Ferrite Sludge Research Articles

The treatment of electroplating wastewater using an integrated approach of interior microelectrolysis and Fenton combined with recycle ferrite

Heavy metal ions in chelated forms have aroused great concerns because of their high solubility, poor biodegradation and extreme stability. In this research, an efficient strategy, interior microelectrolysis-Fenton-recycle ferrite (IM-Fenton-RF), was developed to treat simulated electroplating wastewater containing chelated copper at room temperature. The decomplexation of chelated copper was carried out by both interior microelectrolysis and Fenton reactions. IM process can not only partly degrade the complexes of chelated copper via the microelectrolysis reaction but also it produces Fe2+ ions for the Fenton reaction. After decomplexation, the IM-Fenton effluent directly flowed into the RF reactor for copper ions removal. Under optimum reaction conditions (reflux ratio = 0.37, Fe2+ concentration = 9.20 g/L at pH 10.18), 99.9% copper was removed by the IM-Fenton-RF system. The produced IM-Fenton-RF sludge is based on ferrite precipitate and has several advantages over metal hydroxides sludge. Ferrite sludge is stable owing to the stability of ferrite's crystal structure, while the toxicity characteristic leaching procedure (TCLP) test meets relevant standards. The sedimentation rate and volume of ferrite sludge were 3.86 times faster and 11.0 times lower than those of metal hydroxides sludge. Furthermore, the yielding sludge of ferrite can be recovered and utilized for the synthesis of Fe–C metallic species, the main compound of IM packing for interior microelectrolysis reaction. All these results show that a combination of IM-Fenton and RF is an effective approach to treat wastewater containing chelated copper, showing great potential for industrial applications.

Development of technology of utilization of products of ferritization processing of galvanic waste in the composition of alkaline cements

A study of the products of ferritization processing of galvanic waste: sludge and spent process solutions is carried out. As a result of experiments on dynamic leaching of heavy metal ions, the immobilization properties of the sludge, obtained at different process parameters of ferritization are determined. It is shown that the level of immobilization of heavy metals in ferrite sludge after leaching is 99.96 wt % and in the sludge of traditional wastewater neutralization <97.83 wt %. The studies determine the possibility of reliable utilization of ferritized galvanic waste – introduction into the charge to produce alkaline cements. It is found that the main crystalline phases in the structure of alkaline cements with ferrite sludge are calcite, quartz and heavy metal ferrites. In addition, jelly-like formations are found, which are further capable of crystallization. Such formations reliably bind heavy metals in the chemical structure of cement. It is found that when using up to 10 wt % of ferrite sludge in the total weight of cement, the compressive strength of artificial stone reaches 40 MPa, which meets the requirements of the current standard. The chemical stability of the alkali cement matrix using ferrite sludge is confirmed by the study of leaching of heavy metals for one day in neutral, alkaline and acidic media. It is shown that the degree of immobilization of heavy metal ions in cement with a ferrite sludge content of 30 wt % is >99.98 %. In addition, the concentrations of heavy metal ions during leaching meet the national and international standards for their MPC in drinking water and soil. This approach will allow solving the problem of utilization of hazardous galvanic waste and production of general construction materials

