1 Introduction. 2 Sintered aggregates ALMATIS PREMIUM ALUMINA-BASED RAW MATERIALS. Marion Schnabel, Gunter Büchel; Almatis GmbH, Frankfurt, Germany

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1 ALMATIS PREMIUM ALUMINABASED RAW MATERIALS Marion Schnabel, Gunter Büchel; Almatis GmbH, Frankfurt, Germany ALMATIS offers a wide range of aluminabased products for use in refractory and ceramic products. The paper presents the different raw materials and discusses briefly their major properties with regard to the final application. 1 Introduction Alumina (Aluminum oxide) is most widely known and used as the starting material for the production of aluminum. However, there is a wide range of specialty aluminas for nonmetallic applications. Alumina is highly heat resistance (fusion point 2050 C (3725 F)) and is an excellent thermal and el ectrical insulator. In its crystalline form, called corundum, its hardness makes it suitable for use as an abrasive and as a component in cutting tools. Aluminum oxide adds great mechanical strength, has excellent resistance to corrosion and wear, and is a nontoxic material. Almatis is committed to globally provide high quality specialty alumina products and leading edge services. Almatis is the only global and the world's leading producer of aluminabased materials for refractory, ceramics and polishing applications. Almatis concentrates fully on its role as producer and secure supplier of premium alumina. With its high quality alumina materials including tabular alumina, sintered magnesia aluminate spinels, calcium aluminate cements and binders, calcined, reactive alumina and dispersing aluminas as well as dense and lightweight aggregates based on calciumhexaluminate the company offers the broadest product portfolio in the market and a onestopshop for its customers. 2 Sintered aggregates Tabular Alumina T60/T64 Almatis tabular alumina T60/T64 is a pure and fully densified sintered alumina material that is characterized by its large, well developed hexagonal tablet shaped alumina crystals of up to 200 µm length with closed spherical pores. The production of tabular alumina follows the same process steps than practiced in the advanced ceramics industry. In the first step, finecrystalline alumina is ground. In order to get aggregate and powder sizes as needed by the refractory producers the ground alumina is in a second step granulated. The following continuous rapidsintering of the green balls takes place without the use of sintering aids at temperatures in excess of 1800 C in a vertical shaft kiln. The final step aft er cooling is crushing and screening of the material to aggregate sizes. Tabular alumina is a highpurity refractory raw material with an alumina content higher than 99.5 % and a bulk specific gravity >3.50 g/cm³. Its high melting point of about C ensures a high hot modulus of rupture and good volume stability at high temperatures. In addition, virtually no plastic deformation occurs at high temperatures. The excellent thermal shock resistance of tabular alumina can be attributed to its specific microstructure: low open porosity and large crystals with closed spherical pores, which are entrapped upon recrystallization during rapid sintering. (Fig. 1) In comparison with fused alumina, which is more or less free of micro pores, the percentage of undamaged grains of tabular alumina after 20 thermal shock cycles is four to five times higher. Tabular alumina has high mechanical strength and abrasion resistance, very good chemical purity, excellent dielectric properties and good resistance against acid and alkali corrosion. Fig. 1: Scanning electron microscope (SEM) image of Tabular alumina This combination of properties makes tabular alumina the aggregate of choice in unshaped and shaped high performance refractories. It is used in a variety of industries such as steel, foundry and cement, petrochemical, ceramic and waste incineration. Other common applications include its use in electrical insulators, kiln furniture and as a catalyst support. Ground tabular is an excellent product to be used as filler in epoxy or resin systems where high dielectric strength, thermal conductivity or abrasion resistance is desired. Sintered spinels AR 78 / AR 90 / MR 66 Spinels are a group of compounds of the same crystal type consisting of two metal oxides, in which one of the metal ions has two and the other three valences. Magnesium aluminate spinel (MgO Al 2O 3) is commercially the most important spinel. A strong feature of all spinels is the tendency to substitutional solidsolutioning, where large percentages of one or both of the spinel components may be substituted by others of the group. Sintered magnesium aluminate spinel is manufactured from high purity raw materials by essentially the same process as Tabular alumina. Magnesium aluminate spinel has excellent refractory properties with a fusion point of the stoichiometric spinel (28.3 % MgO and 71.7 % Al 2O 3) of C. MRS / 24.Aug

