A method for wet cascade desulfurization of manganese slag

Abstract

The present invention discloses a method for wet-process cascade desulfurization of manganese slag. The method comprises the following steps: subjecting manganese ore to particle size classification and then subjecting it to leaching, solution purification, filtration, and other treatments; then subjecting the obtained manganese slag to particle size classification to obtain coarse-grained manganese slag and fine-grained manganese slag; then subjecting the fine-grained manganese slag to calcium sulfate partial phase transformation and fine-grained floc flotation to obtain low-sulfur tailings and high-sulfur manganese slag; and then mixing the coarse-grained manganese slag and low-sulfur tailings to obtain low-sulfur manganese slag. The low-sulfur manganese slag produced by the present invention can be used as a raw material for preparing cement clinker, and the high-sulfur manganese slag can be used as a cement retarder. The method of the present invention achieves resource utilization of slag during electrolytic manganese production by physical means, has a simple process, does not generate secondary pollution, and has good industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of treatment and resource utilization of manganese slag, and in particular to a method for wet cascade desulfurization of manganese slag. Background Art

[0002] Manganese and its compounds are essential raw materials supporting the development of the national economy and are widely used in steel, batteries, electronics, chemicals, pharmaceuticals, and other fields. my country is the world's largest producer, consumer, and exporter of electrolytic manganese. During electrolytic manganese production, every ton of manganese produces 6 to 10 tons of manganese slag, with my country generating over 10 million tons of manganese slag annually. Furthermore, the amount of manganese slag generated during the production of electrolytic manganese dioxide and manganese sulfate is also significant. Manganese slag, with its high production volume, high content of soluble pollutants, and fine particles, has become the largest source of ecological and environmental risk in the manganese industry.

[0003] On October 1, 2022, the national ecological and environmental standard "Technical Specifications for Pollution Control of Manganese Slag" (HJ 1241-2022) officially came into effect. This standard comprehensively stipulates pollution control regulations for manganese slag during collection, storage, transportation, pretreatment, utilization, filling, backfilling, and landfill, and puts forward specific requirements for strengthening pollution prevention and control throughout the entire manganese slag process. Therefore, taking measures to treat or utilize manganese slag has become an urgent issue to be addressed in the manganese industry. The main components of manganese slag are gypsum (CaSO4·2H2O) and quartz, as well as soluble manganese, magnesium, and ammonium salts. It also contains small amounts of heavy metals such as cobalt and nickel. Currently, the treatment of manganese slag is mainly divided into two methods: harmless treatment and resource utilization.

[0004] The harmless treatment of manganese slag mainly involves washing, leaching, or solidification and stabilization to extract or solidify harmful elements such as manganese, ammonia nitrogen, cobalt, and nickel from the manganese slag. Chinese patent CN115747518A discloses a method for recovering nickel-cobalt manganese slag, which involves acid leaching the manganese slag with sulfuric acid and formic acid, filtering, adding an oxidizing agent and an alkali to the filtrate, adjusting the pH to 5-6, and filtering again to obtain a nickel-cobalt-manganese sulfate solution. Chinese patent CN103320621A discloses a method for solidifying heavy metals in electrolytic manganese slag and co-producing sulfur. A raw material containing calcium sulfite and / or calcium sulfate is mixed with a carbon-based reducing agent and roasted to obtain a calcine containing calcium sulfide. The calcine containing calcium sulfide is mixed with manganese slag, water is added, and the mixture is stirred at room temperature. The mixture is filtered to obtain a filtrate and a filter residue. The filtrate is allowed to stand to precipitate sulfur, and the filter residue is the solidified manganese slag.

[0005] The resource utilization of manganese slag is usually to further process the manganese slag and prepare it into a usable product. Chinese patent CN102674965A discloses a manganese slag compound fertilizer and its preparation method, which includes adding a carbonate-containing fertilizer to the manganese slag to convert the calcium sulfate in the manganese slag into calcium carbonate, and then mixing it with a lignin-containing additive and an element fertilizer composed of one or more of nitrogen fertilizer, phosphate fertilizer, and potash fertilizer to prepare the manganese slag compound fertilizer. Chinese patent CN102584316A discloses a method for preparing electrolytic manganese slag porous ceramics, which includes mixing manganese slag, a porogen, a binder, and a flux, adding water and stirring evenly, and using a steel mold to press and shape the green body. After drying, the green body is placed in a high-temperature electric furnace for program-controlled sintering to obtain porous ceramics. Chinese patent CN111644269B discloses a method for the comprehensive utilization of manganese slag, which uses a cationic collector to flotate the manganese slag to obtain concentrate foam and tailings slurry. The concentrate foam is further processed to obtain a white gypsum product, and the tailings slurry is further processed to make unburned bricks or cement clinker.

