An experimental study on the effects of some process parameters on lignite flotation

This study investigated the performance of aggloflotation, a novel hybrid process that combines oil agglomeration and flotation, for the beneficiation of lignite coal from Sivas/Gemerek, Türkiye. The effects of critical process parameters, including depressant (sodium silicate) dosage, collector (kerosene) dosage, frother (methyl isobutyl carbinol) dosage, pulp pH, and solid-liquid ratio, were systematically evaluated. The optimum conditions were determined to be 250 g/t sodium silicate, 250 g/t kerosene, 200 g/t methyl isobutyl carbinol, pH 4, and a solid-liquid ratio of 10%. Under these conditions, the aggloflotation process achieved a yield of 80.92%, a combustible recovery of 91.35% and an ash content of 8.65%. Compared to conventional flotation and oil agglomeration, aggloflotation significantly outperformed both, particularly in reducing ash content while maintaining high recoveries. The process demonstrated efficiency in treating fine and ultrafine coal particles, addressing a significant challenge in the beneficiation of low-rank coals. These results suggest that aggloflotation offers a promising, efficient, and environmentally friendly solution for the cleaning of low-rank coals, with potential implications for enhancing coal utilization in energy production.

This study investigates the flotation performance of di(2-ethylhexyl) phosphoric acid (DEHPA) as an organic collector and optimizes key operating parameters using response surface methodology (RSM) for the flotation of Çorum/İskilip lignite from Türkiye. Preliminary flotation experiments were conducted using conventional collectors (kerosene, diesel oil, and fuel oil) to investigate flotation performance. The highest flotation performance was obtained using a binary collector system consisting of 20 kg/t DEHPA combined with 32 kg/t diesel oil (total dosage: 52 kg/t). Following collector optimization, the effects of sodium silicate dosage, pine oil dosage, and flotation time on flotation performance were investigated. Ash rejection and combustible recovery were selected as response variables. A Box-Behnken design (BBD) integrated with RSM was applied to evaluate the individual and interactive effects of these parameters. Model adequacy and statistical significance were assessed using analysis of variance (ANOVA). Optimization results indicated that optimum conditions were a pine oil dosage of 150 g/t and a flotation time of 240 s, while optimum sodium silicate dosage converged to 0 g/t, indicating that a depressant was unnecessary. Under these conditions, maximum ash rejection and combustible recovery were 55.19% and 55.62%, respectively. Overall, DEHPA improved flotation efficiency and ANOVA confirmed the reliability of model.

The adsorption and orientation of frother surfactants on heterogeneous wetting surfaces

The selection of suitable frothers in flotation processes plays a crucial role in controlling bubble formation, foam stability, and ultimately mineral recovery. Therefore, understanding the interfacial behavior of frothers is important to optimize flotation efficiency, especially for valuable sulfide minerals such as galena (PbS). In this study, the interfacial behavior and flotation performance of different frothers in PbS flotation were investigated with a particular focus on surface tension, bubble coalescence, foam stability, and flotation recovery. A high-purity crystalline PbS sample (≈96.65% PbS) obtained from Trabzon, Türkiye, was subjected to systematic experimental analyses including surface tension measurements, critical coalescence concentration (CCC) determination, dynamic foam stability (DFS) tests using the DFA100 analyzer, and micro-flotation experiments. 2-ethylhexanol (EH), polypropylene glycol 250 (PPG250), and methyl isobutyl carbinol (MIBC) were used as frothers, while potassium ethyl xanthate (PEX) was employed as a collector. The results revealed that EH had the highest surface activity (42.67 mN/m at 1000 ppm), and the lowest CCC value (~2 ppm) compared to PPG250 (~3 ppm) and MIBC (~8 ppm). According to the micro-flotation results, the flotation recovery gradually increased with increasing frother dosage; the highest recoveries were obtained with PPG250 (99.45%), EH (98.31%), and MIBC (95.17%). PPG250 and EH achieved higher flotation performance at lower dosages compared to MIBC. These findings highlight the critical role of molecular structure and interfacial properties in the effective selection of frothers for galena flotation.

