A method for separating iron gallium from acid leaching solution of coal-based solid waste

Abstract

This invention discloses a method for simultaneously separating iron and gallium from acid leaching solutions of coal-based solid waste, belonging to the field of coal-based solid waste resource utilization technology. The method includes: adjusting the pH of the acid leaching solution of coal-based solid waste to obtain a pretreated leachate; subjecting the pretreated leachate to hydrothermal precipitation to obtain reaction products; and subsequently subjecting the reaction products to sedimentation treatment to obtain an aluminum-containing solution and gallium-rich iron slag. This invention achieves efficient separation of the impurity component iron and preliminary enrichment of the valuable component gallium from acid leaching solutions of coal-based solid waste simultaneously through simple hydrothermal precipitation without introducing any exogenous impurity ions. The process is simple, the operating conditions are mild, and it provides a stable and reliable technical path for the treatment of acid leaching solutions of coal-based solid waste.

Description

Technical Field

[0001] This invention belongs to the field of coal-based solid waste resource utilization technology, specifically relating to a method for separating iron gallium from acid leaching solution of coal-based solid waste. Background Technology

[0002] Coal-based solid waste mainly includes two categories: fly ash and coal gangue, which are generated throughout the entire process of coal mining, processing, and utilization. Coal gangue is a rock-like material that is associated with coal resources and is discharged in large quantities during underground mining and coal washing. Fly ash is a byproduct of coal combustion, mainly emitted by thermal power plants during production. This type of waste not only occupies a large amount of land resources but also causes significant pollution to the surrounding ecological environment. Relevant chemical tests show that coal contains more than 80 chemical elements. During combustion, only a small number of elements are released with the flue gas, while the vast majority of components are enriched and retained in fly ash. Fly ash contains rare metal elements with high utilization value, such as germanium, gallium, uranium, and thorium. Therefore, if the high-value-added components in fly ash can be efficiently extracted and utilized, it can be transformed into a renewable resource with abundant sources, broad application prospects, and significant economic benefits.

[0003] Several technologies are currently being researched for gallium extraction from coal-based solid waste, but all have certain limitations. Patent CN120485551 A utilizes ammonium sulfate roasting activation and composite extractant extraction processes, combining coal gangue and bauxite waste to extract gallium, achieving excellent extraction efficiency. However, the process is complex, requiring sophisticated equipment and parameter control, and the extractant cost is high. Patent CN120060650 A separates aluminum, iron, and gallium from fly ash leachate through a three-stage stepwise extraction and multi-stage back-extraction process. The extractant can be recycled, but the overall processing is cumbersome, requiring multiple extractants and strong acids, resulting in a complex system and high reagent costs. Patent CN 117737470 A uses polyurethane foam adsorption for gallium extraction, requiring no organic solvents and operating at room temperature. It is simple to operate and allows for flexible adjustment of process parameters. However, the NaF additive used in this process easily generates difficult-to-treat fluorine-containing waste liquid, causing secondary pollution and equipment corrosion, and requires strict precision in additive dosing.

[0004] Therefore, there is an urgent need to invent a method for the simultaneous separation of iron and gallium from acid leaching solutions of coal-based solid waste to solve the above problems. This method provides a new and feasible solution for the purification and separation of acid leaching solutions of coal-based solid waste, offers some support for the efficient recycling and utilization of gallium resources in my country, and has good application prospects. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a method for the simultaneous separation of iron and gallium from acid leaching solutions of coal-based solid waste. This method features high iron and gallium precipitation rates and strong selectivity, offering a new and feasible solution for the purification and separation of acid leaching solutions of coal-based solid waste. It also provides support for the efficient recycling and utilization of gallium resources in my country and has promising application prospects.

[0006] A method for simultaneous separation of iron and gallium from acid leaching solution of coal-based solid waste, the method comprising the following steps: (1) Adjust the pH of the acid leaching solution of coal-based solid waste to 0.5-2.5 to obtain the pretreated leachate; (2) The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation to obtain the reaction product; (3) The reaction products obtained in step (2) are separated by sedimentation to obtain an aluminum-containing solution and a gallium-containing iron slag.

[0007] Furthermore, the acid leaching solution processed in step (1) includes sulfuric acid leaching solution or nitric acid leaching solution of coal gangue, fly ash, coal gasification slag, and coal-based solid waste.

[0008] Furthermore, the acid leaching solution processed in step (1) contains 10-50 g / L aluminum, 1-5 g / L iron, and 50-300 mg / L gallium.

[0009] Furthermore, the pH adjustment in step (1) is performed using aluminum hydroxide.

[0010] Furthermore, in step (2), the temperature of hydrothermal precipitation is 140-200 ℃, the time is 20-100 min, and the rotation speed is 100-400 r / min.

