Svetlin Toshev, Alexandre Loukanov

ABSTRACT. The paper focuses on the development of ultra–small carbon nanodots as sensitive sensors for detection and monitoring of manganese in drinking water and groundwater. The environmental contamination with manganese is often a result from industrial activities such as mining and agriculture. The soluble Mn ions are toxic for many organisms and might even cause serious human diseases. The strategy for sensory detection used by us is based on a photo–oxidation reaction, in which the carbon nanodots are dissolved in acidic solution and illuminated with UV irradiation ( = 365 nm). At these conditions the nanoparticles acted as photosensitizer and produced singlet oxygen, which can be monitored by 3,3’,5,5’–tetramethylbenzidine as an organic indicator. However, to proceed this reaction, it is necessary to introduce the redox pair Mn(II)/Mn(III) in the reaction mixture, which plays the role of a catalytic mediator for the electron transfer. Thus, the oxidation of 3,3’,5,5’–tetramethylbenzidine appears, which results in blue colour of the solution with absorbance maximum at 645 nm. The rate of this sensory reaction was significantly enhanced in the presence of EDTA, which was used as a ligand to obtain a stable complex of Mn(III)/EDTA. The formed complex itself oxidised the organic indicator and caused the colorimetric reaction. Among the other metal ions tested, only manganese could be detected by the presented sensory approach.

Keywords: manganese detection and monitoring, ultra–small carbon nanodots, sensory reaction

Toshev, S., A. Loukanov. Detection and monitoring of manganese in drinking water and groundwater through photo-oxidation sensory reaction with ultra-small carbon nanodots
DOI: 10.5281/zenodo.4270156
DOI: https://doi.org/10.58903/a14161836

References
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2. Bamforth, S, M., Manning, D. A., Singleton, I., Younger, P. L., Johnson, K. L., (2006) Manganese removal from mine waters–investigating the occurrence and importance of manganese carbonates. Appl. Geochem. 21, 1274–1287. https://doi.org/10.1016/j.apgeochem.2006.06.004

3. Bulska, E., Ruszczyńska, (2017) Analytical techniques for trace element determination. Physical Sciences Reviews 2, 20178002. https://doi.org/10.1515/psr-2017-8002

4. Chiswell, B., Huang, S.-H. D., (2006) Chapter 10 – Manganese removal. Interface Science and Technology 10, 179–192. DOI:  10.1016/S1573-4285(06)80079-7

5. Dieter, H. H., Rotard, W., Simon, J., Wilke, O., (1992) Manganese in natural mineral waters from Germany. Die Nahrung 36, 477–484. https://doi.org/10.1002/food.19920360509

6. Khadse, G. K., Patni, P. M., Labhasetwar, P. K., (2015) Removal of iron and manganese from drinking water supply. Sustainable Water Resources Management 1, 157–165. https://doi.org/10.1007/s40899-015-0017-4

7. Loukanov, A., Mladenova, P., Udono, H., Miskolczy, Z., Angelov, A., Biczók, L., Nakabayashi, S., (2018) Sulfur doped fluorescent carbon dots as nanosensors for rapid and sensitive monitoring of calcium in hard water. Journal of Chemical Technology and Metallurgy 53, 473–479.

8. O’Neal, S. L., Zheng, W., (2015) Manganese toxicity upon overexposure: a decade in review. Curr Environ Health Rep. 2, 315–328. doi: 10.1007/s40572-015-0056-x.

9. Park, J. H., Kim, B. S., Chon, C. M., (2018) Characterization of iron and manganese minerals and their associated microbiota in different mine sites to reveal the potential interactions of microbiota with mineral formation. Chemosphere 191, 245–252. doi: 10.1016/j.chemosphere.2017.10.050

10. Tuerhong, M., Xu, Y., Yin, X.-B., (2017) Review on carbon dots and their applications. Chinese Journal of Analytical Chemistry 45, 139–150. https://doi.org/10.1016/S1872-2040(16)60990-8

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12. Wilschefski, S. C., Baxter, M. R., (2019) Inductively coupled plasma mass spectrometry: introduction to analytical aspects. Clin Biochem Rev. 40, 115–133. doi: 10.33176/AACB-19-00024

13. Wuana, R. A., Okieimen, F, E., (2011) Heavy metals in contaminated soils: a review of sources, chemistry, risks and best available strategies for remediation. International Scholarly Research Network, Article ID 402647.  https://doi.org/10.5402/2011/402647

14. Zhang, Z., Xiao, C., Adeyeye, O., Yang, W., Liang, X., (2020) Source and mobilization mechanism of iron, manganese and arsenic in groundwater of Shuangliao city, Northeast China. Water 12, 534. https://doi.org/10.3390/w12020534

Nadezhda Stoycheva, Petar Shishkov

ABSTRACT. In some cases, during the extraction of certain mineral resources, industrial explosives are not sufficiently safe for the environment in terms of generated shock waves, toxic gases, seismic waves, scattering and vibrations. The main reasons for these harmful effects of the explosion are the speed and the mechanism of the chemical reaction of explosive decomposition. The authors have focused their research on a variety of fast–combusting high–energetic compositions, that can fully replace the widely used detonating explosives in the extraction and secondary processing (cutting) of large stone blocks. Samples from polymer containers filled with non–detonating compositions, based on waste gunpowder and metal–containing pyrotechnic mixtures were subjected to field tests. The experiments were performed in real conditions on stone blo cks with hardness f = 16 according to the Protodyakonov rock strength scale. Depending on the lengths of the blast holes, different charge designs were used.

Keywords: non–detonating blasting cartridges, propellants, smooth blasting, ornamental stone extraction

Stoycheva, N., P. Shishkov. Non-detonating charges in polymer housings for smooth splitting of rock blocks during primary extraction and secondary cutting
DOI: 10.5281/zenodo.4270146
DOI: https://doi.org/10.58903/a14161835

References

1. Boychev Y., Asenov S., 2018. “Pirotehnicheski sastavi za neletalni svetlinnozvukovi sredstva”, ISBN:978-619-7246-20-9, ISSN:2367-7481, 614-620, National Academic Publishing House (in Bulgarian) 

2. Boychev Y., 2018. “Pirotehnicheski neletalni sredstva za zashtita”, National conference with international attendance “Defence Industry – Leader of the Innovations in Bulgaria”, 20.09.2018, Sofia, Bulgaria  (in Bulgarian)

3. Mitkov, V. 2007. Za bezopasnostta na eksplozivite za gragdanski celi.– Annual of the University of Mining and Geology “St. Ivan Rilski”, 50, Part 2, 109−114 (in Bulgarian).  ISSN 1312-1820 

4. Mitkov, V. 2011. Razrabotvane i izsledvane na novi zariadi ot utilizirani boepripasi, Geology and mineral resourses Nr. 4, p. 30-33, ISSN 1310-2265 (in Bulgarian).

