The Mannheim process is an industrial process for the production of

hydrogen chloride The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride ga ...

and

sodium sulfate Sodium sulfate (also known as sodium sulphate or sulfate of soda) is the inorganic compound with formula Na2SO4 as well as several related hydrates. All forms are white solids that are highly soluble in water. With an annual production of 6 milli ...

from

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

and

sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...

. The Mannheim furnace is also used to produce

potassium sulfate Potassium sulfate (US) or potassium sulphate (UK), also called sulphate of potash (SOP), arcanite, or archaically potash of sulfur, is the inorganic compound with formula K2SO4, a white water-soluble solid. It is commonly used in fertilizers, pro ...

from

potassium chloride Potassium chloride (KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt ...

. The Mannheim process is a stage in the

Leblanc process The Leblanc process (pronounced leh-blaank) was an early industrial process for making ''soda ash'' (sodium carbonate) used throughout the 19th century, named after its inventor, Nicolas Leblanc. It involved two stages: making sodium sulfate from ...

for the production of

sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...

Process

The process is conducted in a Mannheim furnace, a large cast iron kiln. Sodium chloride and sulfuric acid are first fed onto a stationary reaction plate where an initial reaction takes place. The stationary plate is up to in diameter. Rotating rabble arms constantly turn over the mixture and move the intermediate product to a lower plate. The kiln portion of the furnace is constructed with bricks that have high resistance to direct flame, temperature, and acid. The other parts of the furnace are heat and acid resistant. Hot flue gas passes up over the plates carrying out liberated

gas. The intermediate product reacts with more sodium chloride in the lower, hotter section of the kiln producing sodium sulfate. This exits the furnace and passes through cooling drums before being milled, screened and sent to product storage facilities. The process involves intermediate formation of

sodium bisulfate Sodium bisulfate, also known as sodium hydrogen sulfate, is the sodium salt of the bisulfate anion, with the molecular formula NaHSO4. Sodium bisulfate is an acid salt formed by partial neutralization of sulfuric acid by an equivalent of sodium b ...

, an exothermic reaction that occurs at room temperature: :NaCl + H₂SO₄ → HCl + NaHSO₄ The second step of the process is endothermic, requiring energy input: :NaCl + NaHSO₄ → HCl + Na₂SO₄ Temperatures in the range 600-700 °C are required.{{cite book, last1=Riegel, first1=Emil Raymond, editor1-last=Kent, editor1-first=James Albert, title=Riegel's Handbook of Industrial Chemistry, url=https://archive.org/details/handbookofindust0000rieg, url-access=registration, date=1974, publisher=Van Nostrand Reinhold, location=New York, isbn=9780442243470, pag
132
edition=7th

References

Chemical processes