Dissolution method of high-iron-monohydrate-boehmite-type bauxite

Abstract

The invention relates to the technical field of non-ferrous metallurgy, and discloses a dissolution method of high-iron-monohydrate-boehmite type bauxite. The method comprises the following steps: (1) preparing mixed ore pulp from high-iron monohydrate bauxite, sodium aluminate circulating mother liquor and an additive; the additive is one or a mixture of more of organic alkali, carboxylic acid and amino acid; (2) the mixed ore pulp is subjected to ultrasonic treatment and then heated to 190-280 DEG C for a dissolution reaction, dissolution slurry and dissolution residues are obtained, the dissolution residues are subjected to magnetic separation and recovery, and iron ore concentrate is obtained; the power of the ultrasonic treatment is 200 to 300W, and the time of the ultrasonic treatment is 30 to 50 minutes. According to the method, the problem that iron minerals are difficult to separate due to silicon minerals in the dissolution process of the high-iron monohydrate bauxite is solved. The method is simple in process, low in production cost, low in equipment requirement and good in industrialization prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metallurgy, and particularly relates to a method for digesting high-iron diaspore-type bauxite. Background Art

[0002] When traditional bauxite digestion methods are used for alumina production, only the collection of single aluminum resources is emphasized. Generally, a high proportion of iron minerals are discharged as red mud waste components, which not only brings serious environmental problems but also causes great waste of iron resources. Another problem in the utilization of iron resources in high-iron diaspore-type bauxite is the close combination of iron minerals and silicon minerals. When iron minerals are used as raw materials for the steel industry, silicon mineral impurities will cause the blast furnace slag to thicken, increase the slag volume and energy consumption, and iron ore with too high silicon content even has no utilization value.

[0003] Therefore, if the iron minerals and silicon minerals in high-iron diaspore-type bauxite can be dissociated and separated during the bauxite digestion production process, and the iron component can be recovered, it can not only greatly reduce the discharge of red mud waste during alumina production, but also obtain high-grade iron minerals for utilization, taking into account both environmental and economic benefits. Therefore, it is necessary to improve the existing digestion method to achieve the efficient utilization of iron components in high-iron diaspore-type bauxite.

[0004] CN107201441A discloses a comprehensive utilization method for high-iron bauxite and an additive for treating high-iron bauxite. In this method, the finely ground high-iron bauxite is first mixed with the additive, pelletized, dried, and then subjected to reduction roasting using coal as a reducing agent. After roasting, the agglomerates are crushed, ground, and the iron component is magnetically separated. This method requires an additional high-temperature roasting process, and the subsequent utilization of aluminum resources needs to be realized through two-step wet processes of acid dissolution → alkali neutralization, with more steps, high production costs and a large amount of low-value by-products.

[0005] CN102976374B discloses a method for converting iron minerals in the alumina production process. In this method, one or more of iron or divalent iron compounds are added as additives to the bauxite digestion system to convert the iron minerals in the bauxite into magnetite for separation and recovery. However, it does not mention the content of silicon impurities in the recovered iron, and the divalent iron compounds (such as siderite, pyrite, ferrous chloride, ferrous sulfate, etc.) contain impurity anions, and their introduction into the bauxite digestion process may affect the purity of the alumina product. Similarly, CN 102976375 B discloses a high-pressure digestion method for diaspore-type bauxite, using at least one of iron powder and ether cellulose as an additive to have a physicochemical interaction with the surface of titanium minerals and reduce the concentration of titanate ions in the solution, thereby eliminating the retardation effect of titanium minerals on alumina digestion. This patent mainly focuses on promoting the digestion of alumina and does not involve promoting the dissociation and separation of iron minerals and silicon minerals. CN102976377B discloses a digestion method for boehmite-type bauxite. During the bauxite digestion process, a mixture of one or more of alcohols, sugars, aldehydes, alkanes, activated carbon, graphite, coal, coal tar, and wheat bran is introduced as an additive to replace the traditional additive lime to solve the hindrance of titanium minerals to bauxite digestion and simultaneously perform magnetic conversion on iron minerals. This method also does not notice the influence of silicon mineral impurities on the recovery of iron components. The total iron (TFe) mass percentage content (56.30% - 62.12%) of the obtained iron concentrate and the recovery rate of iron in bauxite (37.82% - 50.26%) are not high, and the new additive contains a variety of long-chain carbon organic substances (such as sugars, alkanes, coal, coal tar, wheat bran, etc.), which is likely to cause an increase in the organic matter content in the bauxite digestion cycle and affect the quality of the alumina product.

