Method for filtering and washing raw red mud

Abstract

The invention discloses a crude red mud filtrating and washing process, which consists of loading crude red mud slip from the red mud grading procedure into horizontal band filters or flat disc type filters for filtrating and washing, wherein the distribution head on the filters divides the whole filter into a separation zone and a washing zone, loading the crude liquor obtained in the seperation zone into a desiliconisation procedure, entering the filter cakes of seperaton area into the washing zone, proceed reversal washing for two to three times, loading the washed red mud cleaning solution to a dissolving procedure, loading the washed crude red mud to sponge iron plant for reclamation of iron.

Description

Technical field: [0001] The invention relates to an alumina production process, which is suitable for filtering and washing coarse red mud of high-iron bauxite. Background technique: [0002] The existing alumina plants in my country mainly use diaspore as raw material, and a few alumina plants also use gibbsite ore imported from abroad. Under normal circumstances, the ore is ground finer, and the raw ore pulp after grinding is dissolved, diluted, red mud sedimentation, separation and washing, and the bottom flow of the final washing settling tank is filtered with a plate and frame filter press or a cylindrical filter. The red mud is sent to the red mud yard for storage. [0003] The high-iron bauxite in Guangxi is a new type of mineral resource. It contains two useful minerals, alumina and iron, and the content of iron oxide in the ore is greater than that of alumina. Any kind of mineral is uneconomical, and aluminum and iron must be recovered at the same time to have hig...

AI Technical Summary

Problems solved by technology

When the concentration and temperature of the dissolved alkali are increased, and the ore is further ground, not only the dissolution rate of alumina cannot be increased, but the silicon minerals in the ore will participate in the chemical reaction, resulting in an increase in alkali consumption and a decrease in the dissolution rate of alumina.

[0005] Since the grinding particle size of this ore is much coarser than that of the existing alumina plant, the particle size of the red mud after dissolution is also relatively coarse. If the sedimentation tank is directly used for separation and washing, the coarse red mud has a large specificity and a fast settling speed. Due to the slow stirring speed of the settling tank, the coarse red mud will be blocked at the bottom of the tank and cannot be discharged, causing the settling tank to not work normally; in addition, the alumina content in the ore is low, and the ore consumption per unit product is large, and the output of alumina per ton The amount of red mud is 4 to 5 times that of the existing alumina plant, reaching 4.5 to 5.0t / t-Al 2 o 3 , for such a high amount of red mud, and it is necessary to control the amount of red mud washing water added in the process. Considering this condition, the existing settling tank cannot operate normally due to the limitation of the liquid-solid ratio of the feed and the washing water index, and must be Adopt new red mud treatment technology