## 5 Conclusions  
In this study, a computational fluid dynamics (CFD) study was performed employing the SST \(k\)-\(\omega\) turbulence and discrete phase (DPM) models to predict the wear characteristics of small two-stage mining pumps. It also outlined potential methods for developing a predictive model for long-term wear prediction taking into account factors such as material degradation, cumulative damage accumulation, and maintenance schedules. This would allow better planning and management of pump maintenance activities to minimize downtime and maximize equipment life. In addition, experimental verification studies have also been carried out. The following conclusions were drawn:  
1. Numerical simulations were performed to compare the wear on the impeller and guide-vane surfaces under several conditions. During the transportation of small particles, the first-stage guide vane always exhibited the greatest surface wear, at all flow rates. However, during the transportation of large particles, the second-stage guide vane exhibited the least surface wear in the low-flow and rated-flow conditions, whereas in the high-flow condition, the first-stage guide vane exhibited the least surface wear. Therefore, the surface strength of the first-stage guide vane should be prioritized in the design and construction of small, two-stage mining pumps.
2. In the pump wear experiment, which was performed at the pump's rated flow, severe wear was observed at the radial inlet of the pump, as well as the LE and TE of the first-stage impeller and second-stage impeller. Moreover, the surface wear on the second-stage impeller was more severe than that on the first-stage impeller. Hence, the flow-passing components must be strengthened at these locations.
3. A comparison was performed between numerically simulated and experimentally observed wear characteristics, which showed that the numerical and experimental results are consistent with each other. Therefore, the numerical method used in this work can accurately predict the surface wear of flow-passing components in mining pumps.
4. As mining pumps work in complex operating environments and comprise several flow-passing components, their particle motions are highly complex. When a mining pump is used to transport solid-liquid two-phase flows, the solid particles cause varying degrees of wear in the flow-passing components. However, by predicting the wear characteristics of mining pumps using an appropriate numerical method and erosive wear model, pump designers and manufacturers may use the insights gained from these predictions to selectively strengthen the parts of the flow-passing components that are expected to experience significant wear. Thus, the methods proposed in this study are expected to function as a suitable numerical method and wear model that is well-suited for this purpose.  
**Author Contributions:** Conceptualization, S.H.; methodology, S.H. and X.H.; software, S.H.; validation, S.H.; formal analysis, S.H.; investigation, S.H.; resources, S.H. and X.H.; data curation, S.H.; Writing--Original draft preparation, S.H.; Writing--Review and editing, S.H. and X.H.; visualization, S.H.; supervision, S.H.; project administration, S.H.; funding acquisition, X.H. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported by the National Key Research and Development Project of China, grant number 2016 YFC0304103.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data are contained within the article.  
**Conflicts of Interest:** The authors declared no conflicts of interest.