CA1093103A - Refractory mix composition and method of preparation - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The invention relates to an alumina based, phosphate bondable, dry refractory mix composition exhibiting an extended shelf life of up to eighteen months and longer. The mixture has the following preferred composition on a weight percentage basis:
40-70% sized tabular alumina, 15-35% calcined alumina, 2-10%
hydrated alumina, 1-10% calcium aluminate cement and an acid ingredient such as 3 to 15 weight percent of a 115 percent concentration of polyphosphoric acid. The mix is prepared by a method which comprises the steps of formulating dry ingredients into a mixer, mixing the dry ingredients to a homogenous state, then adding a liquid acid ingredient to the mixture of dry ingredients, and subjecting the dry and acid ingredient mix to a high intensity mixing action for a predetermined period of time.
The product is substantially dry to the touch.

Description

Case 4179 3 ~ ~ 3 BACKG~OUND OF THE INVENTION

m e present inven~ion ~enerally relates to dry re~rac~o~y mix compositions and the method of prepar-ing the same~ and more particularly, to a single package phosphate bondable dry refractory mix compo ition, and a high in~ensity mixing process for preparing the mix.
The term t'refractory specialty'l has often been used to refer to a bro~d class o~ unconsolidated re- -fractories, i.e. not in pre~ormed shapes such as molded brick~ Re~ractory specialties are typically utilized in monolithic refractory constructions wherein the re-fractory is installed in situ and forms an integral jointless structure. Many refractory specialties are popularly produced, packaged, and shipped as mixes --blends o~ materials proportioned in a definite manner.
These mixes may be produced and shipped in a substan-tially wet or plastic condition for use without ~further treatment, in a dry state requiring liquid tempering and mixing, or as a two package (one dry, one wet) system 2C requ~ring intermixin~ of the package components with or without the addition of a liquid prior to the use of the mix. m us, refractory specialty mixes used for mono-lithic refractory construction may be further distin~
:
guished and classified, in either of two ways, by the l~
condition in which they are shipped, e~.g.~ plast~c, ary~ -and wet, or moreoYer~ by the techniques ky ~hich they are applied? e g~ ? ramming, gunning, casting and trowel-. . ~

~ Case 4179 3~03 ing, or both We~ refractories are sub.stantially wet to ~he .to.uch and, ~onver.sely~ dry ref~.actories are sub.stanti211y dry to the touch, Plastic re-~ractories are refractorY ~aterials, generally tempered with water into a.sti~f plasti.c condition ha~ing a desir.ed consis~ency~ t~at .can be extruded and thàt ha~e suitable wo~kability for use in forming a monolithic structure ~l~hout further preparation~ Plastic refractories are often rammed into place.
Ramming mixes, by definition, consist essen-tially o~ ground and sized refractory aggregates,with amounts of other m~terials added to promote workabili~y and bonding, that cannot be extruded but ha~e suitable properties to permit ramming into place to form a mono~ ~
lithic structure. Hence, ramming mixes are usually ~.
shipped in a we~ state and further liquid addition is not required for the application technique.
A castable, in contrast, is deflned as a combination o~ re~ractory grain and suitable bonding agent that, a~ter the addition of a proper liquid,is ~`
generally poured into place to ~orm a refractory shape or structure which becomes rigid due to chemical actlon. ~ :
Castables are ge~erally cast or gunned into place.
Refractory mix compositions which utilize high percentages of ~arious inert refractory aggregates, especially alumina, and which include phosphoric acid or phosphates are kPown in the art. ~hen phos-~ Case 4179 3L0931~)3 phoric acid or acid phosphate salts are used to generatea chemical bond premature hardening and loss of work-ability is often encountered and limits the shelf life of the mixes. The premature uncontrolled presetting -~
of these phosphate bondable mixes is believed to be caused by a series of complex chemical reactions between the phospha~e ingredients and the alumina bearing materials in the mix.
Presently, there are phosphate bondable re-fractory mix products marketed as a two package (each ha~ing mult~ple ingredients) system. A typical two package product includes a package having damp mix ingredients containing tabular alumina and an equil-ibrium mixture of phosphoric based acid, and a package ~ - alumina of dry mix ingredients containing tabular alumina,calcined/
hydrated alumina and a calcium aluminate cement~
Blending o~ the ingredients of the two packageæ wlth the addit1on o~ water to achieve~a desired consis-tency initiates setting of the mixture. 3ecause the `~
damp and dry packages cannot be lntermlxed until a short time be~ore the mix is to be applied, each `-package must be separately produced, packed and maintain-ed. The shelf life of the ~amp package, moreover, `
:
is limited in time due to reactions of its consti- ;
tuent acid and alumina. Such reactlons are accel-erated if the damp component package is contaminated, poorly sealed or exposed to excessive heak. ~he limited shelf life of the damp component package can result in warehousing or production scheduling ;~
3 problems or both. Use of a two package mix also -exposes the placement operation to the possibility ~_ 4 -.

