Gravity Separation Research Articles

Flotation of a South African Low-Grade Banded Iron Formation (BIF)

AbstractDue to declining iron ore grades, low-grade ores with complex mineralogy, namely, banded iron formation (BIF), are being explored to maximize iron ore resources and increase the life of mine. Flotation is the standard global process used for the beneficiation of BIF ores, as it is a complex ore reserve, and liberation is typically achieved below 1 mm. This study focuses on flotation of a South African BIF evaluating its response to different collectors, as well as effect of grind. Since flotation is an expensive process and South Africa ranks high on the production cost curve, pre-concentration via gravity or magnetic separation is performed prior to flotation. Thus, flotation was also performed on a gravity concentrate to determine if a grade suitable for steelmaking (~ 63%) is achievable. The results indicate that the use of an alkyl ether amine-based collector partially neutralized with acetic acid is suitable for separation of hematite from illite and quartz at high pH values. Further optimization tests are being pursued to improve overall recovery and grade.

Judicious combinations of gravity, magnetic, electrostatic separators and microwave heat energy on recovery of ilmenite from Humma lean grade beach placer deposit

Microwave heating is an eco-friendly and novel technique for sintering and heating minerals and materials as it has several advantages in terms of phase transformation, energy efficiency, enhancing speed, process simplicity, improved properties. Such heating provides the composite materials to absorb electromagnetic energy volumetrically and transform into heat and produces larger densities as compared to conventional heating. This study focuses on two main objectives: the recovery of ilmenite through a strategic combination of mineral processing equipment, including a spiral concentrator, followed by magnetic and electrostatic separation, and the enhancement of ilmenite concentrate using microwave heat energy on a cleaner magnetic product, followed by electrostatic separation. Continuous magnetic separation results indicate that among the dry high-intensity belt magnetic separator, box mag wet high-intensity magnetic separator and dry rare earth drum magnetic separators, the rare earth magnetic separator yielded the highest quality product. The application of microwave heat energy before the rare earth drum magnetic separator at 1.4 T, followed by high-tension separation, produced the best grade of ilmenite. The magnetic product obtained after microwave treatment contained 98.6% ilmenite, which was further upgraded to a 99.6% ilmenite concentrate through high-tension separation. Therefore, it is recommended that an effective combination of gravity separation, microwave heat energy, rare earth drum dry magnetic separation and high-tension separation be employed to achieve the highest grade of ilmenite concentrate.

Deep recovery of clean coal from coking middlings: Pre-separation in liquid-solid fluidized bed and subsequent flotation

The coking middlings remaining after the production of coking coal contain a significant amount of clean coal, which has the high economic and environmental value if it can be effectively enriched. To improve resource utilization and avoid the negative environmental impacts of coking middlings, this study evaluated a new comprehensive separation process (i.e., pre-gravity separation in liquid-solid fluidized bed and subsequent flotation) to achieve high-yield recovery of clean coal from coking middlings. Preliminary enrichment by gravity separation achieved a combustible recovery rate, a clean-coal yield, and an ash content of 64.43 %, 49.62 %, and 15.89 %, respectively. This product was ground for 20 min to further dissociate clean coal and inorganic minerals and was further enriched by flotation separation. Under optimal flotation conditions (rotational speed, 2200 rpm; mass of collector, 2 kg/t; mass of frother, 200 g/t; and pulp concentration, 40 g/L), a clean-coal combustible recovery rate of 84.19 % was achieved. Overall, the comprehensive separation process achieved a clean-coal product with a high yield of 38.82 % and low ash content of 9.08 %, which is suitable for use as coking coal for steel plants. The tailings, with an ash content of 51.49 % and a yield of 61.18 %, are suitable as fuel for power plants. Therefore, the comprehensive separation process provides good economic benefits.

