448. ~ ~ ~ ~-.. ',. :
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'7~9 Sodium aluminum phosphate is a well known leavening agent in the baking industry. It finds ~1se in baking powders, sel-rising mixes, preleavened pancake f]ours and mixes, prepared biscui~ mixes, and prepared cake mixes. (See U.S. 2J550,491J 3~109~73~ 3~041,177, 3~096~178)~
It is also used as a mel~ controlling additive in cheese and as a meat binding agent.
It is taught in U.S. Patent 2,550,490 that the speed ~;
of the gas developing reaction of the sodium aluminum phosphate can be accelerated by the use o~ an accelerator such as L monocalcium phosphate. The monocalcium phosphate may be formed .~.~ , .
` on the surface of the sodium aluminum phosphate crystals. This .-, . ,: .
can be accomplished by preparing the SALP as usual but omitting ;~
an alcohol wash to remove excess phosphoric acid, The excess `-`15 phosphoric acid is then neutralized with hydrated lime. Specific- ~ ;
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allyJ the sodium aluminum phosphate was prepared by dissolving aluminum in phosphoric acid and adding sodium carbonate. After --.
`,~ concentrating to a thick slurry, the slurry was added to a .~, .
mixer con~aining hydrated lime. Vigorous agitation was continued untLl the mixture solidified into small granular lumps. A~ter drying, the product was milled to provlde a dry, non-hydroscopic powder having a neutralizing value of 100 4. It was tested in the baking of biscuits and found to have baking characteristics equal to that o standard commercial phosphate-alum baking ~ 5 powders. Results of baking at a neutralizing value of 90 -~ showed the baked biscuits to have a ~pecific volume of 2.6, .. : . ~.
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7 ~ ~9 a pH of 7.4 and a fine open grain structure.
These results required milling of the SALP to obtain particle sizes sufficiently small to be usable in baking.
Sodium aluminum phosphate is generally employed ln baking applications in a finely divided state dlle to its substantial insolubility. Furthermore, lf relatively large particles of sodîum aluminum phosphate are used in bakery -~
~ applications, they can impart an undesirable, gritty property.
;~ Sodium aluminum phosphate has several inherent deficiencies O the mos~ serious of which is dus~ing and hygroscopicity.
Sodium aluminum phosphate dust is very light and rapidly permeates the air in food processing plants, creating cleaning `
and sanitation problems and unsa~isfactory working conditions for the employees. An additional problem in handling sodium ~5 aluminum phosphate is that the finely divided particles do ~'~''.Ji not flow ea~ily.
Sodium aluminum phosphate is also an inherently ~ ~ .
hygroscopic material which will absorb a large quantity of atmospheric moisture, usually abou~ 28-29~ by weight.
o Originally produced, SALP is a dry, white crystalline product.
If permitted to stand exposed in a ~ot, humîd atmosphere, it rapidly absorbs moisture, first forming water droplets or caking at the surface, then becoming what may be termed a viscous semi-fluid. Commercially, this phenomenon is minimized ~ somewhat by the use of sealed, air-tight containers. Never-theles;s, t~e precautLons required are time consuming and e~pensive, and in practical applications, the problem remains a significant .f, . ~
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Several proposals have been made in the pas~ for improving the physical handling proper~ies of sodium aluminum pho~pha~e, particularly directed to lmproving flow characteris-~5 tics and dust properties. These approaches have generally been directed to agglomerating or pelletizing the SALP as disclosed, for example, in U.S. Patent ~,620,972 which utilizes ` water as an agglomerating medium. Other methods have involved the employment of various binders such as sugars and crysta~
I lizing syrups. S~ill o~her approaches utilize the addition of small amounts of colloidal SiO~ or tricalcium phosphate to the SALP as flow conditioners to improve physical handling properties.
In connection with SAL,P ~:2:~ disclosed in U.S,3,501,314, it is known to dry blend a flow conditioner with dry SALP crystals. The flow conditioner can be any alkali or , ~;1 ~ alkaline earth metal phosphate, caLcium hydroxide or aluminum `1 ~
oxide~ It is taught that the dry flow conditioner particles are adhered to dry SALP particles as a dry coating. The flow conditioners are taught to increase flowability and reduce ... . .
hygroscopicity, However, flow conditioners in general are known to only improve handling characteristics to a slight degree.

!' U.S. Patent 3,255, 073 to Blanch et al.
describ~ a potassium modified sodium aluminum acid phosphate ; having decreased hygroscopicity. This result is accomplished '`! ~ : -by modifiying the original sodium aluminum phosphate molecule ~; with the introduction of potassium. The potassium is explained as replacing hydrogen atoms in the crystalline lattice o ,;

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- sodium aluminum phophate. This improved potassium ~odified sodium aluminum pho8phate is descrlbed as having hygroscopic properties wherein it does not increase in weight by more than about 20~, preferably not more than about 10% of its original weight during continued exposure at 35~. and 75~ relative humidity for 140 hours.
An improvement over U,S. Patent 3,205,07~ is U.S. `
Patent 3,411,~72 to Post et al. which attempts to improve the flow characteristics of Blanch et al~s potassium modified sodium aluminum phosphate by incorpora~ng the potassium ions in a solvent suspension of an alkanol.
A further improvement over U.S. 3,205,773 is disclosed in U.S. Patent 4,05A,678 issued October 8, 1977 to R.
Benjamin et al, In that application, a specific ratio of :
sodium and potassium is used to prepa~ a po~assium modified SALP. The improved SALP product is characterized by increased ~' density and reduced dusting properties. Among the advantages ~,, accrued therebyJ are ease of packagingj use of smalIer bags ~ that palletize more easily, decreased hygroscopicity and improved flow characteristics. All of these properties enable . . .
better handling, in general, e9pecially under conditions of high humidity.

