Fluidized calcining technology of high-activity metakaolin

Abstract

The invention provides a fluidized calcining technology of high-activity metakaolin. The problems of unstable product quality, high energy consumption, huge investment and high production cost exist in the existing calcining technology. The calcining technology provided in the invention comprises a device system consisting of a counterflow fluidized calcining furnace, a raw-material preheat and afterheat utilization system, a wrought material cooling system and an air heating furnace system. Powered material of kaolin is fed in the furnace from the peak of the calcining furnace through a spreading machine after being preheated; and hot smoke gas produced by the air heating furnace enters the bottom of the calcining furnace and upwardly flows at a speed of 1-2.5m / s so that crystal water is quickly dewatered at a temperature of 560 DEG C to 750 DEG C when the materials and the host smoke gas are in the state of counterflow, thereby forming the high-activity metakaolin. The absorption value of Ca(OH)2 of finished products in the invention can reach 1000mg / g or more and the screen analysis D50 can reach about 2 microns; and the technology has the beneficial effects of stable quality, energy saving, low production cost and less investment.

Description

technical field [0001] The invention relates to a method for calcining materials, in particular to a calcining process for silicate materials. Background technique [0002] Metakaolin is an amorphous anhydrous aluminum silicate formed after kaolin is dehydrated at an appropriate temperature. When kaolin is heat-treated between 600-850°C, the OH existing in the interlayer of silicon-oxygen tetrahedron and aluminum-oxygen octahedral structure in kaolin - The group is removed, this kind only removes OH - Although the base kaolin can still maintain the original layered structure, large dislocations have occurred in the arrangement of its atoms, forming a substance characterized by an amorphous transition phase, which is called metakaolin. This metakaolin is in a thermodynamically metastable state and therefore has a high reactivity. In recent years, international research on the properties and applications of metakaolin has become increasingly active. In view of its low calci...

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Problems solved by technology

The raw material calcination device described in ZL03154421.5 "Rapid Circulation Fluidized Calcination Method and Equipment for Ultrafine Kaolin" uses a circulating fluidized bed calcination furnace. When the materials are discharged while circulating, the old and new materials are mixed in the Together, it is difficult to evenly control the residence time of the material in the furnace. Therefore, for the metakaolin that requires the product to have high activity, the quality is difficult to reach and stabilize; The fluidized bed calciner has been improved, and two sets of facilities, the flame-chambered fluidized calciner and the flame-chambered moving bed calciner, are used. The process is too complicated and the investment is large.

ZL200610153358.3 "The fluidized instantaneous calcination process of coal series kaolin" adopts pipeline fluidized calcination technology, the flue gas temperature is 850-1000 ℃, the flow rate is 15-40m / s, the temperature is too high and the speed is too fast It is difficult to meet the calcination requirements of highly active metakaolin. In addition, the heat recovery of tail gas in this process is not perfect. Only the first-stage cyclone preheater is used, and the heat loss will be relatively large.

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