Defeng Shi

Prof. Defeng Shi


Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
14 September 2024 in Ore Geology Reviews
Verified
Journal Article
Open access
DSDefeng Shi
Defeng Shi
SFShini Fan
Shini Fan
GLGuixian Li
Guixian Li
YZYun Zhu
Yun Zhu
QYQing Yan
Qing Yan
MFMohamed Faisal
Mohamed Faisal

22 September 2021 in Materials
Verified
Journal Article
Open access
PDF file
Jianqun WangJianqun Wang
Jianqun Wang
LLLong Li
Long Li
LZLongwei Zhang
Longwei Zhang
BLBei Li
Bei Li
RDRenjian DENG
Renjian DENG
DSDefeng Shi
Defeng Shi
In this research, the sustainable applications for utilizing antimony tailing coarse aggregate (ATCA) in concrete is investigated. Comprehensive verifications were performed by a series of experiments on the characteristic of ATCA and the toxicity risks of concrete. Firstly, a real case study of utilization of ATCA as a complete substitute for natural coarse aggregate (NCA) in high strength concrete was conducted. Then, chemical composition of ATCA was tested. It is demonstrated that the essential mineral is SiO2 and the lithology of ATCA is quartzite. The mechanical properties, coarse quality of ATCA, and NCA were studied and compared. The compressive strength, splitting tensile strength, and compressive elastic modulus of ATWR are 221.51 MPa, 5.93 MPa, and 3.33 × 104 MPa, which are 1.31, 2.22, 1.40 times of that of NR, respectively. All of the quality control indices of ATCA meet the requirements of the current industry standards of China. Finally, the toxicity risks of ATCA concrete were investigated. It is illustrated that the leaching of main heavy metals including Sb, As, Hg, Pb, Cd, and Zn in the ATCA concrete under different pH conditions are below the regulatory limits. The utilization of antimony tailing has significant environmental and economic benefits.

2 October 2026 in Minerals
Verified
Journal Article
Open access
PDF file
RDRuolan Deng
Ruolan Deng
DSDefeng Shi
Defeng Shi
RTRuichang Tan
Ruichang Tan
LTLong Tang
Long Tang
Pyrite trace-element chemistry is widely used to infer ore-forming processes, yet its ability to discriminate ore-fluid, deposit-genetic, and commodity classes has not been quantified within a unified validation framework. We compiled 12,582 LA-ICP-MS pyrite analyses, of which 12,495 from 188 deposits worldwide remained after cleaning, and compared five supervised classifiers (TabPFN, XGBoost, Random Forest, support vector machine, and artificial neural network) across three classification tasks. To limit leakage arising from analyses from the same deposit, all models were evaluated using 100 deposit-grouped train–test splits with deposit-grouped inner cross-validation, and model differences were tested with paired comparisons across identical splits. All three tasks used pyrite trace-element features only (14 elements for commodity; 21 and 18 element and element-ratio features for deposit genesis and ore fluid); no temperature, sulfur-isotope, or fluid-type descriptor entered any classifier. Across the splits, mean balanced accuracy ranged from 0.58 to 0.69 for commodity classification, from 0.51 to 0.58 for four-class deposit-genesis classification (magmatic-hydrothermal, VMS, sediment-hosted Pb–Zn, orogenic Au), and from 0.77 to 0.78 for ore-fluid classification (magmatic, metamorphic, sedimentary). TabPFN achieved the highest balanced accuracy for commodity (0.686 ± 0.092; +0.07 over the next model, Holm-adjusted p < 10−12) and deposit-genesis classification (0.580; +0.04 to +0.07, p < 10−7), whereas the five algorithms were statistically equivalent for ore-fluid classification. Deposit-level majority-vote balanced accuracy, which counts test deposits rather than analyses, gave the same ranking (0.81, 0.69, and 0.83 for TabPFN in the three tasks). Sensitivity analyses of below-detection-limit imputation, outlier screening, and feature transformation changed mean balanced accuracy by ≤0.04 and did not reverse the model ranking within a given preprocessing pipeline. SHAP attributions were led by Au, Sb, Se, and As for commodity; by Tl, Se, Ni, As, and Co/Ni for deposit genesis; and by Sn, As, Mo, and Co/Ni for ore fluid, with the same leading features recovered by all audited algorithms in the latter two tasks (cross-model Kendall’s W = 0.81 and 0.75). Across 20 repeated grouped splits, adding the ore-fluid label to the trace elements increased commodity balanced accuracy by 0.18 ± 0.09, whereas the element-unique gain over the fluid label alone was near zero (0.02 ± 0.11). These results support pyrite trace elements as useful screening proxies for ore-system characteristics, while their transferability is limited by class imbalance, label consolidation, heterogeneous literature data, and the unequal representation of deposits across classes and data sources. Model outputs should therefore be interpreted alongside independent geological evidence.