~ Case 4179 ~0~3~1Ll)3 of errors, e.g., in weighing and mixing the com~
ponents, which can result in an inferior product and wastage, and increased preparation time of the user. Clearly, a single package mix having an extended shelf life can lead to improved economies.
Techniques for extending the shelf life of single or two package phosphate bondable preparations agent ~nerally encompass use of a sequestering/or inhibitor ~o retard premature reaction between the alumina and phosphoric acid. Vnited States Patent No. 3,622,360, for example, discloses an alum~na-phosphoric acid rammin~ mix composition. The ramming mix of United States Patent No. 3,622,360 is described as having an extended shelf life and prolonged workability specifically due to the addition of an inhlbitor selected from the group consisting of nitrilotria-cetic acid and ethylenediaminetetracetic acid whlch promote the age retardation of the mix. me ramming mix described is tempered with water to achieve a desired plasticity.
United States Patent No. 3,197,315 discloses the formulation and use of a typical high alumina content wet refractory composition, packed in suitable paper containers for shipment, utilizing 85% phosphoric -~
acid. m e alumina particles, as an additional re-quirement, are precoated with heated fatty acids such as palmitic or stearic acids or mixtures thereof to produce/lubricated, free-flowing gunning composition.
The composition disclosed therein also contains 3~ amounts of boric acid used as a binder in conjunction with the phosphoric ac1d. The addition of small ~;

, .. ., . : . ...

9 3 lO 3 Case 4179 amounts of boric acid in such a composition is known to retard alumina-phosphoric acid reactions. The compos~tion is prepared by heating the ~atty acid mixture components to above the melting point of the fatty ac~d mixture which is added to a premixed batch of the remaining ingredients ~or intermixing of the entire blend.
United States Patent No. 3,303,034 teaches a plastic refractory mixture with phosphoric acid and 1~ aluminous material from the group consisting o~ tab-ular alumina, bauxite, kyanite and diaspore that is disclosed as suitable for installation by ramming techniques after storage periods of up to six months.
The improved storage shelf lire is attributed to the presence o~ bentonite as plastlclzer which is less reactive with the phosphoric acid than the previously used plasticizers.
United States Patent No. 2,85Z,401 teaches ~-high temperature phosphate bondable refractory com-posltions in the form of unconsolidated particles that are substantially dry to the touch. The compositions;
o~ United States Patent No. 2,852,401 are formed by lncorporatlng phosphoric acid in a~refractory~batch having a ma~or proportion of refractory aggregate and ~ ~-a minor proportion of aluminous materlal that~is chemically reactive with phosphoric acld at room temperature~ followed by drylng of the;mixture at a temperature not in excess of about 125F. Hence, the refractory aggre~ate must be sufflciently inert that ~;
3~ it does not, upon the addltlon of the acld, produce~;
`;, _ 6 - ; ~

3~3 sufficient heat of reaction to bring the batch temperature above the critical 125F upon which the desirable properties of the disclosed compositions depend.
Prior art techniques for preparation of the two component mixes typically rely on a thorough mixing of each component separately. At the time of use, the components are intermixed with water and again subjected to further mixing.
Thus, the development of a dry alumina based, phosphate bondable single package refractory mix composition which exhibits extended shelf life, which does not require an inhibitor is highly desirable. Moreover, a simplified process of preparing such a composition which eliminates necessary prior art process steps for preparing the mix such as drying or precoating aluminous materials with combinations of fatty acid under controlled conditions offers further attraction.
The present invention provides a single package, dry refractory mix, which exhibits extended shelf life under conventional storage conditions and does not require an inhibitor, -t~hich sets upon the addition of water, and which exhibits high abrasion resistance when set, consisting essentially of:
(a) 40 to 70 weight percent of an inert refractory aggregate, - ~`
(b) 15 to 35 weight percent of an aluminous material selected from the group consisting of calcined alumina, calcined bauxite and kaolin calcine, (c) 2 to lO weight percent hydrated alumina, (d) l to lO weight percent calcium aluminate cement, and (e) 3 to 15 weight percent of 115 percent polyphosphoric acid;
prepared by a process comprising the steps of introducing the dry ingredients into a mixer, mixing the dry ingredients, adding the acid ingredient to the mixture of dry ingredients, and subjecting ~ _ 7 _ - ~0~3i~3 .
the dry and acid ingredient mix to a high intensity mixing action for a predetermined period of time, not exceeding four minutes.

