Magnesia Glossary

Magnesia glossary A B C D E F G H I J K  K L L M N O P R S R S T U V W Z

A

ABBRASIVE -> Brake Lining

ABSORPTION Penetration of a substance into the body of another. Absorption properties of magnesiu are important in neutralisation applications e.g. -> Magnesium Bisulphite Process. Process.

ACETIC ACID TEST -Caustic Magnesia Activity (CMA)

ACID ACCEPTOR  Substance which is capable of binding acids. The basic character of magnesia causes it widely used acid acceptor. This term describes the central magnesia property. -> Neutralisation -> Buffer

ACID BINDING -> Acid Acceptor -> Buffer

ACTIVITY Common term for the reactive capability of magnesium oxide. Its correlation with -> Specific Surface Area makes this a suitable measure.

ACTIVITY INDEX Former measure for -> Activity of magnesium oxide, expressed by its - Iodine absorption

ADSORPTION Binding of gases or liquids at or on (also inner) surface of a solid only by surface forces by chemical bonds. -> Iodine Adsorption

AGEING Test criterion especially for rubber compounds determining the change in properties (ha tensile strength, elongation at break) relative to the time of storing or stress under defi conditions (DIN 53508). Ageing properties are highly dependent on the degree of crosswhich is determined by the curing process. Magnesium oxides with selected properties positively influence curing.

-> Scorch Time. Time.

AGGLOMERATES Assemblage of powdered particles rigidly joined together. Precipitated magnesia in particular is made up of agglomerates agglomerates in the form of very small crystallites measuring as little as only a few microns. Undesired agglomerates are formed by humidity and carbon dioxide from the atmosphere if magnesia is handled incorrectly.

AGRICULTURE Large application area for magnesia, particularly as additive for fertilisers and animal nutrition, as well as for plant protection against acid rain.

ALKALINITY Common term for the alkaline reaction of caustic magnesium oxides. It is determined by acid titration or by neutralisation tests. -> Citric Acid Activity -> Caustic Magnesia Activity

AMORPHOUS MATERIAL Non-crystalline Non-crystalline solid material. Magnesia would appear to be amorphous, especially in cryptocrystalline cryptocrystalline modifications, through X-ray diffraction reveals the existence of crystalline structures.

ANTACIDS Substance counteracts excess production of stomach acid -> Pharmacy

ANTICAKING AGENT Substances (additives) which maintain the free-flowing properties of powders. Magnesium hydroxide carbonates carbonates are widely used for anti-caking purposes, e.g. in table salt.

APPARENT DENSITY LOOSE The mass of powdered or granulated materials materials (mainly g/l) loosely filled in a measuring cylinder (s. DIN 53912).

APPARENT DENSITY TAPPED The mass of powdered or granulated materials materials (mainly g/l) compacted in a tapping volumeter (s. DIN 53194)

APPARENT VOLUME Volume of a defined mass of powder, free-flowingly filled. The A.V. is a feature listed in pharmacopoeias, e.g. for pharmaceutical magnesia grades. -> Apparent Density

ASH Residue formed when e.g. magnesia paste is ignited (at 950 °C). A. represents the (ignited free) content of magnesium oxide (DIN 53658).

ATMOSPHERIC IMPACT Impact of humidity and carbon dioxide on magnesium oxide which lowers quality.

ATOMIC ADSORPTION SPECTOMETRY (AAS) Spectrometric Spectrometric method of analysis for determining the quantity of a wide range of elements, particularly particularly metals in low concentrations. concentrations. AAS may be used to determine, e.g., traces of  cadmium, copper, chromium, cobalt, nickel, lead, mercury, Arsenicic in magnesia.

B

BALL MILL Mill consisting of a horizontal cylindrical vessel in which a substance is ground by rotation with steel or ceramic balls. Used also for grinding magnesite.

BASIFICATION -> Tanning

B.E.T. SURFACE AREA -> Specific surface Area Surface area of a solid material, e.g., powder, measured from the nitrogen adsorption isotherm according to the method developed by Brunauer, Emmet and Teller.

BIG BAGS Packaging form using large bags of approx. 1 m³ volume to pack, e.g., distinct magnesia types.

BMC BMC = Bulk Moulding Compound. Polyester resin compounds made from unsaturated unsaturated polyester resins and textile glass. BMC is moulded to moulded thermosetting parts. Magnesia is used for thickening (control of viscosity) of BMC -> LUVATOL

BOWL MILL Type of mill for micronising minerals using a pendulum-like milling tool. Widely used to grind magnesite.

