scholarly journals Sustainable Underground Iron Ore Mining in Ukraine with Backfilling Worked-Out Area

2021 ◽  
Vol 13 (2) ◽  
pp. 834
Author(s):  
Oleg Bazaluk ◽  
Mykhailo Petlovanyi ◽  
Vasyl Lozynskyi ◽  
Serhii Zubko ◽  
Kateryna Sai ◽  
...  
Keyword(s):  
Rock Mass ◽  
Industrial Waste ◽  
Iron Ore ◽  
High Grade ◽  
Stability Assessment ◽  
High Quality ◽  
Considerable Part ◽  
Mine Production ◽  
World Markets ◽  
Ore District

The present paper considers aspects of underground iron ore mining in Ukraine, in particular the level of mine production and reserves of basic ore fields. It analyzes and generalizes the practice of using cemented rockfill under difficult mining and hydrogeological conditions of the Pivdenno-Bilozerske high-grade iron ore field. The Belozersky iron ore district is the only one in Ukraine that, without any technological cycle of beneficiation, can provide both domestic and foreign consumers with high-quality raw iron ore as required by world markets. The PJSC Zaporizhzhia iron ore plant extracts iron ore from the Pivdenno-Bilozerske field with an iron content of more than 60% using the low-waste, environmentally friendly technology of backfilling the mined-out area with a hardening mixture. The peculiarities of the technology for steep deposit mining and the main processes of backfilling operations in terms of preparation, transportation, and construction of the backfill mass with its stability assessment are explained in detail in this paper. As a result of using cemented rockfill, rock mass stability is provided, a considerable part of industrial waste is disposed of in the mined-out area, and the earth’s surface subsidence within the area is prevented (in comparison with mining enterprises in other fields).

Synthesis of Low Viscosity Polydimethylsiloxane Using Low Grade of Octamethylcyclotetrasiloxane

2021 ◽  
Vol 1028 ◽  
pp. 365-370
Author(s):  
Diba G Auliya ◽  
Soni Setiadji ◽  
Zulfi Mofa Agasa ◽  
Fitrilawati ◽  
Norman Syakir ◽  
...  
Keyword(s):  
Ring Opening ◽  
Raw Materials ◽  
Vitreoretinal Surgery ◽  
Production Costs ◽  
Low Grade ◽  
High Grade ◽  
High Quality ◽  
Low Viscosity ◽  
Polymerization Method

Polydimethylsiloxane (PDMS) has been widely used as a vitreous humour substitution in vitreoretinal surgery. Due to its limited availability and increasing domestic needs, the price of PDMS in Indonesia became very expensive. Previously, we reported the synthesized of PDMS from a high grade of monomer of 98% of Octamethylcyclotetrasiloxane (D4) and found that all PDMS samples produced high quality samples similar to that of commercial one. However, by considering the ease of obtaining raw materials and also the production costs, the synthesis of PDMS using monomer which easy to be found in Indonesia and low production costs is needed to be developed. Here, we reported the synthesis of PDMS using low grade of 96% of D4 in order to produce high quality of PDMS with low viscosity that can be used for vitreous humous substitution in vitreoretinal surgery. PDMS samples with low viscosity value of 0.94-1.35 Pa.s have been successfully synthesized from low grade of D4 and MM using ring-opening polymerization method. The yields of PDMS resulted in this research were in the range between 67.27% and 76.26%. From FTIR spectroscopy, it is found that all synthesized samples have structure and functional groups similar to PDMS using high grade of monomer of 98% Octamethylcyclotetrasiloxane (D4). From refractometer and surfgauge measurements, all samples have refractive index in the range of 1,4034-1,4040 and the value surface tension was 21 m.N/m.

scholarly journals Stability Assessment of Mining Excavations: the Impact of Large Depths

2018 ◽  
Vol 40 (3) ◽  
pp. 180-187
Author(s):  
Tadeusz Majcherczyk ◽  
Zbigniew Niedbalski ◽  
Łukasz Bednarek
Keyword(s):  
Rock Mass ◽  
In Situ Monitoring ◽  
Stability Assessment ◽  
Underground Excavations ◽  
Deformation Prediction ◽  
Large Depth ◽  
Coal Deposits ◽  
The Impact

