Method for strengthening desulfurization and improving metal recovery rate through mechanical-oxidative activation of electrolytic manganese residues

Abstract

The invention discloses a method for strengthening desulfurization and improving the metal recovery rate through mechanical-oxidation activation of electrolytic manganese residues. The method comprises the three steps of mechanical activation, oxidation degree regulation and activation and desulfurization leaching. Desulfurization leaching of the electrolytic manganese residues activated through the method has the following advantages that the electrolytic manganese residues are mechanically activated to damage a calcium sulfate salt layer wrapping the outer layer, so that more desulfurization active phases are exposed, and meanwhile crystal form transformation of the electrolytic manganese residues is promoted; under the condition that an active area is exposed, a proper amount of low-valence Mn is converted into a high-valence Mn through oxidation activation, and the manganese oxidation degree (the proportion of MnO2 / Mn < 2 + >) in the electrolytic manganese residues is regulated and controlled; the desulfurization efficiency can be improved, the leaching efficiency of the metal Mn can be remarkably improved, and efficient recovery of valuable metal resources is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of wet desulfurization and solid waste resource utilization, and specifically relates to a method for activating electrolytic manganese slag to strengthen desulfurization and improve metal recovery rate. Background Art

[0002] Electrolytic manganese slag is a near-neutral waste slag produced after manganese ore is leached with sulfuric acid, purified, and filtered. With the continuous increase in manganese resource consumption, the grade of manganese ore continues to decline. For every ton of electrolytic manganese product produced, 10 to 12 tons of electrolytic manganese slag will be produced. At present, most electrolytic manganese enterprises in my country adopt the method of slag storage for electrolytic manganese slag. Electrolytic manganese slag contains soluble manganese ions, sulfates and a small amount of heavy metal ions, which can easily infiltrate into the surrounding water and soil with surface runoff, affecting groundwater, polluting the environment, and endangering the survival and health of residents. Faced with the dual pressures of environmental protection and resource scarcity, achieving harmless and resource-based treatment of electrolytic manganese slag plays an important role in the sustainable development of the manganese industry.

[0003] The main components of electrolytic manganese slag are calcium sulfate, silicon dioxide, manganese dioxide and manganese sulfate. It also contains a variety of valuable metals. Direct storage and disposal causes waste of resources and environmental pollution. The total manganese content in electrolytic manganese slag is about 4%. It is easily oxidized when exposed to air for a long time, making it difficult for some manganese to be leached out by water. At present, there are studies on improving the leaching rate of manganese in electrolytic manganese slag under the conditions of acid leaching, ultrasound, auxiliary agents, etc., but the leaching rate is not high, the operating conditions are harsh, the process is complicated, and the recovery cost is high.

[0004] Sulfur dioxide (SO2) is the main atmospheric pollutant in smelting flue gas and the main precursor of acid rain and photochemical haze, which has posed a serious threat to the ecosystem and human health. Therefore, it is necessary to absorb SO2 from flue gas and reduce its emissions. As we all know, wet limestone flue gas desulfurization technology is widely used in desulfurization, but the process occupies a large area, has high operating costs, and has high byproducts CO2 and gypsum production, making it difficult to achieve resource recycling. As a typical reducing agent, SO2 reacts with FeO, Fe2O3 and MnO2 to generate FeSO4 and MnSO4, thereby achieving desulfurization and leaching of valuable metals. The slurry flue gas desulfurization technology is used to deeply couple the flue gas desulfurization process with the mineral sulfuric acid leaching process, use mineral raw materials and solid waste to prepare slurry to replace desulfurizers, and SO2 in flue gas to replace sulfuric acid, so as to achieve the purpose of "waste treatment" and "resource recycling". Summary of the invention

