Flotation separation of barite from calcite using acidified water glass as the depressant

Flotation Separation of Fluorite from Calcite using an Efficient Depressant Nitrilotriacetic Acid in the NaOL System

Fluorite and calcite were separated with nitrilotriacetic acid (NTA) as a depressant. The single mineral flotation experiment confirmed that with 40 mg/L NaOL and 80 mg/L NTA, the fluorite recovery and calcite recovery were 24.37 and 94.13%, respectively, at pH 9. Meanwhile, in the fluorite-calcite binary mixed ore flotation experiment, the calcite recovery and fluorite recovery were 75.50 and 26.84%, respectively, and the CaCO3 and CaF2 grade in concentrate was 74.32 and 25.61%, respectively. The results confirmed that NTA could be used as a depressant to selectively inhibit fluorite flotation. The mechanism study illustrated that NTA was selectively reacted with fluorite by chemical interaction between O of NTA and Ca of fluorite. The adsorption of NTA on fluorite will impede the interaction between fluorite and NaOL. NTA could adsorb on fluorite in three ways, while the dominant two ways were the complex between double O of NTA and Ca of fluorite in a vertical model and the complex between double O of NTA and Ca of fluorite in a horizontal model.

Impact of Solution {Ba2+}:{SO42-} on Charge Evolution of Forming and Growing Barite (BaSO4) Crystals: A ζ-Potential Measurement Investigation

The impact of solution stoichiometry on formation of BaSO4 (barite) crystals and the development of surface charge was investigated at various predefined stoichiometries (raq = 0.01, 0.1, 1, 10, and 100, where raq = {Ba2+}:{SO42-}). Synthesis experiments and zeta potential (ζ-potential) measurements were conducted at a fixed initial degree of supersaturation (Ωbarite = 1000, where Ωbarite = {Ba2+}{SO42-}/Ksp), at circumneutral pH of ∼6, 0.02 M NaCl, and ambient temperature and pressure. Mixed-mode measurement-phase analysis light scattering (M3-PALS) showed that the particles stayed negative for raq < 1 during barite crystal formation and positive for raq > 1. At raq = 1, two populations with a positive or negative ζ-potential prevailed for ∼2.5 h before a population with a circumneutral ζ-potential (-10 to +10 mV) remained. We relate the observations of particle charge evolution to particle size and morphology evolution under the experimental conditions. Furthermore, we showed that the ζ-potential became more negative when the pH was increased for every raq. In addition, our results demonstrated that the type of monovalent background electrolyte did not influence the ζ-potential of barite crystals significantly, although NaCl showed slightly different behavior compared to KCl and NaNO3. Our results show the important role of surface charge (evolution) during ionic crystal formation under nonstoichiometric conditions. Moreover, our combined scanning electron microscopy and ζ-potential results imply that the surface charge during particle formation can be influenced by solution stoichiometry, besides the pH and ionic strength, and may aid in predicting the fate of barite in environmental settings and in understanding and improving industrial barite (surface chemistry) processes.

Efficient removal of NaOl from mineral processing wastewater using Al-electrocoagulation

Sodium oleate (NaOl) is widely used as collector for oxidised ore flotation, and residual NaOl in mineral processing wastewater is a serious threat to mine environment. In this work, the feasibility of electrocoagulation (EC) as an alternative for chemical oxygen demand (COD) removal from NaOl-containing wastewater was demonstrated. Major variables were evaluated to optimise EC, and related mechanisms were proposed to interpret the observations in EC experiments. The initial pH of the wastewater greatly affected the COD removal efficiency, which was likely to be related to the variation of predominant species. When the pH was below 8.93 (original pH), liquid HOl_(l) was the predominant specie, which could be rapidly removed by EC thought charge neutralisation and adsorption. At original pH or higher, Ol^- could react with dissolved Al³⁺ to form insoluble Al(Ol)₃, which was subsequently removed through charge neutralisation and adsorption. The presence of fine mineral particles could reduce repulsion force of the suspended solids and promote flocculation, whereas the presence of water glass had an opposite effect. These results demonstrated that EC can be employed as an effective process to purify NaOl-containing wastewater. This study will contribute to deepening our understanding of EC technology for NaOl removal and provide useful information to researchers in mineral processing industry.