B. P. Abbreviation Abbreviation for British Pharmacopoeia. Pharmacopoeia.

BRAKE LININGS Lining of friction elements for brakes and clutches containing magnesia.

BRINE Salt solutions, product of -> Leaching

BROMOBUTYL RUBBER  Elastomers containing bromine. Application Application area of magnesium oxide.

BROOKFIELD VISCOSITY Viscosity data obtained by measuring with a Brookfield Viscometer having a rotating measuring device. One of its applications is to determine the viscosity of polyester resins for -> SMC

BRUCITE Magnesium containing mineral. Chemistry: Magnesium hydroxide Mg(OH)2

B. S. Abbreviation Abbreviation for British Standards

BUFFER  Mixtures of substances limiting change in pH value when acids or alkalis are added. Magnesium compounds may be constituent of a buffer mixture if a high pH-value has to be avoided. -> Neutralisation.. Neutralisation

BURNING Moderate to strong heating of solid substances to separate crystal water and for thermal decomposition. decomposition. Burning is used, e.g., to produce magnesium oxide from magnesium carbonate or magnesium hydroxide. Calcination Calcination is the more common term for B. of Magnesia. -> Burning Temperature

BURNING TEMPERATURE Choice of burning temperature influences -> Activity and -> Specific Surface Area of the magnesium oxide produced by -> Burning

BURNT MAGNESITE -> Calcined Magnesite

C

CALCINATION -> Burning

CALCINED MAGNESIA Common term for -> Magnesium oxide

CALCINED MAGNESITE Common term for magnesium oxide produced from -> Magnesite by -> Burning

CAQ Abbreviation Abbreviation for computer aided quality control.

CAUSTIC MAGNESIA Common term for caustic (low, light) calcined magnesium oxide. Shows alkaline reaction.

CAUSTIC MAGNESIA ACTIVITY (CMA) Reaction test for magnesium oxide using acetic acid. -> Alkalinity

CERAMICS Sintered material, porous or tight produced also by use of magnesia. High purity magnesia types offer interesting perspectives for new applications applications in engineering ceramics.

CHLOROPRENE RUBBER  Polymerisation Polymerisation product of chlorinated butadiene showing specific properties additional to those similar to natural rubber. Important application area for active magnesium oxide, also in paste form to prevent scorching. -> Scorch Time

CHROME TANNING -> Tanning

CITRIC ACID ACTIVITY (CAA) Reaction test for magnesium oxide using citric acid, especially for magnesium oxide for -> Transformer Steel. Steel.

CLUTCH LININGS -> Brake Linings

COATED MAGNESIA Surface treated magnesia, e.g., with stearic acid for special purposes

COLORIMETER  Instrument used for the precise measurement of intensity of a colour. Used to determine iron and manganese when analysing magnesia. A special colorimeter is used to determine the whiteness of powders. -> Leukometer

COMPLEXOMETRY Widely use analytical method applied, e.g. for volumetric determination of calcium and magnesium in magnesia, sometimes also for other elements.

COMPRESSION SET Test method for elastomers to determine the residual deformation after defined compression (DIN 53517). C. S. depends on the degree of cross-linking of the elastomer which, in turn, is influenced by the curing process. Since magnesium oxide impacts curing together with other components C. S. is used as one criterion to select the most appropriate appropriate grade of magnesium oxide.

CONTENT Content of magnesia in MgO e xpressed as percentage is defined in various ways. Very often the data relates to the ignited material, in other cases the content is given without correction for the loss on ignition.

CORROSION CONTROL -> Fuel Oil

CR RUBBER  -> Chloropren Rubber

CRUCIBLE MATERIAL Magnesia grades for producing sintered crucibles in metallurgy.

CRYPTO CRYSTALLINE Virtually -> Amorphous Materials containing very small crystallites. The crystalline structure can only be proven by x-ray diffraction.

CRYSTALLINE A solid in which the atoms or molecules are arranged in a regular lattice -> Single Crystals

D

DAB Abbreviation Abbreviation for Deutsches Arzneibuch, the German pharmacopoeia. pharmacopoeia.

