Specialty fertilizers in a wide range of products
At the Neuhof-Ellers plant, potassium-, magnesium- and sulfate-containing valuable materials are separated from the crude salt and processed into standard and specialty fertilizers in a wide range of products to meet demand.
The path to the product begins for the crude salt that is extracted from the mine with a system of mills and sieves that grind it to a grain size of less than one millimeter. Subsequently, valuable magnesium sulfate is separated in the electrostatic treatment (ESTA®), while valuable materials containing potassium are recovered in the flotation treatment. The two processes use different physical properties of the salts to separate the valuable materials magnesium sulfate (Kieserite) and potassium chloride from rock salt and other materials.
a) ESTA® process
The ESTA® process, a process developed and patented by K+S, utilizes the different chargeability of the mineral components. The ground crude salt is mutually charged by means of auxiliary materials added in small quantities and separated in an electric high-voltage field. The charged minerals are sorted depending on their charge. In Neuhof, the salt is pre-concentrated in two parallel plants in order to be purified into highly concentrated Kieserite in a downstream stage. The electrostatic separation process is a dry treatment process. This means that cost-intensive, energy-intensive product drying is not necessary.
b) Flotation process
The flotation process is based on the fact that potassium chloride crystals treated with surface-active reagents adhere to air bubbles and float in a saturated salt solution, while the rock salt crystals sink in the solution. The floating potassium chloride concentrate is skimmed off on the surface as a foam and concentrated in a multi-stage process to a purity of up to 95 percent. This is followed by dewatering in filters and centrifuges and drying of the product. The residues from the flotation - rock salt and other accompanying minerals are transported to the tailings pile via conveyor belts.
The Neuhof-Ellers plant produces more than 1.2 million tonnes of mineral fertilizers per year. All these products meet the requirements of European fertilizer legislation and are therefore declared as EC fertilizers.