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Brazil has 95 million tons of Li reserves in the form of pegmatites but produces less than 1% of the global output. Historically Li production in Brazil has been low due to governmental restrictions aimed at controlling the exploitation and trade of Li in Brazil. However, as of 2022, these restrictions were revoked. The abundance of untapped pegmatite ores in Brazil complements the soaring demand for Li in energy-storage applications. This study performs process mineralogy studies on 10 samples collected from a Li pegmatite deposit in the southeastern region of Minas Gerais in Brazil. The samples were characterized by combining density separation and SEM-based automated mineralogy processing system allied with XRF, ICP OES, XRD, and LA–ICPMS. The latter was used to determine Li content in micas which allowed determining the Li deportment between Li-bearing minerals. The results show that the samples contain such Li-bearing minerals as muscovite (0.5 wt% Li2O) and lepidolite (3.1 wt% Li2O), in addition to spodumene (8.0 wt% Li2O). According to the characterization of the spodumene concentrate (d = 3.11) by density separation (at d = 2.95), two main trends were observed: (a) low Li deportment in the sink product (approximately 44% wt%) and higher Li2O grade (approximately 6.5 wt%), and (b) higher Li deportment in the sink product (58%) and lower Li2O content (approximately 4.9 wt%). The first trend is associated with higher modal content of mica since it carries Li to the light product. Lower Li grade is related to the presence of Fe-bearing minerals (e.g., epidote and amphibole) as they report to the dense product and do not contain Li. Spodumene has a high degree of liberation in all samples; therefore, it did not influence the deportment results. The findings highlight the benefit of combining scanning electron microscopy-based automated mineralogy with LA–ICPMS and other techniques from process mineralogy studies in mineral processing. In addition to the mineralogy and liberation characteristics, identifying Li-bearing minerals and determining Li deportment is crucial.

This article evaluates the efficiency, benefits and limitations of pre-concentration by density separation for process mineralogy studies of low-grade gold ore. The pre-concentration by density aims to generate a product with a high content of gold and to maximize the number of gold-bearing particles characterized, thereby increasing the representativity and reducing the number of polished sections to be analyzed. Pre-concentration by density was carried out for a low-grade sulfide gold ore (0.96 ppm) from the north of Brazil. The sample was ground to below 1.7 mm, sieved down to 0.037 mm and subjected to density separation, amalgamation of the heavy product and cyanide leaching of all products. Gold was assessed in each product to evaluate the separation recovery and distribution. The finer the particle size, the higher the gold distribution in the heavy product, due to a higher degree of liberation of gold and sulfides; these values varied from 65% to 84% in fractions below 0.60 mm and decreased from 40% to 13% in the coarser fractions. Regarding gold distribution, fractions finer than 0.84 mm indicates a notable increase on gold recovery by amalgamation, indication higher surface exposure.

Reservoir wettability plays a critical role in determining the fluid interactions, distributions, and flow paths in porous mediums, which is directly reflected in oil production and recovery strategies during a field’s production life. Many factors can influence reservoir wettability characterisation on the laboratory scale such as: sample origin, mineralogical composition, cleaning procedures for further analysis, pressure, temperature, and the oil aging process. The best practice to restore the sample's original wettability by aging processes is unclear, impacting the assessment of contact angle (CA) measurements. This work addresses the oil aging time and experimental conditions associated with the pressure and temperature in CA measurements on rock surfaces from a Brazilian pre-salt reservoir with a predominance of calcite, dolomite, and quartz, respectively. For this purpose, all surfaces used were cleaned with solvents and saturated with synthetic formation water under vacuum conditions. To evaluate the influence of oil aging time on the samples' wettability, the CA measurements, by captive bubble method, were performed on unaged surfaces. The CA measurements were then taken again on the same surfaces after 14 and 42 days of oil aging. To evaluate the pressure and temperature effects on the CA values, the experiments were run at 14.7 psi and 22 °C (room conditions), 14.7 psi and 60 °C and 4000 psi and 60 °C. The results showed a mischaracterization of all surfaces' original wettability due to the cleaning process, showing the higher hydrophilic degree and wettability character of neutral and water-wet surfaces. The oil aging procedure was confirmed to be a fundamental process in restoring the wettability of rock surfaces, requiring more than 14 days to be achieved. Pressure and temperature conditions also matter on CA evaluations. The surface's hydrophobic degree increased as the pressure increased from 14.7 psi to 4000 psi, and the temperature from 22 °C to 60 °C. Furthermore, a higher influence of temperature than pressure was observed to impact CA values. Oil aging and experimental conditions presented a larger effect on increasing the hydrophobic degree of samples with calcite and dolomite predominance than those with quartz predominance.

