A method for comprehensively utilizing flotation tailings and red mud

Abstract

This application relates to a method for comprehensively utilizing flotation tailings and red mud, belonging to the technical field of solid waste resource recovery. The method includes: mixing the flotation tailings and red mud to obtain a mixed material; roasting the mixed material to obtain a roasted product; separating the roasted product to obtain iron minerals and aluminosilicate slag; wherein, the flotation tailings contain FeS2. This application provides a method for the collaborative comprehensive utilization of flotation tailings and red mud, avoiding the environmental impact caused by the stacking of flotation tailings and red mud, realizing the collaborative recovery of iron minerals in flotation tailings and red mud, and the remaining aluminosilicate slag can be returned to the alumina process or used as building materials.

Description

Technical Field

[0001] This application relates to the technical field of solid waste resource recovery, and particularly relates to a method for comprehensively utilizing flotation tailings and red mud. Background Art

[0002] High-sulfur bauxite is a potentially utilizable resource for alumina production. Due to the harmful effects of sulfur on alumina production, it is usually necessary to pre-treat it to reduce the sulfur content to meet the requirements of alumina production. Flotation desulfurization is a commonly used desulfurization method for high-sulfur bauxite at present. However, while reducing the sulfur content of bauxite, flotation tailings are also produced.

[0003] Red mud is a highly alkaline industrial solid waste generated during the alumina production process, with complex components. Currently, there is no economically feasible large-scale utilization method.

[0004] Currently, there is no report on the comprehensive utilization method of flotation tailings and red mud. Summary of the Invention

[0005] This application provides a method for comprehensively utilizing flotation tailings and red mud to solve the problem of insufficient comprehensive utilization technology for flotation desulfurization tailings of bauxite and red mud.

[0006] In the first aspect, this application provides a method for comprehensively utilizing flotation tailings and red mud, and the method includes:

[0007] Mix the flotation tailings and red mud to obtain a mixed material;

[0008] Roast the mixed material to obtain a roasted product;

[0009] Separate the roasted product to obtain iron minerals and aluminosilicate slag;

[0010] Among them, the flotation tailings contain FeS2.

[0011] Further, the flotation tailings are flotation tailings of high-sulfur bauxite.

[0012] Further, the molar ratio of FeS2 and Fe2O3 in the mixed material is 1:(3 - 6).

[0013] Further, the molar ratio of FeS2 and Fe2O3 in the mixed material is 1:(4 - 5).

[0014] Further, the working parameters of the roasting include: the roasting temperature is 350 - 450 °C, the roasting time is 5 - 30 min, and the volume concentration of oxygen in the roasting atmosphere is 5% - 23%.

[0015] Further, the working parameters of the roasting include: the roasting temperature is 380 - 420 °C, the roasting time is 10 - 20 min, and the volume concentration of oxygen in the roasting atmosphere is 5% - 20%.

[0016] Further, the red mud includes at least one of sintering red mud, Bayer red mud, and combined red mud.

[0017] Further, the iron concentrate yield in the iron minerals is > 29%.

[0018] Further, based on total iron, the grade of the iron concentrate is > 54%.

[0019] Further, the specific process of separating the roasted product to obtain iron minerals and aluminosilicate slag includes:

[0020] Crush the roasted product and then perform magnetic separation to obtain iron minerals and aluminosilicate slag.

[0021] The above technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:

[0022] The embodiments of the present application provide a method for comprehensively utilizing flotation tailings and red mud. In this method, the flotation tailings containing FeS2 and red mud are directly roasted after mixing, without the need to add other chemical reagents additionally. FeS2, Fe2O3, and O2 can undergo an oxidation-reduction reaction to generate Fe3O4 and SO2. The generated Fe3O4 has enhanced magnetism, which is conducive to magnetic separation. The generated SO2 reacts with the alkaline substances (calcium minerals, sodium minerals, magnesium minerals) in the red mud, reducing the alkalinity of the red mud and reducing the emissions of SO2 in the roasting flue gas, obtaining iron minerals and aluminosilicate slag. The synergistic recovery of iron minerals in the flotation tailings and red mud is realized. The remaining aluminosilicate slag can be returned to the alumina process or used for building materials, and it has the characteristics of high comprehensive utilization rate and low cost. Description of the Drawings

[0023] The drawings here are incorporated into the specification and form a part of this specification, showing the embodiments consistent with the present application and used together with the specification to explain the principles of the present application.

[0024] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is a schematic flow chart of a method for comprehensively utilizing flotation tailings and red mud provided by the embodiments of the present application;

[0026] Figure 2 Schematic flow chart of a method for comprehensively utilizing flotation tailings and red mud provided in Embodiments 1-4 of the present application. Detailed implementation manners

[0027] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0028] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments and equipment used in the present application can be obtained through market purchase or can be prepared by existing methods.

