Method for oxidizing molybdenite and synchronously fixing sulfur through high-iron manganese ore

Abstract

The invention discloses a method for oxidizing molybdenite and synchronously fixing sulfur through high-iron manganese ore, and belongs to the technical field of non-ferrous metallurgy smelting. The method comprises the following steps: respectively crushing high-iron manganese ore and molybdenite, grinding to predetermined fineness, sieving with a 200-mesh sieve, and stirring and mixing according to the molar ratio of manganese element to molybdenum disulfide, namely n (Mn): n (MoS2), of 1.0: 1-2.5: 1; then in a pure oxygen atmosphere, oxidizing roasting is carried out by adopting two-stage temperature control, heat preservation is carried out at the first stage of 440-460 DEG C, heat preservation is carried out at the second stage of 540-560 DEG C, molybdenum in molybdenite is oxidized, meanwhile, sulfur is fixed into sulfate, and a roasted product containing molybdenum oxide and manganese sulfate is obtained; according to the method, the oxidizability of MnO2 and the catalytic action of Fe2O3 in the high-iron manganese ore are utilized, sulfur is efficiently fixed into manganese sulfate while molybdenite is completely oxidized, the sulfur fixation rate can reach 80% or above, value-added utilization of two mineral resources is synchronously achieved, SO2 emission is greatly reduced, and the method has the advantages of being short in process, low in energy consumption, low in cost, environmentally friendly and the like.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metallurgical smelting technology, specifically to a method for oxidizing molybdenite from high-iron manganese ore and simultaneously fixing sulfur. Background Technology

[0002] Molybdenum, as an important strategic metal, is widely used in steel, chemical, and other fields. Molybdenite is the most important ore source for molybdenum smelting, with over 80% of global molybdenum production achieved through the "oxidative roasting-wet leaching" process. However, this traditional process generates large amounts of SO2 during roasting, causing severe air pollution and wasting sulfur resources. To address this issue, existing technologies have proposed adding sulfur-fixing agents during roasting, such as lime or soda. While this can achieve sulfur fixation to some extent, it suffers from limitations such as limited sulfur fixation rate, high roasting temperature, and poor adaptability to low-grade ores.

[0003] On the other hand, my country's manganese oxide ore resources generally exhibit a significant iron-manganese symbiosis, with high-iron manganese ore presenting a particular technical challenge in iron-manganese separation due to the fine-grained intergrowth and cementation of iron and manganese minerals. Traditional processing methods are energy-intensive and economically unsound. However, manganese in high-iron manganese ore primarily exists in the form of pyrolusite (MnO2), which has the highest MnO2 content and excellent reactivity. Therefore, co-roasting high-iron manganese ore with molybdenite can lower the reaction temperature of molybdenite through the catalytic oxidation of MnO2, reducing energy consumption, while also avoiding SO2 emissions that pollute the environment and waste sulfur resources.

[0004] Previous studies have shown that co-roasting manganese dioxide and molybdenite can fix sulfur into manganese sulfate through a chemical reaction, while simultaneously lowering the roasting temperature and promoting the decomposition of molybdenite. However, existing technologies all use high-purity pyrolusite as the manganese source and do not involve the utilization of high-iron manganese ore, which limits the economics and industrial application prospects of the process. Therefore, developing a process that can achieve the co-processing of high-iron manganese ore and molybdenite and simultaneous sulfur fixation is of significant practical importance. Summary of the Invention

[0005] Based on the above analysis, this invention provides a method for oxidizing molybdenite in high-iron manganese ore and simultaneously fixing sulfur. The process is simple, energy-efficient, and environmentally friendly, aiming to solve the problems of sulfur pollution from molybdenite roasting and poor utilization of high-iron manganese ore.

[0006] The technical solution of this invention is as follows: This invention provides a method for oxidizing molybdenite in high-iron manganese ore and simultaneously fixing sulfur, comprising the following steps: S1. Raw material pretreatment: crush and grind the high-iron manganese ore and molybdenite to the predetermined fineness and pass them through a 200-mesh sieve. S2. Mixing: The pretreated high-iron manganese ore powder and molybdenite powder are stirred and mixed in a ratio of manganese to molybdenum disulfide n(Mn): n(MoS2) = 1.0:1 ~ 2.5:1 to obtain mixed ore material; S3. Oxidative roasting: The mixed ore is placed in a roasting furnace and oxidized under an oxygen-containing atmosphere to oxidize the molybdenum in molybdenite and fix the sulfur into sulfate, thereby obtaining a roasting product containing molybdenum oxide and manganese sulfate.

