WO2013175436A1

WO2013175436A1 - Unshaped refractory mixture

Info

Publication number: WO2013175436A1
Application number: PCT/IB2013/054295
Authority: WO
Inventors: Olivier PANAGIOTIS; Ludovic LECOCQ
Original assignee: Saint-Gobain Centre De Recherches Et D'etudes Europeen
Priority date: 2012-05-25
Filing date: 2013-05-24
Publication date: 2013-11-28
Also published as: FR2990940A1; FR2990940B1

Abstract

An unshaped refractory mixture consisting of: - a coarse fraction consisting of particles having a size greater than 100 µm, and - a fraction complementary to the coarse fraction, consisting of - a fine fraction consisting of particles having a size less than or equal to 100 µm and representing more than 1% of the weight of the unshaped refractory mixture after calcination, and - optionally a liquid phase, wherein the coarse fraction comprises more than 90% by weight of refractory particles, wherein the fraction complementary to the coarse fraction comprises, as percentage by weight on the basis of the complementary fraction after calcination and for a total of 100%, - more than 50% of silicon carbide and/or of silicon nitride and/or of silicon oxinitride, and less than 15% of other compounds of silicon, or "SiO₂", - between 0.5% and 15% of B₂O₃,- between 0.6% and 10% of Na₂O, - less than 48.9% of ZrO₂, - less than 10% of P₂O₅, - less than 4.8% of Al₂O₃, - less than 5% of CaO, - less than 5% of other species.

Description

Unshaped refractory mixture

Technical area

The invention relates to an unshaped refractory mixture, in particular for forming a mortar for grouting refractory blocks or a coating, in particular a coating for protecting a wall or a repair paste, in particular in a metallurgical furnace. The invention also relates to a hardened or even sintered mortar obtained from such an unshaped refractory mixture, as well as to an oven, in particular a copper remelting furnace, having a refractory coating that is grouted or protected or repaired by means of of such a hardened mortar. Technological background

Copper reflow furnaces are furnaces in which copper (or "cathode"), generally in the form of plates, is remelted so that it can be converted, for example, into ingots, bars or wires, in particular to produce the electric cables. Such furnaces are described for example in US 3 199 977, US 4 309 170, FR 2 483 957, or US 4 536 152.

The refractory wall of such an oven can be made by an assembly of refractory blocks, for example in the form of bricks.

The blocks consisting of an SiC-based aggregate bonded with an oxide matrix of silica (SiO ₂ ) or nitride (S 1 ₃ N ₄ ) or oxynitride (mainly of the Si ₂ ON _{2 type} ) type are particularly well suited. They are traditionally assembled through a joint consisting of grouting mortar.

A protective coating can be applied to the inner surface of the refractory wall, up to an average thickness of 2 mm. Such a coating is particularly useful for providing protection when starting the oven.

Finally, the refractory wall or the protective coating may degrade locally, leading to the appearance of cracks or holes, for example. Repairs can then be made by filling said cracks or holes with a repair paste.

In an application relating to a copper remelting furnace, the activated mortar used to form the joints or the protective coating or the repair paste must have the following properties: - ease of implementation,

- adapted rheology,

good adhesion to the blocks, in particular based on SiC,

- fast curing,

- mechanical strength allowing stable and solid stacking, before sintering in situ by starting the oven.

After sintering, the cured mortar must have the following properties:

abrasion resistance in order to withstand the stresses associated with the loading of copper,

- resistance to corrosion by molten copper,

dimensional stability and resistance to oxidation, especially during the start-up phase.

In addition, these properties must be adapted to the area of the oven concerned:

In the loading zone, typically the upper part of the furnace, special interest is attached to the resistance to abrasion and impact due to the stacking and displacement of the copper plates.

In the combustion zone, in the vicinity of the burners, special attention is given to resistance to infiltration, corrosion by molten copper, oxidation by the gases of the burners, such as C0 ₂ , O ₂ , CO and water vapor, and resistance to erosion by hot gases coming out at high speed from the burners.

In the intermediate zone, conventionally the lower part of the furnace, particular interest is attached to the resistance to oxidation and corrosion by copper, this zone comprising the triple interface formed by the refractory wall, the molten copper bath and the oxidizing atmosphere.

The unshaped refractory mixture is therefore conventionally adapted according to the zone for which it is intended.

The degradation of the joints leads to premature wear of the refractory wall, in particular because it increases the contact area between the blocks and the copper and / or the oxidizing gases inside the furnace. This degradation may in particular make it possible to attack, by the molten copper or hot gases, the insulating back layer, or even the corrosion of the outer metal coating of the furnace. There is therefore a permanent need for an unshaped refractory mixture to increase the life of the refractory walls of reflow furnaces. An object of the invention is to satisfy, at least partially, this need.

Summary of the invention

According to the invention, this object is achieved by means of an unshaped refractory mixture consisting of:

a coarse fraction consisting of particles having a size greater than 100 μιη, and

a fraction complementary to the coarse fraction consisting of

a fine fraction consisting of particles having a size of less than or equal to 100 μιη and representing more than 1% and, preferably, less than 70% of the mass of the unshaped refractory mixture after calcination, and

optionally a liquid phase,

the coarse fraction comprising more than 90% by mass of refractory particles, the fraction complementary to the coarse fraction comprising, as a percentage by weight on the basis of the complementary fraction after calcination, and for a total of 100%,

more than 50%) of silicon carbide and / or of silicon nitride and / or of silicon oxynitride, the silicon oxynitride being preferably in the Si ₂ ON _{2 form} , and less than 15% and preferably more preferably 0.5%> other silicon compounds (which excludes metallic silicon), or "Si0 ₂ ",

between 0.5% and 15% of B ₂ 0 ₃ ,

between 0.6% and 10% of Na ₂ O,

less than 48.9% of Zr0 ₂ ,

less than 10% of P ₂ 0 ₅ ,

- less than 4.8% of Al ₂ 0 ₃ ,

- less than 5% CaO,

- less than 5% of other species.

