Coastal Sediment Budgets and the Littoral Cutoff Diameter: A Grain Size Threshold for Quantifying Active Sediment Inputs

2008 ◽  
Vol 2 ◽  
pp. 122-133 ◽  
Author(s):  
Patrick W. Limber ◽  
Kiki B. Patsch ◽  
Gary B. Griggs
Keyword(s):  
Grain Size ◽  
Coastal Sediment ◽  
Sediment Budgets ◽  
Size Threshold

Comminution effects on mineral grade distribution

2020 ◽  
Author(s):  
Gabriele Baldassarre ◽  
Oliviero Baietto
Keyword(s):  
Grain Size ◽  
Froth Flotation ◽  
Mining Operations ◽  
Thin Sections ◽  
Grade Distribution ◽  
Important Trend ◽  
Disk Mill ◽  
Definition Of ◽  
Quality Material ◽  
Size Threshold

<p>Every mining operations is followed by a beneficiation process aimed to deliver quality material to the transformation industry. Mainly, in mineral processing comminution and grinding of extracted ore, are crucial operations for the following separation steps in order to obtain valuable minerals from gangue.</p><p>Comminution is the most energy consuming phase and the quality of the results is strictly related to the characteristic of the material under treatment.</p><p>A preliminary study has been performed in order to understand the crushing behaviour of a mixed sulphide ore, containing galena and sphalerite, and the distribution of the two target minerals among the different sized products of the process.</p><p>Ore samples have been examined and characterized by means of thin sections observation and SEM analyses for the determination of the free grain size, while XRD quantitative analyses have been performed for the definition of the grades.</p><p>The selected crushing circuit comprises lab-scale impact crusher, jaw crusher, disk mill and rod mill. For each stage of the process products below the free grain size threshold have been collected and particle size analyses have been carried out.</p><p>Comminution products were divided in dimensional classes suitable for flotation separation, ranging between 0.250 and 0.075mm and XRD analyses showed a variable mineral grade distribution varying with the reduction in dimension of the products.</p><p>This important trend should be considered for further investigation related to an efficient froth flotation separation.</p>

scholarly journals Grain size threshold for enhanced irradiation resistance in nanocrystalline and ultrafine tungsten

2017 ◽  
Vol 5 (5) ◽  
pp. 343-349 ◽  
Author(s):  
O. El-Atwani ◽  
J. A. Hinks ◽  
G. Greaves ◽  
J. P. Allain ◽  
S. A. Maloy
Keyword(s):  
Grain Size ◽  
Size Threshold ◽  
Irradiation Resistance

scholarly journals Coastal Sediment Transport along Kalpakkam using Sediment Trend Exploaration and Numerical Modelling

2019 ◽  
Vol 8 (2S11) ◽  
pp. 3011-3015
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Numerical Model ◽  
Numerical Modelling ◽  
Trend Analysis ◽  
Coastal Sediment ◽  
Sediment Grain Size ◽  
Coastal Sediment Transport ◽  
The Impact ◽  
Grain Size Trend Analysis

The impact of coastal sediment transport in the nearshore region is significant and the need for improved sediment quantification techniques appears to be universally accepted. The coastal sediment transport models presently in use were derived empirically from very sparse measurements of waves and currents and from laboratory experiments. The shoreline of Kadalur fishing villages near Kalpakkam has been experiencing erosion due to occurrence of cyclones every monsoon. Palar River with its confluence in the Bay of Bengal at the northern tip of the Kadalur villages has its mouth closed due to negligible river flow. The purpose of this study is to assess sediment dynamics in the Kalpakkam coast using two independent approaches; namely Sediment Trend Analysis (STA) and two dimensional numerical modelling. The latter can track the movement of individual particles. Numerical modelling approach is based on Delft3D model which allows the coupling of flow and wave modules. STA and numerical modelling results can provide sediment transport direction. The combination of both approaches provides a means of verification of sedimentation processes. The basic assumption in STA is that sediment transport can be responsible for the differences in sediment grain size distributions. For Grain Size Trend Analysis, grab samples were collected throughout the nearshore area. Grain Size Trend Analysis was then carried out and subsequent results were plotted to obtain the sediment transport pattern for the region. The results obtained are compared with the numerical model results and also used for validation of sediment transport evaluated using the numerical model.

scholarly journals Reconstructing Coastal Sediment Budgets From Beach‐ and Foredune‐Ridge Morphology: A Coupled Field and Modeling Approach

