Method for improving grade of beta-naphthol cobalt residue by alkali addition and low temperature curing method

Abstract

The application discloses a method for improving the grade of beta-naphthol cobalt residue by alkali low-temperature curing method, which comprises the steps of alkali low-temperature curing, water immersion and post-treatment. Alkali is added into cobalt residue and uniformly mixed to obtain material a; 2-4 times solid-liquid volume of material a is added into material a, and then the mixture is stirred and uniformly mixed, and then curing is carried out under the conditions of temperature 110-160 DEG C and time 1-4 h to obtain material b and flue gas c; the flue gas c is absorbed by water to prepare ammonia water; material b is cooled and then slurry is prepared by adding water to obtain material d; 3-12 times solid-liquid volume of water is added into material d, and then water immersion is carried out under the condition of temperature 30-80 DEG C to obtain material e; material e is filtered to obtain filtrate f and filter residue g; the filter residue g is washed by hot water for 2-4 times; the filtrate f is sent to water treatment after enrichment; and the filter residue g is cobalt-enriched residue. In the application, the specific conditions are adopted to carry out low-temperature curing on the cobalt residue, so that the nitrogen is separated from the cobalt in the form of ammonia which is easy to absorb and treat, and the grade of the cobalt residue is improved after the curing material is water immersed.

Description

Technical Field

[0001] This invention belongs to the field of mining engineering technology, specifically relating to a method for improving the grade of β-naphthol cobalt slag by low-temperature alkali curing. Background Technology

[0002] Sphalerite often contains metals such as cobalt. During zinc smelting, these metals dissolve into the zinc sulfate solution along with the zinc. When the concentration of cobalt ions in the zinc electrolyte reaches a certain level, it can cause the zinc electrolysis plate to melt back. This can affect the current efficiency and energy consumption of zinc electrolysis, or even hinder normal production. α-Nitrosaminoglycan (α-nitroso-β-naphthol) offers advantages such as good selectivity, low cost, and convenient operation for cobalt removal, and is widely used in zinc smelting and recycling processes. The resulting cobalt slag has a cobalt grade between 6-10%, and can be sold directly when the cobalt market is favorable. However, its relatively stable nature leads to a long and costly subsequent cobalt smelting and recycling process. Therefore, although the α-nitroso-β-naphthol cobalt slag has a suitable grade, the overall sales environment is not good. To reduce the amount of stockpiled cobalt slag and realize its economic value, it is necessary to consider how to effectively improve its cobalt grade to create better conditions for its sale. The traditional method is to dry the acid-washed cobalt slag and then calcine it directly. After burning off the organic matter, the cobalt grade is enriched to over 50%. However, because α-nitroso-β-naphthol contains nitrogen, its calcination process produces yellow fumes of nitrogen oxides, requiring a corresponding denitrification system for normal operation. Therefore, exploring other methods to effectively improve the grade of α-nitroso-β-naphthol cobalt slag is essential. Summary of the Invention

[0003] The purpose of this invention is to provide a method for improving the grade of β-naphthol cobalt slag through low-temperature alkali curing.

[0004] The objective of this invention is achieved by including the following steps: low-temperature alkali curing, water soaking, and post-treatment:

[0005] A. Low-temperature alkali curing method:

[0006] 1) Add sodium hydroxide to cobalt slag and mix well to obtain material a;

[0007] 2) Add 2 to 4 times the solid-liquid volume of material a to material a and mix well. Then, mature the mixture at 110 to 200°C for 1 to 4 hours to obtain material b and flue gas c. Flue gas c is used to absorb ammonia water.

[0008] B. Water immersion:

[0009] 1) After cooling material b, water is added to slurry to obtain material d;

[0010] 2) Add water to material d at a volume of 3 to 12 times that of material d (solid-liquid ratio), and soak in water at a temperature of 30 to 80°C to obtain material e;

[0011] C. Post-processing: Material e is filtered to obtain filtrate f and filter residue g. Filter residue g is washed with hot water 2-4 times. Filtrate f is the enriched liquid and sent for water treatment. Filter residue g is the enriched cobalt residue.