As will be seen in more detail in the following description, a refractory material obtained by activation, hardening and then sintering an unshaped refractory mixture according to the invention is well suited to application to a metal melting furnace, in particular particular copper. In addition, its qualities allow it to be used indifferently in the loading zone, the combustion zone or the intermediate zone of a shaft furnace, more particularly for the reflow of copper cathodes.

An unshaped refractory mixture according to the invention may also include one or more of the following optional features:

The unshaped refractory mixture comprises more than 70% SiC, in weight percent based on the unshaped refractory mixture after calcination.

The fraction complementary to the coarse fraction represents less than 35% of the mass of the unshaped refractory mixture.

- The fraction complementary to the coarse fraction comprises, in mass percentage on the basis of the complementary fraction after calcination,

more than 55.0%) and less than 90.0% of silicon carbide and / or silicon nitride and / or silicon oxynitride, the silicon oxynitride being preferably in the Si ₂ ON _{2 form} , preferably SiC, and / or more than 1.0% and less than 10.0% SiO ₂ , and / or

more than 1.5% and less than 8.0%> of B ₂ 0 ₃ , and / or

more than 1.0% and less than 4.5%, Al ₂ 0 ₃ , and / or

more than 1.0%, and less than 7.5% Na ₂ 0, and / or

more than 0.1%) and less than 9.0% of P ₂ 0 ₅ , and / or

more than 5.0%) and less than 20.0% of Zr0 ₂ , and / or

more than 0.05%) and less than 5.0% CaO.

more than 65.0%) and less than 80.0% of silicon carbide and / or silicon nitride and / or silicon oxynitride, the silicon oxynitride being preferably in the Si ₂ ON _{2 form} of SiC preference, and / or more than 2.0%) and less than 7.0% SiO ₂ , and / or

less than 5.0% of B ₂ 0 ₃ , and / or

- more than 2.0% and less than 4.0% Al ₂ 0 ₃ , and / or

more than 1.5% and less than 5.0% Na ₂ 0, and / or

more than 2.0%) and less than 8.0% of P ₂ 0 ₅ , and / or more than 7.0% and less than 15.0% of Zr0 ₂ and / or

more than 0.05%), preferably more than 0.5%, and less than 2.0% CaO. The fraction complementary to the coarse fraction comprises, in weight percentage on the basis of the complementary fraction after calcination,

more than 70.0% o and less than 80.0%> of silicon carbide and / or silicon nitride and / or silicon oxynitride, the silicon oxynitride being preferably in the Si ₂ ON _{2 form} , preferably SiC, and / or more than 3.0%) and less than 5.0%> SiO ₂ , and / or

less than 4.5% of B ₂ 0 ₃ , and / or

- more than 3,0% Al ₂ 0 ₃ , and / or

less than 3.0%> of Na ₂ 0, and / or

more than 1.5% and less than 5.5% of P ₂ 0 ₅ , and / or

less than 12,0% of Zr0 ₂ and / or

more than 0.05%), preferably more than 0.5% and less than 2.0% CaO. The fraction complementary to the coarse fraction comprises, in weight percentage on the basis of the complementary fraction after calcination,

- more than 60% of SiC, and / or

- more than 4.0% of Si0 ₂ , and / or

less than 3.8% of B ₂ 0 ₃ .

The fraction complementary to the coarse fraction has a composition such that, for a total of more than 98%, as a percentage on the basis of the complementary fraction after calcination:

- SiC and / or Si ₃ N ₄ and / or Si ₂ ON ₂ 61.1-85.0%

- Si0 ₂ : 3.0 - 5.0%

- B ₂ 0 ₃ : 1.0 - 5.0%

- A1 ₂ 0 ₃ : 0 - 4.8%

- Na ₂ 0: 1.0 - 3.0%

- P ₂ 0 ₅ : 2.0 - 3.0%

- Zr0 ₂ : 5.0 - 15.0%

- CaO: 0.05 - 3.1%. The invention also relates to a mortar obtained by activating an unshaped refractory mixture according to the invention, or "activated mortar", a hardened refractory material obtained by curing an activated mortar according to the invention, or "hardened mortar". and a sintered refractory material obtained by sintering a hardened mortar according to the invention, or "sintered mortar".

The inventors have observed that the joints formed with the mortars currently used could have, after the start-up phase under strongly oxidizing conditions, a cracking and a migration of certain chemical elements, in particular the alkalis, producing a contamination, by diffusion, of the blocks. adjacent. Advantageously, a sintered mortar according to the invention does not substantially lead to such contamination.

The invention also relates to an oven, in particular a copper remelting furnace, comprising a refractory wall comprising an assembly of blocks joined by means of a seal and / or covered with a protective coating and / or comprising a repaired region. , said seal and / or said protective coating and / or said repaired region being in a hardened mortar, or sintered according to the invention.