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'1 Brief De`scr_ption of the Invention ~-~

In accordance with the present invention, it has :, :
` been found that a calcium treated sodium aluminum phosphate ~
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having improved handling characteristics and useful as -~`0 a leavening agent in moist doughs and liquid batters can be prepared by contacting a slurry of a complex aluminum phosphate .
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~ 3713'~3 of the formula: Ma)Alb)~lc)(po~)d)-H2oe)9 wh~r i cation selected from the group consisting of sodium~ pota~sium, ammonium and mixtures thereof, a)~ b), c) and d) being numbers, and e) being from 0 to nJ n being a number with a calcium compound followed by granulating the calci~m treated product while drying under such condition~s ~hat a majority of the granulated par~icles are less than 840 micron (through 20 mesh) and at least 90~ less than 2000 micron. There is provided granulated complex aluminum phosphate granules with at ~st a calcium rich outer surface, The process of the present invention can al90 be included as part of the processes for preparing SALP and potassium .; , ; modi~ied SALP. This involves contacting an alkali metal aluminum phosphate with a calcium compound subsequent to the ,, initial formation of alkali metal aluminum phosphate crystals and prior to completion of the dr~ing of ~he slurry. The granulation while drying is then accomplished. ;~
The products of the invention show improved handling characteristics and as leavening acids improved holding and storage characteristics in moist doughs and liquid batters, Improved hygroscopicity means improved storage s~ability of dry blends, Brief Description of the Drawin~s Figure 1 is a representation of an electron probe analysis for calcium made on the cross-section of a particle of the present invention magnified 1,000 times, ,~
~; Figure 2 is a representation of an electron probe .. .
~`~ analysis for phosphorus on the same particle cros.s-section ., ~ as in Figure 1.
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~ ~'7~ ~ 9 Figure ~, is a repre~entation of an elec~ron probe analysis or aluminum on the same particle cross-section as in Flgure 1.
Figure 4 is a representation o~ an electron probe ~.
analysis for calcium on the cross-section of a particle produced in accordance with U.S. Patent 2,550,490, magnified 462 times.
. Figure 5 is a representation of an electron probe analysis for phosphorus on the same particle cross-section as in Figure 4.
Figure 6 is a representation of an electron probe analysis for aluminum on t~e same particle cross_section as in Figure 4.

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~-4664 ~ ~ ~7 ~ ~9 Deta _ed Descriptl _ of the Present In~ention The product of the present in~ention is a calcium treated alkali metal aluminum phospha~e of the formula;
Ma )Alb)HC) (P04 )dH2eJ
~5 wherein M is an alkali metal of sodium or potassi.um, an ammonium ion or mixtures thereof. Ammonium is generally included within the class of alkali metals because of its similar chemic~l:properties. The letter.~ a), b), ~) and d) are numbers representing the various numerical ratios possible ~0 in preparing alkali metal aluminum phosphates. These numbers can be integers or fractions thereo~. The letter e relates to :. .
- the quantity of ~ater of hydration present which can range from 0 ; upward. Representative ratio~ are shown in the dlscussion of the background of the invention. It is intended ~hat this application cover only those ratios which will form an alkali metal aluminum ::;
phosphate, At present, two SALP~s are commercially available as leavening acids, i.e., 1:3:8 and 3:2:8 and these are intended to~be covered specifically. SALP compounds are traditionally prepared by mixing an alkali metal hydroxide or carbonate such

3 as sodium~ 80dium hyclroxide, potassium carbonateJ potassium hydroxide, ammonium carbonateJ ammonium hydroxide or mixtures thereof, with about 60-90% acid~ preferably, about 85-88% and ' ~1 more preferably about 86~ acid in an amount sufficient to provide ;l the ra~io o~ alkali metal to P0~ which is desired. The selection `3 of these ratios can be easily ascertained by one skilled in the . ~ ~
~ the art. The temperature during this mixing period is generally .~

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maintained above ~0CO and belowloo~c. This materlal is then treated with an alwminum compound 9uch as alumina trihydrate, The aluminum compound is generally added incrementally. The : temperature during aluminum addition can rise to about 140C.
a~d then drop to about 110C.
A~ this point, the reaction product is usually cooled to about 60-75~C. for about 15-30 minutes to form a slurry of crystalline alkali metal aluminum phosphate, The slurry is then directed to a Kneadermaster kneader conveyor blender where ;
`l the product is dried and granulated simultaneously.

The Kneadermaster mixers or blenders comprise jacke~ed vessels having an operating pressure of about 80-120 psig of steam. Hot air at a temperature of about 300C. is fed :.'',' ' into the central portion of the vessel. The slurry of reaction ~5 product traverses the length of the Kneadermaster blender moved along by rotating blades. A particular length of the ,.:....................................................................... :
K~eadermaster is designated as the "wet zone" and is indicative of the~distance the slurry traverses in the Kneade~iaster before ".~ , becoming substantially particulate and dry in appearance. Some 0 processes uilize a "short wet zone'~ or a "regular wet zone".

In generaI, the length of the wet zone can be varied and is , ~ .
determined by the loss on ignition (LOI) of the final product.
. ~ , ,~/ LOI is a measurement of the ,~ weight loss of a 2 gram sample ,.. . .
of the prbd~ct when ignited in a muffLe furnace at a temperature of about 750-850C. preferably QOO~C. for a period of about 10 minutes. Variation in LOI can vary the rate of gas release of the product in a leavening system. LOI's can be varied to `;; provide different rates for different leavening and systems. ~:
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The calciual treated alkali m~al aluminum phosphate of the present invention can be prepared using any known acid soluble alkali metal aluminum phosphate material, the pre~erred materials being 1:3:8 and 3:2:8 SALP and more preferably ~;5 1:~:8 SALP.
For ease of description, the remaining description will relate to SA~P ~sodium aluminum pho~phate) 1:3:8 though it is ~ -understood that this description applies to all aluminum phosphates generically encompassed by the invention unless ~10 otherwise stated.
After the initLal formation of SALP crystals in a slurry and prior to drying in the reactor or by reslurrying dried SALP crystals, the SALP slurry is added to or has added to it a calcium compound such as calcium hydroxide.
iL5 Any calcium compound can be used as long as it is reactable ; with the system and does not have a anion which will interfere with the reaction. Illus~rative of such calcium compounds are .
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c- 466 ~Q~7~3,Z9 calcium oxide" calcium hydroxide, calcium carbonate, and mixtures thereof. The preferred ma~erial i9 hydrated lime.
It is preferred to add the hydrated lime to the SALP
slurry to prevent dusting losses. Addition is made incrementally with agitation at a temperature of 80-100C. The calcium compound can be added with equal eEfectiveness at any time after the initial formation of SALP crystalq and before drying~
It is preferred that the SALP slurry be cooled and that the ..~
slurry contain a high percentage crystals prior to calcium treatment. At least some free water or other solvent must be present for effective treatment.

