A method for efficiently extracting desmear aluminum-iron ion solution from high-iron coal gangue and fly ash

Abstract

The present application relates to a kind of from high iron coal gangue and fly ash efficient extraction of non-sticky aluminum iron ion solution method, belong to coal-based solid waste resource utilization field.The method includes: after adding active agent in coal gangue and / or fly ash is mixed and is roasted to obtain calcine;The calcine is filtered after water immersion, and solid and filtrate are obtained;The solid is separated after acid leaching to obtain the non-sticky aluminum iron ion solution and filter residue of liquid.The present application is activated by reasonable collocation and heat treatment to active agent, and aluminum iron atom is fully activated, can be efficiently leached under mild conditions when acid leaching, to improve the solid-liquid separation efficiency of acid leaching solution, the non-sticky aluminum iron ion solution obtained after processing can be used as water purifying agent and other social needs of high value-added product, the remaining residue is easy to extract silicon and other useful elements, realize the industrialized comprehensive utilization of high iron coal gangue and fly ash.

Description

Technical Field

[0001] This invention relates to a method for efficiently extracting a de-sticky aluminum-iron ion solution from high-speed railway coal gangue and fly ash, belonging to the field of coal-based solid waste resource utilization. Background Technology

[0002] High-iron coal gangue and fly ash contain high levels of aluminum and ferrous ions. During acid leaching to extract these ions, their complex structure and the presence of various components in the leaching solution result in high viscosity, making solid-liquid separation difficult. When using pressure filtration, the sticky substances adhere to the filter cloth, leading to frequent replacements and significantly increasing separation costs. Although industrial-scale attempts at aluminum-ferrous extraction technology have been made, economic issues stemming from the technical bottlenecks in solid-liquid separation have forced cessation. Therefore, efficiently extracting and de-sticking aluminum-ferrous ion solutions is crucial for the high-value utilization of high-iron coal gangue and fly ash. Summary of the Invention

[0003] The purpose of this invention is to provide a method for efficiently extracting de-sticky aluminum and iron ion solutions from high-speed iron coal gangue and fly ash, so as to solve the problems existing in the prior art, reduce the viscosity of the acid leaching solution of aluminum and iron in high-speed iron coal gangue and fly ash, improve the solid-liquid separation efficiency, and fully realize its industrial application.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] One of the technical solutions of this invention: a method for extracting a de-sticky aluminum-iron ion solution from high-speed iron coal gangue and / or fly ash, comprising the following steps:

[0006] Calcined sand is obtained by adding an activator to coal gangue and / or fly ash, mixing and then calcining.

[0007] The calcined sand was soaked in water and then filtered to obtain a solid and a filtrate.

[0008] The solid was subjected to acid leaching followed by solid-liquid separation to obtain the de-adhesive aluminum-iron ion solution and filter residue;

[0009] The activator is a mixture of component A and component B;

[0010] Component A is one or more of sodium carbonate, sodium hydroxide, potassium hydroxide, sodium sulfate, and potassium sulfate.

[0011] Component B is one or more of sodium chloride, potassium chloride, sodium fluoride, and potassium fluoride.

[0012] Furthermore, the coal gangue and / or fly ash contains more than 10 wt% iron oxide and more than 15 wt% alumina.

[0013] Furthermore, the mass ratio of component A to component B is 1:(1-0.1).

[0014] Furthermore, the amount of the activator is 1-60% of the mass of the coal gangue and / or fly ash.

[0015] Furthermore, the calcination temperature is 500-900℃ and the time is 30-120min.

[0016] Furthermore, the water immersion conditions are as follows: solid-liquid ratio of 1g:(1-6)mL, temperature of 40-95℃, and time of 30-120min.

[0017] Furthermore, the acid leaching conditions are as follows: solid-liquid ratio of 1g:(1-6)mL, temperature of 40-95℃, and time of 4-9h. The acid leaching uses hydrochloric acid or sulfuric acid with a concentration of 1-9mol / L.

[0018] Furthermore, the solid-liquid separation method is to use a diaphragm filter press for thermal filtration.

[0019] Furthermore, the thermal filtration temperature is 80-90℃, the pressure is 3.5-5MPa, and the filtration accuracy is 20-50μm.

[0020] Furthermore, the filter cake after hot filtration has a moisture content of 15-30 wt% and a liquid suspended solids content of less than 15 mg / L.

[0021] The acid leaching solution treated by this invention has a relatively uniform particle size, generally distributed in the range of 15-60 μm, with fewer adhesive microparticles and a viscosity below 60 Pa·s. Solid-liquid separation can be achieved by thermal filtration using a diaphragm filter press.

[0022] Furthermore, it also includes the step of adjusting the iron-aluminum molar ratio of the de-adhesive aluminum-iron ion solution to (0.1-1):(0.1-1), aging it at pH 1-6 for 8-24 hours to prepare a water purification agent.

