Fluidized low-temperature reduction device and reduction method for powdery manganese oxide ores

Abstract

The invention relates to a fluidized low-temperature reduction device and a fluidized low-temperature reduction method for powdery manganese oxide ores. The device comprises a feeding unit, a preheating unit, a reduction roasting unit and a cooling unit which are connected from top down, wherein the reduction roasting unit is connected with a combustion chamber; and the combustion chamber is connected below the preheating unit. In the reduction method, tail gas formed in the reduction process enters the combustion chamber combusts with supplementary gas and air to form flue gas; and the flue gas is subjected to countercurrent heat exchange with the manganese oxide ores. The fluidized low-temperature reduction device and the reduction method have the advantages that: the gas can be used as a reducer and also can be used as fuel; and the utilization rate of the gas is 100 percent. In the reduction device, the reduction temperature of the manganese oxide ores is low, so a manganese-containing phase which is insoluble to sulfuric acid is avoided, and heat carried by the manganese oxide ores is reduced by over 30 percent. The manganese oxide ores in a fluidized reduction roasting furnace are in the bubbling fluidized state, the heat transfer efficiency, the mass transfer efficiency and the reaction efficiency are high, the distribution of retention time is uniform, and the reduction rate of the manganese oxide is more than 98 percent.

Description

technical field [0001] The invention belongs to the fields of chemical industry and metallurgy, and in particular relates to a fluidized low-temperature reduction device and reduction method for powdered manganese oxide ore. Background technique [0002] Electrolytic manganese is an important raw material for the production of stainless steel, high-strength low-alloy steel, aluminum-manganese alloy, copper-manganese alloy, etc. It is also the main raw material for the production of welding electrodes, ferrite, permanent magnetic alloys, and manganese salts for many pharmaceutical and chemical industries. Manganese ore, the main raw material for the production of electrolytic manganese metal, is mainly divided into two categories: manganese oxide ore and manganese carbonate ore. Manganese carbonate ore can be directly leached by sulfuric acid solution to prepare manganese sulfate solution, and then an electrolyte solution is prepared through a series of processes such as neut...

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Problems solved by technology

[0006] 1. The reduction tail gas and calcination tail gas are directly discharged, one of which is to reduce the H in the tail gas 2 , CO and other components have not been utilized; secondly, the heat contained in the reduction tail gas and calcination tail gas has not been recycled, and the energy waste is serious

[0007] 2. Calcining manganese oxide ore with a fluidized calciner, the calcination time is longer, and a large amount of MnO 2 decomposed into Mn 2 o 3 , MnO 2 Decomposition reaction is an endothermic chemical reaction, see reaction formula (1), needs to consume a large amount of heat; MnO 2 Reduction reaction and Mn 2 o 3 The reduction reaction is an exothermic reaction, see reaction formula (2) and (3), but the heat release of reaction (2) has only 32% (same mass) of reaction (3), therefore, MnO 2 decomposed into Mn 2 o 3 Leads to a substantial increase in the heat requirements of the calcination and reduction processes

[0011] 3. The particle size of manganese oxide ore is relatively thick (<3.35mm), the internal mass transfer resistance is relatively large, and the reaction efficiency is low, resulting in low utilization rate of reducing gas

[0013] 1. The residence time of manganese oxide ore in the reduction furnace, that is, the reaction time, is only 5-10 seconds, so a higher reaction temperature (700-950°C) is required, and the temperature of manganese oxide ore obtained after reduction is 700-950°C ℃, discharged after cooling, manganese monoxide ore has a high temperature and contains a lot of heat, and this part of heat energy has not been recycled

[0014] 2. The reduction temperature is high, and some manganese-containing phases that are insoluble in sulfuric acid are formed

[0015] 3. The material in the reduction furnace is in a spray fluidized state, the residence time is short, and the back-mixing is serious, which is not conducive to improving the reduction rate

[0016] 4. The CO content in the reducing gas is 3-10%, the CO concentration is low and the reaction efficiency is low

[0017] 5. More than 90% of the reducing gas has no reducing effect, and part of the gas needs to be compressed and recycled, and the cycle compression process consumes a lot of energy

[0018] 6. The exhaust gas contains CO, which pollutes the environment and wastes energy

The main reasons for high energy consumption are: (1) low reduction efficiency: the utilization rate of the reducing agent is only 50% to 90%; (2) low comprehensive utilization rate of energy: direct discharge of high-temperature exhaust gas wastes CO and H in the exhaust gas 2 The energy contained in the components such as and the heat of the tail gas, the manganese monoxide ore obtained after reduction has brought out a large amount of heat; (3) the preheating stage MnO 2 The decomposition rate is high, which increases the energy consumption of preheating and reduces the heat released by the reduction reaction.

[0022] The low manganese leaching rate and high reduction energy consumption are the bottlenecks that limit the large-scale application of manganese oxide ore in the field of electrolytic manganese. Therefore, there is an urgent need in this field for a high-efficiency, low-consumption manganese oxide ore low-temperature reduction process to reduce reduction costs and improve manganese. The leaching rate makes manganese oxide ore more widely used in the field of electrolytic manganese

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