[0005] The present invention discloses a method for mechanically-oxidatively activating electrolytic manganese slag to enhance desulfurization and improve metal recovery rate, and the method comprises three steps of pretreatment, mechanical activation and oxidation degree regulation activation. The electrolytic manganese slag activated by the method has the following advantages in desulfurization leaching: mechanically activating the electrolytic manganese slag destroys the calcium sulfate salt layer wrapped in the outer layer, so that the desulfurization active phase is more exposed and its crystal transformation is promoted; under the condition of active area exposure, through oxidation activation, a proper amount of low-valent Mn is transformed into a high-valent state, and the manganese oxidation degree (MnO2 / Mn 2+ ratio); it can not only improve the desulfurization efficiency, but also effectively improve the leaching efficiency of metal Mn and realize the recovery of valuable metal resources.

[0006] A method for mechanically-oxidatively activating electrolytic manganese slag to enhance desulfurization and improve metal recovery, the method comprising the following steps:

[0007] 1) Mechanical activation: electrolytic manganese slag is dried at low temperature, crushed and put into a ball mill, a certain amount of dispersant is added, and the ball milling parameters are adjusted for mixed ball milling;

[0008] 2) Oxidation degree control activation: The electrolytic manganese slag after ball milling is placed in a tube furnace under certain oxidation conditions to obtain the manganese oxidation degree (MnO2 / Mn 2+ The proportion of) suitable electrolytic manganese slag;

[0009] 3) Desulfurization leaching: The electrolytic manganese slag obtained in step (2) is mixed with water to form a desulfurization slurry, the pH of the solution is adjusted, a bubbling reactor is constructed using a three-necked flask, and the reactor is placed in a heat-collecting magnetic stirrer. In this device, a desulfurization leaching reaction is carried out by introducing simulated process flue gas.

[0010] In the above method, the ball-to-material ratio in step (1) is 1:1, 2:1, 5:1, 8:1, or 10:1.

[0011] In step (1), the dispersant is one of polyvinylidene fluoride, anhydrous ethanol, stearic acid and polyacrylic acid, and the amount of the ball milling dispersant is 1-2 ml.

[0012] The ball milling speed in step (1) is 50 rpm, 100 rpm, 150 rpm, 200 rpm, and 250 rpm.

[0013] The ball milling time in step (1) is 20 min, 30 min, 40 min, 50 min, and 60 min.

[0014] The oxidation temperature in step (2) is 150°C, 200°C, 300°C, and 400°C.

[0015] In step (2), the oxidizing atmosphere is one of oxygen and air.

[0016] The oxidation time in step (2) is 60 min, 90 min, 120 min, and 150 min.

[0017] The solid-liquid ratio in step (3) is 1:1 (g / L), 3:1 (g / L), and 5:1 (g / L).

[0018] In step (3), the pH value is adjusted to 8-9 with 1-2 mol / L NaOH.

[0019] In step (3), the reaction temperature of the bubbling reactor is 20-80° C., and the reaction time is 60-150 min.

[0020] In step (3), the SO2 concentration is 2000-8000 mg / m 3 .

[0021] The main chemical reactions involved in the present invention are as follows:

[0022] SO2+H2O→SO2·H2O→H2SO3

[0023] MnO2+SO2·H2O→MnSO4+H2O

[0024]

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The raw materials used in the present invention are abundant in resources and low in price, and the activation process is simple and easy.

[0027] 2. Mechanical activation of electrolytic manganese slag destroys the outer layer of calcium sulfate salt, exposing more desulfurization active phase and promoting its crystal transformation.

[0028] 3. Under the condition of active area exposure, through oxidation activation, the appropriate amount of low-valent Mn is transformed into high-valent state, and the manganese oxidation degree (MnO2 / Mn 2+ ratio), which can not only improve the desulfurization efficiency, but also effectively improve the leaching efficiency of metal Mn.

[0029] 4. Desulfurization leaching by activating electrolytic manganese slag has high desulfurization efficiency and metal recovery rate, achieving the dual goals of waste treatment and resource reuse.

