Mannheim process

Several types of chemical processes are used to produce potassium sulfate. The traditional Mannheim process is used in countries that produce KCl but lack a natural source of sulfate salts for converting the KCl to K2SO4. In this process, KCl reacts with sulfuric acid to yield K2SO4 and HCl as a co-product. 

The Mannheim process produces sodium sulfate by reaction of sodium chloride and sulfuric acid. 

This is called the Hargreavesprocess. Only a minor amount of sodium sulfate is made in the United States using the Hargreaves process, but both the Hargreaves and the Mannheim processes are used widely in the test of the wodd. Table 4 hsts U.S. producers and capacity information for natural and synthetic sulfate in 1992. 

Potassium sulfate (K2SO4) is produced from mixed minerals or brines such as langbenite ore, K2S04 2MgS04, found in Mexico. Reaction with potassium chloride gives pure potassium sulfate. In the Mannheim process potassium chloride reacts with sulfuric acid to give the sulfate. 

Also, potassium sulfate can be made by two other processes in which no naturally occurring mineral is employed. In the Mannheim process, the salt is produced by action of sulfuric acid on potassium chloride ... 

Sodium sulfate is synthesized by the Mannheim process or Hargreaves process. Manheim s process is based on GlaubePs reaction between sulfuric acid and sodium chloride ... 

For those producers who do not have access to such suitable sulfate salts to serve as the sulfate donor, the so-called Mannheim process, in which sulfuric acid is reacted with KCl, may be utilized. The following reaction unfortunately generates the corrosive substance hydrochloric acid as a co-product ... 

Sodium sulfate is produced from natural sources and as byproduct in a variety of processes including ascorbic acid, battery recycling, resorcinol, silica pigment, viscose rayon, and sodium bichromate. Other salt cake production processes are based on the reaction of sulfuric acid (Mannheim process) or S02 and air (Hargreaves process) with sodium chloride. The Mannheim process is no longer in use in the United States. U.S. Hargreaves capacity is very limited. However, both processes are used widely in the rest of the world. 

In the Mannheim process, NaCl and 100 percent H2S04, in amounts equivalent to complete conversion to Na2S04, are fed to a circular muffle furnace made of cast iron. The furnace is equipped with a shaft, which penetrates from below and carries four arms, each of which is fitted with two cast iron plows. The shaft rotates at 0.5 rpm, slowly plowing the heated mixture to the circumference where the burned cake discharges through a chute. The furnace charge is heated to about 840°C, just below the fusion temperature of the salt cake. HC1 is liberated, cooled, and absorbed in water to produce 32 percent HC1 for sale. The salt cake is really a byproduct of the operation. 

Sodium sulfate is also formed as a byproduct in the manufacture of hydrogen chloride by the reaction of sodium chloride with sulfuric acid at high temperatures (Mannheim process, Hargreaves process and the fluidized bed process). At the end of the I970 s the Mannheim process was used to produce about half of the sodium sulfate produced in Europe. However, these processes are hardly operated any more. 

Potassium Sulfate Production 15.5.2.1 Mannheim Process - Historically potassium sulfate has been made primarily from KCl and sulfuric acid (and a small amount from KCl and SO2) when the byproduct HQ was the dominant product. However, over the years the HCI market has had more competition, and natural K2SO4 with lower capital and operating costs has begun to dominate its production in some countries with natural complex salts. 

The Mannheim process was originally developed from sodium sulfate production by reacting NaCl wTth suffuric acid. Replacing NaCl wth KCl produces potassium sulfate. The reaction is two-stage ... 

The antibiotic chloramphenicol, which is mainly used in veterinary medicine, is produced by the Boehringer Mannheim process from dnnamic alcohol, which in turn is obtained from benzaldehyde through aldol condensation with acetaldehyde and reduction of the intermediate cinnamaldehyde. 

Oxidation of Salt. Salt can be decomposed by strong acids. The Mannheim process was used for many years to produce HCl and salt cake from salt and sulfuric acid ... 

Sulfuric acid is used for a variety of other purposes in the chemical industry. For example, it is the usual acid catalyst for the conversion of cyclohexanone oxime to caprolactam, used for making nylon. It is used for making hydrochloric acid from salt via the Mannheim process. Much H2SO4 is used in petroleum refining, for example as a catalyst for the reaction of isobutane with isobutylene to give isooctane, a compound that raises the octane rating of gasoline (petrol). Sulfuric acid is also important in the manufacture of dyestuffs solutions and is the "acid" in lead-acid (car) batteries. 

Production capacity for sodium sulfate, or salt cake, has remained fairly constant over the last decade, with the number of producing plants continuing to decline. Over half of the U.S. supply of Na2S04 is produced from natural brines. Most of the remainder is by-product derived from the production of viscose rayon, sodium dichromate, and sulfonation process phenol. Salt cake produced in the manufacture of HCl from salt by the action of sulfuric acid (Mannheim process), or SO2 and air (Hargreaves process), is on the decline. 

Wohler and Mahla Foimd that chromium and copper oxides oxidized sulfur dioxide. Copper metal inactive the first comment on oxidation with oxide catalysis. Showed iron and copper were reduced and oxidized during reactiorr Findings later applied to Mannheim process [Arm. Chim. Pharm. 81,255 (1852)]. 

Further development of the contact process did not rely on a better catalyst but depended on better methods to remove poisons and clean the gases produced by roasting pyrites, which, by then, had replaced sulfur as the preferr source of sulfur dioxide. In attempting to overcome the difficulty, the Mannheim process used a bed of relatively inactive iron oxide to guard the main bed of a platinum catalyst. New Jersey Zinc and the General Chemical Company in the United States built plants of this kind in 1899 and 1901, respectively. 

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