5. Mitkov V., 2010. Bezopasnost pri proizvodstvoto i upotrebata na eksplozivi,  ISBN 978-954-353-131-8 (in Bulgarian)

6. Mitkov V., 2010. Development of a new brand of coarse dispersed explosive based on technical ammonium nitrate. Fúrás- robbantástechnika  Nemzetközi Konferencia Balatonkenese 2010, Szeptember 8-10., pp. 65-70, HU ISSN 1788-5671. 

7. Mitkov V., Totev L., 2012.  Development of a new brand of coarse dispersed explosive based on technical ammonium nitrate Conference proceedings from the International conference of Blasting techniques, Stara Lesna, Slovak Republic, p. 135-141, ISBN 978-80-970265-4-7.

8. Shishkov P., Stoycheva N., 2018. Savremenni vzrivni tehniki za dobiv na skalno-oblicovachni materiali  – Mining and geology magazine, 10-11, p.42-49, ISSN 0861-5713 (in Bulgarian with English abstract) 

9. Stoyanov D.,1994. Rakovodstvo za uprazhneniya po probivno-vzrivni raboti v otkriti rudnici, karieri i stroitelstvoto”, MGU, Sofia (in Bulgarian)

10. Stoycheva N., Shishkov P., 2019. Innovative formulations for a new generation of low-speed explosive compositions, designed for blasting in tender conditions and for extraction of rock-cladding materials  – Journal of Mining and Geological Sciences, p.94 – 99, vol.62, Nr.2 

Vessela Petrova

ABSTRACT. The circular economy, which promotes the responsible and cyclical use of resources, contributing to sustainable development is becoming more and more popular, especially in the European Union. The concept of switching from the traditional linear to cyclical consumption model leads to minimisation of waste and environmental pollution, and in this regard the New Circular Economy Plan is already in place. The great ambitions for changes in the industry are strengthened by the Green Pact (Green Deal). The publication presents an in–depth study of the literature on the subject, as well as the five business models through which, in practice, a circle is realised. It has been established that the literature in the context of the mining industry is extremely scarce, and the business models through which the processes in the industry are carried out are poorly studied. An up–to–date survey of 13 companies in the raw–material resources sector in Bulgaria is also presented, aimed at showing the extent to which they understand and apply the circular economy in their work. The res ults unequivocally prove that the concept is not new for the business.

Keywords: circular economy, business models, raw material industry

Petrova, V. Circular economy practices in the Bulgarian raw material industry
DOI: 10.5281/zenodo.4270134
DOI: https://doi.org/10.58903/a14161834

References

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2. Boulding, K. (1966), “The Economics of the Coming Spaceship Earth”, in H. Jarrett (ed.), Environmental Quality in a Growing Economy, Baltimore, MD: Johns Hopkins University.

3. Bulgarian Chamber of Mining and Geology. 2010-2019. Godishen byuletin 2010-2019, Mineralno-surovinnata industria v Bulgaria. BMGK, Sofia (in Bulgarian) : https://www.bmgk.bg/%d0%b1%d1%8e%d0%bb%d0%b5%d1%82%d0%b8%d0%bd-%20%20%20%20%d0%b0%d1%80%d1%85%d0%b8%d0%b2/.

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5. Ellen MacArthur Foundation (2017) Circular Economy Schools of Thought – Performance Economy.

6. Ellen MacArthur Foundation (2012) Towards the circular economy: Economic business rationale for an accelerated transition.

7. EPEA (2017) The Cradle to Cradle® design concept – EPEA, EPEA Internationale Umweltforschung GmbH.

8. Fiorenza Belussi, Katia Caldari, At the origin of the industrial district: Alfred Marshall and the Cambridge school, Cambridge Journal of Economics, Volume 33, Issue 2, March 2009, Pages 335–355, https://academic.oup.com/cje/article/33/2/335/1732562.

9. Ghisellini, P., Cialani, C. and Ulgiati, S. (2016) A review on circular economy: The expected transition to a balanced interplay of environmental and economic systems, Journal of Cleaner Production, vol. 114, pp. 11–32. https://doi.org/10.1016/j.jclepro.2015.09.007

10. Heck, P. (2006). Circular economy related international practices and policy trends: Current situation and practices on sustainable production and consumption and international circular economy development policy summary and analysis. World Bank Report.

11. Heshmati, A. (2014b). An Empirical Survey of the Ramification of a Green Economy. IZA Discussion Paper 2014:8078, 33 pages.

12. Heshmati, A. (2014a). Demand, Customer Base-Line and Demand Response in the Electricity Market: A Survey. Journal of Economics Surveys 28(5), 862-888.

13. Heshmati, A., Abolhosseini S. and J. Altmann (2015). The Development of Renewable Energy Sources and its Significance for the Environment. Springer.

14. Marshall, Alfred (1890). Principles of Economics. 1 (First ed.). London: Macmillan.

15. Meadows, Donella H, Meadows, Dennis L, Randers, Jørgen. (1972) The Limits to Growth; A Report for the Club of Rome’s Project on the Predicament of Mankind. New York, Universe Books.

16. METI (2004). Handbook on Resource Recycling Legislation and 3R Initiatives. Ministry of Economy, Trade and Industry, Tokyo, Japan.

17. Mitchell, P. (2015), “Employment and the circular economy – Job Creation through resource efficiency in London’’. Report produced by WRAP for the London Sustainable Development Commission, the London Waste and Recycling Board and the Greater London Authority.

18. Morioka, T., K. Tsunemi, Y. Yamamoto, H. Yabar and N. Yoshida (2005). Eco-efficiency of advanced loop closing systems for vehicles and household appliances in Hyogo Eco-town. Journal of Industrial Ecology 9(4), 205-221. DOI: 10.1162/108819805775247909

19. Nogalski, B. A. Szpitter, A. Jablonski, M. Jablonski (2020) Networked Business Models in the Circular Economy, IGI Global.  DOI: 10.4018/978-1-5225-7850-5

20. Paspaldzjiev, I., (2020) Evropeyskata zelena sdelka – promenite te parva predstoiat, [Online] Available at https://www.sustainability.bg/%D0%B7%D0%B5%D0%BB%D0%B5%D0%BD%D0%B0-%D1%81%D0%B4%D0%B5%D0%BB%D0%BA%D0%B0/ (in Bulgarian).

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Rizos, V., K. Tuokko, A. Behrens (2017) The circular economy. A review of definitions, processes and impacts. CEPS Research Report No. 2017/09.

