Collector Concentration Research Articles

Co-adsorption of NaOL/SHA composite collectors on cassiterite surfaces and its effect on surface hydrophobicity and floatability

A binary collector system containing sodium oleate/salicylhydroxamic acid (NaOL/SHA) was optimized to improve the floatability of cassiterite at low concentrations. The results of the microflotation experiments demonstrated that the binary mixture performed better than the single collector. At the optimum pH of 8.0 and a total collector concentration of only 5 × 10-5 mol/L, the flotation recovery of cassiterite in the presence of the NaOL:SHA (1:2) mixture was above 90 %. The synergism between NaOL and SHA was rationalized by studying the changes at the solid–liquid interface based on zeta potential measurements, collector adsorption quantification, surface tension analysis, and X-ray photoelectron spectroscopy. Density functional theory calculations confirmed that the co-adsorption of the two collectors resulted in strong O-Sn chemical bonds with the cassiterite surface.

Effects of physical and physico-chemical factors on pulp rheology of smithsonite

Pulp rheology is an important factor affecting flotation. The effects of particle size (150-74 μm, 74-38 μm, 38-23μm, -23 μm), pulp density (11.76%-34.78%), pH (5.3-12.4), collector concentration (25-500 mg/dm3), and stirring intensity (400-900 rpm) on the rheology of smithsonite, kaolinite, quartz, and calcite minerals were investigated in detail. Additionally, the agglomerate morphology of particles was observed by a polarizing microscope. The results showed that as the mineral particle size decreased and pulp density increased, the apparent viscosity and yield stress of the pulp increased. Especially the fine mineral particles (-23 μm) presented a higher apparent viscosity and yield stress. The order of apparent viscosity and yield stress for the minerals from large to small was: kaolinite>calcite>smithsonite>quartz under different pH values, the collector concentrations, and stirring intensities. In the presence of collector of octadecylamine, smithsonite, kaolinite, and calcite particles could form aggregates, especially smithsonite particles presented obvious agglomeration with large particle size and compact network structure. The agglomeration effect of calcite and kaolinite particles were weaker than that of smithsonite. The particle agglomeration resulted in the increase of the apparent viscosity and yield stress of the pulp. Quartz particles did not form clusters，hence the pulp’s apparent viscosity and yield stress were the lowest. The research on the changes in rheological properties of the pulp will hopefully provide some guidance for future flotation.

The impact of indigenous microorganisms on coal flotation: A new perspective on water consumption

Coal preparation plants are devoted to finding new strategies for reducing fresh water consumption, however, rarely taking consideration on slurry microorganisms. The impact of the abundant microorganisms on coal flotation, especially the isolated indigenous bacteria Bacillus sp. QX4 was systematically investigated in this study. Orthogonal experiments involved in parameters of concentration of microorganisms, collector and frother were conducted. The response surface analysis showed that the concentration of microorganisms was the main factor affecting flotation recovery and water consumption. With the amount of microorganisms increased from 105 to 108 cells/ml, clean coal yield decreased by 15 %, and water consumption increased by as high as 30 %. The characterization of the coal showed that the attachment of microorganisms increased the number of oxygen-containing functional groups onto the coal surface, and the contact angle of coal decreased from 79.5°to 56.6°. In addition, the net negative zeta potential decreased after microorganism addition, which improved the froth stability and weakened the coal’s attachment to the collector molecules. Further evaluation showed that the transfer of water reduced the calorific value of the clean coal by about 500 kcal/kg while increasing the carbon emission during combustion by about 5.9 %. This study provides a new perspective on the reverse impact of indigenous microorganisms on fresh water consumption and flotation product in coal flotation, which can potentially help efficient operation involved in optimizing water management of coal preparation plants.

