Research and application of surface paste disposal for clay-sized tailings in tropical rainy climate

Surface paste disposal (SPD) of waste tailings is a new disposal method, while it is not suitable for the projects in rainy regions. Traditional tailings disposal means (a setting pond or a dam) are getting obsolete gradually due to high risk and bad influence on environment. Mining project in tropical rainy areas will face great challenge in disposing waste tailings when there is no mine-out area for backfill (new mining project or surface mining). This paper discusses the application of SPD of an iron mine project in Indonesia and demonstrates its feasibility by laboratory unconfined compression strength test and rainfall erosion test. Two kinds of tailings collected from project are used in these experiments, one of them is relatively ordinary and the other is quite fine (clay-sized particles reaches 42%), which also contains many clay minerals. Binders are added to tailings slurry to form paste tailings. Results show that the paste strength increases with the clay mineral content in a certain range and then gets fluctuating under the max value. Authors conduct preliminary discussion on this phenomenon and it is worthy to be studied deeply. Direct share test and scale effect test provide evaluation of the in situ mechanical strength on which the field paste tailings samples are based. Simulation of rainfall erosion indicates that the paste tailings curing for > 6 h can withstand the location extreme rainfall without obvious damage.