Method for preparing low-carbon clinker by synergistically disposing phosphogypsum with electrolytic manganese residue

Abstract

The application discloses a method for preparing low-carbon clinker by electrolytic manganese residue and phosphogypsum, and the method comprises the following steps: obtaining phosphogypsum, electrolytic manganese residue and carbonaceous raw materials, drying and crushing, and then mixing and grinding according to the modified C:S, KH value and total CaO:SiO2 mass ratio; the obtained mixture is added with water to form material balls, and then the material balls are dried; the dried material balls are calcined in an oxygen-deficient or oxygen-free environment, and then the low-carbon clinker is obtained after cooling; and the reduction components in the electrolytic manganese residue are used for decomposing the phosphogypsum, so that the industrial solid wastes, i.e., the electrolytic manganese residue and the phosphogypsum, are effectively and cooperatively utilized, and energy is saved; except for the carbonaceous raw materials, the total utilization rate of the electrolytic manganese residue and the phosphogypsum in the batching reaches 100%, the industrial solid wastes, i.e., the electrolytic manganese residue and the phosphogypsum, are effectively and cooperatively utilized, the amount of the carbonaceous raw materials required for decomposing the phosphogypsum is reduced, the cost and carbon emission are reduced, and the low-carbon clinker is synchronously prepared.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag. Background Technology

[0002] Phosphogypsum is a solid waste generated during the wet-process phosphoric acid production. Its composition is complex, containing not only hydrated calcium sulfate but also incompletely decomposed phosphate rock, residual phosphoric acid, fluorides, acid-insoluble substances, and organic matter. The presence of fluorine and organic matter has the greatest impact on the resource utilization of phosphogypsum. Stockpiling it occupies a large amount of land and pollutes water and land resources. Currently, there are no effective utilization methods for phosphogypsum. Its resource utilization and safe, efficient use are of great significance in solving the environmental pollution and resource waste problems caused by stockpiling.

[0003] Replacing limestone with phosphogypsum as a CaO source in cement clinker production is a challenging yet significant direction for the resource utilization of phosphogypsum. However, compared to CaCO3, CaSO4 requires higher temperatures to fully decompose and desulfurize, increasing the operational difficulty and cost of the process. Furthermore, it can still exist in large quantities even under high-temperature calcination, which undoubtedly restricts the effective application of phosphogypsum. Low-temperature decomposition of CaSO4 generally uses carbonaceous raw materials as reducing agents, which increases the cost and carbon emissions associated with phosphogypsum treatment.

[0004] The production of electrolytic manganese metal generates a large amount of electrolytic manganese slag, a major source of pollution in the industry. Its harmful components are mainly soluble heavy metals and ammonia nitrogen. Statistics show that approximately 10 tons of electrolytic manganese slag are produced for every ton of metallic manganese produced. The amount of unutilized electrolytic manganese slag increases by about 10 million tons annually, reaching over 80 million tons in China by 2023. Currently, companies have not found a proper method for disposing of electrolytic manganese slag, typically leaving it in open-air piles. With rainwater erosion and sun and wind exposure, this leads to soil, water, and air pollution, damaging the ecological environment.

[0005] CN1837120A discloses a "method for producing cement using electrolytic manganese slag," which uses limestone, electrolytic manganese slag, iron powder, fluorite, and anthracite mixed and ground as raw material, then pelletized and roasted to produce clinker. This method still uses natural mineral limestone to prepare clinker, but the carbon emissions from the decomposition of limestone into CO2 and CaO are high, accounting for about 60% of the total carbon emissions of the cement industry. It also uses iron powder and fluorite, which are expensive in the market and not widely distributed in the region. Furthermore, it does not test the reducing components of the electrolytic manganese slag, resulting in the reduction components in the electrolytic manganese slag not being fully utilized, which does not meet the current goals of "dual carbon" and "green environmental protection."

[0006] Whether industrial solid waste electrolytic manganese slag and phosphogypsum can be co-processed to produce high-value clinker, thereby reducing costs, energy consumption, and carbon emissions, has become an urgent technical problem to be solved. Summary of the Invention

[0007] The purpose of this invention is to provide a method for co-processing phosphogypsum with electrolytic manganese slag and preparing low-carbon clinker. The reducing components in the electrolytic manganese slag are used for the decomposition of phosphogypsum, so as to achieve effective synergistic utilization of industrial solid waste electrolytic manganese slag and phosphogypsum, save energy, reduce costs and carbon emissions, and simultaneously produce low-carbon clinker.

