Alumina-zirconia-silica refractory product

Abstract

The invention relates to a cast refractory product comprising, in mass percent on the basis of oxides and for a total of 100%: ZrO2 + HfO2: 39.0% to 55.0%, where HfO2lt; the component A comprises the following components in percentage by weight: 5% of SiO2, 10.5%-14.0% of Al2O3, 0.80%-3.00% of Na2O + K2O and 1t of B2O3, and the sum of the components is 100%; 1.0% of Fe2O3 + TiO2: lt; 0.60%, and other types: lt; a 1.0%-ratio (K2O / 1.52) / (Na2O + K2O / 1.52) of greater than 0.30, where Na2Olt; 0.60%, or the ratio (K2O / 1.52) / (Na2O + K2O / 1.52) is greater than 0.60.

Description

Technical Field

[0001] The present invention relates to an AZS (alumina-zirconia-silica) fused refractory product and also to a glass melting furnace comprising such a product. Background Art

[0002] Glass melting furnaces usually contain a very large number of refractory products, which are arranged in different locations according to their nature. For each part of the furnace, the product selected will be one that does not cause any defects that make the glass unusable (which would reduce the production yield) and has a resistance long enough to give the furnace a satisfactory service life.

[0003] Among refractory blocks, a distinction is made between fused blocks and sintered blocks.

[0004] Unlike sintered blocks, fused blocks usually contain intercrystalline glass phases connecting the crystallized grains. Therefore, the problems encountered by sintered blocks and fused blocks and the technical solutions adopted to solve these problems are usually different. Therefore, a composition developed for the production of sintered blocks cannot in principle be used as such to produce fused blocks, and vice versa.

[0005] A fused mass, usually called an "electrofused mass" or "fused cast mass", is obtained by melting a mixture of suitable starting materials in an electric arc furnace or by any other suitable technique. The molten material is then usually cast in a mould and then solidifies. Usually, the product obtained then undergoes a controlled cooling cycle to reach ambient temperature without cracking. This operation is called "annealing" by a person skilled in the art.

[0006] Alumina-zirconia-silica (AZS) fused products are known and mainly comprise aluminum oxide (Al 2 O 3 )、ZrO 2 ) and silicon dioxide (SiO 2 ). In particular, AZS products generally contain less than 80% by mass of zirconium oxide. AZS products also contain corundum (free or in the form of a corundum / zirconia eutectic) in an amount generally greater than 10% or even greater than 30%.

[0007] AZS products usually contain sodium oxide Na 2 O, in order to give the glass phase suitable physical and chemical properties. 2 O and Na 2 O is considered to have equivalent effect.

[0008] US 2 438 552 proposes adding sodium oxide (1.0% to 2.2%) and a total MgO+CaO content between 0.2% and 0.8% to cope with the presence of 9% to 12% SiO 2 and feasibility issues associated with AZS products with iron oxide content between 0.4% and 1.7%.

[0009] EP 939 065 proposes to add B 2 O 3 , P 2 O 5 , and group SnO 2 , ZnO, CuO and MnO 2 At least one oxide to reduce the content of ZrO from 20% to 59% 2 and 5% to 12% SiO 2 The degree of exudation of AZS products.

[0010] WO 2011 / 161588 proposes to remove Al 2 O 3 It also contains 30% to 50% ZrO 2 8% to 16% SiO 2 , Y 2 O 3 , and more than 0.2% Na 2 O+K 2 O+B 2 O 3 Anti-exudation AZS products.

[0011] One of the factors limiting the life of a glass melting furnace is the loss of blocks, in particular blocks constituting the side walls of the vessel. Monitoring the residual thickness of the fused blocks of a furnace in use is difficult, in particular due to the temperature of its environment. Methods for monitoring the blocks have been developed. In particular, methods using electromagnetic waves, in particular radar waves ("radar-based sensors" (TOF)) are known. However, the application of these methods is limited to cases where the residual thickness is small.

