Electrolysis (used for sodium) fails because of the high solubility of potassium in molten KCl. Physical properties
The crystal structure of potassium chloride is like that of NaCl. It adopts a face-centered cubic structure. Its lattice constant is roughly 6.3 Å.   Crystals cleave easily in three directions. Some other properties are

Transmission range: 210 nm to 20 µm
Transmittivity = 92% at 450 nm and rises linearly to 94% at 16 µm
Refractive index = 1.456 at 10 µm
Reflection loss = 6.8% at 10 µm (two surfaces)
dN/dT (expansion coefficient)= −33.2×10−6/°C
dL/dT (refractive index gradient)= 40×10−6/°C
Thermal conductivity = 0.036 W/(cm·K)
Damage threshold (Newman and Novak): 4 GW/cm2 or 2 J/cm2 (0.5 or 1 ns pulse rate); 4.2 J/cm2 (1.7 ns pulse rate Kovalev and Faizullov)As with other compounds containing potassium, KCl in powdered form gives a lilac flame. Production
Potassium chloride is extracted from minerals sylvite, carnallite, and potash. It is also extracted from salt water and can be manufactured by crystallization from solution, flotation or electrostatic separation from suitable minerals. It is a by-product of the production of nitric acid from potassium nitrate and hydrochloric acid. The vast majority of potassium chloride is produced as agricultural and industrial grade potash in Saskatchewan, Canada, as well as Russia and Belarus. Saskatchewan alone accounted for over 25% of the worlds potash production in 2017. Laboratory methods
Potassium chloride is inexpensively available and is rarely prepared intentionally in the laboratory.
Wheal may refer to:

Wheals, a type of skin lesion
Brad Wheal (born 1996), British cricketer
Donald James Wheal (1931–2008), British British television writer, novelist and non-fiction writer
David John Wheal, Australian businessman
"The Wheal", a 1987 song by Coil

See also
All pages with titles containing Wheal
Mining in Cornwall and Devon, includes mines whose names include Wheal
Wheel (disambiguation)