Refractory Industry Research Articles

Complex utilization of the useful components of the andreye-yulyevskoe kyanite tecnogenic deposit (Southern Urals)

Utilization of sillimanite group’s minerals (kyanite, sillimanite, andalusite) in high-aluminiferous refractory industry with a purpose of following utilization in metallurgy to obtain silumine and aluminium by elctrothermic method is impossible without new resources. A one of them is the Andree-Yulyevskaya group of kyanite-bearing technogenic objects. Technogenic deposits formed as a result of alluvial gold deposits’ exploitation at the Southern Urals is an additional source of the complex mineral products. A concentration of minerals of the technogenic objects is higher than initial alluvial placers’ one in n10-n1000 times. During the valuation of industrial potential of the Andree-Yulyevskayakya tetechnogenic deposit, (Southern Urals) a concentrate method of technogenic sands’ sampling has been used which permits estimating a gold placers’ potential of the technogenic objects with poor gold and rutile as a useful additional mineral has been distinguished. As a result of researches a principal technological scheme of technogenic sands’ concentration permitting to obtain kyanite concentrates with content of Al2O3 of 55.5 (%) to 60.2 (%) — the main product and gold-bearing and rutile concentrates as additional products. Complex extraction of kyanite, gold, and rutile from technogenic objects has a commercial attraction of this type deposits’ exploitation.

Analysis of the conditions of the process of regeneration of high-temperature filters in the case of dust collection in the refractory industry

A study of different types of ceramic filter materials that have shown promise in applications in the temperature range 500 – 850°C is performed. Features are illustrated and the problem of filtration at high temperatures is demonstrated. Strategies for increasing the effectiveness of regeneration are proposed.

Clean Chromite Production from Fine Chromite Tailings by Combination of Multi Gravity Separator and Hydrocyclone

Chromite is an important mineral used in the metallurgy, chemistry, and refractory industries. For this reason, beneficiation of chromite tailings is very important. In this study, the possibility of beneficiation of chromite tailings in the Uckopru/Fethiye-Turkey region by Hydrocyclone and Multi Gravity Separator (MGS) combination was investigated. The two signification operational parameters of hydrocyclone, which were diameter of apex and diameter of vortex, and the three signification operational parameters of MGS, which were drum speed, tilt angle, and wash water, were varied and the results were evaluated with the Central Composite Rotatable Design. The results of beneficiation studies showed that commercial concentrate containing 48.18% Cr2O3 was obtainable with a 69.79% rate of recovery.

Spectral pathways for effective delineation of high-grade bauxites: a case study from the Savitri River Basin, Maharashtra, India, using EO-1 Hyperion data

Bauxite, the only source of aluminium, is an aggregate of minerals, most of which are oxides and hydroxides of aluminium and iron such as gibbsite, bohemite, goethite and haematite. Bauxite is used in the chemical and refractory industries and its quality is controlled by the presence of impurities such as iron and silica. Bauxite commonly occurs together with iron-rich laterites as alteration products of parental igneous and metamorphic rocks. Aluminium-rich bauxites grade towards highly ferruginous laterites with a transitional Al-rich laterites or ferruginous bauxite, herein described as Al-laterites. In the Savitri River Basin, bauxite contains 58–75% gibbsite, 6–11% goethite and 19–26% haematite, whereas the mineralogy of Al-laterites and Fe-laterites are dominated by haematite (29–68%) and goethite (6–25%) with subordinate amounts of gibbsite. Conventional techniques to demarcate the high-grade pockets of bauxites rich in gibbsite are tedious, time consuming and involve detailed field sampling and geochemical analyses. Our work illustrates how spectral properties of these three litho-units can be effectively utilized in mapping of high-grade bauxites occurring over wide areas using hyperspectral remote sensing (HRS). The methodology adopted herein involves generation of noise-free field spectral database of target materials, linear unmixing of field spectra for constituent minerals, classification of preprocessed Hyperion images using field spectra and finally accuracy assessment for ore grade estimation. It is observed that bauxite mapping using Hyperion data and noise-free field spectra yielded results that correlate well with the chemistry and mineralogy of representative samples. By adopting the above procedure, we achieved classification accuracies of 100%, 71% and 89% for bauxite, Al-laterite and Fe-laterite classes, respectively.

