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WO2025208197A1 - Système liant, composition de bloc réfractaire et procédé de préparation d'un bloc réfractaire - Google Patents

Système liant, composition de bloc réfractaire et procédé de préparation d'un bloc réfractaire

Info

Publication number
WO2025208197A1
WO2025208197A1 PCT/BR2025/050127 BR2025050127W WO2025208197A1 WO 2025208197 A1 WO2025208197 A1 WO 2025208197A1 BR 2025050127 W BR2025050127 W BR 2025050127W WO 2025208197 A1 WO2025208197 A1 WO 2025208197A1
Authority
WO
WIPO (PCT)
Prior art keywords
refractory
refractory block
binder
weight
fact
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/BR2025/050127
Other languages
English (en)
Portuguese (pt)
Inventor
Patrícia Alves Silva de Resende BRUM
Ariovaldo DO NASCIMENTO
Vladnilson Peter de Souza RAMOS
Riccardo Augusto Moreira MONTUORI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shinagawa Refratarios Do Brasil Ltda
Original Assignee
Shinagawa Refratarios Do Brasil Ltda
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from BR102024006692-8A external-priority patent/BR102024006692A2/pt
Application filed by Shinagawa Refratarios Do Brasil Ltda filed Critical Shinagawa Refratarios Do Brasil Ltda
Publication of WO2025208197A1 publication Critical patent/WO2025208197A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
    • C04B24/24—Macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/66—Monolithic refractories or refractory mortars, including those whether or not containing clay