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~ 3~3 Case 4179 The preferred mix is prepared by formu-lating a mixture of the dry ingredients in a mixer, m~xing the dry ingredients to a homogenous state, introducing the liquid acid component into the homogenous mixture of dry ingredients, and sub-jecting the entire mass to a high intensity mixing step for a selected period of time to produce a single component refractory mix substantially dry to the touch with a highly dispersed acid phase lQ within the intermixed mass. ~he resulting mix is characterized as a dry single pac~age alumina based, phosphate bondable refractory mix com-position having an extended shel~ life.
The various ~eatures o~ novelty which characterize the invention are pointed out with pPrticular1ty in the claims annexed to and forming a part of this specification. For a better under-standing o~ the invention, its operating advantages and specific ob~ects obtained by its use, reference

2~ should be had to the accompanying descriptive matter 1n which there is described a preferred embodlment Of the inYention~
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DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present inventive composition, as noted above, may be described as a dry alumina based, phosphate bondable refractory mix composi-tion that has particular utility for lnstallation by re~ractory ramming, gunning and troweling techniques. It is generally of the variety of i ~ ~ Case 4179 ~3~0;~

chemically set relractory specialties that are heated subsequent ~o their application. The pre-ferred composition contains graded tabular alumina, calcined alumina, hydra~ed alumina, a calcium aluminate cement and a dispersed phosphoric acid.
The indi~idual ingredients are mixed within certain compositional ranges, described hereinafter, to produce a dry single component mix composition characterized by an extended shelf life which is remarkably longer than current competitive products, and having comparable modulus of rupture, cold crushing strength, abrasion resistance and percent linear dimensional changes.
All size grading or mesh ~ndications here- ;
in are according to the standard Tyler series.
A wide variety of materials is suited for use as inert (not active in causing the primary bonding reaction to occur) refractory aggregate in the practice of this invention. These include tabular alumina, calcined bauxite, kaolin calcine, and synthetic mullite. Use of a particular aggre-gate~or combination of two or more aggregates, as well as particle size grading will depend upon the `
particular application technique and the deslred properties of the monolithic structure to be formed.
Tabular alumina is preferred because of its high re-fractorir.ess and resistanoe to abrasion.
Tabular alumina is a relatively pure form of sintered calcined alumina oontaining trace amounts 3C of SiO2, Fe203 and Na2O. This form of alumina has well-developed alpha a1umina orystals with a Mohs _ 9 _ Case 4179

3 ~ ~ 3 hardness scale reading of 9. For use in accordance with the invention, particles larger than 6 ~esh generally have a negative influence on the workability charac~eristics of the resul~ing mix. Hence, ~he tabular alumina aggregate should be all ground to -6 mesh in order to obtain desirable particle packing.
Tabular alumina is generally commercially available in sizes larger than 100 mesh but such aggregate sized at -100 mesh would be suitable. An appropriate 1~ tabular alumina is produced and marketed by the .~
Aluminum Company of America ("Alcoa~') under the ~;
designation o~ Tabular Alumina T-61. The other sources Or aggregate may be used in place of the ,-~abular alumina with selection of ~he size of the substitute ~gregate based on availability and end use.
The calcined alumina preferred is sized as all minus 100 mesh. This alumina phase is charac-terized by a ~ine crystal size, less than 5 microns and displays comparatlvely little shrinkage. A
suitable commercially available calcined alumina is produced by Alcoa and marketed as Calcined Alumina A-2. Calcined bauxlte or kaolin calcine could be substituted. ~ ,;
A reactive alumina compound such as hydrated alumina is used, in conjunction with the proper i distribution of diphosphorous pentaoxide in an acld, ,~-`
to generate one of the necessary bonding agents~ '~
Hydrated alumina is a white crystalline substance 3 granular in nature generally designated as Al(OH)3.
The refined form generally contains small amounts '~

~ ~a~e h~k - 10 - ~

Case 4179 ~O ~ 3~ O 3 (less than 1%~ o~ S102, ~e203 and Na2O. Hydrated Alumina C-31 produced by Alco~ is.a.suitable commer-cially ;a~ailable materi~l for use he.re~n~ Common-im~ure bauxite which is naturally hydrat.ed.is also sa~is~actory ~or ~he purposes of the present compo-sition It has been found that ~he hydrated alumina ingredien~ size significantly influences the working time and set of the mix. Shorter ~orking times are associated with the finer forms of equi~alent weights of alumina hydrate in that the finer grades expose more surface for the reaction.
Calclum aluminate cements are compositions having monocalcium aluminate (CaO-A1203) as their major con-stituent~ Re~con, a shock sintered, pelletized calcium aluminate cement manufactured by Uni~ersal Atlas Cement Division of United States Steel Corporation has been found to give satisfactory performance in the present inventive composition as one o~ the binding agents for :
the refractory aggregates heretofore described. Refcon*
2a ls supplied as a ground powder. Selection of a refrac- d tory cement binder, as well as selection o~ the aggre-gate~ requires attention .be paid to the temperature re- :
quirements of the final refractory product. Where temp- ;
eratures approaching 3900F are expected, appropriate ~; .
commercial replacement for Refcon may be made.
Polyphosphoric acid (PPA~, as an anhydrous super saturated solution containing P205 distrlbuted as ortho~
phosphoric acid and condensed acids is ~he preferred P205 de~i~ed acid i~gredlen~. PPA has .s~ron~ dehydrating proper.ties and has .found ~arious ~ de ~ k .. . . .. .