The furnace may be selected from a copper remelting furnace and a cast iron furnace.

The furnace may be in particular a vertical furnace with tank for continuous melting of copper cathodes, in particular obtained by electrolytic refining.

Definitions

- An unshaped refractory mixture is called an activatable, dry or moist particulate mixture.

- Activation is a process of taking in mass. The activated state conventionally results from moistening an unshaped refractory mixture with water or other liquid. During this process, a wet unformed refractory mixture is called an "activated mortar". Caking or "curing" of an activated mortar may result from drying or, for example, curing of a resin. It can be accelerated by means of a catalyst. The "hardened mortar" obtained can then undergo temperature rises which lead to a substantially total evaporation of the water. It can be sintered. The terms "activated mortar" and "hardened mortar" are used in the present description and claims independently of their application, and in particular can be used to refer to an "activated" or "hardened" grouting mortar, coating or repair paste. ", respectively.

- "Block" means a solid object that is not a particle.

- "Particle" means a solid object whose size is less than 10 mm. In particular, there are particles having a size greater than 100 μιη, called "grains", and those having a size less than or equal to 100 μιη, called "fine particles" or "matrix particles". All grains constitute the "coarse fraction". The set of matrix particles constitutes the "matrix fraction" or "fine fraction". In a "sintered mortar", the grains from the coarse fraction, or "granulate" are bound by a matrix that provides a binding structure between the grains.

- A set of particles forms a "powder".

The size of the particles of a powder is evaluated classically by a particle size distribution characterization performed with a laser granulometer. The laser granulometer may be, for example, a Partica LA-950 from the company HORIBA.

The percentiles or "percentiles" (D ₁₀ ), 50 (D ₅₀ ), 90 (D ₉₀ ) and 99.5 (D ₉ 9 ₁₅ ) of a powder are the particle sizes corresponding to the percentages, by mass, of

10%, 50%, 90% and 99.5%, respectively, on the cumulative particle size distribution curve of the powder particles, the particle sizes being ranked in ascending order. For example, 10% by weight of the particles of the powder have a size less than or equal to D ₁₀ and 90% of the particles by mass have a size greater than D ₁₀ . Percentiles can be determined using a particle size distribution using a laser granulometer.

- We call "minimum size of a powder", the percentile 10 (D ₁₀ ) of said powder.

- The "maximum size" is the 99.5 percentile (p99, ₅ ) of said powder.

- The "median size" is the percentile D50, that is to say the size dividing a set of particles in first and second populations equal in mass, these first and second populations having only particles having a size greater than or equal to or less than the median size, respectively.

- A "glass frit" is conventionally referred to as a mixture based on silica sand and on various constituents that may be alkaline and / or alkaline earth carbonates (ie CaCO ₃ , Na ₂ CO _3, etc.), or even mineral acids. such as boric acid or orthophosphoric acid, or even minerals added in small amounts (ie borax, alumina ...). This mixture undergoes a beginning of fusion in order to eliminate the carbonates and other hydrates, which makes it possible to facilitate its final use. The molten material is rapidly cooled to make a glass, and then milled to the desired particle size.

"Silica in micron form" means a silica powder whose particles, partially amorphous, have a median diameter of between 0.01 and 4 μιη. Silica in colloidal form has a median particle diameter that may be smaller, generally of the order of a few nanometers.

- "refractory" means "having a melting point or dissociation greater than 1000 ° C". By extension, an unshaped mixture having a coarse fraction having greater than 90% by weight of refractory particles may be termed "unshaped refractory mixture".

"Impurities" means the inevitable constituents introduced involuntarily and necessarily with the raw materials or resulting from reactions with these constituents. Impurities are not necessary constituents, but only tolerated.

- Unless otherwise indicated, all percentages for grades are percentages by mass measured after calcination (which excludes in particular water and organic matter). To measure the chemical composition of the material after calcination, it is conventionally carried out a heat treatment in air at 750 ° C. for 30 minutes, at atmospheric pressure. The duration of calcination can however be adjusted, the calcination must be sufficient to remove water and organic materials (the composition then not substantially evolving). The person skilled in the art knows which constituents will be extracted by the calcination. It therefore knows how to determine the refractory mixtures according to the invention, the fraction complementary to the coarse fraction a composition "after calcination" according to the invention. The fraction of the product that is extracted during the calcination is classically called "loss on ignition".

The mass content of a constituent is conventionally expressed in the form of the most stable oxide. The devices conventionally used to determine the compositions (microprobe, X-ray fluorescence) automatically convert the contents of the non-oxide constituents into equivalent oxide contents. For silicon, the most stable oxide is Si0 ₂ . However, the contents of silicon in the form of silicon carbide, silicon nitride, silicon oxynitride and metallic silicon have been isolated, "Si0 ₂ " thus corresponding to the mass content of silicon in all other forms than carbide of silicon, silicon nitride, silicon oxynitride and metallic silicon, expressed as Si0 ₂ .

The contents of silicon carbide, silicon nitride, silicon oxynitride and metallic silicon can be measured by X-ray diffraction. The SiC content can also be measured according to a protocol defined according to the ANSI standard B74.15-1992. (R2007) by difference between total carbon and free carbon, this difference corresponding to the carbon fixed in the form of silicon carbide.

- Classically, silicon nitride Si ₃ N ₄ denotes all forms of Si ₃ N ₄ (ie Si ₃ N ₄ -a and Si ₃ N ₄ -).

