WO2018232474A1 - Pozzolan containing andradite and method for producing pozzolan containing andradite formed in situ - Google Patents

Pozzolan containing andradite and method for producing pozzolan containing andradite formed in situ Download PDF

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Publication number
WO2018232474A1
WO2018232474A1 PCT/BR2017/050155 BR2017050155W WO2018232474A1 WO 2018232474 A1 WO2018232474 A1 WO 2018232474A1 BR 2017050155 W BR2017050155 W BR 2017050155W WO 2018232474 A1 WO2018232474 A1 WO 2018232474A1
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WIPO (PCT)
Prior art keywords
andradite
clay
pozolana
limestone
calcination
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PCT/BR2017/050155
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French (fr)
Portuguese (pt)
Inventor
José EUSTAQUIO MACHADO
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Votorantim Cimentos S.A
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Priority to BR112019027393-0A priority Critical patent/BR112019027393A2/en
Priority to PCT/BR2017/050155 priority patent/WO2018232474A1/en
Publication of WO2018232474A1 publication Critical patent/WO2018232474A1/en

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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
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • 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
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/04—Silica-rich materials; Silicates
    • C04B14/10—Clay
    • 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
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/26—Carbonates
    • C04B14/28—Carbonates of calcium
    • 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
    • C04B7/00—Hydraulic cements
    • 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
    • C04B7/00—Hydraulic cements
    • C04B7/12—Natural pozzuolanas; Natural pozzuolana cements; Artificial pozzuolanas or artificial pozzuolana cements other than those obtained from waste or combustion residues, e.g. burned clay; Treating inorganic materials to improve their pozzuolanic characteristics
    • 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
    • C04B7/00—Hydraulic cements
    • C04B7/12—Natural pozzuolanas; Natural pozzuolana cements; Artificial pozzuolanas or artificial pozzuolana cements other than those obtained from waste or combustion residues, e.g. burned clay; Treating inorganic materials to improve their pozzuolanic characteristics
    • C04B7/13—Mixtures thereof with inorganic cementitious materials, e.g. Portland cements
    • 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
    • C04B7/00—Hydraulic cements
    • C04B7/36—Manufacture of hydraulic cements in general
    • C04B7/38—Preparing or treating the raw materials individually or as batches, e.g. mixing with fuel

Definitions

  • the present invention also relates to a process for the formation of inorganic andradite to provide an alkaline earthenware of acceptable red clay for to the cement.
  • the process of manufacturing pozoin from red clays is known, but little used, as a function of the color of the produced Pozo.
  • the clay is calcined pure, the calcination temperature of the material does not exceed 900 ° C, generating a red calcined pottery that, when added to the cement, changes its color to brown, causing a rejection of the use the consumer and even distrust of product quality.
  • Red clay shows good pozzolanic activity when calcined, however, it is rejected for pozoan production.
  • the purpose of the present invention is to enable the use of red clay for the production of pozoian by modifying its coloration in calcination.
  • PI 1002450 of Cement Company Liz S / A. reveals a form of calcination of clays with the addition of fuel, such as ground oil coke.
  • the calcination occurs at temperatures between 600 and 900 ° C with residence time of the material in the kiln 40 to 70 minutes, temperature below the range of the invention, 900 ° C and 130 ° C, in the opposite direction to the present invention, the document does not disclose in-situ formation of andradite, nor does it reveal the use of red clay for the production of a gray-colored Pozoian.
  • W012142547 to Green Binder Technologies LTD, discloses a cement composition using a binder comprising 60-94% of a pozzolanic material.
  • the binder comprises andradite.
  • the document reveals the inclusion / addition of andradite in the pozzolanic cement, however, does not reveal in-situ andradite formation in the calcination.
  • the present invention enables the use of red clays, hitherto an abundant and easily accessible reserve, subtilized for the manufacture of pozzolana, since a good part of the limestone deposits are red clays.
  • the inventors have found, surprisingly and unexpectedly, that the composition is capable of promoting such benefits; and in particular by producing a pozzolana suitable for use in cements.
  • Fig. 1 shows the comparison of red clay, in natura without limestone, before calcination, on the left; and red clay, without limestone, after calcination, on the right.
  • Fig. 2 shows the comparison between red clay, with 18% limestone, before calcination, on the left; and the same red clay after the calcination, to the right, already showing dark gray color.
  • Fig. 3 presents the red clay with limestone, at the exit of the manufacturing process already showing dark gray color.
  • Fig. 4 shows the diffractogram of the red clay without the addition of limestone, calcined in the laboratory at 950 ° C.
  • Fig. 5 shows Diffractogram of red clay with the addition of limestone, calcined in the laboratory at 950 ° C.
  • the present invention aims at making the use of red clay for the production of pozzolana possible by modifying their coloration in calcination. This was surprisingly achieved by the combination of 18% limestone and 82% red clay, calcined with pozzolan oil at a temperature of 950 ° C.
