DE680180C - Manufacture of dehydrated borax by gradually heating crystallized borax - Google Patents

Description

Production of dehydrated borax by gradually heating @ crystallized borax In the production of dehydrated borax in amorphous form, which is increasingly used by industry in place of crystallized borax is made by melting crystallized borax and completely draining it underneath on further heating the borax puffs up so much that it becomes extraordinarily extensive technical devices to carry out the drainage are required. There the complete removal of the water of hydration requires very high and long heating required, the building material of the furnace is attacked by the molten borax, so that expensive furnace designs must be used.

To avoid these disadvantages, it has already been proposed to crystallize Borax by heating to 7o to 9o °, first partially and then at 35o to q.00 ° to drain completely. However, this is obtained after the first process stage a borax with still 5 molecules of H.0, which in the second process stage causes an inflation of borax results in up to three times its volume. Also will eventually but an only imperfectly dehydrated product was obtained.

Even with the dehydration of crystallized borax by gradual Heating with air of controlled humidity will only produce a product a molecule of H20, also in an inflated form.

Finally, it is also known to initially reduce raw kernite to low temperatures, z. B. iao °, to be heated and then recalcined at about q.00 °. This method however, does not allow the production of anhydrous borax, but only the extraction of pure white, crystallized borax.

It has been found that dehydrated borax can be obtained by step-white heating of crystallized borax without swelling of the material and without attacking the device, in that crystallized borax first in saturated borax solution at a moderate temperature until the water of crystallization content is reduced to 4 to 2 H. 0 heated and the separated pre-dehydrated salt is then completely dehydrated at a higher temperature.

The pre-drainage is preferably carried out at temperatures of about 120 biE3rö °, while the final drainage r @ is done at around 36o °.

The separation of the pre-drained salt from the saturated borax solution is expediently done while maintaining the temperature of the pre-drainage.

During the pre-drainage in saturated borax solution neither occurs an inflation or an attack on parts of the device. The preferably up to 2 molecules of crystal water pre-dehydrated borax also melts with the then later applied high dewatering temperatures no longer, - also does not find any noticeable puffing up instead.

Exemplary embodiment In 10000 of a lye with 3600 g Nag B407 im Liters are suspended ioookg borax with ioH20 and at about 130 ° for 2 hours heated, then the mass is quickly centrifuged at the same temperature. Of the Borax obtained, which now only contains 2 mol. water of hydration, is placed in a rotating drum completely drained at about 36o °.

Claims (3)

PATENT CLAIMS: i. Process for the production of drained borax by stepwise heating of crystallized borax, characterized in that that crystallized borax first in saturated borax solution at a moderate temperature until the water of crystallization is reduced to 4. to 2H20, the pre-drained Salt is separated and completely dehydrated at a higher temperature. 2. Procedure according to claim i, characterized in that the pre-drainage at temperatures from about i2o to 130 'and complete drainage is done at about 36o ° will. 3. The method according to claim i and 2, characterized in that the separating of the pre-dehydrated salt from the saturated borax solution while maintaining the temperature of the pre-drainage is carried out.