Dairi Prima Mineral Ready to Develop Black Dog Underground Mine

JAKARTA - PT Dairi Prima Mineral (DPM) has confirmed that the underground lead (Pb) and zinc (Zn) mine project in Dairi Regency, North Sumatra, has obtained approval for a revised feasibility study and an addendum to the Environmental Impact Analysis (AMDAL) in 2026.

For information, currently the company is preparing to develop the Black Dog deposit with a processing capacity of 1 million tons of ore per year.

DPM Widianto's Technical Manager said that the project's licensing journey had lasted for almost three decades since the Contract of Works was signed in 1998 to 2002, black and zinc lead deposits with significant levels were found.

"Where the prospects found are called black dog prospects," said Widianto in an E2S discussion entitled "Perspectives on Science, Law, Technology and Environmental Protection", Monday, July 27.

He explained that the first feasibility study was compiled in 2004 and the AMDAL was ratified by the Regent of Dairi in 2005. Subsequently, the company obtained a Forest Area Lease (IPPKH) of 53.11 hectares in 2012, before a feasibility study was revised in 2015 due to changes in the location of the portal, Tailing Storage Facility (TSF), and explosives warehouse.

According to Widianto, in 2022 the government approved an AMDAL addendum that accommodated the three changes. However, in 2024 the Supreme Court won a lawsuit by a community group against the approval of the AMDAL addendum, so that the Minister of Environment carried out the MA's decision by revoking the approval in 2025. The 53.11-hectare IPPKH, Kontrak Karya also remains in force until December 29, 2047.

Meanwhile, based on the latest study that became the basis for the revision of the feasibility study, DPM has two main prospects, namely Black Dog and Lae Jehe.

"For the Black Dog Prospect resources we get 8.5 million tons with a zinc content of 13.8 percent and a lead content of 7.9 percent. Meanwhile, the Lae Jehe Prospect has resources of 27.9 million tons with a zinc content of around 6 percent and lead of 3.7 percent," explained Widianto.

From the results of the conversion of resources into reserves, the Black Dog Prospect has reserves of 7.7 million tons with a zinc content of 12.5 percent and 7.3 percent of lead. Meanwhile, the Lae Jehe Prospect has reserves of around 10 million tons with a zinc content of 6.4 percent and 3.8 percent of lead.

"For the initial stage, we will develop the Black Dog Prospect first, while Lae Jehe will still be drilled to obtain more detailed mineral grade data," he said.

Apply Underground Mining and Backfill System

Widianto emphasized that DPM would implement underground mining methods using a combination of longhole stoping and cut and fill, so that the former mine space would be filled back with processed tailing material.

"Tailing material is not disposed of or placed on the surface, but is first separated between liquid and solid. The liquid is reused in the processing process, while the solid is mixed with cement and then pumped back into the mine hole as a backfill material," he explained.

He added that the use of tailings as a backfill material was not done carelessly because it had to obtain technical approval from the government.

"We have obtained permission to use the waste as backfill from the Ministry of Environment as an inseparable part of the approved AMDAL addendum," he said.

In addition to producing black lead and zinc concentrates, DPM will also utilize the sulfur separation process to produce sulfur concentrates. As for the final waste of the processing process, it will be used entirely as backfill material so that the company no longer uses a Tailing Storage Facility (TSF) or a tailing dam.

In the production phase, DPM plans to build a processing plant with a capacity of 1 million tons of dry ore per year from the Black Dog deposit. The end result is zinc concentrate, black lead concentrate and sulfur concentrate which will be sold to refining companies or smelters.

Based on the company's production plan, during the total operation period the dry concentrate produced is estimated to reach 2.43 million tons, with metal content of about 473,895 tons of lead and 821,150 tons of zinc.