Sauvé, S., S. Bernard and P. Sloan (2016), “Environmental sciences, sustainable development and circular economy: Alternative concepts for trans-disciplinary research’’, Environmental Development, Vol. 17, pp. 48-56.  https://doi.org/10.1016/j.envdev.2015.09.002

SITRA (2019а). Dictionary – The circular economy. Noudettu osoitteesta. https://www.sitra.fi/en/dictionary/the-circular-economy/

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Trifonova, B. (2019) Model for HR Management in Mining Companies. Izvestia Journal of the Union of Scientists – Varna. Economic Sciences Series, 8 (1), 166-173, (in Bulgarian). doi: 10.36997/IJUSV-ESS/2019.8.1

Van Berkel, R., T. Fujita, S. Hashimoto, and Y. Geng (2009). Industrial and urban symbiosis in Japan: analysis of the eco-town. Journal of Environmental Management 90, 1544-1556. https://doi.org/10.1016/j.jenvman.2008.11.010

Katerina Nikolova, Svetlana Bratkova, Anatoliy Angelov, Petia Genova, Rosen Ivanov, Ani Stefanova

ABSTRACT. Mine wastewaters are often characterised with high concentrations of sulphates, heavy metals and increased electrical conductivity. It is mandatory for the industry to implement convenient treatment methods in order to reduce these parameters. The aluminium precipitation with the simultaneous formation of ettringite was chosen for laboratory testing as it is appropriate when the concentrations of sulphates have to be reduced–up to 300 mg/l according to the Bulgarian regulatory framework. In the present study synthetic waters were treated, as their composition was similar to that of typical mining effluents. Initially, the pH of the solutions was adjusted to 9.0 with Ca(OH)2 and thus the heavy metals precipitated in the form of hydroxides. Then, an aluminium source was added as Al–cement, industrial Na–aluminate or aluminium oxychloride. The best results in terms of sulphates and electrical conductivity decrease were obtained with Al–cement (69 – 100 % sulphates removal rate), but the quantities of the generated sludges were large, which raises the question of their proper disposal. With the industrial Na–aluminate the rate of removal of sulphates was very low and with AlOCl it was 96%. However, the use of both reagents showed an increase in the electrical conductivity of the treated solutions.

Keywords: ettringite, sulphates, removal

Nikolova, K., S. Bratkova, A. Angelov, P. Genova, R. Ivanov, A. Stefanova. Treatment of sulphates-rich solutions through ettringite precipitation with industrial reagents
DOI: 10.5281/zenodo.4270121
DOI: https://doi.org/10.58903/a14161833

References

1. Aygun, A., Dogan, S., & Argun, M. E. (2018). Statistical optimization of ettringite precipitation in landfill leachate. Brazilian Journal of Chemical Engineering, 35(3), 969–976. https://doi.org/10.1590/0104-6632.20180353s20170528 

2. Benatti, C. T.; Tavares, C. R. G.; Lenzi, E. (2009): Sulphate removal from waste chemicals by precipitation. Journal of Environmental Management 90: 504-511. DOI: 10.1016/j.jenvman.2007.12.006

3. Bologo V, Maree JP, Carlsson F (2012) Application of magnesium hydroxide and barium hydroxide for the removal of metals and sulphate from mine water. Water SA 38(1):23–28 DOI: 10.4314/wsa.v38i1.4

4. Bowell, R. J. (2000). Sulfate and salt minerals: The problem of treating mine waste. Min. Environ. Mgmt, 11–14.

5. Bowell, R. J. (2004): A review of sulphate removal options for mine waters: mine water 2004 – Proceedings Inter-national Mine Water Association Symposium 2. – 75-91 p.; Newcastle upon Tyne (University of Newcastle).

6. Dou, W., Zhou, Z., Jiang, L.-M., Jiang, A., Huang, R., Tian, X., Chen, D. (2017). Sulfate removal from wastewater using ettringite precipitation: Magnesium ion inhibition and process optimization. Journal of Environmental Management, 196, 518–526. doi: 10.1016/j.jenvman.2017.03.054

7. Fang, P., Tang, Z., Chen, X., Huang, J., Tang, Z., & Cen, C. (2018). Removal of High-Concentration Sulfate Ions from the Sodium Alkali FGD Wastewater Using Ettringite Precipitation Method: Factor Assessment, Feasibility, and Prospect. Journal of Chemistry, 2018, 1–8. doi: 10.1155/2018/1265168

8. Kabdaşlı, I., Bilgin, A., & Tünay, O. (2015). Sulphate control by ettringite precipitation in textile industry wastewaters. Environmental Technology, 37(4), 446–451. doi: 10.1080/09593330.2015.1026245

9. Kießig, G., and Kunze, C., 1996, Wasserbehandlung und Rückstandsentsorgung (Water Treatment and Waste Disposal, in German), Geowissenschaften, Vol. 14, Issue 11, November 1996, p. 481.

10. Liang, H. C.; Tamburini, J. and Johns, F. (2015) Designing a Mine Water Treatment Facility to Remove Sulfate. 10^th ICARD IMRA 2015. DOI: 10.2175/193864710798193671

11. Pehlivanoglu, E & Kabdaşlı, Nuray & Tunay, Olcay. (1998). Sulfate removal by ettringite precipitation. Fresenius Environmental Bulletin. 7. 826-832.

12. Špaldon, T.; Hančuľák, J.; Šestinová, O.; Findoráková, L., Fedorová, E. (2017): Barium Use for Sulphates Removal at Various pH Values, InThynieria Mineralna – STYCZEffi – CZERWIEC <2017> JANUARY – JUNE – Journal of the Polish Mineral Engineering Society. DOI: 10.29227/IM-2017-01-12.

13. Tian, X., Zhou, Z., Xin, Y., Jiang, L.-M., Zhao, X., & An, Y. (2019). A novel sulfate removal process by ettringite precipitation with aluminium recovery: Kinetics and a pilot-scale study. Journal of Hazardous Materials, 365, 572–580. doi: 10.1016/j.jhazmat.2018.11.032

Ivelina Moteva, Plamen Georgiev

ABSTRACT. The main aim of this study was to assess the effects of ferrous iron oxidation, hydrolysis and precipitation of the ferric iron on the mechanisms of arsenate removal from acid mine drainage. The study was realized at the pH range 2,0 – 6,5. H2O2 was the oxidant used in the chemical test. A mixed culture of mesophilic iron–oxidizing chemolithotrophic bacteria (Acidithiobacillus ferrooxidans, Leptospirillum ferroxidans) carried out the ferrous oxidation in the biological test. NaOH was used as an alkalizing agent which triggered the ferric iron hydrolysis and precipitation. The results showed that the total content of retained arsenic by ferric iron hydrous oxides and its speciation as geochemical fractions depended on the iron and phosphate concentrations in acid solution. The results showed that phosphate concentration lower than 6 mg/ L limited the ferrous iron oxidation rate. At the tested experimental conditions, arsenic sorption by formed ferric iron hydrous oxides was the main mechanism for its removal from acid mine drainage, as the ratio between iron and phosphate determined the proportions between the geochemical fractions of scavenged arsenic.

