Method for deeply removing sulfur in sodium aluminate solution

Abstract

The invention belongs to the field of hydrometallurgy, and particularly relates to a deep removal method for sulfur in a sodium aluminate solution. The invention relates to a method for deeply removing sulfur in a sodium aluminate solution. The method comprises the following steps: (1) adding manganese sulfate into the sodium aluminate solution to carry out a first reaction; (2) adding copper sulfate into the solution after the first reaction to carry out a second reaction; (3) adding nano iron powder into the solution after the second reaction for adsorption; and (4) carrying out solid-liquid separation on the adsorbed solution to obtain a sodium aluminate solution and a precipitate. According to the method, the manganese sulfate and the copper sulfate are sequentially added into the sodium aluminate solution, then the nano iron powder is adopted for physical adsorption, and then solid-liquid separation is carried out, so that S < 2-> in the sodium aluminate solution is effectively removed, and the method has the technical advantages of being high in S < 2-> removal rate, low in technical cost, easy to industrialize and the like.

Description

Technical Field

[0001] The invention belongs to the field of hydrometallurgy, and in particular relates to a method for deep removal of sulfur from a sodium aluminate solution. Background Art

[0002] my country has abundant high-sulfur diaspore-type bauxite, which is mainly distributed in Chongqing Dongwan, Guangxi Dahua, Guizhou Qingzhen and Wuchuan, Yunnan Banmao, Shandong Zibo, Henan Caoyao Coal Mine and Yushan. The alumina grade in high-sulfur bauxite is generally high, with an aluminum-silicon ratio of about 7.0 and a sulfur mass fraction of about 1%. Guizhou's high-sulfur bauxite reserves are approximately 150 million tons. In the alumina production process, the main hazards of sulfur are as follows: ① Increased alkali consumption and affected red mud settling performance; sulfur-containing compounds not only react with caustic soda solution to increase alkali consumption, but also the reaction products will enter the red mud and easily adsorb A1(OH)4 - 、Na + and H2O, which reduces the sedimentation of red mud; ② Corrosion of dissolution equipment, affecting the quality of alumina. When high-sulfur minerals enter the dissolution equipment or pipelines, the sulfur dissolved in the sodium aluminate solution will exist in the form of sulfur ions of different valences and their complexes, causing corrosion to the dissolution pipelines, as well as the heat exchange tubes in the evaporator, filter screens and other equipment; S in the solution 2- The increase in concentration will promote the formation of sodium hydroxysulfoferrate and increase the stability of this substance. However, the formation of sodium hydroxysulfoferrate will aggravate corrosion. The solubility of sodium hydroxysulfoferrate decreases as the solution gradually cools, and it eventually enters the aluminum hydroxide, increasing the iron content in the alumina and causing the final product aluminum hydroxide to be impure. ③ Reduce the decomposition rate of the seeds. When the Na2SO4 content exceeds a certain level, it will cause the seed rate of the sodium aluminate solution to decrease. Most of the sulfur in bauxite exists in the form of pyrite, and is dissolved as S 2- It enters the sodium aluminate solution in the form of iron, causing the iron content in the product alumina to exceed the standard and the quality to be unqualified.

[0003] The desulfurization methods in the existing technology mainly include roasting desulfurization, flotation desulfurization, and barium salt precipitation desulfurization. 2- , zinc oxide desulfurization, hydrogen peroxide oxidation to remove sulfur 2- However, the existing technology has the following shortcomings: the cost of roasting desulfurization in the industrial production process is too high, the reagents in the flotation desulfurization production process enter the subsequent process and affect the production, the cost of adding barium salt precipitation desulfurization and zinc oxide desulfurization is high, and the hydrogen peroxide desulfurization oxidation efficiency is low, so it cannot be industrially applied.

[0004] Therefore, there is an urgent need to provide a technical solution to the above-mentioned deficiencies in the existing technology. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a2- A method for deep removal of sulfur from sodium aluminate solution has technical advantages such as high removal rate, low technical cost and easy industrial application.

[0006] In order to achieve the above-mentioned purpose, the present application provides a method for deep removal of sulfur from sodium aluminate solution using the following technical solution: A method for deep removal of sulfur from a sodium aluminate solution comprises the following steps: (1) Add manganese sulfate to the sodium aluminate solution for the first reaction; (2) Add copper sulfate to the solution after the first reaction to carry out a second reaction; (3) Adding nano-iron powder to the solution after the second reaction for adsorption; (4) The adsorbed solution is subjected to solid-liquid separation to obtain sodium aluminate solution and precipitate.

[0007] Preferably, in step (1), after adding manganese sulfate powder to the industrial sodium aluminate solution, the ratio of manganese sulfate powder to industrial sodium aluminate solution is 0.2-0.8 g / L.