Simulation and Experimental Validation of a New Separator Design for a Wide Range of Gas Volume Fractions

Summary For downhole gas-liquid separation, it is crucial to maintain high separation efficiency across a wide range of inlet gas volume fractions. In this paper, we present a numerical investigation into the flow field characteristics and separation mechanism of a new gas-liquid separator that utilizes centrifugal and gravity separation methods. An experimental system was built to validate the accuracy of the numerical model, and the numerical results show similar characteristics with experimental data in phase distribution as well as separation efficiency. In addition, we examine the impact of various operational parameters on the separation performance in this study. The findings indicate that the separator is capable of achieving a separation efficiency of approximately 100% within the inlet gas volume fraction range of 40–80%. Furthermore, it is crucial to control the liquid level to ensure effective separation of gas from the water layer. Altering the inlet liquid flow rate and gas volume fraction has a direct influence on the water content of the gas outlet, resulting in a decrease in separation efficiency. Consequently, optimization of the upper region of the separator is necessary to improve the separation performance.

Waste-to-energy technologies: Integrating anaerobic digestion, microbial electrolysis cells, hydrodynamic cavitation, and electrocoagulation

This study explores a novel integration of electro-physicochemical technologies to generate energy and treat water from combined food waste (FW) and blackwater (FW-BW), with BW containing waste activated sludge with simulated flush water. The FW-BW substrate was gravity-separated and pretreated with hydrodynamic cavitation (HDC). Solids from gravity separation were used for energy generation via anaerobic digestion (AD) alone or integrated with microbial electrolysis cells (AD-MEC). HDC pretreatment had 51.6% more CH4 production in 5 days (266 mL CH4/g VS) and 63% more in 30 days compared to AD without HDC. The CH4 production after 5 days of digestion with HDC pretreatment (266 mL CH4/g VS) was similar to the amount produced without HDC over 30 days (263 mL CH4/g VS). Using MEC increased CH4 production by 12.7% compared to AD-only. The liquids from gravity separation were treated with electrocoagulation (EC) at 15 V (90 min), which removed 96.2% of the chemical oxygen demand (COD) and 100% of the total suspended solids. The pilot scale design indicates that the AD-MEC and EC units would generate 1.4 times more energy than energy consumed through applying these novel technologies. These findings demonstration the applications of four technologies (HDC, AD, MEC, and EC) in an energy-efficient waste management approach, producing bioenergy and cleaner water for low-tier use, especially in areas lacking traditional waste treatment options.

Exploring Low-Grade Iron Ore Beneficiation Techniques: A Comprehensive Review

The beneficiation of low-grade iron ores is a key research and development topic in the mineral processing industry. The gradual exhaustion of high-grade iron ore reserves, and rising consumer iron and steel demand globally necessitate efficient low-quality iron ore beneficiation to meet steelmaking quality requirements. This comprehensive review explores various beneficiation techniques for low-quality iron ore, focusing on conventional methods including comminution, froth flotation and gravity separation. This article discusses the principles, processes, and equipment used in these techniques and highlights recent advancements and research efforts in the field. This review also emphasizes the importance of effective beneficiation processes in enhancing economic viability, sustainable resource management, and environmental conservation. Furthermore, it presents a case study of iron ore deposits in Botswana, highlighting the potential economic growth and sustainable development that can be achieved by maximizing resource utilization through reductive roasting, followed by magnetic separation of iron ore using semi-bituminous coal as a reductant. Overall, this review provides valuable insights into low-grade iron ore beneficiation techniques and their significance in meeting the growing demand for high-quality iron and steel products.

