Method for preheating canalization molten-salt section during producing alumina

Abstract

The invention discloses a method for preheating a canalization molten-salt section during producing alumina and relates to a method for preheating a molten-salt heating section before pump starting of canalization molten-salt during producing alumina. The method is characterized in that the preheating of the canalization molten-salt section is realized in such a way that dead steam in a self-evaporation system is adopted to heat ore pulp in a canalization stripping pipe and molten salt in an interlayer of the canalization stripping pipe is preheated through the heated ore pulp. Compared with the prior art, the method for preheating a canalization molten-salt section during producing alumina adopts steam heating, low fault compared with electric tracing cords, lower investment and running cost than electric tracing, short heating time, can achieve temperature needed for the start of the canalization device in short time, can preheat the whole system through self-evaporation systems of a canalization system at all levels and is beneficial to establishing heat balance after the canalization device starts.

Description

technical field [0001] The invention relates to a preheating method for a pipelined molten salt section in an alumina production process, and relates to a method for preheating a molten salt heating section before starting a pipelined dissolution salt pump for alumina production. Background technique [0002] Pipeline dissolution is an important link in the Bayer alumina production process. The slurry heating process is divided into three processes. The molten salt heating section is the most important heating stage. It uses heat-carrying molten salt to heat the slurry. To the required dissolution temperature, the heat-carrying molten salt used is made of KNO 3 、NaNO 3 、NaNO 2 Composed of three components, in order to prevent the molten salt from solidifying, the pipeline device must go through the preheating process of the molten salt heating section before starting the pipeline device in a cold state after cleaning and maintenance. It is required that the temperature of ...

AI Technical Summary

Problems solved by technology

[0005] 1. The electric heating wire is easily damaged, and the pipeline cleaning adopts hydraulic cleaning. If water enters the electric heating wiring during cleaning, it will cause damage to the electric heating wire and affect the life of the electric heating wire

[0006] 2. It is difficult to replace the electric heating wire. The insulation of the whole pipe must be removed first, and then the electric heating wire can be replaced. It takes about 2 days

[0007] 3. The cost of the electric heating wire is high, the value of the electric heating wire in the molten salt heating section is more than 200,000 yuan, and the investment cost and replacement cost are high

[0008] 4. The heating time of the electric heating wire is long, and it takes about 20 hours for the pipeline in the molten salt heating section to be heated to above 180°C required for the start-up of the device, which causes the start-up time of the entire pipeline device to be prolonged