RESPEC Project

Cemex owns and operates two neighboring quarry properties (referred to as the White Mountain and Black Mountain Quarries) 14 miles northeast of Victorville, California. The Black Mountain Quarry began operations in the 1970s and currently supplies limestone to the cement plant, and the White Mountain Quarry is currently nonoperational. For the Black Mountain Quarry, RESPEC prepared a geologic block model using Gemcon-Surpac, an ultimate pit plan for the site, and a detailed 10-year mine plan.

RESPEC developed a detailed Gemcon block model by using existing Cemex exploration data, shallow-depth exploration holes, and the complete borehole sampling from the production drill holes. The surface topography was developed by using the most recent aerial photography updated with previously mined blocks. The modeled parameters included calcium oxide (CaO), magnesium oxide (MgO), and a calculated value for tricalcium silicate (C3S).

The ultimate pit plan was developed using the Gemcon block model to extend the pit depth consistent with the anticipated plant-feed specifications. Reserves and waste volumes were determined for the ultimate pit plan. Using the geologic block model, a 10-year mine plan was developed in annual increments to indicate the mined blocks and the expected annual head grade. The required plant-feed chemistry was used as the driving force for sequencing.

Overall, RESPEC’s planning and modeling aided Cemex in defining the mining sequence that maximized the quarry resource and met the cement factory feed requirements. The plan also defined the timing for relocating the primary crusher.