A Comparative Study of Active Solo and Dual Inclined Compound Parabolic Concentrator Collector Solar Stills Based on Exergoeconomic and Enviroeconomic

Abstract: The Parabolic Concentrator (CPC) is a uniform photovoltaic thermal (PVT) compound linked to solar photos (N) of water collectors called PVT-CPC Active Solar Filtration System Analysis. New Delhi Analysis is done for a solar filter system for a given particle size under weather conditions. We assess efficiency, system productivity, and life cycle cost analysis. The Thermal Model Life cycle cost efficiency (LCCE), designed for LCCE analysis, is considered the only and double-doubled effective PVT-CPC system for filtering solar energy recovery time. In this work, we need to analyze the appropriate points of the collector and extract the bulk of the system. Tests were performed on dual-solar and dual-inclined PVT-CPC operating systems with a single basin size and a water depth of 0.14 m, with yield on yearly basis, factor of energy payback, and efficiency of life cycle cost conversion analysis of 5.0%, 12.63%. Moreover, 22.21% is two times higher than the solo inclined system. In addition, the water return, one PVT-CPC, and two turns have been found to have a recovery time (EPT) with an interest rate of 5%. The solar filter system is 10.89% and 17.99% higher than the solo inclined photovoltaic thermal compound parabolic concentrator activated solar filter system, respectively. The above analysis concluded, we can confirm that the two bends are better than the active PVT-CPC system for solar filtering, which is the only inclination of the depth of 0.14 m in water based on daily based analysis. If depth of water 0.14 m is more significant, for basin size provided the performance of one inline is improved and is better than curved solar-powered filtering systems. The upgraded system lasts longer and can meet potable water and DC electricity on sunny commercial days.

Investigation of Heat Transfer Fluids Using a Solar Concentrator for Medium Temperature Storage Receiver Systems and Applications

Solar concentrator collectors have the potential of meeting the medium- and high-temperature thermal energy demands of the world. A heat transfer fluid (HTF) is a vital component of a concentrating system to transfer and store thermal energy. This paper presents the design development of a solar paraboloidal dish concentrator (SPDC) and a study of selected HTFs using the storage receiver system of the concentrator. The locally designed SPDC (diameter 1.21 m and height 0.20 m) has features like light weight, effortless tracking, convenient transportation along with high optical and thermal performance. Three HTFs, silicone oil (SO), engine oil (EO) and ethylene glycol (EG), are selected based on their favorable properties for medium temperature (150–300 °C) applications. The characteristic parameters of HTFs, heating rate (Rh), instant thermal efficiency (ηith) and the overall heat loss coefficient (UL), are illustrated and determined experimentally. A new characteristic parameter, the normalized maximum fluid temperature (Tnf), is also introduced in the paper. In the heating test, the maximum attained temperatures by fluids, SO, EO and EG are found to be 240 °C, 180 °C and 160 °C, respectively. The thermal efficiencies of SO, EO and EG are determined to be 45, 36 and 31%, respectively. The heating rate of 6.56 °C/s is found to be the maximum for SO. Through the cooling test, the overall heat loss coefficient (UL) is computed to be 14 W/mK, which is the least among the three fluids compared. The high thermal performance, environmental safety and chemical stability of silicone oil make it suitable for use in concentrators for medium-temperature heat transfer and storage applications.

Improvement of fine muscovite flotation through nanobubble pretreatment and its mechanism

With the increasing demand for mineral resources, it is necessary to further recycle some fine muscovite which are not of high quality and discarded after the first development. This study was to improve the recovery of fine muscovite (−20 μm) by introducing of nanobubbles (NBs). A series of techniques including flotation test, mineral adsorption capacity measurement, Zeta potential measurement and the visualization of mineral and bubble interaction were used to investigate the flotation effect of NBs pretreatment on fine muscovite. The results showed that in the dodecylamine (DDA) flotation system, the flotation recovery of fine muscovite pretreated by NBs was higher than that without NBs pretreatment under any concentration of collector and flotation recovery was increased by about 7 %. Meanwhile, the dosage of reagent was reduced by 25 % at the same recovery. NBs pretreatment could reduce the adsorption capacity of DDA and electrostatic repulsion of the muscovite particles, which was beneficial to form particle agglomeration. In addition, the three-phase contact line of the muscovite pretreated with NBs could be formed faster (34 ms). Furthermore, the trajectory of muscovite particles pretreated by NBs were closer to bubbles, and easier to form obvious agglomeration. The introduction of NBs can enhance the flotation of fine muscovite, which provide a cost-effective approach for the fine particle flotation.