Different Additives to Inhibit Magnesia (MgO) Hydration

Magnesia (MgO) is a fundamental component of many minerals found in nature and is used widely in our life, especially in refractory industry. However, the antihydration of MgO is a key concern in refractory suspension processing, MgO additions only in form of coarse particles(≥ 50 μm) or its contents of up to 10 wt.% are as a result of their high possibility to take place hydration reaction in water and the reaction can lead to volumetric expansion obviously. In the present work, citric acid (CA) can complex with Mg2+ in the MgO suspension under the condition of 4h and 25°C, and the deposit of magnesium ion-CA complexes become protective coating to inhibit magnesia react with water to form Mg(OH)2.The test results of RSV of different additives shows CA is the best antihydration compound to inhibit MgO hydration comparing with EDTA-2Na，sodium pyrophosphate(SP)，trimeric sodium phosphate(TSP), which RSV is only 5.3ml when its dosage is 0.3%wt.

Steelmaking. Use of refractory materials. Correction of trends. Predictions

An analysis of the development in 2011 of ferrous metallurgy, the principal consumer of refractory materials, together with predictions for the development of metallurgy and the refractory industry in the Community of Independent States (CIS) in the next few years are presented. Different trends and aspects of the development of the refractories industry in CIS as a constituent element of the world market for the production and consumption of refractory materials are analyzed.

Influence of Nanocrystalline MgAl2O4 Spinel Addition on the Properties of MgO-C Refractories

Nanopowders of magnesium aluminate (MgAl2O4) spinel, prepared through citrate-nitrate gel method and calcined at 800°C, were incorporated to the matrix of magnesia-carbon (MgO-C) refractory. The physical and chemical properties of the nano-MgAl2O4 spinel-added (0.5 and 1.0 wt%) MgO-C bricks were compared with those of MgO-C bricks containing no spinel and commercially available micron-sized (<45 µm) stoichiometric spinel (AR-78). It was observed that nano-spinel (NS) (1 wt%) containing MgO-C refractories effectively prevents the oxidation, slag corrosion, and penetration resistance compared to MgO-C bricks with or without micron-sized spinel added. The average pore diameter decreases, and the concentration of the fine pore increases with addition of nano-MgAl2O4 spinel in the matrix of MgO-C bricks. Due to the lower pore size and higher concentration of fine pores as well as higher amount of carbon retention, nano-MgAl2O4 spinel-added MgO-C bricks show better physical as well as chemical properties and may have potential applications in both steel and refractory industries.

Development of Cordierite Honeycomb Ceramics Using Cordierite Waste

Cordierite ceramics (2MgO·2Al2O3·5SiO2) were prepared from cordierite waste from refractory industry. The composition of the mixture composed of 70 wt% cordierite waste powder, 23 wt% talc and 7 wt% alumina mixing with binders, plasticizer, lubricant and water to form ceramic dough. The cordierite samples were sintered at 1250-1350 °C for 2 h. All samples were investigated in terms of phase composition, microstructure, bending strength and thermal expansion coefficient. It was found that the sample sintered at 1300 °C achieved the single phase of cordierite with the bending strength of 21.70 MPa and the lowest thermal expansion coefficient of 2.94×10−6 °C−1 observed in this study.

Processing of refractory materials using various magnesium sources derived from Zinelbulak talc-magnesite

Magnesia (MgO) is widely used in the production of refractory materials due to its high melting point, high thermal shock, and excellent slag resistance. The properties of refractory materials depend upon magnesia sources and processing parameters. In this work, three different magnesium sources, namely, magnesium hydroxide concentrate, magnesium carbonate concentrate, and intermediate flotation concentrate, were obtained from the Zinelbulak talc-magnesite, Uzbekistan, by causticization-hydration and flotation processes, respectively. A series of refractory materials were prepared on the basis of these magnesium sources, and their effects on physico-mechanical properties and microstructures were investigated as a function of sintering temperature, molding pressure, and the particle size of magnesium sources. The experimental results showed that a refractory material obtained from the magnesium hydroxide concentrate at 1600°C for 4 h demonstrated favorable parameters due mainly to a higher degree of contact among fine particles. The results obtained from X-ray diffraction and optical microscopy confirmed the presence of periclase and forsterite as the predominant phases in refractory specimens. The prepared refractory materials meet the requirements of the State Standards (Nos.4689-94 and 14832-96) for magnesia and forsterite refractories, respectively. It is, therefore, suggested herein that the use of different magnesium sources derived from the Zinelbulak talc-magnesite will offer the potential to provide economic benefits in the refractory industry.

