A method for decarbonization and iron removal of high-sulfur bauxite

Abstract

The present application relates to the technical field of impurity removal and quality improvement of non-ferrous metals, and in particular to a method for decarbonization and iron removal of high-sulfur bauxite; the method comprises: crushing the high-sulfur bauxite and screening it with a preset particle size to obtain fine-grained high-sulfur bauxite; wet coarse grinding the fine-grained high-sulfur bauxite to obtain a coarse-ground slurry; adjusting the pH value of the coarse-ground slurry, and then adding a flotation agent to the coarse-ground slurry for flotation to obtain a desulfurized aluminum concentrate; finely grinding the desulfurized aluminum concentrate and performing strong magnetic separation to obtain a low-carbon and low-iron aluminum concentrate and a high-carbon and high-iron tailings, respectively; the flotation agent comprises an inhibitor, an activator, a composite desulfurization collector and a frother; the preset particle size is 6 mm to 9 mm; and adopts a "stage grinding-flotation magnetic combined stage separation technology" with the characteristics of low energy consumption, low production cost, high recovery rate, strong process adaptability, stable production, and high comprehensive utilization rate.

Description

Technical Field

[0001] The present application relates to the technical field of impurity removal and quality improvement of nonferrous metals, and in particular to a method for decarbonizing and removing iron from high-sulfur bauxite. Background Art

[0002] Bauxite, the sole raw material for alumina production in the aluminum industry, is also widely used in high-temperature refractories, refractory cement, ceramic materials, and precision casting. In recent years, with the rapid development of the alumina industry and the increasing depletion of high-quality aluminum resources, domestic bauxite, which accounts for only 3% of reserves and is increasingly poor, fine, and mixed in quality, is far from meeting production needs. Consequently, the industry has gradually begun using imported bauxite to produce alumina, resulting in a yearly increase in bauxite imports. Since 2019, annual bauxite imports have exceeded 10 million tons, with a self-sufficiency rate of less than 45%. High-sulfur, high-carbon bauxite has become a significant potential resource for the aluminum industry. However, due to its complex properties and fine ore distribution, high impurity contents such as sulfur, carbon, and iron have hindered its economical and efficient development. Addressing the desulfurization, decarbonization, and iron removal of high-sulfur, high-carbon bauxite would alleviate the current resource shortage facing the industry. Therefore, technological development and utilization of high-sulfur bauxite are necessary.

[0003] At present, flotation is mostly used to desulfurize high-sulfur bauxite, which can remove a portion of organic carbon while removing the aluminum concentrate. However, there are problems such as high inorganic carbon content and high iron content in the aluminum concentrate, high grinding energy consumption and high reagent usage. Therefore, how to provide a flotation desulfurization method for high-sulfur bauxite to achieve impurity removal and quality improvement of high-sulfur bauxite while overcoming the technical problems of fine particle size of carbon-containing minerals in high-sulfur bauxite, difficulty in removing inorganic carbon, high direct grinding cost and high dissolution cost. Summary of the Invention

[0004] The present application provides a method for decarbonizing and removing iron from high-sulfur bauxite to solve the technical problems in the prior art of removing impurities and upgrading high-sulfur bauxite, such as fine particle size of carbonaceous minerals, difficulty in removing inorganic carbon, high cost of direct grinding, and high cost of dissolution.

[0005] In a first aspect, the present application provides a method for decarbonizing and removing iron from high-sulfur bauxite, the method comprising:

[0006] Crushing high-sulfur bauxite and screening it to a preset particle size to obtain fine-grained high-sulfur bauxite;

[0007] performing wet coarse grinding on the fine-grained high-sulfur bauxite to obtain coarsely ground ore pulp;

[0008] Adjusting the pH of the coarsely ground slurry, and then adding a flotation agent to the coarsely ground slurry for flotation to achieve desulfurization and organic carbon removal to obtain desulfurized aluminum concentrate;

[0009] Finely grinding the desulfurized aluminum concentrate and subjecting it to strong magnetic separation to remove iron and inorganic carbon, thereby obtaining low-carbon and low-iron aluminum concentrate and high-carbon and high-iron tailings, respectively;

[0010] Wherein, the flotation reagents include inhibitors, activators, composite desulfurization collectors and foaming agents;

[0011] The preset particle size is 6 mm to 9 mm.

[0012] Optionally, the composite desulfurization collector includes butyl xanthate and ethyl thiocyanate, and the mass ratio of the butyl xanthate to the ethyl thiocyanate is 2:1.

[0013] Optionally, the butyl xanthate includes tert-butyl xanthate and / or isobutyl xanthate.

[0014] Optionally, the ratio of the added amount of the composite desulfurization collector to the added amount of the foaming agent is 3.5:1 to 3:1.

[0015] Optionally, the coarse grinding may satisfy that the proportion of ore materials having a grinding fineness of ≤0.038 mm is 55% to 75%.

[0016] Optionally, the fine grinding satisfies the requirement that the proportion of ore materials with a grinding fineness of ≤0.038 mm is 80% to 90%.

[0017] Optionally, the number of strong magnetic separation is 2 to 3 times.

[0018] Optionally, when the number of strong magnetic separations is 3, the strong magnetic separation includes roughing, first sweeping and second sweeping;

[0019] The rough selection magnetic field strength is 0.9T to 1T; and / or,

[0020] The magnetic field strength of the first scan is 1.1T to 1.3T; and / or,

[0021] The magnetic field strength of the second scan is 1.3T to 1.5T.

