Optimization of flotation pH for the reverse flotation of an African low-grade BIF haematite ore

Abstract

Beneficiation of iron ore by flotation is widely used in Brazil, India and China. In Africa, however, this practice is not yet commercially developed.The aim of this test work is to serve as a starting point by establishing suitable pH conditions for the development of a practically implementable reagent suite, which will then be included in a larger beneficiation circuit for producing high-grade iron ore sinter feed.In the literature, African iron ore types are graded as low-grade (60.0-62.9% Fe; 8.6-12.5% SiO 2 and insolubles), high-grade (66.0-69.9% Fe; 0.8-4.5% SiO 2 and insolubles), and meduim-grade as the remaining portion (Astrup et al., 1998). The low-grade ore used in this work contains less than 60% Fe.For Brazilian ores consisting of a combination of haematite and quartz, it is common to use corn starch as a depressant and ether amine blends as collectors with additional frothing characteristic (Araujo et al., 2005). Work by Turrer and Peres (2010) shows the possibility of using other depressants successfully as well.The main mechanism of the reverse flotation of quartz from iron ore is based on the electrostatic theory of flotation. This is due to the strong pH dependence of the zeta potential of the mineral edge planes on silicate particles (Fuerstenau and Pradip. 2005).An electrical double layer, (inner and outer Helmotz planes), as illustrated in Figure 1, forms on the surface of particles submerged in a solution. The charge in the outer Helmotz plane is depicted by the potential-determining ions on the mineral surface. The ion type that is predominantly concentrated on the surface is determined by the solution pH.In general, a higher quartz recovery to the froth phase is attained at pH 9, which is attributed mainly to the largest negative surface charge at this pH, (Vieira and Peres, 2007), as indicated in Figure 2. Hydrophobicity of quartz increases as the zeta potential becomes more negative, due to the increased force between the negatively charged quartz surface and the positively charged amine molecule.Sirkeci (2000) attributed the increased quantities of silicate minerals reporting to the froth phase to the equilibrium between ionized and molecular amine species at pH 9.3.A low-grade haematite ore from Africa was utilized for this flotation test work. Ore characterization consisted of particle size distribution, mineralogical characterization, and compositional characterization. Sample splitting and blending at a representative level were conducted to produce feed samples for laboratory-scale flotation tests.The flotation reagent suite included 150 g/t combined isodecyl ether propylene amine/amino acetate and 1,3-P-propanediamine, N-(3-(C10-C16-alkyloxy) propyl)-derivatives collector and a causticized corn starch, with solution concentration of 2.0% by

Understanding the Environmental Impact of a Mine Dam Rupture in Brazil: Prospects for Remediation

“…The relevant increase in soil pH from 5.2 in preserved soil to 8.1 in sediment can be understood based on the iron ore beneficiation process, particularly the reverse flotation which takes place at an optimum pH ∼ 9 (Araujo et al, 2005; Filippov et al, 2014; Fouchee et al, 2016). It would be expected that the increase in soil pH might be followed by an elevation not only in NH 4 + concentration but also in Na.…”

“…Desliming efficiency is achieved by increasing the pH with NaOH, which favors electrostatic repulsion among the particles to separate the hematite. The main mechanism of the reverse flotation of quartz from iron ore is based on the electrostatic theory of flotation, which depends on the zeta potential of the mineral on silicate particles at a pH ∼ 8.0 (Fouchee et al, 2016).…”

Total and arbuscular mycorrhizal fungal communities in the first 3 years after the collapse of the Fundão Dam: are we on the ecosystem recovery pathway?

“…Considering soil pH as a factor that limits microbiota and plant establishment and affects nutrients availability in the soil, we observed small changes in the chemical attributes for the same area over this short period of time and a substantial difference in soil pH between affected and unaffected sites. This difference can be explained by the effects of the iron ore refining process, which maintains the flotation pH range between neutral and slightly alkaline (Fouchee et al 2016). The pH, as noted in PCoA, was a factor that drove the separation of sampled areas during monitoring.…”

Removal of Silica and Alumina as Impurities from Low-Grade Iron Ore Using Wet High-Intensity Magnetic Separation and Reverse Flotation

“…of alumina and silica with amine collectors depends on the surface charge of the mineral particles [14]. The overall mineral surface charge in slurry strongly depends on the pH of the slurry [15]. When surface charge and the zeta potential of the hematite are more negative, the hydrophobicity of quartz increases.…”