Method for preparing low-iron low-titanium high-quality aluminum-silicon oxide from coal gangue

Abstract

The invention belongs to the technical field of comprehensive utilization of coal gangue solid waste resources, and particularly relates to a method for preparing a low-iron low-titanium high-quality active aluminum-silicon material from coal gangue. The method comprises the following steps: pretreatment of raw materials: crushing coal gangue, grinding, magnetizing roasting and magnetic separation to obtain iron-poor phase aluminum-silicon powder; chemical activation: performing normal-pressure desiliconization treatment through a sodium hydroxide solution to obtain desiliconized activated aluminum-silicon powder; acid leaching impurity removal: leaching impurities at normal temperature by using hydrochloric acid to obtain impurity-removed aluminum-silicon powder; drying and magnetization are carried out, the aluminum-silicon powder is subjected to rapid magnetization treatment in a reducing atmosphere, and the magnetic response performance is improved; and finally, magnetic impurities are thoroughly separated through magnetic separation, and the high-purity active aluminum-silicon material with the Fe2O3 content being smaller than or equal to 0.1% and the TiO2 content being smaller than or equal to 0.5% is obtained. The method is mild in operation, low in energy consumption and simple in step, and the obtained product is suitable for high-added-value application scenes such as ceramics, high-performance fillers and catalytic carriers.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of comprehensive utilization of coal gangue solid waste resources, and particularly relates to a method for preparing low-iron low-titanium high-quality active aluminum-silicon material from coal gangue. BACKGROUND

[0002] Coal gangue is a large amount of solid waste generated in the process of coal mining and washing. For a long time, due to its complex mineral composition, high impurity content and low resource utilization rate, it has been facing the problems of low resource utilization rate and high environmental pollution risk. However, coal gangue is rich in a certain proportion of aluminum-silicon minerals, especially alumina and silicon dioxide. If they can be efficiently separated and purified, and converted into aluminum-silicon oxides with high activity, high purity and low impurities, it will have an important impact on many industries such as inorganic materials, fillers, catalyst carriers, ceramics, and new building materials. Therefore, around the extraction and high-value utilization of aluminum-silicon resources in coal gangue, it has become a research hotspot in the current solid waste resource utilization technology.

[0003] At present, the aluminum extraction and silicon extraction processes for coal gangue mainly focus on the technical paths of roasting-acid leaching, sintering-alkali dissolution, hydrothermal reaction and flotation-classification. These traditional processes have multiple technical bottlenecks, for example: high-temperature roasting consumes a huge amount of energy, usually requires a continuous reaction above 800℃, has high requirements for equipment and high energy consumption cost; in the acid leaching or alkali dissolution reaction, high-concentration inorganic acid or alkali is used, which is highly corrosive and the residual liquid is difficult to handle, increasing the environmental risk; in addition, it is difficult to effectively remove impurities such as iron and titanium during the extraction of aluminum-silicon oxides, resulting in low purity of the obtained products, which limits their application in high-value-added material fields. Especially, impurities such as Fe2O3 and TiO2, even if the content is only below 0.5%, will significantly affect the application performance of aluminum-silicon oxides in ceramics, high-performance fillers or electronic materials.

[0004] Another important problem is that iron and titanium in coal gangue exist in the form of magnetism or inclusions, and simple magnetic separation process is difficult to completely separate them from non-magnetic aluminum-silicon phases. If there is no magnetization treatment of coal gangue powder before magnetic separation, the magnetic phase distribution is uneven and the magnetic difference is significant, resulting in low beneficiation efficiency and high impurity residue. In addition, although some existing processes try to introduce magnetization roasting or composite reduction treatment technology to improve the efficiency of magnetic separation, there are still problems such as incomplete magnetization and unstable beneficiation indexes, which are difficult to meet the needs of industrialized stable preparation of low-iron low-titanium aluminum-silicon oxides.

[0005] From the existing research and industrialization process, to realize the efficient extraction of aluminum-silicon components in coal gangue and obtain high-purity aluminum-silicon oxide products with Fe2O3≤0.1% and TiO2≤0.5%, the following core technical difficulties need to be systematically solved: 1. How to realize the pre-removal of silicon under low temperature and low energy consumption conditions, while avoiding the loss of aluminum components; 2. How to effectively remove impurities such as iron, titanium, calcium, sodium, etc. by optimizing acid leaching parameters and impurity removal paths, and improve the purity and quality of the products; 3. How to enhance the magnetic response ability of the powder through physical and chemical synergistic activation means, and provide protection for subsequent efficient magnetic separation of iron; 4. How to realize the recycling of acid and alkali resources in the whole purification process, reduce reagent consumption and environmental pressure.

