Refractory Products Research Articles

Optimization of the Slag Composition in Ladle Treatment of Steel for Increasing the Resistance of Refractories and Promoting Slag Reuse

Methods of ladle furnace slag stabilization are analyzed. It is shown that increasing the Al2O3 content of slag to higher than 18% results in chemical stabilization of slag. It is revealed that if the Al2O3 content is less than 30 wt.%, the refining properties of the slag do not degrade. When that content is exceeded, Al2O3 behaves similarly to SiO2, i.e., reduces the desulfurization ability of slag and makes it more corrosion aggressive. The most favorable content of Al2O3 in slag is from 12 to 25%, the properties of slag varying from basic to acidic. If the Al2O3 content is higher than 14%, the probability of formation of MgO–Al2O3 refractory spinel on the surface of refractory products increases, thereby increasing the durability of ladles and vacuum chambers.

Establishing the Optimum Composition of Superaluminous Refractory Products, Used for Steel Ladle Bubbling

It is widely acknowledged by all specialists in the field of ferrous metallurgy that the porous peg of the kit for injecting inert gases into the steel casting ladle is the weakness of the entire assembly. This is the most prompted piece due to the thermal shocks that occur when injecting cold gas and the wear and tear and corrosion caused by disturbances in the steel during the injection process. The porous structure of the peg considerably weakens the physical properties and widens the surface of metal - refractory material contact thus enabling the destructive chemical action. In addition, the process of injecting oxygen for cleaning the metal peg also contributes to the destructive action and the substantial decline in its endurance. All these considered, it has been decided that the material for producing these items should contain at least 95% Al2O3 which means using only tabular alumina. As far as the binder is concerned, it has been established that a liquid chemical binder made of colloidal alumina should be used since this does not considerably diminish the Al2O3 content of the end product. It is the aim of this paper to bring forward the author�s research regarding the production of the porous plug using high-alumina refractory materials.

Recycling of waste serpentine for the production of forsterite refractories: the effects of various parameters on the sintering behavior

The waste serpentine, natural magnesite, and caustic magnesia were used for the production of the sintered forsterite. The forsterite-phase content of the samples sintered at 1650 °C reached to 93.6 wt.%. The effects of various parameters such as additives, particle size, and calcined raw materials were tested on the sintering behavior. The thermal expansion of 9.54 × 10−6 at 800 °C and pH of 8.99 were obtained from the samples fired at 1650 °C. These results reveal that sintered forsterite has properties similar to those of natural olivines and propose an actual solution to overcome the environmental problem resulting from several million tons of waste rocks in Abdasht chromite mines.

Development of the technical specifications and changes to the TSs for refractories by JSC “The Ukrainian research institute of refractories named after A. S. Berezhnoy” in 2017

This article includes information about development of the technical specifications (TS) and changes to the TSs for refractories by institute in 2017. In 2017 in accordance to the requirements of the state standardization system 12 change to TSs for serial refractory products, produced by Ukrainian enterprises, including verification and approval 1 change to TS for serial refractory products developed PrJSC “KDZ”, 10 TSs and 4 change to TSs for pilot batches of refractories manufactured by JSC “The URIR named after A. S. Berezhnoy” have been developed and endorsed by enterprises.
 Changes to technical conditions and new technical conditions developed in accordance to the requirements of modern system to standardizations of the Ukraine (SОU КZPS 74.9-02568182-003:2016, DSTU 1.5:2015, SОU MPP 01.120-090:2005), have been endorsed by manufacturers and enterprise consumers, tested for compliance with current legislation, technical regulations and regulatory documents and entered into the database “Technical conditions of Ukraine” — SE “Kharkivstandartmetrology”, and approved by the technical committee TC 7 “Refractories”.
 Institute plans to continue work on the development of TS and changes to the TSs for refractory products, study and analysis of the global level of standardization in the field refractories.