Keywords: arsenate, ferric iron, ferrous iron oxidation, sorption, fractions

Moteva I., P. Georgiev. Effects of the iron oxidation and precipitation processes on the arsenate sorption and coprecipitation
DOI: 10.5281/zenodo.4270111
DOI: https://doi.org/10.58903/a14161832

References

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6. Georgiev, P., I. Zheleva, S. Groudev, M. Nicolova, I. Spasova. 2017. Effects of some factors on the iron removal from rich-in-iron waste solutions by means of goethite and hematite precipitation processes. Journal of Mining and Geological Sciences, 60, part II, Mining, Technology and Mineral Processing, 131-135.

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10. Singhania, S., Q. Wang, D. Filippou, G.P. Demopoulos. 2005. Temperature and seeding effects on the precipitation of scorodite from sulfate solutions under atmospheric pressure conditions. Metall. Mater. Trans. B 36, 327–333. https://doi.org/10.1007/s11663-005-0062-8

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13. Tuovinen, O.H., S.I. Niemelä, H.G. Gyllenberg. 1971. Effect of mineral nutrients and organic substances on the development of Thiobacillus ferrooxidans. Biotechnology & Bioengineering 13, 517-527.  https://doi.org/10.1002/bit.26013040

14. Tuovinen, O.H., D.P. Kelly. 1973. Studies on the growth of Thiobacillus ferrooxidans: I. Use of membrane filters and ferrous iron agar to determine viable numbers and comparison with CO₂ fixation and iron oxidation measures of growth. Archives on Microbiology 68, 285. https://doi.org/10.1007/BF00409941

15. Zheleva, I., P. Georgiev, S. Groudev. 2016. Adsorption/ desorption of arsenate on/ from goethite and hematite, Annual of University of Mining and Geology “St. Ivan Rislki”, vol.59, II, 137-141.

16. Zheleva, I., P. Georgiev. 2019. Study of adsorption/ desorption of arsenate on/ from goethite-covered quartz sand underflow regime of operation. Journal of Mining and Geological Sciences, 62, 1, 89-94.

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18. Wenzel, W., N. Kirchbaumer, T. Prohaska, G. Stingeder, E. Lombi E, D.C. Adriano. 2001. Arsenic fractionation in soils using an improved sequential extraction procedure. Analytica Chimica Acta 436, 309 – 323. https://doi.org/10.1016/S0003-2670(01)00924-2

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Zdravka Mollova, Vladimir Penev

ABSTRACT. This article presents some of the studies on drilling and blasting technologies applied in the Assarel copper mine. The main emphasis is on examining the seismic effects on a particular engineering facility, located on the territory of the mine – CPT–3. The assessment of the blast– induced seismic loading on the structure is based on an analysis of the registered data on the site. Recommendations for the design of blasting parameters are provided.

Keywords: blast–seismic impact, drilling and blasting technologies, blast–induced seismic vibrations, technological blasting

Mollova, Z., V. Penev. Control of blast-induced seismic action generated by technological blastings
DOI: 10.5281/zenodo.4270102
DOI: https://doi.org/10.58903/a14161831

References

1. Mitkov, V. 2010. Bezopasnost pri proizvodstvo i upotreba na eksplozivi. Sv. Ivan Rilski, Sofia – 343 p. ISBN 978-954-353-131-8. (in Bulgarian)

2. Mitkov, V., Genchev, G. 2009. Determination of the safe distances for window glasses of buildings during detonation of makeshift explosive devices. – Annual of the University of Mining and Geology “St. Ivan Rilski”, 52, Part 2, 157−162 ISSN 1312-1820.  (in Bulgarian with English abstract).

3. Mitkov, V. 2007.  Za bezopasnostta na eksplozivite za grazhdanski tseli.– Annual of the University of Mining and Geology “St. Ivan Rilski”, 50, Part 2, 109−114 ISSN 1312-1820. (in Bulgarian).

4. Mitkov V. 2010. Assessment and risk management of malicious acts aimed at potentially hazardous Hydrotechnical constructions.- Conference proceedings from the International conference of Blasting techniques, Stara Lesna, Slovak Republic, 212-220, ISBN 978-80-970265-2-3.( in English )

5. Mitkov V. 2014. Vliyanie vida donornogo zaryada na skorosty detonatsii granulitov.- Mining informational and analytical bulletin, Moskva, № 9, 305-309, ISSN: 0236-1493. (in Russian)

6. Mitkov V. 2014. Novyye vodoustoychivyye vzryvchatyye veshchestva na osnove energeticheskikh materialov utiliziruyemykh boyepripasov.- Mining informational and analytical bulletin, Moskva, № 11, 312-316, ISSN: 0236-1493. (in Russian)

7. Mitkov, V et al. 2015. Task report: Process Audit of Drilling and Blasting Operations in Copper Ore Mine Asarel. Sv. Ivan Rilski, Sofia (in Bulgarian) 

8. Shiskov, P. 2019. Spravochnik na vzrivnika. Izdatelska kashta Sv. Ivan Rilski, Sofia – 244 p. ISBN 978-954-353-378-9 (in Bulgarian)

9. Shishkov P., Stoycheva N., 2018. Savremenni vzrivni tehniki za dobiv na skalno-oblicovachni materiali – Mining and geology magazine, 10-11, 42-49, ISSN 0861-5713 (in Bulgarian with English abstract)

10. Shishkov P., Stoycheva N., 2019. Application of long term stored single and double based propellants in advanced blasting methods for dimension stone extraction – NTREM 2019 – New trends in research of energetic materials, Pardubice, 09 – 11.04.2019, CZ, Proceedings Part 1, pp.619-629, ISBN 978-80-7560-210-7(in English)

Ivan Minin, Petko Nedyalkov, Simeon Savov, Teodora Hristova

ABSTRACT. The article discusses the topic of the specific power consumption of a drum mill type SAG 8.5×5.3. The purpose of the study is to determine the influence of some basic parameters like angular velocity of the mill drum, the wear on the drum’s lining, mass of the mill filling, loading rate of the mill with ore and flow rate of incoming water of the product to be milled on the relative power consumption of the mill for maintaining quality.
To determine the energy consumption of the mill, the listed parameters were measured and a Fisher matrix was constructed. In accordance with the selected target function, energy consumption patterns are synthesised depending on the loading rate of the mill with ore, the mass of the mill filling, the flow rate of the incoming water and the wear on the drum’s lining. Data processing was performed using the STATGRAPHICS computer programme and an adequate model has been found according to the selected target function. The target function has been found to satisfy the conditions for maintaining quality and reducing costs.