AbstractBack in the early 1980s, coal deposits occurring at depths of ~700 m below surface were already regarded as large-depth deposits. Meanwhile, today the borderline depth of large-depth mining has extended to >1,000 m. Design, excavation and maintenance of mining roadways at the depth of >1,000 m have, therefore, become crucial issues in a practical perspective in recent years. Hence, it is now extremely important to intensify research studies on the influence of large depths on the behaviour of rock mass and deformation of support in underground excavations. The paper presents the results of the study carried out in five mining excavations at depths ranging from 950 to 1,290 m, where monitoring stations with measurement equipment were built. The analysis of data from laboratory and coal mine tests, as well as in situ monitoring, helped to formulate a set of criteria for stability assessment of underground excavations situated at large depths. The proposed methodology of load and deformation prediction in support systems of the excavations unaffected by exploitation is based on the criteria referring to the depth of excavation and the quality of rock mass. The depth parameter is determined by checking whether the analysed excavation lies below the critical depth, whereas the rock mass quality is determined on the basis of the roof lithology index (WL) and the crack intensity factor (n)

CARBON AND FUEL FROM RUBBER WASTE

2020 ◽  
pp. 103-108
Author(s):  
Gennadi I. Zhuravsky ◽  
Maksim I. Nitievski
Keyword(s):  
Zinc Oxide ◽  
Water Vapor ◽  
Raw Materials ◽  
Liquid Waste ◽  
Raw Material ◽  
High Grade ◽  
High Quality ◽  
Technical Carbon ◽  
Rubber Waste ◽  
Composite Mixture

The results of studies of thermolysis waste in the environment of overheated water vapor are presented. It is shown that as a result of fractionation from liquid waste thermolysis products, gasoline and diesel fuel fractions can be obtained. It is proposed to use a composite mixture of liquid and solid waste thermolysis products as raw materials for high-grade technical carbon. Studies have shown that high-grade technical carbon can be obtained as raw materials using a composite mixture of rubber waste thermolysis products as raw materials. The technological line of obtaining technical carbon from the products of thermolysis of worn tires is described. Analysis of the ash produced by the process of burning the composite mixture shows that it contains compounds of iron, zinc and silicon. Therefore, this ash is of interest as a high-quality raw material for the production of zinc oxide, as one of the main ingredients of rubber mixtures.

scholarly journals Proper MgO/Al2O3 Ratio in Blast-Furnace Slag: Analysis of Proper MgO/Al2O3 Ratio Based on Observed Data

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 784
Author(s):  
Fengman Shen ◽  
Xinguang Hu ◽  
Haiyan Zheng ◽  
Xin Jiang ◽  
Qiangjian Gao ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Iron Ore ◽  
Social Benefits ◽  
Blast Furnaces ◽  
High Quality ◽  
Diagram Analysis ◽  
Furnace Slag

With the gradual depletion of high-quality iron-ore resources, ironmaking blast furnaces have gradually shifted to using high-content Al2O3 iron ore. Under this condition, the addition of MgO in the slag is adopted to alleviate operation problems caused by the high content of Al2O3. However, the proper value of the MgO/Al2O3 ratio for blast-furnace slag systems (Al2O3 = 8–25%) is not systematically studied. In this paper, we discuss the proper MgO/Al2O3 ratio on the basis of blast-furnace slag systems under different Al2O3 contents. On the basis of thermodynamics and phase-diagram analysis, it could be concluded that: (1) the MgO/Al2O3 ratio is not limited when Al2O3 in slag is less than 14%, (2) the MgO/Al2O3 ratio is required to be in the range of 0.40–0.50 when Al2O3 in the slag is 15–17%, and (3) the MgO/Al2O3 ratio should be 0.45–0.55 when Al2O3 in the slag is larger than 18%. The proper MgO/Al2O3 ratio value has been established in various industries, and it has achieved significant economic and social benefits.

Anisotropic characteristics of jointed rock mass: A case study at Shirengou iron ore mine in China

2015 ◽  
Vol 48 ◽  
pp. 129-139 ◽  
Author(s):  
Tianhong Yang ◽  
Peitao Wang ◽  
Tao Xu ◽  
Qinglei Yu ◽  
Penghai Zhang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Iron Ore ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Iron Ore Mine
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