FR2589854A1 - COMPOSITIONS FOR MONOLITHIC REFRACTORIES CONTAINING BASIC REFRACTORY AGGREGATE AND LOW SOLUBLE PHOSPHATE - Google Patents

Abstract

THE INVENTION RELATES TO REFRACTORY MATERIALS. IT CONCERNS AN UNFACTORED REFRACTORY COMPOSITION, WHICH INCLUDES ONE OR MORE BASIC REFRACTORY AGGREGATES, CHARACTERIZED IN THAT IT INCLUDES, IN ADDITION, AN INSOLUBLE OR LOW-WATER-SOLUBLE PHOSPHATE AS AN EXTINGUISHING INHIBITOR IN ONE QUANTITY. 0.02 TO 20PARTMENTS BY WEIGHT PER 100PARTS BY WEIGHT OF THE TOTAL OF SAID BASIC REFRACTORY AGGREGATES. USE FOR THE PRODUCTION OF MONOLITHIC REFRACTORY PARTS OR PARTS.

Description

The present invention relates to compositions for refractories

  monolithic to be used not only in various types of furnaces for the manufacture of steel, but also in various furnaces and furnaces for non-ferrous metals, in the ceramic products industry, etc.

  Usually, the compositions for refraction

  Monolithic materials are applied by formulating and mixing powdered materials, water, water, aqueous binder, and so on. However, there are many cases where, in monolithic xefractary compositions containing basic components,

  MgO or CaO, occurs by mixing with the water the phenomenon

  nomène known as "extinction" which causes cracks

  or breakage during curing or drying.

  In order to inhibit these defects, the Japanese patent applications published under No. 52-32908, 53-113812,

  Nos. 57-129864 and 58-99177 disclose methods

  in which additives are introduced.

  However, it can hardly be said that the additives

  The above-mentioned patent publications have demonstrated a capability that satisfies both the extinction inhibition and the applicability criteria as a refractory composition.

monolithic.

  Indeed, the two Japanese patent applications published under N 5232908 and 53-113812 describe

  extinguishing inhibitors comprising orally

  the first being an additive

  binding effect in the manufacture of refractory bricks, but although the effect of this additive may be recognized when a refractory material is pressurized after it has been mixed in the form of an aqueous solution with aggregates, it is difficult to use this additive with casting materials, etc., because of the high concentration of

its aqueous solution.

  On the other hand, the last one is mainly

  effective for projecting materials etc., but not

  highly effective for casting, coating, spraying, etc., and the use of a large quantity of this additive may cause undesirable degradation

  the mechanical strength of the body to be formed.

  In addition,

  are described in Japanese Patent Application Nos. 57-129864 and 58-99177, that described in the first reference being very effective in solution.

  water and for drying in a low temperature range.

  temperatures but insufficiently effective for drying under the conditions prevailing in an autoclave above 100C. The one described in the last reference comprises silica flour which can generally be used for casting and coating materials, a small amount having only a reduced effect, and the use of large quantities disadvantageously degrading the corrosion resistance of basic refractory aggregates. The present invention was developed account

  the state of the art described above.

  An object of the present invention is to provide monolithic refractory compositions having

  a superior ability to apply.

  Another object of the present invention is to provide compositions for monolithic refractories or which do not produce cracking / fracture phenomena resulting from hydration, i.e. extinguishing, taking place in a refractory body. formed in the presence of water or steam / during application,

hardening or drying.

  The present invention relates to a monolithic refractory composition comprising one or more basic refractory aggregates and an insoluble or poorly water soluble phosphate as an extinguishing inhibitor in an amount of 0.02 to 20 parts by weight per 100 parts. by weight of the total of the aggregates

  basic refractories and said phosphate.