Keywords: drum mill, relative power consumption, mass of the mill filling, loading rate

Minin, I., P. Nedyalkov, S. Savov, T. Hristova. Study of the relative energy consumption of a drum mill type SAG 8.5 x 5.3
DOI: 10.5281/zenodo.4270097
DOI: https://doi.org/10.58903/a14161830

References

1. Bojanov, Е. S., Vuchkov, I. N., 1973, Statisticheski metodi za modelirane i optimizirane na mnogofaktorni obekti, Sofia, Tehnika.

2. Bojanov, Е. S., Vuchkov, I. N., 1979, Statisticheski reshenia v proizvodstvoto I nauchnite izsledvania, Sofia, Tehnika.

3. Boteva A., Vladkova B., 2002, New selective collector for flotation of sulfide ores, Annual of the University of Mining and Geology “St. Ivan Rilski”, 45, Part 2, 67-70

4. Dzhustrov K., 2019, Influence of the ball load on the specific power consumption of ball mills, Journal of mining and geological sciences Vol. 62, part 3, p. 77-81

5. Hristova T., 2015, Investigation of specific energy consumption in the SAG milling copper ores, Annual of the University of Mining and Geology “St. Ivan Rilski”, 58, part Mechanization, Electrification and Automation in Mines, p.81-85

6. Hristova T., Ivan Minin, Dimitar Mitev, 2018, Determination of relative energy consumption of a jaw crusher in depending on the width of the discharge port  and of the particle size distribution of the crushing product, Journal of Mining and Geological science, 61s, part Mechanization, Electrification and Automation in Mines, vol. 61, p.13-17, ISSN 2535-1192

7. Istalianov R., N. Lakov, 2019,  Energy control on the linings wear of semi-autogenous mills, Journal of Mining and Geological science, 62s, part Mechanisation, Electrification and Automation in Mines, vol. 62, 2019, p.104-106, ISSN 2682-9525

8. Mryankov I., Ivanov A., 2007, Izsledvane na prostranstvenite treptenya na vibratsionna melnitsa. “Mehanika na machinite”, issue. 68, XV,  № 2, Izdatelstvo TU-Varna, 130-133

9. Nikolov E., N. Nikolova, 2006, Analysis of energy losses in the valve of control system, – In Proc of IFAC ESC 2006 WS: Energy saving control in plants and buildings, October 2 – 5, 2006 Bansko, Bulgaria, 2006 IFAC, ISBN-10:954-9641-47-3, ISBN-13:978-954-9641-47-9, 135-140 https://doi.org/10.3182/20061002-4-BG-4905.00023

10. Nikolova N., E. Nikolov, 2006, Energy saving algorithms and control system, – In Proc of IFAC ESC 2006 WS: Energy saving control in plants and buildings, October 2 – 5, 2006 Bansko, Bulgaria, 2006 IFAC, ISBN-10: 954-9641-47-3, ISBN-13: 978-954-9641-47-9, 141-146 https://doi.org/10.3182/20061002-4-BG-4905.00024

11. Nyandwe E. M, Zhang Q., Wang D., 2020, Optimization of Ore Production in Copper Mine, American Journal of Industrial and Business Management, 10, 61-74 DOI:  10.4236/ajibm.2020.101005

12. Stoyanov A., 2015, A task for the movement of a rigid body with the fixed point, Annual of the University of Mining and Geology “St. Ivan Rilski”, 58,Part3, 119-121 (in Bulgarian with English abstract).

13. Uțu I., Stochițoiu M. D, Samoilă L., Handra A.D., 2020, Active power filters in order to limit the harmonic disturbance from electrical networks, Annals of the University of Petrosani, Electrical Engineering, 20 (2018)

V. A. Luganov, T. A. Chepushtanova, G. D. Guseynova, Y. S. Merkibayev, K. K. Mamyrbaeva, B. Mishra

ABSTRACT. The paper presents the results of the development of a technology for processing of pyrite concentrates with the extraction of non–ferrous metals, iron and sulphur using the technology of two–stage dissociating roasting with hydrometallurgical processing of cinder. Hydrometallurgical processing of cinder was studied. It comprised of two steps – cinder leaching and extraction for processing multi–component solutions. Based on the results of laboratory tests, balance experiments were conducted on the chemical enrichment of nickel –poor and cobalt–pyrite concentrates. The experiments included (i) Thermal decomposition of pyrite concentrate at a temperature of 660 – 700° C and a duration of 60 minutes, an oxygen flow rate of 30–50% of the stoichiometric; (ii) Leaching of the cinder with a HCl solution at a temperature of 90°C, liquid: solid = 8:1, pH 2,7 and a duration of 60 minutes; (iii) Filtration of pulp and precipitation of nickel and cobalt from solutions with iron sulphide. During leaching, mainly iron is transferred to the solution; nickel and cobalt remain in a small amount of cake (the cake weight is reduced by almost ten times compared to the thermal decomposition product). As a result, up to 99% of non–ferrous metals are extracted into the concentrate, and the solution becomes more concentrated in iron.

Keywords: pyrite concentrates, sulphidising roasting, nickel and cobalt, hydrometallurgical processing

Luganov, V.A., T.A. Chepushtanova, G.D. Guseynova, Y.S. Merkibayev, K.K. Mamyrbaeva, B. Mishra. Processing of pyrite concentrates with the extraction of non-ferrous metals: nickel and cobalt technology elaboration
DOI: 10.5281/zenodo.4270170
DOI: https://doi.org/10.58903/a14161829

References

1. Li, B.J., Liao, Y.L., Hu, L., Zhou, J., Huang, F.-R. A review on research for separation of nickel and cobalt in solution. Huaxue Gongcheng/Chemical Engineering (China). 43(8).2015. -Pp.  33-37, (in English). DOI: 10.3969/j.issn.1005-9954.2015.08.008

2. Selivanov, E.N., Klyushnikov, A.M., Gulyaeva, R.I. Application of Sulfide Copper Ores Oxidizing Roasting Products as Sulfidizing Agent During Melting Nickel Raw Materials To Matte. Metallurgist, 63(7-8). 2019.- Pp. 867-877, (in English). https://doi.org/10.1007/s11015-019-00901-z

3. Sadykhov, G.B., Anisonyan, K.G., Kop’ev, D.Y., Goncharov, K.B., Olyunina, T.V. Development of a Low-Temperature Bloomery Process for Nickel and Cobalt Recovery from Saprolite Ores. Russian Metallurgy 2020(3). -Pp. 165-179, (in English). https://doi.org/10.1134/S003602952003009X

4. Merkibaev Y., Panayotova M., Luganov V., Panayotov V., Chepushtanova T. Sulphidation roasting as means to recover zinc from oxidised ores. Comptes rendus de l’Acad´emie bulgare des Sciences. Tome 71, No 8, 2018, P. 1116-1123, (in English). DOI: 10.7546/CRABS.2018.08.14