[0008] Further preferably, the manganese sulfate powder and S in industrial sodium aluminate solution 2- The mass ratio is 1.5 to 2.

[0009] More preferably, the first reaction is carried out under the condition of an ultrasonic intensity of 20 to 40 kHz, a temperature of 60 to 80° C., and a reaction time of 1 to 5 minutes.

[0010] Preferably, in step (2), copper sulfate powder is added to the solution after the first reaction, and the ratio of copper sulfate powder to industrial sodium aluminate solution is 0.01 to 0.1 g / L. 2- The mass ratio is 0.2 to 0.4.

[0011] More preferably, the second reaction is carried out under the condition of an ultrasonic intensity of 20 to 40 kHz, a temperature of 60 to 80° C., and a reaction time of 5 to 10 minutes.

[0012] Preferably, in step (3), the ratio of the nano iron powder to the industrial sodium aluminate solution is 2 to 4 g / L, and the S content of the nano iron powder to the industrial sodium aluminate solution is 2 to 4 g / L. 2- The mass ratio is 10 to 20.

[0013] More preferably, the adsorption temperature is 60-80° C., and the adsorption time is 60-100 min.

[0014] Preferably, in step (4), the solid-liquid separation method is filter pressing or centrifugal separation.

[0015] Beneficial effects: (1) Divalent manganese ions (Mn 2+ ) has a strong oxidizing effect, and can produce a strong stirring and shearing effect under the action of ultrasound, so that the Mn in manganese sulfate 2+ and S in sodium aluminate solution 2- After thorough mixing, ultrasonic waves and manganese sulfate produce a synergistic desulfurization effect, achieving the technical effect of uniform distribution of reactants and enhanced mass transfer.

[0016] (2) The solubility of CuS in water at room temperature and pressure is very low, and its solubility product Ksp is 8.50×10 -45 , copper sulfate can remove trace amounts of S in sodium aluminate solution 2- The CuS is removed and the generated CuS is adsorbed by nano-iron powder.

[0017] (3) Nano-iron powder has the characteristics of fine particles and large specific surface area. The removal of sulfide by nano-iron powder is mainly through the formation of surface complexes of sulfhydryl iron oxide and iron sulfide (FeS, FeS2, FeSn) precipitated and adsorbed on the surface of nano-iron powder; in addition, nano-iron powder can adsorb copper sulfide and manganese sulfide precipitates by physical adsorption. DETAILED DESCRIPTION

[0018] The present application will be described in detail below with reference to the embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations can be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as part of one embodiment can be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention should fall within the scope of protection of the embodiments of the present invention.

[0019] Example 1 A method for deep removal of sulfur from a sodium aluminate solution comprises the following steps: (1) In 2L and S 2- 0.8 g of manganese sulfate was added to an industrial sodium aluminate solution with a concentration of 0.21 g / L, and the first reaction was carried out under an ultrasonic intensity of 30 kHz, a reaction temperature of 80° C., and a reaction time of 4 min.

[0020] (2) Add 0.1 g of copper sulfate to the solution after the first reaction, and conduct a second reaction under an ultrasonic intensity of 30 kHz, a reaction temperature of 70°C, and a reaction time of 8 min.

[0021] (3) Add 5 g of nano-iron powder to the solution after the second reaction for adsorption. The adsorption temperature is 70 °C and the adsorption time is 80 min.

[0022] (4) The adsorbed solution was subjected to solid-liquid separation to obtain sodium aluminate solution and precipitate, and the S content in the sodium aluminate solution was determined. 2- The content is 0.003g / L, S 2- The removal rate is 99.98%.

[0023] Example 2 A method for deep removal of sulfur from a sodium aluminate solution comprises the following steps: (1) In 2L and S 2- 0.9 g of manganese sulfate was added to an industrial sodium aluminate solution with a concentration of 0.23 g / L, and the first reaction was carried out under an ultrasonic intensity of 25 kHz, a reaction temperature of 85° C., and a reaction time of 5 min.

[0024] (2) Add 0.15 g of copper sulfate to the solution after the first reaction, and react under an ultrasonic intensity of 35 kHz, a reaction temperature of 80°C, and a reaction time of 7 min.

[0025] (3) After the second reaction, 6 g of nano-iron powder was added to the solution for adsorption. The adsorption temperature was 80 °C and the adsorption time was 60 min.

[0026] (4) The adsorbed solution was subjected to solid-liquid separation to obtain sodium aluminate solution and precipitate, and the S content in the sodium aluminate solution was determined. 2- The content is 0.002g / L, S 2- The removal rate is 99.13%.

