Special manganese method (1)

The special manganese selection method to be introduced here refers to several special beneficiation methods in addition to conventional re-election, magnetic separation and flotation, which include beneficiation methods such as electro-election, bacterial leaching, reduction or neutral roasting. It should be noted that in addition to neutral calcination, other various manganese-selecting methods have only stayed in the experimental research stage and have not been implemented in industrial production.
A bacterial leaching manganese Biogeotechnology method of Manganese from many years of manganese ore, Institute of Microbiology, Chinese Academy of bacterial oxidation of pyrite mineral using pig iron - manganese sulphate leaching the sulfide ore Tiantaishan achieved very good results, Its chemical reaction:

In the bioleaching process of pyrite, three reactions exist simultaneously, but mainly the biocatalytic reaction predominates.
The manganese sulfide ore and manganese carbonate ore are leached by the H ₂ SO ₄ -Fe ₂ (SO ₄ ) ₃ solvent produced by the above reaction, and the chemical reaction thereof is 3MnCO ₃ +Fe ₂ (SO ₄ ) ₃ +6H ₂ O===3MnSO ₄ +2Fe (OH) ₃ +3H ₂ CO ₃
3MnS+Fe ₂ (SO ₄ ) ₃ +6H ₂ O===3MnSO ₄ +2Fe(OH)3+3H ₂ S
The process of bacterial immersion manganese is shown in Figure 1.

The acid-coated high-iron solution of acid sulfate high-speed iron (industrial reagent) and bacteriological pyrite bacteria can be used to leach the Tiantaishan manganese ore. The former has a manganese leaching rate of 92%, an acid consumption of 21.7%, and acid leaching with pure sulfuric acid. comparison of 74%, acid consumption savings, which leach 3 ~ 4h, manganese leaching rate of 91% ~ 93%, 11.5% acid consumption, manganese leaching solution 11.9 ~ 12.15g / L, phosphorus-containing 0.002g / L.
The Taojiang Manganese Mine also carried out a semi-industrial test on bacterial leaching of the Gaogan manganese ore and interbedded manganese ore in the Gansushan Mountains in 1977. The strain was selected from Thiobacillus ferrooxidans. The leaching solution contained manganese at the leaching temperature of 60-80 °C and the leaching time of 3-4 hours. Up to 10~12g/L, the leaching rate is 70%~88.6%.
The study is currently still in the experimental research phase and has not been implemented in industrial production. [next]
2. Roasting of manganese ore
The manganese elements in the natural manganese ore have different valence states. In the deep processing of manganese ore, in order to obtain the ideal process index, the manganese element must be processed at a certain valence state. In addition, in nature, manganese ore is often mixed with iron minerals. In order to facilitate the separation of ferromanganese, iron minerals are reduced to ferromagnetic Fe ₃ O ₄ . Therefore, the roasting process is an important part in the processing of manganese ore. Generally, calcination is divided into three types: reduction roasting, neutral calcination and oxidative roasting.
(1) The purpose of reduction roasting manganese ore reduction roasting is twofold: one is to reduce high-priced manganese oxide to low-priced manganese oxide, which facilitates the dissolution of manganese into an ionic state during wet leaching of manganese ore. Another purpose is to reduce the weak magnetic iron oxide ore of the ore into a ferromagnetic magnetite or a pseudo-hematite, and then use a weakly selected machine to separate the ferromanganese to increase the manganese-iron ratio of the manganese mineral.
In the reduction roasting, the main chemical reaction formula is as follows:
MnO ₂ +CO===MnO+CO ₂
MnO ₂ +H ₂ ===MnO+H ₂ O
3Fe ₂ O ₃ +CO===2Fe ₃ O ₄ +CO ₂
3Fe ₂ O ₃ +H ₂ ===2Fe ₃ O ₄ +H ₂ O
There are many manganese ore reduction roasting equipments, and there are reverberatory furnaces, shaft furnaces, rotary kiln and boiling furnaces used in industrial production.
Reverberatory furnace

The structure of the reverberatory furnace is simple (Fig. 2). In the late 1960s, the equipment was first used in Changsha Chemical Plant to roast manganese ore to prepare manganese sulfate. It has been obtained in small enterprises in Hunan, Guizhou, Yunnan, Guangxi and other places. widely used.
Manganese oxide and anthracite mass ratio of 100: After mixing ratio of about 16 manually, by the infeed conveyor into the furnace, the material thickness of 150 ~ 200mm, artificial Pa level, to close the baking oven door The calcination temperature is about 800 ° C and the time is about 200 min. Since the material layer in the furnace is in a static state, the furnace door can be opened during the roasting process, and the furnace charge is manually turned to make the calcination reaction uniform. After the calcination is completed, the calcined qualified material is quickly poured into the iron drum by hand and sealed by water spray to be cooled to prevent reoxidation by contact with air. The heat source for roasting is that the high-temperature flue gas supplied from the combustion chamber of the reverberating furnace flows through the roadway under the bottom of the reverberatory furnace to the other end of the reverberatory furnace, then rises and returns to the upper space of the reverberating furnace, and then discharges from the exhaust port into the chimney. .
According to experience, the ratio of reducing agent consumption, mine to coal mass ratio is 100:16, fuel consumption is 100~110kg/t, total coal consumption is 265kg/t ore, total heat consumption (712~773) x10 ⁴ kJ/t ore. The operation is normal, and the manganese ore reduction rate can reach about 90%. The reverberatory furnace is characterized by simple structure, small investment and quick effect. However, the heat consumption is high, the production efficiency is low, and the working conditions are bad, especially the environmental protection problem is not easy to solve.
2. Shaft Furnace The shaft furnace generally refers to the Anshan type shaft furnace. It is named because it was first applied in the roasting workshop of the sintering main plant of Anshan Iron and Steel Co., Ltd. The design of the Bayi manganese ore dressing plant was first used as the reduction roasting equipment.

