One of the oldest iron ore mining operations in Brazil, Companhia Siderúrgica Nacional (CSN)-owned Casa de Pedra holds more than 6 billion tons of resources and 3 billion tons in reserves. The operation mines four orebodies with the iron ore sent for processing in the Central Plant (wet route) or the Mobile Plants (dry route), located near the extraction areas.

Casa de Pedra currently has a production capacity of 30 Mt/y. Products resulting from the beneficiation process are grain, sinter feed and pellet feed. The ore is transported to the Port of Itaguaí (TECAR) via rail terminals located in Casa de Pedra and the Pires Complex.

Opting to decommission its upstream wet tailings dam several years ago, CSN began the design and construction of an extensive new dry stacked tailings plant with Massa, Italy-headquartered Matec Industries in the early parts of 2018, breaking the complete installation into three phases. Phase 1 (solid feed 550 t/h in design, with 585 t/h achieved) comprises two vertical high rake thickeners and four Magnum 2000/190PLT TT2 Fast Filter Presses fed straight from CSN’s tailings dam and was successfully commissioned towards the end of 2018. The plant footprint is 62 m by 15 m and each filter press having 190 plates. The filter cake is removed by conveyor and stockpiled by a radial conveyor.

Phase 2 (solids feed 650 t/h) then eliminated the feed to the upstream tailings dam entirely whilst still rehabilitating the tailings dam. That plant comprises of three vertical high rake thickeners and five Magnum 2000/190PLT TT2 Fast Filter Presses. Again each filter press has 190 plates. Filter cake is removed with conveyors and stockpiled by a radial conveyor. Phase 3 which Matec told IM is now in final commissioning comprises another two Magnum 2000/190PLT TT2 Fast Filter Presses as well as a 40 m horizontal thickener. Overall the tailings plant with all three phases installed now has a capacity of 35,000 t/d.