WO2024098929A1

WO2024098929A1 - Treatment method for red mud resulting from digestion of high-iron bauxite

Info

Publication number: WO2024098929A1
Application number: PCT/CN2023/117418
Authority: WO
Inventors: 张建强; 马俊伟; 吴国亮; 郭鑫; 姚杰; 刘中原; 杜五星; 张站云; 魏兆斌
Original assignee: 中铝郑州有色金属研究院有限公司
Priority date: 2022-11-08
Filing date: 2023-09-07
Publication date: 2024-05-16
Also published as: CN116037313A

Abstract

The present disclosure relates to a treatment method for red mud resulting from the digestion of high-iron bauxite. The treatment method comprises: providing red mud, and subjecting the red mud to mineral separation, so as to obtain a concentrate with a large particle size and first tailings with a small particle size; dehydrating the concentrate to obtain a dehydrated ore; scattering the dehydrated ore, and then subjecting same to ore phase conversion from weakly magnetic iron ore into magnetite at a first temperature in a reducing gas atmosphere; and carrying out low-intensity magnetic separation on the dehydrated ore that is subjected to ore phase conversion, so as to obtain an iron ore concentrate and second tailings.

Description

Treatment method of red mud dissolved from high iron bauxite

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese patent application No. 202211395973.0 filed on November 8, 2022, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to the field of metallurgy, and in particular to a method for treating red mud dissolved from high-iron bauxite.

Background technique

Red mud is a solid waste generated during the production of alumina. Red mud is produced after the dissolution of bauxite. Red mud is the largest waste slag produced in the non-ferrous metal smelting industry. Every ton of alumina produced will produce 1 to 2 tons of red mud. At present, there are more than 4 billion tons of red mud to be treated in the world, and it is increasing at a rate of 180 million tons per year. With the continuous increase in my country's alumina production, the annual discharge and stockpile of red mud continue to increase. In 2021, my country produced 103 million tons of red mud, and the cumulative stockpile exceeded 1.6 billion tons, covering an area of more than 100,000 mu. The stockpile of red mud is easy to pollute water, soil and atmosphere, and there are safety hazards. It is an urgent problem to be solved for the high-quality development of the alumina industry. Due to the characteristics of strong alkalinity, fine particle size, high viscosity and complex composition of red mud, it is difficult to utilize red mud as a resource. The large-scale low-cost disposal and comprehensive utilization of red mud are still a global problem. In 2021, the comprehensive utilization of red mud in my country was 5.76 million tons, and the comprehensive utilization rate of red mud was only about 5.5%. The "Guiding Opinions on the Comprehensive Utilization of Bulk Solid Waste in the 14th Five-Year Plan" jointly issued by the National Development and Reform Commission and other ministries in 2021 put forward new goals and requirements for the comprehensive utilization of red mud. By 2025, the comprehensive utilization rate of new bulk solid waste should reach 60%, and the stock of existing bulk solid waste should be reduced in an orderly manner.

With the rapid development of my country's alumina industry, alumina production accounts for more than 55% of the world, but bauxite reserves account for only 3.13% of the world, which is far from meeting the domestic alumina production needs, resulting in a continuous increase in demand for imported ore in recent years. In 2021, my country imported a total of 107.4206 million tons of bauxite, while bauxite production was only 85.9 million tons, with a foreign dependence rate of 55.57%. my country's imported bauxite mainly comes from Guinea, Australia, Indonesia and other countries, of which 54.8389 million tons of bauxite were imported from Guinea, accounting for 51.05%. The use of imported bauxite to produce alumina has eased the domestic ore shortage and reduced the production and operation costs of alumina. However, due to the high content of iron minerals in imported bauxite, a large amount of red mud is produced and a large area of land is occupied. The iron content in the red mud dissolved from imported high-iron bauxite is relatively high, and the iron-containing minerals are mainly alnicotinite and hematite, of which alnicotinite accounts for more than 50% of the iron-containing minerals. As alnicotinite has weak magnetic properties, it is seriously impregnated with iron by strong magnetic separation. Therefore, the iron concentrate obtained by conventional magnetic separation methods cannot meet the sales requirements. At present, the iron separation production line that uses direct magnetic separation technology to process the red mud produced by imported bauxite has unstable operation and is sometimes turned on and off due to the low grade of iron concentrate (TFe < 50%).

