The preparation of coating material of welding electrode from marine placer via carbothermic reduction with added aluminum (AI) was systematically investigated. The reduction behavior and phase transformation of the marine placer-coal mixture with Al were checked by TG/DTG/DSG, XRD and SEM/EDS analysis. The additional Al can obviously increase the metallization rate of the mixtures, and the corresponding products easily exceeded the technical requirement. A reaction mechanism for the carbothermic reduction of the marine placer-coal mixture with Al was proposed. When the temperature was <960 degrees C, the main reduction reaction was solid-solid reduction (C-iron beating oxides) and a few aluminothermic reductions. These reactions have a slow reaction rate. When the temperature was higher than 960 degrees C, the gasification reaction just started, and the iron-bearing oxides were mostly reduced by CO. As the reduction progressed, the iron bearing oxides and the solid reductants, carbon and Al melt, increase in density because of the sintering mechanism and the compactness of the solid was improved. In addition, the gasification reaction rate increases with the enhancement of temperature, thereby accelerating the whole reduction. The heat released by the aluminothermic reduction increased the temperature in the neighboring area, thereby facilitating the gasification reaction and promoting the reduction rate to generate the metallic iron. (C) 2017 Elsevier B.V. All rights reserved.