Energy-saving processing of galvanic sludge by the feritization method

Increasing the level of ecological safety for industrial facilities through the implementation of resource-saving technology for the processing of toxic waste – galvanic sludge by ferritization method is considered. Advantages of using electromagnetic pulse activation method of ferritization process in comparison with traditional thermal one are experimentally confirmed. It is recommended to use electromagnetic pulse discharges with magnetic induction amplitude of 0.298 T and pulse rate of 0.5 to 10 Hz to activate the ferritization process. This method of activation ensures a high degree of recovery of heavy metal ions – up to 99.97% and the reuse of purified water in industrial facilities. The regularities of removal of heavy metals by ferritization in the range of aeration rate values 0.225 ÷ 0.075 m3/h in the reacton mixture under different activation methods are established. Investigated the physical properties and structure of sediments, obtained by ferritization method. Environment friendly ferrite precipitates are characterized by a high degree of centrifuge seal (more than 90%) and a crystalline structure with the maximum content of ferrite phases with magnetic properties. The method of electromagnetic impulse activation also has undeniable energy advantages in comparison with traditional high-temperature one: electricity costs are reduced more than 60%. In addition, reducing the aeration rate to 0.075 m3/h makes it possible to additional cost reduction for the proposed technology. The immobilization of heavy metals in environmentally safe ferrite sludge enables further disposal of waste in commodity products. The proposed process of galvanic waste processing by improvement of ferritization method prevents environmental pollution, ensures efficient and rational use of water, raw materials and energy in the galvanic industry.

The two-step neutralization ferrite-formation process for sustainable acid mine drainage treatment: Removal of copper, zinc and arsenic, and the influence of coexisting ions on ferritization.

Acid mine drainage (AMD) or acid rock drainage (ARD), the most notorious environmental problem in many mines and underground construction sites, is generally managed using lime neutralization. This approach is effective but unsustainable in the long term, so we introduced the two-step neutralization ferrite-formation process in our previous works as an alternative. However, several important issues related to this new approach-the partitioning of hazardous elements during treatment, stability of generated sludges, and influence of coexisting ions-remains unclear. In this study, real AMD containing zinc (Zn), copper (Cu) and arsenic (As) was treated using a laboratory-type continuous ferrite process flow setup. Partitioning of hazardous elements in the two sludges was elucidated by X-ray fluorescence spectroscopy (XRF) and X-ray absorption spectroscopy (XAS) while the stability of sludges was determined by standard leaching experiments. The bulk of Cu and As species (both As(III) and As(V) based on XANES spectra) were partitioned in the first sludge while ~64% of Zn was associated with the ferrite sludge. In terms of stability, both sludges were relatively inert and released only minute amounts of Zn, Cu and As, all of which were below the Japanese environmental standards. The roles played by two of the most ubiquitous coexisting ions in AMD on ferritization-dissolved silica (Si) and aluminum ion (Al3+)-were also elucidated using 10 synthetic AMDs. Between the two, dissolved Si exhibited stronger adverse effects on ferritization than Al3+. At dissolved Si above 4mg/L, Si-O-Fe surface complex formation on amorphous Fe-precipitates or Fe-oxide precursor minerals became extensive, which protected these phases from the dissolution-transformation reactions required to form strongly magnetic magnesioferrite and magnetite. These results suggest that the flexibility and applicability of this new AMD treatment approach could be improved by controlling the dissolved Si concentration prior to the ferrite formation step.

Magnetite and cobalt ferrite nanoparticles used as seeds for acid mine drainage treatment

In this study, magnetite and cobalt ferrite nanoparticles were used as seeds for acid mine drainage (AMD) treatment at pH of 7.05±0.35. Duplicate samples of AMD, one without heating and another with heating at 60°C was treated under continuous stirring for 1h. The filtrate analysis results from ICP-OES have shown complete removal of Al, Mg, and Mn, while for Fe, Ni and Zn over 90% removals were recorded. Particularly, settling time has significant effect on the removal of Mg, Ca and Na. The results from SQUID have shown superparamagnetic properties of the synthesised magnetic nanoparticles and ferrite sludge. The recovered nanoparticles from AMD are economically important and reduce the cost of waste disposal.

