What Are the Treatment Methods for Oxide Copper Ore Tailings?

Copper metal resources are widely used in industrial production and social life. With the continuous development of the times, the demand for them is increasing. However, since ore is a non-renewable resource, the redevelopment of copper mines is of great significance. Due to the backward technology of early mining, mineral processing and equipment manufacturing, some valuable copper metals were left in the tailings. Therefore, the reselection of this part of the tailings is the main channel to obtain the same resources. Let's take a look at the reselection processes of copper oxide tailings. At present, the commonly used reselection processes of oxide copper ore tailings include flotation and leaching.

01Flotation and re-selection process of oxide copper ore tailings

When the copper content in oxide copper ore tailings reaches about 0.5%-1%, the conventional flotation process may have a certain recovery value. Commonly used flotation methods are conventional flotation, chelating agent flotation and sulfide flotation.

1. Conventional flotation of oxide copper ore tailings

Conventional flotation is based on the differences in the physical and chemical properties of the mineral surface, and uses flotation agents to make copper oxide minerals selectively attach to bubbles, thereby achieving separation from gangue minerals. For the crushed ore, the slurry is adjusted to achieve a suitable acidity, and then fatty acid collectors (oleic acid, oxidized paraffin soap, etc.) are added to react with the surface of copper oxide minerals to make them hydrophobic. At the same time, a foaming agent (such as pine oil) is added to generate bubbles, which bring the hydrophobic copper oxide minerals to the surface of the pulp to form a foam layer, thereby achieving recovery. This flotation method is mostly suitable for tailings with fine particle size and relatively uniform particle size of copper oxide minerals.

2. Chelating agent flotation of oxide copper ore tailings

Chelating agent flotation uses chelating agents to form stable chelates with metal ions on the surface of copper oxide minerals, making the mineral surface hydrophobic, thereby improving the flotation effect. The general principle process is to add specific chelating agents (hydroxamic acids, xanthates, etc.) to the ore pulp after grinding, which can selectively combine with copper oxide minerals, and then add frothers for flotation. This type of flotation is mostly suitable for treating some difficult-to-select copper oxide tailings, especially those containing more siliceous gangue minerals.

3. Sulfidation flotation of oxide copper ore tailings

Sulfidation flotation is to first sulfidize the oxide copper ore minerals to form a layer of copper sulfide film on its surface, and then use the flotation agent for copper sulfide to float. The principle process is to add a quantitative sulfiding agent (such as sodium sulfide) to the ore after grinding, and then add xanthate collector and frother for flotation. This type of flotation is mostly suitable for oxidized copper minerals such as malachite and azurite. Especially when the floatability of oxidized copper minerals in tailings is poor, sulfide flotation can effectively improve its recovery rate.

02Leaching and reselection process of oxide copper ore tailings

When the copper content in the copper oxide ore is above 0.3%-0.5%, the leaching process is used for reselection, and the recovery efficiency is relatively high. The main reason is that the leaching process is relatively adaptable to low-grade ores, especially some copper oxide minerals with relatively active chemical properties and easy to react with leaching agents. Common leaching processes include acid leaching, ammonia leaching and biological leaching.

03Acid leaching method of oxide copper ore tailings

The acid leaching method uses acid to react with copper oxide minerals to dissolve copper into the solution, and then recover copper from the solution through subsequent treatment methods. The process is to mix the copper oxide tailings with acid solutions such as dilute sulfuric acid or hydrochloric acid, and react under certain temperature, stirring speed and other conditions. After the reaction is completed, solid-liquid separation is carried out to obtain a copper-containing leaching solution. The leaching solution is then extracted-electrodeposition or displacement to recover copper from it. This leaching method is mostly suitable for tailings with high copper oxide content and relatively low impurity content.

04Ammonia leaching of oxide copper ore tailings

The ammonia leaching method is that in an ammonia-ammonium salt solution, copper oxide minerals can dissolve to form copper-ammonia complexes, thereby achieving copper leaching. The process is to add copper oxide tailings to a solution containing ammonia and ammonium salts, and carry out leaching reaction under certain temperature, pressure and other conditions. After the reaction is completed, solid-liquid separation is carried out to obtain ammonia leaching solution containing copper. Copper is then recovered from the ammonia leaching solution by ammonia evaporation, extraction-electrodeposition, etc. This method is mostly suitable for treating tailings containing more copper carbonate minerals (such as malachite), and the ammonia leaching method has a better effect.

05Biological leaching method of oxide copper ore tailings

The biological leaching method uses the metabolism of microorganisms to oxidize the copper in copper oxide minerals and dissolve it into the solution. The process is to first cultivate and domesticate the microorganisms to adapt them to the environment of oxide copper ore tailings, and then inoculate the domesticated microorganisms into the leaching system containing copper oxide tailings, and carry out biological leaching under suitable temperature, pH value, ventilation conditions, etc. The metabolites (such as sulfuric acid, iron ions, etc.) produced by microorganisms during their growth process can react with copper oxide minerals to dissolve copper into the solution. After leaching is completed, solid-liquid separation is performed to recover copper from the solution. This method is mostly suitable for treating low-grade and difficult-to-treat copper oxide tailings, especially for copper oxide minerals containing a large amount of gangue minerals.

The above is an introduction to the process of reselection of oxide copper ore tailings. In actual ore dressing plants, due to the differences in the properties of oxidized copper tailings ores, it is necessary to select appropriate treatment methods or a combination of multiple methods based on the specific characteristics of the tailings (such as mineral composition, grade, particle size distribution, impurity content, etc.), combined with economic costs, environmental impacts and other factors. Therefore, it is recommended to conduct ore dressing test analysis and design a suitable oxidized tailings reselection process based on actual conditions.