Application of SL Centrifugal Concentrator in Iron Ore Beneficiation

Micro-fine refractory iron ore constitutes a major technical bottleneck in iron ore processing. Ores feature fine crystal grain size; full mineral liberation cannot be achieved even after grinding to -325 mesh. Gangue minerals are complex and variable in composition. Conventional flotation shows poor adaptability to ore property fluctuations, resulting in unstable separation indexes, high reagent consumption and high operation and maintenance costs, which restrict improvements of iron concentrate quality and metal recovery.

The SL centrifugal concentrator is a centrifugallyenhanced flowingfilm gravityseparation device. Centrifugal force amplifies density differences among mineral particles to realize separation. When pulp enters the highspeed rotating drum, highdensity iron minerals settle rapidly and get enriched under centrifugal force, while lowdensity gangue minerals are discharged as tailings along with pulp. The equipment possesses a low separation lower limit and is specially designed for microfine ironmineral processing. As a physical beneficiation unit, it requires no chemical reagents, features low power consumption and stable operation. It can directly substitute reverse flotation for cleaning of highintensity magnetic concentrate, simplifying beneficiation flowsheets and easing environmental pressure as well as operating costs.

At Kunsteel Dahongshan Iron Mine, the SLon2400 centrifugal concentrator replaced the original reverseflotation circuit and was put into industrial operation in 2010. Before retrofit, iron concentrate grade stood merely at 62%63%. After retrofit, with feed ore grade of 35.61 %, iron concentrate grade rose to 64.95 % and iron recovery reached 74.06 %. Concentrate grade remains stably within 64%-65 %, realizing quality and efficiency improvement. For conventional ironore treatment, at feed grade of 39.15 %, concentrate grade of 63.20 %, concentrate yield of 39.19 % and iron recovery of 63.26 % can be obtained. In a Fujian iron ore tailings recovery project, tailings feed with iron grade of 18.80 % is processed to produce qualified iron fine powder of 60.15 % Fe, achieving resource reuse of tailings.

Production practices verify that the SL centrifugal concentrator has strong adaptability to fine-grained refractory iron ore. It can be deployed either for ironconcentrate upgrading in main beneficiation circuits or for ironresource recovery from iron ore tailings. It maintains stable separation performance under variable ore property conditions, eliminates flotation reagent systems and cuts overall beneficiation costs. It offers a feasible solution for development and utilization of domestic microfine ironore resources.

Key Field application Indicators

72 units of SL-2400 centrifugal concentrators deployed at Hainan Iron Mine Feed grade: 39.15 %; Concentrate grade: 63.20 % Concentrate yield: 39.19 %; Iron recovery: 63.26 %

SL centrifugal concentrator for tailingsderived iron fine powder recovery in Fujian Feed tailings: 18.80 % Fe; Concentrate product: 60.15 % Fe

SL centrifugal concentrator at Kunsteel Dahongshan Iron Mine Overall flowsheet indexes: Feed ore grade: 35.61 %; Iron concentrate grade: 64.95 %; Iron recovery: 74.06 % Iron concentrate grade increased from 62.63 % (pre-retrofit) to stable 64.65 %.

Typical iron ore beneficiation process flow

Process note: The SL-2400 centrifugal concentrator was adopted to replace reverse flotation for cleaning high-intensity magnetic concentrate; the circuit was commissioned in 2010.