It is critical that ~he calcium treated SALP be granulated while drying the product under such conditions that a majority of the particles are less than 840 microns ~0 mesh) and 90~ are less than 2000 micron ~10 mesh). By majority is meant at least 50~, and preferably at least 60~o Less than 10 of the~product as prepared is larger than 2000 microns. If . ' .
~ proper granulation is not undertakenJ large lumps are formed . .,~' .
on drying (about 5000 micron and above) which must be milled in order to obtain a product having a working particle size distribut~ion of less than about 50 mesh. The milled product has ~`
a faster rate of gas release than SALP and acts like a blend of SALP and monocalcium phosphate. If, however~ the product is granulated while drying to a majority o less than 840 micron under such conditions that the large lumps are not allowed ;~ . ;
to form prior to complete drying the product has the same rate of gas release as SALP in a doughnut dough rate of reaction test .~
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but qlower in a baking powder rate of reaction tes~, both tests being described hereinafter. Any soft lumps form~d during the drying procedure can be broken and remain in ~he granulator until the drying is complete. Any large l~lmps should not be allowed to completely dry In theory, a calcium layer has been formed on the SALP which is fr~ngible lf milled. By gxanulating the product whi~ drying the particles are sufficiently small tha~ exten~ive ~- milling is not required. Depending on the particle size range desired, a fraction such as on oO mesh fraction, can be separated, milled and admixed with the remaining fraction, i.e., , . .
~ the through ~0 mesh fraction to obtain a product of commercially .~ acceptable particle size. Since most o~ the particles as . ~ .
produced are small (less than 2000 micron) so that substantial ~I5 milling is not required, there is generally obtained a granule which has at~least a calcium rich out~r surface.
. ~ It has also been ~ound that an improv~d potassium modlfLed alkali metal alulnLnum phosphate granule having calcium enriched outer surface can be prepared. This product .
~20 is characterized by a considerable improvement in dust properties "
and flow characteristlcs over SALP alone or with a flow conditioning agent without loss of baking performar.ce.
The potassium modified alkali metal phosphate is prepared by ~; the controlled substitution o~ potassium ion for a portion of ~, the sodlum i~on used in producing the sodium aluminum phosphate, 8S iS disclosed in~U S. Patent s,Q54,678.
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It appears that when controlIed amounts of potassium ~o ion are contacted with a mixture of sodium treated food grade . . .,, C_ 1~661~
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phosphoric acid which is subsequently reacted with alumina trihydrate, ~Ai203.3H20)~ to produce sodium alu~.in~n phosphate~
changes in the crystal structure occur that appear to stabili2e the crystal habit of the potassium modified sod~um aluminum phosphate. The potassium modified SALP has better flow ; characteristics and less dust than the prior art SALP compositions, while maintaining reduced hygroscopic properties. This change in the crystal structure manifes~s itself in the form of a ~
doublet pattern as shows by x-ray di~fraction powder patterns. ~;
This doublet suggests that there may be direct substitution of potassium for some of the sodium within the alkali metal aluminum phosphate molecule.
In accordance with the present inventionJ the improved calcium treated potassium mcdified sodium aluminum phosphate is produced by contacting a food grade phosphoric acid with ' a sufficient amount of potassium hydroxide to provide an analysis .. , . ~ .
~i of about 0.5 to about 1.2, more preferably 0.6 to about 1.0 weight , ,'!' percent of potassium oxide (K20) in the potassium modified SALP.
Other potassium containing compounds can also be utilized, such as ` 20 K2CO3J I~HC03J K3PO~ and the likeJ with the proviso that the anion attached to the potassium not contaminate the reaction media or product.
It appears that the K20 analysis is a critical factor '`'1 in helping to achieve changes in crystal structure of the fin~
product which contributes to good flow and dust properties ;~
`- of the product.
The potassium treated phosphoric acid is then contacted :., ^:
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wit~ a isufficient amount of ~odium carbonate (Na2CO3) to provide an analysiis of about ~ to about 3.2, pre~erably about 2.6 to about ~ weight percent of sodium oxide (Na20) in the potassium modi~ied SALP. The Na2CO3 is g~nerally added in a dry or anhydrous stateO
The temperature of the phosphoric acid should be maintained above about 40C. and below abou~ loo C. to prevent crystallization of sodium andjor potaissium phospha~e.
~` Other sodium containing compoundis can also be used, such as NaOH~ NaHCO3, Na3PO~ and the like, with the proviso that the anion attached to the sodium not contaminate the reaction medla or product.
The order of addition o~ sodium and potassium compounds ., i~ not critical though it is preferred to add the potassium compound first.
The sodium-potassium treated phosphoric acid then has its temperature adjusted to a temperature within the range . . .
of from about 40 C. to about lOo~C. and pre~erably approximately 80C. and is contacted with a sufficient amount of an aluminum ~l20 compound such as alumina trihydrate to provide fl desired con-;, centration o~ Al20~ in the final product. The alumina trihydrate ~l~ iis generally contacted with the treated phosphoric acid under , .
conditions agitation so that -lt is uniformly distributed throughout the treated acid. ~
The addition of finely divided alumina trihydrate 1~ -':
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'"1 :, : ~87~3Z9 i accomplished incrementally generally over a period ~uch that the extensive boiling does not occur, i.e., at a rate of about 1-~ a minute. The temperature initially rises to about 120 to about 140C. and then drop~ to about 110C.
The reaction of the sodium-potassium treated phosphoric acid wi~h alumina trihydrate produces a slurry of pota~sium .~ :
modified sodium aluminum phosphate. The reaction generally takes from about 1 to about 3 hours at about 110C. to `10 complete.
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The reactor is then cooled to about 60-75C. for about 15-30 minutes. A calcium compound such as hydrated lime . . .
is then incrementally added with mixing to the slurry of the pota~sium modified sodium aluminum phosphate. After thorough ~ .
L5 mixing, the reaction mass is held until the reaction subsides and then the reactlon product is directed to a Kneadermaster :, :
~; blender or mixer, wherein the material is dried and granulated simultaneously.
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The conditions of the Kneadenmaster blender are maintained so ~hat the dry calcium treated potassi~m modi~ied SALP exiting the Kneadermaster has a Loss on ignition (LOI) of about 16 to about 22 weight perc~ot ~:
Af~er exiting the Kneadermaster, the ca'lcium ~reated ~` SA~P proceeds to a classification system wherein the product is ~`/ classified by ~article size in an air separator or other , ', equivalent apparatus. Depending on the particle size desired, the larger size par~icles ,such as on 60 mesh can be separated, ~;.0 milled and reblended with the remalning materlal. The calcium treated potassi~t modified SALP product is then in a commercial , form ready ~o be placed lnto large bins for packaging and shipping.
`, The LOI of the finished calcium treated pota,ssium modiied SALP
,, product is from~about lo to about 22 weight percent.

