Hydrochloric Acid

Medium Concentration

A medium concentrated acid with a concentration of 30 - 35 % is produced from any diluted raw Hydrochloric Acid.

The dual pressure process and extractive rectification are available for medium concentration. The quality of the recovered Hydrochloric Acid of commercial grade is in accordance with DIN 19610 or the more stringent German LAGA standard.
It is primarily used to strengthen pickling acid or as a solvent and reagent in the chemical industry, in ore leaching, in waste water treatment, as a regenerating agent for ion exchanger resins, etc.

Dual pressure process

For production of medium concentrated Hydrochloric Acid also the dual pressure process is available. In the first step pre-concentrated acid of about 22 - 24 % HCl is split into the head product with about 30 - 35 % HCl and the sump product azeotropic acid using rectification under pressure. In the second step the azeotropic acid is re-strengthened by evaporating water at vacuum conditions up to 22 - 24% HCl and then recycled to the first step.

As an alternative the azeotropic acid can also be re-strengthened using high concentrated HCl gas.

 

Extractive rectification

Dilute Hydrochloric Acid mixed with an extraction agent is fed into the rectification column. Due to the extraction agent, the water is absorbed and the volatility of the Hydrochloric Acid is increased. At the head of the column, medium concentrated Hydrochloric Acid is refined; a diluted extraction agent is obtained in the sump, which is concentrated in an external evaporator and fed back to the rectification column.

Brine, like CaCl2 or MgCl2, may be used as an extraction agent to remove the water in a concentration, which ranges between 40 and 50 % as well as sulfuric acid in a concentration ranging from 55 to 75 %. By using extractive rectification, low HCl residual contents can be achieved in the aqueous condensate (acid water). This can be realised with only slight additional technical investment and at low energy costs.