Selective Flocculation Research Articles

Carbon-ash separation of coal gasification fine slag by flocculation-flotation process

ABSTRACT Coal gasification slag (CGFS), which was a bulk solid waste in coal chemical industry, shows great application potential in the preparation of silica microspheres, zeolites ceramic materials, etc. However, its high residual carbon characteristics hinder to its development. Decarburization is a necessary precondition for the effective utilization of CGFS. The efficient separation of carbon or ash from CGFS remains a challenge due to its ultra-fine particle size. This work provides a novel flocculation-flotation process to achieve the complete carbon-ash separation of CGFS. The addition of anionic polyacrylamide (APAM) or polyethylene oxide (PEO) had positive effect on the flotation of CGFS, especially for APAM. With APAM dosage of 50 g/t, the ash content of carbon slag and ash slag were 59.04% and 97.11%, respectively. In this process, the zeta potential of carbon slag and ash slag decreased from −17.43 and −11.77 mV to −23.45 and −29.80 mV, respectively. The greater change of zeta potential of ash slag indicates its stronger adsorption of APAM, leading to the higher flocculation trend of ash particles than that of carbon slag. APAM has selective flocculation effect on ash slag, which contributed to reduce the mechanical entrainment during flotation, thereby achieving complete carbon-ash separation of CGFS.

Implementation of selective flocculation process in drilling operations to optimize per-flex fluid volume consumption and reduce the carbon footprint

One of the significant challenges faced by the oil and gas industry is the reduction of the carbon footprint associated with drilling operations. This paper presents a case study on the implementation of a selective flocculation process to optimize the consumption of PER-FLEX fluid, a high-performance water-based mud (WBM), during drilling operations. Conducted in a Colombian oil field, this study demonstrates how the adjustment of polymer concentration and injection rates in the flocculation process can reduce the need for fluid dilution, thereby decreasing water and chemical consumption, waste production, and CO2 equivalent (CO2 eq.) emissions. The findings highlight the effectiveness of selective flocculation in enhancing drilling fluid performance and contributing to sustainability goals.

Experimental and theoretical investigations into the surface chemical properties and separation of serpentine from quartz using xanthomonas campestris as a selective flocculant

Separation of fine serpentine (SPT) from quartz (QZ) both of d80 close to 20 µm using an eco-friendly microbial exo-polysaccharide, xanthomonas campestris (XCT), as a selective flocculant for SPT was conducted experimentally and substantiated theoretically. The adsorption of XCT onto SPT was observed to decrease with increase in pH, whereas that of QZ was nearly nil beyond pH 2.1. Zeta potential of SPT in presence of XCT decreased with increase in pH further attesting to the adsorption and anionicity of XCT. The FTIR studies confirmed the interaction of XCT with SPT in presence of sodium hexametaphosphate. The nature of intermolecular interactions present in complexes formed on SPT surface was revealed by quantum theory of atoms in molecules to be non-covalent. The electron density difference plot conducted on formed complexes indicated that electrons drifted from XCT to the surface of SPT. Selective flocculation SPT-QZ (1:1) mixture conducted at pH 6 and pH 7.5 in presence of 4 mg/L and 2 mg/L of sodium hexametaphosphate coupled with 100 mg/L of XCT yielded separation efficiency and selectivity ratio of 96.5 % and 71.2, respectively, after three desliming stages. Therefore, XCT is a potential selective flocculant for serpentine.

Integrating selective flocculation techniques for enhanced efficiency in manufacturing processes: A novel approach through artificial neural network modeling