DEAD-BURNT MAGNESIA Magnesia calcined above 1,600 °C under vast loss of activity. -> Activity -> Burning -> Sinter

DENSITY Mass of unit volume of a substance expressed in g/cm³, often also in g/ml. Density of magnesia is generally given as -> Apparent Density, Loose -> Apparent Density, Tapped

DIFFERENTIAL THERMAL ANALYSIS (DTA) -> Thermo Analysis

DIN Symbol for "DIN Deutsches Institut für Normung", the German standards authority. Original Original abbreviation abbreviation for "Deutsche Industrie Norm". For magnesia the standards DIN 53912 (Apparent Density Loose), DIN 53194 (Apparent Density Tapped), and DIN 53580 (Wet Screen Residue) are of importance.

DOLOMITE

Magnesium containing mineral, Chemistry MgCO 3 · CaCO3.

E

ELASTICITY MODULUS -> Modulus

ELASTOMERS Natural or synthetic polymers with elastic properties after cross-linking. Magnesium oxide is used mainly in polychloroprene rubber, halobutyl rubber, chlorosulphonated polyethylene and fluor rubber.

ELECTRIC ARC FURNACE Electric furnace in which the heat for melting magnesium oxide (approx. 3,000 °C) is produced by an electric arc between carbon electrodes, or between a carbon electrode and the furnace charge.

ELECTRO FUSED MAGNESIA -> Fused Magnesia

ELONGATION AT BREAK Elongation of material (normally expressed as percentage percentage of its original length) on breaking. This mechanical property of cured elastomers is determined by the extent of cross-linking. cross-linking. Since the curing process is influenced by the added agents (e.g. magnesium oxide) it is essential that these are carefully selected. For magnesium oxide activity and particle size distribution are of special importance.

E. P. Abbreviation Abbreviation for European Pharmacopoeia. Pharmacopoeia.

EPSOM SALT Magnesium sulphate, Chemistry: MgSO4 · 7H2O.

F

FLAME RETARDANT FURNISHING Preparation Preparation of material with additives or fillers which prevent or retard spreading of flames in case of fire. Special magnesium hydroxide types are used for this application. They are applied as functional fillers in polymers in high concentrations concentrations

FLUOR RUBBER  Elastic high polymers formed by copolymerisation copolymerisation of vinylidene fluoride and chlorofluoroethylene (CFM-type) of copolymerisation or terpolymerisation terpolymerisation with other unsaturated fluorohydrocarbons (FKM-type). Application area of magnesium oxide with controlled medium activity.

FOODSTUFFS Magnesia is added to a large number of food preparations. German law allows the use of  magnesium carbonate carbonate on a general scale while magnesium oxide and magnesium hydroxide are limited to certain foodstuff applications.

FORSTERITE A silicate of magnesium, Mg 2SiO4. With defined electrical insulation properties it represents an important layer on transformer steel sheets. The layer is formed by the reaction of magnesium

oxide with the silicone of the steel during annealing.

FRICTION LININGS -> Brake Linings

FRITS Porous material formed by sintering inorganic powders such as magnesium oxide and carbonate.

FUEL OIL Hydrocarbon mixture mixture used as fuel. The sulphur contained in the mixture produces acidic gases on combustion which may be neutralised by magnesium oxide to minimise corrosion.

FUSED MAGNESIA Magnesia produced by fusion in an electrical arc furnace at a temperature of approx. 3,000°C.

G

GEFAHRSTOFF-VERORDNUNG Regulation of the German Ministry of Employment and Social Services concerning protection of  workers and consumers from hazardous material.

GLASS INDUSTRY Magnesia is used in the manufacture of a number of special types of glass as part of the glass charge.

GRANULATES Form of magnesia with dust-free properties formed by binding with appropriate agent. Suitable therefore for pneumatic pumping and automatic dosing.

GRAS "Generally Recognised As Safe". Term of F.D.A. (US Food and Drug Administration). Administration).

GRAVIMETRIC ANALYSIS Analytical method used for determination of a substance by -> Precipitation very often followed by weighing the precipitate. Used, e.g., to determine the sulphate content of magnesia.

H

HEAVY METALS General term of metals with a density of (normally) more than 4.6 g/cm 3. Usually taken to mean lead, mercury, cadmium, zinc and copper, although there is no reason for this limited choice. For pharmaceutical pharmaceutical qualities summarising tests are used. The results are given as lead.