Investigation of the Flotation Separation of Scheelite from Fluorite with a Novel Chelating Agent: Pentasodium Diethylenetriaminepentaacetate

The recovery of scheelite from calcium-bearing carbonate ores by foam flotation is challenging due to its low separation efficiency. This study investigated the effect of pentasodium diethylenetriaminepentaacetate (PD) on the surface properties of scheelite and fluorite. For this purpose, we performed micro-flotation tests and carried out zeta potential measurements, as well as Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) spectroscopic measurements, in order to analyze the surface properties of these minerals. The addition of PD as a novel depressor significantly improved the effect of fluorite and sodium oleate (NaOl) on the flotation-based scheelite recovery and separation from fluorite. PD was spontaneously adsorbed onto fluorite through electrostatic and chemical adsorption. By contrast, PD did not appear on the scheelite because of the reaction conditions, surface site, and steric hindrance. X-ray photoelectron spectroscopy measurements and a solution chemistry analysis were used for the determination of the PD-selective adsorption mechanism and key factors derived from multi-layer adsorption onto fluorite, which completely hindered that of NaOl.

Barite as an industrial mineral in Nigeria: occurrence, utilization, challenges and future prospects

Barite is a non-metallic mineral which is simply barium sulfate (BaSO₄) and is largely used by the oil and gas industry as a weighting agent in drilling mud during drilling operations. The specific gravity of barite should range from 4.1 to 4.6 to be applicable as a drilling mud additive. This study considered the occurrence, utilization and challenges facing the mining of barite in Nigeria. It also discussed the global reserve, production and consumption of barite and types of barite ores and associated minerals in Nigeria. With the use of data from various ministries, departments and agencies involved in the records of operations within the Nigerian solid minerals sector, the nature of occurrence of barite in Nigeria has been reviewed. The various reported deposits areas have been elucidated while the associated minerals along with the quality reserve estimates have been discussed. Reported geochemical and geological studies of the barite mineralization in Nigeria show cream to grey, reddish-brown, whitish and pinkish varieties. The quality of the Nigerian barite is moderate to high. It is often associated with dolomite, fluorite, quartz, calcite, etc. The major impurities found in the mineral are iron oxide (goethite), quartz, and carbonates of magnesium, iron and calcium. Enumeration of the challenges facing the exploitation of the mineral has been revealed to include poor infrastructural development, safety and security, insufficient geophysical and geoscience data information and crude mining techniques. The barite production industry still has a huge potential for growth if these challenges are addressed.

Effects and Mechanisms of Grinding Media on the Flotation Behavior of Scheelite

Grinding, an essential procedure for size reduction and fresh surface exposure of mineral particles, plays an important role in mineral flotation. The grinding media are the key factors for effective grinding and thus for successful flotation. In this study, ceramic ball (CB) and cast iron ball (CIB), two representative grinding media, were chosen to investigate the effects and mechanisms of grinding media on the flotation behavior of scheelite. The results of pure scheelite flotation show that scheelite ground by CB has a better floatability than that ground by CIB. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analyses indicate that there are Fe species, namely, elemental iron (Fe), ferrous oxide (FeO), and iron oxyhydroxide (FeOOH), coated on the surfaces of scheelite ground by CIB but not in the case of scheelite ground by CB. The dissolved oxygen (DO) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) tests show that Fe ions exist in the CIB grinding slurry but not in the case of CB grinding slurry. Compared with the CB grinding slurry, the CIB grinding slurry has a lower DO content and higher Ca ion concentration. Zeta potential results reveal that the Fe species in the CIB grinding reduce the NaOl adsorption on the scheelite surfaces. Finally, the deleterious effect of CIB grinding on the flotation behavior of scheelite is verified by the actual scheelite ore flotation experiments.

The Potential Role of Colloidal Silica as a Depressant in Scheelite Flotation

The main challenge in scheelite flotation lies in the contamination of the concentrate by other calcium-bearing minerals, mainly calcite. To remedy this problem, sodium silicate is frequently used as a depressant. According to the literature, one hypothesis for the mechanism of water glass consists in its absorption onto calcite through colloidal silica formation, preventing hydrophobization by the collector. This short communication presents research conducted on the direct use of colloidal silica as a depressant in scheelite flotation. Colloidal silica is shown to have an impact on scheelite flotation, especially by depressing silicates.