A method and system for producing manganese monoxide from pyrolusite

Abstract

The application discloses a method and system for preparing manganese monoxide by adopting pyrolusite, through pretreatment of pyrolusite such as pyrolysis, hydrothermal reaction and oxidation reaction, low-cost and high-efficiency conversion of manganese tetroxide and manganese sesquioxide contained in the pyrolusite into manganese dioxide is realized, the product quality of the manganese monoxide prepared through subsequent fluidization reduction is improved, and a foundation is laid for subsequent high-efficiency leaching of manganese. The released carbon dioxide in the fluidization reduction process of the pyrolusite is recycled to prepare the recyclable CO for reduction, the carbon resources are maximally utilized, and the carbon emission is greatly reduced. The method has the characteristics of simple process flow, excellent operation condition, low fossil energy consumption, small environmental pollution, good economic benefit and environmental benefit and the like, and is expected to open up a more stable and efficient way for development and utilization of the pyrolusite.

Description

Technical Field

[0001] This invention relates to manganese monoxide production and processing technology, specifically to a method and system for preparing manganese monoxide using pyrolusite, belonging to the field of manganese monoxide production and processing technology. Background Technology

[0002] Manganese ore is already a scarce resource in my country, with most existing resources being poor and only 6.43% rich in content. Furthermore, the resources often have high impurity levels. Therefore, it is essential to fully utilize these poor manganese oxide ore resources and improve the quality of manganese ore products. How to utilize these manganese oxide ore resources efficiently and at low cost to provide high-quality raw materials for electrolytic manganese metal has become a bottleneck restricting the development of the manganese industry.

[0003] Pyrolusite is a crucial raw material for the production of manganese sulfate, accounting for approximately 60% of the world's manganese sulfate production. Pyrolusite is insoluble in sulfuric acid and must be reduced to manganese monoxide (MnO) before it can react with sulfuric acid to produce manganese sulfate. The traditional process involves roasting the pyrolusite using coal as a reducing agent to convert MnO2 to MnO, followed by sulfuric acid leaching. However, this method suffers from high energy consumption, poor operating conditions, and significant environmental pollution. The two-ore roasting method also has many drawbacks. For example, the pyrolusite roasting process converts MnO2 to MnSO4 and FeS2 to Fe2O3, followed by water leaching. This requires prolonged roasting at a high sulfur-to-manganese ratio, resulting in insufficient utilization of FeS2, large slag volume that is difficult to handle, and problems with flue gas treatment. Direct acid leaching often suffers from low manganese leaching rates, difficult slag treatment, and high sulfuric acid consumption.

[0004] In my country, the main process for producing manganese sulfate from pyrolusite (MnO2·nH2O) is reduction roasting-sulfuric acid leaching-concentration crystallization. Traditional reduction roasting equipment for manganese monoxide production uses a conventional reverberatory furnace, which suffers from high heat consumption, small bed capacity, low manganese recovery rate, and poor working conditions. In the 1980s, rotary kilns were built in Yunnan, western Hunan, and Guangdong to attempt this process, but due to the fine particle size of the raw materials, structural and technical issues with the rotary kilns, severe adhesion occurred within the kiln, rendering most of the kilns unusable for production. A heat recovery microwave reduction roasting process for manganese oxide ore, developed in recent years, uses a microwave heating furnace. However, due to high power consumption (210-240 kW·h) and coal consumption (180 kg / ton), as well as unresolved issues regarding the microwave source, processing capacity, and labor protection, it is currently difficult to promote and apply in production. Summary of the Invention

[0005] To address the problems of high energy consumption, low manganese recovery rate, and serious environmental pollution associated with the preparation of manganese monoxide from pyrolusite in existing technologies, this invention provides a method and system for preparing manganese monoxide from pyrolusite. By pretreating the pyrolusite, almost all manganese elements in different valence states are converted into manganese dioxide. Then, a fluidized bed reduction roasting method is used to directly reduce manganese dioxide to manganese monoxide under a reducing atmosphere. This method features high production efficiency, high manganese recovery rate, low energy consumption, and minimal environmental pollution.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is specifically as follows:

[0007] According to a first embodiment of the present invention, a method for preparing manganese monoxide using pyrolusite is provided:

[0008] A method for preparing manganese monoxide using pyrolusite, the method comprising the following steps:

[0009] 1) Manganese ore powder is obtained by crushing and grinding soft manganese ore and then pyrolyzing it.

[0010] 2) First, add water to the manganese ore powder and heat it to react. Then, raise the temperature and introduce oxygen-containing gas to react, thus obtaining the manganese monoxide precursor.

[0011] 3) Manganese monoxide is obtained by mixing and reacting the manganese monoxide precursor with a reducing agent.