[0022] Optionally, the chemical composition of the high-sulfur bauxite includes, by mass fraction:

[0023] Al2O3≥45%, Fe2O3≤22%, S:0.8%~5%, C:0.8%~4%, and the rest are unavoidable impurities.

[0024] Optionally, the crushing of high-sulfur bauxite and screening with a preset particle size to obtain fine-grained high-sulfur bauxite comprises the following steps:

[0025] Crushing high-sulfur bauxite and screening it according to a preset particle size to obtain coarse-grained high-sulfur bauxite and screening material respectively;

[0026] The coarse-grained high-sulfur bauxite is crushed to the preset particle size, and the screened material is mixed to obtain fine-grained high-sulfur bauxite.

[0027] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0028] The embodiment of the present application provides a method for decarbonizing and removing iron from high-sulfur bauxite. Compared with the traditional method for desulfurizing and decarbonizing high-sulfur bauxite, the method screens the high-sulfur bauxite into a fine-grained grade according to a preset particle size, and then wet-grinds the fine-grained high-sulfur bauxite. The high-sulfur bauxite is further refined by coarse grinding, and the monomer separation of useful aluminum-containing minerals and sulfur-containing mineral pyrite in the fine-grained high-sulfur bauxite is achieved. The pH value of the coarse-grinded slurry is adjusted, and flotation agents are added for flotation, thereby effectively removing sulfur and organic carbon from the high-sulfur bauxite. The desulfurized aluminum concentrate is then finely ground, and strong Magnetic separation is used to separate useful aluminum minerals from inorganic carbon-containing siderite and iron-containing hematite and limonite in the desulfurized aluminum concentrate, thereby removing inorganic carbon and iron to obtain low-carbon and low-iron aluminum concentrate. Therefore, the "stage separation technology of stage grinding-flotation magnetic combination" is adopted, which not only realizes the removal of impurities and quality improvement of high-sulfur bauxite, but also overcomes the problems of fine particle size of carbon-containing minerals in high-sulfur bauxite, difficulty in removing inorganic carbon, high cost of direct grinding, and high cost of dissolution. It has the characteristics of low energy consumption, low production cost, high recovery rate, strong process adaptability, stable production, and high comprehensive utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A schematic flow chart of a method for decarbonizing and removing iron from high-sulfur bauxite provided in an embodiment of the present application;

[0032] Figure 2 A detailed flow chart of a method for decarbonizing and removing iron from high-sulfur bauxite provided in an embodiment of the present application;

[0033] Figure 3 A schematic diagram of the actual operation process of a method for decarbonizing and removing iron from high-sulfur bauxite provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0035] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0036] The creative thinking of this application is:

[0037] High-sulfur and high-carbon bauxite has become an important potential resource for the aluminum industry. Due to its complex properties and fine ore distribution, high-sulfur bauxite has a high content of impurities such as sulfur, carbon, and iron. Since the main sulfur-containing mineral in this type of bauxite is pyrite, and pyrite will gradually oxidize into various forms of sulfur during alumina production, the combined effect of various forms of sulfur not only increases alkali consumption, increases the iron content in alumina products, and deteriorates product quality, which brings many difficulties and hazards to alumina production and operation; at the same time, various forms of sulfur will also accelerate the corrosion of slurry heating systems, dissolution systems, and evaporation system equipment, bringing corresponding difficulties to the operation of red mud sedimentation separation and mother liquor evaporation processes. Carbon primarily exists in the form of organic carbon and carbonates. When the organic carbon content in the Bayer process liquor reaches a certain level, it can lead to reduced aluminum hydroxide production, finer aluminum hydroxide particles, increased impurity levels in the alumina product, coloration of the Bayer process liquor and alumina product, reduced red mud settling velocity, increased alkali loss due to the formation of organic sodium salts, crystallization of oxalate along with aluminum hydroxide, accelerated equipment scaling, and increased carbon-alkali content in the system, among other production issues. Iron, primarily found in bauxite in the form of hematite and limonite, enters the alumina production system along with bauxite, increasing alkali consumption and red mud discharge, while also reducing alumina dissolution rate, production efficiency, and even quality. Therefore, high-sulfur bauxite must be desulfurized, decarbonized, and iron removed to achieve efficient and economical utilization of this resource.

[0038] At present, high-sulfur bauxite is mostly desulfurized by flotation, which can remove sulfur-containing minerals while taking away some organic carbon. However, there are problems such as high inorganic carbon content and high iron content in aluminum concentrate, high grinding energy consumption and high reagent usage. Therefore, how to provide a desulfurization, decarbonization and iron removal method for high-sulfur bauxite to achieve impurity removal and quality improvement of high-sulfur bauxite while overcoming the technical problems of fine particle size of carbon-containing minerals in high-sulfur bauxite, difficulty in removing inorganic carbon, high direct grinding cost and high dissolution cost.

[0039] like Figure 1 As shown, the embodiment of the present application provides a method for decarbonizing and removing iron from high-sulfur bauxite, the method comprising:

[0040] S1. Crushing high-sulfur bauxite and screening it to a preset particle size to obtain fine-grained high-sulfur bauxite;

[0041] S2. Wet coarse grinding of the fine-grained high-sulfur bauxite to obtain a coarsely ground slurry;

[0042] S3 adjusts the pH of the coarsely ground slurry, and then adds a flotation agent to the coarsely ground slurry for flotation to achieve desulfurization and organic carbon removal to obtain a desulfurized aluminum concentrate;

[0043] S4 finely grind the desulfurized aluminum concentrate and perform strong magnetic separation to remove iron and inorganic carbon to obtain low-carbon low-iron aluminum concentrate and high-carbon high-iron tailings;

[0044] Wherein, the flotation reagents include inhibitors, activators, composite desulfurization collectors and foaming agents;

[0045] The preset particle size is 6 mm to 9 mm.

