Overview
Status | Temporary Suspension |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Drift & Fill
- Overhand Cut & Fill
- Longhole stoping
- Cemented backfill
|
Processing |
- Agitated tank (VAT) leaching
- Carbon in leach (CIL)
- Elution
- Carbon adsorption-desorption-recovery (ADR)
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 2020 |
July 07, 2020 - The Holloway Mine, a component of Holt Complex, was placed on care and maintenance in March 2020 with no plans for a resumption of operations. The remainder of the Holt Complex was placed on temporary suspension effective April 2, 2020 as part of the Company’s COVID-19 response. The Complex remained on temporary suspension as at June 30, 2020. |
Source:
p. 21, 23
St Andrew is a wholly-owned subsidiary of the Company.
Deposit Type
- Porphyry
- Vein / narrow vein
Summary:
Numerous gold deposits occur in the vicinity of the PDF (Porcupine-Destor Fault Zone) and related structures such as the Pipestone Fault. These include the major mines of the Timmins camp (Dome, Hollinger, McIntyre, and Pamour).
Some of the PDF gold deposits extend from surface to over 1,000 m below surface, and some are blind deposits, in that they do not reach bedrock surface. The top of the Holloway deposit (i.e. the Lightning Zone), for example, is over 240 m below surface.
The following description of potential gold deposit types on the SAS Timmins area claims is from Reid (2003). Deposit types and exploration models can generally be characterized as one of three main types, although they tend to merge with each other at times. The deposit types may have more to do with the different host rocks than a genetic difference. Proximity to the main break(s), associated splays, presence of hydrothermal alteration, Timiskaming sediments or high level porphyries are common to all. The three main types are as follows:
- Green Carbonate Hosted.
- Felsic Intrusive Related: Ronnoco, Pominex, parts of the Taylor Shaft and Hislop are examples of this type. The intrusive rocks vary from feldspar (plus or minus quartz) porphyry in the west to more syenitic in the east. Mineralization is characterized by both cross cutting to stockwork quartz veins, disseminated sulphides and/or contact skarns or hornfels, depending on host rock. Carbonate alteration is still quite common in the host rocks with silica, sericite, and hematite more within the intrusive.
- Mafic Volcanic Hosted.
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.
The Shaft Deposit was explored underground in 1986 and 1987 via a 172 m shaft and three levels and again in 2006 via a surface ramp, which gave access to these levels.
The molybdenite-graphite-associated mineralization comprises two small lenses extending from surface to a depth of 30 to 40 m. One has a strike length of 60 m and is approximately 9 m thick; the other has a strike length of 18 m and is approximately 11 m thick. Both occur as a zone of quartz veinlets with black molybdenite and graphite fracture filling within a flat lying porphyry dike.
The pyrite-altered porphyry is located 45 m to 120 m below surface and has a strike length of approximately 150 m. Horizontal width varies from 3 m to 18 m and the zone dips 50 degrees to the southeast. The zone is hosted in a brecciated, albite porphyry characterized by 10% to 30% pyrite and, to a lesser extent, red fluorapatite (5%).
The WPZ has been interpreted as a series of stacked and en échelon lenses, which contain a locus of deformation, alteration, quartz veining, and gold mineralization. For this study a total of nine lenses have been defined. The lenses are stacked with an offset to the south west and a vertical separation of about 50 m. The lenses strike approximately 060° to 070°, dip approximately 30° to 50° to the south and are locally irregular in shape (although follow similar shape patterns from lens to lens). In the lower lenses, there appears to be gold enrichment related to a minor flexure in the footwall of the alteration zone with the underlying ultramafic volcanics. This flexure is approximately parallel to another potential structure that marks the down-dip extent of the concentrated gold mineralization.
Gold mineralization with the WPZ occurs in high grade intercepts as relatively coarse free gold in quartz, which tends to have irregular distribution, and as lower grade intercepts, which are interpreted be resultant from fine grained gold, perhaps more evenly distributed and associated with disseminated pyrite. The shape of each goldbearing lens was very broadly interpreted based on structure, alteration, sulphide mineralization and gold grade. Rock type was used to a lesser extent, as it was determined that the gold mineralization is more related to geologic structures that transect lithological boundaries.