[0006] Therefore, there is an urgent need for a coal gangue resource aluminum and silicon extraction technology scheme with efficient desiliconization activation, selective impurity removal, precise regulation of magnetic characteristics, and green low-carbon, to realize the preparation of low-iron low-titanium high-purity aluminum-silicon oxide, improve the added value and application breadth of coal gangue resources, and help realize the goal of high-value utilization of solid waste resources. SUMMARY

[0007] The purpose of the present application is to provide a method for preparing low-iron low-titanium high-quality active aluminum-silicon material from coal gangue, aiming to solve the problems of difficult effective removal of impurities, high energy consumption, large amount of reagent used and low purity of aluminum-silicon oxide in the existing coal gangue resource utilization process.

[0008] In order to achieve the above purpose, the present application provides the following technical scheme:

[0009] A method for preparing low-iron low-titanium high-quality active aluminum-silicon material from coal gangue, comprising the following steps:

[0010] (1) Raw material pretreatment: crushing, grinding, magnetization roasting of coal gangue, and then removing iron-rich magnetic phase by magnetic separation to obtain iron-poor phase aluminum-silicon powder;

[0011] (2) Chemical activation: mixing the iron-poor phase aluminum-silicon powder with sodium hydroxide solution, carrying out normal pressure desiliconization reaction, and after reaction, solid-liquid separation is carried out to obtain solid phase desiliconization activated aluminum-silicon powder;

[0012] (3) Acid leaching of impurities: mixing the desiliconization activated aluminum-silicon powder with hydrochloric acid, carrying out normal pressure impurity removal reaction, and after reaction, solid-liquid separation is carried out to obtain solid phase impurity removal aluminum-silicon powder;

[0013] (4) Drying and magnetization: preheating the impurity removal aluminum-silicon powder and feeding it into a fluidized magnetization drying furnace for magnetization treatment to obtain magnetized active aluminum-silicon powder;

[0014] (5) Magnetic separation: magnetic separation of the magnetized active aluminum-silicon powder to finally obtain active aluminum-silicon material with Fe2O3 content ≤0.1% and TiO2 content ≤0.5%.

[0015] Further, the atmosphere of the magnetization roasting in step (1) is a mixed atmosphere of air and carbon monoxide, and the volume ratio of air to carbon monoxide is (2-5):1.

[0016] Further, the concentration of the sodium hydroxide solution in step (2) is 5-20wt%, and the volume ratio of the iron-poor phase aluminum-silicon powder to the sodium hydroxide solution is (1-2):(3-10).

[0017] Further, the temperature of the atmospheric desiliconization reaction in step (2) is 60-90℃, and the time is 0.5-2h.

[0018] In the present application, the chemical activation treatment in step (2) is a key link for realizing the preparation of high-purity aluminum-silicon materials. Through the atmospheric alkali dissolution reaction of the iron-poor phase aluminum-silicon powder with sodium hydroxide, the selective removal of the silicon component is realized, and the aluminum-silicon skeleton is activated in the microstructure. The reaction is carried out under mild conditions, which can effectively dissolve the free or weakly bound SiO2 to generate soluble silicate that migrates to the liquid phase, thereby increasing the relative proportion of Al2O3 in the solid phase and improving the aluminum-silicon ratio of the material. At the same time, the desiliconization process forms pores and micro-cracks on the particle surface and in the interlayer structure, significantly improving the reaction activity and acid leaching permeability of the powder, providing more efficient migration channels for the subsequent impurity removal reaction, so that Fe 3+ , Ti 4+ and other impurities can be more fully released and dissolved in the acid leaching stage. In addition, this step helps to improve the specific surface area and dispersibility of the powder, and enhances the efficiency and magnetic response characteristics of the subsequent magnetization reaction. Since the operating conditions are mild, the by-product liquid is easy to recover and process, and the alkali utilization rate is high, the entire process not only takes into account technical efficiency and resource utilization, but also meets the concept of green and clean production.

[0019] Further, the volume ratio of the desiliconized activated aluminum-silicon powder to hydrochloric acid in step (3) is (1-1.5):(2-10).