[0023] For example, adjust the aluminum-iron molar ratio to 1:(1-0.1), or adjust the iron-aluminum molar ratio to 1:(1-0.1).

[0024] Furthermore, it also includes the step of collecting the filtrate and the filter residue to extract a silicon-containing solution.

[0025] Furthermore, the filtrate obtained from the filtration can be recycled until the solution reaches a certain concentration before being recycled.

[0026] The second technical solution of the present invention is a method for reducing the viscosity of acid leaching solution for high-iron coal gangue and / or fly ash, wherein the high-iron coal gangue and / or fly ash are treated with the following steps before acid leaching:

[0027] Calcined sand is obtained by adding an activator to coal gangue and / or fly ash, mixing and then calcining.

[0028] The calcined sand was soaked in water and then filtered to obtain a solid and a filtrate.

[0029] The solid was subjected to acid leaching followed by solid-liquid separation to obtain a de-adhesive aluminum-iron ion solution.

[0030] Further, the activator is a mixture of component A and component B; component A is one or more of sodium carbonate, sodium hydroxide, potassium hydroxide, sodium sulfate and potassium sulfate; component B is one or more of sodium chloride, potassium chloride, sodium fluoride and potassium fluoride; the mass ratio of component A to component B is 1:(1-0.1).

[0031] Furthermore, the coal gangue and / or fly ash contains more than 10 wt% iron oxide and more than 15 wt% alumina.

[0032] Furthermore, the amount of the activator is 1-60% of the mass of the coal gangue and / or fly ash.

[0033] Furthermore, the calcination temperature is 500-900℃ and the time is 30-120min.

[0034] Furthermore, the solid-liquid separation method is to use a diaphragm filter press for thermal filtration.

[0035] Furthermore, the thermal filtration temperature is 80-90℃, the pressure is 3.5-5MPa, and the filtration accuracy is 20-50μm.

[0036] Furthermore, the filter cake after hot filtration has a moisture content of 15-30 wt% and a liquid suspended solids content of less than 15 mg / L.

[0037] Furthermore, the water immersion conditions are as follows: solid-liquid ratio of 1g:(1-6)mL, temperature of 40-95℃, and time of 30-120min.

[0038] Furthermore, the acid leaching conditions are as follows: solid-liquid ratio of 1g:(1-6)mL, temperature of 40-95℃, and time of 4-9h.

[0039] Furthermore, the acid leaching uses hydrochloric acid or sulfuric acid with a concentration of 1-9 mol / L.

[0040] The third technical solution of the present invention is a method for improving the solid-liquid separation efficiency of acid leaching solution for high-iron coal gangue and / or fly ash, wherein the high-iron coal gangue and / or fly ash are treated with the following steps before acid leaching:

[0041] Calcined sand is obtained by adding an activator to coal gangue and / or fly ash, mixing and then calcining.

[0042] The calcined sand was soaked in water and then filtered to obtain a solid and a filtrate.

[0043] The solid was subjected to acid leaching followed by solid-liquid separation to obtain a de-adhesive aluminum-iron ion solution.

[0044] Furthermore, the coal gangue and / or fly ash contains more than 10 wt% iron oxide and more than 15 wt% alumina.

[0045] Further, the activator is a mixture of component A and component B; component A is one or more of sodium carbonate, sodium hydroxide, potassium hydroxide, sodium sulfate and potassium sulfate; component B is one or more of sodium chloride, potassium chloride, sodium fluoride and potassium fluoride; the mass ratio of component A to component B is 1:(1-0.1).

[0046] Furthermore, the amount of the activator is 1-60% of the mass of the coal gangue and / or fly ash.

[0047] Furthermore, the calcination temperature is 500-900℃ and the time is 30-120min.

[0048] Furthermore, the solid-liquid separation method is to use a diaphragm filter press for thermal filtration.

[0049] Furthermore, the thermal filtration temperature is 80-90℃, the pressure is 3.5-5MPa, and the filtration accuracy is 20-50μm.

[0050] Furthermore, the filter cake after hot filtration has a moisture content of 15-30 wt% and a liquid suspended solids content of less than 15 mg / L.

[0051] Furthermore, the water immersion conditions are as follows: solid-liquid ratio of 1g:(1-6)mL, temperature of 40-95℃, and time of 30-120min.

[0052] Furthermore, the acid leaching conditions are as follows: solid-liquid ratio of 1g:(1-6)mL, temperature of 40-95℃, and time of 4-9h.

[0053] Furthermore, the acid leaching uses hydrochloric acid or sulfuric acid with a concentration of 1-9 mol / L.

