Production process of low-ammonia wet sodium bicarbonate

Abstract

The invention relates to the field of soda ash production, in particular to a production process of low-ammonia wet sodium bicarbonate. The production process includes the steps of increasing the amount of causticizing liquid required for brine refining, increasing the concentrations of OH<-> and CO3<2-> in refined brine, ensuring that the turbidity index of the refined brine is lower than or equal to 25 ppm, and controlling the total chlorine concentration of the refined brine to be not more than 5.35 mol / L to obtain low-calcium-magnesium refined brine; feeding the refined brine as an ammoniapurification medium into a tail gas ammonia purification tower to purify outlet gases of an alkali filter through ammonia absorption, discharging outlet liquid to a furnace gas scrubbing tower of a light ash process, purifying furnace gases through ammonia absorption, and feeding the low-ammonia brine to a low-ammonia brine bucket; with low-ammonia cold light waste liquid or desalted water whichhave the ammonia concentration lower than 0.05mol / L as the alkali filter wash water, preparing the wet sodium bicarbonate with the low content of volatile ammonia components through a sodium bicarbonate filtration process, and delivering the wet sodium bicarbonate to a downstream process. The wet sodium bicarbonate provided by the invention has low content of the volatile ammonia components, thereby ensuring the salt index of end products and reducing the ammonia and chloride diffusion loss in wet sodium bicarbonate filtration and downstream process production.

Description

technical field [0001] The invention relates to the field of soda ash production, in particular to a low-ammonia wet heavy alkali production process. Background technique [0002] In the two processes of heavy alkali filtration and light ash furnace gas recovery in the soda ash production system, the cold waste liquid (or desalted water) with a single material ammonia concentration below 1ti (0.05mol / L) is generally used for reuse to complete the purification of gaseous ammonia and Alkali filter machine washing water two processes. Firstly, as a net ammonia medium, the cascade utilization completes the ammonia purification and recovery of the outlet gas of the vacuum alkali filter and the light ash furnace gas, and then returns to the alkali filter for secondary use as a washing medium to reduce the wet heavy alkali salt. In the original process, the cold waste liquid (or desalted water) with an ammonia concentration below 1ti (0.05mol / L) can be reused reasonably, but the o...

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Problems solved by technology

In the original process, the cold waste liquid (or desalted water) with an ammonia concentration below 1ti (0.05mol / L) can be reused reasonably, but the original process has a big disadvantage, that is, after the gas cascade purification is completed, the furnace gas cleans the ammonia liquid The ammonia concentration is as high as 14ti-20ti (0.7~1mol / L), which can be reused as washing water for caustic soda filter

After the wet heavy alkali is separated from the alkali filter, about 19% of ammonia-containing aqueous solution is entrained, and the loss of ammonia gas is large in the process of separation, transportation and downstream production, which increases the consumption of ammonia in production, and also causes ammonia odor in related posts and equipment areas Big, poor air quality

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