  • the present invention provides a Pozolane composition comprising at least 2.0% andradite, preferably from [2.0] to [8.0%] andradite.
  • the Pozolana preferably further comprises 2.0% to 10.0% Mulita, 0.1% to 5.0% Hematite, 2.0% to 10.0% Anorthite, to 5.0% % of Cristobalite and 20.0% to 50.0% of Quartz, with andradite being an andradite resulting from in situ formation during calcination.
  • the present invention further comprises a process for producing Pozolana comprising a calcination step which promotes the in situ formation of andradite, it is preferable to perform the calcination between 900 ° C and 1303 ° C.
  • the process preferably further comprises:
  • step c) It may further comprise a cooling step, subsequent to step c) of calcination of the mixture.
  • the Pozolana production process is carried out at a temperature of 950 ° C, with a residence time of the blend within the kiln of approximately 90 minutes.
  • the mixture of clay and limestone is fed into the furnace in counter flow to the exhaust gases produced by the burning of fuel, entrained inside the furnace through an exhaust fan.
  • Red-colored clay is generally used as a corrective in flour, which is the product of grinding clay, which is limestone with clay, and specific additives in ball mills and vertical mills, so that the grain size of the material is about 0.050 mm (50 ⁇ m).
  • This material when calcined in the pozolana oven, under normal operating conditions, generates a pozzolana of good quality. However, its red color significantly affects the color of the cement when this material is used as an addition.
  • the inventors have surprisingly found that in order to solve the problem of red staining, the calcination of the red clay in admixture with 18% limestone at 950 ° C yields a gray color pozzolan which does not alter the color of cement.
  • the clay deposit commonly used in pozzolans is transported over long distances for its production, with calcination of clay.
  • Such common clay has good reactivity and coloration suitable for addition to the cement.
  • transport contributes significantly to its variable cost being higher than the variable clinker cost.
  • a first object of the present invention is to provide a pozolane composition comprising andradite, preferably an andradite resulting from in situ formation during calcination.
  • a second object is to provide a process for the manufacture of pozolana comprising andradite, which allows the in-situ formation of andradita.
  • the pozzolana of the present invention and process is a gray stained pozzolan, which permits its use in cements, free of substantial coloring offsets.
  • the present invention relates to a pozzolana comprising at least 2.0% andradite in its composition, preferably 2.0% to 8.0% andradite and at most 5.0 % of hematite in its composition.
  • the Pozolane according to the present invention further comprises from 2.0% to 10.0% Mulita, from 0.1% to 5.0% of Hematite, from 2.0% to 10.0% of Anortite, 0.0% to 5.0% of Cristobalite and 20.0% to 50.0% of Quartz.
  • Andradite is an andradite resulting from in-situ formation during calcination.
  • the present invention further comprises a process for producing Pozolana comprising a calcination step which promotes in situ formation of andradite, preferably calcination is carried out between 900 ° C and 1303 ° C, preferably 950 ° C W.
  • the production process of Pozolana also includes:
  • the Pozolana production process, object of the present invention has a residence time of the blend within the kiln of approximately 90 minutes, with the feed in the kiln of the clay and limestone mixture being counter flow to the exhaust, produced by the burning of fuel, dragged through the interior of the oven through an exhaust fan.
  • the process contemplates the process known in the art, that is to say, the red clay from the field feeds a hopper with a screwdriver, which supplies an intermediate silo with a balance, which dosages the clay in a conveyor belt that carries the material to the inlet ramp of the furnace where the material is fed into the kiln to be calcined and cooled, where a conveyor receives the material and transports to the silo ready for consumption.
  • a torch coupled to the furnace outlet burns fuel generating gases that are drawn from the interior of the furnace, passing through a cyclone where part of the particulate material is retained and returned to the furnace by gravity.
  • Gases containing fine particles pass through a bag filter where the particulate fines are retained which also returns to the furnace through mechanical transport, where the clean gases pass through the blower and are released into the atmosphere through a flue.
  • the residence time of the material within the furnace is approximately 90 minutes and the calcination temperature is 900 ⁇ ° C to 130 ⁇ ° C, for the simultaneous formation of andradite, giving dark gray the calcined pozzolana.
  • Figure 2 shows the comparison of the red clay with 18% limestone and after calcination, and shows the significant change of color, changing from red ( Figure 1) to dark gray.
  • Table 1 shows the characterization of the red clay in natura and the mixture of 82% red clay and 18% limestone after calcination at 950 ° C:

Abstract

The present application relates to a pozzolanic material containing at least 2% andradite (Ca3Fe2(SiO-4)3) formed in situ in its composition. The pozzolan is produced from red clay, which, after mixing with limestone (50-97% red clay and 3-5% limestone), is calcined at a temperature between 900 and 1300°C, with the in situ formation of andradite occurring. The method in question allows the use of red clay with a high Fe3+ content by means of the conversion of hematite (Fe2O3) into andradite. The final material has a gray colour and does not alter the colour of cement when added to it.

