Calculation of the flotation rate constant of chalcopyrite particles in an ore

Influence and Mechanism of Solid-Phase Particle Factors on Oil-Solid Separation of Oily Sludge Treated by Flotation Method

The solid phase composition in oily sludge (OS) is a key factor affecting the oil-solid separation of OS. In this paper, the effects and mechanisms of solid-phase particle factors on the oil content of residue phase were investigated in order to improve the oil-solid separation efficiency. Flotation experiments were carried out on single-size sand and mixed-size sand OS consisting of three particle sizes at room temperature without adding flotation reagents. The effects of different-size particles as solid phase composition of OS and flotation parameter settings such as flotation temperature (Tp), flotation time (Tt), impeller speed (Rs) and liquid-solid ratio (L/OS) on the oil-solid separation efficiency were investigated. The experimental results showed that the oil content of residue phase decreased with the increasing of solid-phase particle size for single-size sand OS, and the optimal flotation conditions were Tp of 50 °C, Tt of 25 min, Rs of 1450 r/min and L/OS of 12:1. The oil-solid separation was more pronounced for mixed-size sand OS with a complex particle composition, while different particle compositions of the solid phase in OS promoted oil-solid separation. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR) characterisation of OS before and after flotation confirmed the relative advantage of coarse particle OS in the oil-solid separation process. The classical first-order model was well fitted to the flotation kinetic process of single-size sand and mixed-size sand OS. The response surface methodology (RSM) method was used to determine the Rs as the main control factor of the flotation process, and the oil content of residue phase in mixed-size sand OS was optimised to 2.63%. This study provides important process parameters and theoretical basis for the efficient treatment of OS.

The Challenges and Prospects of Recovering Fine Copper Sulfides from Tailings Using Different Flotation Techniques: A Review

Flotation is a common mineral processing method used to upgrade copper sulfide ores; in this method, copper sulfide mineral particles are concentrated in froth, and associated gangue minerals are separated as tailings. However, a significant amount of copper is lost into tailings during the processing; therefore, tailings can be considered secondary resources or future deposits of copper. Particle–bubble collision efficiency and particle–bubble aggregate stability determines the recovery of target particles; this attachment efficiency plays a vital role in the selectivity process. The presence of fine particles in the flotation circuit is because of excessive grinding, which is to achieve a higher degree of liberation. Complex sulfide ores of markedly low grade further necessitate excessive grinding to achieve the maximum degree of liberation. In the flotation process, fine particles due to their small mass and momentum are unable to collide with rising bubbles, and their rate of flotation is very slow, further lowering the recovery of target minerals. This collision efficiency mainly depends on the particle–bubble size ratio and the concentration of particles present in the pulp. To overcome this problem and to maintain a favorable particle–bubble size ratio, different techniques have been employed by researchers to enhance particle–bubble collision efficiency either by increasing particle size or by decreasing bubble size. In this article, the mechanism of tailing loss is discussed in detail. In addition, flotation methods for fine particles recovery such as microbubble flotation, column flotation, nanobubble flotation, polymer flocculation, shear flocculation, oil agglomeration, and carrier flotation are reviewed, and their applications and limitations are discussed in detail.

Regionalized Life Cycle Inventories of Global Sulfidic Copper Tailings

Worldwide, an issue of copper production is the generation of mine waste with varying characteristics. This waste can pollute natural environments, and in particular, the heavy metal emissions of the tailings may pose long-term consequences. Currently, life cycle assessments of mine tailings are hampered by both limited data availability in the metal production value chain and lack of appropriate methodologies. We collect data from 431 active copper mine sites using a combination of information available from the market research and technical handbooks to develop site-specific life cycle inventories for disposal of tailings. The approach considers the influences of copper ore composition and local hydrology for dynamically estimating leached metals of tailings at each site. The analysis reveals that together, copper tailings from the large (i.e., porphyry) and medium-size copper deposits (i.e., volcanogenic massive sulfide and sediment-hosted) contribute to more than three quarters of the total global freshwater ecotoxicity impacts of copper tailings. This strongly correlates with hydrological conditions, leading to high infiltration rates. The generated inventories vary locally, even within single countries, showcasing the importance of site-specific models. Our study provides site-specific, dynamic emission models and thus improves the accuracy of tailing's inventories and toxicity-related impacts.

Correlation between Flotation and Rheology of Fine Particle Suspensions

This paper summarizes and discusses previous investigations into the correlation between the rheology and flotation process of fine particle suspensions. This summary provides a better understanding of the challenges and current status of this subject and useful feedback based on the revision of relevant theories and practical implications for fine particle characterization and processing. Such processes include the sustainable beneficiation of complex ores and wastes for valuable material extraction and the segregation of toxic substances. For example, there has been increasing demand for the beneficiation of complex ores often carrying the values (e.g., critical raw materials) in fine grains, due to the noticeable decrease in the accessibility of high-grade and easily extractable ores. To maintain the sustainable use of limited resources, the effective beneficiation of complex ores is urgently required. It can be successfully achieved only with selective particle/mineral dispersion/liberation and the assistance of mineralogical and fine particle characterization including a proper understanding of the rheological behavior of complex ores in the context of fine particle separation/processing. In correlating flotation with suspension rheology, previous works were summarized and we found that the modeling of their correlations as well as comprehensive contributions of pulp and froth rheology on flotation performance have been studied very limitedly, and comprehensive developments in these aspects are thus strongly suggested.

ToF-SIMS as a new method to determine the contact angle of mineral surfaces

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used as a technique to correlate the surface chemistry of chalcopyrite particles with their contact angle. Three particle sizes (20-38, 75-105, and 150-210 microm) were used, covering a range of contact angles between 20 and 90 degrees. Multivariate statistical techniques were applied to the ToF-SIMS data in order to identify structure in the data and the surface species contributing the most to surface chemistry and hence the hydrophobicity variation. A method to calculate the contact angle of chalcopyrite by ToF-SIMS surface analysis has been developed using only information from three secondary ions: oxygen, sulfur, and a thiol collector fragment. This approach is capable of determining the surface chemistry contribution to the contact angle of individual mineral particles and the distribution of contact angles within a large ensemble of particles. Further measurements verified that the methodology can also be applied to flat surfaces, enabling rapid surface chemistry-hydrophobicity correlations to be made on a wide range of mineral and material systems.