Cemex to start new cement-making method to cut costs, emissions

By Kylie Madry

MEXICO CITY, Feb 29 (Reuters) - Mexican cement maker Cemex will start using a new manufacturing method that will reduce its consumption of a key intermediary ingredient and cut carbon dioxide (CO2) emissions, the company said on Thursday.

Scientists say the industry releases between 8% to 9% of global CO2 emissions per year, making it one of the biggest polluters.

To address that, Cemex will begin a process of "micronizing," or finely grinding, its clinker, the heated mix of limestone and minerals that is an intermediary product in cement making, the company said.

By "micronizing" the clinker along with a proprietary blend of chemical admixtures, Cemex will need to use just a fraction of the clinker it previously put in its cement, Davide Zampini, Cemex's head of research and development, told Reuters ahead of the announcement.

On average, blended cements are made up of around 73% clinker and 27% other products, such as gypsum, cementitious additions like fly ash and slag and fillers like limestone, Zampini said. Substituting clinker further typically weakens the strength of the cement, he said.

However, by micronizing the clinker, Cemex will be able to bring that mix down to around 50-50 without compromising its strength, he added.

Cemex expects the market to be "very receptive" to the new blend, Zampini said. "It's a significant change as to what's conventionally expected from blended cements."

A large part of the cement industry's CO2 emissions come from making clinker, according to Zampini.

Around 60% of clinker's CO2 emissions are from the reaction caused when the limestone to make it is baked at extremely high temperatures, Zampini said, with another 40% being from the fuels used to heat the kilns.

The new formula's carbon footprint is less than half that of the benchmark, Zampini said. It will also reduce costs, as the fillers mixed in with the clinker are much cheaper.

"We want to roll this out as quickly as possible," Zampini said, adding Cemex had already managed to convert one plant over to the new method.

He did not give a number for how many plants would be switched over initially, but said that the change would happen using "existing assets" and with a minimal investment "in a relatively short time." (Reporting by Kylie Madry; Editing by Christian Schmollinger)