HIGHLY ACTIVE MAGNESIUM OXIDE Magnesium oxide with large surface area -> Activity

HUMIDITY

Water adsorbed on material which may be removed by drying under a temperature normally slightly above 100°C. -> Loss on Drying. Drying. An important quality feature for many magnesia applications.

HYDRATISATION Absorption of and reaction with water. For magnesium oxide it is a feature of the residual reaction capability after calcination.

HYDROCHLORIC ACID INSOLUBLES Quality criterion for magnesia giving information on content of impurities, such as silica or gypsum. As gypsum occurs rarely in magnesia the H.A.I. generally concern silica.

HYDRO MAGNESITE Magnesium containing mineral. Chemistry: 3MgCO3 · Mg(OH)2 · 3H2O

I

INVESTIGATION INVESTIGATION METHODS Laboratory methods used to characterise properties of materials. A distinction could be made between physical and chemical investigation investigation methods. Application-oriented methods are applied in addition for magnesia, e.g., test for -> Setting Capabilit Capability y and -> O S S T

IODINE ADSORPTION Value indicating the -> Specific Surface Area and consequently the -> Activity of powders such as magnesium oxide. It is normally given in mg I/g MgO. The range of commercially used magnesium oxides extends from 0 to 200 mg I/g MgO. This method is not in use anymore, because CCl4 is used for its determination. CCl4 is internationally banned.

I.S.O. Abbreviation Abbreviation for International Organisation Organisation for Standardisation. I.S.O. standards, e.g. for screens are also applied to magnesia.

J

JET MILL High efficiency fluidised bed mill. The kinetic energy of opposed gas jets is used for the super fine grinding of dry powders down to particle sizes in the micron and submicron range.

K

KIESERITE Magnesium containing mineral. Chemistry: Magnesium Sulphate MgSO 4 · H2O

L

LASER DIFFRACTION Analytical method to determine

-> Particle Size Distribution. Distribution. It is based on the phenomenon discovered by Fraunhofer, that light is scattered by particles in a characteristic characteristic manner (Frauenhofer's rings). Diameter and intensity of the diffraction rings depend on size and concentration concentration of particles.

LAXATIVES Traditional application area for magnesia.

LEACHING Wet extraction of, e.g., magnesium containing minerals by dissolving in hydrochloric acid as preparation preparation for -> Pyrohydrolysis

LEUKOMETER  Old term used for an instrument to determine "whiteness". -> Colorimeter

LOSS ON DRYING Weight-loss by drying, normally 2 - 4 hours at 105 - 110°C.

LOI Abbreviation Abbreviation for -> Loss on Ignition but also for Limiting Oxygen Index, the oxygen content of an atmosphere necessary to combust a material, e.g., a polymer.

LOSS ON IGNITION Weight loss of, e.g., magnesium oxide when ignited, normally 2 hours at 950°C. It is caused by adsorbed and absorbed water and carbon dioxides (DIN 53 568).

LUVOCORR  Lehmann & Voss & Co. trademark for selected magnesia types to be applied in -> Fuel Oil to reduce corrosion.

LUVOMAG Lehmann & Voss & Co. trademark for highly active magnesium oxide pastes for application in polychloroprene polychloroprene mixtures. Supplied in portioned rolls weighing 1 kg.

LUVATOL Lehmann & Voss & Co. trademark for pastes containing magnesium oxide or magnesium hydroxide and calcium hydroxide. Used to control thickening of  -> BMC and -> SMC

M

MAGCARLUV Lehmann & Voss & Co. trademark for magnesium carbonates.

MAGNESIA General term for magnesium oxide, magnesium hydroxide and magnesium carbonate. Depending

on origin and production procedure it is divided into -> Caustic -> Dead-Burnt -> Fused -> Precipitated -> Sinter -> Synthetic magnesia. magnesia.

MAGNESIA ALBA Latin synonym for magnesium hydroxide carbonate.

MAGNESIA BLOCKS Press-formed magnesium hydroxide carbonate. carbonate. Used to bind hand perspiration perspiration in athletics and for cosmetic purposes.

MAGNESIA CEMENT FLOORING Flooring made from -> Sorel Cement and sawdust.

MAGNESIA CLINKER  Formed and sintered magnesium oxide.

MAGNESIA USTA Latin synonym for magnesium oxide.

MAGNESITE Magnesium containing mineral. Chemistry: Magnesium carbonate MgCO3. In the magnesia business the term M. is often used for calcined magnesite whilst the mineral is called raw (crude) magnesite.

