Abstract: A mixing device (1) having at least two concentric tubular elements (2, 3) including an outer tubular element (2) and an inner tubular element (3) inside the outer tubular element, the outer tubular element and the inner tubular element each supplying a liquid (5) or solid products to be mixed together, and a helical member (4) disposed for rotational movement inside the outer tubular element for entrainment of the liquid (5) or solid products, the helical member surrounding the inner tubular element, the outer tubular element including at least one inlet orifice (6a) for introducing the liquid (5) or solid products into the outer tubular element to be entrained by the helical member, and an outlet orifice (7) for delivering a mixture (9) of the liquid and solid products (5, 8) outside the outer tubular element, the inner tubular element (3) having an open end terminating inside the outer tubular element (2) downstream of the inlet orifice (6a) and upstream of the outlet orifice (7), wherein the mixture (9) i