Computer Vision of Optimal Geometric Concentration Ratio for the Solar Ball Lens

This research evaluates the optical properties of an inhomogeneous and non-paraxial system using a solar ball lens (SBL) as a new thermal solar concentrated collector. This evaluation is based on detecting a diacaustic curve in a straightforward and accurate manner, with the diagnostic relying on image processing as a computational tool using the MATLAB program rather than a complicated numerical analytic procedure. The circle of least confusion (CLC) of the (SBL), (Fluorinated ethylene propylene (FEP) polymer – water core), was calculated. Furthermore, the study evaluated the maximum geometrical concentration ratio (G C) of refracted solar radiation that can be captured by a receiver of the (SBL). Without energy losses due to spherical aberration, the (G C) ratio was (14.10) at (h/r) ratio, circular aperture radius to ball radius, around (0.6). The investigation also revealed an aplanatic point for preventing the development of optical envelope inside the solar ball lens at (h/r) equal to 0.8638, as well as a maximum (h/r) value of 0.7351 for collecting solar radiation.

Reprocessing of magnesite beneficiation waste to recover mineral value and minimise environmental footprint

The current paper deals with the re-processing of mineralised mine waste from magnesite processing operations aiming at the recovery of the value. Two cases of mineralised waste were examined. First, waste derived from the removal of “fine” before hand-sorting, with particle size of -40 mm; this waste is usually stockpiled, comprises mostly of relatively coarse particles and is of relatively high-grade in magnesite. The separation methods applied were sorting, sink-float tests and magnetic separation. In general, the results from the application of physical separation methods were satisfactory. Commercial concentrates were obtained from sorting with MgCO3-grade ranging between 94 and 97% MgCO3 and yield about 46%; in case of mixing concentrate with middling, yield rises to 58-64% while grade slightly drops to 91-94%. Equally satisfactory were the results from sink-float separation at sp.gr. 2.88 (grade 95%, yield 45%) but questions arise from the small sp.gr. difference of magnesite and gangues. Finally, the less satisfactory results obtained from magnetic separation (grade around 80-85%, yield 33-65%) may be due to inefficient particles liberation and higher magnetic field is maybe required. Second, mineralised waste consisting of fine particles from size reduction operations were tested. These fines were processed with selective magnetic coating as well as co-agglomeration / magnetic separation techniques. In general, the results of physicochemical processing of fines were very encouraging both on single minerals and their artificial mixtures. In case of magnetic coating, the effect of pH, collector concentration and kerosene dose was studied first on single minerals. Optimum results were obtained for pH=9, dodecylamine solution 4.5x10-5 M and kerosene 2.5 L/t. Tests on artificial mineral mixtures at optimum conditions and magnetic separation at 0.8 A resulted in non-magnetic product with MgCO3-grade higher than 99%. The parameters examined in co-agglomeration / magnetic separation tests were the same as with magnetic coating. Best conditions for co-agglomeration on single minerals were pH=8, dodecylamine 2 kg/t, kerosene 4 L/t. Tests on mineral mixture reveals that the MgCO3-grade increases with dodecylamine but the yield drops.

On using excess Gibbs energy as an indicator of hydrophobicity in the flotation process

It has been shown that the partial molar excess Gibbs energy (G̅ex) can be used as an indicator of hydrophobicity and hence contributes to explaining the behaviour of collectors in the recovery of minerals by flotation. This is because hydrophobicity of a mineral particle on which a collector is adsorbed is related to the fact that the alkyl chain associated with the collector behaves in the same way as any hydrocarbon would in a non-ideal mixture with water. Such mixtures are quantified thermodynamically by determining the activity coefficient of the hydrocarbon moiety of the collector and hence its G̅ex in the mixture. The present paper is aimed at extending the above concepts in two different ways. Firstly, an investigation is made of the relationship between G̅ex and contact angle and/or recovery for systems such as ionic liquids and aminothiophenols. Secondly, on the basis of the observation that increases in G̅ex are indicative of increases in the hydrophobicity of the mineral particle-collector aggregate, a study was undertaken to examine, respectively, the effects of the presence of electrolytes or alcohols in the system, of pH and changing concentrations of the collector, on G̅ex of the collector alkyl group and hence its hydrophobicity. In the first instance, the relationship between G̅ex and contact angle and recovery is sustained. With respect to the latter, the absence of any correlation between G̅ex and recoveries supported the proposition that the major effect of electrolytes and added alcohols is rather on particle – bubble attachment. Similarly, it is also indicated that since the change in G̅ex is minimal when collector concentration or pulp temperature is increased these changes do not significantly affect the hydrophobicity of the collector-mineral particle and hence also the recovery in a microflotation.