In a multivariate database, the missing data can be obtained through several imputation techniques, which are particularly useful for data that are difficult to obtain, for any reason, or have high uncertainties or scarce variables. A Self-Organizing Maps (SOM) neural network is an effective tool for the analysis of multidimensional data applied for the imputation of data. In this paper, data from drilling were used for training, testing, and validation using the variables: total Au recovery (%), which means gold recovery from a gravity concentration plus hydrometallurgical process, Au (g/t), As (ppm), S (%), Al2O3 (%), CaO (%), K2O (%), and MgO (%). After training, the partial omission of Au content and recovery was carried out, from 10% to 50%, to evaluate the data imputation performance for those variables. The results imputed by the SOM were compared with the original data values and evaluated according to descriptive statistics; the results indicated a determination coefficient of 85% when 50% of the data were omitted and 93% when 10% of the data were omitted. Once demonstrated, the correlation between the original data and SOM imputation analysis can help geologists and metallurgists to obtain results with a high degree of reliability of metallurgical recovery through related chemical variables, making it possible to implement SOM analysis as a powerful tool to input analytical data. One of the practical applications of the proposed model is to produce a pattern of imputed data that can be a good alternative in the construction or generation of a synthetic geometallurgical database with missing data.

The aim of this study was to investigate the construction and demolition waste (CDW) fine size fraction by increasing its reactivity with mechanical activation (MA) in a stirred media mill. Systema...

The study extended the applications of powder pycnometry (PP) replacing the commercial enveloper for alternative envelopers (ceramic and carbon microspheres) to determine the envelope density of fine recycled aggregates (FRA) sand fraction. The properties of enveloper material such as particle size distribution, skeletal density and shape (aspect ratio and sphericity) affect the envelope density determination consequently impacts in porosity results by the association of PP and Helium pycnometry (HePyc). The porosity determination by association of HePyc and PP are comparable with mercury intrusion porosimetry analysis for medium sand fraction (0.300–1.180 mm).

Understanding rock mineralogy is essential for formation evaluation, improving the calculation of porosity and hydrocarbon saturation. The primary method to obtain the mineralogy from a well is by applying a model to the geochemical tool's chemical elements. However, creating a mineralogical model presents challenges such as the minerals' chemical composition and the decision to include a mineral in the model. The traditional application of machine learning can make mineral models less realistic since conventional training is developed based on a set of minerals with different occurrences, lowering some minerals' representativeness. The present research proposes the stepped machine learning (SML), a stepped way to use machine learning to create a mineralogical model from chemical and mineralogical data. A database was assembled with the elemental concentration obtained with XRF analyses and the mineral concentrations obtained with XRD analyses. The chemical elements were Al, Ca, Fe, K, Mg, Mn, Na, Si, and Ti. The minerals were calcite, dolomite, quartz, clays, K-feldspar, plagioclase, and pyroxene. Four algorithms were tested: MLP, GAN, Random Forest, and XGBoost, with XGBoost showing the best results. SML was applied, where a mineral model results are used to train a subsequent model. SML allowed for a significant improvement in some models, notably to clays with an increase in R2 from 0.597 to 0.853, quartz an increase from 0.673 to 0.869, and calcite, from 0.758 to 0.862. A decrease in the mean squared error of these minerals' models was also observed. The model was applied to the geochemical logs from three wells drilled in the Brazilian pre-salt, and the results were compared with XRD analyzes. The SML model was able to honor the mineral concentrations for different rocks. It is demonstrated that the integration between machine learning tools and geological knowledge in SML was crucial for creating a representative mineralogical model.

