A resource utilization method for preparing aluminum sulfate using hydrogen peroxide- containing waste sulfuric acid and aluminum dross ash.

Abstract

This invention relates to the development of a recycling process using waste sulfuric acid containing hydrogen peroxide and aluminum slag as resources. Specifically, it describes a method for preparing recycled aluminum sulfate using these materials. The main process involves using the waste sulfuric acid containing hydrogen peroxide as a metal leaching solution to leach the target metallic aluminum from the aluminum slag. The hydrogen peroxide in the waste sulfuric acid oxidizes the main impurity, iron ions, to ferric ions, facilitating subsequent purification of the aluminum sulfate solution. This reduces the need for additional reagents, optimizes process steps, and lowers production costs. Hydrogen peroxide also acts as an leaching accelerator. The leaching solution, after filtration, yields a pure aluminum sulfate aqueous solution, which is then crystallized to obtain the aluminum sulfate product. This invention not only effectively avoids resource waste but also achieves the goals of a circular economy and energy conservation and carbon reduction.

Claims

1. A method for resource recycling of waste sulfuric acid containing hydrogen peroxide and aluminum slag ash, characterized by the following steps: (1) mixing aluminum slag ash with water to form a mixture of aluminum slag ash and water; (2) slowly adding waste sulfuric acid containing hydrogen peroxide to the mixture of aluminum slag ash and water; (3) heating at 50 to 90°C for 1 to 3 hours, stirring slowly during heating; the solid-liquid ratio of aluminum slag ash to waste sulfuric acid is between 0.1 and 10 g / 100 ml; the sulfuric acid concentration is between 0.5 and 3 M; the hydrogen peroxide concentration is between 0.1 and 1 M; (4) performing solid-liquid separation after the reaction. (5) A crude aluminum sulfate filtrate rich in aluminum and iron and an insoluble filter residue can be obtained; (6) An alkaline substance is slowly added to the crude aluminum sulfate filtrate and the pH value is adjusted to between 3 and 5. After stirring slowly and standing for 1 hour, the filtrate is filtered to obtain a pure aluminum sulfate filtrate rich in aluminum and an iron-containing precipitate. The alkaline substance shall contain at least a solid or liquid sodium hydroxide or potassium hydroxide; (7) The pure aluminum sulfate filtrate is heated to dehydrate and crystallize to precipitate the crystal product. The reaction conditions are a heating rate of 1 to 3 °C / min and a reaction temperature of 80 to 95 °C. After filtration, washing and drying, the aluminum sulfate product is obtained.

2. The method for resource recycling of waste sulfuric acid containing hydrogen peroxide and aluminum slag ash as described in claim 1, wherein, Waste sulfuric acid containing hydrogen peroxide is waste sulfuric acid from cleaning processes in the semiconductor, optoelectronic, and metal surface treatment industries. The waste sulfuric acid has a sulfuric acid weight percentage concentration of 5% to 60% and a hydrogen peroxide weight percentage concentration of 1% to 5%.

3. The method for resource recycling of waste sulfuric acid containing hydrogen peroxide and aluminum slag ash as described in claim 1, wherein, Aluminum slag ash is aluminum slag ash produced in the aluminum smelting industry, with an aluminum weight percentage concentration of 1 to 50%.

4. The method for resource recycling of waste sulfuric acid containing hydrogen peroxide and aluminum slag ash as described in claim 1, wherein, Hydrogen peroxide in waste sulfuric acid can be used as an oxidant and an aluminum impregnation promoter. Without the need to add other oxidants, the aluminum impregnation and iron oxidation steps can be carried out simultaneously. In addition to effectively increasing the aluminum impregnation efficiency, it also oxidizes the ferrous ions in the impregnation solution to ferric ions, which is beneficial for the subsequent purification process.

5. The method for resource recycling of waste sulfuric acid containing hydrogen peroxide and aluminum slag ash as described in claim 1, wherein, The insoluble filter residue is mainly composed of compounds of silicon, magnesium and calcium.

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