[0012] Preferably, in step 1), the pyrolysis temperature is 900-1000℃, more preferably 930-980℃, and even more preferably 950-970℃. The heat treatment time is no more than 10 min, preferably 0.5-8 min, and even more preferably 1-5 min (the reaction time is generally sufficient for manganese trioxide to be basically converted into manganese tetroxide, during which a small amount of manganese dioxide will also be converted into manganese tetroxide).

[0013] Preferably, in step 1), the particle size of the manganese ore powder is no greater than 1 mm, preferably 0.1-0.9 mm, and more preferably 0.15-0.8 mm.

[0014] Preferably, in step 1), the oxygen content in the atmosphere during pyrolysis is not higher than 10 wt%, preferably not higher than 5 wt%, and more preferably not higher than 3 wt%.

[0015] Preferably, in step 2), the water added to the manganese ore powder is hot water or steam at a temperature not lower than 80°C.

[0016] Preferably, in step 2), the reaction temperature after heating is 80-200℃, preferably 90-180℃, and more preferably 100-150℃. The reaction time is 1-60 min, preferably 3-45 min, and more preferably 5-30 min (the reaction time is generally sufficient for manganese tetroxide to be essentially converted into MnOOH).

[0017] Preferably, in step 2), the oxygen-containing gas is a gas with an oxygen content of not less than 20 wt%, more preferably a gas with an oxygen content of not less than 40 wt%, and more preferably a gas with an oxygen content of not less than 60 wt%.

[0018] Preferably, in step 2), the reaction temperature after heating is 200-500℃, more preferably 230-400℃, and even more preferably 260-350℃. The reaction time is 1-120 min, more preferably 5-90 min, and even more preferably 8-60 min (the reaction time is generally long enough for MnOOH to be essentially converted into manganese dioxide).

[0019] Preferably, in step 3), the reducing agent is biochar and / or a reducing gas, preferably a mixed reducing gas containing CO and / or hydrogen.

[0020] Preferably, in step 3), the temperature of the mixing reaction is 500-1200℃, more preferably 550-1000℃, and even more preferably 600-900℃. The reaction time is 0.1-3h, more preferably 0.3-2.5h, and even more preferably 0.5-2h.

[0021] Preferably, the mixing reaction is a fluidized bed mixing reaction. The content of CO and / or hydrogen in the mixed reducing gas is 3-15 wt%, preferably 5-10 wt%, and the remaining gas is nitrogen. The flow rate of the mixed reducing gas is 0.2-2 m / s, preferably 0.3-1.8 m / s.

[0022] According to a second embodiment of the present invention, a system for preparing manganese monoxide using pyrolusite is provided:

[0023] A system for preparing manganese monoxide from pyrolusite, or a system for the first embodiment, is provided. The system includes a crushing and grinding unit, a pyrolysis unit, a hydrothermal reaction unit, an oxidation reaction unit, and a reduction reaction unit. The crushing and grinding unit, pyrolysis unit, hydrothermal reaction unit, oxidation reaction unit, and reduction reaction unit are arranged in series.

[0024] Preferably, the crushing and grinding device includes a crusher, a grinding mill, and a screening machine. The crusher, grinding mill, and screening machine are arranged in series. The undersize material outlet of the screening machine is connected to the feed end of the pyrolysis device through a conveying mechanism, and the oversize material outlet of the screening machine is connected to the feed end of the grinding mill through a return material mechanism.

[0025] Preferably, the screen aperture of the screening machine is no larger than 1 mm, and more preferably 0.5-1 mm.

[0026] Preferably, the pyrolysis device is one of a pyrolysis furnace, a rotary kiln, or a pyrolysis furnace tube.

[0027] Preferably, the hydrothermal reaction device and the oxidation reaction device are each independently one of a reaction vessel, a reaction tank, a reaction tower, or a reaction tube (furnace tube).

[0028] Preferably, the reduction reaction device is a vertical fluidized bed reduction furnace (generally equipped with an internal electric heating device), with a reduction feed port connected to the discharge end of the oxidation reaction device at the lower part of the side wall of the reduction furnace, a reduction gas inlet at the bottom wall of the reduction furnace, and a reduction discharge port at the top of the reduction furnace.

[0029] Preferably, the pyrolysis device, hydrothermal reaction device, and oxidation reaction device are arranged from top to bottom on the outside of the side wall of the reduction reaction device, and are connected in series to form a three-section reaction furnace tube. A protective gas inlet and outlet are provided on the wall of the upper section (pyrolysis device section) of the furnace tube corresponding to pyrolysis; a steam inlet and outlet are provided on the wall of the middle section (hydrothermal reaction device section) of the furnace tube corresponding to hydrothermal reaction; and an oxygen-containing gas inlet and outlet are provided on the wall of the lower section (oxidation device section, whose outlet is connected to the reduction inlet of the reduction reaction device). Preferably, the reaction furnace tube is spirally coiled from top to bottom on the outside of the side wall of the reduction reaction device.

