The mineral deposits of the Colquijirca district belong to a member of the family of porphyry copper (Cu) related deposits known as Cordilleran deposits. These types of deposits, which are generally formed in the upper parts of a porphyry Cu, are fundamentally characterized by prominent zoning with internal parts that are dominated by Cu and external zones where Zn, Pb and Ag are the main economically-interesting elements. In the case of the Colquijirca district, and specifically the area between the Marcapunta Norte and Colquijirca sectors, such zoning generally consists of three zones, which mineralogically consist mainly of enargite in the internal parts; chalcopyrite in the intermediate parts; and sphalerite and galena in the external parts (El Brocal, 2021).

Due to the advance of stoping over the years, the Colquijirca deposit is currently exposed, which facilitates the geological identification of the Tertiary basin. Asymmetric anticlines and synclines composed of carbonate and detrital rocks, attributed to the Eocene-Oligocene Calera Formation, can be found and considered as the host of mineralization. The deposit also presents volcano-clastic intercalations (ash tuffs), which is evidence of volcanic activity that was contemporaneous to sedimentation. In addition, with the review of 5 drillholes, the Shuco conglomerate sequence of the upper Eocene has been identified in depth, which underlies Lower Calera and overlies in depositional contact with the Mitú sa ........

El Brocal mining operations are developed at open pit and underground. In turn, these are distributed in the following sectors:

i. Open pit operations:
1.Tajo Norte
2.Tajo Sur

ii. Underground operations
1.Marcapunta Norte
2.Marcapunta Centro
3.Marcapunta Sureste
4.Marcapunta Suroeste
5.Marcapunta Sur

The underground mining methods are Sub Level Stopping with cemented backfill and Room and Pillar with long holes. The pillars left in the ground are chain pillars that run along the entire mining direction and cover the mantle’s extension.
This method varies depending on the mining sector:
- North Sector: the stope is 8 m wide, 28 m high, and length varies between 50 to 100 m; the pillar width has been set at 6 m.
- South Sector, which includes the Southwest and Southeast Zone: the stope is 14 m wide, 28 m high, and the length varies between 50 and 100 m, with a pillar width of 6 m.

The following design parameters have been considered for the open pit operation:
- Bench height: 6 m.
- Berm width: variable between 5 and 8 m.
- Ramp width: considering equipment width, safety distances, and safety berm, the open pit have ramp widths of 12 m with a 10% slope.
- Optimum turning radius according to the equipment fleet is 6.4 m.
- Minimum loading width considering the excavator and the minimum spaces to carry out operational activities is 20 m. However, one excavator is ........

Plant 1 – Crushing Stage
Dump trucks deliver fresh ore to a coarse ore bin, which has a capacity of 100 tonnes and is equipped with a rock breaker as well as a stationary 20” opening grizzly. The grizzly’s passing size directly feeds a 47” x 33” jaw crusher operating with a 4” close side setting. The crusher discharge is conveyed to a primary 8’ x 20’ double-deck classification vibrating screen whose passing ½” stream becomes the final product from the crushing plant that is conveyed to a stockpile. The coarse stream from the primary screen feeds a secondary closed-circuit crushing-classification stage consisting of a secondary cone crusher operating with a close-side setting of 47 mm and a secondary doubledeck vibrating screen with a ½” passing size. A fraction of the secondary vibrating screen’s coarse stream feeds a tertiary cone crusher operating in open circuit with a close-side setting of 13mm. Alternatively, the secondary screen’s coarse fraction feeds a second tertiary cone crusher with a close-side setting of 10mm operating in open circuit. Product from both tertiary cone crushers becomes final product from the crushing plant that is conveyed to the stockpile.

The crushing plant’s final product sizing approximately P80= ½” is stored on two covered stockpiles of 6,000 tonnes and 2,000 tonnes each.

Plant 1 – Grinding & Classification
The grinding and classification stage consists of primary grinding in an open circuit followed by a classification stage, where hydrocyclones feed the coarse fraction to a secondary grinding stage that operates in a close-circuit with a multi-deck vibrating screen. A fine ore reclaim system feeds the primary grinding stage, which consists of a 7” x 12” and 550 HP single rod mill operating in open circuit. The rod mill product feeds a hydrocyclone classification stage. The hydrocyclone’s coarse fraction feeds the secondary ball mill consisting of a 16.5” x 23’ and 400 HP ball mill. Ball mill discharge along with hydrocyclones fines stream feeds six multi-deck (5 decks) vibrating screens. The screen’s passing (fine fraction) fraction becomes final grinding product and feeds the flotation stage. The screen’s coarse fraction is returned to the ball mill.

Plant 2 – Crushing, Washing & Classification Stage
Dump trucks deliver material to a coarse ore bin of 300 tonnes capacity equipped with a rock breaker and a stationary grizzly. The grizzly’s passing size directly feeds a roller crusher with 536 hp. The crusher discharge is conveyed to a washing stage consisting of a rotary washing trommel of 3.6 m diameter and 12 m long that discharges onto two doubledeck 10’ x 24’ banana screens operating in series (primary and secondary). Oversize from the primary banana screen feeds a secondary crushing stage operating in open circuit and consisting of a 500 tonnes capacity hopper feeding two parallel gyratory crushers. Discharge from the secondary crushers joins the oversize from the secondary banana screen to feed a tertiary crushing stage consisting of a 400 tonnes hopper feeding a high pressure grinding rolls unit (HPGR). Discharge from the HPGR feeds a single 15’ x 26’ banana screen whose passing stream become final product from the crushing plant that is conveyed to a fines stockpile (overall coarse fraction). The coarse stream from the tertiary banana screen is recirculated back to the tertiary crushing stage.

Passing stream from the secondary banana screen feeds a Four-stage classification plant. The first stage consist of a single primary hydrocyclone whose underflow feeds the secondary classification stage using a multi-deck high frequency vibrating screen. The fines fraction from the primary and secondary stage feed the tertiary stage consisting of 22 hydrocylones. Overflow stream (fines) from the tertiary stage feed the quaternary stage consisting of 16 hydrocyclones. The coarse stream from the secondary stage feeds the fines stockpile. The underflow stream from the tertiary stage feeds primary grinding stage. The underflow from the quaternary stage feeds the fines flotation plant. The overflow stream from the quaternary stage feed a 20 m diameter clarifier whose discharge is split between the fines flotation plants and the ultrafines flotation plant.

Plant 2 – Grinding
The coarse fraction from the washing, crushing and classification stage are stored in a 50,000 tonnes capacity stock pile. Ore is reclaimed from the stockpile using a front-end loader to feed a hopper that subsequenlty feeds the primary grinding stage. The primary grinding stage consists of two ball mills operating in parallel; the first unit is a 9.5’ x 14’ and 600 kW and the second unit is a 20’ x 30’ and 6500 kW. Both ball mills operate in close-circuit with 10 units of a high frequency multi-deck vibrating screen. The passing stream from the classification screens feeds the conditioning tank to the flotation stage.

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