Open-Pit Mining Process for Low-Grade Copper-Molybdenum Ore

As medium- and high-grade copper-molybdenum deposits become increasingly scarce, low-grade resources have become the primary targets for extraction. As a professional mining service provider, Xinhai delivers comprehensive open-pit mining solutions by integrating core technologies such as geological modeling, mine planning optimization, and intelligent mining equipment. This article outlines the methodologies used in open-pit mining of low-grade copper-molybdenum ore.

01Geological Modeling and Resource Assessment

Xinhai utilizes 3D geological modeling software to construct detailed geological and economic models. On platforms such as Datamine, the Lerchs–Grossmann (L-G) algorithm is employed to convert parameters—such as the spatial distribution of ore bodies and ore selectivity—into economic indicators, enabling dynamic optimization of the mine plan.

The equivalent grade method is applied to assess the value of copper-molybdenum co-occurring ores. The economically minable resource boundaries are defined using parameters such as metal prices and ore recovery rates (copper ≥ 85%, molybdenum ≥ 75%). For instance, at a copper-molybdenum project in Tibet, the cut-off grade was lowered by 0.015%, resulting in 23 million additional tons of economically recoverable ore.

02Pit Limit and Mining Boundary Optimization

The product cost comparison method, combined with a dual-index verification system based on strip ratio analysis, ensures that stripping costs remain below the economic threshold of ore value. Using the Whittle four-dimensional optimization algorithm, the economic viability of different slope angles (45°–55°) and bench heights (12–15 m) is simulated within the geological model to identify the optimal mine design.

03Semi-Continuous Mining Process for Low-Grade Copper-Molybdenum Ore

A mobile in-pit crushing station is deployed within the mining area. By monitoring the advance rate of the working face in real time, the station’s layout spacing is dynamically adjusted.

At one copper-molybdenum project, the average truck haulage distance was reduced to 1.2 km by optimizing the relocation schedule, resulting in a 28% decrease in transportation energy consumption compared to a conventional fixed crushing system.

To tackle challenges in the ore–waste contact zones, a selective mining and separate haulage strategy is adopted. A trench is first developed along the ore body, and two sets of mining equipment are assigned separately for ore and waste handling. This strategy maintains the ore loss and dilution rates within 3%.

04Construction of a Dynamic Grade Management System

We have developed an intelligent boundary grade control system and established a dynamic economic model based on parameters such as metal prices and production costs.

In one molybdenum mine project, the maximum profit per ton method was applied. When the molybdenum price reached 170,000 yuan/ton, the cut-off grade was raised from 0.05% to 0.078%, increasing the concentrate profit margin by 14 percentage points.

For debt-free mines with sufficient capital, the maximum total profit method is adopted. By lowering the cut-off grade by 0.004 percentage points, the economically recoverable ore increased by 12.05 million tons, and the mine’s service life was extended by 3.6 years.

05Copper-Molybdenum Mining Equipment and Mining Strategy

In terms of equipment selection, we recommend using a 12 m³ electric shovel paired with a 90-ton dump truck to form a standard mining and hauling unit, with each unit capable of processing 8 million tons of ore annually.

A zoning and phased mining strategy is applied to complex ore bodies. High-grade ore near the surface is mined first, while a progressive stripping scheme is adopted for low-grade mixed zones. By implementing this strategy, a mine in Central Asia successfully delayed the stripping peak during the first three years, saving 230 million yuan in upfront investment.

06Mineral Processing Technology for Low-Grade Copper-Molybdenum Ore

For copper-molybdenum ore beneficiation processing, we have developed a “bulk flotation followed by copper-molybdenum separation” process. After the copper-molybdenum bulk concentrate undergoes thickening and impurity removal, nitrogen inflation flotation is employed to selectively depress copper sulfide minerals, stabilizing the molybdenum concentrate grade above 52%.

When this method was applied to a low-grade copper-molybdenum deposit, recoverable resources increased by 23%, and the cut-off grade was lowered by 0.012 percentage points. In addition, the introduction of microwave-assisted heating in the pretreatment stage improved the collector’s decomposition efficiency by 40% and reduced reagent costs by 18%.

Conclusion

As a professional mining service provider, Xinhai Mining offers full-process EPCM+O services in mining and mineral processing. Our projects have been implemented in over 100 countries and regions worldwide, delivering tangible economic benefits to many low-grade copper-molybdenum operations. With the continued advancement of automation and intelligent technologies, Xinhai is committed to providing even more efficient and intelligent mining solutions.