Recycling and processing technologies for used dry batteries

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Technologies for the recycling and processing of used dry batteries. Dry batteries are primarily made up of a zinc casing, electrolytic manganese powder, ammonium chloride, graphite rods, carbon powder, and copper caps. In used dry batteries, only a small portion of the zinc casing is consumed; electrolytic manganese plays only a minor role in oxidation processes, while materials such as carbon powder, graphite rods, and copper caps remain intact. By processing and refining these materials, they can be reused. Recycling used dry batteries turns waste into valuable resources, which is of great significance in terms of cost savings. ?The collected used dry batteries are smashed to separate the zinc casing and the iron bottom of the battery; the copper caps and graphite rods are then removed. The remaining black filler (carbon powder) consists mainly of manganese dioxide and ammonium chloride. The recycling methods are as follows:?1. Zinc plates: The chemical properties and uses of zinc ； Zinc, Zn, has an atomic number of 30 and an atomic weight of 65.38. It is a bluish-white metal with a density of 7.14, a melting point of 419.4°C, and a boiling point of 709°C. Its valence is 2. Zinc is stable in air; it releases oxygen when reacting with acids or bases. It is used in electroplating zinc, as well as in the production of brass, manganese bronze, galvanized steel, and dry batteries. Zinc powder serves as an important reducing agent in the organic synthesis industry. ? Recycling method: First, wash the stripped zinc shells clean using detergent and water, then place them in a graphite crucible intended for refining (the size of the crucible can be determined based on the amount of zinc). Cover the crucible with a layer of asbestos cloth, and place it over a vigorously burning coal fire to melt the zinc (the temperature should be maintained between the melting and boiling points of zinc; if possible, a small household blower can be used to intensify the heat). Once the zinc is completely melted, any impurities floating on the surface can be removed. Then, pour the molten zinc into an iron mold to allow it to solidify and take shape (the resulting zinc ingots can be sold). After it has cooled completely, it can be placed back in the crucible for melting once more; this time, the molten zinc should be poured onto an iron plate, where it will solidify to form zinc sheets. II. Copper sheets: Chemical properties and functions of copper sheets ； Copper has an atomic number of 29 and an atomic weight of 63.546. It is a red-colored, shiny metal that is highly malleable. Its density is 892, its melting point is 1083°C, and its boiling point is 2595°C. It can exhibit valences of 1 and 2. It remains relatively stable in dry air, but its surface tends to develop copper oxide in humid air containing carbon dioxide. Copper dissolves in nitric acid and hot sulfuric acid, and is slightly soluble in hydrochloric acid. It is easily corroded by alkalis. It possesses excellent electrical and thermal conductivity, and is used in the production of copper wires and sheets, electrodes, electroforming plates, switches, as well as in various chemical applications. Recycling method: Remove the copper caps from the used dry batteries, flatten them one by one, and then place them in dilute sulfuric acid at a ratio of 1:1 (the concentration of sulfuric acid is usually 60%-70%). Dilute sulfuric acid is prepared by mixing equal amounts of sulfuric acid and water; when adding water, it should be poured slowly into the sulfuric acid while stirring continuously with a glass rod. Under no circumstances should water be poured into sulfuric acid to prevent violent splashing and potential accidents. Place the dilute sulfuric acid in an acid-resistant container, heat it over a flame, and then remove the copper sheets after they have boiled – resulting in copper sheets of a reddish-brown color. III. Graphite rods: The chemical properties and functions of graphite ； Graphite C, a crystalline form of carbon, ranges in color from iron black to molten steel gray; it is soft with a slippery texture and a metallic luster. It belongs to the hexagonal crystal system and appears in leaf-like, flaky, or lump-shaped forms. Its specific gravity is 2.25 and its hardness is 1. It conducts electricity, has inert chemical properties, and is resistant to corrosion by acids and alkalis. However, it can be oxidized by strong oxidizing agents to form organic acids. It burns vigorously in air or oxygen, producing carbon dioxide. It is used as an anti-friction material and lubricant, as well as in the manufacture of crucibles, electrodes, and dry batteries. The recycling method involves breaking open the waste batteries to extract the graphite rods, which can be cleaned with water and then used as electrodes. IV. Ammonium chloride: Chemical properties and functions of ammonium chloride ； Ammonium chloride NH4Cl, commonly known as nitre, is a white crystal with a specific gravity of 1.5; it sublimes at 117° and 350°C. It is hygroscopic, soluble in water and glycerin, and slightly soluble in ethanol ； It is used for metal welding, electroplating, tanning, and the production of dry batteries; in agriculture it serves as a chlorine fertilizer, and in medicine it is used to relieve phlegm. Recycling method: Place the black filler (carbon powder) from used dry batteries into a ceramic container, add water and stir. After the ink-like substance settles, pour off the upper layer of solution, filter it, and place the filtrate in a container. Heat it to cause evaporation; crystals will form. Stop heating once this occurs, and the crystals will be obtained after cooling.