CA1199648A - Carbonaceous refractory composition for pressing brick shapes - Google Patents
Carbonaceous refractory composition for pressing brick shapesInfo
- Publication number
- CA1199648A CA1199648A CA000424299A CA424299A CA1199648A CA 1199648 A CA1199648 A CA 1199648A CA 000424299 A CA000424299 A CA 000424299A CA 424299 A CA424299 A CA 424299A CA 1199648 A CA1199648 A CA 1199648A
- Authority
- CA
- Canada
- Prior art keywords
- aggregate
- composition according
- periclase
- coarser
- brick
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Compositions Of Oxide Ceramics (AREA)
- Ceramic Products (AREA)
Abstract
ABSTRACT
A more pressable composition for making graphitic refractory brick from oxide aggregate with a carbon bond is obtained when the refractory oxide aggregate is substantially all coarser than 0.15 mm (+100 mesh), preferably coarser than 0.2 mm (+65 mesh), and most prefer-ably coarser than 0.4 mm (+35 mesh), and the matrix is entirely carbonaceous material, such as graphite, par-ticularly flake graphite resin, particularly a phenol formaldehyde resin, together with such other carbonaceous materials as carbon black, calcined coke, anthracite, and the like.
A more pressable composition for making graphitic refractory brick from oxide aggregate with a carbon bond is obtained when the refractory oxide aggregate is substantially all coarser than 0.15 mm (+100 mesh), preferably coarser than 0.2 mm (+65 mesh), and most prefer-ably coarser than 0.4 mm (+35 mesh), and the matrix is entirely carbonaceous material, such as graphite, par-ticularly flake graphite resin, particularly a phenol formaldehyde resin, together with such other carbonaceous materials as carbon black, calcined coke, anthracite, and the like.
Description
~ Case 649~
CARBONACEOUS ~EFRACTORY COMPOSITION FOR PRESSING
BRI~K SHAPES
Back~round of the Invention Fhis invention pertains to carbonaceous refractory compositions, particularly such compositions suited for press-ing into brick shape.
It is known to form a refractory brick by pressing a composition of refractory aggregate (for example, refractory periclase grain) combined with a pitch bond which may also contain other carbonaceous materials, such 2S carbon black, graphite, and the like. In order to for~ a pressed brick which has adequate ~tren8th to be handled and shipped without 10 slumping or breaking, it is customary to use a bonding pitch with a high (for example, 110C) softening point. This means that the brick must be formed (pressed~ with a hot aggregate/
pitch mixture which, when it cools, hardens to form a strong, coherent brick.
In recent years, for various reasons~ for example, to avoid working with hot pitch mixtures, it has become the practice to use a synthetic resin, for example a phenol formaldehyde resin, as bond. These resins can be used in liquid form at room temperature to form the brick and are 20 then set by heating at temperatures of, for example, 110 to 300C to form strong, hard, refractory shapes.
These products are placed in service without fir-ing at elevated temperatures, although they may be tempered at temperatures up to 500C and, in rare instances, coked at 25 temperatures up to 1000C. When placed in service in a furnace which is raised to an elevated temperature, the carbonaceous materials in the brick coke, forming a carbon bond.
When a synthe~ic resin bond was substitu~ed for 30 the tar or pitch bond in refractories con~aining graphite, it was found that the substitution led to low density, high porosity, and lowered streng~h in the brick. In other words, the bonding of the gr~ins by the matrix was generally ~2 poorer when the resin was substituted directly for the pitch in prior compositions.
The present invention is directed to the solution of this problem. In other words, ~he present invention permits the forming of resin-bond~od, graphite-containing refractory compositions into brick which have as high density and strength, and as low porosity, as the former tar or pitch-bonded refractorie 5 containing graphite. In addition, the invention has further application in that it also improves the properties of graphitic refractory brick bonded with a natural resin, such as coal tar pitch.
Swmmary of the Invention The foregoing problem is solved by using a carbon aceous refractory composition for pressing brick shapes consisting essentially o (1) from 60 to 90% refractory oxide aggregate, substantially all of which is coarser than O. 15 mm (+100 mesh), and (2~ a carbonaceous matrix of from
CARBONACEOUS ~EFRACTORY COMPOSITION FOR PRESSING
BRI~K SHAPES
Back~round of the Invention Fhis invention pertains to carbonaceous refractory compositions, particularly such compositions suited for press-ing into brick shape.
