CS265803B1 - Method of mixture production containing largely trihydrogenphosphoric acid or np or npk fertilizers - Google Patents

Abstract

The essence of the process is that prior to adjusting the calcium to phosphorous direct freeze-thaw ratio, the decomposed shrub obtained by decomposition of the phosphates with nitric acid is partially neutralized to eliminate the solid phase, which is separated from the phosphate feedstock which is difficult to decompose. . This phase, preferably in the case of NP or NPK fertilizer production, can be added back to the fertilizer produced in some of the other operations, after adjusting the calcium to phosphorus pentoxide ratio, resulting in the final product. The effect of the proposed method of production is to reduce the formation of villi and the associated technological difficulties in mixing the organic and inorganic phases with direct freezing of the decomposed slurry.

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of a mixture comprising predominantly phosphoric acid and / or NP and / or NPK fertilizers.

In the production of NP or NPK fertilizers based on natural phosphates, using a direct freeze-drying process to adjust the ratio between calcium and phosphorus pentoxide to remove Ca (NC _q ) _rt .4 11 ^ 0 from the system, the decomposition of the phosphate feedstock is carried out . The principle of direct reservation consists in the Torah that the decomposition of the decomposed slurry occurs upon its direct contact with the cooled and immiscible liquid, such as petrol. 31 The problems of this technology are dealt with in books by I. Harmaniak: Industrial Fertilizers, Alfa 1975 and V. Lakota: Production of Combined Fertilizers, SNTL 1964. Under the operating mode conditions, so-called villi are clogged during freezing, phases. One of the causes of this difficulty is the hardly degradable admixtures contained in the phosphate feedstock, the removal of which from the decomposed slurry is a very difficult process, since they are particles of very small size, mostly of a colloidal nature.

As is evident, the lack of direct freeze-drying methods used so far lies in the fact that, before adjusting the ratio between calcium and phosphorus pentoxide, the decomposed slurry is not effectively cleaned of the hardly degradable impurities contained in the phosphate feedstock.

This disadvantage is solved by a process for producing a mixture containing predominantly trihydrogenphosphoric acid and / or NP and / or NPK.

- 2 265 803 fertilizer, including the decomposition of phosphate raw material with nitric acid, adjustment of the ratio between calcium and phosphorus pentoxide by direct freezing, for NP fertilizers, also for the ammoniacalization of frozen sludge, for NPK fertilizers prior to adjusting the ratio between calcium and phosphorus pentoxide by direct freeze-drying, the decomposed slurry is partially ammoniated to precipitate a solid phase which, together with the poorly degradable components from the phosphate feedstock, is separated from the resulting slurry.

The basic effect of the process according to the invention is that the formation of so-called villi is reduced when the organic and inorganic phases are mixed. As a result, the process according to the invention becomes more advantageous than the hitherto known processes.

For example, the proposed process is such that the disintegrated slurry is partially ammoniaised to eliminate a solid phase which, together with the hardly decomposable phosphate feed components, is separated from the resulting slurry and can advantageously be added to the fertilizer produced in some other operation. after adjusting the ratio of calcium to phosphorus pentoxide.

The above process is described in more detail below with reference to specific embodiments.

Example 1

In a batch stirred reactor, apatite Kola was decomposed at a temperature of ca. in an amount corresponding to a surplus of 10% of the consumption standard. After 60 minutes of decomposition, the obtained slurry was ammoniaized to pH 1.9. The resulting solid phase, together with the decomposed phosphate residue, was separated by filtration. The remaining clear filtrate after cooling was mixed and further shaken with cooled gasoline. The freezing temperature was maintained at about -15 ° C. After shaking was complete, 268080 free rapid separation of gasoline without the formation of a vapor phase of the so-called villi from the remaining suspension, containing predominantly phosphoric acid and calcium nitrate tetrahydrate crystals. These were separated by filtration. The product was a solution containing mainly trihydrogen phosphoric acid, non-frozen calcium nitrate and the remaining nitric acid.

Frost-free slurries without ammoniacalization and solid-phase separation produce so-called villi in an amount of about 0.5% by volume. As the industrial process is continuous, the villi volume gradually increases and hence the occurrence of technological problems in the freezing equipment.

Example 2

The process was conducted as in Example 1 except that Senegal phosphate was used instead of the Wheel apatite.

Due to the continuous process of the process, the volume of these villi is rapidly increased and the freezing equipment is gradually clogged.

Example 3

The process was conducted as in Example 1 except that Togo phosphite was used in place of the Wheel apatite.

During the freeze-up of the slurry without prior ammoniaization and separation of the solid phase, so-called villi were formed in an amount of approx.

Example 4

The process was carried out as in Example 1 except that the filtered solid phase formed together with the undissolved apatite residue. The wheels were added to the purified frozen and ammonia to pH = 4.6 neutralized slurry. After drying the product, the product was a fertilizer containing mainly dicalcium phosphate, ammonium dihydrogen phosphate and ammonium nitrate. Almost all of the P 2 O 8 content was soluble in citric acid. The physical properties of the obtained NP fertilizer were approximately comparable to the corresponding types of industrially produced fertilizers.

Example 5

The process was carried out as in Example 1 except that the filtered solids formed together with the undissolved apatite residue were added to the purified frozen and ammonia neutralized slurry (pH = 4.6) together with potassium chloride. The product was fertilizer after drying the NPK. The physical and chemical properties of the obtained fertilizer were comparable to the corresponding types of industrially produced fertilizers.

Claims (1)

SUBJECT OF THE INVENTION Process for the production of a mixture containing predominantly trihycrogenic phosphoric acid and / or NP and / or NPK fertilizers, including the decomposition of phosphate raw material with nitric acid, adjustment of the ratio between calcium and phosphorus pentoxide by direct freeze drying; A freeze-dried slurry, characterized in that, prior to adjusting the ratio between calcium and phosphorus pentoxide by direct recovery, the decomposed slurry is partially ammoniaized to form a solid phase which, together with the poorly degradable phosphate feed components, is separated from the resulting slurry. Corrections in printed descriptions of inventions In the printed description of the invention for author's certificate No. 265 803 (PV 3990-86.C), the surname of the first author is wrongly printed.