Yu. E. Pivinskii

Nanoparticles and Their Effective Use in the Technology of Highly Concentrated Binding Suspensions (HCBS) and Refractory Castables. Part 1

General aspects (including terminology) related to the use of ultradisperse particulates (nanosystems) are discussed. The important role of nanoparticles in the technology of highly concentrated binding suspensions (HCBS) and refractory castables is emphasized. Using nanoparticles provides a route toward improving the rheotechnologic properties of HCBS and HCBS-based molding mixtures as well as the structure and service properties of the end product.

Engineering, Manufacturing, and Servicing of Shaped and Unshaped Refractories Based on Highly Concentrated Ceramic Binding Suspensions

An analysis is made of the many years of experience in designing and improving industrial technologies which use quartz-glass HCBSs (highly concentrated ceramic binding suspensions) and high-alumina composite HCBSs to make shaped and unshaped refractories that are effective products for customers and sources of profit for manufacturers. Long before the current boom in nanomaterials, HCBS-based technologies employed elements that are part of nanotechnologies now in widespread use and are responsible for the high technical-economic efficiency of these materials. The volume of commercial production (CP) of the refractories at the OAO “Dinur” jumped 55% from 2013 to 2014. CP volume in the first quarter of 2015 increased by factors of 2.7 and 2.0 compared to the same periods in 2013 and 2014. Over three decades of use of the above technologies, Dinur has produced roughly 180,000 tons of highly profitable refractories that in current prices are worth about 12 billion rubles.

Research in the Area of Preparing Materials Based on Fuzed Quartz HCBS. Part 1. Comparative Evaluation and Distinguishing Features of Quartz Ceramic and Refractory Technology

The main production processes and preparation parameters are specified for materials based on fuzed quartz HCBS applied to both engineering ceramics and also a broad range of refractories. The fundamental differences between production technology for these groups of materials consists of raw material purity (cost), HCBS preparation conditions, molding system fineness, and molding methods. Technical and economic aspects of the technologies used are considered.

Research in the Field of Preparing Molded and Unmolded Refractories Based on High-Alumina HCBS. Part 1. High-Alumina Bauxite as a Basic Raw Material Component

Chemical composition, physicomechanical properties, mineral composition, and crystallographic properties are specified for high-alumina bauxites (predominantly Chinese) applied to refractory manufacture, prepared by HCBS-technology. Technology is developed for HCBS preparation of composite composition (bauxite + very fine quartz glass, i.e., HCBS) and refractories based on them with improved thermomechanical properties.

New refractory concretes and binding systems : Basic trends of development, production, and use of refractories in the 21st century. Part II. Ceramic binders and castables

A brief review of recently obtained and studied ceramic binding systems and castables based on them is presented. It is shown that corundum ceramic castables (Al2O3>95%) and ceramic castables based on aluminomagnesia spinel can be produced in principle. New molding methods that employ static pressing, ramming (vibroramming), and centrifugal shaping are described. The centrifugal method was used to produce ceramic castables (dmax≤5 mm) with an initial porosity of 13–14%. The method of vibroramming from molding systems with a moisture content of 3.4–4.0% was used to produce mullite-corundum ceramic castables with an elevated density and strength. The high efficiency of use of ceramic castables in metallurgy is due to the superfine porous structure of their matrix (binding) phase. The predominant pore size in various binders is 0.01–1.0 μm. In service, materials with such a structure are not impregnated by slag or metal. A principle for increasing the endurance of refractories produced from conventional raw materials using a new technology is suggested.

Research in the Area of Preparing Materials Based on Fuzed Quartz HCBS. Part 6. Effect of Firing Temperature on Material Sintering and Cristobalitization1

The effect of firing temperature in the range 1000 – 1350°C on indices for shrinkage, porosity, density, and strength of specimens based both fuzed quartz HCBS with different fineness, and cast system with a granular filler based upon them, is studied. Maximum indices for ultimate strength in bending are achieved after firing in the range 1200 – 1250°C. Strength values for different materials are within the limits of 6 – 9%.With a further increase in firing temperature in spite of an increase in density material strength is reduced as a result of cristobalite formation. It is shown that a fundamental factor governing sintering kinetics is starting fuzed quartz viscosity in the corresponding temperature range.

Rheological and binding properties of high-alumina suspensions

ConclusionsOn the basis of a high-alumina chamotte composition, we have obtained a highly concentrated suspension (CV up to 0.73) which makes it possible to mold casts of porosity to 16% and an ultimate bend strength of up to 4 MPa.The main principles in the process of making suspensions and the character of their rheological properties have already been obtained for silicaceous suspensions. The casts of the high-alumina composition are capable of being strengthened by means of the SCACB mechanism which makes it possible to obtain the casts on the basis of both finegrained ceramic and materials of a grainy structure.

Research in the Field of Preparing Molded and Unmolded Refractories Based on High-Alumina HCBS. Part 5. Effect of Firing Temperature on Properties of Materials Prepared From Composite HCBS With Addition of Refractory Clay1

The effect of firing temperature in the range 800 – 1600°C and heat treatment duration (60 h at 1350 – 1400°C) on shrinkage and growth indices, porosity, and strength for specimens based on HCBS of composite composition (bauxite and VFQG), and also with added clay, is studied. Depending on specimen composition there is low shrinkage within the limits of 0.4 – 1.15% in the range 1100 – 1200°C and significant growth (2.0-.27%) as a result of secondary mullite formation occurring at 1300 – 1500°C.

Research in the Area of Preparing Materials Based on Fuzed Quartz HCBS. Part 3. Study and Improvement of Centrifugal Casting1

Chronology is considered for development of research and introductory work in the field of centrifugal casting, implemented in the production of quartz steel-pouring refractories. Large scale application of centrifugal casting is used for the first time in domestic and overseas practice for ceramic and refractory production. The main requirements are considered for original casting systems and regimes making it possible to obtain high density semifinished product. Prospects are shown in a number of examples of using the method in casting objects based on HCBS of other materials.

PRODUCTION AND SERVICE OF HIGH-ALUMINA CASTABLES. 2. PROPERTIES AND SERVICE OF VIBRATION-PLACED CASTABLES BASED ON BAUXITE-MODIFIED HIGHLY CONCENTRATED CERAMIC BINDING SUSPENSIONS (HCBS) FOR USE IN BLAST-FURNACE RUNNERS

The advantages of replacing of rammed castables by vibration-placed castables as the material for fabricating the lining of blast-furnace runners are considered. Batches of environmentally safe vibration-placed castables commercially available from Dinur JSC bauxite-based HCBSs, modified with finely disperse quartz glass, are used as the binder. The castables were tested at the Nizhny Tagil Metal-and-Steel Works. Endurance of the castable under operating conditions of the main runner is 140 thousand tons of iron (to first repair) and greater than 1 million tons (to overhall). The overall consumption rate of the castable is 0.25 – 0.35 kg/ton iron and 0.10 – 0.15 kg/ton iron (in routine repair conditions), which is substantially higher in comparison with the traditionally used rammed castables. At present, 80% of the total number of operating blast-furnace runners at the NTMSW have a lining made of vibration-placed castables.