[0006] In summary, my country has made significant progress in the harmless treatment and resource utilization of manganese slag, providing a better approach to its treatment and utilization. However, existing technologies still have considerable room for improvement in terms of technical economy, industrial chain integration, technological advancement, and stability. Of particular concern is the extremely low resource utilization rate of manganese slag in my country, at only around 5%. Most manganese slag is still disposed of by landfill, and breakthroughs in resource utilization technologies are still urgently needed. Summary of the Invention

[0007] In view of the above-mentioned shortcomings, the present invention provides a method for wet cascade desulfurization of manganese slag. The present invention can render the manganese slag harmless through the particle size classification of manganese ore and manganese slag and the flotation process of fine-grained manganese slag, and divide the manganese slag into high-sulfur manganese slag and low-sulfur manganese slag, which are used as cement retarder and cement clinker, respectively. The manganese slag is organically connected with the cement industry chain, thereby achieving efficient utilization of manganese slag without generating new pollutants, which is conducive to clean production in the manganese industry.

[0008] In order to achieve the above object, the present invention provides a method for wet cascade desulfurization of manganese slag, comprising the following steps:

[0009] Step 1: crushing, grinding, and particle size classification of manganese ore, leaching with sulfuric acid, adjusting the pH, purifying, and filtering to obtain a manganese sulfate solution and a manganese slag; wherein, after particle size classification, the coarse manganese ore with a particle size of -2 mm is obtained, and the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%;

[0010] Step 2: washing the manganese slag with water, filtering to obtain a manganese slag washing liquid and a washed manganese slag, wherein the manganese slag washing liquid is purified and recycled; and the washed manganese slag is subjected to particle size classification to obtain a coarse manganese slag with a particle size of ≥0.074 mm and a fine manganese slag with a particle size of ≤0.074 mm.

[0011] Step 3: Dispersing fine-grained manganese slag of -0.074 mm in water to form a slurry, and converting part of the calcium sulfate in the manganese slag into a calcium carbonate phase with sodium carbonate. At the same time, adjusting the pH of the slurry to 7.5, stirring for 1 to 3 minutes, adding an anionic flocculant to the slurry and stirring for 1 to 5 minutes, then adding sodium oleate and stirring for 3 to 5 minutes for flotation, flotation to obtain high-sulfur manganese slag and low-sulfur tailings, and treating the flotation wastewater for recycling;

[0012] Step 4: Mix the low-sulfur tailings with coarse-grained manganese slag with a particle size of ≥0.074 mm to obtain low-sulfur manganese slag as a raw material for preparing cement clinker, and use the high-sulfur manganese slag as a cement retarder; wherein the SO3 content in the low-sulfur manganese slag is less than 5%; and the SO3 content in the high-sulfur manganese slag is greater than 15%.

[0013] According to one aspect of the present invention, the manganese ore includes any one of manganese carbonate ore and manganese oxide ore.

[0014] According to one aspect of the present invention, the main mineral components of the manganese slag are CaSO4 and SiO2, the content of SO3 in the manganese slag is 10% to 30%, and the particle size of the manganese slag is -2 mm.

[0015] According to one aspect of the present invention, when electrolytic manganese or manganese sulfate is produced using manganese carbonate ore as a raw material, step 1 is specifically as follows:

[0016] Step A1: crushing, grinding, and particle size classification of manganese carbonate ore to obtain coarse manganese ore with a particle size of -2 mm; wherein the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%;

[0017] Step A2: Leaching the coarse manganese ore with sulfuric acid at 40-70° C. for 1-3 hours, aerating the ore after leaching, adding lime to adjust the pH, adding sodium benzoate as a sulfide precipitant to purify the leachate, and filtering to obtain a manganese sulfate solution and manganese slag, wherein the manganese sulfate solution is a raw material in the electrolytic manganese production process or the manganese sulfate production process;

[0018] When electrolytic manganese or manganese sulfate is produced using manganese oxide ore as raw material, step 1 is specifically as follows:

[0019] Step B1: crushing, grinding, and particle size classification of the manganese oxide ore to obtain coarse manganese ore with a particle size of -2 mm, wherein the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%;

[0020] Step B2: Leaching the coarse manganese ore with sulfuric acid with the assistance of a reducing agent at 70-100° C. for 1-4 hours, aerating the ore after leaching, adding lime to adjust the pH, and purifying the leachate by adding sodium fumarate as a sulfide precipitant. The leached solution is filtered to obtain a manganese sulfate solution and a manganese slag, wherein the manganese sulfate solution is a raw material in the electrolytic manganese production process or the manganese sulfate production process.

[0021] Wherein, the reducing agent includes at least one of pyrite, sulfur dioxide, and manganese sulfide.

