What is HCL and how is it different from other strong mineral acids?

HCL (hydrochloric acid) is a solution of hydrogen chloride gas in water, a strong inorganic acid, volatile, corrosive to metals and minerals. Compared with H2SO4, the solution is more flexible in removing rust from steel and adjusting pH, but it creates acid mist so good vapor control is required.

What are the stages of industrial HCL production process?

Reaction stage H2 + Cl2 → 2HCl in the combustion chamber; then absorb HCl gas into demineralized water in the main absorption tower; recover excess gas in the excess gas absorption tower; use ejector to create vacuum and cooling system; finally the finished product tank 31,5–35%.

What is HCL used for in a factory?

Main applications: steel pickling, PVC and isocyanate production (MDI/TDI), water treatment, industrial cleaning, oil and gas exploitation (acidizing), gelatin processing, pH adjustment for some food processes within legal limits.

How to store HCL safely?

Store in steel drums, IBCs or compatible material lined tanks (PVC/FRP/PTFE), with bunds, ventilation, emergency wash down system; avoid heat, sparks; wear acid vapor respirator, chemical resistant gloves, suitable fire extinguisher.

Production process of Hydrochloric Acid – HCL 32% (ACID 32%)

By Basic Chemistry 10/09/2025 News

HCL (Hydrochloric Acid) production process in modern industry

HCL is one of the world's largest-volume basic chemicals, playing an important role in metal descaling, PVC production, water treatment, and industrial cleaning. This article provides an overview of the technology, equipment, operating parameters, quality control, and EHS requirements so you can evaluate, select, and operate effectively.

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Overview & properties of hydrochloric acid

This solution is created when hydrogen chloride gas dissolves in water. At concentrations around 40% it can create acid mist; the common commercial range is 31,5–35% for industrial use. Notable properties: strong acid, reacts with alkalis, metal oxides and some salts; has the ability to dissolve rust quickly, compatible with PVC, CPVC, PTFE, FRP.

CTPT	HCl (hydrochloric acid)
CAS	7647-01-0
A Number	UN 1789 (Corrosive)
Concentration range	31,5–35% (commercial), max ~40%

Odor	Pungent, produces acid mist at high concentrations
Specific gravity (25°C)	~1.16–1.18 g/cm³ (32–35%)
pH	< 1 (strong solution)
Corrosive	Corrosive to many metals; produces H2 when reacting with iron, zinc, etc.

HCL production process: reaction, absorption & recovery

1) Background reaction

Hydrogen gas reacts with chlorine in the combustion chamber according to the equation:

H₂ + Cl₂ → 2HCl (gas)

The product mixture is cooled, led to the absorption tower in contact with mineral-free water to create an acid solution of the desired concentration.

2) Main equipment and production line diagram

Combustion chamber: reaction zone, acid-resistant and heat-resistant material; with water-cooled jacket.
Main absorption tower: Graphite/carbon layer structure, optimizing gas-liquid contact surface area; temperature control to limit acid mist.
Excess gas absorption tower: recover the undissolved gas, reduce emissions.
Vacuum Ejector: Use high pressure steam to maintain the gas flow from bottom to top, increasing recovery efficiency.
Finished product tank: Compatible materials, with bund and leak sensor.

3) Operational description

Start: inert gas (N) blowing₂) chase away the burning mixture; primer H₂, then give Cl₂ into reaction.
Absorb: Adjust the flow of demineralized water to achieve the target concentration; control the temperature to reduce fogging.
Recall: Excess gas is sent to the auxiliary tower; the solution reaches the standard of the finished product tank.

Operating parameters & quality control

Cl pressure₂ input	80–350 mmH₂O
Pressure H₂ input	70–150 mmH₂O
Cooling temperature	33-35 ° C
Finished product concentration	31,5–35% (w/w)

Impurity index	Low Fe (dark yellow water is a sign), As & heavy metals as per COA, Free Chlorine controlled to reduce corrosion
Labeling	GHS/CLP, Corrosive, acid mist hazard
Packaging	200 L steel drum, 1000 L IBC, separate tank
Storage	Ventilation, overflow bund, emergency shower

Safety, Environment & Fire Prevention

Wear PPE: glasses/face-shield, chemical-resistant gloves, boots, anti-corrosion clothing; have an acid vapor filter mask when working near a mist source.
Grounding – anti-static when pumping – pouring; limit reactive metal materials.
Spill treatment: isolate area, neutralize with weak alkali (NaHCO₃), collect waste solution according to regulations.

References: Overview of Hydrochloric Acid on
ScienceDirect
and health and safety recommendations
NIOSH (CDC).

Practical application in the factory

Metal rust removal & surface preparation

Acid solution rapidly removes iron oxide layer before galvanizing, tin plating or painting. Requires proper vapor recovery, corrosion inhibition and waste tank treatment systems.

Petrochemicals & Polymer Materials

Intermediate role in the PVC chain; involved in the production of MDI/TDI for polyurethane. Free chlorine impurities require control to reduce equipment corrosion.

Water treatment & industrial cleaning

Adjust pH, clean pump and pipelines from inorganic deposits. In wastewater systems, pay attention to alkalinity balance to limit pH fluctuations.

Oil and gas extraction (acidizing)

Used for cleaning near-seam areas, dissolving mineral salts, improving permeability; requires strict safety procedures and corrosion inhibitor additives.

Internal links:
HCL product 32–35% •
32% NaOH •
Javen (NaOCl)

Contact – Industrial HCL quotation

Loc Thien Investment and Development Company Limited Providing industrial standard HCL, clear COA, fast delivery in Central & Southern regions.

Station: 452/6B Provincial Road 10, Binh Tri Dong Ward, Binh Tan District, Ho Chi Minh City
Phone: 028 6269 5669 - 028 6269 5662
Hotline: Phone: (+84) 979 891 929
Email: locthien@locthien.vn
Website: https://hoachatcoban.net

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