[0030] 5. The process flow of the present invention is concise and clear, highly operable, and suitable for large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Desulfurization performance diagram of materials before and after activation

[0032] Figure 2Metal leaching performance diagram before and after material activation

[0033] Figure 3 BET test diagram before and after material activation

[0034] Figure 4 XRD test diagram of the material before and after activation DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to specific embodiments, but is not intended to limit the scope of the present invention.

[0036] Example 1

[0037] The steps of preparing the mechanical-oxidation activated electrolytic manganese slag into slurry for wet desulfurization are as follows:

[0038] 1) The electrolytic manganese slag is placed in a 100°C oven and dried for 12 hours, and then the blocky electrolytic manganese slag is crushed.

[0039] 2) 5 g of crushed electrolytic manganese slag, 25 g of agate balls and 2 ml of dispersant were put into a ball mill and milled at a speed of 150 rpm for 30 min. Finally, oxygen was introduced into a tubular furnace and calcined at 300° C. to obtain a mechanically-oxidatively activated electrolytic manganese slag.

[0040] 3) 0.1 g of the electrolytic manganese slag obtained in step (2) was mixed with 100 ml of ultrapure water to prepare a desulfurization slurry, and the initial pH was controlled to 8. A bubbling reactor was constructed using a three-necked flask and placed in a heat-collecting magnetic stirrer. In this device, a desulfurization leaching reaction was carried out by introducing simulated process flue gas, and the reaction was carried out at 40° C. for 120 minutes.

[0041] 4) The total flue gas flow rate is 300ml / min, the O2 volume fraction is 10%, and the SO2 concentration is 3000mg / m 3 To simulate process flue gas.

[0042] The results showed that the desulfurization rate was 98% and the Mn metal recovery rate was 96% after 120 minutes of mechanical-oxidation activated pulp reaction.

[0043] Example 2

[0044] The steps of preparing the electrolytic manganese slag into slurry for wet desulfurization are as follows:

[0045] 1) The electrolytic manganese slag is placed in a 100°C oven and dried for 12 hours, and then the blocky electrolytic manganese slag is crushed.

[0046] 2) 0.1 g of the electrolytic manganese slag obtained in step (1) was mixed with 100 ml of ultrapure water to prepare a desulfurization slurry, and the initial pH was controlled to 8. A bubbling reactor was constructed using a three-necked flask and placed in a heat-collecting magnetic stirrer. In this device, a desulfurization leaching reaction was carried out by introducing simulated process flue gas, and the reaction was carried out at 40° C. for 120 minutes.

[0047] 3) The total flue gas flow rate is 300ml / min, the O2 volume fraction is 10%, and the SO2 concentration is 3000mg / m 3 To simulate process flue gas.

[0048] The results showed that the desulfurization rate of the unactivated slurry was 90% and the Mn metal recovery rate was 56% after 120 minutes of reaction.

[0049] Example 3

[0050] The steps of preparing the oxidatively activated electrolytic manganese slag into slurry for wet desulfurization are as follows:

[0051] 1) The electrolytic manganese slag is placed in a 100°C oven and dried for 12 hours, and then the blocky electrolytic manganese slag is crushed.

[0052] 2) Take 5 g of crushed electrolytic manganese slag, introduce oxygen into a tubular furnace and calcine at 300° C. to obtain oxidatively activated electrolytic manganese slag.

[0053] 3) 0.1 g of the electrolytic manganese slag obtained in step (2) was mixed with 100 ml of ultrapure water to prepare a desulfurization slurry, and the initial pH was controlled to 8. A bubbling reactor was constructed using a three-necked flask and placed in a heat-collecting magnetic stirrer. In this device, a desulfurization leaching reaction was carried out by introducing simulated process flue gas, and the reaction was carried out at 40° C. for 120 minutes.

[0054] 4) The total flue gas flow rate is 300ml / min, the O2 volume fraction is 10%, and the SO2 concentration is 3000mg / m 3 To simulate process flue gas.

