Sequential Bioleaching of Phosphorus and Uranium

Abstract

Phosphorus and uranium are both vital elements for society. In recent decades, fears have arisen about the future availability of low-cost phosphorus and uranium. This has resulted in pressure to de-centralize production of both elements by utilizing lower-grade or complex deposits. The research presented here focused on phosphorus-containing apatite ores with uranium impurities; in order to separate uranium by selective and sequential bioleaching before phosphorus leaching. This would create an alternative process route for solvent-extraction, used to remove/recover uranium from the phosphorus acid product of apatite H2SO4 wet process. In this work, it was seen that the used fluorapatite ore required 24 h leaching at pH 1 by H2SO4 to result in 100% leaching yield for phosphorus. As this ore did not contain much uranium, an artificial fluorapatite-uranium ore was prepared by mixing standard uranium ore and fluorapatite. The research with this ore showed that 89% of uranium dissolved in 3 days at pH > 2 and leaching was improved by applying Fe3+ oxidant. In these conditions only 4% of phosphorus was leached. By prolonged (28 days) leaching 95% uranium yield was reached. According to the experiments, the iron in the uranium leach solution would be mainly Fe3+, which allows the use of H2O2 for uranium recovery and then direct use of spent leachate for another uranium leaching cycle. After the dissolution of uranium, 90% of phosphorus was dissolved by decreasing the pH to 1.3. This was done by bioleaching, by utilizing biogenic sulfur oxidation to sulfuric acid.

Recent Advances in Biomining and Microbial Characterisation

“…Commercial biomining applications have conventionally targeted copper, gold, uranium, nickel, cobalt and zinc [8]. More recently, the possibilities of extracting other commodities such as rare earth elements and phosphorus (P) have also been evaluated [9,10]. The cumulative number of publications listed in Scopus referring (in the title, abstract and/or keywords) to bioleaching, biooxidation, biomining or biosolubilisation, and copper, zinc, nickel, gold, cobalt, uranium or rare earths are shown in Figure 1B.…”

Bioleaching Modeling—A Review

“…Bacterial leaching of metallic sulphides has developed quickly over the last few decades [ 25 ]. The utilization of microorganisms for the retrieval of heavy metals has become a well-established biotechnological practice [ 26 , 27 ], which has been used primarily in copper [ 25 , 28 , 29 ], cobalt [ 30 ], nickel [ 31 ], zinc [ 32 ], and uranium [ 33 ] recovery, metals that are typically obtained from sulfides that are insoluble or, in the case of uranium, from oxidized minerals [ 34 ].…”

Bioleaching of Metals from Wastes of Phosphoric Fertilizers Production

“…It is known a number of studies devoted to the behavior of rare earth elements in phosphorite ores [1,2] and natural water [3][4][5]. It was investigated the possibility of rare earth elements composition obtaining from deposits in the Southwestern Sinai, the characterization of the residue shows the presence of uranium, rare-earth elements (REE), aluminum, and zinc that can be valorized [6].…”

“…An especially acute environmental problem arises in the presence of concomitant radioactive elements, which complicates the implementation of waste recycling processes. In studies by Mäkinen et al [2] the possibility of preliminary selective separation of uranium from phosphoruscontaining apatite ores with uranium impurities has been shown. It was found that the mixture used is fluorapatite and standard uranium ore and requires 24-hour sulfuric acid leaching at pH = 1 to obtain a 100% phosphorus yield.…”