Overview
Stage | Production |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Gravity separation
- Centrifugal concentrator
- Vacuum filtration
- Dewatering
- Hydrochloric acid (reagent)
- Carbon re-activation kiln
- Counter current decantation (CCD)
- Inline Leach Reactor (ILR)
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- AARL elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 10 years (as of Jan 1, 2021) |
Latest News | Endeavour Achieves Record Annual Discoveries With Addition of 3.0Moz of M&I and 0.9Moz of Inferred Resources January 17, 2022 |
Source:
p. 9, 39
Endeavour owns 85% of the Ity mine, except 90% owned Le Plaque deposit, with the Government of Cote d'Ivoire owning 10% and SODEMI (a government-owned mining company) owning the remaining 5%.
Summary:
Ity is located in the Lower Proterozoic Birimian Formation of the Toulépleu-Ity klippe. The Toulépleu-Ity klippe is a small remnant of Birimian within the older Archean portion of the West African Craton. The Ity area is characterized by a series of granodioritic intrusions into a sedimentary sequence of volcano- sediments and carbonates with a general NE-SW strike. The volcanic rocks are generally tuffaceous with chemistry tha ranges from basic to acidic. All formations have been subjected to regional metamorphism.
The deposits of Ity are classified as skarn or typical shear-hosted greenstone deposits. The skarns developed at the contacts of a central northeast trending lensoidal shaped body of granodiorite intrusives with the carbonate units on both northwest and southeast contacts. The Ity, Ity Flat, Tontouo and Walter deposits are hosted along the southeastern contact, whilst Flotouo, Zia and ZiaNE are hosted along the northwestern contact. Bakatouo deposit is interpreted as being hosted by the northeast continuation of the carbonate units, whilst the Colline Sud skarn deposit represents the southwest continuation. The skarns are characterized by epidote, carbonate, diopside, chlorite, tremolite, magnetite and garnet with gold associated with pyrite and chalcopyrite. The Teckraie and Verse Ouest deposits are rock dumps of the now depleted Flotouo (skarn) open pit and sit on top of weathered granodiorite. Aires consists of the decommissioned heap leach pads from the historic operation of the mine.
The in-situ deposits of Daapleu and Gbeitouo share many characteristics with typical shear zone deposits known in Birimian greenstone belts of West Africa. The deposits are associated with a major regional, NE-trending shear zone but are developed on secondary structures. The Daapleu deposit is characterized by the presence of a "rhyolitic" intrusive surrounded by a package of volcano-sediments. The "rhyolite" is locally called "daaplite". The "daaplite" is strongly altered and sheared and, at the contact, both lithologies have been affected by phyllic style hydrothermal alteration (sericite-silica-pyrite). Gold mineralization is mesothermal and occurs as fine-grained free gold within foliation and silicificied strips, associated with arsenopyrite and to a lesser extent with pyrite and silvercopper-antimony sulfosalts. The Gbeitouo deposit is hosted within volcano-sediments with variable intensity silicasericite-pyrite alteration. Minor pyrrhotite, galena and sphalerite have been noted in association with auriferous pyrite in proximal mineralized shears.
Le Plaque was discovered in 2017 and is a shear hosted deposit located mainly at the contact between granodiorite and diorite intrusions, developing a skarn unit with the country rocks. The geology of Le Plaque consists of a granodiorite batholith intruded into a sequence of Birimian meta-volcano-sediments, dominantly metasediments (impure marbles, metasiltstones and sandstones) to the west, and a belt of mafic metavolcanics to the east. Several generations of diorite and microdiorite bodies of variable thickness occur within the metasediments as sheeted sills and dykes, including some which are cutting through or bordering the granodiorite. The metasediments and magmatic rocks have been affected by skarn alteration forming exoskarn and endoskarn, although this event appears not associated with gold, contrary to general Ity style mineralization, whose mineral paragenesis bears significant copper.
The mineralization in Le Plaque is broadly associated with few metres-thick ductile and brittle ductile shears with quartz veining, silica-sericite alteration and locally massive sulfidic seams (pyrite, with subordinate sphalerite, minor chalcopyrite and local trace of galena and pyrrhotite). There is no visible gold on core, even within the highestgrade intercepts, and almost no arsenopyrite. The presence of sphalerite, strong silicification and quartz veining usually correlates very well with the best grades. The anastomosed shearing network is usually well developed in the outer shell of the granodiorite, within the granodiorite and diorite units, and to a lesser extent within the skarn host rocks themselves.
Summary:
The selected mining approach is conventional open pit excavator-truck operation with the production unit operations (drilling, blasting, loading, hauling and dumping) carried out by mining contractors SFTP and SMS, with small earth works being done by Sopremi. The mining fleet consists of larger capacity 90 t dump trucks and 120 t class backhoe excavators. The 40 t articulated dump trucks are still utilized depending on pit and dump conditions, in particular, during the wet season. Ore and waste production rates are monitored, and material reconciliations are carried out continuously for the pit areas in production.