[0007] This invention abandons the traditional end-of-pipe treatment model that requires the addition of expensive sulfur-fixing agents such as lime and soda during roasting. Instead, it uses high-iron manganese ore (mainly containing MnO2 and Fe2O3), which is usually difficult to separate and utilize economically, as an in-situ oxidant and sulfur-fixing agent, and co-roasts it with molybdenite. On the one hand, the strong oxidizing property of MnO2 is used to efficiently decompose molybdenite (MoS2) and fix the released sulfur into stable manganese sulfate (MnSO4), removing SO2 pollution at the source. On the other hand, the high-iron manganese ore itself is reduced, and the manganese in it is transformed from the insoluble MnO2 form into the water-soluble MnSO4, creating conditions for the subsequent wet recovery of manganese and realizing the simultaneous value-added of the two mineral resources.

[0008] Most importantly, this invention makes full use of the iron oxide (Fe2O3) associated with high-iron manganese ore. Studies have found that Fe2O3 is not an inert impurity in this co-calcination system. It promotes the catalytic oxidation of intermediate product SO2 to SO3, thereby accelerating the rate and extent of the reaction between SO3 and manganese oxide to generate more stable MnSO4. Its sulfur fixation effect is better than simply using chemically pure MnO2.

[0009] Further optimization is that, in step S1, the mass content of MnO2 in the high-iron manganese ore is not less than 35%, the mass content of Fe2O3 is not less than 16%, the sulfur content is less than 0.05%, and almost no additional SO2 pollution is generated; the mass content of molybdenite in the molybdenite is not less than 49%, of which the proportion of MoS2 is not less than 82%.

[0010] Further optimization is that, in step S1, after pretreatment, the proportion of particles smaller than 0.074 mm in the high-iron manganese ore powder reaches more than 80%; and the proportion of particles smaller than 0.074 mm in the molybdenite powder reaches more than 90%.

[0011] Further optimization is that, in step S1, the pretreatment of the high-iron manganese ore is specifically as follows: it is first coarsely crushed by a jaw crusher, and then fed into a ball mill for grinding for 20 to 30 minutes (preferably 25 minutes).

[0012] A further optimization is that, in step S1, the pretreatment of molybdenite specifically involves grinding it for 8 to 12 minutes (preferably 10 minutes) using an agate three-head grinder.

[0013] A further optimization is that the mixing in step S2 is achieved by mechanical stirring.

[0014] Further optimization lies in step S3, where the oxidation roasting is a two-stage roasting process, specifically including: the first stage roasting temperature is 440℃~460℃ (preferably 450℃), held for 1.5~2.5 hours (preferably 2 hours). The first stage (approximately 450℃) is a low-temperature pre-oxidation, designed to gently initiate the reaction, control the reaction rate, and avoid premature sintering of the material particle surface due to the exothermic oxidation of MoS2, thereby ensuring unobstructed channels for oxygen diffusion inward and product diffusion outward, and preferentially guiding the initial formation of Mn-S bonds; the second stage roasting temperature is 540℃~560℃ (preferably 550℃), held for 1.5~2.5 hours (preferably 2 hours). The second stage (approximately 550℃) is a high-temperature deep oxidation, which, based on the already formed favorable phase structure, ensures that molybdenum is completely oxidized to MoO3 and the residual sulfur is completely fixed, effectively overcoming the technical bottleneck of "hardened outer shell and unreacted core" that is easily caused by traditional one-step high-temperature roasting, and achieving a more uniform and thorough reaction inside the material.

[0015] Further optimization involves controlling the heating rate of the oxidative calcination to 8℃ / min ~ 12℃ / min (preferably 10℃ / min) and the cooling rate to 4℃ / min ~ 6℃ / min (preferably 5℃ / min).

[0016] A further optimization is that, in step S3, the oxygen-containing atmosphere is a pure oxygen atmosphere, and the gas flow rate is 150 mL / min ~ 200 mL / min.