[0055] The results showed that the desulfurization rate was 92% and the Mn metal recovery rate was 86% after the oxidation activation pulp reaction for 120 minutes.

[0056] Example 4

[0057] The steps of preparing the mechanically activated electrolytic manganese slag into slurry for wet desulfurization are as follows:

[0058] 1) The electrolytic manganese slag is placed in a 100°C oven and dried for 12 hours, and then the blocky electrolytic manganese slag is crushed.

[0059] 2) 5 g of crushed electrolytic manganese slag, 25 g of agate balls and 2 ml of dispersant were put into a ball mill and ball milled at a speed of 150 rpm for 30 min to obtain mechanically activated electrolytic manganese slag.

[0060] 3) 0.1 g of the electrolytic manganese slag obtained in step (2) was mixed with 100 ml of ultrapure water to prepare a desulfurization slurry, and the initial pH was controlled to 8. A bubbling reactor was constructed using a three-necked flask and placed in a heat-collecting magnetic stirrer. In this device, a desulfurization leaching reaction was carried out by introducing simulated process flue gas, and the reaction was carried out at 40° C. for 120 minutes.

[0061] 4) The total flue gas flow rate is 300ml / min, the O2 volume fraction is 10%, and the SO2 concentration is 3000mg / m 3 To simulate process flue gas.

[0062] The results showed that the desulfurization rate was 90% and the Mn metal recovery rate was 89% after the mechanically activated pulp reaction for 120 minutes.

Claims

1. A method for mechanical-oxidative activation of electrolytic manganese slag to enhance desulfurization and improve metal recovery, characterized in that The following steps are involved: 1) Mechanical activation: electrolytic manganese slag is dried at low temperature, crushed and put into a ball mill, a certain amount of dispersant is added, and the ball milling parameters are adjusted for mixed ball milling; 2) Oxidation degree control activation: The electrolytic manganese slag after ball milling is placed in a tube furnace under certain oxidation conditions to obtain the manganese oxidation degree (MnO2 / Mn 2+ The proportion of) suitable electrolytic manganese slag; 3) Desulfurization leaching: The electrolytic manganese slag obtained in step (2) is mixed with water to form a desulfurization slurry, the pH value of the solution is adjusted, a bubbling reactor is constructed using a three-necked flask, and the reactor is placed in a heat-collecting magnetic stirrer. In this device, a desulfurization leaching reaction is carried out by introducing simulated process flue gas.

2. The method of mechanical-oxidative activation of electrolytic manganese slag to enhance desulfurization and improve metal recovery according to claim 1, characterized in that The dispersant in step (1) includes polyvinylidene fluoride, anhydrous ethanol, stearic acid, and polyacrylic acid solution, and the concentration thereof is 0.5 to 2 mol / L.

3. The method of mechanical-oxidative activation of electrolytic manganese slag to enhance desulfurization and improve metal recovery according to claim 1, characterized in that The ball milling speed in step (1) is 50-250 rpm, the ball milling time is 20-60 min, and the ball-to-material ratio is 1:1-10:

1.

4. The method of mechanical-oxidative activation of electrolytic manganese slag to enhance desulfurization and improve metal recovery rate according to claim 1, characterized in that The specific content of the oxidation degree control activation in step (2) is: the ball milled material is placed in a tube furnace at 150-400° C. and calcined for 1-5 hours, the temperature rise rate of the tube furnace is 10-20° C. / min, one of oxygen and air is introduced during the calcination process, and the material is taken out after annealing and cooling for 2-5 hours. The electrolytic manganese slag after oxidation degree control activation has a manganese oxidation degree of 0.5-8.

5. The method of mechanically oxidizing and activating electrolytic manganese slag to enhance desulfurization and improve metal recovery rate according to claim 1, characterized in that The reaction temperature of the bubbling reactor in step (3) is 20-80° C., the reaction time is 120 min, and the stirring speed is 200-400 rpm.

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