[0046] In the embodiment of the present application, the "stage grinding-flotation magnetic combined stage separation technology" is adopted, which not only achieves the purpose of removing impurities and improving the quality of high-sulfur bauxite, but also overcomes the problems of fine particle size of carbon-containing minerals in high-sulfur bauxite, difficulty in removing inorganic carbon, high cost of direct grinding, and high cost of dissolution. It has the characteristics of low energy consumption, low production cost, high recovery rate, strong process adaptability, stable production, and high comprehensive utilization rate.

[0047] Controlling the specific type of flotation reagent can ensure the desulfurization and removal of organic carbon effects during the flotation process, thereby obtaining a relatively pure desulfurized aluminum concentrate.

[0048] Controlling the specific preset particle size can fully guarantee the particle size of fine-grained high-sulfur bauxite, thereby ensuring that the aluminum-containing useful minerals and the sulfur-containing mineral pyrite in the high-sulfur bauxite after subsequent coarse grinding can achieve better monomer dissociation.

[0049] Sulfur concentrate can also be obtained after flotation, and the obtained sulfur concentrate can be sold as raw material for producing sulfuric acid.

[0050] Low-carbon and low-iron aluminum concentrate can be used as aluminum concentrate for alumina production, and high-carbon and high-iron tailings can be used as tailings for the production of unburned bricks.

[0051] In some optional embodiments, the composite desulfurization collector includes butyl xanthate and ethylthiocyanate.

[0052] In the embodiments of the present application, controlling the specific composite desulfurization collector can ensure that the composite desulfurization collector has sufficient collecting capacity while also having strong selectivity, which can reduce the dosage of the composite desulfurization collector and ensure that the S content in the desulfurized aluminum concentrate meets expectations.

[0053] In order to achieve the best collection capacity and appropriate selectivity, the mass ratio of butyl xanthate and ethyl thiocyanate is generally maintained at 2:1.

[0054] In some optional embodiments, the butyl xanthate includes tert-butyl xanthate and / or isobutyl xanthate.

[0055] In the embodiments of the present application, controlling the specific type of butyl xanthate can ensure that the composite desulfurization collector has sufficient collecting capacity while also having strong selectivity, which can reduce the dosage of the composite desulfurization collector and ensure that the S content in the desulfurized aluminum concentrate meets expectations.

[0056] In some optional embodiments, the ratio of the added amount of the composite desulfurization collector to the added amount of the foaming agent is 3.5:1 to 3:1.

[0057] In the embodiments of the present application, the specific ratio of the addition amount of the composite desulfurization collector and the foaming agent is controlled, which not only ensures that sufficient bubbles are generated in the desulfurization process, thereby promoting the composite desulfurization collector to play a role, but also prevents excessive use of the foaming agent from resulting in a decrease in the aluminum concentrate yield and the S content of the sulfur concentrate.

[0058] In some optional embodiments, the coarse grinding satisfies that the proportion of ore materials with a grinding fineness of ≤0.038 mm is 55% to 75%.

[0059] In the embodiment of the present application, controlling the specific proportion of ore with a grinding fineness of ≤0.038mm in coarse grinding can better achieve monomer dissociation of useful aluminum-containing minerals and sulfur-containing mineral pyrite in fine-grained high-sulfur bauxite; if the proportion of the ore is too large, it will be detrimental to the flotation removal of sulfur-containing minerals and will increase the energy consumption of grinding; if the proportion of the ore is too small, the dissociation of pyrite and useful aluminum-containing minerals in sulfur-containing minerals will be incomplete, resulting in an increase in the S content of the aluminum concentrate, thereby affecting the quality of the desulfurized aluminum concentrate.

[0060] In some optional embodiments, the fine grinding satisfies the requirement that the ore material has a grinding fineness of ≤0.038 mm, accounting for 80% to 90%.

[0061] In the embodiment of the present application, controlling the specific ore proportion with a grinding fineness of ≤0.038mm in fine grinding can better achieve monomer dissociation of useful aluminum-containing minerals and inorganic carbon-containing siderite, iron-containing hematite and limonite in the desulfurized aluminum concentrate; if the ore proportion is too large, it will be unfavorable for the magnetic separation and removal of inorganic carbon-containing and iron-containing minerals, and increase the energy consumption of grinding; if the ore proportion is too small, the dissociation of inorganic carbon-containing minerals, iron-containing minerals and useful aluminum-containing minerals will be incomplete, resulting in an increase in the C content and Fe2O3 content of the aluminum concentrate, thereby affecting the quality of the final aluminum concentrate (low-carbon and low-iron aluminum concentrate).

[0062] In some optional embodiments, the number of strong magnetic separation is 2 to 3 times.

[0063] In the embodiment of the present application, the specific number of strong magnetic separations is controlled to ensure that the strong magnetic separation has one roughing selection and one scavenging selection, or one roughing selection and two scavenging selections, thereby ensuring the number of magnetic separations, which can better achieve the purpose of separating useful aluminum-containing minerals from inorganic carbon-containing minerals and iron-containing minerals in the desulfurized aluminum concentrate.

[0064] In some optional embodiments, when the number of strong magnetic separations is three, the strong magnetic separation includes roughing, first sweeping, and second sweeping; the magnetic field intensity of the roughing is 0.9T to 1T; and / or,

[0065] The magnetic field strength of the first scan is 1.1T to 1.3T; and / or,

[0066] The magnetic field strength of the second scan is 1.3T to 1.5T.