[0012] Therefore, there is a need to continuously improve these methods. Summary of the invention

[0013] Summary of the Invention

[0014] The present invention provides a fused-cast refractory product, which, in percentages by mass based on oxides and totaling 100%, comprises:

[0015]

[0016] -Ratio(K 2 O / 1.52) / (Na2 O+K 2 O / 1.52) is greater than 0.30, of which Na 2 O < 0.60%, or

[0017] -Ratio(K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is greater than 0.60.

[0018] As will be seen in more detail later in the specification, the inventors did not seek to improve the apparatus used for monitoring, but rather to improve the quality of the response of the mass so monitored. The inventors unexpectedly discovered that Na 2 O and K 2 O has different effects on the ability of radar waves to penetrate blocks made of the product according to the invention. Furthermore, the inventors have found that within the content range determined by several criteria, in particular by the ratio (K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52), Na 2 O and K 2 O not only improves the ability of radar waves to penetrate blocks, but also maintains feasibility.

[0019] Thus, monitoring can be performed to greater depths, preferably throughout the entire thickness of the block.

[0020] The product according to the invention is therefore perfectly suitable for monitoring its residual thickness.

[0021] The product according to the invention may also include one or more of the following optional features, when they comply with the specific embodiments described below and when these optional features are compatible with the specific embodiments described below:

[0022] - the total porosity of the product is less than 10%, or even less than 5%;

[0023] - preferably, the oxides represent more than 90%, more than 95%, more than 99%, or even substantially 100% of the mass of the product;

[0024] -ZrO 2 +HfO 2% or even less than 42.0%, or even more than 43.0%, or even more than 43.5%, or even more than 44.0%, or even more than 44.5%, or even more than 45.0%, or even more than 45.5%;

[0025] -SiO 2 A mass content of less than 13.8%, or even less than 13.6%, or even less than 13.5%, or even less than 13.4%, or even less than 13.3%, or even less than 13.2%, or even less than 13.0%, or even less than 12.7%, or even less than 12.5%, and / or preferably greater than 10.6%, or even greater than 10.7%, or even greater than 10.8%, or even greater than 10.9%, or even greater than 11.0%, or even greater than 11.3%, or even greater than 11.5%;

[0026] -Al 2 O 3 The mass content is less than 46.0%, or even less than 45.5%, or even less than 45.0%, or even less than 44.0%, or even less than 43.5%, or even less than 43.0%, or even less than 42.0%, and / or greater than 29.0%, or even greater than 30.0%, or even greater than 32.0%, or even greater than 34.0%, or even greater than 36.0%;

[0027] -Sodium oxide Na 2 O and potassium oxide K 2 The sum of the mass contents of O is preferably greater than 0.85%, greater than 0.90%, greater than 0.95%, greater than 1.00%, and / or preferably less than 2.90%, preferably less than 2.80%, preferably less than 2.70%, preferably less than 2.60%, less than 2.50%, even less than 2.30%, even less than 2.20%, even less than 2.10%, even less than 2.00%, even less than 1.90%;

[0028] -Na 2The mass content of O is preferably less than 1.50%, or even less than 1.40%, or even less than 1.30%, or even less than 1.20%, or even less than 1.00%, or even less than 0.80%, or even less than 0.75%, or even less than 0.60%, or even less than 0.55%, or even less than 0.50%, or even less than 0.40%, less than 0.30%, less than 0.20%, or less than 0.10%; in one embodiment, Na 2 O exists as an impurity;

[0029] -K 2 The mass content of O is preferably less than 2.50%, or even less than 2.00%, or even less than 1.90%, or even less than 1.80%, or even less than 1.70%, or even less than 1.60%, or even less than 1.50%, and / or greater than 0.60%, greater than 0.65%, or even greater than 0.70%, or even greater than 0.75%, or even greater than 0.80%, or even greater than 1.00%;

[0030] -Ratio(K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is greater than 0.40, or even greater than 0.45, or even greater than 0.50, or even greater than 0.60, or even greater than 0.62, or even greater than 0.65, or even greater than 0.70, or even greater than 0.75, or even greater than 0.80, and / or less than 0.95, or even less than 0.90;