Floatability and calculated reactivity of sulfide minerals and gold

The paper provides the results of theoretical reactivity calculations for gold, molybdenum, stibnite, galena, chalcopyrite, arsenopyrite and pyrite in comparison with such experimental data as the floatability of monomineral fractions with butyl xanthate, wetting angle values, changes in the kinetics of the mineral electrode potential. The following calculation series in terms of reactivity and oxidizing ability were established by calculation: Au < Sb2S3 < MoS2 < PbS < CuFeS2 < FeAsS < FeS2. During the Hallimond tube flotation, natural gold grains demonstrated the highest recovery (70 %) in the рН = 5÷7 range compared to all the studied sulfides. Molybdenite and stibnite are floated at the level of 50 % under the same conditions. As pH increases towards the alkaline region, a decrease in the floatability of all sulfides except for chalcopyrite is observed. It was established that the highest recovery is achieved when the required time of conditioning with the collector is the inverse of their reactivity. The measured wetting angle of a drop of water on an untreated surface has the highest value (78°) for a gold plate, and the lowest one (67°) for pyrite, but the latter features the greatest increase in the wetting angle (by 15°) after treatment with butyl xanthate at a concentration of 10–4 mol/l and pH = 6. For molybdenite, treatment with butyl xanthate has practically no effect on the measured wetting angle. The Sb2S3 < PbS < CuFeS2 < FeAsS < FeS2 series is determined according to the electrode potential in the рН = 2.0÷5.6 range. Theoretical calculations and experimental data obtained when studying monofractions of sulfides and gold showed that experimental conditions (pH, conditioning time, collector concentration) significantly affect the floatability. The calculated reactivity of chemical sulfide compounds and gold in comparison with experimental results proved the importance of maintaining certain flotation conditions to create contrast in the floatability of minerals.

Thermal management and develop energy storage in performance improvement of triangular and cubical parabolic collectors

The novelties of this work are thermal management in the triangular and cubical concentrator collectors along with turbulent water, oil, ethylene glycol, and glycerin. Present learn about optimized and multiplied the efficiency of attention solar parabolic collector. Three-dimensional computational fluid dynamics (CFD) simulations are performed using FLUENT software to study fluid flow, turbulence, heat transfer, and thermal energy consumption on the nanoparticles water, ethylene glycol, oil, and glycerin sides for various solar panel configurations. CFD Performance Analysis is performed under turbulent flow conditions for circular and octagonal collector configurations. The fluid drift is turbulent, incompressible, steady, and totally developed. The collectors with triangular and cubical move areas have been investigated with water, oil, ethylene glycol, and glycerin fluids. The top half of these go sections is a collector and the lower half is insulated. According to the result, enthalpy performance of the triangular collector using oil, ethylene glycol, and glycerin developed 12%, 26%, and 30%, respectively. Also, total surface heat flux for a cubical collector using ethylene glycol, water, oil, and glycerin increased 25.2%, 41%, 5.9%, and 26.6%, respectively, more than triangular collector. Moreover, surface incident radiation in triangular collector for ethylene glycol, water, oil, and glycerin were 64%, 1.4%, 12.2%, and 7.4%, respectively, more than cubical collector. In addition, radiation heat flux of triangular collector for ethylene glycol, water, oil, and glycerin developed 76%, 8.5%, 85%, and 82%, respectively, more than cubical collector. Finally, performance efficiency of water in cubical collector, oil in triangular, ethylene glycol, and glycerin increased 16%, 11.1%, 11.8%, and 4%, respectively, more than cubical collector.