" ~ It is desirable to control the amount of excess ; .
:~ ! phosphoric ~acid pre~sent in the reaction mixture after forma~ion of SALP~crystals. SLnCe the reactlon never goes to completion and since it is known that some of~the added alumina trihyd~ate doesnlt reach an excess o~ phosphoric acid is generally present~
",o A greater excess of phosphoric acid is generally desired for the , inclusior.t of larger amounts of calcitlm in the product. The , .. . .
, acid is used in~an excess ranging from about O,l~ to ., '", about 65~. This amount can be achieved by the addition of ,i excess acid at the start of the reaction or to the crystaI
~,., ~,5 slurry. Preferably, ~the excess acid is achieved by decreasing i the amount of aluminum used in the ~eaction. The amount of ~,, aluminum can be decreased to about So~h and preferably to about -,' . .
~, 75~ and more preferably from about 85~ to about 95~ Of . ,~, .

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the amount required to form a desired SALP with a desired allcali metal:Al:POg ratio. If only the aluminwm reactant is decreased, an excess of aLkali metal ion is al~o pre8en~ in the reaetion mixture as well as excess phosphate ion. Evidence has been uncovered which shows that the excess alkali metal ion is part of the sur~ace of the calciur,l treated SALP granule. It has also been noted that it appears ~hat the alkali metal and calcium containing ~urface is less fr&ngible than the surface containing less alkali metal. The latter can be achieved by using only an e}~eess of pho~-`~10 phorie aeid in the reaction mix~ure. It is, therefore, pxeferred ~ to treat a system wi~h calcium which has excess alkall metal ; ~ ~
compound as well as phosphoric acid. This can be effectively achieved by reducing the stoichiometric quantity of aluminum required in the reaction.
.. -At least a portion of the excess acid is neutralized :
i~ by the calcium compound. The calcium compound can al~o be `
i~ added in excess of the amount needed to neut~alize the excess r ~.
, acid.
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~o excess phosphoric acid present in the reaction mixture. There is analytieal evidence which appears to indicate that presenee of monocalcium phosphate on the particle.
- Referring specifically to the drawings, Figure 1 is a representation of an electron probe for calcium of a cross-~5 section of a single particle of the product of the present ;-~; ;i invention prepared in accordance with Example ~ embedded in ;~
epoxy resin. As it can be seen, calcium is abundant at the -outer edge of the particle but deficient in the central portions.
~` Figure 2 shows the phosphorus content of the same particle , ` in the same posi~ion as in Figure 1 which is fairly ; -17~
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evenly distributed over the entire cross se~tion of the particle.
Figure ~ show~ the aluminum content of the same par~icle a~
Figure l. It is noted that the aluminum is abundant in the center of the particle where Figure l shows the particle to be calcium deficient. The aluminum is deficient at the sides of the particle where the calcium is abundant. Since the particle is a cross-section, this evidence is interpreted to show that the particle has a calcium rich outer surface and a SALP
inner core.
Figure 4 shows a representation of an electron probe for calcium o~ the cross-saction of a particle prepared in accordance with U.S. Patent 2,550,490 as reported in Example 20 herewith. As it can be seen~ calcium is evenly distributed over the entire cross-section of the interior of the particle. Figure 5 shows that the phosphorus content of the same particle is evenly distributed over the entire cross-section of the particle. Figure 6 shows that the alumLnum is likewise evenly distributed over the entire cross-sectionO This evidence appears to show that the material o~ the present invention has a calclum rich outer la~er superimpos~d on a core of material which is not calcium rich in contrast to that o~ the prior art.

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The calcium treated potassium moclified sodium aluminum phosphate Ls characterized by a more un:Lform con-sistency, i8 more easlly handled and has a lower hygroscopicity than the potassiù~ mod~E$ed SALP alone.
The calcium treated potassium modified SALP particles are harder than the non-potassium contalning SALP particles.
The particle hardness contributes to the improved handlability ~ ' of the product. `~
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As noted previously3 good dust and flow chara~terlstics of leavening acids such as the calcium treated SALP or potas~ium modified SALP are extremely important in plants which mlx and package dry mixes for the preparation o~ baked products and the like, by using automatic feeders for metering the ingredients. The leavening acid i8 generally placed in storage bins having funnel-like openings at the bottom, Ideally, it is desired that the leavening acid be removable from the . ~
bins at a steady, controlled rate, However, it has been found ~lo during the course of removing the leavening acid from the ~; storage bins, intermittent flow sometimes occurs1 and on some occasions, flow will completely cease. This cessation of Elow is called "bridging" and i~ caused by an open path extending rom the bottom of the storage bin to the top of the leavening .. 5 acid. The problems of bridging can sometimes be ameliorated by the addition of flow control agents such as Cab-O-SilTM
. . (a form of SiO2 sold by Cabol Chemical Company) or tricalcium ~:; phosphate, to the leavening acid. The drawbacks of the approach, ;` however, are that these flow agents are expensive, sometimes unpredictable in the effect they will have on flow characteristics `~ arld, unfortunately, can also create dust problems of their own.

