Selective Separation of Hematite by a Synthesized Depressant in Various Scales of Anionic Reverse Flotation

Abstract

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.

A comparative study between the adsorption mechanisms of sodium co-silicate and conventional depressants for the reverse anionic hematite flotation

“…Since CaO exists in the chemical composition of SCS, minor activation of quartz's surface is expected. [16] Nevertheless, it can be concluded that the depressant adsorptions on the quartz's surface have no significant effect on its flotation behavior. Although in the RAF, due to the quartz's negative surface charge, it is not expected that its particles floated with the anionic collector, micro-flotation tests indicate around 21% of quartz particles are floated.…”

“…The SCS is a modified SS, but unlike the SS gel, it is in the form of solid white powder. [16] NaOH (analytical grade) solution was used to modify the pH value (around 9.5) of the flotation pulp and also gelatinization of starch (at a ratio of 5:1). For the flotation tests in the presence of SCS, no pH modifier was added since SCS can play both pH modifier and depressant roles.…”

“…For the flotation tests in the presence of SCS, no pH modifier was added since SCS can play both pH modifier and depressant roles. [16] Distilled water was employed for all the experiments.…”

“…[31] Recently, Tohry et al (2019) indicated that sodium co-silicate (SCS) as a modified SS could be considered for the industrial RAF separation of hematite from fluorapatite. [16] However, SCS interactions on the surface of hematite, quartz, and fluorapatite have not been investigated yet. This work aims to clarify the mechanism of starch, dextrin, SS, and SCS adsorptions on these mineral surfaces as an original investigation.…”

Effect of Ether Mono Amine Collector on the Cationic Flotation of Micaceous Minerals—A Comparative Study

“…Mineral flotation separation, as a physicochemical process, is a well-known technique for the purification of target minerals which become finely liberated (mainly +25-100 micron) [1,2]. Currently, froth flotation is globally considered for processing various finely disseminated minerals (sulphides [3][4][5][6], oxides [7][8][9][10][11][12], silicates [7,8,10,12], phosphates [7,13,14], etc). In direct flotation, target minerals are floated, whereas in reverse flotation, valuable minerals are sunk, and gangue minerals are rejected in the froth phase [1,2].…”