[0029] High-sulfur bauxite is a potentially utilizable resource for alumina production. Due to the harmful effects of sulfur on alumina production, it usually needs to be pretreated to reduce the sulfur content to meet the requirements of alumina production. Flotation desulfurization is a commonly used desulfurization method for high-sulfur bauxite at present. However, while reducing the sulfur content of bauxite, flotation tailings are also generated.

[0030] Red mud is a highly alkaline industrial solid waste generated during the alumina production process, with complex components, and there is currently no economically feasible large-scale utilization method.

[0031] At present, there is no report on the comprehensive utilization method of flotation tailings and red mud.

[0032] The technical solutions provided in the embodiments of the present invention are to solve the above technical problems, and the general idea is as follows:

[0033] In a first aspect, the present application provides a method for comprehensively utilizing flotation tailings and red mud. As Figure 1 shown, the method includes:

[0034] Mix the flotation tailings and red mud to obtain a mixed material;

[0035] Roast the mixed material to obtain a roasted product;

[0036] Separate the roasted product to obtain iron minerals and aluminosilicate slag;

[0037] Among them, the flotation tailings contain FeS2.

[0038] An embodiment of the present application provides a method for comprehensively utilizing flotation tailings and red mud. In this method, the flotation tailings containing FeS2 and red mud are mixed and directly roasted. FeS2, Fe2O3, and O2 can undergo a redox reaction to generate Fe3O4 and SO2. The generated Fe3O4 has enhanced magnetism, which is beneficial for magnetic separation. The generated SO2 reacts with the alkaline substances (calcium minerals, sodium minerals, magnesium minerals) in the red mud, reducing the alkalinity of the red mud and reducing the emissions of SO2 in the roasting flue gas, obtaining iron minerals and aluminosilicate slag. The collaborative recovery of iron minerals in the flotation tailings and red mud is realized. The remaining aluminosilicate slag can be returned to the alumina process or used for building materials, and it has the characteristics of high comprehensive utilization rate and low cost.

[0039] In the present application, the reaction equation that occurs during the direct roasting process after mixing the flotation tailings containing FeS2 and red mud is as follows:

[0040]

[0041] As an implementation manner of the embodiment of the present application, the flotation tailings are high-sulfur bauxite flotation tailings.

[0042] In the present application, high-sulfur bauxite is a potentially utilizable resource for alumina production. Due to the harmful effects of sulfur on alumina production, it usually needs to be pretreated to reduce the sulfur content to meet the requirements of alumina production. Flotation desulfurization is a commonly used desulfurization method for high-sulfur bauxite at present. However, while reducing the sulfur content of bauxite, flotation tailings are also generated. The main components of the flotation tailings are pyrite and aluminosilicate minerals. Due to the low content of pyrite, it is usually directly discharged as solid waste, resulting in waste of resources. Therefore, the present application provides a method for the collaborative comprehensive utilization of high-sulfur bauxite flotation tailings and red mud, avoiding the environmental impact caused by the stacking of flotation tailings and red mud, realizing the collaborative recovery of iron minerals in the flotation tailings and red mud, and the remaining aluminosilicate slag can be returned to the alumina process or used for building materials.

[0043] As an implementation manner of the embodiment of the present application, the molar ratio of FeS2 to Fe2O3 in the mixed material is 1:(3 - 6).

[0044] By controlling the molar ratio of FeS2 / Fe2O3 in the mixed material before roasting at 1:(3 - 6) in the present application, it is beneficial for FeS2, Fe2O3, and O2 to undergo a redox reaction to generate Fe3O4 and SO2, making the reaction more complete, thereby improving the comprehensive utilization rate of the flotation tailings containing FeS2 and red mud.

[0045] In some specific embodiments, the molar ratio of FeS2 to Fe2O3 in the mixed material can be 1:3, 1:4, 1:5, 1:6, etc.

[0046] As an implementation manner of the embodiment of the present application, the molar ratio of FeS2 to Fe2O3 in the mixed material is 1:(4-5).

[0047] In some specific embodiments of the present application, the molar ratio of FeS2 to Fe2O3 in the mixed material is preferably 1:(4-5).

[0048] As an implementation manner of the embodiment of the present application, the working parameters of the roasting include: the roasting temperature is 350-450°C, the roasting time is 5-30 min, and the volume concentration of oxygen in the roasting atmosphere is 5%-23%.

[0049] In the present application, when the working parameters of the roasting are controlled to be the above parameters, it is beneficial for the redox reaction of FeS2, Fe2O3, and O2 to convert into Fe3O4 and SO2. If the volume concentration of oxygen is too high and the roasting time is too long, the further oxidation of Fe3O4 will occur, generating Fe2O3 with weak magnetism, which is not conducive to the subsequent magnetic separation of iron.