[0022] According to one aspect of the present invention, the manganese slag is leached slag obtained by leaching, neutralization precipitation, and sulfide precipitation, or a mixture of neutralization precipitation slag and sulfide precipitation slag; or a mixture of leached slag obtained by leaching, neutralization precipitation, and neutralization precipitation slag;

[0023] When the obtained manganese slag is a mixture of leaching slag, neutralization precipitated slag and sulfide precipitated slag, the step 1 is specifically as follows:

[0024] Step C1: crushing, grinding, and particle size classification of manganese carbonate ore to obtain coarse manganese ore with a particle size of -2 mm; wherein the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%;

[0025] Step C2: leaching the coarse manganese ore with sulfuric acid at 40-70° C. for 1-3 hours, introducing air after leaching, adding lime to adjust the pH, adding sodium furam as a sulfide precipitant to purify the leachate, and filtering to obtain a manganese sulfate solution and a mixture of leaching residue, neutralization precipitate residue, and sulfide precipitate residue;

[0026] When the obtained manganese slag is a mixture of leaching slag and neutralization precipitation slag, the step 1 is specifically as follows:

[0027] Step D1: crushing, grinding, and particle size classification of manganese carbonate ore to obtain coarse manganese ore with a particle size of -2 mm; wherein the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%;

[0028] Step D2: leaching the coarse manganese ore with sulfuric acid at 40-70° C. for 1-3 hours, introducing air after leaching, adding lime to adjust the pH, and filtering to obtain a crude manganese sulfate solution and a mixture of leached residue and neutralized precipitated residue;

[0029] Step D3: sodium fumarate is added as a sulfide precipitant to purify the crude manganese sulfate solution, and the manganese sulfate solution and sulfide slag are obtained by filtration.

[0030] According to one aspect of the present invention, the anionic flocculant includes one or both of polyacrylamide and sodium polyacrylate.

[0031] According to one aspect of the present invention, in step 3, the slurry concentration is 15% to 30%; the amount of sodium oleate is 1 to 6 kg / t; and the amount of sodium carbonate is 2 to 80 kg / t.

[0032] According to one aspect of the present invention, in step 4, when preparing cement clinker with the low-sulfur manganese slag, limestone and silica sand need to be added; wherein the mass ratio of the limestone to the low-sulfur manganese slag is 5:1-4; and the sintering temperature for preparing cement clinker is 1250-1400°C.

[0033] According to one aspect of the present invention, step 1 further comprises step-by-step purification, and step 1 comprising step-by-step purification is specifically as follows:

[0034] Step E1: crushing, grinding, and grading the manganese ore, leaching with sulfuric acid, adjusting the pH to 3-4, and filtering to obtain a crude manganese sulfate solution and manganese slag;

[0035] Step E2: Purify the crude manganese sulfate solution using sodium fumarate as a sulfide precipitant, and filter to obtain the manganese sulfate solution and nickel-cobalt-containing sulfide slag.

[0036] According to one aspect of the present invention, the amount of sodium carbonate used in step 3 is 2 to 20 kg / t; the low-sulfur manganese slag in step 4 is obtained by converting the low-sulfur manganese slag obtained in step 3 into deep phase transformation low-sulfur manganese slag; the process of converting the low-sulfur manganese slag into deep phase transformation low-sulfur manganese slag is specifically as follows: the low-sulfur manganese slag obtained in step 3 and sodium carbonate are placed in water, reacted at 10 to 60°C for 5 to 30 minutes, so that the calcium sulfate in the low-sulfur manganese slag is further converted into calcium carbonate, filtered, and obtained deep phase transformation low-sulfur manganese slag; wherein the amount of sodium carbonate used is 20 to 60 kg / t, the liquid-to-solid volume mass ratio is 2 to 5:1, and the SO3 content of the deep phase transformation low-sulfur manganese slag is less than 0.5%.

[0037] Beneficial effects of the present invention:

[0038] (1) The present invention can render manganese slag harmless through the process of manganese ore particle size classification - leaching - leachate purification - manganese slag particle size classification - calcium sulfate partial phase transformation fine floc flotation, and divide the manganese slag into high-sulfur manganese slag with a CaSO4 content of more than 15% and low-sulfur manganese slag with a CaSO4 content of less than 5%, which are used as cement retarder and cement clinker respectively, organically connecting the manganese slag with the cement industry chain, realizing efficient utilization of manganese slag, and no new pollutants are generated, which is conducive to clean production in the manganese industry;

[0039] (2) The manganese slag treatment method based on the physical separation of manganese ore and manganese slag provided by the present invention is mainly a physical method, does not require heating during the process, and will not introduce new harmful impurities. The process is simple, the cost is low, and it has good technical economy and technical stability;

