Ammonium Sulfate
The basics of Ammonium Sulfate
Ammonium Sulfate [(NH4)2 SO4] is an inorganic salt with a number of commerical uses. The most common uses are as soil fertilizer, food additives & in the treatment of drinking water.
(NH4)2 SO4 or AMSUL was one of the first and most widely used nitrogen (N) fertilizers for crop production. It’s now less common but especially valuable where both N and sulfur (S) are required. Its high solubility provides versatility for a number of agricultural applications.
Ammonium sulfate has been produced for more than 150 years. Initially, it was made from ammonia released during manufacturing coal gas (used to illuminate cities) or from coal coke used to produce steel. Today, manufacturers make it by reacting sulfuric acid with heated ammonia (see process schemes below).
To get the crystal size best suited for the application, the reaction conditions are controlled by screening and drying (centrifuges & ) the particles until achieving the desired size. Some materials are coated with a conditioner to reduce dust and caking.
| SHS pusher centrifuge | CONTURBEX screen scroll centrifuge |
|---|---|
| 302 | 250 |
| 402 | 320 |
| 502 | 400 |
| 602 | 520 |
| 702 | 700 |
| 802 | 1000 |
| 1002 | 1200 |
| Typical machine sizes centrifuges | |
Fertilizer – The primary use of Ammonium Sulfate is as a fertilizer for alkaline soils. In the soil the ammonium ion is released and forms a small amount of acid, lowering the pH balance of the soil, while contributing essential nitrogen for plant growth.
Food Additives | Acid Regulator (E517) – As a food additive, Ammonium Sulfate is considered generally recognized as safe (GRAS) by the U.S. Food and Drug Administration, and in the European Union it is designated by the E number E517. It is used as an acidity regulator in flours and breads.
Treatment of drinking water – In the treatment of drinking water, Ammonium Sulfate is used in combination with chlorine to generate monochloramine for disinfection.
Ammonium Sulfate – Centrifuges
Selection Criteria for SHS & CONTURBEX
| SHS | CONTURBEX | |
|---|---|---|
 | 
| |
| Minimum of the solid concentration in the feed | ||
| Average diameter d50 | %w/w | %w/w |
| < 0,5 mm | 40 | 20 |
| > 0,5 mm | 35 | 20 |
| Key Points | ||
| Solid layer | +++ Smooth product transport, less particle breakage and less solid losses to filtrate due to high thickness of solid layer. | ++ Thinner solid layer provides a quick dewatering, but may cause more particle breakage and higher losses of solids in the filtrate. |
| Solid concentration | + High and stable solid concentration is requested. | +++ Low and varying solid concentration can be handled. |
| Product washing | +++ Very good washing efficiency due to long retention time of product on the screen. | ++ Partly limited washing efficiency due to short retention time. |
| Product transport | + No forced product transport, product remains in the drum after feeding stop. Cleaning is requested before restarting the machine to prevent high vibrations. | +++ Forced product transport by the scroll - “self-cleaning” - minimum remaining product after feeding stop. |
| g-force | +++ Smooth product transport and less particle breakage due to low g-force. | + Higher g-force provides a quick dewatering, but more stressful product transport (scroll) may cause higher particle breakage and higher losses of solids in the filtrate. |
| Gas-tight execution | +++ Vapour- and gas tight execution available. | +++ Vapour- and gas tight execution available. |
Ammonium Sulfate Processes
Ammonium Sulfate out of ammonia gas and sulfuric acid
A) Synthetic production of Ammonium Sulfate out of ammonia gas and sulfuric acid.
Ammonium Sulfate – recovering out of wastewater
B) Recovering Ammonium Sulfate out of sulfuric- or ammonia containing wastewater from processes such as:
- Acrylnitrile (AN)
→ Acrylamide, glue, solvents - Methylmethacrylate (MMA)
→ Acrylic glass (plexiglass) - Caprolactam (CPL)
→ Polyamide 6 (textile fiber, foil).
Ammonium Sulfate as by-product (desulfurization)
C) By-product of the desulfurization of coke oven gas or ammonia-containing wastewater.