Case 4179 3~03 applications for its catalytic and sequestering abilities. A typical composition of polyphosphoric acid produced by the FMC Corporation, Philadelphia, Pa. and used to successfully prepare an in~entive refractory mix described herein is listed in Table~

T A B L E

Concentration, ~ H3P04 115 ~iscosity at 27C, centipoise28aO00 Viscosity at 100C, centipoise510 Com~osition 2 5~ 83 2 P20~ Distribution as orthophosphoric acid, % 5 pyrophosphoric acid, % 16 triphosphoric acid9 % 17 tetraphosphoric acid, % 16 higher polymer acids, % 46 Due to the high viscosity o~ PPA at lower temp- ~

eratures it is preferred, but not required, to ~-utilize the PPA within th~e ~emperatur~e range~ of 160F to 200F to facilitate addltion to the dry `^

ingredients as described hereinafter.
It has been found that the preparation of the mix using the method described hereinafter ;
permits replacement of the PPA with 85% phosphoric acid. This finding is unexpected in view or the fact that an inhibitor is not required as in the prior art. Although a product having extended shelf li~e is formed when thè PPA is replaced with 85%
phosphoric acid, the mechanical properties of the 93~03 products using PPA appear to be superior for particular industrial applications such as in petroleum catalytic crackers, where high abrasion resistance is required.
Although the physiochemical nature of the bond produced is not completely understood, it is believed that phosphoric acid readily reacts with hydrated alumina to form hydrated aluminum phosphate in the presence of water and is responsible, in conjunction with the cementing reation of the calcium aluminate cement, for the mixture setting. In the inventive composition, PPA and phosphoric acid provide the phosphate constituent needed to ultimately form the aluminum phosphate bond, but while the properly conditioned mix is maintained in a dry condition, the dispersion of the acid precludes bond formation.
The inventive mixture has a broad and preferred ;
compositional makeup within the ranges shown in Table II as follows:
T A B L E I I

COMPONENT BROAD RANGE (w/o ) PREFERRED RAN OE (w/o ) Tabular Alumina 40-70 50-60 20 Calcined Alumina 15-35 22-32 Hydrated Alumina 2-10 2-6 Calcium Aluminate Cement 1-10 1-5 ~`

Acid Ingredient 3-19 (85% 5-9 (85 H3PO4) H3PO4) * w/o - Weight Percent - 13 ~

, . . .

~ Case 4179 3~L03 Hydrated alumina present in amounts ex¢eed-ing ten weight percent promotes bloating of the refractory when wet, making it undesirable ~or use as a ramming mlx. Difficulty in setting occurs when the mix contains less than two percent hy-drated alumina.
The presence o~ calcium aluminate cement between zero and one percent also retards setting of the mix upon application. However, with amounts of calcium aluminate cement greater than ten percent, the mixture will tend to ~lash se~ 3 makin~ it extreme-ly di~ficult to apply to a sur~ace and work into place.
` It has further been found that the PPA, the preferred acid ingredient, must be present within the range o~ 3-15% for the mix to develop the nec- `
essary setting properties when water is added.
Howe~er, PPA in amounts in excess of 15%, espec-ially in the presence of a high cal¢ium aluminate ~0 cement content, will cause flash setting of the mixture adversely affecting the workability of the mlx. In this regard, the upper limlt of 15% PPA
is critical in producing a phosphate bonded ram-ming mix with commercially acceptable charac- `
teristics. When 85% phosphoric acld is utilized, the upper limit becomes 19%. Shrinkage of products made from amounts greater than 19% would be un-acceptably high.
The balance of the materials used to form 30~ the mix, ~iz., tabular alumina and calcined alumina, in the preferred embodiment, are ad~usted as is ~ :
known in the art to provide suitable workability . . .
- 14 - ~

