Graphite flotation purification involves separating impurities, including organic carbon elements, from graphite ore to obtain higher-purity graphite products. Below is a common graphite flotation purification process and how flotation is used to remove carbon elements from graphite.
Crushing and Grinding: Initially, raw graphite ore is subjected to crushing and grinding to refine it into suitable particle sizes, providing better conditions for subsequent flotation.
Flotation Separation: Graphite flotation typically employs sodium hydroxide (NaOH) as a regulator to float graphite into the froth. During flotation, bubbles created through agitation carry graphite particles to the liquid surface, where they are removed with the froth. However, organic carbon is often resistant to flotation, causing it to stay at the bottom or be excluded.
De-sliming: After flotation, the graphite slurry may still contain some impurities such as clay and other particulates. By sedimentation or mechanical dewatering, some of these impurities can be removed to further purify the slurry.
Alkali Washing: Alkali washing is a common method involving treating the graphite slurry with an alkaline solution (such as sodium hydroxide) to convert organic carbon into soluble carbonate, removing it from the slurry. Solid and liquid separation steps, such as filtration, are then used to obtain a purified slurry.
Re-flotation: If the removal of organic carbon is insufficient, re-flotation can be considered. Re-flotation involves subjecting the alkali-treated slurry to another flotation process, using appropriate reagents and conditions to prevent the flotation of organic carbon, further enhancing graphite purity.
Drying and Sintering: The purified graphite slurry is dried to obtain graphite powder or particles. Subsequently, these graphite particles can undergo sintering processes to achieve the desired physical and chemical properties in the graphite product.
In summary, the graphite flotation purification process involves multiple steps, primarily utilizing flotation and alkali washing to remove organic carbon and other impurities from the graphite. Specific parameters and operating conditions for these steps should be adjusted according to the characteristics and requirements of the graphite ore to ensure the effectiveness and quality of the purification process.
In graphite flotation, carbon elements usually refer to organic carbon present in the graphite ore, such as organics and humic substances. Since these organic carbons can affect flotation efficiency and product quality, their removal is necessary during the flotation process. Here are some commonly used methods to remove carbon elements from graphite ore:
Alkali Leaching: This method involves immersing and stirring the graphite ore in an alkaline solution (such as sodium hydroxide or potassium hydroxide) to convert the organic carbon into soluble carbonate, effectively dissolving it from the graphite ore. Subsequent steps can be used to remove carbonate from the solution.
Acid Leaching: Acid leaching involves soaking the graphite ore in an acidic solution, causing the organic carbon to undergo acid decomposition and convert into soluble acidic products, which can be separated from the ore. Commonly used acids include sulfuric acid and hydrochloric acid.
Thermal Decomposition: Thermal decomposition involves subjecting the graphite ore to high temperatures, causing the organic carbon to decompose into gases or volatile products, thereby removing it from the ore. This method is suitable for ores with higher organic carbon content.
Oxidation: Oxidation involves exposing the graphite ore to an oxidative atmosphere, causing the organic carbon to undergo oxidation and convert into gases or oxidized products, which can then be removed from the ore.
Comprehensive Beneficiation: In comprehensive graphite beneficiation processes, a series of flotation stages, de-sliming, and other steps can be used to effectively remove most of the organic carbon from the flotation slurry.
It's important to note that selecting the appropriate method to remove carbon depends on the specific properties of the graphite ore, organic carbon content, and process requirements. Different methods may be suitable for different ore types and engineering needs. In practical applications, the choice of carbon removal method should be based on ore testing results and ore characteristics to ensure the effectiveness and quality of graphite flotation.
