Abstract: A method for producing colloidal mixtures, especially water-cement mixtures with or without further solid additions, comprising the steps of feeding the material for forming the colloidal mixture into a container, stirring the material fed into the container by a blade stirrer driven by a motor at a circumferential speed at the outer diameter of the blade stirrer of at least 500 and preferably 1,500 meters per minute, continuously measuring the variations in the energy take-up of the motor, and stopping stirring of the material when the continuously observed energy take-up indicates a sudden transition from a fluctuating to a substantially steady course; and an apparatus for carrying out this method.

Abstract: A method of removing encrustations from a metallurgical lance comprising the steps of relatively displacing the lance and a tool with the tool in contact with a layer of encrustation on the lance and applying a repetitive movement to the tool against the layer to dislodge the layer from the lance and permit the layer to fall therefrom by its weight.