Ana Claudia Queiroz Ladeira

Centro de Desenvolvimento da Tecnologia Nuclear | CDTN · Mineral Technology

This paper investigates the occurrence of natural attenuation in sediments from a water reservoir impacted by metals and radionuclides resulting from acid mine drainage. The chemical and radiochemical characterization indicated the enrichment of radionuclides (238U and 226Ra) and metals (Zn) in the sediments. The isotopic deviation δ34S (− 1.3 to −...

This work investigates the use of chelating resins for recovering rare earth elements (REE) from a laboratory solution with pH and sulphate concentrations similar to those of an acid mine drainage (AMD). The loading experiments were performed in ion exchange columns, fed with a solution at pH 3.5 containing 0.49 g L-1 of REE, 0.06 g L-1 of impuriti...

The ion exchange process for the recovery of rare earth elements (REE) from acid waters is investigated through combined experimental and theoretical approaches. Loading and elution experiments using a strongly acidic cation resin were carried out batchwise and in columns by applying laboratory solutions as well as crude acid mine drainage (AMD). L...

Considered critical and strategic, the rare earth elements (REE) can be found in ores as well as in secondary sources such as acid mine drainage (AMD). The present work studies the ion exchange process to recover and separate the REE present in a solution similar to an acid mine effluent containing La, Pr, Nd, Sm, Eu, Gd, Dy, Er, metal impurities (...

The scavenging of soluble metals by iron (Fe) and aluminium (Al) oxyhydroxides is a natural process that occurs in acid mine drainage (AMD). This phenomenon is relevant to the immobilization, transport, and recovery of important natural resources such as rare earth elements (REE) and uranium (U). Furthermore, understanding the players and the react...

Lubricating oils in nuclear power plants may be contaminated with radionuclides and become a challenging radwaste for treatment as they decompose in storage and disposal and do not lend themselves to conventional cementitious stabilization methods. This work addresses the radwaste immobilization using geopolymer (alkaliactivated material), an innov...

The current work addresses the study of the recovery of rare earth elements (REE) from acid mine water by using cationic exchange resin. The acid water was obtained from a closed uranium mine in Brazil. Ion exchange experiments were carried out in batch with three different resins at 25±0.5 °C and pH values 1.4, 2.4 and 3.4 (natural). Data were adj...

Rare Earth Elements (REE) are crucial to the development of new technologies, given their strategic importance, a wide range of actions has been implemented to ensure sustainable and affordable supplies. Acid Mine Drainage (AMD) besides being one of the major environmental issues faced by the mining industry is a naturally occurring process involvi...

Radionuclides may contaminate lubricant oils in nuclear power plants. In Brazil, this kind of waste has been stored in the generator’s facilities, awaiting treatment alternatives. This work intends to investigate a process to treat it for final deposition, using bentonite as sorbent material. This process will result in decontaminated oil, free fro...

Many approaches have been proposed to remove manganese from public supply waters as well as from acid mine drainage. This study investigated the removal of high levels of soluble Mn (II), similar to forms found in acid mine drainage in Brazil, by using a manganese oxide (MnO2) residue from the electrowinning process and a Bacillus cereus strain iso...

Acid mine drainage (AMD) is one of the main environmental issue caused by chemical and bacterial oxidation of pyrite (FeS2) and other sulfite minerals when exposed to atmospheric conditions during mining. In Brazil, AMD occurs in a former uranium mine and contains radionuclides and other elements, which are precipitated from acidic water by liming....

Radionuclides may contaminate lubricant oils in nuclear power plants. In Brazil, this kind of waste has been stored in the generator’s facilities, awaiting treatment alternatives. This work intends to investigate a process to treat it for final deposition, using bentonite as sorbent material. This process will result in decontaminated oil, free fro...

The carbonaceous matter present in some gold ores adsorbs the gold cyanide complexes from the leached solution and transport them to tailings, resulting in loses and preventing the recovery of the metal – a phenomenon known as preg-robbing. The present work aims at evaluating the capacity of 8 blinding additives to deactivate/passivate the carbonac...

