DE280084C - - Google Patents

Description

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280084 CLASS 12 / ??, GROUP

containing minerals.

Patented in the German Empire on September 27, 1913.

The present invention relates to a method for producing magnesium carbonate or Magnesia usta from magnesium silicates, e.g. B. from talc, asbestos, soapstone, etc. and from Magnesium carbonate containing minerals, e.g. B. from dolomite or from its fuel products.

The finely ground magnesium silicate is calcined with so much lime or limestone that the lime _{forms monocalcium silicate (Ca Si O 3} ) with the silicic acid of the magnesium silicate, so that the magnesium content can be converted into magnesium oxide through the chemical interaction according to the reaction given here:

Mg,

H ₂ Si ₄ O ₁₂ + 4CaCO ₃ = ₃ Mg0 + 4CaSiO ₃ + 4CO ₂ + H ₂

Talk

If this kiln, consisting of Mg O and Ca Si O ₃ , is treated at normal pressure, also at normal temperature and with ammonium carbonate solution, the magnesium oxide or Mg (OH) ₂ (magnesium hydroxide) dissolves in it, while the annealed one Monocalcium silicate, which is known to be not decomposed by water, in un- 40

45

remains in an altered and insoluble state. The ammonium magnesium carbonate (double salt) that got into the solution in this way is now converted into Mg CO ₃ by simple heating.

The course of this chemical process is as follows:

a) Mg O + (Ca Si O ₃ ) + 2 (NH ₄ ) ₂ CO ₃ = 2 NH ₃ + MgCO ₃ - (NH ₄ ) ₂ CO ₃ + H ₂ O + (Ca Si O ₃ ). 55

Firing material

b) MgCO ₃ - (NH ₄ ) ₂ CO ₃ = MgCO ₃ + CO ₂ + 2NH ₃ + H ₂ O.

The digestion of the magnesium silicate is most expedient in a rotary kiln at a temperature below which the monocalcium silicate is formed.

If the Mg CO _{3 is} extracted from dolomite, it is only annealed until the carbonic acid escapes from the rock or from the magnesium carbonate; this happens at around 400 ° C. In this way only Mg O is formed. If a little Ca O has also formed, this is precipitated _{by (NH 4} ) ₂ CO _3;

After the magnesium carbonate has been added in the manner described above in

stands is established, one gains from this by further annealing at about 300 ° C the magnesia usta (Mg O).

The now in the decomposition of the

Mg CO ₃ (NH ₄ ), CO ₃

Escaping carbonic acid or carbonic acid and ammonia, such as the _{carbonic acid expelled during the glowing of the MgCO 3} to magnesia usta, are captured or _{regenerated to (NH 4} ) ₂ CO ₃ and used again for the above purposes.

Any loss that may arise here is caused by the loss that escapes from the digestion furnace Carbon dioxide replaced.

The method described has the advantage that after the unlocking of the Calcium silicate (aluminate) left over from magnesium silicate for cement manufacture and furthermore for various ceramic purposes, such as for glass, glaze and porcelain production, with can be exploited to a high degree.

It can also be made from the magnesium bicarbonate and when glowing the magnesium carbonate escaping chemically pure carbonic acid is captured and compressed, and can thus be used for a number of industrial purposes be made.

Claims (1)

Patent claim: Process for the production of magnesium carbonate from calcium and magnesium containing Minerals, e.g. B. magnesite, dolomite and from magnesium silicates, by annealing with or without the addition of lime or limestone, characterized in that the magnesium oxide obtained in this way is removed from the material to be fired at ordinary temperature brings into solution with ammonium carbonate solution and 'the magnesium carbonate precipitates from the ammonium magnesium carbonate solution thus formed by heating.