It is known to form a refractory brick by pressing a composition of refractory aggregate (for example, refractory periclase grain) combined with a pitch bond which may also contain other carbonaceous materials, such 2S carbon black, graphite, and the like. In order to for~ a pressed brick which has adequate ~tren8th to be handled and shipped without 10 slumping or breaking, it is customary to use a bonding pitch with a high (for example, 110C) softening point. This means that the brick must be formed (pressed~ with a hot aggregate/
pitch mixture which, when it cools, hardens to form a strong, coherent brick.
In recent years, for various reasons~ for example, to avoid working with hot pitch mixtures, it has become the practice to use a synthetic resin, for example a phenol formaldehyde resin, as bond. These resins can be used in liquid form at room temperature to form the brick and are 20 then set by heating at temperatures of, for example, 110 to 300C to form strong, hard, refractory shapes.
These products are placed in service without fir-ing at elevated temperatures, although they may be tempered at temperatures up to 500C and, in rare instances, coked at 25 temperatures up to 1000C. When placed in service in a furnace which is raised to an elevated temperature, the carbonaceous materials in the brick coke, forming a carbon bond.
When a synthe~ic resin bond was substitu~ed for 30 the tar or pitch bond in refractories con~aining graphite, it was found that the substitution led to low density, high porosity, and lowered streng~h in the brick. In other words, the bonding of the gr~ins by the matrix was generally ~2 poorer when the resin was substituted directly for the pitch in prior compositions.
The present invention is directed to the solution of this problem. In other words, ~he present invention permits the forming of resin-bond~od, graphite-containing refractory compositions into brick which have as high density and strength, and as low porosity, as the former tar or pitch-bonded refractorie 5 containing graphite. In addition, the invention has further application in that it also improves the properties of graphitic refractory brick bonded with a natural resin, such as coal tar pitch.
Swmmary of the Invention The foregoing problem is solved by using a carbon aceous refractory composition for pressing brick shapes consisting essentially o (1) from 60 to 90% refractory oxide aggregate, substantially all of which is coarser than O. 15 mm (+100 mesh), and (2~ a carbonaceous matrix of from
2% to 30% graphite, substantially all finer than 0.4 mm (-35 mesh), 2% to 8% resin and from 0% to 6% other carbon material, said matrix being substantially free of oxide refractory materi~l, all percen~ages being by weight and based on the total weight of the composition.
Detailed Description The refractory aggregate used in practicing the invention may be any such known material, for example~
tabular alwmina, calcined 1int clay, and the like. However, the invention is most useful with periclase refractory ag gregate. A particularly preferred aggregate is periclase containing at least 95% MgO.
In general~ the aggrega~e will be sized according to wellknown principles to o`btain m~;ml1m packing and dens-ity. However, in the practîce of ~he invention, ~he sizing of the aggregate is different from ~hat of conventional oxide re~ractories. In conven~ional refractories, the siz-ing of the aggregate ranges from a top size of, for example, 4.7 or 6.7 mm (~4 or -3 mesh) down to material finer than 44 microns (-325 mesh), the so-called sub-sieve si~e material or ball mill fines. This material finer than 44 microns can be as much as 15 or 20% of the total weight OL
the refractory aggregates in conventional compositions.
In the present invention, on the other hand, the oxide refractory aggregate is all coarser than 0.15 mm (100 mesh), and preferably is coarser than 0.2 mm (65 mesh), and most preferably contains no material smaller than 0.4 mm 10 (35 mesh). It is the discovery of this invention that when the oxide refrac~ory aggregate is confined to these coarser æizes, and the matrix material consists entirely o carbon-aceous material, that the problems originally encountered in substituting the synthetic resin bond for the pitch bond, 15 the decreased density and strength, are overcome.
The resin may be any such material, but is prefer-ably a synthetic resin which is initially liquid, and remains so during the forming process, but which subsequently sets up, either at ambient temperature or under the application 20 of limi~ed heat, for example, temperatures up to 110 to 300C. A particularly preferred form o resin is one of the phenol formaldehyde resins. These are described in detail in the article on "Phenolic Resins" in Mark-Gaylord's Encyclopedia of Polymer Science and Technolo~y.