[0030] Preferably, the system also includes a material water cooling device. The feed end of the material water cooling device is connected to the reduction discharge port via a discharge pipe.

[0031] Preferably, the system further includes a reducing gas generator, the inlet of which is connected to the upper chamber of the reduction reaction device via a suction pipe, and the outlet of which is connected to the reducing gas inlet via an exhaust pipe. A carbon powder adding pipe is also provided on the reducing gas generator. Preferably, a gas composition detector is also provided in the upper chamber of the reduction reaction device. A filter is provided at the inlet end of the suction pipe.

[0032] In this invention, manganese monoxide is produced by fluidized bed reduction roasting using pyrolusite as raw material. The fluidized bed rapid preheating and reduction reaction, which has high-efficiency mass and heat transfer characteristics, has many advantages, eliminating the cumbersome agglomeration process. Compared with traditional reduction roasting technology, its biggest difference lies in changing the original packed gas-solid heat exchange and mass transfer to a suspended gas-solid transfer process. After the material enters the reduction furnace tube, it forms a suspension under the action of the tangential wind force of the cyclone. The transfer process in the dilute phase suspension state has the following advantages over the transfer process in the packed state: ① larger transfer area; ② larger comprehensive transfer coefficient; ③ larger transfer power. The fluidized bed reduction roasting of pyrolusite to produce manganese monoxide is a gas-solid phase non-catalytic reaction. Due to the high density, small porosity, fast reaction rate, and solid product formation of pyrolusite, the entire reaction process of a single particle can be described by the unreacted core contraction model with constant particle size. The macroscopic rate of roasting is related not only to the chemical rate but also to heat and mass transfer. In actual production, the total reaction rate is mainly determined by the reaction temperature, particle size, relative velocity of the gas and solid phases, and gas-solid phase contact area. The fundamental ways to improve the reaction rate are to increase the reaction temperature, reduce the particle size of the ore, and increase the relative velocity of the gas and ore particles. The preparation of manganese monoxide by fluidized bed reduction roasting of pyrolusite using electric heating has the characteristics of low fossil energy consumption, stable product quality, high quality, and environmental friendliness.

[0033] In this invention, the reducing agent used in the fluidized bed reduction roasting of pyrolusite is generally a reducing gas, such as CO or hydrogen. Hydrogen, as a clean energy source, avoids generating waste gas and polluting the environment, but it is relatively expensive. Therefore, CO is generally used as the gaseous reducing medium, and the reduction of 1 mol MnO2 emits approximately 1 mol CO2, resulting in a large carbon emission. To address the drawback of high carbon emissions in the fluidized bed reduction process of pyrolusite caused by using CO as the reducing medium, the proposed solution is to collect the CO2 emitted from the reduction reaction into a gas storage tank (i.e., a reducing gas generator). A small amount of solid carbon powder is introduced into the tank, causing it to undergo a Bourdelle reaction with the CO2 gas to generate CO gas (C + CO2 = 2CO). The reducing gas is then returned to the fluidized bed reduction system of pyrolusite, and this process is repeated to achieve carbon recycling and reduce the system's carbon emissions. First, the reduction roasting furnace tubes and pipes are cleaned by blowing inert nitrogen gas. Then, a certain weight of pyrolusite raw material is added into the roasting furnace tubes through the reduction feed inlet at the bottom. A mixture of CO and nitrogen is used as the fluidizing gas, and roasting is carried out according to the set fluidized reduction roasting temperature, time, and gas fluidization rate (the reducing gas enters the system from the bottom of the furnace tubes at a certain airflow rate, and the direction of operation is from bottom to top; the pyrolusite is suspended in the furnace tubes under the blowing of the airflow, and reacts with CO at high temperature to generate MnO, and CO2 gas is emitted during the reaction process). After the reaction is completed, the gas fluidization rate is increased, and the material is blown into the reduction outlet by the gas and enters the material water cooling device for cooling. After water cooling, MnO is obtained for hydrometallurgy. The gas generated during the reaction is transported to the gas reaction tank through the gas pipeline (i.e., the exhaust pipe) at the top of the furnace tubes, and a small amount of solid carbon powder is introduced to convert CO2 into CO before returning it to the system. This method utilizes the characteristics of fluidized bed reduction of pyrolusite, which requires a low CO concentration (generally 3-10 wt%) and the ability of emitted CO2 to react with carbon powder to regenerate reducing gas CO. Only a small amount of carbon powder is needed to continuously carry out the reduction reaction of pyrolusite, realizing the recycling and efficient utilization of carbon. 1 mol of carbon resource can reduce 10-33 mol of pyrolusite after recycling, maximizing the utilization of carbon resources and significantly reducing carbon emissions.

