Factors Influencing Mullite Formation in Refractory Grog

The mineral mullite has many outstanding refractory properties. The content of aluminum oxide in the raw material is the basic factor influencing the content of mullite in the final product. Depending on Al2O3 content, silica-alumina materials can be divided into fireclay and high-alumina with the Al2O3 content of 45 % and more. The study describes the influence of raw material, the influence of homogenization of raw material and influence of firing temperature on the mullite formation in fireclay refractory material. Three kinds of refractory clay with different chemical composition were used as raw material for fireclay grog production. Three kinds of homogenization and three different temperatures were studied as factors influencing mullite formation. Powder X-ray diffraction was used to determine mullite content in material. Quantitative phase analysis was conducted by the Rietveld method. Mullite crystals morphology was observed by scanning electron microscopy.

Design, Fabrication and Construction of Cupola Furnace for Metallurgical Industries

A 350 kilogram per hour capacity Cupola Furnace was designed and fabricated from locally available materials for the production of cast iron using pig iron, oily or contaminated steel scraps, foundry returns and fluxes. The main fuel used is metallurgical coke. After analyzing the design parameters, the metallic shells were fabricated in four segments for easy lining: the stack zone, preheating zone, combustion zone and the hearth. Mild steel sheet of 4 mm thickness was procured, marked out as per the design drawing, sliced, rolled into cylindrical shapes and welded together at each seam. The internal configuration was lined first with asbestos paper measuring 4 mm thick using water-glass to enable it adhere to the internal shell of the segments, thereafter, a less dense insulating refractory material was used and finally fireclay refractory bricks were used for lining as they interface directly with the molten metal. The various segments were then assembled and erected with the blower connected to the combustion zone. The research work also contains the materials and components bill.

Improving the Physical and Mechanical Properties of Fireclay Refractory Bricks by Added Bauxite

In this study, the investigation of Local natural Iraqi rocks kaolin with the addition of different proportions of bauxite and its effect on the physical and mechanical properties of the produced refractories was conducted. Kaolin/bauxite mixture was milled and classified into various size fractions, the kaolin (less than 105 μm) and the bauxite (less than 70μm). The specimens were mixed from kaolin and bauxite in ranges B1 (95+5)%, B2 (90+10)%, B3(85+15)%, and B4 (80+20)% respectively. The green specimens were shaped by the semi-dry method using a hydraulic press and a molding pressure of 7 MPa with the addition of (9-12) %wt. of PVA ratio. After molding and drying, the specimens were fired at (1100, 1200 and 1300) °C. Physical properties (density, porosity, water absorption) and mechanical properties (indirect tensile strength and hardness) were measured for all the prepared samples. The results showed that the porosity was increased and the density was decreased, such increase and decrease affected on to the mechanical properties for refractory. The highest values of indirect tensile strength and hardness were obtained at 20% Bauxite at 1300 °C (0.85386 MPa, 1411Kg / mm²) respectively.

REFINEMENT OF REPAIR PROCEDURES OF THERMAL GENERATING SET COFFERING

Different repair procedures for coffering of thermal generating set from fireclay refractory are viewed. To improve repair technologies the authors propose formulations of soluble-glass heat resistant plactic compositions with spread effect raised from metallic aluminum in the form of fine-dispersed particles. Coffering is treated by method of liquid phosphate bond deep impregnation to enhance thermal and chemical resistance of coffering repair surface. Phosphate bonds permit to enhance density and resistance of compositions based on any binding substance.