[0040] (3) The present invention is based on the difference in the distribution of calcium sulfate (CaSO4) in coarse and fine-grained manganese slag, that is, calcium sulfate is more distributed in fine-grained manganese slag and coarse-grained manganese slag contains less calcium sulfate. The method of controlling the particle size of manganese ore and coarse-grained manganese slag is creatively proposed. Compared with the existing manganese ore with a particle size of -0.15mm to be leached after crushing and grinding, the manganese ore of the present application is subjected to particle size classification, and the coarse-grained manganese ore obtained has a large particle size, and the coarse particles with a particle size of -2 to +0.15mm account for 70%, so that when the manganese slag is subsequently subjected to particle size classification, it is easier to obtain coarse-grained manganese slag, and the coarse-grained manganese slag accounts for a large proportion. This greatly improves the separation of calcium sulfate from manganese slag, allowing for easy separation of calcium sulfate. This technology further utilizes a fine-grained floc flotation technique using partial phase conversion of calcium sulfate. This involves adding an excess of Na2CO3, causing a portion of the Na2CO3 to react with CaSO4 in the fine-grained manganese slag to produce CaCO3, which then encapsulates the CaSO4. The remaining Na2CO3, combined with an anionic flocculant and sodium oleate, encapsulates the CaSO4 and floats it off the surface. This enhances the calcium sulfate separation process, further phase conversion of the low-sulfur manganese slag, resulting in a deep phase conversion low-sulfur manganese slag with a SO3 content of less than 0.5%. This method not only incorporates the manganese slag treatment process but also improves the manganese ore treatment process, proposing a systematic solution for the resource utilization of manganese slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a process flow chart for preparing low-sulfur manganese slag and high-sulfur manganese slag by the method for wet cascade desulfurization of manganese slag in Example 1 of the present invention;

[0042] Figure 2 This is a process flow chart for preparing cement according to Example 2 of the present invention;

[0043] Figure 3 This is a process flow chart of manganese ore particle size classification-leaching-step precipitation in comparative example 4 of the present invention;

[0044] Figure 4 Flow chart of the flotation process of fine-grained manganese slag described in Examples 4 and 5 of the present invention;

[0045] Figure 5 This is a closed-circuit flotation process flow chart of fine-grained manganese slag in Comparative Example 3 of the present invention;

[0046] Figure 6 This is the XRD pattern of the cement clinker prepared in Example 2 of the present invention;

[0047] Figure 7 1 is the XRD pattern before and after the reaction of manganese slag and sodium carbonate described in Example 6 of the present invention. DETAILED DESCRIPTION

[0048] To make the present invention easier to understand, the present invention is further described below with reference to specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by professional and technical personnel in this field; unless otherwise specified, the raw materials and reagents involved in this article can be purchased from the market or prepared by known methods.

[0049] It should be noted that the SO3 described in this application exists in the form of sulfate, but when expressing the content, it is often calculated as sulfur trioxide.

[0050] It should be noted that the unit "kg / t" in this application refers to a certain number of kilograms of a substance added per ton of manganese slag. For example, "the dosage of sodium oleate is 1 kg / t" means that 1 kilogram of sodium oleate is added per ton of manganese slag.

[0051] Example 1

[0052] The manganese ore used in this embodiment is manganese carbonate ore from Guizhou, and its Mn grade is 16.74%.

[0053] Use Figure 1 The process shown is for processing manganese ore, and the specific steps are as follows:

[0054] S1: Manganese ore is crushed and ground, and coarse manganese ore with a particle size of -2mm is screened out, and the coarse manganese ore with a particle size of -2 to +0.15mm accounts for more than 70%, of which the manganese ore with a particle size of -2 to +1mm accounts for 43.21%. Sulfuric acid is used as a leaching agent, and the manganese ore with a particle size of -2 to +1mm is leached under the conditions of a mineral acid mass ratio of 1:1 and a liquid-solid volume mass ratio of 4:1. After leaching at 55°C for 1h, air is introduced for oxidation leaching. The divalent iron ions in the solution are removed, and sodium thiamethoxam is used as a sulfide precipitant to purify the leachate, lime is used as a pH adjuster, the pH of the solution is adjusted to 4, and a manganese sulfate solution and a manganese slag are obtained by filtration. The manganese slag is washed with water to obtain a washed manganese slag. The manganese sulfate solution can be used as a qualified electrolytic manganese solution, and the manganese content in the solution is 34.56 g / L, the magnesium content is 3.10 g / L, and the contents of Ni, Co, Fe, etc. are all less than 1 mg / L;

[0055] S2: The washed manganese slag is subjected to particle size classification to obtain coarse manganese slag with a particle size of ≥0.074 mm and fine manganese slag with a particle size of ≤0.074 mm, wherein the coarse manganese slag with a particle size of ≥0.074 mm accounts for 44.12% of the mass of the manganese slag and has a SO3 content of 6.24%;

