Magnetic separation places the leading position in iron ore separation. For weak magnetic and lean iron, Xinhai adopts gravity separation, magnetic separation, flotation, and roasting magnetic separation; used for strong magnetic iron ore, magnetic separation
Magnetite Separation Production Line is used to single magnetite with simple ore properties
It is used to low grade magnetite. Due to the strong magnetic and easy to grind, one stage grinding is adopted for magnetite with coarse particle distribution, conversely the multi stages grinding. At present the fine grinding technology promoted by Xinhai improves the concentrate grate from 61% to 67%
Weak magnetic iron ore separation process
Weak magnetic mineral could use the strong magnetic mineral separation process after the magnetizing and roasting
In two stages grinding, stages separation, single weak magnetic flow, fine grinding means adding fine screen regrinding process to separate fine minerals timely and reduce the over-grinding. It improves the capacity of ball mill and concentrate grade by 2%
A magnetite in Inner Mongolia, the main mental mineral was magnetite with disseminated structure and fine particle distribution. The iron content was about 12-16%. This plant adopted the grinding-weak magnetic process and obtained 65% concentrate grade and 90% recovery rate, but the operation cost is too high after a long time running. It authorized Xinhai to reform the process. Xinhai did not only keep the original indexes, but also reduce the operation costs. Indexes comparison as follow
Comparison of Reformation
Iron Concentrate Grade /%
Iron Concentrate Recovery Rate /%
Three stages grinding, Three stages magnetic separation
Stages grinding, stages separation
Due to the low grade of the iron ore, the stages grinding and stages separation could reduce energy consumption. Cost saving is the key of developing the mine. The fine grinding process has guide significance for similar iron ore
Case 2 —— Shanxi 1,200t/d Iron Mineral Processing Plant
The Shanxi 1,200t/d iron mineral processing plant was an EPC+M+O project.
Two-stage closed-circuit crushing and screening-two-stage closed-circuit grinding and classification-magnetic separation process of one-stage roughing and three-stage concentration concentrates and tailings filtering and dewatering.
Crushing and screening: the final product size was -12mm. Advanced and cost-effective equipment was adopted;crushing and screening processes shared the plant for convenience; the crushing product was fine so that crushing and grinding costs were cut.
Grinding and classification: the first- and second-grinding fineness was -200 mesh (67%) and -325 mesh (88.47%) respectively. Bearing-drive energy-saving ball mill was adopted so that grinding costs were significantly reduced. Upgraded spiral classifier and fine screen were adopted in the first- and second-stage classification respectively to control the particle size strictly.
Magnetic separation: one-stage roughing and three-stage concentration. (Xinhai rubber pump was used to transport slurry.)
Concentrates and tailings transportation: iron concentrates were dehydrated in the permanent magnetic filter and then transported by belt conveyor to the iron concentrates powder dump, and tailings flowed by gravity to the ditch outside the plant.
The project adopted advanced, sound and energy-saving equipment and simple auxiliary facilities to cut construction costs and increase output. There was no environmental pollution, meaning that no waste water was discharged.
Case 3 —— Anhui 600t/d Iron Mineral Processing Plant
As the ore properties were complicated, Xinhai carried out a series of mineral processing tests. After the comparison among them, an ideal process was identified for the ore.
Two-stage grinding-six-stage magnetic separation-iron concentrates dewatering-gravity concentration for magnetic tailings-regrinding-sulfur and titanium flotation and separation.
Grinding and separation: two-stage grinding-six-stage magnetic separation.
Iron concentrates dewatering: iron concentrates were pumped to the permanent magnetic filter and dehydrated together with already produced concentrates; filtrate returned to the system for recycling and filter cake was transported by belt conveyor at three times to the dump.
Sulfur and titanium separation: gravity concentration-regrinding-flotation.
While increasing the efficiency of resources exploration, Xinhai paid attention to environmental protection. Effective solutions were adopted to address the spread of dust and noise and the disposal of waste water and tailings so that green development of the mine was ensured.