[0008] To achieve the above objectives, the following technical solution is adopted:

[0009] A method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag includes the following steps:

[0010] (1) Obtain phosphogypsum, electrolytic manganese slag, and carbonaceous raw materials, dry and crush them, and mix and grind them according to the corrected C:S, KH value and total CaO:SiO2 mass ratio.

[0011] (2) Add water to the obtained mixture to form pellets, and then dry them;

[0012] (3) The dried pellets are calcined in an oxygen-deficient or oxygen-free environment, and then cooled after calcination to obtain low-carbon clinker.

[0013] According to the above scheme, the main chemical components of the phosphogypsum in step (1) include, by mass percentage, SiO2: 0-10%; Al2O3: 0-1%; Fe2O3: 0-1%; CaO: 25-35%; MgO: 0-1%; SO3: 40-45%; and loss on ignition of 15-25%.

[0014] According to the above scheme, the main chemical components of the electrolytic manganese slag in step (1), by mass percentage, include SiO2: 30-45%; Al2O3: 2-10%; Fe2O3: 2-10%; CaO: 5-15%; MgO: 0-5%; MnO: 0-10%; SO3: 15-25%; and loss on ignition of 20-25%.

[0015] According to the above scheme, the carbonaceous raw material in step (1) is one or more of ordinary coal, high-sulfur coal, and coke.

[0016] According to the above scheme, the modified C:S in step (1) is the molar ratio of fixed carbon in the carbonaceous raw material to SO3 in the phosphogypsum, which is obtained by modifying the initial C:S = 0.7-0.9; the actual amount of carbonaceous raw material to be added in the batch is obtained by subtracting the modification amount from the initial C:S, and the modification amount is the amount of fixed carbon equivalent of the carbonaceous raw material replaced by the reducing component of the electrolytic manganese slag; the modified C:S is 0.6-0.8.

[0017] According to the above scheme, the KH value in step (1) is 0.4-0.55, and the total CaO:SiO2 mass ratio is 1.45-1.87.

[0018] According to the above scheme, the diameter of the material ball in step (2) is 1-3cm.

[0019] According to the above scheme, the calcination temperature in step (3) is 1150-1250℃, the calcination time is 5-30min, and the O2 concentration in the calcination environment is 0-10%.

[0020] According to the above scheme, the SO3 content of the low-carbon clinker obtained in step (3) is ≤2wt%, and the mineral composition is mainly C2S and C3S2.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The sulfur in electrolytic manganese slag is not entirely present in the form of hydrated CaSO4, which is difficult to desulfurize. It also contains sulfates such as MnSO4 and (NH4)2SO4, which are easily decomposed and desulfurized, as well as sulfur that can react with CaSO4 and desulfurize. - Many electrolytic manganese slags, even in powder form, can decompose and desulfurize under anaerobic or oxygen-deficient conditions at 1000-1100℃. The pelletizing method is used to remove the potential reducing component S in the electrolytic manganese slag. - NH4 + Mn 2+ The reduced component is enclosed inside the sphere, making it less susceptible to oxidation from contact with O2 in the air during calcination. At this point, the reducing component is in excess. After adding phosphogypsum, this excess reducing component can be fully utilized to decompose and desulfurize the phosphogypsum. The actual amount of desulfurized phosphogypsum that can be decomposed from electrolytic manganese slag was obtained from the pelletizing and calcination test of electrolytic manganese slag with phosphogypsum. Through this method, the amount of reducing agent required for decomposition and desulfurization of phosphogypsum in low-carbon clinker batches can be reduced.

[0023] (2) In addition to carbonaceous raw materials, the total utilization rate of electrolytic manganese slag and phosphogypsum in the batching reached 100%, realizing the effective synergistic utilization of industrial solid waste electrolytic manganese slag and phosphogypsum and reducing the amount of carbonaceous raw materials that need to be decomposed into phosphogypsum, thus reducing costs and carbon emissions, and simultaneously producing low-carbon clinker.

