Ammonia recovery process and equipment for non-ferrous metal metallurgical industry

Abstract

The invention discloses an ammonia recovery process and equipment for a non-ferrous metal metallurgical industry. The process comprises the following steps: mixing a base liquid with a raw material liquid in a pipeline and then feeding a mixed liquid to the upper part of an ammonia still, and carrying out steam stripping to remove ammonia in the raw material liquid; feeding a low-ammonia aqueous solution obtained at the bottom of the ammonia still to the next process; condensing gas-phase ammonia on the top of the ammonia still in an ammonia dephlegmator so as to obtain high-concentration ammonia gas; feeding the high-concentration ammonia gas into the bottom of an ammonia recovery tower to be absorbed by soft water; and recovering and recycling the high-mass-concentration ammonia water obtained at the bottom of the ammonia recovery tower, and evacuating trace fixed gas at the top of the ammonia recovery tower. The equipment is suitable for the ammonia recovery process disclosed by the invention and mainly comprises the ammonia still and the ammonia recovery tower, wherein the upper part of the ammonia still is in pipe connection with an alkali formulating tank through an alkali liquid pump and in pipe connection with a raw material liquid through a raw material pump; the ammonia dephlegmator is arranged inside the upper part of the ammonia still, and the lower part of the ammonia still is externally connected with a reboiler and is in pipe connection with the upper part of the ammonia still; and the kettle bottom of the ammonia recovery tower is in pipe connection with an ammonia water pump, the upper part of the ammonia recovery tower is in pipe connection with a soft water pipe, and the top of the ammonia recovery tower is provided with a discharge pipe.

Description

technical field [0001] The invention relates to an ammonia recovery technology in the chemical industry, in particular to an ammonia recovery process and equipment used in the nonferrous metal metallurgy industry. Background technique [0002] During the production of non-ferrous metals, a large amount of aqueous solution containing solid particles, volatile ammonia, non-ferrous metal ions, and complexes of non-ferrous metal ions and ammonia (referred to as raw material solution) is often produced. The raw material solution needs to be processed through ammonia recovery, and the volatilized ammonia and ammonia complexed with metal ions are removed to obtain a solution containing ammonia ≤ 150ppm, which is sent to the next process, and the removed ammonia is made into a solution with a mass concentration ≥ 20 % ammonia water, return to the previous process, recycle and reuse. [0003] The existing ammonia recovery process is as follows: the raw material liquid is sent to a b...

AI Technical Summary

Problems solved by technology

Due to the low efficiency of the bubble-cap tray, the ammonia content in the liquid phase at the bottom of the tower is high, which seriously exceeds the requirements of environmental protection indicators, thereby affecting the normal operation of subsequent processes; normal pressure operation and low ammonia removal rate make the tower top After the ammonia vapor is condensed by the condenser, only ammonia water with a mass concentration of about 5% can be obtained

On the one hand, the ammonia water cannot be recycled because the concentration is too low; on the other hand, most of the uncondensed ammonia is discharged as non-condensable gas, which not only causes a great waste of ammonia, but also makes the ammonia recovery rate very low. low and pollute the environment

In addition, the structure of the bubble-cap tray is easy to cause it to be blocked by solid particles in the raw material liquid. Once blocked, the production must be stopped for maintenance and clearing, or even replaced with a new tray, in order to maintain the normal operation of the distillation, which not only affects the normal production to reduce production efficiency and increase production costs

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