Method for preparing high-purity aragonite-type calcium carbonate whiskers from electrolytic manganese residue

Abstract

This invention provides a method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag. The method includes: adding tetrasodium IDS to the leachate of the electrolytic manganese slag, stirring and reacting to obtain an intermediate solution; the molar concentration ratio of tetrasodium IDS to manganese ions in the leachate is 1.2-2; slowly adding ammonia water to the intermediate solution while continuously introducing CO2 gas; after the reaction is complete, performing solid-liquid separation, drying the filter cake, and obtaining aragonite-type calcium carbonate whiskers. This invention uses electrolytic manganese slag as raw material to prepare high-value-added aragonite-type calcium carbonate whisker materials, achieving high-value utilization and full-component resource utilization while mitigating the environmental pollution caused by electrolytic manganese slag; this invention fully utilizes the soluble chemical components of electrolytic manganese slag while reducing production costs; and the entire preparation process is carried out at low temperature and normal pressure; the entire process generates no waste.

Description

Technical Field

[0001] This invention relates to the field of electrolytic manganese slag treatment, and more specifically, to a method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag. Background Technology

[0002] Electrolytic manganese slag is a strongly acidic or neutral solid waste generated during the pressure filtration process in the electrolytic production of metallic manganese. Currently, approximately 10 million tons are discharged annually nationwide, with historical stockpiles exceeding 100 million tons. It is in the form of a mud cake, with a moisture content of 28%-35%, and its main components include SiO2, CaSO4·2H2O, Fe2O3, Al2O3, and soluble Mn and NH4+. + SO4 2- The pH value is 3-6. Due to its high concentration of soluble manganese and ammonia nitrogen, direct storage of electrolytic manganese slag can easily lead to soil acidification, excessive manganese / ammonia nitrogen levels in groundwater, and long-term risks to the surrounding ecosystem. Currently, electrolytic manganese slag is mainly used in the production of cement clinker, new wall materials, permeable bricks, and roadbed materials.

[0003] Calcium carbonate whiskers are artificially synthesized single-crystal materials with aragonite-type calcium carbonate as the main component. They have a fibrous structure and a relative density of 2.8 g / cm³. 3 The crystals are 20-80 μm in length, 0.5-2 μm in diameter, and have an aspect ratio of 20-30. They are non-toxic, odorless, high-strength, and heat-resistant and insulating. They are mainly prepared using hydrothermal methods, chemical precipitation methods, and modified carbonation methods. Calcium carbonate whiskers are a new type of inorganic filler following nano-calcium carbonate. They are non-toxic, odorless, and appear as a white, fluffy solid. As a new generation of filler material, they possess high comprehensive mechanical strength and can reduce vibration, prevent slippage, reduce noise, and absorb waves during use. The powder generated after friction is non-toxic and produces minimal pollution.

[0004] To date, no research has been found on the preparation of aragonite-type calcium carbonate whiskers from electrolytic manganese slag, nor has any report been found on the preparation of high-purity, high-whiteness aragonite-type calcium carbonate whiskers, co-production of manganese fertilizer, and treatment of waste liquid using electrolytic manganese slag salt leaching solution as raw material, based on the selective complexation characteristics of sodium tetrasodium IDS with manganese ions in the calcium-manganese system, proposed in this invention. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one of the aforementioned deficiencies in the prior art. For example, one objective of this invention is to prepare high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag as raw material, and another objective is to simultaneously achieve wastewater treatment.

[0006] To achieve the above objectives, the present invention provides a method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag.

[0007] The method includes: (1) adding tetrasodium IDS to the leachate of electrolytic manganese slag and stirring to obtain an intermediate solution; wherein the leachate of electrolytic manganese slag is obtained by leaching with ammonium chloride solution; the ratio of the molar concentration of tetrasodium IDS to the molar concentration of manganese ions in the leachate is 1.2~2; (2) slowly adding ammonia water to the intermediate solution while continuously introducing CO2 gas, and after the reaction is completed, performing solid-liquid separation to obtain a filter cake, drying the filter cake to obtain aragonite-type calcium carbonate whiskers.

