666.762.16 Starting with 1989, the life of the linings of open hearth shop teeming ladles prepared from in-house produced chamotte parts dropped sharply from 11.4 to 9.5 heats. The basic reason for this was a drop in quality of the raw material supplied. For example, the water absorption of chamotte from Prosyanaya kaolin increased from 6-7 to i0-11% and in 1990 the alumina content dropped by more than 2.5% in comparison with 1989.The instability of the physicochemical properties of the original imported raw materials and also the irregularity of delivery of them had a negative influence on the quality indices of the finished product.In connection with freeing of facilities for firing ore and also to stabilize operation of the refractory shop and obtain higher quality ladle parts a production test of firing of Kumak clay in a rotating kiln was made. A method of firing of Kumak clay into chamotte with a water absorption of less than 5 % was developed but as the result of the low A120 3 content in the parts (32% max.) and the presence of Fe203 impurity (more than 2%) it was not possible to increase ladle lining life. Therefore firing of higher quality Arkalyk Deposit ARO and ARV-1 clays (TU 14-8-58-72) was subsequently switched to, which made it possible to obtain chamotte satisfying the requirements of TU 14-8-58-72. Such chamotte had more stable water absorption (3-3.5%) and the average A1203 content was 47.5% and Fe203 content 1.4%. It should be noted that the cost of chamotte from Arkalyk clay is significantly lower than from imported.In 1992 the Refractory Shop produced an experimental production lot of ladle parts using in-house produced charnotte from Arkalyk clays. In preparation of the charge using Arkalyk chamotte and in preparation of the raw material intermediate indices responsible for higher density and strength of the experimental parts than parts of imported chamotte were obtained. However, the density of fired chamotte parts produced from semidry mixtures depends not orfly upon the packing density of the chamotte grains but also upon their capacity to sinter in firing. The first lot of ladle parts, fired according to a temperarare cycle specified by existing instructions with the greatest increase in final temperature, showed satisfactory results both in visual inspection (absence of incompletely burned material) and according to quality indices.Use of in-house produced Arkalyk chamotte for production of ladle parts makes it possible to obtain refractories with high quality indices. For example, their average compressive strength is 35.2 and the maximum 56.5 N/mm 2 while for those using imported chamo~e these figures are 32.7 and 43.5 N/ram 2. The average open porosity of the experimental parts was 17.8% and of the parts of imported chamotte 19.3%. In addition the average A1203 content in the experimental parts was 38.0% and the temperature of the start of deformation under a load of 0.2 N/mm 2 1370~ while for the parts of imported chamotte these figures were 36.9% and 1320~The experimental par...

The service of refractories in the lining of the VP-130 and ~SPTs vacuum degassers of Orsk-Khalilovo Metallurgical Combine is characterized by severe conditions of the aggressive action of slag containing 2-4% YeO, 3-5% TiO2, 4-7% A1203, 16-22% MgO, 1-3% Cr203, 27-36% CaO, and 18-28% SiO 2. The metal is superheated in the electric furance to 1750~ as the result of its subsequent teeming in a continuous casting machine [I]. The slag basicity of 1.6-1.9 favors the formation in it of dicalcium silicate which, as is known, penetrates into the pores of the refractory and destroys it as the result of expansion of the volume in the polymorphic transformation during cooling [2][3][4].In accordance with the normally used method for reducing the corrosive action of slag on the lining it is neutralized during treatment in the vacuum degasser by supplying a slag neutralizer to the vacuum chamber.A corundum slag neutralizer to Technical Specification 14-8-489-85 and also a ramming compound to Technical Specification 14-8-359-80 are used as the slag neutralizer in Orsk-Khalilovo Metallurgical Combine.However, these materials do not influence the polymorphic transformation of dicalcium silicate.At the same time a number of elements (boron, phosphorus, etc.) stabilizing the high-temperature phase of dicalcium silicate at low temperatures are known [2].Orsk-Khalilovo Metallurgical Combine and the All-Union Institute for Refractories have developed a corundum slag neutralizer containing oxides of boron and phosphorous which neutralizes the slag and stabilizes the high-temperature phase of dicalcium silicate in it. Aluminoborophosphate concentrate, which contains these elements, is simultaneously the binder for the mixture.Commercial-grade alumina to GOST 6972-74, Kumak clay to Technical Specification 14-8-338-80, and aluminoborophosphate concentrate to Technical Specification 113-08-10-17-84 were used for the production of this slag neutralizer.The alumina is supplied to Orsk-Khalilovo Metallurgical Combine in the form of a fine powder (with a residue on a No. 0088 sieve of not more than 30%) and it is not additionally treated.Clay from the existing production line in the form of powder with passage through a No. 054 sieve of not less than 65% was used.The aluminoborophosphate concentrate was used in the form of an aqueous solution with a density of 1.5-1.6 g/cm 3.First laboratory tests were made of four compositions of slag neutralizer on cylindrical specimens with a diameter of 36 m~n and a height of 50 mm formed on a hyraulic press. A mixture with a moisture content of 22-24% was prepared in a laboratory mill.The clay was added in the form of a slip. The compositions differed in the content of clay and aluminoborophosphate concentrate.The specimens of each form were dried in a drying chamber at 100~ and heat treated at 120, 700, and 1350~In determination of the physicomechanical properties the best results were obtained after heat treatment of the specimens of composition 4 at 1350~ (Table i). This composition was recommended f...