The Mustavaara deposit is characteristic of a vanadiferous titanomagnetite deposit (VTM), which are typical mafic layered intrusions.

Mustavaara magnetite gabbro lies in the upper part of the Porttivaara intrusion (part of Koillismaa igneous complex) where it forms a coherent layer following the general layering of the intrusion. The magnetite gabbro is plagioclaseaugite-ilmenomagnetite adcumulate with sharp lower contact and gradual upper contact which is characteristic for VTM deposits.

The Mustavaara deposit is a vanadium bearing magnetite gabbro horizon which is part of a large mafic layered intrusive complex, known as the Koillismaa Layered Igneous Complex. The age of the intrusion is approximately 2,400 to 2,500 Ma. This sheet like body intruded into the Archean basement as a single body with a total length of 100 km and a thickness of up to 3 km. This body has separated into at least 5 distinct large blocks due to later folding and faulting. The block containing the Mustavaara deposit is the Porttivaara Block, with a total approximate length of 19 km.

The layered intrusion is divided into a marginal series (50 to 250 m thick) at the base and a thick layered series (up to 2,500 m thick) making up the bulk of the intrusion. The layered series is mainly composed of norites, gabbronorites, leucogabbros and anorthosites. The ore- bearing Mustavaara magnetite-gabbro occurs in the upper part of the layered series, surrounded by anorthosite rocks. The ore-horizon is a sheet-like body that trends east-west over a total strike length of approximately 15km within the Porttivaara Block. The ore-horizon generally dips 35°- 45° to the north. The thickness progressively increases from east to west up to a maximum of 200 m, while the average magnetite concentrate decreases to the west from 20% in the east to less than 10% in the western part.

Genetically, the vanadium rich magnetite gabbro is considered to be of magmatic origin formed as a segregation from an iron-rich liquid.

According to Karinen et al. (2015), the Mustavaara vanadiferous titanomagnetite (VTM) deposit was formed by gravity concentration of iron oxide crystals, or by sorting of a magnetite slurry. In the Panzhihua Complex, VTM deposit formation via gravitational accumulation has been suggested as well as fractional crystallisation of Fe-Ti-V oxides (Gao et al. 2019). Repetition of these mechanisms has led to the formation of several stratified layers of magnetite ore. In Mustavaara the magnetite crystals contain thin lamellae of ilmenite and are generally referred to as ilmenomagnetite. Iron content of the ilmenomagnetite concentrate is around 62 - 63% Fe and the average vanadium contents in the magnetite concentrate from the four units is approximately 0.9% V. At Mustavaara the amount of ilmenomagnetite in magnetite gabbro changes in such a regular way that the ilmenomagnetite layer can be divided into four separate layers. The three lowermost layers comprise the main constituent of the Mustavaara ore deposit and they are called: ore lower layer (OLL), ore middle layer (OML) and ore upper layer (OUL). The highest ilmenomagnetite content of 20 – 35 wt.% is in OLL (footwall contact), which forms a narrow and continuous layer (0.2 – 4 m) just above and following the footwall contact. OUL (hanging wall contact) forms a thicker (20 – 40 m) and continuous layer along the hanging wall contact in the main ore layer and has ilmenomagnetite content of 18 – 25 wt.%. In the thickest (10 – 50 m) OML the ilmenomagnetite content is 10 – 15 wt.%.

The fourth layer above the hanging wall contact consists of weakly disseminated ilmenomagnetite and is labelled as the ore disseminated layer (ODL). The ODL is the most inhomogeneous layer, which contains scattered anorthosite, and anorthosite gabbro fragments and compact magnetite veins. The anorthosite gabbro waste rock blocks do not necessarily follow the general layering and are randomly oriented. Upwards, the ilmenomagnetite dissemination gradually decrease and the amount of anorthosite gabbro blocks and layers in the magnetite gabbro increase. This happens until the rock is a heterogeneous anorthosite gabbro containing specks of magnetite gabbro. In this disseminated layer the ilmenomagnetite content usually varies from 2 - 10 wt.%.

The magnetite gabbro horizon dips 30 to 40° to the north. In the westernmost part (800 m) the thickness of the coherent ilmenomagnetite ore layer (OLL+OML+OUL) is 60 – 95 metres. Eastward (700 m) the thickness of the ore layer is quite consistent at 40 – 50 metres. In the easternmost part, over a distance of 200 m, the dip starts to steepen from 40 to 70°. Over the same distance the thickness of the ore layer starts to become thinner, from 40 meters to 10 metres thick, until it finally dies out completely.

