From: veritasium
Mysterious electric blue ponds visible from high above in the Utah desert are actually part of a process to extract potash, a chemical that has been prized throughout human history and is deeply connected to various industries and technological advancements [00:01:00].
What is Potash?
Historically, potash was produced from hardwood ash [00:02:24]. A 1,500-year-old recipe involved burning hardwood for its ash, adding water to the ash in a pot, straining out solids, and then evaporating the water in the sun to leave behind a crystalline substance [00:02:29]. This substance was called potash because it literally came from “pot ash” [00:03:00].
In 1807, British scientist Humphry Davy discovered a new element by putting electrodes into damp potash connected to a battery [00:03:06]. He observed the formation of tiny metal globules that spontaneously caught fire, leading him to name the new element “pot-ash-ium,” or potassium [00:03:17].
Potassium is an incredibly reactive metal that must be kept submerged under oil to prevent it from reacting with water in the atmosphere [00:04:02]. When pure potassium reacts with water, it forms potassium hydroxide and hydrogen gas, releasing a lot of heat that causes the hydrogen gas to spontaneously combust [00:05:02]. This reactivity is due to a single electron in its outermost shell, which is easily removed [00:05:16]. The term “potash” has evolved to become a catchall term for many potassium-containing compounds, not just potassium carbonate, which was the original form from ash [00:05:32].
Early Industrial Applications
Potash has been a vital ingredient in several early industrial processes:
- Soap Manufacturing: For centuries, potash was used with animal fat to create primitive liquid soap through a chemical reaction [00:06:08].
- Glassmaking: Adding potash to sand (silicon dioxide) reduces the melting point of glass, making it less brittle and easier to work with in early furnaces [00:06:33].
- Gunpowder Production: By adding bat guano or manure to a potash solution, crystals of potassium nitrate (also known as saltpeter) form [00:06:57]. Saltpeter is a core ingredient in fireworks and gunpowder [00:07:08]. Potash-infused gunpowder was crucial in battles during the American Revolution and other historical conflicts [00:07:26].
Potash in Early American Economy and Patents
Potash was the primary chemical product of the early American colonies and a significant source of revenue [00:07:48]. By 1788, Massachusetts alone had 250 potash works, where wood was burned on a massive scale solely for its ash [00:07:55].
The newly-independent U.S. government issued its first ever patent on July 31, 1790, for an improved process for making potash [00:08:09]. This patent was signed by President George Washington, underscoring the immense importance of potash at the time [00:08:32].
The high demand for potash led to widespread deforestation across Europe and the eastern U.S., as vast amounts of lumber were required to produce even a small quantity of potash [00:08:43].
Transition to Mineral Potash and Geopolitical Impact
In 1861, Germany began producing potassium from a different source: rock deposits containing potassium chloride, which also became known as potash [00:08:56]. This discovery revolutionized the industry, allowing Germany to establish a near monopoly on the global potash supply [00:09:24].
Germany found new uses for their abundant supply, discovering that potash acted as an excellent fertilizer [00:09:28]. Potassium, along with nitrogen and phosphorus, helps crops grow larger and makes them more drought-resistant [00:09:40].
Before World War I, in 1910, Germany cut off potash exports to the world, demonstrating its strategic importance [00:09:51]. This act deprived countries of a chemical essential for feeding their growing populations [00:10:01]. Consequently, in 1911, the U.S. Congress appropriated money to find domestic sources of potassium, leading to the discovery of potash deposits near Searles Lake, California; Carlsbad, New Mexico; and Moab, Utah [00:10:08].
Evolution of Mining Techniques
Initially, potash rock deposits, found deep underground in formations like the Paradox Formation in Utah, were mined using traditional underground methods similar to coal mining [00:10:33]. These deposits were formed by the evaporation of ancient inland oceans [00:11:06].
A tragic explosion occurred on August 27, 1963, at the Moab potash mine, resulting in the deaths of 18 men [00:11:52]. Investigators concluded the disaster was caused by the ignition of combustible gas—methane—by electric arcs, sparks, or open flames [00:12:02]. This highlights the inherent dangers of underground mining. An invention designed to prevent such explosions was the Davy lamp, invented by Sir Humphry Davy, which uses a wire mesh to disperse heat from a flame, preventing the ignition of gas outside the screen [00:12:20].
A safer method of extraction, known as solution mining, was discovered in 1964 by a Canadian mining company in Saskatchewan [00:14:05]. This technique involves pumping water deep underground (in Utah, from the Colorado River, 3,900 feet down) to dissolve the potash salt [00:14:16]. The resulting brine solution is then pumped back to the surface and into large evaporation ponds, where the water evaporates under the sun and dry air, leaving behind the potash [00:14:36].
The evaporation ponds in Utah, covering 400 acres, are distinctively blue due to the addition of copper sulfate [00:15:55]. Copper sulfate prevents the growth of algae and other organisms, and its dark blue color absorbs more sunlight, accelerating water evaporation [00:17:10]. The color of the ponds changes from deep blue to seafoam green and then tan as the water evaporates, eventually leaving white crystalline potash to be scraped up [00:16:19]. The Paradox Basin alone contains an estimated 2 billion tons of potash [00:16:01].
Modern Impact: Feeding the World
Today, fertilizer supports half of the world’s population [00:17:30]. The efficient harvesting of potash and other essential minerals has been crucial for the growth of global food supplies [00:17:36]. The ability to grow crops efficiently with the help of fertilizer has freed up human time and resources, allowing societies to explore different ways of life beyond basic food gathering, fostering the development of arts, music, and science [00:18:04].
Potash is considered irreplaceable and has significantly contributed to making the modern world what it is today [00:18:30].