Definitions

  • the present invention relates to an organic and/or inorganic binding system that, when used in a chromium-free refractory block composition, allows maintaining the integrity of the refractory block after heat treatment at low temperatures. Furthermore, the present invention relates to the refractory block composition and a process for preparing a refractory block.
  • refractory blocks used in vacuum degassing furnaces such as RH degassers, used in the steel refining process, comprise a lining made with products based on electrofused magnesium oxide and chromium oxide in their composition.
  • These are refractory bricks that undergo heat treatment (firing) at high temperatures, above 1500°C during production, before being supplied to the customer and used as linings for these furnaces.
  • the heat treatment stage at high temperatures, above 1500°C, is a process that requires high consumption of gases (natural and/or nitrogen) and energy expenditure, generating emissions of greenhouse gases, such as carbon dioxide, that is, it contributes to increasing the carbon footprint.
  • the chromium element which comes from chromium oxide, one of the raw materials used in the formulations currently used in refractory linings for RH degassers, can have negative impacts on the environment and human beings. If the refractory lining is not properly disposed of after the RH degasser has finished operating, the chromium, when in the Cr 6+ (hexavalent) valence, can become toxic and harmful to the environment. environment.
  • document CN105218116 refers to refractory bricks and the method of preparing these refractory bricks, specifically relating to a type of chromium-free brick for use in RH vacuum furnaces.
  • this refractory block comprises magnesium oxide (MgO), calcium oxide (CaO), silicon oxide (SiO) in electrofused magnesite clinker and aluminum-rich spinel powder trace for electric casting.
  • Document W02004087609 refers to a chromium-free amorphous refractory used for lining a waste melting furnace, such as a gasification melting furnace or a ash fusion.
  • the refractory formulation described in this document includes a specific amount of yttria-based material in the main raw material, alumina, to improve the durability of the refractory as a lining for the melting furnace.
  • the composition of this brick comprises metallic aluminum and carbon-based organic binders, and the heat treatment applied to this brick is not carried out at high temperatures.
  • the present invention aims to provide an organic and/or inorganic binding system to be applied in a refractory block composition allowing to maintain the integrity of the refractory block after it undergoes heat treatment at low temperatures, so that the refractory block has sufficient resistance to maintain its integrity during transportation and even its application as a lining for furnaces that work at high temperatures, such as, for example, an RH degasser.
  • Another objective of this invention is to provide a refractory block composition, free of chromium and with high corrosion resistance when in contact with slag during its application as a lining of an RH degasser.
  • the present invention has as its object a binding system, comprising: a) from 0.1 to 5% by weight of inorganic binder selected from a group of polymeric silicates and/or a group of polymeric phosphates; or b) from 0.1 to 5% by weight of organic binder; wherein the concentration of said components is calculated based on the binder system by weight.
  • an object of this invention is a refractory block composition for use as a lining in high temperature furnaces, comprising
  • composition further comprising 0.1% to 5% by weight of the binder system.
  • Another object of the present invention is a process for preparing a refractory block, comprising:
  • Figures 1a and 1b - illustrate cross sections of a sample of burnt refractory block and Magnesia-Chromium 1 base subjected to lance corrosion test;
  • Figures 6a, 6b and 6c - illustrates results of thermodynamic simulations performed in the FactSage 8.0 software considering the composition of the refractory in contact with the C2 slag under conditions similar to the slag test;
  • the present invention has as its object a binder system comprising from 0.1 to 5% by weight of inorganic binders selected from a group of polymeric silicates and/or from a group of polymeric phosphates; or from 0.1 to 5% by weight of organic binder; the concentration of said components being calculated based on the system binder by weight.
  • the organic binder is also used as a binder or deflocculant as an alternative to the inorganic binder or in addition to this inorganic binder.
  • the organic binder consists of a resin-based compound such as Novolac resin, which is widely used as a binder in magnesium oxide-based refractory bricks because it ensures good mechanical strength properties to the product.
  • the function of the binding system is to enable the refractory blocks to be formed with a heat treatment step at low temperatures, between 150°C and 600°C, which are already sufficient to activate this binding system so that, with this, the refractory blocks can maintain their integrity and resistance during handling, transportation and installation in furnaces.
  • the spinel is present in particle sizes smaller than 3.00 mm and, as described above, together with the electrofused and/or sintered magnesium oxide, it has the function of providing greater resistance to thermal shock of the refractory block.
  • the binding system is present in the refractory block composition in a range of 0.1 to 5% and has the function of agglutinating the grains of the elements of this composition, hardening the refractory block during the heat treatment stage, as will be seen below, and, further, ensuring the resistance and maintenance of the integrity of this refractory block before the sintering reactions that will form the ceramic phases when the refractory block is exposed to high temperatures during its use.
  • the present invention also has as its object a process for preparing a refractory block, as illustrated in figure 7, which comprises the following main steps:
  • Step (a) the portioning of the raw materials, consists of combining the electrofused and/or sintered magnesium oxide, the spinel and the zirconium sources in the granulometries defined and described above, in order to form the raw material particulates containing the coarse and fine particulates.
  • the binder system is added to the raw material particulates in quantities ranging from 0.1 to 5%.
  • the binder system may comprise the powdered inorganic binder or the liquid organic binder, as detailed previously.
  • the raw material particles and the binding system are mixed in a conventional mixer until the most homogeneous mixture possible is obtained. This mixture is then compacted, using presses, into molds with the desired shape for the refractory blocks.
  • pre-cured molded refractory blocks are obtained. Due to the presence of the binder system in the composition of this plurality of pre-cured refractory blocks, it is possible to carry out the heat treatment step of these pre-cured refractory blocks at low temperatures, that is, at temperatures between 150°C and 600°C, which are substantially lower than the temperatures of the heat treatment steps of these types of refractory blocks known in the prior art. Thus, the pre-cured molded refractory blocks are subjected to the heat treatment step to remove possible volatiles from the organic binders and to activate the binder system and harden the pre-cured refractory blocks.
  • the cooling stage of the heat treatment begins, at a cooling rate between 10°C and -50°C per hour.
  • cured refractory blocks are obtained with the binding system activated so that remain intact during packaging, transportation, and even during the assembly of these blocks on the furnace walls.
  • the atoms of the refractory material or new phases coalesce, with reactions and interactions between the particles of this refractory material forming strong bonds between these particles, called ceramic bonds, and creating a protective layer on the refractory blocks against corrosion due to contact with the slag formed inside the furnace, with which the refractory blocks have intense and prolonged contact.
  • the first test conducted at the Shinagawa Research Center in Japan, consists of passing oxygen gas through a steel lance to generate a very aggressive slag composed of iron oxide (FeO), due to the reaction ' ⁇ 2 * and which occurs at high temperatures ( ⁇ 2000°C).
  • the lance remains in contact with the face of the refractory block or brick to be evaluated for 30 seconds so that, after cooling, the depth and volume of the wear caused can be determined.
  • the cured brick identified here as 3 is the cured, chromium-free refractory block that has the composition subject to the present invention, with the characteristics described above and prepared by the refractory block preparation process, also subject to this invention.
  • Figures 1a, 2a and 3a illustrate the contact region with the oxygen lance of bricks 1, 2 and 3, respectively, after the test was performed.
  • Figures 1b, 2b and 3b illustrate the cut cross sections of bricks 1, 2 and 3, respectively, evaluated in the test and show the difference in wear between the pieces.
  • the fired bricks of samples 1 and 2 as illustrated in figures 1a, 1b, 2a and 2b, presented cracks, further indicating low mechanical and thermal shock resistance, when compared to the cured brick or cured refractory block of the present invention, illustrated in figures 3a and 3b.
  • the second test conducted at the Laboratory of the Technical Department of Shinagawa Brasil, consists of internally lining a rotary kiln with the samples of refractory bricks to be studied and, with the aid of a blowtorch that emits a flow of gas rich in oxygen and natural gas, maintaining the internal temperature at around 1620°C ⁇ 30°C, allowing the slag that will be in contact with the refractory block under study to melt.
  • the RH Degasser type furnace contains different refining stages, including oxygen blowing and the addition of aluminum (Al), among others, the composition of the slag undergoes changes throughout the cycle.
  • Table 1 Chemical composition of synthetic slags used in rotary kiln corrosion testing.
  • the graphs in figures 4a and 4b illustrate the comparative wear results between the fired bricks and the cured refractory block of the present invention, when exposed to the two slags F2 and C2 respectively, in the rotary kiln test.
  • the cured refractory block object of the present invention will have more resistance to a slag rich in CaO, as indicated in the corrosion test in the rotary kiln using the C2 slag.
  • the cured refractory block obtained from the composition and process that are objects of the present invention, is free of the chromium element, however, it comprises the binding system that allows this refractory block to be obtained with a heat treatment step at low temperatures and, when in use, achieves a corrosion and crack resistance performance similar and/or superior to bricks or blocks fired at high temperatures and containing chromium in their composition, which are known in the state of the art and currently applied in RH furnace linings.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)

