Overview
Status | Temporary Suspension |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Overhand Cut & Fill
- Longhole stoping
- Avoca
- Longitudinal retreat
- Room-and-pillar
- Cemented backfill
|
Processing |
- Carbon re-activation kiln
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
On February 19, 2020, the Company designated the Holt Complex as a non-core asset with plans to review options for maximizing value. In mid-March, the Company placed the Holloway Mine on care and maintenance, with no plans for a future resumption of operations. Effective April 2, 2020, the Company suspended operations at the Taylor Mine and Holt Mine and Mill as part of the Company’s response to the COVID-19 pandemic while the Company continued the strategic review of the Holt Complex assets involving the consideration of all options for the maximizing of value. On July 16, 2020, the Company announced that the suspension of operations at the Holt Complex was being extended until further notice.
The 100% owned Holt Mine Complex consists of three mines (Holt Mine, Holloway Mine and Taylor Mine) all feeding the Holt Mill for processing.
Beginning in Q1 2019, the Company began reporting production, cost and expenditure results for the Holt Complex as a reporting business segment. |
Latest News | Kirkland Lake Gold Extends Suspension of Operations at Holt Complex July 16, 2020 |
Source:
p. 1
St Andrew Goldfields Ltd. is a wholly-owned subsidiary of Kirkland Lake Gold Ltd.
February 8, 2022 – Agnico Eagle Mines Limited and Kirkland Lake Gold Ltd. are pleased to announce the successful completion of the previously announced merger of equals transaction (the “Merger”).
The combined company will continue as Agnico Eagle Mines Limited.
Deposit Type
- Carbonate replacement
- Vein / narrow vein
- Volcanic hosted
Summary:
At Holt-Holloway, the deposit is a mafic volcanic hosted where the gold mineralization is quite unlike the classical Superior province auriferous quartz vein systems resulting from deformed, extensional fracture arrays. Rather, it is associated with disseminated sulphides in altered rock, sometimes described as replacement mineralization. Mineralization typically consists of moderately to steeply dipping tabular zones of disseminated pyrite (generally less than 5 per cent per volume) and gold in intensely altered tholeiitic basalt, with variably developed microveinlet stockworks. The ore is gold rich (Au:Ag is greater than 5) and contains concentrations of arsenic. The mineralized zones occur in a variety of geological settings reflecting a variety of controls on the localization of the mineralization: along low-strain lithological contacts (Lightning, Blacktop and Lightning Deep zones at Holloway), along brittle and/or ductile faults (McDermott, Worvest and Mattawasaga zones), and as shallowly dipping discordant zones (Tousignant, South Zone and Zone 4) of which the South Zone (Holt) is spatially
coincident with an array of shallowly dipping syenitic dykes.
Mineralized zones are coincident with zones of intense albite-ankerite alteration of the host basalt, which, in turn, are partly fringed by sericite alteration haloes at Holloway and fringed by broader zones of calcite alteration. Disseminated specular hematite can be present within or outboard of mineralized zones.
Gold mineralization at the Holt and Holloway Mines is associated with replacement carbonate pyrite-albite-quartz alteration that overprints mafic volcanic rocks in, and adjacent to, D3-D4 high strain zones. The overprinting of multiple mineralization phases in the same area suggests that mineralization was long lived and spanned syntectonic deformation during exploitation of the same fluid channel ways.
The deposit types vary within the Taylor Mine Complex. The Shaft Deposit furthest east is identified as a Felsic intrusive related model, with a contemporaneous green carbonate association. Feldspar porphyritic intrusions are the host to high grade gold veins and high concentrations of disseminated sulphides (generally pyrite).
Within the West Porphyry Deposit, free gold is found within quartz dominant extension veins and veinlets, cross-cutting the foliation present within the chrome-mica and chloritic altered ultramafic rock. This unit can be up to 20 m thick as the true extent of the veins are not fully understood. Additionally, the main shear (interpreted to be the contact of the PDF between the mafic and sediment contact, is host to a quartz brecciated shear vein, which can be up to 2m thick. Altered mafic units consisting of high concentrations of disseminated sulphides are also host to gold mineralization.
The Taylor Mineralization is in close proximity, within the hanging wall, to the PDF. Over a strike length of 2.3 kilometres there are three mineralization zones that have been identified. From east to west these are:
- The Shaft Deposit, with gold mineralization associated with felsic intrusive rocks.