2 According to the phase diagram the ratio between Al 2O 3 and MgO of the spinel can be shifted around the stoichiometric composition with an Al 2O 3 content varying between 65 % (magnesiarich spinel) and 90 % (aluminarich spinel). (Fig. 2) MR 66 AR 78 AR 90 heating and firing which inhibit crack propagation caused by thermally or mechanically induced tensile stress. Spinel linings resist the attack of reducing atmosphere that contains free sulphur dioxide or trioxide. They also exhibit high resistance to alkaline compounds in slags. Magnesiarich spinel MR 66 contains free magnesium oxide and is prone to hydration, which is accompanied by volume expansion. Because of potential crack for mation as a result of hydration, this spinel is therefore not recommended for castables, especially for large structural parts. Tab. 1: Typical properties of ALMATIS Spinels Fig.2: ALMATIS Spinels in the phase diagram Al 2O 3 MgO Aluminarich spinels AR 78 and AR 90, distinguished by their chemistries (78% and 90% alumina respectively), are for use with alumina bodies and magnesiarich spinel MR 66 is used particularly in basic (magnesiabased) refractory products. Sintered Spinel MR 66 Chemical Composition (typical values) Al 2 O 3 [%] > 63,0 MgO [%] 33,0 CaO [%] 0,39 SiO 2 [%] 0,09 Na 2 O [%] 0,03 Fe 2 O 3 [%] 0,20 Physical properties Bulk Specific Gravity [g/cm³] 3,3 Apparent Porosity [Vol.%] 1,8 Phase composition (Xray diffraction peaks) Spinel Corundum (Al 2 O 3 ) Periclase (MgO) + AR 78 > 74,0 22,5 0,24 0,10 0,09 0,15 3,3 1,8 AR 90 > 87,0 9,5 0,15 0,06 0,15 0,06 3,4 2,0 (+) AluminaRich Spinels AR 78 and AR 90 Additionally to the tendency for substitutional solidsolutioning, which is inherent for all spinels, the aluminarich spinels have due to their processing conditions free vacancies in the crystal structure, with the capability to absorb FeO and consequently retard the infiltration of slag. Superstochiometric spinel, containing 90 % alumina, precipitates alpha alumina at working temperatures which reacts with calcium oxide in the slag forming the refractory 6 phase at the edge of the spinel grains. This 6 layer protects the spinel grains against further corrosion. Almatis Spinels AR 78 and AR 90 are used above all for unshaped refractories in the iron and steel industry. It is generally agreed that the spinel content of such castables should be in the order of 1530 %. Laboratory investigations and market experiences show that spinel addition to aluminous refractory bricks, monolithics and prefired shapes considerably improve their resistance to slag attack and their thermal shock resistance. MagnesiaRich Spinel MR 66 For environmental reasons, the use of chromiumcontaining raw materials is continuously decreasing in the cement and lime industry as well as in the steel industry. Almatis Spinel MR 66 is used as a replacement for chrome ore in basic bricks for cement and lime kiln linings. MR 66 imparts the improved thermal shock resistance normally associated with chrome additions, but without the potential problem of hazardous waste disposal. Because MR 66 spinel has a lower thermal expansion coefficient than periclase (approximately half that of magnesia), micropores and microcracks form around the spinel grains contained in basic linings during Bonite and Super Light Weight Aggregate SLA92 Bonite and SLA92 are synthetic refractory aggregates based on calcium hexaluminate, 6. (Table 2) Calcium hexaluminate is described in the literature as a refractory material that exhibits: very high refractoriness (onset of melting C) low solubility in iron containing slag high stability in reducing atmospheres, e.g. CO high chemical resistance in alkaline environment low wettability by molten metals and slag (ferrous and nonferrous) thermal expansion coefficient similar to corundum Both aggregates are prereacted by high temperature sintering and thus show no volume increase due to the formation of new phases during heatup. SLA92 Increased process temperatures and the need for energy savings due to new environmental laws require efficient high temperature refractory insulation material. The recent classification of refractory ceramic fibres under REACH as substances of very high concern (SVHC) has further stimulated the search for alternative solutions with similar properties, but less concerns about potential health hazards. The microporous, silicafree calcium hexaluminate based insulating material SLA92 is an alternative to refractory ceramic fibres and other insulating refractory materials. Key properties can be listed as: high chemical purity long term high temperature stability up to C low thermal conductivity up to C high thermal shock resistance MRS / 24.Aug