Short overview about iron ore beneficiation: a case study in recovering the iron ore from the tailing pond of the Kip-Tuoc processing plant

Iron is a critical metal for many fields of life and industry. The iron-containing minerals are recovered from the iron run-of-mine (ROM) ore and the tailing pond (TP) of the previous processes. The minerals containing iron are hematite, magnetite, goethite, maghemite, etc. In addition, the invaluable minerals and gangue normally are quartz, kaolinite, gibbsite, pyrite, dolomite, chlorite, etc. Many methods to upgrade the iron content as well as separating the iron minerals and gangue are applied. Those technologies are magnetic separation, gravity separation, flotation, chemical separation, thermal beneficiation, or even the application of biotechnology. In Vietnam, there are many technological research projects on iron ore beneficiation and processing. The main technologies are washing and scrubbing methods, magnetizing roasting combined with a magnetic separator, spiral and magnetic separator, flotation, etc. The article shows a short review of the main methods in order to treat the type of raw material as well as some current applied technology in Vietnam. Based on the knowledge, a study to recover the iron of Kip-Tuoc tailing from the tailing pond is presented. The applied technology is the combination of a trommel screen, spiral and shaking table. The result showed that by applying the rational method and carefully controlling the operational parameters, the iron ore (from the tailing pond with 14.28% Fe) recovered up to 57.57% at the 59.49% Fe grade content. The iron content is suitable for feeding to the blast furnaces in Vietnam. Through the research results, a flowsheet for iron recovery at the tailing pond of the Kip Tuoc beneficiation plant is proposed and scaled up to industrial production's next step.

Comparative processing studies of the Arkachan deposit gold-bearing ores using dry separation and classical wet gravity separation methods

Comparative processing studies of the Arkachan deposit gold-bearing ores using dry separation and classical wet gravity separation methods

Characterization, potential valuable metals recovery and remediation of historic wolframite mining waste

The understanding of tungsten (W) mineral weathering and mobilization in nature remains limited due to W being a transition element with a wide range of oxidation states, which enables it to form a variety of complex chemical compounds. This study examined W mining waste at the abandoned Wolfram Camp mine in North Queensland, Australia, to address this gap. The mineralogical analysis showed the W tailings primarily consisted of silicates, including quartz, illite/mica, plagioclase, and K-Feldspar, with low WO3 content. Static acid mine drainage (AMD) tests indicated most tailings were non-acid forming, while groundwater samples exhibited acidification, with pH ranging from 3.8 to 5.2. The reprocessing trials using gravity separation and bioleaching demonstrated promising results, suggesting both techniques could effectively recover resource and decontaminate the mining waste. The gravity separation reprocessing test has successfully recovered 48.4% W from the tailings, with the resulting W concentrate achieving a 21.6% WO3 grade. On the other hand, the bioleaching reprocessing exhibited a remarkable 44-fold enrichment of W from the tailings, with 2.2% W in the AMD sediment. Synchrotron-based XFM/μ-XANES imaging analysis revealed significant wolframite weathering in reprocessed W concentrates. This study proposed a comprehensive approach, integrating environmental remediation and resource recovery technologies, to repurpose abandoned W mining waste. Passive treatment appears to be an economical option for remediating abandoned W mine sites. The findings provide valuable insights for sustainable W mining waste management and the rehabilitation of the abandoned Wolfram Camp W mine site.

Study on the influence of baffle height and angle on the performance of coarse powder separator in power plant based on CFD-DPM method

In this study, the two-phase motion characteristics in a coarse powder separator were investigated using computational fluid dynamics (CFD) method, discrete particle model (DPM) and isokinetic sampling experimental method, and the structure of the coarse powder separator was optimized to improve the efficiency of the separator. The results showed that the particle separation in different separation zones was also dominated by gravity separation and centrifugal separation, respectively. When the baffle angle was increased from 20° to 60° at a low mounting height, the tangential velocity in the separation zone was reduced by 67 % and the axial velocity was increased by 33 %. The effects of the baffle angle on the tangential and axial velocities were weakened with the rise of the baffles mounting height. The optimum operating condition of the chosen powder separator involved a baffle angle α 30°, a baffle height H = 6.27 m, and a inlet velocity v = 19.3 m/s. The fineness of coal powder at the fine powder outlet was reduced by 60 % and the fineness of coal powder at the coarse powder return port was improved by 43 % for the optimized model compared with the original coarse powder separator.

