The main ore body of the East Mine is located approximately 900 to 1,100 feet below the surface and is a mixed ore body with two minerals: sylvite (or potash) and langbeinite.

The Permian Delaware Basin in New Mexico is host to extensive potash deposits. The Delaware Basin deposits were the principal source of U.S. potash beginning in 1931. These deposits continue to be mined today. When New Mexico potash production was near its peak in 1966 and before the giant potash deposits of Canada were discovered, the Delaware Basin was the source of about 25 percent of the world’s potash (Jones and Madsen, 1968). In 2006, the Delaware Basin deposits supplied 19 percent of the potash for domestic use (Barker and others, 2008). The Delaware Basin formed in what today is west Texas and southeast New Mexico. The basin is bordered on the east by the Central basin platform and on the west by the Guadalupe Mountains. Midland Basin, east of the Central basin platform, is not known for potash deposits. The Delaware and Apache Mountains border the basin on the southwest and south, respectively. The basin has a 9,144-m-thick accumulation of Cambrian to Quaternary sedimentary rocks. Potash formed in the 609-m-thick Salado Formation that is part of the Ochoa Series (Lowenstein, 1988). The Ochoa Series is a sequence of ocean-basin carbonate reef, shoal, shale, and turbidite sandstone deposits. The series formed when a Permian seaway advanced into the area of what is today southern Arizona and New Mexico; northern Sonora, Mexico; and west-central Texas (Hayes, 1964). Salt evaporites that contain potash form stratiform beds that overlie the basin, reef, and shoal marine-carbonate deposits. The McNutt zone of the Salado Formation contains multiple potash beds that are interbedded primarily with halite and polyhalite but also contains minor siltstone and anhydrite (Lowenstein, 1988).

Sylvite and langbeinite ore at our Carlsbad locations occurs in a stacked ore body containing at least 10 different mineralized zones, seven of which contain proven and probable reserves.

The Carlsbad, New Mexico, potash deposits are at depths amenable to underground mining and accessed by vertical shafts between 198 and 533 m below the surface (Austin, 1980).

The Carlsbad deposits that are considered mineable contain a minimum of 10 percent potassium oxide in sylvite, or 4 percent potassium oxide in langbeinite. The Moab, Utah, potash deposit was mined by the underground method in the 1960s, but the Carlsbad deposits are the only U.S. potash deposits currently mined underground.

A 75-year mining legacy at the Carlsbad potash mine has generated significant mine waste at the surface. A primary geoenvironmental issue related to potash mining is the weathering of mine waste. Weathering of potash waste produces brine that may migrate from the waste site to nearby streams and soils and can be toxic to vegetation and aquatic life. A relatively dry climate near Carlsbad helps to mitigate waste weathering and reduce brine mobility.

The Carlsbad potash deposits differ from the nonstratiform potash-bearing salts of Moab, Utah. The potash at Carlsbad is in multiple, nearly flat, continuous beds that can be mined using a continuous mining machine. Continuous miners can extract sylvite-rich, gently dipping strata along miles of strike. A two-person crew operating a remotely controlled continuous mining machine and a loading car can mine as much as 600 to 1,000 metric tons of ore per 12-hour shift. Due to the precision of the mining equipment and skill of the operator, the continuous miner can avoid impure layers containing clay, salt, or dolomite and extract only high purity ore. Underground mining of potash is still profitable in the Carlsbad region today, making this one of the longest operating underground potash mines in the United States.

A conventional underground mine uses a mechanical method of extracting minerals from underground. Underground mining consists of multiple shafts or entry points and a network of tunnels to provide access to minerals and conveyance systems to transport materials to the surface. Underground mining machines are used to remove the ore and a series of pillars are left behind to provide the appropriate level of ground support to ensure safe access and mining.

Potash was mined from underground bedded deposits using continuous mining machines with shuttle car haulage from the face.

The East mine has a current estimated productive capacity of approximately 400,000 tons of Trio® annually, based on current design. The East mine was converted to a Trio®-only operation in April 2016 and potash is no longer produced from the East mine.

Ore extraction and conveyance to the surface is similar for both our East Mine and West Mine. The East mill produces 62 percent K2O white Muriate of Potash (MOP) from sylvite ore and Sulfate of Potash Magnesia products, Trio®, from the langbeinite ore. Potash is refined from the ore through hot brine dissolution of the potassium salts commonly called “hot leaching,” and then re-crystallization by rapidly cooling the brine. Natural gas boilers provide process steam.

The surface facility uses a flotation process to separate the sylvite from the salt. The refined sylvite is called Muriate of Potash or potash for short and is transported to the North Facility where it is compacted and processed into a granular form sui ........