[0017] A further optimization is that the oxidative roasting process is carried out under normal pressure.

[0018] The roasted product processed by this method has a high-value-added phase composition. Molybdenum mainly exists in the form of volatile MoO3 and stable ferric molybdate (Fe2(MoO4)3), while manganese is almost entirely converted into water-soluble MnSO4. This clear phase distribution provides a prerequisite for the efficient and clean separation of manganese (entering the solution) from molybdenum and iron (remaining in the slag) through a simple water immersion-filtration process, without generating secondary waste residue.

[0019] Based on the above technical solution, the advantages of the present invention compared with the prior art are as follows: (1) This invention utilizes the strong oxidizing properties of MnO2 in high-iron manganese ore to completely oxidize molybdenite while fixing the sulfur released during roasting into stable manganese sulfate in situ. The sulfur fixation rate can reach more than 80%, which greatly reduces SO2 emissions from the source and solves the sulfur pollution problem of traditional processes, thus achieving both economic and environmental benefits.

[0020] (2) For the first time, the synergistic resource utilization of high-iron manganese ore and molybdenite has been realized. This process not only processes molybdenite, but also converts the manganese in the difficult-to-process high-iron manganese ore into water-soluble manganese sulfate, creating favorable conditions for its subsequent wet recovery and simultaneously increasing the added value of the two mineral resources.

[0021] (3) By adopting a segmented low-temperature roasting process of 450-600℃, energy consumption can be reduced by more than 30% compared with traditional high-temperature roasting. At the same time, cheap high-iron manganese ore completely replaces expensive chemical pure soft manganese ore or lime and other desulfurizing agents, reducing raw material costs.

[0022] (4) The phase composition of the roasting product is clear. Molybdenum mainly exists in the form of MoO3 and iron molybdate, while manganese is converted into MnSO4. This product system provides an ideal premise for the efficient separation of manganese from molybdenum and iron through a simple water leaching process. The whole process is clean and no secondary waste is generated.

[0023] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments specifically pointed out in the description. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0025] Figure 2 The images show the XRD phase analysis of the calcination products from Examples 1-4. Detailed Implementation

[0026] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0027] Example 1

[0028] The main components of the raw materials, molybdenum concentrate and high-iron manganese ore, are shown in Tables 1 and 2. The Mo content in molybdenite is 49.62%, of which MoS2 accounts for 82.7%; the MnO2 content in high-iron manganese ore is 35.59%, the Fe2O3 content is 16.04%, and the sulfur content is only 0.04%, which hardly produces any additional SO2 pollution.

[0029] Table 1. Elemental analysis results of molybdenum concentrate / %

[0030]

[0031] Table 2 Component Analysis Results of High-Iron Manganese Ore / %

[0032]

[0033] High-iron manganese ore and molybdenite were crushed and ground separately. The high-iron manganese ore was crushed by a jaw crusher and then ground in a ball mill for 25 minutes. After passing through a 200-mesh sieve, high-iron manganese ore powder with a content of more than 80% of -0.074mm was obtained. The molybdenite was ground in an agate three-head mill for 10 minutes to obtain molybdenite powder with a content of more than 90% of -0.074mm. The two ores were mixed evenly according to the ratio of n(Mn):n(MoS2)=1.0:1 and placed in a corundum crucible. The crucible was placed in a roasting furnace, and oxygen was introduced at a flow rate of 175 mL / min for oxidative roasting. The temperature was controlled at 450℃ for 120 minutes and 550℃ for 120 minutes. The heating rate of the roasting furnace was 10℃ / min.

[0034] Phase analysis (XRD) and sulfur element detection (barium sulfate gravimetric method) were performed on the roasting products. The results showed that the oxidation rate of Mo was 100%, the sulfur fixation rate was 38.54%, and the main roasting products were molybdenum trioxide, ferric molybdate, and manganese sulfate.

[0035] Example 2

[0036] After crushing and grinding, the two ores were mixed in a ratio of n(Mn):n(MoS2)=1.5:1 and placed in a corundum crucible. The crucible was then placed in a roasting furnace, and oxygen was introduced at a flow rate of 175 mL / min for oxidative roasting. The temperature was controlled at 450℃ for 120 min and 550℃ for 120 min. The heating rate of the roasting furnace was 10℃ / min.