Case 4179 : 1C~93~[)3 and the like.
At the point of use, a.suff.icie.nt amount ~f water is added to the mix to obt.ain the: consi.stency required ~or the application technique~. e~g~ ramming, gunning or slap t~oweling, to be..utili.zed for the parti.cular ~ix, The binde~ sy.s~em of the preferred embodiment is considered to comp~i.se the phosphate -~
components~ the hydrated alum,ina and a calcium aluminate cement~ The complex series' Of reactions and physiochemical nature o~ the resulting bond is not completely understood. However, the reactions -:
are highly exothermic and the .~inal bond is charac-terized as an aluminate ph,osphake bond. No sub- `
sequent heating or curing of the bona is required, :
hence the bonding is essentially cold setting. It .
has been ~ound that the desirable characteristics achieved by the mix are not present in the absence : ~.
o~ calcium aluminate cement which is apparently essential to the highly exothermic nature of the bonding reac'tions. Hence, the presence of calcium aluminate cement is deemed critical. The use o~
calclum aluminate cement in conjunction with the other components o~ the binder sys.tem, moreover, ,;
results in a mix yielding a monolithic refractory construction which has advantages over conventional ;~
calcium aluminate cement constru~tion in that superior pr~perties are obt.ained in the 1000F ~o 2Q0.0F temperature range.
..... . . .
' - 15 - . , Case 4179 ~093~ 3 The method of producing the mix comprises ~ormula~ing the dry (non-acid) ingredients in a blending pot followed by m~xing thereof to a homo-genous state. It is not critical to achieve homo-ge~ity of the dry components prior to adding the acid. PPA is then added in an amount such that the co~position makeup falls within the above dis-closed ranges for each o~ the ingredients. The mixture is then su~ected to a high intensity mix-ing step for a selected period of time which will vary based on the batch size to be made. It is critical to production of the improved product mix that the mixing operation be characterized as high intensity as described hereafter. While the exact `~
reason for this is not understood, it is believed that high intensity mixing action shatters and dis-perses the acid droplets allowing the acid to be ~``
coated by alumina fines. This coating and separa~
tion of the acid par~icles, it is believed, prevents their reaction, inhibiting the aluminum phosphate - , , and cement hydration reactions which cause the mixture to set The resulting mix, moreover, i5 substàntially dry to the touch although the acid ingredient was added as a liquid.
No suitable techn~que for determining degree of dispersion of the acid in the mixture is avail- ~ ;
able, however, a suitable degree of dispersion can be predicted by reference to a "specific mixing energy~' or specific energy input into a batch pre-paration expressed in kilowatts per hundred kilo-grams of batch.

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~ Case 4179 1~ 3103 In preparation of the inventive composition a specific mixing energy with the range of approxi-mately .4 to approximately 1.4 kilowatts per hundred kilograms has been found necessary to produce a satis~ctory product with an extended shelf life. How-ever~ a time variable has been found to be critical as regards a successful mix~ this variable appearing in the form of mechanical work on the mix. The work on the mix is defined as the product of the power(amps --- operating current less free load current --- multi-plied by rated voltage of the mixer motor~ and the mixing time. Once the appropriate speci~lc mixing energy ~alues are obtained, total mixing time of from 1 to 4 minutes ~ill insure a satis~actory product with a 2.5 minute mixing time for the acid blended mixture being an optimum time value.
The term 'Ihigh intensity mixing", in the speci-fication and claims, is intended to denote mixing with à speci~ic mixing energy of .4 to 1.4 kilowatts per ?& hundred kilograms of batch ingredients.
The preferred method of preparation of the com-position is to formulate the dry ingredients in a mixing pot and mix these to a homogenou~ state. The acid is then added to the blended dry ingredient mixture. The entire mass is then mixed for a predetermined period of time, not exceeding four minutes.
The sequence in Example 1 o~ startin~ the mixer at a slower speed and subsequently increasing the speed is not critical to the process and is merely 3~ a characteristic of the control arrangement on the particular equipment utll`ized. Rotation o~ the mixer ~ 17 ~