Description

"POZOLANA COM ANDRADITA E PROCESSO PARA PRODUÇÃO DE  "POZOLANA WITH ANDRADITA AND PROCESS FOR PRODUCTION OF
POZOLA A COM ANDRADITA FORMADA IN-SITU POZOLA A WITH ANDRADITA FORMED IN-SITU
CAMPO DA INVENÇÃO FIELD OF THE INVENTION
[001 ] A presente invenção refere-se a uma pozoiana compreendendo andradita em sua composição, resultante de formação in-situ durante a calcinação, A presente invenção também revela processo de formação de andradita in-situ para entregar uma pozoiana de argila vermelha aceitável para misturação ao cimento. The present invention also relates to a process for the formation of inorganic andradite to provide an alkaline earthenware of acceptable red clay for to the cement.
ANTECEDENTES DA INVENÇÃO BACKGROUND OF THE INVENTION
[002] O processo de fabricação de pozoiana a partir de argilas vermelhas é conhecido, mas pouco utilizado, em função da cor da pozoiana produzida. Neste processo, a argila é calcinada pura, a temperatura de calcinação do material não ultrapassa 900°C, gerando uma pozoiana calcinada de cor vermelha que, quando adicionada ao cimento, altera a cor do mesmo para marrom, provocando a rejeição de uso por parte do consumidor e até mesmo desconfiança da qualidade do produto. The process of manufacturing pozoin from red clays is known, but little used, as a function of the color of the produced Pozo. In this process, the clay is calcined pure, the calcination temperature of the material does not exceed 900 ° C, generating a red calcined pottery that, when added to the cement, changes its color to brown, causing a rejection of the use the consumer and even distrust of product quality.
[003] A argila vermelha apresenta boa atividade pozolânica quando calcinada, contudo, é rejeitada para a produção de pozoiana. A presente invenção tem como objetivo viabilizar o uso da argila vermelha para a produção de pozoiana, pela modificação de sua coloração na calcinação. [003] Red clay shows good pozzolanic activity when calcined, however, it is rejected for pozoan production. The purpose of the present invention is to enable the use of red clay for the production of pozoian by modifying its coloration in calcination.
[004] O PI 1002450 de Empresa de Cimento Liz S/A. , revela uma forma de calcinação de argilas com a adição de combustível, como o coque de petróleo moído. A calcinação se dá em temperaturas dentre 600 a 900°C com tempo de residência do material no forno de 40 a 70 minutos, temperatura inferior à faixa da invenção, de 900°C e 13Q0°C, em sentido contrário ao da presente invenção, o documento não revela a formação in-situ de andradita, tampouco revela a utilização de argila vermelha para a produção de uma pozoiana de coloração cinza. [004] PI 1002450 of Cement Company Liz S / A. , reveals a form of calcination of clays with the addition of fuel, such as ground oil coke. The calcination occurs at temperatures between 600 and 900 ° C with residence time of the material in the kiln 40 to 70 minutes, temperature below the range of the invention, 900 ° C and 130 ° C, in the opposite direction to the present invention, the document does not disclose in-situ formation of andradite, nor does it reveal the use of red clay for the production of a gray-colored Pozoian.
[005] O W012142547, de Green Binder Technologies LTD, revela uma composição de cimento que utiliza um ligante (binder) compreendendo de 60-94% de um material pozolânico. No Exemplo 3, revela que o binder compreende andradita. Assim, o documento revela a inclusão/adição de andradita no cimento pozolânico, contudo, não revela a formação de andradita in-situ na calcinação. W012142547, to Green Binder Technologies LTD, discloses a cement composition using a binder comprising 60-94% of a pozzolanic material. In Example 3, it is disclosed that the binder comprises andradite. Thus, the document reveals the inclusion / addition of andradite in the pozzolanic cement, however, does not reveal in-situ andradite formation in the calcination.
[006] Portanto, existe uma necessidade por pozolanas e métodos que busquem sua produção utilizando materiais de fácil acesso e que são subutilizados, como a argila vermelha, resultando em aceitação pelo mercado consumidor pela promoção de coloração compatível com o cimento. Therefore, there is a need for pozzolans and methods that seek their production using materials that are easily accessible and that are underutilized, such as red clay, resulting in acceptance by the consumer market for the promotion of coloration compatible with the cement.
[007] A presente invenção viabiliza a utilização de argilas vermelhas, até então uma reserva abundante e de fácil acesso, subtilizada para o fabrico de pozolana, já que uma boa parte dos capeamentos das jazidas de calcário é constituída de argilas vermelhas. The present invention enables the use of red clays, hitherto an abundant and easily accessible reserve, subtilized for the manufacture of pozzolana, since a good part of the limestone deposits are red clays.
