Mineral Processing

How To Beneficiation Various Types Of Iron Ore 

The beneficiation process for rhodochrosite, limonite, polymetallic symbiotic iron ore and so on iron ores.

Siderite ore beneficiation technology

Because the theoretical iron grade of limonite is low, and often with calcium, magnesium, manganese is a homogeneous symbiosis, so the use of physical beneficiation methods iron ore concentrate grade is difficult to reach more than 45%, but after roasting because of the large burn loss and significantly improve the grade of iron ore concentrate. The more economical beneficiation method is gravity separation, strong magnetic separation, but it is difficult to effectively reduce the content of impurities in the iron ore concentrate. Strong magnetic separation – flotation combined process can effectively reduce the content of impurities in iron ore concentrate, iron ore concentrate roasting is still a high-quality ironmaking raw material.

Limonite ore beneficiation

Since limonite is rich in crystalline water, it is difficult to reach 60% iron ore concentrate grade by physical beneficiation method, but the iron ore concentrate grade is greatly improved after roasting due to larger burn loss. In addition, it is difficult to obtain a high metal recovery rate because limonite is easily muddied in the crushing and grinding process. The limonite ore beneficiation process includes reduction magnetization, roasting-weak magnetic separation, strong magnetic separation, gravity separation, flotation and its combined process. 

We have conducted industrial tests on selective flocculation – strong magnetic separation technology for limonite ore in Jiangxi iron pit, and the results show that the iron metal recovery rate can be increased by more than 10 percentage points, but it has not been industrialized due to the control of flocculation equipment and selective flocculation process conditions. In the past two years, with the successful development of new high-gradient strong magnetic separator and new high-efficiency anti-flotation agent, strong magnetic separation – reverse flotation – roasting combined process of sorting limonite ore has made significant progress, that is, first through the strong magnetic – reverse flotation to obtain low impurity content of iron ore concentrate, and then through ordinary roasting or with magnetite The production of pellet ore by ordinary roasting or mixing with magnetic iron ore concentrate can significantly improve the iron grade of the product, which is still a high-quality raw material for iron making.

Composite iron ore beneficiation

Most of the iron ores in China contain more than two kinds of iron minerals, and the more kinds the worse the selectivity. This type of iron ore to co-exist with hematite, mirror iron ore, needle iron ore, rhodochrosite, limonite and other weak magnetic iron minerals are more difficult to select. For this reason, in recent years, a large number of related research work, the more prominent research results are weak magnetic – strong magnetic – flotation and magnetization roasting – reverse flotation and other joint processes.

Polymetallic co-generation of iron ore beneficiation

China’s difficult to select polymetallic symbiotic iron ore mainly includes Baotou Baiyun Ebo rare earth iron ore and Panzhihua vanadium-titanium magnetite, etc. This type of iron ore is characterized by complex mineral composition and symbiotic relationship, which results in low iron concentrate separation index and low recovery of co-associated valuable elements. Among them, Baotou Baiyun Ebo rare earth iron oxide ore is especially difficult to be selected. 

At present, the iron oxide ore line of Baotou Baosteel processing plant adopts weak magnetic – strong magnetic – reverse flotation process for iron separation, and the strong magnetic concentrate mainly contains easy to float fluorite, carbonate and other minerals and difficult to float and difficult to select iron silicate minerals. 

For easy to float fluorite, carbonate and other minerals Baosteel processing plant through decades of research and production practice has formed a more mature method, that is, water glass as inhibitor, GE-28 for the trapping agent of weak alkaline reverse flotation production process, and difficult to float difficult to select iron silicate minerals have not been effectively separated, resulting in low iron concentrate grade (hovering at 55% below ), and high potassium content in the concentrate. 

For the strong magnetic concentrate sample taken from the site, with fineness of -0.076mm accounting for about 88% and iron grade of about 43.5%, the optimized combination of reverse flotation – positive flotation process was adopted, and a new type of high efficiency trapping agent was used in the positive flotation operation, and the flotation closed circuit test index of the whole process was about 53% of concentrate and 62% of iron grade. 

At the same time, the harmful elements such as P, K2O, Na2O and F are greatly reduced, which opens up an effective new way to improve the separation index of this type of iron ore. In addition, for Panzhihua vanadium and titanium magnetite ore, respectively, using fine screening – re-mill process for iron and high gradient strong magnetic – flotation process for titanium, the selection index of the ore have been significantly improved.

Oolitic hematite beneficiation

Oolitic hematite embedded in very fine particle size and often with rhodochrosite, oolitic chlorite and phosphorus minerals symbiotic or mutual wrapping, so oolitic hematite is currently recognized as the most difficult type of iron ore selection at home and abroad. In the past, a lot of experimental research work on this type of iron ore beneficiation, including reduction roasting – weak magnetic separation process of the selection index is relatively good, but because of its technical difficulties is the need for ultra-fine grinding, and the current conventional beneficiation equipment and chemicals are difficult to effectively recover -10μm microfine particles of iron minerals, so this type of iron ore resources basically not utilized. 

With the gradual decrease of available iron ore resources in China, the study of efficient beneficiation technology for oolitic hematite has highlighted the importance and urgency. 

Relevant preliminary research results prove that ultra-fine grinding – selective flocculation (agglomeration) – strong magnetic separation or flotation, reduction roasting – ultra-fine grinding – selective flocculation (agglomeration) – weak magnetic separation or flotation and other high-efficiency beneficiation process or combined electrometallurgical process has shown its superiority.

Beneficiation iron ore contain high sulfur, phosphorus

Most of our iron ore contains sulfur, phosphorus and other harmful impurities. Especially for iron ores rich in magnetic pyrite, microfine particles of apatite or colloidal phosphate ore, the iron ore concentrate is extremely difficult to remove the impurities. The common processes used to remove sulfur from iron ore concentrates are flotation and roasting, while the latter is costly and produces environmental pollution, so the main direction of research is to strengthen flotation. Our company has developed a high-efficiency separation process of magnetite and magnetic pyrite with high-efficiency activator as the key technology. 

Through a number of domestic and foreign magnetic pyrite type high sulfur magnetite beneficiation research and application results prove that compared with conventional flotation, iron concentrate sulfur content can be reduced by 0.5 percentage points, the important thing is that the iron concentrate sulfur content can meet the requirements of subsequent users. 

A large number of research results prove that iron ore concentrate phosphorus removal can be used magnetic separation, reverse flotation, selective flocculation (agglomeration), acid leaching, chlorination roasting – acid leaching, bioleaching and its combined process, etc., of which magnetic separation – reverse flotation, selective flocculation (agglomeration) – reverse flotation combined process is more economical, chlorination roasting -Acid leaching process to remove phosphorus effect is better, but the cost is higher, and bioleaching is the future development direction.