[0012] Under specific conditions, low-temperature aging of cobalt slag successfully separates nitrogen from cobalt using easily absorbed ammonia. Water leaching of the clinker then improves the grade of the cobalt slag. The specific principle is as follows: Nitrosyl groups in α-nitrosoβ-naphthol are reduced to amines (from R-NO to R-NH2) in a strongly alkaline environment at high temperatures. These amines further react with alkali to generate soluble organic sodium salts and ammonia. The ammonia volatilizes into the flue gas and is absorbed by water to produce ammonia water. The ammonia water is then dispersed by soaking the clinker in water, thus improving the grade of the cobalt slag. TG-MS analysis of the alkali-treated cobalt slag shows that ammonia is produced at aging temperatures of 100.6℃-147.5℃, while nitrogen oxides are only produced at 225.2℃. Therefore, within the aging temperature range used in this invention, only water and ammonia appear in the flue gas. Preparing ammonia water by absorbing an appropriate amount of water is feasible. The low-temperature aging process is easier to implement in production and therefore has high value for industrial application. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the TG / DSC thermal analysis spectrum of the sample;

[0014] Figure 2 Schematic diagram of MS thermal analysis spectrum of sample 1;

[0015] Figure 3 Schematic diagram of MS thermal analysis spectrum of sample 2;

[0016] Figure 4 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0017] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0018] The method for improving the grade of β-naphthol cobalt slag by alkali addition and low-temperature aging according to the present invention includes alkali addition and low-temperature aging, water leaching, and post-treatment steps:

[0019] A. Low-temperature alkali curing method:

[0020] 1) Add alkali to cobalt slag and mix well to obtain material a;

[0021] 2) Add water to material a in a volume of 2 to 4 times the solid-liquid volume of material a and mix them into a slurry. Then, mature the mixture at a temperature of 110 to 160°C to obtain material b and flue gas c. Flue gas c is absorbed by water.

[0022] B. Water immersion:

[0023] 1) After cooling material b, water is added to slurry to obtain material d;

[0024] 2) Add water to material d at a volume of 3 to 12 times that of material d (solid-liquid ratio), and soak in water at a temperature of 30 to 80°C to obtain material e;

[0025] C. Post-processing: Material e is filtered to obtain filtrate f and filter residue g. Filter residue g is washed with hot water 2-4 times. Filtrate f is the enriched liquid; filter residue g is the enriched cobalt residue.

[0026] The mass ratio of cobalt slag to alkali is 1:(0.5~1.5).

[0027] The mass ratio of cobalt slag to alkali is 1:(0.75~1.0).

[0028] The mass ratio of cobalt slag to alkali is 1:0.75.

[0029] The mixing process involves adding sodium hydroxide of the specified formula to the cobalt slag, adding an appropriate amount of water, stirring until well mixed, and then performing low-temperature curing.

[0030] The ripening temperature is 150°C.

[0031] The water immersion temperature is 30~80℃.

[0032] The water immersion temperature is 80℃.

[0033] The immersion time is 3-5 hours.

[0034] The immersion time was 4 hours.

[0035] The invention will be further illustrated below with specific implementation examples:

[0036] Example 1

[0037] The α-nitroso-β-naphthol cobalt slag is produced by precipitating cobalt in the cadmium-poor cadmium recovery solution of a zinc smelter using the α-nitroso-β-naphthol method. After acid washing, its main components are: 63.77% water and 8.71% Co.

[0038] 1. Low-temperature alkaline ripening and water immersion test

[0039] (1) Effect of alkali dosage on the aging and water leaching of naphthol cobalt slag

[0040] Maturation conditions: 30g dry cobalt slag (81.94g wet slag), cobalt slag: NaOH ratio of 1:1.5, 1:1, 1:0.75, 1:0.5, NaOH dosage of 45g, 30g, 22.5g, 15g, add appropriate amount of water (about 30mL) to fully mix the alkali with the cobalt slag and put it directly into a muffle furnace to heat to 150℃ and keep it at that temperature for 2h. After the time is up, take it out directly, cool it, and then add water to slurry it.

[0041] Water immersion conditions: liquid-to-solid ratio 10:1, temperature 80℃, time 4h. The filter residue was washed with hot water 3 times. The test results are shown in Table 1.

[0042] Table 1 Alkali Dosage Test

[0043]

[0044] Note: GJ-23 was directly cured at 150℃ for 2 hours, and the clinker was leached with 100g / L NaOH at a liquid-to-solid ratio of 10:1 for 4 hours.