Measuring the perception of safety officers on occupational health in Indian industries

Perceptions and understandings of risk in occupational health and safety (OHS) among employers and employees influence the control of risk at work. Critical analysis of OHS standards implementation reveals that the dimensions and the variables responsible for improving health and safety norms widely vary across industries and locations. A study of risk perceptions and understanding in OHS by safety officers have been conducted in three Indian industrial sectors, e.g. construction, refractory and steel industries. A broad-based questionnaire is prepared covering various aspects of current OHS practices in industries. The responses are analysed using factor analysis and ten factors are extracted and interpreted. Finally, identified factors again analysed using discriminant analysis to highlight statistical difference among practices existing in three sectors. Findings of the study suggest that perception of safety officers has positive influence on factors such as injury avoidance, work practices, standardisation, healthcare and risk management.

The Exploring Research of the Determination Method of Magnesium Oxide Hydration

Magnesium oxide is one of the most important raw materials in the refractory industry due to its high melting point (2800oC), corrosion resistance in the basic environment, and low cost. Nevertheless, magnesium oxide reacts easily with water to produce magnesium hydrate, which is followed by a large volumetric expansion, limiting its application in refractory industry. As the hydration of MgO is very important either in theory or in industrial production of magnesium, in this paper, the influence of temperature, residence time, as well as the impact of the solid content on MgO hydration and the kinetics of hydration reaction was evaluated to optimize the determination method of magnesium oxide hydration in refractory industry.

Beneficiation of Iranian magnesite ores by reverse flotation process and its effects on shaped and unshaped refractories properties

The primary aim of this study is the beneficiation of magnesite ores from eastern part of Iran by reverse flotation process. For this purpose, the mineralogical and microstructural characteristics of the as-received and the processed ores from Iranian Afzal Abad mine were established. The liberation degree of ore was estimated at about 75 µm. Then the as-received ore and the processed one were dead burnt to produce magnesia aggregates. These aggregates were used for production of shaped and unshaped refractories. Bricks and monolithic ramming mixes which were made from these aggregates were analysed and their mechanical and physical properties, studied. The results of this investigation showed that the application of reverse flotation process on the magnesite ore of eastern part of Iran causes an acceptable reduction on the amount of its siliceous inclusions, so that this type of the processed magnesia is suitable for utilization in the refractory industries. The magnesia produced from the original calcined ore was not suitable for this industry due to the presence of unacceptable amount of siliceous inclusions, which make its properties very poor.

Mulitização em refratários utilizando diferentes fontes precursoras: revisão

A mulita é uma fase cerâmica obtida pela reação entre alumina e sílica em temperaturas elevadas e amplamente utilizada em refratários devido as suas excelentes propriedades. Muitos trabalhos na literatura estudaram e analisaram a síntese de mulita, bem como sua incorporação em refratários, que pode ser feita pela adição do pó pré-formado ou pela obtenção in-situ. Esta revisão une os principais trabalhos publicados sobre síntese de mulita focando principalmente aspectos da cinética da reação, como a ocorrência de fase líquida metaestável durante a mulitização, etapa inevitável para o processo. O trabalho traz também um panorama geral das diversas fontes silico-aluminosas precursoras e das características e propriedades da mulita obtida a partir de cada uma delas. O estudo sugere que a utilização de sílicas e aluminas de alta reatividade favorece a mulitização reduzindo a temperatura de obtenção e a quantidade de fase líquida residual.

Characterization and origin of spongillite-hosting sediment from João Pinheiro, Minas Gerais, Brazil

