Refractory Industry Research Articles

A Fuzzy Mathematical Programming Model for Sustainable Supply Chain under Competition and Uncertainty Environment

In this paper, a fuzzy mathematical programming model based on the nested model is proposed to design a sustainable multi-product, multi-period supply chain network (including three parts of the procurement, production and distribution) under the competition and uncertainty conditions. Sustainability measures are carried out using previous studies and the supply chain operations reference (SCOR) model is extracted in each of the sustainability dimensions and then localised using the fuzzy Delphi method. In order to determine the relationship between indicators and the importance of each index, DEMATEL method is used and then the obtained fuzzy model is converted into a crisp one. To demonstrate the efficiency of the model, a real example is presented in the refractory industry. Finally, the results are analysed and suggestions are presented.

Interlaboratory comparisons of the results of the work of the chemical­analytical unit of JSC “The URIR named after A. S. Berezhnoy” in 2018

One of the activity areas of JSC “The URIR named after A. S. Berezhnoy” is assistance to refractory industry enterprises of Ukraine in ensuring their work in the quality monitoring of products and raw materials.
 The comparison of work quality of chemical­analytical units of following enterprises: JSC “KDZ”, PJSC “Chasovoyarsk Refractory Plant”, JSC “Velikoanadol Refractory Plant” and JSC “The URIR named after A. S. Berezhnoy” was carried out. The discrepancy between the average results of components determination in the chemical­analytical units of refractory enterprises and in the chemical­analytical laboratory of JSC “The URIR named after A. S. Berezhnoy” does not exceed the value of in terms of ND. The work quality of chemical­analytical units of central refractory laboratories of all the above mentioned enterprises is satisfactory. Recommendations to improve the accuracy of analysis results are not required.
 The work on interlaboratory comparison of work results of the chemical­analytical unit of JSC “The URIR named after A. S. Berezhnoy” and IP “SGS Ukraine” was completed. The quality of interlaboratory comparisons carried out between the Testing Centre of IP “SGS Ukraine” and JSC “The URIR named after A. S. Berezhnoy” was found to be satisfactory. The test results were accepted by the NAAU during the next inspection as corresponding to DSTU ISO / IEC 17025:2006.

Refractory Grade Bauxite: An Overview about the Effects of different Bauxite Sources and Forming Processes on the Quality of the Material

Refractories have been very important for humankind development enabling the manufacturing of a wide range of materials. Primary industries demanding refractories include the manufacturing of steel, non-ferrous metals, glass, lime, cement, ceramics, petrochemicals and incineration. Refractory grade bauxites (RGBs) are high-alumina materials used as aggregates in shaped and unshaped refractory linings suitable to with stand high temperature heating and a corrosive environment. Despite the wide availability of bauxite ores in the world, few countries can supply a bauxite with refractory grades. Guyana, China and Brazil have emerged as suppliers for the refractory industry and the peculiarities of each bauxite from these countries impact directly on the refractory performance.

A MASK-RCNN Based Approach Using Scale Invariant Feature Transform Key points for Object Detection from Uniform Background Scene

Object identification using deep learning in known environment gives a new dimension to the research area of computer vision based automation system. As it uses supervised learning technique using Convolution Neural Network (RCNN) it helps automation software tools and machines to detect and identify objects using vision based systems. One of RCNN technique known as Mask-RCNN has been applied in this proposed design and this paper presents a novel approach to object detection problem using Big Data storage for large set of features based data. Earlier work Faster Region-based CNN has led to the development of a state-of-the-art object detector termed as Mask R-CNN. Some samples of solid material objects used in refractory industry have been taken as input images. In our experiment the SIFT based features have been implemented and trained using filter and convolution operation. In addition to improved accuracy, pixel-level annotation (annotating bounding boxes is approximately an order of magnitude which is quicker to perform). The model is retrained to perform the detection of four types of metal objects, with the entire process of annotation and training for the new model per solid block. A key benefit of feature based Mask-RCNN approach is high precision (~94%) in classification and minimized feature points with SIFT key points.

Possibility of obtaining high-alumina materials from industrial wastes of ceramic and refractory industry (Review)

The issues of obtaining aluminum oxide from man-made materials, the issues of differences in the structure, composition and properties of alumina obtained by different technological methods and the issues of providing high-alumina materials to the domestic ceramic, electronic and refractory industries are reviewed.

