By Martin Zimmermann
The journey from Asmara to the Emba Derho mine, the “heart” of the Asmara Mining Share Company (AMSC), takes just under 20 minutes. The Chinese company Sichuan Road and Bridge Mining Investment Company (SRBM) holds a 60 per cent stake in the joint venture, with the state-owned Eritrean National Mining Company (ENAMCO) holding the remaining 40 per cent. AMSC has three further licenses for the mining of gold, silver, copper and zinc in Debarwa, Adi Nefas and Gupo.
The Emba Derho mine, which extends over a length of 1,200 meters and a width of 850 meters, is currently being prepared for open-pit mining. This is also where the central processing plant (flotation plant) is being built, where the ore from all AMSC mines will be processed for export. Equipped with protective helmets, high-visibility vests and sturdy footwear, we set off. Taking photos? No problem. “We have nothing to hide!” says Francis Darpatem, a Ghanaian citizen and project manager at AMSC, who is guiding me through the mine. We pass a dam, which, with a capacity of 1.5 million cubic meters, is already very well filled and supplies fresh water to the processing plant, to the highest point of the mine. From here, the terraced structure of the open-pit mine is already clearly visible. Piles of reddish ore are stored separately in one area of the mine. “This is gold-bearing ore that will be processed in a separate carbon-in-leach (CIL) gold processing circuit, which is currently under construction, once the flotation plant is completed,” explains the AMSC project manager.
Excavators Eat their Way through the Landscape
The expansion of the mine is a dusty business: in the open-pit mine, the upper layer of earth, the “overburden”, is first removed in order to reach the gold- or copper-bearing rock. Heavy machinery – excavators, wheel loaders and controlled blasting – are used to loosen the rock and remove it efficiently. Excavators eat their way through the landscape, trucks kick up dust. As agricultural businesses border directly on the mine site and farmers go about their work, trucks with water sprinklers regularly make their rounds on the dusty tracks. This is an environmental protection measure that is a must for the mine operator. In this way, the environmental compatibility of mining and agriculture in this densely populated area is ensured on a small scale: tomatoes and Swiss chard growing in the fields next door should not be
contaminated with dust.
Mine’s Power Plant Supplies the Energy
From the hilltop, Darpatem points to the centre of the mine, where the central flotation plant for all four AMSC mines (Emba Derho, Debarwa, Gupo and the Adi Nefas underground mine) is being built from scratch. In this plant, the ore crushed in the large rock crusher is further processed into a concentrate and prepared for shipment to smelters. A 30-megawatt power plant, offices, technical rooms, a canteen and a small clinic are being built around the flotation plant, “which we hope we will never have to use for serious cases,” says the project manager. The power plant, which runs on heavy oil, supplies the mine independently of the public power grid.
Chemical Cocktail Instead of Shovel and Wash Basin
Anyone involved in the industrial extraction of mineral resources will quickly abandon the cliché, portrayed countless times in films, of rough-and-ready men setting off as gold prospectors with shovels, sieves and wash bowls and finding fist-sized nuggets.
Modern mining has nothing to do with this romanticized image of the gold rush. Gold is usually extracted from crushed ore using a highly toxic mixture of chemicals consisting of water, sodium cyanide or mercury. During the processing and concentration of copper ore in the flotation plant, calcium carbonate and sulphuric acid, among other things, are used to enrich the copper ore to a 20 to 30 per cent copper concentrate before it goes into smelting.
Public Safety Concerns taken Seriously
Mining in the densely populated area around the capital Asmara and in the catchment area of natural water resources has raised concerns and questions among the population – which are being openly discussed. Francis Darpatem, a mining expert with many years of professional experience in mines in Ghana, the Democratic Republic of Congo and Eritrea (Bisha), is familiar with such fears and concerns: “If mining is not carried out professionally and with the utmost care, there is a risk of major damage to the environment and nature.” This is precisely what needs to be prevented: “We are working here at the highest international level and the feasibility study for the mine has been carried out extremely thoroughly over a period of ten years.” This is a very long time, but it is also an important preparation for the safe operation of the mine. He assures us that complex waste and water management prevents pollutants from entering the environment. “The process water from the flotation plant is recycled within the mine and fed through kilometers of steel pipes into a watertight collection basin called a TSF (tailings storage facility), which is
lined with thick plastic sheeting.”