[0037] Phase analysis and sulfur element detection of the roasting products showed that the oxidation rate of Mo was 100%, the sulfur fixation rate was 59.29%, and the main roasting products were molybdenum trioxide, ferric molybdate, and manganese sulfate.

[0038] Example 3

[0039] The crushed and ground ores were mixed in a ratio of n(Mn):n(MoS2) = 2.0:1 and placed in a corundum crucible. The crucible was then placed in a roasting furnace, and oxygen was introduced at a flow rate of 175 mL / min for oxidative roasting. The temperature was controlled at 450℃ for 120 min and 550℃ for 120 min. The heating rate of the roasting furnace was 10℃ / min.

[0040] Phase analysis and sulfur element detection of the roasting products showed that the oxidation rate of Mo was 100%, the sulfur fixation rate was 70.53%, and the main roasting products were molybdenum trioxide, ferric molybdate, and manganese sulfate.

[0041] Example 4

[0042] The crushed and ground ores were mixed in a ratio of n(Mn):n(MoS2) = 2.5:1 and placed in a corundum crucible. The crucible was then placed in a roasting furnace, and oxygen was introduced at a flow rate of 175 mL / min for oxidative roasting. The temperature was controlled at 450℃ for 120 min and 550℃ for 120 min. The heating rate of the roasting furnace was 10℃ / min.

[0043] Phase analysis and sulfur element detection of the roasting products showed that the oxidation rate of Mo was 100%, the sulfur fixation rate was 82.31%, and the main roasting products were molybdenum trioxide, ferric molybdate, and manganese sulfate.

[0044] Example 5

[0045] The raw material preparation was the same as in Example 1, with high-iron manganese ore powder and molybdenite powder prepared separately. The two ore powders were weighed according to the ratio of n(Mn):n(MoS2) = 2.0:1. The mixture was placed in a high-energy planetary ball mill with a ball-to-material ratio of 10:1 and a rotation speed of 400 rpm for co-milling and activation for 30 minutes. The activated mixture was placed in a corundum crucible, oxygen was introduced (flow rate 175 mL / min), and a two-stage roasting program was performed (450℃ 120min + 550℃ 120min) with a heating rate of 10℃ / min.

[0046] Phase analysis and sulfur element detection of the roasted products showed that the oxidation rate of Mo was 100% and the sulfur fixation rate was 90.45%. The main products were molybdenum trioxide, ferric molybdate, and manganese sulfate. Compared with Example 3 (same ratio 2.0:1, sulfur fixation rate 70.53%), the sulfur fixation rate of Example 5 was significantly increased by about 20 percentage points. This is because co-milling activation not only achieved microscopic uniform mixing of materials, but more importantly, high-energy ball milling destroyed the inert layer on the mineral surface, increased lattice defects, and greatly promoted the diffusion reaction at the solid-solid interface, enabling a high sulfur fixation rate to be achieved even at a lower manganese-molybdenum ratio.

[0047] Example 6

[0048] The raw material pretreatment is the same as above. Weigh the two mineral powders according to the ratio of n(Mn):n(MoS2) = 2.5:1, and add 1.0% sodium carbonate (Na2CO3) as a mineralizer as a total mass of the mixture. Place the mixture in a high-energy planetary ball mill with a ball-to-material ratio of 10:1 and a rotation speed of 400 rpm for co-milling and activation for 30 minutes. Place the activated mixture in a corundum crucible, introduce oxygen (flow rate 175 mL / min), and perform a two-stage roasting program (450℃ 120 min + 550℃ 120 min) with a heating rate of 10℃ / min.

[0049] Phase analysis and sulfur content determination of the calcined products showed that the oxidation rate of Mo was 100% and the sulfur fixation rate was 96.82%. The products were loose and porous, with the main phases being MoO3, MnSO4, Fe2(MoO4)3 and a small amount of Na2SO4. 4， This embodiment achieves optimal results. On the one hand, co-grinding activation enhances contact and provides a highly reactive interface; trace amounts of Na2SO4 form low-melting-point micro-regions during calcination, generating a local liquid phase, which promotes atomic / ion diffusion (liquid phase mass transfer), accelerating the oxidative decomposition of MoS2 and helping SO2 to be captured by MnO2 / Fe2O3 to form stable sulfates.