[0006] In summary, it is urgent to develop a digestion method for high-iron boehmite-type bauxite to simultaneously solve the problem of the combination of iron minerals and silicon minerals in high-iron bauxite and more efficiently and low-costly solve the problem of difficult utilization of iron resources in high-iron bauxite. Summary of the Invention

[0007] Aiming at the above-mentioned shortcomings and deficiencies of the existing technologies, the purpose of the present invention is to provide a digestion method for high-iron boehmite-type bauxite to solve the problem of difficult separation of iron minerals caused by silicon minerals during the bauxite digestion process. The method has a simple process, low production cost, and low equipment requirements, and has good industrialization prospects.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] The present invention provides a digestion method for high-iron boehmite-type bauxite, including the following steps:

[0010] (1) preparing a mixed slurry from high-iron diaspore type bauxite, sodium aluminate circulating mother liquor and an additive; the additive is a mixture of one or more of an organic base, a carboxylic acid and an amino acid;

[0011] (2) subjecting the mixed ore pulp to ultrasonic treatment, and then heating the mixed ore pulp to 190-280° C. for dissolution reaction to obtain dissolution slurry and dissolution slag, and subjecting the dissolution slag to magnetic separation and recovery to obtain iron concentrate;

[0012] The power of the ultrasonic treatment is 200-300W, and the time is 30-50min.

[0013] Furthermore, the high-iron gibbsite bauxite described in step (1) refers to a bauxite whose main component is gibbsite and whose iron mineral content is greater than 15% (measured in terms of mass percentage in the form of Fe2O3), including gibbsite bauxite and boehmite bauxite.

[0014] Furthermore, the Na2O in the sodium aluminate circulating mother liquor in step (1) k The concentration is 160~280g / L and the Al2O3 concentration is 75~140g / L.

[0015] Furthermore, the mass volume ratio of the added mass of the high-iron gibbsite bauxite in step (1) to the mass volume ratio of the sodium aluminate circulating mother liquor is 130 to 360 g / L.

[0016] Furthermore, the mass volume ratio of the additive added in step (1) to the circulating mother liquor is 0.5 to 50 g / L.

[0017] Furthermore, in step (1), the organic base is preferably at least one of choline, triethanolamine, ethylenediamine, and diethylenetriamine; the carboxylic acid is preferably acetic acid; and the amino acid is preferably glycine.

[0018] Further preferably, the additive in step (1) is choline, triethanolamine, ethylenediamine or diethylenetriamine; more preferably choline. The present invention verifies that when the additive is selected as choline, triethanolamine, ethylenediamine or diethylenetriamine, it has good interface adjustment function and reducibility, and can significantly promote the reduction reaction of iron minerals in the ore to generate magnetic magnetite or iron element, and promote the dispersion and dissociation of iron minerals and silicon mineral impurities in high-iron gibbsite bauxite, improve the iron recovery rate of bauxite and reduce the content of silicon impurities in the iron concentrate obtained by magnetic separation of bauxite slag.

[0019] Furthermore, the dissolution reaction time in step (2) is 30 to 90 minutes.

[0020] More preferably, the dissolution reaction in step (2) is to first heat the temperature to 90-120° C. for a pre-reaction of 90-210 min, and then heat the temperature to 190-280° C. for a reaction of 30-90 min.

[0021] Furthermore, the dissolution slurry described in step (2) is diluted and then finely filtered, and seed crystals are added to the obtained filtrate to promote the decomposition of sodium aluminate in the solution to generate aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid is obtained, which is further calcined to obtain an alumina product, and the liquid is returned to the dissolution process for continued use.