[0054] In traditional methods, silicon, aluminum, and iron readily form localized micro-sol particles in acidic solutions, adsorbing ions and agglomerating into highly adhesive colloidal particles. These particles easily adhere to pores or the surrounding walls of the container, clogging the mesh or filter cloth. This invention uses a mixture of components A and B as an activator, mixed with high-iron coal gangue and / or fly ash, followed by calcination. This alters the atomic composition of elements such as silicon, aluminum, and iron. Component A dissociates the grid structure, while component B, as an auxiliary material, stabilizes the charge and promotes equilibrium. Combined with calcination, this effectively promotes the replacement of impurity atoms in the silicon-oxygen grid structure, causing aluminum and iron ions to detach from the grid and achieve charge balance with the activator. Therefore, no adhesive substances form during acid leaching. As valuable metals dissolve during acid leaching, the silicon atom fragments adjacent to the metal do not detach from the grid structure; the fragment ends are bound by the activator, forming a stable structure and significantly reducing viscosity.

[0055] In a preferred embodiment of the present invention, sufficient aluminum-iron ion solution can be obtained by limiting the content of iron oxide and aluminum oxide in coal gangue and / or fly ash, thereby reducing production costs.

[0056] In a preferred embodiment of the present invention, by limiting the mass ratio of component A and component B, component A plays the role of dissociating the grid structure, while component B plays the role of stabilizing the structure and balancing the charge.

[0057] In a preferred embodiment of the present invention, the amount of activator affects the separation of other impurity element atoms and the size of the separated fragments in the silicon-oxygen grid system.

[0058] In a preferred embodiment of the present invention, the limiting of the calcination conditions enables other impurity element atoms in the silicon-oxygen grid system to react with the activator and be effectively separated.

[0059] In a preferred embodiment of the present invention, the water immersion conditions further passivate the separated substances and recover some of the alkali and possible alumina, thereby obtaining a highly efficient aluminum-iron ion solution under acid immersion conditions.

[0060] In a preferred embodiment of the present invention, the obtained de-adhesive aluminum-iron ion solution can be further processed according to different needs, such as preparing polyaluminum-iron water purification agents; the filtrate and the filter residue after solid-liquid separation can be further mixed with sodium hydroxide solution to extract silicon.

[0061] The present invention discloses the following technical effects:

[0062] This invention, through the rational combination and heat treatment of activators, fully activates aluminum and iron atoms, enabling efficient leaching under mild conditions during acid leaching. This improves the solid-liquid separation efficiency of the acid leaching solution. The resulting de-adhesive aluminum and iron ion solution can be processed to produce high-value-added products in demand by society, such as water purification agents. The remaining residue can be easily used to extract silicon and other useful elements, realizing the comprehensive industrial utilization of high-iron coal gangue and fly ash.

[0063] After processing with the technology of this invention, firstly, the viscosity of the aluminum-iron solution is significantly reduced after the formulation of the activator, making solid-liquid separation easier; secondly, during solid-liquid separation, the filter cloth does not adhere, extending the service life of the filter cloth and greatly reducing raw material consumption; thirdly, the solid-liquid separation time is greatly shortened, production efficiency is greatly improved, and production costs are significantly reduced; fourthly, the extraction efficiency is higher, with the extraction rates of aluminum and iron by acid leaching both exceeding 85%, creating better conditions for the subsequent separation and extraction of elements such as silicon; and fifthly, acid leaching accelerates the reaction rate, reducing the reaction time to 4-9 hours, which is significantly shorter than the traditional 9-12 hours, saving time and improving production efficiency and capacity.

[0064] The active agent formulation of this invention can activate the aluminum and iron activity in coal gangue and fly ash, significantly improve the de-adhesion of the solution, and greatly increase the dissolution rate of aluminum and iron in coal gangue and fly ash, thus creating favorable conditions for the high-value-added development and utilization of coal gangue and fly ash. Attached Figure Description

[0065] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0066] Figure 1 This is a flowchart illustrating the efficient extraction process of aluminum and iron from high-speed coal gangue and / or fly ash in an embodiment of the present invention.

[0067] Figure 2 This is the de-adhesive aluminum-iron ion solution obtained in Example 1 of the present invention.

[0068] Figure 3 The results show the stability performance comparison between the mixture of ferric chloride and aluminum chloride (left) and the polyaluminum-iron water purifier of Example 1 of the present invention (right). Detailed Implementation

[0069] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0070] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0071] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0072] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0073] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0074] The original composition of the coal gangue used in the embodiments of the present invention is shown in Table 1, and the original composition of the fly ash is shown in Table 2.

[0075] Table 1. Composition of Coal Gangue (wt%)

[0076]

[0077] Table 2. Composition of fly ash (wt%)

[0078]

[0079] In a specific embodiment of the present invention, solid-liquid separation after acid leaching is performed using a diaphragm filter press for thermal filtration. The diaphragm filter press uses filter cloth with strong acid and alkali resistance (commercially available product, filtration accuracy of 20μm, maximum air permeability of 500L / m²·s). After filtration, the filter cake has a water content of 15-30wt% and liquid suspended solids of less than 15mg / L. Filtration conditions: temperature of 85℃ and pressure of 5MPa.

