Salt Michel Dumont Although dietary intake can vary for people from various countries, on average an adult’s total salt intake should be The author is with the Minerals and Metals Sector, no more than 6 g per day and a child’s no more than 4 g. Natural Resources Canada. The average person’s diet incorporates at least 9 g per day. Telephone: 613-995-2917 Dietary sodium is measured in milligrams (mg). The most E-mail: [email protected] common form of sodium used is table salt, which is 40% sodium. One teaspoon of table salt contains 2300 mg of sodium. HIGHLIGHTS The salt markets in developed regions such as North • Salt is critical to human and animal health. In insuffi- America and Western Europe are both stable and mature. cient quantities, our muscles won’t contract, our blood The main consuming regions are North America, Asia and won’t circulate, our food won’t digest, and our hearts the Middle East, and Western Europe. World salt consump- won’t beat. tion is on the rise, mainly in response to increasing demand in Southeast Asia and other developing nations. China is • Due to severe North American winter (2007-08) weather the world’s leading producer of synthetic soda ash (source: conditions, 2008 data indicate Canadian shipments of U.S. Geological Survey [USGS] 2006 salt review), which salt increased by 18.4% (or 2.2 Mt) to 14.2 Mt valued at uses large quantities of salt as feedstock, and many of $537.8 million. China’s salt operations have not been able to keep up with the strong demand created by the rise in soda ash • Preliminary 2008 Canadian data indicate total salt production. exports of 4.9 Mt (valued at $121.2 million), of which 99.6% was exported to the United States. Canada, like many countries, extracts, processes, con- sumes, exports, and imports salt. Canada has a vast terri- • Sifto Canada Inc., located in Goderich, Ontario (a sub- tory with many known deposits and significant geological sidiary of Compass Minerals International Inc.), potential for new discoveries. Known salt areas are cur- expanded capacity by 750 000 short tons (st) resulting in rently exploited by a small number of companies that are a total mine annual capacity of 7.25 million st. An addi- large players in the industry. Most of the salt is useed for tional 1 million st of annual capacity is scheduled to be de-icing, chemical production, and domestic (e.g., table, completed by 2010. food-grade, livestock feed) consumption. • Consequent to growing demand from the Chinese chem- Major Canadian salt deposits are found in Nova Scotia, ical industry, global demand is expected to grow at an New Brunswick, Quebec, Ontario, Manitoba, Saskatch- average of 3%/y, reaching over 300 Mt by 2012. ewan, and Alberta. Since similar geological conditions are necessary, many salt deposits have been discovered while exploring for oil and gas and potash. The largest deposits are in western Canada, followed by Ontario and the Atlan- INTRODUCTION tic provinces. In western Canada, the salt beds extend from the Northwest Territories down through Alberta, Saskatch- Salt (i.e., sodium chloride) is such a common part of our ewan, and into Manitoba. This immense deposit, averaging everyday lives that we rarely think of it as a natural 122 m (400 ft) in thickness and covering an area of resource that must be discovered, boiled/evaporated or approximately 390 000 km2 (150 000 square miles), con- mined, processed, marketed, and consumed. Each human tains more than one million billion tonnes of salt. being contains about 113 g of salt. With insufficient quanti- ties, our muscles won’t contract, our blood won’t circulate, In Ontario, salt is found along the shores of Lake Huron our food won’t digest, and our hearts won’t beat. The same and Lake Erie. This deposit is part of the known Michigan is true for livestock; therefore, salt is critical to human and Basin and is a saucer-shaped formation underlying part of animal health. Michigan, part of Ohio, and lakes Huron and Erie. 39.2 CANADIAN MINERALS YEARBOOK, 2008 In Prince Edward Island, a rock salt deposit of undeter- Canada also imports salt. Preliminary data (Table 1) show mined size was encountered at a depth of over 4200 m that Canada imported 1.9 Mt in 2008 (valued at $73.6 mil- under Hillsborough Bay on the southern side of the island. lion), mostly from the United States (61.0%) and Mexico Brine springs, usually indicative of salt deposits, have been (22.3%). found in Newfoundland and Labrador and in British Columbia. Production in most provinces is by two main methods of extraction (i.e., underground room-and-pillar CONSUMPTION mining and brining). Recovery as a co-product of potash mining is also practised. Of the millions of tonnes of dry salt produced annually in North