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A case study on the recovery of unevenly embedded particle size in high-carbon chalcopyrite using an alkyne-based thioester collector: Flotation processing and adsorption mechanism

Qi Yuechao, Luo Yunbo, Qiu Xianyang, Wei Dezhou, Zhang Faming, Wang Chenghang

Physicochemical Problems of Mineral Processing

2024

Vol. 60, iss. 2

art. no. 188154

Abstract: The difference in chalcopyrite's primary ore-hosting rocks (dolomite and carbonaceous slate) in the Democratic Republic of the Congo results in an extremely uneven grain size distribution. Additionally, the presence of 2.21% organic carbon in the gangue impacts flotation efficiency. To address these challenges, ore properties were analyzed using the Mineral Liberation Analyzer (MLA), X-Ray Diffractometer (XRD), and microscopy. Flotation process was modified to incorporate a "middlings regrinding" processing, utilizing PDEC (an alkyne-based thioester collector, prop-2-yn-1-yl diethylcarbamodithioate) as the collector for experimental studies. Density Functional Theory (DFT) calculations elucidated the interaction mechanism of PDEC on chalcopyrite's surface. The MLA analysis indicates that chalcopyrite is mainly found in medium to fine grains, with the presence of fine-grained copper minerals smaller than 0.04mm accounting for 16.29% of the sample. This implies that these minerals require fine grinding for effective separation. Despite interference from organic carbon, PDEC demonstrates remarkable selectivity and efficiency in chalcopyrite flotation. By employing the "middlings regrinding" flotation method, a concentrate with a Cu content of 26.79% and a recovery of 87.88% was achieved, representing an increase of 0.17% in Cu grade and 4.09% in recovery rate compared to the conventional flotation process. DFT analysis demonstrates that the S 3p orbitals in carbon-sulfur double bond of PDEC and the C 2p orbitals in its acetylene group significantly affect its collection efficiency, engaging in hybridization with the Fe 3d orbitals on the surface of chalcopyrite, thereby facilitating a robust bonding interaction.

Damage deterioration mechanism and damage constitutive modelling of red sandstone under cyclic thermal-cooling treatments

Cao Ri-hong, Fang Lei, Qiu Xianyang, Lin Hang, Li Xilong, Li Wenxin

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 4

art. no. e188, 2022

In the process of exploiting mineral and geothermal energy resources, the influence of the cyclic heat effect on the mechanical properties of the surrounding rock becomes increasingly prominent. To further study the damage deterioration mechanism, deformation and failure characteristics of cyclic heating–cooling (H–C) of the rock, cyclic H–C treatment tests and uniaxial compression tests were conducted, acoustic emission (AE) events were monitored, and the mesoscale characteristics of the fracture surface were imaged and analysed. The results show that the number of H–C cycles played an important role in the evolutions of the strength, cumulative damage variables and deformation modulus of the red sandstone. The peak strength of the specimens decreased with the increase in the number of H–C cycles, and the damage variables increased with the number of H–C cycles. The cyclic H–C treatments promoted the development of microcracks and the growth of the stress–strain curve crack closure stage. Both the crack closure stress and crack closure strain increased with the number of H–C cycles. Furthermore, both the number of transgranular microcracks and the microcrack spacing increased during cyclic H–C treatment, which also led to the failure mode of the specimens gradually changing from shear failure to splitting failure. In addition, based on the principle of strain equivalence, a damage constitutive model under the coupling action of cyclic H–C treatment and loading was deduced. The crack closure deformation of specimens treated with different numbers of H–C cycles was well reflected by the proposed model, and the prediction of other mechanical parameters, such as the peak stress, peak strain and tangent modulus of the theoretical curves, was also verified by test data.