5 Common Limonite Mineral Dressing Methods

There are many limonite reserves in the world. The main types are goethite and hydrogoethite, which have weak magnetism, wide range of hardness changes, and are easy to muddy in the process of crushing and grinding. And due to some of its natural properties, it is difficult for limonite to meet the taste requirements of iron concentrate by simple physical beneficiation methods, and it is difficult to obtain a high metal recovery rate. Therefore, limonite is a relatively complex and difficult iron ore one.

Choosing an efficient limonite mineral dressing method is one of the ways to improve its resource utilization. The following will introduce five limonite beneficiation methods for you, namely: washing-screening-gravity separation + strong magnetic separation method, Flotation method, strong magnetic separation method, selective flocculation-strong magnetic separation method, reduction magnetization roasting-weak magnetic separation method.

01Limonite washing-screening-gravity+strong magnetic separation

In the past, for low-grade limonite, ore concentrators often adopted simple physical beneficiation methods, and the content of medium iron ore was relatively high. To improve the grade and recovery of iron concentrate, a limonite mineral processing method combining scrubbing, screening, gravity separation, and high-intensity magnetic separation was subsequently developed.

Specific limonite ore dressing process: the limonite enters the crusher for fine crushing, and the finely crushed product enters the rod mill for grinding. After the pretreatment is completed, the ore enters the ore washing machine for washing, and after desliming, it enters the screening machine for classification. The coarse-grained limonite obtained by classification is separated by gravity separation, the medium-grained limonite enters the roller-type strong magnetic separator for magnetic separation, and the fine-grained minerals enter the high-gradient strong magnetic separator for separation . Among them, the tailings after a re-selection can be re-grinded and re-selected, which can further increase the recovery rate of concentrate iron. This beneficiation process can obviously improve the grade of concentrate iron, and at the same time recover finer limonite and iron minerals in the slime.

02Limonite flotation separation

Limonite single flotation process is simple, and the recovery effect of fine-grained iron ore concentrate is better, but limonite is easy to muddy, which will seriously affect its flotation effect. In order to overcome this problem, desliming or enhanced dispersion of slime can be considered before flotation. In actual beneficiation, reverse flotation is mostly used in limonite flotation, which is beneficial to improve the concentrate grade and remove impurities. Limonite crystals are loose and have a large specific surface area. In order to avoid high chemical consumption, multi-stage chemical addition and multi-stage separation processes can be used in the flotation process. At the same time, in order to improve resource utilization, the flotation process returns to the closed-circuit flotation process.

03Limonite strong magnetic separation method

Because the strong magnetic separation process is simple and easy to operate, it is widely used in the mineral processing industry. In the strong magnetic separation of limonite, the ore is firstly subjected to two-stage crushing and two-stage screening. For products of different particle sizes, permanent magnetic roller magnetic separator is used for dry magnetic separation. This method has a higher recovery rate for -10mm limonite, but poor recovery rate for -20mm ore.

04Limonite selective flocculation-strong magnetic separation method

Low-grade fine-grained limonite can be finely ground to obtain higher-grade concentrates, but the ore after fine grinding is easy to muddy, which leads to a decrease in the recovery rate of the concentrate. The selective flocculation-strong magnetic separation method can improve the problem of poor separation of fine-grained iron minerals by strong magnetic separators, thereby increasing the recovery rate of fine-grained concentrates. The key to this limonite separation technique lies in the control of selective dispersion, flocculation and other conditions of strong magnetic separation, such as ore feeding method and flushing water volume.

05Limonite reduction magnetization roasting-weak magnetic separation 

This method is one of the more effective ways to process limonite. It mainly uses fluidized bed furnace and rotary kiln for magnetized roasting, using lignite as a reducing agent, and the roasted product enters a mill for grinding treatment, followed by weak magnetic separation. In order to reduce production costs and infrastructure investment, cheap low-quality lignite can be used as a solid reducing agent and heating fuel instead of gas.

Comparison of Common Limonite Beneficiation Methods

For a clear and direct comparison, we’ve summarized the key specifications—suitable ore types, cost, and recovery rates—of all five limonite processing methods below. This succinct overview is designed to streamline your decision-making.

The above are the five mineral dressing processes of limonite. In the actual beneficiation operation, it is necessary to select the appropriate beneficiation process flow according to the specific ore properties. Xinhai Mining recommends that the ore beneficiation test and analysis be carried out before the beneficiation process design to determine the ore composition. Xinhai Mining can provide you with professional limonite ore analysis tests, beneficiation process design and complete set of beneficiation equipment manufacturing. If necessary, welcome to consult.