Metals and sulphate removal from acid mine drainage in two steps via ferrite sludge and barium sulphate formation

In this work, primary test of ferrite formation by coprecipitation method from pure Fe(NO3)3⋅9H2O and FeSO4⋅7H2O were evaluated at different pH and temperature by continues stirring using magnetic stirrer. The optimized method was applied on simulated and real acid mine drainage (AMD). The impact of simultaneous removal of metals and sulphate on the magnetic moment of ferrite sludge and addition of ferrite or ferrite sludge seeds into real AMD samples were also investigated. The XRD results of synthesised ferrite from pure binary salts confirmed that presence of heat and increased pH improved the degree of crystallite of ferrite. During neutralization of AMD using sodium hydroxide, gypsum was not precipitated in the absence of calcium hydroxide or barium ions. Consequently, the two step processes were applied; whereby metals are removed in the first step via ferrite sludge formation using sodium hydroxide and followed by treatment of the filtrate with barium chloride or barium hydroxide for complete sulphate removal as barium sulphate precipitate. From the analysis results, the ferrite sludge produced separately from sulphate showed higher magnetic moments than produced simultaneously. In the pH range of 7–8.5, at temperature of 60°C, 93%, 12%, and 28%, and 99.6%, 57.5% and 47.5% of Fe, Mn and Co were removed from real AMD; in the absence and presence of ferrite seeds in 20min reaction time, respectively. Furthermore, the rate of metal removals and magnetic moments of synthesised ferrite sludge were increased in the presence of ferrite seeds. Generally, these results indicated that AMD could be used as a resource for production of commercially valuable chemicals, which in turn could help to offset the cost of treatment.

Synthesis and characterization of magnetic nanoparticles and study their removal capacity of metals from acid mine drainage

In this study, the possibility of synthesising magnetic nanoparticles (MNPs) with and without heat from pure chemicals and real acid mine drainage (AMD) by co-precipitation method was explored. In addition, the influences of temperature, pH and stirring time on the crystalline size of MNPs were studied. The results revealed that possibility of synthesising Fe3O4 and CoFe2O4 from their corresponding binary salts under these conditions. Further, the method was applied on simulated and real AMD; however, formation of well crystalline MNPs at lower pH and temperature from both samples were hampered due to interfering and combined effect of the metal cations. Increasing pH and temperature increased crystalline size of synthesised MNPs as confirmed by XRD results. Similarly, these observations were further reflected by the formation of Fe3O4, γ-Fe2O3, Mn3O4, MnO2 and ZnO mixtures as major components from real AMD. Treating AMD in the presence of MNP seeds accelerated formation of ferrite and resulted in increased magnetic moment of ferrite sludge. Under all conditions, higher intensity and better resolution of XRD peaks of synthesised MNPs were obtained when NH4OH (aq.) was used for neutralization than NaOH (aq.). In general, this study demonstrates that the possibility of converting environmental pollutants into commercially valuable chemicals.

Development of Rotary Magnetoferrite Treatment with Stirrers for Waste Water Treatment Plants to Reduce Excess Sludge

A large amount of excess sludge is being produced in the waste water treatment plants (WWTPs), which is a serious problem in terms of economical and environmental problems. So, the experiments on reduction of excess sludge are carried out. We have introduced a new approach for reduction of excess sludge by using ferrite particles and permanent magnets. A rotary treatment plant was introduced which showed good possibilities of this method for application in the WWTPs. Stirrers hold a very important role in rotary magnetoferrite treatment as they directly get in touch with ferrite particles and sludge. In this paper, we have shown the relationship between the ferrite particles and stirrers. Again, the treatment was carried out for different amounts of activated sludge which shows that the smaller the amount, the better the treatment of sludge. This knowledge may pave the way for the reduction of excess sludge in WWTPs in practical fields.

