Abstract

Phosphate rock is a finite resource whose extraction in sedimentary deposits generates substantial volumes of waste rock. This study develops a panel-scale 3D geological modeling workflow for operational material accounting in a multilayer sedimentary phosphate deposit. Phosphate layers were modeled using a hanging wall–footwall approach and evaluated against independent well data. Bone Phosphate of Lime (BPL) grades were estimated from borehole-layer composite assay values using nearest neighbor, inverse distance weighting, and ordinary kriging. Domain-wise external validation showed that ordinary kriging provided the most consistent agreement with withheld observations in most mineable layers. Each mineable layer was treated as an independent estimation domain, with one composite BPL value retained per drillhole and per mineable layer. The validated block models were regularized to the mine plan and aggregated into operational strips, enabling strip-scale material accounting and mineability filtering under operation-specific technical criteria. To limit disclosure of confidential operational quantities, panel-scale resource, recoverable resource, and residual ore results are presented in relative rather than absolute terms. The results show that most modeled phosphate-bearing material satisfies the applied criteria and is classified as recoverable, whereas residual phosphate-bearing material excluded by the operational criteria remains concentrated in a limited subset of layers. The terms ‘resource,’ ‘recoverable resource,’ and ‘residual ore’ are used throughout in an operational material-accounting sense only and are not intended in the sense of any international mineral reporting code. Strip-based stripping ratio maps further reveal spatial variability in waste-to-ore and waste-to-grade relationships. The resulting workflow provides a quantitative spatial basis for future scenario-based assessment of waste management and selective dumping alternatives in sedimentary phosphate mining.

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