[008] Neste aspecto, os inventores verificaram, de modo surpreendente e inesperado, que a composição é capaz de promover tais benefícios; e em especial produzindo uma pozolana de coloração adequada para a utilização em cimentos. In this regard, the inventors have found, surprisingly and unexpectedly, that the composition is capable of promoting such benefits; and in particular by producing a pozzolana suitable for use in cements.
FIGURAS FIGURES
[009] A Fig. 1 apresenta a comparação entre a argila vermelha, in natura sem calcário, antes da calcinação, à esquerda; e a argila vermelha, sem calcário, após a calcinação, à direita. [009] Fig. 1 shows the comparison of red clay, in natura without limestone, before calcination, on the left; and red clay, without limestone, after calcination, on the right.
[01 0] A Fig. 2 apresenta a comparação entre a argila vermelha, com 18% de calcário, antes da calcinação, à esquerda; e mesma argila vermelha após a calcinação, à direita, já apresentando cor cinza escuro. [01 0] Fig. 2 shows the comparison between red clay, with 18% limestone, before calcination, on the left; and the same red clay after the calcination, to the right, already showing dark gray color.
[01 1 ] A Fig. 3 apresenta a argila vermelha com calcário, na saída do processo de fabricação já apresentando cor cinza escuro. Fig. 3 presents the red clay with limestone, at the exit of the manufacturing process already showing dark gray color.
[01 2] A Fig. 4 apresenta Difratograma da argila vermelha sem a adição de calcário, calcinada em laboratório a 950°C. Fig. 4 shows the diffractogram of the red clay without the addition of limestone, calcined in the laboratory at 950 ° C.
[01 3] A Fig. 5 apresenta Difratograma da argila vermelha com a adição de calcário, calcinada em laboratório a 950°C. Fig. 5 shows Diffractogram of red clay with the addition of limestone, calcined in the laboratory at 950 ° C.
SUMÁRIO DA INVENÇÃO [01 4] A presente invenção tem como objetivo viabilizar o uso da argila vermelha para a produção de pozolana, pela modificação de sua coloração na calcinação. Tal feito foi, surpreendentemente, alcançado pela combinação de 18% de calcário e 82% de argila vermelha, calcinada errí forno de pozolana a uma temperatura de 950°C. SUMMARY OF THE INVENTION The present invention aims at making the use of red clay for the production of pozzolana possible by modifying their coloration in calcination. This was surprisingly achieved by the combination of 18% limestone and 82% red clay, calcined with pozzolan oil at a temperature of 950 ° C.
[01 5] A presente invenção apresenta uma composição de Pozolana, compreendendo pelo menos 2,0% de andradita, preferivelmente de [2,0] a [8,0%] de andradita. A Pozolana, preferivelmente, compreender ainda de 2,0% a 10,0% de Mulita, de 0,1 % a 5,0% de Hematita, de 2,0% a 10,0% de Anortita, até 5,0% de Cristobalita e de 20,0% a 50,0% de Quartzo, sendo que a andradita é uma andradita resultante de formação in-situ durante a calcinação. The present invention provides a Pozolane composition comprising at least 2.0% andradite, preferably from [2.0] to [8.0%] andradite. The Pozolana preferably further comprises 2.0% to 10.0% Mulita, 0.1% to 5.0% Hematite, 2.0% to 10.0% Anorthite, to 5.0% % of Cristobalite and 20.0% to 50.0% of Quartz, with andradite being an andradite resulting from in situ formation during calcination.
[01 6] A presente invenção compreende ainda um processo de produção de Pozolana, compreendendo uma etapa de calcinação que promove a formação, in- situ, de andradita, sendo preferível a realização da calcinação entre 900 °C e 1 .300 °C. O processo preferivelmente compreende ainda: The present invention further comprises a process for producing Pozolana comprising a calcination step which promotes the in situ formation of andradite, it is preferable to perform the calcination between 900 ° C and 1303 ° C. The process preferably further comprises:
[01 7] a) Misturação de argila vermelha e calcário na proporção de 50% a 97% de argila e 3% a 50% de calcário, produzindo uma mistura, [017] (a) Mixing of red clay and limestone in the proportion of 50% to 97% clay and 3% to 50% limestone, producing a mixture,
[01 8] b) Alimentação no forno com a mistura de argila e calcário, [01 8] (b) Feeding in the oven with the mixture of clay and limestone,
[01 9] c) Calcinação da mistura a uma temperatura entre 900 °C e 1 .300 °C. [019] c) Calcination of the blend at a temperature between 900 ° C and 1,300 ° C.
[020] d) Formação in-situ de andradita. [020] d) In-situ formation of andradita.
