Mineralization throughout the Punitaqui-Ovalle district is related to hydrothermal activity and are considered broadly as epigenetic Cu+/- Au-Ag-Hg deposits and have been referred to as stratiform and mesothermal. The economic mineralization is controlled by channels of mineralization (feeders) into dilational structures and shear zones and is constituted by pyrite, chalcopyrite and bornite. In many deposits in the district copper and gold mineralization occur with magnetite and hematite which like other deposits in the region confirm them to be related to the Iron Oxide Copper Gold (IOCG) family of deposits.

The significant projects located within the concessions include the Cinabrio, San Andres, Dalmacia and Milagros Los Mantos projects. The Esperanza project has no significant work conducted.

Cinabrio
Cinabrio is an Iron Oxide Copper Gold (IOCG) type manto deposit. Mineralisation has a strike length of approximately 750m and the mineralisation is between 10 and 30 metres thick and is very continuous up to a depth of around 700 metres. The mineralisation of predominantly chalcoyprite and minor bornite and pyrite dips steeply to the east and occasionally faulted. Immediately to the south west is the San Andres property which is the faulted offset of the top of the Cinabrio orebody. San Andres is approximately 10 to 15 metres in thickness and additional exploration is required to define its depth limits.

Dalmacia
Based on existing information Dalmacia is located within a roof pendant of volcanic rocks with minor calcareous intercalations of the Agua Salada Complex. This volcano sedimentary complex is intruded by granites of the Illapel Batholith (105-130 Ma) located in a reverse fault.

Milagros and Los Mantos
The geology at Milagros and Los Mantos here contains thin layers of limestone, which appear to be lenticular. Where exposed the limestone layers are mostly about 2 meters thick, but in a few places they bulge out to a much greater thickness. They strike nearly north, and their dips range from 45° W. in the central part of the area, south of the Los Mantos mine, to approximately 90° in the northern part. The limestone has been metamorphosed in widely varying degree, some of it being only a little bleached, whereas some has been altered to a massive garnet rock. Lamprophyre dikes, only 1 or 2 meters thick, are continuous within the Los Mantos vein underground as well as in the granodiorite at the surface. Those seen underground all dip steeply west, but in the granodiorite at the surface some are flat lying and others are vertical. The principal intrusive rock is a typical biotite-hornblende granodiorite containing many dark inclusions. It contains a moderate quantity of quartz, rather abundant hornblende and biotite the latter partly altered to chlorite and epidote along cleavages and accessory sphene, magnetite, and apatite.

The outstanding structural feature of the district is a zone of faulting and minor shearing that was traced intermittently from the northern to the southern end of the área (1km distance and up to 50m wide and 450m depth) It is marked by pockets and streaks of a peculiar, fine-grained fault breccia, consisting of ground-up fragments of volcanic and sedimentary rocks, granodiorite, and of vein material.

The mineralisation can be considered as a vein shear system with copper as chalcopyrite and chalcocite, gold, silver and mercury as cinnabar and mercurian tetrahedrite.

In general mineralization occurs as impregnations and/or disseminations in all strata, affected by preexisting fractures and minor faults. The economic mineralization is controlled by feeders and includes chalcopyrite, bornite and the gangue includes pyrite, calcite and quartz. In the oxide and transition zones (nominally 40 to 60 metres depth but quite variable) malachite, azurite and chrysocolla and native copper are common. It is emphasized that the dominant mineralogy in the enrichment zones consists mainly of chalcocite, bornite and chalcopyrite. In greater depth, mineralization is estimated to contain primary sulphides (pyrite, chalcopyrite and bornite).

The property contains a mill that is permitted to operate at 3,000 t/d, fed by various sources near the property including: the Cinabrio mine; Dalamacia open pit mine (in development); the Dalmacia underground mine (in development); the Los Mantos open pit mine; and the Milagros underground mine.

All mining is performed by a contractor.

