METHOD OF PRODUCING A SYNTHETIC CARBONATED MINERAL COMPONENT IN A CEMENT MANUFACTURING PLANT
A method of producing a synthetic carbonated mineral component in a cement manufacturing plant, includes crushing concrete demolition waste, introducing the crushed concrete demolition waste into a raw meal mill without any prior screening procedure, grinding and simultaneously carbonating the crushed concrete demolition waste in the raw meal mill by reacting the crushed concrete demolition waste with CO 2 contained in a CO 2 enriched exhaust gas, thereby obtaining the synthetic carbonated mineral component, and removing the synthetic carbonated mineral component from the raw meal mill.
1 . A method of producing a synthetic carbonated mineral component from concrete demolition waste in a cement manufacturing plant, wherein the cement manufacturing plant comprises a calcination device for producing Portland clinker by decarbonating cement raw meal while releasing a CO 2 enriched exhaust gas and further comprising a raw meal mill for grinding the cement raw meal before being introduced into the calcination device, wherein the CO 2 enriched exhaust gas is fed into the raw meal mill,
wherein the method comprises the steps of:
a) crushing the concrete demolition waste to obtain crushed concrete demolition waste,
b) during a period, in which the raw meal mill is not operating for grinding the cement raw meal, introducing the crushed concrete demolition waste into the raw meal mill without any prior screening step,
c) grinding and simultaneously carbonating the crushed concrete demolition waste in the raw meal mill, said carbonating being carried out by reacting the crushed concrete demolition waste with CO 2 contained in the CO 2 enriched exhaust gas, thereby obtaining the synthetic carbonated mineral component,
d) removing the synthetic carbonated mineral component from the raw meal mill.
2 . The method according to claim 1 , wherein the crushing step a) is carried out to obtain crushed demolition waste having a particle size of 0-15 mm.
3 . The method according to claim 1 , wherein the grinding step is carried out to obtain a synthetic carbonated mineral component, wherein less than 20 wt.-% of the synthetic carbonated mineral component have a diameter larger than 90 micrometers, measured by weighing the residue on a 90 micrometer mesh sieve.
4 . The method according to claim 1 , wherein the crushed concrete demolition waste is dried in a dryer before being introduced into the raw meal mill, wherein the CO 2 enriched exhaust gas is used as a drying gas and the crushed demolition waste is carbonated in the dryer by reacting it with CO 2 contained in the CO 2 enriched exhaust gas.
5 . The method according to claim 1 , wherein water vapor is added to the CO 2 enriched exhaust gas before the CO 2 enriched exhaust gas enters the dryer and/or the raw meal mill.
6 . The method according to claim 1 , wherein the temperature in the raw meal mill during said carbonation and grinding step is adjusted to 110-140° C.
7 . The method according to claim 1 , wherein the CO 2 enriched exhaust gas released from the calcination device is used for preheating ground cement raw meal in a preheater, and wherein the CO 2 enriched exhaust gas exiting from the preheater is fed into the raw meal mill.
8 . The method according to claim 7 , wherein water vapor is added to the CO 2 enriched exhaust gas exiting from the preheater.
9 . The method according to claim 1 , wherein carbonation in the raw meal mill is conducted until the CaCO 3 content of crushed concrete demolition waste has increased by at least 5 wt.-%
10 . The method according to claim 1 , wherein a carbonation rate is controlled by adjusting the feed rate of the crushed concrete demolition waste into the raw meal mill and/or by adjusting the grain size obtained by the crushing step.
11 . A method comprising providing a synthetic carbonated mineral component manufactured according to claim 1 , wherein the synthetic carbonated mineral component is mixed with Portland clinker so as to produce a composite Portland cement.
12 . The method according to claim 11 , wherein the synthetic carbonated mineral component coming from the raw meal mill is added to the mixing step without any prior separating or screening step.
13 . The method according to claim 11 , wherein the ratio of synthetic carbonated mineral component to Portland cement is 5-30%.
14 . The method according to claim 11 , wherein the synthetic carbonated mineral component and the Portland clinker are co-ground in a cement mill of the cement manufacturing plant.
15 . The method according to claim 3 , wherein less than 10 wt.-% of the synthetic carbonated mineral component have a diameter larger than 90 micrometers, measured by weighing the residue on a 90 micrometer mesh sieve.
16 . The method according to claim 6 , wherein the temperature in the raw meal mill during said carbonation and grinding step is adjusted to 120-130° C.
17 . The method according to claim 11 , wherein the synthetic carbonated mineral component is mixed with Portland clinker coming from the calcination device so as to produce the composite Portland cement.
18 . The method according to claim 13 , wherein the ratio of synthetic carbonated mineral component to Portland cement is 20%.