[0056] S3: Dispersing fine manganese slag with water to a pulp concentration of 20%, adjusting the pulp pH to 7.5 with 8.0 kg / t sodium carbonate, stirring for 1 to 3 minutes, adding 15 g / t anionic polyacrylamide to the pulp and stirring for 1 to 5 minutes, then adding 2.4 kg / t sodium oleate and stirring for 3 to 5 minutes for flotation, obtaining high-sulfur manganese slag and low-sulfur tailings by flotation, and treating the flotation wastewater for recycling;

[0057] S4: The low-sulfur tailings are mixed with coarse manganese slag to obtain low-sulfur manganese slag, which is used as a raw material for preparing cement clinker and has an SO3 content of 4.60%. The high-sulfur manganese slag is used as a cement retarder and has an SO3 content of 42.35%.

[0058] Example 2

[0059] The low-sulfur manganese slag and high-sulfur manganese slag used in this example are from Example 1. Figure 2 The process flow shown is used to prepare cement, and the specific steps are as follows:

[0060] S1: Grind the low-sulfur manganese slag, add limestone and silica sand according to the ratio of low-sulfur manganese slag to limestone of 2:3 to adjust the ratio of Ca, Si and Al in the cement raw material, calcine the adjusted cement raw material at 1300°C to obtain cement clinker, and perform XRD characterization on the cement clinker. The results are as follows: Figure 6 shown by Figure 6 It can be seen that the XRD peaks of the product obtained by roasting are consistent with the characteristic peaks of C2S and C3S, indicating that the product is cement clinker;

[0061] S2: Cement clinker and high-sulfur manganese slag were mixed in a mass ratio of 30:1, and the mixture was ground to -0.074 mm to obtain cement. After testing, the SO3 content in the cement was 3.29%, which met the requirement of the national standard "General Portland Cement" (GB 175-2007) that the SO3 content in slag Portland cement should be ≤4.0%.

[0062] Example 3

[0063] The manganese ore used in this embodiment comes from Guizhou, and its composition is the same as that of the manganese ore used in Example 1. Figure 1 The process described above is to carry out particle size classification and leaching treatment on manganese ore, specifically:

[0064] S1: Manganese ore is crushed, ground and graded to obtain coarse manganese ore with a particle size of -2 mm, of which manganese ore particles of -2 to +1 mm account for 47.12%;

[0065] S2: Using sulfuric acid as a leaching agent, leaching the manganese ore particles of -2 to +1 mm described in S1 with sulfuric acid at a mineral acid mass ratio of 1:1, a liquid-solid volume mass ratio of 2:1, and a leaching temperature of 70°C, aerating air after leaching for 3 hours, and adding lime to adjust the pH to 3.5, then adding sodium fumarate as a sulfide precipitant to purify the leachate, and filtering to obtain a manganese sulfate solution and a cobalt-nickel-zinc-manganese slag, wherein the manganese sulfate solution has a Mn content of 34.5 g / L, a Mg content of 2.4 g / L, and Fe, Ni, Co, and Zn contents of less than 1 mg / L, and can be used as a qualified solution for producing electrolytic manganese;

[0066] S3: The manganese slag was subjected to particle size classification, and SO3 in the manganese slag of each particle size classification was analyzed. The results are shown in Table 1.

[0067] Table 1 Analysis of SO3 content after leaching of coarse manganese ore and purification slag particle size classification

[0068]

[0069] Example 4

[0070] The manganese slag used in this example comes from an electrolytic manganese plant in Guizhou. It is a mixture of leaching slag, neutralization precipitate slag and sulfide precipitate slag obtained from manganese carbonate ore. The particle size is -0.15mm and the SO3 content is 12.82%. After the manganese slag is subjected to particle size classification (see Table 4 of Comparative Example 1), it is treated as follows: Figure 4 The flotation process of fine manganese slag is as follows:

[0071] Fine-grained manganese slag (-0.074 mm) was dispersed in water to a 20% slurry concentration. The slurry was adjusted to a pH of 7.5 with 8.0 kg / t of sodium carbonate and stirred for 3 minutes. 15 g / t of anionic flocculant was added to the slurry and stirred for 5 minutes. Subsequently, 2.4 kg / t of sodium oleate was added and stirred for 5 minutes before flotation. High-sulfur manganese slag and low-sulfur tailings were obtained by flotation. The flotation wastewater was treated and recycled. The anionic flocculant was either sodium polyacrylate or anionic polyacrylamide. The flotation results are shown in Table 2.

