Study on the surface chemistry behavior of pyrochlore during froth flotation

Separation of pyrochlore from its associated minerals is typically accomplished by froth flotation. The surface chemistry of pyrochlore is similar to many of its associated non-value minerals. Therefore, understanding the surface chemical properties of the pyrochlore for selective pyrochlore flotation will potentially aid in the design of flotation strategies for optimized recovery. In this study, pyrochlore samples were collected from various points in the flotation scheme at the Niobec plant, Quebec, Canada. The SEM-EDX analysis revealed that pyrochlore from the Niobec deposit occurs as high and low iron varieties, and that recovery favours varieties with a lower Fe content. To understand a potential relationship between pyrochlore matrix composition and the related effect on collector adsorption, the surface of grains from the concentrate and tails were examined by TOF-SIMS. The surface analyses of different pyrochlore grains showed that species indicative of the cationic collector (Tallow diamine acetate) favour Fe poor pyrochlore relative to the Fe rich variety. XPS was used to analyse the surface of high Fe and low Fe pyrochlore in order to identify a potential relationship between pyrochlore matrix composition and surface chemistry. The XPS results verified a relationship between pryochlore surface oxidation and Fe content in the mineral matrix; high Fe pyrochlore particles showed a greater proportion of surface oxidation species suggesting preferential oxidation in comparison with low Fe pyrochlore particles. SEM-EDX analyses revealed that many of the pyrochlore grains were compositionally zoned into regions of high and low Fe contents. TOF-SIMS and XPS analyses were used to analyse the surface of the compositionally zoned Fe pyrochlore grains, in order to link collector adsorption to Fe contents and identify potential mechanisms for the partitioning. Surface analyses of conditioned pyrochlore grains showing zones of high and low Fe content revealed that species indicative of the collector favour the regions with low iron. XPS analyses of similarly treated compositionally zoned pyrochlore grains showed that a greater proportion of surface oxidation species corresponded to the zones with high matrix Fe content. These results are in accord with the results identified for non zoned pyrochlore grains of variable matrix Fe content and verifies the link between pyrochlore Fe composition, surface oxidation and, area selective collector loading

Effects of Conventional Flotation Frothers on the Population of Mesophilic Microorganisms in Different Cultures

peer reviewedBioleaching is an environment-friendly and low-investment process for the extraction of metals from flotation concentrate. Surfactants such as collectors and frothers are widely used in the flotation process. These chemical reagents may have inhibitory effects on the activity of microorganisms through a bioleaching process; however, there is no report indicating influences of reagents on the activity of microorganisms in the mixed culture which is mostly used in the industry. In this investigation, influences of typical flotation frothers (methyl isobutyl carbinol and pine oil) in different concentrations (0.01, 0.10, and 1.00 g/L) were examined on activates of bacteria in the mesophilic mixed culture (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, and Acidithiobacillus thiooxidans). For comparison purposes, experiments were repeated by pure cultures of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans in the same conditions. Results indicated that increasing the dosage of frothers has a negative correlation with bacteria activities while the mixed culture showed a lower sensitivity to the toxicity of these frothers in comparison with examined pure cultures. Outcomes showed the toxicity of Pine oil is lower than methyl isobutyl carbinol (MIBC). These results can be used for designing flotation separation procedures and to produce cleaner products for bio extraction of metals

Data for: Investigating occurrences of valuable trace elements in African coals as potential byproducts of coal and coal combustion products

Analysis of African coal

Explaining surface interactions for common associated gangues of rare earth minerals in response to the oxalic acid

In the flotation of rare earth minerals (REMs), oxalic acid is reportedly acting both as a depressant and pH modifier. Although results of testing have established the significance of oxalic acid in the flotation process, its specific role in either the recovery or selectivity of REMs over their common gangue minerals is not well understood. Pulp pH reduction trials with alternative acids have not shown the same effect on the REMs recovery or the depression of gangue phases. This work studies the effect of oxalic acid on the surface of common REMs gangue minerals (quartz and carbonates (dolomite and calcite)) in a series of conditioning tests. Gangue surface analyses by time of flight secondary ion mass spectroscopy (TOF-SIMS) indicate that oxalic acid inhibits the transfer of secondary ions generated during the conditioning process from one mineral to another. In this regard, the oxalate anion acts to fix ions in solution through chelation, limiting their participation in surface adsorption. Keywords: Oxalic acid, Rare earth, Silicate, Carbonate, TOF-SIM

Data for: Investigating occurrences of valuable trace elements in African coals as potential byproducts of coal and coal combustion products

Analysis of African coalsTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Modeling of particle sizes for industrial HPGR products by a unique explainable AI tool- A “Conscious Lab” development

High-Pressure Grinding Rolls (HPGR), as a modified type of roll crushers, could intensively reduce the energy consumptions in the mineral processing comminution units. However, several problems counted for their operational modeling, especially in the industrial scales. Expanding a conscious laboratory (CL) as a recently developed concept based on the recorded datasets from the HPGR operational variables could be tackled those complications and fill the gap. Moreover, constructing such a CL base on explainable artificial intelligence (EAI) systems would be an innovative point for the digitalizing powder technology industries. Using a robust EAI model as a strategic approach could significantly improve system transparency and trustworthiness to convert any complicated black-box machine learning to a logical human basis system. This study introduced the SHapley Additive exPlanations (SHAP) and extreme gradient boosting (XGBoost) as the latest powerful EAI tool for the CL modeling of the particle sizes produced by an industrial HPGR (P80) in the Fakoor Sanat iron ore processing plant (Kerman, Iran). SHAP precisely assessed multivariable relationships between the monitored operational variables and correlated them with the HPGR P80. SHAP values showed relationship magnitudes among variables and ranked them based on their effectiveness on the P80 prediction. The working gap demonstrated the highest importance for the P80 prediction. XGBoost could precisely predict the P80 and showed higher accuracy than typical machine learning methods (random forest and support vector regression) for constructing the CL of HPGR. These significant outcomes would open a new window for robust consideration of the EAI models within powder technology

Biodegradable acids for pyrite depression and green flotation separation–an overview

Exponential increasing demands for base metals have made meaningful processing of their quite low-grade (&gt;1%) resources. Froth flotation is the most important physicochemical pretreatment technique for processing low-grade sulfide ores. In other words, flotation separation can effectively upgrade finely liberated base metal sulfides based on their surface properties. Various sulfide surface characters can be modified by flotation surfactants (collectors, activators, depressants, pH regulators, frothers, etc.). However, these reagents are mostly toxic. Therefore, using biodegradable flotation reagents would be essential for a green transition of ore treatment plants, while flotation circuits deal with massive volumes of water and materials. Pyrite, the most abundant sulfide mineral, is frequently associated with valuable minerals as a troublesome gangue. It causes severe technical and environmental difficulties. Thus, pyrite should be removed early in the beneficiation process to minimize its problematic issues. Recently, conventional inorganic pyrite depressants (such as cyanide, lime, and sulfur-oxy compounds) have been successfully assisted or even replaced with eco-friendly and green reagents (including polysaccharide-based substances and biodegradable acids). Yet, no comprehensive review is specified on the biodegradable acid depression reagents (such as tannic, lactic, humic acids, etc.) for pyrite removal through flotation separation. This study has comprehensively reviewed the previously conducted investigations in this area and provides suggestions for future assessments and developments. This robust review has systematically explored depression performance, various adsorption mechanisms, and aspects of these reagents on pyrite surfaces. Furthermore, factors affecting their efficiency were analyzed, and gaps within each area were highlighted.Funder: Center  of  Advanced  Mining  and  Metallurgy (CAMM3), Luleå University of Technology</p