Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
  • C22B26/20—Obtaining alkaline earth metals or magnesium
  • C22B26/22—Obtaining magnesium

Definitions

• magnesium can be produced by reacting reducing agents, such as silicon, with a substance containing magnesium oxide in the presence of a slag, whereby lumps of reducing agent, for instance iron and silicon, and lumps of calcined dolomite, are introduced above a molten slag.
• reducing agents such as silicon
• lumps of reducing agent for instance iron and silicon
• lumps of calcined dolomite are introduced above a molten slag.
• the magnesium oxide dissolves in the slag, enters into contact with the lumps of reducing agent and reacts therewith, causing a strong evolution of magnesium in the vapor state.
• the binders normally used to bring about agglomeration also have the effect of introducing impurities into the furnace and hence into the metal and of modifying the composition of the slag, which may affect the process.
• the method of production of magnesium by reaction of silicon with calcined dolomite exhibits another feature, i.e. the slag obtained, consisting of a calcium silico-aluminate plus a little magnesia, has little market value.
• the slag is nevertheless used by the cement industry in combination with other materials to make up cements, but, in order to render it marketable, the slag has to be quenched rapidly by pouring the molten material into cold water. This obviates setting during transportation. A substantial fraction of the slag escapes this treatment and solidifies naturally in air, particularly at the bottom of the receptacle from which the molten slag is poured into the water.
• the non-quenched fraction disintegrates during the cooling stage of between 400 and 600 C, forming a finely divided dust for which no use has yet been discovered and which gives rise to fairly difficult problems of storage.
• the reducing agent is introduced in the form of uniform size granules which exhibit little tendency to sink into the slag.
• the reducing agent is diluted by mixing with part of the slag formed as a by-product of the reaction. Additionally, the process permits the use of a large proportion, if not all, of the non-quenched slag, which has hitherto been unusable and which has constituted a nuisance factor.
• composition is typical of the slag obtained from the furnace:
• This apparatus consisted essentially of a flanged disc inclined at an angle of 3045 to the horizontal, and rotated at a speed of 18 to 24 rpm.
• the mixture of ferro-silicon and slag is poured evenly onto the: disc, accompanied by a spray of water.
• the paste so formed is gradually converted into spherical granules by the rotation of the disc which gradually overflow the rim.
• speed and inclination of the disc it was found possible to obtain spherical granules to 20 mm in diameter, all of which gave good results when subsequently used in the process.
• the balls were calcined for 50 minutes at 700 C in a rotary furnace.
• the silicon content of the balls was determined as follows: The material was finely ground, treated with concentrated caustic soda. The hydrogen evolved was passed over a drying agent and determined by measuring the quantity of water fonned by reaction with copper oxide heated to 400 C. The results of the analysis showed that oxidation of silicon during calcination was negligible.
• a reducing agent is reacted with a substance containing magnesium oxide in the presence of molten slag
• the reducing agent is introduced in the form of agglomerates produced by mixing the finely divided reducing agent with a binder consisting of water and slag, drying the agglomerates, and then calcining the dried agglomerates at a temperature not less than 700 C.
• a process as claimed in claim 1 in which the slag used in the binder is of a composition corresponding to the composition of the slag resulting from the production of magnesium.

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Citations (4)

• 1972
  • 1972-10-30 FR FR7238394A patent/FR2204697B1/fr not_active Expired
• 1973
  • 1973-10-26 CA CA184,378A patent/CA1001421A/en not_active Expired
  • 1973-10-29 JP JP12157073A patent/JPS5348166B2/ja not_active Expired
  • 1973-10-29 US US00410965A patent/US3837843A/en not_active Expired - Lifetime
  • 1973-10-29 NO NO4173/73A patent/NO133843C/no unknown
  • 1973-10-30 BR BR8513/73A patent/BR7308513D0/pt unknown

Patent Citations (4)

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