Tellurium Enrichment in Copper Tailings: A Mineralogical and Processing Study

As the global demand for tellurium (Te) increases, it is crucial to develop efficient recovery methods that consider existing supply streams. This research combines gravity separation and froth flotation processes to enhance the recovery of Te minerals from tailings produced during the beneficiation of copper porphyry ores. Prior to processing, a systematic and comprehensive characterization study of copper tailing (CT) samples was conducted to examine the deportment of Te minerals in different mineral phases and to understand their locking and liberation behavior. Characterization techniques included inductively coupled plasma mass spectrometry (ICP-MS) and TESCAN’s integrated mineral analysis (TIMA). Copper tailing characterization showed that minerals with gold (Au), silver (Ag), bismuth (Bi), and Te were present in various forms, including native Au, electrum, tellurides, and sulfosalts. TIMA revealed that >90% of these minerals were primarily hosted in pyrite as less than 10 µm inclusions in the CT. TIMA also revealed that Te minerals exhibited fine-grained liberation of less than 20 μm. Moreover, TIMA results showed that >80% of mica and other silicate minerals were concentrated in size fractions < 38 μm, suggesting that desliming processes would positively impact Te enrichment. The results from the processing tests showed a Te recovery rate of ~77% and a Te enrichment ratio of 13 when using the combination of gravity separation and froth flotation at 90 g/t xanthate collector and 50 g/t glycol frother. The findings from this study show a significant potential for Te recovery from unconventional sources if appropriate physical beneficiation approaches are adopted.

A new approach for improving the properties of tailings sand autoclaved aerated concrete - From a mineralogical perspective

This study proposed a new method to improve the performance of tailings sand autoclaved aerated concrete (SAAC). Firstly, high silicon iron tailings from the Anqian area and low silicon molybdenum tailings from the Weinan area were selected, and the mineral composition of these two tailings was analyzed. Then, the single mineral in the two tailings were used instead of siliceous raw materials to prepare mineral autoclaved concrete (MAC). The autoclaved reactivities of these minerals were analyzed through compressive strength, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM), and which minerals were beneficial for the preparation of SAAC were determined. On this basis, magnetic separation and gravity-magnetic separation processes were used to pretreat Anqian iron tailings and Weinan molybdenum tailings, respectively. Finally, the effectiveness of this method was verified by preparing SAAC made with tailings before and after pretreated. The tested results showed that the autoclaved activities of siliceous minerals were in the following order: quartz hornblende, feldspar, chlorite, while the montmorillonite and biotite, and the metal mine (hematite and pyrite) did not have autoclaved reactivities. The main crystalline phase of hydration products in MAC made with single mineral without autoclaved reactivities were C-S-H, Ca(OH)2, CaCO3, and hibschite, and that in MAC made with quartz, hornblende, feldspar, and chlorite were C-S-H, tobermorite, Ca(OH)2, CaCO3, and hibschite (except quartz). After 1.3 T strong magnetic separation treatment, the content of Fe2O3 in iron tailings decreased from 11.11 % to 4.16 %, and the compressive strength of SAAC made with iron tailings with magnetic separation pretreated increased by 11.43 % comparted to that of SAAC made with original iron tailings. After gravity separation and 1.1 T strong magnetic separation pretreated, the content of SiO2 in molybdenum tailings increased from 63.97 % to 84.03 %, and the mineral content of biotite decreased from 40.5 % to 11.2 %. The compressive strength of SAAC made with molybdenum tailings with gravity-magnetic separation pretreated increased by 24.09 % comparted to that of SAAC made with original molybdenum tailings.