[0034] In this invention, a gas composition detector is also installed in the upper chamber of the reduction reaction device. The gas composition detector monitors the CO content in the gas above the furnace tube in real time. When the detected CO concentration is between 3-10 wt%, it meets the requirements for fluidized bed reduction of pyrolusite, and the amount of C powder added to the reducing gas generator remains unchanged. When the detected CO concentration is <3 wt%, the reducing gas content in the system is insufficient, and the amount of C powder needs to be increased by b = 5.0 * (a + 3) * 100%. When the detected CO concentration is >10 wt%, the reducing gas content in the system is excessive, and the amount of C powder needs to be reduced by b = 3.0 * (a + 1) * 100%. The C powder used in this invention is coal powder, coke, graphite powder, etc., with a fixed carbon content ≥60 wt% and a particle size of -1 mm, preferably coke powder.

[0035] In this invention, during the fluidized bed reduction roasting process of pyrolusite, it was found that although fluidized bed reduction roasting can quickly and efficiently reduce manganese dioxide to manganese monoxide, some manganese in intermediate valence states (such as manganese tetroxide and manganese trioxide) still exist in pyrolusite. Compared with manganese dioxide, manganese tetroxide and manganese trioxide have relatively weak oxidizing properties and react with reducing gas relatively slowly. Moreover, manganese tetroxide and manganese trioxide are both relatively stable oxides of manganese and are difficult to be directly reduced to manganese monoxide (in addition, research has shown that it is also difficult to completely convert manganese trioxide and manganese tetroxide into manganese dioxide through high-temperature oxidation). This results in a certain amount of manganese tetroxide and manganese trioxide remaining in the reduction product, which affects the product quality and reduces the subsequent leaching efficiency of manganese elements. Therefore, in this invention, by pretreating the pyrolusite, the manganese tetroxide and manganese trioxide contained therein are first converted into manganese dioxide and then reduced and roasted with reducing gas, thereby obtaining a higher quality manganese monoxide product and ensuring the subsequent leaching efficiency of manganese elements.

[0036] In this invention, the pretreatment steps for pyrolusite include crushing and grinding, pyrolysis, hydrothermal reaction, and oxidation reaction. Crushing and grinding refines the pyrolusite into powder. The powdered mineral powder facilitates the rapid progress of pyrolysis, hydrothermal reaction, and oxidation reaction, and also provides a basis for subsequent fluidized bed reduction roasting. The refined manganese ore powder is first subjected to pyrolysis treatment. This involves thermally decomposing manganese trioxide into manganese trioxide and releasing oxygen in an oxygen-deficient (or oxygen-free) environment (filled with nitrogen or under vacuum) at high temperature (900-100℃). At the same time, a small amount of manganese dioxide is also pyrolyzed into manganese trioxide (MnO2→Mn3O4+O2). It should be noted that the pyrolysis temperature should not be too low, otherwise the pyrolysis of manganese trioxide will be incomplete, and manganese dioxide will be converted into manganese trioxide incompletely. If the pyrolysis temperature is too high, the pyrolysis cost will increase and more manganese dioxide will be pyrolyzed, increasing the difficulty of subsequent processing. After pyrolysis, the manganese trioxide in the pyrolusite is basically converted into manganese trioxide (sampling and testing results show that the manganese trioxide content is below the detection limit). Therefore, the manganese trioxide is further converted into MnOOH (Mn3O4 + MnO2 + H2O → MnOOH) through a hydrothermal reaction under the oxidation of manganese dioxide. That is, in a water-containing environment (by introducing steam or placing it directly in hot water) at a temperature of 80-200℃, manganese dioxide (or other oxidants, but manganese dioxide is used here because the raw material itself contains manganese) is used. The oxidation process, which utilizes manganese dioxide (which avoids introducing new impurities and reduces costs), almost completely converts manganese tetroxide (MnOOH) into MnOOH. Further, the MnOOH-containing material is oxidized to manganese dioxide. The oxidation temperature is 200-500℃, and the oxidant is an oxygen-containing gas (such as air or an oxygen-enriched gas). During the oxidation reaction, the temperature should not be too high, otherwise MnOOH will easily convert to manganese trioxide (MnO2). If the temperature is too low, the oxidation will be incomplete, leaving MnOOH residue. In other words, this invention, through the combined action of pyrolysis, hydrothermal reaction, and oxidation reaction, essentially converts the manganese element in pyrolusite into manganese dioxide, improving the efficiency and product quality of subsequent reduction to obtain manganese monoxide, while also facilitating the leaching and recovery of manganese.

