Key Engineering Materials Vol. 517 (2012) pp 617-621 Online available since 2012/Jun/26 at www.scientific.net © (2012) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/KEM.517.617
Characterization Physics, Chemistry and Mineralogy of Waste from Kaolin and Their Potential Pozzolanic to Alkali Activation Ferreira.DTA1,a,Rocha.BD2,b,Lira.EC1,c,Gomes.KC1,d*,Torres.SM2,e, Barbosa.NB2, f 1
Departamento de Solos e Engenharia Rural, CCA/UFPB - Areia/PB – Brazil Nucleo de Estudos e Pesquisas em Materiais NEPEM-UFPB, Joao Pessoa/PB – Brazil a
[email protected],
[email protected],
[email protected], 2
d
[email protected],
[email protected],
[email protected]
Keywords: Characterizations, waste of kaolin, activation alkaline, environment
Abstract. The University Federal of Paraíba has developed various researches to explore the potential for recycling of industrial waste of Paraíba. Among them, the potential of use in the waste generated by processing of kaolin, which is one of the activities of great economic importance to the State of Paraíba and municipalities producers, because it causes a great environmental impact due to lack of an established recycling process. The kaolin processing generates large amounts of waste, one of fractions, a sandy (called in this study of RGC) containing quartz, mica and calcite; and other clay (called in this study of RFC) containing higher amounts of kaolinite. This objective of study is the characterization physical, chemical and mineralogical of waste kaolin (RFC and RGC) in order to evaluate the potential use of these wastes in the alkaline activation using silicates sodium and potassium. The characterizations physics, chemistry and mineralogy were by XRF, XRD, Unit Mass, Specific Mass and Specific Area. With the objective of studying the potential of waste as a material pozzolanic, it was processing through grinding at 10.000, 20.000, 40.000, 60.000 and 80.000 rpm and with the purpose of evaluating the reactivity of materials, these wastes were calcined at 750ºC/2h.The wastes RFC and RGC had different properties according to the processing. Thus, the waste RFChas the potential pozzolanic to use in alkaline activation. Introduction The study of materials with high technological efficiency, energy and environment has become an issue that needs urgent attention by the whole society. Thus, the objective is to obtain materials with high mechanical properties, which involve smaller amounts of energy in your building process, that generate less waste and pollutants or even incorporate them but also are more easily absorbed in nature, and therefore friendly the environment. The industrial waste is one of the most responsible for damage to the environment today. Some, if recycled, can add value when transformed into commercial products or byproducts. Thus, the use of this waste requires systematic studies for reuse to minimize the effects related to environmental impact. Several types of waste are discarded by industry, at random, in nature, such as waste from the processing of kaolin, which are sources of SiO2 and Al2O3. The kaolin is is a clay of high industrial value and various uses in many productive sectors such as textile, refractories, ceramics and paints. The raw material containing kaolin undergoes agravimetric separation of the mineral in settling ponds, screening processes wet and dry, resulting in amaterial that after ground kaolin is marketed. This process generates large amounts of waste that are deposited randomly distributed in nature, as shown in Figure 01.
