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Finland
Otso (Laiva) Mine

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 Location:
16 km SE from Raahe, Finland

  Address:
Laivakankaantie 503
Mattilanperä
Finland
92230
Phone  ...  Subscription required
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  • Overview
  • Owners
  • Geology
  • Mining
  • Processing
  • Production
  • Reserves
  • Financials
  • Fleet
  • Personnel
  • Filings & News

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Overview

StatusCare and Maintenance
Mine TypeOpen Pit
Commodities
  • Gold
  • Silver
Mining Method
  • Truck & Shovel / Loader
Processing
  • Gravity separation
  • Smelting
  • Flotation
  • Agitated tank (VAT) leaching
  • Carbon in leach (CIL)
  • Elution
  • Carbon adsorption
  • Solvent Extraction & Electrowinning
Mine Life6 years (as of Jan 1, 2018)
The Laiva 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.

The latest anticipated restart date of the Otso Gold Mine being April 1, 2021. [09/28/2020, PR]
Latest NewsOtso Gold Corp.: Shareholder Update     April 7, 2021


Owners

Source: p. 2
CompanyInterestOwnership
Otso Gold Corp. 100 % Indirect
The Company owns, indirectly through Swedish and Finnish companies, 100% of a fully licensed and developed gold mine in Finland (the “Otso Gold Mine” )(formerly known as the ”Laiva Gold Mine”).

Deposit Type

  • Orogenic


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.


Mining Methods

  • Truck & Shovel / Loader


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.


Crushing and Grinding


Processing

  • Gravity separation
  • Smelting
  • Flotation
  • Agitated tank (VAT) leaching
  • Carbon in leach (CIL)
  • Elution
  • Carbon adsorption
  • Solvent Extraction & Electrowinning

Flow Sheet: Subscription required

Summary:

The mineral processing plant is located approximatly 1 km northeast from the South and North open pits in the Laivakangas area. Recovery method is direct leaching by CIL method. Processing of mineralized material consists of three primary circuit components: grinding circuits, pre-concentration by by flash flotation and gravity concentration.

Mineralized material from the open pit is trucked to the crusher feed hopper on two or three shifts. The storage capacity of the hopper is 200 t. The crusher capacity is 500- 800 tph and the maximum feed size to crusher is 1,000 mm. Crushing reduces the material size to P80 150 mm. The crushed mineralized material is transported to the stockpile by conveyor belt. The stockpile capacity is 25k ton mineralized material, corresponding to 40 hours, live capacity from that is 10k mineralized material, consumption of the Mill.

The mechanical scale in mill feed conveyor controls the feeders under the stockpile and the targeted feed ........

Recoveries & Grades:

CommodityParameter2018
Gold Recovery Rate, %  ......  Subscription required
Silver Recovery Rate, %  ......  Subscription required

Production:

CommodityUnits2018LOM (Projected)
Gold oz 3,010456,500
Silver oz  ......  Subscription required
All production numbers are expressed as metal in doré.
Subscription required - Subscription is required.


Reserves at September 18, 2019:

CategoryTonnage CommodityGradeContained Metal
Measured 1,780,452 t Gold 1.54 g/t 87,963 oz
Indicated 5,810,777 t Gold 1.56 g/t 291,515 oz
Measured & Indicated 7,591,229 t Gold 1.55 g/t 379,478 oz
Inferred 24,677,098 t Gold 1.52 g/t 1,209,438 oz
Total Resource 32,268,327 t Gold 1.53 g/t 1,588,916 oz

Financials:

Units20182017
Revenue M USD 3.77  
After-tax Income M USD -28.65  1.55  


Heavy Mobile Equipment as of March 1, 2020:
HME TypeModelQuantityLeased or
Contractor
Excavator ....................... Subscription required Leased
Excavator ....................... Subscription required Leased
Truck (haul) ....................... Subscription required 10 Leased
Subscription required - Subscription is required.

Mine Management:

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required May 22, 2020
....................... Subscription required ....................... Subscription required Subscription required May 22, 2020
Subscription required - Subscription is required.

Staff:

EmployeesYear
Subscription required 2013

Corporate Filings & Presentations:

DocumentYear
................................... Subscription required 2020
................................... Subscription required 2020
................................... Subscription required 2020
................................... Subscription required 2020
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2019
................................... Subscription required 2019
Corporate Presentation 2018
Corporate Presentation 2018
Management Discussion & Analysis 2018
Preliminary Economic Assessment 2018
Subscription required - Subscription is required.

News:

NewsDate
Otso Gold Corp.: Shareholder Update April 7, 2021
Otso Completes US$11 Million Strategic Investment and Begins to Move to Production February 8, 2021
Otso Enters into Subscription Agreement with Strategic Investor to Raise US$11 Million and Begins to Move to Production December 14, 2020
Otso Gold Completes $200,000 Equity Financing September 25, 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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