- "Temporary" means "removed from the product during the sintering heat treatment".

- "containing one", "comprising one" or "comprising one" means "containing at least one", unless otherwise indicated. detailed description

1) Unshaped fracture mix

The following tables provide preferred compositions, for a total of 100% of an unshaped refractory mixture according to the invention (whole of the coarse fraction, and of the complementary fraction):

Preferably:

The ranges of these two tables can be combined.

Preferably, the "other species" (that is to say other than SiC, S1 ₃ N _4, S1 ₂ ON _2, S1O _2, B ₂ O _3, Na ₂ 0, ZrO _"2, P ₂ O ₅ , A1 ₂ 0 ₃ , and CaO, the other species including the possible metallic silicon), represent less than 1, 5%, less than 1.0%, less than 0.5%>, or even less than 0.1% .

Preferably, the unshaped refractory mixture comprises more than 70%, and even more than 80%, or even more than 90% SiC, in weight percent based on the unshaped refractory mixture after calcination.

Preferably, the unshaped refractory mixture comprises less than 15% Zr0 ₂ , in weight percent based on the unshaped refractory mixture after calcination.

Preferably, the unshaped refractory mixture comprises less than 1.8% and, more preferably, less than 1.5% Al ₂ O ₃ , in weight percent based on the unshaped refractory mixture after calcination. The liquid phase (including water) is preferably less than 30%, less than 20%, preferably more than 5%, more than 10% by weight of the unshaped refractory mixture.

In one embodiment, the unshaped refractory mixture is substantially dry. Preferably, it has a humidity of less than 2%, preferably less than or equal to 1%, the humidity of the mixture being preferably measured by weight loss at 110 ° C for 4 hours.

After activation, the unshaped refractory mixture preferably comprises less than 30%, less than 20%, preferably more than 5%, more than 10% water, as a weight percentage of the base of the unshaped refractory mixture.

Preferably, SiAlON other than S1 ₃ N ₄ and S 1 ₂ ON ₂ represent less than 3%, less than 2%, less than 1%, or even substantially 0% of the mass of the unshaped refractory mixture.

The loss on ignition preferably represents less than 20%, preferably less than 10% or even less than 5% of the mass of the unshaped refractory mixture.

2) Coarse fraction

The coarse fraction may represent more than 30%, more than 40%, more than 50% and / or less than 99%, less than 80%, less than 70% of the mass of the unshaped refractory mixture.

In one embodiment, particularly for making a coating, the coarse fraction is less than 45%, preferably less than 40%, preferably less than 35% of the mass of the unshaped refractory mixture.

In one embodiment, in particular for making a grouting mortar, the coarse fraction represents more than 55%, more than 60%, more than 65%, and / or less than 85%, less than 80%, less than 75% of the mass of the unshaped refractory mixture.

Composition

The nature of the coarse fraction is not limiting.

However, the coarse fraction is preferably constituted, for more than 95%, more than 98%), preferably substantially 100% refractory particles, in weight percent, preferably particles of a non-oxide material, preferably carbide. silicon. Advantageously, silicon carbide improves the resistance chemical, especially against molten copper, reduces the risk of infiltration and increases the hot stiffness of the hardened and sintered mortar.

The coarse fraction may also be made up, in mass percentage, for more than 95%, more than 98%>, preferably substantially 100% of SiC particles, black corundum, white corundum, tabular alumina, sintered mullite , molten mullite, chromium oxide, magnesia, zirconia, zircon or a mixture of these materials.

Preferably, the mass quantity of the impurities in the coarse fraction is less than 2%, less than 1%, less than 0.5%, or even substantially zero. Particle size distribution

Preferably, the percentile D ₉₀ of the coarse fraction is less than 5 mm, preferably less than 3 mm, preferably less than 2 mm, preferably less than 1 mm and / or greater than 0.2 mm, preferably greater than 0.3 mm, preferably greater than 0.4 mm.

The median size of the coarse fraction is preferably less than 2 mm, preferably less than 1 mm and / or greater than 0.2 mm, preferably greater than 0.3 mm.

3) Complementary fraction (or "100% complement") of the coarse fraction Composition

The composition after calcination is conventionally used to disregard the constituents that will be extracted at high temperature, during sintering. The "loss on ignition", that is to say the part of the constituents removed during the calcination, does not substantially modify the properties of the sintered refractory material. It can, however, modify the rheology of the unshaped refractory mixture. The loss on ignition is preferably less than 30% (especially for a protective coating), preferably less than 25%, or even less than 20% (especially for a grout or a repair paste) of the mass of fine fraction. The loss on ignition may be less than or equal to 10% of the mass of fine fraction.

The liquid phase of the fraction complementary to the coarse fraction is preferably less than 3 times (especially for a protective coating), preferably less than 2.5 times, preferably less than 2 times (especially for a mortar of grouting or repair paste) the mass of the fine fraction. In one embodiment, the fraction complementary to the coarse fraction has substantially no liquid phase. The liquid phase is preferably made up of more than 90%, more than 95% or even substantially 100% by weight of water and / or boric acid and / or phosphoric acid, or even sodium silicate.

The refractory fine particles preferably represent more than 70%>, more than 80%>, more than 90%), or even substantially 100% of the complementary fraction, in weight percent, based on the unshaped refractory mixture after calcination.