The use of medium and low-grade iron ore is gradually becoming more important due to the depletion of high-grade iron ore reserves and stringent environmental acts/rules. Slimes from iron ore washing were discarded in tailing dams; however, there is currently consideration for recovering iron values from ultra-fines as well. There are enormous fine dumps that are still unutilised. Hence, this study attempt to delve the optimization of iron ore slimes an indeed requirement for manufacturing and design in industries. Leveraging a flocculation process, coupled with the implementation of an Artificial Neural Network (ANN) predictive model, the Kiriburu processing plant serves as the primary source for iron ore slime samples. Chemical analyses of the collected iron samples reveal a composition featuring 58.24 % iron content, 3.47 % Al2O3, 4.72 % SiO2, and 5.18 % LOI (Loss on Ignition). The investigation explores the performance of the flocculation technique under varying pH levels, different pulp densities, and diverse flocculant dosages. Furthermore, the varying parameters selected are pH from 6 to 11, pulp density from 1 % to 15 %, and flocculant dose from 0.03 to 0.27 mg/g. The study's findings showcase a substantial improvement in the Fe grade of iron ore, escalating from 58.24 % to 66.12 %, with an impressive recovery rate of 82.54 % achieved using a flocculant dosage of 0.09 mg/g at pH 10. Additionally, a performance assessment of the selective flocculation method for iron ore slimes is conducted using an ANN predictive model, with recovery as the pivotal parameter. The input parameters for this model encompass pH, pulp density, and flocculant dosages. Employing a three-layer ANN model with a 3–3–1 architecture and utilizing feed-forward back propagation, the study demonstrates a close alignment between predicted values and experimental data, confirming the model's effectiveness for practical manufacturing applications. Information regarding the potential applications of the model's iron ore slime beneficiation efficacy for the manufacturing sector should be considered. This could entail lower waste, more effectiveness, or cost savings. Emphasise any possible ramifications for sustainability or the environment that would make the study pertinent in a larger perspective.

Selective Flocculation and H2O2-Free Oxidative Etching-Based Synthesis of Highly Monodisperse Ag Nanospheres for Uniform Quantum Dot Photoluminescence-Enhancing Plasmonic Cavity Applications.

Ag nanoparticles have garnered significant attention for their excellent plasmonic properties and potential use as plasmonic cavities, primarily because of their intrinsically low ohmic losses and optical properties in the visible range. These are particularly crucial in systems involving quantum dots that absorb light at low wavelengths, where the need for a high threshold energy of interband transitions necessitates the incorporation of Ag nanostructures. However, the synthesis of Ag nanoparticles still encounters challenges in achieving structural uniformity and monodispersity, along with chemical stability, consequentially inducing inconsistent and poorly reliable optical responses. Here, we present a two-step approach for synthesizing highly uniform spherical Ag nanoparticles involving depletion-induced flocculation and Cu(II)-mediated oxidative etching. We found that the selective flocculation of multitwinned Ag nanocrystals significantly enhances the uniformity of the resulting Ag nanostructures, leaving behind only single-crystalline and single-twinned nanostructures. Subsequent oxidative etching, in which cupric ions are directly involved in the reaction, was designed based on Pourbaix diagrams to proceed following thermodynamically favorable states and circumvent the generation of reactive chemical species such as H2O2. This leads to perfectly spherical shapes of final Ag nanoparticles with a synthetic yield of 99.5% and additionally reduces the overall reaction time. Furthermore, we explore the potential applications of these monodisperse Ag nanospheres as uniform plasmonic cavities. The fabricated Ag nanosphere films uniformly enhanced the photoluminescence of InP/ZnSe/ZnS quantum dots, showcasing their capabilities in exhibiting consistent plasmonic responses across a large area.

APPLICATION OF THE METHOD OF FOCCULATION AND SELECTIVE FLOCCULATION METHODS IN THE TREATMENT OF INDUSTRIAL SLUDGE FROM THE IRON ORE CONCENTRATION PROCESS

The paper presents research on the use of flocculation and selective flocculation methods in the treatment of industrial sludge, generated in the processing of iron ore minerals. The large quantity of fine sized sludge disposed as final waste still contains a relatively high concentration of iron minerals, as well as quartz and clay minerals, as tailings. It is both an environmental and an economic problem. In both cases it is useful to use flocculants to accelerate settling of fine particles. The action of flocculants, which accelerate settling, can be selective or non-selective. The research was aimed at determining the conditions under which selectivity can be achieved when using some commercial flocculants.