Acidic methods of alumina production (Review)

The requirements for special alumina for the ceramic, electronic and refractory industries are considered. The analysis and comparison of acidic methods of obtaining alumina from the point of view of efficiency, manufacturability and safety of production are given. The risks of acidic methods of alumina production are estimated. The advantage of variants of the sulfuric acid method is substantiated. 1ll. 1. Ref. 54.

Waste rice husk ash derived sol: A potential binder in high alumina refractory castables as a replacement of hydraulic binder

This work provides a new source of binder system, i.e., waste rice husk ash (RHA) derived sol for unshaped refractories. A facile (alkali extraction) route is used to synthesize the sol from the waste RHA. The sol consists of single phase amorphous silica with average particle size around 22 nm. The estimated cost of 30 wt% solid containing RHA derived sol per litre is around 9.35 $. The temperature of mullite (3Al2O3·2SiO2) formation from waste derived sol and reactive alumina containing system is 1250 °C or higher. The sol (30 wt% SiO2) and the dry sol (99.32 wt% SiO2) is used to formulate the high alumina castable samples. The sintering is performed at 1400 °C, 1500 °C and 1550 °C. The different physico-mechanical characterizations and blast furnace slag (BFS) corrosion test at 1500 °C are comprehensively investigated with the prepared castables. The properties of 5 wt% silica (3 wt% from sol and 2 wt% dry sol) containing castable specimens are also equated with the commercially available different silica containing high alumina castable systems. The obtain results are good agreements with the source data. These promising characteristic confirms the possibility of using waste RHA derived sol for manufacturing of cement free high alumina castable and leads to the economic and ecological benefits in the refractory industries.

Acidic Methods of Alumina Production (Review)

Requirements for special-purpose alumina for the ceramic, electronic and refractory industries are considered. Analysis and comparison of acidic methods for preparing alumina from the point of view of efficiency, adaptability and production safety are provided. The risks of alumina acidic production methods are estimated. The advantage of the sulfuric acid method versions is substantiated.

Emission Characteristics and List of Inorganic Elements in Fine Particles of Typical Industrial Kilns in Zhengzhou City

Samples of particulate matter from flue gas emissions of typical brick, cement, and firebrick industrial kilns in Zhengzhou City were collected by dilution channel systems. Cr, Mn, Fe, Co, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Ni, Cu, Zn, Ga, As, Se, Sr, Cd, Sb, Sn, Ba, and Pb were analyzed. The emission factors (EFs) and emissions of inorganic elements of PM2.5 from kilns flue gases of three industries in Zhengzhou City during 2016 were calculated. A grid list of 1 km×1 km was also established. The results show that the highest concentration of total inorganic elements was in the firebrick industry, corresponding to(609.97±490.97) μg·m-3. The concentration of inorganic elements in the three industries accounted for 34%-54%, 27%-42%, and 23%-53% of PM2.5. The inorganic elements emitted from industrial kilns in brick and cement industries were mainly crust elements, and the highest concentration elements were Cl and Al. The inorganic elements emitted by industrial furnaces in the firebrick industry were mainly heavy metals, and the highest concentration element was Pb. The coefficient of divergence (CD) of inorganic elements in brick and cement industry was 0.389, that is slightly different. The CD between cement and refractory industry was 0.732, which represents a significant difference between inorganic element emissions. In 2016, the emissions of Pb, S, Zn, Cl, K, As, Fe, Si, Cr, Al, Na, and Ca in PM2.5 from major industrial furnaces in Zhengzhou City were 919.0, 793.1, 124.7, 378.6, 82.6, 12.2, 60.4, 145.4, 7.4, 86.6, 15.8, and 111.4 kg·a-1, respectively. Heavy metal emission in the Xinmi area was the highest, representing a high health risk.