Gold occurrence in the footwall of the Lappberget Deposit, Garpenberg Mine, Sweden: Implications for recovery efficiency

By-product metals have a significant potential to bring additional economic benefits to mines. However, a detailed characterization of their distribution is generally required to fulfill this potential and should preferably be integrated into a geometallurgical assessment. This contribution presents a detailed mineralogical and textural investigation of gold-bearing phases at the footwall of the Zn–Pb–Ag–(Cu–Au) Lappberget Deposit, Garpenberg Mine, Sweden, using optical microscopy, scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), electron probe microanalysis (EPMA), laser ablation-inductively coupled plasma mass spectrometer (LA-ICPMS), and bulk chemical analysis applied to drill core and Knelson concentrator samples. Gold is a by-product at the Garpenberg mine, but it is unclear how the mineralogy, occurrence, and distribution of gold-bearing phases impact on gold recoveries during mineral processing. Our results show that Au-dominant electrum is the most abundant gold-bearing phase in the footwall of the Lappberget deposit, occurring strongly associated to sulfides in a variety of textures and grain sizes. Electrum grains commonly occur within sulfide borders, as inclusions, intergrowth and overgrowths of chalcopyrite, pyrite, galena, sphalerite, and pyrrhotite. Gangue minerals may also contain disseminated electrum and inclusions. Electrum grain sizes range from ∼5 µm to 300 µm, predominantly below 100 µm. The potential of sulfide lattice-bound invisible gold in the form of solid-solution gold and colloidal gold was also investigated, showing Au depletion within the analyzed sulfide carriers. The analysis of the concentrate samples from the Knelson gravity concentrator showed 584 and 431 ppm of gold content. High degree of liberation is observed among the gold-bearing phases in the concentrate, and gold recovery is highest among fractions coarser than 106 µm mesh. Pyrite and galena are the most abundant minerals in the concentrate samples. The gold-bearing phases were categorized based on its mineralogy, texture, grain size, and association and their influence on gold processing, especially textures and grain size, which implicates its liberation in milling and recovery by the gravity separator.

Improvement in Storage Stability and Physicochemical Properties of Whole-Grain Highland Barley Pulp Prepared by a Novel Industry-Scale Microfluidizer System in Comparison with Colloid Milling.

The aim of this study was to assess the advantages of an industry-scale microfluidizer system (ISMS) to prepare whole-grain highland barley pulp (WHBP) compared with colloid milling. Storage stability was evaluated by particle size, gravity separation stability, and rheological properties, as well as the microstructure observation by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLMS). The results showed that colloid milling failed to effectively homogenize the material, while ISMS sample surfaces were compact and smooth at higher pressures according to visual observation and SEM. The Turbiscan stability index of WHBP by ISMS was much lower as a result of colloid milling, demonstrating ISMS can improve WHBP stability. WHBP by colloid milling displayed a three-peak particle size distribution pattern, while a single-peak pattern was evident after ISMS treatment. A higher shear rate decreased the apparent viscosity, suggesting that WHBP was a shear-thinning fluid. According to CLMS, ISMS can successfully improve homogenization by disrupting the structures of oil bodies, proteins, and starches. The WHBP prepared by ISMS exhibited a higher β-glucan level than that prepared by colloid milling, and showed a significant increase in β-glucan level with ISMS pressure. These findings indicate that using ISMS to produce WHBP is viable for enhancing its storage stability and nutritional value.

Highly efficient and eco-friendly process for selective recovery of copper from waste printed circuit boards via pyrolysis and ammoniacal solvoleaching

This study proposes a process combining pyrolysis and ammoniacal solvoleaching to selectively recover Cu from waste printed circuit boards (WPCBs). Optimal pyrolysis conditions were determined by investigating parameters such as temperature, heating rate, N2 flow rate, holding time and particle size. Under the conditions: 500 °C temperature, 20 °C/min heating rate, 0.3 L/min N2 flow rate, 10 min time and +9.50 mm particle size, ∼25% of weight loss was obtained. The pyrolyzed mass underwent further physical separation process involving impact crushing, magnetic- and gravity separations to enrich metals into a concentrate. Copper in the resulting concentrate was selectively extracted using a one-stage ammoniacal leaching and solvent extraction process (ammoniacal solvoleaching), employing an oxime-based organic extractant, LIX 84-I with a small volume of NH4OH. Ammoniacal solvoleaching was optimized by considering parameters such as stirring speed, time, LIX 84-I concentration, volume of aqueous ammonia, temperature and pulp density. Under the following conditions: 500 rpm, 0.3/0.3/10 (g/mL/mL) of sample/NH4OH/LIX 84-I (0.8 M), 3 h time and 25 °C temperature, quantitative Cu dissolution was achieved after two-stage solvoleaching. Cu solvoleaching followed the Avrami model, with an activation energy of 28.95 kJ/mol in the temperature range 15–45 °C (298–318 K) for the mixed control mechanism. LIX 84-I could be recycled without loss of extraction performance. Cu concentration was further enriched during stripping stage using H2SO4. A flowsheet for the sustainable metal recovery from WPCBs was developed.

