Gravity separation with Nelson concentrator assisted by flotation is an important production process pattern adopted in precious metals concentrators.The convey belt frequently breaks when a mine uses Nelson concentrator in actual production,causing pulp overflows and precious metal loss,probably leading to economic loss and environmental accidents.By studying the technical characteristics of Nelson concentrator and finding out the reasons of frequent conveyor belt break,belt break protection technology for Nelson concentrator is developed.The addition of frequency convertor to the starting circuit of Nelson concentrator converts direct start of electric motors to soft start,and alleviates the impact of frequent start to conveyor belt;based on the current anomaly characteristics after the belt break,current protection is programmed.Automated control system is used to monitor Nelson concentrator so that the belt break can be found in time.The application of the technology can reduce precious metal loss that is worth about 0.2 million yuan annually.