Магния оксид

Описание

Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral, often found as a powder, which occurs naturally as periclase and is a source of magnesium . It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2? ions held together by ionic bonding. Magnesium oxide is only very slightly soluble in water but in aqueous media combines quickly with water to form magnesium hydroxide. The majority of magnesium oxide produced today is obtained from the calcination of naturally occurring minerals, magnesite, MgCO3, being the most common. Other important sources of magnesium oxide are seawater, underground deposits of brine and deep salt beds from which magnesium hydroxide [Mg(OH)2] is processed. In medicine, magnesium oxide can be used as an antacid to relieve heartburn, sour stomach, or acid indigestion, as a laxative for short-term, rapid emptying of the bowel (before surgery, for example) and as a mineral supplement used to prevent and treat low amounts of magnesium in the blood. Besides, magnesium oxide also has many nonmedicinal uses. Caustic calcined magnesia is used in a wide range of industrial applications e.g. plastics, rubber, adhesives and acid neutralization. Magnesium oxide with lower chemical activity can be used for fertilizers and animal feed. Dead-burned magnesia and finally fused magnesia can be used for a variety of refractory and electrical applications e.g. furnace lining, crucibles and fireproofing boarding.

Химические свойства

Magnesium oxide forms a finely divided white particulate dispersed in air.

Физические свойства

White ceramics, with a high reflective index in the visible and near-UV regions. Used as linings in steel furnaces. Crucible container for fluoride melts. Very slowly soluble in pure water but soluble in diluted strong mineral acids. Exhibits outstanding corrosion resistance in liquid metals Mg, Li, and Na. Readily attacked by molten metals Be, Si, Ti, Zr, Nb, and Ta. MgO reacts with water, CO₂ , and diluted acids. Maximum service temperature 2400°C. Transmittance of 80% and n=1.75 in IR region 7 to 300 μm.

Использование

Magnesium Oxide is a source of magnesium which functions as a nutrient and dietary supplement. it exists as a bulky white powder termed light magnesium oxide or as a dense white powder known as heavy magnesium oxide. it is practically insoluble in water and is insoluble in alcohol.

Определение

Two forms are produced, one a light, fluffy material prepared by a relatively low-temperature dehydration of the hydroxide, the other a dense material made by high-temperature furnacing of the oxide after it has been formed from the carbonate or hydroxide.

Подготовка

Magnesium oxide is easily formed by burning magnesium metal ribbon. Mg oxidizes and emits a bright white light, rich in ultraviolet and hard to extinguish. Extreme care must be taken if MgO is to be prepared by this method. Magnesia is a white solid mineral that occurs naturally as “Periclase” and is used as a source of magnesium metal. Magnesium oxide is hygroscopic in nature and care must be taken to protect it from moisture. It reacts with water and forms the hydroxide:
MgO＋H2O→Mg(OH)2
However, this reaction can be reversed by heating it to remove moisture.

Методы производства

Magnesium oxide occurs naturally as the mineral periclase. It can be manufactured by many processes. Limestone containing the mineral dolomite is calcinated at high temperatures to produce dolime, which then reacts with magnesium chloride-rich sea water to produce magnesium hydroxide and calcium chloride.The magnesium hydroxide is then calcinated to produce magnesium oxide and water. In another process, mined magnesite (MgCO₃) is calcinated to produce magnesium oxide and carbon dioxide. Purification methods include crushing and size separation, heavymedia heavymedia separation, and froth flotation. Producing magnesium oxide from sea water is a process that involves heating magnesium chloride concentrated brine from the Dead Sea. The magnesium chloride decomposes into magnesium oxide and hydrochloric acid.Magnesium oxide may also be produced by the thermal decomposition of magnesium chloride, magnesium sulfate, magnesium sulfite, nesquehonite, and the basic carbonate 5MgO·4CO₂·5H₂O. Purification of the magnesium oxide produced through thermal degradation is carried out by filtration or sedimentation.

Общее описание

Finely divided white particulate dispersed in air. (Note: Exposure may occur when magnesium is burned, thermally cut, or welded upon.).

Профиль реактивности

Phosphorus pentachloride and magnesium oxide react with brilliant incandescence [Mellor 8:1016. 1946-1947]. The oxide is incompatible with interhalogens such as bromine pentafluoride, etc.

Опасность

Toxic by inhalation of fume. Upper respiratory tract irritant, and metal fume fever. Questionable carcinogen.

Угроза здоровью

Magnesium oxide fume is an irritant of the eyes and nose.

