Disclosed are a hydraulic binder composition using rapidly-cooled steelmaking reduced slag powder and a method of preparing the same. More particularly, the rapidly-cooled steelmaking reduced slag (RC-LFS) powder is obtained by spraying and scattering gas at a high pressure and high speed onto electric furnace smelting reduction slag, which is one of the by-products generated during iron smelting performed in an ironworks, and quickly cooling and pulverizing the slag. The initial high hydration heat reaction and initial setting of the rapidly-cooled steelmaking reduced slag (RC-LFS) powder are delayed to ensure workability. A retardant and gypsum are mixed into the rapidly-cooled steelmaking reduced slag (RC-LFS) powder so as to activate the generation of needle-shaped ettringite and to thus develop the initial and long-term strength, and therefore the rapidly-cooled steelmaking reduced slag (RC-LFS) powder of the present invention can be used as a substitute for ordinary Portland cement.

A process for producing substantially dry slag granules comprises adding a controlled amount of water to a molten stream of slag, and granulating the slag to produce solidified slag comprising substantially dry slag granules and slag wool. An apparatus for producing substantially dry slag granules comprises: (a) an inclined surface having an upper and lower ends for receiving and discharging the stream of slag; (b) a dispersion device at the lower end of the inclined surface for dispersion of the molten slag; (c) one or more water addition devices for adding a controlled amount of water to the molten slag; and (d) a collection area adjacent to the dispersion device for deposition of solidified slag produced by the dispersion. The quantity of slag wool produced by the process and apparatus is less than that which would be produced without the addition of water.

A method for the granulation of a metallurgical slag includes blowing, from a blower or air nozzle, heated air onto liquid slag to atomize the liquid slag and subsequently form granulated slag as the atomized slag cools. The granulated slag is blown into and collected by a working chamber. In order to ensure a high quality of the granulated slag and operate in an energy-efficient manner, the atomization is provided by blowing a heated air jet free from the addition of water onto the liquid slag. The granulated slag particles are collected in the floor region of the working chamber. Air that is released from the working chamber is either supplied to a heat exchanger, which further heats the air jet blown onto the liquid slag, or the released air is directly recirculated to the blower or air nozzle in order to atomize the supply of liquid slag.

A process for the granulation of slag deriving from iron and steel production, in particular a process for the granulation of slag in air, and an apparatus configured to perform this process, provide for the production of granulates with different characteristics depending on the intended use, thus making this process and apparatus particularly versatile. More specifically, a process according to the present invention includes a step of controlling and modifying the time and/or the cooling rate of the slag granules so as to obtain slag granules having desired morphological features.