[0024] (3) The SO3 content of the low-carbon clinker obtained by this invention is ≤2%. The desulfurization rate is still high even when only phosphogypsum, electrolytic manganese slag and carbonaceous raw materials are used in the batching. The mineral composition is mainly C2S and C3S2. Attached Figure Description

[0025] Figure 1 XRD patterns of the low-carbon clinker obtained in Examples 1, 2, and 3. Detailed Implementation

[0026] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0027] A specific embodiment discloses a method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag, including the following steps:

[0028] (1) Obtain phosphogypsum, electrolytic manganese slag, and carbonaceous raw materials, dry and crush them, and mix and grind them according to the corrected C:S, KH value and total CaO:SiO2 mass ratio.

[0029] (2) Add water to the obtained mixture to form pellets, and then dry them;

[0030] (3) The dried pellets are calcined in an oxygen-deficient or oxygen-free environment, and then cooled after calcination to obtain low-carbon clinker.

[0031] Specifically, the main chemical components of phosphogypsum, by mass percentage, include SiO2: 0-10%; Al2O3: 0-1%; Fe2O3: 0-1%; CaO: 25-35%; MgO: 0-1%; SO3: 40-45%; and a loss on ignition of 15-25%.

[0032] Specifically, the main chemical components of electrolytic manganese slag, by mass percentage, include: SiO2: 30-45%; Al2O3: 2-10%; Fe2O3: 2-10%; CaO: 5-15%; MgO: 0-5%; MnO: 0-10%; SO3: 15-25%; and a loss on ignition of 20-25%.

[0033] Specifically, the carbonaceous raw material is one or more of ordinary coal, high-sulfur coal, and coke.

[0034] Specifically, the corrected C:S is the molar ratio of fixed carbon in the carbonaceous raw material to SO3 in the phosphogypsum, which is obtained by correcting the initial C:S = 0.7-0.9. Subtracting the correction amount from the initial C:S yields the actual amount of carbonaceous raw material to be added in the batching. The correction amount is the amount of fixed carbon equivalent of the carbonaceous raw material replaced by the reducing component of the electrolytic manganese slag. The corrected C:S is 0.6-0.8.

[0035] Specifically, the correction amount is obtained as follows:

[0036] Different amounts of phosphogypsum were added to 100 parts of electrolytic manganese slag to form pellets with an average diameter of 2 cm. After drying, the pellets were calcined at 1000-1100℃ for 5-30 minutes in an oxygen-deficient or oxygen-free environment with an O2 concentration of 0-10%. The SO3 content after calcination was measured. When the SO3 content was ≤1%, x parts of phosphogypsum could be decomposed and desulfurized from 100 parts of electrolytic manganese slag, which is x% of the electrolytic manganese slag. However, considering that using more phosphogypsum (low-carbon clinker feedstock) would reduce the decomposition and desulfurization effect of electrolytic manganese slag, the amount of decomposable phosphogypsum should be reduced. x% is multiplied by a coefficient y, where y is 0.8-1.0. That is, the actual amount of phosphogypsum that can be decomposed and desulfurized from electrolytic manganese slag is x% * y of electrolytic manganese slag. The mass ratio of total CaO to SiO2 was used to prepare the mixture. 磷石膏 :m 锰渣 Therefore, the actual amount of phosphogypsum required to be added as carbonaceous raw material is m' 磷石膏 =m 磷石膏 -m 锰渣 *x%*y, Actual carbonaceous raw material usage m 碳质原料 =m' 磷石膏 *(SO3 mass percentage in phosphogypsum)*(preliminary C:S)*12 / [80*(fixed carbon content percentage in carbonaceous raw materials)], thus obtaining the corrected C:S = [m 碳质原料 *(Percentage of fixed carbon content in carbonaceous raw materials) / 12] / [m 磷石膏 *(SO3 mass percentage in phosphogypsum) / 80], the SO3 mass percentage in phosphogypsum and the fixed carbon content percentage in carbonaceous raw materials are obtained from chemical composition analysis and conventional coal analysis.

[0037] Specifically, the KH value is 0.4-0.55, and the total CaO:SiO2 mass ratio is 1.45-1.87.

[0038] Specifically, the diameter of the material ball is 1-3 cm.

[0039] Specifically, the calcination temperature is 1150-1250℃, the calcination time is 5-30min, and the O2 concentration in the calcination environment is 0-10%; the SO3 content of the resulting low-carbon clinker is ≤2wt%, and the mineral composition is mainly C2S and C3S2.

