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Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides 来自Buriti dos Montes的橙色蛋白石，Piauí:作为遗传指南的固体内含物
Rem-Revista Escola De Minas Pub Date : 2015-03-01 DOI: 10.1590/0370-44672015680203
G. T. Marques, M. Costa, Érico Rodrigues Gomes
{"title":"Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides","authors":"G. T. Marques, M. Costa, Érico Rodrigues Gomes","doi":"10.1590/0370-44672015680203","DOIUrl":"https://doi.org/10.1590/0370-44672015680203","url":null,"abstract":"As opalas laranjas de Buriti dos Montes (Piaui, nordeste do Brasil) tem propriedades gemologicas que favorecem seu uso como joias; essas caracteristicas incluem as cores, transparencia, dureza e estabilidade relativamente elevadas. O exotico conteudo de inclusoes solidas proporciona maior beleza as opalas da regiao. Essas opalas foram originadas por processos hidrotermais e sao encontradas, principalmente, em venulas e veios nos arenitos do Grupo Serra Grande, seccionados por soleiras e diques de diabasio da Formacao Sardinha. Inclusoes solidas, tais como bolhas, agregados botrioidais, dendritos e nodulos, entre outras, consistem, principalmente, de caulinita, hematita/goethita e quartzo e influenciam a composicao quimica das opalas. O zoneamento intenso dos cristais de quartzo e os elevados valores de Ba e Fe sugerem que os depositos de opala foram formados em ambiente hidrotermal. Os diques de diabasio teriam sido responsaveis pelo aquecimento dos fluidos hidrotermais. Os arenitos, ricos em solucoes aquosas, tambem teriam contribuido com a silica disponivel para a saturacao dessas solucoes e as fraturas permitiram a migracao e aprisionamento dos fluidos hidrotermais, resultando nos veios mineralizados.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"23 1","pages":"53-59"},"PeriodicalIF":0.0,"publicationDate":"2015-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85431677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
The effect of metakaolin on the durability of concrete hollow blocks used in masonry: evaluation of degradation caused by driving rain 偏高岭土对砌体用混凝土空心砌块耐久性的影响:暴雨引起的退化评价
Rem-Revista Escola De Minas Pub Date : 2015-03-01 DOI: 10.1590/0370-44672015680076
Maria Luiza de Souza Rezende, J. Nascimento, G. Neves, H. C. Ferreira
{"title":"The effect of metakaolin on the durability of concrete hollow blocks used in masonry: evaluation of degradation caused by driving rain","authors":"Maria Luiza de Souza Rezende, J. Nascimento, G. Neves, H. C. Ferreira","doi":"10.1590/0370-44672015680076","DOIUrl":"https://doi.org/10.1590/0370-44672015680076","url":null,"abstract":"Driving rain, considered one of the major factors in the degradation of external seals, may cause esthetic problems and material decomposition to facades and masonry. In the present research, the production of concrete hollow blocks for masonry underwent testing for which 20 years of exposure have been considered, taking into account the annual precipitation in the State of Paraiba. This was assessed by replacing 10, 15 and 20% of cement for metakaolin using as parameter the specimen’s mass loss at end of the test. It has was found that the concrete with metakaolin revealed values of weight loss greater than those of the reference concrete, without metakaolin, and that these values increased as the level of substitution increased. However, for mixtures with lower cement content, the use of 10% by metakaolin promoted results that have been considered similar to the reference. The test results are, therefore, consistent with those reported in literature for assessment studies on actual exposure situations; however, further studies will be developed to correlate the laboratory results obtained and from the resulting exposure to natural weather conditions.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"11 1","pages":"21-27"},"PeriodicalIF":0.0,"publicationDate":"2015-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89734986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Proposal of an environmental sustainability index for open-pit mines using landscape fragmentation indicators 利用景观破碎化指标构建露天矿环境可持续性指数
Rem-Revista Escola De Minas Pub Date : 2015-03-01 DOI: 10.1590/0370-44672015680160
F. V. Silva, R. Peroni