[0008] Alternatively, the temperature of the stirring reaction in step (1) is 60~90℃ and the time is 1~5min.

[0009] Alternatively, the ammonia solution may be added by: slowly adding it to the solution using a peristaltic pump at a speed of 2 to 10; the amount of ammonia solution added may be determined according to the molar ratio of hydroxyl groups to calcium ions of 2 to 3.

[0010] Optionally, the CO2-containing gas is introduced at a rate of 60-250 mL / min for a duration of 60-120 min.

[0011] Alternatively, the reaction in step (2) can be carried out at a temperature of 70-95°C for a time of 60-120 min.

[0012] Alternatively, the properties of the aragonite-type calcium carbonate whiskers include: aragonite phase crystal form, fibrous morphology, fiber aspect ratio of 12-24, whiteness greater than 96, CaCO3 content greater than 99.9%, and Mn content greater than 99.9%. 2+ The content is less than 0.0001%.

[0013] Alternatively, the method further includes step (3): adding hydrochloric acid to the filtrate obtained in step (2) to adjust the pH to acidic, and then adding barium chloride dihydrate to react and precipitate SO4 in the solution. 2- After precipitation, solid-liquid separation is performed, and the filtrate is collected. The filtrate is evaporated and concentrated, and then anhydrous ethanol is slowly added under continuous stirring to obtain a mixed system. The mixed system is allowed to stand and age, and then solid-liquid separation is performed. The obtained solid is dried to obtain manganese fertilizer, and the obtained filtrate is evaporated and crystallized to obtain ammonium chloride.

[0014] Alternatively, the manganese fertilizer may be manganese iminodisuccinate.

[0015] Alternatively, the amount of anhydrous ethanol added may be determined as 0.5 to 12 times the volume of the evaporated and concentrated solution.

[0016] Alternatively, the temperature for static aging is 60-80°C, and the time is 30-90 minutes.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least one of the following: (1) On the one hand, this invention utilizes the selective complexation property of sodium IDS tetrasodium with manganese ions in the calcium-manganese system, so that manganese does not participate in the subsequent mineralization reaction, laying the foundation for obtaining high-purity mineralization products. On the other hand, it utilizes the unique crystal structure of aragonite-type calcium carbonate to prevent manganese ions in the system from undergoing isomorphic substitution with calcium ions, thereby further realizing the separation of manganese and calcium carbonate in the mineralization system and obtaining high-purity calcium carbonate products.

[0018] (2) This invention uses electrolytic manganese slag as raw material to prepare high-value-added aragonite-type calcium carbonate whisker material; while eliminating the environmental pollution caused by electrolytic manganese slag, it realizes the high-value-added and resource utilization of all components.

[0019] (3) The prepared iminodisuccinate manganese is an environmentally friendly manganese micro-fertilizer. It replenishes the soil with manganese while being easily degraded and harmless to the soil and environment.

[0020] (4) In the preparation of aragonite-type calcium carbonate whiskers, the present invention directly utilizes magnesium chloride contained in electrolytic manganese slag as a crystal form control mechanism; no additional additives are required, which makes full use of the soluble chemical components of electrolytic manganese slag while reducing production costs. Moreover, the entire preparation process is carried out at low temperature and normal pressure.

[0021] (5) This invention makes full use of the various chemical components contained in electrolytic manganese slag. Salt additives such as ammonium chloride can be recovered, sulfate is recovered in the form of barium sulfate, manganese and IDS are recovered in the form of manganese iminodisuccinate, and the whole process has no waste residue, waste gas and wastewater discharge.

[0022] (6) The present invention uses simulated industrial flue gas as a source of CO2, which can synergistically solidify the CO2 generated during the formation of electrolytic manganese slag, thereby realizing the resource utilization of electrolytic manganese slag while achieving low-carbon production in the electrolytic manganese industry. Attached Figure Description

[0023] The above and other objects and / or features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which: Figure 1 The XRD pattern of the carbonated product obtained in Example 1 is shown.

[0024] Figure 2 The infrared spectrum of the carbonated product obtained in Example 1 is shown.

