GRANULES BASED ON UREA AND CALCINED POLYHALITE

The invention relates to spherical fertilizer granules comprising magnesium, calcium, potassium, sulfate and urea, based in each case on the total weight of the granules, in the following amounts: urea, calculated as nitrogen, in an amount of 11.0% to 33.0% by weight, magnesium, in an amount of 1.0% to 3.5% by weight, calcium, in an amount of 3.5% to 9.0% by weight, potassium, in an amount of 3.4% to 9.0% by weight, and sulfate, calculated as elemental sulfur, in an amount of 5.5% to 15.0% by weight, wherein at least some of the calcium, the urea and the sulfate is in the form of the crystalline phase of the formula (I): CaSO4 * 4 NH2-C(=O)-NH2. The invention also relates to a process for producing the fertilizer granules of the invention composed of polyhalite and urea, and to the use of the fertilizer granules as fertilizer or in fertilizer mixtures.