[0031] -B 2 O 3 As an impurity, and / or boron oxide B 2 O 3 The mass content of is less than 0.90%, preferably less than 0.80%, preferably less than 0.70%, preferably less than 0.60%, preferably less than 0.50%, less than 0.40%, or even less than 0.30%, or even less than 0.20%, or even less than 0.10%;

[0032] -Y 2 O 3 The mass content of is less than 0.80%, or even less than 0.60%, or even less than 0.50%, or even less than 0.40%, or even less than 0.30%, or even less than 0.20%;

[0033] -Iron oxide and titanium oxide Fe 2 O 3 +TiO 2 The sum of the mass contents of is less than 0.40%, preferably less than 0.30%, more preferably less than 0.20%;

[0034] - The total mass content of "other substances" is less than 0.9%, or even less than 0.8%, or even less than 0.6%, or even less than 0.5%, or even less than 0.4%;

[0035] - "other substances", i.e., substances other than ZrO 2 , HfO 2 、SiO 2 、Al 2 O 3 、Na 2 O.K 2 O.B 2 O 3 , Fe 2 O 3 and TiO 2 , consisting only of impurities;

[0036] - Any "other substances", especially Ta 2 O 5 and / or Nb 2 O 5 The mass content is less than 0.4%, or even less than 0.3%, or even less than 0.2%, or less than 0.1%;

[0037] The sum of the mass contents of calcium oxide CaO, barium oxide BaO, strontium oxide SrO and magnesium oxide MgO is less than 0.6%, less than 0.5%, less than 0.4%, or even less than 0.3%;

[0038] - The mass content of CaO is less than 0.4%, or even less than 0.3%;

[0039] - the mass content of BaO is less than 0.4%, or even less than 0.3%;

[0040] - The mass content of SrO is less than 0.4%, or even less than 0.3%;

[0041] - The mass content of MgO is less than 0.4%, or even less than 0.3%;

[0042] -The product is in the form of blocks.

[0043] According to a particularly advantageous embodiment, the fused-cast refractory product according to the invention comprises, in percentages by mass based on oxides:

[0044]

[0045] Ratio (K 2 O / 1.52) / (Na 2 O+K 2O / 1.52) is greater than 0.60, or even greater than 0.65.

[0046] According to a particularly advantageous embodiment, the fused-cast refractory product according to the invention comprises, in percentages by mass based on oxides:

[0047] ZrO 2 +HfO 2 : 39.0% to 51.0%, preferably 39.0% to 49.5%, preferably 42.5% to 49.5%

[0048]

[0049] Ratio (K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is greater than 0.65, or even greater than 0.70.

[0050] According to a particularly advantageous embodiment, the fused-cast refractory product according to the invention comprises, in percentages by mass based on oxides:

[0051]

[0052] Ratio (K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is greater than 0.62, preferably greater than 0.65, preferably greater than 0.70.

[0053] According to a particular embodiment, the fused-cast refractory product according to the invention comprises, in percentages by mass based on oxides:

[0054]

[0055]

[0056] Ratio (K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is greater than 0.60, or even greater than 0.65.

[0057] According to a particular embodiment, the fused-cast refractory product according to the invention comprises, in percentages by mass based on oxides:

[0058]

[0059] Ratio (K 2 O / 1.52) / (Na 2 O+K 2O / 1.52) is greater than 0.50.

[0060] According to a particular embodiment, the fused-cast refractory product according to the invention comprises, in percentages by mass based on oxides:

[0061]

[0062] Ratio (K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is greater than 0.60.

[0063] According to a particular embodiment, the fused-cast refractory product according to the invention comprises, in percentages by mass based on oxides:

[0064]

[0065]

[0066] Ratio (K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is preferably greater than 0.60, preferably greater than 0.62, or even greater than 0.65, 0.70 or 0.75.

[0067] In a particular embodiment, the fused-cast refractory product according to the invention comprises, in percentage by mass based on oxides:

[0068]

[0069] Ratio (K 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is greater than 0.65.

