CS214066B1 - A method for the preparation of a magnesium-magnesium solution - Google Patents

Abstract

The invention solves the problem in the field of preparation of a magnesium-magnesium solution by preparing it from a magnesium raw material by reacting nitric acid with ammonium or calcium nitrate so that part of the solution is subjected to alkalization with ammonia and the resulting suspension consists of Mg/OH/2 and crystal nuclei of trivalent metals in the form of hydroxides and is used to further neutralize the mixture.

Description

The present invention relates to an epic process for the preparation of nitrogen-magnesium solutions by decomposing the magnesium raw material with acid due to inorganic salts, preferably nitrates, which cause a better solubility of the resulting magnesium nitrate. and / or · flood acid mixture ·

Due magnesium-magnesium solutions are intermediates in the preparation of due magnesium magnesium liquid fertilizers, an intermediate product in the production of MgO by nitrate and other teehnologies *

The processes described in the literature for decomposing magnesium raw materials with nitric acid are based on a direct reaction of the magnesium raw material / dolomite, magnesite and others / with nitric acid having an acid concentration in the range of 25 to 55 1 ° wt. , US patent 1844862 / · Procedures require precise adherence to neutralization of residual nitric acid and compliance with concentration parameters · At the same time care must be taken to ensure that temperatures are precisely maintained. · Other epoesis of acidic Mg / NOy / g solutions or melt of magnesium nitrate with other substances based on the neutralization of concentrated nitric acid with magnesium hydroxide or magnesium oxide (Czechoslovakia Patent 137487, 139169, 149384) and their subsequent treatment with other substances by processing into a product. The disadvantage of these processes is that they need to work with acids and high water contents to produce nitrate fever vp It did not crystallize during the preparation process, but this requires subsequent thickening of the solution. · When working with β melts, filtration problems do not arise again.

In AO I83OII, the decomposition of magnesite or dolomite is analyzed using highly concentrated nitric acid, resulting in a solution which crystallizes at a relatively high temperature of 80 to 100 ° C, causing considerable difficulties for further processing into liquid fertilizers.

However, an increase in the solubility of the resulting magnesium nitrate in the decomposition mixture can be achieved by increasing the number of components in the reaction system, for example by adding ammonium nitrate, thereby reducing the water content of the system. other crystallization temperatures (usually lower) and the use of this mixture to decompose the magnesium feedstock yields an acidic magnesium-magnesium solution with a water content of up to 30% less than the nicotine additive solution.

The acidic magnesium solution is not yet suitable for practical use and must be neutralized. The direct neutralization of the acidic solution is accompanied by dropping out of the gel solution of the triple metal hydroxides, causing undesirable fouling of the apparatus.

In addition, undesired conversion occurs during neutralization! Mg / NO 2 / g to Mg / OH / g, which falls out of solution and creates unpleasant incrustations on the walls of the device.

The above problems can be successfully solved by using an aqueous Mg / OH / g slurry together with fine / tiny / crystals of trivalent metals to neutralize the acidic magnesium solution to form filterable sludges of the trivalent hydroxide hydroxides ·

The magnesium hydroxide slurry can be readily prepared directly from a portion of the acidic nitrogen-magnesium solution by its full alkalization, for example, by ammonia, which at the same time forms the crystallization nuclei of the hydroxides of the tri-ionic cations. · The suspension has good flow properties and can be pumped · Vy214 066 formed by the suspension e and then neutralizes the main flow of the acidic magnesium solution to the desired pH / 6.0 - 7), wherein filterable particles are formed on the crystalline cores of the trivalent metal hydroxides.

Example 1.

The reaction mixture was 0.37 kg / hr of 30 wt. % nitric acid and 30 wt. of ammonium nitrate in a tubular reactor 0.05 m at 100 ° C is continuously reacted on a layer of magnesite which is in multiple excess against stoichiometry to obtain a mixture of dicalates in aqueous solution containing 1.95 wt.% of free nitric acid. This mixture was allowed to sediment to separate the magnesite removal from the reactor. 0.04 kg / h of mass is separated from the acidic mixture, which is subjected to alkalinization in a thermocirculation reactor with gaseous ammonia. The formed Mg / OH / ₂ slurry together with trivalent metal hydroxide crystallization nuclei is used to neutralize the flow of the acidic magnesium solution. The precipitated hydroxides are filtered off. A magnesium solution of 4.6% by weight was obtained. MgO and 18.5 wt. N at a pH of 6 to 7 in an amount of 0.54 kg / h.

Example 2.

The reaction mixture was added at a rate of 0.292 kg / h in a composition of 35% by weight. % nitric acid and 25 wt. The calcium nitrate is fed into a tubular continuous reactor of 0.05 m diameter and treated at 100 ° C with an excess of magnesite on a layer that is in a multiple stoichiometric excess to give a mixture containing unreacted HNO 2 of 2.5 µl. mass, per mass. The mixture was left to sediment to separate the kidney removal of fine magnesite. The sieve of the acidic mixture is then separated in an amount of about 10% by weight and subjected to alkaline ammonia. The Mg / OH / g slurry formed, together with the crystalline nuclei of trivalent metal hydroxides, is mixed with the aqueous solution to neutralize to pH 6-7. The resulting solution contains 7.6% by weight. MgO, 10.4. CaO and 10.6 wt. N.

Claims (1)

OBJECT OF THE INVENTION A process for preparing a nitrogen-magnesium solution by decomposing a magnesium feedstock with a mixture of nitric acid containing inorganic salts, preferably nitrates, with a salt content of 0.5 to 65% by weight. preferably about 30 wt. salts in acid and ammonium or calcium nitrate, characterized in that part of the decomposed acidic mixture is subjected to alkaline ammonia gas, the remaining acidic suspension being neutralized with magnesium hydroxide to pH 6 to pH 7.