Hydration mechanism and sintering characteristics of hydratable alumina with microsilica addition

Abstract Hydratable alumina is potential for the application in refractory industry as one of Ca-free binders, but it is greatly limited because of the excess hydration of rho-alumina (ρ-Al2O3). In this study, hydration mechanism and sintering characteristics of hydratable alumina with different microsilica addition are researched, via the rheological, hydration, and morphological characteristics of ρ-Al2O3–SiO2–H2O system during aging are analyzed using various techniques. Boehmite (AlOOH) initially appears and increases in content after 1 h aging at the setting temperature of 30 °C and relative humidity of 80%. As the addition of microsilica increases from 0 wt% to 8 wt%, the SiO2 coating combines with the boehmite gel and efficiently suppresses the hydration reaction, resulting in decrease of relative hydrated densities from 5.42% to 4.27% and increase of zeta potential from −10.1 mV to −21.3 mV. Further, the thus-formed SiO2-AlOOH gels cover the surface of hydratable alumina particles, connect with each other, and get distributed homogeneously around hydratable alumina particles to harden, thus inhibiting the further hydration. This is reflected by the high-temperature X-ray diffraction and the final sintering microstructures. Overall, these results indicate that the 6 wt% addition of microsilica makes hydratable alumina promising for application as a kind of controlled binders.

Investigations of quartz raw materials from the locality of Rekovac muncipality

Quality of raw materials, including quartz sand and quartzite, varies from one deposit to another. Furthermore, the material quality determines in which industrial branches it can be used after certain preparation processes. Potential applications of quartz raw materials are: in the construction and refractory industry, ceramics and glass industry, then in metallurgy, foundry and also in production of water treatment filters. Geological investigations of the central Serbia region, in the Rekovac municipality, resulted in identification of occurrence of quartz sand ("Ursula") and quartzite ("Velika Krusevica"). Preliminary laboratory tests and characterization of the quartz sand size fraction -0.63+0.1 mm confirmed the possibility of applying this size fraction in the construction materials industry, while the quartzite can be used in refractory, glass and metallurgy industries. After determining the geological reserve of quartz sand "Ursula" and quartzite "Velika Krusevica", detailed investigations are required. Quality conditions from the aspect of chemical composition and physical properties of quartz sand and quartzite are mostly clearly defined by a special standard for this purpose. On the other hand, there are also application areas where standards does not exist, but users define their quality conditions. This example is with the application of quartz sand in the production of water glass. Chemical composition as well is not always the determining factor for the application of quartz raw material. For example, for quartz sand used for sandblasting, grain form is essential. From the economic analysis point of view, the prices of quartz raw materials vary depending on their chemical and physical properties. After all, what needs to be pointed out is the fact that these raw materials are very widespread in nature and that their exploitation is quite simple. After the raw material is excavated, it is stored and further sieved, washed, dried and processed according to customer requirements. All of these processes are cheaper than preparing, for example, limestone, and significaly cheaper than preparation of metal ores.

The potential usage of waste foundry sand from investment casting in refractory industry

Application of waste foundry sand (WFS) obtained from investment casting in refractories is a promising alternative developed in recent years for reducing waste landfill while also producing high-value products. It is important to enlarge the applicable area in a refractory, especially with the increasing generation of WFS and growing tension in global mineral supply. Systematic studies on as-received WFS and its microstructure evolution after thermal treatment are rare; this imposes restrictions on using WFS in various applications. In this study, WFS is systematically analyzed, and the microstructure evolution of WFS specimens with thermal treatment at 1300–1550 °C is investigated. Quantitative analysis of the crystal phases indicates that WFS contains 46.2 wt% mullite, 28.1 wt% cristobalite, and 10.9 wt% zircon; the main oxidation states of Fe and Ti in WFS are Fe3O4 and TiO2. Leaching of WFS is hazardous; Thermal treatment below 1500 °C is harmless. The transformation of tetragonal ZrO2 to monoclinic ZrO2 in the specimens sintered at 1500 °C reduces the cold modulus of rupture, and Fe2O3 decomposition at 1550 °C reduces the bulk density and modulus of elasticity. Phase changes significantly affect the true density and melting of cristobalite at 1550 °C causes a sharp decrease in density.

