Comparative study of mechanical activation of molybdenite (MoS2) with and without magnesium (Mg) addition

Molybdenite concentrate was mechanically activated in the presence of magnesium metal using a planetary mill in order to try to form elemental molybdenum. A sample milled for 90 min in planetary mill showed almost the same structural distortion as after 50 h in a tumbling mill, neither showed the presence of molybdenum metal. However, molybdenite milled together with magnesium showed more amorphization than separately milled molybdenite. Despite the apparent lack of reaction, molybdenite showed higher solubility in dilute HCl after milling with magnesium than without.Mongolian Journal of Chemistry 16 (42), 2015, 30-3

Leaching of a Mongolian chalcopyrite concentrate

A Mongolian chalcopyrite flotation concentrate was leached using sodium hypochlorite adjusted to different pH using hydrochloric acid. It was found that using a starting pH of below 5.0 resulted in more efficient leaching. The extent of chalcopyrite leaching was determined by the concentration of sodium hypochlorite with > 40% dissolution being achieved. The residue after leaching was found to consist primarily of unreacted chalcopyrite which would be suitable for further leaching or smelting

Characterisation of fly ashes from 4th Thermal Power Station of Ulaanbaatar city and its applicability for a zeolite synthesis

Fly ash from 4th thermal power station of Ulaanbaatar city have been characterised by x-ray fluorescence (XRF), x-ray diffractometry (XRD), particle size analyzer, specific surface area measurement (BET) and scanning electron microscope (SEM) observation. It was found that fly ash from Baganuur coal contains over 15 wt.% of calcium oxide (CaO) and could be assigned as class C fly ash, according to the International classification. Specific surface area of this fly ash was 2.75 m2/g and mean particle diameter was 59.5 μm. Zeolitic compounds were synthesised by using mixture of this fly ash and a transition aluminium oxide under hydrothermal treatment at 100, 150 and 200°C temperatures for a different duration. Various zeolitic compounds including Na-faujasite and sodium aluminosilicate were synthesised as reaction products.DOI: http://dx.doi.org/10.5564/mjc.v12i0.164 Mongolian Journal of Chemistry Vol.12 2011: 16-19

Preparation of rare earth oxides from Synchysite oxidized ore by acid leaching

Mixed rare earth oxides have been prepared from synchysite ore from the Lugiin gol rare earth deposit (Mongolia) which contains about 6% of cerium light rare earth elements. Ore powders were leached for up to 60 min using 80-120 g/l sulfuric acids at an acid to powder ratio of 20, agitation was performed by magnetic stirring followed by precipitation and calcination at 700°C for 1h. The highest leaching of REEs equal to 85% of the total REE was observed in the acid solution of 80 g/l. Obtained mixed rare earth oxides represent a layered type structure

Characterization of ash pond ashes from 3rd thermal power plant by SEM/EDX and XRD methods

  Coal combustion by products from ash pond of 3rdthermal power plant of Ulaanbaatar city have been collected in 2010 and 2013 years. The ash samples have been characterized by XRD, XRF and SEM-EDX methods in order to evaluate their chemical and mineralogical composition changes with disposed times. The mineralogical composition of ash varies with time though the chemical composition of the ashes were close each other. Possibly, inefficient operating condition of the TPS shows influence on the mineralogical composition.DOI: http://dx.doi.org/10.5564/mjc.v14i0.201Mongolian Journal of Chemistry 14 (40), 2013, p61-6