The aim of this study is to characterize barite samples from Azara located in Nasarawa state, Nigeria, and determine their suitability for oil and gas applications. The mineralogy, chemical composition, morphology and specific gravity were determined using X-ray diffractometry, X-ray fluorescence (XRF), scanning electron microscope and energy-dispersive X-ray and optical microscope. Particle size analysis was done using wet sieve analysis and heavy liquid separation; lastly, a pycnometer was used to determine the specific gravity (SG). The results of the chemical composition by XRF revealed the presence of BaO, Fe2O3, SiO2, SO3 and SrO, while the minor minerals present were MgO, Al2O3, K2O, CaO, MnO and NaO and the trace minerals found were P2O5, Cl, NiO, CuO, ZnO and PbO and mineralogical analysis by X-ray diffractometry revealed the presence of 83% barite, 4% quartz and 14% siderite from the head sample. Wet sieve analysis showed that at −600 + 300-µm- and −150 + 75-µm-sieve size, the SG was slightly above 4.2 g/cm3 meeting the API requirements. The results obtained from the heavy liquid separation (HLS) using TBE (2.95 g/cm3) indicated that mineral liberation occurs at (−600 + 300 µm and −300 + 150 µm), with specific gravities of 4.35 g/cm3 and 4.48 g/cm3, respectively. In the sink fraction (−300 + 150 µm) of the HLS, there were 82% barite, 2% quartz and 17% siderite, while in the float fraction 9% barite, 64% quartz, 2% siderite, 12% feldspar and 14% microcline were found. The results indicate that Azara barite ore meets up with the API requirement for drilling mud and has provided relevant mineralogical information to be used to design mineral processing.

A alexandrita natural (BeAl2O4:Cr3+) é um mineral amplamente encontrado no Brasil e tem sido investigada para atuar como um detector de radiação ionizante (dosímetro) com o uso da técnica da termoluminescência (TL). A utilização de materiais naturais na área, é interessante pelo seu menor custo comparado aos sintéticos, além da possibilidade de atuarem na dosimetria retrospectiva. Diferentes características das curvas TL de sete amostras foram investigadas, como a linearidade, homogeneidade, repetibilidade e fading. As amostras foram irradiadas com doses entre 0,5 – 5 Gy, utilizando uma fonte beta de 90Sr/90Y. Os resultados demonstram que a curva TL segue o mecanismo cinético de primeira ordem, além de possuir uma dose-resposta linear, boa repetibilidade e estabilidade do sinal em temperatura ambiente para até 33 dias de armazenamento após a dose. O ajuste também revelou cinco picos nas temperaturas 355, 405, 445, 530 e 585 K (taxa de aquecimento de 1 K/s). A caracterização química constatou que as amostras utilizadas são predominantemente formadas por alexandrita com uma porção significativa de fases apatita. Em geral, os resultados trazem características desejáveis dos materiais dosimétricos, sugerindo que a alexandrita tem potencial de aplicação na área.

Resumo O principal desafio quanto ao uso dos agregados reciclados de concreto (ARC) como materiais de construção de alto desempenho refere-se à pasta de cimento remanescente de construções anteriores que permanece aderida na superfície dos agregados naturais. As propriedades do ARC podem ser aprimoradas com a seleção de equipamentos de cominuição capazes de promover a liberação entre essa zona de interface, todavia os métodos de britagem são pouco abordados na literatura científica. O presente trabalho visa contribuir para a mudança nesse cenário ao comparar as propriedades de ARC cominuídos em britadores de mandíbulas e de impacto, ambos ajustados a fim de gerar um produto com distribuição granulométrica equivalente. O resultado foi a obtenção de agregados reciclados semelhantes em termos de morfologia de partículas, composição química e mineralógica, de modo que se pode concluir que a liberação da pasta de cimento residual em ambas as rotas de britagem foi análoga. Essa similaridade entre as propriedades confronta a crença comum de que o britador de impacto gera um produto com menor teor de pasta de cimento aderido e com finos excessivos. Abstract The main challenge regarding the use of recycled concrete aggregates (RCA) in high-performance building materials refers to the remaining cement paste from previous constructions that remains attached to natural aggregates surface. The properties of RCA can be improved through the selection of comminution equipment capable of promoting release in this interface zone. However, crushing methods are rarely discussed in the scientific literature. This paper aims to contribute to change this scenario, comparing the properties of RCA crushed by jaw and impact crushers, both adjusted in order to generate a product with the same granulometry. The result obtained was a similar product in terms of particle shape, and chemical and mineralogical composition, leading to the conclusion that the liberation of the residual cement paste on both crushing methods was analogous. This similarity between properties challenges the common belief that the impact crusher generates a product with lower grade of adhered cement paste and excessive fines.