A process of carbon enrichment of bottom slag ash for value-added applications

Coal is the primary source of energy in India. Coal ash obtained after coal combustion is considered a waste and dumped near the plant. Storage of coal ash close to thermal and other plants has now become a serious problem and creates environmental pollution. Coal ash contains an appreciable amount of unburned carbon, which can be recovered and reused as a source of energy; whereas the carbon-free ash can be utilized in cement, refractory, and fertilizer industries. Thus, there is a need to apply an effective separation technology to recover unburned carbon from coal ashes. In this study, a froth flotation technique was used to recover unburned carbon from a boiler bottom slag. The effect of particle size, conditioning time, and collector combination was studied to achieve maximum selectivity. The optimum liberation size of bottom slag was found to be around 150 µm (100 mesh size) with a conditioning time of 2 min. Furthermore, it was observed that a collector with a 1:1 proportion of kerosene and fuel oil with methyl isobutyl carbinol as the frother provides significant results. The carbon content in the concentrate was increased from 17% (7283.3 kJ/kg) in the feed to 40% (17990.6 kJ/kg) in the final concentrate and can be recycled as fuel, whereas the tailing fraction with carbon content less than 6% can be used in cement, concrete, and refractory industries.

Identification of principles for calculating composition of heavy magnesia concrete

The article suggests a method for obtaining heavy magnesium concrete on alternative materials, which are magnesium wastes of the mining and refractory industries. The advantages of using a magnesium oxychloride cement as a binder component of a concrete mixture are described. The suitability of the existing methodology for calculating the composition of heavy magnesium concrete has been analyzed and the need for its deep processing has been established. It is established that on the basis of magnesium oxychloride cement and aggregates from dolomite it is possible to obtain heavy concrete in terms of density and strength corresponding to the requirements of the current technical regulations. The need to correct a known method for calculating the composition of heavy concrete, namely the introduction of special correction factors, taking into account the specific features of the materials used, was identified. Based on the calculated formulation, a concrete mixture was obtained and its characteristics were studied.

Investigation of the properties of MgO recovered from reject brine obtained from desalination plants

Abstract In addition to its use in various applications such as those in the agriculture, pharmaceutical and refractory industries, MgO is being investigated as a cement binder due to the low calcination temperatures used during its production and its ability to gain strength by absorbing CO2 in construction products. Similar to the dry-route, the reactivity of MgO synthesized from waste water or reject brine via the calcination of the precipitated Mg(OH)2 depends on the calcination conditions. This study investigated the influence of two bases, namely ammonia solution (NH4OH) and sodium hydroxide (NaOH), on the properties of Mg(OH)2 precipitated and consequently the characteristics of MgO produced under different calcination conditions. The energy consumption of the production of reactive MgO from reject brine via the addition of NH4OH and NaOH was also reported and compared with the industrial production routes to assess the sustainability of the production procedure. The final products were characterized in terms of their specific surface area (SSA) and microstructure. Results indicated that Mg(OH)2 synthesized via the addition of NH4OH into reject brine generated a more porous, flake-like morphology than those obtained via the use of NaOH. The SSA and reactivity of NH4OH-based MgO demonstrated a sharper decrease with increasing temperature and duration compared to NaOH-based MgO. Out of all samples, NH4OH-based MgO calcined at 500 °C for 2 h revealed the highest reactivity (SSA of 78.8 m2/g), which was higher than NaOH-based MgO (SSA of 51.4 m2/g).

A Study on the Phosphate-Bonded High-Alumina Castable — Effect of MgO Addition

Mono-aluminium phosphate [MAP, Al(H2PO4)3] is a widely used chemical binder in the refractory industries due to its higher water solubility and greater bonding strength at low temperatures as it reacts with both basic and amphoteric oxides and has higher application temperature. In the present work, commercial-grade MAP is used in high-alumina castables, with different particle size distributions, as the sole binder. The effect of addition of 1 mass-% MgO as a setting accelerator to the castable compositions is also studied. Castables are processed as per conventional processing methods and heat treated after drying at 1000 and 1600 °C. Dried and fired compositions were evaluated for density and strength. Also micro-structural study of the 1600 °C sintered samples was carried out. Addition of MgO resulted in a marginal decrease in density values which may be due to a greater amount of hydrated phase formation and their decomposition at higher temperatures; but it significantly increased crushing strength for all the heat treatment temperatures. Greater bonding from faster reaction at low temperature and the formation of a liquid phase at higher temperatures are the reasons for such an enhancement.

