The salt field operation at Walvis Bay was established in 1964 and is one of the largest solar evaporation facilities in Africa, processing 24 million tons of sea water to produce in excess of 700 000 tons of high-quality salt per annum. The bulk of the salt produced by Walvis Bay Salt Refiners is exported to markets in Southern and West Africa, where it is used mainly by the chlor alkali industry for the production of chlorine and caustic soda, by the agricultural sector as a feed supplement, as well as a feedstock for refined table salt for human consumption.
The Walvis Bay salt field operates within a Ramsar Site area and forms an important element in the conservation of birdlife in the area. In fact, the salt pond system, together with the adjacent Walvis Bay Estuary, has been identified as one of the important wetlands of Africa. Nutrients found in the ponds sustain a variety of wetland birds such as flamingos and other waders. Up to 120 000 birds at a time have been viewed at the salt field and more than 60 different species have been identified. As a supplementary operation to salt production, Walvis Bay Salt Refiners produces high-quality oysters on a commercial basis-making use of the high flow of sea water into the salt evaporation ponds.
Oysters in the Walvis Bay oyster beds feed on plankton-rich sea water and reach market size in only a few months. Because oysters need to be alive when they reach their destinations, they are flown to increasing numbers of customers, particularly restaurant owners, throughout Southern Africa. The Salt & Chemicals salt production process is based on the solar evaporation of sea water to produce 99,4% pure sodium chloride (NaCl) on dry mass basis. Sea water off Walvis Bay, which is the only raw material, contains a 3,5% concentration of salts with 2,9% sodium chloride.
The water is pumped from a natural lagoon at a rate of 240m3 per minute into a series of 4 pre-evaporation ponds and then through a series of 4 concentration ponds. The total operation covers an area of 4000 ha. Stimulated by wind and sun the brine (concentrated salt water) salinity content gradually increases until it reaches 25%, at which point it is pumped into crystallization ponds, each with a surface area of around 20 ha. The salt then crystallizes to form a layer of crystals on the various crystallizer pavements. During the evaporation process, brine depths and densities are controlled to ensure that the maximum number of unwanted chemical impurities are precipitated before they enter the crystallizers.
A similar monitoring program is adopted to control the depth and density of crystallization ponds, to achieve optimum efficiency levels. Performance is constantly monitored by technicians at an on-site laboratory. Once the salt crystals have grown to the required depth, the salt is removed by mechanical harvesters and transported to a wash plant. Here, the salt undergoes a process of washing, using dilute brine as the washing medium, during the wash process to remove calcium sulphate and magnesium which adheres to the salt.
The final salt solution is then dried in a centrifuge. The salt leaves the centrifuge of the wash plant and is fed onto a stacker belt and stockpiled where further draining occurs. Bulk consignments of salt are conveyed by road directly to a dedicated storage facility at the Walvis Bay harbour for loading.
Salt required by customers in bags is packed at a fully automated bagging plant according to individual bag mass requirements and incorporating specific package identification. Salt of varying crystal sizes is available according to customer needs. Salt destined for bulk shipment is transported from the bulk storage facility at the harbour by a conveyor belt and spout-trimmed into the ship's hold at the Walvis Bay dockside. Loading can take place on a 24-hour basis, seven days a week. Much of the salt is shipped to South Africa.

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