MITOCHONDRIAL DNA ANALYSIS OF ANCIENT DOMESTIC GOAT IN THE MONGOLIA

Food and agricultural production sector, especially livestock production is vital for Mongolia’s economic and social development. The five breeds of livestock – cattle, horses, sheep, goats and camels, have always been directly related to the history, culture and economy of Mongolia. It is undeniable that these five breeds of livestock are considered as an important asset of the Mongolian economy as well as guarantee of national security. Out of the five breeds, small livestock including sheep and goats account for more than 80% of the total livestock population (according to the National Statistical Office data). It is not hard to retrieve research and recorded materials about the morphology or the economic productivity of these breeds and their sub-breeds. However, the development of society now demands higher yield from the livestock animals. Genetically, the a1, a2, a3 and a4 samples appertaining to some 3,000 years ago are substantially different from the haplogroups. However, judging by the phylogenetic tree the 800 year-old samples, as compared to the phylogroups of the 3rd century BC, are closer to the modern samples. Alongside this, from molecular distance we find that the M1 haplogroup is a sample belonging to the 3rd century BC, which had separated the earliest, while the aforementioned 800 year-old sample separates at a later period, which chronologically is convincing. But the a6 ancient sample conforms to the B haplogroup and the a8 or the sample of 800 years ago is in the same haplogroup as the sample of the 3rd century BC. However, the a6 sample obtained from the 3rd century BC tombs obtained sample was the origin of modern goats that can be included in haplogroup B

The mechanochemical activation study of Tsagaan-tsav zeolite

Characterisation of mechanochemically activated Tsagaan-tsav zeolite has been performed. Tsagaan-tsav zeolite has been activated with a vibration mill for 2, 3, 5, 10 and 20 minutes. Ball to powder ratios were varied 1:10, 1:20, 1:50 and 1:100. Efficiency of milling determined based on amorphisation rate and cation exchange capacity changes. The highest efficiency was obtained for zeolite milled with ball to powder ratio of 100. Structural characterisation was performed with XRD, SEM, BET and particle size analyzer. Mechanochemical activation improves cation exchange capacity of natural zeolite.DOI: http://dx.doi.org/10.5564/mjc.v12i0.181 Mongolian Journal of Chemistry Vol.12 2011: 98-101

COMPARATIVE STUDY OF MORPHOLOGY OF VARIOUS FLY ASHES AND POND ASHES FROM DIFFERENT THERMAL POWER STATIONS IN MONGOLIA

In Mongolia coal fired thermal power stations produce over 90% of the country’s electricity. Three thermal power stations located in Ulaanbaatar city produce more than 80% of all electricity produced in Mongolia. The annual output of fly ash and bottom ash from these thermal power stations is about 600,000 tons. The thermal power plants in Ulaanbaatar city use coal from Baganuur and Shivee-Ovoo deposits. This research was conducted to compare morphologies of various fly ashes and pond ashes from TPS in Mongolia. Fly ashes from TPS4 and pond ashes from TPS3 and TPS4 of Ulaanbaatar city were characterized by x-ray fluorescence (XRF), transmission electron microscopy (TEM), laser particle size distribution analyzer, specific surface area measurement (BET), and scanning electron microscopy (SEM). The chemical compositions of the fly ashes and pond ashes indicate that they are class C ashes. Specific surface areas of the fly ashes and pond ashes varied from 1.04 to 25.2 m2/g. Radiation measurements that were performed by γ-spectroscopy indicate that the radium equivalent changed from 292 to 761 Bq/kg in the various ashes. 

Characterization of Alkali Activated Materials Prepared from Continuous Attrition and Ball Milled Fly Ashes

Mechanical activation is known to greatly influence the reactivity of fly ashes. In this paper, we report a comparative study of the properties of alkali-activated geopolymer materials prepared using both ball-milled and attrition-milled fly ashes. Ball milling was carried out for 30 min and 60 min while attrition milling was carried out continuously in a high-speed attritor. The surface area of the raw fly ash decreased from 4017 cm2/g to 3999 cm2/g and 3912 cm2/g after ball milling for 30 min and 60 min, respectively. By contrast, the surface area of the continuously attrition-milled fly ash increased to 5545 cm2/g. Fly ash processed by continuous attrition milling showed a 50% particle size reduction to 25–38 μm, whereas fly ash ball-milled for 30 and 60 min was reduced in size by 33.4 and 42.9%. The milled fly ash samples were activated with 8 M NaOH solution and cured at 40 °C for 68 h. After curing, the samples were maintained at room temperature, and their 7-, 14-, and 28-day compressive strengths were measured. The compressive strength of the attrition-milled 28-day geopolymer paste was 24.6 MPa; that of the geopolymers ball-milled for 30 and 60 min was 23.37 MPa and 17.58 MPa, respectively; and that of the unmilled control geopolymer fly-ash-based paste was 17 MPa. The improvement in the mechanical properties is attributed to the increased gel formation resulting from the increased surface area (decreased particle size) in the fly ash glass starting material