The Concepcion Del Oro district represents a porphyry copper deposit that has been eroded down to a relatively deep level, as evidenced by the outcropping skarn alteration. Skarn alteration is barren unless the skarn is overprinted by the later porphyry style alteration marked by propylitic, phyllic and potassic alteration types. Trace metal geochemistry supports the classification of Concepcion del Oro as a porphyry deposit. Strongly anomalous bismuth, tellurium, arsenic and antimony are present and are typical trace metal assemblages associated with porphyry copper deposits. This trace metal assemblage is most anomalous in areas of phyllic and potassic alteration.

The mineralization in Aranzazu has a strike length of 1.5 km, a width of up to 250 m and depth extents up to 600 m. The Aura Minerals’ exploration and definition drilling shows that mineralization is closing off at BW, Mexicana and AA but open at depth in Glory Hole Porfido zone. The deepest drilling conducted to date was carried out by Aura Minerals indicated the presence of strong copper mineralization at an elevation of 1,500 m, or 600 m below surface.

Copper, gold and silver mineralization occurs in a porphyry alteration assemblage related to the intrusion of an igneous rock complex consisting of quartz monzonitic to granodioritic rocks. The igneous rocks have intruded a sequence of Jurassic to Cretaceous limestones and siltstones. The sedimentary rocks have undergone contact metasomatism and skarnification and now represent a group of rocks ranging from endoskarn and exoskarn, proximal to the intrusive, to marble, distal to the intrusive. Hornfels is present and reflects the contact metasomatic alteration of clastic rocks. Porphyry alteration consisting of propylitic, phyllic and potassic alteration overprints the skarn, quartz monzonite and, in some areas, marble and hornfels. The porphyry alteration is the mineralizing event that deposited the suite of metals that comprise the mineral deposits of interest.

The copper mineral species present in the different zones vary depending on the alteration style that is prevalent. In the BW zone, host to propylitic alteration, the copper mineralization is mostly chalcopyrite. Copper mineralization present in phyllic and potassic alteration styles is chalcocite, copper sulphosalts, chalcopyrite and bornite. The trace metal assemblages also vary depending on the copper minerals present. The BW zone contains moderate amounts of arsenic, but is relatively low in antimony, bismuth and tellurium. In areas of phyllic and potassic alteration where multiple copper mineral species are present, the amounts of arsenic, antimony, bismuth and tellurium increase.

Other phases of mineralization are evident in the Concepcion Del Oro area. Zinc-lead-silver deposits are noted as discrete, relatively small chimney and manto deposits. The zinc-lead-silver mineralization phase is present as both distal deposits relative to the Arroyos Azules copper mineralization and as late stage mineralization that postdates and cross cuts the Arroyos Azules copper mineralization.

Some skarn and intrusive zones contain high concentrations of molybdenum. Often garnet skarn contains several percent of coarse grained molybdenum and it is also common in veins which cut skarn and intrusive. Molybdenum occurs within weakly propylitized endoskarn and exoskarn, though it is not clear from geological relationships where the molybdenum mineralization occurs paragenetically relative to the copper and zinc- lead-silver pulses of mineralization. Molybdenum grades do not return assays that would be considered economic.

Gold mineralization occurs throughout all of the alteration phases previously mentioned with the exception of skarn alteration. Gold grades are generally higher in the phyllic and potassic alteration assemblages compared to propylitic altered rocks.

The Aranzazu underground mine is accessed by two portals which are near the processing plant. Main ramps, driven at 5m high by 5m wide are used to access the underground workings. For the re-start plan, two (2) new ramps are designed to access the GHFW and GHHW zones. Ramps are designed at the same dimensions, with an average gradient of approximately 14.2%.

Mining will be carried out using the Sub-Level Open Stope (SLOS) mining method to extract the ore. Stopes will be extracted in a transverse method (perpendicular to the strike of the orebody) using a primary/secondary stope configuration. In this mining method, haulage galleries are developed parallel to the ore zones on each production level as defined by the sub- level interval. Sub-level intervals are designed between 25 to 30 meters to minimize the amount of waste development on the sublevels. While the majority of the stopes will be mined transverse, there are some areas that will allow the ore to be extracted in a longitudinal approach. Stopes are to be filled with cemented rockfill for primary and uncemented waste material for secondary stopes.