While the present invention is particularly useful with synthetic resins, such as the phenolic resins, it can also be used with "natural" resins, such as coal ~ar pitch, and the term "resin," as used in the specification and claims, is intended to include such materials.
The graphite use~ may be any such material, pre-ferably of high purity9 i.e., less than 10% ash, and most preferably is of the type known as "flake graphite".
The matrix of ~he brick of this invention can con-tain other carbonaceous material, ~or example, carbon black, 35 such as thermal black or furnace black, ground an~hraci~e, gro~md coke, and ~he like.
Refractory shapes are made from the composition of the present invention by mixing ~he various ingredients, for example in an Eirich or Muller mixer, pressing the compo-5 sition into brick shape, for exam~le on a mechanical press,at a pressure o up to 1400 kg/cm (20,000 psi)~ The brick so formed are allowed to harden or they may be subjected to gentle heating, for example, to a temperature of 180C, to hasten the set~ing o~ the resin bond. The brick are then 10 shipped to the user who places them in a furnace structure, for example a basic oxygen furnace. The use of this invention is particularly advantageous when using a mechan-ical or toggle press, on which it has proven very difficult to press graphi~e-containing brick.
Examples Tab~e I sets forth various compositions, some of which are within ~he scope of this invention. Specifically, Composi~ions 3, 4, 6, 7, 8, and 9 ~re within the scope of the invention, the other compositions being comparison compo-20 sitions.
The aggregate used in the examples is a periclasehaving the following typical chemical compositiono 2.3% CaO, 0.8% SiO2, 0 2% Al2O39 0.2% Fe2O3, 0-03% B2O3~ and, by difference, 96.5% MgO. In Table I, the percentage amounts 25 for the different grain sizes are based on the total weight of grain whereas the amounts of ~he other ingredients are based on parts by weight.
The graphites used were flake graphites manufac-tured by Asbury Graphite Mills, Inc., the various numbers 30 indicated in Table I being grade designa~ions applied by the manufacturer. Typically, the graphi~e has an ash content of 8%, the rem~inder being carbon. The carbon blacks are thermal blacks, the NS grade being manuactured by Cabot Corp. and ~he MT being manufactured by R. T. Vanderbilt.
35 Typically, these are aggregates of roughly spherical part icles with earbon eQntentS greater than 97%, produced by the thermal decomposition of oil or natural g~5.
~t ~^ ~
O~ O ~ ~I ~ ~ ~ O
O ~'` O C~ O O
00 OOOO~ Ocoo~
O O ~ O ~ ~
I~ ~ O O C\ ~ O ~D C
~ rC ~
o o o oo ~ l Z c~ O i~ ~ O ~ ~ ~ a .
Cr rt C~l ~ ~~1u~ or~
~_~ <r r O
~ O ~0Or l ~) 00 O O OO ~ ~ O~r-l m co ~, ~ ~ ~
i~
rr U~ o o o o o ~ . O ~ ~ I ~ I
;: .
~ ^ cr 00 t~l r l rt C~
S `J
00 ~ 1~ 0 r~l Ul ~t C~ 1~Ul O ~ Lrl 00 ~ 1~ C~ 1~ Z C~l r Lt~ O 00 00 ~ C~l a ~ ~ ~
~ C~l r~l IIJ U
O ~
.. ; ~ ~ I I I
C I I ~ l ~ O C, ~r 1 1 ~
r~ r r ~ r~l O ~
As to the bonding material~ the pitch used was a 116C softening point (cube-in-air equlvalent) coal tar pltch, and the res~n wa~ a phenol formaldehyde liquld bond~
ing resin sold by t~e Borden ~hemical Company under the name "Durite". It ha~ a viscosity ~t 77~F (25C~ o from 250 to 350 Cp8, and a gel time at 121C o from 32 to 40 minute~. The sulfur added ln the case of the pitch bond was flower~ of sulfur, a very finely divlded fonm of ~ulfur.