[0011] Beneficial effects

[0012] (1) This method achieves simultaneous separation of iron and gallium through hydrothermal precipitation, efficiently realizes the separation and enrichment of target metals, and has excellent performance in key indicators, providing a stable and reliable technical path for the separation of valuable metals in acid leaching solutions of coal-based solid waste.

[0013] (2) The method described in this invention does not add any reagents or introduce any exogenous impurity ions, effectively avoiding pollution and residues caused by chemical additives, while ensuring the purity of the system composition during the separation process, providing a green and clean technical approach for achieving efficient and synchronous separation of iron and gallium.

[0014] (3) The present invention has a simple and compact process flow design, no need for complicated pretreatment and posttreatment procedures, the overall operation is simple and easy to carry out, the conditions are mild and easy to control, the equipment requirements are low, and it can effectively simplify the separation and enrichment of iron, aluminum and gallium in coal-based solid waste acid leaching solution, greatly reduce the difficulty of process operation and production cost, and is suitable for industrial-scale production.

[0015] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0016] To make the technical problem to be solved, the technical solution and advantages of the present invention clearer, specific embodiments will be described in detail below. Unless otherwise specified, all materials used in the following experiments were purchased from the market.

[0017] A method for separating iron gallium from acid leaching solution of coal-based solid waste includes the following steps: (1) pH adjustment: pH adjustment of the acid leaching solution of coal-based solid waste was carried out to obtain pretreated leachate; Acid leaching solutions for coal-based solid waste include sulfuric acid leaching solutions or nitric acid leaching solutions for coal gangue, fly ash, coal gasification slag, and other coal-based solid waste.

[0018] (2) Hydrothermal precipitation: The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation to obtain the reaction product; (3) Sedimentation separation: The reaction products obtained in step (2) are separated by sedimentation to obtain an aluminum-containing solution and gallium-rich iron slag.

[0019] To more clearly demonstrate the technical solution and its effects provided by the present invention, the following detailed description of a method for simultaneous separation of iron and gallium from coal-based solid waste acid leaching solution is provided by the present invention with specific embodiments.

[0020] Example 1 A method for separating iron gallium from acid leaching solution of coal-based solid waste includes the following steps: (1) pH adjustment: Add aluminum hydroxide to the sulfuric acid leaching solution of coal gangue containing 10 g / L aluminum, 2 g / L iron and 100 mg / L gallium to adjust its pH value to 1.5, and obtain the pretreated leaching solution; (2) Hydrothermal precipitation: The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation. The temperature of hydrothermal precipitation is controlled at 140℃, the time is 80min, and the rotation speed is 200r / min to obtain the reaction product. (3) Sedimentation separation: After sedimentation for 8 hours, the reaction products obtained in step (2) yield an aluminum-containing solution and gallium-rich iron slag.

[0021] Example 2 A method for separating iron gallium from acid leaching solution of coal-based solid waste includes the following steps: (1) pH adjustment: Add aluminum hydroxide to the nitric acid leaching solution of coal gangue containing 30 g / L aluminum, 1 g / L iron and 200 mg / L gallium to adjust its pH value to 1.0, and obtain the pretreated leaching solution; (2) Hydrothermal precipitation: The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation. The temperature of hydrothermal precipitation is controlled at 150℃, the time is 20min, and the rotation speed is 300r / min to obtain the reaction product. (3) Sedimentation separation: After sedimentation for 6 hours, the reaction products obtained in step (2) yield an aluminum-containing solution and gallium-rich iron slag.

[0022] Example 3 A method for separating iron gallium from acid leaching solution of coal-based solid waste includes the following steps: (1) pH adjustment: Add aluminum hydroxide to the sulfuric acid leaching solution of fly ash containing 50 g / L aluminum, 3 g / L iron and 150 mg / L gallium to adjust its pH value to 2.0, and obtain the pretreated leaching solution; (2) Hydrothermal precipitation: The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation. The temperature of hydrothermal precipitation is controlled at 200℃, the time is 60min, and the rotation speed is 150r / min to obtain the reaction product. (3) Sedimentation separation: After sedimentation for 0.5 h, the reaction products obtained in step (2) are separated into aluminum-containing solution and gallium-rich iron slag.

[0023] Example 4 A method for separating iron gallium from acid leaching solution of coal-based solid waste includes the following steps: (1) pH adjustment: Add aluminum hydroxide to the fly ash nitric acid leaching solution containing 20 g / L aluminum, 4 g / L iron and 300 mg / L gallium to adjust its pH value to 0.5, and obtain the pretreated leaching solution; (2) Hydrothermal precipitation: The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation. The temperature of hydrothermal precipitation is controlled at 160℃, the time is 100min, and the rotation speed is 180r / min to obtain the reaction product. (3) Sedimentation separation: After sedimentation for 4 hours, the reaction products obtained in step (2) yield an aluminum-containing solution and gallium-rich iron slag.