[0070] The above-mentioned optional features may be combined if they are not technically incompatible with each other.

[0071] The invention also relates to a method for manufacturing a refractory product according to the invention, comprising the following steps carried out in sequence:

[0072] a) mixing the starting materials to form a feed,

[0073] b) melting the feed material until a molten material is obtained,

[0074] c) casting the molten material and solidifying the molten material by cooling to obtain a refractory product,

[0075] Of note with this method is the selection of the starting materials such that the refractory product complies with the invention.

[0076] Preferably, the oxides or precursors of these oxides which require the lowest content are added systematically and methodically. Preferably, the content of these oxides in the source of other oxides in which they are present as impurities is taken into account.

[0077] Preferably, cooling is controlled, preferably so as to occur at a rate of less than 20°C per hour, preferably at a rate of about 10°C per hour.

[0078] The invention also relates to a glass melting furnace comprising a refractory product according to the invention, or a refractory product manufactured or capable of being manufactured by a method according to the invention, in particular in an area intended to come into contact with molten glass, in particular in a vessel of a glass melting furnace, in particular constituting an electrode holder block, for example in the furnace floor of such a vessel.

[0079] The invention thus relates to a glass melting furnace comprising a container intended to contain molten glass or a container containing molten glass, the container comprising a block made from the product according to the invention.

[0080] Finally, the present invention relates to a method for monitoring a glass melting furnace according to the present invention, said method comprising the following operations:

[0081] - applying electromagnetic waves, preferably radar-type waves, with a frequency preferably between 1 GHz and 10 GHz, or even between 1 GHz and 6 GHz, to the blocks of the refractory product according to the invention;

[0082] - Analyzing the signal received in response to the application to determine information related to changes in the mass or medium, in particular information reflecting the interface between the mass and the medium.

[0083] In one embodiment, the application of electromagnetic waves is performed while the furnace is operating, with the block optionally in contact with molten glass.

[0084] Applying electromagnetic waves and analyzing can be performed by any known technique, such as using the method proposed by PaneraTech device.

[0085] definition

[0086] In general, a product is referred to as "molten" when it is obtained by a process of melting a feed material until a molten material is obtained, and then solidifying the material by cooling.

[0087] A block is an object whose dimensions are all greater than 10 mm. All dimensions of a block according to the invention are preferably greater than 50 mm, preferably greater than 100 mm. A block according to the invention may, for example, have the shape of a general parallelepiped or a specific shape adapted to its use. Unlike layers, blocks made of fused-cast refractory products are generally obtained by a process comprising molding and demoulding operations.

[0088] A block of the product according to the invention may have, before or after trimming / processing, one, or even two or three external dimensions (thickness, length or width) of at least 150 mm, preferably at least 250 mm, or even at least 400 mm, or even at least 500 mm, or even at least 600 mm, or even at least 800 mm, or even at least 1000 mm, and / or less than 2000 mm.

[0089] Unless otherwise stated, all oxide contents in the products according to the invention are based on the mass percentage of the oxide. According to standard industrial practice, the mass content of oxides of metal elements refers to the total content of the element expressed in the most stable oxide form.

[0090] HkDJ 2 Cannot be used with ZrO 2 Chemical separation. However, according to the present invention, HfO 2 is not intentionally added to the feed. Therefore, HfO 2 It represents only trace amounts of hafnium oxide, which is always naturally present in zirconium oxide sources in a content of generally less than 5%, more generally less than 2%. In the block according to the invention, HfO 2 The mass content of ZrO is less than 5%, preferably less than 3%, and more preferably less than 2%. 2 ” or “ZrO 2 +HfO 2 ” represents the total content of zirconium oxide and trace amounts of hafnium oxide. Therefore, HfO 2 Not included in “other substances”.

[0091] The term "impurity" refers to unavoidable components introduced with the starting materials or resulting from reactions with these components. Impurities are not essential components but merely acceptable components. For example, compounds constituting the group of oxides, nitrides, oxynitrides, carbides, oxycarbides, carbonitrides and metallic species of iron, titanium, vanadium and chromium are impurities.