The production, drilling and blasting operations are carried out on 10 m benches. A half bench height (flitch) of 2.5 m is mined in ore to achieve a high degree of selectivity in loading and hauling operations. The highly weathered zone (clays and laterites) and transitional zone with a density below 2.0 t/m3 are amenable to free digging. Emulsion is used in both wet and dry blasting for efficiency.
The production, drilling and blasting operations are carried out on 10 m benches. A half bench height (flitch) of 2.5 m is mined in ore to achieve a high degree of selectivity in loading and hauling operations. The highly weathered zone (clays and laterites) and transitional zone with a density below 2.0 t/m3 are amenable to free digging. Emulsion is used in both wet and dry blasting for efficiency.
Grade control drilling is carried out by a drilling contractor and the samples are tested in the onsite laboratory. Sampling commences with grade control drilling ahead of the mining front, aimed at assisting the short to medium term mine planning process. The grade control is based on 138 mm diameter RC drilling and sampling practice. A grade control pattern of 12.5 m x 6 m is used for 36 m deep holes (30 m vertical) and 1.0 m vertical sampling intervals. The holes are angled 50-55 degrees from the hanging wall side of the ore zones to provide a good intersection with the mineralized structures.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
1.6m x 1.2m
|
|
1
|
Pebble crusher
|
|
|
250 kW
|
1
|
SAG mill
|
|
8.5m x 4.35m
|
6000 kW
|
1
|
Ball mill
|
|
6.1m x 9.05m
|
6000 kW
|
1
|
Summary:
A grizzly is fitted to the RoM bin to protect the downstream equipment from oversize material. A mobile rock breaker is utilised to break oversize rocks. RoM ore is drawn from the RoM bin at a controlled rate by an apron feeder which discharges over a vibrating grizzly. The grizzly oversize reports to the jaw crusher. The grizzly undersize enables a portion of the feed to bypass the jaw crusher. Both products discharge onto the surge bin feed conveyor. A weightometer on the surge bin feed conveyor measures crusher product. A tramp metal magnet has been ordered and will be installed on this conveyor in 2020. This will be placed ahead of the weightometer to remove any coarse metal to protect the conveyor belts.
Coarse spillage in the crusher area is cleaned up by FEL and transported to the RoM pad for drying or fed directly to the primary crusher. Water sprays are installed for dust suppression as required. A 10t hoist is provided over the jaw crusher to facilitate regular maintenance.
The crusher output is set to outpace the mill feed setpoint. The surge bin feed conveyor discharges onto a 500t live capacity surge bin, which provides 30 minutes feed to the milling circuit to allow for regular maintenance on the crusher. The surge bin feed conveyor discharges into a fixed point in the surge bin which has a partition wall enabling the overflow to rill into a second smaller compartment in the bin and on to a coarse ore stockpile feed conveyor. The coarse ore stockpile has been increased in size in early 2020 to provide 40,000 tonne capacity. Water sprays are installed for dust suppression as required.
Primary ore is reclaimed from the surge bin via a single variable speed apron feeder. In addition, ore can be reclaimed via FEL from the coarse ore stockpile in the event of an extended crusher shutdown. Each of the feeding options is rated to reclaim at the full mill feed rate, though may be run simultaneously to ensure a regular feed to the SAG mill and to compensate for different material types or hang-ups in the surge bin. The surge bin is fitted with air blasters to reduce such hang-ups.
The grinding circuit consists of an SABC circuit with hydrocyclones.
The SAG mill is 8.50m dia x 4.35m EGL complete with a 6,000kW variable speed drive and operates at up to a maximum 18% volumetric ball loading. Variable speed control of the mill, accomplished through a Variable Voltage Variable Frequency (“VVVF”) system, provides flexibility for processing of the various ore types. A speed range of 60% to 80% critical speed is available, though the mill can be slowed down further for softer ore types. SAG mill steel ball grinding media is typically 100mm to 125mm diameter.
The SAG mill product discharges into a vibrating single deck heavy duty pebble dewatering screen fitted with a nominal 15mm aperture polyurethane screen deck. Undersize from the screen feeds the mill discharge hopper. The oversize pebbles (nominally +15mm) are transferred via a transfer conveyor to a pebble crusher feed bin ahead of a single 250kW pebble crusher.
A single stage of tramp metal removal via a self-cleaning belt magnet across the pebble transfer conveyor is used to remove mill balls and any other magnetic steel debris discharged from the SAG mill. Tramp metal is deposited in a bunker area with concrete walls on three sides which provides access for metal removal and protection to personnel in the area. Metal detection provides a final level of protection against metal entering the pebble crusher. Upon detection of metal, the flop gate at the head of the transfer conveyor is activated and the ore stream can bypass the pebble crusher surge bin for a predetermined period and is deposited directly onto the SAG mill feed conveyor.