Summary of the invention

By utilizing one or more embodiments of the present disclosure, the technical problem of difficult treatment of red mud in the field of aluminum ore smelting is solved.

The disclosed embodiment provides a method for treating red mud dissolved from high-iron bauxite, comprising the following steps: providing red mud, beneficiating the red mud to obtain a concentrate with a large particle size and a first tailing with a small particle size; dehydrating the concentrate to obtain a dehydrated ore; breaking up the dehydrated ore, and then performing a mineral phase transformation from weakly magnetic iron ore to magnetite at a first temperature and in a reducing gas atmosphere; and performing weak magnetic separation on the dehydrated ore after the mineral phase transformation to obtain an iron concentrate and a second tailing.

BRIEF DESCRIPTION OF THE DRAWINGS

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

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

FIG1 shows a schematic flow chart of a method for treating red mud dissolved from high-iron bauxite according to some embodiments of the present disclosure.

Detailed ways

In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

Unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present disclosure belongs. In the event of a conflict, the present specification takes precedence.

Unless otherwise specified, various raw materials, reagents, instruments, and equipment used in the present disclosure can be purchased from the market or prepared by existing methods.

At present, there are technical problems in the field of aluminum ore smelting that are difficult to handle red mud.

The technical solution provided by the embodiments of the present disclosure is to solve the above technical problems, and the overall idea is as follows:

The present disclosure provides a method for treating red mud dissolved from high-iron bauxite, as shown in FIG1 , comprising the following steps:

S1: providing red mud, beneficiating the red mud to obtain large-size concentrate and small-size first tailings;

S2: dehydrating the concentrate to obtain dehydrated ore;

S3: after breaking up the dehydrated ore, performing an ore phase transformation from weakly magnetic iron ore to magnetite at a first temperature and in a reducing gas atmosphere; and

S4: The dehydrated ore after the ore phase transformation is subjected to weak magnetic separation to obtain iron concentrate and the second tailings.

Those skilled in the art will understand that red mud, also known as red mud, is solid waste discharged after alumina is extracted from bauxite. It is red in color because it contains a large amount of trivalent iron.

The purpose of beneficiating red mud according to particle size is to select large-sized particles. Large-sized particles have lower viscosity and higher fluidity, and can be used for subsequent concentrate dehydration at a lower cost.

Those skilled in the art will understand that the purpose of dehydration is to facilitate subsequent mineral phase transformation. Since the temperature is high during the mineral phase transformation process, if the concentrate is not dehydrated or has a high water content, it is easy to stick to the wall during the mineral phase transformation in the high-temperature reactor, reducing the conversion efficiency and the iron ore concentrate yield. Excessive water content will also cause additional heat loss.

Those skilled in the art can understand that the weakly magnetic iron ore in step S3 refers to iron-containing minerals such as alnicotinite and hematite contained in red mud.

Those skilled in the art can understand that weak magnetic separation refers to magnetic separation by a weak magnetic field magnetic separator. A weak magnetic field magnetic separator is a conventional concept in the art. The magnetic field strength of the working gap is generally (0.6-1.6)×10 ⁵ A/m.

The iron concentrate TFe in the present disclosure can reach more than 62%, meeting the grade requirements of imported iron ore. TFe refers to the total iron content, which is a commonly used parameter in the field of iron ore testing.

The first tailings disclosed in the present invention can be used for planting tolerant crops after being regulated by soil because of its high porosity and good adsorption performance.