[0092] Total porosity is expressed as a percentage and is generally equal to 100 x (1 - geometric density divided by absolute density).

[0093] Geometric density is measured according to standard ISO 5016:1997 or EN 1094-4 in g / cm 3 Typically, it is equal to the mass of the sample divided by the bulk volume.

[0094] The absolute density is expressed in g / cm 3 Porosity can be measured by dividing the mass of a sample by the volume of the sample, which has been ground to essentially eliminate porosity. DETAILED DESCRIPTION

[0095] In the molten-cast product according to the invention, ZrO 2 +HfO 2 A content of 20% allows to meet the requirements of high corrosion resistance. On the other hand, too high a content is not conducive to the industrial feasibility of the block.

[0096] The hafnium oxide HfO present in the product according to the invention 2 Preferably, it is naturally present in ZrO 2 Its content in the product according to the invention is therefore less than 4%, generally less than 2%, or even less than 1%.

[0097] SiO 2 The presence of SiO in particular allows the formation of an intercrystalline glass phase which contributes to the viability of the product due to its ability to effectively accommodate temperature deformations. 2 mass content to limit the amount of glassy phase.

[0098] Na 2 O+K 2 The presence of O contributes to the viability of the product. It is preferred to limit Na 2 O+K 2 The mass content of O is adjusted to limit the amount of glass phase and to maintain, in particular, good corrosion resistance to molten glass and good wave propagation.

[0099] In order to have a ratio (K greater than 0.30, or even greater than 0.40, or even greater than 0.50, or even greater than 0.60, or even greater than 0.62, or even greater than 0.65 2 O / 1.52) / (Na 2 O+K 2 O / 1.52), and to allow good wave penetration into the block, K 2 The presence of O is required.

[0100] Na 2 O has an adverse effect on the good penetration of waves into the bulk. Therefore, sodium oxide Na 2 The mass content of O must be kept within limits.

[0101] B 2 O 3 Therefore, the boron oxide B 2 O 3 The quality content must be kept within the limit.

[0102] Y 2 O 3 will have an adverse effect on feasibility. Therefore, Y 2 O 3 The quality content must be kept within the limit.

[0103] According to the present invention, Fe 2 O 3 +TiO 2 The mass content of P is less than 0.60%, preferably less than 0.50%, more preferably less than 0.30%. 2 O 5 The mass content is less than 0.05%. In particular, these oxides are harmful, especially for the exudation of refractory products or the coloring of glass, and their content must be limited to trace amounts introduced as impurities with the starting materials.

[0104] “Other substances” are oxide substances not listed above, i.e., substances other than ZrO 2 , HfO 2 、SiO 2 、Al 2 O 3 、Na 2 O.K 2 O.B 2 O 3 , Y 2 O 3 、TiO 2 and Fe 2 O 3 In one embodiment, "other substances" are limited to substances whose presence is not particularly desired and which are typically present as impurities in the starting materials.

[0105] Preferably, the product according to the invention is in the form of blocks, preferably in the form of at least one, preferably at least two, or even all blocks having an outer dimension greater than 150 mm.

[0106] The total porosity of the product according to the invention is less than 15%, or even less than 10%, or even less than 5%, or even less than 2%, or even less than 1%.

[0107] The product according to the present invention can be conventionally manufactured according to the following steps a) to c):

[0108] a) mixing the starting materials to form a feed,

[0109] b) melting the feed material until a molten material is obtained,

[0110] c) solidifying the molten material by cooling to obtain a refractory product according to the invention.

[0111] In step a), the starting materials are chosen so as to ensure the oxide content in the final product obtained at the end of step c). A person skilled in the art knows perfectly well how to choose the starting materials for this purpose.

[0112] In step b), the melting is preferably carried out by means of a combination of a relatively long electric arc which does not produce any reduction and stirring which promotes reoxidation of the product.

[0113] For the intended application, melting is preferably carried out under oxidizing conditions.

[0114] Preferably, the long arc melting process described in French Patent No. 1 208 577 and its supplements Nos. 75893 and 82310 is used.