In Table I, bulk density i~ giYen ln pounds per 10 cubic foot3 measured a~ the brick came off the press; cold modu~ U5 of rupture (CMOR~ is given in pounds per square inch and measured after c~r~ng; apparent porosity is in volume percent, measured ater coklng; sonic veloclty is in feet per second~ measured along the length (L~ width ~W~
15 and thickness (T) o the cured brick~
Compositio~ 1 is a comparison composition which is typical of prior art tar bondzd periclase reractory brick. As can be seen, ~t conta~ns a substantial amount (17%3 of material finer than 44 microns ~-325 mesh).
20 Composition 2 i9 another comparison example~ and shows ~ha~
the direct subst~tution of a synthetic resin bond for the pitch bond lesds to grPatly reduced densities and strengths~
even thou~h the amount of material under 44 micron~ ~s considerably le~s tha~ in Composition lo The foregoing compositions are to be com~ared with Compo~itions 3 and 49 made a~cording to the presen~
invention. A~ can he seen from Table I~ all the periclase aggregate finer than 0~4 mm ha~ been ell~n~ed from these compositionsO This change resulted i~ brlck of increased 30 density compared to Compositio~ 29 a densl~y ~ui~e s~m~l~r to that o brick made from Compositio~ 1. The difference be~ween Compositlon~ 3 and 4 is in the max~m~m size of the periclase aggregateg Composi~i.on 3 contalning ~ggregat~ all of which wa~ sm~ller than 4.~ mm, and Compositioa 4 con 35 taining aggregate as large aq 10 mm~
~ "r;'~
* Trade Mark The sonic velocity shown in Table I for several of the compositions is an indication of the tightness or strength of bonding together of the aggregate particles, higher sonic velocity indicating better bonding. As can be seen, the sonic veloci~y in Composition 4 is significantly greater than that of Composition 2.
Composition 6 is a pitch~-bonded brick with the sizing of the present invention, and shows, by comparison with Composition 5, the resulting improvement in properties.
Compositions 7, 8, and 3 are also wi~hin the scope of the present invention, Compositions 7 and 8 having - sufficient carbonaceous material to result in a residual carbon content of about 19%, whereas that of Composition 9 is about 30%.
The residual carbon content of all these brick is ; determined by taking the brick, packing them in carbon granules in a closed container, heating to a temperature of ~ 970C for 3 hours to coke them, and then, after cooling, - weighing the coked brick. The specimen is then ignited to 20 burn off all the carbon and again weighed, the difference in the two weights indicating the amount of residual carbon in the coked brickA
-~ The brick whose properties are shown in Table I
were made by m;~;rlg the indicated ingredients for 7 or 8 25 minutes in a Muller or Eirich mixer, depending on whether the bond was resin or pitch~ and pressing the resulting mixture in a Boyd X press at a pressure of 5000 to 20,000 psi (350 to 1400 kg/cm2), depending on composition.
From the foregoing examples, it can be seen that 30 e~clusion of the refractory oxide aggregate finer than 0.2 mm, and preferably excluding that finer than 0.4 mm, results in higher density for a resin-bonded product, as compared to the same composi~ion co~taining ox~de refractory material in the finer, or ma~rix~ portionO
In addi~ion ~o the improvement in quanti~atively ~ 6 measurable properties, petrographic examination of the compositions of the presen~ invention shows them to have better bond continuity and particle compaction ~han compo-si~ions with fine oxide particles. Also, in pressing, it was very difficult, if not impossible, to get crack-free brick with the compositions containing fine oxide material, whereas the compositions according to this invention pressed very well, without cracking.
In the specification and claims, percentages and 10 parts are by weight unless otherwise indica~ed, except that porosities are expressed in volurne percent. Mesh sizes referred to herein are Tyler standard screen sizes which are defined in Chemical Engineers' Handbook, John H. Perry, Editor-in-Chief, Third Edition, 1950, published by McGraw 15 Hill Book Company, at page 963. For example, a 100 mesh screen opening corresponds to 147 microns, and 325 mesh to 44 microns. Ar~alyses of mineral components are reported in the usual manner, expressed as simple oxides, e.g. MgO and SiO2, although the components may actually be present in 20 various combinations, e.g. as a magnesium silicate.
Detailed Description The refractory aggregate used in practicing the invention may be any such known material, for example~
tabular alwmina, calcined 1int clay, and the like. However, the invention is most useful with periclase refractory ag gregate. A particularly preferred aggregate is periclase containing at least 95% MgO.