Enhancing flotation performance of low rank coal by improving its hydrophobicity and the property of oily bubbles using 2-ethylhexanol

The dominant challenge of current copper beneficiation plants is the low recoverability of oxide copper-bearing minerals associated with sulfide type ones. Furthermore, applying commonly used conventional methodologies does not allow the interactional effects of critical parameters in the flotation processes to be investigated, which is mostly overlooked in the literature. To tackle this issue, the present paper aimed at characterizing the behavior of five key effective factors and their interactions in a sulfidized copper ore. In this context, dosage of collector (sodium di-ethydithiophosphate, 60–100 g/t), depressant (sodium silicate, 80–120 g/t) and frother (methyl isobutyl carbinol (MIBC), 6–10 g/t), pulp pH (7–11) and agitation rate (900–1300 rpm) were examined and statistically analyzed using response surface methodology. Flotation experiments were conducted in a Denver type agitated flotation cell at the rougher stage. The experimental results showed that increasing the pH (from 8 to 10) at low agitation rate (1000 rpm) enhanced the recovery from 80.36% to 85.22%, while at high agitation rate (1200 rpm), a slight declination occurred in the recovery. Meanwhile, increasing the collector dosage at a lower frother value (7 g/t), caused a reduction of about 4.44% in copper recovery owing to the interactions between factors, whereas at a higher frother level (9 g/t), the recovery was almost unchanged. The optimization process was also performed using the goal function approach, and maximum copper recovery of 92.75% was obtained using ~70 g/t collector, 110 g/t depressant, 7 g/t frother, pulp pH of 10 and 1000 rpm agitation rate.

During coal production, a significant amount of fine coal dust is generated. The utilization of these high-ash coals is of great importance for the national economy. This study aims to recover the slime of the Lavvar facility located in the Kütahya-Tunçbilek region by flotation. The experimental parameters studied include the collector dosage, dispersant dosage, frother dosage, flotation time, air flow rate, and solid ratio. Flotation performance was evaluated by determining the ash, calorific value, sulfur, volatile matter, fixed carbon, and yield values of the products obtained at the end of the experiment. As a result of the experimental studies, the highest yield value was obtained using 2000 g/t sodium silicate, 2000 g/t diesel oil, and 100 g/t MIBC with a solid ratio of 10%, a flotation time of 4 minutes, and an air flow rate of 4 L/min, producing marketable coal with 6312 KCal/kg calorific value, 0.95% sulfur, and 22.4% ash content.

Effect of frother addition mode on gas dispersion and coal flotation in a downflow flotation column

This research study proposed a novel approach utilising AI models to predict the metallurgical performance of complex sulfide ore flotation. Five machine learning and artificial intelligence models were employed in this study, that is, Random Forest (RF), Artificial Neural Networks (ANN), Adaptive Neuro Fuzzy Interference System (ANFIS), Mamdani Fuzzy Logic (MFL) and Hybrid Neural Fuzzy Interference System (HyFIS). Sixty-two flotation tests were conducted on samples containing galena, chalcopyrite and sphalerite as the main valuable minerals, and pyrite as the main gangue mineral. Different variables were used as inputs in the AI studies including physiochemical and operational parameters. The flotation recovery of lead and copper and their corresponding grades in the bulk concentrate were the primary dependent variables (outputs). The input variables included the dosages of sodium cyanide (pyrite's depressant), sodium isopropyl xanthate (collector), zinc sulfate (sphalerite's depressant) and Methyl isobutyl carbinol (MIBC, frother); air flow rate; flotation time; and the speed of the impeller in the flotation cell, which is indicative of the energy input. For the purpose of AI model development, datasets were divided into two subsets. The first subset was primarily used for the training phase, and it comprised 80% of the total data. The second subset, consisting of 20% of the total data, was used for testing. The models’ performance was assessed using two main indicators: R-squared (R 2 ) for the proportion of explained variation and RMSE for the average prediction error. The Hybrid Neural Fuzzy Interference System demonstrated superior performance in predicting the recovery and grade of copper and lead, with R² and RMSE of 0.9895 and 1.069 for the training phase, respectively, whereas for the testing step the respective values were 0.9128 and 2.859.

Purification of phosphate beneficiation wastewater: Separation of phosphate from Eshydia Mine (Jordan) by column-DAF flotation process

The entrainment of gangue particles always increases the ash content of coal flotation concentrate. In the present work, the adjustment for entrainment of kaolinite in coal flotation was studied focusing on the parameters including solid concentration and frother dosage. The results indicated that the ash contents of concentrates were always higher in the early or late stage (flotation time: 0–30 s or 120–180 s) than that in the middle stage (flotation time: 30–120 s). This is mainly because of the mechanical entrainment in the early stage and the entrainment caused by water transportation in the later stage. It has been confirmed that reducing the feed solid concentration and frother dosage effectively decrease mechanical entrainment in the early stage. Furthermore, better flotation results can be obtained under a high solid concentration and frother dosage in the late stage of the flotation process. Therefore, a novel two-stage flotation process was proposed for the coal flotation. A better flotation performance (combustible recovery: 91.28%; ash content: 4.09%) can be achieved by two-stage flotation, compared to the flotation results (combustible recovery: 93.12%; ash content: 5.16%) of the one-stage flotation process.