In some cases, larger units may be appropriate. For example, larger 8 yd³ scooptrams rather than the existing 6 yd³.

As the Cinabrio deposit deepens, the first real test for the equipment will be the haulage time from the bottom of the mine. This may prompt the evaluation of larger haulage trucks; the width of the ramp, at approximately 5.5 m, should be able to accommodate trucks as large as 50 t and still provide 2.0 m free space.

However, as all of the equipment is contractor-owned, such efficiencies are only relevant if the contract is structured to provide a lower cost to Minera Altos de Punitaqui (MAP).

Each mine has its own bolting standards which are based on the Bieniawski Rock Mass Rating (RMR), a typical industry standard. The RMR varies from 40 to 80, which corresponds to “poor” to “very good” ratings.

Splitsets are used throughout the mines in lengths of 1.8 m, 2.4 m and 3.0 m with mesh. A 1 to 2-inch layer of shotcrete is applied to fault zones.

Many of the headings underground are not bolted. In these zones the back was typically completely covered with half-barrels of the drillholes, a reliable indication of good ground conditions. The possibility of wedges should still be considered.

The Dalmacia open pit mine is designed for 6.9 m wide x 12 m high benches with face angles of 70° and an overall slope angle of 49°, as shown in Figure 24-1.

Waste dumps are designed for 9.6 m wide x 8 m high benches and assume repose angles of between 36° and 39°, resulting in overall slope angles of 23°.

Cinabrio Underground Mine
Operating since 2011, the Cinabrio Mine has been the largest producer at MAP.

The orebody dips at approximately 50° with thicknesses of between 20 m and 100 m extending from the top at 1,000 mASL to the current bottom at about 400 mASL.

Most of the mining levels are unbolted and the ground is solid and competent, with the exception of some fault zones, which are supported with splitsets and shotcrete.

Sublevel open stoping is employed with a 30 m vertical distance between levels. The stopes are mined using uphole drilling. A slot is developed from hangingwall to footwall across the width of the stope then parallel rings are blasted into the open void. All stopes are non-entry to personnel. Remote scooptrams are employed regularly for complete extraction. Haulage from the mine is accomplished using 30 t diesel haulage trucks.

Mining is completed without cemented, self-supporting backfill, and massive pillars are left for support that are continuous from hangingwall to footwall. All development waste is placed in completed stopes, offering confining support to the hangingwall through most, though not all, of the mined areas.

Dalmacia Underground Mine
The Dalmacia deposit is modeled as numerous discrete and discontinuous pods of mineralization.

The Dalmacia underground mine has one level completely developed at 315 mASL. It is currently laid out for sublevel open stoping using a 20 m sublevel spacing without backfill in a similar fashion to the Cinabrio mine.

Plans exist both for underground mining and surface mining of the deposit. As the topography is fairly hilly, an open pit plan would only recover the upper portion of the orebody and, if viable, continued extraction would be done using underground methods.

Dalmacia Surface Mine
As stated, plans exist for a “super pit” for the main Dalmacia deposit, which is currently developed on one level as an underground mine. However, there is a second discrete zone to the East of the underground mine, which is also called the Dalmacia open pit mine, but has the historical names Nova Galicia and Arco Iris.

The mine is currently operating under an exploration permit that allows for 3,000 Mt/d of total mining. The mine in the process of applying for a full mining permit that would allow 20,000 Mt/d. It is being excavated with 12 m high benches.

The strip ratio is currently estimated to be 3:1. More drilling is required to determine the extent of the numerous planned pits and which will merge into much larger pits. The pit will start with a heavier-thanaverage ratio of CuS to CuI.

Three waste dumps are planned for the pit, all within 1.5 km haulage distance.

Milagros Underground Mine
The Milagros mine is a historic gold mine in which the high grade core has been mined out, but the low grade fringe which housed the core remains, as demonstrated in Figure 24-10. The mined-out high grade core is represented in yellow and generally averages 3 m thickness. The lower grade (1 g/t cut-off) matrix is shown in orange and averages a much wider 18 m thickness.