The mine design and mine planning for Mustavaara project is based on the Mineral resource estimate. The Mustavaara deposit mine plan was developed based on the assumption that the mine is operated by an owner operated fleet. The selected conventional truck and shovel excavation is a commonly used mining method in Finland and there is a widely available skilled work force. The mining will start by expanding the existing open pit to west and eventually the maximum open pit dimensions are reached by utilizing a one ramp configuration in the open pit.

A detailed hydrological study has not yet been performed and it is recommended to be done in the next project phase. The created life of mine plan (LOM) supports approximately 20 years of production at Mustavaara. The planned annual mining rate is 3.25 Mt of processed material and the total strip ratio during the life of mine is 1.7. Waste rock mining varies between 4.2 to 7.5 Mt during the main production period.

The open pit optimization results that were used as a base for mine design are based on Measured, Indicated and Inferred mineral resources. The Company further cautions that the PEA is preliminary in nature. No detailed mining study has been completed to support reserve estimation.

The designed open pit is 1,935 meters long (SW–NE) and 435 meters wide (NW–SE). The maximum depth of the pit is 199 meters, calculated from the top of the existing ramp.

Crushing & Primary Grinding
Gyratory crusher (375 kW) is used as a primary crusher. Ore is transported by trucks from the pit to the crusher. Target product particle size after primary crushing is approximately 150 mm (P80). Crushed ore is fed to the screen. Screen overflow is fed to the secondary crusher (cone crusher). Screen underflow and cone crusher product are fed to the conveyor belt and transported to the 30,000 tonne stockpile. Apron feeders are used to feed the ore from the stockpile to the grinding circuit.

HPGR (high pressure grinding roll, 1658 kW) is used in primary grinding. Target product particle size after HPGR circuit is approximately 1 mm (P80). HPGR is operated in a closed circuit with a vibrating screen. Screen oversize is returned to the mill. Screen undersize is fed to the first stage magnetic separation.

Magnetic Separation and Secondary/Tertiary Grinding
Magnetic separation circuit consists of five magnetic separation stages (1,2,3,4 and scavenger separation stages) together with secondary and tertiary grinding stages.

First magnetic separation stage consists of two parallel three drum concurrent LIMS separators. Concentrate is fed to the secondary grinding circuit, tailings to the third hydrocyclone classification.

2,000 kW ball mill is used as a secondary mill. Secondary mill is used to grind first, second and scavenger stage magnetic separation concentrates. Secondary milling is done in closed circuit with pre-classification. Hydrocyclone underflow is fed to the mill, overflow is fed to the third stage magnetic separation. Target product particle size after secondary grinding is 200 µm (P80).

Second magnetic separation stage consists of two parallel double drum concurrent LIMS separators. Concentrate is fed to the secondary grinding circuit, tailings to the hydrocyclone classification.

Third magnetic separation stage consists of three parallel three drum concurrent LIMS separators. Concentrate is fed to the tertiary grinding circuit, tailings to the intermediate thickener.

2,250 kW vertical mill is used as a tertiary mill. Tertiary mill is used to grind third stage magnetic separation concentrate. Tertiary milling is done in closed circuit. Hydrocylone underflow is fed to the mill, overflow is fed to the fourth stage magnetic separation. Mill discharge is fed back to the hydrocyclone. Target product particle size after tertiary grinding is 37 µm (P80).

Fourth magnetic separation stage consists of two parallel six drum concurrent LIMS separators. Concentrate is fed to the concentrate thickener (final concentrate), tailings to the intermediate thickener.

Scavenger magnetic separation stage consists of two single-drum concurrent LIMS separators. Scavenger concentrates are returned to the secondary grinding circuit, tailings are fed to the tailings thickener.

Ferrovanadium production process consists of concentrator plant in Mustavaara and smelter / hydrometallurgical plants in Raahe. Concentrator plant process is based on two-stage crushing, three-stage grinding and multi-stage magnetic separation to produce iron/vanadium concentrate. Direct smelting and selective oxidation are used to bring vanadium to suitable form (vanadium slag) to act as a feed material to roast-leach process. Pig iron is produced as a by-product of smelting process. Roast-leach process is used to produce vanadium pentoxide (V 2 O 5 ) from vanadium slag. Vanadium pentoxide is fed to the aluminothermic reduction. Vanadium product from aluminothermic reduction is ferrovanadium (FeV80).

Process design is based on annual throughput of 3.25 Mtpa ore to the concentrator plant.

Concentrator Plant
Concentrator Plant is operated 7 days a week in three shifts (estimated plant availability 90%), except crushing which is operated 5 days a week in two sh ........