{"title":"Proposal of an environmental sustainability index for open-pit mines using landscape fragmentation indicators","authors":"F. V. Silva, R. Peroni","doi":"10.1590/0370-44672015680160","DOIUrl":"https://doi.org/10.1590/0370-44672015680160","url":null,"abstract":"The perception of the environmental impacts caused by economic activities is subjective and usually negatively affects the image of an extractive sector such as mining. In order to avoid this, the environmental impact assessment must be supported by clear and well-selected environmental indicators. An index of sustainability was created to demonstrate that open-pit mining is comparable to other economic activities. The index is composed by of environmental indicators like water and energy consumption combined with an indicator of landscape fragmentation, using remote sensing data and geoprocessing. A comparative study considering a ten-year period was carried out with the biggest iron ore mine in Brazil, N5W, and the largest Brazilian soybean producer, the Sorriso County, in the Mato Grosso State to illustrate the methodology.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"31 1","pages":"115-122"},"PeriodicalIF":0.0,"publicationDate":"2015-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75672543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Effect of solution heat treatment on the pitting corrosion behavior of a high Mn austenitic stainless steel in chloride solution 固溶热处理对高锰奥氏体不锈钢在氯化物溶液中点蚀行为的影响
Rem-Revista Escola De Minas Pub Date : 2015-03-01 DOI: 10.1590/0370-44672015680002
José Wilmar Calderón Hernandez, Duberney H. Ladino, C. Azevedo, N. A. Falleiros
{"title":"Effect of solution heat treatment on the pitting corrosion behavior of a high Mn austenitic stainless steel in chloride solution","authors":"José Wilmar Calderón Hernandez, Duberney H. Ladino, C. Azevedo, N. A. Falleiros","doi":"10.1590/0370-44672015680002","DOIUrl":"https://doi.org/10.1590/0370-44672015680002","url":null,"abstract":"The effect of solution heat treatment on the pitting corrosion resistance of 17Cr-6Mn-5Ni-1.5Cu austenitic stainless steel in 0.6M NaCl aqueous solution was evaluated. UNS S30403 (304L) steel was used as benchmark material. Solution heat treatments (SHT) were conducted at 1010°C, 1040°C, 1070°C and 1100°C. The microstructural characterization revealed the presence of δ-ferrite, especially in the asreceived condition (AR). The SHT decreased the proportion of the ferrite phase. Mnrich precipitates were observed in the as-received condition of 17Cr-6Mn-5Ni-1.5Cu steel, but they were dissolved after the SHT, causing localized Mn enrichment in the austenite. Potentiodynamic tests showed that the pitting potential (Ep) in the 304L steel was not altered significantly after SHT. On the other hand, the value of Ep of the 17Cr-6Mn-5Ni-1.5Cu steel decreased after SHT. This detrimental effect was explained by the formation of Mn enrichment areas due to the solubilization of Mn-rich precipitates, which promoted preferential Cl- adsorption in these regions.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"13 1","pages":"91-96"},"PeriodicalIF":0.0,"publicationDate":"2015-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81864578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Geochemical mapping of arsenic in surface waters and stream sediments of the Quadrilátero Ferrífero, Brazil 巴西Quadrilátero Ferrífero地表水和河流沉积物中砷的地球化学制图
Rem-Revista Escola De Minas Pub Date : 2015-03-01 DOI: 10.1590/0370-44672015680077
R. V. F. Costa, M. Leite, F. Mendonça, H. Nalini
{"title":"Geochemical mapping of arsenic in surface waters and stream sediments of the Quadrilátero Ferrífero, Brazil","authors":"R. V. F. Costa, M. Leite, F. Mendonça, H. Nalini","doi":"10.1590/0370-44672015680077","DOIUrl":"https://doi.org/10.1590/0370-44672015680077","url":null,"abstract":"A regional study on the arsenic concentration in surface waters and stream sediments, with a density of one sample every 13 km2, was carried out for the first time in the Quadrilatero Ferrifero (Brazil). The region was divided into 3rd order catchment basins, in which 512 areas were sampled. The arsenic concentration was determined in waters and stream sediments after partial digestion with the aid of ICP-OES. The arsenic values found in surface waters ranged from 57.70 to 414 µg.L-1, while for stream sediments, arsenic concentrations ranged from 0.63 to 1691 mg.kg-1, and from the 512 sampling points, 135 (26%) had arsenic concentrations above the limit of detection, which was 0.63 mg.kg-1. It was also found that 106 3rd order catchment basins had values above the third quartile, (5.09 mg.kg-1). The results show that high concentrations of this element are strongly related to the presence of Nova Lima rocks that contain minerals rich in arsenic. However, the anthropogenic influence in such high concentrations cannot be ruled out, as the region has a history of over 300 years of gold mining.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"45 1","pages":"43-51"},"PeriodicalIF":0.0,"publicationDate":"2015-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78925329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 17