Research of the rheological and casting properties of alumina slips and samples from them containing a new dispersing addition and its combination with a hardening addition

The corundum ceramics technology has been developed and implemented at JSC “The URIR named after A. S. Berezhnoy”, which involves the production of high refractory corundum high density products using different methods of forming. A slip casting in gypsum form is one of the often used for forming a corundum ceramics production. The advantage of this method is the simplicity of the equipment, the relatively low cost of forms, as well as the possibility of manufacturing products of various shapes, sizes and weights.
 In depending of the wall thickness of the product using two methods of slip casting: bulk method with using a slip with a density of 2.5 g/cm3 of alumina MARTOXID brand with a dispersing addition (based on an aqueous solution of an ammonium salt of an acrylic copolymer) in an amount of 0.4 % for casting products of complex configuration, insulators, rods, plates, mortars, pestles, and for casting thick-walled products (4—5 mm and more) and a drain method with using a slip with a density of 2.1 g/cm3 of alumina MARTOXID brand with a dispersing addition in an amount of 0.3 % and a hardening addition in an amount of 0.2 % for casting hollow articles in the form of crucibles, covers, pipes, a ditch, boats, etc. for casting thin-walled products (1—3 mm).
 The researches of rheological properties of alumina slips from alumina MARTOXID brand which contain a new dispersing addition based on carboxylic acid and its combination with a hardening addition were carried out in this work.
 The optimum values of rheological and casting properties of the slips, ensuring the production of castings with a maximum density, are achieved with the introduction of 0.3 and 0.2 % dispersing addition into the slips with a density of 2.5 and 2.1 g/cm3 respectively were established.
 It was established that, at use of the dispersing addition based on carboxylic acid the apparent density of green body corundum ceramics lower than with the dispersing addition based on an aqueous solution of an ammonium salt of an acrylic copolymer, but it is sufficient to produce the same high-quality products after firing at 1580 оC (open porosity is not > 0.8 %) with a slightly higher shrinkage during firing, i. e. the use of this addition, if necessary, is possible.

Research of grain composition batch influence on alumina-zirconium silicate and alumina-chromia-zirconium silicate refractories properties

Comparative researches of grain composition batch influence with electrofusion corundum aggregate with a maximum grain size 2.0 mm or 1.0 mm on properties of alumina-zirconium silicate KTSS brand and alumina-chromia-zirconium silicate KCHTSS-30 and KCHTSS-15 brands refractories were carried out. It was established that, from batches with maximum grain size 2.0 mm and fraction content < 0.5 mm 20 % it is possible to obtain refractories with properties that approximate to the properties of refractories from batches with maximum grain size 1.0 mm and fraction content < 0.5 mm 10 %. It was shown that, for the manufacture of alumina-chromia-zirconium silicate refractories from optimal grain composition batches it is advisable to use metallurgical and pigment chromic oxide in the ratio of 2 : 1 or complete replacement of chromic oxide with mud, forming during mechanical treatment of chrome oxide refractory products. The developed compositions of batches make possible to increase efficiency of using electrofusion corundum in the manufacture of alumina-zirconium silicate and alumina-chromia-zirconium silicate refractories. Obtained results are used at making of products for glass melting furnace of industrial lining for fiberglass production from E glass.

Raw materials for mullite grog manufacturing

The starting raw materials for aluminosilicate grog manufacturing are fissile claystones and shales. These raw materials are available in the Czech Republic and grogs with up to 45 % aluminium oxide content are manufactured. However, refractory production cannot do without higher-Al2O3 -content grogs. This group includes grogs with alumina content of 45 % to 70 %, which constitute a transition between fire clay and mullite grogs. Because of the high market price of these grogs, however, there is an effort to seek ways to manufacture these in the Czech Republic. The primary condition for manufacturing is the correct choice of raw material, a suitable treatment facility, and a kiln capable of firing at temperatures above 1400 °C. This paper assesses some local raw materials for grog manufacturing and compares the results with a mullite grog of similar properties that is available on the European market.

