I. D. Kashcheev

Ways toward improving the technology of refractories based on powdered periclase

Periclase powders available from domestic (Magnezit JSC) and foreign manufacturers are analyzed for chemical and mineralogical composition. Domestic magnesite is shown to differ from its foreign analogs in smaller values of MgO content, CaO/SiO2 ratio, and periclase crystal size. A way toward obtaining high-quality powers involves reducing the concentration of SiO2 in magnesite to 0.2 – 0.5% and increasing the calcination temperature to 2000 – 2100°C to prepare coarse-grained periclase with a crystal size larger than 140 μm. The need for developing a technology that would enable fabrication of refractory components with tailored structural properties from periclase powder is emphasized.

Structurization of Unshaped Refractories

The pore structure and properties of vibration-cast high-alumina ceramic castables of three compositions based on highly concentrated binding suspensions of bauxite (HCBS) and different refractory fillers are studied. The matrix (binding) system of ceramic castables is characterized by a structural porosity with a median pore diameter of 0.55 μm. HCBS particles with a size less than 1 – 2 μm are mainly responsible for the structural porosity of both the matrix system and ceramic castable.

Electrofused Alumomagnesium Spinel

The effect of the MgO/Al2O3 ratio in an electrofused material obtained with the use of technical alumina and caustic magnesite is investigated. A conventionally thermostable material with minimum range of shrinkage or growth is obtained for the MgO/Al2O3 ratio ranging from 0.38 to 0.48. The alumomagnesium material grows due to the decomposition of the solid solution, the formation of crystals of Al2O3 spinel on the surface, and the interaction between the latter and periclase. The distribution of the elements over the volume of spinel grains studied by x-ray spectral microanalysis confirms the suggested mechanism of growth of the spinel-bearing material upon heating.

Container pipe transport with the use of secondary energy resources

An equipment and method are proposed for displacing hot loads on account of their heat. Applications are considered for container pipe transportation in nonferrous metallurgy.

Ways for increasing efficiency of a heat recovery unit

The authors present analysis of variants of using low-potential heat, which improve the efficiency of steam gas-fired boilers, air heating, and cleaning waste gases from toxic emissions in thermal machines. In order to achieve a more complete moisture removal from combustion products, an upgraded design of a contact heat recovery unit is proposed equipped with a drip pan with cooled packing.

High-Strength Ceramics Based on Zirconium Dioxide Powder

The method of coprecipitation of components was used to obtain disperse powders of tetragonal zirconium dioxide stabilized by Y2O3, Yb2O3 and a combined additive (Y2O3 + CaO + MgO). The technological parameters of the processes of synthesis and preparation of initial ZrO2 powders intended for ceramics with elevated strength parameters are proposed.

MgO-Al2O3-Cr2O3 refractories of increased corrosion resistance for nonferrous metallurgical furnaces

The paper sums up a study that had as its objective to develop MgO−Al2O3−Cr2O3 refractories of increased corrosion resistance for harsh service conditions. The refractories thus developed, designated PShKhM-1 and PShKhM-2, have better high-temperature strength and abrasion resistance than PKhS refractories manufactured commercially. The experimental refractories will enhance the durability of furnace and converter linings, extend their campaigns, step up their productivity, and reduce consumption of refractories and repair costs.

Tests of periclase-spinel-carbon articles in the lining of an iChKM-10-S1 mixer

Full-scale tests of pilot batches of periclase-spinel-carbon articles of grade PShUS-2 produced by the Dinur Company in the lining of the tank of an IChKM-10-Sl mixer operating at the Sinarskii Pipe Plant are described. The effectiveness of the use of the tested refractories is 2.5-3.0 times higher than that of corundum articles of grades KSP and KF. The endurance of the refractories is determined by the rate of oxidation of carbon.

Grain analysis of highly disperse powders using a scanning photosedimentograph

A scanning photosedimentograph built by specialists at Ural State Engineering University is described. Results of grain analyses of various refractory materials conducted by means of the device are presented. Data are given for alumina, cement, and quartzite, bauxite, and mullite slips. Experimental dependences of the error of measurement, on the concentration of the solid phase are derived. Grain compositions obtained on the photosedimentograph are compared with data obtained on microscreens, and the results are shown to be in satisfactory agreement.

Implementation of a production technology for refractories of the MgO-Al2O3-C system

It is shown that PShUS-2 products produced by the Dinur JSC are quite comparable in exterior appearance and accuracy of dimensions to PL 9310 periclase-carbon refractories manufactured by Magnesit Werke (Germany) with the same wear rate. Their average durability is no less than 45–50 heats. The Kompozit-Ural JSC and the Kombinat Magnezit JSC in cooperation with the Dinur JSC have improved the production technology for refractories of the MgO-Al2O3-C system to produce a variety of articles with the aim of utilizing as much as possible the reserve of their durability in various zones and sections of metallurgical units.