As Closure Approaches, Are You Preparing as Well as You Think You Are?

摘要

Characterization and assessment of waste rock has been the subject of considerable research, with the publication of a sizeable body of international guidance documents. Although detailed information exists for geochemical characterization of waste rock, there is limited detail on how to integrate these studies into engineering planning decisions around waste management options. A quantitative assessment is required to balance environmental management risks and operational cost constraints to facilitate planning decisions. Current industry practice, and the majority of guidance documentation, focuses solely on geochemical classification, without the subsequent connection to engineering planning. Hence, a disconnect exists between study outputs and operational requirements for placement method risk and cost assessment. A quantitative assessment methodology is required to determine risk/cost of various waste management approaches. This assessment must consider the complex interplay of factors influencing water quality at operations in long into closure. Only once these contributing factors to water quality are quantified can one appropriately understand, and quantify, risks associated with closure; in short, to properly plan for closure by achieving close alignment with mine planning and closure planning. O'Kane Consultants have developed an assessment process based around a quantitative risk tool to now allow the industry to accurately assess the risk/cost trade-off of waste management to water quality. Our assessment process captures multifaceted inputs, and employs an analytical model to provide quantitative analysis and outputs. Quantitative analysis and outputs allows risk to be assessed based on waste placement technique and facility engineering design; not solely material properties. Our approach allows assessment of progressive management measures against a deferral of all risks to final closure solutions, such as cover systems and/or mine effluent collection and treatment.