  So far, phosphoric acid, phos-

  water soluble aluminum pte and others, have been used

  as binders in refractory compositions do not contain

  However, these binders have not been used in unshaped refractory compositions containing such basic refractory aggregates. However, paying attention to the reactivity of phosphoric acid and others with basic refractory aggregates, the Applicant has sought various methods for inhibiting the extinction phenomenon,

  in which the basic refractory aggregate is stable

  by generating a modulated reaction of phosphoric acid

  or other only with the surface of the basic refractory aggregate or only with the basic ions

  dissolved in the water that is present, and avoiding

  a reaction with the entire refractory aggregate

  itself during the aforesaid reaction of phosphoric acid or the like, which resulted from the present invention. Indeed, the present invention relates to monolithic refractory compositions comprising basic refractory aggregates selected from one or more types of magnesia clinkers, spinel clinkers, magnesia-chromium clinkers, dolomite clinkers and lime clinkers, and insoluble phosphates. or slightly soluble in water as an extinction inhibitor, in an amount of 0.02 to 20 parts by weight of phosphate per 100 parts by weight of

  total of said refractory aggregates.

  With regard to the clinkers used in the present invention, ie magnesia clinker, spinel clinker, magnesia-chromium clinker, dolomite clinker and lime clinker, various qualities can suitably be used. clinkers available on the market, for example seawater magnesia clinker, natural magnesia clinker, fused magnesia clinker, sintered spinel clinker, fused spinel clinker, natural dolomite clinker, sintered lime clinker, fused lime clinker, etc. To have a free choice of the size of

  particles of material composing the refractory compositions

  preferred clinkers which are in the form of crushable pieces or which are sorted into

various particle sizes.

  These clinkers are used alone or two or more of them are mixed. There are, moreover, cases in which these clinkers are mixed with various refractory materials which are stable with respect to water and water vapor, such as for example alumina, bauxite, mullite, fireclay,

  silica, chromite, olivine, etc., and their

  respective portions of mixture in each case are not

  not particularly limited but must be

  determined according to the working conditions

  various furnaces currently used.

  It is preferred that the insoluble or poorly water-soluble phosphates used in the present invention have a solubility of less than 2.5 g / 100 ml in water at a lower temperature.

  at 40 C, and it is further preferable that the pH in addition to

  If the phosphate has a high solubility in water at low temperature, the reaction with the basic refractory aggregate progresses.

  quickly during mixing or placement and

  treats coagulation or other defects, which makes setting up difficult. If the pH of the phosphate in suspension is greater than 7, the inhibition effect of

extinction will be very limited.

  Although the insoluble or poorly water-soluble phoshates used in the present invention are not specifically limited, materials having orthophosphoric or polyphosphoric groups and salts thereof formed with aluminum, can be advantageously employed. chromium, iron, magnesium, calcium, potassium, sodium, lithium, boron, zinc, lead, barium, bismuth, silver, etc. For example, among aluminum phosphates, Al (H2PO4) 3 is water soluble and therefore not usable, but AlH3 (PO4) 2, Al2 (HPO4) 3 and AlPO4 are insoluble in water and can therefore be used in the present invention. In the class of AlPO4 and others, there are compounds of various types

  crystalline, including amorphous, and it is possible to use

  any of them. In addition, polyphosphates such as aluminum metaphosphate, aluminum tripolyphosphate, etc., are poorly soluble and are therefore also useful. The same reasoning can be applied to phosphates other than aluminum, and it is also possible to use composite phosphates combining two or more phosphates as well as phosphate forming a solution.

solid.

  The amount of insoluble or poorly soluble phesphate in the water that needs to be added varies according to

  the type of clinkers and their proportions of formulation.

  Indeed, for relatively stable clinkers vis-à-

  water screws that magnesia-chromium clinker and a spinel clinker rich in alumina or others, an even extremely small amount of phosphate exerts a certain effect, and in a magnesia-rich spinel clinker or magnesia clinker, the quantity of the phosphate must be more or less increased. In addition, for

  a dolomite clinker and a clinker of lime which

  hold a lot of CaO and are active in the water, we must add a greater amount of phosphate. The amount of phosphate obviously also varies according to the state

  crystalline and crystal size of MgO and CaO pre-

  in each clinker. When using a mixture of clinkers, the amount of phosphate should be determined according to each of the respective aggregates. However, in all cases, the phosphates must be added to the clinkers within the range of 0.02 to 20 parts

  in weight of phosphate per 100 parts by weight of

  total ker. If there is less than 0.02 parts by weight of phosphate, cracking can occur in an autoclave during drying, and addition of more than 20 parts by weight does not provide better effects and is not

economic.

