SOP is produced from primary and secondary sources. The primary sources of SOP and SOPM come from minerals and natural occurring brines predominantly located in China, Germany, Chile, and the United States. In addition to these sources, the United Kingdom has begun to extract the mixed sulphate salt known as polyhalite (the same mineral IC Potash will extract). This primary production accounts for more than half of the world's production of SOP. The remaining portion of the world's supply comes from the processing of potassium chloride (MOP) with sulphuric acid or with a sulphate salt. This secondary source of supply can be produced anywhere raw materials can be shipped and processed and is known as the Mannheim Process.
The primary producers of SOP include SQM, SDIC Luobupo, GSL Minerals, and K+S Kali. SQM, SDIC Luobupo and GSL produce SOP by utilizing salt lakes whereas K+S Kali produces SOP from ore mined at its own sites. Due to this fact, K+S Kali could be considered a secondary producer. The secondary source of SOP supply is highly fragmented with Tessenderlo Chemie of Belgium having the highest capacity of 750 thousand short tons. Other notable secondary producers of SOP include Qingshang and Migao Corp. of China. The table below summarizes SOP capacity by region.