Sustainable apple juice concentration: A fusion of pasteurization and membrane distillation

Apple juice concentrate offers significant advantages in terms of transportation and storage. However, the conventional concentration method is known for its high energy consumption and has been observed to negatively affect the quality of the apple juice. This study investigated an efficient and sustainable process combining pasteurization and membrane distillation (MD) for apple juice concentration. The effects of operational conditions on flux, membrane fouling control, product quality and energy consumption were evaluated. When a single MD was used as a pre-concentration method, apple juice could be concentrated by more than 3.65 times. The final product with a total soluble solids (TSS) content of 60 °Brix after VE re-concentration has better quality, especially in terms of acidity and total phenols content. The flux recovery rate of hydraulic washing can reach more than 96 %. The MD pre-concentration process used uncooled pasteurized apple juice as the feed reduced the energy consumption by 60.6 % compared with thermal concentration.

Advancing Water Deoiling Efficiency in Petroleum Production: A Comprehensive Case Study of Hybrid Flotation Technology Integration

_ The efficient management of increasing water cuts in oil fields is paramount for sustaining profitability and minimizing environmental impact. This article presents a comprehensive case study conducted by Saudi Aramco, focusing on the integration of hybrid flotation technology into a gravity water/oil separator (WOSEP) to enhance deoiling efficiency and reduce operational costs and carbon emissions. The retrofit involved merging enhanced gravity separation with induced gas flotation (IGF) within the same vessel, resulting in significant improvements in deoiling capacity, outlet oil-in-water content reduction, and operational efficiency. Detailed insights into the design, operation, and performance of hybrid flotation systems are provided, offering valuable guidance for similar initiatives in the petroleum industry. Introduction Petroleum production facilities face escalating challenges with increasing water-production rates during crude-oil extraction, particularly in waterflooding operations for secondary oil recovery. This trend not only escalates operational costs but also intensifies environmental concerns, particularly regarding energy consumption and carbon emissions associated with water-handling processes. In response to these challenges, Saudi Aramco embarked on a pioneering initiative to enhance water-deoiling efficiency by integrating hybrid flotation technology into a conventional gravity WOSEP. This case study presents a comprehensive analysis of the design, implementation, and outcomes of this transformative project, offering valuable insights for the broader petroleum industry. Methodology The upgrade process commenced with an assessment of the existing WOSEP system and its operational challenges. Recognizing the impending capacity constraints and escalating oil-in-water content, Saudi Aramco’s engineering team opted for a holistic approach that combined enhanced gravity separation with IGF within the same vessel. The retrofit involved reconfiguring the internal components of the WOSEP to accommodate the hybrid flotation system, including the installation of advanced plate-pack internals for gravity separation and the integration of IGF cells for additional oil removal. Rigorous testing and optimization procedures were conducted to ensure seamless integration and optimal performance of the hybrid system. Gas/Oil Separation Plant Process Description In a typical gas/oil separation plant, the initial phase involves the extraction of crude oil, associated gas, and produced water from wells via a production manifold. These constituents are then directed to a three-phase separator, also known as a high-pressure production trap (HPPT). In the HPPT, free water droplets are separated from the oil through gravity separation, aided by demulsifier injection at the production header. The separated free water is discharged to a WOSEP, typically a gravity separator, for deoiling.