[0045] The experimental results on the effect of alkali dosage on cobalt slag aging and water leaching show that at this temperature, when the alkali dosage reaches 1:0.75, the grade deviation of the cobalt slag is relatively small, all reaching more than 24%. When the alkali dosage is less than 1:0.5, the effect is poor. In addition, the liquid-solid ratio during water leaching may also have a certain impact. The more suitable alkali dosage is a mass ratio of cobalt slag to alkali of 1:0.75.

[0046] (2) Effect of aging temperature on the aging and water leaching of cobalt naphthol residue

[0047] Maturation conditions: 30g dry cobalt slag (81.94g wet slag), cobalt slag: NaOH ratio of 1:0.75, NaOH dosage of 22.5g, add appropriate amount of water (about 30mL) to fully mix the alkali with the cobalt slag, then put it directly into a muffle furnace and heat it to the set temperature and keep it at that temperature for 2 hours. Maturation temperatures are 150, 130, and 110℃. After the time is up, take it out directly, cool it, and then add water to slurry it.

[0048] Water immersion conditions: liquid-to-solid ratio 10:1, temperature 80℃, time 4h, filter residue washed with hot water 3 times, the test results are shown in Table 2.

[0049] Table 2. Curing Temperature Test

[0050]

[0051] The experimental results on the effect of aging temperature on cobalt slag aging and water immersion show that within this temperature range, the grade of cobalt slag increases with the increase of aging temperature, while the effect is poor at lower temperatures. Under the current conditions, the suitable aging temperature is 150℃.

[0052] (3) NaOH substitution test

[0053] In the experiment, the amount of NaOH used was 0.75 times that of the cobalt slag, which was relatively large and the cobalt concentration in the leachate was relatively high. Therefore, it was considered to use sodium sulfite or sodium carbonate to replace part of the sodium hydroxide and to investigate the grade of the cobalt slag and the loss of cobalt in the solution.

[0054] Sodium carbonate substitution test conditions: 81.94g wet cobalt slag (equivalent to 30g dry slag), 15g NaOH, 15g sodium carbonate, 30mL water were added and thoroughly mixed. The aging temperature was 150℃ for 2h, the leaching temperature of the slag was 85℃, the liquid-to-solid ratio was 10:1, and the leaching time was 4h. The slag was analyzed for cobalt and zinc, and the liquid was analyzed for cobalt. The test results are shown in Table 3.105.

[0055] Sodium sulfite substitution test conditions: 81.94g wet cobalt slag (equivalent to 30g dry slag), 15g, 7.5g, and 0.0g NaOH, 15g, 22.5g, and 30.0g sodium sulfite, added to 30mL of water and mixed thoroughly. The aging temperature was 150℃ for 2h, the leaching temperature of the slag was 85℃, the liquid-to-solid ratio was 10:1, and the leaching time was 4h. The slag was analyzed for cobalt and zinc, and the liquid was analyzed for cobalt. The test results are shown in Table 3.105.

[0056] The experimental conditions for the combined substitution of sodium carbonate and sodium sulfite were as follows: 81.94 g of wet cobalt slag (equivalent to 30 g of dry slag), 15 g of NaOH, 5 g of sodium carbonate, and 10 g of sodium sulfite, or 15 g of NaOH, 10 g of sodium carbonate, and 5 g of sodium sulfite were mixed with 30 mL of water. The aging temperature was 150℃ for 2 h, the leaching temperature of the slag was 87℃, the liquid-to-solid ratio was 10:1, and the leaching time was 4 h. The slag was analyzed for cobalt and zinc, and the liquid was analyzed for cobalt. The experimental results are shown in Table 3.

[0057] Table 3 Results of the NaOH substitution experiment

[0058]

[0059] A portion of the leaching residue from GJ-26 was separated and leached with 150 g / L sulfuric acid at a liquid-to-solid ratio of 10:1. The resulting leachate had a Co content of 0.40 g / L, while the residue had a Co content of 8.18%, indicating that sodium sulfite alone cannot improve the cobalt residue grade. Adding sodium sulfite to sodium hydroxide can increase the cobalt grade of the leaching residue to over 30% and reduce the cobalt concentration in the leachate. Adding sodium carbonate can reduce the cobalt concentration in the leachate to some extent, but the cobalt residue grade is similar to that achieved with only alkali. Simultaneous addition of sodium carbonate and sodium sulfite can reduce the amount of alkali used while still achieving the effects of improving the cobalt grade of the leaching residue and reducing the cobalt concentration in the leachate.

