Overview
Stage | Production |
Mine Type | Open Pit |
Commodities |
|
Mining Method |
|
Processing |
- Gravity separation
- Smelting
- INCO sulfur dioxide/air process
- Spiral concentrator / separator
- Flotation
- Carbon in leach (CIL)
- Carbon adsorption
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
|
Mine Life | 6 years (as of Jan 1, 2018) |
The Mine initially commenced production in January 2012; mining ceased in December 2013. The mill continued to operate, processing low-grade stockpile material until March 2014. The second period of operation was from August 2018, continuing to March 2019 when the operation was put into care and maintenance.
September 28, 2021 - The Otso Gold Corp. is pleased to announce that the Otso Gold Corp. restarted the process plant and began ramping-up production at the Otso Gold Mine on September 20, 2021.
November 3, 2021 - First gold pour. |
Latest News | Otso Gold Corp.: Publication of the Feasibility Study November 5, 2021 |
Source:
p. 2
The Company (Otso Gold Corp.) owns, indirectly through Swedish and Finnish subsidiaries, 100% of the Otso Gold Mine (the ‘Mine’) a fully licensed and developed gold mine in Finland.
Summary:
Laiva is classed as an orogenic gold deposit.
Mineralization comprises sheeted quartz-sulphide vein arrays within multiple, sub-parallel, mylonitic shear zone, hosted in metavolcanic and quartz diorite rocks. Mineralization occurs in two main bodies, the North Pit with Eastern Extention in the north, and the South Pit in the south.
At the North Pit, mineralised shear zones can be traced over a strike length of up to 600m, with the mineralized zone (including the Eastern Extention) occurring over an area of 1300 m by 450 m. In the South Pit area, mineralization occurs over an area of 500 m by 400 m. Mineralization has been intercepted at depths of up to 250 m below surface and is open down pit, apart from the western part of the North Pit where mineralization is truncated by the granite pluton. In both the North and South Pits, the mineralized shear zones vary in windth between <1 m to >10 m.
The mineralised shear zones display distinct structural trends in differetn parts of the deposit, with the orientation being dependent on proximity to the Red Shear Zone. West of the Red Shear Zone, mineralised shear zones strike east-northest and dip steeply (78 degrees to 85 degrees) south-southeast. Immediatly east of the Red Shear Zone, mineralised shear zones strike east-northest and dip steeply west- southwest, transitioning to av almost easterly strike wuth southerly, steep dip progressively to the east.
Within the mineralized shear zones, vein density varies between 1 and 29 veins per meter. Mineralized shear zones display sharp contacts with the host rocks and there is no gold grade associated with the narrow selvedges. In general, veins are more closely spaced in the metavolcanic rocks compared to the veins hosted in quartz diorite, and there is a positive correlation between vein density and gold grade. This increased vein density and gold grade in metavolcanic rocks compared to quartz diorite may be attributed to contrasting arheology and/or chemical composition of the host rocks.
Individual veins are typically planar, narrow (2 to 5 mm, rarely 2-5 cm) and display localized pinching and swelling, although the mineralized structure may be continuous over tens of meters.
Quartz veins are composed of very fine-grained, massive, blue-grey quartz with variable, disseminated and blebby, fine- to medium- grained pyrite, arsenopyrite, pyrrhotite, and chalcopyrite. Molybdenite is rarely observed, mainly in the Eastern Extension mineralization.
Gold grade continuity is variable along strike and down dip. Whilst structural continuity and mineralization is continuous along strike and down dip, elevanted grades of >1 g/t gold display a localizedcharacter. Higher grades of >5 g/t gold are relatively common but generally dispersed within a mineralized structure.
Summary:
The Laiva Project is composed of a single project with three mining areas: the previously developed South Pit in the southwestern portion of the project; the previously developed North Pit area in the northern portion of the project; and the East Pit area located east of the North and South pit areas.
Standard mining technology has been utilized to create an open pit at each of the three mining areas. The South Pit has approximate dimensions of 520 m south to north by 550 m east to west and a maximum depth of 190 m below current ground level. The South is composed of six mining phases with a single standalone phase adjoining the main South Pit to the northeast. The North Pit has approximate dimensions of 580 m south to north by 620 m east to west and a maximum depth of 170 m below current ground level. The North Pit is composed of seven mining phases with several phasesbeing small standalone pits slightly to the north and east of the main North pit. The East Pit has approximate dimensions of 110 m south to north 190 m east to west and a maximum depth of 27 m below current ground level. The East pit is composed of four mining phases with two small pits located to the west of the main East pit.
Single benching of 9 m production benches was determined to be feasible in all geologic units. Catch or safety benches with a width of 5.2 m are used in all designed phases. These safety benches are applied on very bench (9 m vertically). Mineralized material mining is planned on 3 m sub-benches while waste mining is planned on 9 m full height benches.
Two-way haul rouds, 20-m wide at a 12% grade, were designed in most cases where higher traffic may require extra width for safe and efficient passing of trucks. To maximize mineralized material recovery at depth, the final benches of each pit floor were designed with single-lane access (9 m width).
The ultimate pit limits selected for the three mining areas foe the Laiva project were selected based on Whittle open-pit economic optimization. The 3 mining areas will be developed using 17 distinct phases designed to approximate an optimal extraction sequence.
South Pit Phased Designs.
The Laiva South pit consists of six phases. Phase 1 is the starter pit while phases 2, 3, and 5 expands these starter pits. Phase 6 is the final pit expansion for the South pit. Phase 4 is a standalone remote pit located just to the northeast of the main South pit.