Фармацевтические приложения

Magnesium oxide is used as an alkaline diluent in solid-dosage forms to modify the pH of tablets.It can be added to solid-dosage forms to bind excess water and keep the granulation dry. In combination with silica, magnesium oxide can be used as an auxiliary glidant. It is also used as a food additive and as an antacid, either alone or in conjunction with aluminum hydroxide. Magnesium oxide is additionally used as an osmotic laxative and a magnesium supplement to treat deficiency states.

Сельскохозяйственное использование

Magnesia is a term used for magnesium oxide (MgO). Magnesite, caustic-calcium magnesite, dead-burned magnesite and synthetic magnesite are also loosely used as synonyms for magnesia. Magnesium oxide is used in agricultural applications for animal feed and fertilizer; in the United States, these applications represent about 20%–25% of the total annual caustic-calcined magnesia shipment. Magnesium serves as a structural part of the chlorophyll molecule, a compound necessary for plant photosynthesis. Without sufficient magnesium, either from the soil or from fertilizer application, plants can die. Grazing ruminants, such as cattle and sheep, require magnesium in their diet to guard ag ainst hypomagnesia, also known as grass tetany, a potentially fatal disease.

Промышленное использование

Magnesium oxide (MgO) is a synthetic mineralproduced in electric arc furnaces or by sinteringof amorphous powder (periclase). Refractoryapplications consume a large quantity of MgO.Both brick and shapes are fabricated at leastpartially of sintered grain for use primarily inthe metal-processing industries. Heating unitinsulation is another major application for periclase.Principal advantages of periclase are itsthermal conductivity and electrical resistivity atelevated temperatures.
Specialty crucibles and shapes also are fabricatedfrom MgO. These are used in pyrometallurgicaland other purifying processes for specialtymetals. Both slip-casting and pressingtechniques are employed to manufactureshapes.
Thermocouple insulation comprises stillanother outlet for periclase. Since most of thesego into nuclear applications, a high-purity productis required. MgO is also an important glazeconstituent.
Single crystals of MgO have received attentionbecause of their use in ductile ceramic studies.Extreme purity is required in this area. Periclasewindows are also of potential interest ininfrared applications because of their transmissioncharacteristics.

Профиль безопасности

Inhalation of the fumes can produce a febrile reaction and leucocytosis in humans. Questionable carcinogen with experimental tumorigenic data. Violent reaction or ignition in contact with interhalogens (e.g., bromine pentafluoride, chlorine trifluoride), Incandescent reaction with phosphorus pentachloride. See also MAGNESIUM COMPOUNDS.

Безопасность

Magnesium oxide is widely used in oral formulations as an excipient and as a therapeutic agent. Therapeutically, 250–500mg is administered orally as an antacid and 2–5g as an osmotic laxative. Magnesium oxide is generally regarded as a nontoxic material when employed as an excipient, although adverse effects, due to its laxative action, may occur if high doses are ingested orally.

Возможный контакт

Used in oil refining, pulp and paper mills; tire manufacturing; in the manufacture of refractory crucibles; fire bricks; magnesia cements and boiler scale compounds. Exposure may occur when magnesium is burned, thermally cut, or welded upon.

хранилище

Magnesium oxide is stable at normal temperatures and pressures. However, it forms magnesium hydroxide in the presence of water. Magnesium oxide is hygroscopic and rapidly absorbs water and carbon dioxide on exposure to the air, the light form more readily than the heavy form.
The bulk material should be stored in an airtight container in a cool, dry place.

Перевозки

UN1418 Magnesium, powder or Magnesium alloys, powder Hazard Class: 4.3; Labels: 4.3-Dangerous when wet material, 4.2-Spontaneously combustible materia

Несовместимости

Violent reaction with halogens/interhalogens, chlorine trifluoride, bromine pentalfluoride; strong acids. Phosphorus pentachloride and magnesium oxide react with brilliant incandescence (Mellor 8:1016. 1946
1947). May ignite and explode when heated with sublimed sulfur, magnesium powder, or aluminum powder

Регуляторный статус

GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (oral capsules, tablets, and buccal). Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-medicinal Ingredients.

использованная литература

1. https://en.wikipedia.org/wiki/Magnesium_oxide
2. https://www.chemistryworld.com/podcasts/magnesium-oxide/7645.article
3. https://pubchem.ncbi.nlm.nih.gov/compound/magnesium_oxide#section=Top
4. http://www.azom.com/article.aspx?ArticleID=54
5. https://medlineplus.gov/druginfo/meds/a601074.html
6. https://www.merriam-webster.com/dictionary/magnesium%20oxide
7. http://www.webmd.com/drugs/2/drug-3954/magnesium-oxide-oral/details