In general~ the aggrega~e will be sized according to wellknown principles to o`btain m~;ml1m packing and dens-ity. However, in the practîce of ~he invention, ~he sizing of the aggregate is different from ~hat of conventional oxide re~ractories. In conven~ional refractories, the siz-ing of the aggregate ranges from a top size of, for example, 4.7 or 6.7 mm (~4 or -3 mesh) down to material finer than 44 microns (-325 mesh), the so-called sub-sieve si~e material or ball mill fines. This material finer than 44 microns can be as much as 15 or 20% of the total weight OL
the refractory aggregates in conventional compositions.
In the present invention, on the other hand, the oxide refractory aggregate is all coarser than 0.15 mm (100 mesh), and preferably is coarser than 0.2 mm (65 mesh), and most preferably contains no material smaller than 0.4 mm 10 (35 mesh). It is the discovery of this invention that when the oxide refrac~ory aggregate is confined to these coarser æizes, and the matrix material consists entirely o carbon-aceous material, that the problems originally encountered in substituting the synthetic resin bond for the pitch bond, 15 the decreased density and strength, are overcome.
The resin may be any such material, but is prefer-ably a synthetic resin which is initially liquid, and remains so during the forming process, but which subsequently sets up, either at ambient temperature or under the application 20 of limi~ed heat, for example, temperatures up to 110 to 300C. A particularly preferred form o resin is one of the phenol formaldehyde resins. These are described in detail in the article on "Phenolic Resins" in Mark-Gaylord's Encyclopedia of Polymer Science and Technolo~y.
While the present invention is particularly useful with synthetic resins, such as the phenolic resins, it can also be used with "natural" resins, such as coal ~ar pitch, and the term "resin," as used in the specification and claims, is intended to include such materials.
The graphite use~ may be any such material, pre-ferably of high purity9 i.e., less than 10% ash, and most preferably is of the type known as "flake graphite".
The matrix of ~he brick of this invention can con-tain other carbonaceous material, ~or example, carbon black, 35 such as thermal black or furnace black, ground an~hraci~e, gro~md coke, and ~he like.
Refractory shapes are made from the composition of the present invention by mixing ~he various ingredients, for example in an Eirich or Muller mixer, pressing the compo-5 sition into brick shape, for exam~le on a mechanical press,at a pressure o up to 1400 kg/cm (20,000 psi)~ The brick so formed are allowed to harden or they may be subjected to gentle heating, for example, to a temperature of 180C, to hasten the set~ing o~ the resin bond. The brick are then 10 shipped to the user who places them in a furnace structure, for example a basic oxygen furnace. The use of this invention is particularly advantageous when using a mechan-ical or toggle press, on which it has proven very difficult to press graphi~e-containing brick.
Examples Tab~e I sets forth various compositions, some of which are within ~he scope of this invention. Specifically, Composi~ions 3, 4, 6, 7, 8, and 9 ~re within the scope of the invention, the other compositions being comparison compo-20 sitions.
The aggregate used in the examples is a periclasehaving the following typical chemical compositiono 2.3% CaO, 0.8% SiO2, 0 2% Al2O39 0.2% Fe2O3, 0-03% B2O3~ and, by difference, 96.5% MgO. In Table I, the percentage amounts 25 for the different grain sizes are based on the total weight of grain whereas the amounts of ~he other ingredients are based on parts by weight.
The graphites used were flake graphites manufac-tured by Asbury Graphite Mills, Inc., the various numbers 30 indicated in Table I being grade designa~ions applied by the manufacturer. Typically, the graphi~e has an ash content of 8%, the rem~inder being carbon. The carbon blacks are thermal blacks, the NS grade being manuactured by Cabot Corp. and ~he MT being manufactured by R. T. Vanderbilt.
35 Typically, these are aggregates of roughly spherical part icles with earbon eQntentS greater than 97%, produced by the thermal decomposition of oil or natural g~5.
~t ~^ ~
O~ O ~ ~I ~ ~ ~ O
O ~'` O C~ O O
00 OOOO~ Ocoo~
O O ~ O ~ ~
I~ ~ O O C\ ~ O ~D C
~ rC ~
o o o oo ~ l Z c~ O i~ ~ O ~ ~ ~ a .
