Manganese is widely distributed in nature. Almost all kinds of ores and silicate rocks contain manganese. In modern industry, manganese and its compounds are widely used in various economic fields, among which iron and steel industry is one of the most important fields, with manganese content up to 90%-95%, mainly used as deoxidizer and desulfurizer in the process of iron making and steelmaking, as well as for making alloys.
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Common manganese ores include manganese oxide ore and manganese carbonate ore.
Manganese oxide ore is mainly secondary oxide ore in deposit produced by the weather. Besides it still contains primary and secondary manganese oxide ore in some sedimentary and hydrothermal deposits. The manganese in manganese oxide ores is mainly pyrolusite, pyrolusite and hydromanganese. The gangue minerals are mainly silicate and carbonate minerals, often growing with iron, phosphorus, nickel, cobalt and other contents.
Sedimentary manganese carbonate ore are mainly rhodochrosite, calcium rhodochrosite, manganese calcite, ferromanganese and so on. The gangue minerals are mainly silicate and carbonate minerals, often growing sulphur, iron and other impurities. The mineral is more complicatedly. Manganese minerals have a fineness less than micron, which is not easily dissociated, and hard to be separated into a higher concentrate grade.
As for the fine and micro embedded manganese ores, and there are an amount of high phosphate ore, high iron ore and co - (concomitant) beneficial metals. It is quite difficult to be separated. Now, common manganese processing technology includes physics mineral processing technology(washing-screening separation, gravity separation, strong magnetic separation, flotation, combined separation), chemical processing technology(leaching), and special processing technology(fire enrichment) and so on. Points of manganese mineral processing technology are introduced as follows.
Washing is mainly using hydraulic washing and mechanical scrubbing to realize the separation of minerals and mud. The common equipment includes washing screen, roller washing scrubber, and chute scrubber. Washing is usually with screening, such as washing with water on vibrating screen and then screening the mineral sands with vibrating screen.
Now, gravity separation is used for simple structure and coarse fineness manganese ores, especially manganese with large density. Common gravity separation technology includes heavy medium separation, jig separation, and shaking table separation.
The technology dealing with manganese oxide ores usually crushing ores into 0-6mm to 0-10mm, and then classifying. The coarse minerals are sent to jig separation, and the fine minerals are sent to shaking table separation.
Manganese mineral has weak magnetic(specific susceptibility X=10×10-6~600×10-6cm3/g), which can be effectively recycle in strong magnetic separator with Ho=800-1600kA/m (10000-20000oe). The grade of manganese can increase 4% to 10%.
For the characteristic easy to operate and control, and strong adaption, magnetic separation is wildly used in manganese separation. In recent years, magnetic separation is important in manganese processing technology. All types of strong magnetic separators for coarse, middle, and fine fineness.
Put the qualified particle size of manganese ore into the magnetic separation machine for weak magnetic separation, get strong magnetic manganese concentrate and weak magnetic separation tailings, tailings to the magnetic separation machine for strong magnetic separation, get strong magnetic separation tailings and concentrates, concentrate to the gravity separation equipment for separation, get gravity separation manganese concentrate and tailings.
The strong magnetic separation - flotation method has good adaptability. The high intensity magnetic separators not only remove the slime effectively, but also improve the selection grade of flotation. Comprehensive manganese concentrate products can be directly obtained by high intensity magnetic - flotation desulfurization. Using sodium petroleum sulfonate instead of oxidized paraffin soap as collector, the separation of pulp can be realized in neutral and normal temperature, and the consumption of medicine and energy can be saved.
Usually, manganese leaching includes direct leaching, roasting leaching and biological leaching. Among them, the direct leaching method also includes disulphate method, sulfur dioxide method, ferrous sulfate method and so on.
Take the so2 leaching method as an example, the manganese ore is mixed with slurry, and the sulfur dioxide gas is injected to convert the manganese oxide in the ore into MnSO4 and MnS2O6. Adding lime milk to filtrate can produce manganese hydroxide precipitation and obtain solid manganese hydroxide after filtration. This method is suitable for the treatment of low grade, micrograined manganese oxide ore.
Manganese ore fire enrichment method is a kind of method to deal with high phosphorus and high iron difficult to select poor manganese ore, which is generally called manganese rich slag method. It mainly USES the different reducing temperature of manganese, phosphorus and iron to selectively separate manganese, phosphorus and iron by controlling their temperature in blast furnace or electric furnace.
The above is the common manganese ore dressing method, in the actual production, the manganese carbonate ore dressing method mostly USES the strong magnetic separation, the heavy medium dressing method and the flotation method and so on. Manganese oxide ore is mainly used by gravity separation method, which mainly adopts ore washing-gravity separation process or ore washing-reduction roasting magnetic separation-gravity separation process. Of course, for refractory manganese ore often need to combine two or even more than a variety of separation methods.
Due to the changes in the properties of selected ores, the single flotation process in the original separation plant could not fully adapt to the changes, resulting in the flotation recovery rate of less than 30%, and the separation plant was in the state of loss. The customer commissioned Xinhai Mining for new construction and transformation. In order to improve labor production efficiency and economic benefits, Xinhai Mining adopts new equipment and new technology as far as possible, and makes full use of topographic conditions on the basis of existing conditions to build the factory area, which greatly saves the investment of dressing plant.
The technological process of "SO2 manganese leaching + cyanidation silver leaching full wet method" is adopted in the selection stage, while the technological process of "silver slime - fire smelting - silver alloy - silver electrolysis smelting" is adopted in the smelting stage. Finally, the total recovery of manganese and silver reached more than 80%.