Hybrid Serving of DOE and RNN-Based Methods to Optimize and Simulate a Copper Flotation Circuit

Prediction of metallurgical responses during the flotation process is extremely vital to increase the process efficiency using a proper modeling approach. In this study, two new variants of the recurrent neural network (RNN) method were used to predict the copper ore flotation indices, i.e., grade and recovery within different operating conditions. The model input parameters including pulp pH and solid content as well as frother and collector dosages were first analysed and then optimized using a two-step factorial approach. The statistical analysis showed a reliable correlation between operating parameters and copper grade and recovery with coefficients of 99.86% and 94.50%, respectively. The main effect plots indicated that pulp pH and solid content positively affect copper grade while increasing the frother and collector dosages negatively influenced the quality of the final concentrate. Despite the same effect from pulp pH, reverse effects from other variables were observed for copper recovery. Process optimization revealed that maximum copper recovery of 44.39% with a grade of 11.48% could be achieved under the optimal condition as pulp pH of 10, solid content of 20%, and frother and collector concentrations of 25 g/t and 9.9 g/t, respectively. Then, the predictive efficiency of long short-term memory (LSTM) and gated recurrent unit (GRU) networks with proper structure were evaluated using mean square error (MSE), root mean square error (RMSE), mean absolute percentage error (MAPE), and correlation coefficient (R2). The simulation results showed that the LSTM network with higher R2 of 0.963 and 0.934 for copper grade and recovery, respectively, was more effective than the GRU algorithm with the corresponding values of 0.956 and 0.919, respectively. The results show that the LSTM model could be useful in predicting the copper flotation behaviour in response to changes in the operating parameters.

Experimental investigation of solar chimney with concentrated collector (SCCC)

In this article, we have experimentally studied the effect of solar radiation concentration on a solar chimney collector. We analytically measured the performance of the solar chimney with concentrated collector (SCCC) while comparing it with the performance of a solar chimney without a reflector as far as the concentration of solar radiation is concerned. The solar chimney is built on a wooden building measuring 2 m × 2 m × 2 m and located at the Higher Polytechnic School of Dakar. The purpose of this article was to evaluate the addition of reflectors (boosters) on a conventional tilted solar chimney on natural ventilation in a building. The results show that the three reflectors added to the solar chimney increased the collector solar radiation. This concentration of radiation, combined with a high absorptivity of the collector, increased the temperature of the collector. There was a noticeable temperature difference between the solar chimney with concentrated collector and the one without concentrated collector. This temperature rise has induced an elevation in velocity. Therefore, the addition of reflectors can improve the chimneys performance for a better natural ventilation in bioclimatic buildings.

Effect of deep oxidation of chalcopyrite on surface properties and flotation performance

In this study, chalcopyrite was oxidized in hydrogen peroxide (H 2 O 2 ) solutions of different concentrations to simulate different degrees of oxidation in real ores, and the effects of H 2 O 2 treatment on chalcopyrite surface properties and flotation performance were investigated by surface analysis techniques and floatation experiments, which implied the reason for the poor grade and recovery of oxidized chalcopyrite concentrate in the production process of the ore. Flotation results showed that when the concentration of H 2 O 2 increased from 0% (by weight) to 5%, the flotation recovery of chalcopyrite decreased sharply. However, with increasing H 2 O 2 concentration from 5% to 30%, chalcopyrite recovery improved relatively to different degrees with different collector concentrations. Analyses of X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-atomic optical emission spectrophotometry (ICP-OES) results indicated that the pretreatment with H 2 O 2 caused that hydrophilic substance formed on chalcopyrite surface with the dissolution of copper ions, and the dissolution amount of copper increased with the increase of H 2 O 2 concentration. UV–visible spectrophotometer and Fourier Transform Infrared spectrum (FTIR) studies indicated that the pretreatment of chalcopyrite with H 2 O 2 had little effect on the adsorption amount of potassium butyl xanthate (PBX) on chalcopyrite surface. However, due to the dissolution of copper ions, PBX interacted with chalcopyrite mainly as buthyl dixanthogen (BX) 2 .