Abstract Spongillite from Joao Pinheiro, Minas Gerais, Brazil is mainly known for its use in brick production and in the refractory industry. Very few studies have focused on its geological context. Spongillite-rich deposits occur in shallow ponds on a karstic planation surface developed on rocks of the Neoproterozoic Sao Francisco Supergroup. Cenozoic siliciclastic sediments are related to this surface. A field study of these deposits and analysis of multispectral images showed a SE–NW preferential drainage system at SE, suggesting that Mesozoic Areado Group sandstones were the source area of the spongillite-hosting sediments. Mineralogical and textural characterization by optical microscopic analysis, X-ray diffraction (XRD), differential and gravimetric thermal analysis (DTA-GTA), infrared spectroscopy (IR) and scanning electron microscopy (SEM) of seven open-pit spongillite-rich deposits (Aviao, Carvoeiro, Vânio, Preguica, Divisa, Severino, Feijao) showed a sedimentological similarity between the deposits. They are lens-shaped and are characterized at the bottom by sand facies, in the middle by spicules-rich muddy-sand facies and at the top by organic matter-rich muddy-sand facies. Petrographically, the spongillite-hosting sediments and the siliclastic sediments of the Areado Group show detrital phases with similar mineralogical and textural features, such as the presence of well-sorted quartz grains and surface features of abrasion typical of aeolian reworking that occurred in the depositional environment in which the sandstones of the Areado Group were formed. Detrital heavy minerals, such as staurolite, zircon, tourmaline, and clay minerals, such as kaolinite, low amounts of illite, scarce chlorite and mixed-layer chlorite/smectite and illite/smectite occur in the spongillite-hosting sediments and in sandstones from the Areado Group. In both formations, staurolite has similar chemical composition. These mineralogical and textural features show that the sediments of the Areado Group constitute the main source of the pond sediments that host spongillite.

Reactive alumina production for the refractory industry

In this study, fine reactive alumina powder production was investigated using Bayer gibbsite as a starting material. Experimental studies consist of three steps; in the first step, the soda content was reduced by means of boric acid and distilled water. In the second step, the effect of heating rate and calcinations temperature on crystal size, phase transformation and surface area were investigated and characterization of the powders was performed by means of XRD and SEM analyses. In the third step, the powders obtained optimum conditions were ground in an attritor mill and then particle size distribution and surface area were measured. The soda content of the gibbsite was reduced from 0.325 to 0.05% by H 3BO 3 treatment, calcination at 1200 °C and then washing in distilled water. The higher the heating rate, the smaller the crystal size is. Alumina ceramics with a density higher than 94.70% of theoretical density were obtained.

Thermal behavior of Zefreh dolomite mine (Central Iran)

Dolomite has a large amounts of MgO and is an important raw materials for steel, iron and refractory industries. In this paper thermal behavior of Zefreh dolomite at various temperatures was studied by differential thermal analysis (DTA), Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT - IR) and powder X-ray diffraction (XRD) techniques. The DTA curve shows two endothermic peaks at 772 and 834?C. The first peak is associated with the formation of magnesia (MgO), calcite(CaCO3) and CO2. The second peak represents the decomposition of calcite with formation of CaO and further CO2 release. At 772?C quantitative XRD analysis in atmospheric condition shows small amounts of CaO (less than 2%) which form simultaneously or later than calcite. TGA curve shows total weight loss for decomposition of dolomite is 46.2%. By increasing heating time of samples in furnace, dolomite decomposes in lower temperatures. X-ray diffraction analysis of heat treated samples up to 750?C indicates that dolomite structure changes into calcite. The increases in quartz content accelerated the mechanochemical deformation and amorphization of dolomite phase. At high temperature ( more than 1000?C) Ca3Mg(SiO4)2 and CaSiO4 were formed. XRD and FTIR confirm dolomite decomposition reactions.

