DRY MATERIAL MIXTURE FOR A BACKFILL, PREFERABLY A REFRACTORY CONCRETE BACKFILL, FOR PRODUCING A HEAVY-CLAY REFRACTORY NON-BASIC PRODUCT, REFRACTORY CONCRETE BACKFILL AND SUCH A PRODUCT, METHOD FOR PRODUCING SAME, LINING, AND INDUSTRIAL FURNACE, CHANNEL TRANSPORT SYSTEM OR MOBILE TRANSPORT VESSEL

Abstract

A dry substance mixture for a batch, preferably a refractory batch, for the production of a coarse ceramic, refractory, non-basic, shaped or unshaped product, such a refractory batch, such a product as well as a method for its production and a lining of an industrial furnace for the aluminum industry, and such an industrial furnace as well as a lining of a launder transport system or a mobile transport vessel for the aluminum industry, and such a launder transport system and such a transport vessel.

Claims

1. A dry substance mixture for a batch, preferably a refractory concrete batch, for the production of a coarse ceramic, refractory, unfired, shaped or unshaped, non-basic product, in particular for a working casing or a backing of a large-volume industrial furnace of the aluminum industry or for a working casing of a launder transport system or a mobile transport vessel of the aluminum industry for the transport of liquid aluminum or a liquid aluminum alloy, the dry substance mixture comprising: a) coarse- and fine-grained aggregate of at least one refractory, non-basic aggregate material with a grain size >200 μm, preferably in a total amount of 45 to 80 ma. %, preferably 50 to 60 ma. %, b) meal-grained aggregate of at least one refractory, non-basic aggregate with a grain size ≤200 μm, preferably in a total amount of 15 to 50 ma. %, preferably 25 to 40 ma. %, wherein the meal-grained aggregate comprise an Al.sub.2O.sub.3 granular material, c) at least one anti-corrosion agent to improve corrosion resistance to molten aluminum, and d) optionally at least one dry binder, wherein the anticorrosive agent comprises at least one first dry, mealy phosphate having a softening point, determined by heating microscopy according to DIN ISO 540:2008, of 600 to 1400° C., preferably 800 to 1300° C., and at least a second dry, mealy phosphate having a softening point, determined by heating microscopy according to DIN ISO 540:2008, of >1600° C., the two phosphates each having a solubility in water at 20° C. according to DIN EN 15216:2008-1 of <50 g/l, preferably <30 g/l, more preferably <20 g/l, and wherein the at least one first phosphate is calcium dihydrogen phosphate (Ca(H.sub.2PO.sub.4).sub.2), magnesium dihydrogen phosphate (Mg(H.sub.2PO.sub.4).sub.2), calcium hydrogen phosphate (CaHPO.sub.4) or magnesium hydrogen phosphate (MgHPO.sub.4) or calcium hydrogen phosphate dihydrate (CaHPO.sub.4.Math.2 H.sub.2O) or magnesium hydrogen phosphate trihydrate (MgHPO.sub.4.Math.3 H.sub.2O), preferably calcium hydrogen phosphate (CaHPO.sub.4), and wherein the at least one second phosphate is aluminum phosphate (AlPO.sub.4).

2. The dry substance mixture according to claim 1, wherein the at least one first phosphate has a solubility in water at 20° C. according to DIN EN 15216:2008-1 of <1 g/l, preferably of <0.1 g/l.

3. The dry substance mixture according to claim 1, wherein the at least one first phosphate is not soluble in water.

4. Dry substance mixture according to claim 1, wherein the at least one first phosphate is a secondary calcium phosphate or magnesium phosphate and/or a primary calcium phosphate or magnesium phosphate.

5. (canceled)

6. The dry substance mixture according to claim 1, wherein the mealy Al.sub.2O.sub.3 granular material has a grain fraction with a grain size ≤100 μm, preferably a grain fraction with a grain size ≤30 μm.

7. The dry material substance according to claim 6, wherein the amount of the grain fraction of the Al.sub.2O.sub.3 granular material with a grain size ≤100 μm in the dry substance mixture is 10 to 45 ma. %, preferably 20 to 35 ma. %, and/or the amount of the grain fraction of the Al.sub.2O.sub.3 granular material with a grain size ≤30 μm in the dry substance mixture is 5 to 35 ma. %, preferably 10 to 20 ma. %.

8. The dry material mixture according to claim 1, wherein the dry substance mixture has a total amount of first phosphate of 2 to 10 ma. %, preferably 4 to 7 ma. % and/or the dry substance mixture has a total amount of second phosphate of 2 to 10 ma. %, preferably 2 to 6 ma. %.