[0080] The liquid suspended matter mentioned in this invention refers to the weight of solid floating matter per liter of solution, and the test method is the same as that for solid content determination. Since the suspended matter content is generally low, to reduce error, the sample volume should be appropriately increased (e.g., 200 mL), and filtered using quantitative filter paper. The calculation formula is as follows:

[0081] .

[0082] Where: W1——weight of filter paper (g);

[0083] W2——Total weight of filter paper and suspended matter after drying (g);

[0084] V – Volume of liquid taken (mL).

[0085] Example 1

[0086] Method of the present invention:

[0087] Sodium carbonate (component A) and sodium chloride (component B) (mass ratio of A:B 1:1) were mixed evenly with coal gangue (crushed and mixed, the amount of activator was 50% of the mass of the coal gangue). The mixture was then placed in a furnace and calcined at 900℃ for 60 minutes. After cooling, calcined sand was obtained. A water leaching solution was prepared by adding water at a solid-liquid ratio of 1 g:5 mL. After leaching at 80℃ for 120 minutes, the solution was filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 4 mol / L hydrochloric acid solution at 70℃ for 5 hours (solid-liquid ratio 1 g:5 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 12 mg / L and a viscosity of 21 Pa·s (actual sample as shown). Figure 2 The filter cake (the filter residue obtained by solid-liquid separation of acid leaching solution) has a water content of 18 wt%. Repeated experiments showed that after 300 uses, the surface adhesive substances of the filter cloth used for solid-liquid separation after acid leaching were negligible, and the air permeability was 335 L / m²·s.

[0088] Traditional technical methods:

[0089] Coal gangue was leached in 4 mol / L hydrochloric acid solution at 70℃ for 5 h (solid-liquid ratio 1 g: 5 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method described in this invention, yielding an aluminum-iron ion solution. The results showed that the liquid suspended solids in the obtained aluminum-iron ion solution were 5 mg / L, the viscosity was 96 Pa·s, and the water content of the filter cake was 33 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.5 mm and an air permeability of 224 L / m²·s.

[0090] Example 2

[0091] Potassium carbonate (component A) and sodium chloride (component B) (mass ratio of A:B 2:1) were mixed evenly with coal gangue (crushed and mixed, the amount of activator was 16.7% of the mass of the coal gangue). The mixture was then placed in a furnace and calcined at 700℃ for 90 min. After cooling, calcined sand was obtained. The calcined sand was added to water at a solid-liquid ratio of 1 g:4 mL to prepare a water leaching solution. After leaching at 60℃ for 100 min, the solution was filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 6 mol / L hydrochloric acid solution at 90℃ for 7 h (solid-liquid ratio 1 g:4 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 11 mg / L, a viscosity of 24 Pa·s, and a filter cake water content of 21 wt%. Repeated experiments revealed that after acid immersion and 300 uses, the surface adhesive substances of the filter cloth used for solid-liquid separation were negligible, and the air permeability was 342 L / m²·s.

[0092] Traditional technical methods:

[0093] Coal gangue was leached in 6 mol / L hydrochloric acid solution at 90℃ for 7 h (solid-liquid ratio 1 g: 4 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method of this invention, yielding an aluminum-iron ion solution. The results showed that the liquid suspended solids in the obtained aluminum-iron ion solution were 6 mg / L, the viscosity was 102 Pa·s, and the filter cake water content was 35 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive material thickness of 0.6 mm and an air permeability of 205 L / m²·s.

[0094] Example 3

[0095] Sodium sulfate (component A) and potassium chloride (component B) (mass ratio of A:B 6:1) were mixed evenly with coal gangue (crushed and mixed, the amount of activator was 10% of the mass of the coal gangue). The mixture was then placed in a furnace and calcined at 800℃ for 50 min. After cooling, calcined sand was obtained. The calcined sand was added to water at a solid-liquid ratio of 1 g:3 mL to prepare a water leaching solution. After leaching at 50℃ for 80 min, the solution was filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 7 mol / L hydrochloric acid solution at 80℃ for 4 h (solid-liquid ratio 1 g:3 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 16 mg / L, a viscosity of 35 Pa·s, and a filter cake water content of 19 wt%. Repeated experiments showed that after 300 uses of the filter cloth for solid-liquid separation following acid leaching, the surface adhesive substances were negligible, and the air permeability was 321 L / m²·s.

[0096] Traditional technical methods:

[0097] Coal gangue was leached in 7 mol / L hydrochloric acid solution at 80℃ for 4 hours (solid-liquid ratio 1 g: 3 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method described in this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 8 mg / L aluminum ion, had a viscosity of 112 Pa·s, and a filter cake water content of 31 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive material thickness of 0.5 mm and an air permeability of 218 L / m²·s.

