Abstract: Desert sand is treated to be used as an aggregate for concrete, a method for producing an aggregate for concrete is provided, and to an aggregate for concrete is provided. The aggregate is obtained by crushing desert sand in a high-pressure roller press, wherein, in a first stage, the desert sand in a bed is crushed by pressure exposure, and then forms agglomerates. In a second stage, the agglomerates are disrupted by further mechanical exposure. The pressure exposure in the first stage is accomplished by a single pressing between two surfaces at more than 50 MPa pressure. Aggregate produced in this way results in substantially greater concrete strength than when untreated desert sand is added.

Abstract: A closed-circuit grinding plant for grinding fresh material, comprising a first device for grinding the fresh material, a static pre-classifier preclassifying the ground material, having an input for the ground material, an output for a coarse meal fraction, and a further output for a fine-grained output material. A device separates out fine material, having an output for a coarse-grained fraction, with subsequent recirculation to the first grinding device, an output for fine material, and at least one input. The input is connected to the static pre-classifier output. A second grinding device is also provided. The static pre-classifier is a cascade classifier and the second grinding device is a ball mill The ball mill has a material inlet connected to the output opening for the coarse meal fraction of the cascade classifier and a material outlet connected to an input opening of the device for separating out fine material.