Magnetic Sensor for the Defect Detection of Steam Generator Tube With Outside Ferrite Sludge

Steam generator tube in nuclear power plant is a boundary between primary side and secondary side. Nondestructive test for the steam generator tube, eddy current testing (ECT) method has been carried out. In case of bobbin-type ECT probe, transverse defect, defect with ferro-phase, outside of tube having ferrite sludge were very difficult to detect. To overcome these problems, a motorized rotating probe coil (MRPC) probe was developed but scan speed is slow and not effective method in time. In this work we have developed a new sensor having U-shape of yoke to measure permeability variation of test specimen, which can detect ferro-phase generated as well as normal defects in the tube material of Inconel 6oo. Electronics for signal processing, 2-phase lock-in amplifier per sensor, ADC, and embedded controller were employed in one probe and measured digital data were transmitted to the PC data acquisition software using RS232C interface. Using the developed sensors we have applied to detect defects in the tube outside with ferrite sludge which is very difficult to detect conventional bobbin-type ECT probe. Developed sensor could measure defect size of 0.2 mm times 10 mm times 0.44 mm (width times length times depth) for the normal defect and defect outside of tube having ferrite sludge. We expect the developed sensor could detect defects like as MRPC probe and scan sensor speed like as bobbin-type ECT probe.

Reactance simulation for the defects in steam generator tube with outside ferrite sludge

A magnetic sludge is partly produced around the tube sheet outside a steam generator due to stress and heat. The sludge with magnetite is one of the important factors affecting eddy current signals. It causes trouble for the safety of the steam generator tubes and is difficult to detect by conventional eddy current methods. A new type of probe is needed to detect the signals for the magnetic sludge. We designed a new U-type yoke which has two kinds of coils—a magnetizing coil and the other a detecting coil—and we simulated the signal induced by the ferromagnetic sludge in the Inconel 600 tube.

Acid mine drainage treatment through a two-step neutralization ferrite-formation process in northern Japan: Physical and chemical characterization of the sludge

The acid mine drainage of a closed iron sulphide mine in northern Japan was treated on-site using a continuous flow bench scale plant. In the bench scale plant of the two-step neutralization ferrite-formation process, magnesium oxide or calcium carbonate was used during the first neutralization step to raise the pH to around 4.8 to produce aluminium hydroxide sludge. In the second neutralization step sodium hydroxide was applied to reach a pH of 8.5 to produce ferrite sludge. Initial settling rates of the produced aluminium and ferrite sludge were from 1.2 to 4.8 times higher than the initial settling rates of the sludge produced by the treatment plant currently operated at the mine. The suspended solids (SS) concentration in the sludge ranged from 1.0 to 11.8 times higher than the SS concentration in the sludge produced by the current facility. The sludge volume index (SVI) of aluminium sludge was 11 and 36 mL/g when produced with magnesium oxide or calcium carbonate, respectively. The SVI of ferrite sludge was 4 mL/g regardless of the type of neutralizer used in the first neutralization, while the same parameter (SVI) of the sludge produced by the current facility is 70 mL/g, which indicates that the two-step neutralization ferrite-formation process generates sludge with much higher density. In addition, the process effectively reduced the concentration of toxic heavy metals from above 800 ppb, 13 ppm, and 15 ppm to as low as 1.4 ppb, 0.02 ppm and 0.2 ppm for arsenic, copper, and zinc, respectively.

フェライトスラッジのリサイクル

フェライトスラッジのリサイクル

カドミウム含有廃液のフェライト化処理によって生成する スラッジの改質

Leached test was used to evaluate the safety of the ferrite sludge formed by the heat treatment after conventional or two-step treatment with pH adjustment of wastewater. Simultaneously, the concentrations of Cd and Fe ions in the treated water were measured before the leached test. The effect of the heat treatment on the concentrations of Cd (CCd) and Fe (CFe) in the elute was discussed by comparing the ferrite sludge formed without heat treatment. The CCd of ferrite sludge formed by the heat treatment with the two-step treatment was remarkably lower than that by conventional or two-step treatments in relation to Cd(OH)2 on the surface of ferrite particles. XPS measurement of the sludge formed by conventional and two-step treatments indicated the existence of Cd(OH)2 on the surface of ferrite particles. XPS measurement of the sludge formed by the heat treatment indicated no existence of Cd(OH)2 on the surface of ferrite particles. The measurement after Xe+ sputtering showed that the Cd(OH)2 is absent not only on the surface but also in the bulk of the particles formed by heat treatment. The heat treatment after two-step treatment stabilizes the sludge and is favorable for steady operation of the ferrite process, industrial utilization of the sludge and good quality of the treated water.