ABSTRACTThe aim of this study is to reduce reagent consumptions in graphite flotation with the addition of Aero 3477 promoter to the flotation stage. A three-level Box–Behnken design is used for optimization and modeling of flotation stages. For this purpose, the flotation experiments are performed in two steps. The maximum weight recovery and the minimum ash content values of the rougher concentrate are calculated as 21.41 and 32.49% using diesel oil dosage (714.24 g/t), methyl isobutyl carbinol (MIBC) dosage (212.81 g/t), and sodium silicate (Na2SiO3) dosage (1451.189 g/t), respectively, in the preliminary experiment tests. Subsequently, keeping the Na2SiO3 dosage constant, Aero 3477 promoter is added to the flotation stage to provide reduction at reagent consumptions. As a result, the reagent consumptions of diesel oil dosage (162.10 g/t), MIBC dosage (129.58 g/t), and Aero 3477 promoter dosage (168.96 g/t) are supplied to reach the approximate weight recovery and the ash content as in primary experimental results. Considerable dosage decreases in both diesel oil and MIBC are achieved using promoter. Moreover, experimental studies are also evaluated using upgrading curves.

Application of flotation for upgrading and recovery of copper (Cu) and molybdenum (Mo) contained in flotation tailings from a copper/molybdenum mine was investigated in this study. The sample contained mainly pyrite (FeS2) and quartz (SiO2) as dominant phases with Cu and Mo contents at 0.38% and 0.23% respectively. A flotation system employing use of collector/frother mixture [kerosene + sodium dodecyl sulphate (SDS) + polyethylene alkyl ethyl] with tannic acid and sodium silicate as FeS2 and SiO2 depressants, compared against potassium amyl xanthate (PAX) and methyl isobutyl carbinol (MIBC) additions were investigated to evaluate Cu and Mo recovery. According to the results, the grades of Cu and Mo in the concentrate did not increase to above 1% when PAX and MIBC were used as collector and frother, even at increased PAX addition. Also grades for tests performed at varying pH rangig from pH 3 to 11 showed no significant improvement. However, with the use of the collector/frother mixture and tannic acid, Cu and Mo grades increased to 1.4 and 2.4% respectively. The grade of Mo was further increased to 8.0% at 52% recovery when sodium silicate was used with the collector/frother mixture. These results indicate that Cu and Mo lost in such tailings can be upgraded and offered as additional resource for possible recovery.

The flotation performance of clean coal with different reagents and pretreatment agents was investigated. The study examines the efficient recovery of anthracite coal using polyacrylamide flotation pretreatment. The mechanism of pretreatment agents and anthracite was investigated using Fourier transform infrared spectroscopy (FTIR), zeta potential measurements and focused beam reflectance measurement (FBRM). The wetting behavior and flotation performance of anthracite and pretreatment agents were investigated using contact angle measurements and series of flotation tests. The coal samples were treated with reagents like kerosene, sec-octanol and pretreatment agents like polyacrylamides, (cat-ionic polyacrylamide, non-ionic polyacrylamide, an-ionic polyacrylamide), sodium silicate and sodium oleate to investigate their impact on coal surface properties and the subsequent flotation performance. The optimum dosage of kerosene was found to be 10 kg/t and that of sec-octanol was 1.84 kg/t. Moreover, the optimum dosages of cat-ionic polyacrylamide, sodium oleate and sodium silicate were 200 g/t, 350 g/t and 500 g/t respectively. The yield of clean coal of cat-ionic polyacrylamide was 70.70 %, ash content of clean coal of cat-ionic polyacrylamide was 11 %. The sodium silicate (Na2SiO3) has the yield of 66.66 % and the ash content of 13.9 %. The results indicated that the cat-ionic polyacrylamide demonstrated the most substantial improvement in flotation performance, particularly when used in conjunction with kerosene and sec-octanol.

A comparative study of methyl cyclohexanemethanol and methyl isobutyl carbinol as frother for coal flotation