DE485070C - Manufacture of fertilizers - Google Patents

Description

Manufacture of fertilizers In de; n patent 481 177 is a process for the production of a fertilizer described, which consists in that after Mixtures composed of rock phosphate, alkali carbonate in certain proportions and silica are subjected to an annealing process.

It has now been shown that the desired exposure of the Phosphoric acid, d. H. their conversion into the citrate-soluble form (according to Petermann), is not achieved, especially if rock phosphates are used, the considerable Contains quantities of calcium fluoride.

A similar adverse effect is caused by the presence-of-somehow caused considerable amounts of gypsum in the rock phosphate.

The disruption of the digestion process already appears that in the presence of the substances mentioned, the reaction mixture often melts before the reaction temperature of about 1 zoo ° C is reached.

It has now been found that one can avoid the abovementioned conditions can if the digestion process is carried out in the presence of steam. Apparently the fluorine or sulfuric acid or by the action of the water vapor both expelled or the expulsion of these substances is facilitated and theirs this eliminates the inhibiting effect. It has also proven to be useful proven to facilitate the decomposition of the gypsum of the mixture to be glowed add small amounts of reducing substances, e.g. coal.

It has already been proposed in the production of calcined phosphates carry out the annealing process in the presence of steam. With this well-known Processes are not used and alkali carbonates, but alkali chlorides here is the water vapor to expel the chlorine from the alkali chloride in the form serve of hydrogen chloride. For this known method was by no means due to the favorable effect of water vapor when working with alkaline-reacting alkali compounds (Carbonates or hydroxides).

It was finally found that even when using rock phosphates with a lower fluorine content, the use of steam offers advantages, since in in each case the digestion process is favorably influenced by the steam will. The glow products obtained are completely or almost free of fluorine and can be used Degree of expulsion of the fluorine as a criterion for the. Degree of exposure will.

EXEMPLARY EMBODIMENT A mixture consisting of zoo parts of a North African phosphate which contained 4.2% / a Ca F: and 5.4% / a Ca SO, 10 parts sand and 22.5 parts soda was in a rotary kiln, which by means of a conventional furnace with dry coal dust was heated. At about 1050 ' the mixture began to melt and at 1080 ° it was already fairly thin. The glow product contained 18.4% citrate-soluble phosphoric acid with 25.1% total phosphoric acid and 3.2% SO3 and 1.2% F.

The same mixture was heated in the presence of steam under the same conditions. It was possible to heat to about 1,300 ° C. without the occurrence of melt flow. The glow product, heated to a temperature of only 1050 to 1080 ° C, contained 26.9% citrate-soluble phosphoric acid at 27.2% total phosphoric acid and was free from SO, and F.

Claims (1)

PATENT CLAIMS: 1. Manufacture of fertilizers according to patent 481 177, characterized in that the annealing process is carried out in the presence of water vapor is, with the mixture to be glowed optionally small amounts of reducing Adding substances. @. The method according to claim 1, characterized in that one for Generation of the temperature necessary for the digestion process, hydrogen-rich fuels (Water gas, oil or the like) used, which for the combustion of the favor able to deliver the necessary water vapor for the reaction.