Valentin Antonovič

Investigating the hydration of deflocculated calcium aluminate cement-based binder with catalyst waste

The hydration of the binder, consisting of calcium aluminate cement (CAC) with Al2O3 >70% and with or without the additives of the FCC catalyst waste and polycarboxylate deflocculant Castament FS-20, is investigated. The methods of calorimetry, thermal analysis, XRD, electrical conductivity, SEM, as well as ultrasonic wave velocity measuring and bending strength evaluation are used. The results of the investigation show that the FCC catalyst as well as polycarboxylate deflocculant, are active additives, influencing the CAC binder’s hydration process. In the structure of the hardened binders, certain amounts of unhydrated CAC minerals, CA, and CA2, and the hydration products, such as CAH10, C2AH8 and the amorphous AH3, are found. However, in the binder with a deflocculant, there are smaller amounts of CAH10 and the amorphous AH3, though the amount of C2AH8 is higher than that in the binder without a deflocculant additive. It has been found that in the case, when the FCC catalyst and deflocculant are simultaneously used, the FCC catalyst produces a positive effect on the formation of the CAC binder’s structure, increasing its mechanical strength. The results obtained in this article allow to predict that the FCC catalyst and deflocculant simultaneously used as the additives to the CAC binder, will enable to control the hydration process of the binder.

Reuse of ultrafine mineral wool production waste in the manufacture of refractory concrete

The paper deals with the mineral wool production waste (cupola dust - CD), presents CD characterization and aims to reuse CD in production of refractory concrete with calcium aluminate cement. The study of CD covers its chemical, phase and thermal analyses along with the morphological study and determination of particles size distribution. Zeta-potential, electrical conductivity and pH values of CD suspension are presented in the paper as well. Commercial microsilica additive in refractory concrete has been replaced with cupola dust. Compositions of refractory concrete have been prepared by incorporating 1%, 2% and 3% of CD. The bulk density, ultrasonic wave velocity, cold crushing strength and thermal shock resistance of the created refractory concrete have been determined. Based on experimental results, it has been found that cupola dust may be used for the production of refractory concrete. The environmental impact related to the CD reuse in refractory concrete production has been evaluated as well.

Study of Alkali Resistance of Refractory Materials Used in Boilers Operating on Wood Fuel

Using the ASTM C 454–83 method alkali resistance is studied for various refractories (chamotte brick, traditional and medium-cement chamotte concrete) used most often in power generation boilers operating on wood fuel. Resistance to alkali of medium-cement concrete developed by the authors with a filler prepared from sinter grade Gorkal-50 (produced by the Gorka Plant, Poland) is also studied. It is established that use of milled quartz sand additive improves resistance of the test cement significantly towards the action of alkaline salt (K2CO3 is used in the work) at 1100°C. It is shown that the test additive during action of alkali facilitates formation of a protective layer that prevents penetration of K2CO3 decomposition products into the material structure.

Evolution of Refractory Materials for Rotary Cement Kiln Sintering Zone

Development of refractory materials for the high-temperature zone of the rotary kilns used in the cement industry that is the second-largest user of refractory materials is given in the article. It is shown that the history of refractory materials used in this rotary kiln high-temperature zone commenced with alumina-silicate materials and ended with specially developed periclase-based materials used currently. Advantages and drawbacks of these materials are considered. Basic information is provided about the manufacture of cement for consideration of possible chemical reactions between cement kiln raw material and refractory material components.

Refractory Materials for Biofuel Boilers

The energy equipment usable for solid biofuel incineration usually operates upon aggressive conditions. The internal structures (lining) of the equipment are made of refractory materials that are affected by combined loads: thermal, mechanical and chemical (i.e. high temperature–up to 1200°C, chemical impact of alkaline compounds and slag, repeating thermal shocks, abrasive effect caused by solid particles and so on). A majority of traditional refractories usable for lining in such equipment are not durable. Upon certain conditions of use (such as high local temperatures, influence of alkaline biofuel combustion products and so on), durability of the traditional materials is 1–2 years only. The opportunities of new refractory materials application should be set upon taking into account the conditions of operation for biofuel boilers of specific types. In this section the data on the peculiarities of using refractory materials in biofuel boilers are reviewed, and the impact of aggressive operating conditions of such thermal equipment on the properties of refractory materials is discussed. In addition, the investigations results of refractory castables alkali resistance and its explosive spalling are discussed. The recommendations for use of refractory materials in biofuel boilers are also presented.

The effect of carbon and polypropylene fibers on thermal shock resistance of the refractory castable

AbstractThis work investigates medium cement refractory castable with additives of carbon and polypropylene fibers. The peculiarities of microstructure changes in the fiber and castable matrix contact zone, channel formation, and changes of cold crushing strength of fiber additives, which have a refractory castable matrix under temperature treatment, were investigated. The investigation results allowed to predict that using a mix of fibers more effective than using them individually. The influence of fiber additives on the mechanical characteristics and thermal shock resistance of the refractory castable with fiber additives was tested. It was found that the addition of carbon fiber has a positive impact on the thermal shock resistance of the investigated castable, which is confirmed by the results obtained by thermal cycling, as well as by the values calculated for thermal shock resistance R4 and Rst. In addition, the results of the investigation of thermal cycling show that the value of the thermal shoc...

The Investigation of Properties of Insulating Refractory Concrete with Portland Cement Binder

The present work contains the results of experimental study on properties of insulating refractory concrete created on the basis of Portland cement (PC) binder and modified with microsilica (MS). The experimental compositions were made using Portland cement, lightweight aggregates (expanded clay and vermiculite) and microsilica additives. It was established that MS additives enable significant improvement of mechanical properties and thermal shock resistance of PC-based insulating concrete with values comparable to insulating refractory concrete based on calcium aluminate cement.