Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Shear failure and mechanical behaviors of granite with discontinuous joints under dynamic disturbance: laboratory tests and numerical simulation

Gong Hangli, Wang Gang, Luo Yi, Liu Tingting, Li Xinping, Liu Xiqi

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 3

art. no. e171, 2023

To investigate the fracture mechanical behavior and failure mechanism of jointed rock mass under compression and shear load. Conventional shear tests and shear tests under normal disturbances were conducted using an electro-hydraulic servo-motor loading system. Meanwhile, the discrete-element program particle flow code was adopted to establish a numerical shear model, and to discuss the microscopic deterioration characteristics and energy dissipation mechanism during shear fracture of rocks with discontinuous joints under joint action of normal static loads and dynamic disturbance. Compared with the conventional shear tests, shear test results under normal disturbances show the following specificities in terms of their macroscopic and microscopic mechanical properties as well as energy evolution: (1) frequent dynamic disturbances accelerate the non-steady fracture process of jointed rock samples and promote occurrence of the weakening effect of shear fracture. (2) The step-like abrupt increase in micro-cracks becomes more obvious before reaching the peak shear stress. (3) The energy-storage capacity and failure resistance of the rocks are weakened. The research results are of great significance for further understanding the dynamic catastrophe effect of deep rock mass.

Selective extraction of vanadium from vanadium-titanium magnetite concentrates by non-salt roasting of pellets-H2SO4 leaching process

Luo Yi, Che Xiaokui, Wang Haixia, Zheng Qi, Wang Lei

Physicochemical Problems of Mineral Processing

2021

Vol. 57, iss. 4

36--47

In this work, a novel process of pellet non-salt roasting and H2SO4 leaching was proposed for the selective extraction of vanadium from vanadium–titanium magnetite concentrate. Vanadium can be leached but the iron impurity was maintained in the pellets. Moreover, the leached pellets can meet the quality requirements of the iron-making process after secondary roasting, realizing comprehensive utilization. The maximal vanadium leaching efficiency was up to 60.3%, whereas 0.17% of the iron impurity was leached. The optimum conditions of pellet roasting and leaching were obtained by single-factor experiments. The X-ray diffraction and scanning electron microscopy–energy disperse X-ray spectrometry analyses showed that the vanadium iron spinel can be oxidized and decomposed into Fe2O3 and vanadate during the roasting process. Given that dilute sulfuric acid can react with vanadate without reacting with Fe2O3 in the leaching process, selective vanadium extraction was realized. This work provides new insights into the industrial production of vanadium–titanium magnetite concentrate involving the direct extraction of vanadium.

Impact of climate warming on the surface water temperature of plateau lake

Peng Zongqi, Yang Jiaying, Luo Yi, Yang Kun, Shang Chunxue

Acta Geophysica

2021

Vol. 69, no. 3

895--907

Lake surface water temperature (LSWT) is a vital indicator in evaluating the ecological environment and has a direct or indirect impact on regulating physical, chemical, and ecological processes of lakes. Changes in LSWT have a huge impact on the water quality, ecosystem function, and biome composition of the entire lake. In this study, we selected Dianchi Lake as the research area, the monthly average LSWT data collected at the monitoring station from 1998 to 2009 were used as the calibration dataset. The error analysis dataset is the average annual temperatures of the Dianchi Lake extracted from MODIS remote sensing images from 2001 to 2017. The daily average LSWT of Dianchi Lake was estimated by the air–water model and the historical changes from 1980 to 2017 of the LSWT were reproduced. The research draws a conclusion that the LSWT of Dianchi Lake has been greatly afected by air temperature over the past 37 years. LSWT and the annual average air temperature correlation coefcient were R>0.9. Both the air temperature and LSWT assumed an increasing tendency. The annual average LSWT increased with the rate of 0.36 °C/decade, and the annual average warming rate of the air temperature was 0.47 °C/decade. The monthly average LSWT and air temperature showed a signifcant correlation at a confdence interval of α=0.001. The LSWT of Dianchi Lake increased signifcantly in February, March, and December. The periodicity of the seasonal mean air temperature change was consistent with that of the LSWT in Dianchi Lake. The relative lag of the thermal response of the LSWT to climate warming was also observed. This study flls in the gaps in the long-term sequence data on the LSWT of Dianchi Lake and reveals the efect of climate warming on the LSWT of low-latitude plateau lakes.