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Fig.1.Processing ok kaolin. (top left): Raw Material, (lower left): Primary Separation, (lower right): Drying of Kaolin cakes, (top right): Provision of waste in the open. Although there is a regulatory requirement of the National Environment Council (CONAMA) regarding the proper disposal of their waste, the waste of kaolin do not yet have known recycling technology developed and validated. Thus, waste of kaolin have been the target of several research at the University Federal of Paraíba, in order to explore the potential for recycling of waste paraibanos for application in construction [1-6]. These wastes have distinct size fractions: a sandy (RGC) and other clay (RFC). The RGF contain quartz, mica and calcite and RFC contain higher amounts of kaolinite. This work will contribute to the development of sustainable technologies for reuse of waste through characterizations physics, chemistry and mineralogy and its potential for use in alkaline activation of materials. Experimental The collected materials were dried in an oven at 100ºC/1h and stored in plastic bags. After this was done grinding and calcination of the materials. Waste RFC and RGC were divided into 5 (five) samples of 2 kg each, for mills as follows: 10.000, 20.000, 40.000, 60.000 and 80.000 rpm. The processing was conducted in a ball mill (model SONNEX I-4205). After grinding, was removed 1Kg of material obtained in each rpm, and subjected to calcination at a temperature of 750ºC/2h, in order to obtain products more reactive. Were performed tests of Specify Mass [7], Area Specific [8] and Unit Mass [9]. The chemical composition of waste obtained by Sequential X-ray Fluorescence Spectrometer Shimadzu (model Shimadzu XRF-1800). The composition mineralogic of waste by X-Ray Diffractometer Siemens (modelo D5000), working with radiation Kα Cu, 30kV e 30mA, with scanning of 5°at 65°(2θ). Tests pozzolanic activity index with calcium hydroxide for the RFC were performed according to NBR 5751 [10]. This test is a direct measure of the degree of a pozzolanic material, through the compressive strength [11] in mortar specimens broken at 7 days. The amount of water used was the one that led to the consistency index of 225 ± 5mm [12] in table of consistency standard.The compressive strength tests were conducted in a universal testing machine of Shimadzu Servopulser.
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Results and Discussion Chemical Composition. Table 1 presents the chemical composition of waste. Table1 Composition of waste (XRF)
Unit Mass, Specific Mass and Specific Area. Table 2 presents the results obtained for Specific Mass and Unit Mass of waste of kaolin RGC and RFC and Table 3 presents the results obtained for Specific Mass and Specific Area of RFC after processing and calcinations. Table 2 Specific Mass and Unit Mass of waste RFC e RGC in nature
Table 3 Massa Especifica e Massa Unitária do RFC após beneficiamento e calcinação
Table 2 shows that the RFC does not show similarities with sand or with lime which has specific mass different. The RGC has specific mass close to that of sand (approximately 2.65 g/cm3). However, the RGC has is lighter than the sand because the sand has bulk density of about 1.60 g/cm3. Table 2 and 3shows that the Specific Mass of RFC has variation of state in natura (2.57g/cm3) to claimed (2.50g/cm3). However, its specific mass is unchanged due to the processing. but led to an increase in the specific area of the material, as expected. But this refinement becomes almost linear after 60.000rpm. X-Ray Diffraction. Figure 2 shows the diffraction pattern of RFC (in nature and calcined) and Table 4 summarizes the phases found before and after calcinations.
Fig.2. XRD patterns of waste of kaolin: (a) RFC fresh and (b) RFC calcined.
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Table 7 Fases encontradas antes e após calcinação dos resíduos
In Figure 2, shows that the RFC in the state in nature contains quartz, kaolinite and mica. After calcination shows the disappearance of kaolinite and the formation of metakaolin, material more reactive which favors alkaline activation. Pozzolanic Activity Index According to Nóbrega [3], the waste RFC fresh obtained values lower than those prescribed by NBR12653 [13]. The calcination brought benefits to the PAI (Pozzolanic Activity Index), but the values minimum normative of 6MPa only been achieved to prodessing from 60.000 rpm. Although the PAI has increased with the processing, this was not linear. This effect was confirmed also by Vieira [14] in studies of the waste of red ceramic whose composition containing metakaolin. Conclusion This study evaluated characterization physical, chemical and mineralogical of waste kaolin (RFC and RGC) and products originating from the alkaline synthesis with calcium hydroxide to the pozzolanic activity index. It can be concluded that: 1, The residues of kaolin may be characterized by the amount of kaolinite, is that the RFC contains much of this mineral, while the RGC has a higher composition of quartz; 2, Viewpoint of grain size, the RGC is best suited the limits of the sand and the RFC is a finer material, serving as a pozzolan, if activated thermal or chemically, and as filler in mortars; 3, Even with high amounts of kaolinite, the RFC unprocessed did not show IAP satisfactory according to NBR 7223, requiring comminution, after which the index has been achieved for processing from 60.000 rpm; 4, The waste of kaolin may serve as a material constituent of mortar and concrete, given their characteristics mineralogical, physical and chemical, but should be studied systematically, given its compositional variability; 5, The potential alkaline activation of the waste of kaolin can be related to the content of residual kaolinite existing, should be evaluated for each type of processing.
