Study of the Water-Physical Characteristics of Alkali-Containing Glass Batches
Abstract Generated abstract
This study examines the wet aggregation behavior of an alkali-containing glass batch with about 21 percent soluble alkaline salts. Maximum molecular and capillary moisture capacities were measured for the batch and its components, and these values were used to calculate granulating ability and working moisture content at room and elevated temperatures. The batch was found to granulate very well at room temperature, with calculated moisture values consistent with practical granulation data, but conventional moisture-capacity methods gave misleading results at higher temperatures. A graphical-analytical method produced characteristic moisture values and working moisture estimates that agreed more satisfactorily with direct granulation experiments above the crystallization temperatures of soda and sodium sulfate.
Full Text
PROCEEDINGS
OF THE TOMSK POLYTECHNIC INSTITUTE NAMED AFTER S. M. KIROV,
ORDER OF THE OCTOBER REVOLUTION AND ORDER OF THE RED BANNER OF LABOR
Vol. 257 1973
STUDY OF THE WATER-PHYSICAL CHARACTERISTICS
OF ALKALI-CONTAINING GLASS BATCHES
V. M. Vityugin, V. A. Trofimov, L. G. Lotova, V. V. Ivanov
(Presented by the scientific seminar of the Department of GCT)
To determine the ability of a glass batch containing about 21% soluble alkaline salts (the batch composition is given in Table I) to undergo wet aggregation, the method of evaluation by the caking index was taken as the basis, using the calculation formula for the working moisture of aggregation [1].
Table I
Composition of the glass batch
| Name of components | Content, % | Fraction content, 0.5–0.25 mm | Fraction content, 0.25–0.1 mm |
|---|---|---|---|
| Sand | 54.60 | 74.60 | 21.50 |
| Feldspar | 6.52 | 32.10 | 50.95 |
| Dolomite | 16.52 | 20.30 | 37.94 |
| Calcined soda | 16.07 | 23.0 | 65.80 |
| Sodium sulfate | 5.36 | 19.48 | 61.00 |
| Fuel oil | 0.93 | – | – |
Determination of the maximum molecular \((W_{\mathrm{MMV}})\) and maximum capillary \((W_{\mathrm{MKV}})\) moisture capacities was initially carried out at room temperature, 20–22°C. The maximum capillary moisture was determined by capillary suction (by soaking) of the liquid phase by columns of dispersed material [2] (column height 60 mm, diameter 15 mm). The maximum mole-
capillary moisture capacity was determined by the moisture-capacity media method [3]. Preliminary experiments on saturating the batch with water showed that dissolution of the alkaline components leads to the formation of large washouts and that the continuity is disrupted. According to the procedure for determining $W_{\mathrm{MKV}}$, this is considered inadmissible. Saturation was carried out with a 30% solution of calcined soda (the solution concentration was selected experimentally). The results of determining $W_{\mathrm{MMV}}$ and $W_{\mathrm{MKV}}$, and the calculated indices of granulating ability and working moisture content of the granulated batch, are presented in Table 2.
Table 2
Values of $W_{\mathrm{MMV}}$ and $W_{\mathrm{MKV}}$ of the components and of the batch
(determination temperature: 24°C)
| No. | Material | Mean value of $W_{\mathrm{MKV}}$, % | Mean value of $W_{\mathrm{MMV}}$, % |
|---|---|---|---|
| 1. | Sand | 23.500 | 0.124 |
| 2. | Dolomite | 16.730 | 4.495 |
| 3. | Feldspar | 26.690 | 0.955 |
| 4. | Calcined soda | 43.500 | 20.400 |
| 5. | Sodium sulfate | 48.700 | 19.400 |
| 6. | Glass batch | 42.800 | 20.200 |
The batch under study may be classified as a material that granulates very well. The obtained value of the working moisture content agrees satisfactorily with the results of practical granulation of batches for technical and household glasses. For granulating batches of a composition analogous to that studied, practically 20 to 27% moisture is required [4, 5].
The values of the characteristic moisture capacities of the batch, determined at elevated temperatures, and the granulating-ability coefficient and working moisture content of aggregation calculated from them, are given in Table 3.
Table 3
Values of characteristic moisture capacities
| Mean values of indicators | Ambient temperature, °C | 30 | 40 | 50 | 60 |
|---|---|---|---|---|---|
| Mean values of indicators | Batch temperature, °C | 33 | 45 | 55 | 65 |
| 1 | 1 | 2 | 3 | 4 | 5 |
| 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|
| $W_{\mathrm{mkv}}$ | 35 | 24.7 | 22.6 | 22.1 |
| $W_{\mathrm{mmv}}$ | 14 | 6.0 | 5.1 | 4.9 |
| $K=\dfrac{W_{\mathrm{mmv}}}{W_{\mathrm{mkv}}-W_{\mathrm{mmv}}}$ | 0.668 | 0.321 | 0.268 | 0.285 |
| $W_{\mathrm{otg}}^{p}=W_{\mathrm{mkv}}-W_{\mathrm{mmv}}$ | 21 | 18.7 | 17.5 | 17.2 |
Analyzing the data of Tables 2 and 3, it may be said that raising the batch temperature from 24 to 60–65°C transfers it from the group of very well agglomerating materials to the group of poorly agglomerating ones, with some decrease in the working moisture content for agglomeration from 22.6% to 17.2%. At the same time, direct experiments on granulating the batch at elevated temperatures do not confirm this conclusion. Obviously, the reason for the contradiction lies in the inapplicability of the method for determining characteristic moisture capacities at elevated temperatures, and especially of the MMV index, for alkali-containing crystallizing batches.
When the graphical-analytical method [6, 7] is used, the obtained values of $W_{\mathrm{nkv}}$ and $W_{\mathrm{mkv}}$, and the working agglomeration moisture determined from them, agree satisfactorily with direct experiments on granulation of the batch under study at temperatures above the crystallization temperature of soda and sodium sulfate (Table 4).
Table 4
Values of characteristic moisture capacities determined by the graphical-analytical method
| Mean values of indicators / Temperature in the layer, °C | 26 | 33 | 45 | 55 | 63 |
|---|---|---|---|---|---|
| $W_{\mathrm{mkv}}$ | 30.6 | 27.8 | 24.5 | 21.8 | 21.2 |
| $W_{\mathrm{nkv}}$ | 12 | 10.2 | 8.6 | 8.0 | 7.7 |
| $W_{\mathrm{otg}}^{p}=W_{\mathrm{mkv}}-W_{\mathrm{nkv}}$ | 18.6 | 17.6 | 15.9 | 13.8 | 13.5 |
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