Tạp chí Khoa học Kỹ thuật Mỏ - Địa chất

Research on the material composition of Ta-Phoi copper tailings and accompanying gold recovery orientation

2025-12-09T03:55:58+07:00

Everyyear,theTa-Phoicopperprocessingplantdisposesofabout970,000tonsoftailingswithanAugradecontentofapproximately0.1g/t.Intheoperatingtechnology,therehasnotyetbeenconsiderationforrecoveringusefulcomponentssuchasgold.Theamountofgoldlostannuallyintailingproductsisabout116.4kgAu.Asof2023,theamountofsludgeis3,531,682tons(equivalentto353.2kgAu).Theamountoftailingsaftertheprocessingissignificantlylarge,andtheAugradecontentinthetailingsisstillrelativelyhigh.Theamountoftailingsiscurrentlystoredatthetailingpond,ifnottreated,itwillwasteresourcesandcausearisktoenvironmentalpollution.ThearticlepresentstheresultsofresearchonthechemicalcompositionandcharacteristicsoftailingscontainingAuusingsieveanalysis,X-raydiffraction(XRD)analysis,inductivelycoupledplasmamassspectrometry/atomicemissionspectrometry(ICP-MS/AES)analysisandscanningelectronmicroscopywithenergydispersiveX-rayspectroscopy(SEM-EDS).TheresearchresultsprovideatechnologicaldirectionforAurecoveryusinggravityseparationmethods(spiral,shakingtable,andjig),centrifugalgravityseparation(Knelson,Falcon),andflotationmethod.ToincreasetheprocessedAucontent,theproductsshouldbethoroughlytreatedthroughtheleachingmethodusingsuitablechemicallixiviantstomeetthesafetyandenvironmentalprotectionrequirements,followingregulationsinVietnam.Thisisthefirsttimethattherearecomprehensivestudiesonthematerialcompositionofcoppertailingsforthepurposeofrecoveringthetailingsbearinggold.Thestudyopensupprospectsfortherecoveryofusefulmineralsinthetailingsofcopperbeneficiationplants,inparticularandthetailingsofthemineralprocessingplantsingenera

Enhancing wind turbine efficiency: characteristics of cylindrical-conical hydrodynamic fluid friction bearings

2025-12-22T10:09:33+07:00

One of the main causes of energy loss in wind turbine systems is friction between moving parts, particularly the multiplier, braking system and shaft supports. Conical- cylindrical plain bearings with a friction-reducing design help reduce energy consumption during turbine operation. Conical-cylindrical hydrodynamic bearings play a crucial role in wind turbines, reducing friction and energy losses, and effectively transmitting mechanical energy from wind blades to generators, thereby enhancing the overall efficiency of wind turbines. The research has developed a mathematical model to analyze the load-bearing capacity and energy losses due to friction. Using the calculation program developed on the basis of mathematical modeling and algorithms, a set of calculation experiments was performed to calculate the load-carrying capacity, moment and frictional power loss in a combined angular contact bearing depending on the shaft speed, lubricating oil supply pressure, radial clearance and relative eccentricity. This study investigates the characteristics of cylindrical-conical hydrodynamic fluid friction bearings and their critical role in optimizing the performance of wind turbines. By analyzing the load-carrying capacity, friction torque, and power losses under varying geometric and kinematic conditions, the research highlights how these bearings contribute to the overall efficiency and reliability of wind energy systems. The findings provide valuable insights into the design and operation of hydrodynamic bearings in highly loaded wind turbine applications, supporting the development of more sustainable and efficient wind energy technologies

Identification of well breathing phenomena in HPHT wells and technical solutions to enhance drilling efficiency in the Nam Con Son Basin