A Novel and Effective Therapeutic Approach to Overcome Refractory Transplant-Related Anti-Glycan Ab Production.

A Novel and Effective Therapeutic Approach to Overcome Refractory Transplant-Related Anti-Glycan Ab Production.

SHS Technology for Composite Ferroalloys. 2. Synthesis of Ferrosilicon Nitride and Ferrotitanium Boride

The combustion of ferrosilicon in nitrogen is very similar to the combustion of metallic silicon. With increase in silicon content in the initial ferrosilicon, its reaction rate with nitrogen increases, as is clear from the considerably more vigorous combustion. The nitrogen concentration in the combustion products increases here. Over the whole range of initial parameters (nitrogen pressure, grain size of the powder, batch composition), the combustion products consist mainly of β-Si3N4. No large quantity of α-Si3N4 is observed. In practice, FS75 and FS90 ferrosilicon is optimal for refractory production, while FS65 and FS75 ferrosilicon, with lower impurity content, is best for the production of components used in steel production. The introduction of iron in the Ti–B system (Tad = 3190 K) considerably restricts the combustion concentration range. A mixture with 16.9% B burns in a narrow Ti:B concentration range close to 0.86. In combustion of the Fe–B + Ti mixture, increase in the initial temperature considerably expands the concentration range for synthesis. In all cases, increase in the initial temperature considerably boosts the combustion rate. Heating to T0 ≥ 300°C permits the use of mixtures with titanium powder containing larger grains (rme.Ti ≥ 0.4 mm) in self-propagating high-temperature synthesis (SHS). A wide range of B:Ti ratios may be used. The combustion of such mixtures permits the production of an alloy with 6–14% B and 30–60% Ti. Specialized industrial equipment has been constructed: a series of SHS reactors with working volumes of 0.06, 0.15, and 0.3 m3, permitting the large-scale production of materials based on refractory inorganic compounds for use in metallurgy. The industrial production of composites based on oxygen-free compounds by self-propagating hightemperature synthesis has been introduced.

Photocatalytic degradation of cooking fume on a TiO2-coated carbon nanotubes composite filter

A TiO2/MWCNTs/Al2O3/NF (TiO2 nanoparticles/multi-walled carbon nanotubes /Al2O3-modified nickel foams) composite filter was prepared through grown of MWCNTs upon Al2O3-modified nickel foams using chemical vapor deposition (CVD) method and then coated TiO2 nanoparticles onto MWCNTs using dip-coating method. The MWCNTs forms a network-like structure on the surface layer of composite filter. The BET surface area of TiO2/MWCNTs/Al2O3/NF composite filter is more than 375 times higher than that of the pristine nickel foam. The degradation performance of oil particles was evaluated. Under optimized reaction conditions, 90% of the oleic acid on the filter was decomposed after 25 h. In addition, the effect of reaction temperature and light intensity were studied. Increased reaction temperature and light intensity were found to significantly improve the degradation rate and restrain the formation of refractory product. Furthermore, a parallel reaction kinetic model was adopted for degradation of oleic acid on the composite filter. The composite filter can reduces the accumulation of oil particles on the filter and the energy consumption of the filter. This approach proposes a new way to treat the cooking fume emission at residential building roofs.

Optimization of the Binder System for Improving Workability and Thermo-Mechanical Properties of Plastic Refractories

Plastic refractory properties were studied by synthesizing two different binders in the laboratory. Liquid phosphate binders from different sources, a sol-gel bonding system, organic plasticizers, water retention agent and deflocculating agent were optimally mixed using different techniques for binder synthesis. The stability of the thixotropic behaviour of the binders varied with different compositions and techniques. Plastic refractory products were manufactured in the laboratory with an identical raw material composition and particle size distribution. Plastic refractory products with different binders were characterized based on the workability index of green mass, bulk density, cold crushing strength, modulus of rupture and permanent linear change of fired samples at 850 °C and 1200 °C. Phase and micro-structure analysis was in line with the thermo-mechanical properties of end products. The plastic refractory prepared with Binder B-1 was found to be optimal in terms of workability and thermo-mechanical properties.

