RU2276420C1 - Method for producing magnetic liquid - Google Patents

Abstract

FIELD: magnetic liquid production; synthesizing main component of magnetic liquid iron phase (highly dispersed magnetite) from etching and electroplating process wastes.

SUBSTANCE: proposed method for producing magnetic liquid includes mixing of hydrochloric solution of electroplating process slug sediment and spent etching solution in Fe³⁺/Fe²⁺ = 3 : 2 proportion, production of magnetite slurry for which purpose mixture of solutions is peptized by adding 28% ammonium hydroxide and co-precipitation of bivalent and trivalent ferric oxides and their interaction, coating of magnetite particle surfaces in aqueous medium with adsorbing layer of stabilizing agent, heating of slurry of magnetic particles incorporating stabilizing agent layer adsorbed therein, their separation from water phase and mixing with other-than-water carrying liquid. Upon co-precipitation bivalent and trivalent iron slurry is exposed to 50-Hz variable magnetic field.

EFFECT: enhanced magnetic characteristics of magnetic liquid.

1 cl, 1 tbl, 5 ex

Description

The invention relates to the field of production of magnetic fluids, as well as to the field of synthesis of the main component of a magnetic fluid of a ferrophase (highly dispersed magnetite) from pickling and galvanic waste. Magnetic fluid is a stable colloidal system of highly dispersed particles of magnetic material (ferro- or ferrimagnetic substances) stabilized by surfactants in a carrier fluid, which is capable of interacting with a magnetic field and in many respects behaves as a homogeneous fluid.

Due to the unusual combination of the properties of magnets, liquids and colloidal solutions, magnetic fluids are a promising material and could find application in various fields of technology: when creating magnetic fluid seals in the chemical industry, as magnetic lubricants, in the processes of magnetic enrichment of non-magnetic materials, in biology and medicine. But their widespread use is limited by high cost.

Getting magnetic fluids consists of two main operations.

1. Obtaining fine particles of a magnet.

2. Stabilization of the magnetic particles in the carrier fluid using a dispersant that prevents aggregation of the magnetic particles in the carrier fluid and ensures the stability of the magnetic fluid.

A known method of producing magnetic fluid. Initially, materials having higher magnetic properties — finely dispersed metallic iron, cobalt, soft magnetic alloys of the permendur type [Matusevich NP, Rakhuba V.K. — were used as a ferrophase in the production of magnetic fluid) Production of magnetic fluids by peptization. - In: Hydrodynamics and Thermophysics of Magnetic Liquids. - Abstracts of the All-Union Symposium. Salaspils, Institute of Academy of Sciences of the Latvian SSR, 1980, p.21-28]. However, when using pure metals, a number of technological difficulties arise, related both to the preparation of finely dispersed particles and their protection against oxidation, and to their stabilization with subsequent dispersion in a carrier fluid. Therefore, along with metals, magnetite (iron oxide) is increasingly used as a ferrophase, which although inferior to metals in magnetic characteristics, but due to the simplicity of producing highly dispersed particles, good adsorption ability, and chemical stability, it allows one to obtain magnetic fluids that are superior in magnetic parameters magnetic fluids on metals.

There is also known a method of producing magnetic fluid, which consists in the deposition of particles of magnetite from aqueous solutions of salts of Fe ²⁺ and Fe ³⁺ excess alkali (NaOH and NH ₄ OH). Chlorides and sulfates are preferred salts due to their availability and cost-effectiveness. The presence of ions of other metals - Mg ²⁺ , Cr ³⁺ , Ni ²⁺ , Cu ²⁺ - is not harmful if their content is low.

The precipitate of magnetite is washed with decontamination from excess alkali and removal of salts to achieve pH = 7. The obtained magnetite has a dispersion, is easily stabilized and dispersed. Magnetic fluid is obtained by adding to the aqueous magnetite suspension a carrier fluid in which a stabilizer, a surfactant, is dissolved. Kerosene is used as a carrier fluid, and oleic acid is used as a stabilizer. During the chemisorption of oleic acid, an adsorption layer forms on the surface of magnetite particles. In this case, dehydration of magnetite particles and phase separation occurs, that is, the isolation of magnetite from the aqueous medium and its transition into the medium of the carrier fluid [Matusevich NP, Rakhuba VK Production of magnetic fluids by peptization. - In: Hydrodynamics and Thermophysics of Magnetic Liquids. - Abstracts of the All-Union Symposium. Salaspils, Institute of Academy of Sciences of the Latvian SSR, 1980, p.21-28].