[0050] Compared with the existing conventional magnetization roasting technology, the roasting temperature of the material is greatly reduced compared with the conventional magnetization roasting temperature (500-700°C). The roasting temperature of this technology is only controlled at 350-450°C, greatly reducing energy consumption.

[0051] In some specific embodiments, the roasting temperature can be 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, etc.; the roasting time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, etc.; the volume concentration of oxygen in the roasting atmosphere can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, etc.

[0052] As an implementation manner of the embodiment of the present application, the working parameters of the roasting include: the roasting temperature is 380-420°C, the roasting time is 10-20 min, and the volume concentration of oxygen in the roasting atmosphere is 5%-20%.

[0053] As an implementation manner of the embodiment of the present application, the red mud includes at least one of sintering red mud, Bayer red mud, and combined red mud.

[0054] Red mud is mainly classified into Bayer red mud and sintering red mud according to different production processes of alumina. The main chemical components contained in red mud are similar, mainly SiO2, Al2O3, CaO, Fe2O3, TiO2, Na2O, K2O, MgO, but the contents of various components are slightly different. In addition, the combined-process red mud refers to the red mud produced by the combined use of the Bayer process and the sintering process.

[0055] As an implementation manner of an embodiment of the present application, the iron concentrate yield in the iron mineral is > 29%.

[0056] As an implementation manner of an embodiment of the present application, based on total iron, the grade of the iron concentrate is > 54%.

[0057] The method for comprehensively utilizing flotation tailings and red mud provided by the present application has a high iron concentrate yield and good grade.

[0058] The following further elaborates the present application in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods without specific conditions indicated in the following embodiments are generally determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0059] The composition analysis results of the high-sulfur bauxite flotation tailings used in the following embodiments and comparative examples of the present application are shown in Table 1, and the flow schematic diagrams of the methods for comprehensively utilizing flotation tailings and red mud provided in Embodiments 1-4 are as Figure 2 shown.

[0060] Table 1 Main chemical compositions of high-sulfur bauxite flotation tailings (in oxide form)

[0061]

[0062] According to the analysis results of the high-sulfur bauxite flotation tailings in Table 1, the pyrite content in the flotation tailings is calculated to be 35.81% and the iron oxide content is 2.41% through the S and Fe2O3 contents.

[0063] The composition analysis results of the red mud used in the embodiments of the present application are shown in Table 2.

[0064] Table 2 Main chemical compositions of red mud (in oxide form)

[0065]

[0066] Mix the flotation tailings of high-sulfur bauxite and red mud evenly in proportion, control the molar ratio of FeS₂ / Fe₂O₃ in the mixed materials to be 1:3, the weights of the flotation tailings of high-sulfur bauxite and red mud are 50 g and 750 g respectively, with a total weight of 800 g. Roast at 450 °C for 5 min, and the volume concentration of oxygen in the roasting atmosphere is 20%. After roasting, the materials are ground and crushed and then subjected to high-gradient magnetic separation under a magnetic field intensity of 1.5 T. The yield of iron concentrate is 29.14%, and the grade of iron concentrate (calculated by total iron TFe) is 54.82%.

[0067] Example 2

[0068] Mix the flotation tailings of high-sulfur bauxite and red mud evenly in proportion, control the molar ratio of FeS₂ / Fe₂O₃ in the mixed materials to be 1:4, the weights of the flotation tailings of high-sulfur bauxite and red mud are 38 g and 762 g respectively, with a total weight of 800 g. Roast at 400 °C for 20 min, and the volume concentration of oxygen in the roasting atmosphere is 10%. After roasting, the materials are ground and crushed and then subjected to high-gradient magnetic separation under a magnetic field intensity of 1.5 T. The yield of iron concentrate is 35.61%, and the grade of iron concentrate (calculated by total iron TFe) is 56.79%.

[0069] Example 3

[0070] Mix the flotation tailings of high-sulfur bauxite and red mud evenly in proportion, control the molar ratio of FeS₂ / Fe₂O₃ in the mixed materials to be 1:5, the weights of the flotation tailings of high-sulfur bauxite and red mud are 30 g and 770 g respectively, with a total weight of 800 g. Roast at 350 °C for 30 min, and the volume concentration of oxygen in the roasting atmosphere is 5%. After roasting, the materials are ground and crushed and then subjected to high-gradient magnetic separation under a magnetic field intensity of 1.5 T. The yield of iron concentrate is 31.25%, and the grade of iron concentrate (calculated by total iron TFe) is 56.85%.