MAGNESIUM BISULPHITE PROCESS Extraction process for wood to produce pulp using magnesium bisulphite solution for leaching. The leaching solution is prepared by reaction of sulphur dioxide with selected magnesium oxide types in an aqueous slurry.

MAGNESIUM CARBONATE Magnesium compound. Primary MgCO 3 -> Magnesite -> Nesquehonite. Nesquehonite. The term is also commonly used for the various magnesium hydroxide carbonates produced by carbon dioxide precipitation from magnesium containing solutions.

MAGNESIUM HYDROGEN CARBONATE Watersoluble magnesium compound. When water is evaporated, it forms magnesium carbonate. Commercially it is not

available.

MAGNESIUM HYDROXIDE Magnesium compound. Chemistry: Mg(OH) 2, occurring naturally as -> Brucite

MAGNESIUM HYDROXIDE CARBONATE -> Magnesium Carbonate -> Magnesia Alba

MAGNESIUM OXIDE Magnesium compound. Chemistry: MgO -> Calcined Magnesia -> Calcined Magnesite -> Caustic Magnesia -> Highly Active Magnesium Oxide -> LUVATOL -> LUVOMAG -> Magnesia Clinker -> Magnesia Usta -> MAGNULUV -> Periclase -> Sinter, Sinter Magnesia

MAGNOZINK Lehmann & Voss & Co. trademark for a co-dispersion of an active magnesium oxide and zinc oxide for Chloropren rubber. Supplied in portioned rolls weighing 1 kg.

MAGNULUV Lehmann & Voss & Co. trademark for magnesium oxide powder.

MAK-Wert Maximale Arbeitsplatz Konzentration. Konzentration. = Maximum Workplace Concentration of hazardous materials. The general dust limit of 6 mg/m3 applies also to magnesia fine dust.

MICRONIZING Milling of powder to very low particle sizes. Technique very important to magnesia to achieve particle sizes showing optimal dispersion capability.

MILK REPLACERS Special animal feedstuff containing substantial amounts of magnesium oxide to supplement nutrition of, e.g., calves during weaning.

MINERAL FEEDSTUFFS Feedstuff preparation containing essential minerals of which magnesium oxide is an integral additive. Application of magnesium oxide requires careful selection regarding bio-available magnesium content and particle size.

MODULUS Force required to achieve defined modification of shape (stretching, compression, bending). Of  particular interest in rubber technology is the -> Elasticity Modulus. Modulus . This is the force needed to stretch a test material with a cross-section of 1 cm2 by, e.g., 100 % (modulus 100). The value is given in N/cm2 (previously kg / cm2), i.e., based on the cross-section of the (unstretched) sample. Details found under DIN 53 504. Modulus is used, like other data for material testing of cured products, to assess quality of rubber mixture components, such as magnesia.

MOONEY PLASTOMETER  Shear-disc plastometer to determine plasticity of viscosity of elastomers and mixtures and their scorching properties. -> Mooney Scorch Time It measures the shear resistance of a standardised test-piece rotating rotating in the test chamber filled with the elastomer being tested. The result is given in degrees Mooney. 1° Mooney corresponds to 8.64 g s m. Test is carried out mostly for 4 minutes at 100°C (DIN 53 523 and 53 524). Often also called Mooney Viscometer.

MOONEY SCORCH TIME Important characteristic characteristic for rubber mixtures. Elapsed time is measured when plasticity rises from 5 units to 35 units above minimum at a certain temperature. The instrument used to measure this is the -> Mooney Plastomet Plastometer er.. M.S.T. characterises storing stability and processing conditions of rubber mixtures (DIN 53 524) and thus quality properties of additives like magnesia. -> Scorching

MULTIPLE-HEARTH ROASTER  Vertical kiln, subdivided into hearths, typically used for -> Burning and roasting of materials, e.g. -> Raw Magnesite

N

NESQUEHONITE Magnesium containing mineral. Chemistry: Magnesium carbonate MgCO3 ·3H2O

NEUTRALISATION The reaction of an acid and a base with the formation of a salt. Magnesia, mainly magnesium oxide, is used in various applications applications to bind acids (buffer).

NF Abbreviation Abbreviation for National Formulary. Formulary. Originally covered only defined qualitative standards for pharmaceutical pharmaceutical ingredients. Since 1975 NF is published together with -> USP USP.. Following this, monographs of both compendia were harmonised so dual listing of single substances is avoided. Since USP XX/NF XV magnesia is only listed in USP. USP XXI/NF XVI is in force since 1985.