[0067] In the embodiment of the present application, the specific magnetic field strengths of roughing, first scavenging and second scavenging are controlled, and the stepped magnetic field strength can be utilized to complete the effective separation between inorganic carbon-containing minerals, iron-containing minerals and useful aluminum-containing minerals, thereby achieving the removal of iron and inorganic carbon in the desulfurized aluminum concentrate.

[0068] In some optional embodiments, the chemical composition of the high-sulfur bauxite includes, by mass fraction:

[0069] Al2O3≥45%, Fe2O3≤22%, S:0.8%~5%, C:0.8%~4%, and the rest are unavoidable impurities.

[0070] In the embodiments of the present application, the specific chemical composition of high-sulfur bauxite is controlled, which can cover most high-sulfur bauxite and ensure the removal effect of sulfur, organic carbon, iron and inorganic carbon in high-sulfur bauxite in the method of the present application.

[0071] like Figure 2 As shown, in some optional embodiments, the crushing of high-sulfur bauxite and screening with a preset particle size to obtain fine-grained high-sulfur bauxite includes the steps of:

[0072] S101. Crushing high-sulfur bauxite and screening it to a preset particle size to obtain coarse-grained high-sulfur bauxite and screening material;

[0073] S102. Crushing the coarse-grained high-sulfur bauxite to the preset particle size, and mixing the screened material to obtain fine-grained high-sulfur bauxite.

[0074] In the embodiment of the present application, the screening is further refined, and the high-sulfur bauxite can be cyclically and continuously crushed, so that a sufficient amount of fine-grained high-sulfur bauxite can be obtained, and the transformation of high-sulfur bauxite to fine-grained high-sulfur bauxite can be preliminarily completed.

[0075] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0076] Example 1

[0077] High-sulfur bauxite is taken from a place in Guangxi. Calculated by mass fraction, the chemical composition of high-sulfur bauxite includes:

[0078] Al2O3: 52.25%, SiO2: 8.52%, Fe2O3: 16.37%, C: 1.37%, S: 2.41%, and A / S is 6.13.

[0079] Useful minerals are diaspore and gibbsite, and gangue minerals are mainly chlorite, hematite, siderite, pyrite, rutile, etc.; harmful impurities include pyrite, hematite, limonite, organic carbon and siderite containing inorganic carbon. The specific steps of decarbonization and iron removal are as follows: Figure 3 As shown:

[0080] The high-sulfur bauxite is crushed and screened with a preset particle size of 7 mm. The high-sulfur bauxite with a particle size of >7 mm returns to the crusher for further crushing, while the high-sulfur bauxite with a particle size of ≤7 mm enters the rod mill with water and is coarsely ground to a particle size of ≤0.038 mm, accounting for 60.31%;

[0081] An appropriate amount of Na2CO3 is then added to adjust the pH of the flotation pulp to 8.5, the dosage of the inhibitor Na2O·nSiO2 is 1000g / t; the dosage of the pyrite activator CuSO4 is 40g / t; the total amount of the composite desulfurization collector (formed by mixing isobutyl xanthate and ethyl dithiocarbamide in a ratio of 2:1) is 300g / t (150g / t for roughing, 90g / t for first concentration, and 60g / t for second concentration), and the total amount of the foaming agent pine oil is 100g / t (50g / t for roughing, 30g / t for first concentration, and 20g / t for second concentration). The "one roughing, two concentrating, three sweeping" closed-circuit process is adopted for flotation desulfurization and organic carbon removal to obtain sulfur concentrate and desulfurized aluminum concentrate.

[0082] The desulfurized aluminum concentrate is finely ground to a content of ≤0.038mm accounting for 83.25%, and then subjected to a coarse (0.9T) and a sweep (1.2T) strong magnetic decarburization and iron removal treatment to obtain low-carbon and low-iron aluminum concentrate and high-carbon and high-iron tailings. The low-carbon and low-iron aluminum concentrate is used as aluminum concentrate for alumina production, the sulfur concentrate is used as raw material for the production of sulfuric acid, and the high-carbon and high-iron tailings are used as tailings for the production of unburned bricks.

[0083] The specific indicators in the above process are shown in Table 1.

[0084] Table 1 Decarburization and iron removal test indicators of high-sulfur bauxite in a certain place in Guangxi

[0085]

[0086] As can be seen from Table 1, after a high-sulfur bauxite in Guangxi is decarbonized and iron-removed by the "stage grinding-flotation magnetic combined stage separation technology", an aluminum concentrate with a yield of 84.25%, an Al2O3 grade of 59.03%, a SiO2 grade of 8.75%, a C content of 0.24%, an S content of 0.21% and an A / S ratio of 6.75 can be obtained. A sulfur concentrate with a yield of 5.71% and an S content of 38.72% can also be obtained, and the tailings with a yield of 10.04% can be used to produce unburned bricks.

[0087] Example 2

[0088] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is:

[0089] High-sulfur bauxite is taken from a place in Henan Province. The chemical composition of high-sulfur bauxite includes:

[0090] Al2O3: 48.91%, SiO2: 7.21%, Fe2O3: 16.37%, C: 1.74%, S: 2.01%, and A / S is 6.78.

