SPUR 2022: Production of CaCO3 through CO2 Mineralization based on phosphogypsum waste

Background

Phosphogypsum is a waste product from the phosphate industry. Global phosphogypsum (PG) generation is estimated at 200 Mt/a (Parreira, Kobayashi and Silvestre, 2003; Yang et al., 2009), but only about 15 percent is recycled as building materials, agricultural fertilizers, or soil stabilization amendments (Tayibi, Choura and Lopez, 2009). The United States Environmental Protection Agency has banned most applications of phosphogypsum having a 226Ra concentration of greater than 10 picocurie/gram (0.4 Bq/g). As a result, phosphogypsum which exceeds this limit is stored in large stacks. Central Florida has a large quantity of phosphate deposits, particularly in the Bone Valley region. As a result, there are about 1 billion tons of phosphogypsum stacked in 25 stacks in Florida (22 are in central Florida) and about 30 million new tons are generated each year. The transformation of CO2 into a precipitated mineral carbonate is considered a promising option for carbon capture and storage since the captured CO2 can be stored permanently and industrial wastes can be recycled and converted into value-added carbonate materials. Carbon mineralization as a strategy to both sequester CO2 and liberate energy-relevant minerals represents a significant opportunity to address the growing need for these minerals while concurrently contribution to a reduction in greenhouse gases. This proposal will use phosphogypsum (PG) waste for CO2 mineralization to produce high quality CaCO3 and recover the REE and radionuclides from phosphogypsum (PG).

Student Role

Student will participate the experimental design and conducting experiments. Proposed research will include phophogypsum dissolution and CO2 mineral carbonation process. In this process the phosphogypsum will be dissolved into solution and obtain a Ca rich solution. Solid product will be separated from lixivium. The carbonation process is performed by adding NH4OH and CO2 into remaining leach solution. After the desired reaction time, the solution is filtered to recover CaCO3 which will be dried under 80 OC. Most experiments will involve in the dissolution/ leaching and solution reactions.

Student Learning Outcomes & Benefits

Student will gain the research experiences in materials science and chemical engineering, including the experimental design, procedure development, material characterization, data analysis. These skills will prepare student for future careers in industry and/or to advance their academic degree.

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Xuming Wang
Research Professor

Materials Science & Engineering
College of Mines & Earth Sciences

The first thing is to develop a relationship founded on mutual respect. I understand that the skills student learned are not only for their present work but also for their future careers. Therefore, I will involve in student’s skill development. I will first discuss student’s interests, the type of work they want to do, and their future goals. Let student know what necessary skills need to be developed. I will continuously encourage student’s independence. In order to provide enough guidance, I will have project meeting with student every week to develop the research plan, experimental procedure and discuss the experimental data. I will be available to answer their questions.