3 Tab.2: Typical data of SLA92 and Bonite Calciumhexaluminate Chemical Composition (typical values) Al 2 O 3 [%] CaO [%] Na 2 O [%] SiO 2 [%] Fe 2 O 3 [%] Physical properties Bulk Specific Gravity [g/cm³] Apparent Porosity [Vol.%] Phase composition (Xray diffraction peaks) Calciumhexalumiate ( 6 ) Corundum (Al 2 O 3 ) 2 SLA ,5 0,40 0,07 0,04 0, (+) Bonite 91 7,6 0,9 0,09 3,0 9,8 Due to a special production process SLA92 has a high micro porosity that hampers the heat transfer by radiation at temperatures >1200 C. This pore structure remains stab le which makes SLA92 at high temperatures performing better than ceramic fibre. (Fig. 3) Thermal conductivity [W/m K] mm SLA92, 0.61 g/cm³ 36 mm SLA92, 0.47 g/cm³ 36 mm insul. fireclay grain, 0.5 g/cm³ 36 mm bubble alumina, 0.58 g/cm³ ceramic fibre blanket 80% Al2O3; 0.13 g/cm³ ceramic fibre blanket Temperature [ C] Fig. 3: Thermal conductivity of insulating materials + bubble alumina insul. fireclay grain SLA92 As a refractory aggregate, SLA92 allows the formulation of monolithic concepts for precast shape manufacturing and onsite installations. The comprehensive application experiences with the microporous calcium hexaluminate clearly demonstrates that this insulating aggregate provides both a technical and an economical alternative to conventional refractory ceramic fibers and other insulating materials. Super light weight aggregate SLA92 is used in various industries including steel making, glass, ceramics and petrochemical. Even under severe conditions, as for example exposure to harsh thermal shock conditions or alkali attack, service life has exceeded initial expectations. Bonite Bonite is a dense aggregate, composed of about 90% 6 with only a minor content of corundum, and traces of 2. It has a bulk density of 3.0 g/cm³, which is about 90% of the theoretical density of calcium hexaluminate. Bonite combines the above described characteristics of 6, resulting in advantages e.g. in the aluminium industry (low wettability by molten aluminium), the cement industry (high chemical resistance in alkaline environment), the steel industry (high refractoriness and low solubility in iron containing slag) and in the petrochemical industry (stability in reducing atmospheres). 3 Binder Calcium aluminate cement Calcium aluminate cement is used in highalumina monolithic refractories to form with water a hydraulic bond that contributes to the socalled "cold" strength of the refractory concrete. Highpurity limestone and finecrystalline alumina are the principal raw materials needed for the production of calcium aluminate cements. The raw material mixture is ground and sintered to produce cement clinker. In the course of the sintering process, calcium oxide and aluminium oxide form calcium aluminate phases, which become richer in alumina as the temperature increases. Highpurity calcium aluminate cements consist of a minimum of >70% AI 2O 3. Depending on the type of cement, the curing and setting (hardening and strengthening) behavior varies significantly. In general bonding in a refractory concrete develops in three main phases. (Fig. 4) In the first phase of bond development, metastable H 10 as well as AH 3gel are formed. At curing temperatures of 20 to 35 C, conversion to metastable C 2AH 8/AH 3 gel takes place. This compound further converts to stable gibbsite (AH 3) and C 3AH 6, which holds the lowest reacted water. If curing is carried out at low temperatures (<20 C), the metastabl e H 10/AH 3 gel forms and hardens and eventually converts to stable C 3AH 6/AH 3 at temperatures above 35 C. This conversion is accompanied by a volume reduction of 53%, which causes a lower strength of the concrete. In order to avoid the formation of the metastable H 10/AH 3 gel, it is important to cure the concrete at sufficiently high temperatures. Tabular unhydrated cement 2 C 12 A 7 H Temperature C 0 H 10 C 3 AH 6 C 3 AH x (x=812) 2 6 C 2 AH 8 AH 3 gel AH AH 3 3 C C 12 A Fig. 4: Phase development during hydration Almatis produces high purity calcium aluminate cements with 70 and 80% Al 2O 3 content. The 70% alumina cements are represented by two product types, 14 and 270. In the refractory industry they find their use especially in low and ultralow cement, low moisture castables with gunning, vibration or selfflowing placement. 14 is a well established product line with three distinct setting time ranges. 270 is a product characterized by very low water demand, excellent flowability, and high strength development. Almatis 70 % alumina cements do not contain any organic additives in order to give full flexibility in product design without any potential chemical mismatches. C A A A MRS / 24.Aug

4 The 80 % alumina cements are represented by 25 R (Regular Grade), 25 M (Medium Grade) and 25 C (Casting Grade). They are used in the refractory industry in conventional and low cement castables, which require fast setting, high early strength development, and good strength at intermediate temperatures. The latest development, the new temperature independent cement 470 TI shows clear advantages when compared to standard 70 % Al 2O 3 cements. 