SE124169C1

SE124169C1 -

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Publication number: SE124169C1
Authority: SE
Publication date: 1949-01-01

Description

KLASS 40 a:46/ BESKRIVNING OFFENTLIGGJORD AV KUNGL. CLASS 40 a: 46 / DESCRIPTION PUBLISHED BY KUNGL.

PATENT- OCH REGISTRERINGSVERKET BEVILJAT DEN 5 JANUAR! 1949 PATENTTID FRAN DEN 6 MARS 1943 PUBLICERAT DEN 1 MARS 194? Ans. den1943, nr 1620/1943. PATENT AND REGISTRATION AGENCY GRANTED ON 5 JANUARY! 1949 PATENT PERIOD FROM MARCH 6, 1943 PUBLISHED ON MARCH 1, 194? Ans. den1943, No. 1620/1943.

G. N. KIRSEBOM, RIKSBY. G. N. KIRSEBOM, RIKSBY.

Satt att framsalla alunainiummangan- eller jarnmanganlegeringar. Set to produce alumina- manganese or iron-manganese alloys.

Prioritet begard frdn den 3 december 1942 (Norge). Priority requested from 3 December 1942 (Norway).

Foreliggande uppfinning avser ett forfaringssatt for framstallning eller raffinering av mangan. The present invention relates to a process for the production or refining of manganese.

Mangan anvandes sfisom bekant i stor utstt'äckning inom stalindustrien for framstallning av vissa typer manganstal, som aro sarskilt vardefulla fOr sadana konstruktioner, som utsattas for slitage och pakanning, t. ex. skendelar, som utsattas for stark pakanning, inlagg for kulkvarnar, kulor o. s. v. Manganese is known to be widely used in the steel industry for the production of certain types of manganese, which are particularly valuable for such structures, which are subject to wear and packing, e.g. skein parts, which are subjected to strong packing, inserts for ball mills, balls, etc.

Mangan .anvandes i allmdnhet i form av ferromangan, som dr en jarn-manganlegering med en storre eller mindre halt kol och kisel och som i allmanhet motsvarar formeln (MnFe) C. Ferromangan anvandes ocksá i stor utstrackning mom stalindustrien for des-oxidations-, avsvavlings- och avkolningsandamal. Manganese is generally used in the form of ferro-manganese, which forms an iron-manganese alloy with a greater or lesser content of carbon and silicon and which generally corresponds to the formula (MnFe) C. Ferro-manganese is also widely used in the steel industry for deoxidation, desulphurisation and decarburization purposes.

Ferromangan framstalles i allmanhet i elektriska ugnar genom reduktion med kol. Da mangan har en stark affinitet i fOrhallande till kol, Or det harunder omojligt ,att framstalla en mangan, som icke innehaller kol. Ferromangan innehaller i allananhet overensstammelse med ovan namnda formel cirka 6-7 clo. Ferro-manganese is generally produced in electric furnaces by reduction with carbon. Since manganese has a strong affinity in relation to carbon, it is impossible to produce a manganese which does not contain carbon. Ferro-manganese contains in all units in accordance with the above-mentioned formula about 6-7 clo.

For manga dndamal Oro fororeningarna i ferromangan och dá sarskilt kol ofordelaktiga och det har ddrfor foreslagits flera forfaringssatt fOr framstallning av Fain, som. Or fritt fran f8roreningar. Kolhalten kan genom vissa raffineringsmetoder bringas ned till cirka 1 %. Harunder fOrslaggas emellertid dock stora mangder av den tillstadesvarande manganen, sâ att dessa processer icke Oro sarskilt lonande. T. o. in. kolmangder av naninda storleksordning Oro ofordelaktiga vid framstallfling av vissa stalsorter och det är ddrfor av betydelse ati Oven kunna avlagsna kola fullstandigt. For many dndamal Oro the contaminants in the ferro-manganese and in particular carbon are unfavorable and it has therefore been proposed several procedures for the production of Fain, which. Or free from pollution. The carbon content can be reduced to about 1% by certain refining methods. However, large amounts of the manganese present are proposed, so that these processes are not particularly rewarding. T. o. In. Coal quantities of naninda order of magnitude Concerns are unfavorable in the production of certain types of steel and it is therefore important that the coal can be completely removed.