O

OIL ABSORPTION Amount of a defined oil which can be soaked up by a powder substance, e.g. magnesia, without draining out again. Physically this phenomenon is an -> Adsorption but the term O.A. is usual.

OIL ADDITIVES Functional additives, often -> Surfactants for lubricants. Sulphonates containing magnesium are produced from magnesia.

OPTICAL SORTING Sorting process using different colour or similar optical properties of materials to separate them from each other: Important for refining of raw magnesite.

OSST -> Oxysulphate-Setting-Test

OXYChlorideE CEMENTS -> Sorrel Cement

OXYSULPHATE-SETTING-TEST Setting test using magnesium sulphate (Epsom Salt) to investigate certain qualities of  magnesium oxide for use in specific reactions, e.g. production of -> Oil Additives

P

PARTICLE SIZE DISTRIBUTION Portion of particles with certain sizes in a powder matrix. For magnesia very important quality feature in many applications. applications. -> Laser Diffraction -> Sieving Screening

PASTES Viscose to highly viscose pre-dispersed magnesia preparations preparations with excellent processing properties enabling safer and more convenient application of magnesium oxide in polychloroprene polychloroprene rubber and polyesters. -> BMC -> SMC

-> LUVOMAG -> MAGNOZINK

PATTISON PROCESS Manufacturing Manufacturing process to produce magnesium hydroxide carbonate ( especially with low apparent density) from magnesia limestone or dolomite.

PERICLASE Magnesium containing mineral. Chemistry: Magnesium Oxide MgO. The mineral name is also used for sinter magnesia produced synthetically.

PHARMACOPEIAS Compendia of regulations for the quality of drugs and ingredients and their investigation. Pharmaceutical Pharmaceutical magnesia qualities are mostly defined according to -> DAB DAB-> -> E.P E.P.. -> B.P B.P.. -> USP USP-> -> NF The E.P. has gained importance in recent years and is gradually replacing replacing national pharmacopoeias pharmacopoeias in the interest of European standardisation. standardisation.

PHARMACY Science of pharmaceutics. pharmaceutics. Magnesia is applied in pharmacy to release acids. -> Neutralisation -> Acid Acceptor or when the magnesium ion is needed to compensate for deficits in the organism. Excessive gastric acids are neutralised by -> Antacids purgative effect of magnesia -> Laxative can also be used pharmaceutically, pharmaceutically, in addition to spasmolytic properties. Magnesia for pharmaceutical pharmaceutical use must satisfy requirements of  -> Pharmacopoeias (-> E.P. E.P.,DAB,USP, ,DAB,USP,B.P. B.P.NF NF))

PHENOLIC RESINS -> Thermosetting Plastics

PHLOGISTON THEORY Theory prevalent in the 17th century which understood exothermal phenomena, such as combustion and corrosion, as being caused by a single agent called phlogiston. According to this theory incombustible substances contain no phlogiston whilst those containing phlogiston burn the more readily proportional to the amount of this agent contained therein. Disproved at the end of the 18th century by Lavoisier.

PHOTOMETRIC METHODS Analytical methods based on measuring light absorption or emission. -> Colorimeter

-> Spectral Photometer

PICKING Manual method or sorting when raw minerals and ones are mined.

POLYCHLOROPRENE -> Chloropren Rubber

POLYESTER  Polymers produced by polycondensation of polyhydric alcohol with polybasic acids. Liquid unsaturated polyesters react with magnesium oxide and magnesium hydroxide under thickening. This property is used to control viscosity, e.g. in -> BMC -> SMC

POLYMERS High molecular compounds often also called plastics. Magnesia is used in polymers as a stabiliser (acid acceptor) or to impart -> Flame Retardancy and as smoke suppressant.

POWDERS BLENDS To obtain tailor-made properties, such as certain apparent density or activity, distinct magnesia qualities are produced by special blending process.

PRECIPITATED MAGNESIA Magnesia produced by Precipitation Precipitation mostly by the-> Seawater Process

PRECIPITATION Chemical reaction between substances giving a product insoluble in the reaction medium. Precipitation Precipitation of the magnesium hydroxide from the seawater in one example.