The second tailings disclosed in the present invention can be used to prepare silicate cement because it has the characteristics of increased activity of elements such as silicon, aluminum and iron after roasting.

The method for treating red mud dissolved from high-iron bauxite provided in the embodiment of the present disclosure can reduce the cost of subsequent dehydration and mineral phase conversion by selecting concentrate with larger particle size; weakly magnetic iron minerals are converted into magnetite through mineral phase conversion, and high-grade iron concentrate with TFe of more than 62% can be obtained by magnetic separation; and the first tailings produced in the treatment process can be used for planting tolerant crops after soil regulation, and the second tailings can be used for preparing silicate cement. Almost all parts of the red mud have application value after being treated by the method of the present disclosure. Therefore, the method for treating red mud dissolved from high-iron bauxite provided in the embodiment of the present disclosure can comprehensively utilize red mud and turn waste into treasure.

Those skilled in the art can understand that the iron content in the red mud dissolved from imported high-iron bauxite is relatively high, but the iron-containing minerals are mainly alumite and hematite, of which alumite accounts for more than 50% of the iron-containing minerals. Since alumite has weak magnetic properties, it is seriously impregnated with iron by strong magnetic separation. Therefore, the iron concentrate content using conventional magnetic separation methods cannot meet sales requirements. The present disclosure has a good magnetic separation effect on weakly magnetic alumite, especially for high-iron bauxite in which alumite accounts for more than 50% of the iron-containing minerals.

In some embodiments of the present disclosure, the mineral separation described in step S1 includes at least one of gravity separation or magnetic separation.

Those skilled in the art will appreciate that both gravity separation and magnetic separation can achieve the purpose of separation according to particle size. Gravity separation can be performed by a hydraulic classifying cyclone, and magnetic separation can be performed by a high gradient magnetic separator.

In some embodiments of the present disclosure, the mass of the first tailings accounts for 25% to 40% of the mass of the red mud.

The reason for controlling the mass percentage of fine-grained reduced tailings is that a suitable mass percentage of fine-grained reduced tailings can improve the grade of coarse-grained upgraded concentrate and improve its dehydration performance. The adverse effect of an excessively large content is that it will lead to a low final iron concentrate yield, while the adverse effect of an excessively small content is that it will increase the subsequent drying and roasting energy consumption and cost of the coarse-grained upgraded concentrate.

In some embodiments of the present disclosure, the weight percentage of mineral particles with a particle size of less than 0.023 mm in the concentrate is more than 25% less than the weight percentage of mineral particles with a particle size of less than 0.023 mm in the red mud.

The reason for controlling the weight percentage of mineral particles with a particle size of less than 0.023 mm in the coarse-grained upgraded concentrate is that mineral particles with a particle size of less than 0.023 mm have a greater impact on the dehydration performance of the product. If this percentage in the concentrate is not significantly reduced, it will affect the subsequent dehydration effect of the coarse-grained upgraded concentrate.

In some embodiments of the present disclosure, dehydrating the concentrate comprises the following steps:

S21: sedimenting and filtering the concentrate to obtain a filter cake, and drying the filter cake at a second temperature.

In some embodiments of the present disclosure, the weight percentage of water in the filter cake is ≤25%.

The reason for controlling the weight percentage of filter cake water is that if the content is too large, the subsequent drying and dehydration costs will increase.

Those skilled in the art will understand that the moisture content of the filter cake after conventional red mud filter pressing and dehydration is generally greater than 30%. However, the present invention selects concentrate with larger particle size, which can more easily reduce the moisture content of the filter cake due to the improvement of its particle size distribution.

In some embodiments of the present disclosure, the second temperature is 60°C to 80°C.

Those skilled in the art can understand that the weight percentage of water in the filter cake after the initial dehydration is ≤25%, and the overall particle size of the mineral particles in the filter cake is larger and easier to dry, so it can be dried at a lower temperature, that is, below 80°C, which is conducive to reducing drying energy consumption. However, too low a temperature will significantly affect the drying efficiency, so the second temperature is above 60°C.

