DE915454C - Process for the production of phosphate fertilizers from kieserite-containing potash crude salts (hard salts) and rock phosphates - Google Patents

Description

Process for the production of phosphate fertilizers from kieserite-containing Potash crude salts (hard salts) and rock phosphates The flotation of ground potash crude salts for the purpose of separating off potassium chlorine and then kieserite has already been described been.

Likewise, it is no longer new to convert sulfur dioxide gases and potassium chloride to potassium sulfate and hydrochloric acid; see e.g. B. the well-known Hargreaves process, which runs according to approximately the following equation: 2 KCI + SO2 + H20 + 1 /, 02 = K, SO, + 2 HCl from a patent is also a. Process known according to which raw phosphates are broken down by melting them together with lime and silica and then quenching the melt, with the addition of lime being wholly or partially replaced by magnesium oxide or magnesium salts. The production of potash glow phosphates can also be found in the literature.

The invention now relates to a particularly advantageous combination of procedural measures for the production of valuable phosphate fertilizers kieserithaltigen potash crude salts (hard salts) and rock phosphates, with some of the Known measures mentioned at the outset for a continuous interlocking Operation can be put together so that almost all chemical components the starting materials can be used economically in the most advantageous manner.

According to the invention, kieserite-containing crude potash salts, e.g. B. Hard salts, floated after suitable grinding, whereby in addition to high percentage chlorine potassium as The residue of kieserite and common salt remain. This residue is used again for separation of kieserite and table salt subjected to flotation.

The kieserite thus separated is then split in a known manner in a rotary kiln and the like into magnesium oxide and sulfur dioxide. The S 0, -containing exhaust gases, which up to now have consistently been processed on sulfuric acid, whereby the removal of the small amounts of hydrochloric acid gas present in them, resulting from the decomposition of added table salt, caused difficulties if the kieserite was not previously pre-cleaned by repeated recrystallization as Epsom salt now with the obtained highly concentrated in the flotation of potassium chloride according to the known Hargreaves process for potassium sulfate and hydrochloric acid (the latter optionally chlorine) processes, each cleaning of the S 0, -containing exhaust gases is eliminated.

This combination of cleavage of the kieserite in the rotary kiln and use of the resulting S 0, -containing exhaust gases in unpurified state in the Hargreaves process according to the present invention has been found to be particularly advantageous.

The usual K, SO, is now processed with rock phosphate and coal in a reducing atmosphere at goo to iooo 'while leaving the sulfur in the end product to a potash glow phosphate with the best fertilizer properties. In addition, the magnesium oxide formed during the cleavage of kieserite (see above) is melted together in a manner known per se with the addition of SiO ", for example in the form of sand or the like, and optionally lime with rock phosphates at between 400 and 1500", I t Mg S 04 produces about 9.6 t melt phosphate with phosphoric acid soluble in neutral citrate or citric acid.

The hot exhaust gases from the melting furnaces can also be used for kieserite drainage be used.

So it succeeds in the simplest way while avoiding numerous unnecessary ones Operations and costly transport of residues all in hard salt and rock phosphate containing chemical components except for the proportionate to continuously process worthless sodium chloride in one go in a large-scale plant.

In the following, for example, a working diagram for processing about 50,000 t hard salt and about 75,000 t rock phosphate is shown, assuming a hard salt with an average composition of about 240% potassium chloride and 240% kieserite. Figures taking into account reasonable technical yields and degrees of purity. Hard salt 47,000 t Flotation gravel : 12,000 t Flotation potash + SO2 Mg0 + pebble phosphate 33.6 0/0 + sand 6750 t K20. 5330 t 3350 t 61,000 t 7600 t Morocco phosphate 340 /, + KI S 04 techn. Melt phosphate 15 500 t P, Oä 13 500 t 69,000 t 1 1 1 With 20,000 t P2 05 Potash glow phosphate HCI 23 6oo t '5500 t with 5100 t P, 05 1 66oo t K, 0 chlorine

Claims (2)

PATENT CLAIMS. i. Process for the production of phosphate fertilizers from kieserite-containing potash salts and raw phosphates, characterized in that the kieserite obtained from kieserite-containing potash salts in addition to high-percentage potassium chlorine by flotation is split into magnesium oxide and sulfur dioxide in the rotary kiln and then the potassium chloride with the unrefined S 0, - Process is processed on potassium sulphate and the main products obtained in this way, namely potassium sulphate and magnesium oxide, are processed with the addition of rock phosphates to high-quality potash phosphate or melt phosphate fertilizers. 2. The method according to claim i, characterized in that a Kaliglühphosphatdüngemittel is obtained in a known manner from the potassium sulfate with the addition of rock phosphate and coal by annealing in a reducing atmosphere at about goo to iooo ', leaving the sulfur in the end product. 3. The method according to claim i, characterized in that the magnesium oxide obtained from the decomposition of kieserite with the addition of SiO ", for example in the form of sand, and optionally of lime or the like, and of rock phosphate in a manner known per se about 1300 to 1500 'is processed on a magnesium-containing melt phosphate fertilizer. 4. The method according to claim 1, characterized in that the hydrochloric acid formed during the reaction of potassium chloride with the unpurified S 0, -containing exhaust gases in addition to potassium sulfate in any, is known to be processed on chlorine.