The Don Mario property is underlain by Lower to Middle Proterozoic metamorphic rocks of the Cristal Sequence that comprise a portion of the Bolivian Shield’s Adventura Complex. The Cristal Sequence is composed of medium to high grade metasedimentary units such as biotite schist, mica schist, quartzite, biotite–plagioclase gneiss and calcsilicates gneiss, as well as lesser amounts of pegmatite and amphibolite dikes. The Cristal Schist belt subunit hosts the Don Mario mine’s Upper and Lower Mineralized Zones as well as the nearby CF, Don Mario North, and Don Mario South gold prospects (Wright et al., 2009).

Mining and exploration programs to date on the property have shown the Don Mario deposit to consist of the gold-enriched LMZ and the copper-enriched UMZ. The LMZ is characterized by a well-developed northwest striking and steeply northeast dipping structural/lithologic corridor that constrains gold-coppersilver mineralization as well as distinctive alteration assemblages. Alteration associated with gold-coppersilver mineralization commonly takes the form of iron carbonate, white mica, biotite, quartz, albite, andalusite, staurolite, garnet, cordierite, gedrite and anthophylllite-cummingtonite. Spatial disposition of the LMZ and UMZ deposits may be of structural derivation, with the calc- silicate dominated and synclinally folded UMZ host sequence representing a shearing- associated “flower structure” above the sheared LMZ.

Past workers have characterized mineralization at the Don Mario deposit as being structurally focused or shear zone related. However, as outlined by Wright et al. (2009), alternative views on deposit genesis include skarn association, banded iron formation-hosted structural association, and deformed, syngenetic massive sulphide association,. In contrast to these, the deposit was more recently classified by Arce Burgoa (2009) as being a deformed example of the Iron Ore copper Gold (IOCG) association.

The current mining methods used at Don Mario UMZ are conventional open pit mining. Ore and waste are loaded into 20 to 25 tonne nominal capacity trucks using a 10 tonne nominal capacity front end loader. The ore is hauled directly to the process plant ore stockpile area and waste is hauled directly to the waste dump facility. Any oxide or low grade material is hauled to various surface stockpiles located near the plant and mine.

Crushing
Ore extracted from the UMZ pit is stockpiled and classified according to mineralogy, gold, copper, and/or deleterious element grades. When possible, a suitable ore blend is prepared to feed the mill. A front end loader collects the ore from the plant stockpile and delivers it to the crusher feed bin equipped with a 500 mm aperture slotted grizzly screen. The crusher feed bin has an apron feeder that feeds the primary single toggle jaw crusher and any apron feeder spillage is collected on a conveyor belt below. The jaw crusher set to 153 mm. The spillage and the crushed ore which is less than 90 mm in size are transferred to the next conveyor belt equipped with load cell type belt weightometer and this belt discharges into the 800 ton fine ore mill feed bin. A level indicator and controller in the mill feed bin controls the apron feeder feed rate to the jaw crusher to maintain the set level in the bin.

Grinding
Dry crushed ore at P80 < 90 mm is fed to the SAG mill (5.5 m internal diameter by 2.7 m effective grinding length) by means of a conveyor belt equipped with a load cell type belt weightometer. The load signal controls the feed rate from the mill feed bin discharge conveyor onto the conveyor belt feeding the SAG mill. The pulp density in the mill is controlled by adding process water to the SAG mill inlet. Oversize material is removed from the mill discharge pulp with the discharge end trommel screen. The oversize fraction is delivered back to the SAG mill inlet, while the undersize fraction flows to the common pump box for both the SAG mill discharge and the ball mill discharge. The combined mill discharge is pumped to a cluster of three 380 mm diameter Krebs hydrocyclones for classification (there is one on standby). The cyclone overflow reports to the flotation section and the cyclone underflow is split, with part reporting to the gravity concentration section (approximately 100 tph) and the balance reporting to the ball mill feed. The ball mill has a 3.6 m internal diameter by 6 m effective grinding length. The cyclone overflow at 40% solids has a size of P80 < 106 µm.

Don Mario processing plant consists of the following sequence of macro unit operations:
• Crushing and Screening
• Grinding and Cycloning
• Gravity Concentration
• Flotation Concentration
• Tailings Storage Facility (TSF).

The CIL circuit was placed on care and maintenance in April 2011 when the Company commenced mining the metallurgically more complex UMZ.

In the first quarter of fiscal 2016, a metallurgical testing program was completed and the results showed that re-commissioning of the carbon-in-leach (“CIL”) circuit in use until 2011 to process the LMZ resource material would maximize the value of the then recently defined Don Mario resource estimates (the “CIL Project”). The Company began construction on the CIL Project in fiscal 2016 and successfully completed re-commissioning in the second quarter of fiscal 2017.

Gravity Concentration
Milling reduces the size of the ore to less than one mm and liberates metallic go ........