[0091] The useful mineral is diaspore, and the gangue minerals are mainly hematite, calcite, chlorite, siderite, pyrite, and anatase; the harmful impurities are pyrite, hematite, limonite, organic carbon, and siderite containing inorganic carbon. The specific steps for decarburization and iron removal are as follows: Figure 3 As shown:

[0092] The high-sulfur bauxite is crushed and screened with a preset particle size of 8 mm. The high-sulfur bauxite with a particle size of >8 mm is returned to the crusher for further crushing, while the high-sulfur bauxite with a particle size of ≤8 mm is fed into the rod mill with water and coarsely ground to a particle size of ≤0.038 mm, accounting for 63.31%;

[0093] An appropriate amount of Na2CO3 is then added to adjust the pH of the flotation pulp to 8.5, the dosage of the inhibitor Na2O·nSiO2 is 1000g / t; the dosage of the pyrite activator CuSO4 is 25g / t; the total amount of the composite desulfurization collector (formed by mixing isobutyl xanthate and ethyl disulfide in a ratio of 2:1) is 400g / t (200g / t for roughing, 100g / t for the first cleaning, and 100g / t for the second cleaning), and the total amount of the foaming agent pine oil is 130g / t (70g / t for roughing, 30g / t for the first cleaning, and 30g / t for the second cleaning). The "one roughing, two cleaning, three sweeping" closed-circuit process is adopted for flotation desulfurization and organic carbon removal to obtain sulfur concentrate and desulfurized aluminum concentrate;

[0094] The desulfurized aluminum concentrate is finely ground to a content of 80.33% of ≤0.038mm and then subjected to a coarse (0.9T) and a sweep (1.3T) strong magnetic decarburization and iron removal treatment to obtain low-carbon, low-iron aluminum concentrate and high-carbon, high-iron tailings. The low-carbon, low-iron aluminum concentrate is used as aluminum concentrate for alumina production, the sulfur concentrate is used as raw material for the production of sulfuric acid, and the high-carbon, high-iron tailings are used as tailings for the production of unburned bricks.

[0095] The specific indicators in the above process are shown in Table 2.

[0096] Table 2 Decarburization and iron removal test indicators of high-sulfur bauxite in a certain place in Henan

[0097]

[0098] As shown in Table 2, after decarburization and iron removal treatment by the "stage grinding-flotation magnetic combined stage separation technology", a high-sulfur bauxite in Henan can obtain an aluminum concentrate with a yield of 83.41%, an Al2O3 grade of 55.73%, a SiO2 grade of 7.52%, a S content of 0.17%, a C content of 0.28% and an A / S ratio of 7.41. A sulfur concentrate with a yield of 5.11% and an S content of 36.11% can also be obtained, and the tailings with a yield of 11.48% can be used to produce unburned bricks.

[0099] Example 3

[0100] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is:

[0101] High-sulfur bauxite is taken from a place in Guizhou. Calculated by mass fraction, the chemical composition of high-sulfur bauxite includes:

[0102] Al2O3: 50.71%, SiO2: 7.21%, Fe2O3: 14.71%, C: 2.01%, S: 3.21%, and A / S is 6.18.

[0103] Useful minerals are diaspore and gibbsite, and gangue minerals are mainly hematite, calcite, siderite, pyrite, rutile, etc.; harmful impurities include pyrite, hematite, limonite, organic carbon and siderite containing inorganic carbon. The specific steps of decarburization and iron removal are as follows: Figure 3 As shown:

[0104] The high-sulfur bauxite is crushed and screened with a preset particle size of 6 mm. The high-sulfur bauxite with a particle size of >6 mm returns to the crusher for further crushing, while the high-sulfur bauxite with a particle size of ≤6 mm enters the rod mill with water and is coarsely ground to a particle size of ≤0.038 mm, accounting for 68.35%;

[0105] An appropriate amount of dilute sulfuric acid was added to adjust the pH of the flotation pulp to 4.5, the dosage of the inhibitor Na2O·nSiO2 was 1200 g / t; the dosage of the pyrite activator CuSO4 was 50 g / t; the total amount of the composite desulfurization collector (formed by mixing tert-butyl xanthate and ethyl disulfide in a ratio of 2:1) was 500 g / t (200 g / t for roughing, 100 g / t for the first cleaning, 100 g / t for the second cleaning, and 100 g / t for the third cleaning), and the total amount of the foaming agent pine oil was 160 g / t (70 g / t for roughing, 30 g / t for the first cleaning, 30 g / t for the second cleaning, and 30 g / t for the third cleaning). A "one roughing, three cleaning, four sweeping" closed-circuit process was adopted for flotation desulfurization and organic carbon removal to obtain sulfur concentrate and desulfurized aluminum concentrate.

[0106] The desulfurized aluminum concentrate is finely ground to a content of 84.33% of ≤0.038mm and then subjected to a coarse (0.9T) secondary sweep (the first sweep is 1.2T, the second sweep is 1.4T) strong magnetic decarburization and iron removal treatment to obtain low-carbon and low-iron aluminum concentrate and high-carbon and high-iron tailings. The low-carbon and low-iron aluminum concentrate is used as aluminum concentrate for alumina production, the sulfur concentrate is used as raw material for the production of sulfuric acid, and the high-carbon and high-iron tailings are used as tailings for the production of unburned bricks.

[0107] The specific indicators in the above process are shown in Table 3.

[0108] Table 3 Decarburization and iron removal test indicators of high-sulfur bauxite in a certain place in Guizhou

[0109]

[0110] As shown in Table 3, after a high-sulfur bauxite in Guizhou is decarbonized and iron-removed by the "stage grinding-flotation magnetic combined stage separation technology", an aluminum concentrate with a yield of 81.92%, an Al2O3 grade of 58.45%, a SiO2 grade of 8.43%, a S content of 0.22%, a C content of 0.29% and an A / S ratio of 6.93 can be obtained. A sulfur concentrate with a yield of 7.01% and an S content of 42.82% can also be obtained, and the tailings with a yield of 11.07% can be used to produce unburned bricks.