Removal of Potassium and Iron in Low Grade Bauxite by a Calcination-Acid Leaching Process

In order to explore the commercialized applications of the low-grade bauxite in the refractory industry, a calcination integrated with acid leaching method was adopted to remove the potassium (K) and iron (Fe) from the diaspore-illite (DI) type low-grade bauxite. Following calcining the bauxite at different temperatures, the leaching parameters, including the sulfuric acid concentration, temperature, sulfuric acid to bauxite ratio, and reaction time were systematically studied. The appropriate and economical conditions for removing the impurities were found to be calcining the bauxite at 550 °C, and leaching it with a sulfuric acid solution of 1.2 mol/L, sulfuric acid/bauxite ratio of 9 mL/g at a reaction temperature of 70 °C and reaction time of 2 h, under these conditions, the removal efficiency of K and Fe from the bauxite can reach 30.32% and 47.33%, respectively. The treated bauxite was examined by XRD analysis, SEM observations, and chemical analysis. Kinetics of the removing process were calculated by two models, and the results showed that the leaching process was controlled by the mixed shrinking core model, which was affected by both the diffusion through solid layer and the interface transfer. In summary, the approach in this work presents a promising process for comprehensive utilization of the low-grade bauxite.

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.

CONTRIBUTION TO THE KNOWLEDGE OF THE MAGNESITE DEPOSITS IN BOSNIA AND HERZEGOVINA

Magnesite is an industrial mineral of magnesium, which most often occurs in the form of crystalline, massive and amorphous forms. Mineral magnesite has a wide and varied application in the production of high-strength materials: powder (flour), sinter, bricks (magnesite, magnesite-chromite, forsteric, etc.). In the construction industry it is used for the production of magnesium cement. In smaller quantities it is used in chemical, pharmaceutical, rubber and other industrial branches. The area of the so-called "Bosnian Serpentine Zone" are stand out in the area of the inner Dinarides of Bosnia and Herzegovina, among numerous phenomena and larger deposits of magnesite. In terms of quality, the variability from high quality to those that can not be used in the refractory industry is determined. Magnesite deposits mostly require certain preparation procedures in order to achieve higher quality magnesite. The paper presents deposits and the appearance of magnesite in Bosnia and Herzegovina, with emphasis on the results of previous research, quality, reserves, usability and laboratory testing, and the results of the latest X - ray examinations from one site have been presented.

Composition, radioactivity, and possible applications of kaolin deposits of Sinai, Egypt

This work discusses the composition, radioactivity, and possible utilization of the kaolin resources in Sinai which are hosted in thick sandstone sequences belonging to the Carboniferous (Wadi Khaboba) and Early Cretaceous (Wadi Iseila and Abansakar) ages. The characterization of kaolin was done by microscopic and SEM examination, supported by XRD and ICP-MS analyses. The studied kaolin resources consist of kaolinite, as the main constituent, associated with subsidiary dickite and halloysite, and minor contribution of smectite and illite. The most dominant non-clay mineral is quartz, besides minor gypsum, dolomite, and hematite. Ferrugination dominates, in most cases, at the upper boundaries of the kaolin lenses, suggesting possible supergene activity. The high Al2O3/SiO2 ratio for the Cretaceous kaolin (0.54, in average) specifies its better grade relative to the Carboniferous kaolin (0.43, in average). The kaolin of the middle part of lens C in Wadi Iseila contains Si/Al molecular ratio of about unity, suggesting high-grade kaolin. The Carboniferous kaolin has enriched the radionuclides: U, Th, and Ra (at disequilibrium state due to leaching of eU relative to Ra) and the REE, relative to that of the Cretaceous age. The Carboniferous kaolin is characterized by a higher contribution of HREE (zircon signature), whereas LREE seems to be more influential for the Early Cretaceous kaolin (monazite signature). In spite of the very high CIA index (93 to 99), none of the analyzed kaolin deposits displays Ce abnormality. The high radioactivity of some Carboniferous kaolin can be a serious impediment for its utilization or its exportation. The kaolin of Sinai does not satisfy the international standards for paperwork industries and refractory manufacturing, but beneficiation may overcome this challenge. However, some lenses have high-grade kaolin with a low percentage of oxides of iron, magnesium, calcium, sodium, and potassium and a low radioactivity, hence nominated for the local refractory industry. The high-grade kaolin of Sinai fulfills the standards required for ceramics manufacturing in the global market. Grade 3 kaolin (< 30%, Al2O3) can be used in the manufacturing of white Portland cement and red glaze manufacturing on both local and global markets.