The present invention relates to a novel cementitious product produced from steelworks slag additivation to obtain material having properties suitable for use in the partial or total clinker replacement for the production of different types of cement. The process, which is also object of this invention, aims to adapt the properties of steelworks slag, by means of thermochemical treatment, including and preferably, but not only, still in the liquid steelworks slag pot, taking advantage of the thermal input of steel processing, to form a greater amount of alite (essential compound to increase pozzolanicity), under controlled conditions. After additivation, preferably, but not exclusively, the additivated steelworks slag is subjected to quenching, comminution and concentration to stabilize the alite fraction, to release the present phases and to remove any excess contaminants, such as metallic iron.

The present invention relates to a novel cementitious product produced from steelworks slag additivation to obtain material having properties suitable for use in the partial or total clinker replacement for the production of different types of cement. The process, which is also object of this invention, aims to adapt the properties of steelworks slag, by means of thermochemical treatment, including and preferably, but not only, still in the liquid steelworks slag pot, taking advantage of the thermal input of steel processing, to form a greater amount of alite (essential compound to increase pozzolanicity), under controlled conditions. After additivation, preferably, but not exclusively, the additivated steelworks slag is subjected to quenching, comminution and concentration to stabilize the alite fraction, to release the present phases and to remove any excess contaminants, such as metallic iron.

A composition of the supplementary cementitious material (SCM) is, on a dry basis, iron silicate having the chemical formula 2FeO.Math.x SiO.sub.2, where x is 1.05-2.1, the iron silicate being the balance of the SCM; 0-4% by weight of aluminum comprised in aluminum-containing compounds, preferably 2-4% by weight, and 0-7% by weight of chain breaking elements, wherein the chain breaking elements are selected from the group consisting of calcium oxide (CaO), magnesium oxide, (MgO), sodium oxide (Na.sub.2O), barium oxide (BaO), strontium oxide (SrO), manganese (II) oxide (MnO), zinc oxide (ZnO), beryllium oxide (BeO), or any combination thereof; 0-4% by weight of trace elements and/or naturally occurring impurities. The SCM has an amorphous content of at least 95% by weight.

A composition of the supplementary cementitious material (SCM) is, on a dry basis, iron silicate having the chemical formula 2FeO.Math.x SiO.sub.2, where x is 1.05-2.1, the iron silicate being the balance of the SCM; 0-4% by weight of aluminum comprised in aluminum-containing compounds, preferably 2-4% by weight, and 0-7% by weight of chain breaking elements, wherein the chain breaking elements are selected from the group consisting of calcium oxide (CaO), magnesium oxide, (MgO), sodium oxide (Na.sub.2O), barium oxide (BaO), strontium oxide (SrO), manganese (II) oxide (MnO), zinc oxide (ZnO), beryllium oxide (BeO), or any combination thereof; 0-4% by weight of trace elements and/or naturally occurring impurities. The SCM has an amorphous content of at least 95% by weight.

The invention relates to a method for processing steel slag to produce a hydraulic mineral binder with a high hardening potential and to recover iron. There is provision for this purpose to provide a feed product comprising steel slag with MnO. This feed product is further processed as a melt by introducing reducing agent into the melt. A lime saturation factor of between 90 and 110 is hereby to be achieved in the mineral melt portion. Subsequently the melt is cooled in a defined manner and elementary iron is mechanically separated from the solidified melt. The solidified melt is then supplied for use as hydraulic mineral binder. Furthermore the invention relates to a hydraulic mineral binder.

The invention relates to a method for processing steel slag to produce a hydraulic mineral binder with a high hardening potential and to recover iron. There is provision for this purpose to provide a feed product comprising steel slag with MnO. This feed product is further processed as a melt by introducing reducing agent into the melt. A lime saturation factor of between 90 and 110 is hereby to be achieved in the mineral melt portion. Subsequently the melt is cooled in a defined manner and elementary iron is mechanically separated from the solidified melt. The solidified melt is then supplied for use as hydraulic mineral binder. Furthermore the invention relates to a hydraulic mineral binder.

Disclosed are a hydraulic binder composition containing at least 50% by weight of ground granulated blast furnace slag and a system for activating the slag, the system containing at least calcium sulphate, at least one product chosen from a source of Portland clinker and lime, at least one aluminum derivative and at least one alkali metal or alkaline earth metal salt; containing a ready-to-mix building material composition comprising such a hydraulic binder and aggregates of inert material capable of being agglomerated in the presence of an aqueous phase; and a process for employing the ready-to-mix composition containing a stage of mixing the said composition with water for the purpose of the preparation of a building material, such as a concrete or mortar, and in particular an adhesive mortar, pointing mortar or levelling mortar or coating.

Disclosed are a hydraulic binder composition containing at least 50% by weight of ground granulated blast furnace slag and a system for activating the slag, the system containing at least calcium sulphate, at least one product chosen from a source of Portland clinker and lime, at least one aluminum derivative and at least one alkali metal or alkaline earth metal salt; containing a ready-to-mix building material composition comprising such a hydraulic binder and aggregates of inert material capable of being agglomerated in the presence of an aqueous phase; and a process for employing the ready-to-mix composition containing a stage of mixing the said composition with water for the purpose of the preparation of a building material, such as a concrete or mortar, and in particular an adhesive mortar, pointing mortar or levelling mortar or coating.

The present disclosure is related to the field of steel slag treatment, and in particular to a process for stabilizing steel slag, the process comprising subjecting the steel slag to an autoclave treatment by use of a high temperature and pressure saturated vapor at a pressure of 2.0 MPa or above. The process provides the slag with reliable volume stability and makes it possible to meet desired requirements of various building materials. Additionally, the process is low cost, non-polluting, and of very high industrial value.

The present disclosure is related to the field of steel slag treatment, and in particular to a process for stabilizing steel slag, the process comprising subjecting the steel slag to an autoclave treatment by use of a high temperature and pressure saturated vapor at a pressure of 2.0 MPa or above. The process provides the slag with reliable volume stability and makes it possible to meet desired requirements of various building materials. Additionally, the process is low cost, non-polluting, and of very high industrial value.