PRILLED MAGNESIA Agglomerated magnesia, similar to -> Granulates for reduced dust generation and convenient handling.

PULP Main constituent of wood. Produced by leaching off the lignin substances. As leaching agent -> Magnesium Bisulphite produced by reaction of sulphur dioxide with aqueous slurries of  magnesium oxide is most widely used. Pure pulp is identical to cellulose.

PURITY Purity is often indicated by percentage content of MgO and that impurities. Results are mainly given on ignited basis, e.g. in pharmacopoeias pharmacopoeias or on "as-is" basis, i.e. without correction of  ignition loss. -> Content

PYROHYDROLYSIS

Process to produce metal oxides, e.g., magnesium oxide , by thermal decomposition decomposition of aqueous solutions containing the metal Chloridees.

R 

RAW MAGNESITE Common term for natural. -> Magnesium carbonate to distinguish from -> Calcined Magnesite

REACTIVITY -> Activity

REFRACTORIES The high melting point (2800°C) and the heat resistance ( 1700°C in the reducing and 2300 °C in oxidising atmosphere) of magnesium oxide make it suitable for the production of refractories. -> Magnesia Clinker

RELATIVE SURFACE -> Specific Surface

RHEOMETER  Instrument to determine rheological properties e.g. viscosity. Used to analyse thickening property of polyester resins with the magnesium oxide or magnesium hydroxide: special type of R. is used to determine state of cure of rubber mixtures. -> Mooney Viscosity

ROTARY KILN Rotating kiln, slightly inclined from the horizontal axis, used for -> Burning of, e.g. raw magnesite and magnesium hydroxide.

S

SCORCHING First step in the curing of rubber mixtures, mostly undesired. - Vulcanisation a measure for the elapsed time is -Mooney Scorch Time

SCORCH TIME -> Mooney Scorch Time

SCREEN RESIDUE SIEVES RESIDUE Quantity of substances remaining on the screen after sieving. -> Sieving , Screening -> Wet Screen Residue

SEAWATER MAGNESIA

Magnesia produced from seawater as magnesium source by the -> Seawater Process

SEAWATER PROCESS Method of extracting magnesia from seawater. Seawater contains approx. 1300 ppm magnesium.

SERPENTINE Magnesium containing mineral. Chemistry: (Mg6 [ (OH)8 I Si4O10] )

SESQUI OXIDES Term previously used for the trivalent oxides Fe2O3 and Al2O3, precipitated together as hydroxides by ammonia during quantitative magnesia analysis.

SETTING CAPABILITY Property of magnesium oxides to form a tough and stone-like material when reacting exothermally with other magnesium compounds such as magnesium Chloridee or magnesium sulphate in aqueous slurry. S.C. is determined by test revealing setting time and temperature -> Sorrel Cement

SEWAGE TREATMENT Purification of sewage to allow for harmless feed into main drainage channels or for direct recycling. Due to the soft alkaline properties properties of magnesia, it may be used as a neutralising agent in S.T.

SHAFT KILN Vertical kiln, typically used for -> Burning of minerals, e.g. -> Raw Magnesite

SHORE HARDNESS Measure for the hardness of elastomers determined by measuring the resistance against penetration by a defined test-piece under standardised pressure (DIN 53 505).

SIEVING, SCREENING Separation and classification of material into different particle sizes with screens or sieves. -> Particle Size Distribution Wet screening according to DIN 53 580 is usual for magnesia. Depending on application the -> Wet screen Residue on 40,63 or 75 µm (occasionally also wider screens) is determined.

SINGLE CRYSTALS Crystalline magnesium oxide with uniformly patterned crystal lattice. Used in optics and electronics.

SINTER, SINTER MAGNESIA Magnesium oxide burnt at high temperature (dead-burnt) -> Burning with especially high chemical resistance -> Ceramics -> Magnesia Clinker -> Refractories

SMC SMC = Sheet Moulding Compound. Polyester resin compound compound made from polyester resin and textile glass. Magnesium oxide and hydroxide is used for thickening of SMC. -> Luvatol

SOLUBILITY Magnesia is practically insoluble in water.

SOREL CEMENT Setting product of magnesium oxide and aqueous magnesium Chloridee solution. -> Magnesia Cement Flooring The -> Setting Capability of the applied magnesium is of special importance. importance.