9. The dry substance mixture according to claim 1, wherein the dry substance mixture comprises a total amount of P.sub.2O.sub.5, determined by means of X-ray fluorescence analysis in accordance with DIN EN ISO 12677:2013-2, resulting from the at least one first phosphate of 1.0 to 6.0 ma. %, preferably 2.0 to 4.0 ma. % and/or resulting from the at least one second phosphate of 1.0 to 6.0 ma. %, preferably 1.2 to 3.0 ma. %.

10. (canceled)

11. (canceled)

12. The dry substance mixture according to claim 1, wherein the first and second phosphates have a bulk density according to DIN ISO 697:1984-01 of from 200 to 1400 g/l, preferably from 400 to 900 g/l.

13. The dry substance mixture according to claim 1, wherein one or more of the following exists: the Al.sub.2O.sub.3 granular material consists of at least one raw material rich in alumina with an Al.sub.2O.sub.3 content of ≥40 ma. %, preferably ≥90 ma. %, particularly preferably ≥95 ma. %; and/or the Al.sub.2O.sub.3 granular material consists of alumina, preferably fused alumina, preferably white fused alumina, and/or calcined alumina, e.g. reactive alumina, and/or sintered alumina, preferably tabular alumina, and/or sintered bauxite, and/or of spinel and/or mullite and/or fireclay; and/or the dry substance mixture has a total amount of 15 to 50 ma. %, preferably 25 to 40 ma. %, of mealy Al.sub.2O.sub.3 granular material.

14. (canceled)

15. (canceled)

16. The dry substance mixture according to claim 1, characterized in that the coarse- and fine-grained aggregate has a fine-grain fraction with a grain size ≤1 mm and >200 μm and a coarse-grain fraction with a grain size >1 mm.

17. The aggregate mixture according to claim 1, wherein the aggregate consists of at least 40 ma. %, preferably of at least 80 ma. %, preferably of 90 ma. %, preferably of 100 ma. %, of aggregate materials of alumina and/or aluminosilicates.

18. (canceled)

19. The dry substance mixture according to claim 1, wherein the dry binder is a hydraulic binder, preferably calcium aluminate cement, and/or water glass and/or an aluminum hydroxide binder and/or a geopolymer binder and/or a phosphate binder.

20. The dry substance mixture according to claim 1, wherein the dry substance mixture further comprises at least one liquefier and/or a further, phosphate-free, anti-corrosion agent, preferably barium sulfate and/or a fluoride-containing anti-corrosion agent, preferably calcium fluoride and/or strontium fluoride and/or aluminum fluoride and/or an anti-corrosion agent from a stable calcium aluminate phase, such as from CA, CA.sub.2 or CA.sub.6.

21. (canceled)

22. A refractory concrete batch for the production of a coarse ceramic, refractory, unfired, shaped or unshaped, non-basic product, in particular for a working casing or a backing of a large-volume industrial furnace of the aluminum industry or for a working casing of a launder transport system or a mobile transport vessel of the aluminum industry for the transport of liquid aluminum or a liquid aluminum alloy, the refractory concrete batch comprising: a) a dry substance mixture according to claim 1, and b) in addition to the dry substance mixture at least one liquid binder in enclosed form.

23. The refractory concrete batch according to claim 22, wherein the batch has a total content of P.sub.2O.sub.5, determined by X-ray fluorescence analysis in accordance with DIN EN ISO 12677:2013-2, of 2 to 10 ma. %, preferably of 4 to 6 ma. %, based on the total dry mass of the batch.

24. The refractory concrete batch according to claim 22, wherein the batch is a liquefied refractory concrete batch and/or the liquid binder is a silica sol and/or an alumina sol and/or an organic binder and/or a phosphate binder.

25. (canceled)

26. (canceled)

27. (canceled)

28. A method for the production of a coarse ceramic, refractory, unfired, shaped or unshaped, non-basic product, in particular for a working casing or a backing of a large-volume industrial furnace of the aluminum industry, wherein the method comprises forming the product from a batch comprising a dry substance mixture according to claim 1.

29. A lining of an industrial furnace, preferably a smelting furnace or casting furnace or holding furnace, or of a stationary launder transport system or a mobile transport vessel for transporting liquid aluminum or a liquid aluminum alloy, used in the primary or secondary aluminum industry, wherein the lining comprises at least one refractory product, preferably a prefabricated component, which is produced from a batch comprising a dry substance mixture according to claim 1.

30. The lining according to claim 29, wherein the lining comprises a working casing and/or an insulating backing comprising the at least one refractory product.

31. The lining according to claim 30, wherein the working casing is installed in a single-layer or multi-layer masonry and/or the lining is arranged in a bath region, in a region of a ramp or in a burner field of the industrial furnace.

