A method for preparing light-burned magnesia by a magnesite cracking method

Abstract

A method for preparing light-burned magnesia by cracking magnesite, relates to a method for preparing light-burned magnesia. In the first step of the method, magnesite powder (200 mesh) is preheated by a rotary preheater, and then processed The silo and material legs evenly enter the fluidized bed; the second step is that the magnesite powder is suspended in the high temperature (900°C-1200°C) carbon dioxide gas flow (residence time 5s-9s) and cracked to generate magnesium oxide powder and carbon dioxide gas; the second step The magnesium oxide powder and carbon dioxide gas generated in the three steps enter the cyclone separator to realize the separation of magnesium oxide powder and carbon dioxide; in the fourth step, the high temperature magnesium oxide powder settles to the silo, and is cooled by a heat exchanger to obtain lightly burned magnesium oxide powder; In the fifth step, part of the high-temperature and high-purity carbon dioxide is circulated as a fluidized gas, which is mainly coupled with methane to generate synthesis gas and methanol; in the sixth step, air and high-temperature magnesium oxide powder are exchanged through a rotary jacket heat exchanger. After heating, it is used for preheating magnesite powder to realize waste heat utilization.

Description

technical field [0001] The invention relates to a method for preparing light-burned magnesia, in particular to a method for preparing light-burned magnesia by cracking magnesite. Background technique [0002] Since 2015, with the increasingly stringent requirements of the national environmental protection policy, the magnesite processing industry in Haicheng, Liaoning Province, etc. has entered a period of industrial transformation and adjustment, and the magnesite processing industry has stopped production one after another, which has caused a huge impact on the refractory industry , the phenomenon of "Luoyang paper is expensive" once appeared, and the prices of various magnesite products rose sharply. [0003] Light-burned magnesia is an indispensable raw material for refractory materials such as dead-burned magnesia, fused magnesia, and magnesium refractory. For a long time, in order to obtain magnesia powder, only a simple mixture of coal and magnesite was used. Put it ...

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Problems solved by technology

[0005] At present, the reflective kiln (shaft kiln) has been ordered to process light-burned magnesia, so the technology of swirling flash-roasted magnesia powder has been gradually adopted. Because this technology meets the requirements of environmental protection and has a large production capacity, it is blooming everywhere like bamboo shoots after a rain, and enterprises have launched one after another. The production equipment, however, still does not consider the use or emission of carbon dioxide. It should be known that the carbon dioxide released by magnesite cracking plus the carbon dioxide released by fuel combustion produces about 4.6 tons of carbon dioxide per ton of magnesium oxide powder, which is a large amount of carbon dioxide emissions. , not only causing air pollution, increasing the greenhouse gas effect, but also wasting resources

[0006] Decomposition of magnesite by electric heating shaft kiln technology, and natural gas external heating rotary kiln technology have begun to decompose magnesite. However, the use of carbon dioxide has been reported to be made into dry ice, but the sales volume is limited, and the carbon dioxide produced by digestion limited, and the waste heat recovery and utilization of magnesium oxide powder is not clear. Moreover, the two processing technologies still have problems such as long processing time and intermittent production.

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