[0025] Figure 3 The microstructure of the carbonated product obtained in Example 1 is shown. Detailed Implementation

[0026] In the following, the method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to the present invention will be described in detail with reference to exemplary embodiments.

[0027] Exemplary Example 1 This exemplary embodiment provides a method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag. The preparation method may include the following steps: (1) Add tetrasodium IDS to the leachate of electrolytic manganese slag and stir to obtain an intermediate solution. The leachate of electrolytic manganese slag is obtained by leaching with ammonium chloride solution. The mass of tetrasodium IDS is determined as follows: the ratio of the molar concentration of tetrasodium IDS to the molar concentration of manganese ions in the leachate is 1.2 to 2, for example, a molar concentration ratio of 1.3, 1.4, 1.5, 1.7, 1.9, etc.

[0028] In this embodiment, the reaction temperature is 60~90℃, such as 61, 70, 80, 85, 89℃, etc., and the time is 1~5min, such as 2, 3, 4min, etc.

[0029] In this embodiment, the stirring rate is 60~120 rpm and the stirring time is 1~5 min.

[0030] (2) Ammonia water is slowly added to the intermediate solution while CO2 gas is continuously introduced. After the reaction is completed, solid-liquid separation is performed to obtain a filter cake. The filter cake is dried to obtain aragonite-type calcium carbonate whiskers.

[0031] In this embodiment, the ammonia solution is added by slowly adding a certain volume of ammonia solution to the solution using a peristaltic pump at a rotation speed of 2 to 10 rpm. The amount of ammonia solution added is determined according to the molar ratio of hydroxyl groups to calcium ions of 2 to 3, for example, by molar ratios of 2.1, 2.5, 2.7, or 2.9.

[0032] In this embodiment, as an example, the CO2 gas can be introduced at a rate of 30-300 mL / min for a duration of 60-120 min.

[0033] The CO2-containing gas may include at least one of the following: industrial flue gas, simulated industrial flue gas, industrial-grade CO2, etc., in which the CO2 concentration is not less than 15%.

[0034] In this embodiment, in step (2), the temperature of the reaction can be 70~95℃, such as 71, 80, 85, 90, 94℃, etc., and the time can be 60~120min, such as 61, 70, 80, 90, 100, 110, 115min, etc.

[0035] In this embodiment, the drying temperature is 50~95℃ and the drying time is 12~24h.

[0036] In this embodiment, the properties of the aragonite-type calcium carbonate whiskers include: the obtained calcium carbonate has an aragonite phase crystal form, a fibrous morphology, an aspect ratio of 12-24, a whiteness greater than 96, a CaCO3 content greater than 99.9%, and a Mn content of [missing information]. 2+ The content is less than 0.0001%.

[0037] Exemplary Example 2 Based on exemplary embodiment 1, the method further includes step (3): Hydrochloric acid was added to the filtrate obtained in step (2) to adjust the pH to acidic, and then barium chloride dihydrate was added to react and precipitate SO4 in the solution. 2- After precipitation, solid-liquid separation is performed, and the filtrate is collected. The filtrate is evaporated and concentrated, and then anhydrous ethanol is added at once under continuous stirring to obtain a mixed system. The mixed system is allowed to stand and age, and then solid-liquid separation is performed. The obtained solid is dried to obtain manganese fertilizer, and the obtained filtrate is evaporated and crystallized to obtain ammonium chloride.

[0038] In this embodiment, the amount of barium chloride dihydrate added is determined according to the concentration of sulfate in the filtrate. The reaction carried out by adding barium chloride dihydrate can be a shaking reaction, for example, the reaction is carried out in a constant temperature water bath shaking table, the reaction temperature is 60~80℃, and the time is 30~120min.

[0039] In this embodiment, the amount of anhydrous ethanol added is determined to be 0.5 to 1 times the solution volume (i.e., the volume of the solution after evaporation and concentration), for example, 0.6, 0.7, 0.8, 0.9 times, etc., and the anhydrous ethanol is added all at once.

[0040] In this embodiment, the temperature for static aging can be 60~80℃, and the time can be 30~90min.