The fine fraction preferably represents more than 10%>, more than 20%>, more than 25% or even more than 30%> and / or less than 60%>, less than 50%>, less than 45%, less by 40%, or even less than 35% of the mass of the unshaped refractory mixture after calcination.

The fraction complementary to the coarse fraction preferably comprises, in weight percentage on the basis of the complementary fraction after calcination, more than 52%, more than 55%, more than 57%, preferably more than 60%, more than 62% , preferably more than 65%, more than 67%, preferably more than 70% and / or less than 90%, less than 80% of silicon compound in a form other than SiO ₂ , and in particular silicon carbide and / or silicon nitride and / or silicon oxynitride, the silicon oxynitride being in the form preferably Si ₂ ON ₂ , preferably SiC.

Preferably, more than 90%, more than 95%, or even substantially 100% by weight of silicon carbide, silicon nitride, and silicon oxynitride, is provided by particles comprising more than 60%, more than 70%, more than 75%, more than 90%, more than 95%), more than 98%, or even substantially 100% by weight of silicon carbide, silicon nitride, and silicon oxynitride, respectively. In particular it is possible to use used SiC.

The fraction which is complementary to the coarse fraction preferably comprises more than 1.0%, more than 2.0%, more than 3.0%, more than 4.0% and / or less than 10.0%, less than 7.0%), preferably less than 5.0% SiO ₂ . SiO ₂ can in particular be provided by micron silica, and in particular silica fume, a natural alumino silicate, for example a clay, a bentonite, a cyanite or even a kerphalite, or even a calcined mullite powder or an alumino silicate synthesis. The fraction complementary to the coarse fraction preferably comprises more than 1.0%, more than 1.5% and / or less than 10% less than 5.0%, preferably less than 4.5%, and preferably less than 3.8% of B ₂ 0 ₃ .

Preferably, more than 90%>, more than 95%, even substantially 100% by weight of B ₂ 0 ₃ is provided by

a liquid phase or particles comprising more than 90%, more than 95% or even substantially 100% by weight of boric acid, and / or

particles having more than 90%, more than 95%, even substantially 100% by weight of Borax (Na ₂ B ₄ 0v), and / or

particles having more than 90%, more than 95%, even substantially 100% by weight of CaB ₆ and / or

particles comprising more than 90%, more than 95%, or even substantially 100% by mass of colemanite (Ca ₂ B ₆ 0n, 5H ₂ O) and / or

particles having more than 90%, more than 95%, even substantially 100% by weight of B ₄ C, and / or

particles comprising more than 90%, more than 95%, or even substantially 100% by weight of a mixture of B ₄ C and / or boric acid and / or borax and / or CaB ₆ and / or colemanite.

Preferably, the boron supply is carried out essentially in oxide form, in particular acid, borax or colemanite.

B ₂ 0 ₃ , for example in the form of boric acid or borax, may be added in liquid form to the unshaped refractory mixture to activate it.

The fraction complementary to the coarse fraction preferably comprises more than 0.5%, more than 1.0%, more than 2.0%, more than 3.0% and / or less than 4.5%, preferably less than 4.0% Al ₂ 0 ₃ . Preferably, more than 90%, more than 95%, or even substantially 100% by weight of the Al ₂ O ₃ of the fraction complementary to the coarse fraction is provided by particles comprising more than 90%, more than 95%, or substantially 100% by weight of crystallized alumina, preferably alpha alumina.

A1 ₂ 0 ₃ , for example in the form of alumina phosphate, may be added in liquid form to the unshaped refractory mixture to activate it.

The fraction complementary to the coarse fraction preferably comprises more than 1.0%, preferably more than 1.5% and / or less than 7.5%, preferably less than 5.0%, even less than 3.0% of Na ₂ 0. Preferably, more than 90%>, more than 95%, or even substantially 100% by weight of the Na ₂ 0 of the fraction complementary to the coarse fraction is provided by particles comprising more than 90%>, more than 95%, even substantially 100% by weight of sodium silicate, or sodium hexametaphosphate (HMPNa) or sodium polymethacrylate or Borax or a mixture of these species.

Na ₂ 0, for example in the form of sodium silicate or sodium phosphate, may be added in liquid form to the unshaped refractory mixture in order to activate it. Preferably, the fraction complementary to the coarse fraction comprises more than 0.1%, more than 2.0%, and / or less than 9.0%, less than 8.0%, preferably less than , 5%), less than 3.5% of P ₂ 0 ₅ , or even less than 3.0% of P ₂ 0 ₅ .

Preferably, more than 90%, more than 95%, or even substantially 100% by weight of the P ₂ 0 ₅ is provided by phosphoric acid and / or aluminum monophosphate and / or alkali metal phosphates, by example of sodium hexametaphosphate (HMPNa).

P ₂ 0 ₅ may be added in liquid form to activate the unshaped refractory mixture.

Preferably, the fraction complementary to the coarse fraction comprises more than 5.0%), preferably more than 7.0% and / or less than 45.0%, less than 43.0%, less than 40.0% ), less than 37.0%, less than 35.0%, less than 33.0%, less than 30.0%, less than 27.0%), less than 25.0%, less than 23.0 %, less than 20.0%, less than 17.0%, less than 15.0%, or even less than 12.0% Zr0 ₂ .

Preferably, more than 90%, more than 95%, or even substantially 100% by weight of Zr0 ₂ is provided in the form of zirconia or zircon, preferably in the form of particles having a size of less than 50μιη. Zirconia can be provided in stabilized form or not.