Influence of pH and ionic strength on the floc-magnetic separation: Selective flocculation of fine iron ore

This study proposes the application of floc-magnetic separation to enhance the recovery of fine iron (Fe) ores from the Musan mine. The X-ray diffraction analysis revealed the predominant composition of raw samples to be magnetite (Fe3O4) and quartz (SiO2). Conventional magnetic separation indicated an increasing efficiency of Fe separation with increasing magnetic intensity. However, this method exhibited shortcomings in effectively separating fine particles. Consequently, supplementary floc-magnetic separation was undertaken. The introduction of sodium oleate and kerosene as flocculants increased the efficiency of Fe separation. This enhancement was attributed to the alteration of the hydrophobic surface properties of fine iron particles, leading to the formation of larger aggregates that could be readily separated. Furthermore, floc-magnetic separation was performed in the presence of salt solutions. The heightened ionic strength facilitated the aggregation of iron fine particles by compressing the electrical double layer around them. This reduction in the energy barrier between iron fine particles and flocculants facilitated a more favorable interaction in the presence of salt solutions than in their absence. The experimental findings indicate that the floc-magnetic separation method reinforced by the addition of flocculants and salt solutions demonstrates enhanced efficiency in separating iron minerals from raw ores. This is particularly notable for addressing the challenge posed by fine particles that remained unresolved in conventional magnetic separation processes.

Selective flocculation and recovery of chrome from plants limes using starch and sodium oleate as flocculants

Selective flocculation and recovery of chrome from plants limes using starch and sodium oleate as flocculants

A novel pH-responsive flocculant for efficient separation and recovery of Cu and Mo from secondary resources via selective flocculation-flotation

A novel pH-responsive flocculant, P(AM-DEA-DPL) (PADD), was first used for efficient separation and recovery of Cu and Mo from secondary resources via selective flocculation-flotation. The selective flocculation behavior, flocculation-flotation and deflocculation of fine molybdenite, chalcopyrite and quartz were researched by single and artificial mixed ore. Moreover, fourier transform infrared (FTIR) spectroscopy, zeta potential, contact angle and fluorescence microscope were utilized to reveal the flocculation and deflocculation mechanism. The results showed that PADD had an excellent selective flocculation of fine molybdenite and chalcopyrite particles in the presence of sodium hexametaphosphate (SHMP), which originated from the bridging molecular chains, electrostatic adsorption and hydrophobic interaction among PADD and the fine hydrophobic particles. Moreover, the floated flocs obtained from the artificial mixed ore of fine molybdenite, chalcopyrite and quartz could be well dissociated to small size particles when the slurry pH was adjusted to 6.0, resulting from the enhanced deprotonation effect and electronegativity of PADD. It would facilitate the further separation of molybdenite and chalcopyrite from the mixed concentrate via flotation. Therefore, PADD hold a broad application prospect with the efficiently recovering and further separating molybdenite and chalcopyrite from secondary resources containing Cu and Mo.

A Study on the Effect of Particle Size on Li-Ion Battery Recycling via Flotation and Perspectives on Selective Flocculation

The recycling of active materials from Li-ion batteries (LIBs) via froth flotation has gained interest recently. To date, recycled graphite has not been pure enough for direct reuse in LIB manufacturing. The present work studied the effect of particle sizes on the grade of recycled graphite. Furthermore, selective flocculation is proposed as a novel approach to control particle sizes and thus improve graphite grade by preventing the entrainment of cathode components. Zeta potential and particle size measurements were performed to find an optimal pH for electrically selective flocculation and to study the interaction of flocculants, respectively. Batch flotation experiments were performed to investigate the effect of particle size on the purity of the recovered graphite. Results suggested that, in the absence of ultrafine fine particles, battery-grade graphite of 99.4% purity could be recovered. In the presence of ultrafine particles, a grade of 98.2% was observed. Flocculating the ultrafine feed increased the grade to 98.4%, although a drop in recovery was observed. By applying a dispersant in addition to a flocculant, the recovery could be increased while maintaining a 98.4% grade. Branched flocculants provided improved selectivity over linear flocculants. The results suggest that particle size needs to be controlled for battery-grade graphite to be recovered.

