Coal kaolin, as an important industrial raw material, is used in the production of artificial Molochite sand whose application is of great potential for high-end castings due to its ability to significantly reduce the cost of mineral sand and improve the quality of sand mold. In this paper, the key factors in the calcination of coal kaolin were systematically analyzed with a three-factor, four-level orthogonal test, and the test factors were rotary kiln temperature, particle size, and residence time of materials. The optimal calcination parameters determined by range analysis were a temperature of 1500°C coal kaolin, a particle size of 4-8 mm, and residence time of 1.5 hours. Analysis of variance showed that temperature had the most significant effect on the calcination effect, followed by coal kaolin particle size. In contrast, the effect of residence time of materials was relatively small. The test showed that the basic needs of producing 60% mullite, the standard percentage, could be met at 1100°C. In order to verify the required coal feed and temperature distribution in the actual rotary kiln, a rotary kiln model was established by numerical simulation technology to simulate the actual conditions. The results showed that the rotary kiln has an average temperature of 1159°C and a maximum temperature of 1428°C when the coal consumption is 1.5 kg/s, which meets the temperature requirements for 60% mullite.