[0060] (4) Prepare slag under optimal conditions and investigate its composition.

[0061] The requirements for the main components and impurities of different grades of cobalt concentrate in standard YS / T301-2007 are shown in Table 4.

[0062] Table 4 Standards for Different Types of Cobalt Concentrate

[0063]

[0064] By comparing the standard cobalt concentrate and the composition of the cobalt slag produced in the experiment, we analyzed the feasibility of treating it as cobalt concentrate.

[0065] The curing test conditions were as follows: 163.88 g of wet cobalt slag, the ratio of cobalt slag to NaOH was 1:0.75, the amount of NaOH used was 45 g, and an appropriate amount of water (about 60 mL) was added. After the alkali and cobalt slag were thoroughly mixed, the mixture was directly placed in a muffle furnace and kept at 150 °C for 2 h. After the time was up, the mixture was taken out and cooled, and then water was added for slurrying.

[0066] Water immersion conditions: liquid-to-solid ratio 10:1, temperature 87℃, time 4h. The filter residue was washed with hot water 3 times. The test results are shown in Table 5. The analysis results of cobalt concentrate standard are shown in Table 6.

[0067] Table 5 Results of the comprehensive test under the conditions of aging and immersion in water

[0068]

[0069] Table 6. Analysis results compared with cobalt concentrate standards.

[0070]

[0071] The components of samples GJ-27 and 28 were analyzed against the cobalt concentrate standard, and the results are shown in Table 7.

[0072] Table 7. Analysis results of samples GJ-27 and 28 compared with cobalt concentrate standards.

[0073]

[0074] Comparing the standards for cobalt slag and cobalt concentrate, it can be seen that the Hg content in the cobalt slag is higher, but the leaching solution of the purified slag does not contain Hg. This may be due to the auxiliary materials used or analytical deviations. The remaining impurities are all lower than the required values ​​for cobalt concentrate. The cobalt slag produced by replacing part of the alkali with sodium carbonate and sodium sulfite has a higher grade, all impurities meet the requirements, and the cobalt loss during the leaching process is low.

[0075] (5) Gas composition analysis during low-temperature alkaline ripening process

[0076] To investigate the gases produced during the alkali-addition maturation of cobalt slag, thermogravimetric-mass spectrometry (TGA-MS) was performed on the slurry after alkali and water addition. The heating rate was 5℃ / min, the temperature range was room temperature to 500℃, and the medium was air. The analytical results are as follows: Figure 1 .

[0077] The TG and DSC thermal analysis results of the sample are as follows: Figure 1 As shown, the MS thermal analysis results are as follows: Figure 2 , Figure 3 As shown.

[0078] The DSC (Differential Scanning Calorimetry) curve shows a weak exothermic peak in the temperature range of 90.4℃-118.4℃, with a peak temperature of 105.1℃, indicating that the sample underwent an oxidation reaction and released gas. Multiple consecutive exothermic peaks appear in the temperature range of 176.4℃-266.0℃, with peak temperatures of 201.8℃, 231.0℃, and 249.0℃, respectively, indicating that the sample underwent an oxidation reaction and released gas. A continuous double exothermic reaction occurs in the temperature range of 313.5℃-443.0℃, with peak temperatures of 331.6℃ and 399.7℃, respectively. The exothermic peak at 399.7℃ is stronger, indicating that the sample underwent an oxidation reaction and released gas.

[0079] The thermogravimetric (TG) curve shows a weight loss of 9.49% in the 40.0℃-90.4℃ temperature range, 13.37% in the 90.4℃-118.4℃ temperature range, 6.66% in the 118.4℃-176.4℃ temperature range, a weight gain of 1.55% in the 176.4℃-266.0℃ temperature range, a weight loss of 1.82% in the 266.0℃-313.5℃ temperature range, a weight loss of 2.19% in the 313.5℃-343.5℃ temperature range, a weight loss of 10.97% in the 343.5℃-443.0℃ temperature range, and a weight loss of 0.53% in the 443.0℃-500.0℃ temperature range, for a total weight loss of 43.48%.