[0037] In this invention, the pyrolysis device used for the pyrolysis reaction is one of a pyrolysis furnace, a rotary kiln, or a pyrolysis furnace tube. The hydrothermal reaction device used for the hydrothermal reaction and the oxidation reaction device used for the oxidation reaction are each independently one of a reaction vessel, a reaction tank, a reaction tower, or a reaction tube. The pyrolysis device, hydrothermal reaction device, and oxidation reaction device can be set up independently or connected in series as a single unit, for example, a three-section reaction furnace tube (including a pyrolysis section, a hydrothermal reaction section, and an oxidation reaction section, each section having independent gas inlet and outlet and independently equipped with an electric heating device) connected in series. In a preferred embodiment, the reaction furnace tube, composed of the pyrolysis device, the hydrothermal reaction device, and the oxidation reaction device, is spirally coiled from top to bottom around the side wall of the reduction reaction device. That is, the material after crushing and grinding passes sequentially through the pyrolysis section, the hydrothermal reaction section, and the oxidation reaction section of the reaction furnace tube before entering the reduction reaction device for reduction. The entire process is continuous and uninterrupted, requiring no intermediate transfer, greatly improving production efficiency while saving equipment investment and space occupation.

[0038] In this invention, the diameter of the three-section reactor tube, which comprises the pyrolysis device, the hydrothermal reaction device, and the oxidation reaction device, is 0.1-10 m, preferably 0.2-8 m, and more preferably 0.3-6 m. The inner diameter of the reducing gas generating device is 0.2-20 m, preferably 0.3-15 m, and more preferably 0.5-12 m.

[0039] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0040] 1. This invention pre-treats pyrolusite through pyrolysis, hydrothermal reaction, and oxidation reaction, converting manganese tetroxide and manganese trioxide contained in pyrolusite into manganese dioxide in a low cost and high efficiency, thereby improving the quality of manganese monoxide products in subsequent fluidized bed reduction and laying the foundation for efficient subsequent leaching of manganese.

[0041] 2: This invention recycles the carbon dioxide released during the fluidized reduction process of pyrolusite by means of electrothermal heating, and further prepares CO that can be recycled for reduction, thereby maximizing the utilization of carbon resources and significantly reducing carbon emissions.

[0042] 3. The process flow of this invention is simple, the operating conditions are excellent, the consumption of fossil energy is low, and the environmental pollution is minimal. The overall system structure of this invention is simple, easy to operate, requires little equipment investment, and occupies little space. It has the advantage of large-scale promotion and has good economic and environmental benefits, and is expected to open up a more stable and efficient way for the development and utilization of pyrolusite. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0044] Figure 2 This is a schematic diagram of the overall structure of the system described in this invention.

[0045] Figure 3 This is a schematic diagram of the structure of the pyrolysis device, hydrothermal reaction device, and oxidation reaction device of the present invention, which are arranged in series on the outer wall of the reduction reaction device.

[0046] Figure 4 This is a schematic diagram of the structure of a three-section reaction furnace tube that together form a spiral, consisting of a pyrolysis device, a hydrothermal reaction device, and an oxidation reaction device.

[0047] Reference numerals in the attached figures: 1: Crushing and grinding device; 101: Crusher; 102: Grinding mill; 103: Screening machine; 2: Pyrolysis device; 3: Hydrothermal reaction device; 4: Oxidation reaction device; 5: Reduction reaction device; 501: Reduction feed inlet; 502: Reduction gas inlet; 503: Reduction discharge outlet; 6: Material water cooling device; 7: Reduction gas generator; 701: Carbon powder addition pipeline; 8: Gas composition detector; 9: Filter. Detailed Implementation

[0048] The technical solution of the present invention will be illustrated below with examples. The scope of protection sought by the present invention includes, but is not limited to, the following embodiments.

[0049] A system for preparing manganese monoxide from pyrolusite includes a crushing and grinding unit 1, a pyrolysis unit 2, a hydrothermal reaction unit 3, an oxidation reaction unit 4, and a reduction reaction unit 5. The crushing and grinding unit 1, the pyrolysis unit 2, the hydrothermal reaction unit 3, the oxidation reaction unit 4, and the reduction reaction unit 5 are connected in series.

[0050] Preferably, the crushing and grinding device 1 includes a crusher 101, a grinding mill 102, and a screening machine 103. The crusher 101, grinding mill 102, and screening machine 103 are arranged in series. The undersize material outlet of the screening machine 103 is connected to the feed end of the pyrolysis device 2 through a conveying mechanism, and the oversize material outlet of the screening machine 103 is connected to the feed end of the grinding mill 102 through a return material mechanism.

[0051] Preferably, the screen aperture of the screening machine 103 is no greater than 1 mm, and more preferably 0.5-1 mm.

[0052] Preferably, the pyrolysis device 2 is one of a pyrolysis furnace, a rotary kiln, or a pyrolysis furnace tube.