[0041] In this embodiment, the drying temperature can be 50~95℃ and the drying time can be 12~24h.

[0042] In this embodiment, the obtained manganese fertilizer is manganese iminodisuccinate.

[0043] Exemplary Example 3 Based on exemplary embodiment 1 or 2, the leachate from the electrolytic manganese slag in step (1) can be prepared by the following method: Electrolytic manganese slag and ammonium chloride solution are mixed and then subjected to a shaking reaction. After the reaction is completed, solid-liquid separation is performed to obtain the leachate of electrolytic manganese slag.

[0044] The dosage relationship between electrolytic manganese slag and ammonium chloride solution is as follows: ammonium chloride concentration 2~5 mol / L, liquid-to-solid ratio 20~50 mL / g. The shaking reaction is carried out in a constant temperature water bath shaking table at a temperature of 30~100℃ for 2~60 min.

[0045] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0046] Example 1 Using electrolytic manganese slag from an electrolytic manganese plant in Sichuan as raw material, 20 g of electrolytic manganese slag was placed in a 1000 mL Erlenmeyer flask, and 500 mL of 2 mol / L ammonium chloride solution was added. The mixture was reacted in a 30 ℃ constant temperature water bath shaking table for 3 min. After the reaction was completed, solid-liquid separation was performed, and the filtrate was collected.

[0047] 400 mL of the filtrate was measured into a 500 mL beaker, and 6.02 g of IDS tetrasodium was added. The mixture was reacted in a 75 ℃ constant-temperature magnetically stirred water bath for 30 min. After the reaction, 60 mL of 5.5 mol / L ammonia solution was slowly added to the solution using a peristaltic pump at a speed of 5.6, while simultaneously introducing simulated industrial flue gas (CO2-N2 ratio of 40%-60%) into the solution at a flow rate of 75 mL / min. The reaction was continued at 85 ℃ for 90 min. After the reaction, solid-liquid separation was performed, and the resulting filter cake was dried at 50 ℃. The resulting carbonated solid product was aragonite-type calcium carbonate whiskers. The carbonated solid product was analyzed by XRD, infrared spectroscopy, and SEM, and the results are shown below. Figure 1 , Figure 2 and Figure 3 As shown. The obtained product has an aragonite phase, a fibrous morphology, a whiteness of 97.1, and a calcium carbonate content of 99.93%. Mn 2+ The content is 0.00005%.

[0048] The obtained carbonation filtrate was collected in a 300 mL beaker, and hydrochloric acid was added dropwise to adjust the pH of the solution to 3.5 with stirring. 5.26 g of barium chloride dihydrate was added to the filtrate and reacted in an 80 °C constant temperature water bath shaking table for 60 min. After precipitation, solid-liquid separation was performed, and the solid was dried to obtain barium sulfate powder. The filtrate was collected and concentrated to approximately 100 mL at 105 °C. Subsequently, 100 mL of anhydrous ethanol was slowly added to the concentrate with continuous stirring, and the mixture was placed in a 60 °C constant temperature water bath for 1 h of aging. Finally, solid-liquid separation was achieved by centrifugation, and the obtained solid was dried at 50 °C to obtain manganese fertilizer (manganese iminodisuccinate). The filtrate was further evaporated and crystallized to obtain ammonium chloride.

[0049] Example 2 Using electrolytic manganese slag from an electrolytic manganese plant in Guizhou as raw material, 25 g of electrolytic manganese slag was placed in a 1000 mL Erlenmeyer flask, and 700 mL of 2.5 mol / L ammonium chloride solution was added. The mixture was reacted in a 30 ℃ constant temperature water bath shaking table for 5 min. After the reaction was completed, solid-liquid separation was performed, and the filtrate was collected.