32. (canceled)

33. (canceled)

34. An industrial furnace for the primary or secondary aluminum industry, preferably smelting furnace or casting furnace or holding furnace, wherein the industrial furnace comprises a lining according to claim 29.

35. The industrial furnace according to claim 34, wherein the smelting furnace is a drum melting furnace, e.g. a tilting drum melting furnace, a shaft smelting furnace, an induction furnace, e.g. a channel induction furnace, or a two- or multi-chamber furnace.

36. A stationary launder transport system for the primary or secondary aluminum industry for transporting liquid aluminum or a liquid aluminum alloy, wherein the launder transport system comprises a lining according to claim 29.

37. A mobile transport vessel for the primary or secondary aluminum industry for transporting liquid aluminum or a liquid aluminum alloy, wherein the transport vessel comprises a lining according to claim 29.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0082] In order that the disclosure may be well understood, the present disclosure is explained in more detail by way of example with reference to the accompanying drawings, in which:

[0083] FIG. 1 shows a graph of differential voltage plotted as a function of temperature for temperature-dependent reactions in the Ca(HPO.sub.4)/Al.sub.2O.sub.3 system;

[0084] FIG. 2: shows a graph of differential voltage plotted as a function of temperature for temperature-dependent reactions in the system AlPO.sub.4/Al.sub.2O.sub.3;

[0085] FIG. 3: shows a cross-section of a s crucible exposed to liquid aluminum at 1000° C./150h;

[0086] FIG. 4: shows a cross-section of a s crucible exposed to liquid aluminum at 1200° C./150h.

[0087] The drawings are provided herewith for purely illustrative purposes and are not intended to limit the scope of the present invention.

DETAILED DESCRIPTION

[0088] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. It should be understood that throughout the description, corresponding reference numerals indicate like or corresponding parts and features.

[0089] Within this specification, embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0090] In general, the present disclosure provides a dry substance mixture, a refractory concrete batch, and a lining as described above and as further defined herein, as well as an industrial furnace, a launder transport system, and a mobile transport that incorporates said lining and a method of forming a product from the dry substance mixture.

[0091] Within the scope of the present disclosure, it was surprisingly found that excellent corrosion resistance can be achieved in case of wetting with liquid aluminum and aluminum alloys if the dry substance mixture according to the invention comprises at least a first dry, mealy phosphate with a softening point determined by heating microscopy according to DIN ISO 540:2008 of 600 to 1400° C., preferably 800 to 1300° C., and at least a second dry, mealy phosphate with a softening point determined by heating microscopy according to DIN ISO 540:2008 of >1500° C., preferably >1600° C., particularly preferably >1700° C., in combination with a mealy Al.sub.2O.sub.3 granular material.

[0092] The dry substance mixture according to the present disclosure thus has the following components: [0093] a) coarse- and fine-grained aggregate of at least one refractory, non-basic, aggregate material with a grain size >200 μm, preferably in a total amount of 45 to 80 ma. %, preferably 50 to 60 ma. %, [0094] b) meal-grained aggregate of at least one refractory, non-basic, aggregate material with a grain size ≤200 μm, preferably in a total amount of 15 to 50 ma. %, preferably 25 to 40 ma. %, wherein the meal-grained aggregate has an Al.sub.2O.sub.3 granular material, [0095] c) optionally at least one binder in dry form, [0096] d) at least one anti-corrosion agent, in particular an anti-wetting agent, in the form of a first dry, mealy phosphate with a softening point according to DIN ISO 540:2008 of 600 to 1400, preferably 800 to 1300° C., and [0097] e) at least one anti-corrosion agent, in particular an anti-wetting agent, in the form of a second dry, mealy phosphate having a softening point according to DIN ISO 540:2008 of >1500° C., preferably >1600° C., particularly preferably >1700° C.

[0098] The refractory concrete batch according to the present disclosure has the dry substance mixture and, in addition to the dry substance mixture, at least one liquid binder in enclosed form.

[0099] Phosphates are the salts and esters of orthophosphoric acid (H.sub.3PO.sub.4). Phosphorus (P) is present in the oxidation state (V) in all these compounds. A further distinction is made between, among others, primary phosphates (dihydrogen phosphates), secondary phosphates (hydrogen phosphates) and tertiary phosphates.

[0100] Preferably, the first phosphate is a primary phosphate, preferably an alkaline earth dihydrogen phosphate, or a secondary phosphate, preferably an alkaline earth hydrogen phosphate. However, it may also be a tertiary phosphate.

[0101] In addition, although the first phosphate is preferably an orthophosphate, it may also be a metaphosphate.

[0102] Preferably, it is calcium dihydrogen phosphate (Ca(H.sub.2PO.sub.4).sub.2), magnesium dihydrogen phosphate (Mg(H.sub.2PO.sub.4).sub.2), calcium hydrogen phosphate (CaHPO.sub.4) or magnesium hydrogen phosphate (MgHPO.sub.4).