Uranium speciation and its complexes are an important environmental issue mainly when it is associated with acid rock drainage (ARD). Ion exchange resins are the most appropriate technology for the removal of low levels of uranium from highly concentrated sulfate solutions. The chemical speciation of uranium/sulfate system indicates that the predom...

O presente trabalho busca simular a atividade preg-robbing da matriz carbonosa de minérios auríferos a partir de carvões minerais de diferentes níveis de maturação (antracito, betuminoso e lignito), a fim de avaliar a aplicabilidade e a funcionalidade de oito aditivos químicos em desativar/passivar a matéria carbonosa responsável por adsorver o our...

Abstract The preferred option for disposal of short-lived low and intermediate level radioactive wastes is a near surface disposal facility in which soil is one of the barriers that avoid radionuclide migration outside the controlled area. For construction of that kind of facility, concrete is widely used, and its interaction with water induces its...

To be used as backfilling materials in radioactive waste disposal facilities, a natural material must have a suitable permeability, mechanical properties and a high sorption capacity for radionuclides. Also important when considering a material as a backfill is the effect of its interaction with the alkaline solution generated from concrete degrada...

This work aimed at separating Zr(IV) from Hf(IV) from an acid solution using cationic resin through column experiments. The influence of different inorganic acids in the loading of the resin as well as different organic and inorganic eluents such as hydrochloric, sulfuric, citric and oxalic acids were evaluated. The loading of Zr varied from 1.14 t...

A área de estudo relaciona-se com o Complexo Mínero Industrial do Planalto de Poços de Caldas (CIPC), gerador de um efluente ácido que, após tratado, é descartado na Represa de Águas Claras que devido à ineficiência do processo de precipitação e subdimensionamento dos tanques de decantação, tem atuado como uma espécie de bacia de retenção dos conta...

This work presents the investigation in an environment that contains uranium deposits by using Pb isotope signatures. The study area, southeast of Brazil, is characterized by the lack of surface water and, as a consequence, the groundwater plays an important role in the economy of the region, such as the supply to the uranium industry and, above al...

Amostras de solo provenientes de Minas Gerais (Brasil) foram investigadas quanto à capacidade de sorção de césio (Cs) com vistas a aplicação destes como material de enchimento em um repo-sitório para deposição de rejeitos radioativos de médio e baixo nível de atividade. Foram avaliadas cinco amostras de solo quanto à capacidade máxima de sorção de...

Purpose The present study investigated lake and river sediments affected by metals from an acid mine drainage (AMD) from a former uranium mine. The role of bacterial sulfate reduction in the immobilization of contaminants was evaluated, and the analyses of acid volatile sulfide (AVS) and sequential extraction were performed. Consequently, the poten...

Purpose: The present study investigated lake and river sediments affected by metals from an acid mine drainage (AMD) from a former uranium mine. The role of bacterial sulphate reduction in the immobilization of contaminants was evaluated and analyses of acid volatile sulphide (AVS) and sequential extraction were performed. Consequently, the potenti...

In the present study, continuous fixed bed column runs were carried out in an attempt to evaluate the feasibility of using bone char for the removal of manganese from acid mine drainage (AMD). Tests using a laboratory solution of pure manganese at typical concentration levels were also performed for comparison purposes. The following operating vari...

Existem quatro isotopos naturais de Pb, tres dos quais, 206Pb, 207Pb e 208Pb, sao, respectivamente, os produtos finais estaveis provenientes dos decaimentos radioativos do 238U, 235U e 232Th. Na natureza, ocorre um quarto isotopo nao radiogenico, o 204Pb, cuja abundância nao e afetada pelo decaimento radioativo do U ou do Th, sendo considerada cons...

A possibilidade de remoção de manganês contido em efluentes de mineração de elevada concentração, i.e., até 140mg/L, foi estudada através de adsorção em carvão ativado. Inicialmente, foi feito um tratamento térmico no carvão em duas temperaturas distintas, com o intuito de avaliar a importância dos sítios de adsorção no processo. Os ensaios de adso...

