Furnace For Preparing Magnesium Slag As Raw Material Of Brick, The Performance Of Processes And Materials Research

The research of the comprehensive utilization of magnesium slags todevelop the high added value products is the subject of widespread attention athome and abroad．In this paper,it was studied the technology and related usageproperty of Gehlenite-Forsterite(C₂AS－M₂S) refractory material withmagnesium slags from Shanxi．So in this paper．It was studied the microstructure and phase composition ofC₂AS－M₂S refractory material by XRD, SEM and EDS,and then analyzed theinfluence of the porosity, the shaping method and sintering status on thecompression strength by systematic experiments. Combined with the thermaland mechanical properties of materials, the relations between porosity and theapplied stress and thermal shock resistance were studied. The hydrationresistance property of the materials was studied, and its' hydration process andhydration mechanism were also discussed. The results are as follows：1. Through the reasonable components design, molding and sinteringprocess, C₂AS－M₂S refractory material was produced with magnesium slags asthe main raw material by controlling the microscopic structure. Refractoriness ofthe product was1470℃. The crystallization rate of sintering sample is high, andthe main phases were C₂AS and M₂S. The product was also porous material. Theroughness of sample surface was uneven, but no big significant crack in the rowtimes; it's found that the sample crystallization rate was high, and the C₂ASmassive body grains were surrounded by a lot of little smaller M₂S cone shapegrains at the high magnification. Sample section was porous and concentratedwith a great number of hard matrixes.2. Studied the effect of two type factors of the shaping method andsintering condition such as porous agent content, briquetting pressure andsintering temperature on compression strength by systematic experiments, it wasconfirmed the compressive strength of refractory products under normaltemperature was the parameter of its organizational structure, and porosity was the main factor.(1) with the increase of the amount of PVA, the porosity wasbasically raised, and its compressive strength was declined;(2) the briquettingpressure on the compressive strength has little effect, that's because the sinteringsystem was the absolute role here, and briquetting pressure only has played akey role in the embryo body shaping;(3)if the raw materials and the preparationprocess are certain, sintering temperature restricted the microscopic structure ofthe material directly, and microstructure of materials influenced the compressivestrength directly. As sintering temperature rise, high temperature solid statereaction should be more fully, the more stomata eduction from embryos body,the more low porosity, sample volume density was gradually increasing,macroscopic showing such as mechanical properties were strengthened;(4) inthe same molding and sintering process, the compressive strength of porousrefractory materials was increased gradually with the decline of porosity. In theexperiment results, the compressive strength of refractory products mostlyconcentrated on180²00MPa, the compressive strength of materials was veryhigh.3. Combined with the thermal and mechanical properties of materials, therelations between porosity and applied stress and thermal shock resistance werestudied.(1) in the same molding and sintering process, with the increase of theporosity, cyclic number of thermal shock experiments under600℃wasincreased gradually, and the thermal shock resistance were more better. Theexpansion ways of crack in the solid phase were both intergranular fracture andtransgranular fracture, and the basic expanding direction has not changed. Crackexpansion in the gas phase met block, not only the direction happened to deflectand disperse, and the strength decreased as the stomata exists energy dissipationmechanism;(2) in the same process and the porosity, extra artificial defectsdeclined the cyclic number of the thermal shock experiments under600℃obviously, and the thermal shock resistance was getting worse.4. After high temperature solid state reaction, the high hydration activitychemical composition CaO and MgO in the raw materials have composed toC₂AS and M₂S through the reasonable formula and forming, sintering process. The sample hydrated for72h have no obvious cracks or deformation. Thisindicates that the sample has an excellent hydration resistance. Before beinghydrated, the main phases are C₂AS and M₂S; after being hydrated for72h, themain phases is not changed, while the diffraction peaks are slightly shift to left.With the increase of the hydration time, surface morphology change greatly.During the course of hydration, firstly, the surface attachments are sheded fromthe surface, the matrix is exposed; secondly, the stick big grains are generated;thirdly, the mesh grains are formed; finally, hydration products fell off ordissolved, and a new course starts. The morphology is different between surfaceand section. Section morphology almost is closed holes and hard matrix. Thestick big grains are not appeared. The samples are porous; most of the holes areclosed. The hydration reaction is not exit in the internal part.