Gualcamayo Mine

Overview

Minas Argentinas S.A. (MASA) began exploration at Gualcamayo in 1994. Gualcamayo is located in the northwest of Jáchal department, approximately 270 km from the capital city of San Juan province and 110 km from the city of San José de Jáchal. The mine, which was constructed in 2007 and started production in 2009, has a maximum elevation of 2,500 masl, with the camp located at 1,600 masl. The mine, covering 7,128 hectares, has a disseminated gold deposit, primarily composed of oxidized ore, located in the area called Quebrada del Diablo, along with two adjacent areas called Amelia Inés and Magdalena.

Gualcamayo’s production currently focuses on the secondary recovery of leach piles. This means that ore extracted and crushed during mining operation is now being rewashed to extract the remaining gold. The final product, doré metal bars containing gold and silver, is exported for refining and marketing internationally.

Knight Piésold has conducted over 40 assignments for the project, including the following:

• From the initial stages, Knight Piésold was integral in maintaining the stability of geotechnical structures, conducting stability studies of slopes, waste dumps, and leach piles. Additionally, a detailed analysis of the pad’s liquefaction potential was conducted that allowed for the optimization of the mine’s lifespan.
• Detailed engineering was crucial for project development. Knight Piésold’s work included designing the original North Pad, the final connection for the ore conveyor belt, and the expansion of the North Valley. In addition, PLS solution recirculation and barren solution pumping systems were developed, maintaining the operational efficiency of the leaching process.
• Rigorous environmental monitoring plans were implemented to assess emissions and impacts. This monitoring, alongside a revegetation plan, was an integral part of environmental management to support area restoration and the minimization of long-term impacts. Additionally, Knight Piésold worked on updates to environmental impact reports.
• A detailed closure plan was developed for Gualcamayo. The engineering applied in this phase helped define optimal closure strategies, while reviews and updates on closure costs maintained alignment with economic expectations. These efforts were fundamental to supporting sustainable and efficient closure while optimizing available resources.

In 2025, MASA plans to advance to the feasibility stage of Gualcamayo’s Deep Carbonates Project (DCP), a gold deposit in sulfides situated beneath oxide gold mineralization in the underground mine, comprising the Rodalo, Santiago, and Feeder deposits. This project aims to extend the mine’s operational life and facilitate continued gold and silver extraction in the area. The estimated investment is approximately US$340 million, with projected operations for 17 years, supported by technical feasibility studies.

The Challenge

The challenges overcome at Gualcamayo highlight the complexity of maintaining environmental compliance, geotechnical stability, and engineering optimization at every stage of mine development. This involved improving engineering designs for a deposit nearing the end of its intended extraction cycle, with the purpose of extending its operational horizon.

Gualcamayo currently faces the challenge of extending its operational lifespan. To achieve this, MASA is evaluating the DCP and the extraction of the Salamanca mine—a proposed mine located a few kilometers away from Gualcamayo, in the La Rioja province—with the possibility of processing Salamanca’s ore at Gualcamayo’s facilities. Additionally, environmental management, especially the optimization of water resource use in an arid area, remains critical. Another key challenge is the need to modernize processes with technologies to improve efficiency and adapt the processing method to the DCP.

Our Approach

Knight Piésold served as a strategic partner for MASA, providing engineering solutions tailored to each project stage, from the beginning, during operations, and near the end of its operational life, supporting the projection of a promising new operational phase.

In the early stages, Knight Piésold worked on the stability of geotechnical structures, supporting operational efficiency and optimizing operational life. Through detailed studies of slopes, waste dumps, and leach piles, as well as the analysis of the pad’s liquefaction potential, Knight Piésold implemented improvements that supported the safety and sustainability of the deposit.

As Gualcamayo progressed, Knight Piésold provided detailed engineering that laid the groundwork in its development. Knight Piésold designed the original North Pad, the final connection of the ore conveyor belt, and the North Valley expansion, directly contributing to operational continuity. In addition, Knight Piésold optimized the PLS solution recirculation and barren solution pumping systems, supporting a more efficient leaching process.

Looking forward, Knight Piésold will continue to support MASA in overcoming Gualcamayo’s current challenges. Leveraging on experience, Knight Piésold aims for the mine to maintain its pivotal role in the region, operating efficiently and sustainably while optimizing resource use.

The Results

Knight Piésold played an instrumental role in accelerating environmental permit approvals for the Gualcamayo mine, implementing efficient strategies to streamline environmental studies, facilitating project continuity and sustainable resource management. Additionally, Knight Piésold secured approval of the mine’s detailed closure plan, confirming that the restoration strategies and impact management were approved within the expected timeframes.

In terms of engineering, Knight Piésold’s designs not only met MASA’s requirements but also adapted to the needs of the final production years. During this stage, the mineral composition evolved from an oxide base to a porphyry and sulfide matrix, requiring innovative solutions to maintain process efficiency. Optimizing geotechnical structures and designing more efficient leaching systems allowed the extension of the pad’s life, beyond the originally planned timeframe, maximizing processing capacity and supporting the mine’s operational continuity.

Knight Piésold is aiming to play an active role in Gualcamayo’s upcoming milestones, providing innovative engineering solutions for their new processing stages. With a creative approach tailored to the needs of the project, Knight Piésold is projecting designs that will allow the mine to continue operating safely and efficiently, supporting its long-term sustainability.