Those skilled in the art will appreciate that drying can be performed using a low-temperature dryer.

In some embodiments of the present disclosure, the weight percentage of water in the dehydrated ore is ≤5%.

Those skilled in the art can understand that the weight percentage of water in the filter cake after preliminary dehydration is ≤25%, and the overall particle size of the ore particles in the filter cake is larger and easier to dry, so it is relatively easy to control the weight percentage of water in the dehydrated ore to below 5%. The temperature is high during the ore phase transformation process. If the weight percentage of dehydrated ore water in the dehydrated ore is too high, it is easy to stick to the wall during the ore phase transformation in the high-temperature reactor, reducing the conversion efficiency and the yield of iron ore concentrate, and excessive water will cause additional heat loss.

In some embodiments of the present disclosure, the dehydrated ore is broken up, and the weight percentage of ore particles with a particle size of less than 0.023 mm in the dehydrated ore after breaking up increases by no more than 2% compared to that before breaking up.

The reason for controlling the weight content of the cascade dewatered material with a particle size of less than 0.023 mm after efficient dispersion is Yu: The adverse effect of taking the content too high is that it not only increases the energy consumption of breaking up, but also too many small-sized mineral particles with a particle size of less than 0.023 mm are not conducive to the subsequent high-temperature mineral phase transformation.

In some embodiments of the present disclosure, the reducing gas component in the reducing gas is carbon monoxide, and the concentration of carbon monoxide is 1.5% to 3.5%.

The reason for controlling the carbon monoxide concentration of the reducing gas to 1.5% to 3.5% is that the carbon monoxide concentration plays an important role in the effect of mineral phase transformation. The disadvantage of taking the concentration too small is that it will lead to insufficient transformation of weakly magnetic iron minerals such as aluminum goethite and hematite into magnetite. The disadvantage of taking the concentration too large is that excess CO will continue to react with magnetite to generate weakly magnetic FeO.

In some embodiments of the present disclosure, the first temperature is 650°C to 850°C.

The reason for controlling the first temperature to be 650°C to 850°C is that temperature plays a vital role in the effect of mineral phase conversion. The disadvantage of taking the mineral phase conversion temperature too low is low temperature conversion efficiency. Increased temperature is conducive to the reduction _of aluminum goethite and hematite to magnetite. The disadvantage of taking the mineral phase conversion temperature too high is that over-reduction will occur. _Fe3O4 continues to react with CO to generate FeO with relatively weak magnetism, resulting in a decrease in the magnetism of the converted ore.

In some embodiments of the present disclosure, the mineral phase conversion time is 1 minute to 3 minutes.

The reason for controlling the high-temperature mineral phase conversion time to 1 minute to 3 minutes is that: an appropriate high-temperature mineral phase conversion time can make the reduction reaction proceed effectively and thoroughly. The disadvantage of taking a too small value for the mineral phase conversion time is that the reduction reaction of weakly magnetic iron minerals such as alnicotinite and hematite to magnetite is not sufficient. The disadvantage of taking a too large value for the mineral phase conversion time is that over-reduction is likely to occur, resulting in a decrease in magnetic separation indicators.

The present disclosure is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present disclosure and are not intended to limit the scope of the present disclosure. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then it is carried out according to the general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

Example 1

This embodiment provides a method for treating red mud dissolved from high-iron bauxite.

First, red mud dissolved from Indonesian high-iron bauxite is provided. The red mud has a TFe content of 31.46% by mass, and the iron-containing minerals are mainly alnicotinite and hematite, wherein alnicotinite accounts for 51.65% of the iron-containing minerals.

The method for treating red mud dissolved from high-iron bauxite in this embodiment comprises the following steps Sa to Sd:

Sa: The red mud is beneficiated to obtain large-size concentrate and small-size first tailings.

Among them, the method of mineral separation is gravity separation, and the equipment for gravity separation is hydraulic classification cyclone.