[0103] Also well suited for the present disclosure are calcium hydrogen phosphate as dihydrate (CaHPO.sub.4.Math.2 H.sub.2O) and magnesium hydrogen phosphate as trihydrate (MgHPO.sub.4.Math.3 H.sub.2O).

[0104] The second phosphate is preferably a tertiary phosphate, preferably aluminum phosphate (AlPO.sub.4) or zirconium phosphate (ZrP.sub.2O.sub.7). Aluminum phosphate (AlPO.sub.4) is particularly preferred.

[0105] According to another aspect of the present disclosure, the two phosphates are not soluble or only moderately soluble in water so as not to influence the pH value of the batch fresh mass produced from the batch according to the invention. According to the invention, the phosphates have a solubility in water at 20° C. according to DIN EN 15216:2008-1 of <50 g/l, preferably <30 g/l, particularly preferably <20 g/l.

[0106] Particularly preferably, the phosphates comprise a solubility in water at 20° C. according to DIN EN 15216:2008-1 of <1 g/l, preferably of <0.1 g/l. Such phosphates are particularly suitable for the present disclosure.

[0107] In general, the first phosphate is preferably a calcium phosphate that is not soluble in water or a magnesium phosphate that is not soluble in water or a calcium phosphate or a magnesium phosphate with the indicated low solubility, in particular with a solubility <1 g/L, preferably <0.1 g/L, and the softening point indicated for the first phosphate.

[0108] The calcium phosphate or magnesium phosphate may be anhydrous or hydrous, preferably it is anhydrous.

[0109] Particularly preferably, it is a secondary, anhydrous or hydrous, preferably anhydrous, calcium phosphate (=calcium hydrogen phosphate) or a secondary, anhydrous or hydrous, preferably anhydrous, magnesium phosphate (=magnesium hydrogen phosphate). In addition, the batch preferably has a total content of P.sub.2O.sub.5, based on the total dry mass of the batch, determined by X-ray fluorescence analysis according to DIN EN ISO 12677:2013-2, of 2 to 10 ma.-%, preferably from 4 to 6 ma. %.

[0110] Preferably, the dry substance mixture has a total amount of 2 to 10 wt. %, preferably 4 to 7 ma. %, of first phosphate.

[0111] Preferably, moreover, the total amount of P.sub.2O.sub.5 in the dry substance mixture resulting from the at least one first phosphate, determined by means of X-ray fluorescence analysis in accordance with DIN EN ISO 12677:2013-2, is 1.0 to 6.0 ma. %, preferably 2.0 to 4.0 ma. %.

[0112] Preferably, the dry substance mixture also has a total amount of 2 to 10 ma. %, preferably 2 to 6 ma. %, of second phosphate.

[0113] Preferably, moreover, the total amount of P.sub.2O.sub.5 in the dry substance mixture resulting from the at least one second phosphate, determined by means of X-ray fluorescence analysis in accordance with DIN EN ISO 12677, is 1.0 to 6.0 ma. %, preferably from 1.2 to 3.0 ma. %.

[0114] Furthermore, the two phosphates preferably comprise a bulk density according to DIN ISO 697:1984-01 of 200 to 1400 g/l, preferably 400 to 900 g/l. The bulk density provides good processing behaviour.

[0115] In addition, the phosphates are preferably label-free (non-toxic/non-harmful to health).

[0116] The Al.sub.2O.sub.3 component or Al.sub.2O.sub.3 granular material consists of at least one raw material containing at least 40 ma. %, preferably at least 90 ma. %, particularly preferably at least 95 ma. %, aluminum oxide (Al.sub.2O.sub.3).

[0117] The Al.sub.2O.sub.3 component or Al.sub.2O.sub.3 granular material thus particularly preferably consists of alumina. However, it can also consist of an aluminosilicate or another raw material rich in alumina.

[0118] Preferably, the mealy Al.sub.2O.sub.3 granular material consists of alumina, preferably fused alumina, in particular white fused alumina, and/or calcined alumina, e.g. reactive alumina, and/or sintered alumina, particularly preferably tabular alumina, or sintered bauxite. However, it may also consist of spinel and/or mullite and/or fireclay, for example. The Al.sub.2O.sub.3 granular material can thus consist of one or more raw materials rich in alumina.

[0119] Preferably, the batch has a total amount of 15 to 50 ma. %, preferably 25 to 40 wt. %, of mealy Al.sub.2O.sub.3 granular material, based on the total dry mass of the batch.

[0120] Thereby, the mealy Al.sub.2O.sub.3 granular material preferably has a grain fraction with a grain size ≤100 μm, preferably a grain fraction with a grain size ≤30 μm.