[0053] Preferably, the hydrothermal reaction device 3 and the oxidation reaction device 4 are each independently one of a reaction vessel, a reaction tank, a reaction tower, and a reaction tube.

[0054] Preferably, the reduction reaction device 5 is a vertical fluidized bed reduction furnace, with a reduction feed port 501 connected to the discharge end of the oxidation reaction device 4 at the lower part of the side wall of the reduction furnace, a reduction gas inlet 502 at the bottom wall of the reduction furnace, and a reduction discharge port 503 at the top of the reduction furnace.

[0055] Preferably, the pyrolysis device 2, hydrothermal reaction device 3, and oxidation reaction device 4 are arranged from top to bottom on the outside of the side wall of the reduction reaction device 5, and are connected in series to form a three-section reaction furnace tube. A protective gas inlet and outlet are provided on the upper section of the furnace tube corresponding to the pyrolysis reaction, a steam inlet and outlet are provided on the middle section of the furnace tube corresponding to the hydrothermal reaction, and an oxygen-containing gas inlet and outlet are provided on the lower section of the furnace tube corresponding to the oxidation reaction. Preferably, the reaction furnace tube is spirally coiled from top to bottom on the outside of the side wall of the reduction reaction device 5.

[0056] Preferably, the system also includes a material water cooling device 6. The feed end of the material water cooling device 6 is connected to the reduction discharge port 503 via a discharge pipe.

[0057] Preferably, the system further includes a reducing gas generator 7, the inlet of which is connected to the upper chamber of the reduction reaction device 5 via a suction pipe, and the outlet of which is connected to the reducing gas inlet 502 via an exhaust pipe. A carbon powder adding pipe 701 is also provided on the reducing gas generator 7. Preferably, a gas composition detector 8 is also provided in the upper chamber of the reduction reaction device 5. A filter 9 is provided at the inlet end of the suction pipe.

[0058] Example 1

[0059] like Figure 2-4 As shown, a system for preparing manganese monoxide from pyrolusite is disclosed. The system includes a crushing and grinding device 1, a pyrolysis device 2, a hydrothermal reaction device 3, an oxidation reaction device 4, and a reduction reaction device 5. The crushing and grinding device 1, the pyrolysis device 2, the hydrothermal reaction device 3, the oxidation reaction device 4, and the reduction reaction device 5 are arranged in series.

[0060] Example 2

[0061] The embodiment 1 is repeated, except that the crushing and grinding device 1 includes a crusher 101, a grinding mill 102, and a screening machine 103. The crusher 101, grinding mill 102, and screening machine 103 are arranged in series. The undersize material outlet of the screening machine 103 is connected to the feed end of the pyrolysis device 2 through a conveying mechanism, and the oversize material outlet of the screening machine 103 is connected to the feed end of the grinding mill 102 through a return material mechanism.

[0062] Example 3

[0063] Example 2 is repeated, except that the sieve aperture of the screening machine 103 is 0.8 mm.

[0064] Example 4

[0065] Repeat Example 3, except that the sieve aperture of the screening machine 103 is 1 mm.

[0066] Example 5

[0067] Example 4 is repeated, except that the pyrolysis device 2 is a pyrolysis furnace.

[0068] Example 6

[0069] Example 5 is repeated, except that the pyrolysis device 2 is a pyrolysis furnace tube.

[0070] Example 7

[0071] Example 6 is repeated, except that the hydrothermal reaction device 3 and the oxidation reaction device 4 are each a separate reaction vessel.

[0072] Example 8

[0073] Example 7 is repeated, except that the hydrothermal reaction device 3 and the oxidation reaction device 4 are each a separate reaction tube.

[0074] Example 9

[0075] Example 8 is repeated, except that the reduction reaction device 5 is a vertical fluidized bed reduction furnace. A reduction feed port 501 connected to the discharge end of the oxidation reaction device 4 is provided on the lower side wall of the reduction furnace, a reduction gas inlet 502 is provided on the bottom wall of the reduction furnace, and a reduction discharge port 503 is provided on the top of the reduction furnace.

[0076] Example 10

[0077] Example 9 is repeated, except that the pyrolysis device 2, hydrothermal reaction device 3, and oxidation reaction device 4 are arranged from top to bottom on the outside of the side wall of the reduction reaction device 5, and the pyrolysis device 2, hydrothermal reaction device 3, and oxidation reaction device 4 are connected in series to form a three-section reaction furnace tube. A protective gas inlet and outlet are opened on the upper section of the furnace tube corresponding to pyrolysis, a water vapor inlet and outlet are opened on the middle section of the furnace tube corresponding to hydrothermal reaction, and an oxygen-containing gas inlet and outlet are opened on the lower section of the furnace tube corresponding to oxidation reaction.

[0078] Example 11

[0079] Repeat Example 10, except that the reactor tube is spirally coiled from top to bottom on the outside of the side wall of the reduction reaction device 5.