[0050] Comparative Example 1

[0051] Using the same raw materials and methods as in Example 3, high-iron manganese ore powder (over 80% of which is -0.074mm) and molybdenite powder (over 90% of which is -0.074mm) were prepared. At the same molar ratio as in Example 3, n(Mn):n(MoS2) = 2.0:1, the corresponding masses of high-iron manganese ore powder and molybdenite powder were weighed and mechanically mixed in a mixer for 30 minutes to ensure uniform mixing, resulting in a mixed ore material. The mixed ore material was placed in a corundum crucible and placed in a programmable temperature-controlled roasting furnace. Pure oxygen was introduced into the furnace, and the oxygen flow rate was controlled at 175 mL / min. The roasting program was set as follows: the temperature was increased directly from room temperature to 550℃ at a rate of 10℃ / min, and held at 550℃ for 4 hours. After the holding period, the temperature was decreased to below 200℃ at a rate of 5℃ / min, and then cooled to room temperature with the furnace to obtain the roasted product.

[0052] The roasted product exhibited significant agglomeration and compaction, being denser than the product of Example 3. Phase analysis and sulfur content detection of the roasted product revealed a molybdenum oxidation rate of 97.5% and a sulfur fixation rate of 62.1%, both lower than those of Example 3 (100% and 70.53%, respectively). This indicates that a single-stage high-temperature roasting process can easily lead to rapid sintering of the material surface, hindering the diffusion of oxygen into the particle interior and the discharge of reaction products, thereby reducing reaction efficiency and sulfur fixation effect. A two-stage roasting process is necessary to obtain high oxidation and sulfur fixation rates.

[0053] Comparative Example 2

[0054] Analytical pure manganese dioxide (MnO2, content ≥99%) was used instead of high-iron manganese ore and mixed with molybdenite powder at the same manganese molar ratio as in Example 3 (n(Mn):n(MoS2)=2.0:1). The experiment was conducted under the same atmosphere and a two-stage roasting procedure (450℃ 2h + 550℃ 2h).

[0055] The roasted product was relatively loose and did not show obvious agglomeration. Phase analysis and sulfur element detection of the roasted product showed that the molybdenum oxidation rate was 100%, but the sulfur fixation rate was only 58.7%, which was significantly lower than that of Example 3 (70.53%) using high-iron manganese ore. This indicates that the iron oxide (Fe2O3) associated with natural high-iron manganese ore played a key synergistic catalytic role in the sulfur fixation process of this invention.

[0056] Comparative Example 3

[0057] Take the same mixed mineral material with the same proportions and particle size as in Example 3, and perform the same two-stage roasting (450℃ 2h + 550℃ 2h) under static air atmosphere (instead of flowing pure oxygen).

[0058] The reaction process was slow, and the material color was uneven after roasting. The test showed that the molybdenum oxidation rate was 91.2% and the sulfur fixation rate was 55.4%. This indicates that a sufficient oxygen concentration (pure oxygen atmosphere) is crucial for achieving rapid and complete oxidation of molybdenite and a high sulfur fixation rate. An air atmosphere is difficult to meet the reaction requirements.

[0059] Comparative Example 4

[0060] The preparation method of high-iron manganese ore powder and molybdenite powder is the same as in the series of examples. They are weighed and mechanically mixed according to the ratio of n(Mn):n(MoS2) = 0.5:1. The mixed ore is placed in a corundum crucible, placed in a roasting furnace, and pure oxygen is introduced at a flow rate of 175 mL / min. The same two-stage roasting program (450℃ 2h + 550℃ 2h) and heating and cooling rates as in Example 3 are adopted.

[0061] A distinctly pungent odor (SO2) can be detected during the roasting process. Tests showed that the molybdenum oxidation rate was 88.5%, while the sulfur fixation rate was only 15.2%. A large amount of sulfur escaped in the form of SO2. This indicates that when the amount of manganese is insufficient, the sulfur released from the decomposition of molybdenite cannot be effectively fixed, and most of it is emitted in the form of SO2. Furthermore, the oxidation of molybdenum is also inhibited.

