Mining company PT Merdeka Copper Gold (MDKA), part of the Saratoga Group owned by Garibaldi “Boy” Thohir, plans to invest around US$1.5 billion (Rp25.02 trillion) to develop the Tujuh Bukit underground copper mine in Banyuwangi, East Java.

Tom Malik, General Manager of Communications at Merdeka Copper Gold, said the investment estimate excludes the cost of building a smelter facility. He cited that underground development began in 2018 through continued exploration activities.

“For the Tujuh Bukit Underground project, with all underground development, implantation processes, and other works, the investment could reach between US$1 billion and US$1.5 billion,” Tom said during a presentation in Banyuwangi on Friday, November 7, 2025.

The massive copper reserve at the Tujuh Bukit Project, located more than 100 meters below sea level, is managed by PT Bumi Suksesindo (BSI), a subsidiary of Merdeka Copper Gold. This deposit is considered one of the largest copper resources currently under development in Indonesia.

The project is now undergoing a feasibility study (FS), targeted for completion by late 2025.

“We’re expanding deeper to extract copper and gold, a process that’s still ongoing and far from simple since this is an underground mine located by the sea,” Tom said.

Since 2018, the company has invested around US$250 million (Rp4.17 trillion) in exploration and development. The underground mine is designed using the Sub-Level Caving and Block Caving mining methods.

Based on the latest Mineral Resources Estimate (MRE), total mineral resources have increased from 1.706 billion tons to 1.738 billion tons. Indicated resources jumped from 442 million tons to 755 million tons, while contained copper rose from 8.1 million tons to 8.2 million tons, and gold from 27.4 million ounces to 27.9 million ounces.

Currently, Indonesia’s copper industry is dominated by three key players. PT Freeport Indonesia remains the largest, producing around 800,000 tons annually from its Grasberg mine in Papua. PT Amman Mineral Internasional (AMMAN) follows with 300,000 tons per year from the Batu Hijau mine in West Nusa Tenggara.

Merdeka Copper Gold, through the Tujuh Bukit project, aims to produce 115,000 to 120,000 tons annually at full operation − potentially increasing Indonesia’s total copper output by 10–15 percent.

“Once operational, we’ll become Indonesia’s third-largest copper producer, after Freeport and Amman Mineral,” Tom said.