Metallisk mangan kan Oven framstallas genom direkt reduktion med kol, men man liar liar naturligtvis samma svarighet, i det att det icke Or mojligt att framstalla metallisk mangan utan en betydlig halt av kol. Da mangan forutom vid stalframstallningen Oven anvandes som tillsattning till andra me-taller, sasom t. ex. i aluminiumlegeringar, mangan-kopparlegeringar, Heuslers legeringar o. s. v., och dO metallen i dessa fall maste vara renast mojligt, har man i sadana fall varit tvungen att anvanda reduktion med aluminium enligt Goldschmidts metod. Man maste harvid utga. frail en blandning av manganoxid och mangandioxid och manganoxiderna maste vara av renast mojliga kvalitet. Vid anvandning av dylika utgangsprodukter och aluminiumpulver kan man framstalla en jamforelsevis ren mangan. DO utgangsmedlen emellertid Oro kostbara, I det att det Or dyrhart att framstalla ren mangandioxid och (la vidare aluminium i sig sjalv Or ett jamforelsevis dyrbart fimne blir resultatet, att metallisk mangan Or dyrbar att framstalla och skillnaden mellan priset ph ferromangan och manganmetall Or dadar oproportionerligt stor. A andra sidan Or det klart, att man vid stalframstallningen skulle foredraga metallisk, kolfri mangan framf Or ferromangan, om icke den stora prisskillnaden gjorde detta om8jligt. Metallic manganese can also be produced by direct reduction with carbon, but of course there is the same similarity, in that it is not possible to produce metallic manganese without a significant content of carbon. Since manganese, in addition to the steel production above, was used as an additive to other metals, such as e.g. in aluminum alloys, manganese-copper alloys, Heusler's alloys, etc., and dO the metal in these cases must be as pure as possible, in such cases it has been necessary to use reduction with aluminum according to Goldschmidt's method. You have to pay. frail a mixture of manganese oxide and manganese dioxide and the manganese oxides must be of the purest possible quality. When using such starting products and aluminum powder, a comparatively pure manganese can be produced. However, the starting materials are expensive, in that it is expensive to produce pure manganese dioxide and (further adding aluminum itself) or a comparatively expensive figure, the result is that metallic manganese is expensive to produce and the difference between the price of ferromanganese and manganese metal is disproportionate. On the other hand, it is clear that metallic, carbon-free manganese would be preferred to ferro-manganese in steel production, unless the large price difference made this impossible.

Sasom framgar av ovanstaende torde det vara av stor betydelse att kunna astadkomma ett forfaringssatt for att skilja mangan frail andra ledsagande metaller, sasom t. ex. jam och fororeningar sasom kol och att mojliguora en enkel och tillfredsstallande tramstallning av manganlegeringar, t. ex. manganstal, mangankoppar, manganaluminium, som till vasentlig del Oro fria fran fororeningar. As is clear from the above, it should be of great importance to be able to achieve a procedure for separating manganese from other accompanying metals, such as e.g. jams and contaminants such as carbon and that a simple and satisfactory formulation of manganese alloys, e.g. manganese numbers, manganese cups, manganese aluminum, which to a significant extent Oro free from pollution.

Foreliggande uppfinning avser ett forfaringssatt for losandet av detta problem. Vid forfaringssattet blir det Oven mojligt att ett enkelt och jamforelsevis billigt salt framstalla mangan med en renhetsprocent av hit-tills i tekniken icke uppnadd grad. The present invention relates to a method for solving this problem. In the process, it also becomes possible to produce a simple and comparatively inexpensive salt with manganese with a purity percentage of a degree not hitherto achieved in the art.