[0020] Further, the temperature of the atmospheric impurity removal reaction in step (3) is 20-30℃, and the time is 0.5-2h.

[0021] Further, the liquid phase obtained after the solid-liquid separation in step (3) is a mixed solution of chlorinated salts, and the mixed solution of chlorinated salts is recycled in step (3) after being supplemented with hydrochloric acid.

[0022] Further, when the concentration of the mixed solution of chlorinated salts is ≥200g / L, a negative pressure salt separation process is carried out, the solid phase obtains a crystalline chlorinated salt, and the gas phase obtains a mixed solution of hydrochloric acid and water, which enters a hydrochloric acid concentration tower, and water is obtained at the top of the tower, and hydrochloric acid is obtained at the bottom of the tower.

[0023] Furthermore, the vacuum degree of the negative pressure salt separation process is 10-20 kPa, and the evaporation temperature is 40-70°C.

[0024] In this invention, the core function of acid leaching in step (3) is to selectively remove non-aluminum silicon components such as iron, titanium, calcium, and sodium by using hydrochloric acid to react with impurity elements in the desiliconized activated aluminum silicon powder through complexation and dissolution reactions, thereby further improving the solid phase purity and aluminum-silicon ratio. After the previous desiliconization treatment, the internal structure of the aluminum silicon powder is effectively activated, forming a large number of microporous channels and loose boundaries. These structures significantly improve the permeability and reactivity of the acid solution, allowing hydrochloric acid to fully contact the impurities and dissolve them quickly. During the reaction, Fe 3+ Ti 4+ Cations and Cl - Stable water-soluble chlorides, such as FeCl3 and TiCl4, are formed and effectively migrate to the liquid phase. Simultaneously, alkaline earth and alkali metal impurities, such as calcium and sodium, can be dissolved in hydrochloric acid to form soluble salts like CaCl2 and NaCl. The overall reaction exhibits good selectivity and migration efficiency. Compared to polyvalent anion systems like sulfuric acid, the chloride system has higher solubility for impurity salts, avoiding secondary coating or pore blockage problems caused by impurity precipitation, thus improving the thoroughness of impurity removal and the continuity of the reaction. This step is carried out under mild conditions, at room temperature and pressure, avoiding structural damage and energy consumption burdens caused by high-temperature side reactions. Furthermore, the resulting liquid-phase chloride salt mixture has a stable composition and can be recycled through acid replenishment, demonstrating good resource utilization efficiency and industrial adaptability.

[0025] Furthermore, the magnetization treatment in step (4) is carried out at a temperature of 400–850°C for a time of 20–180 s.

[0026] Furthermore, the magnetization treatment in step (4) is carried out in a mixed atmosphere of air and carbon monoxide, with a volume ratio of air to carbon monoxide of (1-3):1.

[0027] In the present application, the drying and magnetizing treatment of step (4) remolds the physical structure and magnetic characteristics of the aluminum-silicon powder through the synergistic effect of high temperature and a specific atmosphere. This process uses a fluidization device to heat the impurity-removed aluminum-silicon powder to about 700℃ in a short time while introducing a weak reducing atmosphere composed of air and carbon monoxide, so that the powder undergoes surface and interface microstructure rearrangement under the short-term high-temperature excitation. In particular, the trace amounts of impurities such as Fe2O3 and TiO2 originally remaining in the powder are partially converted into low-valence or spinel-type magnetic components with stronger magnetic response capability under this atmosphere condition, thereby giving the impurity components a clear magnetic contrast without changing the main aluminum-silicon skeleton. This magnetic difference is the basis for achieving efficient separation in the subsequent magnetic separation process. Compared with the traditional normal-temperature magnetic separation which is prone to leave weakly magnetic impurities, this step realizes the "magnetic recognizable" treatment of impurities by precisely regulating the reaction atmosphere and the heating and residence time. In addition, the uniform heat transfer characteristics of the fluidization system ensure that the powder is heated uniformly and does not agglomerate, avoiding the collapse of crystal type or sintering of particles caused by local overheating, and ensuring the stability and dispersibility of the product structure. After this step, the saturation magnetization of the aluminum-silicon powder is significantly improved, the magnetic characteristics are clear, and the magnetic separation efficiency is greatly improved.