[0062] Comparative Example 5

[0063] Using the same mixed ore and pure oxygen atmosphere as in Example 3, the first stage roasting temperature was adjusted to 400℃ and held for 2 hours, while the second stage was still held at 550℃ for 2 hours.

[0064] The test results showed that the molybdenum oxidation rate was 99.2% and the sulfur fixation rate was 63.8%. The molybdenum oxidation was still relatively complete, but the sulfur fixation rate was significantly lower than the 70.53% in Example 3.

[0065] Comparative Example 6

[0066] Using the same mixed ore as in Example 4 (n(Mn):n(MoS2)=2.5:1) and a pure oxygen atmosphere, the first stage was held at 450°C for 2 hours, and the second stage was held at 650°C for 2 hours.

[0067] The molybdenum oxidation rate was 98.1% and the sulfur fixation rate was 80.5%. Compared with Example 4 (100%, 82.31%), the molybdenum oxidation rate decreased and the sulfur fixation rate did not increase further.

[0068] Based on the test results of Examples 1-4 and Comparative Examples 1-4, the following table 3 is obtained.

[0069]

[0070] Table 3

[0071] Based on Table 1 above, as well as the various embodiments and comparative examples, the following conclusions can be drawn: Examples 1 to 4 demonstrate the effect of the manganese-molybdenum molar ratio on the sulfur fixation rate. When the ratio of n(Mn):n(MoS2) gradually increases from 1.0:1 (Example 1) to 2.5:1 (Example 4), the sulfur fixation rate increases from 38.54% to 82.31%. This continuous gradient change clearly reveals the positive correlation between sulfur fixation efficiency and manganese dosage, providing a quantitative basis for process control. In contrast, the sulfur fixation rate of Comparative Example 4 (n(Mn):n(MoS2)=0.5:1) is only 15.2%, which defines the critical point for the technology to take effect from the opposite perspective.

[0072] By comparing Example 3 and Comparative Example 1, under the same total duration (4 hours), same final temperature (550℃), and same ratio (2.0:1), Comparative Example 1, which eliminated the 450℃ low-temperature stage, had a sulfur fixation rate (62.1%) that decreased by 8.43 percentage points compared to Example 3 (70.53%), and the product showed sintering. This data proves that the two-stage temperature control is not a simple time allocation, but a key step to prevent premature densification of materials and ensure mass transfer in the reaction. Data from Comparative Examples 5 and 6 proves that when the temperature in the first stage is below about 440℃, although it does not seriously affect the final oxidation of molybdenum (due to the high temperature guarantee in the second stage), it affects the full progress of the initial sulfur fixation reaction, resulting in a decrease in the total sulfur fixation efficiency. When the temperature in the second stage exceeds 600℃, some MoO3 will be lost through volatilization, resulting in a decrease in the oxidation rate, and the stability of sulfate will also be affected.

[0073] When chemically pure MnO2 was used to replace high-iron manganese ore with the same manganese content, the sulfur fixation rate of Comparative Example 2 (58.7%) decreased by 11.83 percentage points compared with Example 3 (70.53%), even though all other conditions were exactly the same. This difference could not be attributed to the purity of the raw materials, but rather to the in-situ catalytic function of Fe2O3 in the high-iron manganese ore, which improved the production efficiency of manganese sulfate by promoting the conversion of SO2→SO3.

[0074] Under static air, the molybdenum oxidation rate (91.2%) and sulfur fixation rate (55.4%) of Comparative Example 3 decreased by 8.8 and 15.13 percentage points, respectively, compared with Example 3. This indicates that a sufficient oxygen concentration (pure oxygen atmosphere) is crucial for achieving rapid and complete oxidation of molybdenite and a high sulfur fixation rate, and an air atmosphere is insufficient to meet the reaction requirements.

