The ore preparation plant is a four-stage series of crushing and screening whereby the undersize is fed into the next stage of crushing and the oversize is crushed again. The crushing stages are primary crushing, secondary crushing, tertiary crushing and fines crushing. Each stage is preceded by screening.
The Ore Preparation Plant receives feed from underground with a top size of 300mm. The ore is processed through the plant in four different stages with the aim to reduce the particle size to 80% passing 6mm. The first stage of crushing is done by a jaw crusher. The jaw crusher has a gap size of 150mm. The jaw crusher product is stored on the ROM stockpile after which it is used to feed the secondary section. The secondary cone crusher has a closed side setting of 40mm.
The secondary section is preceded by a scalping screen with an aperture size of 40mm. The scalping screen undersize and the cone crusher product feed the tertiary screens with an aperture size of 19mm. The tertiary screen oversize feeds the tertiary cone crusher. The tertiary screen undersize and the tertiary cone crusher product feed the fines screens. The fines screens are double-deck screens; the top deck has an aperture size of 15mm and the bottom deck is 10mm. The fines screens screen oversize form a recirculating load as it is fed into the fines impact crushers. The impact crusher product is discharged on the same conveyor as the one conveying the tertiary screen undersize and the tertiary cone crusher product to the fines screens. The fines screen undersize is regarded as the final product of the Ore Preparation Plant.
The tertiary cone crushers have a closed-side setting of 19mm and the impact crushers have a gap size of 20mm. The fines screens are double-deck screens with the top deck aperture size of 15mm and the bottom deck has an aperture size of 10mm. The 90% passing 8mm is required for the downstream process of sintering. The product size is highly important as it affects the downstream sintering process.