O zircônio e o háfnio são dois importantes metais para a indústria nuclear. O háfnio ocorrer em todos os minérios de zircônio na faixa de 2 - 3%. Entretanto, o uso do zircônio na indústria nuclear exige que o háfnio esteja em concentrações menores que 100 mg Kg-1. O atual trabalho consiste na separação do par zircônio e háfnio pelo método de troca...

In recent years, much attention has been devoted in developing inexpensive or alternative systems for treating acid mine drainage (AMD). Manganese is a common component of AMD, and it is traditionally removed by precipitation. However, in order to meet the standard limits for discharging, usually −1, it is necessary to raise the pH above 10 which i...

Sediments of the São Francisco River basin (Brazil) were investigated to determine the environmental consequences of incorrect disposal of wastes generated by a zinc industry. Surface sediments were characterized by X-ray diffraction (XRD) and chemically analyzed by X-ray fluorescence (XRF). Total organic carbon (TOC), acid volatile sulfides (AVSs)...

Although oxidative precipitation by potassium permanganate is a widely recognised process for manganese removal, research dealing with highly contaminated acid mine drainage (AMD) has yet to be performed. The present study investigated the efficiency of KMnO4 in removing manganese from AMD effluents. Samples of AMD that originated from inactive ura...

Acid mine drainage in the uranium mine at the Caldas Municipality (MG) has been occuring for over 20 years. This drainage has a pH of around 3.0 and contains metals and non-metals. The current acid water treatment uses lime to increase the pH and precipitates the contaminants before discharging the water into the environment. This procedure generat...

Ettringite-gypsum sludge, formed by neutralization of acid mine drainage with lime, has been stored temporarily in the open pit of a uranium mine that floods periodically. The present study characterized samples of this sludge, named according to the time of placement as Fresh, Intermediate, and Old. Standard leaching and sequential extraction proc...

Waste materials, stored in inappropriate places, are one of the most significant environmental issues concerning mining activities. In Brazil, one closed uranium mine has faced such a problem. The waste, produced during the neutralization of acid drainage and containing several metals including uranium, has been disposed into the mine opening as a...

The nuclear fuel cycle comprises a series of industrial processes which involve the production of electricity from uranium in nuclear power reactors. In Brazil the conversion of uranium hexafluoride (UF6) into uranium dioxide (UO2) takes place in Resende (RJ) at the Nuclear Fuel Factory (FCN). The process generates liquid effluents with significant...

Acid mine drainage (AMD) is one of the main environmental issues faced by the mining industry. The acid mine water generally contains metals above the permissible discharging levels. Manganese is particularly present in this effluent and its removal is notoriously difficult due to its high solubility over a wide range of pH. While most of the metal...

The work aimed at the characterization of wastes and liquid effluents from galvanizing industry in order to identify the main elements responsible for their toxicity and the classification of the residues as hazardous or non hazardous. The characterization of the samples showed that Zn and Fe are the predominant elements. However, elements like Ni,...

The work aimed at the characterization of wastes and liquid effluents from galvanizing industry in order to identify the main elements responsible for their toxicity and the classification of the residues as hazardous or non hazardous. The characterization of the samples showed that Zn and Fe are the predominant elements. However, elements like Ni,...

This work is aimed at the selection of an appropriate adsorbent for uranium and manganese present in acid mine water drainage. The pH of the acid water is around 2.7, the uranium concentration is in a range of 9-15mg/L, the manganese concentration approximately 170mg/L and the sulphate concentration is near 2000mg/L. The uranium in this solution, w...

Uranium extraction can be accomplished by polymeric ion exchange resin or solvent extraction. The choice of the technique and type of extradant depend on the uranium concentration and the presence of other ions in aqueous medium. In solutions with low uranium concentration, polymeric resin is more suitable. However, in solutions with high uranium c...