[021 ] Podendo ainda compreender uma etapa de resfriamento, posterior à etapa c) de calcinação da mistura. Preferivelmente, o processo de produção de Pozolana é realizado à uma temperatura de 950 °C, com um tempo de residência da mistura dentro do forno de aproximadamente 90 minutos. Alimenta-se a mistura de argila e calcário no forno em contra fluxo aos gases de exaustão, produzidos pela queima de combustível, arrastados pelo interior do forno através de exaustor. [021] It may further comprise a cooling step, subsequent to step c) of calcination of the mixture. Preferably, the Pozolana production process is carried out at a temperature of 950 ° C, with a residence time of the blend within the kiln of approximately 90 minutes. The mixture of clay and limestone is fed into the furnace in counter flow to the exhaust gases produced by the burning of fuel, entrained inside the furnace through an exhaust fan.
[022] A pozolana alcançada pela presente composição e processo apresenta qualidade adequada, além da coloração cinza escura, muito próxima à cor do cimento, sendo uma óti ma coloração para a aceitação no mercado. DESCRIÇÃO DETALHADA DA INVENÇÃO [022] The pozzolana reached by the present composition and process presents adequate quality, in addition to the dark gray coloration, very close to the color of the cement, being an excellent staining for the market acceptance. DETAILED DESCRIPTION OF THE INVENTION
[023] A argila de coloração vermelha é geralmente utilizada parcialmente como corretivo na farinha, que é produto da moagem do argical, que é o calcário com argila, e aditivos específicos, em moinhos de bolas e moinhos verticais, para que a granulometria do material fique por volta de 0,050 mm (50 pm). [023] Red-colored clay is generally used as a corrective in flour, which is the product of grinding clay, which is limestone with clay, and specific additives in ball mills and vertical mills, so that the grain size of the material is about 0.050 mm (50 μm).
[024] Esse material quando calcinado no forno de pozolana, em condição normal de operação, gera uma pozolana de boa qualidade. Porém, a sua coloração vermelha afeta significativamente a cor do cimento quando se usa esse material como adição. [024] This material, when calcined in the pozolana oven, under normal operating conditions, generates a pozzolana of good quality. However, its red color significantly affects the color of the cement when this material is used as an addition.
[025] Os inventores descobriram, surpreendentemente, que para solucionar o problema de coloração vermelha, a calcinação da argila vermelha em mistura com 1 8% de calcário a 950°C obtém -se uma pozolana de cor cinza, que não altera a cor do cimento. The inventors have surprisingly found that in order to solve the problem of red staining, the calcination of the red clay in admixture with 18% limestone at 950 ° C yields a gray color pozzolan which does not alter the color of cement.
[026] Em geral, a jazida de argila comumente utilizada nas pozolanas é transportada por longas distâncias para sua produção, com a calcinação de argila. Tal argila comum possui boa reatividade e coloração adequada para adição ao cimento. Porém, o transporte contribui significativamente para que seu custo variável seja superior ao custo variável do clínquer. [026] In general, the clay deposit commonly used in pozzolans is transported over long distances for its production, with calcination of clay. Such common clay has good reactivity and coloration suitable for addition to the cement. However, transport contributes significantly to its variable cost being higher than the variable clinker cost.
[027] Uma das alternativas para reduzir o custo da pozolana seria utilizar o capeamento de argila vermelha , já disponível nas jazidas de calcário, pois também possui boa reatividade após calcinação. No entanto, quando calcinada, a argila vermelha resulta em uma pozolana vermelha, que afeta negativamente a cor do cimento ao qual ela é adicionada. [027] One of the alternatives to reduce the cost of pozzolana would be to use the red clay cap, already available in the limestone deposits, because it also has good reactivity after calcination. However, when calcined, the red clay results in a red pozzolana, which adversely affects the color of the cement to which it is added.
[028] Um primeiro objetivo da presente invenção é prover uma composição de pozolana compreendendo andradita, preferivelmente uma andradita resultante de formação in-situ durante a calcinação. Um segundo objetivo é prover um processo para a fabricação de pozolana compreendendo andradita, que permite a formação in-situ de andradita. A pozolana da presente invenção e processo é uma pozolana de coloração cinza, que permite seu uso em cimentos, livre de desvios substanciais de coloração. [029] Para atingir este objetivo, a presente invenção refere-se a uma pozolana compreendendo pelo menos 2,0% de andradita em sua composição, preferivelmente, de 2,0% a 8,0% de andradita e no máximo 5,0% de hematita, em sua composição. Preferivelmente, a Pozolana, de acordo com a presente invenção, compreende adicionalmente de 2,0% a 10,0% de Mulita, de 0, 1 % a 5,0% de Hematita, de 2,0% a 10,0% de Anortita, de 0,0% a 5,0% de Cristobalita e de 20,0% a 50,0% de Quartzo. A andradita é uma andradita resultante de formação in-situ durante a calcinação. [028] A first object of the present invention is to provide a pozolane composition comprising andradite, preferably an andradite resulting from in situ formation during calcination. A second object is to provide a process for the manufacture of pozolana comprising andradite, which allows the in-situ formation of andradita. The pozzolana of the present invention and process is a gray stained pozzolan, which permits its use in cements, free of substantial coloring offsets. [029] To achieve this object, the present invention relates to a pozzolana comprising at least 2.0% andradite in its composition, preferably 2.0% to 8.0% andradite and at most 5.0 % of hematite in its composition. Preferably, the Pozolane according to the present invention further comprises from 2.0% to 10.0% Mulita, from 0.1% to 5.0% of Hematite, from 2.0% to 10.0% of Anortite, 0.0% to 5.0% of Cristobalite and 20.0% to 50.0% of Quartz. Andradite is an andradite resulting from in-situ formation during calcination.
