Pilot-scale experimental work on sustainable process method of production of precipitated calcium carbonate from steel slag and carbon dioxide

摘要

Steel is the most manufactured metal in the world, last year 1665 million tones were produced. What is more, in the last decades steel production has increased exponentially. Apart from being the most important metal in industry, it is a major source of carbon dioxide emissions, waste and energy consumption. In a world who is more concerned about global warming every day, trying to reduce greenhouse gas emissions, it is necessary to try to find ways to reduce these emissions. The production of steel generates steel slag, a by-product that can be utilized in industry due to its high calcium content, avoiding then the need of sending it to landfill. Slag2PCC is a process in which is possible to use the steel slag to convert it to precipitated calcium carbonate (PCC). Carbon dioxide flows are used in the process, meaning that it is a way to reduce carbon dioxide emissions and at the same time reduce energy waste. This is done in two stages: precipitation and carbonation. Precipitation has been studied thoroughly, so carbonation has been the aim of the study. Tests have been done both in the pilot scale plant and in a laboratory, in order to obtain a specific crystal morphology of PCC, scalenohedral form of calcite. When performing the tests in the pilot plant scale it was not produced scalenohedral, we performed tests in laboratory scale. This could reduce time and money, as reactor in the laboratory scale was 5 L and in the laboratory scale was 200 L. Different tests were done varying carbon dioxide flow used and the quantity of solution flow entering and leaving the reactor. Cost of producing PCC was estimated as 581.83 euro/ton PCC produced based on the parameters utilized in the pilot plant scale. This price is in range of expected if we consider the pilot plant scale as a big scale process.