Exposure of geomaterials to acidic leachates may compromise their structure and functionality due to changes in physicochemical, mineralogical, and hydraulic behavior. The literature identifies the need to evaluate changes in a pure state and in conditions of extreme acidity. This study aimed to evaluate changes in the chemical, mineralogical, and morphological properties of Osorio fine uniform sand (OFS), basalt residual soil (BRS), kaolin (KAO), and bentonite (BEN) exposed to sulfuric acid in concentrations of 0.00 mol/L (distilled water), 0.01 mol/L, and 1.00 mol/L. The tested samples were characterized using X-ray fluorescence spectrometry, X-ray diffraction, thermogravimetry, differential scanning calorimetry, and scanning electron microscopy. The acid attack on geomaterials by contact with the solution 1.00 mol/L has resulted in the solubilization of some constituent minerals, as well as the formation of sulfate minerals, changes in the water dehydration peak in the pores, and mass loss. The morphology of the sand and bentonite particles did not change with exposure to sulfuric acid. The acidic attack resulted in changes in the morphology of the particles for BRS and KAO. The results of this study are important for determining operational parameters of waste containment systems and contaminated areas, as well as for applying geomaterials as founding materials.

The wettability of reservoir rocks is one of the critical, advanced petrophysical parameters affecting oil production, during the field production life, from primary to enhanced recovery projects. This paper addresses the effect of mineral heterogeneities on wettability behaviour by measuring the contact angle (CA) on carbonate rock core samples from a Brazilian pre-salt reservoir. Mineralogical composition and mineral maps of samples extracted from reservoir plugs were characterised by X-ray based image analysis (scanning electron microscope coupled with automated mineral liberation analysis - SEM-MLA). The results indicated that around 99% of the samples were composed of calcite, dolomite, and quartz with completely different mineral distribution and texture. Also, the attained mineral maps directed the obtention of samples containing different mineral contents in which CA measurements were carried out by using the sessile drop method. CA experiments were run at a temperature of 60 °C and a pressure of 4000 psi with no-aged and aged samples in dead oil. Self-organised maps, generated by machine learning, were used to analyse the relationships between the variables. The results indicate that the predominant mineral constituents and their distribution influence the contact angle values and emphasise the importance of using reservoir core samples and their closest analogues when approaching rock/fluid interaction studies. Despite the samples with higher quartz content showing a greater water-phase affinity than carbonate ones, when both phases are inter-grown, wettability was changed to neutral and oil-wet. In this way, the mineral proportions and texture play a key role in the measured CA. Dolomite contributes to increasing the oil-wet tendency of the rock samples. Mineral maps are not currently applied in wettability studies but demonstrate that it can be a valuable tool for more reproducible measurements and a better understanding of the reservoir.

Geochemical analyses can provide multiple analytical variables. Accordingly, the generation of large geochemical databases enables imputation studies or analytical estimates of missing values or complex measuring. The processing of bauxite is a key step in the production of aluminum, in which the determination of Reactive Silica (RxSiO 2 ) and Available Alumina (AvAl 2 O 3 ) are very relevant. The traditional analytical method for achieving RxSiO 2 has limitations associated with poor repeatability and reproducibility of results. Based on the values from the unsupervised Self-Organizing Maps technique, this study aims to develop, systematically, the imputation of missing grades of the geochemical composition of bauxite samples of a database from three trial projects, for the variables: total Al 2 O 3 ; total SiO 2 ; total Fe 2 O 3 ; and total TiO 2 . Each project was submitted to partial exclusion of AvAl 2 O 3 and RxSiO 2 values, in proportion of 20%, 30%, 40% and 50%, to investigate the SOM technique as imputation method for RxSiO 2 and AvAl 2 O 3 . By comparing the imputed values from the SOM analysis with the original values, SOM technique demonstrated to be an imputation tool capable of obtaining analytical results with up to 50% of missing data. Specifically, the best results demonstrate that AvAl 2 O 3 can be obtained by imputation with a higher correlation than RxSiO 2 , based on the parameters and variables involved in the study. Similarity in the nature of samples and an increase in the number of embedded analytical variables are factors that provided better imputation results.

A crescente demanda por estanho no cenário mundial vem promovendo maior interesse no estudo de mineralizações primárias e mais complexas. Nesse contexto, estudos de caracterização tecnológica foram efetuados em duas amostras (sulfetada e oxidada), provenientes do norte do Brasil, Estado de Rondônia, com o objetivo de verificar as características da cassiterita e dos sulfetos presentes e suas associações com a ganga. Os estudos envolveram análises granulométricas, separações minerais e estudos de mineralogia quantitativa por microscopia eletrônica de varredura (MEV/EDS) utilizando análise de imagens automatizada (Mineral Liberation Analyser - MLA), possibilitando a obtenção da composição mineral, as características de associação e de liberação dos minerais de interesse e a partição dos elementos químicos nos minerais portadores. Os resultados indicam que as amostras têm teores semelhantes de estanho e de zinco e a mesma assembleia mineralógica, variando apenas a proporção relativa entre os minerais presentes. O grau de liberação da cassiterita para o material cominuído abaixo de 3,36 mm é da ordem de 40 a 50%. Os estudos sugerem que o processamento da cassiterita poderia ser efetuado em duas etapas de cominuição conjugados com concentração gravítica; os mistos e rejeitos, a depender dos teores de Sn e Zn, poderiam ser remoídos para a recuperação da esfalerita por flotação, obtendo-se ainda um eventual concentrado acabado de estanho.