America, a very small percentage finds its way to In the Atlantic provinces, large, thick deposits have been family dining tables either in commercially processed found underlying New Brunswick, Nova Scotia, part foods, in home preparations, or in the salt shaker. Globally, of Newfoundland and Labrador, and even the Gulf of the largest markets for salt are for use as brine and dry salt St. Lawrence. These deposits occurred in various geologic in the chemical industry. Directly or indirectly, salt plays a eras and all of them are the remains of ancient inland seas. part in the manufacture of a seemingly endless list of chem- The shorelines of these ancient seas, which outline the icals and chemical products. On average, chemical raw edges of the salt beds, often indicate the presence of oil, materials represent 60% of world salt consumption, fol- gas, and coal deposits. lowed by table salt (20%) and road de-icing salt (10%); the remaining 10% is used in animal feed and water treatment. Major salt deposits and dry salt production in North America can be viewed on the Internet at www.saltinstitute. Consumption patterns differ in North America. On a per- org/images/map.pdf. capita basis, Canada is the largest consumer of salt in the world, and this is due mainly to its winter conditions. Can- Environmentally, the continued use of road salt in Canada ada’s per-capita consumption of salt has been estimated at is an issue. In April 2004, Environment Canada issued a over 360 kg per person. Most of the salt is used as a de- Code of Practice for the Environmental Management of icing agent in Ontario, Quebec, and Atlantic Canada. Road Salts. The Code applies to any organization that uses Roughly 90-95% of Canada’s apparent domestic consump- more than 500 t/y of road salts. tion (source: Canadian Salt Institute) is for chemical and de-icing purposes. The remainder is used for water condi- tioning, food processing, fisheries, and other industrial PRODUCTION AND TRADE uses. Salt is a widespread, low-value, bulk commodity. It is rela- Salt consumption details provided by the USGS may well tively easy to extract, and transportation represents a sig- reflect North American consumption patterns. In 2007, the nificant proportion of the total delivered price. Many global U.S. distribution of salt (source: USGS) by major end use markets are served by neighbouring salt-producing coun- was for: chemicals (40%); ice control (39%); distributors tries; therefore, long-distance trade is limited (Table 1). (grocery, other wholesalers and retailers) (8%); general Nevertheless, even though both Canada and the United industrial (3%); agricultural (3%); food processing (3%); States produce salt, some regions on both sides of the bor- primary water treatment (2%); and other uses (2%). der still rely, for economic reasons and convenience of supply, on large quantities of imports. The U.S. Salt Institute’s web site provides an explanation of the many uses of salt. It can be found at www. In 2007, total estimated world production (source: USGS) saltinstitute.org/16.html. decreased to 257 Mt from the revised 262 Mt in 2006. The industrial chemicals industry (source: Natural Resour- Canada (source: USGS 2007 salt review) remained the fifth ces Canada) uses salt in the manufacture of chlor-alkali largest producer of salt (Table 3) in 2007. Preliminary 2008 such as caustic soda (sodium hydroxide), chlorine, and data indicate that Canadian salt shipments were valued at sodium chlorate. Salt for caustic soda and chlorine plants $537.9 million (14.2 Mt), a $94.9 million increase from the (i.e., facilities) in Canada is obtained from on-site brining 12.0 Mt shipped in 2007. This 2008 value reflects the and natural brines. Other plants use mined rock salt or cyclical production level from year to year in response to imported solar or evaporated salt. The chlor-alkali industry winter conditions since 1988 (Table 2). is by far the largest segment of the chemical sector that uses salt. Other industrial chemical production that requires Preliminary 2008 data (Table 1) also indicate that Canada significant use of salt includes sodium bicarbonate, sodium exported a total of 4.9 Mt (valued at $121.2 million), of chlorite, sodium hypochlorite, sodium carbonate (soda which 99.6% was exported to the United States (valued at ash), and calcium chloride. For example, salt goes into the $87.4 million). With exports of almost 4.8 Mt to the United production of chlorine and into the manufacture of soda States in 2007, Canada was that country’s leading source of ash; in turn, these two products are used in the processing salt imports, accounting for about 49% of its total imports or manufacture of a wide variety of end products ranging (source: USGS).