Enviroeconomic and Exergoeconomic Based Analytical Study of Double Slope Solar Distiller Unit Using Al2O3 Nanoparticles

Abstract: Present study represents the environeconomic and exergoeconomic analysis of a double slope solar desalination unit (DSDU) coupled with N identical compound parabolic concentrator collector (N-CPC) with helically coiled heat exchanger using Al2O3 nanoparticles. The analysis is observed for a yearly based for the atmospheric situation of New Delhi with the help of analytical program fed in MATLAB. The input data required for the mathematically calculation has been taken from Indian Metrological Department, Pune, India. The average value of annual energy output will be computed based on the energy outputs of summer and winter seasons followed by the evaluation of economic, enviroeconomic and exergoeconomic for the system and compared with previous system. Furthermore, based on annual as well as life of 15 and 20 years it is found 8.5% greater yield, annual exergy 7.31% greater, CO2 mitigation/ton energy 3.9% and 2.85% less, annual productivity 5.17% greater, and exergoeconomic parameter 4% greater respectively. It will be concluded that the proposed system is better than other system based on energy enviroeconomic and exergoeconomic parameters

Prediction of grade and recovery in flotation from physicochemical and operational aspects using machine learning models

Machine learning (ML) models for predicting flotation behavior focus on operational variables. Fundamental aspects, e.g., physicochemical variables that describe mineral surfaces for bubble–particle interactions, are largely neglected in these models; however, these physicochemical variables of mineral particles, including bubbles and pulp, influence the flotation behavior. Thus, this study aimed to advance the prediction of flotation behavior by including physicochemical variables. Among four ML models used for the prediction, the random forest model had the best performance and was therefore subsequently used to investigate variable importance. Contact angle, particle diameter, bubble diameter, particle charge, collector concentration, flotation time, and number of mineral species were the most important variables. Limitations (e.g., assumptions and empiricism) and implications of our study were presented. Finally, our expectation was to encourage more attention to physicochemistry in flotation using ML for a more generalized empirical flotation model.

Control Strategies Applied to a Heat Transfer Loop of a Linear Fresnel Collector

The modelling of Linear Fresnel Collectors (LFCs) is crucial in order to predict accurate performance for annual yields and to define proper commands to design the suitable controller. The ISO 9806 modelling, applied to thermal collectors, presents some gaps especially with concentration collectors including LFCs notably due to the factorisation of the incidence angle modifiers and the fact that they are considered symmetric around the south meridian. The present work details the use of two alternative modellings methodologies based on recorded experimental data on the solar system installed at the Cyprus Institute, in the outskirts of Nicosia, Cyprus. The first modelling is the RealTrackEff, which is an improved ISO9806 modelling, and the second is constructed using the CARNOT blockset in MATLAB/Simulink. Both models include all the elements of the heat transfer fluid loop, i.e., mineral oil, with a tank and a heat-exchanger. First, the open loop’s studies demonstrated that the root mean square on temperature is 1 °C with the RealTrackEff; 2.9 °C with the CARNOT and 6.3 °C with the ISO9806 in comparison to the experimental data. Then, a PID control is applied on the experimental values in order to estimate the impact on the outlet temperature on the absorber and on power generation. Results showed that the error on the estimation of the heat absorbed reaches 32%.

Improving the flotation recovery of Cu from flash smelting slags by utilizing cellulose-based frother formulationss