[0121] Preferably, the amount of the grain fraction of the Al.sub.2O.sub.3 granular material with a grain size ≤100 μm in the dry substance mixture is 10 to 45 ma. %, preferably 20 to 35 ma. %.

[0122] Preferably, the amount of the grain fraction of the Al.sub.2O.sub.3 granular material with a grain size ≤30 μm in the dry substance mixture is 5 to 35 ma. %, preferably 10 to 20 ma. %.

[0123] According to another aspect of the present disclosure, the combination of the two phosphates with the mealy Al.sub.2O.sub.3 granular material provides a corrosion protection effect over a wide temperature range from 1000 to 1400° C.

[0124] Preferably, the mass ratio of the two phosphates: Al.sub.2O.sub.3 granular material is 1:2 to 1:6, preferably 1:3 to 1:5.

[0125] The first phosphate, in the presence of Al.sub.2O.sub.3 as reactant, forms new phases below 1050° C., which improve the corrosion resistance by the above described mechanisms above 1050° C. The less reactive second phosphate is more unreactive in this temperature range (no early softening of the microstructure) and only undergoes modification changes (AlPO.sub.4: berlinite, cristobalite, tridymite) and densifies the microstructure at temperatures >1100° C.

[0126] In particular, phase transformations of the first phosphate with the Al.sub.2O.sub.3 grain, preferably the alumina, and/or the second phosphate, especially the AlPO.sub.4, lead to the improvement. At even higher temperatures (above the softening point of the calcium aluminate phosphate phases), the second phosphate, in particular the AlPO.sub.4, remains stable and additionally, due to the transformations and the increasing sintering/densification, increases the strengths. The two phosphates according to the invention thus complement one another depending on the temperature, alone, the properties would not be given for both. The first phosphate is reactive early, forms new phases and softens, while the second phosphate, in particular the AlPO.sub.4, serves as a reactant, undergoes modification changes and solidifies the microstructure at high temperatures.

[0127] As explained above, the batch according to the invention also comprises refractory aggregate. The refractory, non-basic aggregate forms the raw material basis of the dry substance mixture and/or the refractory concrete batch in a manner known per se.

[0128] In a manner known per se, the refractory aggregate comprises at least one refractory, non-basic, aggregate material. In addition, the aggregate has a grain size distribution typical for the production of a coarse ceramic refractory product. That is, the aggregate thus comprises a grain size distribution such that the coarse aggregate grains in the manufactured product form a support structure grains embedded in the binder matrix in a manner known per se.

[0129] That is, the aggregate preferably has both a fine-grain proportion or fine-grain fraction and a coarse-grain proportion or coarse-grain fraction. In this regard, both the fine grain proportion and the coarse grain proportion preferably comprise a continuous grain size distribution. The fine grain proportion also has a meal-grain proportion or a meal-grain fraction.

[0130] In the context of the present disclosure, fine grain proportion refers to all granular materials ≤1 mm and >200 μm. Accordingly, the coarse grain proportion has grain sizes >1 mm. In the context of the invention, the term meal-grain proportion refers to all granular materials ≤200 μm.

[0131] Preferably, the coarse grain proportion is 40 to 60 ma. %, based on the total amount of aggregate.

[0132] Preferably, the aggregate also has a maximum grain size ≤15 mm, preferably s 7 mm.

[0133] Preferably, the other aggregate materials of the aggregate also consist of raw materials rich in alumina, preferably with a content of at least 40 ma. % Al.sub.2O.sub.3, more preferably at least 80 ma. % Al.sub.2O.sub.3, very particularly preferably at least 90 ma. % Al.sub.2O.sub.3.

[0134] Thus, the refractory concrete batch according to the present disclosure preferably is an Al.sub.2O.sub.3—SiO.sub.2 product.

[0135] And the products according to the present disclosure are preferably products of the SiO.sub.2—Al.sub.2O.sub.3 series.

[0136] Preferably, the aggregate materials of the aggregate consist of alumina, preferably fused alumina, preferably white fused alumina, and/or calcined alumina, e.g. reactive alumina, and/or sintered alumina, preferably tabular alumina, and/or sintered bauxite. However, they may also consist, for example, of other raw materials rich in alumina, preferably spinel and/or mullite and/or fireclay.

[0137] Preferably, at least 80 ma. %, preferably 90 ma. %, preferably 100 ma. % of the aggregate consists of aggregate materials of alumina. This reduces the reaction potential with liquid aluminum and aluminum alloys.

[0138] Preferably, for this reason, the dry substance mixture also has an Al.sub.2O.sub.3 content of 60 to 92 ma. %, preferably 80 to 90 ma. %.