[0071] Example 4

[0072] Mix the flotation tailings of high-sulfur bauxite and red mud evenly in proportion, control the molar ratio of FeS₂ / Fe₂O₃ in the mixed materials to be 1:6, the weights of the flotation tailings of high-sulfur bauxite and red mud are 26 g and 774 g respectively, with a total weight of 800 g. Roast at 400 °C for 15 min, and the volume concentration of oxygen in the roasting atmosphere is 20%. After roasting, the materials are ground and crushed and then subjected to high-gradient magnetic separation under a magnetic field intensity of 1.5 T. The yield of iron concentrate is 30.38%, and the grade of iron concentrate (calculated by total iron TFe) is 55.64%.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 2 is that after the flotation tailings of high-sulfur bauxite and red mud are mixed in proportion, magnetic separation is carried out directly without roasting.

[0075] Mix the flotation tailings of high-sulfur bauxite and red mud evenly in proportion, control the molar ratio of FeS₂ / Fe₂O₃ in the mixed material to be 1:4, the weights of the flotation tailings of high-sulfur bauxite and red mud are 38 g and 762 g respectively, with a total weight of 800 g. After mixing evenly, the material is subjected to high-gradient magnetic separation under a magnetic field intensity of 1.5 T. The yield of iron concentrate is 3.26%, and the grade of iron concentrate (calculated as total iron TFe) is 25.51%.

[0076] As can be seen from Comparative Example 1, when the flotation tailings of high-sulfur bauxite and red mud are directly mixed and directly subjected to magnetic separation without roasting, since the iron minerals are not magnetically transformed, the yield of the magnetically separated iron concentrate is very small, and the grade of the iron concentrate is also very low, and the separation performance is poor.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 2 is that after the flotation tailings of high-sulfur bauxite and red mud are mixed in proportion, the roasting temperature exceeds 450 °C.

[0079] Mix the flotation tailings of high-sulfur bauxite and red mud evenly in proportion, control the molar ratio of FeS₂ / Fe₂O₃ in the mixed material to be 1:4, the weights of the flotation tailings of high-sulfur bauxite and red mud are 38 g and 762 g respectively, with a total weight of 800 g. Roast at 500 °C for 20 min, the volume concentration of oxygen in the roasting atmosphere is 20%. After mixing evenly, the material is subjected to high-gradient magnetic separation under a magnetic field intensity of 1.5 T. The yield of iron concentrate is 5.84%, and the grade of iron concentrate (calculated as total iron TFe) is 27.45%.

[0080] As can be seen from Comparative Example 2, after the flotation tailings of high-sulfur bauxite and red mud are mixed in proportion and roasted, when the roasting temperature reaches 500 °C, the iron minerals are further oxidized and transformed into Fe₂O₃, and the separation efficiency of magnetic separation is reduced, and the iron minerals in the flotation tailings of high-sulfur bauxite and red mud cannot be effectively recovered.

[0081] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the description of the range has specifically disclosed all possible sub-ranges and single values within that range. For example, it should be considered that the description of the range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0082] In this application, unless otherwise specified, the orientation terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Additionally, in the description of the specification of this application, the terms "including", "comprising", etc. mean "including but not limited to". In this text, relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this text, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. In this text, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single item (item) or plural items (items). For example, "at least one (item) of a, b, or c", or, "at least one (item) of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0083] The above description is only the specific implementation manners of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to these embodiments shown herein, but rather will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for comprehensive utilization of flotation tailings and red mud, characterized in that, The method includes: Mixing flotation tailings and red mud to obtain a mixed material; Roasting the mixed material to obtain a roasted product; Separating the roasted product to obtain iron minerals and aluminosilicate slag; Among them, the flotation tailings are high-sulfur bauxite flotation tailings containing FeS₂; the content of pyrite in the flotation tailings is 35.81%, and the content of iron oxide is 2.41%; The working parameters of the roasting include: the roasting temperature is 350-450 °C, the roasting time is 5-30 min, and the volume concentration of oxygen in the roasting atmosphere is 5%-23%; The yield of iron concentrate in the iron minerals is >29%, and based on total iron, the grade of the iron concentrate is >54%; The molar ratio of FeS₂ to Fe₂O₃ in the mixed material is 1:(3-6); The red mud includes at least one of sintering red mud, Bayer red mud, and combined process red mud.

2. The method for comprehensive utilization of flotation tailings and red mud according to claim 1, characterized in that, The molar ratio of FeS₂ to Fe₂O₃ in the mixed material is 1:(4-5).

3. The method for comprehensive utilization of flotation tailings and red mud according to claim 1, characterized in that, The working parameters of the roasting include: the roasting temperature is 380-420 °C, the roasting time is 10-20 min, and the volume concentration of oxygen in the roasting atmosphere is 5%-20%.

4. The method for comprehensive utilization of flotation tailings and red mud according to claim 1, characterized in that, The specific process of separating the roasted product to obtain iron minerals and aluminosilicate slag includes: Crushing the roasted product and then performing magnetic separation to obtain iron minerals and aluminosilicate slag.

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