  The raw materials used in conventional unformed refractory compositions can

  obviously be used in refractile compositions

  Unwaxed formers of the present invention and may be, as required, inorganic binders such as cements, sodium silicate, water-soluble sodium phosphate, etc., and organic binders such as various resins and the like. dispersants such as various water-soluble sodium phosphates and carboxylates and the like, and various setting control agents such as various sulfates, carbonates, hydroxides, chlorides, borides, carboxylic acids, etc. However, in the unformed refractory compositions of the present invention, the binder is not always necessary,

  especially in casting applications. We can

  it is so because the pH increases as the Mg2 + and Ca2 + ions are eluted from the clinker, so that very little phosphoric acid is eluted and some compounds are produced with Mg2 + and Ca2 +,

  which reinforces the structure of the body in formation.

  The refractory aggregates of the refractory composition of the present invention may have particle size distributions suitable for particular applications such as casting, spray application, patch repair, coating, grooming, and the like. It is also possible to add, if necessary, clay, fine powdered silica, fine powdered alumina, etc., in order to improve characteristics such as flowability,

consistency, and others.

  Although the monolithic refractory compositions of the present invention contain insoluble or poorly water-soluble phosphates, so that the compositions are stable to the

  water and thus hardly react during their application

  cation after being mixed with water, one can

  recognize that as time passes after the addi-

  With the addition of water, the pH rises as the Mg2 + and Ca2 + ions are eluted, resulting in the elution of a very small amount of phosphoric acid forming compounds with Mg2 + and Ca2 +, so that 'it does not happen

  cracking or breaking due to extinguishment.

  The following nonlimiting examples illustrate

the present invention.

Example 1

  Compositions have been prepared in the proportions

  formulations of the formulations shown in Table 1, and 6.5 parts by weight of water per 100 parts by weight of the compositions were added thereto, then, after mixing, these compositions were cast into 40 × 40 × 160 molds. mm and cured at room temperature for 24 hours to obtain test pieces. After drying each test piece at 110 ° C. for 24 hours, the rupture modulus and the porosity were measured. Other test pieces were subjected to an autoclave test immediately after curing for 3 hours at 5 bar. The modulus of rupture and the porosity of the specimens which were

  not broken in the autoclave test.

  The test results of the test specimens

  are shown in Table 1.

  As is clear from Table 1, the specimens formulated in accordance with the present invention

  have absolutely no cracking or breaking

  under the severe conditions of a pressure of 5 bar for 3 hours. In addition, for test pieces

  according to the formulas of the present invention, the

  flexural strength after the autoclave test is mounted above that found after drying and the

  porosity decreased in the same way. On the other hand,

  vales of the Comparative Example broke or exhibited reduced strength. In addition, the compositions containing water-soluble acid phosphates such as Al (H 2 PO 4) 3 could not be applied because of the reactions

  taking place during the mixing operation.

  Table 1 Examples of the Present Inventory Comparative Example 1) 4 S yt 9 I 1 12 to 14 15 16 Clinker, 40n 40 40 4040 40 40 40 mg. 0 to 20 0 20 20 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 to 40 40 40 40 40 40 40 to 40 [Inet pea /], (,,,,,,,,,,,,,,,,,,,,,,,, d = 0, o, o - o..O ... o o, on% ioi - -Ai o, o Ibb of ragreb (llPe) 11,5 9,2sn1,81,01,88,61, 71, 81,81,85,6 _w O OP () | O, 1 # 20Il ll 25s4s 02 lee | 1, | 1F o

I .... (dSL _: ... *.

e * '"', (s.Yl ,, aLS,

_J4.U, ob x, 5 - - -

  ## STR1 ## 5,16 5,59 5,96 6,86 6,96 6,37 8,4,4,7,65 8,73 8,34. 8.14 4.41 7.55 9.02 5.100 Ft * ('[13 il O1th 15, 1i, 0'3]; 14 284P3831183,213> 383gS8 1 3 382.0 - t3,3 net ca * .QMiWWto % NWDJI & elephants, roueapii- ja Nkle dempbwm (NP &) 11,51 9,32 j9,71 10, 98 10,80 11,28 88,26 11,77 11,10 10,98 10,58 1 6 t Uept Mitt 88.1 209 182.0 18.4 I8, U #> a 2, l 1, # 4 Ir? 1 0k2 18.0 laJ 83> 5