5. Motovilov I. Y., Luganov V. A., Mishra B., Chepushtanova T. A.. Oxide powders production from iron chloride. CIS Iron and steel review. Vol. 15, pp. 2018, 28-32, (in English). DOI: http://dx.doi.org/10.17580/cisisr.2018.01.06

Nadezhda Kostadinova

ABSTRACT. Tunnel construction has become an important and growing activity. Tunnelling is an important part of transport infrastructure and is a part of the sustainable development of the country. The tunnel ventilation during construction and operation is part of the whole design procedure. Although ventilation might be performed with different approaches, longitudinal ventilation with jet fans is most often employed. The efficiency of such devices depends on several factors – design parameters, location in the tunnel, interaction with main current. The last one is crucial in emergency situations, especially during fires when both temperature and density of main current change. One important point in normal and emergency ventilation design is the downwind influence of jet fans. This paper presents a longitudinal scheme with jet fans. Based on energy and mass conservation, the interaction between the jet fan and the main current is considered, leading to expressions for areas of impact. Several models for fire temperature distribution downstream are presented, outcomes are compared and suggestions for use are made. Additionally, jet fan efficiency coefficients are adjusted due to modelling results.

Keywords: jet fans, longitudinal ventilation, jet fan efficiency, road tunnels

Kostadinova, N. Jet fans efficiency in tunnel emergency situations
DOI: 10.5281/zenodo.4270086
DOI: https://doi.org/10.58903/a14161828

References

1. Beyer M., Peter J. Sturm, Saurwein M., Bacher M., 2016, Evaluation of Jet Fan Performance in Tunnels, 8th Int. Conf. Tunnel Safety and Ventilation, Graz, 

2. Beyer M., Höpperger B., Sturm P.J., Bacher M., Croll J., 2012, Impact of the Consideration of Hot Smoke Gases in the Design of Ttansverse Ventilation Systems, 6^th Int. Conf. ‘Tunnel Safety and Ventilation’, Graz, At Graz, 211-221.

3. Cafalo E., V. Bertola, 2010, Fires in Tunnels: Experiments and Modelling, The Open Thermodynamics Journal, 4, 156-166, ISSN 1874-396X DOI:  10.2174/1874396X01004010156

4. CETU 2003: Dossier pilote des tunnels equipements, section 4.1. Ventilation, ISBN 2-11-084740-9, 155, https://www.cetu.developpement-durable.gouv.fr/IMG/pdf/DP_ventilation_cle557d66-3.pdf

6. Del Rey, I., Fernández, S.; Fraile, A; Espinosa I, 2012, Simplified Method for Longitudinal Ventilation System Design in Fire Situation, 6th Int. Conf. ‘Tunnel Safety and Ventilation’, Graz, 195-202

7. Guihong Pei and Jie Pan, 2014, Numerical Study on Different Series Modes of Jet Fan in a Longitudinal Tunnel Ventilation System, Hindawi Publishing Corporation Mathematical Problems in Engineering, Vol. 2014, Article ID 194125, 9 p., http://dx.doi.org/10.1155/2014/194125

8. Ingason H., Li Y., 2010, Model Sacle Tunnel Fire Tests with Longitudinal Ventilation, Fire Safety Journal, vol. 45, pp. 371-384, DOI: 10.1016/j.firesaf.2010.07.004

9. Kempf, J., 1965, “Einfluss der Wandeffekte auf die Treibstrahlwirkung eines Strahlgebläses: ein Beitrag zur Aerodynamik der Tunnellüftung”, Schweizerische Bauzeitung, vol.83/4, 47-52. doi.org/10.5169/seals-68079

10. Kuda R. Mutama, Allan E. Hall, 1999, Theoretical Analysis of Jet Fan Performance Using Momentum and Energy Considerations, Proc. of the 8th US Mine Ventilation Symposium, 469-476.

11. Lonnermark A., 2005, On the Characteristics of Fires in Tunnels, ISBN 91-628-6637-0, 122

12. Mutama K., 1995, Wind tunnel investigation of Jet fan Aerodynamics, PhD Thesis, The University of British Columbia, https://open.library.ubc.ca/cIRcle/collections/ubctheses/831/items/1.0078620

13. Naredba № RD-02-20-2 ot 21 dekemvri 2015 g. za tehnicheski pravila i normi za proektirane na patni tuneli, DV broy 8, 29.01.2016

14. PIARC, 2007, Systems and Equipment for Fire and Smoke Control in Road Tunnels, PIARC Committee on Road Tunnels (C5), 2007, ISBN 2-84060-175-3.

15. Tarada F, R Brandt, HBI Haerter Ltd, 2009, Impulse Ventilation for Tunnels – A State of the Art Review, 13th International Symposium on Aerodynamics and Ventilation of Vehicle Tunnels, New Brunswick, New Jersey, USA

16. Vlasseva El., 2015, Ventilacija na transportni tuneli, Izd. kushta “Sv. Ivan Rilski”, Sofia, pp. 96, ISBN 978-954-353-286-5 – in Bulgarian

17. Vlasseva E, Z. Dinchev, “Natural and Mechanical Ventilation interaction in Road Tunnels”, Annual of the University of Mining and Geology “St. Ivan Rilski”, Volume 58, part II, Mining and Mineral Processing, Sofia, 2015, p.67-72, (ISSN 1312-1820) –( in Bulgarian with English abstract)

18. Yotova M., Georgiev B., Vladkova B., Karadjova V., 2017, Analiz na pozharnia risk pri gorene na materiali, otdelyashti tsian-sadarzhashti saedinenia, VIII Nauchna konferentsia s mezhdunarodno uchastie i izlozhba, “grazhdanskata bezopasnost”, MVR Akademia, Sofia, 6 – 7 april 2017, , pp. 177-181, ISSN 1313-7700 (in Bulgarian)

Dimitar Kaykov, Ivaylo Koprev

ABSTRACT. The location for dumping the waste from the open–pit mine has a significant weight for the establishment of the waste treatment costs. According to the constructive parameters of the waste dump and the terrain’s characteristics, the volume of the affected area is determined, in relation to the waste volume generated from the exploitation of a mineral deposit. In order to optimise the waste dump’s location and its constructive parameters, a number of alternatives have to be taken into account. These alternatives have to be technically plausible, as well as their safety factor must be satisfactory. Based on the considered alternatives, the optimisation problem can be defined so that the optimal solution provides the required capacity of the waste dump, as well as a minimal area of negative environmental impact and lowest operational costs.