New insights into the interaction between monomers from acrylamide-based polymeric flocculants and montmorillonite: A DFT study

Montmorillonite (MMT) is the main clay mineral in mine wastewater and also the most difficult fine particles to treat. In order to explore how common acrylamide-based organic polymeric flocculants interact with montmorillonite surfaces on micro scale, three kinds of active monomers of acrylamide-based organic polymeric flocculants were selected, and the microcosmic mechanism between the three active monomers and MMT (001) and (010) surfaces was analyzed by density functional theory (DFT). The simulation results of adsorption energy, charge analysis and partial electronic density of states show that the three studied monomers can be adsorbed on the (001) and (010) surfaces and 2-acryloyloxyethyltrimethyl-ammonium chloride (DAC) adsorbed more strongly than 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), which in turn adsorbed more strongly than acrylamide (AM). The adsorption on (001) surface is more favorable because the three active monomers can be stably adsorbed at both the easy and hard hydration sites on (001) surface, while only stably adsorbed at the hard hydration sites on (010) surface. After adsorption, the stronger the delocalization of the PDOS on the same surface, the shorter the hydrogen bond length and the larger the population value. Electrostatic interaction dominates the adsorption process on the Na-MMT (001) surface, whereas hydrogen bonding dominates the adsorption mechanism on the Na-MMT (010) surface. This research provides theoretical guidance for the design and synthesis of novel selective flocculants.

Macromolecular selective flocculant derived from functionalized starch towards beneficiation of low-quality iron ore: Atomistic simulations and experimental studies

In this work, a selective flocculant (St-Meth-Co-PAM) has been developed through functionalization of starch (St). At first, starch methacrylate (St-Meth) has been synthesized by the simple esterification reaction of starch and methacrylic anhydride (MAh) and then a 3D network like formation has been developed by free radical polymerization among St-Meth molecules with simultaneous grafting of polyacrylamide chain on the St-Meth backbone. Several characterization techniques have been employed to check the development of the selective flocculant. From the selective flocculation study, it has been established that the material exhibits very good selective flocculation efficiency. From theoretical study, it has been confirmed that the material can form coordination with the hematite particles selectively. The synthesized material can be used in industrial purpose as it has been displayed very high settling speed rather than the conventional selective flocculant. SynopsisDuring the beneficiation process of iron ore, a huge amount of extremely fine particles having size lower than 45 µm, called as slimes are produced. These slimes are generally deposited in large tailing ponds, which acquire large area and also it grabs immense volume of water that resulted in environmental pollution. This water cannot be used for another purpose. By virtue of this selective flocculation technique, the water can be reused and environmental pollution may be diminished.

Sustainable Use of Copper Resources: Beneficiation of Low-Grade Copper Ores

The global market has announced copper as a modern energy metal and finds its extensive utilization in the construction industry, electrical wiring, power transmission lines, alloying, anticorrosive coating, heat exchangers, refrigeration tubing, etc. Copper ore is primarily beneficiated from sulphide mineral deposits. Due to high-grade copper sulphide deposit exhaustion, the focus has now shifted towards recovery from different lean-grade oxide and mixed ore deposits. The present paper summarizes the utilization of copper as a clean energy mineral and its importance in the current renewable energy sector. Extensive research has been carried out on the flotation of copper sulphide ore as compared to copper oxide and mixed type ores. Besides flotation, other beneficiation techniques (selective flocculation and gravity separation) are also discussed in the present review. A few novel pretreatment methods are currently being studied for copper ore to intensify the separation for higher productivity.

Selective flocculation and floc-flotation of iron bearing mineral slimes

The mineral processing of friable iron ores usually generates ultrafine (smaller than 15 µm) particles, normally called slimes, which usually have a high iron grade and are usually disposed into tailings dam. The traditional mineral process techniques for iron ore do not work efficiently with ultrafines; however, selective flocculation is an alternative to concentrate that fraction. The physical-chemical treatment of iron ore slime was studied here, on a bench scale, based on the scientific foundations of selective flocculation and flotation. Samples of slimes from two Brazilian iron ore processing plants (CEII and VGII) and industrial process waters were used in the tests. Complexometric titration of calcium and magnesium indicated that the process waters were adequate for selective flocculation. Only selective flocculation, even under optimum conditions, did not achieve good results. However, its use prior to flotation led to promising results. The VGII sample has stood out, for which the final concentrate achieved 60.1 % of Fe, the mass recovery was 64.5 % and 13.5 % of Fe in the tailing, resulting selectivity index of 6.58, only with one stage of selective flocculation and one stage of flotation.

