# Investigation of Roller Press Surface and Stud Based on FEM Simulation
## 1 Introduction
Analyze the impact of rolls surface wear on output and power to predict output and adjust the working gap of the roller press. [PERSON] [9] built a laboratory-scale HPGR. To be able to install and inspect the whole rolls surface inside the scanning electron microscope (SEM) a special device has been designed. And through this special device to carry out microscopic analysis of the rolls surface. Then wear mechanism of the rolls surface during the operation of the roller press is analyzed. And analyzed the three conditions of grinding pressure, raw material particle size and raw material moisture on the surface wear of roller press. It can contribute to a better understanding of the complex wear system of HPGR and more accurate wear estimates for different minerals. [PERSON] summarizes basic principles of the equipment and of various options how to include an HPGR in the grinding circuit for the most efficient use. And case studies [10] demonstrate the application of HPGR's in different grinding circuit set-ups and for the comminution of different ore types. In order to study the impact of particle crushing on the working efficiency of the roller press, the coupled flow and crushing of particles can be predicted by discrete element method (DEM). And optimize the structural design of the roller press through the crushing model. And prediction of throughput through DEM simulation and the effect of roller press working gap and pressure between particles on the production process [11]. [PERSON] [12; 13] through coupled DEM-MBD-PRM simulations of HPGR. Validation and calibration of a pilot-scale roller press and making predictions of HPGR operation under skewing possible. [PERSON] developed a DEM-based particle fragmentation model [14] to simulate the dynamics of particles in HPGR. The crushing of cement particles under different conditions was compared to predict the performance of HPGR under various conditions. [PERSON] [15] used DEM to simulate the wear of the roller press to study the impact of rolls surface wear on the output and power of the roller press. The load and wear of the rolls surface material are analyzed by DEM. The pressure distribution between the rolls in HPGR is generally expected to vary significantly in the axial direction due to end effects at the ends of the rolls. Prediction of coupled flow and breakage of particles within HPGR using DEM [16]. [PERSON] [17] established a model of high pressure roller mill by establishing different mathematical methods and utilizing the crushing distribution function. A method for determining functional parameters was proposed, and the theoretical calculation values were compared with the actual materials processed by the roller press to verify the correctness of the model. At the same time, relevant research was conducted on the working gap of the roller press. The dependence of the production efficiency of the roller press on the feed top-size, porosity, moisture and specific pressure was investigated. Several researchers [18] investigate a model system describing the role of the gas flow in the feed powder during the rolling process through the analysis of gas pressure distributions. [PERSON] [19] proposed an off-line observation framework. From the working gap, throughput, and operating variables (specific force and rolls speed), the model calculates the slip, shear stress, and pressure profiles which subsequently allow estimating the power draw and the specific force. [PERSON] [20] presented a novel piston press test (PPT) procedure to predict the HPGR operational gap. A gap-calibrated methodology is proposed based on the PPT sample volume. As for the rolls surface of the roller press, there are currently three commonly used rolls surface: smooth rolls, composite rolls and studded rolls. The select of the surface of the roller press is an important factor in increasing the service life of the roller press.