[0022] The principle of the present invention is that by adding a reducing additive with the function of adjusting the surface and interface properties, during the dissolution process of bauxite, the iron minerals in the ore undergo a reduction reaction to generate magnetic magnetite or iron element, and at the same time, the surface properties of the iron minerals are adjusted to disperse and dissociate the silicon mineral impurities closely connected with them, so that the iron minerals can be separated and enriched by simple magnetic separation.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Compared with the traditional dissolution method of adding lime, the method of the present invention uses a low amount of additives, greatly reduces the amount of red mud discharged, and has significant environmental advantages.

[0025] (2) The method of the present invention uses only a small amount of additives to complete the enrichment of iron minerals and the removal of silicon impurities during the dissolution of bauxite, and convert them into easily separable magnetic iron minerals, greatly improving the efficiency of iron resource recovery.

[0026] (3) The method of the present invention does not require the addition of a large number of other equipment in the existing dissolution production process, and is low in cost and simple and easy to implement. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0029] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0030] Example 1

[0031] A high-iron diaspore-type bauxite (mineral composition: 60.60% Al2O3, 25.61% Fe2O3, 10.76% SiO2), 200 mL of recycled mother liquor, and the additive triethanolamine were formulated into a mixed pulp. In the recycled mother liquor: Na2O k The concentration was 250 g / L, the Al2O3 concentration was 125 g / L. The mass ratio of the added bauxite to the volume of the recycled mother liquor was 224 g / L, and the mass ratio of the added additive to the volume of the recycled mother liquor was 5 g / L. The mixed pulp was first ultrasonically treated at a power of 300 W for 40 min, then pre-reacted at 95 °C for 180 min and then heated to 260 °C for a digestion reaction for 60 min to obtain a digested slurry and digested residue. Under these conditions, the obtained digested residue was subjected to magnetic separation at a magnetic field intensity of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate was 86.94% (total iron mass percentage = mass of iron in the iron concentrate (calculated as Fe2O3) / mass of the iron concentrate × 100%), the mass percentage of silicon impurity (calculated as SiO2) was 3.02%, and the iron recovery rate in the bauxite was 75.31% (iron recovery rate = mass of iron in the iron concentrate (calculated as Fe2O3) / mass of iron in the bauxite × 100%). The relative dissolution rate of alumina was 97.94% (relative dissolution rate of alumina = (iron-silicon ratio of bauxite - iron-silicon ratio of digested residue) / (iron-silicon ratio of bauxite - 1) × 100%). The digested slurry was diluted and then subjected to fine filtration. The obtained filtrate was added with seeds to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid was obtained and further calcined to obtain alumina product, and the liquid was returned to the digestion process for continued use. The obtained alumina product meets the GB / T 24487-2022 standard.

[0032] Example 2

[0033] A high-iron diaspore-type bauxite (same mineral composition as in Example 1), 200 mL of recycled mother liquor, and the additive choline were formulated into a mixed pulp. In the recycled mother liquor: Na2O kThe concentration is 230 g / L, the concentration of Al2O3 is 110 g / L, the ratio of the mass of bauxite added to the volume of circulating mother liquor is 250 g / L, and the ratio of the mass of additive added to the volume of circulating mother liquor is 6 g / L; the mixed pulp is first ultrasonically treated at a power of 200 W for 50 min, then pre-reacted at 100 °C for 120 min and then heated to 260 °C for a digestion reaction for 90 min to obtain a digested slurry and digested residue. Under these conditions, the obtained digested residue is subjected to magnetic separation at a magnetic field intensity of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate is 91.67%, the mass percentage of silicon impurity (calculated as SiO2) is 2.68%, and the iron recovery rate in bauxite is 79.28%. The relative digestion rate of alumina is 99.01%. The digested slurry is diluted and then subjected to fine filtration. The obtained filtrate is added with seeds to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid is obtained, and further calcined to obtain alumina product, and the liquid is returned to the digestion process for continuous use. The obtained alumina product meets the standard of GB / T 24487-2022.