The Shoot Zone consists of a single, regularly shaped, moderately dipping tabular body which strikes approximately 060° to 070° and dips 40° to 50° to the south. The zone has a strike length of about 350 m and has been traced from surface to a vertical depth of 350 m. The zone is controlled by a metasedimentary unit which includes greywacke and argillite. This unit hosts gold bearing quartz carbonate veins. The unit is thickest near surface averaging about 13 m and thins down dip and to the west.
Mining Methods
- Drift & Fill
- Overhand Cut & Fill
- Longhole stoping
- Cemented backfill
Summary:
The Taylor Mine consists of a few zones: the Shoot Deposit (located on the west side of the property), the West Porphyry Deposit (WPZ), the East Porphyry Deposit and the Shaft Deposit (located on the east side of the property).
The WPZ extend vertically about 600 m and is mostly open at depth. The WPZ 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.
Overhand Cut and Fill (OC&F) and Drift and Fill (D&F) were selected as the most suitable mining methods:
- Where the ore is dipping at less than 45° and the ore horizontal width is narrower than 10 m, OC&F is the method of choice;
- Where the ore is dipping at less than 45° and the ore horizontal width exceeds 10 m, D&F will be the method of choice.
Where the ore is dipping at more than 45°, longhole mining will be the method of choice, requiring minimum mining width of 3 m. Waste rock generated by development activities is the source of backfill (whether cemented or not).
Upon examination of the mining shapes, the geologist applied a dilution factor varying from approximately 10% to 50% and a dilution grade ranging from approximately 0.5 g/t to 1.0 g/t. Mining extraction varied from approximately 90% to 95%, based on the mining method.
An average mining rate of approximately 600 tpd was selected.
Processing
- 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.
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).
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 grinding circuit is controlled by an expert system and fuzzy logic.
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 un ........

Recoveries & Grades:
Commodity | Parameter | 2018 | 2017 | 2016 |
Gold
|
Recovery Rate, %
| ......  | ......  | ......  |
Gold
|
Head Grade, g/t
| 5 | 5.6 | 6.9 |
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Production:
Commodity | Units | 2018 | 2017 | 2016 |
Gold
|
oz
| ......  | 50,764 | 42,639 |
All production numbers are expressed as metal in doré.
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Operational Metrics:
Metrics | 2018 | 2017 | 2016 |
Tonnes milled
| ......  | ......  | 199,231 t |
Daily mining rate
| ......  | ......  | 600 t |
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Reserves at December 31, 2018:
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven & Probable
|
751 kt
|
Gold
|
4.9 g/t
|
117 koz
|
Measured & Indicated
|
826 kt
|
Gold
|
5 g/t
|
133 koz
|
Inferred
|
1,988 kt
|
Gold
|
5.3 g/t
|
337 koz
|
Commodity Production Costs:
| Commodity | Units | 2018 | 2017 | 2016 |
Cash costs (sold)
|
Gold
|
USD
|
......
|
610 / oz
|
438 / oz
|
All-in sustaining costs (sold)
|
Gold
|
USD
|
......
|
972 / oz
|
711 / oz
|
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Financials:
| Units | 2018 | 2017 | 2016 |
Sustaining costs
|
M USD
| ......  | ......  | |
Capital expenditures
|
M USD
| ......  | ......  | ......  |
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Heavy Mobile Equipment as of December 31, 2016:
HME Type | Size | Quantity |
Drill jumbo (single boom)
|
|
1
|
Drill jumbo (two boom)
|
|
2
|
Load-Haul-Dump (LHD)
|
6 cu. m
|
5
|
Load-Haul-Dump (LHD)
|
3.5 cu. m
|
2
|
Scissor Lift
|
|
3
|
Truck (haul)
|
45 t
|
3
|
Truck (haul)
|
30 t
|
1
|
Corporate Filings & Presentations:
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Aerial view:
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