[0028] Further, the magnetic separation of step (5) is dry magnetic separation or wet magnetic separation.

[0029] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0030] The present application realizes the efficient enrichment of aluminum-silicon components and the deep removal of impurities in coal gangue through the synergistic mechanism of "desiliconization + impurity removal + magnetization", effectively improving the purity and magnetic separation efficiency of the aluminum-silicon material. The method completes the core reaction process under normal pressure and low temperature conditions, is energy-saving and environmentally friendly, and the by-products of each step can be recycled, and the process is green and low-carbon. The impurity content of the final product is significantly lower than that of the traditional process, has higher industrial adaptability and material performance, and is suitable for popularization and application in the field of high-value utilization of coal gangue. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0032] The raw materials used in the embodiments are ordinary commercially available products unless otherwise specified.

[0033] Embodiment 1

[0034] The embodiment provides a method for preparing low-iron, low-titanium and high-quality active aluminum-silicon material from coal gangue.

[0035] (1) Raw material pretreatment: the coal gangue is used as the starting raw material, the raw ore is first crushed and ground, so that the particle size is controlled in the range of 50-325 meshes, so as to meet the process requirements of subsequent magnetization roasting. Then the treated coal gangue powder is sent into a magnetization roasting device, short-time roasting is carried out at 600 DEG C, the atmosphere is controlled to be a mixed gas of air and carbon monoxide with a volume ratio of 4:1, the residence time is 80 seconds, so that the valence state of part of the magnetic iron and titanium phase minerals is converted or the crystal form is changed, thereby the magnetization difference between the magnetic and non-magnetic components is enhanced. After the roasting is completed, the material is rapidly cooled and enters a magnetic separation section, magnetic separation is carried out in a magnetic excitation mode, the magnetic iron-rich phase is effectively separated, and thus the iron-poor aluminum-silicon powder is obtained. The A / S ratio of the iron-poor aluminum-silicon powder is 3, the Fe2O3 content is about 0.5%, and the TiO2 content is about 1%.

[0036] (2) Chemical activation: the iron-poor aluminum-silicon powder obtained in step (1) is weighed, the particle size is controlled to be below 100 meshes, and is placed in a four-necked glass reaction bottle. A 10wt% sodium hydroxide solution is prepared and is slowly added into the reaction bottle, so that the solid-liquid volume ratio is controlled to be 1:6. A mechanical stirring device is started, the stirring speed is set to be 300 rpm, a constant temperature water bath is started, and the reaction temperature is controlled to be 80 DEG C. The normal pressure reaction is carried out for 2 hours under the condition of the temperature and stirring. After the reaction is completed, the reaction slurry is subjected to solid-liquid separation through suction filtration. The filter cake is washed with deionized water for 5 times, until the pH value of the washing liquid is reduced to be below 8, so that the unreacted NaOH is fully removed. The obtained filter cake is the desiliconized activated aluminum-silicon powder, which is dried and reserved.

[0037] (3) Acid leaching and impurity removal: the desiliconized activated aluminum-silicon powder is placed into a corrosion-resistant polypropylene stirring reaction bottle, a 10wt% dilute hydrochloric acid solution is prepared, and is added into the reaction bottle according to the volume ratio of the desiliconized activated aluminum-silicon powder to the dilute hydrochloric acid, the mechanical stirrer is started under the room temperature (25 DEG C) condition, the stirring speed is set to be 350 rpm, and the impurity removal reaction is carried out under the normal pressure condition. The reaction time is set to be 1.5 hours. After the reaction is completed, the slurry is subjected to solid-liquid separation through suction filtration. The filter cake is washed with deionized water for 5 times, until the pH value of the washing liquid is close to neutral, so that the residual acid and soluble impurity salts are thoroughly removed, and the obtained solid phase is the impurity-removed aluminum-silicon powder.

[0038] The obtained liquid phase is a mixed solution of chlorinated salts, mainly containing AlCl3, FeCl3, CaCl2, NaCl and other soluble salts, and can be used in the next batch of acid leaching process for recycling. In order to maintain the stability of the acidity, a certain concentration of hydrochloric acid is added before each use, and the acidity is adjusted to pH≈1. If the concentration of the mixed solution of chlorinated salts is ≥200 g / L, the negative pressure concentration method can be selected to recover the hydrochloric acid and crystallize the impurity salts.