- The West Porphyry Deposit (WPZ), a system of stacked lenses, with the gold mineralization associated with felsic intrusive and altered mafic-ultramafic rocks (Green Quartz Carbonate).
- The Shoot Deposit, with gold mineralization hosted by argillaceous metasedimentary rocks within a package of green quartz carbonate. Gold commonly occurs as relatively coarse-sized free gold in quartz, but also occurs as fine particles, which may be intimately associated with sulphides (particularly pyrite and locally, arsenopyrite) both in quartz-carbonate veins or in surrounding altered host rocks.
Mining Methods
- Overhand Cut & Fill
- Longhole stoping
- Avoca
- Longitudinal retreat
- Room-and-pillar
- Cemented backfill
Summary:
The primary stoping method at the Holt Mine is mechanised long hole drilling and blasting within the mining blocks with rail transport to the shaft ore passes. The spacing between sublevels for long hole stoping varies between 20 m and 17 m, depending on the dip of the ore. Mechanized long hole stoping is planned to be used in all zones at the Holt mine. “Drift and pillar” stoping may be needed in some areas where the ore is too shallow and not amenable to long hole methods. Drilling is performed with tophammer drills, with hole sizes ranging from 64 mm to 76 mm in diameter.
The Tousignant Zone is planned to be mined with modified room and pillar.
Zone 4 is accessed by mechanised equipment via ramps and sublevels connected to two main rail haulage levels 925 and 1075. Zone 4 is divided into two mining blocks: the upper mining block represents the stopes reporting to the 925 haulage level and the lower mining block represents the stopes reporting to the 1075 haulage level. The use of both haulage levels provides increased flexibility to the overall Holt mine plan.
The mine extraction sequence for Zone 4 is using a primary-secondary stoping arrangement with cemented rock fill being used in the primary stopes. Strike length is set at 15 m for the primary stopes and 20 m for the secondary stopes. Sublevels in Zone 4 are spaced 17 m apart due to the shallow dipping nature of the ore within the zone. The current mine plan includes stopes being mined using up holes, with the remainder of the stopes being mined using down holes. This method of combining up and down hole configurations helps minimize hole length and increases accuracy of hole drilling.
Zone 6 is planned to be accessed via a ramp system and sublevels spaced at 20 m intervals for “conventional long hole” stoping. Accesses will be connected to haulage levels on 925, 775 and 1075 via drifts and ore passes.
The mine extraction sequence for Zone 6 is using a primary-secondary stoping arrangement with cemented rock fill being used in the primary stopes. The strike length is set at 20 m for all stopes (primary and secondary). The delivery of cemented rock fill to the upper portion of the zone will be initiated from the 435 level cement plant. From here a slurry hole has been drilled down to 775 level backfill system, which will deliver cement to the lower portion of the zone. Secondary stopes are planned to be filled with rock fill produced during development of the ramp and footwall drifts.
Upper Zone 6 is currently transitioning to the Avoca mining method for the extraction of its reserves. If proven to be viable, it is expected that this mining method will be incorporated into the lower portions of the zone.
Ore will report to one of three rail haulage levels (775, 925, or 1075 level, depending on the stopes elevation) via an internal ore pass system. Ore will then be trammed on rail to the shaft ore pass system.
Zone 7 is planned to be accessed via a ramp system and sublevels spaced at 20 m intervals for open stoping. Accesses will be connected to the 435 haulage level via drifts and ore passes.
The mine extraction sequence for Zone 7 is using a primary-secondary stoping arrangement similarly to Zone 6. Cemented rock fill being will be used in the primary stopes and secondary stopes will be filled with rock fill produced during development of the ramp and footwall drifts. The strike length is set at 20 m for all stopes (primary and secondary). The delivery of cemented rock fill to the upper portion of the zone will be initiated from the 435 level cement plant.
V-93 is a steeply dipping ore body located to the south of Zone 4 and above 775 level on the west end of the mine. The mineral reserves for V-93 are estimated at 100,184 tonnes grading at 4.59 g/t.
V-93 Zone is planned to be accessed from a ramp system connected to the 775 level with sublevels spaced at 20 m intervals. The zone is planned to be mined using longitudinal long hole retreat method. The stopes will be backfilled using cemented rock fill from the planned 775 level backfill system. Rock fill will be provided from development headings or could be trammed from Zone 6 development when available.