[0072] Table 2 Flotation results of fine manganese slag

[0073]

[0074] Example 5

[0075] The manganese slag used in this embodiment is the same as that in embodiment 4. After the manganese slag is subjected to particle size classification, the Figure 4The flotation process of fine-grained manganese slag (-0.074 mm) was carried out. The difference between this embodiment and Example 5 is that the anionic flocculant used in this embodiment is anionic polyacrylamide, the amount of dextrin used is 0.6 kg / t, the amount of sodium carbonate used is 8.0 kg / t, and the amount of sodium oleate used is 1.2-6.0 kg / t. The results are shown in Table 3.

[0076] Table 3 Flotation results of fine manganese slag

[0077]

[0078] Example 6

[0079] The manganese slag used in this example is the same as that in Example 4. To prove that the presence of Na2CO3 can cause a phase transformation of part of CaSO4, this example is stirred for 10 minutes under the conditions of a slurry concentration of 20%, a sodium carbonate dosage of 80kg / t, an anionic flocculant dosage of 15g / t, a sodium oleate dosage of 2kg / t, and a pH of 8. After solid-liquid separation, the solid product is collected and dried, and the product is characterized by XRD. The results are shown in FIG. Figure 7 shown. Figure 7 This study demonstrates that under flotation conditions, Na₂CO₃ can partially convert the CaSO₄ in manganese slag into CaCO₃. The Na₂SO₄ in solution is recycled with the flotation wastewater. When the concentration reaches a certain level, the flotation wastewater is collected in an open circuit and sodium sulfate crystals are recovered by evaporation and crystallization.

[0080] Example 7

[0081] The low-sulfur manganese slag used in this example was from Example 1. To further reduce the SO₃ content in the low-sulfur manganese slag, Na₂CO₃ was used to phase-convert the CaSO₄ in the low-sulfur manganese slag into CaCO₃. The low-sulfur manganese slag was uniformly mixed with 20 kg / t of Na₂CO₃ at room temperature. The mixture was reacted for 10 minutes at a liquid-to-solid volume mass ratio of 4:1, a temperature of 25°C, and a pH of 8. After solid-liquid separation, a deep phase-conversion low-sulfur manganese slag was obtained. Analysis of the deep phase-conversion low-sulfur manganese slag revealed a SO₃ content of 0.4%, significantly reduced from 4.60% before the reaction.

[0082] Comparative Example 1

[0083] The manganese slag of this comparative example is the same as that of Example 4. The electrolytic manganese slag was subjected to particle size classification, and the specific composition is shown in Table 4.

[0084] Table 4 Analysis of SO3 content after manganese slag particle size classification

[0085]

[0086] Comparative Example 2

[0087] The manganese slag used in this comparative example is the same as that in Example 4. Figure 1 The process shown is to carry out particle size classification and flotation of manganese slag, specifically:

[0088] S1: washing the manganese slag with water at a liquid-to-solid volume mass ratio of 4:1 and a temperature of 25°C, filtering to obtain a manganese slag washing liquid and a washed manganese slag, and recycling the manganese slag washing liquid after treatment;

[0089] S2: The washed manganese slag is subjected to particle size classification to obtain coarse manganese slag with a particle size of ≥0.074 mm and fine manganese slag with a particle size of ≤0.074 mm. The coarse manganese slag accounts for 5.13% and has a SO3 content of 1.71%, while the fine manganese slag accounts for 94.87% and has a SO3 content of 12.85%.

[0090] S3: Dispersing fine manganese slag in water to a pulp concentration of 20%, adding 8.0 kg / t of sodium carbonate to adjust the pulp pH to 7.5, stirring for 3 minutes, adding 15 g / t of anionic flocculant to the pulp and stirring for 5 minutes, then adding 2.4 kg / t of sodium oleate and stirring for 5 minutes for flotation, obtaining high-sulfur manganese slag and low-sulfur tailings by flotation, treating the flotation wastewater and recycling it, and measuring and analyzing the yield of the low-sulfur tailings to be 46.13%, and the SO3 content thereof to be 5.42%, and the yield of the high-sulfur manganese slag to be 49.92%, and the SO3 content thereof to be 19.01%;

[0091] S4: The low-sulfur tailings are mixed with coarse-grained manganese slag to obtain low-sulfur manganese slag as a raw material for preparing cement clinker, and its SO3 content is 3.24%. The high-sulfur manganese slag is used as a cement retarder, and its SO3 content is 19.01%.

[0092] Comparative Example 3

[0093] The manganese slag used in this comparative example is the same as that in Example 4. After the manganese slag is subjected to particle size classification, the following Figure 5 The flotation closed-circuit experiment of fine manganese slag was carried out in the following process:

[0094] Step 1: Dispersing fine manganese slag with water to a pulp concentration of 20%, adding 8 kg / t of sodium carbonate to adjust the pulp pH to 7.5, stirring for 3 minutes, adding 15 g / t of anionic flocculant to the pulp and stirring for 5 minutes, then adding 2.4 kg / t of sodium oleate and stirring for 5 minutes for roughing, to obtain roughing tailings and high-sulfur manganese slag;

[0095] Step 2: Add 1.0 kg / t sodium oleate to the roughing tailings obtained from the roughing process to perform a scavenging process to obtain middlings and low-sulfur tailings, wherein the middlings are returned to the roughing process.