The pebble crusher surge bin can hold approximately 25 minutes capacity to improve steady state operation of the pebble crusher. This design allows for use of a single pebble crusher to meet the expected pebble load as the competence of the ore is moderate.
A variable speed vibrating feeder transfers the pebbles at a controlled rate from the surge bin into the pebble crusher. Pebbles are crushed from a nominal top size of 75mm to a P80 of approximately 12mm. The pebble crusher operates at a closed side setting of 11mm, depending on ore competency, moisture content and crusher power draw. Product from the pebble crusher is transferred to the SAG mill feed conveyor. An overhead hoist is provided to facilitate crusher maintenance.
A 6.10m dia x 9.05 m EGL overflow ball mill complete with a 6,000kW variable speed drive operates at up to 35% volumetric loading of steel balls. Variable speed control of the mill, accomplished through a VVVF system, provides greater control during the plant start-up or shutdown phase. Product size from the grinding circuit is 80% passing 75µm on 100% primary ore. The ball mill is set at a fixed speed operating at 100% of the critical speed.
Ball mill grinding media is 50mm diameter balls and is stored in bags adjacent to the grinding area. Grinding media is loaded via a kibble and hoist, into the ball mill feed chute.
Processing
- Gravity separation
- Centrifugal concentrator
- Vacuum filtration
- Dewatering
- Hydrochloric acid (reagent)
- Carbon re-activation kiln
- Counter current decantation (CCD)
- Inline Leach Reactor (ILR)
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- AARL elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
Mining and stacking activities for the heap leach operation ceased in mid-December 2018 as the focus shifted to commissioning and ramping up the CIL plant.
The Ity Carbon-In-Leach Plant (“Ity CIL Plant”) processes a range of ore types (oxide, transition and fresh) with variable ore characteristics, gold grades and metallurgical treatment requirements. The primary ores (Fresh) are significantly more competent than the oxide ores.
Processing trials conducted in November 2019 and February 2020 indicated that low grade (<1.2g/t) primary ore can achieve a recovery of 76%. Further trials and testwork is underway to determine whether increased recoveries can be achieved from the high-grade portion of the Daapleu primary ore.
By contrast to some of the primary ore types, oxide ores are free milling with leach extraction of 90% to 96%. Mill feed requirements are supplemented successively with oxide material from Ity Flat, Mont Ity, Gbeitouo, Walter and Zia NE.
Recoveries & Grades:
Commodity | Parameter | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
Gold
|
Recovery Rate, %
| ......  | ......  | ......  | 81 | 83 | 93 | 83 |
Gold
|
Head Grade, g/t
| ......  | ......  | ......  | 2.49 | 1.85 | 2.2 | 2.56 |
Production:
Commodity | Units | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
Gold
|
koz
| ...... ^ | ......  | ......  | ......  | 85 | 59 | 76 |
All production numbers are expressed as metal in doré.
^ Guidance / Forecast.
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Operational Metrics:
Metrics | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
Total tonnes mined
| ......  | ......  | 14,053 kt | 4,028 kt | 6,647 kt | 6,102 kt |
Ore tonnes mined
| ......  | ......  | 5,733 kt | 1,127 kt | 1,410 kt | 1,186 kt |
Waste
| ......  | ......  | 8,320 kt | 2,901 kt | 5,237 kt | 4,916 kt |
Tonnes milled
| ......  | ......  | 3,693 kt | 1,307 kt | 1,194 kt | 1,173 kt |
Stripping / waste ratio
| ......  | ......  | 1.45 | 2.58 | 3.71 | 4.15 |
Annual processing capacity
| ......  | ......  | 5 Mt | | | |
Annual processing rate
| ......  | ......  | | 950 kt | 950 kt | 950 kt |
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Reserves at December 31, 2021:
Cut-off grades for the resources are as follows: oxide at 0.50g/t Au except ZiaNE which is at 0.30g/t Au.
Cut-off grades for the reserves are as follows: oxide: 0.40g/t Au to 0.50g/t Au; transitional: 0.40g/t Au to 0.80g/t Au; fresh: 0.40g/t Au to 0.80g/t Au.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
11.9 Mt
|
Gold
|
0.89 g/t
|
338 koz
|
Probable
|
51.2 Mt
|
Gold
|
1.61 g/t
|
2,641 koz
|
Proven & Probable
|
63 Mt
|
Gold
|
1.47 g/t
|
2,979 koz
|
Measured
|
12.1 Mt
|
Gold
|
0.88 g/t
|
344 koz
|
Indicated
|
77.3 Mt
|
Gold
|
1.66 g/t
|
4,131 koz
|
Measured & Indicated
|
89.5 Mt
|
Gold
|
1.56 g/t
|
4,475 koz
|
Inferred
|
27.1 Mt
|
Gold
|
1.47 g/t
|
1,279 koz
|
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