Stabilization of Boron-Containing Mineral Sludge With Various Solidification Agents

Abstract

Research and development on the stabilization of waste boron-containing mineral sludge with various mineral solidification agents such as fly ash, portland cement, their mixtures and calcinated lime is presented. The alkaline sludge (pH = 10) contains about 1% of soluble sodium borate. Addition of at least an equal amount of fly ash to the sludge, combined with appropriate mixing, can—after curing—reduce the leachability of boron by a factor 40-50. The physical integrity and hydraulic impermeability of the solidified mixture is required and important for safe landfilling. The same can be achieved by a much smaller addition (about 10% with respect to the sludge weight) of Portland cement, whereas addition of lime showed little stabilization effect on the sludge. Field experiments, carried out on the landfill using an ordinary sheepfoot roller for interdispersing layered sludge and fly ash, showed results close to those obtained in the laboratory. © 1997 ISWA