クエン酸共存下におけるニッケル含有廃液のフェライト化処理によって生成するスラッジの改質

Leached test was used to evaluate the safety of the ferrite sludge formed by conventional, two-step treatments and two-step treatments with pre-treatment by KMnO4. Simultaneously, the concentration of Ni, Fe and Mn ions in the treated water was measured before the leached test. The effect of pre-treatment on the concentration (C) of Ni, Fe and Mn in the elute was discussed by comparing the conventional and two-step treatments.The CNi and CMn of ferrite sludge formed by the two-step treatment with pre-treatment were remarkably lower than that by conventional and two-step treatments in relation to Ni(OH)2 on the surface of ferrite particles. However, the limit in the ability to treat heavy metals decreases in the wastewater containing citric acid. XPS measurement of the sludge formed by conventional and two-step treatment with pre-treatment indicated the existence of Ni(OH)2 on the surface of ferrite particles. The measurement after Xe+ sputtering showed that the Ni(OH)2 is present not only on the surface but also in the bulk of the particles formed by conventional treatment.The two-step treatment with pre-treatment stabilizes the sludge and is favorable for steady operation of the ferrite process, industrial utilization of the sludge and good quality of the treated water.

ニッケル含有廃液のフェライト化処理によって生成するスラッジの安定化

The saturated magnetization σ(emu·g-1) was measured for the ferrite sludge formed by two-step treatment with pH adjustment of wastewater containing nickel sulfate. Simultaneously, the concentration of nickel and iron ions in the treated water was measured. The effect of pH adjustment on the above parameters was quantitatively discussed by comparing the two different treatments: conventional and two-step treatments.The σ of ferrite sludge formed by the two-step treatment with pH adjustment was slightly larger than that by conventional and two-step treatments. XPS measurement of the sludge formed by conventional and two-step treatment with pH adjustment indicated the existence of Ni(OH)2 on the surface of ferrite particles. The measurement after Xe+ sputtering showed that the Ni(OH)2 is present not only on the surface but also in the bulk of the particles formed by conventional treatment. In leached test, the concentration of nickel ion in the elute was lower in order of conventional, two-step and two-step treatment with pH adjustment in relation to Ni(OH)2 on the surface of ferrite particles.The two-step treatment with pH adjustment stabilizes the sludge and is favorable for steady operation of the ferrite process, industrial utilization of the sludge and good quality of the treated water.

Magnetic Separation of Ferrite Sludge from a Wastewater Purification Process

The purification of wastewater containing dissolved metal ions by in situ precipitation gives rise to a sludge composed mainly of ferrites MeXFe3-xO4 (where Me represents the existing metal ions in the wastewater). Oxides, iron oxy-hydroxides and other impurities are also present in the sludge in smaller proportion. The present investigation proposes magnetic separation of the sludge to recover the ferrites for their possible re-use. Under optimum operating conditions of the magnetic separator, a recovery efficiency of the magnetic fraction in excess of 99% and a high degree of selectivity were obtained.

Optimization of the operational variables of a medium-scale reactor for metal-containing wastewater purification by ferrite formation