[0096] Measurement and analysis of high-sulfur manganese slag and low-sulfur tailings showed that the yield of high-sulfur manganese slag was 58.15%, and its SO3 content was 22.41%; the yield of low-sulfur tailings was 41.85%, and its SO3 content was 1.31%.

[0097] Comparative Example 4

[0098] The manganese ore used in this comparative example is the same as that in Example 1. Figure 3 The process described is to carry out particle size classification, leaching and step-by-step precipitation treatment of manganese ore, specifically:

[0099] S1: Manganese ore is crushed, ground and graded to obtain coarse manganese ore with a particle size of -2 mm, of which manganese ore particles with a particle size of -0.6 to +0.355 mm account for 21.35%;

[0100] S2: Using sulfuric acid as a leaching agent, leaching the manganese ore particles of -0.6 to +0.355 mm described in S1 with sulfuric acid at a mineral acid mass ratio of 1:1, a liquid-solid volume mass ratio of 2:1, and a leaching temperature of 70°C. After leaching for 3 hours, air is introduced, and lime is added to adjust the pH to 4 before filtering to obtain a crude manganese sulfate solution and a mixed slag of leaching residue and neutralization precipitation residue. The solution has a Mn content of 30.47 g / L, a Mg content of 3.47 g / L, a Zn content of 25 mg / L, a Co content of 35 mg / L, and Fe and Ni contents of less than 1 mg / L. The crude manganese sulfate solution is further purified by sulfide precipitation to obtain a manganese sulfate solution and nickel-cobalt-zinc sulfide slag.

[0101] S3: The manganese slag described in S2 is subjected to particle size classification, and SO3 of the manganese slag of each particle size classification is analyzed. The results are shown in Table 5.

[0102] Table 5 Analysis of SO3 content after leaching of coarse manganese ore and manganese slag particle size classification

[0103]

[0104] Result analysis:

[0105] It can be seen from Table 1 of Example 3 and Table 4 of Comparative Example 1 that the proportion of coarse-grained manganese slag in Example 3 (42.08%) is much greater than that in Comparative Example 1 (5.02%), indicating that the use of the manganese ore size-grading leaching method of the present invention is beneficial to increasing the proportion of coarse-grained manganese slag.

[0106] It can be seen from Table 5 of Comparative Example 4, Table 4 of Comparative Example 1 and Table 1 of Example 3 that the proportion of coarse-grained manganese slag in Comparative Example 4 (20.12%) is greater than that in Comparative Example 1 (5.02%), and less than that in Example 3 (42.08%), indicating that increasing the particle size of the leached manganese ore is beneficial to increasing the proportion of coarse-grained manganese slag.

[0107] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for wet cascade desulfurization of manganese slag, characterized in that: The following steps are involved: Step 1: crushing, grinding, and particle size classification of manganese ore, leaching with sulfuric acid, adjusting the pH, purifying, and filtering to obtain a manganese sulfate solution and a manganese slag; wherein, after particle size classification, the coarse manganese ore with a particle size of -2 mm is obtained, and the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%; Step 2: washing the manganese slag with water, filtering to obtain a manganese slag washing liquid and a washed manganese slag, wherein the manganese slag washing liquid is purified and recycled; and the washed manganese slag is subjected to particle size classification to obtain a coarse manganese slag with a particle size of ≥0.074 mm and a fine manganese slag with a particle size of ≤0.074 mm. Step 3: Dispersing fine-grained manganese slag of -0.074 mm in water to form a slurry, and converting part of the calcium sulfate in the manganese slag into a calcium carbonate phase with sodium carbonate, while adjusting the slurry pH to 7.5 and stirring for 1 to 3 minutes, adding an anionic flocculant to the slurry and stirring for 1 to 5 minutes, then adding sodium oleate and stirring for 3 to 5 minutes to perform fine floc flotation, obtaining high-sulfur manganese slag and low-sulfur tailings by flotation, and treating the flotation wastewater for recycling; wherein, the slurry concentration is 15% to 30%; the amount of sodium oleate is 1 to 6 kg / t; the amount of sodium carbonate is 2 to 20 kg / t; and the anionic flocculant comprises one or both of polyacrylamide and sodium polyacrylate; Step 4: Mix the low-sulfur tailings with coarse-grained manganese slag with a particle size of ≥0.074 mm to obtain low-sulfur manganese slag as a raw material for preparing cement clinker, and use the high-sulfur manganese slag as a cement retarder; wherein the SO3 content in the low-sulfur manganese slag is less than 5%; and the SO3 content in the high-sulfur manganese slag is greater than 15%.

