Semi-acid refractories from the hydrocyclone product of Tugan kaolinized sands
Abstract Generated abstract
This study evaluates the hydrocyclone product obtained during processing of the kaolinized sands of the Tugan ilmenite-zircon deposit as a raw material for semi-acid refractories. Chemical, grain-size, and ceramic properties were characterized, and laboratory specimens were produced using fired grog from the same material, molded and fired under specified conditions. The resulting products showed refractoriness of 1670°C, apparent porosity of 27.5%, compressive strength of 160 kg/cm², high thermal shock resistance, and low additional shrinkage, meeting the stated GOST requirements for class B semi-acid refractories. The work concludes that this hydrocyclone product is a technically suitable and potentially lower-cost alternative to semi-acid clays then in use.
Full Text
SEMI-ACID REFRACTORIES
FROM THE HYDROCYCLONE PRODUCT
OF THE KAOLINIZED SANDS OF TUGAN
(productive layer)
P. G. Usov, N. F. Voronova, A. V. Kuskova
(Presented by the scientific seminar of the Department of Technology of Silicates,
Inorganic Substances, and Electrochemical Productions)
The productive layer of the ilmenite-zircon placers of the Tugan deposit contains about 20% clayey material.
During the primary processing of the rock in hydrocyclones, a clayey product is separated, the composition of which depends on the degree of its purification from dusty sand. These data are given in Table 1.
Table 1
| Fractions | H₂O | l.o.i. | SiO₂ | TiO₂ | Al₂O₃ | Fe₂O₃ | CaO | MgO | Total |
|---|---|---|---|---|---|---|---|---|---|
| Hydrocyclone product | 0.60 | 8.10 | 62.00 | 1.07 | 25.95 | 0.80 | 0.59 | 0.77 | 99.88 |
| Fraction <50 µm | 0.83 | 8.91 | 6.20 | 1.20 | 26.85 | 0.85 | 0.56 | 0.76 | 100.10 |
| <20 µm | — | 10.26 | 57.96 | 1.10 | 28.50 | 1.03 | 0.61 | 0.71 | 100.17 |
| » <10 µm | 1.41 | 11.49 | 49.46 | 1.07 | 33.06 | 2.07 | 0.77 | 0.65 | 99.98 |
| » <5 µm | — | 13.86 | 45.78 | 1.14 | 36.92 | 1.44 | 0.57 | 0.31 | 100.02 |
It is evident from the table that the chemical composition of the hydrocyclone product is very close to the chemical composition of the fraction finer than 50 µm, separated by elutriation from the productive layer of the Tugan deposit.
The average grain-size composition of the hydrocyclone product is given in Table 2.
It is evident from Table 2 that the hydrocyclone product contains a large amount of dusty fractions—fine-grained sand—which, during the firing of products, has a favorable effect on their density [1].
In chemical composition the hydrocyclone product corresponds to semi-acid clays. Semi-acid refractory products are widely used in ferrous metallurgy as a steel-pouring
Table 2
| Sample | 1–0.25 mm | 0.25–0.05 mm | 0.05–0.01 mm | 0.01–0.005 mm | 0.005–0.001 mm | <0.001 mm | Sum of fractions <0.005 mm |
|---|---|---|---|---|---|---|---|
| Hydrocyclone product | 0.1 | 3.2 | 31.4 | 3.8 | 20.7 | 40.7 | 61.4 |
batch, the demand for which by 1970 will increase by 8%. Semi-acid refractories, as casting-pit refractories, have a longer service life than fireclay ones [2].
We carried out laboratory studies of the hydrocyclone product as a raw material for the manufacture of semi-acid refractories. A mineralogical analysis of the clayey component of the productive bed was previously carried out at the Department of Silicate Technology [3].
In terms of ceramic properties, the hydrocyclone product is as follows: molding moisture content 23–25%, drying shrinkage 4.0–4.5%, total shrinkage upon firing at a temperature of 1300°C is 8–10%. Plasticity is of the third class; the drying-sensitivity coefficient is 1.2–1.3.
The product sinters at temperatures above 1300°C. Water absorption decreases uniformly, without jumps, with increasing temperature.
The maximum strength at a firing temperature of 1300°C, converted to a standard brick, is 200–250 kg/cm². The technological scheme for manufacturing semi-acid products is as follows: grog is prepared from the hydrocyclone product by firing briquettes, made by plastic molding, at 1340°C. The water absorption of such grog is 10%.
The grain composition of the grog powder is selected with a view to obtaining a dense body and is as follows:
fraction 1–2 mm — 35%,
fraction 0.5 mm — 65%.
The batch, composed in a grog-to-clay ratio of 2:3, with a moisture content of 10%, was readily molded into products at a pressure of 250 kg/cm².
The dimensions of the products: diameter and height were equal to 25 mm.
The dried products were fired in a silite furnace at a temperature of 1320°C, with a holding time of 1 hour at the final temperature.
Table 3
| No. | Properties | Values | GOST requirements for semi-acid products of class B |
|---|---|---|---|
| 1 | Refractoriness, °C | 1670 | 1670 |
| 2 | Apparent porosity, % | 27.5 | 30.0 |
| 3 | Compressive strength, kg/cm² | 160 | 100 |
| 4 | Thermal shock resistance (water heat changes) 850°C | >65 | — |
| 5 | Additional shrinkage at 1350°C, % | 0.4 | 0.5 |
Table 3 gives the properties of the products in comparison with the GOST requirements for semi-acid products.
It is evident from the table that, in terms of properties, the specimens made from the hydrocyclone product fully correspond to semi-acid products of class B.
Conclusions
-
The hydrocyclone product of the kaolinized sands of Tugan can be used as a raw material for the manufacture of semi-acid refractories.
-
The cost of this raw material is considerably lower than that of the semi-acid clays of the Barzas deposit currently in use.
References
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P. S. Mamykin. Refractory Products. Sverdlovsk, Metallurgizdat, 372, 1955.
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V. D. Tsigler, V. L. Bulakh. Use of siliceous refractory materials in steel-pouring ladles, Refractories, 12, 31, 1966.
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P. G. Usov, N. S. Dubovskaya, A. V. Petrov. Local non-ore raw materials of the metallurgical, silicate, and construction industries of Western Siberia. Tomsk, Tomsk University, 79, 1964.