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The Zgounder silver mine is the second most significant silver mine in Morocco after Managem’s Imiter silver mine. It is the flagship high-grade silver asset of Aya Gold & Silver, which was formerly known as Maya Gold & Silver.
The Zgounder silver mine is owned by a joint venture between Aya’s subsidiary Zgounder Millennium Silver Mining (ZMSM, 85%) and the Office National des Hydrocarbures et des Mines (ONHYM, 15%).
Maya acquired the 85% interest in 2011 after winning a tender conducted by ONHYM.
Zgounder silver mine development details
After being placed under care and maintenance since 1990 due to low silver prices, the Zgounder mine produced first silver in 2014. Aya is focused on developing the project to achieve full production.
GoldMinds Geoservices (GMG) conducted the first NI 43-101-compliant mineral resource assessment in 2014. Aya released the preliminary economic assessment (PEA) study for the Zgounder mine in the same year.
The company again commissioned a mineral resource estimation study and a PEA in April 2017. The estimate and the PEA were published in January 2018 and February 2018, respectively. A feasibility study to expand the silver mine was commissioned in August 2020 to achieve an increase in tonnage, with a preliminary target of 2,000 tonnes per day (tpd). The study is expected to be completed by the fourth quarter of 2021.
The mine currently has a nameplate capacity of 700tpd and operates at approximately 500tpd.
Zgounder silver mine location, geology, and mineralisation
The Zgounder silver mine is located approximately 265km east of Agadir City in the central Anti-Atlas Mountains in the Taroudant province. The exploration licence covers an area of 16km².
The mine’s geology comprises three formations, including the blue and brown formations with a clastic portion intercalated with volcanic sequences overlain by the black formation, which is an acid ignimbrite volcanic complex.
Silver mineralisation occurs at the peak of the brown formation, primarily at the point of contact and within the sill of dolerite. It extends over 1,000m laterally to the south with a sub-vertical dip.
Zgounder silver mine reserves and resources
The Zgounder silver mine was estimated to contain 493,582t of proven and probable mineral reserves comprising 4.93Moz of contained silver (Ag) graded 311g/t of Ag, as of January 2018.
Mining at Zgounder silver mine
The underground Zgounder silver mine employs the cut-and-fill mining method, which is also suitable for steep-dipping high-grade deposits. The use of cut-and-fill mining involves mining the mineralised material in horizontal slices, beginning from a bottom undercut and going upward.
The material undergoes a series of steps, including drilling, blasting, loading and removal from the stope, which is then backfilled with waste materials.
The mill feed rate is increased from 200tpd to 500tpd in 2020 and further to 2,000tpd in 2021 for the remaining seven years until 2027. The mining dilution is approximately 10% by 2020 and will rise to 30% by the end of operations in 2027.
According to the PEA, the production will be increased to 1.354Moz a year and further up to 4.762Moz of silver a year.
Based on the PEA, approximately 45% of the mill feed will come from the open-pit, 12% will come from the old tailings, while the remaining feed will be obtained from underground sectors.
Processing at Zgounder silver mine
According to the PEA, the 500tpd processing plant uses gravity-flotation process followed by the cyanide leaching of the gravity and the flotation concentrates to extract silver.
The upper mill will be located 1.5km from the lower mill and include run-of-mine ore storage, a three-stage crushing plant, two 500t material bins, a two-stage grinding bay integrating gravity, and a flotation section, followed by gravity and flotation concentrates thickening and regrinding zones.
The lower mill will be fed by gravity from gravity-flotation concentrates from the upper mill.
Material coming from underground will be hauled off the road haul trucks to be pumped directly into the crusher feed hopper out of mine.
The jaw crusher hopper will be discharged into a feeder for the middle-duty plate, which will later feed the primary jaw crusher. The mineralised material will be transferred to a vibrating screen in close circuit with a cone crusher.
The oversized material from the top screen will fall into a smaller jaw crusher and then mixed with the bottom deck’s oversize before being conveyed to the cone crusher.
The screen undersize will be delivered to two 500t live load fine ore bins. Each fine ore bin will have four openings at the bottom discharging on a dedicated conveyor. The crushing capacity will be approximately 100tph.
Processing will also include grinding, flotation, thickening and regrinding, leaching and decantation, silvery recovery, and smelting.
The Zgounder mine can be accessed from Agadir via N10 and P1706 highways.
The mine sources water from a barren solution tank and from tailings-polishing ponds.
Electricity is currently provided by three 800kW generators of 1,000kVA. A new 22kV power line with a capacity of 2,500kVA will supply power to the mine.
Key players involved
ENGITECH was contracted to perform environmental monitoring of the mine site while GoldMinds Geoservices was hired to prepare the mineral resource estimate and the PEA in April 2017. It was assisted by SGS Geostat in preparing the PEA.
The upper mill was designed by Yantai Xinhai Mining Research & Design.
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