[0039] (4) Drying and magnetization: The impurity-removed aluminum-silicon powder obtained in step (3) was placed in a hot air circulating oven and pre-dried at 105°C for 4 hours to remove the residual free water on the surface, obtaining dried impurity-removed aluminum-silicon powder. The dried aluminum-silicon powder was fed into a fluidized magnetization drying furnace for short-time rapid magnetization treatment. The magnetization furnace was a vertical upflow fluidized bed device equipped with a temperature control heating system and an atmosphere adjusting device. The aluminum-silicon powder was uniformly fed into the furnace, the temperature was set to 700°C, the atmosphere was set to a mixture of air and carbon monoxide at a volume ratio of 2:1, the total flow rate of the mixed gas was controlled at 60 mL / min, and the residence time of the aluminum-silicon powder in the atmosphere was set to 90 seconds. After magnetization treatment, the material was quickly carried out by the bottom gas flow and entered the cooling section for rapid cooling to prevent crystal type change and impurity re-aggregation reaction. The obtained powder after cooling was the magnetized active aluminum-silicon powder, which was detected to have a saturation magnetization of about 3.20 A·m 2 ·kg -1 , which was higher than that before treatment (about 0.29 A·m 2 ·kg -1 ·kg, and had good magnetic separation basis.

[0040] (5) Magnetic separation: The magnetized active aluminum-silicon powder obtained in step (4) was placed in a dry high-gradient magnetic separator for magnetic separation, the magnetic field strength was set to 1.2 T, the drum linear velocity was 2.0 m / s, and the feeding rate was controlled at 10 g / min. The magnetic impurities were adsorbed and separated, and the non-magnetic part was collected as the target product, which was the active aluminum-silicon material. The Fe2O3 content was 0.08wt%, and the TiO2 content was 0.45wt%, which met the use requirements of high-purity aluminum-silicon material.

[0041] Comparative Example 1

[0042] The difference between this comparative example and Example 1 was that the atmosphere of magnetization roasting in step (1) was air. The Fe2O3 content in the obtained active aluminum-silicon material was 0.29wt%, and the TiO2 content was 0.54wt%.

[0043] In this comparative example, pure air was used as the atmosphere during magnetization roasting, which lacked the reducing component of carbon monoxide, resulting in ineffective valence conversion of iron and titanium impurities and difficulty in forming a strong magnetic phase that could be magnetically separated. Therefore, the iron-rich impurities could not be fully removed in the magnetic separation stage. Finally, the Fe2O3 content in the obtained active aluminum-silicon material was as high as 0.29wt%, and the TiO2 content was 0.54wt%, which was significantly higher than the optimized conditions and had poor impurity removal effect.

[0044] Comparative Example 2

[0045] The difference between the present comparative example and Example 1 is that sodium hydroxide in step (2) is replaced by potassium hydroxide. It is detected that the Fe2O3 content in the obtained active aluminum-silicon material is 0.21wt%, and the TiO2 content is 0.52wt%.

[0046] After replacing sodium hydroxide with potassium hydroxide, the K+ ion hydration is stronger, and the permeability between the aluminum-silicon structure layers is weaker, resulting in a decrease in desiliconization efficiency, incomplete dissolution of the silicon component, and insufficient opening of the aluminum-silicon skeleton structure, which limits the migration and release space of subsequent impurities and affects the impurity removal depth.

[0047] Comparative Example 3

[0048] The difference between the present comparative example and Example 1 is that hydrochloric acid in step (3) is replaced by sulfuric acid. It is detected that the Fe2O3 content in the obtained active aluminum-silicon material is 0.33wt%, and the TiO2 content is 0.58wt%.

[0049] When using sulfuric acid instead of hydrochloric acid for impurity removal treatment, although the acid strength is comparable, Fe 3+ , Ti 4+ impurities are prone to form insoluble precipitates or complexes in the sulfuric acid medium, resulting in their ineffective migration to the liquid phase. In addition, the dissolution behavior of the sulfate system is different from that of the chloride system, which is not conducive to the formation of recyclable chloride impurity salt solution. The Fe2O3 content in the final product is as high as 0.33wt%, and the TiO2 content is 0.58wt%, which is a serious deficiency in impurity removal.

[0050] Comparative Example 4

[0051] The difference between the present comparative example and Example 1 is that the atmosphere for magnetization treatment in step (4) is air. It is detected that the Fe2O3 content in the obtained active aluminum-silicon material is 0.26wt%, and the TiO2 content is 0.51wt%.

