System and method for preparing alkaline water used for preparing flocculating agent

Abstract

The invention discloses the preparation of alkaline water and particularly relates to a system and a method for preparing alkaline water used for preparing a flocculating agent for use in a red mud sedimentation separation and washing process step in an aluminum oxide production process. The system for preparing alkaline water used for preparing the flocculating agent comprises the following structures: a red mud washing liquid tank and a freshwater tank, wherein the red mud washing liquid tank is connected with a qualified alkaline water tank through a combined pipe; and the fresh water tank is connected to the combined pipe through a pipe. The system has the advantages that the substitution of red mud washing liquid for the alkaline liquid eliminates the use of high-concentration alkaline caustic liquid and improves the safety of production operation. The preparation of the alkaline water by using the red mud washing liquid allows for full utilization of the original heat energy of the red mud washing liquid and ensures the temperature can reach a temperature required by qualified alkaline water after the red mud washing liquid is diluted; therefore steam for raising temperature is not required to be added and energy consumption is lowered. The flocculating agent preparation process step is usually performed in a red mud separation and washing area, so as that the preparation of the alkaline water by using the red mud liquid has the advantages of short transport distance and low kinetic energy consumption.

Description

technical field [0001] The invention relates to a preparation system and method of alkaline water, in particular to a preparation system and method of alkaline water required for the preparation of flocculant used in red mud sedimentation, separation and washing process in alumina production process. Background technique [0002] In the process of alumina production, whether the flocculant used for sedimentation, separation and washing of red mud is liquid or powder, it needs qualified alkaline water to dissolve it. This alkaline water is called qualified alkaline water, and its qualified technical index: the concentration of caustic alkali is 10 ~20g / l, the temperature is 20~60℃. In the production process, qualified alkaline water needs to be prepared. There are two existing methods for preparing alkaline water: [0003] Method 1: Purchase high-concentration caustic lye, the concentration is 420g / l, dilute with water, and add steam to raise the temperature. [0004] Metho...

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Problems solved by technology

[0006] 1. In method 1, according to the amount of liquid caustic soda, caustic lye is regularly purchased from outside, and it needs to be unloaded and loaded into tanks. Once the lye is splashed during this process, there is a danger of burns, great unsafe risks, and high outsourcing costs

[0007] 2. In method 2, the process of providing seed liquor by the alumina plant is far away from the preparation process of flocculant for red mud separation and washing, so special pumps are required to transport seed liquor, which increases power consumption

Since the concentration of caustic soda in the mother liquor is about 150g / l and the temperature is about 60°C, it is necessary to add water 7 to 14 times the temperature of about 10°C, and the prepared alkaline water needs to be heated by adding steam to increase energy consumption.

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