Leaching of gold and silver from printed circuit board of mobile phones 从手机印刷电路板中浸出金和银
Rem-Revista Escola De Minas Pub Date : 2015-03-01 DOI: 10.1590/0370-44672015680152
Patrícia Melo Halmenschlager Petter, H. Veit, A. Bernardes
{"title":"Leaching of gold and silver from printed circuit board of mobile phones","authors":"Patrícia Melo Halmenschlager Petter, H. Veit, A. Bernardes","doi":"10.1590/0370-44672015680152","DOIUrl":"https://doi.org/10.1590/0370-44672015680152","url":null,"abstract":"Nowadays there is a wide variety of models, sizes and configurations of mobile phones available for consumption. After the life cycle of this equipment, the recycling and reuse of the precious metals found in the printed circuit boards (PCB) of the mobile phones are principal objectives. Thus, the objective of this work was to characterize the gold and silver present in a PCB and develop a recycling route using alternative reagents for cyanide, such as sodium and ammonium thiosulfate. These reagents are less harmful to the environment and worker health. The first characterization of gold and silver was performed with aqua regia. The results show 86.26g Au/ton of PCBs and 123.85g Ag/ton of PCBs. The second characterization was performed with a commercial cyanide-based reagent and 112.02g Au/ton of PCBs and 26.13g Ag/ ton of PCBs were obtained. A leaching study with solutions based on thiosulfate was performed and an extraction of 9.02g Au/ton of PCBs and 33.88g Ag/ton of PCBs was obtained, compared to characterization results using a cyanide-based reagent.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"1 1","pages":"61-68"},"PeriodicalIF":0.0,"publicationDate":"2015-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90727321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 23
Methodology to control the influence of processing factors during composite stone fabrication 控制复合石材加工过程中加工因素影响的方法
Rem-Revista Escola De Minas Pub Date : 2015-03-01 DOI: 10.1590/0370-44672015680208
F. Lameiras, Gláucia Danielle Leirose da Silva
{"title":"Methodology to control the influence of processing factors during composite stone fabrication","authors":"F. Lameiras, Gláucia Danielle Leirose da Silva","doi":"10.1590/0370-44672015680208","DOIUrl":"https://doi.org/10.1590/0370-44672015680208","url":null,"abstract":"Composite stone is made of crushed materials bound by a polymer resin. A design of experimental techniques was used to evaluate the influence of factors (resin type, use of adhesion promoter, compaction pressure, vibration duration, use of a vacuum, and cure program) on the manufacturing of composite stone. The response variable was flexural strength. A 2IV6-2 fractional factorial design with five replications was initially used, which showed that resin type, use of adhesion promoter, and a cure program were factors of significant influence, as well as the interaction between them and the interaction between the resin type and the use of adhesion promoter. The data was re-arranged into a full 23 factorial design with ten replications to calculate the influence of these factors. The lack of influence of the other factors suggests that lower pressures should be used to improve the process by employing the surface response methodology.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"7 1","pages":"69-75"},"PeriodicalIF":0.0,"publicationDate":"2015-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77257672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Mineral paste production from phosphate rock tailings 用磷矿尾矿生产矿物膏体
Rem-Revista Escola De Minas Pub Date : 2014-12-15 DOI: 10.1590/0370-44672015680103
André Carlos Silva, E. M. S. Silva, Â. S. S. Junior, João Paulo Aparecido Arruda, Vitor Rodrigues de Araújo Vaz
