Removal of Major Phosphate Impurities by Flotation using DTAB Collector

Removal of phosphate impurities is a prerequisite for using phosphate ores in different applications. The flotation process is one of the most promising processes that have been used to improve the phosphate grade. However, the flotation performance depends on the type of the associated impurities to valuable minerals due to their different flotation behaviour that needs more attention. In this paper, the flotation response of impurities at different pH and dodecyl tri-methyl ammonium bromide (DTAB) collector concentrations was investigated using the statistical design of experiments. The results indicated that some impurities were completely removed such as silica and alumina while others are only partially removed at about 72% and 38%, respectively. Thus, based on the impurities response to flotation and their rejection by flotation using DTAB collector, they are classified into two groups. The first group is SiO2, MgO, and Al2O3, while the second group includes only sulphide mineral (FeS2). The lowest rejection percentage for pyrite is due to its chemical composition as a sulphide mineral that has a different interaction with DTAB collector in comparison to first group minerals.

Review of the Main Factors Affecting the Flotation of Phosphate Ores

The way to successfully upgrade a phosphate ore is based on the full understanding of its mineralogy, minerals surface properties, minerals distribution and liberation. The conception of a treatment process consists of choosing the proper operations with an adequate succession depending on the ore properties. Usually, froth flotation takes place in phosphate enrichment processes, since it is cheap, convenient, and well developed. Nevertheless, it is a complex technique as it depends on the mineral’s superficial properties in aqueous solutions. Aspects such as wettability, surface charge, zeta potential, and the solubility of minerals play a basic role in defining the flotation conditions. These aspects range from the reagents type and dosage to the pH of the pulp. Other variables namely particles size, froth stability, and bubbles size play critical roles during the treatment, as well. The overall aim is to control the selectivity and recovery of the process. The following review is an attempt to add to previous works gathering phosphate froth flotation data. In that sense, the relevant parameters of phosphate ores flotation are discussed while focusing on apatite, calcite, dolomite, and quartz as main constituent minerals.

Production of a Phosphate Concentrate from the Tailings of a Niobium Ore Concentrator

Apatite is the main source of phosphorous for the making of chemical fertilizers. While apatite is usually recovered from phosphate orebodies as the primary product of a mining exploitation, this paper documents the approach taken to produce a phosphate concentrate as a secondary product from the tailings of a niobium ore concentrator. The conventional desliming/flotation scheme used to process phosphate ores was tested and adapted to process one of the reject streams of a niobium concentrator in order to produce a salable phosphate concentrate. For that particular material, it was found that the reverse flotation of apatite yielded better results than the commonly used direct flotation of apatite. The recommended approach to produce the phosphate concentrate is desliming followed by reverse flotation of apatite and an acid leaching of the apatite concentrate to lower the MgO content below the specification for a phosphate concentrate. The obtained phosphate concentrate assays more than 32% P2O5 at a P2O5 recovery of 41%, which although low is found to be economic for the case of processing plant reject tailings.