Vid forfaringssattet enligt foreliggande uppfinning forfar man pa sO satt, att manganhaltigt utgangsmaterial, I. ex. nietallisk mangan, oren mangan resp. manganlegeringar, foretradesvis ferromangan, spegeljarn, som uppvisar fororeningar sasom kol och andra element, upphettas med bly, sa att manganen bringas att losa sig i blyet, varefter manganen atfoljande, i blyet olosliga amnen avlagsnas fran det manganhaltiga blybadet, och att 2— — detta darefter tillfores ett aluminium- resp. ett jarnbad, varvid bildas en aluminium-manEan- resp. en jarn-manganlegering, som skiljer sig frail blyet, varefter detta kan ledas tillbaka till processen. Den erhallna manganen, som eventuellt kan uppvisa en viss halt av fororeningar, kan om sá erfordras anyo upplosas i bly och efter avskiljningen fran Ilyet erhalles mangan, som är betydligt re-mare an den forst erhallna. Genom att fort-, Alta pa detta satt kan man efter hand komma fram till en mangan av osedvanlig renhetsgrad. In the process according to the present invention, it is carried out in such a way that manganese-containing starting material, e.g. nonallic manganese, ore manganese resp. manganese alloys, preferably ferro-manganese, mirror iron, which exhibit contaminants such as carbon and other elements, are heated with lead, so that the manganese is caused to dissolve in the lead, after which the manganese adjoining, lead-insoluble substances are removed from the manganese-containing lead bath, and then an aluminum resp. an iron bath, whereby an aluminum-manEan- resp. an iron-manganese alloy, which differs frail lead, after which this can be traced back to the process. The manganese obtained, which may possibly have a certain content of impurities, can, if required, be dissolved in lead and, after separation from the ile, the manganese is obtained, which is considerably re-more than the first obtained. By continuing in this way, one can gradually arrive at a manganese of unusual degree of purity.

Det liar emellertid visat sig, att aven efter en gangs behandling i allmanhet erhalles en mangan a-v en utomordentligt hog renhetsgrad, som Or fullt tillracklig for de i allmanhet forekommande andamalen. avriga kann.etecken framgà av foljande beskrivning. It has been found, however, that even after a one-time treatment in general, a manganese a-v is obtained of an extraordinarily high degree of purity, which is fully sufficient for the andamals which occur in general. other characters may appear from the following description.

Forfaringssattet Or mycket enkelt nit utfora och detsamma beror alltsa pit att manganen upploses lattare i bly vid hogre temperaturer an de vanligast forekommande fororeningama och beledsagande metallerna och att den i blyet losta manganen skiljes fran blyet, nar detta kyles till lagre temperaturer. The procedure is very simple to perform and the same is due to the fact that the manganese dissolves more easily in lead at higher temperatures than the most common contaminants and accompanying metals and that the manganese dissolved in the lead is separated from the lead when cooled to lower temperatures.

Manganens loslighet i bly Or vid 400° C praktiskt taget lika med n.oll, men losligheten stiger gradvis alit eftersom temperaturen. Okar och ar vid 12000 G ungefar 10 %. Nar darfOr mangan inlegeras i bly vid hogre ternperaturer kommer den att vid lagre temperaturer att kristallisera ut som metallisk mangan. De vanligtvis i ferronaan.gan forutom mangan fOrefintliga amnena hava visat sig vara av en sadan natur, att de t. o. m. vid 13.8gre temperaturer praktiskt taget icke legera sig med My. Detta är framf Or alit fallet rimed kol, jarn, kisel sit, att -vid sammansmaltning av ferromangan med bly vid tillrackligt hog temperatur, kommer manganen till vasentlig del att inlegeras i blyet, under det att kol, jam och kisel komma att forbliva olosta. Dessa ananen komma att flyta pa ytan av blybadet och avlagsnas genorn avskrapning eller liknande. Efter det att fororeningarna eller de ledsagande amnena hava avIagsnats avkyles manganblyet och harunder kommer da manganen att utskiljas och samlas pit ytan av blybadet, som blir heft manganfritt och som darefter kan anvandas pa nytt for omsmaltning av nya mangder ferromangan. Den erhallna, avskilda manganen kan darefter smaltas on for sig, varvid smit mangder bly, som forefinnas komma att avskilj as eller f Orangas. The solubility of manganese in lead Or at 400 ° C is practically equal to zero, but the solubility gradually increases as the temperature. Increases and is at 12000 G about 10%. When manganese is alloyed in lead at higher temperatures, it will crystallize out as metallic manganese at lower temperatures. The substances usually present in ferrous oxide, in addition to manganese, have been found to be of such a nature that even at 13.8 degrees Celsius they practically do not alloy with My. This is especially the case with coal, iron, silicon, in that - when fusing the ferromanganese with lead at a sufficiently high temperature, the manganese will be substantially alloyed in the lead, while coal, jam and silicon will remain unresolved. These pineapples will float on the surface of the lead bath and be removed by scraping or the like. After the contaminants or accompanying substances have been removed, the manganese lead is cooled and the manganese will then be separated and collected in the surface of the lead bath, which becomes manganese-free and can then be used again for remelting new amounts of ferro-manganese. The obtained, separated manganese can then be melted on its own, thereby infecting large amounts of lead, which are found to be separated or orangas.