[0040] The following specific embodiments describe the acquisition and testing of raw materials:

[0041] Electrolytic manganese slag and phosphogypsum were obtained, dried, crushed, and ground, and then subjected to chemical composition analysis. The chemical composition of a batch of electrolytic manganese slag and phosphogypsum is shown in Table 1. Note that the SO3 content in the electrolytic manganese slag was calculated from measured sulfur (S) and is not entirely SO3. The SO3 content of the electrolytic manganese slag, after decomposition and desulfurization at 1000℃ under anaerobic or oxygen-deficient conditions in powder form, was 0.84%, and the SO3 content after decomposition and desulfurization at 1100℃ was 0.33%.

[0042] Table 1 Chemical composition analysis

[0043] name Loss on ignition <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[SO3]]> MnO Electrolytic manganese slag 22.87 39.27 9.36 5.41 6.12 3.57 19.17 3.35 phosphogypsum 19.27 6.6 0.23 0.52 29.66 0.03 42.46 /

[0044] The carbonaceous raw materials used were subjected to routine analysis and chemical composition analysis of ash. This was high-sulfur coal, and the results are shown in Tables 2 and 3, respectively.

[0045] Table 2. Conventional Analysis of High-Sulfur Coal

[0046] name Moisture Ash Volatile matter Fixed carbon content Total sulfur Qnet,ad Qnet,d High sulfur coal 1.42 23.48 10.25 64.85 2.99 25.25 26.33

[0047] Table 3 Chemical composition analysis of high-sulfur coal ash

[0048] name Loss on ignition <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[SO3]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> coal ash 0 47.36 26.12 15.21 4.16 1.55 2.11 1.03 0.40

[0049] The method for testing the reducing components of electrolytic manganese slag is as follows: Different amounts of phosphogypsum are added to 100 parts of electrolytic manganese slag to form pellets with an average diameter of 2 cm. After drying, the pellets are calcined at 1000-1100℃ for 5-30 minutes in an oxygen-deficient or oxygen-free environment with an O2 concentration of 0-10%. The SO3 content after calcination is measured. When the SO3 content is ≤1%, 100 parts of electrolytic manganese slag can be decomposed and desulfurized by 33-37 parts of phosphogypsum, which is 33-37% of the electrolytic manganese slag. However, considering that using more phosphogypsum (in low-carbon clinker batches) will reduce the decomposition and desulfurization effect of electrolytic manganese slag, based on experiments and experience, it is found that 100 parts of electrolytic manganese slag can actually be decomposed and desulfurized by 30-33 parts of phosphogypsum, which is 30-33% of the electrolytic manganese slag, in the batches for calcining low-carbon clinker.

[0050] Example 1

[0051] 1. Proportioning Design

[0052] The SO3 content in phosphogypsum is included in its loss on ignition. Based on a loss on ignition of 19.27% ​​+ 42.46% = 61.73%, the remaining chemical components are quantified according to substances primarily composed of CaO. The mixture is then designed with electrolytic manganese slag and high-sulfur coal, based on a preliminary C:S ratio of 0.8146 (C:S) for C in the high-sulfur coal to SO3 in the modified phosphogypsum, a KH value of 0.486, an SM value of 3.287, and a total CaO to SiO2 mass ratio of 1.702. The resulting weight ratio is phosphogypsum:electrolytic manganese slag:high-sulfur coal 78:22. 5.69, Verification: The amount of phosphogypsum required to be added to the high-sulfur coal is 78 - 22 * ​​31.2647% = 71.1218, the actual amount of high-sulfur coal used = the amount of phosphogypsum required to be added to the high-sulfur coal * 0.4246 * 0.8146 * 12 / (80 * 0.6485) = 5.69, the corrected C:S = (5.69 * 0.6485 / 12) / (78 * 0.4246 / 80) = 0.7428, the ash weight introduced by the high-sulfur coal is 5.69 * 0.2348 = 1.34, the proportions and corresponding indicators are shown in Tables 4 and 5 respectively:

[0053] Table 4 Proportions

[0054]

[0055] Table 5. Indicators Corresponding to the Proportions

[0056]

[0057] 2. Ball making

[0058] The phosphogypsum, electrolytic manganese slag, and high-sulfur coal measured according to the above proportions were mixed and ground, and then water was added to make material balls with an average diameter of 2 cm, which were then naturally dried for 1 day.

