SRK used numerical modelling on a 3D MS Excel platform to solve challenges involving the deposit of a heavy minerals thickened paste on natural valley slopes, to determine maximum coverage and hang-up, and evaluate the potential increase or decrease in design target dry densities of the slimes.
During heavy minerals extraction processes, ultra fine slimes residue is produced as a by-product that presents its own disposal challenges. These challenges are exacerbated along the south eastern coast of Africa due to steep terrain and high seasonal rainfall, therefore understanding the interdependent relationships between yield/shear stresses, deposition rates, evaporation requirements, placement stability and thickness of deposit layers on steep terrain is imperative to accurately size and design of the storage facility. Steep terrain within the storage facilities basin confines potentially could lower the average target of dry densities, which in turn directly affects the facility’s storage requirements and increases the time before rehabilitation or closure begins.
The numerical models provided SRK with graphics and tables summarising the number of deposition cycles per area, and the terrain’s effect on the average target dry density and volume of slimes retained on the slopes per deposition cycle. SRK then ascertained the most cost effective method of slimes deposit – by open ending, spigot or spray bar.
This numerical modelling method has also been adapted to size the slimes/sand rehabilitation mixture in co-disposal production plants and determine the developmental phases and capacity curves for both conventional and non-Newtonian thickened slimes/tailings.