[0098] Example 4

[0099] Potassium sulfate (group A) and sodium chloride (group B) (mass ratio of A:B:1) were mixed evenly with coal gangue (crushed and mixed, the amount of activator was 2% of the mass of the coal gangue). The mixture was then placed in a furnace and calcined at 600℃ for 120 min. After cooling, calcined sand was obtained. The calcined sand was added to water at a solid-liquid ratio of 1 g:3 mL to prepare a water leaching solution. After leaching at 90℃ for 60 min, the solution was filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 5 mol / L hydrochloric acid solution at 80℃ for 9 h (solid-liquid ratio of 1 g:3 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 15 mg / L, a viscosity of 52 Pa·s, and a filter cake water content of 24 wt%. Repeated experiments showed that after 300 uses of the filter cloth for solid-liquid separation following acid leaching, the surface adhesive substances were negligible, and the air permeability was 356 L / m²·s.

[0100] Traditional technical methods:

[0101] Coal gangue was leached in 5 mol / L hydrochloric acid solution at 80℃ for 9 h (solid-liquid ratio 1 g: 3 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method of this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 9 mg / L of suspended solids, had a viscosity of 122 Pa·s, and a filter cake water content of 36 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.5 mm and an air permeability of 220 L / m²·s.

[0102] Example 5

[0103] Sodium hydroxide (component A) and sodium chloride (component B, mass ratio 1:1) were mixed evenly with coal gangue at a mass ratio of 1% (crushed and mixed). The mixture was then placed in a furnace and calcined at 700℃ for 80 minutes. After cooling, calcined sand was obtained. A water leaching solution was prepared by adding water at a solid-liquid ratio of 1g:6mL to the calcined sand. After leaching at 60℃ for 80 minutes, the solution was filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 8mol / L hydrochloric acid solution at 80℃ for 9 hours (solid-liquid ratio 1g:6mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 13 mg / L, a viscosity of 55 Pa·s, and a filter cake water content of 26wt%. Repeated experiments showed that after 300 uses of the filter cloth for solid-liquid separation following acid leaching, the surface adhesive substances were negligible, and the air permeability was 296 L / m²·s.

[0104] Traditional technical methods:

[0105] Coal gangue was leached in 8 mol / L hydrochloric acid solution at 80℃ for 9 h (solid-liquid ratio 1 g: 6 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method described in this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 5 mg / L of suspended solids, had a viscosity of 131 Pa·s, and a filter cake water content of 38 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.7 mm and an air permeability of 198 L / m²·s.

[0106] Example 6

[0107] Potassium hydroxide (component A) and potassium chloride (component B, mass ratio 1:1) were mixed with coal gangue and fly ash (mass ratio 1:1) at a mass ratio of 1.7% (crushed and mixed). The mixture was then placed in a furnace and calcined at 700℃ for 80 min. After cooling, calcined sand was obtained. A water leaching solution was prepared by adding water at a solid-liquid ratio of 1 g: 4 mL. The solution was then leached at 90℃ for 70 min, followed by filtration to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 6 mol / L hydrochloric acid solution at 80℃ for 6 h (solid-liquid ratio 1 g: 4 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 14 mg / L, a viscosity of 52 Pa·s, and a filter cake water content of 27 wt%. After 300 uses, the surface adhesive substances on the filter cloth were negligible, and the air permeability was 288 L / m²·s.

[0108] Traditional technical methods:

[0109] A 6 mol / L hydrochloric acid solution was added and the mixture was acid-leached at 80°C for 6 hours (solid-liquid ratio 1 g: 4 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method of this invention, yielding an aluminum-iron ion solution. The results showed that the liquid suspended solids in the obtained aluminum-iron ion solution were 4 mg / L, the viscosity was 135 Pa·s, and the water content of the filter cake was 37 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.6 mm and an air permeability of 206 L / m²·s.

[0110] Example 7

[0111] Potassium hydroxide (component A) and sodium chloride (component B, mass ratio 2:1) were mixed with coal gangue and fly ash (mass ratio 2:1) at a mass ratio of 2.5% (crushed and mixed). The mixture was then placed in a furnace and calcined at 600℃ for 70 min. After cooling, calcined sand was obtained. A water immersion solution was prepared by adding water at a solid-liquid ratio of 1 g: 3 mL. The solution was then immersed at 90℃ for 100 min and filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 6 mol / L hydrochloric acid solution at 80℃ for 8 h (solid-liquid ratio 1 g: 3 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 13 mg / L, a viscosity of 49 Pa·s, and a filter cake water content of 25 wt%. After 300 uses, the surface adhesive substances on the filter cloth were negligible, and the air permeability was 302 L / m²·s.