470 TI improves the setting behavior of castables at low temperature whether or not they contain silica fume. Castables with 470 TI exhibit a much more robust setting and avoid the setting time variability and uncertainty which are especially apparent during winter time. The flow of silica fume containing mixes is improved by when using 470 TI instead of normal 14 M. Tests with different silica fume grades and Andalusite as aggregate have confirmed the robustness of 470 TI exhibiting reliable setting behavior even at low ambient temperature. Alphabond Almatis hydratable alumina binder, Alphabond, is an engineered binder for use in nocement refractory castable formulations. Alphabond has been developed for applications where the chemistry of the refractory matrix is critical to product performance. Alphabond 300 contains <0.1% CaO which reduces the formation of low melting point silicates in the matrix. Such silicates can have a significant deleterious impact on high temperature properties, notably strength (particularly creep) and resistance to slag attack. Although Alphabond behaves similarly to high purity calcium aluminate cement based castables with respect to working time, setting times, water demand and flow properties, it has some unique characteristics that need special attention when working with Alphabond. Dispersing aluminas The matrix of refractory castables often contains ultra fine particles like reactive aluminas and hydraulic calcium aluminate cement. To achieve a full dispersion of these components at reduced water demand the use of dispersing agents is required. Almatis Dispersing aluminas are very efficient additives to optimize flow properties and adjust the setting times of castables according to specific placement requirements and climatic conditions. The ratio of the retarding S type dispersing alumina to the accelerating W type is varied to achieve set control. The total of the two types is typically 0.7% to 1.2% total dispersing alumina, which guarantees a certain robustness of dosing for the production of refractory castables. There are two different product lines of Dispersing Aluminas available for individual castable concepts: ADS 1 / ADS 3 / ADW 1 for high performance silicafree castables with alumina fines and MADS 1 / M ADS 3 / MADW 1 for fumed silicacontaining castables using alumina fines 4 Calcined and reactive aluminas The conversion of alumina to specialty alumina passes various transition phases. By varying the calcination temperature and heat treatment time, specialty aluminas with a wide range of physical properties, depending on the product's application, can be produced. As a general rule, the higher the calcination temperature and the longer the holding time for calcination in the rotary kiln, the larger the crystal size of the alumina. The crystal growth can also be enhanced by the addition of mineralisers. At a given temperature, these additives increase the crystal growth rate. The SEM (scanning electron micrograph) pictures show the completely different microstructures of material calcined at temperatures <1.200 C. (Fig. 5, left) and in contra st of material which was calcined at temperatures above C. (Fig. 5, middle). The influence of mineralisers on the crystal growth can be seen in Fig. 5, right. The different crystal sizes have as well an influence on the surface area, another important physical property of calcined and reactive aluminas. Fig. 5: Scanning electron microscope pictures (SEM) of calcined aluminas (left: low temp. middle: high temp. right: with mineralizers) Calcined aluminas Calcined aluminas consist primarily of sintered agglomerates of individual alumina crystals. The size of these primary crystals depends on the degree of calcination. Most aluminas which are calcined at higher temperatures have a primary crystal diameter of 3 µm or above. With the addition of mineralisers and calcination temperatures above C their primary crystals could grow up to >20µm and the surface area (BET) may reach values of less than 1 m²/g. Calcined aluminas are ground in a continuous ball mill connected to an air classifier and the majority is supplied to end users in ground (<63 µm) and fineground (<45 µm) forms. The agglomerates are not fully destroyed (Fig. 6 left) during the grinding which makes a significant difference to the reactive aluminas. (Fig. 6 right) Reactive aluminas The fully ground reactive Aluminas are produced by batch grinding mostly in ball mills. In such grinding, the agglomerates are almost completely ground down to primary (single) crystals. The average particle size d 50 of these reactive aluminas, therefore, is nearly equal to the diameter of the single crystals. Their particle size ranges from 0.3 to 1.5 µm and the surface area (BET) is in the order of 2 to 10 m 2 /g. MRS / 24.Aug

5 As a pressed body, reactive aluminas have the ability to reach their final density at temperatures as low as C, their final density being close to the theoretical value of 3.98 g/cm³. For a given green density, these aluminas exhibit the highest degree of densification on firing and, therefore, the highest shrinkage. Applications in the refractory industry Refractory products are generally composed of a mixture of coarse aggregates (above 0.1 mm) and a matrix of fine particle sizes (smaller than 0.1 mm). In order to get the highest packing density, so as to achieve low porosity and high mechanical strength, it is necessary to create a matrix with improved particle packing. Calcined aluminas in ground and fineground forms and super ground reactive aluminas in particular are used in the fine fraction of the