Taylor Property.
The Taylor Mine consists of a few zones: the Shoot Deposit (located on the west side of the property), the WPZ, the East Porphyry Deposit and the Shaft Deposit (located on the east side of the property), development and operating activities are currently focused on the WPZ; it extends vertically about 600 m and is mostly open at depth. The deposit is accessed via a ramp and mined by overhand cut and fill method (for shallow dip ore zones) or longhole stoping (where the ore zones dip at an angle greater than 45°). Ore and waste are trucked to surface where the ore is loaded into surface trucks for haulage to the Holt mill and the waste is stockpiled on designated surface areas. Ventilation is forced underground via the shaft opening. Auxiliary fans are installed, as required, for adequate airflow distribution. Underground water is pumped to a collector pond on surface prior to be discharged in the environment.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
|
|
|
1
|
SAG mill
|
.......................
|
|
3400 HP
|
1
|
Ball mill
|
.......................
|
|
1650 HP
|
1
|
Ball mill
|
.......................
|
|
1250 HP
|
1
|
Summary:
Surface ore storage is a total of 4,900 t in three silos, the Holt headframe bin (900 t) and two other separate storage bins (1,000 t and 3,000 t). Ore can be delivered to the mill from the Holt Mine by conveyor or from a separate surface dump that enters a 100 tonne hopper, and then can be fed to either of the two storage bins.
The grinding circuit consists of a 5 m diameter by 6.1 m long Allis Chalmers ball mill, converted to a SAG mill, a 4 m diameter by 5.5 m long Allis Chalmers ball mill and a 3.6 m diameter by 4.9 m long tertiary ball mill, all operating in series and in closed circuit. The details of the grinding circuit are shown below in Table 16-1. The grinding circuit is controlled by a Wonderware system and Modicom programmable logic.
Processing
- Carbon re-activation kiln
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The Holt Mill was constructed in 1988 and was originally designed for a throughput of 1,360 tpd. Expansions in 1988 and 2001 increased the throughput to 2,500 tpd and 3,000 tpd, respectively.
The primary cyclone cluster consists of six 381 mm (15”) Krebs D15B cyclones. A secondary cyclone cluster consists of twelve 254 mm (10”) Krebs gMAX cyclones with an Outokumpu PSI-200 online analyzer. The secondary cyclone cluster feeds a 27 m (90 ft) Eimco thickener. The thickener underflow feeds a pre-aeration tank, which gravity feeds five carbon-in-leach (CIL) tanks in series. The tank system is conventional gravity flow for slurry with counter-current carbon advancement
Precious metal stripping is performed in batch operations, advancing 2.7 t of loaded carbon through a 1.2 m by 2.4 m (4 ft x 8ft) Simplicity screen. Carbon is transferred to an adsorption column where a Zadra process is utilized as the gold elution method. Barren solution is circulated through two shell ........

Recoveries & Grades:
Commodity | Parameter | 2020 | 2019 | 2018 | 2016 |
Gold
|
Recovery Rate, %
| ......  | ......  | 94.7 | 93.8 |
Gold
|
Head Grade, g/t
| ......  | ......  | 4.9 | 5.2 |
Production:
Commodity | Units | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
Gold
|
koz
| ......  | ......  | 127 | 117 | 129 | 107 |
All production numbers are expressed as metal in doré.
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Operational Metrics:
Metrics | 2020 | 2019 | 2018 | 2017 | 2016 |
Tonnes milled
| ......  | 853,528 t | 860,023 t | 754,990 t | 820,055 t |
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Reserves at December 31, 2020:
Mineral Resources for Holt Complex were estimated at the following cut-off grades: Holt Mine: 2.8 g/t, with the exceptions noted below; Holt Near-Surface Zones: 2.5 g/t (Tousignant, Cascade, North Mattawasaga Pit); Holloway Mine: 2.8 g/t, with the exception of the Deep Thunder (2.7g/t) and Canamax (2.5 g/t); Taylor Mine: 2.6 g/t; Hislop Property: 2.2 g/t.
Category | Tonnage | Commodity | Grade | Contained Metal |
Measured & Indicated
|
11,690 kt
|
Gold
|
4.5 g/t
|
1,699 koz
|
Inferred
|
9,097 kt
|
Gold
|
4.5 g/t
|
1,310 koz
|
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