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| VARAJÃO,CÉSAR A.C.; BRUAND,ARY; RAMANAIDOU,ERICK R.; GILKES,ROBERT J.. |
| Massive hematite ore (MHO) is a special high-grade iron ore, used as lump ore in the process of obtaining direct reduction iron (DRI). The influence of porosity on the reducibility of MHO from the Capitão do Mato Mine (Iron Quadrangle, Brazil) was investigated using optical and scanning electron microscopes on drill core and open pit samples. Hematite is the main component of the samples and occurs as granular crystals (10 mum), microplates (1 mum) and euhedral martite (10 to 30 mum). Quartz, maghemite, kenomagnetite and goethite are minor components. Primary micropores (Å to 1 mum) are associated with microplaty crystals that fill cavities between granular hematite. Secondary micropores (Å to 5 mum) related to euhedral martite crystals, are the most... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: BIF; Porosity; Massive hematite ore; Direct reduction iron; Reducibility. |
| Ano: 2002 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652002000100008 |
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| MATTEUZZO,MARCELA C.; VOLKMER-RIBEIRO,CECÍLIA; VARAJÃO,ANGÉLICA F.D.C.; VARAJÃO,CÉSAR A.C.; ALEXANDRE,ANNE; GUADAGNIN,DEMETRIO L.; ALMEIDA,ARIANA C.S.. |
| ABSTRACT Adverse natural conditions will, generally, induce gemmulation in freshwater sponges. Because of this environmental dependence, gemmoscleres are given exceptional value in taxonomic, ecological and paleoenvironmental studies. Other spicules categories such as microscleres and beta megascleres have received little attention with regard to their occurrence and function during the sponge biological cycle. Metania spinata, a South American species common to bog waters in the Cerrado biome, produces alpha and beta megascleres, microscleres and gemmoscleres. To detect the environmental factors triggering the production of all these kinds of spicules, the species annual seasonal cycle was studied. Artificial substrates were devised, supplied with... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Field monitoring; Metania spinata; Paleointerpretations; Spicules. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652015000502013 |
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