Renewable | KRAVVARITIS & PARTNERS | Consulting Engineers, appointed by Thracean Gold Mining S.A. (www.tgm.gr) to undertake the Technical Study & Basic Design Update for the development of the gold mine of Perama Hill in the Prefecture of Evros (Greece).
The oxidized gold deposit at Perama consists a typical deposit of low sulfidation which is located in sedimentary rocks of Eocene to Oligocene age. It is located in Northeastern Greece, on the border of the Evros and Rodopi prefectures. The mineralization of gold has been supplied through a tectonically controlled system of fractures in andesites, to the highly porous arenaceous caprocks. Eighty percent of the mineralization is located in sandstones and the rest is connected with andesite breccias and conglomerates. The deposit of Perama does not contain As (arsenic), Pb (lead) or other heavy metals.
The project is located in a non-residential area, of a low agricultural and forestry production value in the prefecture of Evros in Thrace. The intervention area of the project does not exceed 0.742 square kilometers in total making it one of the smallest mines in the world.
Its design is in full compliance with the Directives of the European Union on Best Available Techniques and Mine Waste Disposal, which are based on the principle of “zero discharge” to the environment (deposition of solid filter cake residues, dust elimination, water recycling), and, of course, with the Greek legislation.
Due to the surface position and the geometry of the deposit, a closed-type open-pit mining method has been planned. The hydrometallurgical processing of the ore which will be based on the principle of zero discharge to the environment will take place. The main processing features are the following:
- Processing of 3,288 ore tonnes per day, 24 hours a day, 365 days a year.
- Crushing and milling of the ore in a closed circuit, to a size less than 100 microns.
- Gold is dissolved with the use of a Sodium Cyanide (ΝaCΝ) solution in thickener tanks.
- Gold is absorbed on the surface of the activated carbon chips.
- Sodium cyanide is used in a closed circuit and reused in the production process.
- Detoxification of tailings with the INCOTM (SO2/oxygen) method at content levels < 1ppm CN.
- Thickening of the slurry and dehumidification in filter presses.
- Recycling of water from the filter presses and reuse in the production process (closed circuit).
- Deposition of the dehumidified tailing (filter cake) (85% solid residues content by weight) at a specially designed watertight area.
- Recovery of 90% of the gold and 60% of the silver.