2. Materials and methods
2.1. Sample
A phosphate concentrate sample from Bayóvar Mine/Peru was
used for the tests. According to Bayovar rock phosphate specification sheet (Union Harvest, 2015) the cadmium content ranges from
10 to 60 mg kg1 (Bech et al., 2010). For this work, the sample with
a medium particle size, around 150 lm, was used.
2.2. Cadmium removal tests from the phosphate sample
Cadmium leaching tests were carried out in two steps: (1) oxidation with 40 mg L1 H2O2 (based on exploratory tests) for
organic matter removal; (2) leaching with different leaching
agents, such as MgCl2, KCl, Na2-EDTA and citric acid for cadmium
removal. In order to check the benefits of partial oxidation of
organic matter, some leaching tests were carried out without previous oxidation for comparison purposes. A simplified flowsheet of
the cadmium removal process by organic matter oxidation with
hydrogen peroxide followed by leaching with MgCl2, KCl,
Na2-EDTA or citric acid solution is presented in