Eppawala Rock Phosphate Deposit and Processing Plant

Eppawala Rock Phosphate 

Location

Grama Niladhari administrative division in North Central Province, Sri Lanka. It forms part of the Thalawa Divisional Secretariat within the Anuradhapura District. It is situated around 20 kilometers south of the ancient city of Anuradhapura and 150 kilometers north east of Sri Lankan capital Colombo

History

Before finding the Eppawala appetite deposit from Geological survey and mines Bauer the   appetite crystals were hanged in the cart as a counterpart. By seeing that they have found the deposit. Seven mountains were located there. The Lanka Phosphate limited was established in 1971.Before 1980 baller mills have used for grinding.In 1980 Roller mills were introduced to the process.

Geology and mineralogy

The appetite bearing crystalline limestone (carbonatite) is well exposed and the surrounding country rock consist of granitic gneisses , charnockites , marbles ,biotite gneisses and thin bands of quartzite of the highland series. Each block consists of a “leached zone” (appetite, in a matrix of iron oxides) at the top, rich in appetite. This zone extend downwards to a depth of around 60m and rests on fresh carbonatite with appetite, magnetite and spinel. The average P2O5 is 35% , at times higher , for the phosphate ore rich ore.Rock phosphate also contains CaF2 or CaCl2 and the chemical formula can be written Ca5(PO4)3Cl or 3Ca3(PO4)2.Ca(F,Cl)2.
The appetite occurs in two ways, 
  • As a constituent of acid igneous rocks
  • In pegmatite

About deposit

The carbonatite complex consists of six elevated hill rocks with a general elevation of 60m above the general level of the surrounding country. This has igneous type origin. Geologist believed that marble rock is present beneath the appetite deposit. The deposit goes up to 50ft beneath from the earth surface. Also geologists has estimated 60 million tons of appetite present in the deposit and that will be enough for another 1500yrs if the process happening from this speed rate.Chloro appetite, Fluoro appetite and hydroxo appetite are present in Eppawala Rock phosphate (EPR).It is considered that due to presence of above three forms of appetite the solubility of EPR is very low. It is not suitable for short term cultivations. Only suitable for long term crops like tea, rubber, coconut etc.

Processing

In the extraction they simply removed the carbonatite overburden and take the apatite bearing rocks

  • For screening used gravity separators for separate particle sizes
  • Sorting is doing from the visual appearance. Less coated appetites are send to the crushing
  • Crushing is done using jaw crusher
  • Roller mills are using for grinding.


There is a small laboratory in Lanka phosphate limited. In their P2O5 content is testing. Produce 210 tons per day. Two types of raw materials producing. They are,

  • HERP (High grade Eppawala Rock Phosphate) – 38% P2O5
  • ERP (Eppawala Rock Phosphate) – 28% P2O5

Uses

  • Raw material for fertilizer industry
  • Paint industry
  • Pharmaceutical