Characterization of ultra-fine grained aluminum produced by accumulative back extrusion (ABE)

AbstractFrom mineralogical and chemical characterization of two waste-rock piles from Vigonzano and Libiola sulphide mines in the northern Apennines, two types of fine-grained weathering products were recognized, One, from the Vigonzano mine, has a typical blue colour and consists of the Cu-Al sulphate of the woodwardite group. Its formation is related to an alkaline geochemical barrier, it is rather stable in acidic solution, and it controls Cu and Zn dispersion in the surrounding environment. The other group of sediments has a typical ochreous colour. Vigonzano samples consist mostly of goethite, whereas ferrihydrite is abundant in the Libiola sample. The ochreous sediments are enriched in Co, As, Mo, Se and Mn, thus significantly reducing the potential environmental hazard of the site, whereas solubility tests indicated possible problems due to AI dissolution at Libiola.

Download Full-text

Characterization of glacial silt and clay using automated mineralogy

Annals of Glaciology ◽

10.1017/aog.2019.45 ◽

2019 ◽

Vol 60 (80) ◽

pp. 49-65

Author(s):

Jeff W. Crompton ◽

Gwenn E. Flowers ◽

Brendan Dyck

Keyword(s):

Grain Size ◽

Size Composition ◽

Rock Properties ◽

Fine Grained ◽

Rock Fragments ◽

Grain Sizes ◽

Automated Mineralogy ◽

Log Normal ◽

Discrete Populations

AbstractGlacial erosion produces vast quantities of fine-grained sediment that has a far-reaching impact on Earth surface processes. To gain a better understanding of the production of glacial silt and clay, we use automated mineralogy to quantify the microstructure and mineralogy of rock and sediment samples from 20 basins in the St. Elias Mountains, Yukon, Canada. Sediments were collected from proglacial streams, while rock samples were collected from ice marginal outcrops and fragmented using electrical pulse disaggregation. For both rock fragments and sediments, we observe a log-normal distribution of grain sizes and a sub-micrometer terminal grain size. We find that the abrasion of silt and clay results in both rounding and the exploitation of through-going fractures. The abundance of inter- versus intragranular fractures depends on mineralogy and size. Unlike the relatively larger grains, where crushing and abrasion are thought to exploit and produce discrete populations of grain sizes, the comminution of fines leads to a grain size, composition and rounding that is continuously distributed across size, and highly dependent on source-rock properties.

Download Full-text

Scaling property of ideal granitic sequences

Nonlinear Processes in Geophysics ◽

10.5194/npg-14-237-2007 ◽

2007 ◽

Vol 14 (3) ◽

pp. 237-246 ◽

Cited By ~ 3

Author(s):

D. Xu ◽

Q. Cheng ◽

F. Agterberg

Keyword(s):

Lake Area ◽

Fine Grained ◽

Multi Scale ◽

Invariance Properties ◽

The Past ◽

Ideal Granite ◽

Markov Properties ◽

The Ideal

Abstract. Quantification of granite textures and structures using a mathematical model for characterization of granites has been a long-term attempt of mathematical geologists over the past four decades. It is usually difficult to determine the influence of magma properties on mineral crystallization forming fined-grained granites due to its irregular and fine-grained textures. The ideal granite model was originally developed for modeling mineral sequences from first and second-order Markov properties. This paper proposes a new model for quantifying scale invariance properties of mineral clusters and voids observed within mineral sequences. Sequences of the minerals plagioclase, quartz and orthoclase observed under the microscope for 104 aplite samples collected from the Meech Lake area, Gatineau Park, Québec were used for validation of the model. The results show that the multi-scale approaches proposed in this paper may enable quantification of the nature of the randomness of mineral grain distributions. This, in turn, may be related to original properties of the magma.

Download Full-text