Preferably, the fraction complementary to the coarse fraction comprises more than 0.05% of CaO. In an advantageous embodiment, CaO> 0.1%, preferably CaO> 1.0%, or even CaO> 1.5%.

Preferably, CaO <4.0%, preferably CaO <3.5%, preferably CaO <3.0%, even CaO <2.5% or CaO <2.0%. Preferably, the mass quantity of "other species" of the fraction complementary to the coarse fraction (ie other than silicon carbide, silicon nitride, silicon oxynitride, SiO ₂ , B ₂ 0 ₃ , Na ₂ O, ZrO ₂ , P ₂ O ₅ , Al ₂ O ₃ , and CaO, the other species including the possible metallic silicon) in the fraction complementary to the coarse fraction is less than 2%, less than 1% , less than 0.5%, or substantially zero.

Part of the constituents of the fraction complementary to the coarse fraction may be introduced into the feedstock in the form of a frit or a mixture of glass frits.

Preferably, the 90 D ₉₀ percentile of the frit or glass frit mixture is less than 200 μιη, preferably less than 150 μιη, preferably less than 100 μιη.

A preferred composition range of the coarse fraction is as follows, for a total of greater than 98%, or even substantially 100%, based on the elemental fraction after calcination:

The preferred composition of the fraction complementary to the coarse fraction is as follows, for a total of more than 98%, or even substantially 100%, as a percentage on the basis of the complementary fraction after calcination:

In a preferred embodiment, the fine fraction of an unshaped refractory mixture according to the invention comprises, for a total of more than 95%:

more than 60%, preferably 65% to 85%, preferably 70% to 80% of fine particles of a silicon compound other than SiO ₂ , in particular silicon carbide and / or silicon nitride and / or oxynitride silicon, and preferably SiC, and

- 5%) at 15%), preferably 7% to 13%, preferably 8% to 12% of fine particles in a compound comprising ZrO ₂ , in particular a compound selected from zircon and / or zirconia, stabilized or no, preferably unstabilized zirconia, and

- 3%) to 13%), preferably 5% to 1 1%, preferably 7% to 10% of fine particles in a compound comprising Si0 ₂ and / or Al ₂ 0 ₃ , preferably selected from micronic silicas, in particular silica fume, aluminas, in particular alpha alumina, natural aluminosilicates, in particular clays, bentonite, cyanite, andalusite, kerphalite, calcined mullite, synthetic aluminosilicates, and mixtures thereof, preferably a natural aluminosilicate which also provides soda such as clay, provided that the A1 ₂ 0 _{3 content} remains below 4.8% in the complementary fraction, and

- 1%) to 5%>, preferably 2% to 5%, preferably 3% to 5% of fine particles in a mineral compound comprising boron, especially in the form of boric acid and / or borax and / or colemanite, or even CaB ₆ or B ₄ C, preferably boric acid, and

- 2%) to 7%) of fine particles in a compound comprising phosphorus and sodium hydroxide, especially chosen from alkali metal phosphates, preferably sodium hexametaphosphate.

Sintered refractory material

The manufacture of an activated mortar according to the invention is conventionally carried out by adding water to an unshaped refractory mixture according to the invention, and then mixing. In addition to the constituents mentioned above, the unshaped refractory mixture may also comprise a form-forming additive, preferably temporary, of the type conventionally used. As examples of usable additives, mention may be made, in a nonlimiting manner:

organic temporary binders, such as resins, derivatives of cellulose or lignin, such as carboxymethylcellulose, dextrin, polyvinyl alcohols, polyethylene glycols;

inorganic binders, such as silica gels or silica in colloidal form;

sintering promoters such as titanium dioxide or magnesium hydroxide;

shaping agents such as magnesium or calcium stearates;

- and their mixtures.

The appropriate additive contents are well known to those skilled in the art. The unshaped refractory mixture may typically comprise between 0.1% and 5% additive, in percent by weight based on the mass of the unshaped refractory mixture after calcination.

To form a grouting mortar, the amount of water added to the unshaped refractory mixture is preferably from 10% to 20%, based on the mass of the unshaped refractory mixture after calcination. Conventionally, the jointing joint has a thickness of between 0.5 and 10 mm, preferably between 1 and 5 mm.

To form a plaster, the amount of water is preferably between 10 and 30%, based on the mass of the unshaped refractory mixture after calcination. To form a repair paste, the amount of water is preferably from 10% to 25%, preferably from 10% to 20%, based on the mass of the unshaped refractory mixture after calcination.

The maximum size of the particles employed is preferably at least 3 times, preferably at least 5 times, less than the average thickness of the desired seal or coating or repair paste after curing. Finally, the shaping additive is chosen according to the desired rheology. Cellulosic derivatives (rheo-thinner) are preferably used, for example Shin-Etsu Tylose H200.

The coating can be applied in particular to the interior surface of an oven. All the classical techniques can be implemented. Preferably, the coating formed from the coating has a thickness of between 0.2 and 2 mm, preferably between 0.5 and 1 mm.

The sintering is preferably carried out at a temperature between 600 and 1600 ° C and leads to the generation of the matrix. The matrix may be a crystallized phase or not. The contribution of zirconia advantageously makes it possible to obtain a sintered matrix that is stable at high temperature.

Preferably, the composition of the matrix is substantially the same as that of the fraction complementary to the coarse fraction.