{"title":"Mineral paste production from phosphate rock tailings","authors":"André Carlos Silva, E. M. S. Silva, Â. S. S. Junior, João Paulo Aparecido Arruda, Vitor Rodrigues de Araújo Vaz","doi":"10.1590/0370-44672015680103","DOIUrl":"https://doi.org/10.1590/0370-44672015680103","url":null,"abstract":"The dewatering stage is among the most important industrial unit operations, and is widely adopted in many different industries. Nowadays, mineral processing tailings disposal is a big problem due to the environmental degradation it causes. The phosphate rock processing in Anglo American Phosphate Brazil, situated in Catalao/ Go/Brazil, generates around 180 t/h of tailings for a plant feed of 480 t/h (approximately 37.5% of the processing plant feed), with 5 to 10% of solids and approximately 14% of P2O5. Nowadays, the tailings are sent directly to the tailings dam. The present work proposes paste production using the tailings from the phosphate rock processing plant. Through decantation of a tailings sample, a clarified liquid was obtained and drained. The decanted pulp then went through a second stage consisting of vacuum filtration. Flocculant addition in this stage generated a faster sedimentation rate and a higher dewatering performance in next stage of dewatering, because the flocculated material was retained by the filter medium instead of passing through it. The results were satisfactory for paste tailings production with a solid percentage of around 65%.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"114 1","pages":"103-108"},"PeriodicalIF":0.0,"publicationDate":"2014-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72965812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
Fuzzy Algorithm of discontinuity sets 不连续集的模糊算法
Rem-Revista Escola De Minas Pub Date : 2014-12-01 DOI: 10.1590/0370-44672014670178
André Monteiro Klen, M. Lana
{"title":"Fuzzy Algorithm of discontinuity sets","authors":"André Monteiro Klen, M. Lana","doi":"10.1590/0370-44672014670178","DOIUrl":"https://doi.org/10.1590/0370-44672014670178","url":null,"abstract":"O agrupamento de descontinuidades em familias nem sempre e uma tarefa trivial, particularmente quando se utiliza apenas o diagrama de densidade de polos, metodo classico. Este e extremamente subjetivo, uma vez que o tamanho da area da celula de contagem, a sobreposicao de polos e a presenca de outliers entre as familias dificultam a definicao de suas caracteristicas. Nesses casos, e util a aplicacao de metodos numericos em consonância com o metodo classico. Para isso, esse trabalho propoe um algoritmo baseado no Metodo Fuzzy K-means, que permite reunir as descontinuidades em familias sem a influencia desses fatores. O algoritmo teve seus resultados comparados com dois conjuntos de fraturas estudados na literatura e demonstrou-se eficiente.","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"46 1","pages":"439-445"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83555463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
The effect of accumulation in 2D estimates in phosphatic ore 二维估算中磷矿聚集的影响
Rem-Revista Escola De Minas Pub Date : 2014-12-01 DOI: 10.1590/0370-44672014670179
D. Marques, R. Rubio, J. Costa, Evangelina Maria Apparicio da Silva
{"title":"The effect of accumulation in 2D estimates in phosphatic ore","authors":"D. Marques, R. Rubio, J. Costa, Evangelina Maria Apparicio da Silva","doi":"10.1590/0370-44672014670179","DOIUrl":"https://doi.org/10.1590/0370-44672014670179","url":null,"abstract":"The geological modeling of stratiform deposits can become very complex, often making use of geological envelopes of small thickness and requiring the use of subblocks (based on Cartesian coordinates) to produce a coherent block model. However, geological events after the formation of the deposit (folds, faults, etc.) can change the direction of spatial continuity of certain attributes, with the mixing of samples belonging to different formation eras (in the case of stratiform deposits) in the same elevation. This study presents a solution for deposits with stratigraphic grades combined with samples of different origins. The solution is a two-dimensional estimate obtained by accumulating the thicknesses of P 2 O 5 in a phosphate deposit (as compared to traditional statistical analysis in three dimensions).","PeriodicalId":54498,"journal":{"name":"Rem-Revista Escola De Minas","volume":"32 1","pages":"431-437"},"PeriodicalIF":0.0,"publicationDate":"2014-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87672619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
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