August 10, 1941
NEWS
EDITION
839
Magnesium from Magnesite PRODUCTION of magnesium from magnesite b y the Hansgirg process is expected to start on August 15 in the first unit of the new plant of the Permanente Corp. at Palo Alto, Calif. The operation i s being watched with keen interest as a source of cheap magnesium. Humors of troubles previously encountered with this process have gained wide currency. Conditions abroad and censorship of information from warring countries have prevented checking these rumors with those who know t h e facts in Germany, Wales, and Japan. The basic idea of t h e Hansgirg process i s to reduce magnesium oxide with carbon a t a high temperature, dilute and cool the reaction products with a cold inert gas, and thus recover metallic magnesium. T h e reversible reaction (MgO + C = M g + CO) is forced to the right b y t h e high temperature (2000° C.) of a threephase electric arc furnace. If the reaction products are cooled normally, t h e reverse reaction occurs and t h e yield of metallic magnesium is negligible. Sudden chilling and dilution of t h e Mg-CO mixture minimizes t h e reaction between t h e t w o and gives a high yield of metal. T h e original process employed cold hydrogen introduced directly into the gas stream from the furnace to dilute and cool the mixture suddenly t o 150° t o 200° C. Approximately 50 volumes of hydrogen were used per volume of magnesium vapor. Under these circumstances metallic magnesium is precipitated as a dust containing some magnesium oxide and some carbon carried over from t h e furnace. The dust is briquetted with oil, distilled at 7 5 0 ° to 950° C. in vacuo and t h e metal condensed and collected a s powder under a hydrocarbon oil. T h e metallic powder is t h e n melted and cast into ingots. The residue from t h e still (MgO + C ) is returned to t h e pr ess. T h e mixture of hydrogen and ca*oon monoxide from the condensers is treated with steam in the presence of a catalyst t o convert C O to C 0 2 , which i s scrubbed out, and t h e hydrogen is returned t o t h e process. This is substantially t h e process as i t was developed by Hansgirg of t h e AustroAmerican Magnesite Co. and operated a t Radenthein, Austria, some years ago. T h e magnesite used was of t h e highest purity consistent with reasonable cost. T h e hydrogen must be low in carbon monoxide a n d free from carbon dioxide and water vapor. T h e quantity of h y drogen in circulation in the process is large, but t h e amount required once the process is started is merely the make-up of mechanical losses (about 4 cubic feet per pound of metal). A t Radenthein, the electric furnaces used were 800-kilovolt
ampere capacity, three-phase arc furnaces. The plant and process were described in some detail by Landis 1 . Subsequent installations of the process with modifications are reported t o have been made in Germany, in Wales, and in Chosen, but for obvious reasons, details cannot now be obtained T h e present operation at Palo Alto is planned on a larger scale than any of the others. T h e first unit is a 9,000-kilovolt ampere furnace. As planned ultimate capacity will be 15,000 tons of magnesium per year. Condensation of the evolved magnesium vapor is t o be effected b y the use of large volumes of natural gas instead of hydrogen as in previous plants. Since the magnesium plant is located adjacent t o the Permanente cement mill, the natural gas used for condensing will be passed, after removal of magnesium and dust, t o the cement kilns for use as fuel. This operation is being watched with the utmost interest in view of the present special importance of magnesium in national defense and of the basic cheapness of the process for recovering metal from magnesite directly. Considerable 1 Trans. Eleetrochem. Soc. 72, 293 (1937).
skepticism has been expressed about the success of the present venture based on reports of troubles encountered in other plants using the Hansgirg process. T h e difficulties have been those that might be expected from handling hydrogen and highly flammable magnesium in vapor and powder forms and are no more insurmountable t h a n many others successfully solved in other electric furnace industries (phosphorus and calcium carbide, for example). T h e vacuum distillation of the magnesium powder has presented problems in heat transfer to which a number of different solutions have been proposed. D a t a from reliable sources on the operation of the process at Radenthein give a power consumption of approximately 22,000 kilowatt-hours per ton of metal, a recovery of approximately 80 per cent of the magnesium fed a s ore in t h e form of ingots of high purity, and a consumption of hydrogen of about 4 cubic feet per pound of metal produced. On this basis the cost of magnesium b y this method should b e low. T h e present development is a joint venture of the Permanente Corp., manufacturers of cement, and the Todd-California Shipbuilding Corp., one of the T o d d shipbuilding companies. The Permanente Corp. is understood t o control t h e Hansgirg process in the United States and t o share in financing the operation. T h e Todd-California Shipbuilding Corp. CONTINUED ON PAGE 8 4 1
Flow Diagram of the Hansgirs Magnésium Process Coke or anthracite coal
Magnesite Calcined
Steam Catalytic converters Η, + CO,
MgO CO2 scrubbers Briquetted Electric furnace 2000° C.
CO2 Waste
Mg + CO Condenser 150-200° C.
H2 + CO Mg + dust Briquetted with oil Residue MgO + C
Distilled in vacuum 750-950° C. ι M g vapor Pure magnesium Cast in ingots
H2
Evening. Fireworks display. Pageant presentation of "Ice-Capades of 1941", sensational musical comedy on ice, with first appearance of contestants at Convention Hall. Tuesday, September 2 Spectacular American beauty parade on Boardwalk, with 100 gaily decorated floats and 18 bands. Evening. Mardi Gras on Boardwalk. . . . Gala costume parade . . . dancing. Wednesday, September 3 Newsreel pictures on beach. Evening. First official preliminary judging of Miss America contestants. Convention Hall. Thursday, September 4 Evening. Second official preliminary judging, talent contest, and ''California Sportswear Revue" at Convention Hall. Friday, September 5 Ail-American baby parade on Boardwalk . . . selection of Miss and Master Junior America. Evening. Third official preliminary judging, talent contest, and "Cavalcade of Screen Glamour", at Convention Hall. Saturday, September 6 Beach party for contestants Evening. "Cavalcade of Screen Glamour". . . . Final official judging, talent revue, selection and crowning of Miss America 1941 at Convention Hall. Coronation ball. Sunday, September 7 Re-enactment of crowning for newsreels. This tentative program is subject to change.
Magnesium from Magnesite CONTINUED PROM PAGE 8 3 9
is reported t o be the responsible borrower of the major share of the funds required from the Reconstruction Finance Corporation. Arrangements for R F C financing to the extent of $9,250,000 for the whole plant were announced in February 1941. Part of this sum was advanced for the building of the first unit of the plant, and the remainder of the loan (about two thirds of the total) is to be made available only after successful demonstration of the process in the unit now nearing completion. U. S. production of magnesium is rising rapidly under the stimulus of defense demands. Output in 1935 was 2,120 tons and had risen to 5,325 tons by 1939. Estimated production for 1940 was 6,250 tons. Estimated world production for 1939 was 32,800 metric tons. Plans now under way look to an ultimate U. S. production of some 50,000 short tons annually.
Chester B. Kwiecien is now employed in the Planning Department of the Sherwin-Williams Co., Chicago, 111.