Enhanced separation of oil-in-water emulsion by cyclic penetration of emulsion droplets through an oil layer

The separation of emulsion components is a typical heterogeneous phase separation process. This process can be promoted by coalescence of the dispersed phase droplets. However, the coalescence would be inhibited due to the interface between the continuous and dispersed phases. The separation efficiency can be increased by increasing the probability of collisions between the droplets, and this can be realized by increasing the area of contact among the dispersed phase droplets. In this study, a new enhanced separation method involving the circulation of emulsion droplets containing an emulsified oil phase through an oil layer is proposed. The migration of the emulsified oil phase from the millimeter-sized droplets to the oil layer was studied. This migration enabled efficient separation of the oil and water phases, and this process was assessed by using a dyeing agent in the oil phase and by monitoring the variation in the turbidity. The influence of main factors such as the circulating droplet size, thickness of the oil layer, and effect of the circulation rate on the separation was determined. The turbidity of the emulsion reduced from 394.33 NTU to 10.98 NTU, with a separation efficiency of 97.22 % under the optimum operation conditions. The linear fitting relationship for the main factors that affect separation with the duration or number of circulation cycles was obtained. The results indicate that the novel strategy of using an additional oil layer and circulating emulsion droplets through it is promising for oil–water separation, especially via gravity separation.

A theoretical and experimental investigation of continuous oil–water gravity separation

In this study, we have developed a mathematical model for a three-phase separator. The model consists of two sections: the inlet section and the separation section, separated by a perforated calming baffle. In the inlet section, two dispersion layers undergo droplet size evolution due to turbulent breakage and coalescence, described by a spatially homogeneous PBE. In the separation section, the two dispersion layers flow alongside each other and interact at an interface. The volumetric flow and velocity profiles are influenced by interfacial coalescence, with considerations for plug and laminar flow assumptions. The model incorporates droplet gravity-driven transport using the Kumar and Hartland model, binary and interfacial coalescence employing a film drainage model, and an effective diffusion term to account for the formation of the dense packed layer which ensures a physical volume fraction range of 0–1. Steady-state and transient numerical solvers are developed to solve the resulting advection–diffusion equations. Additionally, a series of experiments were conducted using a lab-scale multi-parallel pipes separator to investigate the impact of varying volume fractions and flow rates on the separation efficiency of the equipment. The model results are compared with the experimental data which shows relatively good agreement.

Optimization of the coagulation-flocculation process using response surface methodology for wastewater pretreatment generated by vegetable oil refineries: A path towards environmental sustainability

Treating complex and variable wastewater, mainly from refineries with diverse pollutants, presents multifaceted challenges. However, through diligent management and the implementation of efficient treatment strategies, the effectiveness of wastewater treatment can be maintained, ensuring the protection of the environment and public health. This study aims to enhance the coagulation-flocculation process for pretreated wastewater from vegetable oil refineries (VORW). Findings reveal that pretreatment through gravity separation influences coagulation-flocculation efficiency for oil-containing wastewater. Employing a central composite design (CCD), the study examines the effects of pH, coagulant/flocculant dosage, and settling time on turbidity and chemical oxygen demand removal (COD). Each factor significantly impacts results, with pH exerting the most substantial influence. ANOVA results validate the statistical significance of the selected models, aligning with experimental data for each response. The study demonstrates a satisfactory model fit, supported by high adjusted coefficients of determination (R2Adj = 96.59 % for turbidity and R2Adj = 93.61 % for COD). Optimal parameters—pH 7.5, coagulant dose 110 mg/L, flocculant dose 0.55 ml/L, and settling time 15 min—yield a 96 % reduction in turbidity and a 95 % reduction in COD. Furthermore, the combined treatment of flotation followed by coagulation-flocculation proves highly effective in achieving significant pollutant removal, showcasing the practical application of the design of experiments (DOE) in optimizing wastewater treatment processes.