Magadi ward lies in the Great Rift Valley, about 120 km South West of Nairobi at a latitude of 605m (2000 feet) above sea level. Lake Magadi consists of a deep crystalline bed of Trona (the name given to the naturally occurring solid mineral content), which is a mixture of sodium sesquicarbonate, sodium chloride, other sodium salts and clays, together with a small amount of organic matter. The Trona deposit is up to 30 meters thick, and the surface of the lake covers about 80sq.Kms (Omollo, 2013).

The geography and geology of Lake Magadi is such that it is among the few places on earth where trona (a naturally occurring mineral that contains sodium carbonate compounds) can be found at the surface.

Lake Magadi occupies a trough in the Great Rift Valley of East Africa. Rainfall in and around the Rift Valley drains underground and is heated geothermally.

The hot water dissolves chemical compounds of sodium that occur in the underground rock strata and the solution comes to the surface in the form of hot, mildly alkaline springs which can be found all around the edge of the lake.

Magadi's high temperatures and long sunny days cause the solution to concentrate by evaporation eventually giving rise to more trona. Thus, the trona deposit in Lake Magadi is constantly renewing itself by natural means.

At Tata Chemical’s Magadi, trona (Naturally-occurring Sodium sequicarbonate) is obtained from the lake by dredgers set up at different locations on the lake. The trona crystals form a crust about 40m thick at Lake Magadi.

Mapping of the volumes of trona at Lake Magadi has been done by geologists working in the company but the lifespan of the mine could not be determined. This is because mined trona is able to regenerate after about 10 years to the original volume. It was also noted that the amount of trona currently is more than it was initially in 1911 when mining began.

Soda ash manufacturing
At Tata Chemicals Magadi's manufacturing facility, soda ash is obtained by washing and calcining trona, a naturally occurring form of sodium sesquicarbonate, extracted from Lake Magadi in Kenya.

The alkali deposits at Lake Magadi exist as solid trona crystals with interstitial saturated alkaline liquor. The sodium sesquicarbonate crystals are crushed, slurried and pumped to the washery plant or dewatering tower by use of dredgers.

At the washery plant, washing and blending is carried out to achieve required specifications. As a final stage in the washery, the interstitial liquor is displaced by processed water to drop the sodium chloride level associated with the liquor from 11.5 per cent to around 0.33 per cent.

The crushed refined soda (CRS) is then conveyed to the calciner plant. Here it is fed into two large rotary kilns where the main chemical reaction takes place. The CRS is loaded in the rotary kiln and a continuous fl ........