- - ', -1, - - - Io

o K) tn o. O Ln vil

Example 2

  Compositions have been prepared according to the

  formulation portions shown in Table 2, and

  water has been added according to the methods of application

  cation and then, after mixing the

  positions, blocks 230 x 230 x 300 mm were cast.

  The blocks were then cured for 24 hours at room temperature, first dried at 110 ° C. for 3 hours, and then at 200 ° C. for 24 hours, after which

  the external appearance of the blocks was observed after drying.

  Since the internal vapor pressure of the molded bodies is not uniform due to differences in porosity, such a large block drying test is a realistic way to appreciate the extent of defects that may occur during drying in a container. oven in practical use. As shown in Table 2, all the blocks of Comparative Example had cracking or breakage, but the compositions of this

  invention have demonstrated good applicability to

  cation and showed no change in appearance.

Table 2

  Examples of the Present Invention Examples Coperetiff

  _____ _____ i312 and 24 Il 26 r1 iI i9a il *.

  (4), 40, 40 40, 40 40, 40 40 40 0 40

_ I _I I _

  0, 0, 0, 40, 0, 3, 10, 10, and 10, such as

Cl, * I IIer of, 2.

  The result is that it has been converted to a sintered alumina solution (<0. 40%). II, II, II, II, II, II, II, II, II, 2, Silicate, Dec., 20, 20, 20, II, II, II, II, II, II, II, II, II, II, II trns {_r # e) 00 * y, R Sotutkon dek Ftanil oXl} oRes * e sopol iD I ^ tc. ## EQU1 ##

tt - ar, j -

  dsel ai CoRen he coUlee 6p boluM paMIuI bo. 1-jnd WIL mllll, lrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrn inxu cioDese eoue ae

4O5 6.0

boneia r v o u

I I I

  inhrw Ms b b 1 oeai tl- ciat- nothing. .r. low cquRetl ro t "Co \ 0 Ln I

-.- - 1-

J

Claims (9)

  Monolithic refractory composition, which comprises one or more basic refractory aggregates, characterized in that it further comprises an insoluble or slightly water-soluble phosphate as an extinction inhibitor in an amount of 0, 02 to 20 parts by weight per 100 parts by weight of   total of said basic refractory aggregates.   2. Composition for monolithic refractory according to claim 1, characterized in that said basic aggregate is constituted by one or more of the following: magnesia clinker, spinel clinker, magnesia-chromium clinker, dolomite clinker and clinker of lime.   3. Composition for monolithic refractory according to claim 2, characterized in that said clinker of magnesia is selected from a clinker of magnesia of sea water, a clinker of natural magnesia   and a fused magnesia clinker.   4. Monolithic refractory composition according to claim 2, characterized in that the dolomite clinker is chosen from a dolomite clinker.   natural and synthetic dolomite clinker.   5. Composition for monolithic refractory according to claim 2, characterized in that said lime clinker is selected from a clinker of lime   sintered and fused lime clinker.   6. Composition for monolithic refractory according to claim 1, characterized in that it further comprises one or more of the following materials: sintered alumina, bauxite, mullite, chamotte,   silica, chromium ores and olivine.   7. Composition for monolithic refractory according to claim 1, characterized in that said phosphate is chosen from phosphates comprising an orthophosphate group or a polyphosphate group, at least one of the cations of said phosphate being chosen from those of the following elements: aluminum, chromium, iron, magnesium, calcium, potassium, sodium, lithium, boron,   zinc, lead, barium, bismuth and silver.   8. Composition for monolithic refractory according to claim 7, characterized in that said phosphates have a solubility in water less than 2.5 g / 100 ml.   9. Composition for monolithic refractory according to claim 7, characterized in that said phosphates have a pH of less than 7 in aqueous suspension.