Method for preparing high-activity light calcined magnesia with fixed bed-fluidized bed at multiple flow states

Abstract

The invention relates to a method for preparing high-activity light calcined magnesia with a fixed bed-fluidized bed at multiple flow states. The method comprises the following steps: taking magnesitewith the granularity being 30-300mm as a raw material, feeding the magnesite into a fixed bed calcining decomposition furnace through a feeding system, and decomposing blocky magnesite into a relatively small block material and a powder material, wherein 10-80% of the magnesite is subjected to a decomposition reaction, and the decomposition reaction is a piled state decomposition; feeding material granules discharged from the fixed bed calcining decomposition furnace into a fluidized bed boiling state decomposition furnace through a pipeline, and keeping the material granules at a boiling state to continuously decompose undecomposed magnesite in the braising process in the fluidized bed boiling state decomposition furnace, wherein the decomposition reaction is a boiling state decomposition; feeding the hot flue gas with the completely decomposed light calcined magnesia into a cooling device, cooling, and collecting from a discharge hole. The material is at multiple flow states in thewhole process, the multiple flow states are beneficial to sufficient decomposition reactions of the magnesite, the magnesite decomposition rate can be greater than 99%, and the uniform and stable product quality can be ensured.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a method for preparing high-activity light-burned magnesia in a fixed bed-fluidized bed multi-fluid state. Background technique [0002] Magnesite is one of my country's advantageous mineral resources, with a total reserve of more than 3 billion tons, accounting for a quarter of the world's magnesite reserves and ranking first in the world. Light-burned magnesia produced by calcination of magnesite is the most productive magnesia material. The annual production capacity of light-burned magnesia in my country is over 10 million tons. Light-burned magnesia has excellent alkali resistance and electrical insulation, strong adsorption capacity, high thermal conductivity, and large thermal expansion coefficient. It is widely used in metallurgy, building materials, and national defense. It is also an important industrial raw material. Its downstream products include: High-grade refr...

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Problems solved by technology

The reverberatory kiln can only use high-quality lump ore resources, and a large amount of powder resources are wasted; the energy consumption per ton of products is equivalent to more than 240 kg of standard coal, which is too large; a large amount of dust is emitted during the production process, and the concentration exceeds 200 mg / standard cubic meter. It has serious adverse effects on the environment and ecology; manual operation is used in production, which is labor-intensive and low in automation; the preparation of light-burned magnesia by this method is distributed in a piled state, and a large number of undecomposed raw meal blocks are accompanied by the generated light-burned magnesia. Discharge together, resulting in incomplete decomposition of magnesite, resulting in uneven quality of light-burned magnesia, unstable properties, poor activity, and low added value, which greatly limits the production and application of light-burned magnesia

[0004] The suspension method calcination technology that has appeared in recent years to prepare light-burned magnesia has the characteristics of large transfer area, large comprehensive transfer coefficient, large transfer power, fast calcination speed and high thermal efficiency. The gaseous suspension preheating and pre-decomposition device transplanted is not suitable for the decomposition and calcination of magnesite. Because the residence time of magnesite in the suspension kiln is very short, the heat transfer and reaction time are insufficient, and the material decomposition is not complete. Some magnesite The ore particles are not really decomposed, and the quality of the prepared light-burned magnesia is uneven and stable, so the effect of calcining magnesite by suspension method is not ideal in practical application

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