2019 ◽  
Vol 124 (6) ◽  
pp. 1398-1416 ◽  
Author(s):  
Daniel J. Ciarletta ◽  
Justin L. Shawler ◽  
Christopher Tenebruso ◽  
Christopher J. Hein ◽  
Jorge Lorenzo‐Trueba
Keyword(s):  
Coastal Sediment ◽  
Sediment Budgets ◽  
Modeling Approach ◽  
Coupled Field

scholarly journals Comminution Effects on Mineral-Grade Distribution: The Case of an MVT Lead-Zinc Ore Deposit

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 893
Author(s):  
Gabriele Baldassarre ◽  
Oliviero Baietto ◽  
Paola Marini
Keyword(s):  
Grain Size ◽  
Texture Features ◽  
Mining Operation ◽  
Mississippi Valley ◽  
Grade Distribution ◽  
Lead Zinc ◽  
Energy Consuming ◽  
Definition Of ◽  
Crushing Behavior ◽  
Size Threshold

Every mining operation is followed by a beneficiation process aimed at delivering quality materials to the transformation industry. Mainly, in order to separate valuable minerals from gangue in mineral processing, the crushing and grinding of extracted ore are crucial operations for the following separation steps. Comminution is the most energy-consuming operation in mining, and the quality of the results is strictly related to the characteristic of the material under treatment, the type of equipment used in comminution, and the circuit design adopted. A preliminary study was performed in order to understand the crushing behavior under different comminution forces of a high-grade mixed Zn-Pb sulfide ore sample, collected in a Mississippi-Valley Type (MVT) deposit, and the distribution of the target minerals among the products of the process. Ore samples were examined and characterized through thin section observation and SEM analyses for the determination of grain size and texture features, while X-ray powder diffraction (XRPD) quantitative analyses were performed for the definition of target mineral concentrations of comminuted product samples. The selected crushing and grinding circuit comprised lab-scale equipment. For each stage of the process, products below the estimated free-grain size threshold were collected, and particle size analyses were carried out. Comminution products were divided into size distribution classes suitable for further separation operations, and XRPD analyses showed a mineral-grade distribution varying with the dimensions of the products. Characterization of the ore material after crushing and grinding force applications in terms of the distribution of target minerals among different-sized classes was achieved. The important trends highlighted should be considered for further investigation related to an efficient separation.

Effect of Shock Loading on the Microstructure of Uniloy 326

1974 ◽  
Vol 32 ◽  
pp. 504-505
Author(s):  
K. P. Staudhammer ◽  
L. E. Murr
Keyword(s):  
Grain Size ◽  
Shock Loading ◽  
Current Investigation ◽  
Two Phase ◽  
05 C ◽  
Shock Deformation ◽  
Heat Treated

The effect of shock loading on a variety of steels has been reviewed recently by Leslie. It is generally observed that significant changes in microstructure and microhardness are produced by explosive shock deformation. While the effect of shock loading on austenitic, ferritic, martensitic, and pearlitic structures has been investigated, there have been no systematic studies of the shock-loading of microduplex structures.In the current investigation, the shock-loading response of millrolled and heat-treated Uniloy 326 (thickness 60 mil) having a residual grain size of 1 to 2μ before shock loading was studied. Uniloy 326 is a two phase (microduplex) alloy consisting of 30% austenite (γ) in a ferrite (α) matrix; with the composition.3% Ti, 1% Mn, .6% Si,.05% C, 6% Ni, 26% Cr, balance Fe.

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

Novel magneto-optical recording materials: Bi-substituted garnet films

1991 ◽  
Vol 49 ◽  
pp. 776-777
Author(s):  
Takao Suzuki ◽  
Hossein Nuri
Keyword(s):  
Grain Size ◽  
Amorphous Film ◽  
Nitrogen Atmosphere ◽  
Optical Recording ◽  
Garnet Film ◽  
Media Noise ◽  
Garnet Films ◽  
Order Of Magnitude ◽  
A New Technique ◽  
A Current

For future high density magneto-optical recording materials, a Bi-substituted garnet film ((BiDy)3(FeGa)5O12) is an attractive candidate since it has strong magneto-optic effect at short wavelengths less than 600 nm. The signal in read back performance at 500 nm using a garnet film can be an order of magnitude higher than a current rare earth-transition metal amorphous film. However, the granularity and surface roughness of such crystalline garnet films are the key to control for minimizing media noise.We have demonstrated a new technique to fabricate a garnet film which has much smaller grain size and smoother surfaces than those annealed in a conventional oven. This method employs a high ramp-up rate annealing (Γ = 50 ~ 100 C/s) in nitrogen atmosphere. Fig.1 shows a typical microstruture of a Bi-susbtituted garnet film deposited by r.f. sputtering and then subsequently crystallized by a rapid thermal annealing technique at Γ = 50 C/s at 650 °C for 2 min. The structure is a single phase of garnet, and a grain size is about 300A.

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