Upgradation of Iron Ore Fines and Slime by Selective Flocculation Using Surface-Active Agents, Settling Study, and Characterization of the Beneficiation Waste for Value Addition

Washing of iron ore fines and slime (10% and 25% w/v, slurry concentrations) with two types of surface-active agents (sodium humate (synthesized) and AD 200 (commercial)) at varying concentrations at pH 8 was conducted for ascertaining the efficacy of dispersants in beneficiating the low-grade iron ores. The beneficiation process follows the “selective dispersion-cum-settling technique.” The process results in the formation of a dispersed phase rich in gangue minerals and a settled phase of predominantly active hematite mineral. The stability of dispersed phase (DP) was evaluated by determination of the percentage solid content in the DP. Settling tests were performed. First-order kinetic models have been applied to the dispersion-cum-settling behaviour of both the samples, and evaluated kinetic parameters were found to have good agreement with experimental data. Removal of gangue minerals from iron ore depends on the pH of the slurry, concentration of the slurry, and concentration of the surface-active agent used. The surface-active agents at pH 8 produce ∼1.2–1.5 times more stable suspension in the case of iron ore fines and slimes than that of without surface-active agent. They significantly remove gangue minerals and increase the iron value ∼2–7% with ∼58–74% recovery depending on the experimental conditions. The concentrates collected satisfy the required specifications (Al203/Fe < 0.05 and Al203/Si02 < 1). The gangues in the dispersed phase as characterised by “SEM-EDXA” are mostly clay-bearing minerals like kaolinite, goethite, chlorite, and alumina-silicate minerals. Heat treatment causes distortion of clay minerals present in the dispersed phase and also indicates the complex nature of the gangue minerals.

Studies on Performance Evaluation of Modified Polymer on Iron Ore Fines by Selective Flocculation Process

Studies on Performance Evaluation of Modified Polymer on Iron Ore Fines by Selective Flocculation Process

The flotation of fine hematite by selective flocculation using sodium polyacrylate

• Fine hematite was separated from fine quartz by PAAS flocculation flotation . • The hematite particle size increased by 52% due to PAAS selective flocculation. • The adsorption mechanism of PAAS on the hematite surface was discussed in detail. Fine hematite and quartz are particularly difficult to separate using classic flotation and magnetic separation methods because the particles were very small and readily reported to the wrong product. The effect of sodium polyacrylate (PAAS) on the flotation separation of fine hematite from quartz and its mechanism were investigated by micro-flotation experiments using NaOL as a collector, particle size analysis, zeta potential measurements, FT-IR, SEM analysis as well as XPS analyses. The flotation tests found that the flotation recovery of fine hematite increased observably to 94.51% from 68.69% by adding 4 mg/L PAAS before NaOL at pulp pH 7.3; in the separation of mixed hematite and quartz, the separation efficiencies of fine hematite with and without the addition of the PAAS are 85.71% and 68.84%, respectively. After treatment with the PAAS, the fine hematite was well flocculated so that the average hematite particle size increased to 26.73 μm from 17.69 μm, and the particle size distribution of hematite less than 17 μm decreased to 29.58% from 52.51%. Zeta potential variations indicate that the collector NaOL is able to adsorb on the hematite surface after flocculation by the flocculant PAAS whereas the adsorption of the PAAS on quartz plays an inhibitory role in the adsorption of collector NaOL on the quartz surface, considerably improving the floatability of fine hematite, and thus realizing the effective separation of fine hematite from fine quartz. Furthermore, FT-IR, SEM, and XPS analyses suggest that the flocculant PAAS adsorbs on the hematite surface in a scattered punctiform morphology via a chemical bond in which the Fe 3+ of the hematite surface reacts with the –COO – of PAAS to form dimers, including (RCOO) 2 2– or RCOOH-RCOO - .