matrix having multiple functions. Ground and fineground calcined aluminas are used as a filler to upgrade the product performance of formulations based on natural raw materials. By increasing the overall alumina content particles of the mixes and improving their particle packing through the addition of fine alumina the refractoriness and the mechanical properties like hot modulus of rupture and abrasion resistance are improved. The fully ground reactive aluminas are specially designed for the production of high performance refractories where defined particle packing, rheology and consistent placement characteristics are as important as superior physical properties of the final product. Their excellent sintering reactivity and highly controlled particle size distribution down to the submicron range provide unique properties to refractory formulations. In monolithic refractories they help to optimize the particle packing and thus achieving the desired physical properties and placement rheology. They are also increasing the high temperature mechanical performance when used as substitute for other superfine materials of lower refractoriness. Reactive aluminas with their excellent sintering reactivity form a strong ceramic bond of high refractoriness and good thermal shock resistance by reacting with binder components like calcium aluminate cement and / or clays. The most recent multimodal reactive aluminas have a broad particle size that has been optimized over a wide range to minimize the number of matrix components needed. Their use minimizes the formulation design time and effort necessary to achieve extremely good physical and rheological properties. Modern bimodal or multimodal reactive aluminas like CTC 30, CTC 50, and CTC 55 (contains spinel) give excellent flow and physical and chemical properties. Often, high alumina containing castables show a dilatant rheological behavior. To overcome this characteristic and to achieve a soft working consistency the bimodal reactive aluminas, ESY 1000 and ESY 2000 (contains spinel) can be used. Almatis contimilled calcined alumina CT9FG, A2325 (1000x) Almatis batchmilled reactive alumina RG µm Fig. 6: Scanning electron microscope (SEM) pictures of calcined (left) and reactive alumina (right) Calcined and reactive aluminas for manufacturing of refractories occupy about 50 % of the specialty alumina used in the market. Another 25 % of the alumina is used for the production of advanced ceramics and 20 % for abrasives and polishing powders. The remaining 5 % is used for other products such as insulating fibres and glazes. Applications in the ceramic industry Calcined and reactive aluminas are the most important raw materials for the production of industrial and advanced hightech ceramics. Reasons are the superior mechanical, thermal, electrical and chemical properties as well as the outstanding price / performance relationship of aluminium oxide. The main criteria for the selection of special aluminas are chemical purity predominantly the level of soda and the primary crystal size. Tab. 3: Ceramic applications of aluminas Field of Application Advanced and Wear Resistant Ceramics parts with > 99% Al 2 O 3 parts with 85 99% Al 2 O 3 Electrical Insulators 90 98% Al 2 O 3 Spark Plugs High Tension Insulators Electronic Components / Substrates 99.5% Al 2 O 3 Ceramics 70 99% Al 2 O 3 Ceramics Porous Ceramic & Catalyst Carriers High Alumina Ceramics Aluminosilicate Ceramics Ceramic Properties Uniform, dense ceramic matrix Defined surface properties Excellent wear and abrasion resistance High dielectric strength High mechanical strength High thermal conductivity High electrical resistance Uniform dense ceramic matrix High mechanical strength Defined pore structure Good mechanical and impact strength Alumina Grades and Key Properties 3000 SG, CT 1200 SG CT 800, WRA, CL 2500 Fine controlled particle size Distribution High thermal reactivity Good grindability High chemical purity % Al 2 O 3 CL 3000, CL 5000, CT 700 H VA FG, CT 19 FG Consistent shrinkage Very low Na 2 O Good machining properties Alphaalumina CT 3000 SG, CT 1200 SG CL 2500, CL 3000, CL 5000 Very low Na 2 O <0.06% Consistent shrinkage High thermal reactivity CL 3000 FG H VA FG, CT 19 FG Defined particle size distribution Good ceramic reactivity Consistent shrinkage Corundum with a scratch hardness of 9 (Mohs scale) is one of the hardest known materials. This extreme hardness and wear resistance is advantageously utilized for wearresistant ceramics such as baffle plates, armor plates, grinding media, ceramic mill linings and hardsurfacing of equipment in the pulp and paper industry. For these products, containing 85 to 98% aluminium oxide, mediumcrystalline aluminas are applied in combination with fluxes. Advanced hightech ceramics consisting of more than 98% aluminium oxide owe their extreme mechanical strength as well as their excellent corrosion resistance to the existence of the finecrystalline, highpurity reactive aluminas with a soda content of maximum 0.10%. Typical examples for the numerous applications are bearings, MRS / 24.Aug

