IE36791L - Making npk fertilisers. - Google Patents

Abstract

1420305 Mixing solids and liquids in flow ALBRIGHT & WILSON LTD 25 Oct 1972 [25 Oct 1971] 49547/71 Heading B1C [Also in Division Cl] In a method of mixing together particulate potassium chloride and liquid nitrogen-phosphorus melt to form an N:P:K fertiliser, the liquid melt is formed into a continuous, funnelshaped vortex having a vertical axis and a stream of the particulate potassium chloride is 'dropped along the axis and deflected outwardly into the vortex. In one apparatus for carrying out the method Fig. 1, the liquid is introduced tangentially into chamber 1 through inlets 4 so as to form the vortex. The stream of solid particles is fed down inlet 5 and is deflected by a static or vibrated conical deflector 7 which may be vertically adjustable by means of rod 8. A skirt 9 may be used to protect the deflector from liquid splashes. The mixture passes out through outlet 3. In another apparatus the conical deflector is replaced by a rotating impeller plate (10 Fig. 2 not shown) which displaces the particles centrifugally, while in a further apparatus, Fig. 3, there is an electrostatic conductor 13 electrically insulated from the chamber 1-which along with skirt is earthed-the conductor on being charged by means 7, providing a corona discharge which charges and repels the particles. A vertically adjustable deflector 16 forms the particles into a curtain around the conductor 13. The apparatus including the funnel and inlets may be steam-jacketed to keep the mixture sufficiently fluid. In a particular example, a 93-95% solution of ammonium nitrate was mixed with cold phosphoric acid containing 49-53% P 2 O 5 to produce a final product with the ratio N:P 2 O 5 equal to 1:1. This was treated with ammonia gas in a neutralizer at boiling point and atmospheric pressure to the equivalent of pH 2.7-3.0 in a 10% aqueous solution. Concentrated sulphuric acid was added and the NP solution was evaporated at 0.1-0.15 atmospheres absolute pressure to form a melt containing 0.3-1.0% water. The pH was then raised with ammonia. The hot melt was passed to the apparatus shown in Fig. 1 where preheated potassium chloride was added. The mixture was passed directly to a spinning, perforated prill bucket at the top of a prilling tower. Hot prills were recovered by raking from the floor of the tower. The product had a N:P 2 O 5 :K 2 O ratio of 15:15:21. [GB1420305A]