[0115] The process consists in using an electric arc furnace in which an arc is struck between a charge and at least one electrode spaced apart from said charge, and in adjusting the arc length so as to minimize its reducing effect while maintaining an oxidizing atmosphere above the molten bath and stirring said bath, for example by the action of the arc itself.

[0116] In step c), cooling is preferably carried out at a rate of less than 20°C / hour, preferably at a rate of about 10°C / hour, preferably in a mould having the desired dimensions, taking into account the feeding and possible processing after step c).

[0117] Any conventional method for the manufacture of molten zirconia-based products intended for application in glass melting furnaces may be used, provided that the composition of the starting feedstock is such that a product having a composition corresponding to that of the product according to the invention can be obtained.

[0118] Example

[0119] The following non-limiting examples are given for the purpose of illustrating the present invention.

[0120] In these examples, the following starting materials were used:

[0121] -Contains an average of 99% ZrO 2 +HfO 2 Zirconia Q1,

[0122] -Contains an average of 99% SiO 2 "Sable BE01 Bédouin" silica,

[0123] - Average Al content: 99% 2 O 3 AC34 alumina,

[0124] - As Na 2 O source contains an average of 99.5% Na 2 CO 3 of sodium carbonate,

[0125] -As K 2 O source contains an average of 99.5% K 2 CO 3 of potassium carbonate.

[0126] The product was prepared by a conventional arc furnace melting process and then cast in a mold to obtain blocks with minimum dimensions of 150 mm x 250 mm x 500 mm after trimming.

[0127] Chemical analysis

[0128] The average chemical analysis of the resulting products is given in Table 1; this is the chemical analysis of the liquid feed poured into the mould, given in mass percentages.

[0129] Different from ZrO 2 , HfO 2 、SiO 2 、Al 2 O 3 , B 2 O 3 、Na 2 O and K 2 O substances (especially Fe 2 O 3 、TiO 2 and Y 2 O 3 (may exist)) is an impurity, among which Y 2 O 3 <0.2% and Fe 2 O 3 +TiO 2 <0.3%.

[0130] In Table 1, HfO 2 The content of is always less than 4%. 2 O / 1.52) / (Na 2 O+K 2 O / 1.52) is called the "Ratio".

[0131] feasibility

[0132] The external state of the obtained products is observed. Their dimensions (three dimensions greater than 150 mm and at least one dimension of at least 400 mm) make it possible to assess industrial feasibility. If there are through cracks, the feasibility is judged to be unsatisfactory. The product is then cut in half to observe the filling. If incorrect filling occurs, the feasibility is considered unsatisfactory. Otherwise, the feasibility is considered satisfactory. All embodiments in the present invention have satisfactory feasibility.

[0133] Measurement of wave propagation

[0134] In various examples of the blocks produced, a cylindrical product rod of approximately 4 mm in diameter and 13 mm in height was penetrated by a 2.4 GHz wave at 1000° C. (this temperature corresponds to the temperature close to the outer surface of the container block). The received signal is studied to evaluate the depth at which the wave loses half its power (half-power depth: HPD); it is then divided by the value obtained for the reference (Example 1*) and multiplied by 100, obtaining the index P of wave propagation.

[0135] [Table 1]

[0136]

[0137] * indicates "outside the present invention".

[0138] It can be seen that when the ratio increases, the P index increases. The amount of potassium oxide in the product increases relative to the amount of sodium oxide, so that when Na 2 When the O content is less than 0.60%, the ratio is greater than 0.30, or when the ratio is greater than 0.60, this can promote the penetration of waves into the refractory product, thereby improving the monitoring quality without any deterioration in feasibility.

[0139] It is evident that the present invention thus provides a product having remarkable properties in the environment of the vessel of a glass melting furnace.

[0140] It goes without saying that the invention is not limited to the embodiments described and shown, which are provided for illustrative purposes only.

Claims

1. A fused-cast refractory product, based on the mass percentage of oxides and totaling 100%, comprising: - Ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.30, Wherein, Na 2 O < 0.60%, or - Ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.