This study proposes a new method of selective dissolution of calcium from C-S-H and CH phases by deionized water to evaluate the cement paste content in recycled concrete aggregates (RCA). The selective dissolution tests were carried out in standard phases of hydrated cement paste (HCP), calcite, dolomite and quartzite sand, and mixtures simulating RCA containing 1,5,10,20% HCP. The materials were characterized by X-ray diffractometry, thermal analysis, Raman and infrared spectroscopic analyzes, chemical analysis and laser diffraction analysis. Materials characterization indicates good selectivity of the deionized water in the calcium dissolution of the CH and C-S-H compared to limestone.

Plugs are cylindrical rocks with known dimensions that are extracted typically from reservoir formations with representative mineralogical compounds, petrophysical properties and oilfield fluids. They are used in the laboratory to understand the behaviour of oil in reservoirs. One of their applications is to study the screening of chemicals, such as surfactants and polymers, for enhanced oil recovery research before being applied in the reservoir. Many of Brazil’s pre-salt basins are located in ultra-deep waters, and the high heterogeneities of its offshore carbonate reservoirs make the extraction of representative rock samples difficult, risky and expensive. The literature reports the construction of synthetic plug samples that reproduce rocks as an alternative and viable solution for this issue. However, there is a lack of publications that focus on the construction of representative carbonate plugs that considers both the mineralogical composition and petrophysics properties, such as porosity and permeability. In this work, the construction of synthetic plugs is studied, using a combination of published methodologies to achieve an alternative construction of synthetic carbonate plugs for laboratory scale studies. Using a procedure based on the use of pulverized rock matrices with known particle sizes, uniaxial compaction, and probable CaCO3 solubility control by changing temperature and pH, it was possible to obtain synthetic carbonate plugs with a similar mineralogy to the natural carbonate reservoir. However, further studies are necessary to obtain more controlled petrophysical properties of such samples.

Os Resíduos de Construção e Demolição (RCDs) representam cerca de 50% dos resíduos sólidos de cidades brasileiras; a reciclagem é, portanto, desejável, tanto do ponto de vista econômico, como ambiental. Nesse trabalho são apresentados resultados de estudos de caracterização química referentes a amostras de duas usinas de reciclagem do Estado de São Paulo. Verificou-se que a classificação corrente do RCD, segundo critérios visuais (tipos cinza e vermelho), não está relacionada à composição química destes, sendo esta influenciada, principalmente, pela granulometria. A composição química dos RCDs varia em função dos conteúdos de pasta de cimento, tipos dos agregados naturais (areia quartzosa ou granito), cerâmica vermelha e argila. Ainda, para a reciclagem dos resíduos como agregados para concretos, são necessários dois estágios de britagem para atendimento às normas ABNT. A fração miúda apresenta um enriquecimento nos teores de sílica, indicando liberação da pasta de cimento para os finos (< 0,15 mm). Os finos têm aplicações potenciais na indústria de cimento. Construction and Demolition Waste (CDW) represents about 50% of the total Brazilian municipal solid waste; thus, recycling represents huge benefits both in environmental and economic perspectives. Herein, the chemical characterization results of three samples from two different recycling plants from the State of Sao Paulo is prevented. The results demonstrated that the visual classification into grey and red is not related to the chemical composition but mostly to the grain size fraction. The chemical composition of the CDW varies according to the content of cement paste, natural aggregates (quartz sand or granite), red ceramic and clay. Furthermore, the production of recycled concrete aggregates requires two crushing stages to meet the technical standards. The sand fraction (below 4.8 mm) presents high grades of SiO2, which indicates the liberation of cement paste to fines (< 0.15 mm). The fines have a great potential to be used in the cement industry.

