scholarly journals Automated Gold Grain Counting. Part 2: What a Gold Grain Size and Shape Can Tell!

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 379
Author(s):  
Réjean Girard ◽  
Jonathan Tremblay ◽  
Alexandre Néron ◽  
Hugues Longuépée ◽  
Sheida Makvandi
Keyword(s):  
Grain Size ◽  
Gold Deposits ◽  
Source Rocks ◽  
Size And Shape ◽  
Fine Grained ◽  
Reverse Circulation ◽  
Backscattered Electron ◽  
Grain Size And Shape ◽  
Northern Territories ◽  
Automated Scanning

Glacial drift exploration methods are well established and widely used by mineral industry exploring for blind deposit in northern territories, and rely on the dispersion of mineral or chemical signal in sediments derived from an eroded mineralized source. Gold grains themselves are the prime indicator minerals to be used for the detection of blind gold deposits. Surprisingly, very little attention has been dedicated to the information that size and shape of gold grain can provide, other than a simple shape classification based on modification affecting the grains that are induced in the course of sediment transport. With the advent of automated scanning electron microscope (SEM)-based gold grain detection, high magnification backscattered electron images of each grain are routinely acquired, which can be used for accurate size measurement and shape analysis. A library with 88,613 gold grain images has been accumulated from various glacial sediment surveys on the Canadian Shield and used to detect trends in grains size and shape. A series of conclusions are drawn: (1) grain size distribution is consistent among various surveys and areas, (2) there is no measurable fine-grained gold loss due to natural elutriation in ablation or reworked till, or during the course of reverse circulation drilling, (3) there is no grain size sorting during glacial transport, severing small grains from large ones, (4) shape modification induced by transport is highly dependent on grain size and original shapes, and (5) the use of grain shape inherited from neighboring minerals in the source rocks is a useful feature when assessing deposit types and developing exploration strategies.

MICROSTRUCTURAL CHANGES OF ALUMINIUM ALLOY A319 ON COOLING SLOPE PLATE

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Ahmad Muhammad Aziz ◽  
Mohd Zaidi Omar ◽  
Zainuddin Sajuri ◽  
Mohd Shukor Salleh
Keyword(s):  
Grain Size ◽  
Shape Factor ◽  
Casting Process ◽  
Impact Zone ◽  
Dendritic Microstructure ◽  
Size And Shape ◽  
Cooling Slope ◽  
Grain Size And Shape ◽  
Bottom Zone ◽  
The Impact

The cooling slope (CS) casting process is one of the simplest methods for producing a non-dendritic microstructure. To more clearly determine how this microstructure is formed, specifically in A319, requires an examination of how the dendritic microstructure evolves along the entirety of the CS plate. Yet until now, there are still unclear on the verification of microstructures changes on the CS plate. Based on experimental results, this paper offers an explanation for the mechanism involved in producing a nearly globular microstructure in A319. In addition, the mechanism is verified by using the planimetry method. Moreover a quantitative method is used to determine the grain size and shape factor to provide further support for the proposed mechanism. The solid fraction of α-Al at the impact zone is 70 % which is the highest compared to other zones. Grain size and shape factor shown a decreasing and increasing value respectively from the impact zone until the bottom zone.

scholarly journals Synthesis of the new lost foam refractory coatings based on talc

2021 ◽  
pp. 111-111
Author(s):  
Marko Pavlovic ◽  
Jasmina Nikolic ◽  
Ljubisa Andric ◽  
Dejan Todorovic ◽  
Katarina Bozic ◽  
...  
Keyword(s):  
Grain Size ◽  
Positive Influence ◽  
X Ray Diffraction ◽  
Size And Shape ◽  
Refractory Coatings ◽  
Alloy Castings ◽  
Grain Size And Shape ◽  
Time Required ◽  
The Cost ◽  
Lost Foam

This paper is focused on the preparation procedures, using talc-based filler to improve the rheologic properties of the lost foam refractory coatings. Talc, with grain size of 40 mm, was mechanically activated in a vibration mill over the following times: 10, 20 and 30 min. Depending on the time required for the mechanical activation, the change in the filler grain size and shape was analysed along their effects on the talc-filled lost foam coating dispersion ability and stability. In order to characterize the filler, the following methods were used: X-ray diffraction, scanning electron microscopy and optic microscopy. The coating compo-sition was tuned by choosing the suitable grain size and shape factor of the activated filler. In addition, different coating components (additives, solvent) were applied to alter the coating generation procedure. It was shown that the application of this type of the lost foam refractory coatings - water-based coatings - have a positive influence on quality of the aluminium alloy castings, which contributes to reducing the cost of cleaning and processing of the castings. Also, alcohol-based refractory coatings with talc-based activated fillers were tested and used to have the castings produced in the sand moulds.

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