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References [1]
Dantas, R. R. Relatório de estágio supervisionado na CAULISA, Indústria de Caulim – S/A, Campina Grande –PB, 1983. [2] Dantas, K.C.B.; Nóbrega, A.F.; Ribeiro, P.H.L.C.; Torres, S.M.; Barbosa, N.P. Avaliação do potencial de reciclagem de resíduos do beneficiamento do caulim na construção civil: Mineralogia, índices físicos, cominuição e atividade pozolânica. IAC - BRASIL NOCMAT 2006 - Salvador, BA, Brasil, Octuber 20th – November 01th 2006. [3] Nóbrega, A.F.; Dantas, K.C.B.; Oliveira, M.P.; Torres, S.M.; Barbosa, N.P. Avaliação do desempenho de Argamassas com o uso de Rejeito de Caulim Industrial como Material de Substituição do Cimento Portland, IAC-NOCMAT 2005–Rio Rio de Janeiro, RJ, Brazil, November 11th - November 15th 2005 [4] Nóbrega, A.F.; Dantas, K.C.B.; Torres, S.M.; Sobrinho Jr, A.S.; Barbosa, N.P. Resíduos de Caulim em Argamassas de Múltiplo Uso: Efeito da Granulometria no Desempenho Mecânico, IACBRASIL NOCMAT 2006 - Salvador, BA, Brasil, 20 de Outubro a 01 de Novembro de 2006. [5] Nóbrega, A.F.; Oliveira, M.P.; Torres, S.M.; Polari Filho, R.S.;A.S.; Barbosa, N.P.; Araújo, J.L.Potencial do Uso do Rejeito de Caulim Industrial como Material de Substituição de Cimento Portland. In: 47o Congresso Brasileiro do Concreto, 2005, Recife. Anais do 47o Congresso Brasileiro do Concreto, 2005. v. v. p. [6] Nóbrega, A.F. Potencial de aproveitamento de resíduos de caulim paraibano para desenvolvimento de argamassas de múltiplo uso. Dissertação de Mestrado, Programa de Pós-graduação em Engenharia Urbana da Universidade Federal da Paraíba, 2007. [7] ABNT, NBR 9776-Agregado – Determinação da Massa Especifica de Agregados Miúdos por meio de Frasco de Chapman. Associação Brasileira de Normas Técnicas, Rio de Janeiro, 1987. [8] ABNT, NBR - NM76 - Determinação da finura pelo método de permeabilidade ao ar (Método de Blaine),– Cimento Portland. Associação Brasileira de Normas Técnicas, Rio de Janeiro, 1998; [9] ABNT, NBR 7251- Agregado em Estado Solto - Determinação da Massa Unitára. Associação Brasileira de Normas Técnicas, Rio de Janeiro, 1982; [10] ABNT, NBR 5751 - Índice de atividade pozolânica com a cal. Associação Brasileira de Normas Técnicas, Rio de Janeiro, 1992. [11] ABNT, NBR 7215-Determinação da resistência à compressão - Cimento Portland. Associação Brasileira de Normas Técnicas, Rio de Janeiro, 1996. [12] ABNT, NBR 13276-Determinação do teor de água para obtenção do índice de consistência padrão - Argamassa para assentamento de paredes e tetos. Associação Brasileira de Normas Técnicas,1995; [13] ABNT, NBR 12653 – Materiais Pozolânicos – Especificação. Associação Brasileira de Normas Técnicas, Rio de Janeiro, 1992. [14] VIEIRA, A.A.P. Estudo do aproveitamento de resíduos de cerâmica vermelha como substituição pozolânica em argamassas e concretos. 2005. Dissertação de Mestrado. Programa de Pós-Graduação em Engenharia Urbana. Universidade Federal da Paraíba, 2005.
Novel and Non-Conventional Materials and Technologies for Sustainability 10.4028/www.scientific.net/KEM.517
Characterization Physics, Chemistry and Mineralogy of Waste from Kaolin and their Potential Pozzolanic to Alkali Activation 10.4028/www.scientific.net/KEM.517.617