[0112] Traditional technical methods:

[0113] Coal gangue and fly ash (mass ratio 2:1) were added to a 6 mol / L hydrochloric acid solution and leached at 80℃ for 8 hours (solid-liquid ratio 1 g: 3 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method of this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 4 mg / L of suspended solids, had a viscosity of 135 Pa·s, and a filter cake moisture content of 35 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.6 mm and an air permeability of 208 L / m²·s.

[0114] Example 8

[0115] Potassium sulfate (component A) and potassium fluoride (component B) in a mass ratio of 2:1 were mixed with coal gangue and fly ash (combustion ratio 4:1) at a mass ratio of 5% (crushed and mixed). The mixture was then placed in a furnace and calcined at 600℃ for 50 minutes. After cooling, calcined sand was obtained. A water leaching solution was prepared by adding water at a solid-liquid ratio of 1g:3mL to the calcined sand. The solution was then leached at 90℃ for 90 minutes and filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 5mol / L hydrochloric acid solution at 60℃ for 6 hours (solid-liquid ratio 1g:3mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 12 mg / L, a viscosity of 55 Pa·s, and a filter cake water content of 28wt%. After 300 uses, the surface adhesive substances on the filter cloth were negligible, and the air permeability was 310 L / m²·s.

[0116] Traditional technical methods:

[0117] Coal gangue and fly ash (mass ratio 4:1) were added to a 5 mol / L hydrochloric acid solution and acid-leached at 60℃ for 6 h (solid-liquid ratio 1 g: 3 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method of this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 7 mg / L of suspended solids, had a viscosity of 123 Pa·s, and a filter cake moisture content of 34 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.5 mm and an air permeability of 212 L / m²·s.

[0118] Example 9

[0119] Sodium carbonate (component A) and potassium fluoride (component B) (mass ratio 3:1) were mixed evenly with coal gangue at a mass ratio of 10% (crushed and mixed). The mixture was then placed in a furnace and calcined at 700℃ for 70 min. After cooling, calcined sand was obtained. A water leaching solution was prepared by adding water at a solid-liquid ratio of 1 g: 6 mL. The solution was then leached at 90℃ for 120 min, followed by filtration to obtain filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 3 mol / L hydrochloric acid solution at 80℃ for 7 h (solid-liquid ratio 1 g: 6 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 13 mg / L, a viscosity of 47 Pa·s, and a filter cake water content of 24 wt%. After 300 uses, the surface adhesive substances on the filter cloth were negligible, and the air permeability was 307 L / m²·s.

[0120] Traditional technical methods:

[0121] Coal gangue was leached in 3 mol / L hydrochloric acid solution at 80℃ for 7 h (solid-liquid ratio 1 g: 6 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method described in this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 9 mg / L of suspended solids, had a viscosity of 117 Pa·s, and a filter cake water content of 32 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.5 mm and an air permeability of 218 L / m²·s.

[0122] Example 10

[0123] Sodium sulfate (component A) and sodium chloride (component B) (mass ratio 3:1) were mixed with coal gangue and fly ash (mass ratio 1:2) at a mass ratio of 5% (crushed and mixed). The mixture was then placed in a furnace and calcined at 800℃ for 80 min. After cooling, calcined sand was obtained. A water immersion solution was prepared by adding water at a solid-liquid ratio of 1 g:3 mL. The solution was then immersed at 90℃ for 90 min and filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 6 mol / L hydrochloric acid solution at 60℃ for 9 h (solid-liquid ratio 1 g:3 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 14 mg / L, a viscosity of 52 Pa·s, and a filter cake water content of 25 wt%. After 300 uses, the surface adhesive substances on the filter cloth were negligible, and the air permeability was 311 L / m²·s.

[0124] Traditional technical methods:

[0125] Coal gangue and fly ash (mass ratio 1:2) were added to a 6 mol / L hydrochloric acid solution and acid-leached at 60℃ for 9 h (solid-liquid ratio 1 g: 3 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method of this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 6 mg / L of suspended solids, had a viscosity of 123 Pa·s, and a filter cake moisture content of 35 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.6 mm and an air permeability of 213 L / m²·s.

[0126] Example 11

[0127] Potassium hydroxide (group A) and sodium chloride (group B) (mass ratio 2:1) were mixed with coal gangue and fly ash (mass ratio 1:3) at a mass ratio of 1:25 (crushed and mixed). The mixture was then placed in a furnace and calcined at 800℃ for 60 minutes. After cooling, calcined sand was obtained. A water immersion solution was prepared by adding water at a solid-liquid ratio of 1 g:3 mL. The solution was then immersed at 90℃ for 80 minutes and filtered to obtain a filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 8 mol / L hydrochloric acid solution at 80℃ for 6 hours (solid-liquid ratio 1 g:3 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 15 mg / L, a viscosity of 57 Pa·s, and a filter cake water content of 26 wt%. After 300 uses, the surface adhesive substances on the filter cloth were negligible, and the air permeability was 316 L / m²·s.