[0027] Example 3 A method for deep removal of sulfur from a sodium aluminate solution comprises the following steps: (1) In 2L and S 2- 0.7 g of manganese sulfate was added to an industrial sodium aluminate solution with a concentration of 0.2 g / L, and the first reaction was carried out under an ultrasonic intensity of 35 kHz, a reaction temperature of 70° C., and a reaction time of 5 min.

[0028] (2) Add 0.09 g of copper sulfate to the solution after the first reaction, and react under an ultrasonic intensity of 35 kHz, a reaction temperature of 80°C, and a reaction time of 6 min.

[0029] (3) 8 g of nano-iron powder was added to the solution after the second reaction for adsorption. The adsorption temperature was 70 °C and the adsorption time was 80 min.

[0030] (4) The adsorbed solution was subjected to solid-liquid separation to obtain sodium aluminate solution and precipitate, and the S content in the sodium aluminate solution was determined.2- The content is 0.001g / L, S 2- The removal rate is 99.5%.

[0031] The present invention adopts manganese sulfate, copper sulfate and iron powder to treat S in sodium aluminate solution. 2- Removal of Mn in MnSO4 2+ It has a strong oxidizing effect and can produce strong stirring and shearing effects under the action of ultrasound, making Mn 2+ and S in sodium aluminate solution 2- After thorough mixing, ultrasonic waves and manganese sulfate produce a synergistic desulfurization effect, achieving the technical effect of uniform distribution of reactants and enhanced mass transfer. Since the solubility of CuS in water is very low at room temperature and pressure, its solubility product Ksp is 8.50×10 -45 , copper sulfate can remove trace amounts of S in sodium aluminate solution 2- Further removal. Nano-iron powders have the characteristics of fine particles and large specific surface area. Nano-iron powders remove the generated CuS mainly by forming surface complexes of sulfhydryl iron oxide and iron sulfide (FeS, FeS2, FeSn), which are precipitated and adsorbed on the surface of the nano-iron powder. In addition, nano-iron powders can adsorb copper sulfide and manganese sulfide precipitates through physical adsorption.

[0032] The present invention sequentially adds manganese sulfate and copper sulfate to the sodium aluminate solution, and then uses nano iron powder for physical adsorption and solid-liquid separation. The present invention effectively removes S in the sodium aluminate solution. 2- , with S 2- It has technical advantages such as high removal rate, low technical cost and easy industrialization.

[0033] Throughout the present invention, terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" mean that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0034] The foregoing description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for deep removal of sulfur in sodium aluminate solution, characterized in that: The steps include: (1) Add manganese sulfate to industrial sodium aluminate solution for the first reaction; (2) Add copper sulfate to the solution after the first reaction to carry out a second reaction; (3) Adding nano-iron powder to the solution after the second reaction for adsorption; (4) The adsorbed solution is subjected to solid-liquid separation to obtain sodium aluminate solution and precipitate.

2. The method for deep removal of sulfur in sodium aluminate solution according to claim 1, characterized in that: In step (1), after manganese sulfate powder is added to the industrial sodium aluminate solution, the ratio of manganese sulfate powder to industrial sodium aluminate solution is 0.2 to 0.8 g / L.

3. The method for deep removal of sulfur in sodium aluminate solution according to claim 2, characterized in that: The manganese sulfate powder and the S in the industrial sodium aluminate solution 2- The mass ratio is 1.5 to 2.

4. The method for deep removal of sulfur from sodium aluminate solution according to any one of claims 1 to 3, characterized in that: The first reaction is carried out under the condition of ultrasonic intensity of 20-40 kHz, the temperature of the first reaction is 60-80° C., and the reaction time is 1-5 minutes.

5. The method for deep removal of sulfur in sodium aluminate solution according to claim 1, characterized in that: In step (2), copper sulfate powder is added to the solution after the first reaction, and the ratio of copper sulfate powder to industrial sodium aluminate solution is 0.01-0.1 g / L. 2- The mass ratio is 0.2 to 0.

4.

6. The method for deep removal of sulfur in sodium aluminate solution according to claim 5, characterized in that: The second reaction is carried out under the condition of an ultrasonic intensity of 20 to 40 kHz, a temperature of 60 to 80° C., and a reaction time of 5 to 10 minutes.

7. The method for deep removal of sulfur in sodium aluminate solution according to claim 1, characterized in that: In step (3), the ratio of the nano iron powder to the industrial sodium aluminate solution is 2 to 4 g / L. 2- The mass ratio is 10 to 20.

8. The method for deep removal of sulfur in sodium aluminate solution according to claim 7, characterized in that: The adsorption temperature is 60-80°C, and the adsorption time is 60-100 minutes.

9. The method for deep removal of sulfur in sodium aluminate solution according to claim 1, characterized in that: In step (4), the solid-liquid separation method is filter pressing or centrifugal separation.