[0080] MS (mass spectrometry) was used to detect NH3 (curve 2), H2O (curve 3), CO (curve 4), NO (curve 5), H2S (curve 6), CO2 (curve 7), NO2 (curve 8), SO2 (curve 9), C6H6 (curve 10), SO3 (curve 11), C6H5OH (curve 12), and C. 10 Thirteen gases, including H8O (curve 13) and nitrosonaphthol (curve 14).

[0081] CO (curve 4), H2S (curve 6), SO2 (curve 9), C6H6 (curve 10), SO3 (curve 11), C6H5OH (curve 12), C 10 H8O (curve 13) and nitrosonaphthol (curve 14) showed no significant volatilization.

[0082] NH3 (curve 2) volatilizes in the temperature range of 100.6℃-147.5℃, with a volatilization peak of 116.4℃;

[0083] H2O (curve 3) volatilizes in the temperature range of 100.6℃-147.5℃, with a volatilization peak of 116.4℃;

[0084] NO (curve 5) volatilizes in the temperature range of 225.2℃-266.0℃, with volatilization peaks at 236.0℃ and 254.8℃, and a small amount of volatilization near 330.9℃ and 406.9℃;

[0085] CO2 (curve 7) volatilizes in the temperature range of 225.2℃-266.0℃, with volatilization peaks at 235.2℃ and 256.2℃; and volatilizes in the temperature range of 313.5℃-443.0℃, with volatilization peaks at 334.1℃ and 401.2℃.

[0086] NO2 (curve 8) volatilizes in the temperature range of 244.6℃-266.0℃, with a volatilization peak of 254.8℃, and volatilizes in the temperature range of 313.5℃-443.0℃, with volatilization peaks of 334.1℃ and 402.7℃.

[0087] The TG / DSC-MS analysis results show that only water and NH3 were detected at aging temperatures below 200℃. This explains why some cobalt ions are still present in the solution under strongly alkaline conditions, and also verifies that it is possible for ammonia to be generated during alkaline leaching of cobalt slag. In addition, temperatures above 220℃ may cause organic matter to decompose and release nitrogen oxides and carbon oxides. The leaching temperature of cobalt slag can reach 150℃ to leach organic matter from the cobalt slag and improve the grade of cobalt slag. The ammonia generated during the aging process needs to be absorbed by water or acid. The volatilization of ammonia can reduce the entry of nitrogen-containing compounds into the zinc sulfate solution.

Claims

1. A method for improving the grade of β-naphthol cobalt slag through low-temperature alkali curing, characterized in that, This includes steps such as low-temperature alkali curing, water soaking, and post-treatment: A. Low-temperature alkali curing method: 1) Add alkali to cobalt slag and mix well to obtain material a; 2) Add 2 to 4 times the volume of water to material a and stir well. Then, mature the mixture at 110 to 160°C for 1 to 4 hours to obtain material b and flue gas c. Use water to absorb the flue gas c to prepare ammonia water. B. Water immersion: 1) After cooling material b, water is added to slurry to obtain material d; 2) Add 3 to 12 times the volume of water to material d, and soak in water at 30 to 80°C for 2 to 6 hours to obtain material e; C. Post-processing: Material e is filtered to obtain filtrate f and filter residue g. Filter residue g is washed with hot water 2-4 times. Filtrate f is the enriched liquid and sent for water treatment. Filter residue g is the enriched cobalt residue.

2. The method for improving the grade of β-naphthol cobalt slag by low-temperature alkali curing according to claim 1, characterized in that, The alkali is NaOH; or NaOH and Na2CO3; or NaOH and Na2SO3; or any one of NaOH, Na2CO3 and Na2SO3; the mass ratio of the cobalt slag to the alkali is 1:(0.25~1.5).

3. The method for improving the grade of β-naphthol cobalt slag by low-temperature alkali curing according to claim 2, characterized in that, The mass ratio of cobalt slag to alkali is 1:(0.75~1.0).

4. The method for improving the grade of β-naphthol cobalt slag by low-temperature alkali curing according to claim 1, characterized in that, The water immersion temperature is 50~80℃.

5. The method for improving the grade of β-naphthol cobalt slag by low-temperature alkali curing according to claim 1, characterized in that, The immersion time is 3-5 hours.

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