2. The method for wet cascade desulfurization of manganese slag according to claim 1, characterized in that: The manganese ore includes any one of manganese carbonate ore and manganese oxide ore.

3. The method for wet cascade desulfurization of manganese slag according to claim 1, characterized in that: The main mineral components of the manganese slag are CaSO4 and SiO2, the content of SO3 in the manganese slag is 10% to 30%, and the particle size of the manganese slag is -2 mm.

4. The method for wet cascade desulfurization of manganese slag according to claim 2, characterized in that: When manganese carbonate ore is used as raw material to produce electrolytic manganese or manganese sulfate, the step 1 is specifically as follows: Step A1: crushing, grinding, and particle size classification of manganese carbonate ore to obtain coarse manganese ore with a particle size of -2 mm; wherein the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%; Step A2: Leaching the coarse manganese ore with sulfuric acid at 40-70° C. for 1-3 hours, aerating the ore after leaching, adding lime to adjust the pH, adding sodium benzoate as a sulfide precipitant to purify the leachate, and filtering to obtain a manganese sulfate solution and manganese slag, wherein the manganese sulfate solution is a raw material in the electrolytic manganese production process or the manganese sulfate production process; When electrolytic manganese or manganese sulfate is produced using manganese oxide ore as raw material, step 1 is specifically as follows: Step B1: crushing, grinding, and particle size classification of the manganese oxide ore to obtain coarse manganese ore with a particle size of -2 mm, wherein the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%; Step B2: Leaching the coarse manganese ore with sulfuric acid with the assistance of a reducing agent at 70-100° C. for 1-4 hours, aerating the ore after leaching, adding lime to adjust the pH, and purifying the leachate by adding sodium fumarate as a sulfide precipitant. The leached solution is filtered to obtain a manganese sulfate solution and a manganese slag, wherein the manganese sulfate solution is a raw material in the electrolytic manganese production process or the manganese sulfate production process. Wherein, the reducing agent includes at least one of pyrite, sulfur dioxide, and manganese sulfide.

5. The method for wet cascade desulfurization of manganese slag according to claim 1, characterized in that: The manganese slag is a mixture of leaching slag, neutralization precipitated slag and sulfide precipitated slag; or a mixture of leaching slag and neutralization precipitated slag; When the obtained manganese slag is a mixture of leaching slag, neutralization precipitated slag and sulfide precipitated slag, the step 1 is specifically as follows: Step C1: crushing, grinding, and particle size classification of manganese carbonate ore to obtain coarse manganese ore with a particle size of -2 mm; wherein the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%; Step C2: leaching the coarse manganese ore with sulfuric acid at 40-70° C. for 1-3 hours, introducing air after leaching, adding lime to adjust the pH, adding sodium furam as a sulfide precipitant to purify the leachate, and filtering to obtain a manganese sulfate solution and a mixture of leaching residue, neutralization precipitate residue, and sulfide precipitate residue; When the obtained manganese slag is a mixture of leaching slag and neutralization precipitation slag, the step 1 is specifically as follows: Step D1: crushing, grinding, and particle size classification of manganese carbonate ore to obtain coarse manganese ore with a particle size of -2 mm; wherein the coarse manganese ore with a particle size of -2 to +0.15 mm accounts for more than 70%; Step D2: leaching the coarse manganese ore with sulfuric acid at 40-70° C. for 1-3 hours, introducing air after leaching, adding lime to adjust the pH, and filtering to obtain a crude manganese sulfate solution and a mixture of leached residue and neutralized precipitated residue; Step D3: sodium fumarate is added as a sulfide precipitant to purify the crude manganese sulfate solution, and the manganese sulfate solution and sulfide slag are obtained by filtration.

6. The method for wet cascade desulfurization of manganese slag according to claim 1, characterized in that: In step 4, when preparing cement clinker with the low-sulfur manganese slag, limestone and silica sand need to be added; wherein, the mass ratio of the limestone to the low-sulfur manganese slag is 5:1-4; and the sintering temperature for preparing cement clinker is 1250-1400°C.

7. The method for wet cascade desulfurization of manganese slag according to claim 1, characterized in that: Step 1 also includes step-by-step purification, and step 1 including step-by-step purification is specifically: Step E1: crushing, grinding, and grading the manganese ore, leaching with sulfuric acid, adjusting the pH to 3-4, and filtering to obtain a crude manganese sulfate solution and manganese slag; Step E2: Purify the crude manganese sulfate solution using sodium fumarate as a sulfide precipitant, and obtain the manganese sulfate solution and nickel-cobalt-containing sulfide slag by filtration.

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