The mass of the first tailings accounts for 39.25% of the mass of red mud.

After the first tailings were conditioned by soil, the germination rate of tolerant crops was 82% in 10 days and the plant height was 25.6 cm in 60 days.

The weight percentage of the ore particles with a particle size of less than 0.023 mm in the concentrate is 29.83% lower than the weight percentage of the ore particles with a particle size of less than 0.023 mm in the red mud;

Sb: The concentrate is subjected to sedimentation and filter pressing to obtain a filter cake, and the filter cake is heated to a second temperature Drying to obtain dehydrated ore,

Among them, the moisture content of the filter cake is 18.89%.

The second temperature is 60°C, and drying is carried out using a low temperature dryer.

The weight percentage of water in the dehydrated ore is 3.35%;

Sc: breaking up the dehydrated ore and adding it into a high temperature reaction furnace to carry out ore phase transformation from weakly magnetic iron ore to magnetite under a first temperature and a reducing gas atmosphere,

Among them, the weight percentage of the ore particles with a particle size of less than 0.023 mm in the dehydrated ore after being dispersed increased by 1.76% compared with that before being dispersed.

The components of the reducing gas are carbon dioxide and carbon monoxide, and the concentration of carbon monoxide is 1.5%;

The first temperature is 650°C and the mineral phase conversion time is 3 minutes;

Sd: The dehydrated ore after the ore phase transformation is subjected to weak magnetic separation to obtain iron concentrate and second tailings.

Among them, the TFe content of iron ore concentrate is 62.18%, which meets the grade requirements of imported iron ore;

The silicate cement prepared with a second tailings dosage of 4.6% meets the 42.5 cement grade requirement in "General Portland Cement" (GB175-2019).

The component contents of each product in this example are shown in Table 1:

Table 1 Component contents of the product of Example 1

Example 2

First, red mud dissolved from Australian high-iron bauxite is provided. The red mud has a TFe content of 34.38% by mass, and the iron-containing minerals are mainly alnicotinite and hematite, wherein alnicotinite accounts for 53.48% of the iron-containing minerals.

The mass of the first tailings accounts for 36.64% of the mass of red mud.

After the first tailings were conditioned by soil, the germination rate of tolerant crops was 83% in 10 days and the plant height was 26.7 cm in 60 days.

The weight percentage of the ore particles with a particle size of less than 0.023 mm in the concentrate is 28.47% lower than the weight percentage of the ore particles with a particle size of less than 0.023 mm in the red mud;

Sb: the concentrate is subjected to sedimentation and filter pressing to obtain a filter cake, and the filter cake is dried at a second temperature to obtain a dehydrated ore,

Among them, the moisture content of the filter cake is 19.35%,

The second temperature is 65°C, and drying is carried out using a low temperature dryer.

The weight percentage of water in the dehydrated ore is 3.82%;

Among them, the weight percentage of the ore particles with a particle size of less than 0.023 mm in the dehydrated ore after being dispersed increased by 1.79% compared with that before being dispersed.

The components of the reducing gas are carbon dioxide and carbon monoxide, and the concentration of carbon monoxide is 2.0%;

The first temperature is 700°C and the time for mineral phase transformation is 2.5 minutes;

Among them, the TFe content of iron ore concentrate is 62.28%, which meets the grade requirements of imported iron ore;

The component contents of each product in this example are shown in Table 2:

Table 2 Component contents of the product of Example 2

Example 3

First, red mud dissolved from Guinea high-iron bauxite is provided. The red mud has a TFe content of 37.46% by mass, and the iron-containing minerals are mainly alnicotinite and hematite, wherein alnicotinite accounts for 56.72% of the iron-containing minerals.

Among them, the method of mineral processing is magnetic separation, and the equipment for magnetic separation is a high gradient magnetic separator.

The mass of the first tailings accounts for 32.48% of the mass of red mud.

