Cement stabilisation as an aid to the disposal of coal preparation plant tailings

Abstract

ABSTRACT This paper presents the results of a programme of laboratory-based research into factors which may influence the geotechnical properties of dewatered coal preparation plant tailings which were mixed with small quantities of Ordinary Portland cement. Oedometer and consolidated undrained triaxial tests demonstrated that the characteristics of the tailings were significantly altered by the addition of cement. The consolidation of the cemented tailings caused the gradual degradation of the cemented structure, resulting in a reduction in strength of the material. After total degradation of the cemented structure, consolidation to higher stresses resulted in the cemented tailings gaining strength in a similar manner to that of uncemented tailings. This behaviour indicates that cement addition cannot be relied upon to induce tip stability through a permanent increase in shear strength. In current practice, cement is only added to dewatered tailings in sufficient quantities to improve their handling and placement characteristics and is not exploited for tip stability.