The presence of uranium and other elements in high concentrations in acid mine drainage at Poços de Caldas Uranium Mine (Brazil) is a matter of concern. The acid water pH is around 2.7, the uranium concentration is in the range of 6-14 mg L(-1), sulfate concentration near 1400 mg L(-1), fluoride 140 mg L(-1) and iron 180 mg L(-1). In this solution,...

The present paper aims at the recovery of uranium present in an alkaline solution. This solution was generated by the nuclear industry and contains uranium [40mg/L], ammonium [80g/L], carbonate [170g/L] and fluoride [0.35g/L]. Ion exchange technique was employed for uranium recovery. The first step consisted in using laboratory solutions and batch...

It is well known that As(III) has a higher mobility compared to As(V) in the environment. This fact is explained by the high reversibility of As(III) adsorption on minerals such as Al (hydr)oxides. Nevertheless, experimental results pointed out that adsorption of As(III) leads to innersphere complexes, which appears to be in conflict with the high...

One of the most serious environment problems created by the mining industry is acid mine drainage. In one plant of Nuclear Indus-tries of Brazil—INB, this problem is a matter of concern. The presence of iron sulfites, such as pyrite, generates water with acidity above the levels allowed by the legislation and therefore, inappropriate for releasing...

The recovery of uranium from nuclear industrial effluent has been studied using laboratory column and polymeric ion exchange resin. The industrial effluent, at pH around 10, contains uranium (40 mg/L), ammonium (80 g/L) and carbonate (170 g/L) and cannot be discharged without previous treatment. Uranium is in the form of uranyl quadrivalent complex...

Uranium in solution can be precipitated over a wide pH range, from acidity and alkalinity, depending upon the solution and the precipitant used. The precipitate is generally filtered and the solution resultant contains uranium that should be recovered. This work is aimed at the selection of an appropriate resin for uranium recovery from alkaline so...

The present work investigates the adsorption and mobility (desorption) of As(III) and As(V) on an oxisol, and its main mineral constituents, as part of a broader project aimed at selecting a soil liner to be used in tailings dams at a sulfidic gold ore plant. Emphasis was given to a quantitative comparison of As mobility-here assessed by the amount...

Esse trabalho consistiu da realização de estudos comparativos da capacidade de retenção de arsênio de 3 amostras de solos do Estado de Minas Gerais e de 1 amostra de rejeito de minério aurífero oriundo da mina do Morro do Ouro, da Rio Paracatu Mineração S.A. A capacidade de retenção foi avaliada com base no levantamento de isotermas, através das qu...

X-ray absorption fine structure spectroscopy and density functional calculations were used to determine the structural model of arsenic surface complex on gibbsite mineral. The structural environment of arsenic at the solid surface may determine its potential for remobilization and stability. Data were collected for arsenate adsorbed on gibbsite su...

The work investigated the use of a ferruginous clay material for removal of arsenic, in both trivalent and pentavalent valence states, from aqueous solutions. Sorption was well described by a Langmuir type equation. Maximum uptake with respect to As (V) was 3mg/g of clay and occurred at pH 2; for As(III), maximum removal was in the range of 4-5mg/g...

This work presents a comparative characterization of five samples of activated carbon and a kinetic evaluation of gold adsorption from diluted cyanide solutions. The characterization was aimed at determining and quantifying some physical and chemical properties considered important for adequate performance of carbon in gold plants. The kinetic stud...

This work aims at evaluating Al-based adsorbents (gibbsite and calcined gibbsite) for arsenic removal in water treatment. The thermal treatment consisted in the calcination in temperatures from 70 and 400°C. Both the specific surface area and the adsorption capacity were found to increase up to 20 and 10 times, respectively, as a result of the trea...

In southeastern Brazil, a closed uranium mine produces acid mine water at pH 2.7 which contains significant concentrations of uranium and other elements like manganese, sulfate, iron and zinc. The contaminants are removed from the acid water to acceptable limits through precipitation of the elements using lime. The precipitation procedure has been...