Name:

Aljustrel Mining Complex.

Location:

The Aljustrel Mining Complex is located in the south of lower Alentejo, in Portugal, and Andalusia, in Spain.

Mine Owner/s:

ALMINA-Minas do Alentejo.

Brief Description:

The Aljustrel mining lease covers the St João, Moinho, Algares, Feitais and Estação deposits over 5.2 km².  The lease was signed between the Secretary of State of Industry on behalf of the government of Portugal and Pirites Alentejanas SA on January 10, 1992.  The permit is valid for 50 years from the date of signing, with a right of renewal, and includes the exploitation of sulphur, copper, zinc, lead, silver and gold.

Brief History:

Metal extraction at the Aljustrel mines, particularly the São João and Algares deposits, started in the pre-Roman and Roman periods. During that time, extraction was focused on copper, silver and gold.

Ownership of the mining area changed hands multiple times, with records from 1848 noting that the first mining grant for Aljustrel was awarded to a Spanish citizen, Sebastian Gargamala. Within a few years, the grant was transferred to a Portuguese mining company Transtagana, which ran a large-scale operation for fifteen years before going bankrupt.

The mining grant was then transferred to the bank Fonseca, Santos & Vianna which, in association with a Belgian company, helped to create the Société Anonyme Belge des Mines d'Aljustrel. This entity explored the mine until 1975, when it was nationalised and renamed to Pirites Alentejanas SA. Ownership of the mine changed several times from 1975 to 2009.

Work at the Aljustrel complex has been suspended on numerous occasions since 1975, including in 1993, owing to technical and economic reasons. From 2000 to 2006, several projects were commissioned to restart the mine and, in December 2007, after 14 years of care and maintenance, production at Aljustrel resumed. At the time, Pirites Alentejanas SA was a subsidiary of Canada’s Lundin Mining.

Activities were suspended again in November 2008, owing to the global financial crisis. Lundin Mining sold Pirites Alentejanas SA to a Portuguese holding company in February 2009. Subsequently, Portuguese group I’M Mining acquired the company, altering its corporate name to ALMINA-Minas Do Alentejo.

Primary Metals/Minerals:

Zinc, copper, lead and silver.

Secondary Metals/Minerals:

Gold.

Geology/Mineralisation:

The Aljustrel mining complex is located on the western tip of the Iberian Pyrite Belt (IPB). The deposits contain pyrite, sphalerite and chalcopyrite. They were the largest deposits in the IPB, with original resources of more than 200-million tons, and a historical production reported in the past century of about 16-million tons.

The IPB is characterised by volcanic massive sulphide-type mineralisation, containing metals such as copper, zinc and lead.

Reserves: 

A 2007 report compiled by Wardell Armstrong International for Lundin Mining notes that the Feitais deposits had probable zinc mineral reserves of 12.2-million tons grading 5.67%, 0.22% copper, 1.77% lead and 64.15 g/t of silver.

The Moinho deposit had a probable zinc mineral reserve of 2.15-million tons grading 4.49% zinc, 0.54% copper, 1.82% lead and 53.95 g/t of silver.

Resources:

The 2007 report also notes that the Aljustrel operation, specifically its Feitais, Moinho and Estação deposits, had a total measured and indicated zinc resource of 23.58-million tons grading 5.66% zinc, 0.23% copper, 1.79% lead and 60.79 g/t of silver.

During a corporate presentation by metals streaming company Wheaton Precious Metals in September 2023, it was reported that Aljustrel had a measured and indicated resource of 17.7-million tonnes grading 50.2 g/t of silver.

Type of Mine:

Underground.

Mining Method:

Underground.

Major Infrastructure/Equipment:

The Aljustrel plant was originally designed to process 1.15-million tonnes a year of Moinho ore using a primary grind of 80% passing 30 µm. The circuit consisted of autogenous milling and sequential flotation to produce selective copper, lead and zinc concentrates. This continued until the first shutdown in 1993.

In the mid 2000s, the Aljustrel plant was redesigned to process 1.8-million tonnes a year of massive sulphide zinc/lead ore from the Feitais deposit, although Moinho ore was treated during the first 18 months of operation. There were significant changes to the flowsheet after 2006, when a decision was made to install a conventional crushing circuit using two stages of cone crushing, followed by two stages of ball milling.

This method of ore processing continued until the first quarter of 2018, when the mill was converted to treat zinc ore and produce a zinc/lead/silver concentrate.

Prospects:

Reuters reported on September 12, 2023, that Almina-Minas do Alentejo will halt the production of zinc and lead concentrates at Aljustrel from September 24 until the second quarter of 2025, owing to low zinc prices.

Newspaper Correio Alentejo had previously reported that the mine had “a useful life expectancy of more than ten years” and was evaluating new exploration areas.

It also reported that Almina-Minas do Alentejo’s president Humberto da Costa Leite cited a prospecting project and noted that the company was finalising a feasibility study for the Estação deposit and “deepening knowledge” of the other deposits, particularly São João.

Contact Details

ALMINA-Minas Do Alentejo

Tel +351 284 249 400

Email geral@almina.pt

Sources

ALMINA-Minas Do Alentejo S.A. Website https://www.almina.pt/en/

ALMINA-Minas Do Alentejo S.A. Aljustrel Overview.

ALMINA-Minas Do Alentejo S.A. Company Overview.

Empresa de Desenvolvimento Mineiro. Website https://edm.pt/en/

Empresa de Desenvolvimento Mineiro. Environmental Remediation of the Aljustrel Mining Area 2006 – 2015.

Jornal Correio Alentejo. https://correioalentejo.com/

Jornal Correio Alentejo. Empresa mineira de Aljustrel avalia novos jazigos (November 12, 2020).

Lundin Mining. Website https://lundinmining.com

Lundin Mining. Lundin Mining Provides Aljustrel and Neves-Corvo Operations Update (November 13, 2008).

Lundin Mining. Lundin Mining Closes Sale of Aljustrel Mine (February 5, 2009).

Mindat. Website https://www.mindat.org/

Mindat. A briefing of Aljustrel mines (January 12, 2015).

Reuters. Website https://www.reuters.com/

Reuters. Almina-Minas halts zinc and lead concentrate operations at Aljustrel (September 12, 2023).

US Securities and Exchange Commission. Website https://www.sec.gov

US Securities and Exchange Commission. Company Filings. Lundin Mining. Technical Report on the Aljustrel Mine, Southern Portugal (1 November 2007).

Wheaton Precious Metals. Website https://www.wheatonpm.com

Wheaton Precious Metals. Corporate Presentation. (September 2023).