Enhancement of Flotation Performance of Oxidized Coal by the Mixture of Laurylamine Dipropylene Diamine and Kerosene

Conventional hydrocarbon oil cannot adhere effectively to oxidized coal, resulting in a low yield of clean coal. In this study, a high-speed homogenizer was used to emulsify LDD (laurylamine dipropylene diamine) and kerosene, which enhanced the flotation efficiency of oxidized coal. The flotation results showed an increase from 4.12% (only kerosene) to 23.33% (emulsified oil). An increase in contact angle indicated that the mixture reagent can increase the hydrophobicity of coal particles, which is attributed to the adsorption of LDD onto the coal particle surface and the decrease of the oil droplet A lower surface tension of LDD allows it to produce a stable layer of froth than the layer generated by kerosene alone.

Effects of Pyrite Texture on Flotation Performance of Copper Sulfide Ores

Pyrite particles, having framboidal/altered texture, are known to significantly affect pulp chemistry and adversely affect flotation performance. Therefore, the main objectives of this study were to demonstrate influence of pyrite mineralogy on the flotation of copper (sulphidic) ores and develop alternative conditions to improve the performance. Two copper ore samples (Ore A and Ore B) having different textural/modal mineralogy and flotation characteristics were taken from different zones of the same ore deposit. Ore B contained framboidal pyrite and altered pyrite/marcasite, which is considered the main reason for the low flotation performance in both copper and pyrite flotation sections of the process plant. Flotation tests were conducted under different conditions using the two ore samples and a 50:50 blend. The results showed that Ore A could be concentrated under the base conditions, as applied in the existing flotation plant. On the other hand, Ore B did not respond to the base conditions and a copper recovery of only 5% could be obtained. Besides, blending Ore B with Ore A negatively affected the flotation behavior of Ore A. An alternative flotation chemistry was applied on Ore B using Na2S for surface cleaning and Na-Metabisulfite (MBS) for pyrite depression in the copper flotation stage. The surface cleaning reduced the rate of oxidation of the framboidal pyrite in Ore B. As a result, the copper recovery could be increased to 52% Cu for Ore B, and 65% for the mixed ore sample.

Flotation of Carbonaceous Matter from a Double Refractory Gold Ore: The Effect of MIBC on Flotation Performance and Kinetics

The use of alkaline pressure oxidation to pretreat refractory gold ore often results in insufficient gold recovery (<60%) in downstream thiosulfate leaching. To improve gold recovery, flotation was considered for the separation of carbonaceous matter (C-matter). In this study, the effect of MIBC on C-matter flotation was investigated to understand the role of the frother in bubble and froth formation and on flotation kinetics. MIBC dosages between 30 and 150 g/t were used in combination with 500 g/t of kerosene as a collector. The results showed that the recovery and selectivity of C-matter were improved with increasing MIBC dosages. Improved selectivity at higher MIBC dosages was attributed to faster C-matter recovery as bubble size decreased to the critical coalescence concentration (CCC) and to changes to the foam structure. Analysis of flotation kinetics showed that the flotation rate increased as the MIBC dosage increased due to the decreasing bubble size and the reduced induction time caused by the interaction between the collector and the frother. The results of this study explain the role of MIBC in C-matter flotation and can be used as a design basis for scavenger-cleaner flotation testing. Overall, the results show the potential for flotation as a means to improve gold recovery in thiosulfate leaching through the removal of C-matter.

A Rational Interpretation of the Role of Turbulence in Particle-Bubble Interactions

Interactions between particles and bubbles have been cornerstone for the successful applications of froth flotation to the beneficiations of minerals or coal. Particle-bubble interactions are highly physio-chemical processes on the basis of surface science and hydrodynamics. Though these two aspects are deeply interwoven, we focus on the discussions of the effects of turbulence on the interactions between particles and bubbles, i.e., collision, attachment and detachment. It has to be mentioned this effect is not working in one direction and can affect flotation performance in a complicated way. Only when turbulence effects are well understood, flotation processes can be optimised by suitably changing equipment structure or operating parameters. The aim of this paper is to review the most recent progresses in this aspect and to identify the future development in successfully considering turbulence effects on flotation processes.

Zinc Recovery from Wulagen Sulfide Flotation Plant Tail by Applying Ether Amine Organic Collectors

Separating oxidized zinc minerals from flotation tailings is always a challenge. In this study, a flotation tailing from Wulagen zinc mine in China (Zn grade < 1%) was processed using froth flotation with combinations of amines (OPA 10, OPA 1214, OPA 13, DDA) and Na2S to study the effects of these amines on the zinc recovery as well as their interactions with other reagents, aiming to screen out a proper reagent scheme to improve zinc separation from extremely low-grade zinc flotation tailings. The results show that different amines led to different flotation performance, and the collectors were ranked as OPA 1214, OPA 13, OPA 10 and DDA in a decreasing order based on flotation collectivity and selectivity. An increase in the concentration of each collector increased the zinc recovery but reduced the concentrate zinc grade. Interactions were also observed between different amines and Na2S and Na2SiO3, and OPA 1214 outdid the others in saving the usage of both the Na2S and Na2SiO3. The measured adsorption of collector onto smithsonite was found to correlate well with flotation test results. It was concluded that hydrocarbon chains can be held accountable for the difference in the flotation performance with different amines. The longer the hydrocarbon chain, the stronger the hydrophobic association ability of amine, which is conducive to the selective amine adsorption onto sulfurized smithsonite particles and hence the smithsonite flotation.