Testing a new composition of periclase spinel objects

Abstract

În the basis of periclase powder (70%) and aluminomagnesia spinel (30%), synthesized from secondary aluminum production waste and caustic magnesite, test objects are produced of periclase spinel composition satisfying the requirements of GOST 1579-006-00190495-98. The articles are successfully tested in the working layer for lining tunnel furnace cars of OAO Kombinat Magnezit.With the aim of utilizing dust waste materials from secondary aluminum production (WSAP) for producing periclase spinel refractories technology has been developed for preparing aluminomagnesia briquettes containing sintered aluminomagnesia spinel [1 -3]. Periclase spinel objects based on sintered aluminomagnesia briquettes have been manufactured using sintered periclase fractions 3 -0.5, 1 -0, and < 0.063 mm (finely ground). The chemical composition of the periclase powders is presented in Table 1.Aluminomagnesia spinel was prepared by sintering from WSAP dust and caustic magnesite, taken in the ratio 1:1 and formed into briquettes with raw material having an apparent density r app of the of 2.15 g/cm 3 , and an ultimate strength in compression s co of 24.4 MPa. Briquettes were fired at 1750°C. The characteristics of fired briquettes are, wt. %: SiO 2 5.20, Al 2 O 3 34.2, MgO 52.5, Fe 2 O 3 2.36, CaO 3.60, Na 2 O 0.79, K 2 O 0.21, Dm prc 0.25; r app = 2.74 g/cm 3 , s co = 48.2 MPa. It was established by petrographic studies that the texture of the briquettes obtained is porous. The pore size is 4 mm. The mineral composition of sintered aluminomagnesia briquettes is, vol.%: spinel 60 -62, periclase 33 -35, silicates (forsterite, monticellite) 4 -6, the rest (sodium-potassium silicate, pyroxene, melinite, sodium glass) 1. the predominant grain size of spinels is 22 -25 mm, and the maximum is 50 mm.In developing technology for preparing periclase spinel objects based on synthesized spinel it was directed towards the properties of periclase spinel produced by OAO Kombinat Magnezit [4]. The charge consisted of 15 -20% periclase powder fraction 3 -0.5 mm, 20 -25% periclase powder fraction 1 -0 mm, 25 -30% aluminomagnesia spinel powder fraction 0.5 -0 mm, 25 -30% finely ground sintered periclase fraction < 0.064 mm. Objects of the composition 30% spinel and 70% sintered periclase were compacted at a pressure of 150 MPa in a hydraulic press and fired at 1680°C in a tunnel furnace by the firing regime for periclase-chromite refractories. The chemical composition of the test periclase spinel objects was, wt.%: MgO 86.5, Al 2 O 3 6.83, SiO 2 2.52, CaO 2.15, Fe 2 O 3 1.86, Dm prc 0.32. The properties of the test periclase spinel objects were: open porosity 14.6%, apparent density 3.01 g/cm 3 , ultimate strength in compression 77.6 MPa, temperature for the start of deformation under a load of 0.2 MPa 1580 -1590°C, heat resistance (1300°C -water) 6 -7 thermal cycles, volumetric shrinkage 0.7%. it follows from the data provided that the test periclase spinel objects in physicomechanical properties relate to the specifications for this class of objects.It ...