[0128] Traditional technical methods:

[0129] Coal gangue and fly ash (mass ratio 1:3) were added to an 8 mol / L hydrochloric acid solution and acid-leached at 80℃ for 6 h (solid-liquid ratio 1 g: 3 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method of this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 5 mg / L of suspended solids, had a viscosity of 115 Pa·s, and a filter cake moisture content of 36 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.4 mm and an air permeability of 215 L / m²·s.

[0130] Example 12

[0131] Sodium carbonate (group A) and potassium chloride (group B) (mass ratio 1:1) were mixed with fly ash at a mass ratio of 2.5% (crushed and mixed). The mixture was then placed in a furnace and calcined at 800℃ for 80 minutes. After cooling, calcined sand was obtained. A water immersion solution was prepared by adding water at a solid-liquid ratio of 1 g: 4 mL. The solution was then immersed at 90℃ for 120 minutes and filtered to obtain filter cake and filtrate. The filter cake was washed, dried, and then acid-leached in 7 mol / L hydrochloric acid solution at 80℃ for 9 hours (solid-liquid ratio 1 g: 4 mL). Solid-liquid separation was then performed using a diaphragm filter press to obtain a de-adhesive aluminum-iron ion solution (aluminum-iron solution). The final aluminum-iron solution had a liquid suspended solids concentration of 15 mg / L, a viscosity of 59 Pa·s, and a filter cake water content of 28 wt%. After 300 uses, the surface adhesive substances on the filter cloth were negligible, and the air permeability was 295 L / m²·s.

[0132] Traditional technical methods:

[0133] Fly ash was added to a 7 mol / L hydrochloric acid solution and leached at 80℃ for 9 hours (solid-liquid ratio 1 g: 4 mL). Solid-liquid separation was then performed using a diaphragm filter press under the same conditions as the method described in this invention, yielding an aluminum-iron ion solution. The results showed that the obtained aluminum-iron ion solution contained 5 mg / L of suspended solids, had a viscosity of 133 Pa·s, and a filter cake moisture content of 37 wt%. Repeated experiments revealed that after 300 uses, the filter cloth used for solid-liquid separation after acid leaching had a surface adhesive layer thickness of 0.5 mm and an air permeability of 211 L / m²·s.

[0134] The parts not mentioned in Examples 2-12 above are the same as in Example 1.

[0135] Comparative Example 1

[0136] Same as Example 1, except that only sodium carbonate is used as the surfactant. The specific steps are as follows:

[0137] The results showed that, in this embodiment, because only sodium carbonate was used as the surfactant, the viscosity of the solution after acid leaching increased slightly to 65 Pa·s.

[0138] Comparative Example 2

[0139] Same as Example 1, except that the acid leaching conditions were adjusted to an acid concentration of 0.5 mol / L and a temperature of 30°C.

[0140] The results show that, in this embodiment, the aluminum-iron dissolution rate was significantly reduced due to the change in acid leaching conditions. The viscosity of the solution decreased accordingly after acid leaching.

[0141] Effect Verification 1

[0142] The aluminum and iron ion solutions obtained in the above embodiments and comparative examples were tested, the aluminum leaching rate and iron leaching rate were calculated, the solid-liquid separation time of the acid leaching solution was statistically analyzed, and the filter cloth replacement cycle of the method of the present invention and the conventional technology in Example 1 was also statistically analyzed. The results are shown in Table 3.

[0143] The aluminum leaching rate is calculated as follows:

[0144] ;

[0145] Iron leaching rate calculation method:

[0146] .

[0147] Solid-liquid separation time per unit area (m²) 2 Filter cloth filtration unit volume (m³) 3 The timer used for the acid leaching solution (to compare the effect of vacuum filtration).

[0148] Table 3. Leaching rate and solid-liquid separation effect of aluminum and iron leaching solution

[0149]

[0150] Based on the results in Table 1, it can be concluded that the method of the present invention can achieve efficient leaching of aluminum and iron, and significantly improve the solid-liquid separation efficiency of the acid leaching solution, providing effective support for the complete industrial application of coal gangue and fly ash.

[0151] The standard for replacing the filter cloth during hot filtration is an air permeability of less than 90 L / m²·s. The results show that in Example 1, the method of the present invention filters 282 cubic meters of acid leaching solution per square meter of filter cloth in one replacement cycle, while the traditional method filters 33 cubic meters of acid leaching solution per square meter of filter cloth in one replacement cycle.

[0152] Example 2 of effect verification

[0153] The composition of the acid leaching residue (filter cake) obtained in Examples 4, 6, and 8 was analyzed, and the results are shown in Table 4. According to Table 4, the iron and aluminum content in the residue after acid leaching is greatly reduced, while the silicon content increases to about 80%.

