Salt discharging system and method in Bayer-process aluminium oxide production process

Abstract

A disclosed salt discharging system in a Bayer-process aluminium oxide production process comprises a strong-base storage tank, a salt settling tank, an overflow tank, a circulating mother liquor tank, filtering equipment and a causticization system; an evaporator-station discharging pipe in the aluminium oxide production process is communicated respectively with the strong-base storage tank and the circulating mother liquor tank; a discharge port of the strong-base tank is communicated with a feed inlet of the salt settling tank via a pump and a pipeline; the upper part of the salt settling tank is provided with an overflow pipe, and the bottom of the salt settling tank is provided with a bottom flow outlet; the overflow pipe is communicated with the overflow tank, and the bottom flow outlet is communicated with the causticization system via the filtering equipment; and a discharge port of the overflow tank is communicated with the circulating mother liquor tank via a pump and a pipeline. The invention also discloses a salt discharging method in the Bayer-process aluminium oxide production process, and the salt discharging system in the Bayer-process aluminium oxide production process is employed. Two functions such as alkali supplement and salt discharging during aluminium oxide production are both provided, running time of a forced circulation evaporator is reduced during aluminium oxide production, and energy consumption and equipment maintenance cost are reduced.

Description

technical field [0001] The invention belongs to the field of alumina production, and in particular relates to a salt discharge system and method in the production process of Bayer process alumina. Background technique [0002] During the production of Bayer alumina, the sodium aluminate solution contains a large amount of impurities such as sodium carbonate, sodium sulfate, and sodium aluminosilicate. Sodium carbonate is one of the most important impurities. If the concentration is too high, crystals will be precipitated under specific conditions, resulting in a decrease in the heat transfer coefficient of the heat exchanger in the system, pipe blockage and other hazards, which will have a huge impact on equipment efficiency and production continuity. influences. The source of sodium carbonate is mainly the raw materials required for production such as bauxite and lime. If it accumulates for a long time and is not eliminated, it will bring serious harm to the entire alumina...

AI Technical Summary

Problems solved by technology

This technology needs to configure special evaporator equipment, use steam for heating and concentration, and use electric energy for forced circulation, which consumes a lot of energy.

At the same time, due to the high concentration and strong corrosion of the solution, the requirements for equipment and pipes are high, and the maintenance cost is high.

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