[0139] Consequently, the mealy Al.sub.2O.sub.3 granular material forms part of the mealy aggregate. And the total amount of mealy Al.sub.2O.sub.3 granular material is composed of the meal-grain proportion of all the aggregate materials consisting of a raw material rich in alumina with the minimum Al.sub.2O.sub.3 content mentioned above.

[0140] As already explained, the dry substance mixture also optionally has a dry binder, preferably in amounts of 0 to 20 ma. %, preferably 1 to 7 ma. %.

[0141] Dry binders are known to be present in granular form or as granular material. The dry binder is preferably a hydraulic binder, preferably calcium aluminate cement (CAC), and/or water glass and/or aluminum hydroxide binder and/or a geopolymer binder and/or a phosphate binder consisting of a water-soluble phosphate.

[0142] Unlike phosphate binders, the phosphates according to the invention, due to their at most moderate solubility, do not form a binding between room temperature and 800° C. They therefore do not shift the pH value of the mixture during mixing. No neutralization reactions with precipitation of new phases take place.

[0143] Calcium aluminate cement is particularly preferred for unshaped products, as it ensures good workability and controlled setting behavior. In particular, calcium aluminate cement provides good strength after 24 h after setting at room temperature.

[0144] As described above, the refractory concrete batch according to the invention also has at least one liquid binder in addition to the dry substance mixture, preferably in an amount of 4 to 12 ma. %, preferably 6 to 10 ma. %, based on the dry mass of the dry substance mixture. In addition thus means that the amount of liquid, enclosed binder is based on the dry mass of the dry substance mixture (see exemplary embodiments).

[0145] The liquid binder is preferably silica sol and/or alumina sol and/or an organic binder and/or a phosphate binder. Particularly preferably silica sol is used.

[0146] The liquid binders are enclosed in a container separate from the dry components of the batch.

[0147] The batch also preferably has a total binder content (active ingredient content) of 1 to 30 ma. %, preferably 1 to 15 ma. %, based on the total dry mass of the batch. In the case of the liquid binder, of course, only the active ingredient content is included if it is a suspension or the like.

[0148] The total dry mass of the batch or of the fresh batch mass produced therefrom is thus obtained from the sum of the dry batch components (=dry mass of the dry substance mixture) and, if applicable, the active ingredient content of the liquid batch components.

[0149] The batch according to one aspect of the present disclosure, in particular the dry substance mixture, may also contain at least one further additive (in addition to the two phosphates according to the invention). Additives improve, for example, the workability or formability or the corrosion resistance or modify the microstructure. The additives can be contained in the batch in mealy, dry form or, in addition to the dry substance mixture, in liquid form (enclosed). The maximum amount of additional additive(s) (active ingredient content) in the batch according to the invention, based on the dry mass of the batch, is preferably <10 ma. %, preferably <6 ma. %.

[0150] Preferably, the batch according to the invention, in particular the dry substance mixture, comprises at least one liquefier as an additive, in particular if the batch is a liquefied refractory concrete batch.

[0151] Furthermore, the batch according to another aspect of the present disclosure, in particular the dry substance mixture, preferably comprises at least one further, phosphate-free, anti-corrosion agent as an additive. Preferably, the batch comprises barium sulfate and/or a fluoride-containing anti-corrosion agent, preferably calcium fluoride and/or strontium fluoride and/or aluminum fluoride.

[0152] In addition to the aforementioned anti-wetting agents, at least one anti-corrosion agent from a stable calcium aluminate phase, such as CA, CA.sub.2 or CA.sub.6, may be contained.

[0153] In addition, the batch, in particular the dry substance mixture, may comprise at least one activator for the binder as an additive. For example, this may be mealy magnesia and/or a sulfate and/or powdered water glass. The activators serve in particular to shift the pH value.

[0154] The dry substance mixture may also contain fibers, in particular burn-out fibers, as an additive. Preferably, these are plastic fibers, preferably polypropylene fibers. The total amount of fibers in the dry substance mixture is thereby preferably <1 ma. %, preferably <0.5 ma. %. After burning out, channels are formed through which water vapor can escape in a manner known per se. The fibers thus provide a heating aid.

[0155] As already explained, shaped or unshaped products are produced from the coarse ceramic batch according to the invention in a manner known per se.

[0156] For the production of unshaped products, in particular of masses, preferably gunning masses or vibrating masses or casting masses or poking masses, a fresh batch mass is prepared from the dry and liquid components of the refractory batch. Since the batch contains a liquid binder, the addition of water is not necessary, but possible.

[0157] The fresh batch mass is processed in a manner known per se, e.g. by gunning or, particularly preferably, by casting.

