Dimensionamento de sistema de paste backfill: estudo de caso para uma mina subterrânea

Abstract

Paste backfill is a technique used in underground mining, where the tailings generated during ore processing are thickened to achieve paste-like consistency and then combined with a binder, typically cement. This material is transported to the underground stopes left by mining. Paste backfill serves several purposes, including the stabilization of underground mines, enabling the continuity of ore extraction, reducing tailings disposal on the surface, and minimizing the environmental impact of mining operations. Cement represents most of the costs involved in the backfill operation. Therefore, optimizing the paste specification is crucial to ensure that both the hydraulic and operational requirements of the mine are met, avoiding excessive cement consumption. This study aims to design a paste backfill system for a copper and gold mine transitioning from open-pit to underground mining. The resulting paste must meet the requirements for gravitational transport and achieve the necessary compressive strength criteria for filling the underground stopes. For the design, the paste was characterized in terms of its rheology, particle size distribution, and solid density. The cement percentage was determined based on the results of unconfined compression tests. A hydraulic model was developed, considering the system’s route, allowing the definition of the piping to be used and the optimized paste mix recipe.