The Los Mantos open pit is directly above and north of the Milagros mine.

The Los Mantos pit abuts both the processing plant and the tailings impoundments. A LOM plan will be impacted by these facilities, as it is unlikely to warrant relocating either.

Surface haulage from the outlying properties is accomplished using 20 to 25 tonne (t) highway trucks.

Crushing
Run-of-mine (ROM) mineralized rock is delivered to the coarse stockpile as separate material for evaluation and assaying prior to being blended through the plant. ROM mineralized rock is control discharged from the 50 t ROM bin by a grizzly feeder ahead of a 56” x 48” Nordberg C140 Jaw crusher. ROM fines at nominally minus 150 mm by-pass the jaw crusher and are conveyed with jaw product at nominal 200 mm to the secondary crusher.

The primary crushed product is screened on a 5 ft by 17 ft double deck rubber mesh screen with 75 mm gaps on the top deck and 32 mm gaps on the bottom deck. Undersize by-passes the Trio 66 standard cone crusher while the oversize passes to the Standard cone crusher with a closed-side setting (css) of nominal 25 mm.

The standard crusher discharge combines with the by-pass fines and is conveyed to the tertiary crushing circuit storage bin of nominal 300 t capacity for control discharge to the tertiary circuit.

Vibratory feeders control the feed to three 5 ft x 17 ft tertiary double deck screens with 20 mm top deck aperture and 14 mm bottom deck aperture for control of the final product to nominal 9 mm. Oversize from the tertiary screens feeds directly to three Trio 51 shorthead cone crushers prior to recycling in closed circuit back to the 300 t surge bin.

Fines from the tertiary screens at nominal 8 to 9 mm are conveyed to a 14,000 t fine mineralized rock stockpile.

Milling
The grinding circuit consists of two modules each consisting of a single stage 14 ft x 20 ft ball mill. Each mill is in closed circuit with a D26 cyclone system maintaining a closed circuit with the mill. Mill circuit product is sized at a P80 of 110 µm. Mineralized rock is delivered by a mechanical gate discharge to the ball mill over a weightometer to monitor the weight to the mill for metallurgical accounting.

The discharge from each of the 14 ft by 20 ft ball mills is pumped by an 8/6 unit to a two cyclone battery with 26” cyclones for classification of the mill product. Overflow gravitates to flotation, while the underflow as coarse oversize recycles back to the ball mill for further grinding.

Mill circuit number 1 contains steel liners in the grinding mill, while Mill No. 2 is equipped with polymet liners.

Three “old” (not used) ball mills also exist which are assumed to be the original plant. The mills are: 10.5 ft by 13 ft ball mill with discharge pumps and 15” cyclone classification. A 10 ft x 10 ft ball mill with discharge pumps and 15” cyclone classifier.

There is also an 8 ft x 12 ft Denver rod mill with discharge pumps. A mill support for a fourth mill (removed) exists between the two ball mills.

The plant is a conventional three stage crushing with single stage ball milling and bulk flotation to generate a concentrate of combined copper-gold with silver as a byproduct. It is then dewatered on site and trucked to either Glencore’s Chilean Altonorte smelter, or to the port, for dispatch to the market.

The property contains a mill that is permitted to operate at 3000 Mt/d, with an allowance to exceed the permitted capacity by an additional 20%, suggesting a maximum allowable milling rate of approximately 3,600 Mt/d.

Flotation
The flotation circuit consists of a rougher-scavenger circuit, with a three stage cleaner circuit to upgrade the copper to nominally 23% copper in the final concentrate. The gold content of the copper concentrate is totally dependent upon the mineralized rock mix utilized on the ROM pad.

Rougher Scavenger Flotation
The grinding circuit product is conditioned in two stages utilizing a 10 ft x 10 ft primary and an 11 ........