Process for activating mineral raw materials with low kaolinite content, activated materials obtainable therefrom and uses thereof

Abstract

A process for the mechanochemical activation of low kaolinite starting materials, the process comprising the following steps: a) providing a solid starting material comprising a phyllosilicate mineral, the starting material having a kaolinite content determined by XRD of less than 50 wt%, preferably less than 20 wt%, more preferably less than 10 wt%; b) providing a gas; c) introducing the feedstock and the gas into a mechanical agitation unit; and d) subjecting the starting material to mechanical agitation in the presence of the gas in the mechanical agitation unit; wherein the phyllosilicate mineral is selected from the kaolinite group, serpentinite group, mica group, chlorite group, and combinations thereof.

Claims

[1] A process for the mechanochemical activation of low kaolinite starting materials, the process comprising the following steps: a) providing a solid starting material comprising a phyllosilicate mineral, the starting material having a kaolinite content determined by XRD of less than 50 wt%, preferably less than 20 wt%, more preferably less than 10 wt%; b) providing a gas; c) introducing the feedstock and the gas into a mechanical agitation unit; and d) subjecting the starting material to mechanical agitation in the presence of the gas in the mechanical agitation unit; wherein the phyllosilicate mineral is selected from the kaolinite group, serpentinite group, mica group, chlorite group, and combinations thereof. [2] The method of claim 1, wherein the phyllosilicate mineral is selected from the serpentinite group, mica group, chlorite group, and combinations thereof. [3] The method of claim 2, wherein the phyllosilicate mineral is selected from illite, chlorite, muscovite, and combinations thereof. [4] A process according to any one of claims 1 to 3, wherein the phyllosilicate mineral is present in an amount of at least 5 wt%, preferably at least 10 wt%, more preferably at least 15 wt%, based on the total weight of the starting material. [5] A process according to any one of the preceding claims, wherein the phyllosilicate mineral is not kaolinite and the starting material from step (a) comprises less than 10 wt% kaolinite, preferably less than 5 wt% kaolinite and more preferably less than 3 wt% kaolinite. [6] A process according to any one of the preceding claims, wherein the starting material comprises at least 10 wt% quartz, preferably at least 15 wt% quartz, more preferably at least 20 wt% quartz, based on the total weight of the starting material. [7] A process according to any one of the preceding claims, wherein the starting material has an amorphous fraction determined by XRD of at least 10 wt%, preferably at least 15 wt%, more preferably at least 20 wt%. [8] A process according to any one of the preceding claims, wherein the combined total amount of Si and O in the starting material is at least 60 wt%, preferably at least 65 wt%. [9] A process according to any one of the preceding claims, wherein step (d) is carried out such that the dehydration onset temperature of the mechanochemically activated material obtained in step (d) is at least 50°C lower than the dehydration onset temperature of the starting material provided in step (a), preferably at least 100°C lower, more preferably at least 175°C lower. [10] A process according to any one of the preceding claims, wherein the gas provided in step (b) is air or a gas containing at least 0.1 vol% CO2. [11] Mechanochemically activated material obtainable by the process according to any one of claims 1 to 10. [12] Mechanochemically activated material according to claim 11, which has one, two, three or four, preferably all four of the following properties: • a D50 value in the range of 0.1-30 µm, preferably 0.5-15 µm, most preferably 1-10 µm; • a dehydration onset temperature of less than 250°C, preferably less than 200°C, more preferably less than 150°C, even more preferably less than 130°C; • an amorphous content of at least 25% by weight, preferably at least 30% by weight and more preferably at least 35% by weight; • a phyllosilicate mineral content of less than 10 wt%, based on the total weight of the mechanochemically activated material, preferably less than 5 wt%. [13] A composition comprising the mechanochemically activated material according to any one of claims 11 or 12 and another material selected from the group consisting of asphalt, geopolymers, cement, polymers and combinations thereof, preferably cement, more preferably Portland cement. [14] A process for producing concrete or mortar, the process comprising the following steps: (i) providing the mechanochemically activated material according to any one of claims 11 or 12 and a further material selected from the group consisting of asphalt, cement, geopolymers and combinations thereof, optionally in the form of the composition described in claim 13, wherein the further material is selected from the group consisting of asphalt, cement, geopolymers and combinations thereof; (ii) providing a construction aggregate; (iii) contacting, preferably mixing, the mechanochemically activated material and the further material from step (i) with the building aggregate from step (ii) and optionally water. [15] Use of the mechanochemically activated material according to one of claims 11 or 12: • as a filler, preferably as a filler in a material selected from the group consisting of asphalt, geopolymer, cement, mortar, polymers and combinations thereof; • as a partial replacement for asphalt, geopolymer, clinker or cement in concrete or mortar; • to increase the compressive strength of concrete, cement or mortar; • to improve the durability of concrete or mortar; • to reduce the expansion of concrete; • to improve the resistance of concrete or mortar by reducing chloride permeability and / or porosity; • to improve the strength activity index of concrete or mortar; and / or • to reduce the water requirement of concrete or mortar, preferably, • to simultaneously improve the strength activity index of concrete and reduce the water demand of concrete; or • to simultaneously improve the strength activity index of mortar and reduce the water requirement of mortar.