The calcium treated SALP's of the present invention have suf~iciently improved flow and dust characteristics to ~, overcome a majority of these problems.
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The compositions of ~he present invention are useful as leavening acids in such areas as blscuit mixes~ pancake mixes, waffle mixes, cake mixes, doughnut mixes, muffin mixes~ -self-rising flour and the like. The compositions of the present invention are also effective as leavening acids in mois~ure containing doughs and liquid batters -as they have good holding characteris~ics, i.e., the ability to be in contact with moisture and bicarbonate of soda without significant loss in leavening acid capabilities. This is a particular advantage in liquid batters 6uch as pancake batter whether made for use within one days time or packaged and sold for latter use. A leavening system ih a liquid batter using the product of the invention will not go "flat" after standing for a short period of time. It is also possible to program leavening acid rates of gas relates for specific applications. The ratio of milled to unmilled products of the invention can also be adjusted to program the rate of gas release. Various other materials can ~lso be added to the compositions of the present invention to adjust rate such as mono-calcium phosphate.
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Another advantage of the present invention is the ability to add significant quarltities of calcium to self-rising J; 10ur compositions without seriously affecting the rate of leavening action. This is in contrast to the well known fact - that blends of monocalcium phosphate and SALP have a ~ast gas .
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producing rate. This controlled leavening action even in the presence o~ a calcium surface is a significant improvement in ~elf-rising flours.
The products of the present invention are also le5 hygroscopic than normal SALP materials or potassium modified SALP ' s as disclo~ed in U . S . Pate~t 4, Q54, 678 .
This allows for easier plant processing of the material, Mills and screens do not become caked after short period~ of use as with the prior art material. The decrea~ed hygroscopicity al~o increases the storage stability of the dried product itself . . .
as well as dried blends using ~he same. Decreased hygroscopicity allows the user a wider range o~ use since the user can leave the product open on the floor without ~ear of excessive ~aking.
~: The invention will be illustrated in the Examples which follow, .
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EXAMPLE~
Calcium containing potas~ium modified sodium aluminum phosphates are prepared as follows:
A reaction slurry was prepared by treating 60~
phosphoric acid with a sufficient amount of potassium nydroxide ~;
to provide an analysiY of 0.8 t 0.2 weight percent potassium ~-;
oxide (K20) in the final product. The potassium treated phosphoric acid was then reacted with a sufficient amount of ; dry sodium carbonate (Na2C03) to provide an analysis of 2.8 +
~ 10 0.2 weight percent sodium oxide (Na20) in the final product~
, ~ .
`` These percentages were used unless otherwise noted in Table I.
The temperature was kept above 40C. to prevent sodium and/or potassium phosphate crystallization.
- After adjusting the temperature of the mixture to , 15 above 80C., alumina trihydrate was then admixed with the sodium/potassium treated phosphoric acid in a quantity less `
; than the amount needed to form a 1:3:8 sodium aluminum phosphate.
; ; The amount of alùmina added is recorded in Table I. The ,ij addition of the aluminum trihydrate was accomplished incrementally with slow agitation to insure uniform mixing of the aluminum ~;
trihydrate in the acid. The mixture was ~hen reacted for the..
time given in Table I at a temperature of aboutllO" c to . .
form a reacted slurry.
A small quantity (See Table I) of the reacted slurry 1 25 was placed in a tub shaped covered jacketed mixer having two contrarotating mixing arms with downwardly dependent mixing ~:"i ` ~ :
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~(~8'~ 9 blades. The cover was provided with an ingredient inlet and a steam outlet. After covering the tub, the hydrated lime was added at a controlled rate. Process variations are shown in Table I. After the lime had reacted, the product was dried while under sufficient mixing to granulate ~he product.
I The dried product was finally milled in a Raymond Laboratory Hammer Mill fitted with a screen having 1/16 inch ~1.59 mm) openings. The product had the elemental analysis and sieve analysis a~ shown in Table II.

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~ ~ ~'78 ~ ~ C-4664 A standard method for evaluating baking performance of a leavening acid is the baking powder rate of reaction test (BPRR). In this test, a baking powder is formulated comprising a leavening acidJ sodium bicarbonate, starch and water, The purpose of the BPRR ~est is to observe and measure the rate , of carbon dioxide discharge from the baking powder as a means `i .
. of evaluating the suitability and quality of the leaveni~g . .: , ` acid candidate as a baking acid, Ideally, there should be a sufficient initial release ,~
of carbon dioxide in the ba~ing mix to facilitate mixing and `-^. blending of the constituents. The mixture should also be ~ capable of suppressing the release of carbon dioxide until ~ .
., such time as the mix is placed in an oven and heated, whereupon ~ 1 ' more carbon dioxide is reIeased during baking, The BPRR test ,, ~ .
~ll5 is conducted at a temperature of 27C. - 0.5C. The . !1 ~;~ leavening acid and sodium bicarbonate are used in proportions :i.,~ that are theoretically capable of;~liberating 200 cc of carbon .
. ~
dioxlde, More details regarding reaction rate testingJ as ' ;7, ' well as the apparatus required, are ound in Cereal ChemistryJ ,~
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Volume 8J pages 423-433 (1933). The baking powder rate of reaction tests or Examples 1-11 are given in Table III.

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3~)1378Z9 c-l~664 TABLE III
~, Example 2 mln. 4 min. 10 min.

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- 1~) 40 57 85 11 31 45 67 . `
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EXAMPLES 1~-15 A slurry of potassium modified sodium aluminum hydrated phosphate was prepared as in Example l. AEter cooling to about 80 C, lime was then incrementally added to the reaction mass in the reactor and agitated for reaction periods of about 1-4 minutes between additions. The conditions of reaction are given in Table IV.
The slurry of calcium treated potassium modified .
sodium aluminum phosphate is directed to a Kneadermaster kneader-conveyor blender or mixer, wherein the material i9 dried and granulated. The condltions of the Kneadermaster blender are maintained so that the dry calcium treated potassium modi~ied SALP exiting the Kneadmaster has a loss on ignition (LOI) of about 22 weight percent.

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After exiting the Kneadmaster, the calcium trea~ed potaqsium modified SALP proceeds to a mill and air classification system wherein the product is milled and classified by particle ~ize in an air separator. The sieving analysis is shown in Table V. The calcium treated potassium modified SALP product is then in a commercial form reaty to be packaged and shipped.
The LOI of the finished potassium modified SALP product ls from about 19.; to 20.5 weight percent. .
: The product was free flowing, non-dusting and did ; lo not blind the screens when milled. The analysis ~or the product : is given in Table V.
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'7~3'Z9 C-In a reactor fitted with a condenser, thermometer and mechanical stirrsr was placed phosphoric acid in the amounts given in Table VI. The acid was heated to assist in dissolving the ingredients to be added (about 40-50C.). Sodium carbonate and, in some instances, potassium hydroxide (in a 45~
. .
aqueous solution) were slowly added to the heated acid at such a ratie that the reaction was allowed to subside. ~he amount added is given in Table VI~ A clear~solution was obtained.
0 The temperature of this solution was adjusted to;80-85C.
Hydrated alumina (Al203 3HzO) was slowly added to this solution at 80-85C. over a 1 hour period. The amount of hydrated ~", `"r. alumina added is given in Table VI. The temperature of the .~ mixture increased to 110-120C. After all the hydrated alumlna ~`5 was added, the mixture was allowed to react about;l~? houri"at ;~
110-120C. ~A white v1scous slurry was obtained.
The slurry was transferred toithe~mixer bowl of a kitchen type mixer. Hydrated 1ime in the amount giVen in Table VI wa~ added to the slurry. The slurry was mixed at low speed scraping the 0 walls of mixer bowl until the lime was well blended. A white ^~ and creamy material was obtained.
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- ,, j This~material was transferred to a farinograph (a jacketed ~igma bladed blender) which was held at 98C. to granulate and dry~the product. Time required to dry averaged 30-4~5~minutes. on ocoassion ~soft lumps were formed when too muoh material was~being~dried. The soft lumps~were~broken up before the product had~completely dried and drying was continued.
~ A fine white powder was obtained.
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, .~ , C~4664 3'Y8'~9 . Excess ~ c~l -:~ ~1 ~ O O
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108'î~9 X~MPLE 20 Control _Preparation in accordance with r~,s. 2J~ 490 In a reactor fitted with a condenser, thermometer and stirrer were placed 844 grams of 75~ phosphoric acid.
The acid was heated to 70C. and 27 grams of sodium carbonate was slowly added. The mix~ure was allowed to react until a clear solution was obtained. The clear solution was heated to 90C. and 114.5 grams of hydrated alumina was added at such a rate that the charge did not bail over (about 20 minutes).
The condenser was removed and the charge was allowed to boil ~^; down until a white viscous slurry was obtained. Initial temperature was 135C. Evaporation temperature was generally ~: .
about 115-120C., ~' ' ~, The slurry was transferred to the bowl o~ a home-type ;, 15 mixer con~aining 11.84 g of hydrated lime. The slurry and lime were . -., .
mixed at low speed until well blended. A white and creamy material was obtained. This material was transferred to a ,,, Eobart mixer and~mixed until it solidified intolarge lumps. The product ~as oYen dr~ed at 98~C. for four hours. The product was m~lled in Raymond Laboratory Ha~mer Mill, fltted with a screen.
The elemental and sieving analyses are given in Table VII.