[0111] Example 4

[0112] Comparing Example 4 with Example 1, the difference between Example 4 and Example 1 is:

[0113] High-sulfur bauxite is taken from a place in Shanxi. Calculated by mass fraction, the chemical composition of high-sulfur bauxite includes:

[0114] Al2O3: 52.37%, SiO2: 10.32%, Fe2O3: 13.52%, C: 2.58%, S: 3.85%, and A / S is 5.07.

[0115] The useful mineral is diaspore, and the gangue minerals are mainly hematite, calcite, siderite, pyrite, rutile, anatase, etc.; the harmful impurities are pyrite, hematite, limonite, organic carbon and siderite containing inorganic carbon. The specific steps of decarburization and iron removal are as follows: Figure 3 As shown:

[0116] The high-sulfur bauxite is crushed and screened with a preset particle size of 9 mm. The high-sulfur bauxite with a particle size of >9 mm is returned to the crusher for further crushing, while the high-sulfur bauxite with a particle size of ≤9 mm is fed into the rod mill with water and coarsely ground to a particle size of ≤0.038 mm, accounting for 62.48%;

[0117] An appropriate amount of dilute sulfuric acid was added to adjust the pH of the flotation pulp to 5, the dosage of the inhibitor Na2O·nSiO2 was 1400 g / t; the dosage of the pyrite activator CuSO4 was 60 g / t; the total amount of the composite desulfurization collector (tert-butyl xanthate and ethyl disulfide mixed in a ratio of 2:1) was 600 g / t (300 g / t for roughing, 100 g / t for the first cleaning, 100 g / t for the second cleaning, and 100 g / t for the third cleaning), and the total amount of the foaming agent pine oil was 190 g / t (100 g / t for roughing, 30 g / t for the first cleaning, 30 g / t for the second cleaning, and 30 g / t for the third cleaning). A "one roughing, three cleaning, four sweeping" closed-circuit process was adopted for flotation desulfurization and organic carbon removal to obtain sulfur concentrate and desulfurized aluminum concentrate.

[0118] The desulfurized aluminum concentrate is finely ground to a content of 83.86% of ≤0.038mm and then subjected to a coarse (1.0T) secondary sweep (the first sweep is 1.3T, the second sweep is 1.5T) strong magnetic decarburization and iron removal treatment to obtain low-carbon and low-iron aluminum concentrate and high-carbon and high-iron tailings. The low-carbon and low-iron aluminum concentrate is used as aluminum concentrate for alumina production, the sulfur concentrate is used as raw material for the production of sulfuric acid, and the high-carbon and high-iron tailings are used as tailings for the production of unburned bricks.

[0119] The specific indicators in the above process are shown in Table 4.

[0120] Table 4 Decarburization and iron removal test indicators of high-sulfur bauxite in a certain place in Shanxi

[0121]

[0122] As shown in Table 4, after a high-sulfur bauxite in Shanxi is decarbonized and iron-removed by the "stage grinding-flotation magnetic combined stage separation technology", an aluminum concentrate with a yield of 78.51%, an Al2O3 grade of 61.93%, a SiO2 grade of 10.75%, a S content of 0.29%, a C content of 0.33% and an A / S ratio of 5.76 can be obtained. A sulfur concentrate with a yield of 8.76% and an S content of 40.92% can also be obtained, and the tailings with a yield of 12.73% can be used to produce unburned bricks.

[0123] Example 5

[0124] Comparing Example 5 with Example 1, the difference between Example 5 and Example 1 is:

[0125] High-sulfur bauxite is taken from a place in Shanxi. Calculated by mass fraction, the chemical composition of high-sulfur bauxite includes:

[0126] Al2O3: 51.22%, SiO2: 7.52%, Fe2O3: 14.47%, C: 2.22%, S: 4.21%, and A / S is 6.81.

[0127] The useful mineral is diaspore, and the gangue minerals are mainly hematite, calcite, siderite, pyrite, rutile, anatase, etc.; the harmful impurities are pyrite, hematite, limonite, organic carbon and siderite containing inorganic carbon. The specific steps of decarburization and iron removal are as follows: Figure 3 As shown:

[0128] The high-sulfur bauxite is crushed and screened with a preset particle size of 6 mm. The high-sulfur bauxite with a particle size of >9 mm is returned to the crusher for further crushing, while the high-sulfur bauxite with a particle size of ≤9 mm is fed into the rod mill with water and coarsely ground to a particle size of ≤0.038 mm, accounting for 63.82%;

[0129] An appropriate amount of oxalic acid was added to adjust the pH of the flotation pulp to 4, the dosage of the inhibitor Na2O·nSiO2 was 1400 g / t; the dosage of the pyrite activator CuSO4 was 60 g / t; the total amount of the composite desulfurization collector (tert-butyl xanthate and ethyl dithiocarbamide mixed in a ratio of 2:1) was 700 g / t (300 g / t for roughing, 200 g / t for the first cleaning, 100 g / t for the second cleaning, and 100 g / t for the third cleaning), and the total amount of the foaming agent pine oil was 230 g / t (100 g / t for roughing, 70 g / t for the first cleaning, 30 g / t for the second cleaning, and 30 g / t for the third cleaning). A "one roughing, three cleaning, four sweeping" closed-circuit process was adopted for flotation desulfurization and organic carbon removal to obtain sulfur concentrate and desulfurized aluminum concentrate.

