The Gediktepe deposit is a skarn type Massive Sulfide or MS type of metal sulfide ore deposit. These deposits are created by volcanic-associated hydrothermal events in submarine environments. They are typically high in copper, zinc, and other sulfide minerals.

Mineralization at Gediktepe is related with schist that is metamorphosed under green schist facies conditions. The mineralization is thought to be deposited syngenetically in sedimentary units and metamorphosed to schist. Green schists generally are comprised of actinolite + chlorite + albite + epidote minerals.

The upper portion of the Gediktepe deposit has been weathered, leached, and oxidized by naturally occurring acidic surface water and ground water. The natural acidity is due to the presence of sulfides, particularly pyrite.

Within the oxidized zone, the sulfide mineralization has been nearly completely leached out leaving the gold and silver relatively intact. Relic “lenses” or zones of high gold mineralization can been seen in the oxide zone. There is some evidence that gold mineralization has been transported downward chemically or mechanically as there is often an increase in gold grade just above the oxide –sulfide contact.

The bottom of oxidation is generally abrupt with rapid changes of metal grade between adjacent assay intervals. Copper and zinc grades are typically less than 0.10% within the oxide zone, but they increase to typical values of 1.4% Zn and 0.80% Cu immediately below the oxide horizon. Gold and silver follow the opposite trend. Gold can be in the range of 3.0 gm/t in the oxide zone and often less than 0.5 gm/t immediately below in the sulfide zone.

The Gediktepe oxide type mineralization is indicated by yellow to red leach zones of intense iron oxide Gossan. Near surface, a leached cap has occurred which is typically low grade in all economic metals. This material often forms a few meters of ferricrete.

The gossan oxide is a hematite rich and highly oxidized unit. It can vary in texture from a breccia with unoxidized clasts to a consistent nearly soil like material where oxidation has obliterated the original texture of the protolith. It hosts locally high values of gold and silver. In general, the upper portion of the gossan zone is low in precious metal grade with abrupt increases from waste to ore grade as one scans down a drill hole. That boundary has been incorporated into the block model as a population boundary between low grade and high grade gossan.

The massive pyrite and massive pyrite magnetite are the primary ore types within the sulfide zone. The MPM+MPY mineralization forms lenses or veins that average 20m wide and contain pyrite, sphalerite, tetrahedrite, tenantite, chalcopyrite, and galena. Magnetite is present in both units but it is particularly evident in the MPM. Other sulfide minerals include pyrite, sphalerite, tetrahedrite, tenantite, chalcopyrite, and galena. Within these unites the mineralization has completely over printed the shistosity of the host units.

The Gediktepe deposit will be mined by conventional open pit hard rock mining methods. Polimetal currently plans to utilize a contract mining company to move the ore and waste from the mine.

Compared with typical mining practices in North America, Turkish contractors generally utilize small back hoe loading units with relatively small haul trucks. The mine geometries have been designed with the assumption that mining will be completed by a Turkish contractor with 3-4m3 backhoes and 35-40 tonne trucks. The mine geometries have been designed with 12 meter haul roads and minimum mining widths of ~70 meters.

The mineral reserve at Gediktepe is comprised of 2 ore types: oxides and sulfides.

Following a three month ramp up period that produces ore at an average of 2,200 tonnes per day, the Gediktepe PFS mine plan produces oxide mineralization to a heap leach facility at a rate of 3,000 tons per day for a little over 3 years. After that period, the minor oxide material that is incurred during sulfide mining will be sent to the waste storage facility.

Sulfide process feed starts during year 3 at a throughput rate of 4,500 tons per day. Sulfide ores that are incurred in year 1 are assumed to be waste while sulfide ore mined in year 2 is stockpiled to be fed to the crusher in year 3. In year 4, the sulfide throughput increases to 6,500 tons per day as the oxide material is exhausted.

Heap Leach Process Flowsheet for Oxide Ore

Based on the test work for the oxide ore, it became evident that the ore could be efficiently processed in a heap leach. This would result in lower capital cost while sacrificing very little in gold or silver recovery.

