Distribution and extraction of chromium from phosphate ore

Abstract

Phosphate rocks are a vital and non-renewable resource which is crucial for agricultural uses. However, this raw material contains various contaminants such as Pb, Cr, Cu, Ni and Zn. Among these elements, chromium is considered as an essential micronutrient at low intake levels. Its occurrence in industrial products at higher concentration can cause a potential risk to plants, animals and human health. The objective of this work was to select a chemical reagent capable of efficiently extracting chromium from phosphate ore in order to reduce its content. The study of chromium speciation in phosphate ore allows us to evaluate its mobility and therefore its potential toxicity. To this end, the test and selection of the specific chemical reagent for efficient chromium extraction from phosphate ore were studied. The effects of some parameters were taken into consideration and optimized. The results show that the chromium content was reduced to approximately 30% in natural phosphate using citric acid as extracting solution. Sequential extractions proposed by the European Communities Bureau of Reference method were used to assess the distribution of chromium before and after chemical extraction. The results indicate that the distribution of chromium in the residual fraction is dominant.