OAO Krasnogorovka Refractory Plant innovative technology

The Krasnogorovka Refractory Plant is one of the leading enterprises of the refractory industry with more than 100 years of experience of producing high quality refractory materials. The plant was founded in 1899 as the Societe Franco-Russe de Krasnogorofka as a plant for producing quartz and silica bricks, ceramic fireplaces and bottles. Before 1905 the plant operated seasonally. Currently the plant is one of the largest enterprises in the area of refractories. The number of production personnel is 1353. The annual volume of production in 2007 was 125 thousand tons. The plant produces dinas, aluminosilicate refractories, and also unmolded materials of silica and aluminosilicate compositions. In view of the reduction in demand for traditional forms of refractories the plant has renewed its production range. In 2003 an innovation center was created whose efforts were directed towards expansion of the product range and an improvement in quality. Considering the increased specifications for contemporary refractory materials the specialists of the center started independently to develop and assimilate production technology for starting mixes for filling the pouring channel of steel-pouring ladle. It would be necessary to offer the user a competitive product with properties not surpassed by overseas analogs. Several compositions of mixtures were tested under laboratory conditions with different feedstock materials and grain size composition undergoing tests at high temperature. After analyzing test results samples of mixtures were prepared for testing under industrial conditions in the “upstream pouring” of the Il’ich OAO MMK converter workshop. Mixtures were tested during pouring of rimming and killed grades of steel; mixtures similar in composition to the starting mixes were tested during pouring steel in a CBCM. Metal was in the ladles from delivery to pouring in a CBCM from 1.10 to 1.36 h. All ladles were opened spontaneously without using oxygen pipes, but due to difficulties that arise during charging mixes into the ladle pouring channel the composition of the starting mix was modified; a new test-industrial batch was prepared taking account of the requirements of metallurgists. Mixtures were tested in the OAO MMK im Il’icha converter workshop both in the CBCM and in the “upstream pouring” with delivery of different grades of steel; the duration of metal in the ladle from the start of delivery to the start of pouring was 0.37 to 2.26 h. The test starting mix providing uniform opening capacity for the delivery channel and correspondingly a uniform stream, and least metal splashing. The opening capacity of the slide gate channel without using oxygen pipes was 95.6%. By achieving good results for opening capacity, the OAO Krasnogorovka Refractory Plant proposed using their starting mixes for charging the channel of the ladle nozzle during pouring steel in various metallurgical enterprises of Russia and the Ukraine. Channel opening capacity for the slide gate using starting mixes in different enterprises was: 97.8% in OAO Alchevsk Metallurgical Combine, 95.8% in OAO Novolipetsk Metallurgical Combine, 92.5% in Dzerzhinskii Dneprovsk Metallurgical Combine, 100% in OAO Mechel, 100% in OAO Izhstal’. In OAO Izhstal’ the starting mix was tested in slide gates of a 30-ton ladle of the furnace-ladle unit. Structural low-alloy steel was processed in the ladles. The pouring temperature was 1560 – 1580°C. On opening the slide gate the mix spontaneously ran out of the pouring nozzle channel in all melts. The results of industrial tests of starting mixes in metallurgical enterprises of Russia and the Ukraine both in the “upstream pouring” and in a CBCM showed that the mix has high operating characteristics and it properties it is no worse than overseas analogs. Use of a starting mix in OAO KrOZ for charging the steel-pouring channel almost entirely excluded washing away of the pouring opening of a steel-pouring ladle before metal delivery. OAO KrOZ independently developed and introduced technology for competitive refractory production not manufactured by other refractory enterprises in the Ukraine. In view of this the question arose of developing normative and technical documentation for starting mixes. The enterprise Refractories and Industrial Ceramics Vol. 50, No. 1, 2009

Anisotropic behaviour of andalusite particles used as aggregates on refractory castables

Andalusite is a well known alumino-silicate mineral largely employed in the refractory industry in order to provide high mechanical properties and thermal shock resistance. This work is devoted to the study of the thermal expansion behaviour of andalusite aggregates used in refractory castables. Anisotropic thermal expansion behaviour has been underlined by dilatometric measurements on andalusite single crystals according to their crystallographic axes. This behaviour can be magnified by the presence of quartz, even in small quantity, as impurities in the andalusite particle. The anisotropy of dilation is preserved after mullitisation of andalusite. These important results make it possible to explain the origin of the diffuse damage observed in andalusite-based castables which is most probably responsible for the enhancement of the strain to rupture required for the good thermal shock performance of such material.

Hydrodynamic molding method — a tool of resource-saving technology in ceramic and refractory production

A concept of ceramic refractory technology is formed, based on advanced examples of material nano-, micro-and macrotechnology, of the technique of high and elevated pressure (0.1-1.0 GPa), high-speed (pulsed, 5-15 msec) loading and molding of powder heterocompositions in hydrodynamic machines of the HDM class, performed under the action of propellant explosive substances (ES), manufactured from inexpensive artillery powders. Control of dynamic and production parameters for molding objects is provided by the weight of ES charge or the charging density in the hydrodynamic machine (HDM) combustion chamber. Scientific and technical bases created in GNU IPM NAN Belorussii for ceramic and refractory technology based on high energy pulsed compaction make it possible to organize and assimilate output of a broad range of objects for the ceramic and refractory industries.

Synthetic spinels of the system MgO-Cr2O3-Al2O3-Fe2O3

Synthetic spinels of the system MgO-Cr 2 O 3 -Al 2 O 3 -Fe 2 O 3 are considered and the desirability of organizing their production for the refractory industry is demonstrated.