[030] A presente invenção compreende ainda um processo de produção de Pozolana compreendendo uma etapa de calcinação que promove a formação, in- situ, de andradita, preferivelmente, a calcinação é realizada entre 900 °C e 1 .300 °C, preferivelmente 950 °C. O processo de produção de Pozolana compreende ainda: The present invention further comprises a process for producing Pozolana comprising a calcination step which promotes in situ formation of andradite, preferably calcination is carried out between 900 ° C and 1303 ° C, preferably 950 ° C W. The production process of Pozolana also includes:
[031 ] a) Mistu ração de argila vermelha e calcário na proporção de 50% a 97% de argila e 3% a 50% de calcário, produzindo uma mistura, [031] a) Mixture of red clay and limestone in the proportion of 50% to 97% clay and 3% to 50% limestone, producing a mixture,
[032] b) Alimentação no forno com a mistura de argila e calcário, [032] (b) Feeding in the oven with the mixture of clay and limestone,
[033] c) Calcinação da mistura a uma temperatura entre 900 °C e 1 .300 °G [033] c) Calcination of the blend at a temperature between 900 ° C and 1,300 ° C
[034] d) Formação in-situ de andradita. [034] d) In-situ formation of andradita.
[035] O processo de produção de Pozolana, objeto da presente invenção, apresenta um tempo de residência da mistura dentro do forno de aproximadamente 90 minutos, com a alimentação, no forno, da mistura de argila e calcário ser em contra fluxo aos gases de exaustão, produzidos pela queima de combustível, arrastados pelo interior do forno através de exaustor. The Pozolana production process, object of the present invention, has a residence time of the blend within the kiln of approximately 90 minutes, with the feed in the kiln of the clay and limestone mixture being counter flow to the exhaust, produced by the burning of fuel, dragged through the interior of the oven through an exhaust fan.
[036] Especificamente, o processo contempla o processo já conhecido na técnica, ou seja, a argila vermelha proveniente da jazida alimenta uma moega com destorroador, que abastece um silo intermediário dotado de balança, que dosa a argila em uma correia transportadora que transporta o material até a rampa de entrada do forno onde o material é alimentado ao forno para ser calcinado e resfriado, onde um transportador recebe o material e transporta até o silo de estocagem estando pronto para consumo. Um maçarico acoplado à saída do forno queima combustível gerando gases que são arrastados do interior do forno, passam por um ciclone onde parte do material particulado é retido e retorna ao forno por gravidade. Os gases contendo partículas finas passam por um filtro de mangas onde ficam retidos os finos de particulado que também retorna ao forno através de transporte mecânico, sendo que os gases limpos passam pelo ventilador de tiragem e são lançados na atmosfera através de uma chaminé. No processo da presente invenção, o tempo de residência do material dentro do forno é de aproximadamente 90 minutos e a temperatura de calcinação é de 900°C a 1 .3Q0°C, para formação in- sítu de andradita, conferindo coloração cinza-escuro à pozolana calcinada. Specifically, the process contemplates the process known in the art, that is to say, the red clay from the field feeds a hopper with a screwdriver, which supplies an intermediate silo with a balance, which dosages the clay in a conveyor belt that carries the material to the inlet ramp of the furnace where the material is fed into the kiln to be calcined and cooled, where a conveyor receives the material and transports to the silo ready for consumption. A torch coupled to the furnace outlet burns fuel generating gases that are drawn from the interior of the furnace, passing through a cyclone where part of the particulate material is retained and returned to the furnace by gravity. Gases containing fine particles pass through a bag filter where the particulate fines are retained which also returns to the furnace through mechanical transport, where the clean gases pass through the blower and are released into the atmosphere through a flue. In the process of the present invention, the residence time of the material within the furnace is approximately 90 minutes and the calcination temperature is 900Â ° C to 130Â ° C, for the simultaneous formation of andradite, giving dark gray the calcined pozzolana.
[037] Os exemplos não limitadores a seguir ilustram com mais detalhes a invenção. [037] The non-limiting examples below illustrate in more detail the invention.