[0059] 3. Calcination

[0060] The naturally dried pellets were placed in a rotary kiln with oxygen deficiency after burning coal (coal that provides temperature and heat) for calcination. The O2 concentration was 6%. After calcination, the pellets were cooled to obtain low-carbon clinker. The kiln calcination temperature was set at 1200℃ and the time was 10 minutes.

[0061] Example 2

[0062] 1. Proportioning Design

[0063] The SO3 content in phosphogypsum is included in its loss on ignition. Based on a loss on ignition of 19.27% ​​+ 42.46% = 61.73%, the remaining chemical components are quantified according to substances primarily composed of CaO. The mixture is designed with electrolytic manganese slag and high-sulfur coal, based on a preliminary C:S ratio of 0.8146 (C:S) for C in the high-sulfur coal to SO3 in the modified phosphogypsum, a KH value of 0.429, an SM value of 3.217, and a total CaO to SiO2 mass ratio of 1.551. The weight ratio is phosphogypsum:electrolytic manganese slag:high-sulfur coal of 75:25. 5.37, Verification: The amount of phosphogypsum required to be added to the high-sulfur coal is 75 - 25 * 31.2647% = 67.1838. The actual amount of high-sulfur coal used = the amount of phosphogypsum required to be added to the high-sulfur coal * 0.4246 * 0.8146 * 12 / (80 * 0.6485) = 5.37. The corrected C:S = (5.37 * 0.6485 / 12) / (75 * 0.4246 / 80) = 0.7290. The ash weight introduced by the high-sulfur coal is 5.37 * 0.2348 = 1.26. The proportions and corresponding indicators are shown in Tables 6 and 7 respectively.

[0064] Table 6 Proportions

[0065]

[0066] Table 7. Indicators Corresponding to the Proportions

[0067]

[0068] 2. Ball making

[0069] The phosphogypsum, electrolytic manganese slag, and high-sulfur coal measured according to the above proportions were mixed and ground, and then water was added to make material balls with an average diameter of 2 cm, which were then naturally dried for 1 day.

[0070] 3. Calcination

[0071] The naturally dried pellets were placed in a rotary kiln with oxygen deficiency after burning coal (coal that provides temperature and heat) for calcination. The O2 concentration was 3%. After calcination, the pellets were cooled to obtain low-carbon clinker. The kiln calcination temperature was set at 1180℃ and the time was 12 minutes.

[0072] Example 3

[0073] 1. Proportioning Design

[0074] The SO3 content in phosphogypsum is included in its loss on ignition. Based on a loss on ignition of 19.27% ​​+ 42.46% = 61.73%, the remaining chemical components are quantified according to substances primarily composed of CaO. The mixture is designed with electrolytic manganese slag and high-sulfur coal, based on a preliminary C:S ratio of 0.8146 (C:S) for C in the high-sulfur coal to SO3 in the modified phosphogypsum, a KH value of 0.528, an SM value of 3.342, and a total CaO to SiO2 mass ratio of 1.814. The weight ratio is phosphogypsum:electrolytic manganese slag:high-sulfur coal of 80:20. 5.90, Verification: The amount of phosphogypsum required to be added to the high-sulfur coal is 80 - 20 * 31.2647% = 73.7471. The actual amount of high-sulfur coal used = the amount of phosphogypsum required to be added to the high-sulfur coal * 0.4246 * 0.8146 * 12 / (80 * 0.6485) = 5.90. Corrected C:S = (5.90 * 0.6485 / 12) / (80 * 0.4246 / 80) = 0.7509. The ash weight introduced by the high-sulfur coal is 5.90 * 0.2348 = 1.39. The proportions and corresponding indicators are shown in Tables 8 and 9 respectively.

[0075] Table 8 Proportions

[0076]

[0077] Table 9. Indicators Corresponding to the Proportions

[0078]

[0079] 2. Ball making

[0080] The phosphogypsum, electrolytic manganese slag, and high-sulfur coal measured according to the above proportions were mixed and ground, and then water was added to make material balls with an average diameter of 2 cm, which were then naturally dried for 1 day.

[0081] 3. Calcination

[0082] The naturally dried pellets were placed in a rotary kiln with oxygen deficiency after burning coal (coal that provides temperature and heat) for calcination. The O2 concentration was 5%. After calcination, the pellets were cooled to obtain low-carbon clinker. The kiln calcination temperature was set at 1230℃ and the time was 8 minutes.

