{"id":17877,"date":"2026-04-19T16:46:24","date_gmt":"2026-04-19T11:16:24","guid":{"rendered":"https:\/\/aluminiummagazine.com\/mag\/?p=17877"},"modified":"2026-04-19T16:46:25","modified_gmt":"2026-04-19T11:16:25","slug":"sodium-aluminum-fluoride-cryolite-smelting","status":"publish","type":"post","link":"https:\/\/aluminiummagazine.com\/mag\/aluminium\/compounds\/sodium-aluminum-fluoride-cryolite-smelting.html","title":{"rendered":"Sodium Aluminium Fluoride (Na\u2083AlF\u2086): Technical Guide to Cryolite"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Sodium aluminium fluoride, universally known by its mineral name <strong>cryolite<\/strong>, is a strategically important compound. Its high\u2011temperature properties govern the economics of aluminium metal production. It appears as glassy, white, or colorless chunks, and its role in the Hall\u2011H\u00e9roult smelting process makes it one of the most manufactured inorganic compounds on Earth.<\/p>\n\n\n\n<div style=\"height:50px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">1. <strong>Basic Identification<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Chemical Formula:<\/strong> Na\u2083AlF\u2086<\/li>\n\n\n\n<li><strong>Alternative Names:<\/strong> Cryolite, sodium hexafluoroaluminate<\/li>\n\n\n\n<li><strong>Molecular Weight:<\/strong> 209.94\u202fg\/mol<\/li>\n\n\n\n<li><strong>CAS Number:<\/strong> 13775-53-6 (synthetic); 15096-52-3 (mineral)<\/li>\n\n\n\n<li><strong>Appearance:<\/strong> Glassy, colorless to white solid lumps or fine white powder<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">2. <strong>Physical Properties<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Property<\/th><th class=\"has-text-align-center\" data-align=\"center\">Sodium Aluminum Fluoride (Cryolite)<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Melting Point<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">1012\u202f\u00b0C (1853\u202f\u00b0F)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Boiling Point<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">~1200\u202f\u00b0C (decomposes and fumes)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Density<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">2.90\u202fg\/cm\u00b3<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Refractive Index<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">1.338 (very close to water: 1.333)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Solubility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">0.04\u202fg\/100\u202fmL water; soluble in strong mineral acids<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Natural or melted cryolite looks like cloudy ice or shattered glass. Because its refractive index nearly matches water, a clear chunk submerged in water becomes almost invisible.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">3. <strong>Chemical Behavior &amp; Synthesis<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">3.1 High\u2011Temperature Solvent Action<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">At room temperature, cryolite is stable. Above 1000\u202f\u00b0C in molten form, it readily dissolves aluminum oxide (Al\u2082O\u2083). This is the key to aluminum smelting: alumina normally melts at 2072\u202f\u00b0C, but in molten cryolite it dissolves like sugar in coffee at ~1000\u202f\u00b0C.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">3.2 Synthesis<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Natural cryolite was mined from a single massive quarry in Greenland, exhausted in the 1980s. Today, all industrial cryolite is synthetic:<\/p>\n\n\n\n<p class=\"has-large-font-size wp-block-paragraph\"><strong>Al(OH)\u2083 + 3 NaOH + 6 HF \u2192 Na\u2083AlF\u2086 + 6 H\u2082O<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Aluminum hydroxide is reacted with sodium hydroxide and hydrogen fluoride gas to precipitate pure cryolite.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">4. <strong>Industrial Applications<\/strong><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">4.1 Aluminum Smelting (Hall\u2011H\u00e9roult Process)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Cryolite is the electrolyte that makes aluminum production economical. It dissolves alumina at ~1000\u202f\u00b0C, allowing electrolysis to extract aluminum metal at far lower energy cost than melting pure alumina. Without synthetic cryolite, the modern aluminum industry would not exist.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4.2 Pyrotechnics &amp; Glass Making<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Glass:<\/strong> Acts as an opacifier (makes glass milky\u2011white) and lowers melting point.<\/li>\n\n\n\n<li><strong>Fireworks:<\/strong> Sodium in cryolite produces a brilliant yellow flame.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">4.3 Abrasives &amp; Historical Pesticides<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Used as a filler in bonded grinding wheels to reduce friction heat. Historically used as an insecticide (now largely replaced by safer alternatives).