Reverse cationic flotation is currently the main processing technique for upgrading fine hematite from silicates. Flotation is known as an efficient method of mineral enrichment that deals with possibly hazardous chemicals. Thus, using eco-friendly flotation reagents for such a process is an emerging need for sustainable development and green transition. As an innovative approach, this investigation explored the potential of locust bean gum (LBG) as a biodegradable depressant for the selective separation of fine hematite from quartz through reverse cationic flotation. Various flotation conditions (micro and batch flotation) were conducted, and the mechanisms of LBG adsorption have been examined by different analyses (contact angle measurement, surface adsorption, zeta potential measurements, and FT-IR analysis). The micro flotation outcome indicated that the LBG could selectively depress hematite particles with negligible effect on quartz floatability. Flotation of mixed minerals (hematite and quartz mixture in various ratios) indicated that LGB could enhance separation efficiency (hematite recovery > 88%). Outcomes of the surface wettability indicated that even in the presence of the collector (dodecylamine), LBG decreased the hematite work of adhesion and had a slight effect on quartz. The LBG adsorbed selectively by hydrogen bonding on the surface of hematite based on various surface analyses.

Micaceous minerals, known as layer silicates, are counted mostly as the gangue minerals associated with valuable minerals, especially iron oxides. They mainly reject through the reverse flotation process using the cationic collectors, e.g., ether amines, to improve process sustainability. Although ether amines have been applied for floating the wide range of silicates, few investigations explored their adsorption behaviors on the micaceous minerals. In this study, flotation of phlogopite, biotite, and quartz (for comparison purposes) in the presence of Flotigam^®EDA (EDA) (commercial ether monoamine collector), at pH 10 was investigated through the single mineral micro–flotation experiments. Adsorption behaviors were explored by the contact angle, residual surface tension measurements, and zeta potential analyses. Micro–flotation outcomes indicated that the quartz floatability was more than phlogopite and biotite. In the presence of 30 mg/dm³ EDA, their recoveries were 97.1, 46.3, and 63.8%, respectively. Increasing EDA concentration made a substantial increase in micaceous minerals’ floatability. Adsorption assessments confirmed that increasing the EDA concentration resulted in higher adsorption of EDA onto the surface of micaceous minerals than the quartz (all by physical adsorption). Such a behavior could be related to the nature of micaceous minerals, including their layer structure and low hardness.

Demand for high-quality iron concentrate is significantly increasing around the world. Thus, the development of the techniques for a selective separation and rejection of typical associated minerals in the iron oxide ores, such as phosphorous minerals (mainly apatite group), is a high priority. Reverse anionic flotation by using sodium silicate (SS) as an iron oxide depressant is one of the techniques for iron ore processing. This investigation is going to present a synthesized reagent “sodium co-silicate (SCS)” for hematite depression through a reverse anionic flotation. The main hypothesis is the selective depression of hematite and, simultaneously, modification of the pulp pH by SCS. Various flotation experiments, including micro-flotation, and batch flotation of laboratory and industrial scales, were conducted in order to compare the depression selectivity of SS versus SCS. Outcomes of flotation tests at the different flotation scales demonstrated that hematite depression by SCS is around 3.3% higher than by SS. Based on flotation experiment outcomes, it was concluded that SCS can modify the pH of the process at ~9.5, and the plant reagents (including NaOH, Na₂CO₃, and SS gel) can be replaced by just SCS, which can also lead to a higher efficiency in the plant.