[0075] Example 4 (ratio 2.5:1) achieved a sulfur fixation rate of 82.31% under the complete process. However, if any feature was removed (e.g., removal of two-stage roasting in Comparative Example 1, removal of iron component in Comparative Example 2, and removal of pure oxygen in Comparative Example 3), the effect deteriorated even with a high ratio. Even with the complete process, a low ratio (Comparative Example 4) also led to failure. This indicates that the specific ratio of high-iron manganese ore, the two-stage roasting process, and the pure oxygen atmosphere constitute a complementary system. The innovation of this system lies in: utilizing the synergistic function of multiple components (MnO2 and Fe2O3) in natural high-iron manganese ore, and through optimized temperature program and atmosphere control, while achieving efficient molybdenum oxidation (oxidation rate ≥99%), sulfur is directionally converted into stable manganese sulfate (sulfur fixation rate ≥82%), reducing the emission load of potential pollutant SO2 by more than 80%. This transforms traditionally difficult-to-treat high-iron manganese ore into valuable manganese intermediate products. The raw material cost of sulfur fixatives in traditional processes is reduced through a waste-to-waste approach.

[0076] In Example 5, with the same manganese-molybdenum ratio as in Example 3 (2.0:1), the sulfur fixation rate increased from 70.53% to 90.45% after high-energy ball milling co-grinding activation, an increase of nearly 20 percentage points. This was achieved by mechanically inducing lattice distortion and increasing interfacial activity, fundamentally accelerating the solid-solid phase reaction kinetics, reducing the consumption of chemical reagents (manganese ore) while improving sulfur fixation efficiency. In Example 6, based on the optimized ratio (2.5:1) and co-grinding activation, a mineralizer was introduced, further increasing the sulfur fixation rate to 96.82%. This indicates that trace amounts of mineralizer can form a liquid phase during roasting to promote mass transfer, creating a synergistic effect of interfacial activation-mass transfer promotion with the active interface generated by mechanical activation, providing a new solution to the long-standing sulfur pollution problem.

[0077] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for oxidizing molybdenite in high-iron manganese ore and simultaneously fixing sulfur, characterized in that, Includes the following steps: S1. Raw material pretreatment: Crush and grind the high-iron manganese ore and molybdenite to the predetermined fineness and pass them through a 200-mesh sieve. S2. Mixing: The pretreated high-iron manganese ore powder and molybdenite powder are stirred and mixed in a ratio of manganese to molybdenum disulfide n(Mn): n(MoS2) = 1.0:1 ~ 2.5:1 to obtain mixed ore material; S3. Oxidative roasting: The mixed ore is placed in a roasting furnace and oxidized under an oxygen-containing atmosphere to oxidize the molybdenum in molybdenite and fix the sulfur into sulfate, thereby obtaining a roasting product containing molybdenum oxide and manganese sulfate.

2. The method according to claim 1, characterized in that, In step S1, the high-iron manganese ore contains no less than 35% MnO2, no less than 16% Fe2O3, and no less than 0.05% sulfur; the molybdenite contains no less than 49% molybdenum, of which the proportion of MoS2 is no less than 82%.

3. The method according to claim 1, characterized in that, In step S1, after pretreatment, the proportion of particles smaller than 0.074 mm in the high-iron manganese ore powder reaches more than 80%; and the proportion of particles smaller than 0.074 mm in the molybdenite powder reaches more than 90%.

4. The method according to claim 3, characterized in that, In step S1, the pretreatment of the high-iron manganese ore is as follows: it is first coarsely crushed by a jaw crusher, and then fed into a ball mill for grinding for 20 to 30 minutes.

5. The method according to claim 3, characterized in that, In step S1, the pretreatment of molybdenite specifically involves grinding it for 8-12 minutes using an agate three-head grinder.

6. The method according to claim 1, characterized in that, The mixing in step S2 is achieved by mechanical stirring.

7. The method according to claim 1, characterized in that, In step S3, the oxidation calcination is a two-stage calcination, specifically including: the first stage calcination temperature is 440℃~460℃, and the holding time is 1.5~2.5 hours; the second stage calcination temperature is 540℃~560℃, and the holding time is 1.5~2.5 hours.

8. The method according to claim 7, characterized in that, The heating rate of the oxidation calcination is controlled at 8℃ / min to 12℃ / min, and the cooling rate is controlled at 4℃ / min to 6℃ / min.

9. The method according to claim 1, characterized in that, In step S3, the oxygen-containing atmosphere is a pure oxygen atmosphere, and the gas flow rate is 150 mL / min ~ 200 mL / min.

10. The method according to claim 1, characterized in that, The oxidative roasting process is carried out under normal pressure.

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