After the first tailings were conditioned by soil, the germination rate of tolerant crops was 84% in 10 days and the plant height was 25.4 cm in 60 days.

The weight percentage of the ore particles with a particle size of less than 0.023 mm in the concentrate is 27.66% lower than the weight percentage of the ore particles with a particle size of less than 0.023 mm in the red mud;

Among them, the moisture content of the filter cake is 20.47%,

The second temperature is 70°C, and drying is carried out using a low temperature dryer.

The weight percentage of water in the dehydrated ore is 4.16%;

Among them, the weight percentage of the ore particles with a particle size of less than 0.023 mm in the dehydrated ore after being dispersed increased by 1.69% compared with that before being dispersed.

The components of the reducing gas are carbon dioxide and carbon monoxide, and the concentration of carbon monoxide is 2.5%;

The first temperature is 750°C and the time for mineral phase transformation is 2.0 minutes;

Among them, the TFe content of iron ore concentrate is 62.58%, which meets the grade requirements of imported iron ore;

The component contents of each product in this example are shown in Table 3:

Table 3 Component contents of the product of Example 3

Example 4

First, red mud dissolved from Guinea high-iron bauxite is provided. The red mud has a TFe content of 40.18% by mass, and the iron-containing minerals are mainly alnicotinite and hematite, wherein alnicotinite accounts for 60.59% of the iron-containing minerals.

The mass of the first tailings accounts for 29.73% of the mass of red mud.

After the first tailings were soil-conditioned, the germination rate of tolerant crops was 83% in 10 days and the plant height was 27.3 cm in 60 days.

The weight percentage of the ore particles with a particle size of less than 0.023 mm in the concentrate is 26.75% lower than the weight percentage of the ore particles with a particle size of less than 0.023 mm in the red mud;

Among them, the moisture content of the filter cake is 21.78%,

The second temperature is 75°C, and drying is carried out using a low temperature dryer.

The weight percentage of water in the dehydrated ore is 4.34%;

Among them, the weight percentage of the ore particles with a particle size of less than 0.023 mm in the dehydrated ore after being dispersed increased by 1.83% compared with that before being dispersed.

The components of the reducing gas are carbon dioxide and carbon monoxide, and the concentration of carbon monoxide is 3.0%;

The first temperature is 800°C and the time for mineral phase transformation is 1.5 minutes;

Among them, the TFe content of iron ore concentrate is 62.87%, which meets the grade requirements of imported iron ore;

The component contents of each product in this example are shown in Table 4:

Table 4 Component contents of the product of Example 4

Example 5

First, red mud dissolved from Guinea high-iron bauxite is provided. The red mud has a TFe content of 43.39% by mass, and the iron-containing minerals are mainly alnicotinite and hematite, wherein alnicotinite accounts for 54.68% of the iron-containing minerals.

The mass of the first tailings accounts for 25.83% of the mass of red mud.

After the first tailings were conditioned by soil, the germination rate of tolerant crops was 84% in 10 days and the plant height was 26.4 cm in 60 days.

The weight percentage of the ore particles with a particle size of less than 0.023 mm in the concentrate is 25.69% lower than the weight percentage of the ore particles with a particle size of less than 0.023 mm in the red mud;

Among them, the moisture content of the filter cake is 22.69%.

The weight percentage of water in the dehydrated ore is 4.85%;

Among them, the weight percentage of the ore particles with a particle size of less than 0.023 mm in the dehydrated ore after being dispersed increased by 1.63% compared with that before being dispersed.

The components of the reducing gas are carbon dioxide and carbon monoxide, and the concentration of carbon monoxide is 3.5%;

The first temperature is 850°C, and the time for mineral phase transformation is 1.0 minute;

Among them, the TFe content of iron ore concentrate is 63.16%, which meets the grade requirements of imported iron ore;

The component contents of each product in this example are shown in Table 5:

Table 5 Component contents of the product of Example 5

Comparative Example 1

In this comparative example, the same Indonesian high-iron bauxite red mud as in Example 1 was treated by a method for preparing iron concentrate by suspended roasting of red mud provided in Chinese invention patent application CN107686885A. The component contents of the obtained product are shown in Table 6:

Table 6 Component contents of the product of Comparative Example 1

It can be seen that the iron concentrate of Example 1 is superior to the iron concentrate of Comparative Example 1 in terms of both yield and grade.