<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">5. <strong>Safety &amp; Hazard Management<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">GHS Symbol<\/th><th class=\"has-text-align-center\" data-align=\"center\">Meaning<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\">\u2620\ufe0f GHS06<\/td><td class=\"has-text-align-center\" data-align=\"center\">Toxic (chronic)<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\">\u2757 GHS07<\/td><td class=\"has-text-align-center\" data-align=\"center\">Harmful<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Critical Warning:<\/strong> Cryolite poses a <strong>chronic fluoride toxicity hazard<\/strong>. Long\u2011term inhalation of dust causes <strong>fluorosis<\/strong> \u2013 severe bone calcification and joint fusion.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<h3 class=\"wp-block-heading\">5.1 Health Effects<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Route of Exposure<\/th><th>Effect<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Inhalation<\/strong><\/td><td>Primary risk. Chronic exposure \u2192 fluorosis (bone distortion, calcification of ligaments, paralysis).<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Skin Contact<\/strong><\/td><td>Mild irritation. Wash off to prevent incidental ingestion.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Eye Contact<\/strong><\/td><td>Mechanical and mild chemical irritation.<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Ingestion<\/strong><\/td><td>Toxic \u2013 gastric pain, nausea, calcium metabolism disruption, cardiac arrhythmias.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">5.2 PPE<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Respiratory:<\/strong> P100 (HEPA) respirator \u2013 N95 is insufficient for daily contact.<\/li>\n\n\n\n<li><strong>Hands:<\/strong> Standard laboratory gloves.<\/li>\n\n\n\n<li><strong>Eyes:<\/strong> Tight\u2011sealing splash\/dust goggles.<\/li>\n\n\n\n<li><strong>Body:<\/strong> Coveralls to prevent dust transfer to clothing.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">5.3 First Aid<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Eyes:<\/strong> Flush with water 15+ minutes.<\/li>\n\n\n\n<li><strong>Ingestion:<\/strong> Drink milk immediately (calcium binds fluoride). <strong>Seek emergency medical attention.<\/strong><\/li>\n\n\n\n<li><strong>Inhalation:<\/strong> Remove from exposure; seek medical evaluation for chronic exposure.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">5.4 Firefighting &amp; Incompatibles<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Incompatible with strong acids<\/strong> \u2013 releases lethal hydrogen fluoride (HF) gas.<\/li>\n\n\n\n<li>Firefighting: Use media appropriate for surrounding fire; cryolite itself is not flammable.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">6. <strong>Storage &amp; Handling<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Container:<\/strong> Sealed industrial bags or plastic drums<\/li>\n\n\n\n<li><strong>Atmosphere:<\/strong> Normal air; humidity does not degrade it<\/li>\n\n\n\n<li><strong>Location:<\/strong> Dry industrial storage, isolated from strong acids<\/li>\n\n\n\n<li><strong>Disposal:<\/strong> Convert to insoluble calcium fluoride (CaF\u2082) using lime, then landfill as non\u2011hazardous<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">7. <strong>Environmental Impact<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Cryolite itself is stable, but fluoride dust run\u2011off or emissions from smelters can poison aquatic life, stunt plant growth, and harm livestock. Smelters are regulated to trap fluoride emissions.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">8. <strong>Comparison with Other Aluminum Halide Salts<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Compound<\/th><th class=\"has-text-align-center\" data-align=\"center\">Formula<\/th><th>Primary Nature<\/th><th>Primary Use<\/th><\/tr><\/thead><tbody><tr><td><strong>Sodium Aluminum Fluoride<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Na\u2083AlF\u2086<\/td><td>Stable mixed salt (cryolite)<\/td><td>Aluminum smelting electrolyte<\/td><\/tr><tr><td><strong>Aluminum Fluoride<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">AlF\u2083<\/td><td>Simple salt<\/td><td>Additive in smelting bath<\/td><\/tr><tr><td><strong>Aluminum Chloride<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">AlCl\u2083<\/td><td>Corrosive Lewis acid<\/td><td>Petrochemical catalysis<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">9. <strong>Frequently Asked Questions<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Did we really mine all natural cryolite?<\/strong><br>A: Yes. The only large deposit was in Ivigtut, Greenland, exhausted by the late 1900s. All cryolite used today is synthetic.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: Does cryolite end up in aluminum cans?<\/strong><br>A: No. Cryolite acts only as a molten solvent. The aluminum metal separates and pools at the bottom; the cryolite bath is recycled continuously.