Testes Tests
[038] Foi realizado um teste industrial de fabricação da pozolana, objeto da presente invenção, com a produção de 300 1 de pozolana durante 6 horas. O forno de pozolana trabalhou de forma estável, não ocorrendo nenhum distúrbio operacional durante a realização do teste. A pozolana produzida, Figura 2 e Figura 3, apresentou boa granulação e coloração cinza escura, adequada para utilização como adição ao cimento. An industrial pozzolan manufacturing test, object of the present invention, was carried out with the production of 300 l pozzolana for 6 hours. The pozolana oven worked steadily, with no operational disturbance occurring during the test. The pozzolan produced, Figure 2 and Figure 3, presented good granulation and dark gray coloration, suitable for use as addition to the cement.
Resultados Results
[039] Caracterização dos materiais [039] Characterization of materials
[040] A argila vermelha foi calcinada in natura, sem calcário. A comparação entre sua cor antes e depois de calcinada é apresentada na Figura 1 . [040] The red clay was calcined in natura, without limestone. The comparison between its color before and after calcined is shown in Figure 1.
[041 ] A Figura 2 exibe a comparação da argila vermelha com 18% de calcário e após calcinação, e evidencia a mudança significativa de cor, que passa de vermelho (Figura 1 ) para cinza escuro. [041] Figure 2 shows the comparison of the red clay with 18% limestone and after calcination, and shows the significant change of color, changing from red (Figure 1) to dark gray.
[042] A Tabela 1 apresenta a caracterização da argila vermelha in natura e da mistura de 82% de argila vermelha e 18% de calcário, após a calcinação a 950°C: [042] Table 1 shows the characterization of the red clay in natura and the mixture of 82% red clay and 18% limestone after calcination at 950 ° C:
Figure imgf000009_0001
Figure imgf000009_0001
Tabe a 1 - Caracterização da argila n natura e da mistura 82% de argila e 18% calcário calcinada  Tabe a 1 - Characterization of the natural clay and the mixture 82% clay and 18% calcined limestone
[043] A análise mineralógica por difração de raios X (DRX) da argila vermelha calcinada em laboratório, sem a adição de calcário, é apresentada na Figura 4. [043] The mineralogical analysis by X-ray diffraction (XRD) of calcined red clay in the laboratory, without the addition of limestone, is presented in Figure 4.
[044] Observa -se que quando a argila é calcinada sem o calcário, há a permanência do ferro na forma de hematita, que é o mineral responsável pela coloração vermelha. [045] A análise mineralógica por difração de raios X (DRX) da argila vermelha calcinada em laboratório, com a adição de calcário, é apresentada na Figura 5. [044] It is observed that when the clay is calcined without the limestone, the iron remains in the form of hematite, which is the mineral responsible for the red coloration. [045] The mineralogical analysis by X-ray diffraction (XRD) of calcined red clay in the laboratory, with the addition of limestone, is presented in Figure 5.
[046] Quando a argila é calcinada com o calcário, observa -se o desaparecimento da hematite e a formação de andradita, que é um silicato de ferro e cálcio. Este mineral tem cor esverdeada, contribuindo, assim, para a modificação da cor da pozolana resultante. [046] When the clay is calcined with limestone, the disappearance of hematite and the formation of andradite, which is an iron and calcium silicate, is observed. This mineral has a greenish color, thus contributing to the color change of the resulting pozzolana.
[047] Na Tabela 2, são detalhadas as nomenclaturas dos minerais, suas fórmulas químicas e coloração. [047] In Table 2, the nomenclatures of the minerals, their chemical formulas and coloration are detailed.
[048] Tabela 2 [048] Table 2
Figure imgf000010_0001
Figure imgf000010_0001
[049] Tabela 2 - Lista dos minerais identificados na DRX, com fórmula química e possíveis cores.  [049] Table 2 - List of minerals identified in XRD, with chemical formula and possible colors.
[050] O teste industrial realizado no forno de pozolana mostrou ser possível produzir pozolana de boa qualidade tanto do ponto de vista da reatividade quanto da cor, a partir de argila vermelha em mistura com calcário. Sem prender-se à teoria, acredita-se que a mudança de coloração final da pozolana, de vermelha para cinza, ocorreu devido à formação de andradita, no lugar de hematite, em função da presença de cálcio proveniente do calcário e do silício proveniente da própria argila vermelha. The industrial test carried out in the pozolana furnace showed that it is possible to produce good quality pozzolan from both the reactivity and color points, from red clay mixed with limestone. Without being attached to the theory, it is believed that the change in the final staining of the pozzolan, from red to gray, occurred due to the formation of andradite, in the place of hematite, due to the presence of calcium from limestone and silicon from own red clay.
