Determination of the concentration of Ce, La, Sm and Eu in a phosphogypsum stack, in Imbituba city, Santa Catarina, Brazil

Renata Coura Borges,Cláudio Fernando Mahler,Alfredo Victor Bellido Bernedo,Letícia Mombrini Marques

doi:10.26850/1678-4618eqj.v43.3.2018.p37-44

Abstract

Phosphate fertilizer industry produces phosphoric acid from phosphate rocks, and as a byproduct, it produces phosphogypsum, also known as agricultural gypsum. This material was stock an open-air stacks near the producing units. In order to determine levels of rare-earth elements in phosphogypsum stacks, located in Imbituba, Brazil. Samples of 1000 grams of phosphogypsum were collected in nine different points in stack 1. The concentration of rare-earth elements was determined through neutron activation analysis and results indicate significant values of rare earth elements in the phosphogypsum from Imbituba, when compared to the values of the Earth’s crust.

Highlights

Phosphogypsum is a byproduct of phosphoric acid industry and it comes from acid leaching of phosphate rock with water and concentrated sulfuric acid
Phosphogypsum is mostly composed of calcium sulfate dehydrate, impurities from the original phosphate rock can be identified in high levels
Phosphogypsum generated in Imbituba-SC was composed by phosphate rocks from igneous origins

Summary

Introduction

Phosphogypsum is a byproduct of phosphoric acid industry and it comes from acid leaching of phosphate rock with water and concentrated sulfuric acid. Phosphogypsum is mostly composed of calcium sulfate dehydrate, impurities from the original phosphate rock can be identified in high levels. These impurities are redistributed between the phosphoric acid and the phosphogypsum, during the manufacture. In the Brazilian state of Santa Catarina, there is a stack of the material, located in the city of Imbituba, south of the state capital, Florianopolis. This material is currently commercialized and applied in apple and soybean crops. This work aimed to quantify the presence of rare-earth elements (Sm, La, Ce, Eu) in phosphogypsum of Imbituba - Santa Catarina

Study site

Sample collection and preparation

Determination of rare-earth elements in the samples

Concentration of rare-earth elements

Statistical Analysis – Cluster

Conclusions