DE552056C - Process for the production of potassium carbonate - Google Patents

Description

Process for the preparation of potassium carbonate As known, it is not possible to use potassium carbonate after the Solvay process, d. H. by introducing ammonia and carbonic acid in a potassium chloride solution, to be manufactured in a factory. Because of the relatively high solubility of the KHC03 formed in comparison to NH, HCOg occurs a state of equilibrium even with a low content of NH, CI in the solution a lot of KCl. A separation of these two salts is - if possible - too cumbersome, to ensure profitable production.

It is already known the Solvay process for the production of potassium carbonate to be carried out in such a way that the reaction is not carried out in water solution but in trimethylamine can go on, whereby trimethylamine bicarbonate is formed first, which reacts with the alkali chloride to form alkali carbonate and hydrochloric acid trimethylamine. The hydrochloric acid trimethylamine formed is then converted to trimethylamine according to known methods Process processed.

The invention relates to the production of potassium carbonate via potassium carbamate using liquid ammonia. The technical advantages over the mentioned Process consists in that not the special to be produced and over and over again Trimethylamine to be regenerated and supplemented is used as a conversion agent but the cheap ammonia, which is always available in abundance, which occurs again in the further course of the process and is included in the cycle of the Process is reintroduced.

When CO. and NH3 are combined as gases or in solution, see above As is known, the result is a mixture of ammonium carbamate and ammonium carbonate. The presence of a lot of water in the gases or a dilute solution is beneficial the carbonate formation, while conversely carbamate from carbonate by a dehydrating one Means such as strong NH, solution, K = CO3, etc., is obtained.

Next is ammonium carbamate as well as ammonium chloride in anhydrous or liquid ammonia containing little water is quite soluble, while potassium chloride and even more potassium carbamate are sparingly soluble in it.

According to the invention, a solid potassium salt, e.g. B. KCl, with a salt made from NH3 and CO, in anhydrous or little water liquid NH3 stirred, so that solid potassium carbamate, KCO, NH2, excreted will, while NH "Cl, NH, C02 NH2 in addition to very small amounts of KCO2 NH2 remain in the solution. NH, CO2NH2 -f- KCl - KC02NH2 -f- NH4CI solid solid solid dissolved If a little water is added to KC02NH2 and heated, NH3 or escapes NH3 and C02, and what remains is KHC03 or K2 C03 or a mixture of these two salts return. This decomposition takes place at a relatively low temperature (below ioo °).

2KC02NH2 + H20 = :: K, CO3 + 2NH3 + C02 When performing the procedure, ammonium carbamate be prepared in such a way that C02 is passed into an aqueous NH, solution, after which the solution is cooled and the precipitated salt is separated off in the pressure filter. The solution is again saturated with NH3 and C02 is reintroduced.

This salt is then stirred into liquid NH3 with solid KCl.

Instead of this salt produced in this way you can usually use it Processes produced from NH3 and C02 salts, e.g. B. Hirschhornsalz, applied or C02 can be introduced directly into the liquid NH3.

After completion of the implementation of potassium carbamate and any excess Ammonium carbamate existing sediment is separated from the liquid and washed with liquid NH. The washing liquid is used for new approaches, to carry out the procedure in a loop.

The separated and washed potassium carbamate is washed with a little water stirred and heated, with NH3 or NH3 and C02 depending on the level of temperature escape and be returned to production.

The KHC03 or K2 C03 obtained in this way represents the final product.

The separated liquid is a solution of NH @ Cl and NH, C02 NH2 in addition to small amounts of KC02 NH2 in liquid NH3.

The NH3 is separated from the solution in such a way that it becomes liquid again NH3 is obtained, either by ordinary distillation if appropriate Pressure can be done or through pressure reduction and recompression in conjunction with cooling.

The residue is heated, taking the small amount present in it KC02 NH2 reacts again with NH, Cl in KCl and NH, C02NH2. With further continuation As the temperature increases, the NH4 C02 NH2 breaks down into C02 and NH3, which are then used in production.

NH, C02 NH2 =: z NH3 -S- C02 The residue finally obtained in this way consists of NH, Cl and small amounts of KC1. It is stirred out with water and after known process in the abortion machine treated with milk of lime for the purpose of recovery of the NH3, which goes back into production.

The new process gives surprising yields; you can rely on that Produce the potassium salt used up to almost 100 ° 10 potash. Examples i. ok kg of finely ground KCl are mixed well with 12.6 kg of NH, C02NH2 and with 64.7 kg extracted liquid NH3.

This creates a sediment that is separated and has the following composition: 12.6 kg KC02 NH2, 0.6 kg NH, C02 NH2, 3J kg NH3.

Escape by adding 2.3 kg of H20 to this soil body and heating it up 5.7 kg NH3 and 0.4 kg C02 and 12.7 kg KHC03 are obtained. By further calcining 2.81: g of C02 escape and 8.8 kg of K2 C03 are obtained.

The liquid separated from the sediment has the following composition: 0.4 kg KCl, 2.0 kg NH, C02NH2, 6.8 kg NH, CI, 61.4 kg NH3.

The NH3 is distilled off from this liquid and the residue is heated, whereby 0.9 kg of NH3 and i, i kg of CO2 are obtained. The rest exists mainly from NH4 C1.

2. 10 kg of KCl are converted into 10 kg of liquid NH3 at normal temperature stirred in under pressure and then introduced 7 kg of CO 2. After implementation the KC02 NH2 is separated from the liquid and both, as in example i described, treated.

Claims (1)

PATENT CLAIMS: i. Process for the production of potassium carbonate, characterized in that a potassium salt, the acid radical of which with ammonia in anhydrous ammonia forms soluble salts, e.g. B. potassium chloride, in solid form in (anhydrous or little water containing) liquid ammonia with ammonium carbamate, Treated with ammonium carbonate or other compounds of ammonia and carbonic acid whereupon the potassium carbamate obtained in this way becomes known way is converted into potassium bicarbonate or potassium carbonate. z. Method of manufacture of potassium carbonate, characterized in that a potassium salt according to claim i is preferably in solid form in (anhydrous or little water containing) liquid ammonia is stirred in with simultaneous introduction of carbonic acid, whereupon this obtained potassium carbamate in a known manner in potassium bicarbonate or potassium carbonate is convicted.