Cr rt C~l ~ ~~1u~ or~
~_~ <r r O
~ O ~0Or l ~) 00 O O OO ~ ~ O~r-l m co ~, ~ ~ ~
i~
rr U~ o o o o o ~ . O ~ ~ I ~ I
;: .
~ ^ cr 00 t~l r l rt C~
S `J
00 ~ 1~ 0 r~l Ul ~t C~ 1~Ul O ~ Lrl 00 ~ 1~ C~ 1~ Z C~l r Lt~ O 00 00 ~ C~l a ~ ~ ~
~ C~l r~l IIJ U
O ~
.. ; ~ ~ I I I
C I I ~ l ~ O C, ~r 1 1 ~
r~ r r ~ r~l O ~
As to the bonding material~ the pitch used was a 116C softening point (cube-in-air equlvalent) coal tar pltch, and the res~n wa~ a phenol formaldehyde liquld bond~
ing resin sold by t~e Borden ~hemical Company under the name "Durite". It ha~ a viscosity ~t 77~F (25C~ o from 250 to 350 Cp8, and a gel time at 121C o from 32 to 40 minute~. The sulfur added ln the case of the pitch bond was flower~ of sulfur, a very finely divlded fonm of ~ulfur.
In Table I, bulk density i~ giYen ln pounds per 10 cubic foot3 measured a~ the brick came off the press; cold modu~ U5 of rupture (CMOR~ is given in pounds per square inch and measured after c~r~ng; apparent porosity is in volume percent, measured ater coklng; sonic veloclty is in feet per second~ measured along the length (L~ width ~W~
15 and thickness (T) o the cured brick~
Compositio~ 1 is a comparison composition which is typical of prior art tar bondzd periclase reractory brick. As can be seen, ~t conta~ns a substantial amount (17%3 of material finer than 44 microns ~-325 mesh).
20 Composition 2 i9 another comparison example~ and shows ~ha~
the direct subst~tution of a synthetic resin bond for the pitch bond lesds to grPatly reduced densities and strengths~
even thou~h the amount of material under 44 micron~ ~s considerably le~s tha~ in Composition lo The foregoing compositions are to be com~ared with Compo~itions 3 and 49 made a~cording to the presen~
invention. A~ can he seen from Table I~ all the periclase aggregate finer than 0~4 mm ha~ been ell~n~ed from these compositionsO This change resulted i~ brlck of increased 30 density compared to Compositio~ 29 a densl~y ~ui~e s~m~l~r to that o brick made from Compositio~ 1. The difference be~ween Compositlon~ 3 and 4 is in the max~m~m size of the periclase aggregateg Composi~i.on 3 contalning ~ggregat~ all of which wa~ sm~ller than 4.~ mm, and Compositioa 4 con 35 taining aggregate as large aq 10 mm~
~ "r;'~
* Trade Mark The sonic velocity shown in Table I for several of the compositions is an indication of the tightness or strength of bonding together of the aggregate particles, higher sonic velocity indicating better bonding. As can be seen, the sonic veloci~y in Composition 4 is significantly greater than that of Composition 2.
Composition 6 is a pitch~-bonded brick with the sizing of the present invention, and shows, by comparison with Composition 5, the resulting improvement in properties.
Compositions 7, 8, and 3 are also wi~hin the scope of the present invention, Compositions 7 and 8 having - sufficient carbonaceous material to result in a residual carbon content of about 19%, whereas that of Composition 9 is about 30%.
The residual carbon content of all these brick is ; determined by taking the brick, packing them in carbon granules in a closed container, heating to a temperature of ~ 970C for 3 hours to coke them, and then, after cooling, - weighing the coked brick. The specimen is then ignited to 20 burn off all the carbon and again weighed, the difference in the two weights indicating the amount of residual carbon in the coked brickA
-~ The brick whose properties are shown in Table I
were made by m;~;rlg the indicated ingredients for 7 or 8 25 minutes in a Muller or Eirich mixer, depending on whether the bond was resin or pitch~ and pressing the resulting mixture in a Boyd X press at a pressure of 5000 to 20,000 psi (350 to 1400 kg/cm2), depending on composition.