Vid forsOk utf8rda i en elektrisk ugn vid cirka 1500° C visade det sig, att en inlegering av mangan fran ferromangan i bly gav en produkt, som vid avkylning i vatten visade sig innehalla 8,% Mn. Vid omsmaltning frigjordes frail denna legering kristaller, som visade sig innehalla ran mangan med nagon fororeningkisel och bly, under det att kol och jam voro helt borta. Produkten visade vid analys innehalla 99,7 % mangan. Experiments carried out in an electric furnace at about 1500 ° C showed that an alloy of manganese from ferromanganese in lead gave a product which, on cooling in water, was found to contain 8% Mn. Upon remelting, alloy crystals were released from this alloy, which were found to contain manganese with some contaminant silicon and lead, while carbon and jam were completely gone. The product showed on analysis to contain 99.7% manganese.

I praktiken kan den beskrivna raffineringen kombineras med ferromanganframstallningen, i det att den smalta ferromanganen ledes direkt frail ugnen till en induktionsugn, dar My forefinnes i smalt form av hOgsta mojliga temperatur. Blyet och ferromanganen utsattes darefter for induktionsupphettning under kortare tid, varvid en inlegering av mangan i blyet ager rum. Den overskjutande ferromanganen halles tillbaka med tilhjitlp av en skiljevagg eller liknande och manganblyet tommes Over i en annan ugn, dar avkylningen ager rum, samtidigt som man uppratthaller en reducerande eller neutral atmosfar Over badet under avkylningen for att forhindra oxidation av den utkristalliserade manganen. Mangenen kommer att samla sig som en fast kaka pa ytan av blybadet, varefter denna, nar temperaturen ham gait ned till 100° C kan avlagsnas och omsmaltas i en induktionsugn med kolfritt infordringsmaterial. Blyet ledes darefter tillbaka till processen for behandling av nya mangder ferromangan. Forfaringssattet enligt fOreliggande uppfinning bör med for-del utforas under kraftig ornroring, vilket Or sarskilt latt att erna vid anvandning av en elektrisk induktionsugn. In practice, the refining described can be combined with the ferromanganese production, in that the narrow ferromanganese is passed directly from the furnace to an induction furnace, where My is present in a narrow form of the highest possible temperature. The lead and ferro-manganese are then subjected to induction heating for a shorter time, whereby an alloying of manganese in the lead takes place. The excess ferro-manganese is held back by means of a partition or the like and the manganese lead is emptied into another oven, where the cooling takes place, while maintaining a reducing or neutral atmosphere over the bath during the cooling to prevent oxidation of the crystallized manganese. The manganese will accumulate as a solid cake on the surface of the lead bath, after which, when the temperature has dropped to 100 ° C, it can be removed and remelted in an induction furnace with carbon-free lining material. The lead is then returned to the process for processing new amounts of ferromanganese. The process set according to the present invention should advantageously be carried out under heavy agitation, which is particularly easy to do when using an electric induction furnace.

Vid en sarskilt gynnsam utforingsform av forfaringssattet for framstallning av manganlegeringar foliar man. pafoljande Ott: Skall man I. ex. framstalla jarn-manganlegeringar tillfores manganblyet ett smalt jarnbad av den forut bestamda mangden. Manganblyet kommer da att sjunka ned genom jarnbadet och harunder kommer jarnet och manganen att legeras med -varandra och samlas pa ytan av blybadet. Jarnmanganen avlagsnas darpa fran blybadet, som ledes tillbaka till processen. Om nodvandigt omr5res badet under processen. In a particularly favorable embodiment of the procedure for producing manganese alloys, one foils. pafoljande Ott: Skall man I. ex. to produce iron-manganese alloys, the manganese lead is fed to a narrow iron bath of the predetermined amount. The manganese lead will then sink down through the iron bath and during this the iron and the manganese will be alloyed with each other and collect on the surface of the lead bath. The iron manganese is removed from the lead bath, which is led back to the process. If necessary, the bath is stirred during the process.