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TABLE V I I

T O T A L ~a= Excess for 1 :3:~ SALP
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Moles P ~ 6 3 . 92 2 . 54 Moles Na~ 0. 51 0. 49 0. 02 Moles Al 1.47 1.47 0 i Moles Ca l o 60 :
Moles Ca/ ~ 0. 63 ~ ;
~:~. Moles Excess P
-~ , 0. 02 Excess Na /Moles ) ~: Sieving Analysis on 60 8 ,l throu~ 60 on 100 42 ~o through 100 on 140 20 ~; through 140 30`~
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1.087B~9 C-4664 The compounds of the present invention can be used effectively ln preparing self-rising flour biscuits, Self-rising flour (on SRF) is de~ined in the Federal Register o~ May 2, 1961, Title 21, Part 15, section 15.50(a)J
Definition and Standards of Identity, a9 follows:
"Self-rising flour) self~rising white flour, self~;
rising wheat flour, is an intimate mixture of flour, sodium ; bicarbonate, and one or more of the acid-reacting substances monocalcium phosphate~ sodium acid pyrophosphate, and sodium aluminum phosphate. It is seasoned with salt. Then it i9 .
tested by the method pr~scribed in paragraph (c) of this section~
I ~.
not less than 0.5 percent of carbon dioxide is evolved. The~
acid-reacting substance is added in su~ficient quantity to '!;, '~ ' neutralize the sodium bicarbonàte,' The"combioe d weig~t;of~such acid-reacting substance and sodium`b'icarb~nate is no't more than 4.5 parts to each 100 parts of Iour uséd."
The term "self-rising-flour- used herein is intended ~ ~ .
to describe compositio~ within the de~init~on set ~orth above. `

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' c-l~664 ~8 ~ ~ Z9 saking response was detenmined by adding a specified portion of the product of the invention to a standard self-rising flour formulation comprising:
Sodium Bicarbonate ~.3 gms Leavening Acid See Table VIII Sel~-rising ; Salt 5.4 gms Flour Mixture Flour 240 gms.
- Shortening 32 gm9 `~ Milk 165-170 cc.
lo The amount of leavening acid required can be determined by its neutralizing value. Its neutralizing value is a ~;
measurement of the parts by weight of sodium bicarbonate which will be neutralized by exactly 100 parts by weight o~ a given leavening acid. The amount of leavening acid required was obtained by multiplying the amount of sodium bicarbonate used (in this case 3.3 gms) by 100 and dividing the result by the neutralizing value of the leavening acid. This amount was ., :
added to the sel~-rising flour formulation. Biscuit were baked under controlIed conditions as follows:
1) Heat electric oven to ~40F;
.
2) Weigh out self-rising flour, shortening and milk;
,. .
3) Cut shortening into self-rising ~lour in Hobart blender for 1 1/2 minutes until mix is fine and crumbly;
, 25 4) Roll on cloth covered board with 1/2" gauge rails using dusting flour and cloth covered rolling pin;
; 5) Cut dough with 2 i~ch cutter and bake 18 minutes at 450F.
Biscuit bake tests and evaluation of the results there- ~

37- ' ~, .
- . .. ~ , , . . . ~, . . ; . , ~ 8 ~ 9 C-4664 from iq explalned in Cereal Laboratory M~thodsJ 6th Ed., American As~ociation of Cereal Chemists, 1957 pp. 46~4~, The results of the biscuit bakes including the amount of leavening acid used are reported in Table VIII .
The biscuit weight is the weight of 7 biscuits just after baking. The slx most evenly sloped biscuits are then measured to provide biscuit height in inches. The volume is the number of cc's of rope seed displaced by six biscuits. The specific volume is obtained by dividing the volume by biscuit welght.
Amount of acid used, dough weight and biscuit weight are in grams.
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~ C-4664 10~'7~9 The products of the present invention were tested in a doughnut dough reaction rate test. The doughnut dough ~ reaction rate test is an analytical method used for reactivity ; studies o~ baking acids. The tes~ procedure involves reacting ~; ~

5 the acid with sodium bicarbonate while the reactants are :; suspended in a moist doughnut dough at a temperature of 27C. -~
+ 0.5C The proportions of acid and bicarbonate employed ; are those which are capable of theoretically li~erating 200 cc.
~; of CO2 gas as 0C. The remainder of the ingredients are outlined in a paper on reaction rate testing which appeared in Cereal ~' ~
f'~ Chemis-try, Vol. 8, American Association of Cereal Chemis~s, St. Paul, Minne~ota, 1931~ pp. 423-33 Both milled and ~ ~:
unmilled samples were tested. The results are reported in Table rx beIow. All results are relative to the bicarbonate ~: 15 of soda blank or control.
Table I~
Dou~hnut Dou~h Rate of ReactionMinut~s ~ ~ Product of Example ~CaO 2 15 Q _ ~ on ~0 mesh _ ,--i 1 2 3 42 54 ~ 12 12.2 3 10.5 51 ~5 14 29.
; 2 14.2 60 7l~ 18 1~.~
14 '5 ~ 56 13 0.6 1.4 49 64 15 1.5 . Product o~ U.S.O 42 56 14 --'~ Patent 4,054r678 -:
--i Bicarbonate of 0 31 35 4 ~--Soda Blank . , , :. :

~ ~ ~ _4j~_ C-~'661~

Doughnut dough rate o~ react:ion tests were conducted on a single sample milled and unmilled at the same particle sixe. The data as reported ln the Table X below shows ~hat milled samples of ~he same particle size generally have a faster rate of rea~tion than the unmilled.
Similar studie~ are also reported in Table X

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:DOUGH~UT DOUGH RATE OF REACTION TEST ON SIEVED FRACTIONS
~,OF THE PRODUCT OF EXAMPLE 5 .. . .
DOUGHNUT DOUGH RATE OF REACTION IN MIMUTES, Unmilled Milled Mesh 2 15 2 15 .~ . .