The run-of-mine ore will be crushed in three crushing stages to produce a product with P100 of 19 mm. A 19 mm opening screen is planned on the feed to the tertiary crusher to remove the finished product. The tertiary crusher product will be recycled back to the screen. The crushed ore will be discharged onto a conveyor which will convey the ore to the agglomerating drum.

he ore will be agglomerated with cement, lime and cyanide solution. The agglomerated ore will be discharged to a conveyor which will convey the ore to the leach pad. At the leach pad, grass hoppers and a stacker will be employed to stack the ore on the pad.

The ore will be leached with cyanide solution having a strength of 0.5 g/L and fed at a rate of 12.2 L/hr/m2 . The ore will be leached for 30 to 45 days and the pregnant solution collected in the pregnant solution pond. The pregnant solution will be processed using the Merrill Crowe process to recover gold and silver precipitate. In case the precipitate has high amounts of copper, it will be leached in a batch leach circuit with sulfuric acid and the residue filtered in a plate and frame filter press. The filtrate will be sent to the tailings pond in years 3 and 4 and to the clarifier backwash during years 1 and 2 when TSF construction is not complete. The residue containing gold and silver will be smelted in the furnace to produce a doré bar.

Flotation Process Flowsheet for Sulfide Ore

The plant was designed to process 6500 mtpd of massive sulfide ore. The run-of-mine ore will be processed in a three-stage crushing circuit to produce a product with a P80 of 12 mm. The crushing circuit will be the same as designed for the oxide ore heap leach process.

The fine crushed ore will be sent to the primary ball mill which will be operated in an opencircuit mode. Discharge of both primary and secondary ball mills are sent to the common sump. The ground slurry is pumped to the cyclones and cyclone underflow is sent to the secondary ball mill. The cyclone overflow, having a P80 of 45 microns, is the feed to the flotation circuit. The depressants, namely metabisulfite (MBS), zinc sulfate (ZnSO4), sodium sulfide (Na2S) and sodium silicate (Na2O(SiO2) ) are added into the primary ball mill.

The cyclone overflow is fed to pre-flotation circuit which consists of two tank cells. MIBC is added to the feed box of the first cell. Talc is floated in these cells and sent to the tailings pond. The pre-flotation circuit tailings are sent to the copper conditioner where collector sodium aerofloat is added. It is also stage-added in the copper rougher flotation circuit.

The copper rougher concentrate is sent to the copper regrind cyclone sump where it is mixed with copper cleaner scavenger concentrate and copper cleaner 2 tailings. Depressants (MBS, ZnSO4, Na2S, Na2O(SiO2) and NaCN) are added into the regrind mill. Copper regrind cyclone overflow, having a P80 of 20 micrometers, is sent to the copper cleaner conditioner where it is conditioned with the collector Aero 8761. Copper cleaner 1 concentrate is sent to second cleaner stage and the cleaner 1 tailing is sent to cleaner scavenger circuit. The concentrate is cleaned three more times in a counter-current circuit, namely, the tailings go back to the previous cleaner stage feed. The fourth cleaner concentrate is the final product and is sent to the thickener and thickener underflow to the filter.

The copper rougher tailings are sent to the zinc conditioner 1 where zinc is activated with copper sulfate (CuSO4) and lime is added to adjust pH to 11.5. Collector Aero 7279 is added to zinc conditioner 2. Rougher zinc concentrate is floated in the rougher flotation circuit. The concentrate is sent to zinc regrind circuit. The zinc regrind and cleaner flotation circuit is identical to the copper circuit. The zinc cleaner 4 concentrate is sent to thickener and the thickener underflow to the concentrate filter.

The zinc rougher tailing and zinc cleaner scavenger tailings are combined and sent to tailing thickener. The thickener overflow is sent back as process water and the thickener underflow s pumped to the tailings pond. The process water will be treated in the water treatment plant before being returned to the process plant.