[0052] The present comparative example does not use reducing gas during the magnetization drying stage, but only uses air, which cannot effectively induce the magnetic response conversion of residual impurity phases, resulting in insufficient magnetization activity and decreased magnetic separation rate. Since part of the weakly magnetic impurities cannot be adsorbed by the magnetic field area, they remain in the product, and the Fe2O3 content in the final active aluminum-silicon material is 0.26wt%, and the TiO2 content is 0.51wt%, which significantly reduces the impurity removal performance.

[0053] Comparative Example 5

[0054] The difference between the present comparative example and Example 1 is that the temperature for magnetization treatment in step (4) is 300°C. It is detected that the Fe2O3 content in the obtained active aluminum-silicon material is 0.24wt%, and the TiO2 content is 0.50wt%.

[0055] The temperature of the comparative example is reduced to 300 DEG C in the magnetization treatment stage, and the lower temperature results in that the residual Fe and Ti impurities in the powder cannot complete the full valence state conversion and crystal form adjustment in a short time, so that the overall magnetization intensity of the powder is insufficient, and the subsequent magnetic separation link cannot form effective magnetic difference, and the impurity removal efficiency is obviously decreased.

[0056] The above is the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue, comprising the following steps: (1) Raw material pretreatment: The coal gangue is crushed, ground, magnetized and roasted, and then the iron-rich magnetic phase is removed by magnetic separation to obtain iron-poor phase aluminum silicon powder. (2) Chemical activation: Iron-poor phase aluminum silicon powder is mixed with sodium hydroxide solution and subjected to desilication reaction under normal pressure. After the reaction is completed, solid-liquid separation is performed to obtain solid phase desilication activated aluminum silicon powder. (3) Acid leaching to remove impurities: The desiliconized activated aluminum silicon powder is mixed with hydrochloric acid and subjected to a normal pressure impurity removal reaction. After the reaction is completed, solid-liquid separation is performed to obtain solid phase impurity-removed aluminum silicon powder. (4) Drying and magnetization: After preheating the impurity-removed aluminum silicon powder, it is sent to a fluidized magnetic drying furnace for magnetization treatment to obtain magnetized active aluminum silicon powder. (5) Magnetic separation: The magnetized active aluminum silicon powder is separated by magnetic separation to finally obtain active aluminum silicon material with Fe2O3 content ≤0.1% and TiO2 content ≤0.5%.

2. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 1, characterized in that, The magnetization roasting in step (1) is carried out in a mixed atmosphere of air and carbon monoxide, with a volume ratio of air to carbon monoxide of (2-5):

1.

3. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 1, characterized in that, The concentration of the sodium hydroxide solution in step (2) is 5-20 wt%, and the volume ratio of the iron-poor phase aluminum silicon powder to the sodium hydroxide solution is (1-2):(3-10).

4. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 1, characterized in that, The temperature of the atmospheric pressure desilication reaction in step (2) is 60-90℃ and the time is 0.5-2h.

5. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 1, characterized in that, The volume ratio of the desiliconized activated alumina silicon powder to hydrochloric acid in step (3) is (1-1.5):(2-10).

6. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 1, characterized in that, The temperature of the atmospheric pressure impurity removal reaction in step (3) is 20-30℃, and the time is 0.5-2h.

7. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 1, characterized in that, The liquid phase obtained after solid-liquid separation in step (3) is a chloride salt mixed solution, which is recycled in step (3) after being supplemented with hydrochloric acid.

8. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 7, characterized in that, When the concentration of the chloride salt mixed solution is ≥200g / L, a negative pressure salt separation process is carried out. The solid phase yields crystalline chloride salt, and the gas phase yields a mixed solution of hydrochloric acid and water. The mixed solution enters a hydrochloric acid concentration tower, where water is obtained at the top of the tower and hydrochloric acid is obtained at the bottom.

9. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 1, characterized in that, The magnetization process in step (4) is carried out at a temperature of 400–850°C for 20–180 seconds.

10. The method for preparing low-iron, low-titanium, high-quality active aluminum-silicon materials from coal gangue according to claim 1, characterized in that, The magnetization process described in step (4) is carried out in a mixed atmosphere of air and carbon monoxide, with a volume ratio of air to carbon monoxide of (1-3):1.