Patented Oct. 11, 1938 2,132,408

UNITED STATES PATENT OFFICE 2,132,408 PROCESS FOR THE PRODUCTION OF MAG NESUM OR ALLOYS THEREOF Daniel Gardner, Rueil-Malmaison, France, as signor to Studien and Werwertungs-Aktienge sellschaft, Neuhausen, Switzerland, a joint stock company of Switzerland No Drawing. Application December 12, 1936, Se rial No. 115,540. In Great Britain December 23, 1935 5 Claims. (C. 5-67) This invention relates to a process for the Which readily combine with the to form production of or alloys thereof in which melt considerably below the de metallic State. Composition temperature of magnesium . It has been shown that nitrogen has an affin For example the magnesium nitride may be ity for magnesium and that the absorption of heated to its decomposition temperature in the nitrogen by magnesium starts at 780° C., whereby presence of calcium carbide or calcium silicide, magnesium nitride, Mg3N2, is formed, the reac whereby there is formed , which tion being understood to be facilitated by the has a melting point of about 900° C. which per presence of catalysts, such as copper oxide. mits of its 8asy gradual removal, and metallic It has also been proposed to convert magne magnesium, Which latter is distilled off in a cur sium oxide into the nitride at high temperatures rent of gas that is inert towards the magnesium, 0 by the action of carbon and nitrogen, the reaction and is collected in vacuo or in an atmosphere of being expressed by the following equation: hydrogen, or an inert gas such as , or other gas that has no action on liquid or vapourized magnesium. Alternatively the magnesium ni 5 and from the nitride thus formed to obtain ne tride may be heated in an atmosphere of hydro 5 tallic magnesium by the action of certain metals gen in large excess, whereby metallic magnesium as ferrosilicon. The production of magnesium and are formed. by these methods on an industrial Scale has not The magnesium produced by the present proc however proved possible. eSS is obtained in a high state of purity and, if 20 Hitherto the chief use of magnesium nitride desired, can be directly, combined with other has been for the production of ammonia, the metals, such as for example aluminium or bery nitride undergoing hydrolysis by the action of lium, to form magnesium alloys. water. This reaction is expressed by the follow The magnesium nitride can be obtained by ing equation: paSSing nitrogen through a powdered mixture of a magnesium compound With a carbonaceous re ducing agent at a high temperature, preferably The present invention for its object to utilize above 1000 C., so as to form magnesium nitride, magnesium nitride for the production of metallic the reaction being effected in an atmosphere free magnesium. For this purpose according to the from moisture. 30 present invention a process for the production of The present process is applicable to the pro 30 magnesium consists in heating magnesium ni duction of magnesium from practically all mag tride to a temperature above the vaporization nesium ores and salts of magnesium. The pres point 1120° C. of magnesium, for example about ence of combined Sulphur or combined chlorine 1600° C., sufficient to decompose it into vaporous ... in the ingredients facilitates the decomposition 35 magnesium and gaseous nitrogen, in the presence of the magnesium nitride by the formation of 35 of a substance which immediately combines with annonium Sulphide or chloride, and in addition and binds the nitrogen so liberated and thus re to the calcium carbide or Silicide there may also moves it from the Sphere of reaction and pre be added Suitable fluxes such as aluminium fluo vents its re-combination with the metallic mag ride or magnesium fluoride that facilitate the 40 nesium at lower temperatures. formation of liquid slags to render them easily 40 When heated to or above a dissociation tem removable. perature of 1500 and preferably about 1600° C., The process can easily be regulated so as to magnesium nitride decomposes, but the metallic Operate in a continuous manner. magnesium liberated tends to combine at once I claim: 45 with the nitrogen in the cooler ZOnes of the fur l. The proceSS of producing metallic magne 45 nace in which the treatment is carried out unless sium or its alloys Which comprises heating mag special precautions be taken to prevent this. nesium nitride Mg3N2 to a decomposition tem The process according to the present invention perature of about 1600° C. thereby to dissociate utilizes the described affinity of nitrogen for it into its elements Vaporous magnesium and 50 magnesium for the industrial production of mag nitrogen, and reacting the mixed vapors with an 50 nesium. Thus in carrying out the present proc agent that readily combines selectively with the ess magnesium nitride Mg3N2 is heated to the free nitrogen thereby holding the nitrogen - decomposition temperature, and to bind the free against recombination, at or below such decom nitrogen there is introduced into the sphere of position temperature, with the magnesium; and 55 reaction Substances, Such as calcium compounds, condensing the vaporous magnesium and col

2,182,408 lecting it in metallic form separately from the Substantially not above normal of a gas that is remaining products of the reaction; the nitrogen non-reactive with the magnesium vapor. combining agent being one or more of the group 4. The process of claim 2 and wherein the re consisting of calcium carbide and calcium silicide action is effected in an atmosphere at pressure and hydrogen gas in excess. Substantially not above normal of a gas that is 5 2. The process of producing metallic magne non-reactive with the magnesium vapor, and the Sium Or its alloys which comprises heating mag gas is maintained in flow from the reaction Zone nesium nitride Mg3N2 to at least is decomposition to the place of condensation. temperature thereby to dissociate it into its ele 5. The process of producing metallic magne ments vaporous magnesium and gaseous nitrogen, sium or its alloys which comprises heating mag 0 and reacting Such gases with a binding agent, nesium nitride Mg3N2 to at least its decomposi inamely, of the group consisting of calcium car tion temperature thereby to dissociate it into its bide and calcium silicide, which readily combines elements vaporous magnesium and nitrogen, with the released nitrogen to form inolten cal while maintaining in the reaction Zone an atmos 5 cium nitride which vaporizes only well above and phere of hydrogen in large excess, thereby to Solidifies only well below such decomposition tem cause the released nitrogen to combine with the perature, thereby holding the nitrogen against hydrogen as ammonia and thus to bind the recombination, at or below such decomposition nitrogen against recombination at or below Such temperature, with the magnesium; and separat decomposition temperature with the magnesium; ing the magnesium vapor from the remaining removing the magnesium vapors from the re 20 20 products of the reaction and condensing it in action zone, and condensing them in metallic metallic form. form, separate from the ammonia. 3. The process of claim 2 and wherein the re action is effected in an atmosphere at pressure OANE GARDNER