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Limonite is a weak magnetic mineral, as refractory iron ore. It doesn’t have obvious differences in density, magnetism, and floatability. Limonite has the characteristics of unfixed chemical composition, unstable iron content, a huge change of water content, and easy to over-crush in the crushing and grinding stage. In this passage, let’s learn about the common processing methods of refractory iron ores.
Use the table of contents below to navigate through the guide:
01 Enhanced desliming-verse flotation technology
02 Stage-grinding-Verse flotation technology
03 Improved dispersion-strong magnetic separation
04 Improved classification-coarse magnetic separation-fine flocculation magnetic separation
05 Gravity separation-strong magnetic separation-oxidation roasting-weak magnetic separation process
06 Improved classification-gravity separation-verse flotation technology
Single flotation has characteristics of simple technology flow and good recovery effect of micro-fine limonite ore. However, limonite is very to slime, which seriously influences the effect of flotation. Therefore, enhanced desliming or scattered slime is very important. Besides, verse flotation is more suitable for limonite purification. Limonite particles are the crystallization in osteoporosis. The specific surface area is large, which is easy to adsorb and consume agents. Dosing in small amounts several times and processing several times is suitable.
The technology of enhanced desliming - doing in small amounts several times and flotation several times uses new high-efficiency cationic flotation agents. With the coordination of high-efficiency desliming measures and dispersant, multi-level extraction can extract difficult limonite ores.
For limonite ore that has a close symbiosis relationship between iron-bearing minerals and gangue minerals, and has a finer grain size, the stage grinding-reverse flotation process can be used for separation.
On the one hand, a part of qualified concentrate can be obtained in the case of coarse grinding, and the useful minerals remaining in the rich tailings need to be re-grinded and re-selected before they can be recovered. On the other hand, because limonite ore has the characteristics of complex ore structure, finer grain size, and large mud water content, choosing the reverse flotation process to increase iron and reduce silicon can achieve a better separation effect.
For limonite ores with large magnetic differences between useful minerals and gangue minerals, ideal separation indexes can be obtained by magnetic separation methods. In the grinding process of raw ore, adding dispersants such as sodium carbonate and water glass to strengthen the dispersion of ore pulp is a key technology to improve the separation efficiency of magnetic separation. For the weak and medium-magnetic limonite, strong magnetic separation can be used to recover it, but it is still important to strengthen the dispersion of the sludge before magnetic separation.
For low-grade fine-grained limonite, although fine grinding can improve the grade of the concentrate, it will also produce the phenomenon of over-grinding and sludge, resulting in a low concentrate recovery rate.
The enhanced classification-coarse-grain magnetic separation-fine-grain flocculation magnetic separation process can better recover the fine-grained iron minerals slushed in the grinding process and improve the recovery rate of the concentrate. The key to the implementation of this process lies in selective dispersion, control of flocculation conditions, and separation conditions of the magnetic separator (such as feed concentration, magnetic field strength, and flushing water, etc.).
For the harmful impurities such as sulfur, phosphorus, lead, zinc, and another compound, the number of impurities is still high through reduction roasting. Therefore, in the reduction roasting process, adding other agents (such as chlorinating agents) can reduce the content of harmful impurities, thereby obtaining qualified iron ore concentrates.
Limonite is a suitable mineral, which will be siltified in the process of crushing, grinding, transportation and mixing. At the same time, iron-containing minerals and gangue minerals have a close symbiosis relationship. If the monomer is dissociated, it will inevitably lead to over-grinding and the phenomenon of fine mud. The enhanced classification-gravity separation-reverse flotation process can overcome the current problems of poor control of limonite beneficiation and grinding fineness, large metal loss during desliming, and low concentrate grade.
The above are several common beneficiation methods for refractory limonite. Although limonite is more difficult to be selected, the comprehensive utilization value of choosing a suitable beneficiation method is also considerable. In order to effectively select a suitable beneficiation method, the editor recommends that you first find a professional beneficiation manufacturer to conduct a beneficiation test analysis on the mineral properties of the limonite, and then customize the limonite beneficiation process that meets the actual situation based on the analysis results.