[0158] The shaped products according to the invention are prefabricated components. In the production of the prefabricated components, the fresh batch mass prepared as described above is placed in a mold and, if applicable, compacted so that molded bodies are formed. If the batch contains a liquid binder and/or a liquid additive, the addition of water is not necessary, but possible. Thus, if applicable, only water is added, especially if a dry binder is contained in the dry substance mixture. In contrast to the production of the unshaped products from the refractory concrete batch according to the invention, the liquid batch components also do not have to be present in an enclosed form.

[0159] If applicable, depending on the binder used, drying is carried out after shaping, e.g. between 60 and 500° C., in particular between 90 and 450° C. Drying is preferably carried out to a residual moisture content of between 0.1 and 4 ma. %, in particular between 0.5 and 3 ma. %, determined in accordance with DIN 51078:2002-12.

[0160] The prefabricated components according to the invention, in particular the bricks, are used unfired or tempered.

[0161] Both the shaped prefabricated components as well as the unshaped products comprise excellent mechanical properties. Unless otherwise explained, the values given below are based on a standardized test of the products according to DIN EN ISO 1927-6:2013-04 after a standardized production of the test specimens with a heat treatment at 1100° C. according to DIN EN ISO 1927-5:2013-04:

[0162] The products according to the invention comprise a very good cold compressive strength according to DIN EN ISO 1927-6:2013-04 preferably of 50 to 90 MPa, in particular 60 to 75 MPa.

[0163] The cold bending strength according to DIN EN ISO 1927-6:2013-043 of the products according to the invention, is preferably 12 to 20 MPa, in particular from 15 to 18 MPa.

[0164] The products according to the present disclosure also preferably have an open porosity of 13 to 22 vol. %, especially 17 to 21 vol. %, determined according to DIN EN ISO 1927-6:2013-04. And/or they preferably comprise a raw density of 2.50 to 3.00 g/cm.sup.3, in particular of 2.8 to 2.95 g/cm.sup.3, determined according to DIN EN ISO 1927-6:2013-04.

[0165] The products according to the present disclosure also preferably have a modulus of elasticity of 50 to 80 GPa, in particular of 60 to 70 GPa, determined in accordance with DIN EN ISO 1927-6:2013-04.

[0166] All the aforementioned properties of the products according to the present disclosure and of the batch according to the invention are in each case individually and in any combination according to the invention. In addition, the respective upper and lower limits of the individual range specifications can all be combined with each other according to the invention.

[0167] In order to prove the mode of operation of the two phosphates according to the present disclosure in combination with the Al.sub.2O.sub.3 granular material, some comparative tests were carried out within the scope of the present disclosure. The following raw materials were used for the comparative tests:

TABLE-US-00002 TABLE 1 Raw materials used Tabular alumina (all Tabular Alumina T60 Almatis Co. grain groups) White fused alumina 0-0.2 mm White Fused Alumina 0-0.2 Bosai Co. Calcined alumina CT 9 G Almatis Co., d.sub.99 value = 63 μm Second phosphate (AlPO.sub.4) M 13-02 Budenheim Co. First phosphate (Ca(HPO.sub.4)) C 22-03 Budenheim Co., d.sub.50 value = 12 μm Liquefier Castament FS 20 BASF Co. PP fibre polypropylene cut, 20 μm, 6 mm Contrack Co. Silica sol LIQUIDBINDER NO. 1 CWK Co.

[0168] Among other things, comparative tests were carried out with the first phosphate and with the second phosphate, in combination with the calcined alumina respectively. The first phosphate and the calcined alumina were mixed together in a ratio of 1:3. The second phosphate and the calcined alumina were also mixed together in a ratio of 1:3. The mixtures respectively were subjected to temperatures of 800° C. and 1200° C. in a crucible. In addition, differential thermal analysis and X-ray diffraction analysis of the initial mixtures and the fired mixtures were carried out.

[0169] The result of the measurements are shown in FIGS. 1 and 2.

[0170] Among other things, it was found that the first phosphate initially starts to dehydrate at about 400° C. (FIG. 1). At 800° C., the Ca phosphate is present as dicalcium phosphate Ca.sub.2(P.sub.2O.sub.7), but already begins to react with the calcined alumina to form calcium aluminum phosphate Ca.sub.9Al(PO.sub.4).sub.7. At 1200° C. the reaction to calcium aluminum phosphate Ca.sub.9Al(PO.sub.4).sub.7 is complete.

[0171] The second phosphate (FIG. 2) undergoes only modification changes analogous to SiO.sub.2. At 800° C., both the quartz structure (berlinite) as well as the tridymite and cristobalite structures are present. At 1200° C., the aluminum phosphate (AlPO.sub.4) almost is only present in the cristobalite structure. The total amount of aluminum phosphate (AlPO.sub.4) appears to remain about the same. The calcined alumina does not undergo any significant changes (participates in the phosphate transformation, if applicable).