[0130] The desulfurized aluminum concentrate is finely ground to a content of 89.52% of ≤0.038mm and then subjected to a coarse (0.9T) secondary sweep (the first sweep is 1.3T, the second sweep is 1.5T) strong magnetic decarburization and iron removal treatment to obtain low-carbon and low-iron aluminum concentrate and high-carbon and high-iron tailings. The low-carbon and low-iron aluminum concentrate is used as aluminum concentrate for alumina production, the sulfur concentrate is used as raw material for the production of sulfuric acid, and the high-carbon and high-iron tailings are used as tailings for the production of unburned bricks.

[0131] The specific indicators in the above process are shown in Table 5.

[0132] Table 5 Decarburization and iron removal test indicators of high-sulfur bauxite in a certain place in Shanxi

[0133]

[0134] As shown in Table 5, after a high-sulfur bauxite in Shanxi is decarbonized and iron-removed by the "stage grinding-flotation magnetic combined stage separation technology", an aluminum concentrate with a yield of 79.02%, an Al2O3 grade of 60.33%, a SiO2 grade of 7.75%, a S content of 0.34%, a C content of 0.28% and an A / S ratio of 7.78 can be obtained. A sulfur concentrate with a yield of 9.02% and an S content of 41.72% can also be obtained, and the tailings with a yield of 11.96% can be used to produce unburned bricks.

[0135] Comparative Example 1

[0136] Comparing Comparative Example 1 with Example 1, the difference between Comparative Example 1 and Example 1 is:

[0137] High-sulfur bauxite is taken from a place in Guangxi. Calculated by mass fraction, the chemical composition of high-sulfur bauxite includes:

[0138] Al2O3: 52.25%, SiO2: 8.52%, Fe2O3: 14.47%, C: 1.37%, S: 2.41%, and A / S is 6.13.

[0139] Useful minerals are diaspore and gibbsite, while gangue minerals primarily include chlorite, hematite, siderite, pyrite, and rutile. Harmful impurities include pyrite, hematite, limonite, organic carbon, and siderite containing inorganic carbon. The specific decarburization and iron removal steps employ flotation desulfurization, as described in Patent CN105233991A.

[0140] The specific indicators in the above process are shown in Table 6.

[0141] Table 6 Decarburization and iron removal test indicators of high-sulfur bauxite in a certain place in Guangxi

[0142]

[0143] As shown in Table 6, Comparative Example 1 can produce an aluminum concentrate with a yield of 93.22%, an Al2O3 grade of 53.93%, a SiO2 grade of 8.78%, a C content of 0.85%, a S content of 0.41%, and an A / S ratio of 6.08. Furthermore, the aluminum concentrate yield in Comparative Example 1 is 8.97% higher than that in Example 1. However, the aluminum concentrate in Comparative Example 1 has high C and S contents. If this aluminum concentrate is used for alumina production, it will affect the subsequent dissolution of alumina. Therefore, the method provided in CN105233991A is not suitable for decarburization and iron removal of high-sulfur bauxite.

[0144] Comparative Example 2

[0145] Comparing Comparative Example 2 with Example 2, the difference between Comparative Example 2 and Example 2 is:

[0146] High-sulfur bauxite is taken from a place in Henan Province. The chemical composition of high-sulfur bauxite includes:

[0147] Al2O3: 48.91%, SiO2: 7.21%, Fe2O3: 17.22%, C: 1.74%, S: 2.01%, and A / S is 6.78.

[0148] The useful mineral is diaspore, and the gangue minerals are primarily hematite, calcite, chlorite, siderite, pyrite, and anatase. Harmful impurities include pyrite, organic carbon, and siderite containing inorganic carbon. The specific decarburization and iron removal steps employ flotation desulfurization, as described in Patent CN105233991A.

[0149] The specific indicators in the above process are shown in Table 7.

[0150] Table 7 Decarburization and iron removal test indicators of high-sulfur bauxite in a certain place in Henan

[0151]

[0152] As shown in Table 7, Comparative Example 2 can obtain an aluminum concentrate with a yield of 94.01%, an Al2O3 grade of 49.51%, a SiO2 grade of 7.44, a C content of 0.99%, an S content of 0.38%, and an A / S ratio of 6.65. Compared with the aluminum concentrate in Example 2, although the yield of Comparative Example 2 is higher, the C and S contents in the aluminum concentrate are higher than those in Example 2. Although the S content of the aluminum concentrate in Comparative Example 2 is lower than 0.40%, the C content is relatively high, which will affect the subsequent Bayer process alumina dissolution. Therefore, the method provided in CN105233991 A is not suitable for desulfurization, decarbonization and upgrading of high-sulfur bauxite, indicating that the method of the present application is necessary for desulfurization, decarbonization and upgrading of high-sulfur bauxite.

[0153] Comparative Example 3

[0154] Comparing Comparative Example 3 with Example 3, the difference between Comparative Example 3 and Example 3 is:

[0155] High-sulfur bauxite is taken from a place in Guizhou. Calculated by mass fraction, the chemical composition of high-sulfur bauxite includes:

[0156] Al2O3: 50.71%, SiO2: 7.21%, Fe2O3: 14.71%, C: 2.01%, S: 3.21%, and A / S is 6.18.

[0157] Useful minerals are diaspore and gibbsite, while gangue minerals primarily include hematite, calcite, siderite, pyrite, and rutile. Harmful impurities include pyrite, hematite, limonite, organic carbon, and siderite containing inorganic carbon. The specific decarburization and iron removal steps employ flotation desulfurization, as described in Patent CN105233991A.