[0034] Example 3

[0035] The high-iron diaspore-type bauxite (mineral composition is the same as that in Example 1), 200 mL of circulating mother liquor and the additive ethylenediamine are formulated into a mixed pulp, in which in the circulating mother liquor: Na2O k The concentration is 280 g / L, the concentration of Al2O3 is 140 g / L, the ratio of the mass of bauxite added to the volume of circulating mother liquor is 180 g / L, and the ratio of the mass of additive added to the volume of circulating mother liquor is 3 g / L; the mixed pulp is first ultrasonically treated at a power of 300 W for 30 min, then pre-reacted at 95 °C for 180 min and then heated to 270 °C for a digestion reaction for 75 min to obtain a digested slurry and digested residue. Under these conditions, the obtained digested residue is subjected to magnetic separation at a magnetic field intensity of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate is 80.36%, the mass percentage of silicon impurity (calculated as SiO2) is 4.03%, and the iron recovery rate in bauxite is 78.69%. The relative digestion rate of alumina is 99.01%. The digested slurry is diluted and then subjected to fine filtration. The obtained filtrate is added with seeds to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid is obtained, and further calcined to obtain alumina product, and the liquid is returned to the digestion process for continuous use. The obtained alumina product meets the standard of GB / T 24487-2022.

[0036] Comparative Example 1

[0037] In this comparative example compared with Example 2, the additive choline is replaced with an equal amount of glucose, and the rest are the same.

[0038] Under the conditions of this comparative example, the leaching residue obtained was subjected to magnetic separation under a magnetic field intensity of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate was 62.12%, the mass percentage of silicon impurity (calculated as SiO2) was 12.15%, and the iron recovery rate in the bauxite was 58.22%. The leaching rate of alumina was 96.18%. After the leaching slurry was diluted, it was subjected to fine filtration treatment. Seeds were added to the obtained filtrate to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid was obtained, which was further calcined to obtain alumina products, and the liquid was returned to the leaching process for continued use. The obtained alumina products did not meet the requirements of the GB / T 24487-2022 standard.

[0039] Comparative Example 2

[0040] In comparison with Example 2, in this comparative example, the additive choline was replaced with an equal amount of kerosene, and the rest was the same.

[0041] Under the conditions of this comparative example, the leaching residue obtained was subjected to magnetic separation under a magnetic field intensity of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate was 66.98%, the mass percentage of silicon impurity (calculated as SiO2) was 10.28%, and the iron recovery rate in the bauxite was 62.33%. The leaching rate of alumina was 97.11%. After the leaching slurry was diluted, it was subjected to fine filtration treatment. Seeds were added to the obtained filtrate to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid was obtained, which was further calcined to obtain alumina products, and the liquid was returned to the leaching process for continued use. The obtained alumina products did not meet the requirements of the GB / T 24487-2022 standard.

[0042] From the results of the above Examples 1-3 and Comparative Examples 1-2, it can be seen that in the present invention, using choline, triethanolamine or ethylenediamine as the leaching additive for bauxite, compared with long-chain carbon organic substances such as glucose and kerosene, can significantly promote the reduction of iron minerals in the ore and the dispersion and dissociation from silicon mineral impurities, improve the iron recovery rate of bauxite and reduce the silicon impurity content in the obtained iron concentrate. Among them, the leaching effect with choline as the additive is further significantly improved. And the obtained alumina products have higher quality and can meet the requirements of the GB / T 24487-2022 standard.

