Basic Refractories Research Articles

カーボン含有耐火物の概要

Carbon based or containing refractories has been attracting great attention because of their unique properties e.g. high thermal conductivity, low thermal expansion, high resistance to thermal shock and chemical inertness to the slag. They are classified into two groups; carbon/bricks/blocks and carbon containing materials. Carbon containing materials are further classified into carbon containing basic refractories and non-basic refractories. Manufacturing processes are considered. The properties e.g. physical, thermal, mechanical and chemical are reviewed. Antioxidant and bonding materials for these types of the refractory products are reviewed. Their applications are also considered.

Behavior of basic refractories at high temperatures in steelmaking processes thermodynamics and implications for the usability of olivine as refractory material

Basic unshaped refractories are used as tundish lining in the continuous casting steelmaking process. These refractories are composed of forsteritic olivine and periclase. Slag covers the steel bath in the tundish in order to protect the melt from reoxidation. Using TEM, we demonstrate that the fayalite component of the olivine is reduced to metallic iron giving the olivine a dusty appearence in transmitted light. The reduced olivine appears stable under high temperature reducing conditions. We suggest that diffusion of Mg2+ from the outer part of the olivine into empty Fe2+ lattice positions in the interior prohibits formation of SiO2 as by-product of the fayalite reduction. Some of the silica may also have left the olivine in form of gaseous SiO. Periclase reacts with Al2O3 from the tundish slag to form spinel. We show that Mn from the steel melt is oxidized and enriched in tundish slag as well as in the refractory. The steel melt is the only source of Mn in the slag. Thermodynamic calculations show that equilibrium fractionation of Fe and Mn between steel melt and slag results in effective separation of Fe (in steel) and Mn (in oxides/silicates).

Basic Refractories for Cement Rotary Kiln

Basic Refractories for Cement Rotary Kiln

Alkalies and Cement Clinker Reactions on Basic Refractories

Alkalies and Cement Clinker Reactions on Basic Refractories

A study of the Na 2O–CaO–P 2O 5–SiO 2 system with respect to the behaviour of phosphate bonded basic refractories at high temperature

Investigating various phosphate bonded basic refractories by means of powder X-ray diffraction, energy dispersive spectroscopy and X-ray fluorescence analyses, reveals a relation between good mechanical properties at high temperature and the presence of a silicophosphate bond ( T>1200°C). The silicophosphate formation mechanism was studied using X-ray thermodiffractometry. From room temperature up to 500°C, a mixed calcium sodium phosphate gel is formed. It transforms around 500°C into a crystalline calcium sodium phosphate which is not stable at room temperature. Above 1200°C, the silicophosphate belongs to a Na 2− x Ca 5+ x (PO 4) 4− x (SiO 4) x type solid solution with x>0 identified by studying the Na 2O–CaO–P 2O 5–SiO 2 system. The Na 2− x Ca 5+ x (PO 4) 4− x (SiO 4) x solid solution structure was shown to be a superstructure of the glaserite-type structure. Good mechanical properties of the refractory material are maintained as long as the silicophosphate glaserite-type unit cell superstructure is kept. That is achieved using starting raw materials with a high CaO SiO 2 ratio and a high calcium content.

Ceramic innovations in the 20th century

Ceramic innovations in the 20th century

Analysis of magnesia chrome refractories weared in a rotary cement kiln

Summary Magnesia chrome bricks are basic refractories which are essentially composed of magnesia and interstitial phases: Mg2SiO4 and Mg(Al1.5Cr0.5)O4. These refractories, used in the clinkering zones lining of moroccan cement kilns, have presented a premature wear. X-ray diffraction, scanning electron microscopy, and thermal expansion were used to characterize the damaged refractories. The colorimetric method shows the presence of toxic hexavalent chromium in the hot face of the refractory.

Toxic emissions in refractory production

Quantitative and qualitative characteristics of dust and gas emissions in the production of basic refractories are considered. The data obtained can become a basis for designing gas-cleaning for enterprises of the refractory industry.

Resource-saving technology for producing periclase powders with 92–95% MgO

A brief characterization of magnesite of the Satkinskoe Deposit and a technology for the production of periclase powders using two-stage firing of the raw material are presented. The quality of the fired product and the technical and economic parameters of the production of powders for basic refractories are described. Results on extraction of MgO into the fired products and an elemental analysis of caustic magnesite are presented. A possibility of two-stage firing in industrial conditions of reduced waste gases and quote of raw material consumption in the production process.

Influence of mechanical activation of basic refractories and mixtures on sintering

Mechanical activation leads to partial breakdown of the crystalline structures of refractory materials, conferring a higher reaction state on them. This is manifest as a reduction in the temperature range in which the magnesite and dolomite undergo conversions during heating, and also in the greater degree of exposure of the periclase and chrome concentrate.

