Pinargozu and Horzum’s passive margin setting with inversion and collisional orogeny is favourable for the formation of MVT and Irish-type zinc deposits. The post-collisional Neogene magmatism on the Anatolian plateau is permissive of skarn/manto (or CRD) type deposits; CRD deposits typically form distal from porphyritic intrusions in magmatic arc or back-arc settings.

Pinargozu and Horzum occur within the Tufanbeyli–Horzum Zinc Belt, where mineralisation has generally been interpreted as MVT deposits, formed within the passive- margin platform carbonate sequences with fluid-flow systems related to the Cimmerian or Alpine orogenic compression and uplift. However, the deposits in the Nigde, Zamanti, Keban district have been described as intrusive-related.

Mining to date at Pinargozu has mainly been of secondary zinc mineralisation, formed through supergene oxidation of massive sulphide mineralisation. Primary massive sulphide mineralisation is becoming more dominant as the mine becomes deeper.

Sulphide Mineralisation
The primary mineralisation is characterised by coarse massive sphalerite-rich sulphide with subordinate pyrite. Massive galena also occurs and typically post-dates sphalerite, cutting and replacing sphalerite and associated with more abundant carbonate gangue. The carbonate weathers brown and is interpreted to be iron-rich and potentially manganoan. The absence of a black weathering patina suggests that manganese is subsidiary.

Contacts of massive sulphide with bleached limestone are sharp, with minor disseminated and clotty sulphide in the limestone. Based on mining, the mineralisation is crudely stratabound within the central part of the Degirmentas Formation. Observations underground suggest that massive sulphide contacts are mainly stratabound.

Secondary Zinc Mineralisation
During weathering of massive sulphide deposits in limestone, sulphide oxidation generates acid which readily transports Zn, and to a lesser extent Pb, until neutralised by carbonate wall rocks. Secondary zinc mineralisation can be direct replacement, where neutralisation is almost immediate and secondary minerals directly replace primary, or wall-rock replacement where zinc is transported out of the primary deposit and are precipitated by reaction with the wall rock, often in acid-enhanced karst cavity systems (Hitzman et al., 2003). Acid generation capacity is strongly related to pyrite content, which is low at Pinargozu.

Secondary zinc mineralisation at Pinargozu consists mainly of smithsonite, ZnCO3, and hemimorphite, Zn4Si2O7(OH)2·H2O, with minor amount of replacive hydrozincite, Zn5(CO3)2(OH)6. Secondary zinc mineralisation is associated with abundant concentrations of Fe-oxides and hydroxides and cerussite, PbCO3, as well as remnant galena, sphalerite, and pyrite. Very high-grade zinc mineralisation (>40% Zn) is associated with banded smithsonite.

Mineralisation is accompanied by a general tenor of >50 g/t silver. Local pockets of high grade silver (>250 g/t) exist, most notably in the southern lodes where sulphide proportions are higher. Elevated lead concentrations (typically galena) are almost entirely restricted to these southern lodes where, as development has extended deeper, sulphide mineralisation has become more prevalent.

Pinargozu is an underground mining operation that is currently producing high-grade zinc oxide and sulphide material of direct shipping grade. The mine currently produces from 3 adits with over 5.5 km of underground development.

90% of mining activity is via cut and fill(CAF) with the remaining 10% via shrinkage stoping. This flexibility is effective in response to changes in orebody geometry and technical limitations.

Production utilises semi mechanized CAF stoping by hand held phnomatic drillers, mini loaders and mini trucks, where the orebody is wider. Here, drifts are cut from the decline. In areas of narrower orebody geometry, a stope is driven flat with full wooden support and blasted material is mucked outside and the stope subsequently backfilled.

Some locations in the mine utilise shrinkage stoping, generally in areas where 1-3 m thick ore veins are limit the raises between drifts, to 2.0 x 2.0 m dimensions. The vein is blasted from the bottom to the top.

The Pinargozu mine has three zones defined, reflecting mining domains:

• The Upper Level (811 to 690 level), largely oxide material.
• The Middle Level (690 to 670 level), the transitional zone.
• The lower Level (670 to 550 level), fresh sulphide material.

The average dilution is 6% per wet tonne. There are good visible ore indicators.

The production schedule is based on seven days per week and 365 days per year. Crews work in 3, 8-hour shifts per day, with 1.5 hours per shift devoted to breaks, safety meetings, equipment checks and minor maintenance. Based on the existing workforce and machine utilization, the ore production rate is between 4,000 tpm to 5,000 tpm, the latter being the peak limit of mining capacity. The irregular shape of the ore body and the presence of karstic voids are some of the limitations to current production rates.

The Pinargozu mine is accessed by three adits, with current development of a fourth at the 811 m level. Each level is connected with raises or ramps for escape and ventilation. Average ramp grades are preferred at 13-15% in the main access and spirals. The production and development section dimensions are 3.0 m x 3.0 m and 3.5 m x 3.0 m.

The size specification for saleable oxide product is 90% passing 1 cm. The sulphide product must be 100% passing 1 cm and 95% passing 0.5 cm. The sulphide product must therefore be prepared to a finer specification for sale than that of the oxide product.

The sample as received is first spread out on a concrete pad to dry. After a short drying phase, the largest rocks (>1 m) are broken with a rock breaker or front-end loader. The material is then fed to the crushing plant via a front-end loader feeding a feed hopper that discharges to a conveyor belt that takes the material to the primary jaw crusher. The primary jaw crusher is set to a nominal crush size of 3 cm. A sampler working alongside the primary crusher feed conveyor removes any obvious gangue material (usually limestone) and other extraneous material. By this method of hand picking from the conveyor belt, about 6% of the total weight is removed and rejected as waste material. The crushed material is then screened at 3 cm with the oversize being repassed and the undersize stockpiled. The undersized product is 90% passing 10 mm.

The use of the primary jaw crusher is sufficient to produce the oxide saleable product, however a secondary crushing circuit is required to prepare the sulphide product.

When preparing the sulphide product, the primary screen undersize is passed through a secondary crushing circuit. The primary screen undersize if discharged to a conveyor belt which carries the material to a secondary impact hammer crusher. This crusher has a discharge set size of 0.5 cm. The crusher product is discharged to another conveyor belt and taken to a secondary stage of screening. The secondary screening is carried out at 0.5 cm with the oversize being stockpiled for repassing to the secondary crusher and the undersize product (95% passing 0.5 cm) being stockpiled as final sulphide product ready for sale.

The mineralization being mined at Pinargozu mine is direct-shipping material. The mining in-situ grade is of sufficiently high grade to not require any metallurgical process to concentrate the grade. The oxide product, as mined, averages 31% Zn and the sulphide product, as mined, averages greater than 40% Zn. The only processing required is to reduce the size of material to the specifications required by the buyer. This size reduction is carried out via a crushing plant.

The product mined at Pinargozu is trucked down to Adana (90 kms south of the mine site) where Pasinex’s JV partner, Akmetal AS, owns and operates a warehouse and processing facility. Within the warehouse facility, a crushing plant is installed. The mined product is crushed to the appropriate size specification and then stockpile stored. When the material is ready for sale it is either sent to the port of Mersin for international sales or via truck for regional sales. The port of Mersin is located on the Medi ........