Polyhalite IMI process for KNO3 production

A kind of polyhalite, NO3- technology, applied in the field of preparing KNO3

Active Publication Date: 2013-01-09
ICL EUROPE COOPERATIEF U A
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, substantially pure KNO is directly prepared from t

Method used

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  • Polyhalite IMI process for KNO3 production

Examples

Experimental program
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Embodiment 1

[0064] To stirred nitric acid (59%, 146.7g) and recirculation solution (1090g, combined from the KNO given in Example 3 3 Polyhalite (unwashed, crushed and sieved to ~0.5 mm, 400 g) was added to a mixture of crystallized mother liquor and gypsum wash water from a previous batch). The concentration of nitric acid was varied by diluting with wash water from previous runs to maintain a constant nitrate concentration of 15-16% in the final filtrate. The reaction mixture was heated to 65 °C and stirred for 3 h. Afterwards, milk of lime (169.4 g, 30% strength in water) was added dropwise via pump to the hot mixture during 1 hour to neutralize the acidity of the slurry (slurry). When the mixture reached a pH of 5.5-6.5, the addition was stopped and the mixture was filtered under vacuum while still hot. The gypsum filter cake (700 g, 60.8% solids) was then washed with water (3 x 350 g) so that the nitrate content of the filter cake was satisfactorily low. The wet washed gypsum (575...

Embodiment 2

[0066] A sample of the solution obtained after completion of the reaction given in Example 1 above (720-900 g of solution) was treated with a 15% milk of lime solution (300 g) at a temperature of 60-70°C. As a result of this treatment, the Mg concentration was reduced from 1.5% to below 0.2%. The precipitated solid was allowed to settle, then filtered and washed. Dry solids contain more than 92% Mg(OH) 2 . The main impurities are Ca (4 2- (2%), NO 3 - (0.2%) and Cl - (0.05%).

Embodiment 3

[0068] Concentrate the precipitated Mg(OH) as described in Example 2 above by evaporation at a temperature in excess of 80° C. 2 A sample of the remaining solution containing (concentrations in w / w relative to the total solution) 2.2% Ca, 4.4% K, 1.9% Na, 0.01% Mg, 13.3% NO 3 - , 3.1% Cl - and 0.08% SO 4 2- . As a result of concentration, the total concentration of dissolved salts increased by >80%. The NaCl thus crystallized is isolated at a temperature of more than 80 °C and its purity exceeds 98% after washing.

[0069] The remaining solution is then cooled to a temperature 3 Precipitated, then separated from mother liquor and washed. Income KNO 3 The purity of is more than 99.5%, while the concentration of dissolved salts in the mother liquor to be recycled back to the reaction is in the range of 55-60%.

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Abstract

A process for producing KNO3 from polyhalite is disclosed. In a preferred embodiment, the process comprises steps of (a) contacting polyhalite with HNO3; (b) adding Ca(OH)2 to the solution, thereby precipitating as CaSO4 at least part of the sulfate present in said solution; (c) precipitating as Mg(OH)2 at least part of the Mg2+ remaining in said solution by further addition of Ca(OH)2 to the remaining solution; (d) concentrating the solution, thereby precipitating as a sulfate compound at least part of the sulfate remaining in solution; (e) separating at least part of the NaCl from the solution remaining; and (f) crystallizing as solid KNO3 at least part of the K+ and NO3- contained in the solution. The process enables direct conversion of polyhalite to KNO3 of purity exceeding 98.5% and that is essentially free of magnesium and sulfate impurities.

Description

[0001] References to related publications [0002] This application claims priority to US Provisional Application 61 / 220,230, filed June 25, 2009, which is hereby incorporated by reference in its entirety. technical field [0003] The present invention relates to the preparation of KNO 3 The method of , in particular, relates to a method using polyhalite as a starting material. Background technique [0004] Potassium nitrate (KNO 3 ) are industrially important chemicals used in explosives, fertilizers, etc. Polyhalite (K 2 SO 4 · MgSO 4 2CaSO 4 2H 2 O) is a widely distributed and readily available source of potassium. It is known in the literature to combine polyhalites with acids such as HNO 3 ) reaction as a means of preparing coarse salt mixtures containing "compound mineral fertilizers". For example, U.S. Patent No. 4,246,019 discloses a polyhalite and HNO 3 Reaction preparation containing 53.54% KNO 3 , 39.87% Mg (NO 3 ) 2 , 5.48% CaSO 4 and 1.01%H 2 O m...

Claims

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Application Information

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IPC IPC(8): C01D9/04
CPCC22B3/44C22B26/10C01D3/04C01F11/46C22B3/065C05C5/02C01F5/22C01F5/14C01D9/04Y02P10/20
Inventor 迈克尔·博南埃亚·金兹伯格阿基瓦·莫泽斯埃亚·巴尔内亚胡戈·基泽尔曼吉迪恩·弗里德曼龙·弗里姆科内利斯·佩特鲁斯·朗格维尔德
Owner ICL EUROPE COOPERATIEF U A
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