A New Large Crystal Sintermagnesia: Production, Properties, Performance

The development of new basic refractory raw material is a complex process, one that requires careful consideration of many technological, economic, market and commercial factors. This paper reviews the issues considered and the approach adopted by the sea-water magnesia manufacturer, Premier Periclase Limited, Drogheda, Ireland, in the development of a new synthetic large crystal sintermagnesia.Because of the heavy dependence on magnesia usage in steel- making, key technical and market developments in that industry over the past 10–15 years were examined. This, combined with a study of basic refractories development and their wear mechanisms in steel plant applications enabled the formulation of a sound product strategy. Finally, the development programme from initial prototype material preparation and testing to plant selection and product launch in late 1990 is described.

A combined lining of the sintering zone of rotary kilns for firing of magnesite

Increased wear resistance of a combined lining consisting of acid and basic parts in the sintering zone of rotary kilns for firing of magnesite was established on the basis of chemical and petrographic investigations and visual observations. The wear of ShB aluminosilicate parts is by fusion and of PKhTs refractories primarily by spalling. The ShB parts have a lower wear rate. The positive effect from the combination of PKhTs and ShB parts in a combined lining is obtained both between them and with the material being fired in the kiln. The products of chemical interaction of ShB and PKhTs parts are refractory minerals (spinel and forsterite) and low-melting compounds (glassy phase and cordierite). The increase in wear resistance of the combined lining is caused by contact burning together (welding together) of the high-temperature layers of the parts with formation of a monolith. The use of a combined lining of the sintering zone is recommended for introduction into rotary kilns of the cement and other industries for the purpose of economy in basic refractories. It should be noted that at present unfired chromite-periclase parts with 35.1 wt.% R2O3, 55.4 wt.% MgO+CaO, and 0.8 wt.% P2O5 are being successfully used as the basic refractories in a combined lining to decrease fuel and raw material consumption. Their compressive strength is 45.3–53.9 N/mm2 and their open porosity 10.8–15.1%.

Microstructural and Chemical Studies of Stainless Steel/Refractory Interaction

The experimental work investigates the behavior of commercial‐grade aluminosilicate and basic refractories in contact with stainless steels at 1630°C in an argon atmosphere. For the aluminosilicate refractories, Mn proves to be the most deleterious to these refractories. For the basic refractories, silicon is the most destructive element attacking the magnesioferrite phase to produce a complex silicate of magnesium, managanese, and calcium. The presence of metal droplets in the hot face of every steel/refractory system is explained on the basis of disproportionation and reaction of lower oxides, especially CrO.

Wear Pattern of Basic Refractories in the Burning Zone of Rotary Cement Kiln

Wear Pattern of Basic Refractories in the Burning Zone of Rotary Cement Kiln

Relation between Bonding Texture and High Temperature Strength of Basic Refractories for the Cement and Lime Kiln

Relation between Bonding Texture and High Temperature Strength of Basic Refractories for the Cement and Lime Kiln

Magnesia—An important Industrial Mineral: A Review of Processing Options and Uses

Magnesia is widely used as an important component in basic refractories, as an animal feed supplement, fertilizer, insulation material, cement, and in several environmental control procedures. The major sources of magnesia are magnesite, seawater and brines. Less important sources are dolomite, bitterns and salt deposits. This review outlines the more significant physical and chemical processes for the production of the various grades of magnesia and discusses some of the more important uses of magnesia. Consumption of magnesia in basic refractories is slowly declining and future market growth will be largely restricted to chemically reactive magnesia (caustic calcined magnesia).

An alternative technology for making carbon containing basic refractories

An alternative technology for making carbon containing basic refractories

High quality chrome-bearing basic refractories from brine magnesia

Abstract Pure magnesia (>96% MgO) was recovered from marine brine of high MgCl2 content using calcined dolomitic magnesite as alkali precipitating agent. High quality chrome-bearing refractories were obtained from clinkers produced by joint fine grinding and firing at 1550°C of the dried Mg(OH)2 paste with different amounts (10, 20, 35 wt. %) of common chrome ore and chemically enriched ore. The technical characteristics of the basic refractories were improved as the chrome content is increased up to 20% common ore and 35% chemically enriched ore. On substituting the common ore by the chemically enriched one the properties of the refractories were remarkably improved due to lower silicate level (about 2%) and higher chrome spinellide content. The properties of the basic refractories were correlated with their different constituent phases.

Reaction between Lime and Basic Refractories with Different Textures

Reaction between Lime and Basic Refractories with Different Textures

Influence of Alkalies on the Basic Refractories in the Rotary Cement Kiln

Influence of Alkalies on the Basic Refractories in the Rotary Cement Kiln