Extraction of TiO2 from kaolin deposits in the Central Region, Ghana: An alternative material for the formulation of climate-smart Portland cement

This paper is one of series of papers assessing the suitability of formulating titanium dioxide climate smart Portland cement in developing countries using locally available cementitious material like kaolin. In this paper, authors highlight extraction of titanium dioxide from kaolin deposits in the Central Region, Ghana using selective flocculation techniques and later used to formulate climate-smart cement. Titanium dioxide (TiO2) a photocatalytic ingredient which studies from developed countries have shown that when nano-sized of it is added to cement is able to reduce smog-forming air pollutants, keep surfaces of buildings clean and resist sulphate attack. However, developing countries with weak economies and low technologies are not able to utilize nano-size TiO2 in the formulation of climate-smart cement. It is within this context that this study was undertaken. About 450 g of 53 μm kaolin samples were treated with dispersing agents such as sodium polyacrylate and sodium silicate in excess amount so as to produce maximum deflocculation of the kaolinite particles. The percentage of titanium dioxide extracted ranges from 86.1% for kaolin samples from Saltpond to 91.8% for kaolin samples from Assin Foso respectively; which was later used to formulate climate-smart Portland cement. The ability of the formulated TiO2-ordinary Portland climate smart cement to degrade Rhodamine B dye was tested. Mortar pastes containing various percentages of TiO2-climate smart Portland cement with Rhodamine B dye were exposed to sunlight for 0, 24, 48, 72 and 96 h respectively. The test results indicate that addition of TiO2 extracted from kaolin and used to synthesize climate -smart ordinary Portland cement is able to degrade air pollutants from vehicular exhaust such as PAHs, and as such its use in the construction industry can improve the durability of buildings and for that matter the socio-economic development of the region as well as Ghana as a whole.

Selective flocculation performance of amphiphilic quaternary ammonium salt in kaolin and bentonite suspensions

In the present work, a type of amphiphilic alkyl quaternary ammonium salt, dimethyl distearylammonium chloride (DAC), was introduced and used as a selective flocculant in kaolin and bentonite suspensions. The selective flocculation property was evaluated by turbidity tests, floc size measurements, zeta potential variation, contact angle measurements and scanning electron microscopy (SEM) observation. The results indicated that an appropriate amount of DAC could achieve selective flocculation at alkaline condition. Based on the experimental facts from size, zeta potential and contact angle measurements, the different flocculation mechanisms of kaolin and bentonite were also investigated. For kaolin suspension, charge neutralization was quite predominant. At different pH level, a low dosage (45 mg/L) of DAC always caused excellent flocculation while high dosage (> 45 mg/L) gradually leaded to restabilization owing to the electrostatic exclusion. For bentonite suspension, bridging effect played the key role. Under acidic condition, bentonite particle always performed good flocculation phenomena at different DAC dosages. But it would gradually lead to enhanced flocculation efficiency from poor to good with increasing the dosage of DAC under alkaline condition. As a result, DAC showed the selective flocculation performance by controlling the dosage of DAC and pH, which provided us the guidance on designing more effective selective flocculant in complex clay mixture system.

Ultrasonic treatment improves the performance of starch as depressant for hematite flotation

In this study, ultrasonic treatment was introduced to enhance the depressive performance of starch in the reverse flotation separation of fine hematite from quartz. It was found that after ultrasonic treatment, starch was not only able to impart a higher surface wettability of hematite, but also better reduced the degree of entrainment of fine hematite, both of which alleviated the loss of hematite to the froth. Flocculation tests together with starch property characterization were conducted to understand the underpinning mechanism. It is interesting that ultrasonic treatment of starch led to stronger and more selective flocculation of hematite, which accounted for the reduced entrainment loss of fine hematite and benefited the concentrate Fe grade. It was also found that ultrasonic treatment enhanced the dissolution and acidity of starch with a simultaneous increase in the content of amylose, which in turn could contribute to the improved depression and selective flocculation of hematite.