Oven

The side wall of an oven conventionally comprises a plurality of assembled blocks. Preferably, the blocks are assembled by means of an activated mortar according to the invention and / or coated with a coating consisting of an activated mortar according to the invention and / or repaired by means of an activated mortar according to the invention. the invention.

After hardening, the sintering of the cured mortar can be carried out in situ, during the first temperature rise of the oven.

In operation, the furnace vessel contains a bath of molten metal, particularly a copper bath. Preferably, the sintered mortar according to the invention is disposed in a zone in which it is likely to come into contact with the molten metal bath, in particular in a zone at the interface between the molten metal and the molten metal. gaseous environment.

Examples of furnaces are described in particular in the documents cited in the preamble of the present description.

Examples

The following examples are provided for illustrative and not limiting.

For each sample, a feedstock is prepared from the following raw materials:

- Black SiC supplied by Saint-Gobain Ceramic Materials SIKA grades 36/70, 100F and 220F ("SiC source" in the Table below),

zirconia CC10 supplied by SEPR ("source of Zr" in the table below), - RR40 clay supplied by DAMREC ("source of Al / Si / Na" in the table below),

- mixture of white corundum grade 0-0, 5mm supplied by Alcan and tabular alumina - 100 mesh supplied by Almatis (source of "Al"),

- zircon sand supplied by SEPR (source of "Zr / Si"),

- sodium hexametaphosphate supplied by the company Budenheim ("source of P" in the table below),

- powder of colemanite (calcium borate) supplied by Solargil ("source of B" for example 1 of the table below).

borate powder (borate of soda) called "Neobor powder" supplied by Mule team ("source of B" for example 2 of the table below),

boric acid supplied by the company VWR ("source of B" in the examples of the table below, except for Examples 1 and 2).

Constitution of the starting load

(as a weight percentage based on unshaped refractory mixture after calcination)

Composition of the fraction complementary to the coarse fraction

(as a weight percentage based on unshaped refractory mixture after calcination)

(*): The 100% complement consists of the coarse fraction.

The activated mortar is prepared according to a conventional procedure comprising:

- Dry mixing of the feedstock in a non-intensive planetary type mixer, for 2 minutes, then

an addition of water of 15% with respect to the mass of the starting charge, then

- Kneading for 10 minutes until a sufficient consistency for application as a grouting mortar.

Cryston Cu® (SiC3N4 matrix SiC) refractory bricks, each with a groove, are prepared and immersed in water to limit roasting. The groove is then filled with activated mortar. The clavels thus prepared are left at room temperature for 24 hours and then baked at 110 ° C. for 24 hours. The bells are then assembled, without joint between the bells, so as to form a crucible, the grooves being oriented towards the inside of the crucible so as to expose the mortar samples.

The crucible is sealed by pouring an aluminous refractory concrete outside the claveaux.

The crucible is heat-treated at 400 ° C. The temperature of the oven is raised to 1450 ° C. The crucible is gradually filled halfway up with molten copper. The crucible is then maintained at 1450 ° C. for at least 48 hours, in an oxidizing atmosphere. The oven rotates on itself to eliminate the "gas abrasion" factor, at a speed of 6 revolutions per minute.

At the end of the test, the aluminous concrete is removed in order to extract the corroded logs.

On each sample, we observe the different zones involved: zone in contact with molten copper, zone in contact with the burner gases and interface between these two zones. The "flame rank" measures the corrosion resistance of the zone in contact with the burner gases, taking into account the presence of grinding on the surface of the sample and the keel, corresponding to a diffusion of the mortar.

The "flame + interface" rank adds the corrosion criterion at the triple interface between the sample, the claveau and the molten metal, taking into account the resistance of the mortar to infiltration by molten copper.

The lower the index ("flame rank + interface" or "flame rank"), the better the performance. The following table provides the results obtained:

Examples 1 to 7 are according to the invention. Examples C1 to C5 are given for comparison. Example C4 consists of a matrix essentially based on zircon (ZrSiO ₄ ), thus with a high content of Zr0 ₂ and Si0 ₂ . Examples 1 to 3 have a composition of about 73 to 76% SiC, 1.6 to 1.7% B ₂ O ₃ , 1.8 to 2.6% Na ₂ O, less 3.5% Al ₂ O ₃ and less than 5%> SiO ₂ .

As is now clear, the invention provides a mortar that is perfectly suited for application to a copper reflow oven.

The invention is however not limited to this application. In particular, the mortar is also suitable for other metallurgical applications, especially for grouting cast iron blast furnace blocks. Preferably, the granulate is a corundum granulate, in particular with a brown or black corundum granulate.

Claims

1. Unshaped refractory mixture consisting of:

a coarse fraction consisting of particles having a size greater than 100 μηι, and

a fraction complementary to the coarse fraction consisting of

a fine fraction consisting of particles having a size of less than or equal to 100 μιη and representing more than 1%, and preferably less than 70%, of the mass of the unshaped refractory mixture after calcination, and

optionally a liquid phase,

the coarse fraction comprising more than 90% by mass of refractory particles, in mass percentage on the basis of the coarse fraction, after calcination, the fraction complementary to the coarse fraction comprising, as a percentage by weight on the basis of the complementary fraction, after calcination, and for a total of 100%,

- more than 50%) of silicon carbide and / or silicon nitride and / or silicon oxynitride, and less than 15% of other silicon compounds, or "Si0 ₂ ",

between 0.5% and 15% of B ₂ 0 ₃ ,

between 0.6% and 10% of Na ₂ O,

less than 48.9% of Zr0 ₂ ,

less than 10% of P ₂ O ₅ ,

- less than 4.8% of Al ₂ 0 ₃ ,

- less than 5% CaO,

- less than 5% of other species.