[051 ] Esta nova condição de calcinação permitirá a plantas de fabricação da pozolana, onde existem fornos antigos ociosos, produzirem pozolanas de coloração cinza a partir do uso de argilas vermelhas abundantes nos capeamentos das jazidas de calcário. [051] This new condition of calcination will allow pozolana plants, where there are old ovens, to produce pozolanas of color ash from the use of abundant red clays in the cappings of limestone deposits.
[052] Tal iniciativa reduzirá substancialmente os custos de fabricação e o fator clínquer. [052] Such an initiative will substantially reduce manufacturing costs and the clinker factor.

Claims

REIVI NDICAÇÕES REIVI NDICATIONS
1 . Pozolana, CARACTERIZADA por compreender pelo menos 2,0% de andradita em sua composição. 1 . Pozolana, CHARACTERIZED in that it comprises at least 2.0% of andradite in its composition.
2. Pozolana, de acordo com a reivindicação 1 , CARACTERIZADA por compreender de 2,0% a 8,0% de andradita e no máximo 5,0% de hematita, em sua composição. Pozolana according to claim 1, CHARACTERIZED in that it comprises from 2.0% to 8.0% andradita and a maximum of 5.0% hematite in its composition.
3. Pozolana, de acordo com a reivindicação 1 , CARACTERIZADA por adicionalmente compreender de 2,0% a 10,0% de Mulita, de 0,1 % a 5,0% de Hematita, de 2,0% a 10,0% de Anortita, até 5,0% de Cristobalita e de 20,0% a 50,0% de Quartzo, em sua composição. Pozzolana according to claim 1, CHARACTERIZED as further comprising from 2.0% to 10.0% Mulita, from 0.1% to 5.0% of Hematite, from 2.0% to 10.0% % Anortite, up to 5.0% of Cristobalite and 20.0% to 50.0% of Quartz in its composition.
4. Pozolana, de acordo com a reivindicação 1 , CARACTERIZADA pela andradita ser uma andradita resultante de formação in-situ durante a calcinação em sua composição. 4. Pozolane according to claim 1, CHARACTERIZED by andradite is an andradite resulting from in situ formation during calcination in its composition.
5. Processo de produção de Pozolana, CARACTERIZADO por compreender uma etapa de calcinação que promove a formação, in-situ, de andradita. A Pozolana production process, CHARACTERIZED in that it comprises a calcination step which promotes in-situ formation of andradite.
6. Processo de produção de Pozolana, de acordo com a reivindicação 5, CARACTERIZADO pela calcinação ser realizada entre 900 °C e 1 .300 °C. The production process of Pozolana according to claim 5, wherein the calcination is carried out at 900 ° C to 1303 ° C.
7. Processo de produção de Pozolana, CARACTERIZADO por compreender: a) Misturação de argila vermelha e calcário na proporção de 50% a 97% de argila e 3% a 50% de calcário, produzindo uma mistura, b) Alimentação no forno com a mistura de argila e calcário, c) Calcinação da mistura a uma temperatura entre 900 °C e 1 .300 °C d) Formação in-situ de andradita. A process for the production of Pozolana, characterized in that it comprises: a) mixing of red clay and limestone in the proportion of 50% to 97% clay and 3% to 50% limestone, producing a mixture, b) Feeding in the furnace with mixture of clay and limestone, c) calcination of the blend at a temperature between 900 ° C and 1,300 ° C. d) in-situ formation of andradite.
8. Processo de produção de Pozolana, de acordo com a reivindicação 7, CARACTERIZADO pela temperatura de calcinação ser de 950 °C. The Pozolana production process according to claim 7, wherein the calcination temperature is 950 ° C.
9. Processo de produção de Pozolana, de acordo com a reivindicação 8, CARACTERIZADO pelo tempo de residência da mistura dentro do forno ser de aproximadamente 90 minutos. A Pozolana production process according to claim 8, wherein the residence time of the blend within the kiln is approximately 90 minutes.
1 0. Processo de produção de Pozolana, de acordo com a reivindicação 9, CARACTERIZADO pela alimentação no forno com a mistura de argila e calcário ser em contra fluxo aos gases de exaustão, produzidos pela queima de combustível, arrastados pelo interior do forno através de exaustor. A production process of Pozolana according to claim 9, characterized in that the feed in the furnace with the clay-lime mixture is counterflow to the exhaust gases produced by the burning of fuel entrained by the interior of the furnace through exhaust fan
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WO2012126696A1 (en) * 2011-03-18 2012-09-27 Outotec Oyj Clinker substitute based on calcined clay
US20120312194A1 (en) * 2011-06-09 2012-12-13 Rutgers, The State University Of New Jersey Synthetic formulations and methods of manufacturing and using thereof

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WO2012126696A1 (en) * 2011-03-18 2012-09-27 Outotec Oyj Clinker substitute based on calcined clay
US20120312194A1 (en) * 2011-06-09 2012-12-13 Rutgers, The State University Of New Jersey Synthetic formulations and methods of manufacturing and using thereof

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