Investigation of the Effect of Magnetic Treatment on the Aggregate Properties of Moist Dispersed Materials
Abstract Generated abstract
This study examines whether magnetic treatment can alter the aggregate-forming properties of moist dispersed materials by changing the state of water associated with their particles. Kaolin, limestone, iron-ore concentrate, alumina, and coal slurry were exposed to a permanent magnetic field while dry, at characteristic moisture capacities, capillary-saturated, or in suspension, and the effect was evaluated through maximum molecular moisture capacity. The results indicate that magnetic treatment has little effect when water is already bound, but increases molecular moisture capacity when free water is present, especially in suspensions. The paper concludes that the treatment can enhance lump-forming capacity by converting part of the free water into a more bound, structured state.
Full Text
STUDY OF THE EFFECT OF MAGNETIC TREATMENT ON THE AGGREGATE PROPERTIES OF MOIST DISPERSED MATERIALS
V. M. Vitotin, V. P. Podkova
(Presented by the scientific seminar of the Department of General Chemical Technology)
The mechanical strength of moist granules and the structural state of aqueous suspensions and pastes are ultimately determined by the energy of interaction of solid-phase particles through water interlayers. Of extremely great importance in this interaction are the structural properties of the layers of water between the particles.
It is known that water located in the field of action of the surface molecular forces of solid particles differs substantially in its structure from free water. Thus, in particular, water bound by the surface of particles has increased density and viscosity. In other words, from the standpoint of wet aggregation of dispersed materials, bound water plays the role of a binding substance.
The amount of water bound by a dispersed material can be determined with sufficient accuracy through the index of maximum molecular moisture capacity \((W_{\text{mmv}})\) [1].
Investigations by the Department of General Chemical Technology have established a directly proportional relationship between the index \(W_{\text{mmv}}\) and the lump-forming ability of a moist dispersed material.
On the other hand, it is known that the structural properties of water change substantially after its magnetic treatment. Thus it has been established that, after magnetic treatment of water, viscosity and density increase noticeably, and electrical conductivity correspondingly decreases [2].
These circumstances make it possible to suppose that preliminary magnetic treatment of moist dispersed materials and aqueous suspensions should promote an increase in the amount of bound, structured water in these systems.
Thus, preliminary magnetic treatment will increase the ability of dispersed materials to form lumps.
For an experimental check of the effect of magnetic treatment of moist dispersed materials, kaolin with a particle size of \(0.1—0\) mm, limestone with a particle size of \(0.15—0\) mm, an iron-ore magnetite concentrate with a particle size of \(0.1—0\) mm, clay with a particle size of \(0.07—0\) mm, and coal dust with a particle size of \(0.1—0\) mm were used.
Magnetic treatment of the indicated materials was carried out in the interpole space of a permanent magnet with an effective field strength of 1000 oersteds.
In the investigations, the moisture content of the dispersed materials and the treatment time were varied. The moisture content of the samples corresponded to the characteristic moisture capacities of the materials (maximum hygroscopic—MH;
maximum molecular (MMC) and maximum capillary (MCC). Suspensions were prepared at a ratio \(T : Ж = 1 : 1\). During magnetic treatment the suspensions were continuously stirred.
The effectiveness of magnetic treatment was assessed by the value of the maximum molecular moisture capacity. The experimental results are given in Table 1.
Table 1
Effect of magnetic treatment on the molecular moisture capacity of dispersed materials
| No. | Moisture content of the material during magnetic treatment, % | Treatment time, min | Kaolin | Limestone | Iron-ore concentrate | Alumina | Coal slurry |
|---|---|---|---|---|---|---|---|
| 1 | 0 | without treatment | 21.4 | 8.2 | 5.7 | 24 | 7.01 |
| 2 | 0 | 30 | 22.5 | 8.5 | 5.5 | 25.2 | 7 |
| 3 | 21.4 | 30 | 22.47 | ||||
| 4 | 8.2 | 30 | 9.3 | ||||
| 5 | 5.7 | 30 | 5.92 | ||||
| 6 | 24 | 30 | 24.5 | ||||
| 7 | 7.01 | 30 | 7.3 | ||||
| 8 | 53 | 30 | 22.5 | ||||
| 9 | 27.25 | 30 | 9.74 | ||||
| 10 | 17.1 | 30 | 5.94 | ||||
| 11 | 60.5 | 30 | 24.25 | ||||
| 12 | 76.4 | 30 | 7.3 | ||||
| 13 | 53 | 60 | 22.6 | ||||
| 14 | 60.5 | 60 | 24.5 | ||||
| 15 | 17.1 | 60 | 5.32 | ||||
| 16 | \(T : Ж = 1 : 1\) | 30 | 23.04 | 11.8 | 7.2 | 32.8 | 18.7 |
As might be expected, magnetic treatment of dispersed materials in the presence in them of bound moisture, MMC and MCC, produces no effect, evidently because the structuring influence of the electromagnetic force field on the particle surface is greater than that after the action of magnetic treatment. In magnetic treatment of capillary-saturated samples, the free water present in the capillaries partially passes into the bound state. This effect is observed still better in the magnetic treatment of suspensions. Thus, the effect of preliminary magnetic treatment of moist dispersed materials is determined by the amount of free water.
Conclusions
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Magnetic treatment of moist dispersed materials makes it possible to increase the value of the maximum molecular moisture capacity and thereby contributes to an increase in lump-forming capacity.
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The effect of magnetic treatment depends on the moisture content of dispersed materials. The external magnetic field acts only on free water.
References
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A. A. Rode. Fundamentals of the Theory of Soil Moisture. Gidrometeoizdat, Moscow, 1965.
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V. I. Minenko, S. M. Petrov, M. M. Mints. Magnetic Treatment of Water. Kharkov, 1962.