From the foregoing examples, it can be seen that 30 e~clusion of the refractory oxide aggregate finer than 0.2 mm, and preferably excluding that finer than 0.4 mm, results in higher density for a resin-bonded product, as compared to the same composi~ion co~taining ox~de refractory material in the finer, or ma~rix~ portionO
In addi~ion ~o the improvement in quanti~atively ~ 6 measurable properties, petrographic examination of the compositions of the presen~ invention shows them to have better bond continuity and particle compaction ~han compo-si~ions with fine oxide particles. Also, in pressing, it was very difficult, if not impossible, to get crack-free brick with the compositions containing fine oxide material, whereas the compositions according to this invention pressed very well, without cracking.
In the specification and claims, percentages and 10 parts are by weight unless otherwise indica~ed, except that porosities are expressed in volurne percent. Mesh sizes referred to herein are Tyler standard screen sizes which are defined in Chemical Engineers' Handbook, John H. Perry, Editor-in-Chief, Third Edition, 1950, published by McGraw 15 Hill Book Company, at page 963. For example, a 100 mesh screen opening corresponds to 147 microns, and 325 mesh to 44 microns. Ar~alyses of mineral components are reported in the usual manner, expressed as simple oxides, e.g. MgO and SiO2, although the components may actually be present in 20 various combinations, e.g. as a magnesium silicate.
Claims (20)
1. A carbonaceous refractory composition for pressing brick shapes consisting essentially of (1) from 60 to 90% refractory oxide aggregate, substantially all of which is coarser than 0.15 mm, and (2) a carbonaceous matrix of from 2% to 30% graphite, substantially all finer than 0.4 mm, 2% to 8% resin, and from 0% to 6% other car-bon material, said matrix being substantially free of ox-ide refractory material, all percentages being by weight and based on the total weight of the composition.
2. Composition according to claim 1 wherein the graphite is flake graphite.
3. Composition according to claim 1 wherein the resin is a phenol formaldehyde resin.
4. Composition according to claim 3 wherein the graphite is flake graphite.
5. Composition according to claim 1, 2 or 3 wherein the aggregate is
6. Composition according to claim 4 wherein the aggregate is periclase.
7. Composition according to claim 1, 2 or 3 wherein the aggregate is periclase and said periclase contains at least 95% MgO.
8. Composition according to claim 6 wherein the periclase contains at least 95% MgO.
9. Composition according to claim 1, 2 or 3 wherein the aggregate is all coarser than 0.2 mm.
10. Composition according to claim 4 wherein the aggregate is all coarser than 0.2 mm.
11. Composition according to claim 1, 2 or 3 wherein the aggregate is all coarser than 0.4 mm.
12. Composition according to claim 4 wherein the aggregate is all coarser than 0.4 mm.
13. Composition according to claim 1, 2 or 3 wherein the aggregate is all coarser than 0.2 mm and said aggregate is periclase.
14. Composition according to claim 10 wherein the aggregate is periclase.
15. Composition according to claim 1, 2 or 3 wherein the aggregate is all coarser than 0.4 mm and said aggregate is periclase.
16. Composition according to claim 12 wherein the aggregate is periclase.
17. Composition according to claim 1, 2 or 3 wherein the aggregate is all coarser than 0.2 mm and said aggregate is periclase containing at least 95% MgO.
18. Composition according to claim 14 wherein said periclase contains at least 95% MgO.
19. Composition according to claim 1, 2 or 3 wherein the aggregate is all coarser than 0.4 mm and said aggregate is periclase containing at least 95% MgO.
20. Composition according to claim 16 wherein the periclase contains at least 95% MgO.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US36771382A | 1982-04-12 | 1982-04-12 | |
| US367,713 | 1982-04-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1199648A true CA1199648A (en) | 1986-01-21 |
Family
ID=23448312
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000424299A Expired CA1199648A (en) | 1982-04-12 | 1983-03-23 | Carbonaceous refractory composition for pressing brick shapes |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1199648A (en) |
| NZ (1) | NZ203671A (en) |
-
1983
- 1983-03-23 CA CA000424299A patent/CA1199648A/en not_active Expired
- 1983-03-23 NZ NZ20367183A patent/NZ203671A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NZ203671A (en) | 1984-10-19 |
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