Slagging-free type and multilevel differential temperature fluidized roasting system for crystallized aluminum salt and method thereof

Abstract

The invention provides a slagging-free type, low-energy consumption and multilevel differential temperature fluidized roasting system for crystallized aluminum salt and a method thereof. The system comprises a crystallized aluminum salt low-temperature roasting system, an aluminum oxide high-temperature finished product roasting system, a high-temperature aluminum oxide multilevel fluidized cooling and heat recovery system and a chimney. The method comprises the following steps of: reducing the outlet temperature of low-temperature roasting flue gas with large gas production rate by adopting a differential temperature multiple roasting method, so that sensible heat carried by the flue gas is greatly reduced; and carrying out reasonable cascade utilization on energy and converting fuel chemical energy inputted by a process system into effective heat of the system to a greatest extent. The slagging-free type and multilevel differential temperature fluidized roasting system has the remarkable advantages of strong adaptability to the content of attached water of the crystallized aluminum salt, good adjustment and stability, high product purity, low energy consumption, low investment, small floor area and the like.

Description

technical field [0001] The invention relates to a slagging-free, low energy consumption, multi-stage differential temperature fluidized roasting system and method for crystalline aluminum salts, in particular to a multi-stage, differential temperature roasting process for preparing industrial alumina by fluidized roasting crystalline aluminum salts systems and methods. The crystalline aluminum salt may include crystalline aluminum chloride hexahydrate, crystalline aluminum sulfate, aluminum hydroxide and the like. Background technique [0002] my country is the largest alumina producer in the world, but there is a serious shortage of high-grade bauxite in my country, which has seriously affected the rapid development of my country's alumina industry. my country is a big country with coal power, and a large amount of high-alumina fly ash (Al 2 o 3 ≥38wt%), according to statistics, the annual output of high-alumina fly ash is as high as 100 million tons, which is a very imp...

AI Technical Summary

Problems solved by technology

At present, the use of rotary kilns as high-temperature roasting equipment for crystalline aluminum salts has the advantage of being easy to implement, but industrial devices such as rotary kilns have the following problems: thermal decomposition of crystalline aluminum salts at a low temperature of 200-300 °C needs to absorb a large amount of heat, and the rotary kiln can only The heat source is provided at the kiln head, which will inevitably lead to insufficient heat absorption or uneven heating of the crystalline aluminum salt in the low-temperature roasting section at the rear of the rotary kiln, resulting in low reaction efficiency

However, when the conventional aluminum hydroxide fluidized roasting system is used for the roasting and preheating of the crystalline aluminum salt, there are the following technical problems: ① The low-temperature drying of the crystalline aluminum salt needs to absorb a large amount of heat, so if the conventional multi-stage series cyclone is used to recover the waste heat As a preheating unit, due to the concentrated release of a large amount of crystal water, the heat supply is insufficient and untimely, and the material continues to be in a low-temperature state, which is prone to agglomeration and slagging, and the continuous operation performance of the equipment is poor.

②In the preheating unit, the corrosive gas released by the decomposition of crystalline aluminum salt (such as HCl, SO 3 ) is easy to condense and cause dew point corrosion, which brings serious corrosion problems to the equipment, and the material requirements are high

③Crystalline aluminum salt roasting has a large heat absorption and decomposes to produce a large amount of corrosive gas and water vapor. If a conventional single fluidized bed roaster is used to process crystallized aluminum salt in industrialization, the roaster is bulky and the amount of combustion material required for roasting is large , economically unfeasible

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