Keywords: waste dump, optimisation, location, costs

Kaykov, D., I. Koprev. Rationalising the location and design of the waste dump in the case of open-pit mining
DOI: 10.5281/zenodo.4270076
DOI: https://doi.org/10.58903/a14161827

References

1. Aleksandrova, E., 1999. Algorithm for optimization of dump slopes in the East Maritza coal basin. – Annual of the University of Mining and Geology “St. Ivan Rilski”, Vol. XLII. p.21, (in Bulgarian);

2. Aleksandrova, E., 1998. Optimization of the technology of open pit mining for minimizing losses in land reclamation. State and development of open pit mining in market economy, 5^th National open pit mining conference with international participation, 2-6^th June, Varna, Bulgaria, (in Bulgarian with Russian abstract), p. 183, (in Bulgarian);

3. Anachkov, A., G. Konstantinov, 1985, Open pit mine design. Sofia, “Tehnika” publishing, p. 72, (in Bulgarian);

4. Atanasov, A., P. Zlatanov, D. Stoyanov, S. Hristov, 2001. Open-pit mining technology. Sofia, ISBN 954-9748-39-1

5. Hristov, S., E. Aleksandrova, 2000. Timely land reclamation for the areas, disturbed by the “Maritza Iztok” mines – a necessary condition for their efficiency. Geology and mineral resources, Vol. 9, p. 21, (in Bulgarian)

6. Ortiz, J.P., 2017. Methodology for a Dump Design Optimization in Large-Scale Open Pit Mines. Civil & environmental engineering. Cogent Engineering (ISSN: 2331-1916 https://doi.org/10.1080/23311916.2017.1387955

Yassen Gorbounov, Petar Peychinov

ABSTRACT. The magnetic levitation consists of balancing the forces of attraction and repulsion of a ferromagnetic object located in a foreign magnetic field in such a way as to keep a desired distance between the object and the magnet. This technology is receiving increasing attention because it helps to eliminate the frictional losses due to the lack of mechanical contact. This makes it possible to reduce the wear of critical machine parts and achieve high speeds with increased positioning accuracy. Advanced applications include the high–speed Maglev trains, magnetic bearings and suspension, electromagnetic cranes, high–accuracy positioning of wafers in photolithography in the manufacturing of integrated circuits, and other high–precision contactless positioning devices. Positive results are also observed in applications from the mining and processing industry in the extraction and processing of raw materials, which makes the topic relevant. The paper presents a laboratory model of a single degree of freedom electromagnet–based system intended to aid the studying of the effect of magnetic levitation. The possibilities for the
implementation of different positional feedback types are discussed together with the power circuit that drives the electromagnet. A mathematical model and implementation of a fully digital algorithm that uses the PID control law are presented. Experiments are conducted that could aid in building a sensorless control system. The elaborated laboratory model allows for easy upgrade and can be used in disciplines in the field of
measurement, control, and automation as a whole.

Keywords: Magnetic Levitation, Pulse Width Modulation, Programmable Logic Device, Processing of Raw Materials

Gorbounov, Y., P. Peychinov. Laboratory model of a magnetic levitation system
DOI: 10.5281/zenodo.4270069
DOI: https://doi.org/10.58903/a14161826

References

1. Alexandrov, R., A. Zabtchev. 2013. Electronic System for Demagnetisation in Magnetic Separation, Journal of the TU–Sofia Plovdiv branch, Bulgaria, Vol. 19 “Fundamental Sciences and Applications”, Book 1, pp. 205-208, ISSN 1310 – 8271 (in Bulgarian with English abstract)

2. Feedback Instruments, 2019. Magnetic Levitation Control Experiments, Feedback Instruments Ltd., Park Road, Crowborough, East Sussex, TN6 2QR, UK, Manual 33-942S Ed01 122006, Feedback Part No. 1160-33942S, http://www.cpdee.ufmg.br/~palhares/33-942s.pdf

3. Hiroyuki, O. 2000. Levitation Characteristics of Magnetic Bearings using Bulk Superconductors as a Field Shaping Material, Advances in Superconductivity XII, Springer, Tokyo, ISBN 978-4-431-70270-2 https://doi.org/10.1007/978-4-431-66877-0_233

4. Hull, J., J. Fiske, K. Ricci, M. Ricci. 2007. Analysis of Levitational Systems for a Superconducting Launch Ring, IEEE Transactions on Applied Superconductivity, vol. 17, no. 2, pp. 2117-2120, , ISSN 1051-8223 doi 10.1109/TASC.2007.898464

5. Hyung, L., K. Kim, J. Lee, 2006. Review of maglev train technologies, IEEE Transactions on Magnetics, Vol. 42, No. 7, pp. 1917-1925, , ISSN 0018-9464 DOI 10.1109/TMAG.2006.875842

6. Inteco, 2005. Magnetic Levitation System (MLS) User’s Manual version 1.6 for MATLAB 6.5, Inteco, ul. Katowicka 36, 31-351 Krakow, Poland, TIN PL6771821666, http://www.inteco.com.pl/products/magnetic-levitation-systems/

7. Lahdo, M., T. Ströhla, S. Kovalev. 2018. Research on a 6-DoF Magnetic Levitation System, 53rd International Universities Power Engineering Conference (UPEC), Glasgow, pp. 1-5, ISBN 978-1-5386-2911-6  DOI:10.1109/UPEC.2018.8541883

8. Manoj, L., J. Nithesh, T. Manjunath, S. Gowreesh. 2019. Power Generation using Magnetic Levitation Vertical Axis Wind Turbine, International Journal of Engineering and Advanced Technology, Vol. 9, Issue 2, , ISSN 2249 – 8958 DOI 10.35940/ijeat.B3153.129219

9. McNab I. 2003. Launch to space with an electromagnetic railgun, IEEE Transactions on Magnetics, vol. 39, no. 1, pp. 295-304, ISSN 0018-9464 doi 10.1109/TMAG.2002.805923

10. Peng, Z., J. Xie, F. Gu, N. Sharmin, P. Hall, J. Fu. 2018. Separation of mixed waste plastics via magnetic levitation, Waste Management, ISSN 0956-053X, doi 10.1016/j.wasman.2018.02.051

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13. Qiao, X., T. Xiaoping. 2020, The Stability of Magnetic Levitation Milling System Based on Modal Decoupling Control, Hindawi Shock and Vibration, Article ID 7839070, doi 10.1155/2020/7839070

14. Quanser, 2019. MAGLEV: Magnetic Levitation Plant, Document No. 525 Rev. 03, Quanser Ltd. 119 Spy Court Markham, ON L3R 5H6 Canada, https://www.quanser.com/products/magnetic-levitation/

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16. Vuchic, R., J. Casello. 2002. An Evaluation of Maglev Technology and Its Comparison With High Speed Rail, Transportation Quarterly 56(2), 33-49, ISSN 0278-9434 https://repository.upenn.edu/cgi/viewcontent.cgi?article=1887&context=ese_papers

17. Wang, Y., T. Logan, A. Smith, P. Hsu, W. Cohn, L. Xu, R. McMahon. 2016. Systematic Design of a Magnetically Levitated Brushless DC Motor for a Reversible Rotary Intra-Aortic Blood Pump. 24th Congress of the International Society for Rotary Blood Pumps, Japan, 41(10), 923-933, doi 10.1111/aor.12965

18. Yaghoubi, H., 2013. The Most Important Maglev Applications, Hindawi Publishing, Journal of Engineering, Article ID 537986, http://dx.doi.org/10.1155/2013/537986

Plamen Georgiev, Maria–Filipa Ivanova, Marina Nicolova, Irena Spasova, Stoyan Groudev

ABSTRACT. Iron is usually present in higher concentrations in the laden solutions and its removal and elimination to a stable phase is a severe problem in hydrometallurgy. This article analyses and compares the processes of solvent extraction and ion exchange as methods for the iron separation and concentration in a sufficient amount, which would enhance its further removal to products with potential for application to other industries. The factors affecting the goethite, hematite and magnetite processes and the area of use of the produced iron oxides are reviewed.