Det her vidare visat sig, att det aven ar mojligt att kombinera reduktionen av manganmalmer med kol och raffineringsprocessen i ett arbetsforlopp. I detta fall nedsmaltas manganmalmer direkt med kol med eller utan narvaron av flussmedel Over ett blybad, varvid man ph detta satt direkt far en blymanganlegering, som darefter a-vlagsnas fran badet och bearbetas vidare for framstallning av mangan resp. manganlegeringar. Vid denna utforingsform kan man som manganmalm aven anvanda mangansilikat. Det kommer da att bildas mangansilicid. It has further been shown that it is also possible to combine the reduction of manganese ores with coal and the refining process in one workflow. In this case, manganese ores are melted down directly with carbon with or without the presence of flux over a lead bath, whereby this was put directly into a lead manganese alloy, which is then a-waved from the bath and further processed to produce manganese resp. manganese alloys. In this embodiment, manganese silicate can also be used as manganese ore. Manganese silicide will then be formed.

Denna mangansilicid kommer att spaltas av bly sit, att mangan blir i blyet, under det att kiseln kvarstannar. Det Or darfor mojligt att ekonomiskt framstalla mangan ur mangansilikatmalmer sasom t. ex. braunit, i det att man tillsatter manganslilikatet lampligen i narvaro av ett basiskt, slaggbildande element sasom kalk, varvid genom reduktion med — —3 koks forst bildas kiselhaltig mangan och kalksilikat. Narvaron av bly kommer da att astadkomma en avskiljning av mangan i denna metall, som kan ktervinnas pa detta salt. Detta är av betydelse, da man hittills icke ekon.omiskt har kunnat ateryinna mangan ur silikat. This manganese silicide will be decomposed by lead, leaving the manganese in the lead, while the silicon remains. It is therefore possible to economically produce manganese from manganese silicate ores such as e.g. brown, in that the manganese silicate is suitably added in the presence of an alkaline, slag-forming element such as lime, whereby by reduction with - —3 coke first silicon-containing manganese and lime silicate are formed. The presence of lead will then cause a precipitate of manganese in this metal, which can be recovered on this salt. This is important, as it has not hitherto been economically possible to recover manganese from silicate.

Pet torde slutligen framhallas, att processen aven kan utfOras pa det sattet, att en blandning av blyoxider och manganoxider upphettas tillsammans med lwl i en elektrisk ugn. Det kommer d. att Aga rum en samtidig reduktion av blyoxid och manganoxiderna, varefter den reducerade manganen hornmer all upplOsas i det bildade blyet. Efter franskiljning av de bildade slaggerna, vidarebehandlas det erhallna manganblyet sasom ovan beskrivits. Finally, it should be noted that the process can also be carried out in such a way that a mixture of lead oxides and manganese oxides is heated together with lwl in an electric furnace. There will then be a simultaneous reduction of lead oxide and the manganese oxides, after which the reduced manganese will all dissolve in the formed lead. After separation of the formed slag, the obtained manganese lead is further processed as described above.

Man kan i stallet f Sr bly Liven anyanda irissa legeringar av bly och andra element t. ex. magnesiumbly for att Oka manganens loslighet i bly genom bildandet av t. ex. ternara legeringar, som genom avkylning avskilja metallisk mangan. One can in the stable f Sr lead Liven anyanda irissa alloys of lead and other elements e.g. magnesium lead to increase the solubility of manganese in lead through the formation of e.g. ternary alloys, which by cooling separate metallic manganese.

Sasom utforingsexempel shall har nedan anforas nagra laboratorieforsak. As an exemplary embodiment, some laboratory experiments are given below.

Exempel 1. g manganmalm, g blyoxid och 3 g kol upphettas tillsammans i en elektrisk ugn till smaltning yid 1500° C. Efter det att reaktionen var slutfOrd, erholls en. blymanganlegering, som inneholl 7,44 % mangan. Example 1. g of manganese ore, g of lead oxide and 3 g of carbon are heated together in an electric oven to melt at 1500 ° C. After the reaction is complete, one is obtained. lead manganese alloy, which contained 7.44% manganese.

Exempel 2. g manganmahn, sona inneholl 65 % Mn02, och 3 g trakol samt 25 g metalliskt bly upphettades till 1500° C. Man erholl en blylegering med 4,7 % mangan. Example 2. g of manganese manh, zone containing 65% MnO 2, and 3 g of trachol and 25 g of metallic lead were heated to 1500 ° C. A lead alloy with 4.7% manganese was obtained.