[0154] Table 4. Partial Composition of Acid Leaching Residue (wt%)

[0155]

[0156] Analysis of Table 4 shows that after acid leaching, the iron leaching rate is over 90% and the aluminum leaching rate is over 85%.

[0157] Example 3 of effect verification

[0158] The water purification agent prepared from the aluminum-iron ion solution obtained in the above embodiments was subjected to performance verification. The specific steps and results are as follows:

[0159] The mass percentage concentration of aluminum and iron ions in the aluminum-iron ion solution obtained from the statistical examples is shown in Table 5. The aluminum-iron molar ratio was adjusted to 1:1, the pH value was adjusted to 5, and after aging, it was used as a water purification agent. When using it, 5 mL of the water purification agent was diluted to an aluminum-iron ion concentration of 1 wt% to treat industrial wastewater (turbidity 877 NTU) from Huoshaopu Mine of Guizhou Panjiang Refined Coal Co., Ltd. The turbidity removal performance of the water purification agent was measured, as shown in Table 5.

[0160] Table 5 shows the aluminum and iron concentrations and turbidity removal rates of the water purification agents obtained in the examples.

[0161]

[0162] The stability of the obtained polyaluminum iron in the water purification agent was evaluated. Figure 3 The polyaluminum-iron water purifier on the right is from Example 1. It remains homogeneous and stable after 4 months, indicating that the polyaluminum-iron water purifier obtained in Example 1 has excellent stability. The mixture of ferric chloride and aluminum chloride on the left precipitates after being left for a period of time (one week). Figure 3The comparison shows that the polyaluminum iron water purifier obtained in Example 1 has excellent stability.

[0163] The filter residue and filtrate obtained in the above embodiments were recovered for silicon extraction. The specific steps and results are as follows:

[0164] The aqueous leaching filtrate is a solution containing a small amount of alkali. Sodium hydroxide is added to make its concentration 200-240 g / L, and it is mixed with the washed acid leaching residue. The mixture is stirred and reacted at 90℃ for 2 hours. After the reaction is completed, the solid and liquid are separated to obtain a sodium silicate solution. The sodium silicate dissolution rate is statistically analyzed, and the results are shown in Table 6. The obtained sodium silicate solution is used to prepare silicon-containing products such as silica. The residue contains 30-40% valuable metal compounds such as titanium, which can be further processed and used.

[0165] The formula for sodium silicate dissolution rate is as follows: Calculation of SiO2 concentration (titration method): Na2O (g / L) = 62 × 0.2 × V1,

[0166] SiO2 (g / L) = 30.04 × (0.2 × V2 - 0.5 × V3 - blank), where 0.2 is the molar concentration of hydrochloric acid (mol / L); 0.5 is the molar concentration of NaOH (mol / L); phenolphthalein is the indicator; V1 is the volume of hydrochloric acid titrated until phenolphthalein turns red (mL); V2 is the total volume of hydrochloric acid titrated after adding excess NaF and continuing titration until red, with an excess of 2 mL (mL); V3 is the volume of NaOH back titrated (mL).

[0167] Table 6. Silica leaching rate and titanium oxide content in acid leaching residue

[0168]

[0169] Based on the above results, it can be concluded that the de-adhesive aluminum-iron ion solution obtained in the embodiments of the present invention can be processed into high-value-added products such as water purification agents, which meet social needs. The remaining residue can be easily used to extract silicon and other useful elements, realizing the industrial comprehensive utilization of high-speed coal gangue and fly ash.

[0170] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for reducing the viscosity of acid leaching solution for coal gangue, characterized in that, The coal gangue is processed in the following steps: Calcinated sand is obtained by adding an activator to coal gangue, mixing and then calcining. The calcined sand was soaked in water and then filtered to obtain a solid and a filtrate. The solid was subjected to acid leaching followed by solid-liquid separation to obtain a de-adhesive aluminum-iron ion solution; The activator is a mixture of component A and component B; component A is potassium sulfate; component B is sodium chloride. The coal gangue contains more than 10 wt% iron oxide and more than 15 wt% aluminum oxide. The mass ratio of component A to component B is 5:1; The amount of the activator is 2% of the mass of the coal gangue; The roasting temperature is 500-900℃, and the time is 30-120 min; The solid-liquid separation method is thermal filtration using a diaphragm filter press; The thermal filtration temperature is 80-90℃, the pressure is 3.5-5MPa, and the filtration accuracy is 20-50μm. The filter cake after heat filtration has a water content of 15-30 wt% and a liquid suspended solids content of less than 15 mg / L. The water immersion conditions are as follows: solid-liquid ratio of 1g:(1-6)mL, temperature of 40-95℃, and time of 30-120min; The acid leaching conditions are as follows: solid-liquid ratio of 1g:(1-6)mL, temperature of 40-95℃, and time of 4-9h; The acid leaching uses hydrochloric acid or sulfuric acid with a concentration of 1-9 mol / L.

Images