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The Staff of Life

Harvested from the sea or wrested from the earth, salt would appear to be one of the humblest commodities.

Yet the sodium it contains is a life-sustaining element. Sodium chloride is essential in the nutrition and physiological processes of all animals including man.

From long before the first written word, there are repeated references in records and stories to the importance of salt as an essential in the daily diet.

Salt has not only ensured the survival of mankind, but coloured the species food, religions, politics and superstitions. In ancient times, because of its power to preserve and purify, salt was spilled upon legal documents to symbolise enduring agreement and freedom from deceit.

Roman legionnaires who guarded the Via Solaria, one of the most famous military roads in history, received part of their pay in salt, their "salarium." From this came the modern word "salary".

To this day a good man is "worth his salt" and we take others' dramatic pronouncements "with a pinch of salt."

Many of salt's applications, including the art of tanning skins with salt, have remained almost unchanged down through the millennia. Its place in our superstitions and sayings remains entrenched.

Enshrined in the World's many cultures and a vital part of global economies, salt is as essential to life as the air we breathe and the water we drink.

New Zealand, Naturally

New Zealand is a land of striking contrasts. Seemingly endless stretches of golden sand vie for attention with snow-capped mountain ranges, magnificent glacier-fed fjords and waterways alive with salmon and trout. Our seas are hailed as offering some of the world's finest game fishing. It is this wealth of natural resources that encourages thousands of tourists to embark on a voyage of discovery each year.

Flanked by the Tasman Sea and the vast Pacific Ocean, New Zealand, as an island nation, is one of the jewels in the Earth's crown.

New Zealand's primary produce has a reputation for excellence and is in demand the world over. Internationally, consumers have declared their preference for produce with a "clean, green" pedigree.

Surely there can be no product purer, more natural or environmentally friendly than salt - pure sea water provided and evaporated by Nature, harvested and refined to perfection by Man.

Lake Grassmere

Seawater contains just over 2.5 per cent sodium chloride, together with significant amounts of other salts. Some 60,000 to 70,000 tonnes of salt are harvested from Lake Grassmere each year. Sea water is pumped into the 688 hectare main lake continuously throughout summer.

As Nature does its work and evaporation increases the sea water's strength, it is pumped into a series of concentrating ponds, where further evaporation takes place.

When the brine reaches saturation point it is transferred into crystallisation ponds during the summer months.

New Zealand's Marlborough province is renowned for receiving more than its share of sunshine. It was this meteorological feature, coupled with strong, drying Nor' Westerly winds and large areas of suitable flat land, that persuaded the late George W. Skellerup to establish his solar saltworks in 1943.

The salt crust is lifted from the bottom of the crystallisation ponds and transported to one of the two washing plants where it is washed in brine before being stacked in 20-metre high piles.

The snowy stacks of salt are something of a landmark, readily visible by day and night from the Blenheim - Christchurch highway. Salt production is highly dependent on low rainfall and evaporation, so it is necessary to hold large stockpiles of salt to counter the fluctuations in annual production.

During the refining process, the salt is rewashed, crushed, dried and screened before being packed in 25 kilo bags, or bulk bags containing 1-1.2 tonnes. Salt destined for the domestic table salt market accounts for a very small fraction of the harvest. Some of this product is iodised and processed at the Cerebos Skellerup packing plant adjacent to Lake Grassmere.

Mount Maunganui

In the early 1970s it became apparent that even with an annual output of 60,000 tonnes, Grassmere could not meet industry's growing need for salt. In 1971, at Mount Maunganui, in New Zealand's North Island, a site was chosen for a plant to process bulk salt from either Lake Grassmere or overseas. Situated adjacent to one of New Zealand's largest export ports, the Port of Tauranga, and in close proximity to key consumers such as the pulp and paper industry, the site proved ideal.

The installation of vacuum refining has allowed Dominion Salt to develop a wide range of salt grades to meet the needs of the dairy, pharmaceutical and food manufacturing industries.

During 1973 - 1974, Dominion Salt commissioned a vacuum refinery at Mount Maunganui, with a view to supplying high purity, fine salt for food products. A smaller unit was built at Lake Grassmere in 1974 - 1975. Vacuum salt is of much higher purity than solar salt and is formed by the artificial evaporation of treated pure brine in a near vacuum.

The salt is first dissolved, and then treated to purify it. The clarified brine then goes through an evaporation plant where salt crystals are formed in a super-saturated solution. The crystals are removed in a slurry, then dried. Pure Dried Vacuum salt (PDV salt) is highly versatile and can be used in a wide range of products.

As part of the vacuum process, pure salt can be separated by screening - into fine and coarse particles. Extremely fine salt is milled into a flour-like consistency for use in dairy products and baking. Pharmaceutical salt grades (BP and USP) were developed in 1977 and are made from specifically prepared, high purity brine using the vacuum process.

These premium grades are sold both nationally and internationally.

N.B. The NZ Salt Company Logo is a registered trade mark of Dominion Salt NZ Ltd

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