North Pit Phased Designs.
The North pit consists of seven phases. Phase 1 is the starter pit with phases 2 and 3 being expansions of that phase. Phases 4, 5, 6, and 7 are small standalone pits to the north and east of the main North pit.
East Pit Phased Designs.
The East pit consists of four phases. Phases 1 and 2 are starter pits while Phase 3 expands these starter pits. Phase 4 is the final pit expansion for the East pit.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Jaw crusher
|
.......................
|
|
|
1
|
AG mill
|
.......................
|
|
3 MW
|
1
|
Regrind
|
|
|
|
|
Pebble mill
|
.......................
|
|
3 MW
|
1
|
Summary:
Run of Mine ore is crushed using a Metso C160 jaw crusher producing suitable mill feed to a 25,000t stockpile.
Crushed ore is recovered, and conveyor transported to the AG mill followed by a pebble mill at approximately 250 tph. There is a two-stage pebble crushing circuit to control pebble mill load. Both mills are Metso:Outotec design and supply and fitted with 3MW motors. The mills have been inspected and serviced by Metso, the motors by ABB.
Processing
- Gravity separation
- Smelting
- INCO sulfur dioxide/air process
- Spiral concentrator / separator
- Flotation
- Carbon in leach (CIL)
- Carbon adsorption
- Elution
- Solvent Extraction & Electrowinning
- Cyanide (reagent)
Flow Sheet:
Summary:
The process plant was built between 2009-2011 by Metso Minerals in conjunction with Outotec and commissioned. All permits are in place to restart the operations apart from the standard safety and environmental permissions pursuant to our licenses which require the lodgement of the Company’s plans. However, the main focus for the restart is the geology and Mine plan to deliver the name plate 6,000 tonnes per day (two million tonnes processed per annum) to the process plant from Q3 2022 at 1.51 g/t.
The process plant consists of a single stage crushing circuit, grinding mills, a 3 Mw installed power mill, flash flotation, gravity and regrind circuits, high grade and low grade carbon-in-leach plants, carbon stripping and a gold room. Spent mud is sent to two facilities - one high grade and the other low grade. The low-grade dam is approximately 7.5 kilometres from the process plant where it is processed through a thickener. The process plant upgrade and recommissioning is well ........

Recoveries & Grades:
Commodity | Parameter | 2018 |
Gold
|
Recovery Rate, %
| 88.6 |
Silver
|
Recovery Rate, %
| 5.9 |
Production:
Commodity | Units | 2018 | LOM (Projected) |
Gold
|
oz
| 3,010 | 456,500 |
Silver
|
oz
| ......  | |
All production numbers are expressed as metal in doré.
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Reserves at August 5, 2021:
All mineral resources are reported using an open pit gold cut-off of 0.323 g/t Au.
Category | Tonnage | Commodity | Grade | Contained Metal |
Measured
|
1,641,000 t
|
Gold
|
1.26 g/t
|
66,500 oz
|
Indicated
|
13,479,000 t
|
Gold
|
1.063 g/t
|
460,700 oz
|
Measured & Indicated
|
15,120,000 t
|
Gold
|
1.084 g/t
|
527,200 oz
|
Inferred
|
7,333,000 t
|
Gold
|
1.171 g/t
|
276,000 oz
|
Financials:
| Units | 2018 | 2017 |
Revenue
|
M USD
| 3.8 |
|
After-tax Income
|
M USD
| -28.7 |
1.6
|
Corporate Filings & Presentations:
Document | Year |
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2021
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2021
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2021
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2021
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2021
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2020
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2020
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2020
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2020
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2019
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2019
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2019
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2019
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2019
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Corporate Presentation
|
2018
|
Corporate Presentation
|
2018
|
Management Discussion & Analysis
|
2018
|
Preliminary Economic Assessment
|
2018
|
- Subscription is required.
News:
News | Date |
Otso Gold Corp.: Publication of the Feasibility Study
|
November 5, 2021
|
Otso Returns to Production and Pours First Gold
|
November 3, 2021
|
Otso Receives All Approvals to Restart Operations
|
October 12, 2021
|
Otso Gold Corp.: Announces Private Placement of Units for Up To US$5 Million
|
October 4, 2021
|
Otso Gold Provides an Update to Shareholders And Announces the Ramp-Up to Production
|
September 28, 2021
|
Otso Gold Corp.: Updated Mineral Resource Estimate
|
August 19, 2021
|
Otso Gold Executes Mining Contract For Mine Services
|
August 11, 2021
|
Otso Gold Drilling Program Well Advanced
|
May 17, 2021
|
Otso Gold Corp.: Shareholder Update
|
April 7, 2021
|
Otso Enters into Subscription Agreement with Strategic Investor to Raise US$11 Million and Begins to Move to Production
|
December 14, 2020
|
Nordic Gold Inc. Announces Mineral Resource Update for Laiva Project, Raahe, Finland
|
October 15, 2019
|
Nordic Gold Terminates Contract with Mining Contractor
|
March 7, 2019
|
Nordic Gold Completes 1,234 Ounce First Pour
|
December 3, 2018
|
Nordic Gold Announces Approval of Mine Start-up by Finnish Mine Supervising Authority ELY
|
October 11, 2018
|
Firesteel Resources Inc. Announces Economically Robust PEA for Laiva Gold Mine in Finland
|
June 12, 2018
|
Firesteel Resources Closes Joint Venture Agreement with Nordic Mines AB
|
December 11, 2017
|
Aerial view:
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