The Main Reason for Mineral Loss in Gravity Dressing

Gravitational concentration (gravity dressing) is the oldest of all forms of mineral processing used by humanity more than 25 centuries. This method was the most widely applied procedure of mineral enrichment till the end of second millennium. Physically mineral concentration is based on separation of geological rocks and minerals of different specific density by their relative movement in response to the gravity and some additional forces. However, such an enrichment a priori cannot provide a high output of desired minerals. The authors have aimed to attract an attention to significant losses of native gold and diamonds by traditional scheme of their gravitational concentration. Detailed consideration of density and form of native gold and diamonds indicates that fragmental (placer generating) minerals with the different values of average density may have close and identical sizes (on two axes) in heavy concentrates (schlich) and middlings. These dense parameters essentially influence to conditions of these minerals accumulation in natural conditions and degree of their extraction in technological processes of gravitational concentration. The materials presented in the paper span the analyzed mineralogical data from about twenty economic deposits located in various regions of the world (mainly the authors' personal results).