заполненной стальными шарами. Нужная степень пептизации достигается за 6-12 ч.Also known [Akhalaya MG, Kokiashvili M.S., Beria V.P. Prospects for the use of magnetic fluids in biology and medicine. - In the book: Physical properties of magnetic fluids: - Sat. articles. - Sverdlovsk, UNU AN USSR, 1983. - S.115-120] a method for producing magnetic fluid in which the synthesis of the ferrophase is carried out as in [Matusevich NP, Rakhuba VK Production of magnetic fluids by peptization. - In: Hydrodynamics and Thermophysics of Magnetic Liquids. - Abstracts of the All-Union Symposium. Salaspils, Institute of Sciences of the Latvian SSR, 1980, p.21-28], then the water is removed from the precipitate by successive washing with acetone, toluene. To obtain magnetic fluid in the required carrier fluid, toluene is drained from the magnetite precipitate, the wet precipitate is transferred to a porcelain mortar, and a stabilizer, oleic acid, is added to it. From the resulting mixture, toluene is evaporated by heating to 90-110 ° C with continuous grinding of the precipitate. After evaporation of toluene, the mixture is continued to triturate thoroughly at the same temperature. The resulting mass is transferred using the required amount of dispersion medium to the mill and homogenized in a steel mill, on

filled with steel balls. The desired degree of peptization is achieved in 6-12 hours.

A known method of producing magnetic fluid, including the formation of a suspension of magnetite by coprecipitation from solutions of ferrous and trivalent iron ions, coating the surface of magnetite particles with an adsorbed layer of a stabilizing substance, separating from the suspension a fraction containing stabilized magnetic particles in a carrier fluid, and as a source of ferric iron to obtain magnetic ferrophase, a hydrochloric acid solution of sludge-waste from wastewater treatment in galvanic shops is used [RF Patent No. 2182382, Bull. No. 13, 2002; IPC: H 01 F 1/36].

The described methods for producing magnetic fluid are labor intensive and time-consuming with obtaining an expensive product.

Closest to the proposed invention is a method for producing magnetic fluid, we have chosen for the prototype [RF patent No. 2193251, Bull. No. 32, 2002, IPC: H 01 F 1/28].

It consists of the following stages: mixing in the required ratio (Fe ³⁺ / Fe ²⁺ = 3: 2) of a hydrochloric acid solution of a precipitate - galvanic sludge and spent pickling solution; obtaining a suspension of magnetic particles of Fe ²⁺ and Fe ³⁺ oxides of colloidal size by peptization of a mixture of solutions by adding 28% ammonium hydroxide; coating the precipitated particles of Fe ²⁺ and Fe ³⁺ oxides in an aqueous medium with a stabilizing substance that forms, in excess of ammonium hydroxide, an ammonium salt soluble in water; heating a suspension of stabilized particles to convert a stabilizing substance (decomposition of its ammonium salt to form ammonia gas) and turning it into a water-insoluble form and separating them from the aqueous phase; the formation of magnetic fluid when a coagulant is mixed with non-aqueous liquid carriers that have some solubility with respect to the stabilizing substance.

The resulting magnetic fluid is a stable colloidal suspension of magnetic particles, but with low magnetic characteristics compared to magnetic fluid from pure raw materials.

The objective of the present invention is to improve the method of producing magnetic fluids with achieving higher magnetic characteristics by activating the magnetic phase due to its interaction with an alternating magnetic field of industrial frequency to obtain a more developed surface for the interaction of ferrous and ferric oxides.