Magnesium aluminate spinel nanoparticle influences upon the technological properties of MCZ composite brick for RCK lining

Fabrication of magnesia-calcium zirconate (MCZ) composite brick from Egyptian magnesite and zirconia (9.8 wt%) through adding different concentrations (2, 4, 6 wt%) of magnesium aluminate spinel rich magnesia (M-MA) nanoparticles as a modifier was experimented. Densification parameters, cold crushing strength (CCS), corrosion towards cement clinker components (CKC), and other technological properties of the produced bricks were investigated. The results revealed that MCZ brick containing 2.00 wt% of M-MA spinel gave the optimum mechanical properties, thus the strength was fortified by 44.8%. In addition, the penetration resistance and coating behavior toward the clinker components and the thermal shock cycles of the produced bricks were also enhanced with the addition of nano spinel. The investigated bricks showed higher technological properties compared with the refractory products offered in the market for the cement kiln. Accordingly, the brick free from spinel can be highly offered to transition and cooling zones of rotary cement kiln (RCK), while MCZ bricks containing spinel nanoparticles are recommended for lining the burning zone. Moreover, hazard chromite usage for improving coating adhesion can be superseded by environmental safe of nano-MA.

Technology of manufacture of high-alumina refractories based on Shurtan Gas-Chemical complexs used sorbent and enriched kaolin

Technology of manufacture of high-alumina refractories based on Shurtan Gas-Chemical complexs used sorbent and enriched kaolin

A Study of 3D Geometric Shapes, Optimum dimensions, and Designs for Refractory Products for Improved Unit Durability

We have developed, tested, and installed tuyere blocks that reduce by a factor of 9 the number of joints in horizontal-converter tuyere belts, decrease corrosive wear on the refractory products, and reduce the likelihood of penetration by slag-matte melt. A design was developed for a special refractory product that reduces thermal stress as well as heating time, prevents the products from falling from brick courses in roofs, and sharply diminish thermal losses through the brickwork in open-hearth furnaces as well as ore-roasting furnaces and through the lining in Waelz kilns. These special-design products enabled improvements to the lining performance of the high-temperature units without increasing maintenance costs.

Fuzed Periclase Grain Surface Modification with Coal-Tar Pitch

Results are provided for a study of the chemical composition and microstructure of fuzed periclase grains. A method is proposed for modifying periclase skin grains with coal tar pitch that reduces grain porosity and improves the adhesion of a carbon binder to its surface during carbon-containing refractory manufacture.

MOVEMENT OF CORROSION OF PERICLASE-CHROMITE DIRECTLY BOUND REFRACTORIES IN THE SUCTION PIPE OF RH-VACUUM

The results of studies of refractory products based on the fused periclasechromite after service in the suction pipe of the RH vacuum at two metallurgical plants were reported. At one plant, the branch pipe was operated in contact with slag containing as a homogenizing additive fluorspar with an alumina slag-forming component, on the second with slag, for homogenization, which was used only by fluorspar. The duration of operation is 1550‒1800 min. It is established that the depth of infiltration of the slag melt components into the refractory depends on the type of homogenizing additive to the slag in the steel casting ladle. A slag containing a combination of fluorspar with an aluminous slag-forming additive penetrates the microstructure of the refractory to a greater depth, which leads to a change in the initial phase composition.