2025-12-22T10:14:56+07:00

The Nam Con Son Basin is considered the most technically challenging area for drilling operations in Vietnam and ranks among the most complex globally. Its central region, dominated by high-temperature, high-pressure (HPHT) conditions, accounts for approximately 70÷80% of the basin’s total gas production. This area is geologically characterized by heterogeneous stratigraphy, abnormally high formation pressures and temperatures, and a narrow margin between pore pressure and fracture gradient-commonly referred to as the “narrow pressure window.” Under such conditions, even minor variations in mud weight can lead to wellbore instability or formation damage. One of the most critical drilling challenges in this environment is wellbore breathing - a transient loss and subsequent return of drilling fluid-typically observed in formations within the Miocene formation. These formations exhibit low porosity, low permeability, and elastic rock behavior, which can result in misleading well control indications, non-productive time, and potential well control incidents if not identified and managed appropriately. This study presents a novel diagnostic framework for recognizing and managing wellbore breathing in HPHT wells of the Nam Con Son Basin. It systematically evaluates operational data from recent wells using four key indicators: (i) loss circulation behavior during circulation, (ii) mud-volume return after pump stoppage, (iii) downhole pressure variations, and (iv) changes in total gas and gas-peak composition in returns. The combined indicators reliably identified early breathing onset and severity, distinguishing it from other circulation anomalies. Field validation confirmed the method’s robustness across multiple well sections. Applying the proposed framework, along with mud-weight optimization, real-time monitoring, and wellbore strengthening, reduced non-productive time and minimized well-control false alarms. These outcomes demonstrate significant practical value for improving safety, integrity, and efficiency in complex HPHT drilling environments worldwide HPHT.

U-Pb age and Lu-Hf isotopic characteristics of S-type granite in the Bac Tra My area, Quang Nam and their regional tectonic implications

2025-12-22T10:26:20+07:00

The Kon Tum Massif (KTM) in central Vietnam is a key part of the Indochina Block, where Early Paleozoic magmatism is attributed to subduction and subsequent collision between the KTM and the Truong Son Belt (TSB). However, the timing, source and tectonic setting of S-type granites of the Chu Lai Complex, especially near Bac Tra My area, remain unclear. This study presents new zircon U-Pb geochronological and Lu-Hf isotopic data from two granitic gneiss samples of the Chu Lai Complex in the Tra My area to better constrain their formation age, magma source and tectonic implications. Zircon U-Pb dating by MC-LA-ICP-MS yields concordant crystallization ages of 438.7 ± 2.9 Ma and 441.7 ± 1.9 Ma, corresponding to the Late Ordovician. Inherited zircon core ages (1.45÷2.62 Ga) indicate that the magma was derived from partial melting of Paleoproterozoic-Mesoproterozoic metasedimentary sources. Zircon εHf(t) values from -11.1to -2.4 support derivation from ancient crustal materials. Petrographic features, including muscovite, garnet and tourmaline, further indicate an S-type peraluminous affinity. Integrating these data with previous results suggests that Chu Lai magmatism (455÷426 Ma) represents a syn- to post-collisional episode following the closure of the Proto-Tethys Ocean and the collision between the KTM and the TSB. This event, likely during the Middle to Late Ordovician, marks the termination of subduction beneath the KTM and the onset of a widespread post-collisional thermal regime across the Indochina Block. The study refines the timing of Early Paleozoic orogenesis in central Vietnam, provides new isotopic evidence for the crustal evolution of the KTM and contributes to a better understanding of the tectonic assembly of the eastern Indochina Block during the Paleozoic

Surface settlement caused by twin stacked tunnels excavated beneath buildings

2025-12-22T10:39:12+07:00

Underground construction plays a crucial role in the development of megacities by addressing key urban transportation challenges such as traffic congestion and limited parking. One of the most effective solutions to the growing global demand for efficient transportation systems is the development of underground public transit networks, particularly subways. To support the rapid expansion of such infrastructure, this study investigates the impact of twin stacked tunnel excavation on ground surface settlement through three-dimensional (3D) numerical modeling. The models were developed under various excavation scenarios, considering factors such as groundwater level, soil conditions, face pressure, and grouting pressure applied by the Tunnel Boring Machine (TBM). The Ben Thanh - Suoi Tien metro line in Ho Chi Minh City was used as a reference case study, with settlement data from the tunnel site employed to validate the numerical model. The results show that all investigated parameters significantly influence ground settlement above twin stacked tunnels. In particular, variations in water level, soil conditions, face pressure, and grouting pressure have significantly influenced the surface settlement when the upper tunnel is excavated. This indicates their critical role in ensuring ground stability and must be carefully considered during the construction process