The problem is solved as follows: mixing in the required ratio (Fe ³⁺ / Fe ²⁺ = 3: 2) of a hydrochloric acid solution of the precipitate - galvanic sludge and spent pickling solution; obtaining a suspension of magnetite from Fe ²⁺ and Fe ³⁺ oxides of colloidal size by peptization of a mixture of solutions by adding 28% ammonium hydroxide with the coprecipitation of ferrous and ferric oxides and their interaction; exposure to a suspension with an alternating magnetic field with a frequency of 50 Hz, where the magnetite particles are crushed by a magnetic field to form a new surface and become more active, which facilitates and intensifies the interaction of FeO with Fe ₂ O ₃ with an increase in the yield of magnetite; coating the precipitated particles of magnetite in an aqueous medium with a stabilizing substance, forming in excess of ammonium hydroxide an ammonium salt soluble in water; heating a suspension of stabilized particles to convert a stabilizing substance (decomposition of its ammonium salt to form ammonia gas) and turning it into a water-insoluble form and separating them from the aqueous phase; the formation of magnetic fluid when a coagulant is mixed with a non-aqueous carrier fluid, which have some solubility with respect to the stabilizing substance.

The method of obtaining magnetic fluid is illustrated by the following examples.

Example 1

Sludge-waste after treatment of galvanic wastewater, dried at 105 ° C for 1 h with a moisture content of 6.6%, the content of the basic substance (Fe ₂ O ₃ ) - 67.9%, the content of the residue insoluble in HCl - 0.7 %, pH of the aqueous extract - 6.6, the content of water-soluble salts - 3.55% is dissolved in concentrated hydrochloric acid; after filtering the solution, it is mixed with the spent etching solution containing Fe ³⁺ ions and 0.06 mol of Fe ²⁺ , then 50 cm ^{3 of} 28% ammonium hydroxide are slowly added while stirring to co-precipitate the ferrous and ferric oxides. The mixture is heated to 95 ° C and 50 cm ^{3 of} kerosene and 5 cm ^{3 of} oleic acid are added (with vigorous stirring). Then, heating continues and a distinct separation of the aqueous and organic phases occurs. The aqueous phase is removed using a pipette. This reduces the heating time, and also eliminate most of the ammonium chloride. Heating is continued until the water is depleted and the temperature of the organic phase rises to 130 ° C.

The liquid is cooled to room temperature and poured into a beaker. Kerosene is added to a volume of 55 cm ³ , which compensates for the loss of kerosene during heating. The properties of the obtained magnetic fluid are presented in the table (MF ₁ ).

Example 2

It is carried out, as example 1, but after the coprecipitation of ferrous and ferric oxides, magnetite is exposed to an alternating magnetic field with a frequency of 50 Hz for 15 minutes to provide a higher yield of magnetite. The properties of the obtained magnetic fluid are presented in the table (MF ₂ ).

Example 3

It is carried out, as example 2, but the effect of magnetite with an alternating magnetic field with a frequency of 50 Hz is carried out for 30 minutes The properties of the obtained magnetic fluid are presented in the table (MF ₃ ).

Example 4

It is carried out, as example 2, but the effect of magnetite with an alternating magnetic field with a frequency of 50 Hz is carried out for 45 minutes The properties of the obtained magnetic fluid are presented in the table (MF ₄ ).

Example 5

It is carried out, as example 2, but the effect of magnetite with an alternating magnetic field with a frequency of 50 Hz is carried out for 60 minutes The properties of the obtained magnetic fluid are presented in the table (MF ₅ ).

MF ₁ MF ₂ MF ₃ MF ₄ MF ₅ Magnetite activation time τ, min. 0 fifteen thirty 45 60 Saturation magnetization, I, kA / m 12.10 13.47 16.80 19.78 19.80

As can be seen from the table, the saturation magnetization sharply increases with increasing activation time and reaches its maximum value in 60 minutes.

Claims (1)

A method of obtaining a magnetic fluid, comprising mixing a hydrochloric acid solution of a galvanic sludge precipitate and spent pickling solution at a ratio of Fe ³⁺ / Fe ²⁺ = 3: 2, obtaining a suspension of magnetite by peptization of a mixture of solutions by adding 28% ammonium hydroxide with the precipitation of ferric and ferric oxides and their interaction, coating the surface of magnetite particles in an aqueous medium with an adsorbed layer of a stabilizing substance, heating a suspension of magnetic particles with a layer of a stabilizing substance adsorbed on them, about separating them from the aqueous phase and mixing with a non-aqueous carrier liquid, characterized in that after the coprecipitation of ferrous and ferric oxides, they are exposed to a suspension with an alternating magnetic field with a frequency of 50 Hz.