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Sodium sulfate - Wikipedia, the free encycloped,
<br />Production
<br />http://en.wikipedia.org/wiki/Sodium sulfate
<br />The world production of sodium sulfate, mostly in the form of the decahydrate amounts to approximately 5.5 to
<br />6 million tonnes annually (Mt/a). In 1985, production was 4.5 Mt/a, half from natural sources, and half from chemical
<br />production. After 2000, at a stable level until 2006, natural production had increased to 4 Mt/a, and chemical production
<br />decreased to 1.5 to 2 Mt/a, with a total of 5.5 to 6 Mt/a.[12][13][14][15] For all applications, naturally produced and
<br />chemically produced sodium sulfate are practically interchangeable.
<br />Natural sources
<br />Two thirds of the world's production of the decahydrate (Glauber's salt) is from the natural mineral form mirabilite, for
<br />example as found in lake beds in southern Saskatchewan. In 1990, Mexico and Spain were the world's main producers of
<br />natural sodium sulfate (each around 500,000 tonnes), with Russia, US and Canada around 350,000 tonnes each.[13] Natural
<br />resources are estimated as over 1 billion tonnes.[12][13]
<br />Major producers of 200,000-1,500,000 tonnes/a in 2006 include Searles Valley Minerals (California, US), Airborne
<br />Industrial Minerals (Saskatchewan, Canada), Quimica del Rey (Coahuila, Mexico), Criaderos Minerales Y Derivados and
<br />Minera de Santa Marta, also known as Grupo Crimidesa (Burgos, Spain), FMC Foret (Toledo, Spain), Sulquisa (Madrid,
<br />Spain), and in China Chengdu Sanlian Tianquan Chemical (Sichuan), Hongze Yinzhu Chemical Group (Jiangsu), Nafine
<br />Chemical Industry Group (Shanxi), and Sichuan Province Chuanmei Mirabilite (Sichuan), and Kuchuksulphat JSC (Altai
<br />Krai, Siberia, Russia).[121[141
<br />Anhydrous sodium sulfate occurs in and environments as the mineral thenardite. It slowly turns to mirabilite in damp air.
<br />Sodium sulfate is also found as glauberite, a calcium sodium sulfate mineral. Both minerals are less common than mirabilite.
<br />Chemical industry
<br />About one third of the world's sodium sulfate is produced as by-product of other processes in chemical industry. Most of this
<br />production is chemically inherent to the primary process, and only marginally economical. By effort of the industry,
<br />therefore, sodium sulfate production as by-product is declining.
<br />The most important chemical sodium sulfate production is during hydrochloric acid production, either from sodium chloride
<br />(salt) and sulfuric acid, in the Mannheim process, or from sulfur dioxide in the Hargreaves process.["]["] The resulting
<br />sodium sulfate from these processes are known as salt cake.
<br />Mannheim: 2 NaCl + H2SO4 —► 2 HCl + Na2SO4
<br />Hargreaves: 4 NaCl + 2 SO2 + 02 + 2 H2O — 4 HCl + 2 Na2SO4
<br />The second major production of sodium sulfate are the processes where surplus sulfuric acid is neutralised by sodium
<br />hydroxide, as applied on a large scale in the production of rayon. This method is also a regularly applied and convenient
<br />laboratory preparation.
<br />2 NaOH(aq) + H2SO4(aq) Na2SO4(aq) + 2 H200)
<br />Formerly, sodium sulfate was also a by-product of the manufacture of sodium dichromate, where sulfuric acid is added to
<br />sodium chromate solution forming sodium dichromate, or subsequently chromic acid. Alternatively, sodium sulfate is or was
<br />formed in the production of lithium carbonate, chelating agents, resorcinol, ascorbic acid, silica pigments, nitric acid, and
<br />phenol.["]
<br />Bulk sodium sulfate is usually purified via the decahydrate form, since the anhydrous form tends to attract iron compounds
<br />and organic compounds. The anhydrous form is easily produced from the hydrated form by gentle warming.
<br />Major sodium sulfate by-product producers of 50-80 Mt/a in 2006 include Elementis Chromium (chromium industry, Castle
<br />Hayne, NC, US), Lenzing AG (200 Mt/a, rayon industry, Lenzing, Austria), Addiseo (formerly Rhodia, methionine industry,
<br />Les Roches-Roussillon, France), Elementis (chromium industry, Stockton-on-Tees, UK), Shikoku Chemicals (Tokushima,
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