Refractory Ceramic Products from Pure Oxides with Getter Coatings

We developed a technology of manufacturing refractory products from pure oxides with getter titanium coatings intended for the fusion and pouring of chemically active metals and alloys. This technology is realized by the method of plasma spraying. The obtained products guarantee the reliable protection of the melts located inside them against the penetration of gases from the atmosphere. The application of these products significantly increases the reliability of the process of growth of parasite-free single crystals from magnetically hard alloys of the Fe–Co–Ni–Cu–Al–Ti system and makes it insensitive to the presence of gaseous admixtures of nitrogen and carbon and water vapors in the inert atmosphere of growth chamber.

Reducing energy consumption and carbon emissions of magnesia refractory products: A life-cycle perspective

Abstract China is the largest producer of magnesia refractory materials and products in the world, resulting in significant energy consumption and carbon emissions. This study analyzes measures to reduce both the energy consumption and carbon emissions in the production phase and use phase, providing a theoretical basis for a sustainable magnesia refractory industry. Results show that the total carbon emissions of carbon-containing magnesia bricks produced with fused magnesia are much higher than those of other products, and the total carbon emissions of both general magnesia brick and magnesia-carbon spray are lower than those of other products. Carbon emissions of magnesia products are mainly concentrated in the production process of magnesia. Manufacturers should select materials with lower environmental impacts and emphasize saving energy and reducing carbon emissions in the magnesia production process. Through scenario analysis we found that CO2 capture is an effective measure to reduce carbon emissions compared with just improving energy consumption. However, a robust CO2 market does not currently exist. Policy makers should plan on integrating CO2 capture in the magnesia industry into a regional CO2 capture and storage development planning in the long term. In particular, magnesia production is concentrated in a single geographical area which would and thus could take advantage of significant scale effects. In the use phase, extending the service lifetime reduces carbon emissions over the product lifetime, thus users should attempt to extend the service lifetime of a furnace as a whole. However, results show that it is not advisable to add a large number of repair refractories to extend the lifetime of existing furnaces.

Synthesis of second phase hybrid ceramics using two different bio-source and a comparative study on their morphological characterization

Ceramics are generally synthesized with various sources and methods. The most common method for synthesis of ceramics with reduced cost and energy is SOL-GEL method. Combustion synthesis is also a most widely used method for ceramic synthesis. In general, ceramics have enhanced hardness and dimensional stability even at elevated temperatures. For this reason, they are used in the production of refractories, thermal barrier coatings, chemical resistant coatings, wear resistant coatings, and also as reinforcement material to produce metal matrix composites and polymer matrix composites. This work concentrates on the comparison of morphological characterization of such reinforcement particles synthesized from different sources. The particles size range varying from 7 μm to 250 μm with flaky and spongy structures are observed in the ash of Vicia faba. However, the ash of Cocos nucífera resulted in fibrous structure with a diameter of 50 μm to length above 600 μm, particles size ranging from 10 μm to 70 μm micro tubes of diameter 3.6 μm to length of 150 μm. The EDX and XRD analysis of Vicia faba showed the presence of carbon as the major element with a few other elements.

The Effect of Temperature on the Fundamental Characteristics of Self-Compacting No-Cement Refractory Castable

In this research, the impact of firing temperature and MgO addition on mechanical and physical properties of self–compacting no-cement castables were investigated. For this propose up to 3.3 wt % of MgO was added to the corundum castable compositions and the specimens were fired at 600 °C, 800 °C, 1000°C, 1200°C and 1500°C. The mixtures were made so that the consistency of each one was the same. There were only minimal differences in the mixtures water content. The mineral composition of the input raw materials for manufacturing of the refractory castables was determined. The physical and mechanical properties of castable compositions such as self-flow values, bulk density, apparent porosity, cold crushing strength and flexural strength were examined. Also, the X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDX) techniques were used for detection the ceramic phase formation. The corrosion resistance was determined by means of the crucible test according to ČSN P CEN/TS 15418 (726022) Method of test for dense refractory products – Guidelines for testing the corrosion resistance of refractories caused by liquids. The study follows up on research, the results of which were published last year [1], but the study is focused to self-compacting refractory castable.