Ferrite Process Research Articles

Treatment of Wastewater Containing Heavy Metal Ions by Ferrite Process III

Treatment of Wastewater Containing Heavy Metal Ions by Ferrite Process III

Ferrite Process; Heavy Metal Ions Treatment System

The principle of the “Ferrite Process”, heavy metal ions treatment system, and the practically operated systems are presented. In the “Ferrite Process”, the heavy metal ions are incorporated into the lattice points of the ferrites in the course of the formation of the spinel structure by the oxidation of the Fe(II) ions. The ferrite formation reaction proceeds in two paths depending on the reaction pH; 1) the green rust path (pH 7-10), and 2) the γ-FeO(OH) path (pH 10.5-11). The mole ratio of the heavy metal ions incorporated into the lattice points to the Fetotal in the ferrites depends on the reaction pH and the mol ratio of the heavy metal ions in the reaction solution and to the Fe(II) ions added to the reaction solution. Ferrite Process is now practically adopted to the treatment of the laboratory waste waters at the universities and the institutes in Japan, to the treatment of the plating waste waters, and to the treatment of branching mine drainage waters. Since the ferrite sludge has a strong magnetic property, it is reused as a useful magnetic material.

Stabilization of Hazardous Materials into Ferrites

Stabilization of the hazardous materials by the Fe3O4-coating method was studied. In the ferrite-formation reaction in the aqueous solution, the adsorption of the metal ions and the oxidation of the adsorbed Fe(II) ions are repeated on the surface of the ferrite particles. This reaction was adopted to the coating of the hazardous materials with the Fe3O4(or ferrite). By repeating the two steps of l)the addition of the Fe(II) aqueous solution into the suspension of the hazardous materials, and 2)the oxidation by passing air through the reaction suspension, with the Fe3O4 layer, we could coat the surfaces of the hazardous materials, such as the heavy metal sludge from the neutralization-precipitation process, the CaF2 precipitates in the treatment of the waste waters containing fluoride ion along with hazardous metal ions, and the soils containing Cd(II) ion. These Fe3O4-coated hazardous materials are very stable and no heavy metal ions are leached under the normal environmental conditions. The ferrite sludges formed in the “Ferrite Process” were highly stabilized by the present method, and by the heat-treatment.

Fluoride Ions Adsorption onto Products from the Hydrolysis of Titanyl Sulfate

A method of eliminating the fluoride ions was studied to complement the ferrite process for treating inorganic liquid wastes. The experiment was carried out with due attention to the fact that products from the hydrolysis of titanyl sulfate have the ability to adsorb fluoride ions. The adsorption character for fluoride ions on products from the hydrolysis of titanyl sulfate have given excellent results.

Preconcentration of trace amount of cadmium in water by "ferrite Process".

A new concentration method for trace amount of cadmium in water by using a wastewater treatment system Ferrite Process was studied. Aqueous iron(II) hydroxide suspensions containing cadmium were oxidized at 0.1 dm3/min in the air flow rate and at 65°C. Ferrites thus obtained were magnetically separated. At a cadmium concentration of 10 ppb in the initial solution, cadmium ions were recovered quantitatively. At a cadmium concentration of 1 ppb, 90% of cadmium ions were recovered. The concentration factor of this method was 200.

The Fe 3O 4-formation by the ‘Ferrite Process’: Oxidation of the reactive Fe(OH) 2 suspension induced by sucrose

A mechanism of the formation of small particles of iron oxide in the wastewater treatment system ‘Ferrite Process’ is described. Small particles consisting of the Fe 3O 4−γ-Fe 2O 3 solid solution having slightly higher content of γ-Fe 2O 3 were obtained by the aerial oxidation of Fe(OH) 2 suspension in the presence of a weak dispersing reagent, sucrose, at pH 9.0. The increase of γ-Fe 2O 3 content is caused by a further oxidation of the Fe 3O 4 particles in the course of the reaction. The further oxidation was accelerated below 1000 Å of the particle size. When SO 2− 4 ion coexisted with sucrose in the reaction medium, the further oxidation was reduced and the treatment of the wastewater was improved. At a temperature interval of 40°–65°C, the formation of α-FeOOH was completely inhibited by a small amount of sucrose and only Fe 3O 4 was obtained.

Formation of 2VT ferrite during the calcining of a sulfate mixture

1. The calcining of a mixture of magnesium, manganese, and iron sulfates at temperatures of up to 420°C results in their full dehydration. 2. Intense decomposition of these sulfates is observed in the temperature range 620–750°C. 3. Full decomposition of such a salt mixture is attained at 1050°C, i.e., a temperature 100°C lower than the decomposition temperature of the most stable of the compounds investigated, magnesium sulfate. 4. The salt decomposition process is accompanied by a ferrite formation process, which predominates at temperature above 800°C. 5. The optimum ferritization temperature for such a salt mixture may be taken to be 1100°C.

Resistance of heat-treated structural steels to small plastic deformation and cold brittle failure

1. The mechanical properties of hardened low-alloy structural steels reach their optimum values during the development of the ferrite matrix polygonization process. 2. The optimum properties of 15G2SF steel σ0.2≥50 kg/mm2, σb≥60 kg/mm2, σ0.01/σ0.2≈0.95, δ5≫=16%,an−60°C ≥3 kg-m/cm2, T50≤−40°C) after tempering at 600–650°C.