A medium-scale (5l) reactor was designed for the purification of metal-containing wastewater discharged by academical chemical laboratories. The process is based on the precipitation of metals in alkaline solution as metal-bearing ferrites of high magnetic permeability, which can be later used in a variety of applications based in their magnetic properties. Chemical variables affecting the process efficiency were optimized in a previous work and fixed here at their optimum values (pH, 10; Fe(II):Total metal molar ratio, 15). Operational variables or control factors were optimized using a Taguchi parameter design in order to achieve maximum efficiency of the purification process (or minimum total remnant cationic concentration, TRCC), and a solid waste (ferrite sludge) of maximum magnetic permeability, which allows its use in a variety of applications. The interference caused by metal-binding organic matter present in the wastewater was investigated introducing in the optimization experiment a three-level noise factor in order to find control factor levels that yield optimum process performance, insensitive to the uncontrollable variation of this noise. EDTA (disodium salt) was used as model for the noise factor. The effects of temperature, air flow and stirrer rate were moderate. It was observed that the presence of high concentrations of metal-binding organic matter hinders metal precipitation in such a way that EDTA concentrations higher than 10−3M decrease purification efficiencies below 99%. Under the optimized conditions (reaction time, 1h; temperature, 60°C; air flow, 30l/min; and stirrer rate, 560rpm), and for concentrations of metal-binding organic matter below 10−3M, a purification efficiency of 99.9% and a chemically stable (inert) ferrite sludge of relative magnetic permeability 83.60 (66.6% of the MP value for pure magnetite) are obtained. The procedure is therefore recommended for purification of metal-containing wastewater. The chemical reactions involved in the process are discussed.

Electrochemical study of iron ferrite sludge obtained under the conditions proposed for the purification of waste water at a carbon paste electrode

The structure and characteristics of ferrite sludge obtained in the purification of waste water contaminated with metal ions, are dependent on the experimental conditions. Under optimum conditions, a ‘magnetic ferrite sludge’ (mfs) is produced while variation of these conditions gives rise to a ‘non-magnetic ferrite sludge’ (nmfs). Both are free of contaminants. DSC and X-ray analysis revealed that the mfs was composed of magnetite (Fe 3O 4). Heating at 200°C causes the transformation of magnetite into maghemite ( γ-Fe 2O 3) and calcination at 700°C gives rise to hematite ( α-Fe 2O 3). The nmfs consists of magnetite and poorly crystallized goethite ( α-FeO · OH) and undergoes similar changes with temperature. Electrochemical analysis of the mfs, the nmfs and the product obtained by heating mfs at a temperature above 700°C (‘heated ferrite sludge’, hfs) was performed using a carbon paste electrode in HCl and HClO 4. A linear scan from the potential at I = 0 was performed in a positive direction and followed by successive cyclic scans towards negative potentials and back. The linear scan voltammogram (LSV) and the first cyclic scan voltammogram (CVI) indicate that solid species participate in the electrochemical mechanism of the chemical transformations. However, after the first cyclic scan the voltammograms (CV2 etc.) show that only dissolved species absorbed on the graphite (Fe 3+, Fe 2+, FeCl 2 + and FeCl +) intervene.

Treatment of Waste Water Containing Heavy Metal Ions by Ferrite Process and Recycled Ferrite Sludge

Treatment of Waste Water Containing Heavy Metal Ions by Ferrite Process and Recycled Ferrite Sludge

Application of the Taguchi Experimental Design to the Removal of Toxic Metals From Waste Waters by Precipitation as Magnetic Ferrites

Abstract Waste waters polluted with toxic metals can be successfully purified by precipitation of the metals from an alkalinised solution containing iron(II) as ferrite sludge with magnetic properties. The magnetic ferrites obtained by this treatment can be disposed or reutilised with smaller risk for the environment since metals contained in the ferrite are less available. A Taguchi experimental design has been applied to the optimisation of the ferrite precipitation process, the aim being to achieve the maximum purification of the solution and the best magnetic characteristics of the ferrite. Four control factors at three levels were explored. (Fe(II) concentration)/(total metal concentration) ratio, temperature, treatment duration and pH, and assigned to the columns of a L9(34) orthogonal array. A noise factor (potassium permanganate) at three concentration levels was also introduced to simulate the uncontrollable variability of the waste water composition. Optimal heavy metal removal (>99%) and magnet...