~- Soda Blanks 29-32 32-36 3-4 ~,..

$ievin~,%
B~ WeightUnmilled Milled j,, . ;1 on 60 64.5 24.7 ,15 ~hrough 60 On 100 1 3.8 23.2 Through 100 on 140 6.4 12.4 rhrough 140 on 200 6.4 15.8 ç rrhrough 200 on 400 5- 17.8 :"
rhrough 400 3.6 6.1 ~;'.'.",':
Product o~ Example 5: 700/O Alumina ~, 91.8 ~eutralizing Value K20 = .67%
Na20=2 . 900/O

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~ABLE XI

D~UGHNUT DOUGH RATE OF REACTION ON SIEVE FRACTIONS
.
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; of Reaction Minutes : : .
ProauctMesh FractionT~E~ 2 15 ~ ~:
of Example ' ;~ 6 60-100Unmilled 36 49 13

6 60-100 Milled 38 50 12 60-100 Milled 71 95 18 140-200 Milled 75 93 18 16 60-100Unmilled 47 64 17 16 60-100 Milled 45 63 18 : , 16 140-200Unmilled 49 70 21 .
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~-. 19 60-100 Unmilled 52 78 26 1, .
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19 60-100 Milled 63 86 23 ;`;~
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19 140--200 Umnilled 70 94 24 ~: ' 19 l40-200 .
3 140-200 Milled 54 75 21 " ':

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which follows ,, ~ :' :

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Humidification tests were run on a number of samples to determine the amount of moisture pickup over an extended period of time in order to obtain an indication of the hydroscopisity of the sample. The tests were run in accordance wi~h ~he pro-cedure outlined in U.S. 3,205,073. The following data wa~ ob-tained:

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_ample 21 __ .

;` In order to test the holdlng qualities of the leavening acid of the present inventlon in liquid batter, pancake batter was prepared and held for various perlods of time. Pancakes were baked dzily. Volume of gas and bubble Eormation in the batter and pancakes were noted.
~ The pancakes were prepared from the foll~wing recipe:

`~ 3 cups sifted self-rising flour ~; 4 tablespoons sugar ; 2 eggs, beaten 2 2/3 cup milk 6 tablespoons oil The self-rising flour was prepared by blending together:

^` 400 gms. flour 5.5 gms. Sodium Bicarbonate 9.0 gms. salt ~i 3.76 gms. product of example 3 ~i .
After initial baking, one-fourth cup milk was added to thin the batter slightly. The batter was refrigerated in a covered polypropylene bowl. Pancakes were baked using about : ........................................................................ ~ ~
: ,,.
; 20 one-fourth cup per pancake each day for seven days from the ;~` refrigerated~batter. The pancakes were observed to have the same similar light texture. The pancakes were tender and pleasant tasting. No pressure build-up was observed in the~bowl. The ~`j number of bubbles observed during baking appeared to be the same `,'25 throughout the test period.

~, Example 22 `~

S
Pancakes were also prepared according to Example 21 "~ using 7.52 grams of the product of Example 3 in place of the 3.76 ~'~ grams used in Example 21. The batter was prepared in the evening and refrigerated. Pancakes were baked the next day and the ~30 following days for a total of ei8ht days. ~ ~
~- These pancakes were compared with those made using a ~; ;
commercislly available leavening acid prepared in accordance with ~' the process of U.S. Patent 4, 054, 678.

-51A_ .. . .

~ l Q ~ C-4664 :
~ Ex~ple 22 (continued) '.:

', The pancakes prepared with the leaveningacid o~ the inventlon were noticeably l:lghter than those prepared using the commercial leavening system held for the same length of time.
f Pancakes made using the leavening acid of the inven~ion had good !': ." 5 texture but those with the commercial leavening acid were slightly -`~; tough and did not rise as much as based on visual observation.
~ `~ The invention is defined in the claims which follow.
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Claims (24)

WHAT IS CLAIMED IS:

1. A process for preparing an improved alkali metal or ammonium aluminum phosphate which comprises:
a) contacting a slurry of a complex phosphate of the formula: MaAlbHc(PO4)d?H2Oe, wherein M is a cation selected from the group consisting of sodium, potassium, ammonium and mixtures thereof, a, b, c and d are numbers and e is from O to n, n being a number, with a calcium compound, and b) granulating the product of step a) while drying under such conditions that a majority of the granulated parti-cles when dried are less than about 840 micron, and at least 90% are less than 2000 micron, said granulated particles of complex phosphate having a calcium containing outer surface.

2. The process as recited in claim 1 wherein said slurry has an excess of phosphoric acid and at least a portion of said acid is neutralized by said calcium compound.

3. The process as recited in claim 2 wherein at least 80% of said excess acid is neutralized.

4. The process as recited in claim 1 wherein said cation is sodium.

5. The process as recited in claim 1 wherein said cation is potassium.

6 The process as recited in claim 1 wherein said cation is a blend of sodium and potassium.

7. The process as recited in claim 1 wherein said calcium compound is selected from the group consisting of calcium oxide, calcium hydroxide, calcium carbonate, and mixtures thereof.

8. In a process for the preparation of an alkali metal aluminum phosphate which comprises:
a) contacting a food grade phosphoric acid having a concentration of about 70.0 to about 90.0 weight percent H3PO4 with a sufficient amount of an alkali metal ion selected from the group consisting of sodium, potassium and mixtures thereof and aluminum ion to form crystals of an alkali metal aluminum phosphate in a slurry; and b) drying and granulating the alkali metal aluminum phosphate; the improvement which comprises:
1) contacting said alkali metal aluminum phosphate slurry with a calcium compound subsequent to the initial formation of alkali metal aluminum phosphate crystals in the slurry and prior to the completion of the drying in step b); and 2) granulating said product while drying under such conditions that a majority of the dried granulated particles are less than about 840 micron, and at least 90% are less than 2000 micron, said granulated particles of alkali metal aluminum phosphate having a calcium containing outer surface.