6 pistons and gasket elements for the construction of pumps. Highpurity alumina is used in the textile industry for thread guides, spinning rings and friction disks, whereas in sanitary armatures, the faucet valve disks are also made of the same material. Ceramic highvoltage insulators owe their outstanding electrical insulation and mechanical properties to alumina as an ideal raw material for hightension porcelains. Optimal insulation values and highest mechanical strength properties are obtainable by the addition of 20 to 40% lowsoda, mediumcrystalline HVA (HighVoltage Alumina). Spark plug insulators are almost exclusively made of medium or coarsecrystalline lowsoda aluminas with the aid of fluxes. The alumina content of spark plug insulators varies between 88 and 96%. Alumina substrates for electronic parts are made of high purity aluminas with the ability to provide excellent dielectric properties and a very good thermal shock resistance during the production process of the structural elements (800 C and higher). The elements made of alumina al so feature very good thermal conductivity. In catalysts and automotive construction parts, the ability of alumina to form new minerals together with other oxides at temperatures above C is frequently utilized. Examples for these new compounds in ceramics are spinel (MgO AI 2O 3), cordierite (2MgO 2AI 2O 3 5SiO 2), as well as the formation of mullite (3AI 2O 3 2SiO 2) in silica ceramics. By adding calcined aluminas, the quality of glazes and frits e.g. for ceramic tiles and sanitary ceramics is always significantly improved with respect to the scratch hardness and abrasion resistance as well as to the chemical resistance. Applications in the polishing industry The different calcination processes influence the size of the primary crystals and as consequence the hardness, particle size distribution and the oil absorption of the calcined aluminas. Calcined alumina grades with larger crystals can be used for grinding and lapping while some with small primary crystals simply equalize and smooth the surface being treated, without removing significant amounts of material. To obtain the optimum results the selection of polishing aluminas also depends on their particle size distribution. The main application fields for polishing aluminas are rough and fine polishing of steel, particularly of stainless steel but also of nonferrous metals, plastics, marble and granite. Another large application field for polishing aluminas is in household cleansers in addition to the classical abrasives (based on e.g. fineground marble). The aluminabased cleansers offer the advantage that the recipes can be acidic. From a health viewpoint, aluminium oxide is a completely harmless material; it is therefore frequently used for the formulation of socalled bioproducts. Almatis polishing aluminas are used alone or as an ingredient of a polishing compound. As synthetic products, their physical properties and chemical composition are constant, regardless of the pressure or temperature experienced during use which makes them superior to the classical natural materials such as pumice, lime stone and emery. The cutting effect is indicated on a scale of 1 to 10; where 1 represents a low cut and 10 represents a very high degree of abrasion. The polishing effect is classified in the same way, with the scale number 1 indicating a highly reflective surface finish and scale number 10 indicating a lustrous finish achieved by fine, soft aluminas. Tab.4: Typical Almatis polishing aluminas 5 Outlook In the future, synthetic raw materials based on alumina will continue to play an important role as a raw material for multiple applications. With their outstanding physical and chemical properties and favourable price / performance relationship, aluminiabased raw materials will help to increase the service life of equipment e.g. highalumina slide gates, nozzles and stoppers for continuous steel casting or wearresistant ceramic parts of pumps and pipe lining. Spinels will increasingly replace chromium oxide in refractories so as to eliminate potential environmental hazards. Increased use of catalysts and ceramic carriers of catalysts will further protect the environment to a higher degree. Energy savings will be increased by using insulating materials in the form of lightweight aggregates. With easier and safer handling, the nonfibrous, super lightweight aggregate SLA92 with bulk specific density of around 0.5 g/cm 3 will have an increasing potential in steel reheat furnaces or other thermal industrial applications. Premium, aluminabased raw materials will certainly continue to play an important role in the future as the raw materials for high performance ceramics and refractories and innovative technical systems. This not only applies to a full range of diverse calcined aluminas including those with ultra low impurity levels like CT 3000 LS SG or the spray dried aluminas. It also applies to sintered and sized materials. Material combinations and compounds containing a medium to high percentage of aluminium oxide will be offered in a broader variety. MRS / 24.Aug