Case 4179 ` ~93~3 pan, as des.cribed in Examp.le 1 is like.~ise not criti.cal ~o the .~.~oce.ss but is a characterist:ic of the parti.cular mixer. .It is not necessary, moreover, to st-op the ~.ixer prior tQ adding the ~cid i~gredients.
Alternati~ely, the dry and acid ingredients may be concurrently charged into the mixer..
The i~entiQn will be .better unde~.sto.od upon reference to ~xamples 1 and 2 which follow.
(See EXAMPLE 1 on Follow~ng Page) lQ (See EXAMPLE 2 on Page 21) ~ Case 4179 ~31~3 _ _ Two h~ndred-twenty-eight (228) pounds of -6 M/F
~minus 6 mesh to finer) T-61 tabular alumina was added to the pan of an Eirich Model DE 14 counter-current intensi~e mixer which was equipped with a suctlon type rotor. Four hundred-sixty-eight (468~ pounds of -14 M/~
T-61 alumina, along with thirty-six (36) pounds of Refcon cement were also added to the pan~ ~ifty (50) pounds of -200 mesh raw Dutch Gulana bauxite, a hydrate, and one hundred se~enty-seven (177) pounds of -325 M
Alcoa A-2 Alumina along with one hunared fifty-six (156) pounds of -325 M coarse removed A-2 alumina were also added to the mixer pan. The mixer was then started and operated at a rotor speed of 8 ~ rpm and quickly in-creased to a rotor speed o~ 1760 rpm. Rotor rotation was counter-clockwise and the mixer pan rotation clock-wlse. The mixer pan was rotated ~or 50 seconds before the mixer was stopped. Eighty-four (84) pounds of 115%
polyphosphorlc acid (PPA) was t~en added. The mixer was then energized with a rotor speed of 880 rpm and quickly increased to 1760-rpm with the rotor rotating ~ ;
in a counter-clockwise direction and the pan rotating in a clockwise direction for 90 seconds. The mixer was then stopped and the materlal ~rom the pan bagged in polyethylene lined paper bags. The bags were sealed and stored. ~ighteen (18) months later, the sampleæ
were unbagged. The ma~erial flowed ~reely out o~ the bags and no lumps were obser~ed.~
m e material was placed with 6% water and ~-3 formed into test samples measuring 2" x 2" x 9".

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fr~de ~ rk - 9 :, Case 4179 ~0~31~3 The material had a working time of approximately 20 minutes., Each sample was nermit.te.d to ~ir .s.et .o.ver-nigh.t~ dried at 220F ~or 24 hours~ and fir.ed.to.the .temperature i~dic.ated (Ta~le III~ for a fiYe hour period.
Upon being cooled to amb.~ent, the samp.les exhi~it.ed the properties listed in Table III~

(SEE TAB~E III ON PAGE 22~ :.

- 20.- .

Case 4179 ~9 ~ ~ ~ 3 -A ~ix was ~ormulated having the following composition;
-6M~F ~abular alumina ~ 3.5 lbs.
-14~f~ ~abular alumi~a, ~ . , 191.5 lbs, -325 M~ calci~ed alumina. . ~ 136.5 lbs.
Hydrated alumina ~ . . 20.5 lbs.
~alcium Aluminate ~ement . . , . . . . 14.5 lbs.
Phosph~ric Acid (8~ 43.5 lbs.

The pr~cedure utllized ~n~ol~ed adding the dry ingredients to the mixer pan of an Eirich ~odel DE-12 ~.
counter-current mixer~ mixing the batch ~or about 35 seconds at 1008 rpm, adding the acld to the~batch without stopping the mixer and mlxing for an additional 150 seconds, Samples were ~ormed and tèsted using the methods described under Example 1. The results are reported in Table III. The mix was then bagged ln polyethylene paper bags, sealed and stored for 71 days. The mix was subsequentIy examined and found to 20` be loose with lumps which bro~e up upon mixing. The mix was cast with 7 1/2% water and had a working tlme of approximately 15 minutes, Table III lists the~
measured properties of: the sample~

(SEF TABLE III ON FOLLOWING PAGE) :

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.,. , , ''' ' Case 4179 93~1~3 T A B L E III

Exam~le 1 Example 2 Bulk Densi~y, p.c.f., A~ter ---Air drying for 24 hours at 220F 165 160 Fired at 1500F 164 157 ;:
Fired at 2800F 171 Fired at 3000F

Modulus of Rupture, p.s.i. After -~
Air Drying for 24 hours at 220~ 2110 2170 1~ Fired at 1500F 1700 1610 Fired at 2800F 2640 ---Fired at 3000F ~-~ 4300 Cold Crushing Strength, p.s.i. After ~
Air Drying for~24 Hours at 220F 4520 : --- :--Fired at 1~00F 3440 :- -Fired at 2800F ~ 3550 ---Fired at 3000F

Abraslon Loss*, c.c., After --~
Air Drying ~or 24 Hours at 220~ .36 ---2~ Fired at 1500F ~45 ~~~
Fired at 2800F ~ .24 Flred at 3000F ~~~~

` Linear Change after Firing, percent At 1500F 0.0 -0.2 At 2800F -0~9 ~~
At 3000F ~ ~-- ~3 5 *Abrasion Loss Measured Per Sillca Sand method.