The structure of the device is simple (Fig. 3). The inside of the rectangular shape furnace is refractory bricks, and the two long sides are inclined at an angle to form an inclined wall, and the purpose is to uniformly reduce the ore. The shaft furnace is divided into four belts according to its working principle; that is, the charging belt, the heating belt, the reduction belt and the cooling belt. The loading belt itself is a mining tank located in the upper part of the furnace. Its task is to adjust the ore to the furnace evenly according to the ore feeder. When the gas heated by the heating belt heats the ore to the temperature required for the reduction reaction, it gradually descends to the reduction zone and contacts the gaseous reducing agent supplied from the lower portion to start the reduction, and the reduced ore continues to fall to the lower sides of the furnace. The bucket conveyor is used to discharge the bucket conveyor that is sunk in the water. The cooled ore is discharged by the bucket conveyor. [next]
The effective volume of the shaft furnace is 40m3, the size of the furnace waist is 300mm, the height of the material column is 1800mm, the inclination angle of the furnace floor is 50°, the air volume of the exhaust fan is 28500m ³ /h, the wind pressure is 10.5kPa, and the power is l00kW when the air is discharged, the two sides are exhausted, and the middle is unloaded.
See Table 1 for the temperature changes of various parts of the gas and shaft furnace when the shaft furnace is used to roast different ores.

See Table 2 for the indicators for the selection of magnetic separators for roasting.

The mixed ore in the minerals refers to manganese ore with a particle size of 50mm or less. The size analysis shows that the particle size is less than 20mm, accounting for 73.14%, while the particle size is less than 10mm, accounting for 51.28%, and the lump ore is mainly 50~10mm, accounting for 75.52%. The rest is less than l0mm. It is obvious from the selection data that the ore is poor in gas permeability due to the majority of the particle size of the calcination in the furnace, although the exhaust of the configured exhaust fan is large, the negative pressure is high, and the negative pressure at the top of the furnace is as high as 6 kPa, but the combustion chamber Still at ±20Pa, the firing hole is at 250Pa. The furnace has poor gas permeability and poor calcination effect. Therefore, it can be explained that the shaft furnace is only suitable for treating ore with a particle size of 20-75 mm, and the ore having a particle size of less than 20 mm is not more than 10%, which is unsuitable for roasting mixed ore or fine ore.
3. Rotary kiln (FIG. 4) reducing the calcined oxide of manganese ore in the mountain habitat exposed lead zinc ore industrial production practice.

The rotary kiln has an outer diameter of 1.5m, a length of 30m, an inner diameter of 1.2m, an effective volume of 30m ³ , a rotational speed of 0.49~0.51r/min, a transmission power of 12~25kW, a rotary kiln installation slope of 1.9%, and a calcined manganese ore particle size of <15mm. 10% of the coal is used as a reducing agent, and the calcined fuel is water gas.
The processing capacity of the rotary kiln is 40t/h, the reducing agent per ton of raw ore is 90~100kg, and the gas consumption is 277m ³ , which is the total heat consumption per ton of ore (350~400) x10 ⁴ kJ.
The rotary kiln is divided into three zones: drying zone, length of about 10~12m, temperature of 100~200°C, preheating and heating zone length of 12~15m, temperature of 350°C, heating reduction zone at the discharge end, temperature above 900°C, The calcined ore is cooled at 600 ° C into a ф 1.5 m x 16 m cooler (sprinkling water on a cooling cylinder), and the calcined ore is cooled and discharged. The manganese ore reduction rate is over 90%. Since its product is used for acid leaching to produce synthetic manganese dioxide, it has been discontinued due to environmental problems.
In 1963, Bayi Manganese Mine carried out manganese ore reduction roasting expansion test in the Ñ„0.25mx4m rotary kiln of Changsha Research Institute of Mining and Metallurgy, and achieved good technical indicators with a treatment capacity of 2.75t/m ³ .
In 1999, Daxin Manganese Mine was built into an electrically heated stainless steel casing for reduction roasting rotary kiln. Coal was used as a reducing agent. Due to poor cooling effect and unsuitable kiln structure, it is still being rectified.

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