[0043] Example 4

[0044] The high-iron boehmite-type bauxite (mineral composition: Al2O3 57.20%, Fe2O3 24.33%, SiO2 12.34%), 200 mL of circulating mother liquor and the additive diethylenetriamine were formulated into a mixed ore pulp, in which in the circulating mother liquor: Na2O kThe concentration is 260 g / L, the concentration of Al2O3 is 126 g / L, the ratio of the mass of bauxite added to the volume of the circulating mother liquor is 360 g / L, and the ratio of the mass of the additive added to the volume of the circulating mother liquor is 10 g / L; the mixed pulp is digested at 280 °C for 90 min to obtain a digested slurry and digested residue. Under these conditions, the obtained digested residue is subjected to magnetic separation at a magnetic field strength of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate is 78.12%, the mass percentage of silicon impurity (calculated as SiO2) is 3.68%, and the iron recovery rate in bauxite is 69.88%. The relative digestion rate of alumina is 97.57%. The digested slurry is diluted and then subjected to fine filtration treatment. Seeds are added to the obtained filtrate to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid is obtained, which is further calcined to obtain alumina products, and the liquid is returned to the digestion process for continued use. The obtained alumina products meet the GB / T 24487-2022 standard.

[0045] Comparative Example 3

[0046] In comparison with Example 4, in this comparative example, diethylenetriamine as the additive is replaced with an equal amount of glycerol, and the rest are the same.

[0047] Under the conditions of this comparative example, the obtained digested residue is subjected to magnetic separation at a magnetic field strength of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate is 75.12%, the mass percentage of silicon impurity (calculated as SiO2) is 8.21%, and the iron recovery rate in bauxite is 69.22%. The relative digestion rate of alumina is 95.82%. The digested slurry is diluted and then subjected to fine filtration treatment. Seeds are added to the obtained filtrate to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid is obtained, which is further calcined to obtain alumina products, and the liquid is returned to the digestion process for continued use. The obtained alumina products meet the GB / T 24487-2022 standard.

[0048] Comparative Example 4

[0049] In comparison with Example 4, in this comparative example, diethylenetriamine as the additive is replaced with an equal amount of methanol, and the rest are the same.

[0050] The magnetic separation of the dissolution residue obtained under the conditions of this comparative example was carried out under a magnetic field intensity of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate was 70.66%, the mass percentage of silicon impurity (calculated as SiO2) was 8.99%, and the iron recovery rate in the bauxite was 65.12%. The dissolution rate of alumina was 96.12%. After the dissolution slurry was diluted, fine filtration was carried out. Seeds were added to the obtained filtrate to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid was obtained, and further calcination was carried out to obtain alumina products, and the liquid was returned to the dissolution process for continued use. The obtained alumina products meet the GB / T 24487-2022 standard.

[0051] From the results of the above Examples 1 to 4 and Comparative Examples 3 to 4, it can be seen that compared with small molecule alcohols such as glycerol and methanol, using choline, triethanolamine, ethylenediamine or diethylenetriamine as the dissolution additive for bauxite in the present invention can significantly promote the reduction of iron minerals in the ore and the dispersion and dissociation from silicon mineral impurities, improve the iron recovery rate of bauxite and reduce the silicon impurity content in the obtained iron concentrate.

[0052] Example 5

[0053] The high-iron diaspore-type bauxite (mineral composition: Al2O3 63.22%, Fe2O3 20.31%, SiO2 11.13%), 200 mL of circulating mother liquor and the additive acetic acid were formulated into a mixed ore pulp. In the circulating mother liquor: Na2O k The concentration was 260 g / L, the Al2O3 concentration was 126 g / L. The mass ratio of bauxite added to the volume of the circulating mother liquor was 220 g / L, and the mass ratio of the additive added to the volume of the circulating mother liquor was 30 g / L. The mixed ore pulp was heated to 260 °C for a dissolution reaction for 90 min to obtain a dissolution slurry and a dissolution residue. The magnetic separation of the dissolution residue obtained under these conditions was carried out under a magnetic field intensity of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate was 73.12%, the mass percentage of silicon impurity (calculated as SiO2) was 5.01%, and the iron recovery rate in the bauxite was 67.64%. The dissolution rate of alumina was 95.88%. After the dissolution slurry was diluted, fine filtration was carried out. Seeds were added to the obtained filtrate to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid was obtained, and further calcination was carried out to obtain alumina products, and the liquid was returned to the dissolution process for continued use. The obtained alumina products meet the GB / T 24487-2022 standard.