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~ Case 4179 ` ` ~0~3~3 The aver~ge specific mixing energy in Examples 1 and 2 were 1.05 and .6 kilowatts per hlmdred kllograms respecti~ely.
As noted 2bove, high intensity mixing is critical to the production o~ an ~mproved product mixture. Example 3 illustrates the contrasting results attained when a mix was prepared utilizing a low speed non-intensive mixing techn~que:

The following components in the corresponding amounts were added to a standard pan mull~r mixer:
Components Amount (lbs) -6M~F, tabular alumina 191 -14M/F, tabular alumina 390 -325M, calcined alumina 278 Hydrated alumina ~ 42 Calcium Aluminate Cement 30 The above components were dry ~ixed in the muller mixer for 3 minutes while the mixer operated an ~ppr~ximately 30 rpm. Sixty-nlne (69) pounds of 115~ PPA was added on a continuous basis while~the mix was dry mixing. When all the acid had been added, the components were mixed for at least ~ive (5~ minutes or until the mix was well blended. The mlxer was then stopped, unlocked and the;material bagged in polyethylene lined paper bags for storage. The mix was not substantially dry to the touch but had a damp feel. With~n one (1) week the composition had set and hardened.
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Case 4179 3 ~ 3 In the following Examples 4-6 ,. three additi.onal composi~tlons using ingredie.nts,.as .shown.~ re detailed.
Each mix was ~rmed by chargin~ the dry ingred~ents into ~n Eirich:,Model DE-12 counter-curXent mixer, mixin~ th~ batch ~r about 35 .seconds .at 1008 rpm, adding the acid to..the ~.at.ch w~thout .stoppi~g the m~xer and mixing for an additio~al 150 s.ec~nds. Samples were formed as in Exampl~ 1 b,y. casting the' mixes' of Examples 4? 5 and 6 w~th'6~6~ 6,4~ and 8~ ~.ater, and were tes'ted~ The results 2re repo~ted in Tabl.es .IV .-and V.

E X A M P L E 4 `:

Components Weight Percent -5 M/F Calcined Bauxite 19.0 .
-14 M/F Calcined Bauxite 39.0 -325 M/F Calcined Alumina ~ 27.8 ~' .
Xydrated Alumina ~Alcoa C-331)4.2 CPlcium Aluminate Cement 3.0 `:
115% Polyphosphoric Acid 7.0 ' 2~ E X A M P L E 5 Companents Weight Percent -6 M~F Calcined Bauxite ~19.0 :' -14 M/F Calcined Bauxite 39.0 -325 M~F Calcined Alumina 27.8 ~ydrated Alumina (Alcoa C-31~ 4.2 Calcium Alumin~te Cement 3~0 ~;
115~ Polyphosphoric Acid 7,0 tr~d~ ~ra~k ;. . .. -. ;. . , - , . ... . ........ .... . . . .

Ca~e 417 1~3~103 E X A M P L ~3 6 Components lleight Yercenti -8 M/F Kaolin ~alcine 33. 5 -6 M/F Kaol~ n Calcine 13 . 7 -325 M/F Calcined Alumina 35~
Hydrated Alumina 5~ 4 Calcium Aluminate Cemen'c 3 . ~
115~ Polyphosphoric Acid 7.7 (SEE ~ABLE IV ON PAGE 2 6 ) ~SEE TABLE V ON PAGE 2 7 ) - 25 ~

ca~e 4l7g T A B L E IV

~ample 4 Exa~ple 5 Bulk Density~ p.c.f. 7 After ---Air drying ~or Z4 hour~ ~t 220~ 167 165 Fired at 1500F 164 160 Fired at 2800F 178 ---Fired at 2~00F 182 173 Moduluæ o~ Rupture, p.s.i. After ---~ir Drying ~or 24 hours at 220F 2000 1520 1~ Fired at 1500F 1430 1210 Fired at 2800F 5100 --~
Fired at 2900~F 5260 3710 Cold Crushing Strength, p.s.i. After ---Air Drying for 24 Hours at 220F 5300 2730 Fired at 1500F 4590 2630 Fired at 2800F 9590 ---Fired at 2900~ 9700 7760 Abrasion Loss*, c.c.,After ---~lr Drylng ~or 24 Hours ak 220F 6.~ - g.4 ---2~3 Fired at 1500F 6.7 - 7.1 9.0 LinPar Change a~ter ~iring, percent At 1500F -0.2 ~0.1 At 2800F -2.8 ---ht 2900F -2.6 -2.5 *Abrasion Loss M~a~ure~ Per ~STM Standard ~ 704, Standard Method o~ Te~t ~or Abraslon Resl~tance Or ~e~ractory Materials at ~oom Ternperature.

