General Description
Finely divided white particulate dispersed in air. (Note: Exposure may occur when magnesium is burned, thermally cut, or welded upon.).
Reactivity Profile
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.
Hazard
Toxic by inhalation of fume. Upper respiratory tract irritant, and metal fume fever. Questionable carcinogen.
Potential Exposure
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.
Shipping
UN1418 Magnesium, powder or Magnesium
alloys, powder Hazard Class: 4.3; Labels: 4.3-Dangerous
when wet material, 4.2-Spontaneously combustible
materia
Incompatibilities
Violent reaction with halogens/interhalogens, chlorine trifluoride, bromine pentalfluoride; strong
acids. Phosphorus pentachloride and magnesium oxide
react with brilliant incandescence (Mellor 8:1016.
19461947). May ignite and explode when heated with
sublimed sulfur, magnesium powder, or aluminum powder
Physical properties
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.
Preparation
Magnesium
oxide(1309-48-4) 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.
Production Methods
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.
Health Hazard
Magnesium oxide fume is an
irritant of the eyes and nose.
Agricultural Uses
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.
Pharmaceutical Applications
Magnesium oxide(1309-48-4) 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.
Industrial uses
Magnesium oxide (MgO,1309-48-4) 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.
Clinical Use
U.S. Pharmacopoeia (USP)-grade caustic-calcined magnesia can be used in pharmaceutical applications. In the food industry, caustic-calcined magnesia is used in sugar refining for neutralization of raw cane and beet juices and to reduce scaling in juice heaters, evaporators, juice lines, and other equipment.
Safety
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.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit. Thesymptoms of metal fume fever may be delayed for 4°12 hfollowing exposure: it may last less than 36 h.Note to physician: In case of fume inhalation, treat for pulmonary edema. Give prednisone or other corticosteroidorally to reduce tissue response to fume. Positive-pressureventilation may be necessary. Treat metal fume fever withbed rest, analgesics, and antipyretics.
storage
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.
Regulatory Status
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.