• First published study using polymer-surfactant mixes as frothers in Cu slag flotation. • Using the PS-mix improved overall Cu recovery compared to commercial frother. • PS-mix significantly increased productivity, i.e. similar froth product in less time. • PS-mix demonstrated superior tolerance in performance when reducing xanthate dosage. Froth flotation is an operation currently used for the recovery of Cu from pyrometallurgical smelting slags due its simple operation and relatively low operational costs. While it has been utilized for many decades, it may be necessary to develop strategies that improve Cu recovery from slags, as the unprecedented increase in Cu demand has made industrial waste and side streams economically relevant sources of metals. This study presents a novel chemistry-based approach for the flotation of Cu from smelting slags by utilizing an amphiphilic cellulose-surfactant mixture as a flotation frother, hereby referred to as CellFroth. The present work pursues two main objectives: i) to improve the performance of flotation for the treatment of smelting slags and ii) to accomplish a first proof of concept for frothers produced from renewable sources in the context of industrial waste treatment. The flotation performance of CellFroth was compared with a commercially available additive (i.e., DowFroth250) and hydroxypropyl methyl cellulose (HPMC). The results showed significant advantages in performance for CellFroth. At the highest collector concentration, Cu recovery was higher with CellFroth compared to DowFroth 250 and pure HPMC (73%; 62% and 65% respectively). A 75% reduction in xanthate concentrations had negligible effects on Cu recovery for CellFroth (70%), while recoveries decreased drastically with DowFroth250 (47%) and pure HPMC (50 %). Finally, CellFroth consistently reached comparable concentrate productivity (grade and recovery) as DF250 within significantly shorter flotation times. The use of CellFroth thus offers the possibility of increasing the Cu recovery from flash smelting slags, while reducing the environmental impact of the process by using a frother produced from sustainable sources and simultaneously reducing xanthate consumption.

Recovery of soluble chlorides from municipal solid waste incineration fly ash using evaporative crystallisation and flotation methods

ABSTRACT Fly ash contains large amounts of soluble chlorides, including KCl, NaCl, and CaCl2. Currently, KCl and NaCl from the wastewater obtained after washing are separated mainly via evaporative crystallization, whereas CaCl2 is preferentially precipitated using Na2CO3. These methods present poor separation performance of KCl and NaCl. In this study, evaporative crystallization was used to simultaneously separate KCl and NaCl mixture from CaCl2. The solubility test results and theoretical recoveries of KCl and NaCl were used as a basis for the experiments. The recoveries of NaCl and KCl were 92.73% and 92.70%, respectively. Contact angle tests were performed to evaluate hydrophobicity of KCl and NaCl surfaces. The contact angle of a KCl–NaCl saturated solution containing flotation reagents on NaCl and KCl was 0° and 28.2°, respectively, indicating the complete hydrophilicity of NaCl and hydrophobicity of KCl. Separation of KCl and NaCl via flotation was analyzed and the effects of collectors, collector concentration, depressants, and pH on flotation efficiency were determined. Under optimal conditions, the grade and total recovery of KCl were 98.31% and 91.43%, respectively, whereas those of NaCl were 96.62% and 90.00%, respectively. Therefore, the combination of evaporative crystallization and flotation can be a promising method for separating soluble chlorides from fly ash.

Differential flotation of pyrite and Arsenopyrite: Effect of pulp aeration and the critical importance of collector concentration

• Differential oxidation of pyrite and arsenopyrite achieved with pulp aeration. • Recovery of pyrite and arsenopyrite was high when singularly treated. • Xanthate adsorption removed high FeOOH removal from arsenopyrite compared to pyrite. • Adsorption of xanthate on heavily oxidised arsenopyrite surface was slow. • Selectivity was lost at high xanthate concentration. Differences in the oxidation rate and extent of model pyrite and arsenopyrite minerals, augmented by pulp aeration, was investigated using dissolved oxygen demand tests and X-ray photoelectron spectroscopy (XPS) analysis. Flotation studies of single mineral admixture coupled with zeta potential measurements, UV–Vis spectroscopy analysis of collector concentration and ex-situ metal ions in solution after collector addition were ascertained to shed light on reasons for observed window for selective flotation. The highest selectivity was achieved with low collector concentration of 1 × 10 -5 M PAX and selectivity index of 5.2 after 6 min flotation with collector concentration playing a critical role in attaining a good selectivity. Fast adsorption of xanthate and simultaneous oxidation to dixanthogen on slightly oxidised pyrite surface starved heavily oxidised arsenopyrite surface of the collector species, at low collector concentration, leading to its depression. The study was extended to the flotation of an auriferous refractory ore where similar observations were made. 62.7% rejection of pyrite was achieved in the staged flotation process.