Unshaped refractory mixture according to the preceding claim, comprising more than 70% SiC, as a percentage by weight based on the unshaped refractory mixture after calcination.

3. Unshaped refractory mixture according to any of the preceding claims, wherein the fraction complementary to the coarse fraction represents less than 35% of the mass of the unshaped refractory mixture after calcination. An unshaped refractory mixture according to any one of the preceding claims, wherein the fraction complementary to the coarse fraction comprises, as a mass percentage on the basis of the complementary fraction after calcination,

- more than 55.0%) and less than 90.0%> of silicon carbide and / or silicon nitride and / or silicon oxynitride, preferably SiC, and / or

- more than 1.0% o and less than 10.0% of Si0 ₂ , and / or

- more than 1,5% o and less than 8,0%> of B ₂ 0 ₃ , and / or

- more than 1.0% o and less than 4.5%>, of Al ₂ 0 ₃ , and / or

- more than 1.0% o, and less than 7.5%> Na ₂ 0, and / or

- more than 0, 1%) and less than 9,0%> of P ₂ 0 ₅ , and / or

- more than 5.0% o and less than 20,0%> of Zr0 ₂ , and / or

- more than 0.05% o and less than 5.0%> of CaO.

5. Shaped refractory mixture according to the preceding claim, in which the fraction complementary to the coarse fraction comprises, as a percentage by weight, on the basis of the complementary fraction after calcination,

more than 65.0% and less than 80.0% of silicon carbide and / or silicon nitride and / or silicon oxynitride, preferably SiC, and / or

- more than 2.0% o and less than 7.0%> of Si0 ₂ , and / or

- less than 5,0%> of B ₂ 0 ₃ , and / or

- more than 2.0% and less than 4.0% Al ₂ 0 ₃ , and / or

- more than 1.5% o and less than 5.0%> Na ₂ 0, and / or

- more than 2,0% o and less than 8,0%> of P ₂ 0 ₅ , and / or

- more than 7,0% o and less than 15,0% of Zr0 ₂ , and / or

- more than 0.05% o and less than 5.0%> of CaO. Unshaped refractory mixture according to the preceding claim, in which the fraction complementary to the coarse fraction comprises, as a percentage by weight, on the basis of the complementary fraction after calcination,

more than 70.0% and less than 80.0% of silicon carbide and / or silicon nitride and / or silicon oxynitride, preferably SiC, and / or

- more than 3.0%) and less than 5.0%> of Si0 ₂ , and / or

- less than 4,5% of B ₂ 0 ₃ , and / or

- more than 3,0% Al ₂ 0 ₃ , and / or

- less than 3.0%> Na ₂ 0, and / or

- more than 1,5% and less than 5,5% of P ₂ 0 ₅ , and / or

- less than 12,0% of Zr0 ₂ , and / or

- more than 0.05%) and less than 5.0%> CaO.

Unshaped refractory mixture according to the preceding claim, in which the fraction complementary to the coarse fraction comprises, as a percentage by weight, on the basis of the complementary fraction after calcination,

- more than 60% of SiC, and / or

- more than 4.0% of Si0 ₂ , and / or

- less than 3.8% of B ₂ 0 ₃ .

Unshaped refractory mixture according to any one of the preceding claims, wherein the fraction complementary to the coarse fraction has a composition such that, for a total of more than 98%, as a percentage on the basis of the complementary fraction after calcination:

- SiC and / or Si ₃ N ₄ and / or Si ₂ ON ₂ 61.1 - 85.0%

- Si0 ₂ : 3.0 - 5.0%

- B ₂ 0 ₃ : 1, 0 - 5.0%

- A1 ₂ 0 ₃ : 0 - 4.8%

- Na ₂ 0: 1, 0 - 3.0%

- P ₂ 0 ₅ : 2.0 - 3.0%

- Zr0 ₂ : 5.0 - 15.0%

- CaO: 0.05 - 3.1%.

9. Unformed refractory mixture according to any one of the preceding claims having the following chemical composition, in weight percentage after calcination:

10. Unshaped refractory mixture according to any one of the preceding claims having the following chemical composition, in weight percentage after calcination:

1. Refractory mixture according to any one of the preceding claims, wherein the coarse fraction represents more than 60% and less than 75%, in weight percentage after calcination. 12. Refractory mixture according to any one of the preceding claims, in which the coarse fraction consists, in weight percent, of more than 95%, of SiC particles, of black corundum, of white corundum, of tabular alumina, of sintered mullite, molten mullite, chromium oxide, magnesia, zirconia, zircon or a mixture of these materials. 13. refractory mixture according to any one of the preceding claims having a moisture of less than 2%.

Oven having a refractory wall comprising an assembly of blocks joined by means of a seal and / or covered with a protective coating and / or comprising a repaired region, said seal and / or said protective coating and / or said repaired region being a sintered mortar obtained by activating, hardening and sintering an unshaped refractory mixture according to any one of the preceding claims.

15. Oven according to the preceding claim selected from a copper remelting furnace and a cast iron furnace.