The mine development and production schedule were developed using the Deswik® software package. The sequence for both development and production activities was developed and the appropriate rates and production targets were applied to achieve the required schedule of activities. During the first year, development will focus on the GHFW ramp and level development, as well as establishing access to the existing mining zone. Ore production will begin within the first 3 months from easily accessible areas; however, it will require a ramp up period of approximately 14 to15 months to reach full production of 2,597 tpd.

It is intended to use a mining contractor to do all the development and stoping, haulage of ore to the mill and placement of backfill. Aranzazu will provide the main services, such as ventilation, de-watering (pumping), compressed air and electrical reticulation along with technical services.

Ventilation will be provided by two 2.35m diameter Axial Mine Fans. Fresh air will intake through the main portals and exhaust through ventilation raises. The pumping system is designed to handle 40 to 45 l/s of water. Water will be pumped in multiple stages from the bottom of the mine to a central clarifier sump. Clean water will be pumped to the surface storage ponds.

For the existing areas of the mine, electrical power will be provided from the existing sub- stations on surface feeding at 4.16 kV. A new sub- station will be installed to supply power to the new sections of the mine (GHFW and GHHW zones) at 13.6 kV. Compressed air and water will be supplied using the existing systems.

Crushing
Run of mine ore is scalped across a static slotted grizzly screen with 15-inch openings and then fed to a vibrating screen with 4 inch wide slotted openings before the 36 inch X 42 inch (250 hp) primary jaw crusher. Both screen undersize and crushed ore are conveyed to the secondary vibrating screen which has a slotted 9.5 mm lower deck and produces final crushed product while the oversize is crushed in the secondary 300 hp cone crusher. Secondary crusher product is conveyed to the tertiary vibrating screen which has a 9.5 mm slotted lower deck and produces final crushed product from the undersize with the oversize reporting to the 400 hp tertiary cone crusher. The tertiary crusher product is recycled to the tertiary screen forming a closed loop operation. Crushed ore is conveyed to the fine ore distributor above the stockpile. The stockpile provides live capacity for approximately 12 hours of operation of the plant.

Primary Grinding
Design feed tonnage to the grinding circuit is 116.7 tonnes per hour. The three 373kw (500 hp) primary single stage ball mills are fed by conveyors which have single idler weightometers. The existing 186 kw (250 hp) regrind mill, now known as the #4 primary mill, has been converted to primary grinding with the feed being ball mill discharge from two of the 298 kw (425 hp) primary mills. The tonnage is controlled by adjustment of the speed of the conveyors under the feed pipes from the stockpile. The ball mills discharge to primary cyclone feed pump boxes and the primary cyclones operate in closed circuit with the mills to produce a flotation feed with a p80 of 135 microns. Lime and Cytec 5100 are added to each ball mill feed to maintain a pH of 11.0 in the cyclone overflow and to provide the primary collector for both copper and gold flotation. Lime addition rate is controlled using pH measured in each cyclone feed pump box. There will be an addition of Cytec 5100 to the #4 primary mill to ensure that the fresh surface created there has sufficient collector.

The recovery of the metal values from the Aranzazu ore will employ the existing equipment, which utilizes conventional crushing and grinding operations to liberate the minerals with flotation used to concentrate the metals into a saleable concentrate. The primary, secondary and tertiary crushing circuits have the demonstrated capacity to crush the expected throughput of 2,597 TPD of run of mine ore to a size of 80% passing 8 mm. This crush size is fine enough to allow the single stage ball mills and the regrind mill, converted to primary grinding, to grind the ore to a projected 80% passing 135 microns, operating with 92% availability for 365 operating days per year. This yields a throughput of 940,240 tonnes/year, and a daily rate of 2,597 TPD. During 2014 the plant operating utilization was 97% so it has been shown that this operation is capable of achieving a very high operating time.

The flotation section of the plant will use the existing conventional flotation ........