[0080] Example 12

[0081] The system repeats Example 11, except that it also includes a material water cooling device 6. The feed end of the material water cooling device 6 is connected to the reduction discharge port 503 via a discharge pipe.

[0082] Example 13

[0083] The system repeats Embodiment 12, except that it also includes a reducing gas generator 7. The inlet of the reducing gas generator 7 is connected to the upper chamber of the reduction reaction device 5 via a suction pipe, and the outlet of the reducing gas generator 7 is connected to the reducing gas inlet 502 via an exhaust pipe. A carbon powder adding pipe 701 is also provided on the reducing gas generator 7.

[0084] Example 14

[0085] Example 13 is repeated, except that a gas composition detector 8 is also provided in the upper chamber of the reduction reaction device 5. A filter 9 is provided at the inlet end of the extraction pipe.

[0086] Example 15

[0087] like Figure 1 As shown, a method for preparing manganese monoxide using pyrolusite includes the following steps:

[0088] 1) Manganese ore powder is obtained by crushing and grinding soft manganese ore and then pyrolyzing it.

[0089] 2) First, add water to the manganese ore powder and heat it to react. Then, raise the temperature and introduce oxygen-containing gas to react, thus obtaining the manganese monoxide precursor.

[0090] 3) Manganese monoxide is obtained by mixing and reacting the manganese monoxide precursor with a reducing agent.

[0091] In step 1), the pyrolysis temperature is 950°C. The pyrolysis time is 4 minutes. The oxygen content in the atmosphere during pyrolysis is no higher than 8 wt%.

[0092] In step 2), the water added to the manganese ore powder is steam. The reaction temperature after heating is 110°C, and the reaction time is 8 minutes. The oxygen-containing gas is a gas with an oxygen content of 35 wt% (the remainder is nitrogen). The reaction temperature after heating is 265°C, and the reaction time is 6 minutes.

[0093] In step 3), the reducing agent is a mixed reducing gas with a content of 8 wt% CO (the remainder being nitrogen), the flow rate of the mixed reducing gas is 1.5 m / s, the mixing reaction temperature is 900℃, and the reaction time is 25 min.

[0094] Comparative Example 1

[0095] The manganese ore powder obtained after crushing and grinding pyrolusite was directly fed into a fluidized bed reduction furnace for reduction treatment. The reducing agent introduced was a mixed reducing gas with a content of 8 wt% CO (the remainder being nitrogen), the flow rate of the mixed reducing gas was 1.5 m / s, the mixing reaction temperature was 900℃, and the reaction time was 25 min.

[0096] The results showed that the purity of manganese monoxide obtained by reducing pyrolusite using Example 15 was 96.2 wt%, while the purity of manganese monoxide obtained by reducing pyrolusite using Comparative Example 1 was 78.7 wt%.

[0097] In other words, compared with directly using reducing gas to reduce pyrolusite, the purity of the manganese monoxide product obtained in Example 15 is increased by 17.5%.

Claims

1. A method for preparing manganese monoxide using pyrolusite, characterized in that: The method includes the following steps: 1) Manganese ore powder is obtained by crushing and grinding pyrolysis of pyrolysis ore. The pyrolysis temperature is 900-1000℃, the pyrolysis time does not exceed 10 minutes, the particle size of the manganese ore powder is not greater than 1 mm, and the oxygen content in the atmosphere during pyrolysis is not higher than 10 wt%. 2) First, add water to the manganese ore powder and heat it to carry out the reaction. The water added to the manganese ore powder is hot water or steam at a temperature of not less than 80℃. The reaction temperature after heating is 80-200℃, and the reaction time is 1-60 min. Then, raise the temperature and introduce oxygen-containing gas to carry out the reaction. The oxygen-containing gas is a gas with an oxygen content of not less than 20wt%. The reaction temperature after heating is 200-500℃, and the reaction time is 1-120 min. The manganese monoxide precursor is obtained. 3) Manganese monoxide is obtained by mixing manganese monoxide precursor with a reducing agent. The mixing reaction is a fluidized bed reaction. The reducing agent is a mixed reducing gas containing CO. The CO content in the mixed reducing gas is 3-15 wt%, and the remaining gas is nitrogen. The temperature of the mixing reaction is 500-1200℃. The reaction time is 0.1-3h.

2. The method according to claim 1, characterized in that: In step 1), the pyrolysis temperature is 930-980℃; the pyrolysis time is 0.5-8 min; and / or In step 1), the particle size of the manganese ore powder is 0.1-0.9 mm.

3. The method according to claim 2, characterized in that: In step 1), the pyrolysis temperature is 950-970℃; the pyrolysis time is 1-5 min; and / or In step 1), the particle size of the manganese ore powder is 0.15-0.8 mm.