<\/p><div class=\"pai-ad\" style=\"min-height:250px;visibility:hidden;\"><span style=\"display: block; text-align: center; font-size: 10px; margin: 0 0 10px 0; color: #999999;\">Ads<\/span>\r\n<!-- Display-300x250-1 -->\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:inline-block;width:300px;height:250px\"\r\n     data-ad-client=\"ca-pub-3838168351244230\"\r\n     data-ad-slot=\"9933646018\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script><\/div>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Q: What causes fluorosis?<\/strong><br>A: The body mistakes fluoride for calcium, incorporating fluoride into bones. This causes abnormal bone growth, joint fusion, and crippling pain.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div style=\"height:75px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">10. <strong>Summary Data Sheet<\/strong><\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-center\" data-align=\"center\">Property<\/th><th class=\"has-text-align-center\" data-align=\"center\">Value<\/th><\/tr><\/thead><tbody><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Chemical Name<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Sodium Aluminum Fluoride<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Mineral Name<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Cryolite<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Formula<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Na\u2083AlF\u2086<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Appearance<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Transparent chunks or white powder<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Melting Point<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">1012\u202f\u00b0C<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Defining Trait<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Dissolves alumina at low temperature; refractive index matches water<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Primary Utility<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Electrolyte for aluminum smelting<\/td><\/tr><tr><td class=\"has-text-align-center\" data-align=\"center\"><strong>Hazard Note<\/strong><\/td><td class=\"has-text-align-center\" data-align=\"center\">Chronic fluoride toxicity (fluorosis)<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/p><script>document.addEventListener(\"DOMContentLoaded\",function(){\n        if(window.innerWidth <= 768){\n            if (\"immediate\" === \"delay\") {\n                setTimeout(function(){document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\")},0);\n            } else if (\"immediate\" === \"scroll\") {\n                window.addEventListener(\"scroll\",function(){\n                    let s=window.scrollY\/(document.body.scrollHeight-window.innerHeight);\n                    if(s>0.1){\n                        document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\");\n                    }\n                });\n            } else {\n                document.querySelectorAll(\".pai-ad\").forEach(el=>el.style.visibility=\"visible\");\n            }\n        } else {\n            document.querySelectorAll(\".pai-ad\").forEach(el=>el.remove());\n        }\n    });<\/script>","protected":false},"excerpt":{"rendered":"<p>Sodium aluminium fluoride, universally known by its mineral name cryolite, is a strategically important compound. Its high\u2011temperature properties govern the economics of aluminium metal production. It appears as glassy, white, or colorless chunks, and its role in the Hall\u2011H\u00e9roult smelting process makes it one of the most manufactured inorganic compounds on Earth. 1. Basic Identification &#8230; <a title=\"Sodium Aluminium Fluoride (Na\u2083AlF\u2086): Technical Guide to Cryolite\" class=\"read-more\" href=\"https:\/\/aluminiummagazine.com\/mag\/aluminium\/compounds\/sodium-aluminum-fluoride-cryolite-smelting.html\" aria-label=\"Read more about Sodium Aluminium Fluoride (Na\u2083AlF\u2086): Technical Guide to Cryolite\">Read more<\/a><\/p>\n","protected":false},"author":12,"featured_media":18023,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4155],"tags":[4141,4142],"class_list":["post-17877","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-compounds","tag-aluminium-compounds","tag-aluminum-formula"],"_links":{"self":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts\/17877","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/comments?post=17877"}],"version-history":[{"count":0,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/posts\/17877\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/media\/18023"}],"wp:attachment":[{"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/media?parent=17877"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/categories?post=17877"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aluminiummagazine.com\/mag\/wp-json\/wp\/v2\/tags?post=17877"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}