Potash basics

Muriate of potash (MOP) or potassium chloride, to be more accurate, is derived from sylvinite ore. The MOP content in sylvinite is usually around 30 per cent, with sodium chloride (NaCl or rock salt) accounting for 65 per cent and the balance consisting of various insoluble clays.

MOP manufacture basically involves extracting the ore from underground mines and breaking it into smaller particles for further enrichment to separate the MOP from NaCl.

This is done by exploiting the differential solubility of both salts in a brine solution containing 70 per cent NaCl and 30 per cent MOP. The ore is leached with brine at about 115 degree Celsius. Since the brine is already saturated with NaCl, it leads to the separation and eventual crystallisation of MOP on controlled cooling of the solution to 35 degrees.

While sylvinite ore deposits are formed from evaporated sea water, they – as luck would have it – occur in large concentrations only at a few places in the world. An estimated 46.3 per cent of the reserves are in Canada, followed by Russia (at 34.7 per cent), Belarus (7.9), Brazil (3.2), China (2.2), Germany (1.6) and the US (1.4).

Uralkali (including Silvinit) alone has a total resource base of 8.75 billion tonnes of ore. Taking 3.5 to four tonnes of ore for every tonne of MOP, it is equivalent to some 2.2 billion tonnes of the latter – enough for 150 years or more of current production.

Uralkali claims its basic production cost, at $61 a tonne, to be half that of the world's biggest MOP company – Canada's Potash Corporation of Saskatchewan. “It is because all our mines are in the same area, which gives us economies of scale. Moreover, we have to drill only up to 400-440 metres, whereas the depths are 800-1,000 metres in Canada and 1,300 metres for EuroChem's mines in Volgograd,” noted Mr Vladislav Baumgertner, CEO of Uralkali.

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