Safety and Environmental Protection are Top Priorities
Two steel pipelines are being built to feed into the TSF – one of which will remain on standby in case problems arise with the other pipeline. In the first phase, the collection basin will hold 6.6 million cubic meters with a dam height of 35 meters. By the third phase of the planned six-year production period, this basin will be gradually expanded and will then be able to hold 35.4 million cubic meters of water with a dam height of 60 meters. “The water evaporates in the sun, the pollutants crystallize and the toxic components are broken down over time by the sun’s UV radiation,” explains Darpatem. Additional safety dams have been built around the collection basin and checkpoints are used to check daily for any escape of contaminated water. For Darpatem, safety and environmental protection are part of his professional ethics. He knows of examples in other countries where people and the environment are harmed by uncontrolled, often illegal exploitation of mineral resources – where greed literally kills. When asked what he thinks of Eritrea’s mining policy, he responds cautiously:
“Well, I’m not a politician. I am a mining engineer and manager. But I see – and I stand for – the highest standards prevailing in the mines here. The fact that Eritrea holds a 40 per cent stake in mining and uses the resources to build up the country is exceptional compared to other countries. The bottom line is that I would say this is good policy for the country.”
Production is Scheduled to Start in mid-2026
“The goal is to start production here in mid-2026,” says the AMSC project manager. “Then 1,000 to 1,200 people from the surrounding area will find well-paid and secure work here in the mine.” The Eritrean government insists on hiring local workers – a practice that all investors in Eritrea had to come to terms with at first. Highly qualified local workers are also available: graduates of the natural sciences and technical faculties of the Eritrea Institute of Technology (EIT) at Mai Nefhi College, who have studied geology, mining engineering, process engineering and chemical engineering, bring specialist knowledge to the table. Since 2011, graduates of Mai Nefhi College have been trained as mining experts in the mines of Bisha and Zara.
The Prospects for AMSC are Bright
The Asmara Mining Share Company has bright prospects for a lucrative business: the company’s trump card is undoubtedly the open-cast mine in Debarwa, where copper ore has been mined since 2024 and immediately shipped for smelting. With a copper content of 13 to 16 per cent, further processing and concentration of the ore is not worthwhile. The profits from the open-cast mine in Debarwa are being used to finance the construction of the processing plant in Emba Derho. And according to estimates based on exploration of the mining areas, AMSC’s four mines contain 415,000 troy ounces of gold, 11 million troy ounces of silver, 580,000 tonnes of copper and 1.13 million tonnes of zinc. In addition, AMSC has two further exploration Licenses in Adi Rassi and Kodadu, where geological exploration work is underway to also mine the resources available there
What Does the Term “Carbon-in-Leach” Mean?
In the CIL process, crushed gold-bearing rock is mixed with water and cyanide in tanks, where the gold is leached out and simultaneously adsorbed onto activated carbon particles. The gold is later removed from the carbon and recovered. The unusable slurry is directed into a lined basin called a tailings storage facility (TSF), which is located about 4 km from the processing plant. The CIL cycle has a small footprint, requires less earthworks and consumes less energy during operation than other methods. The cyanide is captured within the plant by a robust management system that includes double containment without discharge to the environment.
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A veritable ‘gold mine’: the Arabian-Nubian Shield
Geologically speaking, around 60 per cent of Eritrea’s territory belongs to the Arabian-Nubian Shield (ANS). The term ‘shield’ is used in geology to describe large areas of exposed crystalline magmatic and highly metamorphic rocks from the Precambrian era that form tectonically stable areas. These rocks are more than 570 million years old, some even 2 to 3.5 billion years old. The ANS is one of the largest Precambrian rock formations in the world, rich in easily mineable raw material deposits. It contains large deposits of gold, silver, chromite, cobalt, copper, zinc, manganese, nickel, tantalum and uranium.
Ancient Egypt owed its wealth of gold to the precious metal deposits in Nubia. Nubia, the ancient kingdom south of Egypt in what is now Sudan, was an important source of resources such as gold, ivory, ebony and copper for Egypt during their complex mutual relationship. Egypt was the main producer of gold in early antiquity. Gold production there peaked around 1300 BC.
The Nubian Shield lies on the African continental plate, mainly in the countries of Egypt, Sudan and Eritrea, while the Arabian Shield lies on the Arabian Peninsula of the Asian continental plate. Originally, the Arabian and Nubian Shields were connected. They were only separated as a result of the opening of the Red Sea due to the drifting apart of the African and Asian continental plates about 25 million years ago. Over 1,000 ancient copper and gold mines are known to exist on both geological plates.
Geologists estimate, however, that there are further rich gold and copper deposits at more than 6,000 locations on these geological plates – of which, however, only a handful are currently being exploited using modern methods or are in the preparatory phase of exploration for industrial exploitation.
Not least because of their rich mineral deposits, countries such as Eritrea on the Arabian-Nubian Shield have become increasingly attractive to investors and mining companies in recent years. Very large deposits have already been brought into production here. One example of why industrial mining is particularly worthwhile there is that the copper content in the ore from the Debarwa mine in Eritrea is 13 to 16 per cent when mined in open pits and is shipped directly to China for smelting. By comparison, in Chile, the world’s largest copper producer, the copper content in mined ore averages only 0.65 per cent. 2 Before smelting, Chilean ore must first be processed into higher-grade copper concentrate at great expense.
Sources used:
- The Geology of the Arabian–Nubian Shield, Springer International Publishing
- Germany Trade & Invest
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