A análise de imagens automatizada tem importante papel no setor mineral principalmente pela rapidez das análises, robustez estatística e confiabilidade dos resultados. A técnica pode ser realizada por meio de imagens adquiridas em microscópio eletrônico de varredura (MEV), geralmente associada a microanálises químicas por EDS e podendo ser utilizada em diversas etapas de um empreendimento mineiro. Este estudo teve como objetivo a caraterização tecnológica de minério de ouro da mina Morro do Ouro, Minas Gerais na qual foi utilizado a técnica de análise de imagens automatizada por MLA (do inglês, Mineral Liberation Analyser). Foi possível identificar os grãos de ouro, determinar seu tamanho, forma de ocorrência e acessibilidade diante três tipos de corpos de minério delineados em relação aos seus teores de arsênio.

Os resíduos de construção e demolição (RCD) representam cerca de 50% de todo o resíduo sólido gerado, sendo que cerca de 90% deste é de origem mineral e pode ser reciclado através de processos de beneficiamento mineral. Para se atingir a reciclagem massiva torna-se imperativo o desenvolvimento de novos mercados e melhorias de usina capazes de tornar o resíduo uma matéria prima de qualidade adequada. Dessa forma a caracterização tecnológica é imprescindível para obtenção de informações fundamentais sobre o processo de beneficiamento e as especificações para os produtos. O programa experimental foi desenvolvido em três amostras de RCD britados de duas usinas de reciclagem do Estado de São Paulo, Itaquera cinza (IT-C), Itaquera vermelho (IT-V), Vinhedo vermelho (VI-V). As atividades desenvolvidas foram: amostragem, cominuição, determinação das composições químicas e mineralógicas por faixa granulométrica, determinação de propriedades físicas relevantes para reciclagem de RCD como agregados para uso em concreto, determinação das curvas de separabilidade por densidade e análise de sua composição química e mineralógica e estudos microscópicos para avaliação do teor de aglomerantes por faixa densitária. Os resultados de análises químicas mostram que as composições químicas das três amostras são semelhantes; os teores variam com a granulometria, com marcantes diferenças na fração mais fina. A composição mineralógica predominante é de silicatos, provenientes de agregados e rochas naturais, cerâmicas e aglomerantes, com menores teores de alumina e óxido de cálcio; a perda ao fogo está diretamente relacionada ao teor de aglomerantes, uma vez que representa a água combinada e o gás carbônico presente. A separação do RCD em classes de densidade permitiu identificar que os produtos obtidos apresentam composições diferentes e pode ser empregada para se obter agregados de melhor qualidade e, portanto, para aplicações mais nobres, uma vez que se verifica que cerca de 80% em massa dos resíduos possuem densidades superiores a 2,2 g/cm3 com qualidades físicas adequadas para uso em concreto estrutural. Adicionalmente, a massa específica aparente e absorção de água estão diretamente relacionadas com os intervalos de densidade. O teor de aglomerantes aumenta significativamente para os produtos de menor densidade, sendo que as partículas cerâmicas estão isentas de pasta de cimento endurecida e cal. Construction and demolition waste (CDW) represents around 50% of the total solid waste and are essentially constituted by mineral fraction (>90%); therefore it?s possible to recycle it through mineral processing techniques. The development of different uses and the improvement of the typical technologies applied to CDW recycling are essential to achieve a satisfactory level of recycling. Applied mineralogy tools are fundamental to characterize the studied raw material and support the mineral processing in order to obtain products according to its specifications. This research was carried out in three crushed samples from two different plants close to Sao Paulo; they were named according to its classification: grey Itaquera (IT-C), red Itaquera (IT-V) and red Vinhedo (VI-V). The method involved basically sampling, crushing, characterization of the relevant physical properties for a concrete recycled aggregate approach, evaluation of the specific gravity separability curves and chemical and mineralogical analyses for each grain size fraction and gravity classes, and so microscope analyses to verify the binder contents. The results show that the chemical composition of the three samples is very similar, the grades change according to the grain size fractions, specially for the finest fraction. The mineral composition is also quite akin, it is mostly represented by silicates (mainly aggregates and natural rocks), ceramics and binder; minor amounts of Al2O3 and CaO were also detected. The loss of ignition is directly related to the binder and clay minerals (basically OH and CO2). Specific gravity classes are very different regarding their chemical, mineralogical and physical properties, despite their similarity among the samples. Thus the specific gravity separation is more effective to classify the recycled CD debris than its color and could be applied to obtain high quality recycled aggregates, while a significant amount (80%) is recovered above 2.2 g/cm3 and may be used as high strength concrete aggregates. In addition, the physical properties, like specific gravity and water absorption are strictly related to the specific gravity classes.