4. The method according to claim 1, characterized in that: In step 1), the oxygen content in the atmosphere during pyrolysis is not higher than 5 wt%.

5. The method according to claim 4, characterized in that: In step 1), the oxygen content in the atmosphere during pyrolysis is no higher than 3 wt%.

6. The method according to claim 1, characterized in that: In step 2), the reaction temperature after heating is 90-180℃; the reaction time is 3-45 min.

7. The method according to claim 6, characterized in that: In step 2), the reaction temperature after heating is 100-150℃; the reaction time is 5-30 min.

8. The method according to claim 1, characterized in that: In step 2), the oxygen-containing gas is a gas with an oxygen content of not less than 40 wt%; and / or In step 2), the reaction temperature after heating is 230-400℃; the reaction time is 5-90 min.

9. The method according to claim 8, characterized in that: In step 2), the oxygen-containing gas is a gas with an oxygen content of not less than 60 wt%; and / or In step 2), the reaction temperature after heating is 260-350℃; the reaction time is 8-60 min.

10. The method according to claim 1, characterized in that: In step 3), the temperature of the mixed reaction is 550-1000℃; the reaction time is 0.3-2.5h.

11. The method according to claim 10, characterized in that: In step 3), the temperature of the mixed reaction is 600-900℃; the reaction time is 0.5-2h.

12. The method according to claim 1, characterized in that: The CO content in the mixed reducing gas is 5-10 wt%, and the remaining gas is nitrogen; the flow rate of the mixed reducing gas is 0.2-2 m / s.

13. The method according to claim 12, characterized in that: The flow rate of the mixed reducing gas is 0.3-1.8 m / s.

14. A system for use in the method according to any one of claims 1-13, characterized in that: The system includes a crushing and grinding device (1), a pyrolysis device (2), a hydrothermal reaction device (3), an oxidation reaction device (4), and a reduction reaction device (5); the crushing and grinding device (1), the pyrolysis device (2), the hydrothermal reaction device (3), the oxidation reaction device (4), and the reduction reaction device (5) are connected in series. The crushing and grinding device (1) includes a crusher (101), a grinding mill (102), and a screening machine (103); the crusher (101), the grinding mill (102), and the screening machine (103) are connected in series; the undersize material outlet of the screening machine (103) is connected to the feed end of the pyrolysis device (2) through a conveying mechanism, and the oversize material outlet of the screening machine (103) is connected to the feed end of the grinding mill (102) through a return material mechanism; the reduction reaction device (5) is a vertical fluidized bed reduction furnace, with a reduction feed inlet (501) connected to the discharge end of the oxidation reaction device (4) at the lower part of the side wall of the reduction furnace, and a reduction gas inlet (502) on the bottom wall of the reduction furnace. A reduction discharge port (503) is provided at the top of the reduction furnace; the pyrolysis device (2), hydrothermal reaction device (3), and oxidation reaction device (4) are arranged from top to bottom outside the side wall of the reduction reaction device (5), and the pyrolysis device (2), hydrothermal reaction device (3), and oxidation reaction device (4) are connected in series to form a three-section reaction furnace tube. A protective gas inlet and outlet are provided on the upper section of the furnace tube corresponding to the pyrolysis, a water vapor inlet and outlet are provided on the middle section of the furnace tube corresponding to the hydrothermal reaction, and an oxygen-containing gas inlet and outlet are provided on the lower section of the furnace tube corresponding to the oxidation reaction; the reaction furnace tube is spirally coiled from top to bottom outside the side wall of the reduction reaction device (5).

15. The system according to claim 14, characterized in that: The sieve aperture of the screening machine (103) is no greater than 1 mm.

16. The system according to claim 15, characterized in that: The sieve aperture of the screening machine (103) is 0.5-1mm.

17. The system according to claim 14, characterized in that: The pyrolysis device (2) is one of the following: a pyrolysis furnace, a rotary kiln, or a pyrolysis furnace tube; and / or The hydrothermal reaction device (3) and the oxidation reaction device (4) are each independently one of the following: reaction vessel, reaction tank, reaction tower, and reaction tube.

18. The system according to claim 14, characterized in that: The system also includes a material water cooling device (6); the feed end of the material water cooling device (6) is connected to the reduction discharge port (503) via a discharge pipe; and / or The system also includes a reducing gas generator (7), the inlet of which is connected to the upper chamber of the reducing reaction device (5) through a suction pipe, and the outlet of the reducing gas generator (7) is connected to the reducing gas inlet (502) through an exhaust pipe; a carbon powder adding pipe (701) is also provided on the reducing gas generator (7).

19. The system according to claim 18, characterized in that: A gas composition detector (8) is also provided in the upper chamber of the reduction reaction device (5); a filter (9) is provided at the inlet end of the extraction pipe.

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