Scientific Mining Journal

Scientific Mining Journal

Volume 55 - No 2 (June 2016)
Investigation of the Effects of Main Roof Loading on the Breaking Distance of the Immediate Roof in Longwall Mining
Pages 3-22 Ekin KÖKEN, Ahmet ÖZARSLAN

 As known from the previous studies that the cavability of immediate roof is important to maintain an effective strata control. The other issue should be paid attention in breaking of immediate roof affected by geomechanical properties of roof strata, is the main roof loading. It is not accurately revealed how and to what extent main roof acts on the immediate roof. Important approximations aiming to estimate the breaking distance of immediate roof are summarized in this study. The effect of main roof acting upon the immediate roof with different thickness and triangular distributed loading conditions is investigated according to elastic beam theory. The results obtained from parametrical analysis using beam theory are compared to the breaking distance values of six longwalls located in Zonguldak Hard coal Basin. In conclusion, significant effects of main roof loading are seen for the breaking distance of immediate roof.

Measurement and Evaluation of Hand-Arm Vibration Exposure Sourced From Some Power Tools in Mining Workplaces
Pages 23-44 Bülent ERDEM, Tuğba DOĞAN, Zekeriya DURAN, Zafer ÖZGEN

This study includes measuring and then evaluating the hand-arm vibration exposure of mine workers. The research is supported by measurements taken from industrial establishments. The measurements were carried out using equipment and processes suitable to the relevant standards, which are specified in the Control of Vibration at Work Regulations issued by the Labor and Social Security Ministry of Turkey. For each tool/instrument the following vibration-related parameters were calculated: acceleration equivalent level (AEQ), equivalent vibration acceleration (A(8)), hourly exposure points (HEP), total exposure points (TEP), the dominant vibration acceleration frequency for each axis, time to reach the exposure action value (EAVTT) and time to reach the exposure limit value (ELVTT). Later, instruments/tools were grouped and then analyzed under the following four headings; instruments which perform similar functions, hand-held or hand-driven instruments/tools, performing a specific task by holding the tool/instrument or by holding and feeding a working object to the tool, and finally electricity or pressurized fluid driven tools. In all groups, compactors, drill tools of all types, high-speed grinders and cutters were found to cause extremely high levels of hand-arm vibration exposure, which would confine the time to reach to the exposure limit value within a few minutes.

Behavior of Clays in Pulp Media and Their Effect on Flotation ( Orjinal Araştırma )
Pages 45-52 Hasan Ali TANER, Vildan ÖNEN
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Flotation method has gained importance because of necessity for processing of high clay content and low grade ore deposits with the reduction of the rich ore deposits in the world. Clay minerals which are the main gangue mineral in many mineralization create problems in all steps of the mineral processing. Difficulties in the processing of high clay content in ores are due to their different and complex structure. The clay minerals which have significant structural differences are the most complicated minerals in terms of composition and classification. These structural differences cause different behavior, so effect the enrichment process. The importance of understanding the mineralogy of clay minerals and their structural characteristics, hence effect of this properties to enrichment process is increasing day by day. The presence of clay minerals leads to problems such as changing of froth stability, problems related to swelling behavior, increase in pulp viscosity, overconsumption of reagents, slime coating and mechanical entrainment in flotation. To improve the flotation performance, to ensure the effects of clay minerals and understand this mechanism is required. In this article, it was investigated the effects of clay minerals on flotation performance and scientific studies related with this issue.

Investigation of Underground Blasting Applications in Eti̇ Bakır A.Ş. Küre Underground Mine ( Orjinal Araştırma )
Pages 53-62 Gürhan DEMİR, Muzaffer YILMAZ, Murat ŞEN
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 Underground copper mining at Küre Mine of Eti Bakır A.Ş. have been conducted by a combination of drilling - blasting and sublevel stoping method. Underground blasting operation have been investigated under three main categories: Ore faces, waste faces, and sublevel stoping blasting. Those blasting activities had been followed and used blasting materials, working methods and blasting results are summurized at below study.