9. The process as recited in claim8 wherein said phosphoric acid has a concentration of from about 85.o% to about 88.o%.

10. The process as recited in claim 8 wherein said alkali metal ion is sodium ion.

11. The process as recited in claim 10 wherein said sodium ion is provided by a compound selected from the group consisting of sodium carbonate, sodium hydroxide, sodium bicarbonate and sodium phosphate and mixtures thereof,

12. The process as recited in claim 11 wherein said sodium compound is sodium carbonate.

13. The process as recited in claim 8 wherein said aluminum ion is provided by alumina trihydrate.

14. The process as recited in claim 8 wherein the ratio of alkali metal:aluminum:PO4 is 1:3:8.

15. The process as recited in claim 8 wherein the calcium compound is selected from the group consisting of calcium oxide, calcium hydroxide, calcium carbonate, and mixtures thereof.

16. The process as recited in claim 15 wherein said calcium compound is calcium hydroxide.

17. The process as recited in claim 8 wherein said slurry has an excess of phosphoric acid and at least a portion of said excess acid is neutralized by said calcium compound.

18. The process as recited in claim 17 wherein at least 80% of said excess acid is neutralized.

19. The process as recited in claim 17 wherein said excess phosphoric acid is obtained by adjusting the ratio of H3PO4, alkali metal ion, and aluminum ion such that after adding the aluminum there is an excess of phosphoric acid, at least a portion of said excess being neutralized with said calcium compound.

20. The process as recited in claim 19 wherein the ratio of aluminum to phosphate is decreased to provide the excess phosphoric acid.

21. The process as recited in claim 20 wherein the amount of aluminum is decreased to within the range of from about 85% to about 95%. of the stoichiometric amount.

22. The process as recited in claim 17 wherein the ratio of Na:Al:PO4 equals 1:3 :8.

23. The process as recited in claim 8 wherein said slurry is cooled prior to the addition of said calcium compound.
24. The product formed by the process of claim 1.
25. The product formed by the process of claim 8.
26. The product formed by the process of claim 14.
27. The product formed by the process of claim 17.
28. The product formed by the process of claim 20.
29. The product formed by the process of claim 21.
30. In a process for the preparation of a potassium modified sodium aluminum phosphate which comprises:
a) contacting a food grade phosphoric acid having a concentration of about 70.0 to about 90.0 weight percent H3PO4 with a sufficient amount of potassium ion to provide an analysis of about 0.5 to about 1.2 weight percent as K2O, and sodium, in an amount sufficient to provide in combination with the amount of potassium the amount of alkali metal needed to form the desired alkali metal aluminum phosphate, to provide a sodium of potassium treated phosphoric acid;
b) contacting the sodium-potassium treated phosphoric acid with an aluminum compound to form a potassium modified sodium aluminum phosphate crystalline slurry; and c) drying and granulating the potassium modified sodium aluminum phosphate; the improvement which comprises:
1) contacting said potassium modified sodium aluminum phosphate slurry with a calcium compound subsequent to the initial formation of potassium modified sodium aluminum phosphate crystals in the slurry in step b) and prior to the completion of the drying in step c); and 2) granulating said product while drying under such conditions that a majority of the dried granulated particles are less than about 840 micron, and at least 90% are less than 200 micron, said granulated particles of potassium modified sodium aluminum phosphate having a calcium containing outer surface and having a loss on ignition of about 16 to about 22 weight percent.
31 . The process as recited in claim 20 wherein said potassium ion is provided by a compound selected from the group consisting of potassium hydroxide, potassium carbonate, and potassium phosphate and mixtures thereof.
32. The process as recited in claim 31 wherein said potassium compound is potassium hydroxide.
33. The process as recited in claim 30 wherein said phosphoric acid has a concentration of from about 85.0% to about 88.0%.

34. The process as recited in claim 30 wherein said sodium ion is provided by a compound selected from the group consisting of sodium carbonate, sodium hydroxide, sodium bicarbonate and sodium phosphate and mixtures thereof.
35. The process as recited in claim 34 wherein said sodium compound is sodium carbonate.
36. The process as recited in claim 30 wherein step a) is maintained at a temperature of about about 40°C.
37. The process as recited in claim 30 wherein the ratio of Na+K:Al:PO4 is 1:3:8.
38. The process as recited in claim 30 wherein said slurry has an excess of phosphoric acid and at least a portion of said excess is neutralized with said calcium compound.
39. The process as recited in claim 38 wherein at least 80% of said excess acid is neutralized.
40. The process as recited in claim 38 wherein said excess phosphoric acid is obtained by adjusting the ratio of sodium ion, potassium ion, aluminum and H3PO4 such that after adding the aluminum there is at least an excess of phosphoric acid, said excess being neutralized with said calcium compound.
41. The process as recited in claim 40 wherein the ratio of aluminum to phosphate is decreased to provide said excess phosphoric acid.
42. The process as recited in claim 41 wherein the ratio of aluminum to phosphate is decreased to a range from about 85% to about 95% of the stoichiometric amount.
43.The process as recited in claim 30 wherein said calcium compound is selected from the group consisting of calcium oxide, calcium hydroxide, calcium carbonate, and mixtures thereof .
44. The process as recited in claim 43 wherein said calcium compound is calcium hydroxide.
45. The process as recited in claim 8 wherein said slurry has an excess of phosphoric acid and at least a portion of said excess acid is neutralized by said calcium compound.
46. The product formed by the process of claim30 .
47. The product formed by the process of claim40 .
48. The product formed by the process of claim 42.
49. The product formed by the process of claim 44.
50. The process as recited in claim 43 wherein said slurry is cooled prior to the addition of said calcium compound.
51. As a new baking acid, the product of claim 24.
52. As a new baking acid, the product of claim 25.
53. As a new baking acid, the product of claim 46.

54. In a method for preparing a baked good which is leavened with the aid of a leavening acid the improvement which comprises using for at least a portion of said leavening acid the product of claim 24.
55. The method as recited in claim 54 wherein said baked good is selected from the group consisting of biscuits, and pancakes.
56. The method as recited in claim 54 wherein said leavening acid is incorporated for at least a portion of the leavening acid requirement in a self-rising flour.

57 . A baked good using for at least a portion of its required leavening acid, the product of claim 24.
58 . The product as recited in claim57 wherein the baked good is selected from the group consisting of biscuits and pancakes.

59. A self-rising flour including for at least a portion of its leavening acid, the product of claim 24.
60. In a method for preparing moist doughs and liquid batters containing a leavening acid, the improvement which comprises using as said leavening acid the product of

claim 24.