Powder From Kariandusi

When thinking about diatomite in the Kenyan context, one should consider its mining location, the process that goes into mining and processing it, and the company responsible for its processing. 

The formation of The Great Rift Valley gave rise to unique natural structures, and in the East African Rift System, one of these structures is Kariandusi, a settlement in Nakuru County. Located about 28 kilometers from the county’s administrative capital, Nakuru town, Kariandusi is said to possibly be the first Acheulian site in East Africa. Discovered by archeologist Louis Leakey on an expedition in 1928, findings indicated that the area was occupied as far back as 1 million years ago.  

It is in Kariandusi, a few kilometers from Lake Elementeita, that we find diatomite.  

Diatomite, formed from the word ‘diatom’, is a sedimentary rock that easily crumbles into white powder. Scientifically, it is defined as the naturally occurring fossilized remains of single-celled aquatic algae (diatoms). 

A number of factors make this mineral valuable. From its low density, its insulating properties, its high porosity, and its inertness. It is vital in the manufacturing of filter aids for food and beverage processing, in the dental industry for dental fillings, is used as an additive in paints and plastics, and as a cleaning agent in the cleaning industry. It can be incorporated in soil to increase water and air permeation, and acts as a natural insecticide. Additionally, diatomite contains silica which is used as a food additive and in the pharmaceutical industry as a filler in drugs and vitamins. 

In 1942, the African Diatomite Industries Limited was formed and the factory was set up to the east of Lake Elementeita, where Kenyan mined diatomite is crushed, dried, then milled. 

The mining and processing of diatomite is a delicate, expensive and complicated process – but we will make it simple. To start, diatomite mining requires heavy, earth moving equipment. Processing plants which are often large factories need to be in close proximity. Most times, diatomite is mined in open-pit or surface mines where a considerable thickness of the earth is first removed and the purest of the diatomite is exposed. Thereafter, using scrapers, the material is cut and stockpiled.  

The stockpiled material (usually large pieces the size of small cars) goes into a processing plant where it is crushed (into much, much smaller sizes). The ore, which is usually full of moisture because of where the mineral is obtained, is heated to about 980 degrees Celsius, then milled to preserve the structure. The powdery material obtained is then packaged and distributed for selling. 

Kariandusi Prehistoric site. Image credit: Geocaching

Nakuru map