Sulfate of potash (SOP) is produced from primary and secondary sources. The primary sources of SOP are 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 a mixed sulfate salt known as polyhalite (the same mineral that will be extracted from the Ochoa mine). Primary production accounts for more than half of the world's production of SOP. The secondary source of SOP is the Mannheim process, in which muriate of potash (MOP) is processed using sulfuric acid or sulfate salt.
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 750,000 short tons. Other notable secondary producers of SOP include Qingshang and Migao Corp. of China. The table below summarizes SOP capacity by region.