Abstract

L'invention concerne un système liant, comprenant : a) de 0,1 à 5 % en poids d'un liant inorganique sélectionné dans un groupe des silicates polymères et/ou un groupe des phosphates polymères ; ou b) de 0,1 à 5 % en poids d'un liant inorganique ; la concentration desdits composants étant calculée sur la base du système liant en poids. L'invention concerne également une composition de bloc réfractaire et un procédé de préparation d'un bloc réfractaire, la composition de bloc réfractaire étant destinée à être utilisée comme revêtement dans des fours à haute température, et comprenant : 70 à 90 % en poids d'oxyde de magnésium électrofondu et/ou fritté ; 10 à 15 % en poids de spinelle ; 0,1 à 5 % en poids de sources de zirconium ; la composition comprenant en outre de 0,1 à 5 % en poids du système liant.
PCT/BR2025/050127 2024-04-05 2025-04-03 Système liant, composition de bloc réfractaire et procédé de préparation d'un bloc réfractaire Pending WO2025208197A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BR102024006692-8A BR102024006692A2 (pt) 2024-04-05 Sistema ligante, composição de bloco refratário e processo de preparação de um bloco refratário
BR1020240066928 2024-04-05

Publications (1)

Publication Number Publication Date
WO2025208197A1 true WO2025208197A1 (fr) 2025-10-09

Family

ID=97265674

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/BR2025/050127 Pending WO2025208197A1 (fr) 2024-04-05 2025-04-03 Système liant, composition de bloc réfractaire et procédé de préparation d'un bloc réfractaire

Country Status (1)

Country Link
WO (1) WO2025208197A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000075089A1 (fr) * 1999-06-07 2000-12-14 Allied Mineral Products, Inc. Composition refractaire seche legere
WO2005001359A1 (fr) * 2003-06-30 2005-01-06 Refratechnik Holding Gmbh Ouvrage de maçonnerie a l'epreuve des flammes et pierres a l'epreuve des flammes destinees a cet ouvrage de maçonnerie a produire
BR112014007465B1 (pt) * 2012-11-29 2021-08-24 Refratechnik Holding Gmbh Uso de tijolos refratários não calcinados

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000075089A1 (fr) * 1999-06-07 2000-12-14 Allied Mineral Products, Inc. Composition refractaire seche legere
WO2005001359A1 (fr) * 2003-06-30 2005-01-06 Refratechnik Holding Gmbh Ouvrage de maçonnerie a l'epreuve des flammes et pierres a l'epreuve des flammes destinees a cet ouvrage de maçonnerie a produire
BR112014007465B1 (pt) * 2012-11-29 2021-08-24 Refratechnik Holding Gmbh Uso de tijolos refratários não calcinados

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