60.

2. The product according to the previous claim, Wherein, The ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.

40.

3. The product according to the immediately preceding claim, Wherein, The ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.

50.

4. The product according to the immediately preceding claim, Wherein, The ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.

60.

5. The product according to the immediately preceding claim, Wherein, The ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.

62.

6. The product according to the immediately preceding claim, Wherein, The ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.

65.

7. The product according to any one of the preceding claims, Wherein, The ZrO 2 + HfO 2 has a mass content greater than 42.5%.

8. The product according to the immediately preceding claim, Wherein, The ZrO 2 + HfO 2 has a mass content greater than 43.5%.

9. The product according to the immediately preceding claim, Wherein, The ZrO 2 + HfO 2 has a mass content greater than 44.5%.

10. The product according to any one of the preceding claims, Wherein, The ZrO 2 + HfO 2 has a mass content of less than 52.5%.

11. The product according to the immediately preceding claim, Wherein, The ZrO 2 + HfO 2 has a mass content of less than 51.0%.

12. The product according to the immediately preceding claim, Wherein, The ZrO 2 + HfO 2 has a mass content of less than 49.5%.

13. The product according to the immediately preceding claim, Wherein, The ZrO 2 + HfO 2 has a mass content of less than 48.0%.

14. The product according to any one of the preceding claims, Wherein, The mass content of the SiO 2 is less than 13.5%.

15. The product according to the immediately preceding claim, Wherein, The mass content of the SiO 2 is less than 13.0%.

16. The product according to any one of the preceding claims, Wherein, The mass content of the SiO 2 is greater than 11.0%.

17. The product according to any one of the preceding claims, Wherein, The Na 2 has a mass content of less than 0.60%.

18. The product according to the immediately preceding claim, Wherein, The mass content of the described Na 2 O is less than 0.55%.

19. The product according to the immediately preceding claim, Wherein, The mass content of said Na 2 O is less than 0.50%.

20. The product according to any one of the preceding claims, Wherein, Based on the mass percentage of oxides: Na 2 O + K 2 O: 0.80% to 2.50%, preferably 0.80% to 2.00% Na 2 O: <0.60%, preferably <0.55% Among them, the ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.60, preferably greater than 0.62, or even greater than 0.

65.

21. The product according to any one of the preceding claims, Wherein, The described K 2 The mass content of O is greater than 0.60% and less than 2.00%.

22. The product according to any one of the preceding claims, Wherein, The K 2 has a mass content greater than 0.70%.

23. The product according to the immediately preceding claim, Wherein, The K 2 has a mass content greater than 0.80%.

24. The product according to the immediately preceding claim, Wherein, The said K 2 has a mass content of O greater than 1.00%.

25. The product according to any one of the preceding claims, Wherein, The K 2 has a mass content of less than 1.80%.

26. The product according to any one of the preceding claims, Wherein, The Na 2 O + K 2 The mass content of O is less than 2.50%.

27. The product according to the immediately preceding claim, Wherein, The Na 2 O + K 2 has a mass content of less than 2.00%.

28. The product according to any one of the preceding claims, Wherein, The mass content of said Al 2 O 3 is less than 44.0% and greater than 30.0%.

29. A fused-cast refractory product, based on the mass percentage of oxides and totaling 100%, comprising: ZrO 2 + HfO 2 : 39.0% to 51.0%, preferably 39.0% to 49.5%, more preferably 42.5% to 49.5% Other substances: <1.0% Wherein, Ratio (K 2 O / 1.52) / (Na 2 O + K 2 O / 1.52) is greater than 0.65, or even greater than 0.

70.

30. A glass melting furnace, which includes a container for containing molten glass or a container for containing molten glass, and the container includes a block made of the product according to any one of the preceding claims.

31. A method for monitoring a glass melting furnace, the method comprising the following operations: - Applying an electromagnetic wave to a block of refractory material according to any one of claims 1 to 29; - Analyzing the signal received in response to the application to determine information related to the change of the block or medium, in particular information reflecting the interface.

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