Comparative Example 2

In this comparative example, the same Australian high-iron bauxite red mud as in Example 2 was treated by a method for preparing iron concentrate by suspended roasting of red mud provided in Chinese invention patent application CN107686885A. The component contents of the obtained product are shown in Table 7:

Table 7 Component contents of the product of Comparative Example 2

It can be seen that the iron ore concentrate yield of Example 2 is at the same level as the iron ore concentrate of Comparative Example 2, but the grade is much higher than that of the iron ore concentrate of Comparative Example 2.

Comparative Example 3

In this comparative example, the same Guinea high-iron bauxite red mud as in Example 3 was treated by a method for preparing iron concentrate by suspended roasting of red mud provided in Chinese invention patent application CN107686885A. The component contents of the obtained product are shown in Table 8:

Table 8 Component contents of the product of Comparative Example 3

It can be seen that the iron ore concentrate yield of Example 3 is at the same level as the iron concentrate powder of Comparative Example 3, but the grade is much higher than that of the iron concentrate powder of Comparative Example 3.

Comparative Example 4

In this comparative example, the same Guinea high-iron bauxite leaching red mud as in Example 4 was treated by a method for preparing iron concentrate by suspended roasting of red mud provided in Chinese invention patent application CN107686885A. The component contents of the obtained product are shown in Table 9:

Table 9 Component contents of the product of Comparative Example 4

It can be seen that the iron concentrate of Example 4 is superior to the iron concentrate of Comparative Example 4 in terms of both yield and grade.

Comparative Example 5

In this comparative example, the same Guinea high-iron bauxite high-temperature dissolved red mud as in Example 5 was treated by a method for preparing iron concentrate by suspended roasting of red mud provided in Chinese invention patent application CN107686885A. The component contents of the obtained product are shown in Table 10:

Table 10 Component contents of the product of Comparative Example 5

It can be seen that the iron concentrate of Example 5 is superior to the iron concentrate of Comparative Example 5 in terms of both yield and grade.

Related experiments and effect data:

The iron concentrate indicators obtained by the method for dissolving red mud iron selection from imported high-iron bauxite and comprehensive utilization of tailings provided in Examples 1 to 5 and Comparative Examples 1 to 5 are statistically analyzed, and the results are shown in the table below.

As can be seen from the above table, the iron concentrate TFe content obtained in Examples 1 to 5 of the present disclosure is ≥62.18%, which meets the imported iron ore grade requirements, and the iron recovery rate is ≥70.69%; while for the same imported high-iron bauxite leaching red mud, in Comparative Examples 1 to 5, the iron concentrate TFe content is ≤59.69% under the condition of similar iron concentrate yield, which fails to meet the imported iron ore grade requirements, and the iron concentrate recovery rate is 3.85% to 6.24% lower than that of Examples 1 to 5, and the fine-grained reduced tailings in Examples 1 to 5 can be used for tolerant crop planting after soil regulation, and the weak magnetic separation tailings can be used for the preparation of silicate cement. Therefore, Examples 1 to 5 of the present disclosure have significant advantages over Comparative Examples 1 to 5.

The method for treating red mud dissolved from high-iron bauxite provided in the embodiment of the present disclosure reduces the cost of subsequent dehydration and mineral phase conversion by selecting concentrate with larger particle size; weakly magnetic iron minerals are converted into magnetite through mineral phase conversion, and high-grade iron concentrate with TFe of more than 62% can be obtained by magnetic separation; and the first tailings produced in the treatment process can be used for planting tolerant crops after soil regulation, and the second tailings can be used for preparing silicate cement. Almost all parts of the red mud have application value after being treated by the method of the present disclosure. Therefore, the present disclosure can comprehensively utilize red mud and turn waste into treasure.