Exempel 3. 100 g blymangan med 3,3 % manganhalt tillf5rdes ett small aluminiumbad Tried 29 g aluminium. Blymanganen tillsattes i fast form. Legeringen sjonk genom aluminiumet och harunder legerade sig manganen med aluminium. Blyet, som samlades pa bottnen, var huvudsak fritt fran mangan. Example 3. 100 g of lead manganese with 3.3% manganese content was added to a small aluminum bath Tried 29 g of aluminum. The lead manganese was added in solid form. The alloy sank through the aluminum and below it the manganese alloyed with aluminum. The lead, which accumulated on the bottom, was essentially free of manganese.

Den erhallna aluminiummanganlegeringen yisade en halt av 10,2 % Mn. samma salt sasom angivits i detta exempel kan man framstalla manganstallegeringar genom att tillsatta blymangan till smalt stal. Man erhaller cla en stalmanganlegering och fritt bly. The resulting aluminum manganese alloy yielded a content of 10.2% Mn. the same salt as given in this example, manganese steel alloys can be prepared by adding lead manganese to narrow steel. Cla is obtained from a steel manganese alloy and free lead.

Sasom framgar air ovanstaende kan fore- liggande uppfinning varieras pa ett flertal olika sat. Man kan dessutom driva hela extraktionsprocessen kontinuerligt, i det att den i en extraktionsugn bildade bly-manganlegeringen kontinuerligt avtappas fran ugnen och tvattas fri frail mangan medelst ett aluminiumbad, varefter blyet pumpas tillbaka till extraktionsugnen. Darvid kan man lampligen forfara sa, att endast det ovre sarskilt man- ganrika skiktet avtappas kontinuerligt genom en i extraktionsugnens Owe del anordnad avtappningsanordning Vidare kan forfaringssattet enligt foreliggande uppfinning genomforas i vakuum eller i narvaro av indifferenta gaser f Sr att hindra manganens oxidering. As can be seen from the above, the present invention can be varied in a number of different ways. In addition, the whole extraction process can be run continuously, in that the lead-manganese alloy formed in an extraction furnace is continuously drained from the furnace and free frail manganese is washed by means of an aluminum bath, after which the lead is pumped back to the extraction furnace. In this case, it is possible to proceed in such a way that only the upper, especially manganese-rich layer is continuously drained through a drainage device arranged in the Owe part of the extraction furnace. Furthermore, the process according to the present invention can be carried out in vacuum or in the presence of inert gases.

Claims

Patentanspra.k:

Salt to produce aluminum manganese or iron-manganese alloys, can be drawn & rayed that manganese-containing starting material, preferably ferro-manganese, is heated with lead and that the manganese is caused to dissolve in the lead, after which the manganese that this is then supplied with an aluminum resp. an iron bath, whereby an aluminum manganese resp. an iron-manganese alloy, which differs from lead, after which this can be traced back to the process.

2. sat according to patent claim 1, characterized in that manganese silicide was used as starting material.

Salt according to any one of the preceding patent claims, characterized in that the manganese which is brought to dissolve in the lead is produced by adding manganese alms to the narrow lead bath and the amount of carbon required for the reduction of these.

4. According to one of the preceding patent claims, it has been noted that the manganese to be produced, as part of the lead used to separate the manganese from the accompanying substances and contaminants, is produced in one and the same work process by reducing them. ores with

5. A claim according to claim 1, characterized in that lead alloys were used as the extraction lead for manganese, which exhibit a higher solubility for manganese at higher temperatures than pure lead.

Salt according to patent claim 1, characterized in that the extraction process is carried out continuously, in that it in a. extraction furnace formed the lead-manganese alloy is continuously drained from the furnace and washed free of manganese by means of an aluminum bath, after which the lead is pumped back to the extraction furnace.

7. Salt according to patent claims 1 and 3, characterized in that only the almost particularly manganese-rich layer is drained continuously by a draining device arranged in the upper part of the extraction furnace.

Salt according to patent claim 1, characterized in that the process is carried out with vigorous stirring, i.e. by performing the melting in an electric induction furnace.

Salt according to claims 1-5, characterized in that the process is carried out in vacuum or in the presence of inert gases to prevent the oxidation of the manganese. Stockholm 1949. Kune. Boktr. P. A. Norstedt & Stiller 490089