[0083] The SO3 content of each embodiment and some electrolytic manganese slag reducing components is shown in Table 10. Among them, electrolytic manganese slag reducing component test 1 is 100 parts electrolytic manganese slag and 0 parts phosphogypsum; electrolytic manganese slag reducing component test 2 is 77 parts electrolytic manganese slag and 23 parts phosphogypsum; electrolytic manganese slag reducing component test 3 is 73 parts electrolytic manganese slag and 27 parts phosphogypsum; and electrolytic manganese slag reducing component test 4 is 70 parts electrolytic manganese slag and 30 parts phosphogypsum. The main mineral content of each embodiment is shown in Table 11.

[0084] Table 10 SO3 Content

[0085]

[0086] Table 11. Content of major minerals (%)

[0087]

[0088]

[0089] In all embodiments, the SO3 content was less than 2%, resulting in low-carbon clinker with a total C2S and C3S2 content ≥70%. Except for high-sulfur coal, the total utilization rate of industrial solid waste electrolytic manganese slag and phosphogypsum in the feedstock reached 100%. Adding phosphogypsum to electrolytic manganese slag not only improved the utilization rate of solid waste and reduced costs, but also reduced the amount of high-sulfur coal used. In Example 1, the amount of high-sulfur coal used was reduced by (0.8146-0.7428) / 0.8146 = 8.8%; in Example 2, it was reduced by (0.8146-0.7290) / 0.8146 = 10.5%; and in Example 1, it was reduced by (0.8146-0.7509) / 0.8146 = 7.8%. This also shows that the lower the designed total CaO to SiO2 mass ratio, the larger the amount of electrolytic manganese slag used, the greater the reduction in high-sulfur coal used, and the greater the reduction in carbon emissions. Figure 1 The XRD patterns of the low-carbon clinker obtained in Examples 1, 2, and 3 show that the mineral composition is mainly C2S and C3S2.

[0090] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag, characterized in that... Includes the following steps: (1) Obtain phosphogypsum, electrolytic manganese slag, and carbonaceous raw materials, dry and crush them, and mix and grind them according to the corrected C:S, KH values ​​and total CaO:SiO2 mass ratio. The corrected C:S ratio is the molar ratio of fixed carbon in the carbonaceous raw material to SO3 in the phosphogypsum, obtained by correcting the initial C:S ratio of 0.7-0.

9. Subtracting the correction from the initial C:S ratio yields the actual amount of carbonaceous raw material to be added to the batch. The correction is the amount of fixed carbon equivalent replaced by the reducing component of the electrolytic manganese slag. The corrected C:S ratio is 0.6-0.

8. The KH value is 0.4-0.55, and the total CaO:SiO2 mass ratio is 1.45-1.87; (2) The resulting mixture is mixed with water to form pellets, which are then dried; (3) The dried pellets are calcined in an oxygen-deficient or oxygen-free environment, and then cooled to obtain low-carbon clinker. The calcination temperature is 1150-1250℃, the calcination time is 5-30min, and the O2 concentration in the calcination environment is 0-10%.

2. The method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag as described in claim 1, characterized in that... The main chemical components of the phosphogypsum mentioned in step (1) by mass percentage include SiO2: 0-10%; Al2O3: 0-1%; Fe2O3: 0-1%; CaO: 25-35%; MgO: 0-1%; SO3: 40-45%; and loss on ignition of 15-25%.

3. The method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag as described in claim 1, characterized in that... The main chemical components of the electrolytic manganese slag mentioned in step (1) by mass percentage include SiO2: 30-45%; Al2O3: 2-10%; Fe2O3: 2-10%; CaO: 5-15%; MgO: 0-5%; MnO: 0-10%; SO3: 15-25%; and loss on ignition of 20-25%.

4. The method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag as described in claim 1, characterized in that... The carbonaceous raw material in step (1) is one or more of ordinary coal, high-sulfur coal, and coke.

5. The method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag as described in claim 1, characterized in that... The diameter of the material ball mentioned in step (2) is 1-3cm.

6. The method for preparing low-carbon clinker by co-processing phosphogypsum with electrolytic manganese slag as described in claim 1, characterized in that... The SO3 content of the low-carbon clinker obtained in step (3) is ≤2wt%, and the mineral composition is mainly C2S and C3S2.

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