[0050] 500 mL of the filtrate was measured into a 1000 mL beaker, and 5.91 g of IDS tetrasodium was added. The mixture was reacted in a water bath with magnetic stirring at 82 ℃ for 30 min. After the reaction, 80 mL of 3.5 mol / L ammonia solution was slowly added to the solution using a peristaltic pump at a speed of 5.6, while simultaneously introducing simulated industrial flue gas (CO2-N2 ratio of 50%-50%) into the solution at a flow rate of 120 mL / min. The reaction was continued at 85 ℃ for 90 min. After the reaction, solid-liquid separation was performed, and the resulting filter cake was dried at 50 ℃. The resulting carbonated solid product was aragonite-type calcium carbonate whiskers. The crystal phase of the product was aragonite, the morphology was fibrous, the whiteness was 98.3, the calcium carbonate content in the product was 99.93%, and the Mn content was [missing information]. 2+ The content is 0.00003%.

[0051] The obtained carbonation filtrate was collected in a 500 mL beaker, and hydrochloric acid was added dropwise to adjust the pH to 4 with stirring. 8.42 g of barium chloride dihydrate was added to the filtrate, and the mixture was reacted in an 80 °C water bath with shaking for 60 min. After precipitation, solid-liquid separation was performed, and the solid was dried to obtain barium sulfate powder. The filtrate was collected and concentrated to approximately 100 mL at 105 °C. Subsequently, 80 mL of anhydrous ethanol was slowly added to the concentrate with continuous stirring, and the mixture was placed in a 60 °C water bath for aging for 1 h. Finally, solid-liquid separation was achieved by centrifugation, and the obtained solid was dried at 50 °C to obtain manganese fertilizer (manganese iminodisuccinate). The filtrate was further evaporated and crystallized to obtain ammonium chloride.

[0052] Although the present invention has been described above in conjunction with exemplary embodiments and accompanying drawings, those skilled in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag, characterized in that, The method includes: (1) Add tetrasodium IDS to the leachate of electrolytic manganese slag and stir to obtain an intermediate solution; wherein the leachate of electrolytic manganese slag is obtained by leaching with ammonium chloride solution; the ratio of the molar concentration of tetrasodium IDS to the molar concentration of manganese ions in the leachate is 1.2~2. (2) Ammonia water is slowly added to the intermediate solution while CO2 gas is continuously introduced. After the reaction is completed, solid-liquid separation is performed to obtain a filter cake. The filter cake is dried to obtain aragonite-type calcium carbonate whiskers.

2. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 1, characterized in that, The temperature of the stirring reaction in step (1) is 60~90℃ and the time is 1~5min.

3. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 1, characterized in that, The ammonia solution is added by using a peristaltic pump to slowly add it to the solution at a speed of 2 to 10; the amount of ammonia solution added is determined according to the molar ratio of hydroxyl groups to calcium ions of 2 to 3.

4. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 1, characterized in that, The CO2-containing gas is introduced at a rate of 60-250 mL / min for a duration of 60-120 min.

5. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 1, characterized in that, The reaction in step (2) is carried out at a temperature of 70-95°C for 60-120 minutes.

6. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 1, characterized in that, The properties of the aragonite-type calcium carbonate whiskers include: aragonite crystal form, fibrous morphology, fiber aspect ratio of 12-24, whiteness greater than 96, CaCO3 content greater than 99.9%, and Mn content greater than 99.9%. 2+ The content is less than 0.0001%.

7. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 1, characterized in that, The method further includes step (3): adding hydrochloric acid to the filtrate obtained in step (2) to adjust the pH to acidic, and then adding barium chloride dihydrate to react and precipitate SO4 in the solution. 2- After precipitation, solid-liquid separation is performed, and the filtrate is collected. The filtrate was evaporated and concentrated, and then anhydrous ethanol was slowly added under continuous stirring to obtain a mixed system. The mixed system was allowed to stand and age, then solid-liquid separation was performed. The obtained solid was dried to obtain manganese fertilizer, and the obtained filtrate was evaporated and crystallized to obtain ammonium chloride.

8. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 7, characterized in that, The manganese fertilizer is manganese iminodisuccinate.

9. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 7, characterized in that, The amount of anhydrous ethanol added is determined to be 0.5 to 1 times the volume of the solution after evaporation and concentration.

10. The method for preparing high-purity aragonite-type calcium carbonate whiskers using electrolytic manganese slag according to claim 7, characterized in that, The static aging process is carried out at a temperature of 60-80℃ for 30-90 minutes.

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