A method for the manufacture of hydraulic binders from water treatment residuals

(22) 13.03.2020

(43) 15.09.2021

(57) (Abstract title): Manufacture of high alumina hydraulic binders: A method for the manufacture of a high alumina hydraulic binder comprising hydrating a source of aluminiumions with a source of calcium ions in the presence of water to form mineral hydrates and subsequently heating said mineral hydrates to form the high alumina hydraulic binder. Also provided is a method for the manufacture of calcium aluminate cement comprising mixing a source of calcium ions with water treatment residuals or other aluminium rich waste residuals, in the presence of water, such that mineral hydrates are formed. Water treatment residuals are waste material produced from the industrial purification of drinking water by coagulation using a flocculant. The mineral hydrates are then heated to a temperature of at least 350 °C to oxidise organic material present and at least partially dehydrate the hydrated minerals to form the cement product. Further provided is a method for the manufacture of calcium sulphoaluminate cement by following the previous method with the modification of mixing sulphate salts with the calcium ions and residuals. The source of calcium ions may comprise lime or hydrated lime. The mineral hydrates may be comminuted prior to heating. Air or oxygen may be added to the mixture during heating.

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