[0172] Thus, mainly the formation of calcium aluminate phosphate from dicalcium phosphate occurs in the presence of mealy Al.sub.2O.sub.3 at temperatures from 800 to 1000° C. At 1000° C., dicalcium phosphate phases are no longer detectable, the calcium aluminate phosphate phases are stable up to at least 1200° C. and serve to improve corrosion resistance. On the one hand, the AlPO.sub.4 serves as a reaction partner, yet it mainly undergoes modification changes. At 800° C. it is present in the berlinite, tridymite and cristobalite modification, at 1000° C. and 1200° C. still in the tridymite and cristobalite modification. These reactions lead to an increase in strength and a decrease in open porosity after prefire at 1200° C., this was also confirmed by an experiment with AlPO.sub.4 in a typical system without further phosphates (see below). At lower temperatures it shows no significant effect, one reason for the combination with the first phosphate.

[0173] Furthermore, the subsequent batch was used to investigate the densifying effect of pure aluminum phosphate (AlPO.sub.4):

TABLE-US-00003 TABLE 2 Batch composition for the determination of physical properties (grain groups) amount [ma.-%] Tabular alumina 2-5 mm 25.00 1-3 mm 20.00 0-1 mm 20.00 White fused alumina 0-0.02 mm   10.00 Alumina 22.00 Second phosphate (AlPO.sub.4) 3.00 Liquefier 0.10 PP fibre 0.05 Σ 100 Silica sol 7.5 (based on dry substance mixture)

[0174] The determination of cold flexural strength (CFS) and open porosity (OP) on the above mentioned batch was carried out after pre-firing at 1200° C. according to the respective standards mentioned above. The test specimens were also manufactured in accordance with the standard DIN EN ISO 1927-5:2013-04.

TABLE-US-00004 TABLE 3 Results of the determination of the physical properties CFS in MPa Open porosity in vol. % 18.00 17.00

[0175] In addition, further comparative tests were carried out with regard to corrosion resistance to molten aluminum.

[0176] For this purpose, crucibles were made from a batch with the following batch composition:

TABLE-US-00005 TABLE 4 batch composition (grain groups) for the crucible tests amount [ma. %] Tabular alumina 2-5 mm 25.00 1-3 mm 20.00 0-1 mm 20.00 White fused alumina 0-0.2 mm   10.00 Calcined alumina 16.85 AlPO.sub.4 3.00 Ca(HPO.sub.4) 5.00 Liqufier 0.10 PP fiber 0.05 Σ100 Silica sol 7.50

[0177] The crucibles were manufactured in accordance with the above standard and prefired at the respective test temperature with a holding time of 5 h.

[0178] It was found that a dense passivation or protective layer (FIG. 3) was formed in case of the crucibles exposed to 1000° C. This passivation layer also persisted in case of the crucibles exposed to 1200° C. (FIG. 4). No further infiltration took place.

[0179] In addition, further tests were carried out with three different batches V1 to V3 to document the change in softening behavior. The specimens were again manufactured according to DIN EN ISO 1927-5:2013-04, and the softening range was determined according to DIN EN ISO 1893: 2008-09. A table of the batch compositions and a table with the determined softening ranges are shown below:

TABLE-US-00006 TABLE 5 batch composition for tests V1 to V3 Raw material amount V1 V2 V3 Alumina [ma. %] 69.23 78.95 58.44 First phopsphate [ma. %] 30.77 0.00 25.97 Second phosphate [ma. %] 0.00 21.05 15.58 Silica sol (liquid) [ma. %] 51.08 58.25 43.12

TABLE-US-00007 TABLE 6 softening ranges for tests V1 to V3 sample softening range V1 1080° C. . . . 1247° C. V2 >1546° C. V3 1166° C. . . . 1342° C.

[0180] The results demonstrate that batch V1, which only contains pure calcium hydrogen phosphate, softens earlier and the phosphate combination according to the invention ensures a higher softening point.

[0181] The invention is not limited to the exemplary embodiments shown and described, but rather also comprises all embodiments which work the same way in the sense of the invention. It is emphasized that the exemplary embodiments are not limited to all features in combination, rather each individual partial feature can also have inventive significance in isolation from all other partial features. Furthermore, the invention is so far not yet limited to the combinations of features defined in any embodiment, but rather can also be defined by any other combination of specific features of all of the individual features disclosed. This means that in principle practically any individual feature of an embodiment can be removed or replaced by another individual feature disclosed elsewhere in the application. In other words, embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0182] The foregoing description of various forms of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications or variations are possible in light of the above teachings. The forms discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various forms and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.