[0054] Example 6

[0055] The high-iron diaspore-type bauxite (the same mineral composition as in Example 5), 200 mL of circulating mother liquor and the additive glycine were formulated into a mixed ore pulp. In the circulating mother liquor: Na2O kThe concentration is 260 g / L, the concentration of Al2O3 is 126 g / L, the ratio of the added mass of bauxite to the volume of the circulating mother liquor is 300 g / L, and the ratio of the added mass of the additive to the volume of the circulating mother liquor is 3 g / L; the mixed pulp is heated to 270 °C for digestion reaction for 80 min to obtain a digested slurry and digested residue. Under these conditions, the obtained digested residue is subjected to magnetic separation at a magnetic field intensity of 160 kA / m. The mass percentage of total iron (calculated as Fe2O3) in the obtained iron concentrate is 77.16%, the mass percentage of silicon impurity (calculated as SiO2) is 4.22%, and the iron recovery rate in the bauxite is 69.01%. The digestion rate of alumina is 98.95%. The digested slurry is diluted and then subjected to fine filtration treatment. The obtained filtrate is added with seeds to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid is obtained, and further calcined to obtain alumina product, and the liquid is returned to the digestion process for continuous use. The obtained alumina product meets the GB / T 24487-2022 standard.

[0056] The above-described embodiments are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for digesting high-iron diaspore-type bauxite, characterized in that, It includes the following steps: (1) Prepare a mixed ore pulp from high-iron boehmite-type bauxite, sodium aluminate circulating mother liquor, and an additive; the additive is a mixture of one or more of an organic base, a carboxylic acid, and an amino acid; (2) Perform ultrasonic treatment on the mixed ore pulp, and then heat it to 190-280 °C for a digestion reaction to obtain a digested slurry and digested residue. The digested residue is subjected to magnetic separation to recover iron concentrate; The power of the ultrasonic treatment is 200-300 W, and the time is 30-50 min.

2. The digestion method of a high-iron diasporic bauxite according to claim 1, characterized in that, The high-iron boehmite-type bauxite in step (1) refers to bauxite with the main component of boehmite and an iron mineral content > 15%, including diaspore-type bauxite and boehmite-type bauxite.

3. The digestion method of a high-iron diaspore-type bauxite according to claim 1, characterized in that, The Na2O of the sodium aluminate circulating mother liquor described in step (1) k has a concentration of 160 to 280 g / L and the Al2O3 concentration is 75 to 140 g / L.

4. The digestion method of a high-iron diaspore-type bauxite according to claim 1, characterized in that, The mass ratio of the added high-iron boehmite-type bauxite to the mass volume of the sodium aluminate circulating mother liquor in step (1) is 130-360 g / L.

5. The digestion method of a high-iron diasporic bauxite according to claim 1, characterized in that, The mass ratio of the added additive to the mass volume of the circulating mother liquor in step (1) is 0.5-50 g / L.

6. The digestion method of a high-iron diaspore-type bauxite according to claim 1, wherein, The organic base in step (1) is at least one of choline, triethanolamine, ethylenediamine, and diethylenetriamine; the carboxylic acid is acetic acid; the amino acid is glycine.

7. The digestion method of a high-iron diaspore-type bauxite according to claim 1, wherein, The additive in step (1) is choline, triethanolamine, ethylenediamine, or diethylenetriamine.

8. The digestion method of a high-iron diaspore-type bauxite according to claim 1, wherein The additive in step (1) is choline.

9. The digestion method of a high-iron diaspore-type bauxite according to claim 1, wherein The digestion reaction in step (2) means first heating to 90-120 °C for a pre-reaction for 90-210 min, and then heating to 190-280 °C for a reaction for 30-90 min.

10. The digestion method of a high-iron diaspore-type bauxite according to claim 1, characterized in that The digested slurry in step (2) is diluted and then subjected to fine filtration. The obtained filtrate is added with seeds to promote the decomposition of sodium aluminate in the solution to form aluminum hydroxide. After solid-liquid separation again, aluminum hydroxide solid is obtained, and further calcined to obtain alumina product, and the liquid is returned to the digestion process for continued use.