[0024] Example 5 A method for separating iron gallium from acid leaching solution of coal-based solid waste includes the following steps: (1) pH adjustment: Add aluminum hydroxide to the sulfuric acid leaching solution of coal gasification slag containing 40 g / L aluminum, 2.5 g / L iron and 50 mg / L gallium to adjust its pH value to 2.5, and obtain the pretreated leaching solution; (2) Hydrothermal precipitation: The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation. The temperature of hydrothermal precipitation is controlled at 180℃, the time is 40min, and the rotation speed is 400r / min to obtain the reaction product. (3) Sedimentation separation: After sedimentation for 2 hours, the reaction products obtained in step (2) yield an aluminum-containing solution and gallium-rich iron slag.

[0025] Example 6 A method for separating iron gallium from acid leaching solution of coal-based solid waste includes the following steps: (1) pH adjustment: Add aluminum hydroxide to the nitric acid leaching solution of coal gasification slag containing 28 g / L aluminum, 5 g / L iron and 180 mg / L gallium to adjust its pH value to 0.8, and obtain the pretreated leaching solution; (2) Hydrothermal precipitation: The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation. The temperature of hydrothermal precipitation is controlled at 170℃, the time is 90min, and the rotation speed is 100r / min to obtain the reaction product. (3) Sedimentation separation: After sedimentation for 1 hour, the reaction products obtained in step (2) yield an aluminum-containing solution and gallium-rich iron slag.

[0026] This invention provides a method for separating iron and gallium from acid leaching solutions of coal-based solid waste, wherein the formula for calculating the iron / gallium precipitation ratio is as follows:

[0027] Examples 1-6 are partial embodiments of the present invention, and the iron / gallium precipitation rates of each example are shown in Table 1. The results show that the iron precipitation rate consistently remains above 90%, and the gallium precipitation rate consistently remains above 80%. Therefore, the present invention achieves efficient simultaneous separation of iron and gallium from coal-based solid waste.

[0028] Table 1 Iron / Gallium precipitation rates in each embodiment

[0029] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the hydrothermal precipitation temperature is 100°C. The results show that the gallium precipitation rate decreased to 47% and the iron precipitation rate decreased to 57%.

[0030] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that the aluminum concentration of the acid leaching solution is 60 g / L. The results show that the gallium precipitation rate decreased to 54% and the iron precipitation rate decreased to 74%.

[0031] Comparative Example 3 The difference between Comparative Example 3 and Example 4 is that the iron concentration of the acid leaching solution is 0.5 g / L. The results show that the gallium precipitation rate decreased to 52% and the iron precipitation rate decreased to 68%.

[0032] Comparative Example 4 The difference between Comparative Example 4 and Example 5 is that the gallium concentration in the acid leaching solution is 20 mg / L. The results show that the gallium precipitation rate decreased to 61% and the iron precipitation rate decreased to 83%.

[0033] Comparative Example 5 The difference between Comparative Example 5 and Example 6 is that the pH of the acid leaching solution is 0.3, and the results show that the gallium precipitation rate decreased to 44% and the iron precipitation rate decreased to 52%.

[0034] In summary, factors such as aluminum concentration, iron concentration, and hydrothermal temperature directly affect the separation efficiency of iron and gallium in coal-based solid waste acid leaching solutions. When the operation is not within the parameters set by the technical solution of this invention, the extraction effect of iron and gallium is not ideal. This application achieves efficient extraction of iron and gallium from coal-based solid waste by optimizing the pH and hydrothermal conditions of the acid leaching solution, providing a new implementation scheme for the purification and separation of coal-based solid waste acid leaching solutions.

[0035] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for separating iron-gallium from acid leaching solution of coal-based solid waste, characterized in that, The method includes the following steps: (1) Adjust the pH of the acid leaching solution of coal-based solid waste to 0.5-2.5 to obtain the pretreated leachate; (2) The pretreated leachate obtained in step (1) is subjected to hydrothermal precipitation to obtain the reaction product; (3) The reaction products obtained in step (2) are separated by sedimentation to obtain an aluminum-containing solution and a gallium-containing iron slag.

2. The method according to claim 1, characterized in that, The acid leaching solution processed in step (1) includes sulfuric acid leaching solution or nitric acid leaching solution of coal gangue, fly ash, coal gasification slag, and coal-based solid waste.

3. The method according to claim 1, characterized in that: The acid leaching solution processed in step (1) contains 10-50 g / L aluminum, 1-5 g / L iron, and 50-300 mg / L gallium.

4. The method according to claim 1, characterized in that, The pH adjustment in step (1) is performed using aluminum hydroxide.

5. The method according to claim 1, characterized in that, In step (2), the temperature of hydrothermal precipitation is 140-200℃, the time is 20-100min, and the rotation speed is 100-400r / min.

Images