[0158] The specific indicators in the above process are shown in Table 7.

[0159] Table 8 Decarburization and iron removal test indicators of high-sulfur bauxite in a certain place in Guizhou

[0160]

[0161] As shown in Table 8, Comparative Example 3 can obtain an aluminum concentrate with a yield of 92.85%, an Al2O3 grade of 51.68%, a SiO2 grade of 8.32%, a C content of 1.02%, an S content of 0.46%, and an A / S ratio of 6.21. Compared with the aluminum concentrate in Example 3, although the yield of Comparative Example 3 is higher, the C and S contents in the aluminum concentrate are higher than those in Example 3. The C and S contents of the aluminum concentrate in Comparative Example 3 are relatively high, which will affect the subsequent Bayer process alumina dissolution. In addition, the process of Example 3 has the advantages of low reagent dosage, high reagent selectivity, strong collection capacity, and high efficiency compared to Comparative Example 1. Therefore, the method provided by CN105233991A is not suitable for desulfurization, decarbonization and upgrading of high-sulfur bauxite. Therefore, the method provided by CN105233991A is not suitable for desulfurization, decarbonization and upgrading of high-sulfur bauxite, indicating that the method of the present application is necessary for desulfurization, decarbonization and upgrading of high-sulfur bauxite.

[0162] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0163] (1) The embodiment of the present application provides a method for decarbonizing and removing iron from high-sulfur bauxite. By adopting the "stage grinding-flotation magnetic combined decarbonization and iron removal technology", the aluminum minerals in the high-sulfur bauxite are efficiently separated from the sulfur-containing minerals and the carbon-containing minerals, thereby achieving desulfurization and decarbonization of the high-sulfur bauxite, and overcoming the difficulties of uneven particle size distribution of high-sulfur bauxite, high energy consumption of direct grinding, and difficulty in flotation of inorganic carbon.

[0164] (2) The embodiment of the present application provides a method for decarbonizing and removing iron from high-sulfur bauxite, which has the characteristics of low energy consumption, high recovery rate, strong process adaptability, stable production, and high comprehensive resource rate.

[0165] (3) The embodiment of the present application provides a method for decarbonizing and removing iron from high-sulfur bauxite. By desulfurizing, decarbonizing, removing impurities and improving the quality of high-sulfur bauxite, not only high-quality aluminum concentrate for alumina production and sulfur concentrate for producing sulfuric acid can be obtained, but also tailings that can be used to prepare unburned bricks can be obtained, thereby realizing the comprehensive utilization of high-sulfur bauxite and providing technical support for the efficient utilization of high-sulfur bauxite resources. It has extremely important strategic significance for extending the resource guarantee period of the aluminum industry and ensuring the sustainable development of the aluminum industry, and has important economic and social significance for enhancing the competitiveness of companies related to the aluminum industry.

[0166] Various embodiments of the present application may be presented 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 understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have 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, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0167] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0168] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for decarbonizing and removing iron from high-sulfur bauxite, characterized in that: The method comprises: Crushing high-sulfur bauxite and screening it to a preset particle size to obtain fine-grained high-sulfur bauxite; performing wet coarse grinding on the fine-grained high-sulfur bauxite to obtain coarsely ground ore pulp; Adjusting the pH of the coarsely ground slurry, and then adding a flotation agent to the coarsely ground slurry for flotation to achieve desulfurization and organic carbon removal to obtain desulfurized aluminum concentrate; Finely grinding the desulfurized aluminum concentrate and subjecting it to strong magnetic separation to remove iron and inorganic carbon, thereby obtaining low-carbon and low-iron aluminum concentrate and high-carbon and high-iron tailings, respectively; Wherein, the flotation reagents include inhibitors, activators, composite desulfurization collectors and foaming agents; The preset particle size is 6mm to 9mm; The proportion of ore materials meeting the grinding fineness of 0.038 mm or less in the coarse grinding is 55% to 75%; The fine grinding satisfies the requirement that the ore material with a grinding fineness of ≤0.038mm accounts for 80% to 90%; The strong magnetic separation includes roughing, first sweeping and second sweeping; the magnetic field intensity of the roughing is 0.9T to 1T; The magnetic field strength of the first scan is 1.1T~1.3T; The magnetic field strength of the second scan is 1.3T~1.5T; Measured by mass fraction, the chemical composition of the high-sulfur bauxite includes: Al2O3≥45%, Fe2O3≤22%, S:0.8%~5%, C:0.8%~4%, and the rest are unavoidable impurities.

2. The method according to claim 1, characterized in that The composite desulfurization collector comprises butyl xanthate and ethyl thiocyanate, and the mass ratio of the butyl xanthate to the ethyl thiocyanate is 2:

1.

3. The method according to claim 2, characterized in that The butyl xanthate includes tertiary butyl xanthate and / or isobutyl xanthate.

4. The method according to claim 1, wherein The ratio of the added amount of the composite desulfurization collector to the added amount of the foaming agent is 3.5:1 to 3:

1.

5. The method according to claim 1, wherein The method of crushing the high-sulfur bauxite and screening it with a preset particle size to obtain fine-grained high-sulfur bauxite includes the following steps: Crushing high-sulfur bauxite and screening it according to a preset particle size to obtain coarse-grained high-sulfur bauxite and screening material respectively; The coarse-grained high-sulfur bauxite is crushed to the preset particle size, and the screened material is mixed to obtain fine-grained high-sulfur bauxite.

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