Process for preparing a urea-sulphur fertilizer

1. A process for preparing a urea-sulphur fertilizer comprising steps of:

(a) supplying urea and sulphur to a dispersion mill wherein a rotor turns within a slotted stator, thereby providing a homogenous dispersion of molten urea in molten sulphur, where the molten sulphur is the main constituent of the homogenous dispersion; and

(b) supplying the dispersion of molten urea in molten sulphur to a forming unit to provide the urea-sulphur fertiliser;

wherein the dispersion mill simultaneously melts and mixes the urea and sulphur to provide the homogenous dispersion of molten urea in molten sulphur; and

wherein at least 5 wt % of the total urea supplied to the dispersion mill is solid urea prills.

2. A process according to claim 1 , wherein solid sulphur is supplied to the dispersion mill.

3. A process according to claim 2 , wherein all of the sulphur supplied to the dispersion mill is solid sulphur.

4. A process according to claim 1 , wherein at least 10 wt % of the total urea supplied to the dispersion mill is solid urea.

5. A process according to claim 4 , wherein all of the urea is supplied to the dispersion mill as solid urea, and all of the sulphur supplied to the dispersion mill is molten sulphur.

6. A process according to claim 1 , wherein solid urea-sulphur is supplied to the dispersion mill.

7. A process according to claim 6 , wherein molten urea and molten sulphur are supplied to the dispersion mill.

8. A process according to claim 1 , wherein oversized granules and/or fines of urea, sulphur or urea-sulphur are supplied to the dispersion mill.

9. A process according to claim 1 , wherein one or more surfactants is added during step (a).

10. A process according to claim 9 , wherein a lignosulphonate is added during step (a).