SPECIFIC SURFACE AREA Powder characteristics, characteristics, mostly determined by -> B.E.T. Method and indicated in m2 /g powder. For For magnesia a close correlation correlation with -> Activity -> Burning Temperatur Temperature e and -> Iodine Adsorption is evident.

SPECTRAL PHOTOMETER  Instrument for measuring light emission or absorption for qualitative detection or quantitative determination determination of coloured or light emitting or absorbing substances. -> Photometric Methods

STEEL COATING -> Transformer Steel

SURFACE -> Specific Surface Area

SURFACE ACTIVE SUBSTANCES, SURFACTANS Substances which, e.g., lower surface tension of liquids. They are constituents of detergents and lubricants. Frequently, surfactants are salts (also magnesium salts) of sulfonic acids

SYNTHETIC MAGNESIA Magnesia produced by -> Pattison Process -> Pyrohydrolysis -> Seawater Process or other chemical means. -> Precipitated Magnesia

T

TANNING Processing of animal skins with chemicals to produce leather. Chrome tanning uses selected magnesium oxide to self-adjust and control the pH value during the process (Self-adjusting basification agent).

TENSILE STRENGTH Force necessary to break a standardised test-piece expanded under defined conditions. The value is given relative to the cross-section cross-section of the test-piece.

TETANY Widely occurring disease in animals caused by magnesium deficiency.

THERMAL CONDUCTIVITY Measures for the capability of homogenous material to conduct heat. Fused magnesium oxides are used for insulating heating elements due to their very high thermal conductivity together together with electrical resistance.

THERMO ANALYSIS Term for analytical methods to determine properties of material in relation to temperature temperature (decomposition, (decomposition, phase transformation). transformation). Thus, thermal decomposition of magnesium hydroxide may be monitored by thermogravimetry thermogravimetry (relation of sample weight and temperature)

THERMOSETTING PLASTICS Cross-linked high polymers made from resin capable of being hardened. On heating thermal breakdown occurs without the plastic melting. Magnesia is used as a buffer in phenolic resin types for compression moulding.

TRANSFORMER STEEL Sheets made from silicon steel coated with a layer of -> Forsterite (Mg 2SiO4) possessing defined electrical insulation properties. properties. The layer is formed by the reaction of magnesium oxide with the steel silicon.

TRANSPARENCY Term defining the light transmittance of a substance. Special magnesium carbonate carbonate types are capable of being applied in transparent rubber mixtures.

U

USP United States Pharmacopoeia. -> NF

V

VISCOSITY CONTROL Application area for magnesium oxide and hydroxide. -> BMC -> SMC to control the viscosity of  unsaturated polyester resins and their thickening properties. properties. -> Brookfield Viscosity

VISCOSIMETER  -> Rheometer

VITAMIN PREPARATIONS PREPARATIONS Drugs, Drugs, mostly OTC-type, also doped with minerals, (e.g., magnesium as magnesia) to simultaneously compensate compensate for vitamin and mineral deficiencies.

VULCANISATION Thermal and / or chemical treatment of liquid or plastic rubber mixtures to impart elastic properties. The polymer chains are, therefore, generally cross-linked with sulphur to create a three-dimensional three-dimensional network. Magnesium oxide prevents -> Scorching during mixing, storing and processing unvulcanised compounds. -> Scorch-Time

W

WASSERGEFÄHRDUNGSKLASSEN (WGK) Scheme created by the Federal Republic of Germany to classify substances according to their potential hazard to water. Using the criteria of self-classification magnesia is given WGK 0, the most harmless class. Only highly active magnesium oxide types should be classified WGK 1 due to the degree of their alkalinity.

WET GRINDING Procedure to micronise organic and inorganic substances, e.g. magnesia. The substance for milling is slurred in an appropriate appropriate liquid (mostly water) and then micronised.

WET SCREEN RESIDUE Percentage of substance remaining on the screen after wet screening. -> Sieving, Screening Determined after drying by weighing (DIN 53 580)

WHG Wasserhaushaltsgesetz. German law dealing with regulations concerning water conservation and prevention of water pollution. It also contains the scheme of -> Wassergefährdungsklassen

WHITENESS Measure to define colour of white and whitish whitish powders. Pure magnesium magnesium oxide is used for calibration. calibration. -> Colorimeter

WOOD-BURNT MAGNESITE To produce caustic magnesite low on sulphate, raw magnesite is burnt with wood.

Z Email: Juergen Mannshardt Tel.: +49 40 44197-241 Print

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