Keywords: iron, processing, hematite, magnetite, hydrometallurgy

Georgiev, P., M. F. Ivanova, M. Nicolova, I. Spasova, S. Groudev. Review of the iron recovery processes from laden leach liquors in hydrometallurgy
DOI: 10.5281/zenodo.4270054
DOI: https://doi.org/10.58903/a14161825

References

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Blagica Doneva, Marjan Delipetrev, Gorgi Dimov

ABSTRACT. The reservoir was built in the middle of the 20th century with a total capacity of 750,000 m3. The height of the dam from the river terrace is 22 m, the length of the crown is 319 m, and the width of the crown is 6 m. Due to the low resistance of the earth dam and the increase of water level due to heavy rains, the lake has leaked on several occasions, causing floods and environmental disaster in the surrounding settlements. Due to heavy rains and overflow through the dam crown, damage to the downstream slope of the dam has occurred and the overall stability of the dam has been compromised. By controlled discharge of the reservoir it is brought to a stable state and the dam breakage is pr evented. At the beginning of 2013, the outflow valves of the dam were opened as a result of heavy rains, with reservoir water flowing to more places and residents of the village and livestock evacuated. At the crown of the dam where there was the largest outflow of water, a gap of about 20 m wide and 3.5–4 m thick appeared. Geophysical – seismic surveys have been conducted to determine dam damage.

Keywords: dam, seismic, reflection, refraction, damage

Doneva B., M. Delipetrev, G. Dimov. Seismic explorations for defining the damage to the earth dam Pishica in the Republic of North Macedonia
DOI: 10.5281/zenodo.4270040
DOI: https://doi.org/10.58903/a14161824

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Svetlana Bratkova, Zlatka Alexieva, Anatoliy Angelov, Katerina Nikolova, Petia Genova, Rosen Ivanov, Maria Gerginova, Nadejda Peneva

ABSTRACT. The influence of hydraulic retention time (HRT) on the rate of sulphate–reduction and electricity generation of microbial fuel cell fed with ethanol was studied. The experiments were performed in the laboratory installation, consisting of an anaerobic fixed–bed reactor and a microbial fuel cell with air–cathode. An effective sulphate removal was achieved at hydraulic retention times 44 and 66 h. The effectiveness of COD removal raises with increasing the hydraulic retention time. The highest maximum power density of 258 mW/m2 was obtained at 22 h HRT. The use of ethanol as an electron donor had a great impact on the composition of the microbial community. The metagenomic data obtained showed that the most abundant phylum in bacterial community was Proteobacteria – 87.8 %, and particularly Gammaproteobacteria – 53,1%. The sulphate reducing bacteria that can incompletely oxidise organic compounds usually with acetate as an end product were presented in the microbial community in anodic chamber. The dominant microbial species among sulphate reducing bacteria was Desulfomicrobium mexicanus (19,79%).

Keywords: Microbial fuel cell, Sulphate reduction, Microbial community, Metagenomic analyses, Wastewater treatment

Bratkova, S., Z. Alexieva, A. Angelov, K. Nikolova, P. Genova, R. Ivanov, M. Gerginova, N. Peneva. Efficiency of microbial fuel cells based on the sulphate-reduction by ethanol DOI: 10.5281/zenodo.4270025
DOI: https://doi.org/10.58903/a14161823

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Georgios-Michail Bimpilas, Georgios N. Anastassakis

ABSTRACT. Magnesite is one of the most important mineral commodities mostly because of its technological and industrial applications. The most important commercial sources for its recovery are the corresponding ores. The deposits are characterised by the differences in reference to magnesite mineral crystallinity and gangue composition. For these reasons, the separation efficiency of magnesite from gangue varies from relatively easy to impossible. Another problem is the stocked waste, often of relatively high–grade in magnesite, derived from industrial processing, which may be viewed as future potential deposits. This paper contributes a detailed review on the methods applied to separate magnesite from gangue both on industrial and bench scale; potential processing methods for fine particle size are also reviewed.

Keywords: separation methods of magnesite, magnesite processing, magnesite flotation, serpentine

Bimpilas, G.-M., G.N. Anastassakis. Magnesite beneficiation methods: a review
DOI: 10.5281/zenodo.4269873
DOI: https://doi.org/10.58903/a14161822

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Simeon Asenovski, Dimitar Kaikov

ABSTRACT. In the present economic situation, the open–pit mining processes require flexible solutions for achieving the set goals. The aim of the study is to consider a comprehensive mathematical model for a short and long term open–pit mine optimisation in a truck scheduling problem. The model can be applied in different situations with various number of units and trajectories depending on the landscape of the area in question. Significant amount of parameters modulating the discussed processes is analysed.

Keywords: time scale optimisation, truck scheduling

Asenovski, S., D. Kaikov. Open-pit time scale optimisation in a truck scheduling problem

DOI: 10.5281/zenodo.4269988
DOI: https://doi.org/10.58903/a14161821

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Yordanka Anastasova

ABSTRACT. The Internet of Things are essentially huge networks of connected devices that collect and share data (information) both for specific processes and their application environment. The use of the Internet of Things (IoT) is changing every industry because it allows device-to-device communication and automates the maintenance, communication, and interaction between processes and their management. IoT gives businesses real-time information on how their companies’ systems work, significantly reducing labour costs. For this reason, more and more mining companies are taking advantage of the opportunities provided by IoT, creating their own networks of devices and communication environment. At the same time, IoT has become one of the most critical technologies of our century, due to the fact that cloud technologies and Wi-Fi networks, which are the basis of IoT, have become an attractive place for cyberattacks. The data collected by IoT sensors contain a huge amount of personal and company information, hence, it is especially important that they are securely stored and maximally protected. This article discusses some critically important technologies to ensure the security of IoT implementation and use in the mining industry.

Keywords: Internet of Things, mining industry, implementation, security technologies

Anastasova, Y. Internet of Things in the mining industry – security technologies in their application
DOI: 10.5281/zenodo.4275895
DOI: https://doi.org/10.58903/a14161820

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