Ca~e 4179 ~ O~ 3~.~ 3 T A B L ~ V

x~mple 6 Bulk Density~ p.c.f., After --Air drying for 24 hours at 220~F 145 Fired at 1500F 141 Fired at 2800F 11l7 Fired at 3000~F 143 Modulus of ~upture 9 p.s.l. After --Air drying for 24 hours a~ 220F 1580 ~ired at 1500F 1130 Fired at 2800F 3000 Fired at 3000F 4030 Cold Crushing Strength, p.s.i. A~ter ---Air drying ~or 24 Hours at 220F 3330 Fired at 1500F 3040 Fired at 2800F 7210 Fired at 3000F ---Abra~ion Loss*, c.c. 9 Af~er ---Air drying for Z4 hours at 220~F1~.5 Fired at 1500F 13.8 2G Linear Change after Fi~ing, percent At 1500F
At 2800F -1.9 At 3000F -0.4 ~Abrasion Los~ Measure~ Per AS~M Standard C 704, Standard Method of Te~t for Abrasion Re~l~tance o~ Re~ractory Ma~erials at Room Temperature.

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE CLAIM
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOW:

1. A single package, dry refractory mix, which exhibits extended shelf life under conventional storage conditions and does not require and inhibitor, which sets upon the addition of water, and which exhibits high abrasion resistance when set, consist-ing essentially of:
(a) 40 to 70 weight percent of an inert refractory aggregate, (b) 15 to 35 weight percent of an aluminous material selected from the group consisting of calcined alumina, calcined bauxite and kaolin calcine, (c) 2 to 10 weight percent hydrated alumina, (d) 1 to 10 weight percent calcium aluminate cement, and (e) 3 to 15 weight percent of 115 percent polyphos-prepared by a process comprising the steps of introducing the dry ingredients into a mixer, mixing the dry ingredients, add-ing the acid ingredient to the mixture of dry ingredients, and subjecting the dry and acid ingredient mix to a high intensity mixing action for a predetermined period of time, not exceeding four minutes.

2. A single package, dry refractory mix, which exhibits extended shelf life under conventional storage conditions and does not require an inhibitor, which sets upon the addition of water, and which exhibits high abrasion resistance when set, consisting essentially of (a) 40 to 70 weight percent of an inert refractory aggregate selected from the group consisting of tabular alumina, calcined bauxite, kaolin calcine and synthetic mullite, (b) 15 to 35 weight percent of an aluminous material selected from the group consisting of calcinod alumina, calcined bauxite and kaolin calcine, (c) 2 to 10 weight percent hydrated alumina, (d) 1 to 10 weight percent calcium aluminate cement, and (e) 3 to 15 weight percent of 115 percent polyphos-phoric acid;

Page Two prepared by a process comprising the steps of introducing the dry ingredients into a mixer, mixing the dry ingredients, add-ing the acid ingredient to the mixture of dry ingredients, and subjecting the dry and acid ingredient mix to a high intensity mixing action for a predetermined period of time, not exceeding four minutes.

3. A single package, dry refractory mix, which exhibits extended shelf life under conventional storage conditions and does not require an inhibitor, which sets upon the addition of water, and which exhibits high abrasion resistance when set, consisting essentially of:
(a) 50 to 60 weight percent of an inert refractory aggregate, (b) 22 to 32 weight percent of an aluminous material selected from the group consisting of calcined alumina, calcined bauxite and kaolin calcine, (c) 2 to 6 weight percent of hydrated alumina, (d) 1 to 5 weight percent of calcium aluminate cement, and (e) 3 to 15 weight percent of 115 percent polyphos-prepared by a process comprising the steps of introducing the dry ingredients into a mixer, mixing the dry ingredients, add-ing the acid ingredient to the mixture of dry ingredients, and subjecting the dry and acid ingredientsmix to a high intensity mixing action for a predetermined period of time, not exceeding four minutes.

4. A single package, dry refractory mix, which exhibits extended shelf life under conventional storage conditions and does not require an inhibitor, which sets upon the addition of water and which exhibits high abrasion resistance when set, con-sisting essentially of:
(a) 50 to 60 weight percent of an lnert refractory aggregate selected from the group consisting of tabular alumina, calcined bauxite, kaolin cal-cine and synthetic mullite.
(b) 22 to 32 weight percent of an aluminous material selected from the group consisting of calcined alumina, calcined bauxite and kaolin calcine, (c) 2 to 6 weight percent of hydrated alumina, (d) 1 to 5 weight percent of calcium aluminate cement, and (e) 3 to 15 weight percent of 115 percent polyphos-phoric acid;
prepared by a process comprising the steps of introducing the dry ingredients into a mixer, mixing the dry ingredients, adding the acid ingredient to the mixture of dry ingredients, and subjecting the dry and acid ingredient mix to a high intensity mixing action for a predetermined period of time, not exceeding four minutes.

5. The product of claim 1, 2, or 3 wherein the predetermined period of time is between one minute and four minutes.

6. The product of claim 4 wherein the predetermined period of time is between one minute and four minutes.

7. The product of claim 1, 2, or 3 wherein the predetermined period of time is 2.5 minutes.