Various embodiments of the present disclosure 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 rigid limitation on the scope of the present disclosure; therefore, the range description should be considered to have disclosed all possible sub-ranges and single numerical values within the range. For example, the range description from 1 to 6 should be considered to have 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. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

In the present disclosure, unless otherwise specified, directional words such as "upper" and "lower" refer to the directions of the drawings in the accompanying drawings. In addition, in the description of the present disclosure, the terms "include", "comprise", etc. mean "including but not limited to". Moreover, the terms "include", "comprises" or any other variations thereof are intended to Contains non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the sentence "including..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In this article, relational 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 that there is any such 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 be represented: A exists alone, A and B exist at the same time, and B exists alone. For the association relationship of more than three associated objects described by "and/or", it means that any one of the three associated objects can exist alone, or any at least two of them can exist at the same time. For example, for A, and/or B, and/or C, it can be represented that any one of A, B, and C exists alone, or any two of them exist at the same time, or three of them exist at the same time. In this article, "at least one" refers to one or more, and "multiple" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions refer to any combination of these items, including any combination of single (individual) or plural (individual). For example, "at least one (individual) of a, b, or c", or "at least one (individual) of a, b, and c", can all represent: a, b, c, a~b (i.e. a and b), a~c, b~c, or a~b~c, wherein a, b, and c can be single or multiple, respectively.

The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be 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 disclosure. Therefore, the present disclosure will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

A method for treating red mud dissolved from high-iron bauxite, comprising:

Providing red mud and performing beneficiation on the red mud to obtain a concentrate with a large particle size and a first tailing with a small particle size;

dehydrating the concentrate to obtain dehydrated ore;

After the dehydrated ore is broken up, a phase transformation from weakly magnetic iron ore to magnetite is performed at a first temperature and in a reducing gas atmosphere;

The dehydrated ore after the mineral phase transformation is subjected to weak magnetic separation to obtain iron concentrate and second tailings.
The method for treating red mud dissolved from high-iron bauxite according to claim 1, wherein the mineral separation includes at least one of gravity separation or magnetic separation.
The method for treating red mud dissolved from high-iron bauxite according to claim 1, wherein the mass of the first tailings accounts for 25-40% of the mass of the red mud.
According to the method for treating red mud dissolved from high-iron bauxite as claimed in claim 1, the weight percentage of mineral particles with a particle size of less than 0.023 mm in the concentrate is more than 25% less than the weight percentage of mineral particles with a particle size of less than 0.023 mm in the red mud.
The method for treating red mud dissolved from high-iron bauxite according to claim 1, wherein dehydrating the concentrate comprises:

The concentrate is subjected to sedimentation and filter pressing to obtain a filter cake, and the filter cake is dried at a second temperature.
The method for treating red mud dissolved from high-iron bauxite according to claim 5, wherein the weight percentage of water in the filter cake is ≤25%; and/or,

The second temperature is 60°C to 80°C.
The method for treating red mud dissolved from high-iron bauxite according to claim 6, wherein the weight percentage of water in the dehydrated ore is ≤5%.
According to the method for treating red mud dissolved from high-iron bauxite according to claim 1, wherein the dehydrated ore is broken up, and the weight percentage of mineral particles with a particle size of less than 0.023 mm in the dehydrated ore after breaking up increases by no more than 2% compared to before breaking up.
The method for treating red mud dissolved from high-iron bauxite according to claim 1, wherein the reducing gas component in the reducing gas is carbon monoxide, and the concentration of carbon monoxide is 1.5% to 3.5%.
The method for treating red mud dissolved from high-iron bauxite according to claim 1, wherein the first temperature is 650° C. to 850° C.; and/or,

The mineral phase conversion time is 1 minute to 3 minutes.